Altered levels of lymphocyte enhancer-binding factor-1 modulates the pigmentation in acral and non-acral lesions of non-segmental vitiligo patients: a follow-up-based study in North India

BACKGROUND

Lymphocyte enhancer-binding factor-1 (LEF1) is responsible for melanocyte proliferation, migration and differentiation and its downregulation may result in depigmentation in vitiligo. Narrowband UVB (NB-UVB) phototherapy is known to enhance melanocyte migration from hair follicles to lesional epidermis; hence, it may have a role in the upregulation of LEF1.

OBJECTIVES

We intended to assess the expression of LEF1 both before and after NB-UVB therapy and correlate it with the extent of re-pigmentation.

MATERIALS AND METHODS

In this prospective cohort study, 30 patients of unstable non-segmental vitiligo were administered NB-UVB phototherapy for 24 weeks. Skin biopsies were obtained from acral and non-acral sites in all patients, both prior to initiation and after completion of phototherapy and LEF1 expression was measured.

RESULTS

Amongst the 16 patients who completed the study, at 24 weeks, all patients achieved > 50% re-pigmentation. However, > 75% re-pigmentation was achieved in only 11.1% of acral patches, whereas it was achieved in a significantly higher number of non-acral patches (66.6%) (p = 0.05). A significant increase was observed in the mean fluorescent intensity of the LEF1 gene in both acral as well as non-acral areas at 24 weeks as compared to baseline (p = 0.0078), However, no difference was observed between acral and non-acral lesions in the LEF1 expression at 24 weeks or the change in LEF1 expression from baseline.

CONCLUSION

LEF1 expression modulates the re-pigmentation of vitiligo lesions after treatment with NBUVB phototherapy.

Effect of Fish Bone Bioactive Peptides on Oxidative, Inflammatory and Pigmentation Processes Triggered by UVB Irradiation in Skin Cells

In the present study, we evaluated for the first time the photoprotective effect of fish bone bioactive peptides (FBBP) preparation isolated from silver carp (Hypophthalmichthys molitrix) discarded tissue using in vitro experimental models of skin cells exposed to ultraviolet B (UVB) irradiation and stressing agents. FBBP preparation was obtained by papain treatment of minced bones and centrifugal ultrafiltration, and the molecular weight (MW) distribution was characterized by size exclusion and reversed-phase high performance liquid chromatography (RP-HPLC). In vitro assessment of the effect of FBBP pretreatment in UVB-irradiated L929 fibroblasts and HaCaT keratinocytes revealed their cytoprotective activity. Their capacity to efficiently reduce reactive oxygen species (ROS) production and lipid peroxidation varied in a dose-dependent manner, and it was greater in fibroblasts. A decrease of proinflammatory cytokines secretion, in particular of tumor necrosis factor alpha (TNF-α), was found after FBBP pretreatment of THP-1-derived inflamed macrophages. Melanin production and tyrosinase activity investigated in UVB-irradiated Mel-Juso cells were lowered in direct relation to FBBP concentrations. FBBP fractions with high radical scavenging activity were separated by ion exchange chromatography, and two collagenic sequences were identified. All these results offer new scientific data on aquaculture fish bone-derived peptides confirming their ability to control the antioxidant, anti-inflammatory and pigmentation processes developed during UV irradiation of skin cells and recommend their use as valuable natural ingredients of photoprotective cosmeceutical products.

Intense Pulsed Light Attenuates UV-Induced Hyperimmune Response and Pigmentation in Human Skin Cells

The skin of an organism is affected by various environmental factors and fights against aging stress via mechanical and biochemical responses. Photoaging induced by ultraviolet B (UVB) irradiation is common and is the most vital factor in the senescence phenotype of skin, and so, suppression of UVB stress-induced damage is critical. To lessen the UVB-induced hyperimmune response and hyperpigmentation, we investigated the ameliorative effects of intense pulsed light (IPL) treatment on the photoaged phenotype of skin cells. Normal human epidermal keratinocytes and human epidermal melanocytes were exposed to 20 mJ/cm² of UVB. After UVB irradiation, the cells were treated with green (525–530 nm) and yellow (585–592 nm) IPL at various time points prior to the harvest step. Subsequently, various signs of excessive immune response, including expression of proinflammatory and melanogenic genes and proteins, cellular oxidative stress level, and antioxidative enzyme activity, were examined. We found that IPL treatment reduced excessive cutaneous immune reactions by suppressing UVB-induced proinflammatory cytokine expression. IPL treatment prevented hyperpigmentation, and combined treatment with green and yellow IPL synergistically attenuated both processes. IPL treatment may exert protective effects against UVB injury in skin cells by attenuating inflammatory cytokine and melanogenic gene overexpression, possibly by reducing intracellular oxidative stress. IPL treatment also preserves antioxidative enzyme activity under UVB irradiation. This study suggests that IPL treatment is a useful strategy against photoaging, and provides evidence supporting clinical approaches with non-invasive light therapy.

Melanopsin mediates UVA-dependent modulation of proliferation, pigmentation, apoptosis, and molecular clock in normal and malignant melanocytes

Cutaneous melanocytes and melanoma cells express several opsins, of which melanopsin (OPN4) detects temperature and UVA radiation. To evaluate the interaction between OPN4 and UVA radiation, normal and malignant Opn4WT and Opn4KO melanocytes were exposed to three daily low doses (total 13.2 kJ/m2) of UVA radiation. UVA radiation led to a reduction of proliferation in both Opn4WT cell lines; however, only in melanoma cells this effect was associated with increased cell death by apoptosis. Daily UVA stimuli induced persistent pigment darkening (PPD) in both Opn4WT cell lines. Upon Opn4 knockout, all UVA-induced effects were lost in three independent clones of Opn4KO melanocytes and melanoma cells. Per1 bioluminescence was reduced after 1st and 2nd UVA radiations in Opn4WT cells. In Opn4KO melanocytes and melanoma cells, an acute increase of Per1 expression was seen immediately after each stimulus. We also found that OPN4 expression is downregulated in human melanoma compared to normal skin, and it decreases with disease progression. Interestingly, metastatic melanomas with low expression of OPN4 present increased expression of BMAL1 and longer overall survival. Collectively, our findings reinforce the functionality of the photosensitive system of melanocytes that may subsidize advancements in the understanding of skin related diseases, including cancer.

Floral Pigmentation Has Responded Rapidly to Global Change in Ozone and Temperature

Across kingdoms, organisms ameliorate UV stress by increasing UV-absorbing pigmentation. Rapid ozone degradation during the 20^th century resulted in elevated UV incidence, but pigmentation responses to this aspect of global change have yet to be demonstrated. In flowering plants, UV exposure favors larger areas of UV-absorbing pigmentation on petals, which protects pollen from UV-damage. Pigmentation also affects floral thermoregulation, suggesting climate warming may additionally impact pigmentation. We used 1,238 herbarium specimens collected from 1941 to 2017 to test whether change in UV floral pigmentation was associated with altered ozone and temperature in 42 species spanning three continents. We tested three predictions: first, UV-absorbing pigmentation will increase temporally and be correlated with reduced ozone (higher UV) when accounting for effects of temperature; second, taxa that experienced larger ozone declines will display larger increases in pigmentation; and third, taxa with anthers exposed to ambient UV will respond more strongly than those with anthers protected by petals. Globally, the extent of petal UV pigmentation increased significantly across taxa by ∼2% per year. However, temporal change was species specific-increasing in some taxa but declining in others. Species with exposed anthers experiencing larger declines in ozone displayed more dramatic pigmentation increases. For taxa with anthers enclosed within petals, pigmentation declined with increases in temperature, supporting a thermoregulatory role of UV pigmentation. Results document a rapid phenotypic response of floral pigmentation to anthropogenic climatic change, suggesting that global change may alter pollination through its impact on floral color, with repercussions for plant reproductive fitness.

