Biology subjects

Zeng, Y.

Publications and source records attributed to Zeng, Y..

204 records · Page 12Linked to original sources

bioRxiv2017

Oxford Nanopore sequencing in a research-based undergraduate course

BackgroundNanopore sequencing is a third generation genomic sequencing method that offers real time sequencing of DNA samples. Nanopore sequencing is an excellent tool for teaching because it involves cutting-edge sequencing methods and also helps students to develop a research mindset, where students can learn to identify and resolve problems that arise during an experiment.\n\nResultsWe, as a group of undergraduate biology students, were able to use nanopore sequencing to analyze a sample of pupfish DNA. We were able to accomplish this without computer science backgrounds and only some basic DNA extraction training. Although there were issues, such as inconsistent results across runs, we found it useful as a research learning experience and an application of the skills we learned.\n\nConclusionsAs students, it was exciting to be able to experience this technology first hand and apply what we learned in the classroom. Nanopore sequencing holds potential for DNA sequencing of large fragments in real time. It allows students to be acquainted with novel technologies and the theories behind them. However, as with all new techniques, it does not have the same established support, and when students run into difficulties while using nanopore sequencing, it is often difficult to identify what went wrong.

genomics↗

bioRxiv2017

Genetic and environmental determinants of stressful life events and their overlap with depression and neuroticism

BackgroundStressful life events (SLEs) and neuroticism are risk factors for major depressive disorder (MDD). However, SLEs and neuroticism are heritable traits that are correlated with genetic risk for MDD. In the current study, we sought to investigate the genetic and environmental contributions to SLEs in a large family-based sample, and quantify any genetic overlap with MDD and neuroticism.\n\nMethodsA subset of Generation Scotland: the Scottish Family Health Study, consisting of 9618 individuals comprise the present study. We estimated the heritability of SLEs using pedigree-based and molecular genetic data. The environment was assessed by modelling familial, couple and sibling components. Using polygenic risk scores (PRS) and LD score regression we analysed the genetic overlap between MDD, neuroticism and SLEs.\n\nResultsPast 6-month life events were positively correlated with lifetime MDD status ({beta}=0.21, r2=1.1%, p=2.5 x 10-25) and neuroticism ({beta} =0.13, r2=1.9%, p=1.04 x 10-37). Common SNPs explained 8% of the variance in personal life events (those directly affecting the individual) (S.E.=0.03, p=9 x 10-4). A significant effect of couple environment accounted for 13% (S.E.=0.03, p=0.016) of variation in SLEs. PRS analyses found that individuals with higher PRS for MDD reported more SLEs ({beta} =0.05, r2=0.3%, p=3 x 10-5). LD score regression demonstrated genetic correlations between MDD and both SLEs (rG=0.33, S.E.=0.08) and neuroticism (rG=0.15, S.E.=0.07).\n\nConclusionsThese findings suggest that SLEs are partially heritable and this heritability is shared with risk for MDD and neuroticism. Further work should determine the causal direction and source of these associations.

genetics↗

bioRxiv2017

A mouse model of necrotic biliary pancreatitis induced by combining gallstone formation and ligation of the biliary-pancreatic duct

ObjectiveThe aim of the present investigation is to develop a mouse model of biliary pancreatitis with characteristics of both gallstone formation and pancreatitis, mimicking the human etiology and pathphysiological character.\n\nDesignMale C57BL/6 mice were fed with chow, high fat/cholesterol and lithogenic diet for 12 weeks respectively. Laparotomy was done followed by ligation of pancreatic duct (PD), bile duct and pancreatic duct (BPD), or sham operation.\n\nResultsLittle or no evidence of pancreatitis was observed in PD group of mice fed with chow or high fat/cholesterol diet, or in the tail of pancreata removed from animals fed with lithogenic diet. In the head of pancreas, pancreas damage was dramatically more severe in the lithogenic group. When bile reflux was blocked by BPD, pancreas damage markedly reduced to level of chow diet group. The lithogenic diet group also developed significantly more severe multi organ dysfunction syndrome (MODS) in the lung, kidney and liver. The severity of pancreatitis is associated with persistent high bile level of cholesterol and bile acid after obstruction of the biliary-pancreatic duct. Cholesterol crystal aggravated injury of pancreatic acinar cells caused by taurocholate. After obstruction of the biliary-pancreatic duct, in the lithogenic diet group, liver Abcg8 and Cyp7a1 was up-regulated, compared to the control group.\n\nConclusionWe developed a mouse model of severe biliary pancreatitis in both local pancreas damage and MODS. This model provides a sound explanation for the Opie theory dilemma and a potential therapeutical direction in clinical practice as well.\n\nSummary statementA biliary pancreatitis has characters of both gallstone and pancreatitis, mimicking human etiology and pathophysiology, which gave a clear answer to the long time Opie theory dilemma.

