Mutation to a cytochrome P450 -like gene alters the leaf color by affecting the heme and chlorophyll biosynthesis pathways in Brassica napus

The regulated biosynthesis of chlorophyll is important because of its effects on plant photosynthesis and dry biomass production. In this study, a map-based cloning approach was used to isolate the cytochrome P450 -like gene BnaC08g34840D (BnCDE1) from a chlorophyll-deficient mutant (cde1) of Brassica napus obtained by ethyl methanesulfonate (EMS) mutagenization. Sequence analyses revealed that BnaC08g34840D in the cde1 mutant (BnCDE1I320T ) encodes a substitution at amino acid 320 (Ile320Thr) in the conserved region. The over-expression of BnCDE1I320T in ZS11 (i.e., gene-mapping parent with green leaves) recapitulated a yellow-green leaf phenotype. The CRISPR/Cas9 genome-editing system was used to design two single-guide RNAs (sgRNAs) targeting BnCDE1I320T in the cde1 mutant. The knockout of BnCDE1I320T in the cde1 mutant via a gene-editing method restored normal leaf coloration (i.e., green leaves). These results indicate that the substitution in BnaC08g34840D alters the leaf color. Physiological analyses showed that the over-expression of BnCDE1I320T leads to decreases in the number of chloroplasts per mesophyll cell and in the contents of the intermediates of the chlorophyll biosynthesis pathway in leaves, while it increases heme biosynthesis, thereby lowering the photosynthetic efficiency of the cde1 mutant. The Ile320Thr mutation in the highly conserved region of BnaC08g34840D inhibited chlorophyll biosynthesis and disrupted the balance between heme and chlorophyll biosynthesis. Our findings may further reveal how the proper balance between the chlorophyll and heme biosynthesis pathways is maintained.

Impact of shift work on dementia: a systematic review and dose-response meta-analysis

OBJECTIVES

Although shift work has been reported as having a link to dementia, evidence remains inconsistent, and a comprehensive dose-response meta-analysis of the association is still lacking. We therefore conducted this meta-analysis to explore the association between shift work and the risk of dementia.

STUDY DESIGN

Systematic review and dose-response meta-analysis.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. Fixed or random-effects models were used to estimate the summary relative risks (RRs) and 95% confidence intervals (95% CIs). Generalized least squares regression was used to estimate dose-response associations, and restricted cubic splines were used to examine possible linear or non-linear associations.

RESULTS

Five articles (10 studies) with 72,999 participants and 23,067 cases were eventually included in the meta-analysis. The summary RRs and 95% CIs of dementia risk with shift work and night shift work versus daytime work were 1.13 (95% CI: 1.05-1.21, I2 = 46.70%) and 1.13 (95% CI: 1.03-1.24, I2 = 9.20%), respectively. The risk of dementia increased by 1% (RR = 1.01, 95% CI: 1.01-1.02, I2 = 41.3%) with each 1-year increase in the duration of shift work. We found a non-linear dose-response association between the duration of shift work and the risk of dementia (Pnon-linearity = 0.006). Though the shape of the curve was steeper with the duration of shift work <7 years, the increase was more gradual after 7 years.

CONCLUSION

Our findings suggest that shift work may be a risk factor for future dementia and that controlling the length of shift work is a feasible measure that may contribute to prevent dementia.

Comparative proteomic and physiological analyses reveal tribenuron-methyl phytotoxicity and nontarget-site resistance mechanisms in Brassica napus

The application of herbicides is the most effective strategy for weed control and the development of herbicide-resistant crops will facilitate the weed management. The acetolactate synthase-inhibiting herbicide, tribenuron-methyl (TBM), is broadly used for weed control. However, its application in rapeseed field is restricted since rapeseed is sensitive to TBM. Herein, an integrated study of cytological, physiological and proteomic analysis of the TBM-resistant rapeseed mutant M342 and its wild-type (WT) plants was conducted. After TBM spraying, M342 showed improved tolerance to TBM, and proteins implicated in non-target-site resistance (NTSR) to herbicides had a significantly higher level in M342 as compared with the WT. Differentially accumulated proteins (DAPs) between these two genotypes were enriched in glutathione metabolism and oxidoreduction coenzyme metabolic process, which protected the mutant from oxidative stress triggered by TBM. Important DAPs related to stress or defence response were up-accumulated in M342 regardless of the TBM treatment, which might serve as the constitutive part of NTSR to TBM. These results provide new clues for further exploration of the NTSR mechanism in plants and establish a theoretical basis for the development of herbicide-resistant crops.

Fine Mapping of a Pleiotropic Locus (BnUD1) Responsible for the Up-Curling Leaves and Downward-Pointing Siliques in Brassica napus

Leaves and siliques are important organs associated with dry matter biosynthesis and vegetable oil accumulation in plants. We identified and characterized a novel locus controlling leaf and silique development using the Brassica napus mutant Bnud1, which has downward-pointing siliques and up-curling leaves. The inheritance analysis showed that the up-curling leaf and downward-pointing silique traits are controlled by one dominant locus (BnUD1) in populations derived from NJAU5773 and Zhongshuang 11. The BnUD1 locus was initially mapped to a 3.99 Mb interval on the A05 chromosome with a BC₆F₂ population by a bulked segregant analysis-sequencing approach. To more precisely map BnUD1, 103 InDel primer pairs uniformly covering the mapping interval and the BC₅F₃ and BC₆F₂ populations consisting of 1042 individuals were used to narrow the mapping interval to a 54.84 kb region. The mapping interval included 11 annotated genes. The bioinformatic analysis and gene sequencing data suggested that BnaA05G0157900ZS and BnaA05G0158100ZS may be responsible for the mutant traits. Protein sequence analyses showed that the mutations in the candidate gene BnaA05G0157900ZS altered the encoded PME in the trans-membrane region (G45A), the PMEI domain (G122S), and the pectinesterase domain (G394D). In addition, a 573 bp insertion was detected in the pectinesterase domain of the BnaA05G0157900ZS gene in the Bnud1 mutant. Other primary experiments indicated that the locus responsible for the downward-pointing siliques and up-curling leaves negatively affected the plant height and 1000-seed weight, but it significantly increased the seeds per silique and positively affected photosynthetic efficiency to some extent. Furthermore, plants carrying the BnUD1 locus were compact, implying they may be useful for increasing B. napus planting density. The findings of this study provide an important foundation for future research on the genetic mechanism regulating the dicotyledonous plant growth status, and the Bnud1 plants can be used directly in breeding.

Ammonia borane positively regulates cold tolerance in Brassica napus via hydrogen sulfide signaling

BACKGROUND

Cold stress adversely influences rapeseeds (Brassica napus L.) growth and yield during winter and spring seasons. Hydrogen (H₂) is a potential gasotransmitter that is used to enhance tolerance against abiotic stress, including cold stress. However, convenience and stability are two crucial limiting factors upon the application of H₂ in field agriculture. To explore the application of H₂ in field, here we evaluated the role of ammonia borane (AB), a new candidate for a H₂ donor produced by industrial chemical production, in plant cold tolerance.

RESULTS

The application with AB could obviously alleviate the inhibition of rapeseed seedling growth and reduce the oxidative damage caused by cold stress. The above physiological process was closely related to the increased antioxidant enzyme system and reestablished redox homeostasis. Importantly, cold stress-triggered endogenous H₂S biosynthesis was further stimulated by AB addition. The removal or inhibition of H₂S synthesis significantly abolished plant tolerance against cold stress elicited by AB. Further field experiments demonstrated that the phenotypic and physiological performances of rapeseed plants after challenged with cold stress in the winter and early spring seasons were significantly improved by administration with AB. Particularly, the most studied cold-stress response pathway, the ICE1-CBF-COR transcriptional cascade, was significantly up-regulated either.

