生长休止蛋白7在大鼠小脑皮质发育过程中的动态表达

目的研究生长休止蛋白7(Gas7)在大鼠小脑皮质不同发育时期的动态表达。方法采用逆转录聚合酶链反应(RT-PCR)方法检测Gas7mRNA在大鼠小脑皮质不同发育时期的表达;免疫组织化学方法观察Gas7蛋白在大鼠小脑皮质不同发育时期的表达和分布。结果 RT-PCR结果:Gas7mRNA在大鼠小脑皮质发育时期的表达呈现先增强后减弱的趋势,高峰出现在生后第21d(P21)。免疫组化实验结果:在胚胎第18.5d(E18.5)和E20.5仅Purkinje细胞层有Gas7免疫阳性产物分布;出生当天(P0)外颗粒层出现Gas7阳性神经纤维,Purkinje细胞层出现形态不规则的Gas7免疫阳性细胞;P7外颗粒层和Purkinje细胞层免疫反应增强,内颗粒层出现一些散在的Gas7强阳性细胞,胞体较小,突起清晰可见;P14小脑皮质4层均有Gas7阳性表达;P21小脑皮质3层Gas7免疫阳性反应较P14增强(P0.01);Adult(2月龄)较P21免疫反应减弱(P0.01)。结论 Gas7在大鼠小脑皮质发育过程中的动态表达呈现出时空特异性,提示Gas7基因在大鼠小脑皮质发育过程中可能起着重要的调控作用。     

Identification of proteins that form specific complexes with the highly conserved protein Translin in Schizosaccharomyces pombe

Translin is a single-stranded DNA and RNA binding protein that has a high affinity for G-rich sequences. TRAX is a Translin paralog that associates with Translin. Both Translin and TRAX were highly conserved in eukaryotes. The nucleic acid binding form of Translin is a barrel-shaped homo-octamer. A Translin–TRAX hetero-octamer having a similar structure also binds nucleic acids. Previous reports suggested that Translin may be involved in chromosomal translocations, telomere metabolism and the control of mRNA transport and translation. More recent studies have indicated that Translin–TRAX hetero-octamers are involved in RNA silencing. To gain a further insight into the functions of Translin, we have undertaken to systematically search for proteins with which it forms specific complexes in living cells. Here we report the results of such a search conducted in the fission yeast Schizosaccharomyces pombe, a suitable model system. This search was carried out by affinity purification and immuno-precipitation techniques, combined with differential labeling of the intracellular proteins with the stable isotopes ¹⁵N and ¹⁴N. We identified for the first time two proteins containing an RNA Recognition Motif (RRM), which are specifically associated with the yeast Translin: (1) the pre-mRNA-splicing factor srp1 that belongs to the highly conserved SR family of proteins and (2) vip1, a protein conserved in fungi. Our data also support the presence of RNA in these intracellular complexes. Our experimental approach should be generally applicable to studies of weak intracellular protein–protein interactions and provides a clear distinction between false positive vs. truly interacting proteins.     

Deletion in the EVC2 Gene Causes Chondrodysplastic Dwarfism in Tyrolean Grey Cattle

During the summer of 2013 seven Italian Tyrolean Grey calves were born with abnormally short limbs. Detailed clinical and pathological examination revealed similarities to chondrodysplastic dwarfism. Pedigree analysis showed a common founder, assuming autosomal monogenic recessive transmission of the defective allele. A positional cloning approach combining genome wide association and homozygosity mapping identified a single 1.6 Mb genomic region on BTA 6 that was associated with the disease. Whole genome re-sequencing of an affected calf revealed a single candidate causal mutation in the Ellis van Creveld syndrome 2 (EVC2) gene. This gene is known to be associated with chondrodysplastic dwarfism in Japanese Brown cattle, and dwarfism, abnormal nails and teeth, and dysostosis in humans with Ellis-van Creveld syndrome. Sanger sequencing confirmed the presence of a 2 bp deletion in exon 19 (c.2993_2994ACdel) that led to a premature stop codon in the coding sequence of bovine EVC2, and was concordant with the recessive pattern of inheritance in affected and carrier animals. This loss of function mutation confirms the important role of EVC2 in bone development. Genetic testing can now be used to eliminate this form of chondrodysplastic dwarfism from Tyrolean Grey cattle.     

Fixated on fixation: using ChIP to interrogate the dynamics of chromatin interactions

A new study exploits the time-dependence of formaldehyde cross-linking in the commonly used chromatin immunoprecipitation (ChIP) assay to infer the on and off rates for site-specific chromatin interactions.     

