Loss of pro-apoptotic Bim promotes accumulation of pulmonary T lymphocytes and enhances allergen-induced goblet cell metaplasia

Immunological tolerance during prolonged exposure to allergen is accompanied by a shift in the lymphocyte content and a reduction of goblet cell metaplasia (GCM). Bim initiates negative selection of autoreactive T and B cells and shut down of T cell immune responses in vivo. The present study investigated whether Bim plays a role in the resolution of GCM during prolonged exposure to allergen. Loss of Bim increased T lymphocyte numbers in the bronchoalveolar lavage at 4 and 15 days of allergen exposure. The numbers of pulmonary CD4(+)8(-), CD4(-)8(+), and gammadelta T cells were significantly higher in naive and allergen-challenged bim(-/-) mice compared with wild-type (WT) littermates. When activated, pulmonary bim(-/-) T cells produced increased levels of IFNgamma compared with bim(+/+) T cells. No differences were noted in the total numbers of epithelial cells per millimeter of basal lamina between bim(+/+) and bim(-/-) mice, and the rate of resolution over 15 days of exposure was similar in both groups of mice. However, GCM was significantly enhanced and expression of IL-13Ralpha2 was reduced in bim(-/-) mice compared with WT mice at 4 days. Furthermore, treatment of bronchiolar explant cultures with increasing IFNgamma levels reduced immunostaining for IL-13Ralpha2. Collectively, these studies suggest that, during prolonged exposure to allergen, Bim plays no role in the resolution of GCM, but increased IFNgamma levels in bim(-/-) mice may be responsible for reduced expression of IL-13Ralpha2 and enhanced GCM despite similar levels of IL-13 in bim(+/+) and bim(-/-) mice.     

酵母双杂交系统筛选与RapGAP相互作用的蛋白质

目的筛选与Rap GAP相互作用的蛋白质,为进一步研究人源Rap1GAP介导的信号转导通路、揭示其与肿瘤的关系提供实验依据。方法选用与Rap1GAP同源的来自美丽线虫的Rap GAP作为饵蛋白,以来源于美丽线虫的c DNA文库作为靶蛋白,应用p PC97、p PC86组成的酵母双杂交系统筛选c DNA文库中与Rap GAP相互作用的蛋白质。结果通过营养缺陷平板(-LTH)筛选出63个拟似阳性菌落。经过Lac Z鉴定,19个菌落为阳性,其中7个为强阳性。提取来自19个酵母菌落中的重组DNA,经PCR扩增,12个菌落出现阳性结果。将该19个重组DNA分别电转化入DH5α细菌,涂板培养后,每板挑取4~10个克隆,通过Sal I和Not I双酶切鉴定进行阳性克隆筛选。将阳性克隆的重组DNA进行序列测定。测序结果与Gen Bank比较,其中4个克隆的DNA片段为Y39b6a基因片段、2个为Rap GAP、1个为苯丙氨酸-4-羟化酶、1个为细胞色素C氧化酶,还有1个DNA片段编码美丽线虫特有的小分子蛋白的基因片段,其余11个DNA片段不编码已知蛋白质。结论初步筛选出与Rap GAP相互作用的蛋白质,特别是其中有2个克隆为Rap GAP,提示Rap GAP可能以二聚体的方式存在。     

Swine generated by somatic cell nuclear transfer have increased incidence of intrauterine growth restriction (IUGR)

