A novel plant gene essential for meiosis is related to the human CtIP and the yeast COM1/SAE2 gene

Obligatory homologous recombination (HR) is required for chiasma formation and chromosome segregation in meiosis I. Meiotic HR is initiated by DNA double-strand breaks (DSBs), generated by Spo11, a homologue of the archaebacterial topoisomerase subunit Top6A. In Saccharomyces cerevisiae, Rad50, Mre11 and Com1/Sae2 are essential to process an intermediate of the cleavage reaction consisting of Spo11 covalently linked to the 5' termini of DNA. While Rad50 and Mre11 also confer genome stability to vegetative cells and are well conserved in evolution, Com1/Sae2 was believed to be fungal-specific. Here, we identify COM1/SAE2 homologues in all eukaryotic kingdoms. Arabidopsis thaliana Com1/Sae2 mutants are sterile, accumulate AtSPO11-1 during meiotic prophase and fail to form AtRAd51 foci despite the presence of unrepaired DSBs. Furthermore, DNA fragmentation in AtCom1 is suppressed by eliminating AtSPO11-1. In addition, AtCOM1 is specifically required for mitomycin C resistance. Interestingly, we identified CtIP, an essential protein interacting with the DNA repair machinery, as the mammalian homologue of Com1/Sae2, with important implications for the molecular role of CtIP.     

Sepsis Associated Encephalopathy Studied by MRI and Cerebral Spinal Fluid S100B Measurement

The pathogenesis of sepsis associated encephalopathy (SAE) is not yet clear: the blood–brain barrier (BBB) disruption has been indicated among the possible causative mechanisms. S100B, a calcium binding protein, originates in the central nervous system but it can be also produced by extra-cerebral sources; it is passively released from damaged glial cells and neurons; it has limited passage through the BBB. We aimed to demonstrate BBB damage as part of the pathogenesis of SAE by cerebral spinal fluid (CSF) and serum S100B measurements and by magnetic resonance imaging (MRI). This paper describes four septic patients in whom SAE was clinically evident, who underwent MRI and S100B measurement. We have not found any evidence of CSF-S100B increase. Serum S100B increase was found in three out of four patients. MRI did not identify images attributable to BBB disruption but vasogenic edema, probably caused by an alteration of autoregulation, was diagnosed. S100B does not increase in CSF of septic patients; S100B increase in serum may be due to extracerebral sources and does not prove any injury of BBB. MRI can exclude other cerebral pathologies causing brain dysfunction but is not specific of SAE. BBB damage may be numbered among the contributors of SAE, which aetiology is certainly multifactorial: an interplay between the toxic mediators involved in sepsis and the indirect effects of hyperthermia, hypossia and hypoperfusion.     

海金沙草总黄酮提取工艺的响应面优化

为了提高海金沙草总黄酮提取效率,运用了Plackett-Burman试验设计、爬陡坡试验和Box-Behnken设计对提取工艺进行了响应面优化试验。利用Plackett-Burman对影响总黄酮提取的诸多相关因素进行了评价并成功筛选出主效应因子,即提取时间、提取温度和乙醇浓度。在Plackett-Burman设计基础上,根据主效应因子作用大小与方向进行了爬陡坡试验。最后用Box-Behnken响应面技术优化了总黄酮提取工艺并建立了关键影响产量的二次多项式数学模型,解模型逆矩阵得最优解(优化方案),即提取温度X1=45.45℃,乙醇体积分数X2=47.1%、提取时间X3=84.8 min。模型预测结果为0.433 mg.L-1,验证试验结果为0.428±0.004 mg.L-1(n=3)。     

Gene therapy for PIDs: Progress,pitfalls and prospects

Substantial progress has been made in the past decade in treating several primary immunodeficiency disorders (PIDs) with gene therapy. Current approaches are based on ex-vivo transfer of therapeutic transgene via viral vectors to patient-derived autologous hematopoietic stem cells (HSCs) followed by transplantation back to the patient with or without conditioning. The overall outcome from all the clinical trials targeting different PIDs has been extremely encouraging but not without caveats. Malignant outcomes from insertional mutagenesis have featured prominently in the adverse events associated with these trials and have warranted intense pre-clinical investigation into defining the tendencies of different viral vectors for genomic integration. Coupled with issues pertaining to transgene expression, the therapeutic landscape has undergone a paradigm shift in determining safety, stability and efficacy of gene therapy approaches. In this review, we aim to summarize the progress made in the gene therapy trials targeting ADA-SCID, SCID-X1, CGD and WAS, review the pitfalls, and outline the recent advancements which are expected to further enhance favourable risk benefit ratios for gene therapeutic approaches in the future.     

