年龄增长对GRK5基因缺陷小鼠海马内肿胀轴突丛形成与积累的影响

目的研究G蛋白偶联受体（G protein-coupled receptors）激酶5（GPCR kinase-5,GRK5）基因缺陷和老化交互作用对阿尔茨海默病（Alzheimer＇s disease,AD）早期的病理改变-海马内肿胀轴突丛（swollen axonal clusters,SACs）出现和积累的影响。方法选取5、6、7、9、12～13、18—19月龄雌性GRK5基因敲除小鼠（GRK5 Knockout,GRK5KO）作为观察对象,另选取年龄匹配的雌性野生型（wild type,WT）小鼠为对照,每个年龄段GRK5KO和WT小鼠各4只。用抗人神经原纤维缠结（neurofibrillary tangles,NFTs）特异性抗体的免疫荧光染色方法观察海马内SACs的变化。结果所有小鼠随着年龄增长,海马内SACs逐渐增加;GRKSKO小鼠组海马内NFT^＋ SACs数量较WT型小鼠组显著增加（P〈0．01）;双因素方差分析显示遗传性GRK5基因缺陷和老化双因素对海马内NFT^＋SACs的影响有显著协同效应（P〈0．01）。结论在促进早期AD病理发生的过程中,GRK5缺陷和老化双因素共同加剧了雌性GRKSKO小鼠海马内SACs的形成与积累。     

QTL Mapping of Downy Mildew Resistance in an Introgression Line Derived from Interspecific Hybridization Between Cucumber and Cucumis hystrix

Downy mildew (DM), caused by Pseudoperonospora cubensis (Berk. & M.A. Curtis) Rostovzev, is a worldwide major disease of cucumbers (Cucumis sativus L.). By screening 10 introgression lines (ILs) derived from interspecific hybridization between cucumber and the wild Cucumis, C. hystrix, through a whole plant assay, one introgression line (IL52) was identified with high DM‐resistance. IL52 was further used as a resistant parent to make an F₂ population with ‘changchunmici’ (susceptible parent). The F₂ population (300 plants) was investigated for DM‐yellowing, DM‐necrosis and DM‐resistance in the adult stage. A genetic map spanning 642.5 cM with 104 markers was constructed and used for QTL analysis from the population. Three QTL regions were identified on chromosome 5 and chromosome 6. By interval mapping analysis, two QTLs for DM‐resistance were determined on chromosome 5 (DM_5.1 and DM_5.2), which explained 17.9% and 14.2% of the variation, respectively. QTLs for DM‐yellowing were in the same regions as DM‐resistance. For DM‐necrosis, by interval mapping analysis, one QTL was determined on chromosome 5 (Necr_5.1) that explained 18.3% of the variation and one on chromosome 6 (Necr_6.1) that explained 13.9% of the variation. Our results indicated that the identification of molecular markers linked to the QTLs could be further applied for marker‐assisted selection (MAS) of downy mildew resistance in cucumber.     

Immunomodulatory Effects of Escherichia coli ATCC 25922 on Allergic Airway Inflammation in a Mouse Model

Background

Hygiene hypothesis demonstrates that the lack of microbial exposure would promote the development of allergic airway disease (AAD). Therefore, the gut microbiota, including Escherichia coli (E. coli), would probably offer a potential strategy for AAD.

Objective

To investigate whether E. coli infection is able to suppress the induction of AAD and to elucidate the underlying mechanisms.

Methods

Nonpathogenic E. coli ATCC 25922 was infected by gavage before AAD phase in three patterns: 10⁸ or 10⁶ CFU in neonates or 10⁸ CFU in adults. Then mice were sensitized and challenged with ovalbumin (OVA) to induce allergic inflammation in both the upper and lower airways. Hallmarks of AAD, in terms of eosinophil infiltration and goblet cell metaplasia in subepithelial mucosa, Th2 skewing of the immune response, and levels of T regulate cells (Tregs), were examined by histological analysis, ELISA, and flow cytometry, respectively.

Results

E. coli, especially neonatally infected with an optimal dose, attenuated allergic responses, including a decrease in nasal rubbing and sneezing, a reduction in eosinophil inflammation and goblet cell metaplasia in subepithelial mucosa, decreased serum levels of OVA-specific IgE, and reduced Th2 (IL-4) cytokines. In contrast, this effect came with an increase of Th1 (IFN-r and IL-2) cytokines, and an enhancement of IL-10-secreting Tregs in paratracheal lymph nodes (PTLN).