While somatic cell nuclear transfer (SCNT) has been successful in several species, many pregnancies are lost and anomalies are found in fetal and perinatal stages. In this study SCNT and artificial inseminations (AI) populations were compared for litter size, average birth weight, piglets alive at birth, stillborn, mummies, dead at the first week, intrauterine growth restriction (IUGR) and large for gestational age (LGA). Twenty-three SCNT litters (143 individuals) were compared to 112 AI litters (1300 individuals). Litter size average was 11.5 for AI and 6.2 for SCNT. Litter weight and average birth weight adjusted by litter size were significantly (p < 0.05) higher in AI than in SCNT litters. The SCNT population had a significant (p < 0.01) increase in the number of IUGRs per litter with LSmeans 7.2 +/- 1.4 versus 19.4 +/- 3.5 and means 8.0 +/- 10.8 versus 15.5 +/- 24.5 for AI and SCNT, respectively. Additionally, there was a trend for higher postnatal mortality and stillbirths in the SCNT population. These findings demonstrate that there are some differences between SCNT-derived and AI litters. SCNT-derived pigs are excellent models to study epigenetic factors and genes involved in IUGRs, and to develop effective means to improve fetal growth in humans and animals.     

Do lianas shape ant communities in an early successional tropical forest?

Almost half of lowland tropical forests are at various stages of regeneration following deforestation or fragmentation. Changes in tree communities along successional gradients have predictable bottom‐up effects on consumers. Liana (woody vine) assemblages also change with succession, but their effects on animal succession remain unexplored. Here we used a large‐scale liana removal experiment across a forest successional chronosequence (7–31 years) to determine the importance of lianas to ant community structure. We conducted 1,088 surveys of ants foraging on and living in trees using tree trunk baiting and hand‐collecting techniques at 34 paired forest plots, half of which had all lianas removed. Ant species composition, β‐diversity, and species richness were not affected by liana removal; however, ant species co‐occurrence (the coexistence of two or more species in a single tree) was more frequent in control plots, where lianas were present, versus removal plots. Forest stand age had a larger effect on ant community structure than the presence of lianas. Mean ant species richness in a forest plot increased by ca. 10% with increasing forest age across the 31‐year chronosequence. Ant surveys from forest >20 years old included more canopy specialists and fewer ground‐nesting ant species versus those from forests <20 years old. Consequently, lianas had a minimal effect on arboreal ant communities in this early successional forest, where rapidly changing tree community structure was more important to ant species richness and composition.     

Virtual identification of essential proteins within the protein interaction network of yeast

Topological analysis of large scale protein-protein interaction networks (PINs) is important for understanding the organizational and functional principles of individual proteins. The number of interactions that a protein has in a PIN has been observed to be correlated with its indispensability. Essential proteins generally have more interactions than the nonessential ones. We show here that the lethality associated with removal of a protein from the yeast proteome correlates with different centrality measures of the nodes in the PIN, such as the closeness of a protein to many other proteins, or the number of pairs of proteins which need a specific protein as an intermediary in their communications, or the participation of a protein in different protein clusters in the PIN. These measures are significantly better than random selection in identifying essential proteins in a PIN. Centrality measures based on graph spectral properties of the network, in particular the subgraph centrality, show the best performance in identifying essential proteins in the yeast PIN. Subgraph centrality gives important structural information about the role of individual proteins, and permits the selection of possible targets for rational drug discovery through the identification of essential proteins in the PIN.     

Clinical Focus on Malassezia Folliculitis

Malassezia spp. folliculitis is a variant quite frequent at the tropics. The clinical aspect of perifollicular pustules on an erythematous base with a central hair is the clue for the diagnosis, especially on hairy surfaces. We describe this clinical form caused by Malassezia sp., with background, direct examination findings, and histopathology.     

In silico strategies to couple production of bioethanol with growth in cyanobacteria

Cyanobacteria have been considered as promising candidates for sustainable bioproduction from inexpensive raw materials, as they grow on light, carbon dioxide, and minimal inorganic nutrients. In this study, we present a genome-scale metabolic network model for Synechocystis sp. PCC 6803 and study the optimal design of the strain for ethanol production by using a mixed integer linear problem reformulation of a bilevel programming problem that identifies gene knockouts which lead to coupling between growth and product synthesis. Five mutants were found, where the in silico model predicts coupling between biomass growth and ethanol production in photoautotrophic conditions. The best mutant gives an in silico ethanol production of 1.054 mmol·gDW ⁻¹·h ⁻¹.