iRSpot-DTS: Predict recombination spots by incorporating the dinucleotide-based spare-cross covariance information into Chou's pseudo components

Meiotic recombination plays an important role in the process of genetic evolution. Previous researches have shown that the recombination rates provide important information about the mechanism of recombination study. However, at present, most methods ignore the hidden correlation and spatial autocorrelation of the DNA sequence. In this study, we proposed a predictor called iRSpot-DTS to identify hot/cold spots based on the benchmark datasets. We proposed a feature extraction method called dinucleotide-based spatial autocorrelation(DSA) which can incorporate the original DNA properties and spatial information of DNA sequence. Then it used t-SNE method to remove the noise which outperformed PCA. Finally, we used SAE softmax classifier to do classification which is based on networks and can get more hidden information of DNA sequence, our iRSpot-DTS achieved remarkable performance. Jackknife cross validation tests were done on two benchmark datasets. We achieved state-of-the-art results with 96.61% overall accuracy(OA), 93.16% Matthews correlation coefficient (MCC) and over 95% in Sn and Sp which are the best in this state.     

Sumoylation of SAE2 C Terminus Regulates SAE Nuclear Localization

SUMOylation occurs predominantly in the nucleus, but non-nuclear proteins can also be SUMOylated. It is unclear how intracellular trafficking of the SUMOylation enzymes is regulated to catalyze SUMOylation in different cellular compartments. Here we report that the SAE2 subunit of human SUMO activation enzyme (SAE) underwent rapid nucleocytoplasmic shuttling and its nuclear accumulation depended on SUMO modification at the C terminus. The SUMOylation sites included three Lys residues on the bipartite nuclear localization sequence (NLS) and two Lys residues outside of but adjacent to the NLS, and their SUMOylation was catalyzed by Ubc9. Because SAE2 forms a tight heterodimer with SAE1 and it controls the trafficking of the heterodimer, this study has identified the mechanism used to localize SAE to the nucleus. Similar mechanisms are likely to exist for other proteins that depend on SUMOylation for nuclear localization.     

Nitrogen and fungicide applications against Erysiphe cruciferarum affect quality components of oilseed rape

Oilseed rape (Brassica napus L.) is one of the most important oilseed crops in temperate climates. Erysiphe cruciferarum is an important disease of oilseed rape and causes crop loss in warmer areas of Europe. The research investigated the effect of nitrogen fertilizer and fungicidal treatment against powdery mildew infection caused by E. cruciferarum of oilseed rape on seed components, including protein, oil, oleic acid, linolenic acid and undesirable substances such as sinapic acid esters (SAE) and glucosinolates (GSL), using near infrared spectroscopy (NIRS). Five susceptible oilseed rape varieties were employed in this research using four treatment groups: no nitrogen fertilization and no fungicidal treatment (N₀–F₀); no nitrogen fertilization but fungicidal treatment (N₀–F₁); and nitrogen fertilization but no fungicidal treatment (N₁–F₀); nitrogen fertilization and fungicidal treatment (N₁–F₁). Nitrogen fertilization increased the protein, but lowered the oil content, of the seeds. Fungicidal treatments significantly increased oil contents in all varieties tested, however reduced protein levels in fertilized and non-fertilized plots. The level of linolenic acid did not change significantly in any plots of any treatment combinations; a similar result was observed in the level of oleic acid in most of the genotypes. Nitrogen fertilization increased GSL and SAE levels, whereas fungicidal treatment had no effect. Our findings demonstrated that nitrogen fertilization can markedly influence some quality parameters in oilseed rape; however, the application of fungicides reduced side effects of nitrogen fertilizer and resulted a reduction on GSL, SAE and protein contents but an increase on total oil and oleic acid contents.     

Gene therapy of primary T cell immunodeficiencies

Gene therapy of severe combined immunodeficiencies has been proven to be effective to provide sustained correction of the T cell immunodeficiencies. This has been achieved for 2 forms of SCID, i.e SCID-X1 (γc deficiency) and adenosine deaminase deficiency. Occurrence of gene toxicity generated by integration of first generation retroviral vectors, as observed in the SCID-X1 trials has led to replace these vectors by self inactivated (SIN) retro(or lenti) viruses that may provide equivalent efficacy with a better safety profile. Results of ongoing clinical studies in SCID as well as in other primary immunodeficiencies, such as the Wiskott Aldrich syndrome, will be thus very informative.