Phenotypic, Phytochemical, and Transcriptomic Analysis of Black Sorghum (Sorghum bicolor L.) Pericarp in Response to Light Quality

Black sorghum [Sorghum bicolor (L.) Moench] is characterized by the black appearance of the pericarp and production of 3-deoxyanthocyanidins (3-DOA), which are valued for their cytotoxicity to cancer cells and as natural food colorants and antioxidant additives. The black pericarp phenotype is not fully penetrant in all environments, which implicates the light spectrum and/or photoperiod as the critical factor for trait expression. In this study, black- or red-pericarp genotypes were grown under regimes of visible light, visible light supplemented with UVA or supplemented with UVA plus UVB (or dark control). Pericarp 3-DOAs and pericarp pigmentation were maximized in the black genotype exposed to a light regime supplemented with UVB. Changes in gene expression during black pericarp development revealed that ultraviolet light activates genes related to plant defense, reactive oxygen species, and secondary metabolism, suggesting that 3-DOA accumulation is associated with activation of flavonoid biosynthesis and several overlapping defense and stress signaling pathways.

The effects of chromatic lights on body color and gene expressions of melanin-concentrating hormone and proopiomelanocortin in goldfish (Carassius auratus)

In the present study, the effects of photic environments, such as background color (white and black) and chromatic lights (blue, green, and red), on body color and gene expressions of melanin-concentrating hormone (mch) in the brain and proopiomelanocortin (pomc) in the pituitary, as well as the roles of the eyes and brain as mediators of ambient light to these genes, were examined in goldfish (Carassius auratus). Body color of goldfish exposed to fluorescent light (FL) under white background (WBG) was paler than those under black background (BBG). Gene expression levels for mch and pomc were reciprocally different depending on background color; under WBG, mRNA levels of mch and pomc were high and low, respectively, while under BBG, these levels were reversed. mch and pomc mRNA expressions of the fish exposed to chromatic light from LED were primarily similar to those exposed to FL, while blue light stimulated the expressions of mch and pomc. Ophthalmectomized goldfish exposed to FL or blue light showed minimum expression levels of mch gene, suggesting that eyes are the major mediator of ambient light for mch gene expression. Contrastingly, mRNA expressions of pomc in ophthalmectomized goldfish exposed to FL were different from those of intact goldfish. These results suggest that eyes play a functional role in mediating ambient light to regulate pomc gene expression. Since ophthalmectomy caused an increase in pomc mRNA contents in the fish exposed to blue light, we suggest that the brain is an additional mediator to regulate pomc gene expression.

Differential color development and response to light deprivation of fig (Ficus carica L.) syconia peel and female flower tissues: transcriptome elucidation

BACKGROUND

Color directly affects fruit quality and consumer preference. In fig syconia, the female flower tissue is contained in a receptacle. Anthocyanin pigmentation of this tissue and the peel differs temporally and spatially. A transcriptome study was carried out to elucidate key genes and transcription factors regulating differences in fig coloring.

RESULTS

Anthocyanins in the female flower tissue were identified mainly as pelargonidin-3-glucoside and cyanidin-3-rutinoside; in the peel, the major anthocyanins were cyanidin 3-O-glucoside and cyanidin-3-rutinoside. Anthocyanin content was significantly higher in the female flower tissue vs. peel before fig ripening, whereas at ripening, the anthocyanin content in the peel was 5.39 times higher than that in the female flower tissue. Light-deprivation treatment strongly inhibited peel, but not female flower tissue, anthocyanin pigmentation. RNA-Seq revealed 522 differentially expressed genes (recruited with criteria log₂ ≥ 2 and P < 0.05) at fig ripening, with 50 upregulated and 472 downregulated genes in the female flower tissue. Light deprivation upregulated 1180 and downregulated 856 genes in the peel, and upregulated 909 and downregulated 817 genes in the female flower tissue. KEGG enrichment revealed significantly changed expression in the phenylpropanoid-biosynthesis and flavonoid-biosynthesis pathways in the peel, but not in the female flower tissue, with significant repression of FcCHS, FcCHI, FcF3H, FcF3'H, FcDFR and FcUFGT transcripts. Light deprivation led to differential expression of 71 and 80 transcription factor genes in the peel and female flower tissue, respectively. Yeast one-hybrid screen revealed that FcHY5 and FcMYB114 bind the promoter regions of FcCHS and FcDFR, respectively in the flavonoid-biosynthesis pathway.

CONCLUSIONS

Phenylpropanoid- and flavonoid-biosynthesis pathways were differentially expressed spatially and temporally in the peel and female flower tissue of fig syconia; pathway expression in the peel was strongly regulated by light signal. Differentially expressed transcription factors were recruited as candidates to screen important expression regulators in the light-dependent and light-independent anthocyanin-synthesis pathway. Our study lays the groundwork for further elucidation of crucial players in fig pigmentation.

Photoprotection enhanced by red cell wall pigments in three East Antarctic mosses

BACKGROUND

Antarctic bryophytes (mosses and liverworts) are resilient to physiologically extreme environmental conditions including elevated levels of ultraviolet (UV) radiation due to depletion of stratospheric ozone. Many Antarctic bryophytes synthesise UV-B-absorbing compounds (UVAC) that are localised in their cells and cell walls, a location that is rarely investigated for UVAC in plants. This study compares the concentrations and localisation of intracellular and cell wall UVAC in Antarctic Ceratodon purpureus, Bryum pseudotriquetrum and Schistidium antarctici from the Windmill Islands, East Antarctica.

RESULTS

Multiple stresses, including desiccation and naturally high UV and visible light, seemed to enhance the incorporation of total UVAC including red pigments in the cell walls of all three Antarctic species analysed. The red growth form of C. purpureus had significantly higher levels of cell wall bound and lower intracellular UVAC concentrations than its nearby green form. Microscopic and spectroscopic analyses showed that the red colouration in this species was associated with the cell wall and that these red cell walls contained less pectin and phenolic esters than the green form. All three moss species showed a natural increase in cell wall UVAC content during the growing season and a decline in these compounds in new tissue grown under less stressful conditions in the laboratory.

CONCLUSIONS

UVAC and red pigments are tightly bound to the cell wall and likely have a long-term protective role in Antarctic bryophytes. Although the identity of these red pigments remains unknown, our study demonstrates the importance of investigating cell wall UVAC in plants and contributes to our current understanding of UV-protective strategies employed by particular Antarctic bryophytes. Studies such as these provide clues to how these plants survive in such extreme habitats and are helpful in predicting future survival of the species studied.

Ultraviolet exposure has an epigenetic effect on a Batesian mimetic trait in the butterfly Papilio polytes

Wing polymorphism of butterflies provides a good system in which to study adaptation. The Asian Batesian mimic butterfly Papilio polytes has unmelanized, putative mimetic red spots on its black hind wings. The size of those red spots is non-heritable but it is highly polymorphic, the adaptive significance of which is unknown. We hypothesized that under strong ultraviolet (UV) irradiation, butterflies develop a wider melanized black area to protect the wings from UV damage, and as a result express smaller mimetic red spots. Our field survey on Okinawa Island revealed a negative relationship between the sizes of the red spot and the black area in the wings. The size varied seasonally and was negatively correlated with the intensity of solar UV radiation at the time of capture. Laboratory experiments revealed that the size was reduced by strong UV irradiation not only of the eggs and larvae, but also of their mothers through a putative epigenetic mechanism. The flexible phenotypic expression of the red spots in P. polytes suggests a trade-off between protection against UV damage and predation avoidance, and provides a new insight into the evolution of Batesian mimicry.

Influence of light intensity on chloroplast development and pigment accumulation in the wild-type and etiolated mutant plants of Anthurium andraeanum 'Sonate'

Seedlings of wild-type and etiolate mutant plants of Anthurium andraeanum cultivar 'Sonate' were treated for 15 d with different light intensities (20, 100, and 400 µmol·m^-2·s^-1) to analyze leaf plastid development and pigment content. Significant changes appeared in treated seedlings, including in leaf color, plastid ultrastructure, chloroplast development gene AaGLK expression, chlorophyll and anthocyanin contents, and protoplast shape. Wild-type and etiolated plants exhibited different plastid structures under the same light condition. The results suggest that light intensity is a crucial environmental factor influencing plastid development and leaf color formation in the A. andraeanum cultivar 'Sonate'.