pathology↗

bioRxiv2017

The Stratification Of Major Depressive Disorder Into Genetic Subgroups

Depression is a common and clinically heterogeneous mental health disorder that is frequently comorbid with other diseases and conditions. Stratification of depression may align sub-diagnoses more closely with their underling aetiology and provide more tractable targets for research and effective treatment. In the current study, we investigated whether genetic data could be used to identify subgroups within people with depression using the UK Biobank. Examination of cross-locus correlations was used to test for evidence of subgroups by examining whether there was clustering of independent genetic variants associated with eleven other complex traits and disorders in people with depression. We found evidence of a subgroup within depression using age of natural menopause variants (P = 1.69 x 10-3) and this effect remained significant in females (P = 1.18 x 10-3), but not males (P = 0.186). However, no evidence for this subgroup (P > 0.05) was found in Generation Scotland, iPSYCH, a UK Biobank replication cohort or the GERA cohort. In the UK Biobank, having depression was also associated with a later age of menopause (beta = 0.34, standard error = 0.06, P = 9.92 x 10-8). A potential age of natural menopause subgroup within depression and the association between depression and a later age of menopause suggests that they partially share a developmental pathway.

genetics↗

bioRxiv2017

Genome-Wide Meta-Analyses Of Stratified Depression In Generation Scotland And UK Biobank

Few replicable genetic associations for Major Depressive Disorder (MDD) have been identified. However recent studies of depression have identified common risk variants by using either a broader phenotype definition in very large samples, or by reducing the phenotypic and ancestral heterogeneity of MDD cases. Here, a range of genetic analyses were applied to data from two large British cohorts, Generation Scotland and UK Biobank, to ascertain whether it is more informative to maximize the sample size by using data from all available cases and controls, or to use a refined subset of the data - stratifying by MDD recurrence or sex. Meta-analysis of GWAS data in males from these two studies yielded one genome-wide significant locus on 3p22.3. Three associated genes within this region (CRTAP, GLB1, and TMPPE) were significantly associated in subsequent gene-based tests. Meta-analyzed MDD, recurrent MDD and female MDD were each genetically correlated with 6 of 200 health-correlated traits, namely neuroticism, depressive symptoms, subjective well-being, MDD, a cross-disorder phenotype and Bipolar Disorder. Meta-analyzed male MDD showed no statistically significant correlations with these traits after correction for multiple testing. Whilst stratified GWAS analysis revealed a genome-wide significant locus for male MDD, the lack of independent replication, the equivalent SNP-based heritability estimates and the consistent pattern of genetic correlation with other health-related traits suggests that phenotypic stratification in currently available sample sizes is currently weakly justified. Based upon existing studies and our findings, the strategy of maximizing sample sizes is likely to provide the greater gain.

genetics↗

bioRxiv2017

Assessment of the World Largest Afforestation Program: Success, Failure, and Future Directions

The Three-North Afforestation Program (TNAP), initiated in 1978 and scheduled to be completed in 2050, is the worlds largest afforestation project and covers 4.07 x 106 km2 (42.4%) of China. We systematically assessed goals and outcomes of the first 30 years of the TNAP using high-resolution remote sensing and ground survey data. With almost 23 billion dollars invested between 1978 and 2008, the forested area within the TNAP region increased by 1.20 x 107 ha, but the proportion of high quality forests declined by 15.8%. The establishment of shelterbelts improved crop yield by 1.7%, much lower than the 5.9% expected once all crop fields are fully protected by shelterbelts. The area subjected to soil erosion by water decreased by 36.0% from 6.72 x 107 to 4.27 x 107 ha; the largest reductions occurred in areas where soil erosion had been most severe and forests contributed more than half of this improvement. Desertification area increased from 1978 to 2000 but decreased from 2000 to 2008; the 30-year net reduction was 13.0% (4.05x106 ha), with 8.0% being accounted for by afforestation in areas with only slight, prior desertification. In addition to its direct impacts, the TNAP has enhanced peoples awareness of environmental protection and attracted consistent attention and long-term commitment from the Chinese government to the restoration and protection of fragile ecosystems in the vast Three-North region. The significant decline in forest quality, limited success in reducing desertification, and low coverage of shelterbelts are aspects of the TNAP in need of re-assessment, and additional ca. 34 billion dollars will be needed to ensure the completion of the TNAP.

ecology↗