CONCLUSION

Overall, this study clearly observed the evidence that AB-increased tolerance against cold stress could be suitable for using in field agriculture by stimulation of H₂S signaling.

A small chromosomal inversion mediated by MITE transposons confers cleistogamy in Brassica napus

Cleistogamy, self-pollination within closed flowers, can help maintain seed purity, accelerate breeding speed, and aid in the development of ornamental flowers. However, the mechanism underlying petal closing/opening behavior remains elusive. Here, we found that a Brassica napus petal closing/opening behavior was inherited in a Mendelian manner. Fine mapping and positional cloning experiments revealed that the Mendelian factor originated from a short (29.8 kb) inversion mediated by BnDTH9 miniature inverted-repeat transposable elements (MITEs) on chromosome C03. This inversion led to tissue-specific gene promoter exchange between BnaC03.FBA (BnaC03G0156800ZS encoding an F-Box-associated domain-containing protein) and BnaC03.EFO1 (BnaC03G0157400ZS encoding an EARLY FLOWERING BY OVEREXPRESSION 1 protein) positioned near the respective inversion breakpoints. Our genetic transformation work demonstrated that the cleistogamy originated from high tissue-specific expression of the BnaC03.FBA gene caused by promoter changes due to the MITE-mediated inversion. BnaC03.FBA is involved in the formation of an SCF (Skp1-Cullin-F-box) complex, which participates in ubiquitin-mediated protein targeting for degradation through the ubiquitin 26S-proteasome system. Our results shed light on a molecular model of petal-closing behavior.

Potential role of circulating exosome miRNAs in left ventricular remodeling of patients with ST-segment elevation myocardial infarction

Background

Left ventricular remodeling (LVR) in patients with ST-segment elevation myocardial infarction (STEMI) may lead to poor prognosis in which circulating exosome miRNAs play a critical role. The aim of the present study is to identify specific exosome miRNAs for LVR in patients with STEMI.

Method

Plasma exosome miRNAs were assessed in 20 patients (90% male, mean age of 66.95±1.65 years) 3–6 months after STEMI and 24 healthy individuals (83% male, mean age of 33.2±0.93 years) by using qPCR. Of the 20 patients, 8 had post-STEMI LVR according to echocardiographic evaluation, and the others did not. Clinical biochemical data including total cholesterol, HDL-C, LDL-C, LDH and NT-pro-BNP were collected from the patients with STEMI at same time as exosome miRNAs assessment. Specific exosome miRNAs for LVR were identified by using qPCR. Correlations between the dysregulated exosome miRNAs and the clinical biochemical parameters in patients with STEMI were analyzed using spearman correlation test.

Results

Five exosome miRNAs including hsa-miR-181a-3p (p&lt;0.05, fold change = 0.59), let-7d-3p (p=0.01, fold change = 0.51), hsa-miR-224-5p (p&lt;0.01, fold change = 0.11), hsa-miR-23a-3p (p&lt;0.01, fold change = 1.42) and miR-874-3p (p&lt;0.01, fold change = 0.48) were dysregulated in the post-STEMI patients comparing with the healthy individuals. Among them, the exosome miR-181a-3p (p=0.01, fold change = 0.09) and let-7d-3p (p=0.01, fold change = 0.16) were significantly lower expressed in patients with LVR compared to those without (Figure 1). There was no significant difference in expression of the other three miRNAs between patients with and without LVR. Exosome hsa-miR-874-3p positively associated with LDH (p&lt;0.01, r=0.50) in all the patients with STEMI. In vitro cell culture confirmed that the miR-874-3p mimics upregulated expression of apoptosis related gene BMF (p&lt;0.05, fold change = 1.7) in cardiomyocyte. Exosome hsa-miR-23a-3p and hsa-miR-224-5p positively correlated with both HDL-C (p&lt;0.01, r=0.61; p=0.02, r=0.50) and LDL-C (p=0.02, r=0.50; p&lt;0.05, r=0.52) in all patients with STEMI. No correlation between the dysregulated exosome miRNAs and cholesterol or NT-ProBNP was observed (Figure 2).

Conclusions

Circulating exosome miR-181a-3p and let-7d-3p might play a potential role in LVR in patients 3–6 months after STEMI. Exosome hsa-miR-874-3p might be associated with cardiomyocyte injury. Hsa-miR-23a-3p and hsa-miR-224-5p demonstrated an activity in regulation of lipid metabolism and biosynthesis in patients with STEMI.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): This work was supported by grants from the 3×3 Clinical Scientist Fund of Sun Yat-sen Memorial Hospital

Identification and Fine Mapping of a Locus Related to Leaf Up-Curling Trait (Bnuc3) in Brassica napus

Leaf trait is an important target trait in crop breeding programs. Moderate leaf curling may be a help for improving crop yield by minimizing the shadowing by leaves. Mining locus for leaf curling trait is of significance for plant genetics and breeding researches. The present study identified a novel rapeseed accession with up-curling leaf, analyzed the up-curling leaf trait inheritance, and fine mapped the locus for up-curling leaf property (Bnuc3) in Brassica napus. Genetic analysis revealed that the up-curling leaf trait is controlled by a single dominant locus, named BnUC3. We performed an association study of BnUC3 with single nucleotide polymorphism (SNP) markers using a backcross population derived from the homozygous up-curling leaf line NJAU-M1295 and the canola variety ‘zhongshuang11’ with typical flat leaves, and mapped the BnUC3 locus in a 1.92 Mb interval of chromosome A02 of B. napus. To further map BnUC3, 232 simple sequence repeat (SSR) primers and four pairs of Insertion/Deletion (InDel) primers were developed for the mapping interval. Among them, five SSR markers and two InDel markers were polymorphic. By these markers, the mapping interval was narrowed to 92.0 kb using another F₂ population. This fine mapping interval has 11 annotated genes among which BnaA02T0157000ZS were inferred to be candidate casual genes for up-curling leaf based on the cloned sequence analysis, gene functionality, and gene expression analysis. The current study laid a foundational basis for further elucidating the mechanism of BnUC3 and breeding of variety with up-curling leaf.

Fine mapping of the BnaC04.BIL1 gene controlling plant height in Brassica napus L

BACKGROUND

Plant height is an important architecture trait which is a fundamental yield-determining trait in crops. Variety with dwarf or semi-dwarf phenotype is a major objective in the breeding because dwarfing architecture can help to increase harvest index, increase planting density, enhance lodging resistance, and thus be suitable for mechanization harvest. Although some germplasm or genes associated with dwarfing plant type have been carried out. The molecular mechanisms underlying dwarfism in oilseed rape (Brassica napus L.) are poorly understood, restricting the progress of breeding dwarf varieties in this species. Here, we report a new dwarf mutant Bndwarf2 from our B. napus germplasm. We studied its inheritance and mapped the dwarf locus BnDWARF2.

RESULTS

The inheritance analysis showed that the dwarfism phenotype was controlled by one semi-dominant gene, which was mapped in an interval of 787.88 kb on the C04 chromosome of B. napus by Illumina Brassica 60 K Bead Chip Array. To fine-map BnDWARF2, 318 simple sequence repeat (SSR) primers were designed to uniformly cover the mapping interval. Among them, 15 polymorphic primers that narrowed down the BnDWARF2 locus to 34.62 kb were detected using a F2:3 family population with 889 individuals. Protein sequence analysis showed that only BnaC04.BIL1 (BnaC04g41660D) had two amino acid residues substitutions (Thr187Ser and Gln399His) between ZS11 and Bndwarf2, which encoding a GLYCOGEN SYNTHASE KINASE 3 (GSK3-like). The quantitative real-time PCR (qRT-PCR) analysis showed that the BnaC04.BIL1 gene expressed in all tissues of oilseed rape. Subcellular localization experiment showed that BnaC04.BIL1 was localized in the nucleus in tobacco leaf cells. Genetic transformation experiments confirmed that the BnaC04.BIL1 is responsible for the plant dwarf phenotype in the Bndwarf2 mutants. Overexpression of BnaC04.BIL1 reduced plant height, but also resulted in compact plant architecture.

