Increased dosage of Dyrk1A alters alternative splicing factor (ASF)-regulated alternative splicing of tau in Down syndrome

Two groups of tau, 3R- and 4R-tau, are generated by alternative splicing of tau exon 10. Normal adult human brain expresses equal levels of them. Disruption of the physiological balance is a common feature of several tauopathies. Very early in their life, individuals with Down syndrome (DS) develop Alzheimer-type tau pathology, the molecular basis for which is not fully understood. Here, we demonstrate that Dyrk1A, a kinase encoded by a gene in the DS critical region, phosphorylates alternative splicing factor (ASF) at Ser-227, Ser-234, and Ser-238, driving it into nuclear speckles and preventing it from facilitating tau exon 10 inclusion. The increased dosage of Dyrk1A in DS brain due to trisomy of chromosome 21 correlates to an increase in 3R-tau level, which on abnormal hyperphosphorylation and aggregation of tau results in neurofibrillary degeneration. Imbalance of 3R- and 4R-tau in DS brain by Dyrk1A-induced dysregulation of alternative splicing factor-mediated alternative splicing of tau exon 10 represents a novel mechanism of neurofibrillary degeneration and may help explain early onset tauopathy in individuals with DS.     

Isolation and Genetic Characterization of Toxoplasma gondii from Black Bears (Ursus americanus), Bobcats (Lynx rufus), and Feral Cats (Felis catus) from Pennsylvania

Toxoplasma gondii infects virtually all warm‐blooded hosts worldwide. Recently, attention has been focused on the genetic diversity of the parasite to explain its pathogenicity in different hosts. It has been hypothesized that interaction between feral and domestic cycles of T. gondii may increase unusual genotypes in domestic cats and facilitate transmission of potentially more pathogenic genotypes to humans, domestic animals, and wildlife. In the present study, we tested black bear (Ursus americanus), bobcat (Lynx rufus), and feral cat (Felis catus) from the state of Pennsylvania for T. gondii infection. Antibodies to T. gondii were found in 32 (84.2%) of 38 bears, both bobcats, and 2 of 3 feral cats tested by the modified agglutination test (cut off titer 1:25). Hearts from seropositive animals were bioassayed in mice, and viable T. gondii was isolated from 3 of 32 bears, 2 of 2 bobcats, and 2 of 3 feral cats. DNA isolated from culture‐derived tachyzoites of these isolates was characterized using multilocus PCR‐RFLP markers. Three genotypes were revealed, including ToxoDB PCR‐RFLP genotype #1 or #3 (Type II, 1 isolate), #5 (Type 12, 3 isolates), and #216 (3 isolates), adding to the evidence of genetic diversity of T. gondii in wildlife in Pennsylvania. Pathogenicity of 3 T. gondii isolates (all #216, 1 from bear, and 2 from feral cat) was determined in outbred Swiss Webster mice; all three were virulent causing 100% mortality. Results indicated that highly mouse pathogenic strains of T. gondii are circulating in wildlife, and these strains may pose risk to infect human through consuming of game meat.     

基于单碱基延伸标签反应的常见食源性致病菌基因芯片检测方法的建立

针对8种常见的食源性致病菌(金黄色葡萄球菌、副溶血弧菌、单核细胞增生李斯特菌、沙门氏菌、阪崎肠杆菌、志贺氏菌、肠出血性大肠杆菌O157:H7和空肠弯曲杆菌),建立了基于单碱基延伸标签反应原理的基因芯片检测方法。筛选和整合8种食源性致病菌基因组中的特异性序列和相应PCR引物,致病菌靶DNA片段被扩增和纯化作为单碱基延伸标签反应的模板,反应产物在DNA芯片上与探针进行杂交反应,然后通过扫描基片的荧光强度进行判断。实验结果表明,可采用基于单碱基延伸标签反应的基因芯片方法同时特异性检测8种食源性致病菌,基因组DNA多重检测灵敏度可达到0.1pg,以鼠伤寒沙门氏菌为单一检测对象的细菌纯培养物灵敏度可达到5×102CFU/mL。本方法可以快速灵敏地检测食源性致病菌,为食源性疾病的诊断和防治提供了一个有效的方法。     

Activation of protease-activated receptor 2 reduces glioblastoma cell apoptosis

Background

The pathogenesis of glioma is unclear. The disturbance of the apoptosis process plays a critical role in glioma growth. Factors regulating the apoptosis process are to be further understood. This study aims to investigate the role of protease activated receptor-2 (PAR2) in regulation the apoptosis process in glioma cells.