Individual variation in the transmission of UVB radiation in the young adult eye

Objectives

Data obtained mostly from animal models and ex vivo samples show that a small portion of ultraviolet light (UV, 300–400 nm) penetrates the cornea and crystalline lens and impinges on the human retina. UV transmission to the retina appears to be unique to the young and some older pseudophakes. In this study, we determine the variation in UV transmission in a relatively homogenous sample of young adults.

Methods

42 subjects were tested (M = 19 ± 1.3 years). Absolute thresholds to UV radiation were collected (λmax = 315 nm, 305–325). Macular pigment optical density (MPOD, measured using heterochromatic flicker photometry) and iris color (using a standardized color scale) were also assessed as potential covariates.

Results

All of the subjects could detect UV radiation at 315 nm but individual variation was large (over a factor of 30). Higher MPOD and darker iridies were not related to UV sensitivity in this young sample. Males, however, were more sensitive to UV than the females (p<0.05).

Conclusions

The large individual differences in UV reaching the retina of younger individuals suggests equally significant vulnerability to the actinic effects of this highly energetic light.

Solar irradiation levels during simulated long- and short-term heat waves significantly influence heat survival, pigment and ascorbate composition, and free radical scavenging activity in alpine Vaccinium gaultherioides

In the 20th century, annual mean temperatures in the European Alps rose by almost 1 K and are predicted to rise further, increasing the impact of temperature on alpine plants. The role of light in the heat hardening of plants is still not fully understood. Here, the alpine dwarf shrub Vaccinium gaultherioides was exposed in situ to controlled short-term heat spells (150 min with leaf temperatures 43-49°C) and long-term heat waves (7 days, 30°C) under different irradiation intensities. Lethal leaf temperatures (LT50 ) were calculated. Low solar irradiation [max. 250 photosynthetic photon flux density (PPFD)] during short-term heat treatments mitigated the heat stress, shown by reduced leaf tissue damage and higher Fv /Fm (potential quantum efficiency of photosystem 2) than in darkness. The increase in xanthophyll cycle activity and ascorbate concentration was more pronounced under low light, and free radical scavenging activity increased independent of light conditions. During long-term heat wave exposure, heat tolerance increased from 3.7 to 6.5°C with decreasing mean solar irradiation intensity (585-115 PPFD). Long-term exposure to heat under low light enhanced heat hardening and increased photosynthetic pigment, dehydroascorbate and violaxanthin concentration. In conclusion, V. gaultherioides is able to withstand temperatures of around 50°C, and its heat hardening can be enhanced by low light during both short- and long-term heat treatment. Data showing the specific role of light during short- and long-term heat exposure and the potential risk of lethal damage in alpine shrubs as a result of rising temperature are discussed.

On the source of non-linear light absorbance in photosynthetic samples

This study presents a mathematical model, which expresses the absorbance of a photosynthetic sample as a non-linear polynomial of selected reference absorbance. The non-linearity is explained by inhomogeneities of a product of pigment concentration and light path length in the sample. The quadratic term of the polynomial reflects the extent of inhomogeneities, and the cubic term is related to deviation of the product distribution from a symmetric one. The model was tested by measurements of suspension of unstacked tobacco thylakoid membranes of different chlorophyll concentrations in cuvettes of different thicknesses. The absorbance was calculated from the diffuse transmittance and reflectance of sample, illuminated by perpendicular collimated light. The evaluated quantity was a sensitivity defined as the relative difference between the sample absorbance and the reference absorbance to the reference absorbance. The non-linearity of sample absorbance was demonstrated by a characteristic deviation of the sensitivity spectrum from a constant value. The absorbance non-linearity decreased on an increase of the product of pigment concentration and cuvette thickness. The model suggests that the sieve and detour effects influence the absorbance in a similar way. The model may be of interest in modeling of leaf or canopy optics including light absorption and scattering.

Effect of shading and light recovery on the growth, leaf structure, and photosynthetic performance of soybean in a maize-soybean relay-strip intercropping system

Intercropping is an important agronomic practice adopted to increase crop production and resource efficiency in areas with intensive agricultural production. Two sequential field trials were conducted in 2015-2016 to investigate the effect of shading on the morphological features, leaf structure, and photosynthetic characteristics of soybean in a maize-soybean relay-strip intercropping system. Three treatments were designed on the basis of different row configurations A1 ("50 cm + 50 cm" one row of maize and one row of soybean with a 50 cm spacing between the rows), A2 ("160 cm + 40 cm" two rows of maize by wide-narrow row planting, where two rows of soybean were planted in the wide rows with a width of 40 cm, and with 60 cm row spacing was used between the maize and soybean rows), and CK (sole cropping of soybean, with 70 cm rows spacing). Results showed that the photosynthetically active radiation transmittances of soybean canopy at V5 stage under A2 treatment (31.1%) were considerably higher than those under A1 (8.7%) treatment, and the red-to-far-red ratio was reduced significantly under A1 (0.7) and A2 (1.0) treatments compared with those under CK (1.2). By contrast with CK, stem diameter, total aboveground biomass, chlorophyll content and net photosynthetic rate decreased significantly except plant height under A1 and A2. The thickness of palisade tissue and spongy tissue of soybean leaf under A1 and A2 were significantly reduced at V5 stage compared with CK. The leaf thicknesses under A1 and A2 were lower than those in CK by 39.5% and 18.2%, respectively. At the R1 stage of soybean (after maize harvest), the soybean plant height, stem biomass, leaf biomass and petiole biomass under A1 and A2 treatments were still significantly lower than those under CK, but no significant differences were observed in Chl a/b, Pn, epidermis thickness and spongy tissue thickness of soybean leaves in A2 compared with CK. In addition, the soybean yields (g plant-1) under A1 and A2 were 54.69% and 16.83% lower than those in CK, respectively. These findings suggested that soybean plants can regulate its morphological characteristics and leaf anatomical structures under different light environments.

Geographic variation in pollen color is associated with temperature stress

The evolution of flower color, especially petal pigmentation, has received substantial attention. Less understood is the evolutionary ecology of pollen pigmentation, though it varies among and within species and its biochemical properties affect pollen viability. We characterize the distribution of pollen color across 24 populations of the North American herb Campanula americana, and assess the degree to which this variation is genetically based. We identify abiotic factors that covary with pollen color and test whether germination of light and dark pollen is differentially affected by variable temperature and UV. Pollen color varies from white to deep purple in C. americana and is genetically determined. There was a longitudinal cline whereby pollen was darkest in western populations. Accounting for latitudinal variation, western populations experience elevated temperature and UV irradiance. Germination of light-colored pollen was reduced by 60% under high temperature, but dark pollen was unaffected. Exposure to UV reduced germination of light and dark pollen similarly. The cline in pollen color across the range may reflect adaptation to heat stress. This study supports thermal tolerance as a novel function of pollen pigmentation and contributes to growing evidence that abiotic factors can drive floral diversity.

Engineering RGB color vision into Escherichia coli

Optogenetic tools use colored light to rapidly control gene expression in space and time. We designed a genetically encoded system that gives Escherichia coli the ability to distinguish between red, green, and blue (RGB) light and respond by changing gene expression. We use this system to produce 'color photographs' on bacterial culture plates by controlling pigment production and to redirect metabolic flux by expressing CRISPRi guide RNAs.

Seeing new light: recent insights into the occurrence and regulation of chromatic acclimation in cyanobacteria

Cyanobacteria exhibit a form of photomorphogenesis termed chromatic acclimation (CA), which involves tuning metabolism and physiology to external light cues, with the most readily recognized acclimation being the alteration of pigmentation. Historically, CA has been represented by three types that occur in organisms which synthesize green-light-absorbing phycoerythrin (PE) and red-light-absorbing phycocyanin (PC). The distinct CA types depend upon whether organisms adjust levels of PE (type II), both PE and PC (type III, also complementary chromatic acclimation), or neither (type I) in response to red or green wavelengths. Recently new forms of CA have been described which include responses to blue and green light (type IV) or far-red light (FaRLiP). Here, the molecular bases of distinct forms of CA are discussed.