CONCLUSIONS

A dominant dwarfing gene, BnaC04.BIL1, encodes an GSK3-like that negatively regulates plant height, was mapped and isolated. Our identification of a distinct gene locus may help to improve lodging resistance in oilseed rape.

Nitric Oxide Is Associated With Heterosis of Salinity Tolerance in Brassica napus L

Heterosis is most frequently manifested as the superior performance of a hybrid than either of the parents, especially under stress conditions. Nitric oxide (NO) is a well-known gaseous signaling molecule that acts as a functional component during plant growth, development, and defense responses. In this study, the Brassica napus L. hybrid (F1, NJ4375 × MB1942) showed significant heterosis under salt stress, during both germination and post-germination periods. These phenotypes in the hybrid were in parallel with the better performance in redox homeostasis, including alleviation of reactive oxygen species accumulation and lipid peroxidation, and ion homeostasis, evaluated as a lower Na/K ratio in the leaves than parental lines. Meanwhile, stimulation of endogenous NO was more pronounced in hybrid plants, compared with parental lines, which might be mediated by nitrate reductase. Proteomic and biochemical analyses further revealed that protein abundance related to several metabolic processes, including chlorophyll biosynthesis, proline metabolism, and tricarboxylic acid cycle metabolism pathway, was greatly suppressed by salt stress in the two parental lines than in the hybrid. The above responses in hybrid plants were intensified by a NO-releasing compound, but abolished by a NO scavenger, both of which were matched with the changes in chlorophyll and proline contents. It was deduced that the above metabolic processes might play important roles in heterosis upon salt stress. Taken together, we proposed that heterosis derived from F1 hybridization in salt stress tolerance might be mediated by NO-dependent activation of defense responses and metabolic processes.

Fine mapping of the BnUC2 locus related to leaf up-curling and plant semi-dwarfing in Brassica napus

Background

Studies of leaf shape development and plant stature have made important contributions to the fields of plant breeding and developmental biology. The optimization of leaf morphology and plant height to improve lodging resistance and photosynthetic efficiency, increase planting density and yield, and facilitate mechanized harvesting is a desirable goal in Brassica napus.

Results

Here, we investigated a B. napus germplasm resource exhibiting up-curled leaves and a semi-dwarf stature. In progeny populations derived from NJAU5737 and Zhongshuang 11 (ZS11), we found that the up-curled leaf trait was controlled by a dominant locus, BnUC2. We then fine mapped the BnUC2 locus onto an 83.19-kb interval on chromosome A05 using single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers. We further determined that BnUC2 was a major plant height QTL that explained approximately 70% of the phenotypic variation in two BC₅F₃ family populations derived from NJAU5737 and ZS11. This result implies that BnUC2 was also responsible for the observed semi-dwarf stature. The fine mapping interval of BnUC2 contained five genes, two of which, BnaA05g16700D (BnaA05.IAA2) and BnaA05g16720D, were revealed by comparative sequencing to be mutated in NJAU5737. This result suggests that the candidate gene mutation (BnaA05g16700D, encoding Aux/IAA2 proteins) in the conserved Degron motif GWPPV (P63S) was responsible for the BnUC2 locus. In addition, investigation of agronomic traits in a segregated population indicated that plant height, main inflorescence length, and branching height were significantly reduced by BnUC2, whereas yield was not significantly altered. The determination of the photosynthetic efficiency showed that the BnUC2 locus was beneficial to improve the photosynthetic efficiency. Our findings may provide an effective foundation for plant type breeding in B. napus.

Conclusions

Using SNP and SSR markers, a dominant locus (BnUC2) related to up-curled leaves and semi-dwarf stature in B. napus has been fine mapped onto an 83.19-kb interval of chromosome A05 containing five genes. The BnaA05.IAA2 is inferred to be the candidate gene responsible for the BnUC2 locus.

Using artificial intelligence algorithms to identify existing knowledge within the back pain literature

PURPOSE

Artificial intelligence algorithms can now identify hidden data patterns within the scientific literature. In 2019, these algorithms identified a thermoelectric material within the pre-2009 chemistry literature; years before its discovery in 2012. This approach inspired us to apply this algorithm to the back pain literature as the cause of back pain remains unknown in 90% of cases.

METHODS

We created a subset of all PubMed abstracts containing "back" and "pain" and then trained the Word2vec algorithm to predict word proximity. We then identified word pairings having high vector proximities between three spinal domains: anatomy, pathology and treatment. We plotted both between-domain and within-domain proximities then used the highest proximity pairs as ground truths in analogy testing to identify known associations (e.g., Canal is to Stenosis as Multifidus is to ?) RESULTS: We found  50,038 abstracts resulting in 27,984 unique words and 108,252 instances of "back pain". Ground truth pairings ranged in proximity from 0.86 to 0.70. Plotting revealed unique proximity representations between the three spine domains. From analogy testing, we identified 13 known word associations (pars_interarticularis is to stress_reaction as nerve_root is to compression).

CONCLUSIONS

Artificial intelligence algorithms can successfully extract complex concepts from back pain literature. While use of AI algorithms to discover potentially unknown word associations requires future validation, our results provide investigators with a novel tool to generate new hypotheses regarding the origins of LBP and other spine related topics. To encourage use of these tools, we have created a free web-based app for investigator-driven queries.

Chitinase-like protein YKL-40 regulates human bronchial epithelial cells proliferation, apoptosis, and migration through TGF-β1/Smads pathway

In order to study the effects of chitinase-like protein YKL-40 on proliferation, apoptosis, and migration of human bronchial epithelial cell line (BEAS-2B), and the underlying mechanisms, we cultured BEAS-2B alone or with different concentrations of YKL-40. thiazolyl blue tetrazolium bromide (MTT) assay was used to examine the cell proliferation. Annexin V-fluorescein isothiocyanate isomer (FITC)/propidium iodide staining and scratch assay were performed to test the cell apoptosis and migration. The concentrations of transforming growth factor-β1 (TGF-β1), Smad3, Smad7, alpha-smooth muscle actin (α-SMA), interleukin-4 (IL-4), IL-6, and IL-8 in the cell culture supernatant were detected by enzyme-linked immunosorbent assay. The messenger RNA and protein levels of YKL-40, TGF-β1, Smad3, Smad7, and α-SMA were detected by reverse transcription polymerase chain reaction and Western blot. BEAS-2B cells cultured with different concentrations of YKL-40 showed significantly higher cell proliferation and migration and inflammatory cytokines compared with that of control group, while the cell apoptosis was significantly lower than that of control group (p < 0.05). In addition, BEAS-2B cells cultured with YKL-40 had increased TGF-β1, Smad3, Smad7, and α-SMA levels in the supernatant, compared with that of BEAS-2B cells cultured alone (p < 0.05). Furthermore, LY364947, as TGF-β1/Smads signaling pathway inhibitor, decreased cell proliferation and migration ability and enhanced cell apoptosis of BEAS-2B cells compared with control group (p < 0.05). However, YKL-40 administration reversed the effect of LY364947 on the biological behavior of BEAS-2B cells. YKL-40 could affect the biological behaviors of BEAS-2B cells, which might be related to the TGF-β1/Smads pathway.

