[Response of Soil Fungal Community to Biochar Application Under Different Irrigation Water Salinity]

Saline water irrigation can alleviate the shortage of freshwater resources in the northwest arid zone, but long-term saline water irrigation can damage the soil fungal community structure. To alleviate the harm caused by salinity, biochar is used as a soil amendment to improve the soil fungal community structure. To investigate the intrinsic link between biochar application and the structural diversity of fungal communities in saline soils, two irrigation water salinity levels were set:0.35 dS·m-1 (fresh water) and 8.04 dS·m-1 (saline water). At each irrigation water salinity, two levels of biochar application were set:0 t·hm-2 (no application) and 3.7 t·hm-2 (application). High-throughput sequencing results showed that compared to that under fresh water irrigation, saline water irrigation increased fungal community species diversity and decreased fungal community species richness; biochar application under saline water irrigation reduced soil fungal community species diversity and species richness. The dominant fungal phyla in the soils of each treatment were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Rozellomycota, and Cysticercales, and the dominant genera were Gibberella, Chaetomium, Sarocladium, Stachybotrys, and Fusarium. Compared to that under freshwater irrigation, saline water irrigation significantly increased the relative abundance of Basidiomycota and Chytridiomycota and significantly decreased the relative abundance of Ascomycota and Rozellomycota. The application of biochar under saline irrigation significantly increased the relative abundance of Ascomycota and Sarocladium but significantly decreased the relative abundance of Basidiomycota, Chaetomium, and Fusarium. LEfSe analysis showed that under the condition of no biochar application, saline irrigation reduced the number of potential biomarkers of fungal communities, whereas the application of biochar under the condition of saline irrigation increased the number of potential biomarkers of fungal communities. These results indicated that the application of biochar can improve the saline soil environment and fungal community structure and provide a theoretical basis for reasonable brackish water irrigation and soil fertilization in arid areas.

Head and neck carcinoma in children: A clinicopathological study of 42 cases

Background/purpose

Cancer is an important part of the global burden of childhood diseases. Head and neck carcinoma in children is rare and related research is limited. This study aimed to investigate the clinicopathological features of childhood head and neck carcinoma.

Materials and methods

Forty-two cases of childhood head and neck carcinoma treated in our institution were reviewed and analyzed.

Results

Median age overall was 11 years. Twenty-three patients (54.8%) were male and 19 (45.2%) were female. Parotid gland location was most common (54.8%). Mucoepidermoid carcinoma and squamous cell carcinoma were the most common histological types (57.1% and 11.9%, respectively). Two patients had a history of bone marrow transplantation and two had a history of odontogenic keratocyst. The recurrence rate after treatment was 8.6%.

Conclusion

Early diagnosis and treatment and close follow-up of childhood head and neck carcinoma are warranted to prevent recurrence and improve clinical outcome.

[Revealing the Effect of Saline Water Drip Irrigation on Soil Microorganisms in Cotton Fields Based on Metagenomics]

Saline water irrigation has become an important means to alleviate the shortage of freshwater in arid areas. However, long-term saline water irrigation can cause soil salinity accumulation, affect soil microbial community structure, and then affect soil nutrient transformation. In this study, we used metagenomics to investigate the effects of long-term saline water drip irrigation on soil microbial community structure in a cotton field. In the experiment, the salinity of irrigation water (ECw) was set to two treatments:0.35 dS·m^-1 and 8.04 dS·m^-1 (denoted as FW and SW, respectively), and the nitrogen application rates were 0 kg·hm^-2and 360 kg·hm^-2 (denoted as N0 and N360, respectively). The results showed that saline water irrigation increased soil water content, salinity, organic carbon, and total nitrogen content and decreased soil pH and available potassium content. Nitrogen fertilizer application increased soil organic carbon, salinity, and total nitrogen content and decreased soil water content, pH, and available potassium content. The dominant bacterial phyla in each treatment were:Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, and Gemmatimonadetes. Saline water irrigation significantly increased the relative abundances of Actinobacteria, Chloroflexi, Gemmatimonadetes, and Firmicutes but significantly decreased the relative abundances of Proteobacteria, Acidobacteria, Cyanobacteria, and Nitrospira. Nitrogen fertilizer application significantly increased the relative abundances of Chloroflexi and Nitrospira but significantly decreased the relative abundances of Acidobacteria, Gemmatimonadetes, Planctomycetes, Cyanobacteria, and Verrucomicrobia. LEfSe analysis showed that saline water irrigation had no significant effect on the number of potential biomarkers, and nitrogen fertilizer application decreased the number of potential biomarkers in soil microbial communities. The correlation network diagram showed that the 20 genera had different degrees of correlation, including 44 positive correlations and 48 negative correlations. The core species in the network diagram were Nocardioides, Streptomyces, Pyrinomonas, Candidatus_Solibacter, and Bradyrhizobium spp. Saline water irrigation increased the relative abundances of the denitrification genes nirK, nirS, nasB, and norC and decreased the relative abundances of the nitrification genes amoB, amoC, and nxrA, whereas nitrogen fertilizer application increased the relative abundances of the nitrification genes amoA, amoB, amoC, hao, and nxrA and decreased the relative abundances of the denitrifying genes narB, napA, nasA, and nosZ. Saline water irrigation could adversely affect soil physicochemical properties; SWC, EC_1:5, and BD were the main driving factors affecting soil microbial community structure and function genes; and soil microorganisms adapted to soil salt stress by regulating species composition.

[Clinical and endoscopic characteristics of adult celiac disease]

Objective: The study aimed to analyze the clinical and endoscopic characteristics of adult celiac disease (CD) to provide a scientific basis for more effective CD diagnosis and treatment. Methods: In this cross-sectional study, the clinical and endoscopic data of 96 adult CD patients treated in the Department of Gastroenterology of the People's Hospital of Xinjiang Uygur Autonomous Region from March 2016 to December 2021 were retrospectively collected and analyzed. Results: A total of 96 CD patients were diagnosed, including 33 men and 63 women. The average age was 47±14 years (range, 18-81 years). The disease occurred mainly in the age group of 31-60 years. The median course of the disease was 2.0 (0.2-40.0) years. There were 41 (42.7%) classical and 55 (57.3%) non-classical CD patients. All patients with classical CD showed chronic diarrhea, often accompanied by abdominal pain (46.3%, 19/41), abdominal distension (17.1%, 7/41), anemia (65.9%, 27/41), and chronic fatigue (48.8%, 20/41). The main manifestations of non-classical CD were chronic abdominal pain (58.2%, 32/55), abdominal distension (32.7%, 18/55), anemia (40.0%, 22/55), and osteopenia/osteoporosis (38.2%, 21/55). Compared with non-classical CD, anemia developed more frequently in classical CD, and the difference was statistically significant (P = 0.012). The incidence of complications in CD patients was 36.5% (35/96), and the main complications were thyroid disease (19.8%, 19/96), connective tissue disease (6.2%, 6/96), and kidney disease (6.2%, 6/96). There was no significant difference between classical and non-classical CD (P>0.05). The frequency of endoscopic manifestations in CD patients was 84.4% (81/96). Duodenal bulb endoscopy showed nodular changes (72.9%, 70/96), grooved changes (10.4%, 10/96), and focal villous atrophy (9.4%, 9/96). The main manifestations of descending endoscopy were the decrease, flattening, or disappearance of duodenal folds (43.8%, 42/96), scallop-like changes (38.5%, 37/96), and nodular changes (34.4%, 33/96). Conclusions: Adult CD patients are mostly female. CD occurred mainly in the age group of 31-60 years. The clinical manifestations were mainly those of non-classical CD. Some patients often had other autoimmune diseases. Patients with characteristic endoscopic manifestations should be warned about the possibility of developing CD. Clinicians should strengthen the understanding of CD and reduce the related rates of missed diagnosis.