Importance of the green color, absorption gradient, and spectral absorption of chloroplasts for the radiative energy balance of leaves

Terrestrial green plants absorb photosynthetically active radiation (PAR; 400-700 nm) but do not absorb photons evenly across the PAR waveband. The spectral absorbance of photosystems and chloroplasts is lowest for green light, which occurs within the highest irradiance waveband of direct solar radiation. We demonstrate a close relationship between this phenomenon and the safe and efficient utilization of direct solar radiation in simple biophysiological models. The effects of spectral absorptance on the photon and irradiance absorption processes are evaluated using the spectra of direct and diffuse solar radiation. The radiation absorption of a leaf arises as a consequence of the absorption of chloroplasts. The photon absorption of chloroplasts is strongly dependent on the distribution of pigment concentrations and their absorbance spectra. While chloroplast movements in response to light are important mechanisms controlling PAR absorption, they are not effective for green light because chloroplasts have the lowest spectral absorptance in the waveband. With the development of palisade tissue, the incident photons per total palisade cell surface area and the absorbed photons per chloroplast decrease. The spectral absorbance of carotenoids is effective in eliminating shortwave PAR (<520 nm), which contains much of the surplus energy that is not used for photosynthesis and is dissipated as heat. The PAR absorptance of a whole leaf shows no substantial difference based on the spectra of direct or diffuse solar radiation. However, most of the near infrared radiation is unabsorbed and heat stress is greatly reduced. The incident solar radiation is too strong to be utilized for photosynthesis under the current CO2 concentration in the terrestrial environment. Therefore, the photon absorption of a whole leaf is efficiently regulated by photosynthetic pigments with low spectral absorptance in the highest irradiance waveband and through a combination of pigment density distribution and leaf anatomical structures.

ETHYLENE RESPONSE FACTOR 74 (ERF74) plays an essential role in controlling a respiratory burst oxidase homolog D (RbohD)-dependent mechanism in response to different stresses in Arabidopsis

Recent studies indicate that the ETHYLENE RESPONSE FACTOR VII (ERF-VII) transcription factor is an important regulator of osmotic and hypoxic stress responses in plants. However, the molecular mechanism of ERF-VII-mediated transcriptional regulation remains unclear. Here, we investigated the role of ERF74 (a member of the ERF-VII protein family) by examining the abiotic stress tolerance of an ERF74 overexpression line and a T-DNA insertion mutant using flow cytometry, transactivation and electrophoretic mobility shift assays. 35S::ERF74 showed enhanced tolerance to drought, high light, heat and aluminum stresses, whereas the T-DNA insertion mutant erf74 and the erf74;erf75 double mutant displayed higher sensitivity. Using flow cytometry analysis, we found that erf74 and erf74;erf75 lines lack the reactive oxygen species (ROS) burst in the early stages of various stresses, as a result of the lower expression level of RESPIRATORY BURST OXIDASE HOMOLOG D (RbohD). Furthermore, ERF74 directly binds to the promoter of RbohD and activates its expression under different abiotic stresses. Moreover, induction of stress marker genes and ROS-scavenging enzyme genes under various stress conditions is dependent on the ERF74-RbohD-ROS signal pathway. We propose a pathway that involves ERF74 acting as an on-off switch controlling an RbohD-dependent mechanism in response to different stresses, subsequently maintaining hydrogen peroxide (H₂ O₂ ) homeostasis in Arabidopsis.

Epigenetic regulation of MdMYB1 is associated with paper bagging-induced red pigmentation of apples

Paper-bagging treatment can transform non-transcribed MdMYB1 - 2 and MdMYB1 - 3 alleles into transcribed alleles through epigenetic regulations, resulting in the red pigmentation of a normally non-red apple cultivar 'Mutsu.' Anthocyanin biosynthesis in apples is regulated by MdMYB1/A/10, an R2R3-Type MYB gene. 'Mutsu,' a triploid apple cultivar harboring non-transcribed MdMYB1-2 and MdMYB1-3 alleles, retains green skin color under field conditions. However, it can show red/pink pigmentation under natural or artificial ultraviolet-B (UV-B) light exposure after paper-bagging and bag removal treatment. In the present study, we found that in 'Mutsu,' paper bagging-induced red pigmentation was due to the activation of non-transcribed MdMYB1-2/-3 alleles, which triggered the expression of downstream anthocyanin biosynthesis genes in a UV-B-dependent manner. By monitoring the epigenetic changes during UV-B-induced pigmentation, no significant differences in DNA methylation and histone modifications in the 5' upstream region of MdMYB1-2/-3 were recorded between the UV-B-treated fruit skin (red) and the fruit skin treated only by white light (green). In contrast, bag treatment lowered the DNA methylation in this region of MdMYB1-2/-3 alleles. Similarly, higher levels of histone H3 acetylation and trimethylation of H3 tail at lysine 4, and lower level of trimethylation of H3 tail at lysine 27 were observed in the 5' upstream region of MdMYB1-2/-3 in the skin of the fruit immediately after bag removal. These results suggest that bagging treatment can induce epigenetic changes, facilitating the binding of trans factor(s) to MdMYB1-2/-3 alleles, resulting in the activation of these MYBs after bag removal.

Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation

The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (μmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies.

Transcript level coordination of carbon pathways during silicon starvation-induced lipid accumulation in the diatom Thalassiosira pseudonana

Diatoms are one of the most productive and successful photosynthetic taxa on Earth and possess attributes such as rapid growth rates and production of lipids, making them candidate sources of renewable fuels. Despite their significance, few details of the mechanisms used to regulate growth and carbon metabolism are currently known, hindering metabolic engineering approaches to enhance productivity. To characterize the transcript level component of metabolic regulation, genome-wide changes in transcript abundance were documented in the model diatom Thalassiosira pseudonana on a time-course of silicon starvation. Growth, cell cycle progression, chloroplast replication, fatty acid composition, pigmentation, and photosynthetic parameters were characterized alongside lipid accumulation. Extensive coordination of large suites of genes was observed, highlighting the existence of clusters of coregulated genes as a key feature of global gene regulation in T. pseudonana. The identity of key enzymes for carbon metabolic pathway inputs (photosynthesis) and outputs (growth and storage) reveals these clusters are organized to synchronize these processes. Coordinated transcript level responses to silicon starvation are probably driven by signals linked to cell cycle progression and shifts in photophysiology. A mechanistic understanding of how this is accomplished will aid efforts to engineer metabolism for development of algal-derived biofuels.

Photo-enhanced toxicity of fluoranthene to Gulf of Mexico marine organisms at different larval ages and ultraviolet light intensities

Significant increases in toxicity have been observed as a result of polycyclic aromatic hydrocarbon (PAH) absorption of ultraviolet (UV) radiation in aquatic organisms. Early life stage aquatic organisms are predicted to be more susceptible to PAH photo-enhanced toxicity as a result of their translucence and tendency to inhabit shallow littoral or surface waters. The objective of the present study was to evaluate the sensitivity of varying ages of larval mysid shrimp (Americamysis bahia), inland silverside (Menidia beryllina), sheepshead minnow (Cyprinodon variegatus), and Gulf killifish (Fundulus grandis) to photo-enhanced toxicity and to examine the correlation between photo-enhanced toxicity and organism pigmentation. Organisms were exposed to fluoranthene and artificial UV light at different larval ages and results were compared using median lethal concentrations (LC50s) and the lethal time-to-death (LT50s). In addition, a high UV light intensity, short-duration (4-h) experiment was conducted at approximately 24 W/m(2) of ultraviolet radiation A (UV-A) and compared with a low-intensity, long-duration (12-h) experiment at approximately 8 W/m(2) of UV-A. The results indicated decreased toxicity with increasing age for all larval organisms. The amount of organism pigmentation was correlated with observed LC50 and LT50 values. High-intensity short-duration exposure resulted in greater toxicity than low-intensity long-duration UV treatments for mysid shrimp, inland silverside, and sheepshead minnow. Data from these experiments suggest that toxicity is dependent on age, pigmentation, UV light intensity, and fluoranthene concentration.