Fine mapping of an up-curling leaf locus (BnUC1) in Brassica napus

BACKGROUND

Leaf shape development research is important because leaf shapes such as moderate curling can help to improve light energy utilization efficiency. Leaf growth and development includes initiation of the leaf primordia and polar differentiation of the proximal-distal, adaxial-abaxial, and centrolateral axes. Changes in leaf adaxial-abaxial polarity formation, auxin synthesis and signaling pathways, and development of sclerenchyma and cuticle can cause abnormal leaf shapes such as up-curling leaf. Although many genes related to leaf shape development have been reported, the detailed mechanism of leaf development is still unclear. Here, we report an up-curling leaf mutant plant from our Brassica napus germplasm. We studied its inheritance, mapped the up-curling leaf locus BnUC1, built near-isogenic lines for the Bnuc1 mutant, and evaluated the effect of the dominant leaf curl locus on leaf photosynthetic efficiency and agronomic traits.

RESULTS

The up-curling trait was controlled by one dominant locus in a progeny population derived from NJAU5734 and Zhongshuang 11 (ZS11). This BnUC1 locus was mapped in an interval of 2732.549 kb on the A05 chromosome of B. napus using Illumina Brassica 60 K Bead Chip Array. To fine map BnUC1, we designed 201 simple sequence repeat (SSR) primers covering the mapping interval. Among them, 16 polymorphic primers that narrowed the mapping interval to 54.8 kb were detected using a BC₆F₂ family population with 654 individuals. We found six annotated genes in the mapping interval using the B. napus reference genome, including BnaA05g18250D and BnaA05g18290D, which bioinformatics and gene expression analyses predicted may be responsible for leaf up-curling. The up-curling leaf trait had negative effects on the agronomic traits of 30 randomly selected individuals from the BC₆F₂ population. The near-isogenic line of the up-curling leaf (ZS11-UC1) was constructed to evaluate the effect of BnUC1 on photosynthetic efficiency. The results indicated that the up-curling leaf trait locus was beneficial to improve the photosynthetic efficiency.

CONCLUSIONS

An up-curling leaf mutant Bnuc1 was controlled by one dominant locus BnUC1. This locus had positive effects on photosynthetic efficiency, negative effects on some agronomic traits, and may help to increase planting density in B. napus.

Nitrate reductase-dependent nitric oxide is crucial for multi-walled carbon nanotube-induced plant tolerance against salinity

Although there have been some studies on the plant-carbonaceous nanomaterials (CNMs) interactions, related conclusions were controversial. Here, we report that multi-walled carbon nanotubes (MWCNTs) can enter into rapeseed (Brassica napus L.) seedling root, and transport to stem. Further results showed that salinity-inhibited rapeseed seedling growth was obviously alleviated by MWCNTs. Meanwhile, NaCl-induced nitrate reductase (NR)-dependent NO production was significantly intensified by MWCNTs. The redox and ion imbalance was reestablished as well, confirmed by the reduction in reactive oxygen species (ROS) overproduction, the decrease in thiobarbituric acid reactive substance production, and the lower Na+/K+ ratio. These beneficial effects could be explained by the changes in related antioxidant defense genes, sodium hydrogen exchanger 1 (NHX1), salt overly sensitive 1 (SOS1), and K+transporter 1 (KT1) transcripts. The above responses were separately abolished after the removal of endogenous NO with its scavengers or the addition of the NR inhibitor. Genetic evidence revealed that the NaCl-triggered NO level in wild-type seedling roots was partly abolished in either the nitric reductase mutant (nia1/2) or noa1 mutant (exhibiting indirectly a reduced endogenous NO level). Treatment with MWCNTs could totally rescue the impaired NO production in the noa1 mutant rather than the nia1/2 mutant, suggesting that NR-dependent NO acts as a downstream signaling molecule in MWCNT signaling. This point was verified by phenotypic analyses, histochemical staining, and ion analysis. qPCR analysis further demonstrated that MWCNTs stimulated antioxidant genes and ion balance-related genes through NR-mediated NO. The above molecular and genetic evidence indicated that NR-dependent NO acts downstream of MWCNTs in salinity tolerance, which requires the reestablishment of redox and ion homeostasis.

L-Cysteine desulfhydrase-dependent hydrogen sulfide is required for methane-induced lateral root formation

Methane-triggered lateral root formation is not only a universal event, but also dependent on L-cysteine desulfhydrase-dependent hydrogen sulfide signaling. Whether or how methane (CH₄) triggers lateral root (LR) formation has not been elucidated. In this report, CH₄ induction of lateral rooting and the role of hydrogen sulfide (H₂S) were dissected in tomato and Arabidopsis by using physiological, anatomical, molecular, and genetic approaches. First, we discovered that CH₄ induction of lateral rooting is a universal event. Exogenously applied CH₄ not only triggered tomato lateral rooting, but also increased activities of L-cysteine desulfhydrase (DES; a major synthetic enzyme of H₂S) and induced endogenous H₂S production, and contrasting responses were observed in the presence of hypotaurine (HT; a scavenger of H₂S) or DL-propargylglycine (PAG; an inhibitor of DES) alone. CH₄-triggered lateral rooting were sensitive to the inhibition of endogenous H₂S with HT or PAG. The changes in the transcripts of representative cell cycle regulatory genes, miRNA and its target genes were matched with above phenotypes. In the presence of CH₄, Arabidopsis mutant Atdes1 exhibited defects in lateral rooting, compared with the wild-type. Molecular evidence showed that the transcriptional profiles of representative target genes modulated by CH₄ in wild-type plants were impaired in Atdes1 mutant. Overall, our data demonstrate the main branch of the DES-dependent H₂S signaling cascade in CH₄-triggered LR formation.

Therapeutic effect of ginsenoside Rg1 on mastitis experimentally induced by lipopolysaccharide in lactating goats

Escherichia coli is a cause of subclinical and clinical mastitis in dairy cattle and goats, and sometimes causes severe clinical disease that may result in death of the animal. Previous investigation showed that ginsenoside Rg1 extracted from Panax ginseng C.A. Meyer (Araliaceae) has an anti-inflammatory effect on the sepsis induced by E. coli lipopolysaccharide via competitive binding to toll-like receptor 4. We hypothesized that intravenous injection of Rg1 had therapeutic effect on mastitis experimentally induced by intramammary infusion of lipopolysaccharide in lactating goats. In this study, 9 lactating goats were randomly assigned to 1 of the 3 groups: (1) lipopolysaccharide intramammary infusion + saline intravenous injection, (2) lipopolysaccharide intramammary infusion + Rg1 intravenous injection, and (3) saline intramammary administration + saline intravenous injection. Because no adverse clinical signs were observed after intramammary infusion of saline and intravenous injection of Rg1 in a preliminary experiment, and available qualified goats were limited in this study, this treatment was not included in this study. One udder half of each goat received intramammary infusion of lipopolysaccharide (50 μg/kg of body weight; groups 1 and 2) or saline solution (group 3), and the other half was infused with 2 mL of saline solution at h 0. Afterward, intravenous injections of saline solution (groups 1 and 3) or Rg1 (2.5 mg/kg of body weight; group 2) were administered at h 2 and 4 post-lipopolysaccharide challenge. Blood and milk samples were collected 3, 6, 9, 12, 15, 18, 21, 24, 48, and 72 h post-lipopolysaccharide challenge, and clinical signs were monitored hourly after lipopolysaccharide challenge within the first 10 h and at the same time points as blood samples. The results showed that Rg1 treatment downregulated rectal temperature, udder skin temperature, udder girth, milk somatic cell count, and N-acetyl-β-d-glucosaminidase and upregulated milk production, lactose, and recovered blood components, such as white blood cells, neutrophils, lymphocytes, total proteins, albumin, and globulin. Considering the positive therapeutic effect on lipopolysaccharide-induced mastitis in goats presented in this study as well as the anti-inflammatory activity found previously, the botanical Rg1 deserves further study as a therapeutic agent in the treatment of E. coli mastitis in dairy animals.