Conclusion

E. coli suppresses allergic responses in mice, probably via a shift from Th1 to Th2 and/or induction of Tregs. Moreover, this infection is age- and dose-dependent, which may open up novel possibilities for new therapeutic interventions.     

Promoter Hypermethylation of ARID1A Gene Is Responsible for Its Low mRNA Expression in Many Invasive Breast Cancers

ARID1A (AT-rich interactive domain 1A) has recently been identified as a tumor suppressor gene. Its mRNA expression is significantly low in many breast cancers; this is often associated with more aggressive phenotypes. However, the underlying molecular mechanism for its low expression has not been fully understood. This study was undertaken to evaluate the contribution of gene copy number variation, mutations, promoter methylation and histone modification to ARID1A’s low expression. 38 pairs of breast invasive ductal carcinomas and their normal breast tissue counterparts from the same patients were randomly selected for gene expression and copy number variation detection. Promoter methylation and histone modification levels were evaluated by MeDIP-qPCR and ChIP-qPCR, respectively. PCR product Sanger sequencing was carried out to detect the exon mutation rate. Twenty-two out of 38 invasive ductal carcinomas in the study (57.9%) revealed ARID1A mRNA low expression by realtime RT-PCR. The relative promoter methylation level was, significantly higher in ARID1A mRNA low expression group compared with its high expression group (p<0.001). In the low expression group, nineteen out of 22 invasive ductal carcinomas (86.4%) exhibited ARID1A promoter hypermthylation. In addition, the promoter hypermethylation was accompanied with repressive histone modification (H3K27Me3). Although five out of 38 invasive ductal carcinomas (13.2%) exhibited loss of ARID1A gene copy number by realtime PCR and nine exon novel mutations are seen from eight out of 33 invasive ductal carcinomas (24.2%), there was no statistically significant difference in both ARID1A mRNA low and high expression groups (p = 0.25,and p = 0.68, respectively). We demonstrate that promoter hypermethylation was the main culprit for ARID1A mRNA low expression in invasive ductal carcinomas. The influence of mutation and copy number variation on the expression were statistically insignificant at mRNA level, and were, therefore, not considered the main causes for ARID1A mRNA low expression in invasive breast cancer.     

Heritability of eleven metabolic phenotypes in Danish and Chinese twins: A cross‐population comparison

Objectives : A twin‐based comparative study on the genetic influences in metabolic endophenotypes in two populations of substantial ethnic, environmental, and cultural differences was performed. Design and Methods : Data on 11 metabolic phenotypes including anthropometric measures, blood glucose, and lipids levels as well as blood pressure were available from 756 pairs of Danish twins (309 monozygotic and 447 dizygotic twin pairs) with a mean age of 38 years (range: 18‐67) and from 325 pairs of Chinese twins (183 monozygotic and 142 dizygotic twin pairs) with a mean age of 40.5 years (range: 18‐69). Twin modeling was performed on full and nested models with the best fitting models selected. Results : Heritability estimates were compared between Danish and Chinese samples to identify differential genetic influences on each of the phenotypes. Except for hip circumference, all other body measures exhibited similar heritability patterns in the two samples with body weight showing only a slight difference. Higher genetic influences were estimated for fasting blood glucose level in Chinese twins, whereas the Danish twins showed more genetic regulation over most lipids phenotypes. Systolic blood pressure was more genetically controlled in Danish than in Chinese twins. Conclusions : Metabolic endophenotypes show disparity in their genetic determinants in populations under distinct environmental conditions.     

Cost-Effectiveness Comparison of Genechip and Conventional Drug Susceptibility Test for Detecting Multidrug-Resistant Tuberculosis in China

Background

Genechip (CapitalBio, Beijing, China) is a system for diagnosing resistance to rifampin and isoniazid, which shows high efficiency in detecting drug-resistant tuberculosis. Here, we firstly evaluated the costs of Genechip for detecting the drug susceptibility of Mycobacterium tuberculosis, compared to conventional drug susceptibility test (DST) in laboratories in China.