[Effects of Biochar and Straw Returning on Soil Fungal Community Structure Diversity in Cotton Field with Long-term Brackish Water Irrigation]

Brackish water irrigation increases soil salinity and changes the soil environment, which affects the structure and diversity of soil fungi. In this study, the effects of biochar and straw (3.7 t·hm^-2 and 6 t·hm^-2, respectively) on soil physical and chemical properties and fungal community structure diversity were investigated on the basis of long-term brackish water irrigation. The results showed that compared to the absence of biochar and straw application (control), biochar application significantly increased pH and the contents of total carbon, available potassium, and available phosphorus in soil but significantly decreased the soil conductivity by 20.71%. Straw treatment significantly increased the content of available potassium and phosphorus but significantly decreased the soil bulk density and conductivity by 4.17% and 64.50%, respectively. The biochar and straw treatment showed an increasing trend in the Chao1 index and ACE index of the fungal community but a decreasing trend in the Shannon index and Simpson index. The dominant fungal phyla in the soil were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, and Glomeromycota. The dominant fungal genera were Chaetomium, Gibberella, Fusarium, Idriella, and Mortierella. Biochar and straw were applied to increase the relative abundance of Ascomycota, Mortierellomycota, Basidiomycota, Glomeromycota, and Chaetomium. However, the relative abundance of Chytridomycota, Gibberella, and Idriella decreased. LEfSe analysis showed that biochar application and straw returning decreased the number of potential biomarkers in fungal communities. RDA results showed that soil fungal community structure was significantly correlated with EC_1:5 and TN. Brackish irrigation had adverse effects on soil, in which EC_1:5and TN were the main factors driving the change in soil fungal community structure. The soil fungal community adapted to a salt-stress environment through the improvement of soil by biochar and straw.

Polar meron lattice in strained oxide ferroelectrics

A topological meron features a non-coplanar structure, whose order parameters in the core region are perpendicular to those near the perimeter. A meron is half of a skyrmion, and both have potential applications for information carrying and storage. Although merons and skyrmions in ferromagnetic materials can be readily obtained via inter-spin interactions, their behaviour and even existence in ferroelectric materials are still elusive. Here we observe using electron microscopy not only the atomic morphology of merons with a topological charge of 1/2, but also a periodic meron lattice in ultrathin PbTiO₃ films under tensile epitaxial strain on a SmScO₃ substrate. Phase-field simulations rationalize the formation of merons for which an epitaxial strain, as a single alterable parameter, plays a critical role in the coupling of lattice and charge. This study suggests that by engineering strain at the nanoscale it should be possible to fabricate topological polar textures, which in turn could facilitate the development of nanoscale ferroelectric devices.

[Effect of preoperative Nutritional Risk Screening-2002 combined with hematologic inflammatory markers on prognosis of thoracic esophageal squamous cell carcinoma]

Objective: To evaluate preoperative nutritional status and inflammatory status by Nutritional Risk Screening-2002 (NRS-2002) and hematologic inflammatory markers in patients with thoracic esophageal squamous cell carcinoma (ESCC), and to explore their effects on long-term survival prognosis. Methods: A total of 113 patients with thoracic ESCC treated by radical resection were grouped for further analysis according to preoperative NRS-2002 score, systemic inflammation score (SIS) and the combination of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio (CNP) score. The progression free survival (PFS) and overall survival (OS) between groups were compared. Multivariate Cox regression analysis was used to determine the independent prognostic factors of patients with thoracic esophageal squamous cell carcinoma, and the interaction analysis of statistically significant factors was carried out. Results: The median PFS was 21 months for all the patients. The 1-year, 3-year and 5-year PFS rates were 69.0%, 25.7% and 23.1%, respectively. Correspondingly, the median OS was 36 months, and the 1-year, 3-year and 5-year OS rates were 95.6%, 46.2% and 29.2%, respectively. Cox univariate analysis showed that T stage, N stage, TNM stage, SIS, CNP score and NRS-2002 score were significantly associated with PFS and OS (all P<0.05), and sex was associated with PFS (P=0.032) in patients with thoracic ESCC. Furthermore, cox multivariate analysis showed that TNM stage (HR=1.570, P=0.039), NRS-2002 score (HR=2.706, P<0.001) and CNP score (HR=1.463, P=0.011) were independent prognosis factors of PFS in patients with thoracic ESCC. In cox model interaction analysis, there was a positive interaction between NRS-2002 score and CNP score (RR=2.789, P<0.001). Conclusion: Preoperative NRS-2002 score combined with CNP score are risk factors for prognosis of patients with thoracic ESCC, which can be used as prognostic indicators.

Pharmacokinetics of ropivacaine in elderly patients receiving fascia iliaca compartment block

Local anesthetic of ropivacaine was demonstrated to reduce the postoperative pain in elderly patients. This study investigated the pharmacokinetics of ropivacaine at different concentrations in elderly patients subjected to fascia iliaca compartment block. Forty patients with femoral neck fracture at American Society of Anesthesiologists (ASA) I-II status, undergoing fascia iliaca compartment block (FICB) were randomized to two groups receiving 0.7 ml/kg of solution containing 0.375% ropivacaine (group L) or 0.5% ropivacaine (group H). Samples of venous blood were obtained immediately at different time points after FICB, and the total and free plasma concentrations of ropivacaine were measured by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Statistical analysis was carried out using a pharmacokinetic calculation program (DAS 3.0). Visual Analogue Scale (VAS) scores were significantly decreased after FICB in both groups, and VAS score in group H was lower compared with group L. The total maximum plasma concentration (C_max) and the free C_max of ropivacaine in group H was higher than that in group L (P<0.05). The decrease of the total and free plasma concentration was operation time-dependent. Neither group showed signs of central nervous system and circulatory system toxicity. On the basis of these results, the concentrations of 0.375 and 0.5% ropivacaine held an efficiently analgesic effect for FICB, suggesting that ropivacaine can be employed in analgesic therapy. However, both concentrations have a potentially theoretical risk of local anesthetics poisoning, suggesting that a lower concentration may be a safer option for a single large volume of FICB.

[Effects of electroacupuncture on insulin resistance in patients with knee arthroplasty]

OBJECTIVE

To explore the effect of electroacupuncture on the improvement of insulin resistance after knee joint replacement based on the combined spinal and epidural anesthesia and postoperative epidural analgesia.