Histological, Physiological, and Comparative Proteomic Analyses Provide Insights into Leaf Rolling in Brassica napus

Moderate leaf rolling is important in ideotype breeding, as it improves photosynthetic efficiency and therefore increases crop yields. To understand the regulatory network of leaf rolling in Brassica napus, a down-curved leaf mutant ( Bndcl1) has been investigated. Physiological analyses indicated that the chlorophyll contents and antioxidant enzyme activities were remarkably increased and the photosynthetic performance was significantly improved in Bndcl1. Consistent with these findings, 943 differentially accumulated proteins (DAPs) were identified in the Bndcl1 mutant and its wild-type plants using iTRAQ-based comparative proteomic analyses. Enrichment analysis of proteins with higher abundance in Bndcl1 revealed that the functional category "photosynthesis" was significantly overrepresented. Moreover, proteins associated with oxidative stress response and photosystem II repairing were also up-accumulated in Bndcl1, which might help the mutant to sustain the photosynthetic efficiency under unfavorable conditions. Histological observation showed that the mutant displayed defects in adaxial-abaxial patterning. Important DAPs associated with leaf polarity establishment were detected in Bndcl1, including ribosomal proteins, proteins involved in post-transcriptional gene silencing, and proteins related to brassinosteroid. Together, our findings may help clarify the mechanisms underlying leaf rolling and its physiological effects on plants and may facilitate ideotype breeding in Brassica napus.

A Knowledge Base Completion Model Based on Path Feature Learning

Large-scale knowledge bases, as the foundations for promoting the development of artificial intelligence, have attracted increasing attention in recent years. These knowledge bases contain billions of facts in triple format; yet, they suffer from sparse relations between entities. Researchers proposed the path ranking algorithm (PRA) to solve this fatal problem. To improve the scalability of knowledge inference, PRA exploits random walks to find Horn clauses with chain structures to predict new relations given existing facts. This method can be regarded as a statistical classification issue for statistical relational learning (SRL). However, large-scale knowledge base completion demands superior accuracy and scalability. In this paper, we propose the path feature learning model (PFLM) to achieve this urgent task. More precisely, we define a two-stage model: the first stage aims to learn path features from the existing knowledge base and extra parsed corpus; the second stage uses these path features to predict new relations. The experimental results demonstrate that the PFLM can learn meaningful features and can achieve significant and consistent improvements compared with previous work.

Quantitative Trait Transcripts Mapping Coupled with Expression Quantitative Trait Loci Mapping Reveal the Molecular Network Regulating the Apetalous Characteristic in Brassica napus L

The apetalous trait of rapeseed (Brassica napus, AACC, 2n = 38) is important for breeding an ideal high-yield rapeseed with superior klendusity to Sclerotinia sclerotiorum. Currently, the molecular mechanism underlying the apetalous trait of rapeseed is unclear. In this study, 14 petal regulators genes were chosen as target genes (TGs), and the expression patterns of the 14 TGs in the AH population, containing 189 recombinant inbred lines derived from a cross between apetalous "APL01" and normal "Holly," were analyzed in two environments using qRT-PCR. Phenotypic data of petalous degree (PDgr) in the AH population were obtained from the two environments. Both quantitative trait transcript (QTT)-association mapping and expression QTL (eQTL) analyses of TGs expression levels were performed to reveal regulatory relationships among TGs and PDgr. QTT mapping for PDgr determined that PLURIPETALA (PLP) was the major negative QTT associated with PDgr in both environments, suggesting that PLP negatively regulates the petal development of line "APL01." The QTT mapping of PLP expression levels showed that CHROMATIN-REMODELING PROTEIN 11 (CHR11) was positively associated with PLP expression, indicating that CHR11 acts as a positive regulator of PLP expression. Similarly, QTT mapping for the remaining TGs identified 38 QTTs, associated with 13 TGs, and 31 QTTs, associated with 10 TGs, respectively, in the first and second environments. Additionally, eQTL analyses of TG expression levels showed that 12 and 11 unconditional eQTLs were detected in the first and second environment, respectively. Based on the QTTs and unconditional eQTLs detected, we presented a hypothetical molecular regulatory network in which 14 petal regulators potentially regulated the apetalous trait in "APL01" through the CHR11-PLP pathway. PLP acts directly as the terminal signal integrator negatively regulating petal development in the CHR11-PLP pathway. These findings will aid in the understanding the molecular mechanism underlying the apetalous trait of rapeseed.

An innovative procedure of genome-wide association analysis fits studies on germplasm population and plant breeding

KEY MESSAGE

The innovative RTM-GWAS procedure provides a relatively thorough detection of QTL and their multiple alleles for germplasm population characterization, gene network identification, and genomic selection strategy innovation in plant breeding. The previous genome-wide association studies (GWAS) have been concentrated on finding a handful of major quantitative trait loci (QTL), but plant breeders are interested in revealing the whole-genome QTL-allele constitution in breeding materials/germplasm (in which tremendous historical allelic variation has been accumulated) for genome-wide improvement. To match this requirement, two innovations were suggested for GWAS: first grouping tightly linked sequential SNPs into linkage disequilibrium blocks (SNPLDBs) to form markers with multi-allelic haplotypes, and second utilizing two-stage association analysis for QTL identification, where the markers were preselected by single-locus model followed by multi-locus multi-allele model stepwise regression. Our proposed GWAS procedure is characterized as a novel restricted two-stage multi-locus multi-allele GWAS (RTM-GWAS, https://github.com/njau-sri/rtm-gwas ). The Chinese soybean germplasm population (CSGP) composed of 1024 accessions with 36,952 SNPLDBs (generated from 145,558 SNPs, with reduced linkage disequilibrium decay distance) was used to demonstrate the power and efficiency of RTM-GWAS. Using the CSGP marker information, simulation studies demonstrated that RTM-GWAS achieved the highest QTL detection power and efficiency compared with the previous procedures, especially under large sample size and high trait heritability conditions. A relatively thorough detection of QTL with their multiple alleles was achieved by RTM-GWAS compared with the linear mixed model method on 100-seed weight in CSGP. A QTL-allele matrix (402 alleles of 139 QTL × 1024 accessions) was established as a compact form of the population genetic constitution. The 100-seed weight QTL-allele matrix was used for genetic characterization, candidate gene prediction, and genomic selection for optimal crosses in the germplasm population.