The Type II NADPH Dehydrogenase Facilitates Cyclic Electron Flow, Energy-Dependent Quenching, and Chlororespiratory Metabolism during Acclimation of Chlamydomonas reinhardtii to Nitrogen Deprivation

When photosynthetic organisms are deprived of nitrogen (N), the capacity to grow and assimilate carbon becomes limited, causing a decrease in the productive use of absorbed light energy and likely a rise in the cellular reduction state. Although there is a scarcity of N in many terrestrial and aquatic environments, a mechanistic understanding of how photosynthesis adjusts to low-N conditions and the enzymes/activities integral to these adjustments have not been described. In this work, we use biochemical and biophysical analyses of photoautotrophically grown wild-type and mutant strains of Chlamydomonas reinhardtii to determine the integration of electron transport pathways critical for maintaining active photosynthetic complexes even after exposure of cells to N deprivation for 3 d. Key to acclimation is the type II NADPH dehydrogenase, NDA2, which drives cyclic electron flow (CEF), chlororespiration, and the generation of an H(+) gradient across the thylakoid membranes. N deprivation elicited a doubling of the rate of NDA2-dependent CEF, with little contribution from PGR5/PGRL1-dependent CEF The H(+) gradient generated by CEF is essential to sustain nonphotochemical quenching, while an increase in the level of reduced plastoquinone would promote a state transition; both are necessary to down-regulate photosystem II activity. Moreover, stimulation of NDA2-dependent chlororespiration affords additional relief from the elevated reduction state associated with N deprivation through plastid terminal oxidase-dependent water synthesis. Overall, rerouting electrons through the NDA2 catalytic hub in response to photoautotrophic N deprivation sustains cell viability while promoting the dissipation of excess excitation energy through quenching and chlororespiratory processes.

Tomato MBD5, a methyl CpG binding domain protein, physically interacting with UV-damaged DNA binding protein-1, functions in multiple processes

In tomato (Solanum lycopersicum), high pigment mutations (hp-1 and hp-2) were mapped to genes encoding UV-damaged DNA binding protein 1 (DDB1) and de-etiolated-1 (DET1), respectively. Here we characterized a tomato methyl-CpG-binding domain protein SlMBD5 identified by yeast two-hybrid screening using SlDDB1 as a bait. Yeast two-hybrid assay demonstrated that the physical interaction of SlMBD5 with SlDDB1 is mediated by the C-termini of SlMBD5 and the β-propeller-C (BPC) of SlDDB1. Co-immunoprecipitation analyses revealed that SlMBD5 associates with SlDDB1-interacting partners including SlDET1, SlCUL4, SlRBX1a and SlRBX1b in vivo. SlMBD5 was shown to target to nucleus and dimerizes via its MBD motif. Electrophoresis mobility shift analysis suggested that the MBD of SlMBD5 specifically binds to methylated CpG dinucleotides but not to methylated CpHpG or CpHpH dinucleotides. SlMBD5 expressed in protoplast is capable of activating transcription of CG islands, whereas CUL4/DDB1 antagonizes this effect. Overexpressing SlMBD5 resulted in diverse developmental alterations including darker green fruits with increased plastid level and elevated pigmentation, as well as enhanced expression of SlGLK2, a key regulator of plastid biogenesis. Taken together, we hypothesize that the physical interaction of SlMBD5 with the CUL4-DDB1-DET1 complex component may affect its binding activity to methylated DNA and subsequently attenuate its transcription activation of downstream genes.

Photobiomodulation Mitigates Diabetes-Induced Retinopathy by Direct and Indirect Mechanisms: Evidence from Intervention Studies in Pigmented Mice

Objective

Daily application of far-red light from the onset of diabetes mitigated diabetes-induced abnormalities in retinas of albino rats. Here, we test the hypothesis that photobiomodulation (PBM) is effective in diabetic, pigmented mice, even when delayed until weeks after onset of diabetes. Direct and indirect effects of PBM on the retina also were studied.

Methods

Diabetes was induced in C57Bl/6J mice using streptozotocin. Some diabetics were exposed to PBM therapy (4 min/day; 670 nm) daily. In one study, mice were diabetic for 4 weeks before initiation of PBM for an additional 10 weeks. Retinal oxidative stress, inflammation, and retinal function were measured. In some mice, heads were covered with a lead shield during PBM to prevent direct illumination of the eye, or animals were treated with an inhibitor of heme oxygenase-1. In a second study, PBM was initiated immediately after onset of diabetes, and administered daily for 2 months. These mice were examined using manganese-enhanced MRI to assess effects of PBM on transretinal calcium channel function in vivo.

Results

PBM intervention improved diabetes-induced changes in superoxide generation, leukostasis, expression of ICAM-1, and visual performance. PBM acted in part remotely from the retina because the beneficial effects were achieved even with the head shielded from the light therapy, and because leukocyte-mediated cytotoxicity of retinal endothelial cells was less in diabetics treated with PBM. SnPP+PBM significantly reduced iNOS expression compared to PBM alone, but significantly exacerbated leukostasis. In study 2, PBM largely mitigated diabetes-induced retinal calcium channel dysfunction in all retinal layers.

Conclusions

PBM induces retinal protection against abnormalities induced by diabetes in pigmented animals, and even as an intervention. Beneficial effects on the retina likely are mediated by both direct and indirect mechanisms. PBM is a novel non-pharmacologic treatment strategy to inhibit early changes of diabetic retinopathy.

Betalain induction by l-DOPA application confers photoprotection to saline-exposed leaves of Disphyma australe

The capacity to synthesize betalains has arisen in diverse phylogenetic lineages across the Caryophyllales, and because betalainic plants often grow in deserts, sand dunes, or salt marshes, it is likely that these pigments confer adaptive advantages. However, possible functional roles of foliar betalains remain largely unexplored and are difficult to test experimentally. We adopted a novel approach to examine putative photoprotective roles of betalains in leaves for which chloroplast function has been compromised by salinity. Responses of l-DOPA-treated red shoots of Disphyma australe to high light and salinity were compared with those of naturally red- and green-leafed morphs. Betalain content and tyrosinase activity were measured, and Chl fluorescence profiles and H2 O2 production were compared under white, red or green light. Green leaves lacked tyrosinase activity, but when supplied with exogenous l-DOPA they produced five betacyanins. Both the naturally red and l-DOPA-induced red leaves generated less H2 O2 and showed smaller declines in photosystem II quantum efficiency than did green leaves when exposed to white or green light, although not when exposed to red light. Light screening by epidermal betalains effectively reduces the propensity for photoinhibition and photo-oxidative stress in subjacent chlorenchyma. This may assist plant survival in exposed and saline environments.

Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays

The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of ⁶⁰Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of microbial cells, in particularly for photosynthetic organisms as the cyanobacterium Arthrospira.

Deconvolution of pigment and physiologically related photochemical reflectance index variability at the canopy scale over an entire growing season

The sensitivity of the photochemical reflectance index (PRI) to leaf pigmentation and its impacts on its potential as a proxy for light-use efficiency (LUE) have recently been shown to be problematic at the leaf scale. Most leaf-to-leaf and seasonal variability can be explained by such a confounding effect. This study relies on the analysis of PRI light curves that were generated at the canopy scale under natural conditions to derive a precise deconvolution of pigment-related and physiologically related variability in the PRI. These sources of variability were explained by measured or estimated physiologically relevant variables, such as soil water content, that can be used as indicators of water availability and canopy chlorophyll content. The PRI mainly reflected the variability in the pigment content of the canopy. However, the corrected PRI, which was obtained by subtracting the pigment-related seasonal variability from the PRI measurement, was highly correlated with the upscaled LUE measurements. Moreover, the sensitivity of the PRI to the leaf pigment content may mask the PRI versus LUE relationship or result in an artificial relationship that reflects the relationship of chlorophyll versus LUE, depending on the species phenology.