METHODS

Eighty patients with insulin resistance but normal blood glucose were randomly divided into a control group and an observation group, 40 cases in each group.Both groups of patients underwent combined spinal and epidural anesthesia and postoperative epidural analgesia for knee arthroplasty. On the basis of the treatment,electroacupuncture (EA) was applied during the operation and within 1 month after the operation in the observation group, and EA was used at Hegu (LI 4), Qihai (CV 6), Zhongwan (CV 12), Pishu (BL 20), Shenshu (BL 23), etc. once every other day. The control group was not treated with electroacupuncture. Fasting blood glucose and fasting insulin were recorded 30 min before surgery (T₀), immediately (T₁), 1 d (T₂), 3 d (T₃), 7 d (T₄) and 1 month (T₅) after surgery, and the insulin resistance (IR) index was calculated.

RESULTS

Compared with those at T₀ time point, the IR index of the control group at T₁, T₃, T₄ and T₅ time points and the observation group at T₁, T₄, T₅ time points were lower (all P<0.05). Compared with the control group at the same time point, the IR index of the T₁ and T₅ time points in the observation group was significantly lower (both P<0.05), and it was lower than the insulin resistance standard.

CONCLUSION

Combined spinal and epidural anesthesia and postoperative epidural analgesia can improve short-term insulin resistance. Combined with EA, the improvement of insulin resistance is more obviously and longer.

Low loss (Al)GaAs on an insulator waveguide platform

In this Letter, we demonstrate a low loss gallium arsenide and aluminum gallium arsenide on an insulator platform by heterogenous integration. The resonators on this platform exhibit record high quality factors up to 1.5×10⁶, corresponding to a propagation loss ∼0.4  dB/cm. For the first time, to the best of our knowledge, the loss of integrated III-V semiconductor on insulator waveguides becomes comparable with that of the silicon-on-insulator waveguides. This Letter should have a significant impact on photonic integrated circuits (PICs) and become an essential building block for the evolving nonlinear PICs and integrated quantum photonic systems in the future.

[Prognostic influence of preoperative Nutritional Risk Screening -2002 (NRS-2002) score for patients with thoracic esophageal squamous cell carcinoma receiving surgery]

Objective: To apply Nutritional Risk Screening-2002(NRS-2002) to perform nutritional status score for the patients with thoracic esophageal squamous cell carcinoma (ESCC) receiving surgery, and to explore the prognostic impact of long-term survival. Methods: A total of 117 patients who were diagnosed with ESCC from 2010 to 2012 were retrospectively analyzed. They recieved standard curative esophagectomy in the Yangzhou University Affiliated Taixing People's Hospital. The nutritional status and risk score for recruited patients were assessed according to the standard of NRS-2002 tool prior to surgery, and these patients were grouped for further analysis according to the median values of NRS-2002 score. Finally, the relationship between NRS-2002 score and prognosis was analyzed. Results: Patients were classified into two groups, with 45 in the NRS-2002<2.0 group, and 72 cases in the NRS-2002≥2.0, respectively. In the NRS-2002<2.0 group, the 1-, 3-, and 5-year progression-free survival (PFS) rates were 75.6%, 44.4% and 40.0% separately, while in the NRS-2002≥2.0 group, the PFS rates were 61.1%, 6.9% and 4.2% respectively, and the differences were statistically significant (P<0.001). Correspondingly, in the NRS-2002< 2.0 group, the 1-, 3-, and 5-year overall survival (OS) rates were 97.8%, 66.7% and 57.8% separately, while in the NRS-2002≥2.0 group, the OS rates were 91.7%, 33.3% and 16.7% respectively, and the differences were also statistically significant (P<0.001). Univariate analysis showed that N stage, TNM stage and NRS-2002 score were closely related to PFS and OS (P<0.05), and T stage was only associated with OS in patients with thoracic esophageal squamous cell carcinoma (P<0.05). Furthermore, multivariate Cox regression analysis showed that N stage (RR=1.640, 95% CI 1.049-2.565, P=0.030) and NRS-2002 (RR=3.154, 95% CI 1.946-5.113, P<0.001) were independent prognostic factors for PFS in patients with ESCC after surgery. Additionally, pathological differentiation (RR=1.556, 95% CI 1.004-2.440, P=0.041), N stage (RR=1.624, 95% CI 1.017-2.593, P=0.042) and NRS-2002 (RR=3.906, 95% CI2.245-6.795, P<0.001) were independent prognostic factors for OS in ESCC patients following surgery. Conclusion: Preoperative nutritional risk screening NRS-2002 score is an independent prognostic factor in patients with ESCC receiving surgery and could be used as a tool for primary screening for nutritional risk.

Tunable quad-band transmission response, based on single-layer metamaterials

We investigated the electromagnetically induced transparency (EIT)-like effects in planar metamaterials (MMs) at microwave (GHz) frequencies. The specific MMs that were used in this study consist of cut-wire resonator/ring resonator, which achieved the dual EIT-like effects in a single-layer through the bright- and quasi-dark-mode coupling and the lattice mode coupling. In addition, by varying the distance between the two resonators, the quad-band EIT spectral response in the microwave region was obtained, and the group refractive index at the EIT-like resonance of proposed design reached up to 4,000. This study provides the design approach to the multispectral EIT-like effects and might suggest potential applications in a variety of fields, for example, low-loss slow-light device, multiple switching sensor, and other sensing devices.

Involvement of spinal SIRT1 in development of chronic constriction injury induced neuropathic pain in rats

It is known that the epigenetic process of histone acetylation is involved in the neuropathic pain. The aim of this study was to determine whether sirtuin type 1 (SIRT1), an NAD⁺ dependent deacetylase, affected allodynia and hyperalgesia in neuropathic pain. The neuropathic pain model was established by ligature of the right sciatic nerve to induce chronic constriction injury (CCI) in rats. Histone acetyltransferase (HAT) activity was increased and, and histone deacetylase (HDAC) activity was declined in tissue of the spinal dorsa horn in CCI rates by means of enzyme-linked immunosorbent assay (ELISA). The persistent hyperalgesia and allodynia caused by CCI were associated with downregulation of SIRT1 and upregulation of acetylated-H3 (Ac-H3) in tissue of the spinal cord by Western blot assay, which was reversed after intrathecal injection of SIRT1 agonist SRT1720. SRT1720 treatment achieved analgesic through inhibiting the acetylation of nuclear factor kappa B (NF-κB) and blocking the releases of the inflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 by means of Western blot and real-time quantitative PCR (RT-PCR), respectively. Taken together, these data suggest that SIRT1 in the spinal cord plays an important role in the neuropathic pain in the rat model.

An ultrahigh volumetric capacitance of squeezable three-dimensional bicontinuous nanoporous graphene

Graphene with a large specific surface area and high conductivity has a large specific capacitance. However, its volumetric capacitance is usually very low because the restacking of 2D graphene sheets leads to the loss of the large ion-accessible surface area. Here we report squeezable bicontinuous nanoporous nitrogen-doped graphene, which is extremely flexible and can tolerate large volume contraction by mechanical compression without the face-to-face restacking occurring. The compressed nanoporous N-doped graphene with a large ion accessible surface area and high conductivity shows an ultrahigh volumetric capacitance of ∼300 F cm^-3 together with excellent cycling stability and high rate performance.