Methodology/Principal Findings

Data on the costs of the two tests were collected at four hospitals. Costs were calculated using the essential factor cost calculation method. The costs of diagnosing a single case of multidrug-resistant tuberculosis (MDR-TB) using Genechip and DST were US$22.38 and $53.03, respectively. Taking into account the effect on costs from failure of a certain number of tests to accurately diagnose MDR-TB, the costs of Genechip and DST increased by 17.65% and 5.22%, respectively. The cost of both tests decreased with the increasing prevalence of MDR-TB disease, and the cost of Genechip at a sensitivity of more than 50% was lower than that of DST. When price of Genechip was varied to 50%, 80%, 150%, and 200% of the original price, the cost of Genechip at sensitivities of more than 30%, 40%, 60%, and 70%, respectively, was also lower than that of DST.

Conclusions/Significance

This study showed that Genechip was a more cost-effective method of diagnosing MDR-TB compared to conventional DST.     

The Role of Physical Activity in Harm Reduction among Betel Quid Chewers from a Prospective Cohort of 419,378 Individuals

ObjectiveTo assess the benefits of regular exercise in reducing harms associated with betel quid (BQ) chewing.MethodsThe study cohort, 419,378 individuals, participated in a medical screening program between 1994 and 2008, with 38,324 male and 1,495 female chewers, who consumed 5–15 quids of BQ a day. Physical activity of each individual, based on “MET-hour/week”, was classified as “inactive” or “active”, where activity started from a daily 15 minutes/day or more of brisk walking (≥3.75 MET-hour/week). Hazard ratios for mortality and remaining years in life expectancy were calculated.ResultsNearly one fifth (18.7%) of men, but only 0.7% of women were chewers. Chewers had a 10-fold increase in oral cancer risk; and a 2-3-fold increase in mortality from lung, esophagus and liver cancer, cardiovascular disease, and diabetes, with doubling of all-cause mortality. More than half of chewers were physically inactive (59%). Physical activity was beneficial for chewers, with a reduction of all-cause mortality by 19%. Inactive chewers had their lifespan shortened by 6.3 years, compared to non-chewers, but being active, chewers improved their health by gaining 2.5 years. The improvement, however, fell short of offsetting the harms from chewing.ConclusionsChewers had serious health consequences, but being physically active, chewers could mitigate some of these adverse effects, and extend life expectancy by 2.5 years and reduce mortality by one fifth. Encouraging exercise, in addition to quitting chewing, remains the best advice for 1.5 million chewers in Taiwan.     

A Puzzle Unsolved: Failure to Observe Different Effects of God and Religion Primes on Intergroup Attitudes

Religious priming has been found to have both positive and negative consequences, and recent research suggests that the activation of God-related and community-related religious cognitions may cause outgroup prosociality and outgroup derogation respectively. The present research sought to examine whether reminders of God and religion have different effects on attitudes towards ingroup and outgroup members. Over two studies, little evidence was found for different effects of these two types of religious primes. In study 1, individuals primed with the words “religion”, “God” and a neutral control word evaluated both ingroup and outgroup members similarly, although a marginal tendency towards more negative evaluations of outgroup members by females exposed to religion primes was observed. In study 2, no significant differences in attitudes towards an outgroup member were observed between the God, religion, and neutral priming conditions. Furthermore, the gender effect observed in study 1 did not replicate in this second study. Possible explanations for these null effects are discussed.     

Kinetic Characterization of 100 Glycoside Hydrolase Mutants Enables the Discovery of Structural Features Correlated with Kinetic Constants

The use of computational modeling algorithms to guide the design of novel enzyme catalysts is a rapidly growing field. Force-field based methods have now been used to engineer both enzyme specificity and activity. However, the proportion of designed mutants with the intended function is often less than ten percent. One potential reason for this is that current force-field based approaches are trained on indirect measures of function rather than direct correlation to experimentally-determined functional effects of mutations. We hypothesize that this is partially due to the lack of data sets for which a large panel of enzyme variants has been produced, purified, and kinetically characterized. Here we report the k_cat and K_M values of 100 purified mutants of a glycoside hydrolase enzyme. We demonstrate the utility of this data set by using machine learning to train a new algorithm that enables prediction of each kinetic parameter based on readily-modeled structural features. The generated dataset and analyses carried out in this study not only provide insight into how this enzyme functions, they also provide a clear path forward for the improvement of computational enzyme redesign algorithms.