Spectral effects of LEDs on chlorophyll fluorescence and pigmentation in Phalaenopsis 'Vivien' and 'Purple Star'

We examined the effect of light emitting diode (LED) lighting in greenhouse facilities on growth, chlorophyll fluorescence and pigmentation in Phalaenopsis 'Vivien' and 'Purple Star' under purpose-built LED arrays yielding c. 200 µmol m(-2)  s(-1) at plant height for 14 h per day and 24/18°C day/night temperature, respectively, from January to April 2013. The light treatments were (1) 40% blue in 60% red (40% B/R), (2) 0% blue in 100% red (0% B/R) and (3) white LEDs with 32% blue in white (32% B/W, control), with background daylight under shade screens. The plants were harvested twice for leaf growth and pigmentation. There was no clear pattern in the spectral effect on growth since the order of leaf size differed between harvests in March and April. Fv /Fm was in the range of 0.52-0.72, but overall slightly higher in the control, which indicated a permanent downregulation of PSII in the colored treatments. The fluorescence quenching showed no acclimation to color in 'Purple Star', while 'Vivien' had lower ETR and higher NPQ in the 40% B/R, resembling low light acclimation. The pigmentation showed corresponding spectral response with increasing concentration of lutein while increasing the fraction of blue light, which increased the light absorption in the green/yellow part of the spectrum. The permanent downregulation of PSII moved a substantial part of the thermal dissipation from the light regulated NPQ to non-regulated energy losses estimated by ΦNPQ and ΦNO and the difference found in the balance between ΦPSII and ΦNPQ in 'Vivien' disappeared when ΦNO was included in the thermal dissipation.

Effect of light conditions on anatomical and biochemical aspects of somatic and zygotic embryos of hybrid larch (Larix × marschlinsii)

BACKGROUND AND AIMS

In conifers, mature somatic embryos and zygotic embryos appear to resemble one another physiologically and morphologically. However, phenotypes of cloned conifer embryos can be strongly influenced by a number of in vitro factors and in some instances clonal variation can exceed that found in nature. This study examines whether zygotic embryos that develop within light-opaque cones differ from somatic embryos developing in dark/light conditions in vitro. Embryogenesis in larch is well understood both in situ and in vitro and thus provides a suitable system for addressing this question.

METHODS

Features of somatic and zygotic embryos of hybrid larch, Larix × marschlinsii, were quantified, including cotyledon numbers, protein concentration and phenol chemistry. Somatic embryos were placed either in light or darkness for the entire maturation period. Embryos at different developmental stages were embedded and sectioned for histological analysis.

KEY RESULTS

Light, and to a lesser degree abscisic acid (ABA), influenced accumulation of protein and phenolic compounds in somatic and zygotic embryos. Dark-grown mature somatic embryos had more protein (91·77 ± 11·26 µg protein mg(-1) f.wt) than either dark-grown zygotic embryos (62·40 ± 5·58) or light-grown somatic embryos (58·15 ± 10·02). Zygotic embryos never accumulated phenolic compounds at any stage, whereas somatic embryos stored phenolic compounds in the embryonal root caps and suspensors. Light induced the production of quercetrin (261·13 ± 9·2 µg g(-1) d.wt) in somatic embryos. Mature zygotic embryos that were removed from seeds and placed on medium in light rapidly accumulated phenolics in the embryonal root cap and hypocotyl. Delaying germination with ABA delayed phenolic compound accumulation, restricting it to the embryonal root cap.

CONCLUSIONS

In larch embryos, light has a negative effect on protein accumulation, but a positive effect on phenol accumulation. Light did not affect morphogenesis, e.g. cotyledon number. Somatic embryos produced different amounts of phenolics, such as quercetrin, depending on light conditions. The greatest difference was seen in the embryonal root cap in all embryo types and conditions.

Arabidopsis STAY-GREEN2 is a negative regulator of chlorophyll degradation during leaf senescence

Chlorophyll (Chl) degradation causes leaf yellowing during senescence or under stress conditions. For Chl breakdown, STAY-GREEN1 (SGR1) interacts with Chl catabolic enzymes (CCEs) and light-harvesting complex II (LHCII) at the thylakoid membrane, possibly to allow metabolic channeling of potentially phototoxic Chl breakdown intermediates. Among these Chl catabolic components, SGR1 acts as a key regulator of leaf yellowing. In addition to SGR1 (At4g22920), the Arabidopsis thaliana genome contains an additional homolog, SGR2 (At4g11910), whose biological function remains elusive. Under senescence-inducing conditions, SGR2 expression is highly up-regulated, similarly to SGR1 expression. Here we show that SGR2 function counteracts SGR1 activity in leaf Chl degradation; SGR2-overexpressing plants stayed green and the sgr2-1 knockout mutant exhibited early leaf yellowing under age-, dark-, and stress-induced senescence conditions. Like SGR1, SGR2 interacted with LHCII but, in contrast to SGR1, SGR2 interactions with CCEs were very limited. Furthermore, SGR1 and SGR2 formed homo- or heterodimers, strongly suggesting a role for SGR2 in negatively regulating Chl degradation by possibly interfering with the proposed CCE-recruiting function of SGR1. Our data indicate an antagonistic evolution of the functions of SGR1 and SGR2 in Arabidopsis to balance Chl catabolism in chloroplasts with the dismantling and remobilizing of other cellular components in senescing leaf cells.

Microwave and micronization treatments affect dehulling characteristics and bioactive contents of dry beans (Phaseolus vulgaris L.)

BACKGROUND

Heat pretreatment is considered the first step in grain milling. This study therefore evaluated microwave and micronization heat treatments in improving the dehulling characteristics, phenolic composition and antioxidant and α-amylase activities of bean cultivars from three market classes.

RESULTS

Heat treatments improved dehulling characteristics (hull yield, rate coefficient and reduced abrasive hardness index) depending on bean cultivar, whereas treatment effects increased with dehulling time. Micronization increased minor phenolic components (tartaric esters, flavonols and anthocyanins) of all beans but had variable effects on total phenolic content depending on market class. Microwave treatment increased α-amylase inhibitor concentration, activity and potency, which were strongly correlated (r²  = 0.71, P < 0.0001) with the flavonol content of beans. Heat treatment had variable effects on the phenolic composition of bean hulls obtained by abrasive dehulling without significantly altering the antioxidant activity of black and pinto bean hulls. Principal component analysis on 22 constituents analyzed in this study demonstrated the differences in dehulling characteristics and phenolic components of beans and hulls as major factors in segregating the beneficial heat treatment effects.

CONCLUSION

Heat treatment may be useful in developing novel dietary fibers from beans with variable composition and bioactivity with a considerable range of applications as functional food ingredients.

Changes of DNA quality and meat physicochemical properties in bovine supraspinatus muscle during microwave heating

BACKGROUND

The responses of foods to microwave exposure are usually evaluated only in terms of physicochemical properties, thus undervaluing the importance of DNA in an authentication process by methods based on polymerase chain reaction (PCR). In this study, the time effect of microwave heating on some meat physicochemical properties and DNA quality has been investigated.

RESULTS

Cooking loss, instrumental colour, pH and other physicochemical parameters varied significantly during microwave cooking, reaching the lowest/highest values after 2.5 min of cooking. The exposure of meat to microwaves was found to affect characteristically the quality of extracted DNA (i.e. yield, purity and degradation). PCR products of both mitochondrial and nuclear regions were successfully observed in all samples. However, the band for large fragments became progressively fainter as treatment time increased.

CONCLUSIONS

Microwave heating caused physicochemical changes in bovine supraspinatus muscle and influenced characteristically the yield and integrity of the extracted DNA, indicating that an accurate DNA quantification and a rational choice of the genes (i.e. mtDNA versus nDNA, fragment size, etc.) to be amplified are fundamental in an authentication process by PCR-based methods.