Results

The results showed that U87 cells and human glioma tissue expressed PAR2. Exposure to tryptase, or the PAR2 active peptide, increased STAT3 phosphorylation in the radiated U87 cells, reduced U87 cell apoptosis, suppressed the expression of p53 in U87 cells.

Conclusions

Activation of PAR2 can reduce the radiated U87 cell apoptosis via modulating the expression of p53. The results implicate that PAR2 may be a novel therapeutic target in the treatment of glioma.     

Exploring polymorphisms and associations of the bovine MOGAT3 gene with growth traits

Monoacylglycerol acyltransferase (MGAT3, also known as MOGAT3) catalyzes the synthesis of diacylglycerol (DAG) using 2-monoacylglycerol and fatty acyl coenzyme A. This enzymatic reaction is believed to be an essential and rate-limiting step for the absorption of dietary fat in the small intestine. However, similar research for the bovine MOGAT3 gene is lacking. Therefore, in this paper, polymorphisms of the bovine MOGAT3 gene were detected in 1145 individuals from five cattle breeds by DNA pooling, PCR-RFLP, and DNA sequencing methods. The results showed that 26 novel SNPs were identified, which included 16 mutations in the coding region and the others in the introns. Additionally, association analysis between two missense mutations, g.A229G and g.G1627A, and growth traits in Nanyang cattle up to 2 years of age and adult Qinchuan cattle was performed. The results indicated that polymorphisms were significantly associated with Nanyang cattle, but no convincing associations were observed for Qinchuan cattle for the studied traits.     

质粒pcDNA3—HGF的大规模纯经制备研究

质粒ｐｃＤＮＡ３－ＨＧＦ具有潜在的临床治疗缺血性疾病的应用前景。大规模纯化制备是质粒ＤＮＡ应用于基因治疗的关键步骤。质粒大规模纯化制备流程包括：发酵、离心收集细胞、碱性裂解、Ｑ－Ｓｅｐｈａｒｏｓｅ ＸＬ捕获质粒ＤＮＡ、Ｓｏｕｒｃｅ １５Ｑ精制质粒ＤＮＡ,所得纯超螺旋质粒ｐｃＤＮＡ３－ＨＧＦ符合质量标准。该纯化制备方法避免使用动物源性的酶及有毒试剂。     

Limitations of using extracellular alkaline phosphatase activities as a general indicator for describing P deficiency of phytoplankton in Chinese shallow lakes

Extracellular phosphatase can be produced by phytoplankton to utilize organic phosphorus under phosphorus (P) deficiency. However, there is a controversy about its use as an indicator of P deficiency in natural phytoplankton community inferred by such an “induction–repression” mechanism. Size-fractionation of alkaline phosphatase activity (APA), soluble reactive phosphorus (SRP) concentration, algal density, and composition were determined in six Chinese shallow lakes ranking in gradient of trophic status, where a positive relationship between SRP concentration and algal density was observed. Enzyme-labeled fluorescence (ELF) method was used to localize phosphatase on cell membrane of algae. The so-called algal APA that associated with coarser particle (>3.0 μm) accounted for the largest part of total APA. Within a lake with lower SRP concentration, the “induction–repression” mechanism held true. Contrastingly, both algal and total APA were positively related to SRP concentration based on the data across all study lakes with statistical significance, which may be explained firstly by algal composition. The lakes with higher SRP concentration were dominated by diatoms and green algae, while they easily produced extracellular phosphatases as evidenced by ELFA labeling. In parallel, the lakes with lower SRP concentration were dominated by cyanobacteria, while it was never ELFA-positive; secondly, ELFA-positive dots or structures suggested that, in lakes with higher trophic status, attached bacteria or heterotrophic microorganisms could substantially contribute to extracellular phosphatases for hydrolyzing organophosphoric compounds but probably utilizing the organic moiety as an organic carbon source. This process simultaneously produces inorganic P, leading to the co-occurrence of high phosphate concentration and APA. So, the contributor of APA are complex, which may produce extracellular phosphatase species-specific or not exclusively for P nutrient and consequently make it difficult to normalize APA with the exact biomass estimators. Therefore, it is not reasonable to use APA, normalized or not, as a general indicator for describing P deficiency of phytoplankton in shallow lakes especially eutrophic ones.