Molecular genetic map construction and QTL analysis of fruit maturation period in grapevine

In this study, we aimed at finding the genetic regularity of grape maturation period. Early-maturing grapevine, "87-1", was used as the female parent and late-maturing, "9-22", as the male parent, to create an F1 hybrid population. A total of 149 individual plants and their parents were selected as the mapping population. Sequence-related amplified polymorphism and simple-sequence repeat analyses were performed. We performed a linkage analysis and constructed a molecular genetic map. In the obtained map, the female and male parents each covered 19 linkage groups containing 188 and 175 maker loci, respectively. The total map distances for the female and male parents were 1074.5 and 1100.2 cM, respectively, whereas the average genetic distances between each two loci were 5.7 and 7.8 cM, respectively. The interval-mapping method was used in a quantitative trait locus (QTL) analysis for fruit maturation period. A total of 12 QTLs associated with fruit maturation period were detected. These included four QTLs in the male parent genetic map that were located in linkage groups M5, M11, M14-1, and M16, with a 62.6-75.7% rate of contribution of each QTL. Another three QTLs were found in the female parent genetic map, located in linkage groups F6, F14-1, and F18, with a 72.7-77.7% rate of contribution of each QTL. Five more QTLs were detected in the consensus map, located in linkage groups LG11, LG14-1, LG16, LG17, and LG18, with 8.9-75.7% phenotypic variance explained by each QTL.

Quantitative trait locus analysis of grape weight and soluble solid content

A grapevine hybrid population was derived from a crossing of the early-maturing female parent cultivar '87-1' and the late-maturing male parent cultivar '9-22'. A total of 149 plants were selected from the hybrid population as the mapping population, and after sequence-related amplified polymorphism and simple-sequence repeat marker analysis were conducted we constructed molecular genetic maps of the parents. The molecular linkage map of '87-1' had 19 linkage groups that contained 188 markers, with an average interval of 5.7 cM and a total distance of 1074.5 cM; the '9-22' map had 19 linkage groups that contained 175 markers, with an average interval of 7.8 cM and a total distance of 1100.2 cM. The molecular linkage map of both parents had 19 linkage groups that contained 251 markers, with an average interval of 5.0 cM and a total distance of 1264.2 cM. We used the interval mapping method to conduct a quantitative trait locus (QTL) analysis of grape weight and soluble solid content of the mapping population. Six QTLs were related to grape weight, and the average contribution to the phenotypic variance was between 11.3 and 33.0%. Seven QTLs were related to soluble solid content, and the average contribution to the phenotypic variance was between 15.7 and 55.8%.

Species identification and evolutionary inference of the genera Megalobrama and Parabramis (Cyprinidae: Cultrinae) in China

The species boundaries and evolutionary relationships of two closely related genera, Megalobrama and Parabramis, were inferred from the partial mitochondrial cytochrome oxidase subunit I (COI) gene, NADH dehydrogenase subunit 2 (ND2) gene and their concatenated segment. Phylogenetic reconstructions showed that among the three breams, Megalobrama amblycephala and Megalobrama skolkovii are more closely related to each other than either is to Megalobrama terminalis. The taxonomy of M. pellegrini should be reconsidered. The divergence time estimation based on the assumption of a global molecular clock indicated that speciation and dispersal of the two genera might have occurred at approximately Pliocene to Late Pleistocene, due to major paleo-environmental events associated with monsoon evolution and the formation of the Three Gorges of the Yangtze River.

Current progress of research on pharmacologic actions of salvianolic acid B

As one of the main water-soluble composites of Radix Salviae, salvianolic acid B is a phenolic acid ingredient of the Chinese drug, which is rich content in the herb and has strong pharmaceutical activity. It is used to treat cardiocerebral vascular diseases, antagonize hepatic/renal fibrosis, prevent cancer, and promote stem cell proliferation and differentiation. In the researches of its acting mechanisms, rather deepened studies have been carried out for its application on cardiocerebral vascular diseases, but that for others are rather fewer.

Population Structure, Chemotype Diversity, and Potential Chemotype Shifting of Fusarium graminearum in Wheat Fields of Manitoba

This study was to investigate the variation of acetyl ester derivative of DON at 15-position oxygen (15ADON) and acetyl ester derivative of DON at 3-position oxygen (3ADON) chemotypes and potential chemotype shifting of Fusarium graminearum based on the population structure of this species in Manitoba. The study was conducted in 15 locations with wheat cvs. Superb and AC Barrie in Manitoba from 2004 to 2005. Percentages of chemotypes 3ADON and 15ADON of F. graminearum ranged from 0 to 95.7 and 4.3 to 100%, respectively. The 3ADON chemotype was distributed in the southern part of Manitoba and predominant in Morris and Horndean. The two chemotypes almost shared the same percentage in Portage la Prairie. The 15ADON chemotype was predominant in the other locations. Significant gene flow was found among the populations from Sanford, Portage la Prairie, Hamiota, Plumas, Rapid City, and Virden; the populations from Cartier, Rivers, Killarney, and Souris; and the populations from Morris, Kenville, and Dauphin. There were no differences between the populations from two wheat cultivars and two chemotypes. The great variation of chemotype likely resulted from the great genetic diversity of F. graminearum. Sexual recombination, population age, and cropping system could result in genetic and chemotypic diversities. Wheat seed shipment and long-distance spore transportation of F. graminearum potentially caused the genetic migration and chemotype shifting in Manitoba.

Genetic Diversity of Gibberella zeae Isolates from Manitoba

Gibberella zeae (anamorph Fusarium graminearum) causes Fusarium head blight, one of the most important diseases of cereals in the Canadian prairies for the last decade. In 2002, 60 isolates of G. zeae were collected and single spored from naturally infected spikes of wheat from Carman and Winnipeg in Manitoba. These isolates were compared using vegetative compatibility analysis and polymerase chain reaction (PCR)-based sequence related amplified polymorphisms (SRAP). Sixteen vegetative compatibility groups (VCG) were found among the 50 isolates tested. Five VCGs were found in the two locations, five in Carman and six in Winnipeg. Eight SRAP primer pairs amplified 90 polymorphic DNA fragments from 60 isolates and identified 59 distinct haplotypes. Among seven pairs of isolates, each pair from a distinct spike, four had isolates with different VCGs and six comprised different SRAP haplotypes. Principal component analysis and UPGMA separated the dataset into two main groups, each with isolates from both locations. The analysis of molecular variance also revealed that 75 and 20% of the variance was associated with differences among individual isolates and varieties sampled, respectively. Geographic location was not a significant source of variation at P = 0.05 and accounted for only 4% of total variance. A low correlation between VCG and SRAP marker data was detected. This study showed that, although genetic diversity is high among G. zeae isolates, Carman and Winnipeg collections have a similar genetic makeup and are likely part of the same population. The significant proportion of variance accounted by the variety compared with the geographic origin of isolates suggests that seedborne inoculum might have contributed to the genetic diversity within the G. zeae collection under study.