[Modulation of umbilical cord blood mesenchymal stem cells on Treg cells in the patients with aplastic anemia]

Objective: To research the modulation of Umbilical cord blood mesenchymal stem cells on the number and function of Treg cells in the patients with aplastic anemia, as well as the expression of LFA-1 on Treg cells. Methods: A total of 20 newly diagnosed NSAA patients were collected from May 2015 to Jun 2016 in Department of Hematopathy, General Hospital of Jinan Military, and 10 healthy volunteers were recruited as controls. Separation of the patients and controls with peripheral blood mononuclear cells were divided into two groups, including PBMCs culture alone, PBMCs co-culture with UC-MSCs, application of flow cytometry detect respectively the proportion of the Treg cells and the expression of LFA-1 on Treg cells under different culture conditions. The Treg cells and CD4(+) CD25(-)T lymphocyte were separated by magnetic cell sorting (MACS) system, CFSE label CD4(+) CD25(-)T lymphocyte, comparing the inhibitive function of Treg cells on CD4(+) CD25(-)T lymphocyte with or without co-culture with UC-MSCs. Results: The intensity of fluorescence expression of LFA-1 on T lymphocyte in aplastic anemia increased obviously((71.4±10.1)vs(52.5±8.7) , P=0.002), but the LFA-1 expressed on Treg cells had no significant difference(P=0.199). After co-cultured with UC-MSCs, the proportion of LFA-1 on Treg cells in aplastic anemia reduced greatly ((20.96±1.76)% vs(44.26±1.19)%, P=0.012), at the same time, UC-MSCs increased the proportion of Treg cells obviously ((5.33±1.14)%vs(1.94±0.65)%, P=0.003), but the effect of Treg cells on the mean frquency of dividing CD4(+) CD25(-)T lymphocyte had no significant difference with or without co-culture with UC-MSCs(P=0.290). Conclusions: The intensity of fluorescence expression of LFA-1 on lymphocyte in aplastic anemia increases obviously, indicating the possible pathogenesis of AA. UC-MSCs inhibit the expression of LFA-1 on Treg cells and enhance the proportion of Treg cells, but UC-MSCs doesn't directly improve the immunosuppression of single Treg cells.

Mapping a major QTL responsible for dwarf architecture in Brassica napus using a single-nucleotide polymorphism marker approach

BACKGROUND

Key genes related to plant type traits have played very important roles in the "green revolution" by increasing lodging resistance and elevating the harvest indices of crop cultivars. Although there have been numerous achievements in the development of dwarfism and plant type in Brassica napus breeding, exploring new materials conferring oilseed rape with efficient plant types that provide higher yields is still of significance in breeding, as well as in elucidating the mechanisms underlying plant development. Here, we report a new dwarf architecture with down-curved leaf mutant (Bndwf/dcl1) isolated from an ethyl methanesulphonate (EMS)-mutagenized B. napus line, together with its inheritance and gene mapping, and pleiotropic effects of the mapped locus on plant-type traits.

RESULTS

We constructed a high-density single-nucleotide polymorphism (SNP) map using a backcross population derived from the Bndwf/dcl1 mutant and the canola cultivar 'zhongshuang11' ('ZS11') and mapped the dwarf architecture with the down-curved leaf dominant locus, BnDWF/DCL1, in a 6.58-cM interval between SNP marker bins M46180 and M49962 on the linkage group (LG) C05 of B. napus. Further mapping with other materials derived from Bndwf/dcl1 narrowed the interval harbouring BnDWF/DCL1 to 175 kb in length and this interval contained 16 annotated genes. Quantitative trait locus (QTL) mappings with the backcross population for plant type traits, including plant height, branching height, main raceme length and average branching interval, indicated that the mapped QTLs for plant type traits were located at the same position as the BnDWF/DCL1 locus.

CONCLUSIONS

This study suggests that the BnDWF/DCL1 locus is a major pleiotropic locus/QTL in B. napus, which may reduce plant height, alter plant type traits and change leaf shape, and thus may lead to compact plant architecture. Accordingly, this locus may have substantial breeding potential for increasing planting density.

Fine mapping of a major locus controlling plant height using a high-density single-nucleotide polymorphism map in Brassica napus

A saturated map was constructed using SNP markers to fine-map a Brassica napus dominant locus for dwarf mutant onto a 152-kb interval of chromosome A09 containing 14 genes. Major dwarf loci in crops may play important roles in crop improvement and developmental genetics. The present study investigated and fine-mapped a Brassica napus dwarf-dominant locus BnDWF1. Plants carrying the BnDWF1 locus in populations derived from 'zhongshuang11' and Bndwf1 have deep-green leaves and dwarf architecture that differ sharply from tall plants with normal green leaves. BnDWF1, as a major locus controlling plant height, showed a very high heritability (0.91-0.95). To map this locus, a high-density single-nucleotide polymorphism map was constructed, and the BnDWF1 locus was mapped at an interval between single-nucleotide polymorphism markers, M19704 and M19695, on linkage group A09 of B. napus, with five co-segregating single-nucleotide polymorphism markers. Furthermore, fine mapping narrowed the interval harboring BnDWF1 to 152 kb in length in B. napus. This interval contains 14 annotated or predicted genes, seven of which are candidates responsible for the dwarf trait. This study provides an effective foundation for the study of plant height regulation and plant type breeding in B. napus.

The association of DLG5 polymorphisms with inflammatory bowel disease: a meta-analysis of 25 studies

OBJECTIVE

The aim of this study was to explore the association of polymorphisms in DLG5 gene (G113A, C4136A and e26) with inflammatory bowel disease (IBD) risk.

MATERIALS AND METHODS

A total of 25 studies involved 26583 subjects were pooled for analysis. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to pool the effect size.

RESULTS

For G113A variant, a significant association was observed with CD risk in children (A vs. G: OR = 0.745, 95% CI = 0.569-0.977) and high quality studies (A vs. G: OR = 0.913, 95% CI = 0.850-0.981). Additionally, the results of genotype-phenotype analysis suggested G113A variant was associated with colonic involvement in CD. However, in overall population, the results indicated G113A variant was not associated with CD or UC. We also provided evidence that C4136A polymorphism had different effects on CD risk between Europeans (AA vs. CC: OR = 3.239, 95% CI = 1.149-9.136) and Asians (AA vs. CC: OR = 0.511, 95% CI = 0.299-0.873). For UC, patients with AA genotype of C4136A variant had a significantly increased UC risk (AA vs. CC: OR = 3.877, 95% CI = 1.168-12.867). Finally, no association was detected with G113A or e26 polymorphism in CD or UC patients.

CONCLUSIONS

This meta-analysis indicated G113A variant may be significantly associated with CD risk in children and colonic involvement.

Misfolding Ectodomain Mutations of the Lutropin Receptor Increase Efficacy of Hormone Stimulation

We demonstrate 2 novel mutations of the LHCGR, each homozygous, in a 46,XY patient with severe Leydig cell hypoplasia. One is a mutation in the signal peptide (p.Gln18_Leu19ins9; referred to here as SP) that results in an alteration of the coding sequence of the N terminus of the mature mutant receptor. The other mutation (p.G71R) is also within the ectodomain. Similar to many other inactivating mutations, the cell surface expression of recombinant human LHR(SP,G71R) is greatly reduced due to intracellular retention. However, we made the unusual discovery that the intrinsic efficacy for agonist-stimulated cAMP in the reduced numbers of receptors on the cell surface was greatly increased relative to the same low number of cell surface wild-type receptor. Remarkably, this appears to be a general attribute of misfolding mutations in the ectodomains, but not serpentine domains, of the gonadotropin receptors. These findings suggest that there must be a common, shared mechanism by which disparate mutations in the ectodomain that cause misfolding and therefore reduced cell surface expression concomitantly confer increased agonist efficacy to those receptor mutants on the cell surface. Our data further suggest that, due to their increased agonist efficacy, extremely small changes in cell surface expression of misfolded ectodomain mutants cause larger than expected alterations in the cellular response to agonist. Therefore, for inactivating LHCGR mutations causing ectodomain misfolding, the numbers of cell surface mutant receptors on fetal Leydig cells of 46,XY individuals exert a more exquisite effect on the relative severity of the clinical phenotypes than already appreciated.