Long-Term Evaluation of Cougar Density and Application of Risk Analysis for Harvest Management

Estimates of cougar (Puma concolor) density are among the least available of any big game species in North America because of monetary and logistical challenges. Thus, wildlife managers identify cougar density estimates as a high priority need for population estimation, developing harvest guidelines, and evaluating management objectives. Cougar densities range from <1 to almost 7 cougars/100 km²; however, the magnitude of spatial and temporal variation associated with these estimates is difficult to assess because this range of densities could potentially be reported for any given population using different demographic, temporal, durational, and analytical approaches. We used long-term global positioning system (GPS) data from collared cougars across 5 diverse study areas in Washington, USA, as the basis for calculating multiple annual independent-aged (≥18 months) cougar densities, using consistent methods, and conducted a meta-analysis to assist with statewide harvest guidelines. To generate specific harvest guidelines for unobserved populations at the management unit scale, we employed a Bayesian decision-theoretic approach that minimizes statistical risk of failing to achieve a defined harvest rate. For the 16-year field effort, we calculated 24 annual densities for independent-aged cougars. Average annual densities ranged from 1.55 ± 0.44 (SD) cougars/100 km² (n = 5 years) to 2.79 ± 0.35 cougars/100 km² (n = 5 years) among the 5 study areas. Explicit delineation of the cougar population demonstrated that contribution to density can vary considerably by sex and age class. Application of a 12–16% harvest rate within the risk analysis framework yielded a potential annual harvest of 249 cougars over 91,000 km² of cougar habitat in Washington. Given the importance of density for establishing harvest guidelines, and the degree of uncertainty in projecting derived densities to future years and unstudied management units, our approach may lessen the ambiguity of extrapolations and increase the longevity of research results. Our risk analysis can be used for a diverse array of species and management objectives and be incorporated into an adaptive management framework for minimizing management risk. Our recommendations can improve standardization in reporting and interpretation of cougar density comparisons and bring clarity to the sources of variability observed in cougar populations. © 2021 The Wildlife Society.     

生长在超干旱环境下的3种相思树种表现出异常低的叶片、树枝、树干、根中δ13C含量

生长在超干旱环境下的3种相思树种表现出异常低的叶片、树枝、树干、根中δ¹³C含量 在植物生理生态学中,叶片中碳13(¹³C)含量负值较少(富集),表明叶片处于通过气孔的气体交换减少,比如在干旱胁迫下。此外,与叶片相比,13C在非光合组织中的负值也较少。然而,对从叶片(光合器官)到树枝、树干和根(非光合器官)中的δ ¹³C数值的关系知之甚少,特别是缺少在关联密切的多个树种间或者不同器官间,以及对生长在极端高温和干旱胁迫下的树木中进行测定。本研究测定了3种近缘沙漠相思树种(Acacia tortilis、A. raddiana和A. pachyceras)从叶片到根的¹³C含量。我们在以色列南部成树的叶片组织中测定了δ ¹³C含量。与此同时,在试验果园进行了为期7年的3个水平的灌溉试验。在试验结束时,测定了叶片、树枝、树干和根的生长参数和δ ¹³C含量。研究结果表明,叶片组织中δ ¹³C含量约为−27‰,其同位素贫化程度远超过生长在地球上最干燥和最热环境中的沙漠树种的预期值。在不同的相思树种和不同器官中,所有灌溉水平处理中的δ ¹³C含量并没有富集(−28‰到ca. −27‰),证实了在成熟相思树中的测定结果。在不同器官中,叶片δ ¹³C含量与树枝和根的δ ¹³C含量异常相似,甚至比树干的δ ¹³C含量负值更少。高度贫化的叶片δ ¹³C表明,尽管这些树木生长在极端干燥的生境中,但其气孔气体交换较高。非光合组织中缺乏δ ¹³C富集可能与叶片和异养组织生长的季节耦合有关。     

Ccr5 deficiency regulates the proliferation and trafficking of natural killer cells under physiological conditions

Chemokines were shown to govern the trafficking of immune cells and may also play important roles in the survival and activation of these cells. We report here that under physiological conditions, the bone marrow (BM), spleen, blood and liver of Ccr5, but not of Ccr1-deficient mice, contain reduced numbers of NK cells. NK cells in the BM of Ccr5-deficient mice proliferate to a lesser extent compared to WT mice. Furthermore, spleen NK cells derived from Ccr5-deficient mice that were transplanted into irradiated recipients failed to proliferate in the host. Ccr5, but not Ccr1-deficient NK cells, failed to migrate in vitro in response to RANTES and MIP-1β but not MIP-1β or SDF-1 and had reduced activation, lower expression levels of NK cell markers and a slightly reduced capacity to adhere to target cells and stimulate their killing. Using the polyI:C mouse model for NK trafficking, we found that in the absence of Ccr5, but not Ccr1, NK cells failed to accumulate in the liver. In contrast, using the influenza viral infection as a model to evaluate NK cell proliferation, we found that Ccr5-deficient NK cells in the BM had a higher proliferation rate than WT NK cells. These results suggest a role for Ccr5 in NK cell proliferation and circulation under physiological conditions and a complex role for Ccr5 in determining the fate of NK cells under pathological conditions.