Seasonal and Diurnal Patterns of Spore Dispersal by Leptosphaeria maculans from Canola Stubble in Relation to Environmental Conditions

Seasonal and diurnal patterns of spore dispersal by Leptosphaeria maculans, which causes blackleg disease of canola, were studied in two consecutive field seasons using a 7-day Burkard spore sampler and rotorod impaction spore samplers. Ascospores of L. maculans were trapped from mid-June to the end of July, whereas pycnidiospores were trapped from mid-July until the end of July or early August. Ascospores and pycnidiospores were trapped between 9:00 P.M. and 4:00 A.M., when air temperatures were 13 to 18°C and relative humidity was >80%. Peak ascospore and pycnidiospore dispersal was associated with rain events. Peak ascospore dispersal was found to occur several hours after rainfall ≥2 mm, and ascospore dispersal continued for approximately 3 days after such events. Peak pycnidiospore dispersal occurred during the same hours as rain events. More ascospores and pycnidiospores were carried in the direction of prevailing winds than in other directions. To the south of the inoculated area, the gradients of disease incidence and stem disease severity were -19.2 and -0.8 m^-1, respectively. Disease incidence and stem severity declined by 50% 12.5 and 5.5 m from the inoculated area, respectively. To the north of the inoculated area, the gradients of disease incidence and stem severity were -21.5 and -0.7 m^-1, respectively. Disease incidence and stem severity declined by 50% 14.0 and 5.2 m from the inoculated area, respectively. In 2001, ascospores and pycnidiospores were trapped within 25 m of the inoculated area, whereas pycnidiospores were trapped up to 45 m from the inoculated area.

[Direct determination of selenium and bismuth in antimony and antimony compound by hydride generation-atomic fluorescence spectrometry]

The interference of Sb in determination of Se and Bi in antimony powder and antimony compound has been studied in different acidity, it is found that the interference of antimony has been reduced apparently in high acidity. Simultaneously, according to the difference of hydride generation reaction between Sb5+ and Sb3+, a sensitive and rapid method has been developed and used to determine Se and Bi in real samples. The recovery of the method is 95%-105% for practical samples. Detection limits are 0.00004 x 10(-2) (content) for Se and 0.0001 x 10(-2) mg.L-1 (content) for Bi respectively. The relative standard deviations of Se are 2.4% (content = 0.00169 x 10(-2) mg.L-1) and 5.4% (content = 0.00056 x 10(-2) mg.L-1). The relative standard deviations of Bi are 5.0% (content = 0.00024 x 10(-2) mg.L-1) and 1.3% (content = 0.00229 x 10(-2) mg.L-1). The method has been applied to determination of Se and Bi in practical samples with satisfactory results.

Modulation of CPP32 activity and induction of apoptosis in Human CEM X 174 lymphocytes by heptachlor, a chlorinated hydrocarbon insecticide

Heptachlor is an organochlorine insecticide used worldwide for the control of pests both agriculturally and domestically. Its lipophilic structure allows it to bioaccumulate and pass through the food chain, exposing those who come in contact with it to its tumor promoting and possible carcinogenic effects. As a mechanism of tumor promotion, we explored the possibility of heptachlor suppressing the apoptotic process in human CEM x 174 lymphocytes. In this article, we describe the effect of heptachlor on the activity of the apoptosis protease CPP32. We show that heptachlor by itself was able to stimulate CPP32 activity at relatively high concentrations. When combined with the chemotherapeutic agent doxorubicin, a known CPP32 activator, a dual effect was observed. Low concentrations of heptachlor (5 microM-10 microM) suppressed doxorubicin-induced CPP32 activity, and high concentrations of heptachlor (80 microM-120 microM) augmented it. We also showed that heptachlor alone at relatively high concentrations induced apoptosis-associated changes in CEM x 174 cells including high molecular weight (HMW) DNA cleavage and chromatin condensation. From these results, it appears that heptachlor has tumor promoting-like effects at lower concentrations, and at higher concentrations induces apoptosis as a mechanism of cytotoxicity.

The common nodulation genes of Astragalus sinicus rhizobia are conserved despite chromosomal diversity

The nodulation genes of Mesorhizobium sp. (Astragalus sinicus) strain 7653R were cloned by functional complementation of Sinorhizobium meliloti nod mutants. The common nod genes, nodD, nodA, and nodBC, were identified by heterologous hybridization and sequence analysis. The nodA gene was found to be separated from nodBC by approximately 22 kb and was divergently transcribed. The 2. 0-kb nodDBC region was amplified by PCR from 24 rhizobial strains nodulating A. sinicus, which represented different chromosomal genotypes and geographic origins. No polymorphism was found in the size of PCR products, suggesting that the separation of nodA from nodBC is a common feature of A. sinicus rhizobia. Sequence analysis of the PCR-amplified nodA gene indicated that seven strains representing different 16S and 23S ribosomal DNA genotypes had identical nodA sequences. These data indicate that, whereas microsymbionts of A. sinicus exhibit chromosomal diversity, their nodulation genes are conserved, supporting the hypothesis of horizontal transfer of nod genes among diverse recipient bacteria.

Characterization of Astragalus sinicus rhizobia by restriction fragment length polymorphism analysis of chromosomal and nodulation genes regions

Two hundred and four isolates of rhizobia were sampled from root nodules of Astragalus sinicus grown in rice fields of six southern provinces of China. Genotypic diversity was determined by Southern hybridization using nodDBC genes as a probe, restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S-23S rDNA intergenic spacers (IGS), and plasmid profile. Our results show that rhizobia associated with A. sinicus were very diverse, and 10 genotypes were resolved within the previously identified dominant 16S rDNA type. Diversity levels varied greatly between different geographical locations. The same nod gene genotypes were harbored by distinct chromosomal types, suggesting that lateral plasmid transfer occurred during the evolution process.

The effect of diet on plasma homocysteine concentrations in healthy male subjects

OBJECTIVE

To determine the effect of habitual omnivorous and vegetarian diets on folate and vitamin B12 status and the subsequent effect on homocysteine concentration.

DESIGN

Cross-sectional comparison of free-living habitual meat-eaters and habitual vegetarians.

SETTING

The study was conducted at RMIT University, Melbourne.

SUBJECTS

One hundred and thirty-nine healthy male subjects (vegans n=18, ovolacto vegetarians n=43, moderate meat-eaters n=60 and high meat-eaters n=18) aged 20-55 y who were recruited in Melbourne.

OUTCOME MEASURES

Fasting plasma or serum from each subject was analysed for folate, vitamin B12 and homocysteine concentration. A semi-quantitative Food Frequency Questionnaire was completed by a subset of subjects from each group to determine methionine intake.

RESULTS

The two meat eating groups consumed significantly greater levels of methionine (P<0.001). There was no clear trend in plasma folate status between groups, however the plasma vitamin B12 concentration decreased progressively from the high-meat-eating group to vegans (P<0.05). An inverse trend was observed with plasma homocysteine concentration, with vegans showing the highest levels and high meat eaters the lowest (P<0.05).

CONCLUSIONS

Dietary methionine intake has no observable effect on plasma homocysteine concentration. In habitual diets, where folate intake is adequate, lowered vitamin B12 intake from animal foods leads to depleted plasma vitamin B12 concentration with a concomitant increase in homocysteine concentration. The suggested mechanism is the failure to transfer a methyl group from methyl tetrahydrofolate by vitamin B12 in the remethylation of homocysteine to methionine.