Diapause induction, color change, and cold tolerance physiology of the diapausing larvae of the Chouioia cunea (Hymenoptera: Eulophidae)

The chalcid wasp Chouioia cunea Yang (Hymenoptera: Eulophidae) is one of the most dominant pupal parasitoids of Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), an invasive pest of many forestry trees and agricultural crops. For mass rearing C. cunea for biological control purposes, the pupae of Antheraea pernyi (Guérin-Méneville) (Lepidoptera: Saturniidae) have been widely used as a substitute host in China. In this article, photoperiodic effect on diapause induction in C. cunea within the pupae of A. pernyi was investigated, and the differences in cold tolerance physiology including supercooling point, water content, and activities of three protective enzymes (Peroxidase [POD], Catalase [CAT], and Superoxide dismuase [SOD]) between diapause and nondiapause mature larvae were comparatively determined. Our results revealed that C. cunea possess a short-day induced larval diapause. The critical photoperiods for diapause induction in C. cunea were estimated to be between a photoperiod of 13:11 and 14:10 (L:D) h at 18°C, or between a photoperiod of 12:12 and 13:11 (L:D) h at 21°C or 24°C. We also found that the color of C. cunea diapausing larvae was taupe, while the normally developed (nondiapausing) individuals were light yellow. This body color change can be used as an indicator of diapause entry of C. cunea larave. The average supercooling point of diapausing mature larvae were lower than those of nondiapausing ones. There were significant differences in the activity of three protective enzymes (POD, CAT, and SOD) between diapausing and nondiapausing mature larvae.

Inhibitory effects of salidroside and paeonol on tyrosinase activity and melanin synthesis in mouse B16F10 melanoma cells and ultraviolet B-induced pigmentation in guinea pig skin

Salidroside, the major active component of Rhodiola rosea, a herb with antioxidant, free radical scavenging and tyrosinase inhibitory effects, has been recently reported in protecting the kerationcytes from the UV radiation, suggesting the potential of this component in depigmentation. Paeonol is isolated from Moutan Cortex Radicis with anti-inflammation/microbial activities, was reported to induce the down-regulation of microphthalmia-associated transcription factor and subsequently tyrosinase. To testify the potential of these compounds as melanin formation inhibitors for hyperpigmentation therapy, the influence of salidroside and paeonol on pigmentation was investigated. With arbutin as a positive control, salidroside and paeonol were evaluated for their inhibitory effect on the cell viability, tyrosinase activity and melanin synthesis in B16F10 melanoma cells, as well as their effects in UVB-induced hyperpigmentation in brown guinea pig skins. It was demonstrated that the significant inhibition of salidroside (33.0%) and paeonol (22.2-30.9%) on the tyrosinase activity is slightly lower than that of arbutin (18.4-44.7%). However, salidroside exhibited the dose-dependent inhibition (30.6-42.0%) in melanin synthesis at a low concentration of 100 μM, paeonol and arbutin expressed inhibition rates of 27.4-37.2% and 25.8-45.6% within 500-1000 μM. The in vivo topical application of these compounds was demonstrated to obviously decrease the hyperpigmentation on UVB stimulated guinea pig skin. This study provided the original evidence for the salidroside and paeonol as therapeutic agents for pigmentation disorder and skin lightening, with further clinical investigation of these compounds in the field of depigmentation was suggested.

The functional significance of black-pigmented leaves: photosynthesis, photoprotection and productivity in Ophiopogon planiscapus 'Nigrescens'

Black pigmented leaves are common among horticultural cultivars, yet are extremely rare across natural plant populations. We hypothesised that black pigmentation would disadvantage a plant by reducing photosynthesis and therefore shoot productivity, but that this trait might also confer protective benefits by shielding chloroplasts against photo-oxidative stress. CO2 assimilation, chlorophyll a fluorescence, shoot biomass, and pigment concentrations were compared for near isogenic green- and black-leafed Ophiopogonplaniscapus 'Nigrescens'. The black leaves had lower maximum CO2 assimilation rates, higher light saturation points and higher quantum efficiencies of photosystem II (PSII) than green leaves. Under saturating light, PSII photochemistry was inactivated less and recovered more completely in the black leaves. In full sunlight, green plants branched more abundantly and accumulated shoot biomass quicker than the black plants; in the shade, productivities of the two morphs were comparable. The data indicate a light-screening, photoprotective role of foliar anthocyanins. However, limitations to photosynthetic carbon assimilation are relatively small, insufficient to explain the natural scarcity of black-leafed plants.

The effects of enhanced ultraviolet-B radiation on the biology of green and brown morphs of Sitobion avenae (Hemiptera: Aphididae)

The effects of enhanced UV-B radiation on the biology of green and brown morphs of Sitobion avenae (F.) (Hemiptera: Aphididae) were tested under laboratory conditions. The two S. avenae morphs were exposed directly to different doses (0, 216, 432, and 864 kJ/m(2)) of artificial UV-B. Under low doses of UV-B (216 kJ/m(2)), the nymphal development period was significantly shorter, whereas mean relative growth, total fecundity, and gross reproductive rate were significantly higher for both aphid morphs compared with those morphs under control treatments (0 kJ/m(2)). Under high doses of UV-B (432 kJ/m(2) and/or 864 kJ/m(2)), the nymphal development period was significantly longer, whereas the reproductive period, postreproductive period, difference in weight, mean relative growth, and life table parameters were significantly reduced for both aphid morphs. Moreover, the nymphal development period was significantly shorter and the differences in weight, mean relative growth, total fecundity, and life table parameters were significantly higher for the brown morph under high doses of UV-B compared with the green morph. The results showed that enhanced UV-B affects the performance of the green and brown S. avenae morphs from positively to negatively. The brown morph exhibited stronger adaptability than the green morph at high doses of UV-B.

Loss of plastoglobule kinases ABC1K1 and ABC1K3 causes conditional degreening, modified prenyl-lipids, and recruitment of the jasmonic acid pathway

Plastoglobules (PGs) are plastid lipid-protein particles. This study examines the function of PG-localized kinases ABC1K1 and ABC1K3 in Arabidopsis thaliana. Several lines of evidence suggested that ABC1K1 and ABC1K3 form a protein complex. Null mutants for both genes (abc1k1 and abc1k3) and the double mutant (k1 k3) displayed rapid chlorosis upon high light stress. Also, k1 k3 showed a slower, but irreversible, senescence-like phenotype during moderate light stress that was phenocopied by drought and nitrogen limitation, but not cold stress. This senescence-like phenotype involved degradation of the photosystem II core and upregulation of chlorophyll degradation. The senescence-like phenotype was independent of the EXECUTER pathway that mediates genetically controlled cell death from the chloroplast and correlated with increased levels of the singlet oxygen-derived carotenoid β-cyclocitral, a retrograde plastid signal. Total PG volume increased during light stress in wild type and k1 k3 plants, but with different size distributions. Isolated PGs from k1 k3 showed a modified prenyl-lipid composition, suggesting reduced activity of PG-localized tocopherol cyclase (VTE1), and was consistent with loss of carotenoid cleavage dioxygenase 4. Plastid jasmonate biosynthesis enzymes were recruited to the k1 k3 PGs but not wild-type PGs, while pheophytinase, which is involved in chlorophyll degradation, was induced in k1 k3 and not wild-type plants and was localized to PGs. Thus, the ABC1K1/3 complex contributes to PG function in prenyl-lipid metabolism, stress response, and thylakoid remodeling.

UV-B radiation impacts shoot tissue pigment composition in Allium fistulosum L. cultigens

Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes. In this study, 16 cultigens of bunching onion (Allium fistulosum L.) were grown in a glasshouse under filtered UV radiation (control) or supplemental UV-B radiation [7.0  μ mol·m(-2) · s(-2) (2.68 W · m(-2))] to determine impacts on growth, physiological parameters, and nutritional quality. Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some, but not all, of the bunching onions. Xanthophyll carotenoid pigments lutein and β -carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens. Cultigen "Pesoenyj" responded to supplemental UV-B radiation with increases in the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin, which may indicate a flux in the xanthophyll carotenoids towards deepoxydation, commonly found under high irradiance stress. Increases in carotenoid concentrations would be expected to increase crop nutritional values.

Distinguishing variable phenotypes from variegation caused by transposon activities

Variable phenotypes are common in nature and in laboratory materials. Guidelines and illustrations are presented to help distinguish developmental, environmental, disease, and somatic recombination-generated variation from the phenotypes caused by transposable elements.