Composite Interval Mapping Based on Lattice Design for Error Control May Increase Power of Quantitative Trait Locus Detection

Experimental error control is very important in quantitative trait locus (QTL) mapping. Although numerous statistical methods have been developed for QTL mapping, a QTL detection model based on an appropriate experimental design that emphasizes error control has not been developed. Lattice design is very suitable for experiments with large sample sizes, which is usually required for accurate mapping of quantitative traits. However, the lack of a QTL mapping method based on lattice design dictates that the arithmetic mean or adjusted mean of each line of observations in the lattice design had to be used as a response variable, resulting in low QTL detection power. As an improvement, we developed a QTL mapping method termed composite interval mapping based on lattice design (CIMLD). In the lattice design, experimental errors are decomposed into random errors and block-within-replication errors. Four levels of block-within-replication errors were simulated to show the power of QTL detection under different error controls. The simulation results showed that the arithmetic mean method, which is equivalent to a method under random complete block design (RCBD), was very sensitive to the size of the block variance and with the increase of block variance, the power of QTL detection decreased from 51.3% to 9.4%. In contrast to the RCBD method, the power of CIMLD and the adjusted mean method did not change for different block variances. The CIMLD method showed 1.2- to 7.6-fold higher power of QTL detection than the arithmetic or adjusted mean methods. Our proposed method was applied to real soybean (Glycine max) data as an example and 10 QTLs for biomass were identified that explained 65.87% of the phenotypic variation, while only three and two QTLs were identified by arithmetic and adjusted mean methods, respectively.

An RNA-seq transcriptome analysis of floral buds of an interspecific Brassica hybrid between B. carinata and B. napus

Interspecific hybridizations promote gene transfer between species and play an important role in plant speciation and crop improvement. However, hybrid sterility that commonly found in the first generation of hybrids hinders the utilization of interspecific hybridization. The combination of divergent parental genomes can create extensive transcriptome variations, and to determine these gene expression alterations and their effects on hybrids, an interspecific Brassica hybrid of B. carinata × B. napus was generated. Scanning electron microscopy analysis indicated that some of the hybrid pollen grains were irregular in shape and exhibited abnormal exine patterns compared with those from the parents. Using the Illumina HiSeq 2000 platform, 39,598, 32,403 and 42,208 genes were identified in flower buds of B. carinata cv. W29, B. napus cv. Zhongshuang 11 and their hybrids, respectively. The differentially expressed genes were significantly enriched in pollen wall assembly, pollen exine formation, pollen development, pollen tube growth, pollination, gene transcription, macromolecule methylation and translation, which might be associated with impaired fertility in the F1 hybrid. These results will shed light on the mechanisms underlying the low fertility of the interspecific hybrids and expand our knowledge of interspecific hybridization.

Complete mitochondrial genome of Eruca sativa Mill. (Garden rocket)

Eruca sativa (Cruciferae family) is an ancient crop of great economic and agronomic importance. Here, the complete mitochondrial genome of Eruca sativa was sequenced and annotated. The circular molecule is 247 696 bp long, with a G+C content of 45.07%, containing 33 protein-coding genes, three rRNA genes, and 18 tRNA genes. The Eruca sativa mitochondrial genome may be divided into six master circles and four subgenomic molecules via three pairwise large repeats, resulting in a more dynamic structure of the Eruca sativa mtDNA compared with other cruciferous mitotypes. Comparison with the Brassica napus MtDNA revealed that most of the genes with known function are conserved between these two mitotypes except for the ccmFN2 and rrn18 genes, and 27 point mutations were scattered in the 14 protein-coding genes. Evolutionary relationships analysis suggested that Eruca sativa is more closely related to the Brassica species and to Raphanus sativus than to Arabidopsis thaliana.

Glycogen synthase kinase-3 reduces acetylcholine level in striatum via disturbing cellular distribution of choline acetyltransferase in cholinergic interneurons in rats

Cholinergic interneurons, which provide the main source of acetylcholine (ACh) in the striatum, control the striatal local circuits and deeply involve in the pathogenesis of neurodegenerative diseases. Glycogen synthase kinase-3 (GSK-3) is a crucial kinase with diverse fundamental functions and accepted that deregulation of GSK-3 activity also plays important roles in diverse neurodegenerative diseases. However, up to now, there is no direct proof indicating whether GSK-3 activation is responsible for cholinergic dysfunction. In the present study, with combined intracerebroventricular injection of Wortmannin and GF-109203X, we activated GSK-3 and demonstrated the increased phosphorylation level of microtubule-associated protein tau and neurofilaments (NFs) in the rat striatum. The activated GSK-3 consequently decreased ACh level in the striatum as a result of the reduction of choline acetyltransferase (ChAT) activity. The alteration of ChAT activity was due to impaired ChAT distribution rather than its expression. Furthermore, we proved that cellular ChAT distribution was dependent on low phosphorylation level of NFs. Nevertheless, the cholinergic dysfunction in the striatum failed to induce significant neuronal number reduction. In summary, our data demonstrates the link between GSK-3 activation and cholinergic dysfunction in the striatum and provided beneficial evidence for the pathogenesis study of relevant neurodegenerative diseases.

The mitochondrial genome of soybean reveals complex genome structures and gene evolution at intercellular and phylogenetic levels

Determining mitochondrial genomes is important for elucidating vital activities of seed plants. Mitochondrial genomes are specific to each plant species because of their variable size, complex structures and patterns of gene losses and gains during evolution. This complexity has made research on the soybean mitochondrial genome difficult compared with its nuclear and chloroplast genomes. The present study helps to solve a 30-year mystery regarding the most complex mitochondrial genome structure, showing that pairwise rearrangements among the many large repeats may produce an enriched molecular pool of 760 circles in seed plants. The soybean mitochondrial genome harbors 58 genes of known function in addition to 52 predicted open reading frames of unknown function. The genome contains sequences of multiple identifiable origins, including 6.8 kb and 7.1 kb DNA fragments that have been transferred from the nuclear and chloroplast genomes, respectively, and some horizontal DNA transfers. The soybean mitochondrial genome has lost 16 genes, including nine protein-coding genes and seven tRNA genes; however, it has acquired five chloroplast-derived genes during evolution. Four tRNA genes, common among the three genomes, are derived from the chloroplast. Sizeable DNA transfers to the nucleus, with pericentromeric regions as hotspots, are observed, including DNA transfers of 125.0 kb and 151.6 kb identified unambiguously from the soybean mitochondrial and chloroplast genomes, respectively. The soybean nuclear genome has acquired five genes from its mitochondrial genome. These results provide biological insights into the mitochondrial genome of seed plants, and are especially helpful for deciphering vital activities in soybean.

Complete sequence of heterogenous-composition mitochondrial genome (Brassica napus) and its exogenous source

BACKGROUND

Unlike maternal inheritance of mitochondria in sexual reproduction, somatic hybrids follow no obvious pattern. The introgressed segment orf138 from the mitochondrial genome of radish (Raphanus sativus) to its counterpart in rapeseed (Brassica napus) demonstrates that this inheritance mode derives from the cytoplasm of both parents. Sequencing of the complete mitochondrial genome of five species from Brassica family allowed the prediction of other extraneous sources of the cybrids from the radish parent, and the determination of their mitochondrial rearrangement.

RESULTS

We obtained the complete mitochondrial genome of Ogura-cms-cybrid (oguC) rapeseed. To date, this is the first time that a heterogeneously composed mitochondrial genome was sequenced. The 258,473 bp master circle constituted of 33 protein-coding genes, 3 rRNA sequences, and 23 tRNA sequences. This mitotype noticeably holds two copies of atp9 and is devoid of cox2-2. Relative to nap mitochondrial genome, 40 point mutations were scattered in the 23 protein-coding genes. atp6 even has an abnormal start locus whereas tatC has an abnormal end locus. The rearrangement of the 22 syntenic regions that comprised 80.11% of the genome was influenced by short repeats. A pair of large repeats (9731 bp) was responsible for the multipartite structure. Nine unique regions were detected when compared with other published Brassica mitochondrial genome sequences. We also found six homologous chloroplast segments (Brassica napus).