Homocysteine enhances neutrophil-endothelial interactions in both cultured human cells and rats In vivo

Despite intense investigation, mechanisms linking the development of occlusive vascular disease with elevated levels of homocysteine (HCY) are still unclear. The vascular endothelium plays a key role in regulating thrombogenesis and thrombolysis. We hypothesized that vascular lesions in individuals with elevated plasma HCY may be related to a dysfunction of the endothelium triggered by HCY. We investigated the effect of HCY on human neutrophil adhesion to and migration through endothelial monolayers. We also examined the effect of HCY on leukocyte adhesion and migration in mesenteric venules of anesthetized rats. We found that pathophysiological concentrations of HCY in vitro induce increased adhesion between neutrophils and endothelial cells. This contact results in neutrophil migration across the endothelial layer, with concurrent damage and detachment of endothelial cells. In vivo, HCY infused in anesthetized rats caused parallel effects, increasing leukocyte adhesion to and extravasation from mesenteric venules. Our results suggest that extracellular H2O2, generated by adherent neutrophils and/or endothelial cells, is involved in the in vitro endothelial cell damage. The possibility exists that leukocyte-mediated changes in endothelial integrity and function may lead to the vascular disease seen in individuals with elevated plasma HCY.

Four distinct cyclin-dependent kinases phosphorylate histone H1 at all of its growth-related phosphorylation sites

In mammalian cells, up to six serines and threonines in histone H1 are phosphorylated in vivo in a cell cycle dependent manner that has long been linked with chromatin condensation. Growth-associated H1 kinases, now known as cyclin-dependent kinases (CDKs), are thought to be the enzymes responsible for this process. This paper describes the phosphorylation of histone H1 by four different purified CDKs. The four CDKs phosphorylate only the cell cycle specific phosphorylation sites of H1, indicating that they belong to the kinase class responsible for growth-related H1 phosphorylation in vivo. All four CDKs phosphorylate all of the interphase and mitotic-specific H1 sites. In addition to the (S/T)PXK consensus phosphorylation sites, these four CDKs also phosphorylate a mitotic-specific in vivo H1 phosphorylation site that lacks this sequence. There is no site selectivity among the growth-related phosphorylation sites by any of the four CDKs because all four CDKs phosphorylate all relevant sites. The results imply that the cell cycle dependent H1 phosphorylations observed in vivo must involve differential accessibility of H1 sites at different stages of the cell cycle.

Purinergic agonists, but not cAMP, stimulate coupled granule fusion and Cl- conductance in HT29-Cl.16E

Cl- conductance and capacitance were simultaneously measured in the mucin-secreting cell line, HT29-Cl.16E (Cl.16E), and its sister cell line, HT29-Cl.19A (Cl.19A), which lacks mucin granules. Purinergic stimulation by extracellular ATP transiently increased Cl- conductance in both cell lines with similar peak increases of 0.92 and 1.00 nS/pF in Cl.16E and Cl.19A cells, respectively (baseline of 0.08 nS/pF). Cell capacitance increased only in Cl.16E cells (17% above baseline of 22 pF in Cl.16E and 1% above baseline of 18 pF in Cl.19A cells). Wortmannin inhibited the purinergically activated Cl- conductance and capacitance increases in Cl.16E by 50 and 80%, respectively, but had no effects in Cl.19A cells. In Cl.16E cells, adenosine 3',5'-cyclic monophosphate (cAMP) signaling increased Cl- conductance from 0.08 to 0.52 nS/pF without changing capacitance. Cl- secretion in Cl.16E monolayers was additive in response to supramaximal stimulation of purinergic receptors and adenylyl cyclase, even though granule fusion is nine times greater with purinergic than adenylyl cyclase stimulation. In conclusion, 1) wortmannin does not directly inhibit activation of Cl- conductance, 2) at least 50% of purinergically activated Cl- conductance in Cl.16E is associated with granule fusion, and 3) cAMP-activated Cl- conductance is not associated with granules.

Gender differences and other determinants of the rise in plasma homocysteine after L-methionine loading

The methionine load test is widely used to identify subjects with mild homocysteinemia. We studied factors influencing the rise in plasma homocysteine (tHcy) levels following oral methionine loading, after taking into account determinants of the basal level. The study population comprised 522 persons (mean age 53, range 17 to 95; 63% male; 60% with coronary disease). tHcy was measured fasting and 4 h after administration of L-methionine (dose 4 g/m2). The percentage rise in tHcy was greater in females, at younger ages, and with lower serum creatinine. Basal tHcy was lower in those with high levels of serum folate, red cell folate and serum B12; they also showed a greater percentage rise with loading. After adjustment for age, creatinine and serum vitamins the percent rise was greater in females (mean 230%, S.D. 92) than in males (mean 172%, S.D. 71, P < 0.0001). About 1/4 of this effect was explained by the methionine dose, but important independent gender effects remained. When the results of the loading test were compared with an overall reference range, females were systematically labelled as 'high' but comparison with age and gender-specific reference ranges normalised the sex distribution. Our data show that a single L-methionine loading protocol for both sexes is not appropriate. Gender-specific reference ranges should be used to define post-load homocysteinemia and previous studies which have identified a high proportion of females with this trait probably reflect the need for gender specific reference ranges.

Fasting and post-methionine homocyst(e)ine levels in a healthy Australian population

BACKGROUND

Plasma homocyst(e)ine (H[e]) is frequently measured in patients with occlusive vascular disease, but levels vary between populations and between laboratories.

AIMS

We sought to derive reference values for an Australian population over a wide age range.

METHODS

We measured plasma H(e) in the fasting state and after methionine loading in 116 volunteers selected at random from the Hunter districts of the New South Wales electoral roll and in 49 apparently healthy, active subjects recruited from the region's lawn bowling clubs. Reference ranges were derived for both sexes, in three age strata. We collaborated with two international laboratories in standardising our results.

RESULTS

Mean fasting H(e) levels were approximately 2.7 mumol/L higher in men than women, at all ages (95% CI for the difference, 1.2 to 4.1 mumol/L). Levels increased with age (approximately 1.0 mumol/L/decade, 95% CI 0.5 to 1.5) and were correlated with serum creatine (r = 0.48), serum folate (r = -0.30), red cell folate (r = -0.25) and serum B12 (r = -0.31) (all p < 0.001). These results are similar to those reported in other populations.

CONCLUSIONS

We have defined reference ranges for a typical Australian population, following careful laboratory standardisation. H(e) levels must be interpreted with regard to age, sex, renal function and vitamin B12 and folate status.

Imaging objects in tissuelike media with optical tagging and the diffuse photon differential transmittance

In a proof-of-concept experiment, we optically tagged objects embedded in an inhomogeneous and multiple-scattering medium and measured the difference between the transmitted diffuse photons at two optical wave-lengths, one at and the other off a sharp absorption peak of the exogenous contrast agent. We demonstrated that the visibility of tagged objects was significantly enhanced in comparison with that of untagged objects. From our analysis it seems possible to use dual-wavelength differential transmittance spectrometry together with monoclonal-antibody-delivered optical contrast agents to detect tumors as small as 0.1-0.3 cm in size and embedded as deeply as a few centimeters beneath a tissue surface.