Truncated photosystem chlorophyll antenna size in the green microalga Chlamydomonas reinhardtii upon deletion of the TLA3-CpSRP43 gene

The truncated light-harvesting antenna size3 (tla3) DNA insertional transformant of Chlamydomonas reinhardtii is a chlorophyll-deficient mutant with a lighter green phenotype, a lower chlorophyll (Chl) per cell content, and higher Chl a/b ratio than corresponding wild-type strains. Functional analyses revealed a higher intensity for the saturation of photosynthesis and greater light-saturated photosynthetic activity in the tla3 mutant than in the wild type and a Chl antenna size of the photosystems that was only about 40% of that in the wild type. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western-blot analyses showed that the tla3 strain was deficient in the Chl a/b light-harvesting complex. Molecular and genetic analyses revealed a single plasmid insertion in chromosome 4 of the tla3 nuclear genome, causing deletion of predicted gene g5047 and plasmid insertion within the fourth intron of downstream-predicted gene g5046. Complementation studies defined that gene g5047 alone was necessary and sufficient to rescue the tla3 mutation. Gene g5047 encodes a C. reinhardtii homolog of the chloroplast-localized SRP43 signal recognition particle, whose occurrence and function in green microalgae has not hitherto been investigated. Biochemical analysis showed that the nucleus-encoded and chloroplast-localized CrCpSRP43 protein specifically operates in the assembly of the peripheral components of the Chl a/b light-harvesting antenna. This work demonstrates that cpsrp43 deletion in green microalgae can be employed to generate tla mutants with a substantially diminished Chl antenna size. The latter exhibit improved solar energy conversion efficiency and photosynthetic productivity under mass culture and bright sunlight conditions.

The well-tuned blues: the role of structural colours as optical signals in the species recognition of a local butterfly fauna (Lepidoptera: Lycaenidae: Polyommatinae)

The photonic nanoarchitectures responsible for the blue colour of the males of nine polyommatine butterfly species living in the same site were investigated structurally by electron microscopy and spectrally by reflectance spectroscopy. Optical characterization was carried out on 110 exemplars. The structural data extracted by dedicated software and the spectral data extracted by standard software were inputted into an artificial neural network software to test the specificity of the structural and optical characteristics. It was found that both the structural and the spectral data allow species identification with an accuracy better than 90 per cent. The reflectance data were further analysed using a colour representation diagram built in a manner analogous to that of the human Commission Internationale de l'Eclairage diagram, but the additional blue visual pigment of lycaenid butterflies was taken into account. It was found that this butterfly-specific colour representation diagram yielded a much clearer distinction of the position of the investigated species compared with previous calculations using the human colour space. The specific colours of the investigated species were correlated with the 285 flight-period data points extracted from museum collections. The species with somewhat similar colours fly in distinct periods of the year such that the blue colours are well tuned for safe mate/competitor recognition. This allows for the creation of an effective pre-zygotic isolation mechanism for closely related synchronic and syntopic species.

The use of light in prey capture by the tropical pitcher plant Nepenthes aristolochioides

Nepenthes pitcher plants deploy tube-shaped pitchers to catch invertebrate prey; those of Nepenthes aristolochioides possess an unusual translucent dome. The hypothesis was tested that N. aristolochioides pitchers operate as light traps, by quantifying prey capture under three shade treatments. Flies are red-blind, with visual sensitivity maxima in the UV, blue, and green wavebands. Red celluloid filters were used to reduce the transmission of these wavebands into the interior of the pitchers. Those that were shaded at the rear showed a 3-fold reduction in Drosophila caught, relative to either unshaded control pitchers, or pitchers that were shaded at the front. Thus, light transmitted through the translucent dome is a fundamental component of N. aristolochioides' trapping mechanism.

RNA silencing in white petunia flowers creates pigmentation patterns invisible to the human eye

Modern commercial petunias exhibit a wide range of flower colors, which can be observed in gardens. In this study, we present a petunia cultivar that exhibits a floral pattern that is invisible to humans but is possibly visible to pollinating insects. We show that this hidden pattern is established by differentially localized accumulation of flavonols and cinnamic acid derivatives in the corolla limb. This accumulation is caused by a combination of two distinct mechanisms that inhibit anthocyanin biosynthesis: a loss-of-function mutation in the ANTHOCYANIN2, and localized RNA-silencing of CHALCONE SYNTHASE-A.

Carotenoid profiling and biosynthetic gene expression in flesh and peel of wild-type and hp-1 tomato fruit under UV-B depletion

Although light is recognized as one of the main factors influencing fruit carotenogenesis, the specific role of UV-B radiation has been poorly investigated. The present work is addressed to assess the molecular events underlying carotenoid accumulation in presence or absence of ultraviolet-B (UV-B) light in tomato fruits of wild-type and high pigment-1 (hp-1), a mutant characterized by exaggerated photoresponsiveness and increased fruit pigmentation. Gene expression analyses indicated that in wild-type fruits UV-B radiation mainly negatively affects the carotenoid biosynthetic genes encoding enzymes downstream of lycopene both in flesh and peel, suggesting that the down-regulation of genes CrtL-b and CrtL-e and the subsequent accumulation of lycopene during tomato ripening are determined at least in part by UV-B light. In contrast to wild-type, UV-B depletion did not greatly affect carotenoid accumulation in hp-1 and generally determined minor differences in gene expression between control and UV-B-depleted conditions.

Depigmentation in melanomas increases the efficacy of hypericin-mediated photodynamic-induced cell death

Melanoma is the main cause of death in skin cancers. Despite combating with early detection, resection and post-operative therapy, melanoma treatment remains unsuccessful and investigations into other forms of adjuvant therapy such as photodynamic therapy (PDT) are prudent. This study proposes that depigmentation i.e. the removal of the free radical scavenging pigment, melanin, in melanotic melanoma cells increases their susceptibility to PDT-induced cell death. Two human melanoma cell lines: one pigmented (Mel-1) and one amelanotic (A(375)) cell lines were used. Kojic acid (KA), a tyrosinase-specific inhibitor, was optimised to 6 μg/ml and shown to quantifiably inhibit melanin synthesis after a 3-day exposure. PDT on these cells resulted in a 3.82 fold increase of intracellular ROS production which correlated to 11% increase in cell death susceptibility compared to untreated controls. Moreover, cells allowed to regain their pigment failed to return to normal even after 72 h thus proving the effectiveness of PDT. Using a DPPH* assay, the results confirmed the scavenging properties of melanin (IC(50) 18.30 μg/ml) proving that this pigment may be one of the reasons for melanoma chemoresistance. Overall this study shows that pigment plays an important role in the efficacy of adjunctive PDT treatment and its removal enhances cell death susceptibility in melanomas.

Analysis of al-2 mutations in Neurospora

The orange pigmentation of the fungus Neurospora crassa is due to the accumulation of the xanthophyll neurosporaxanthin and precursor carotenoids. Two key reactions in the synthesis of these pigments, the formation of phytoene from geranylgeranyl pyrophosphate and the introduction of β cycles in desaturated carotenoid products, are catalyzed by two domains of a bifunctional protein, encoded by the gene al-2. We have determined the sequence of nine al-2 mutant alleles and analyzed the carotenoid content in the corresponding strains. One of the mutants is reddish and it is mutated in the cyclase domain of the protein, and the remaining eight mutants are albino and harbor different mutations on the phytoene synthase (PS) domain. Some of the mutations are expected to produce truncated polypeptides. A strain lacking most of the PS domain contained trace amounts of a carotenoid-like pigment, tentatively identified as the squalene desaturation product diapolycopene. In support, trace amounts of this compound were also found in a knock-out mutant for gene al-2, but not in that for gene al-1, coding for the carotene desaturase. The cyclase activity of the AL-2 enzyme from two albino mutants was investigated by heterologous expression in an appropriately engineered E. coli strain. One of the AL-2 enzymes, predictably with only 20% of the PS domain, showed full cyclase activity, suggesting functional independence of both domains. However, the second mutant showed no cyclase activity, indicating that some alterations in the phytoene synthase segment affect the cyclase domain. Expression experiments showed a diminished photoinduction of al-2 transcripts in the al-2 mutants compared to the wild type strain, suggesting a synergic effect between reduced expression and impaired enzymatic activities in the generation of their albino phenotypes.