CONCLUSIONS

The mitochondrial genome of oguC is quite divergent from nap and pol, which are more similar with each other. We analyzed the unique regions of every genome of the Brassica family, and found that very few segments were specific for these six mitotypes, especially cam, jun, and ole, which have no specific segments at all. Therefore, we conclude that the most specific regions of oguC possibly came from radish. Compared with the chloroplast genome, six identical regions were found in the seven mitochondrial genomes, which show that the Brassica family has a stable chloroplast-derived source.

Mitochondrial genome sequencing helps show the evolutionary mechanism of mitochondrial genome formation in Brassica

Background

Angiosperm mitochondrial genomes are more complex than those of other organisms. Analyses of the mitochondrial genome sequences of at least 11 angiosperm species have showed several common properties; these cannot easily explain, however, how the diverse mitotypes evolved within each genus or species. We analyzed the evolutionary relationships of Brassica mitotypes by sequencing.

Results

We sequenced the mitotypes of cam (Brassica rapa), ole (B. oleracea), jun (B. juncea), and car (B. carinata) and analyzed them together with two previously sequenced mitotypes of B. napus (pol and nap). The sizes of whole single circular genomes of cam, jun, ole, and car are 219,747 bp, 219,766 bp, 360,271 bp, and 232,241 bp, respectively. The mitochondrial genome of ole is largest as a resulting of the duplication of a 141.8 kb segment. The jun mitotype is the result of an inherited cam mitotype, and pol is also derived from the cam mitotype with evolutionary modifications. Genes with known functions are conserved in all mitotypes, but clear variation in open reading frames (ORFs) with unknown functions among the six mitotypes was observed. Sequence relationship analysis showed that there has been genome compaction and inheritance in the course of Brassica mitotype evolution.

Conclusions

We have sequenced four Brassica mitotypes, compared six Brassica mitotypes and suggested a mechanism for mitochondrial genome formation in Brassica, including evolutionary events such as inheritance, duplication, rearrangement, genome compaction, and mutation.

BnHO1, a haem oxygenase-1 gene from Brassica napus, is required for salinity and osmotic stress-induced lateral root formation

In this report, a rapeseed (Brassica napus) haem oxygenase-1 gene BnHO1 was cloned and sequenced. It shared high homology with Arabidopsis HY1 proteins, and encodes a 32.6 kDa protein with a 54-amino-acid transit peptide, predicting the mature protein of 25.1 kDa. The mature BnHO1 expressed in Escherichia coli exhibits haem oxygenase (HO) activity. Furthermore, the application of lower doses of NaCl (10 mM) and polyethylene glycol (PEG) (2%) mimicked the inducible effects of naphthylacetic acid and the HO-1 inducer haemin on the up-regulation of BnHO1 and subsequent lateral root (LR) formation. Contrasting effects were observed when a higher dose of NaCl or PEG was applied. The above inducible and inhibitory responses were blocked significantly when the HO-1 inhibitor zinc protoporphyrin IX (ZnPPIX) or haemin was applied, both of which were reversed by the application of carbon monoxide or ZnPPIX, respectively. Moreover, the addition of ZnPPIX at different time points during LR formation indicated that BnHO1 might be involved in the early stages of LR formation. The auxin response factor transcripts and the auxin content in seedling roots were clearly induced by lower doses of salinity or osmotic stress. However, treatment with the inhibitor of polar auxin transport N-1-naphthylphthalamic acid prevented the above inducible responses conferred by lower doses of NaCl and PEG, which were further rescued when the treatments were combined with haemin. Taken together, these results suggested a novel role of the rapeseed HO-1 gene in salinity and osmotic stress-induced LR formation, with a possible interaction with auxin signalling.

Enhanced seed oil production in canola by conditional expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in developing seeds

The seed oil content in oilseed crops is a major selection trait to breeders. In Arabidopsis (Arabidopsis thaliana), LEAFY COTYLEDON1 (LEC1) and LEC1-LIKE (L1L) are key regulators of fatty acid biosynthesis. Overexpression of AtLEC1 and its orthologs in canola (Brassica napus), BnLEC1 and BnL1L, causes an increased fatty acid level in transgenic Arabidopsis plants, which, however, also show severe developmental abnormalities. Here, we use truncated napin A promoters, which retain the seed-specific expression pattern but with a reduced expression level, to drive the expression of BnLEC1 and BnL1L in transgenic canola. Conditional expression of BnLEC1 and BnL1L increases the seed oil content by 2% to 20% and has no detrimental effects on major agronomic traits. In the transgenic canola, expression of a subset of genes involved in fatty acid biosynthesis and glycolysis is up-regulated in developing seeds. Moreover, the BnLEC1 transgene enhances the expression of several genes involved in Suc synthesis and transport in developing seeds and the silique wall. Consistently, the accumulation of Suc and Fru is increased in developing seeds of the transgenic rapeseed, suggesting the increased carbon flux to fatty acid biosynthesis. These results demonstrate that BnLEC1 and BnL1L are reliable targets for genetic improvement of rapeseed in seed oil production.

Ministry of Health clinical practice guidelines: Chronic Hepatitis B Infection

The Ministry of Health (MOH) publishes clinical practice guidelines on Chronic Hepatitis B Infection to provide doctors and patients in Singapore with evidence-based guidance on managing important medical conditions. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Chronic Hepatitis B Infection, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website (http://www.moh.gov.sg/mohcorp/publications.aspx?id=26108). The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Comparison of intra-coronary cell transplantation after myocardial infarction: Autologous skeletal myoblasts versus bone marrow mesenchymal stem cells

Cell transplantation promises restoration of cardiac function after myocardial infarction (MI). Comparison of intracoronary cell transplantation with skeletal myoblasts (SMs) versus bone marrow mesenchymal stem cells (BM-MSCs) was carried out in rabbits with MI induced by ligation of the left anterior descending artery. The infarction-affected artery was injected with SMs, BM-MSCs or cell-free medium (control) 24 h post-infarction (n = 15 per group). At baseline, there were no differences in cardiac parameters between the groups. At 4 weeks post-transplantation, left ventricular ejection fraction significantly improved and left ventricular end-diastolic diameter was significantly decreased in the cell-treated groups compared with pre-transplantation and the control group. Engrafted cells were found in all of the cell-treated rabbits. The cell-treated animals had significantly higher numbers of neovessels compared with the control. No significant difference was seen between the SM and BM-MSC groups. In conclusion, intra-coronary transplantation of SMs and BM-MSCs induced neoangiogenesis with comparable enhancements of cardiac performance and reduced cardiac remodelling in a rabbit MI model.

Cloning and expression analysis of three cDNAs encoding omega-3 fatty acid desaturases from Descurainia sophia

Three cDNAs of DsFAD3, DsFAD7 and DsFAD8, encoding omega-3 fatty acid desaturases, which are the key enzymes for the conversion of linoleic to alpha-linolenic acid (18:3n-3), were isolated from Descurainia sophia using RACE-PCR. Tissue-specific expression analysis revealed that DsFAD3 and DsFAD7 genes were expressed in all tissues and at a high level in stems, leaves and young siliques, whereas DsFAD8 was moderately expressed in photosynthetic tissues including stems, leaves and young siliques. All three genes were significantly induced by wounding stress and DsFAD3 and DsFAD7 transcript levels were down-regulated by cold, whereas DsFAD8 was increased upon cold stress.