Assay of plasma homocysteine: light sensitivity of the fluorescent 7-benzo-2-oxa-1, 3-diazole-4-sulfonic acid derivative, and use of appropriate calibrators

The recognition of homocysteine as a vascular risk factor has led to increased clinical interest in assaying plasma homocysteine concentrations. Our aim was to improve the reliability of a widely used assay based on HPLC of the fluorescent 7-benzo-2-oxa-1, 3-diazole-4-sulfonic acid (SBD) derivative. We found that SBD derivatives of homocysteine, cysteine, and N-acetylhomocysteine were highly unstable in light but essentially stable in the dark for several hours at either 0 degree C or 25 degrees C. As our primary calibrator, we chose homocystine added to human serum for more consistent results than homocysteine or homocystine in an aqueous buffer. N-acetylcysteine was effective as an internal recovery standard. We observed a previously unreported peak with a prolonged elution time in some plasma samples from subjects who had ingested methionine. Our findings suggest improvements in this and other assay procedures for plasma homocysteine.

Assay of plasma homocysteine: light sensitivity of the fluorescent 7-benzo-2-oxa-1, 3-diazole-4-sulfonic acid derivative, and use of appropriate calibrators

The recognition of homocysteine as a vascular risk factor has led to increased clinical interest in assaying plasma homocysteine concentrations. Our aim was to improve the reliability of a widely used assay based on HPLC of the fluorescent 7-benzo-2-oxa-1, 3-diazole-4-sulfonic acid (SBD) derivative. We found that SBD derivatives of homocysteine, cysteine, and N-acetylhomocysteine were highly unstable in light but essentially stable in the dark for several hours at either 0 degree C or 25 degrees C. As our primary calibrator, we chose homocystine added to human serum for more consistent results than homocysteine or homocystine in an aqueous buffer. N-acetylcysteine was effective as an internal recovery standard. We observed a previously unreported peak with a prolonged elution time in some plasma samples from subjects who had ingested methionine. Our findings suggest improvements in this and other assay procedures for plasma homocysteine.

A brief staurosporine treatment of mitotic cells triggers premature exit from mitosis and polyploid cell formation

At any point during the progression of many tumor types, cells can develop a hyperploid DNA content. Hyperploid tumors are significant more aggressive, with a higher growth rate and a poor patient prognosis. Yeast genetics have implicated three important genes involved in DNA ploidy changes: cdc2, cyclin b, and a specific inhibitor of the p34(cdc2)/cyclin B kinase, rum1. Mutations in these genes uncoupled the dependence mitosis on DNA replication in the fission yeast, Saccharomyces pombe. It was proposed that the inactivation of the mitotic kinase complex, p34(cdc2)/cyclin B, induces a G(1), state wherein the cells re-replicate their DNA without an intervening mitosis. We show in this report that treatment of only M phase-arrested mouse cells, with the protein kinase inhibitor staurosporine, induced polyploidy. Nocodazole-arrested metaphase FT210 cells were pulsed with 100 ng/ml of staurosporine for 1 h. This 1-h treatment results in the inhibition of the mitotic p34(cdc2) kinase. The inhibition of the mitotic kinases leads to a reduction in the histone H1 and H3 mitotic-associated phosphorylations, chromosome decondensation and nuclear membrane reformation. When released into normal growth medium, these cells are reset to a G(1)state, re-replicate their DNA without completing mitosis, and become octaploid.

Human homocysteine catabolism: three major pathways and their relevance to development of arterial occlusive disease

Two separate metabolic pathways that methylate homocysteine to methionine are known in humans, utilizing, respectively, 5-methyltetrahydrofolate and betaine as methyl donors. Deficiency of the folate-dependent methylation system is linked to hyperhomocysteinemia. Our data suggest that this deficiency leads to concurrent metabolic down-regulation of homocysteine transsulfuration that may contribute to hyperhomocysteinemia. By contrast, no instances have been reported of hyperhomocysteinemia resulting from deficiencies of betaine-dependent homocysteine methylation. Long-term betaine supplementation of 10 patients, who had pyridoxine-resistant homocystinuria and gross hyperhomocysteinemia due to deficiency of cystathionine beta-synthase activity, caused a substantial lowering of plasma homocysteine, which has now been maintained for periods of up to 13 years. Betaine had to be taken regularly because the effect soon disappeared when treatment was stopped. In conclusion, depressed activity of the transsulfuration pathway may contribute to hyperhomocysteinemia because of primary deficiencies of enzymes of either the transsulfuration or of the folate-dependent methylation pathways. Stimulation of betaine-dependent homocysteine remethylation causes a commensurate decrease in plasma homocysteine that can be maintained as long as betaine is taken.

A ribonucleotide reductase inhibitor, MDL 101,731, induces apoptosis and elevates TRPM-2 mRNA levels in human prostate tumor xenografts

MDL 101,731, (E)2'-fluoromethylene-2'-deoxycytidine, is an irreversible inhibitor of ribonucleotide diphosphate reductase and causes regression of human tumors in nude mouse models. Messenger RNA levels for testosterone-repressed prostatic message-2 (TRPM-2), a transcript that increases in human tumor xenografts undergoing programmed cell death, were analyzed by in situ hybridization. Xenografts derived from a human prostate tumor cell line (PC-3) regressed following treatment with MDL 101,731 and the relative levels of TRPM-2 mRNA increased up to threefold in drug-treated animals. Apoptosis in the tumor xenografts was further indicated by in situ labeling of DNA strand breaks by incorporation of biotinylated-dUTP with terminal deoxynucleotidyl transferase. In vitro, PC-3 cells incubated with MDL 101,731 showed evidence of apoptosis based on flow cytometry and DNA laddering. These data support the hypothesis that MDL 101,731 stimulates programmed cell death in regressing PC-3 xenografts.

Chromosome condensation induced by fostriecin does not require p34cdc2 kinase activity and histone H1 hyperphosphorylation, but is associated with enhanced histone H2A and H3 phosphorylation

Chromosome condensation at mitosis correlates with the activation of p34cdc2 kinase, the hyperphosphorylation of histone H1 and the phosphorylation of histone H3. Chromosome condensation can also be induced by treating interphase cells with the protein phosphatase 1 and 2A inhibitors okadaic acid and fostriecin. Mouse mammary tumour FT210 cells grow normally at 32 degrees C, but at 39 degrees C they lose p34cdc2 kinase activity and arrest in G2 because of a temperature-sensitive lesion in the cdc2 gene. The treatment of these G2-arrested FT210 cells with fostriecin or okadaic acid resulted in full chromosome condensation in the absence of p34cdc2 kinase activity or histone H1 hyperphosphorylation. However, phosphorylation of histones H2A and H3 was strongly stimulated, partly through inhibition of histone H2A and H3 phosphatases, and cyclins A and B were degraded. The cells were unable to complete mitosis and divide. In the presence of the protein kinase inhibitor starosporine, the addition of fostriecin did not induce histone phosphorylation and chromosome condensation. The results show that chromosome condensation can take place without either the histone H1 hyperphosphorylation or the p34cdc2 kinase activity normally associated with mitosis, although it requires a staurosporine-sensitive protein kinase activity. The results further suggest that protein phosphatases 1 and 2A may be important in regulating chromosome condensation by restricting the level of histone phosphorylation during interphase, thereby preventing premature chromosome condensation.

Molecular design of the voltage-dependent, anion-selective channel in the mitochondrial outer membrane

The mitochondrial outer membrane contains numerous copies of a channel protein, VDAC, that is thought to be the main permeability pathway through this membrane for polar molecules and ions. Low-dose electron microscopy has been used to obtain images of two-dimensional crystals of this channel (produced by treating outer membranes from fungal mitochondria with phospholipase A2) embedded in vitreous ice or aurothioglucose. The angular orientation of the channels in the unit cell of one type of array has been determined by rotational correlation analysis. The location of the amino-terminal segment of the protein (which, according to circular dichroism, forms an alpha-helix in nonpolar solvents and detergent solutions) has been determined by labeling arrays with Fab prepared from antibodies directed against residues 1-20. The three-dimensional structure of the channel has been obtained by applying Fourier reconstruction methods to projections of tilted crystals embedded in aurothioglucose, followed by averaging of the three non-symmetry-related channels in the unit cell. The results of this study indicate that the wall of VDAC's lumen has several irregular features (uneven height, grooves) and that the aminoterminal segment extends away from the lumen in this crystalline state.

[Effect of ultrasonic extracting on the extraction rate of baicalin]

The method of extracting baicalin from Scutellaria baicalensis by ultrasound is studied. Compared with that of the decocting process which is usually used in medical industry, the method does not need to heat the medicine and can reduce the extraction time and raise the extraction rate.

Inhibition of histone phosphorylation by staurosporine leads to chromosome decondensation

In mammalian cells, hyperphosphorylation of histone H1 and phosphorylation of histone H3 correlate well with the G2 phase to metaphase condensation of chromosomes, and these phosphorylations most probably have a role in initiating and controlling the entry into mitosis. The protein kinase inhibitor staurosporine has been used to examine the role of H1 and H3 phosphorylations in controlling chromosome condensation in the mouse FM3A cell line. We present evidence that (i) staurosporine inhibits the protein kinases that phosphorylate histone H1 during mitosis, (ii) staurosporine also inhibits the histone H3-specific kinase, (iii) the inhibition of these kinase activities prevent cells from entering mitosis, and (iv) addition of staurosporine to cells already arrested at metaphase by nocodazole causes a rapid dephosphorylation of histones H1 and H3 and the decondensation of the metaphase chromosomes. The results show that the hyperphosphorylation of histone H1 and phosphorylation of histone H3 are required to maintain metaphase chromosomes in their condensed state.

Conformational change in the mitochondrial channel, VDAC, detected by electron cryo-microscopy

Crystalline arrays of the voltage-dependent channel, VDAC, can be produced by treatment of Neurospora mitochondrial outer membranes with phospholipase A2. The membrane crystals undergo a lateral phase transition (lattice contraction) that can be induced by an amphipathic polyanion, which also reduces the channel's gating potential. Electron cryo-microscopy of frozen-hydrated crystals indicates that the mean projected diameters of the channels do not decrease with lattice contraction. Instead, contraction is associated with the disappearance of lateral protein "arms" that normally extend between the channels. A model is presented that explains the changes in channel packing and gating potential in terms of a conformational change involving the movement of a protein "arm" between the bilayer and the channel.

Classification of projection images of crystalline arrays of the mitochondrial, voltage-dependent anion-selective channel embedded in aurothioglucose

Low-dose electron microscopic images have been recorded from membrane crystals of the mitochondrial, voltage-dependent anion-selective channel, embedded in aurothioglucose. There is considerable variation in the high-resolution detail present in correlation averages computed from these images. Correspondence analysis reveals three classes of "control" averages, with main components of variation involving projected size of the pores and density modulations around the pores and in the corners of the unit cells away from the pores. Pretreatments that affect the functional state of the channel also affect the array averages. In particular, there appears to be a general correlation between the expected effector-induced state (i.e., open and closed) and the projected diameter of the channel lumens in the crystalline arrays.

Binding of a synthetic targeting peptide to a mitochondrial channel protein

Membrane crystals of the mitochondrial outer membrane channel VDAC (porin) from Neurospora crassa were incubated with a 20-amino-acid synthetic peptide corresponding to the N-terminal targeting region of subunit IV of cytochrome oxidase. The peptide caused disordering and contraction of the crystal lattice of the membrane arrays. Also, new stain-excluding features were observed on the peptide-treated arrays which most likely correspond to sites at which the peptide accumulates. The stain exclusion zones associated with binding of the targeting peptide (and with binding of apocytochrome c in an earlier study) have been localized on a two-dimensional density map of frozen-hydrated, crystalline VDAC previously obtained by cryo-electron microscopy. The results indicate that both the peptide and cytochrome c bind to protein "arms" which extend laterally between the channel lumens. The finding that imported polypeptides bind to a specific region of the VDAC protein implicates this channel in the process by which precursor proteins are recognized at and translocated across the mitochondrial outer membrane.

Interaction between the VDAC channel and a polyanionic effector. An electron microscopic study

The conductance of the voltage-dependent mitochondrial outer membrane channel is modulated by a synthetic anionic polymer. When added to suspensions of membrane crystals of the channel, the polyanion caused disordering of the usual parallelogram array and increased occurrence of a contracted form of the array. Correlation averages obtained from electron microscopic images of the channel crystals indicated a narrowing of the projected channel lumen in the presence of the polyanion and the appearance of new, narrow zones of stain exclusion on the outside of the channel. These effects are interpreted in terms of possible conformational changes induced in the channel by binding of the polyanion.

Chromatin aggregation depends on the anion species of the salts

The effects of anions on chromatin aggregation may be classified into three categories. First, monovalent anions, glutamate, acetate, chloride, and thiocyante, follow the lyotropic series in their effects on both H1 histone displacement and chromatin aggregation. Second, alkyl carboxylates and dicarboxylates differ in their ability to induce chromatin aggregation depending on charge density, suggesting possible interference by bulky alkyl chains with neutralization (screening) of closely spaced positive protein charges. Third, the multivalent anions, citrate3- and SO4(2-), bind tightly to histone and disrupt nucleosomes and thus interfere with chromatin aggregation. Substantial differences in chromatin aggregation were observed with different species of anions. At salt concentrations of 0-500 mN and pH 7.0, as much as 70% of the chromatin could be induced to aggregate by monosodium glutamate and sodium acetate, whereas only 10% or less was precipitated by NaSCN, Na2SO4, and Na3citrate. The physiological anion composition of the nucleus is not known; however, the anion effects discussed in the present work suggest a potential for regulation of chromatin condensation in higher eukaryotes.

Chromatin aggregation changes substantially as pH varies within the physiological range

In vitro at least, changes of pH within the physiological range are important in regulating chromatin aggregation. The extent of aggregation was shown to depend substantially on pH as well as on salt. In the absence of salt and in all of the salt conditions tested as the pH was increased, less and less chromatin was aggregated. The aggregation of half the chromatin in the presence of 0 mM NaCl, 150 mM NaCl, 150 mM NaCl and 1 mM MgCl2, and 2 mM MgCl2 was observed at pH 5.4, 6.0, 7.0, and 8.3, respectively. In 150 mM NaCl, 1 mM MgCl2, chromatin aggregation decreased from 86 to 63% as the pH was changed from 5.9 to 6.8, which is the same pH change reported to occur between interphase and mitosis. H1 dissociation from chromatin was also found to be pH dependent.