Function and Regulation of the Na+-Ca2+ Exchanger NCX3 Splice Variants in Brain and Skeletal Muscle

Isoform 3 of the Na⁺-Ca²⁺ exchanger (NCX3) is crucial for maintaining intracellular calcium ([Ca²⁺]_i) homeostasis in excitable tissues. In this sense NCX3 plays a key role in neuronal excitotoxicity and Ca²⁺ extrusion during skeletal muscle relaxation. Alternative splicing generates two variants (NCX3-AC and NCX3-B). Here, we demonstrated that NCX3 variants display a tissue-specific distribution in mice, with NCX3-B as mostly expressed in brain and NCX-AC as predominant in skeletal muscle. Using Fura-2-based Ca²⁺ imaging, we measured the capacity and regulation of the two variants during Ca²⁺ extrusion and uptake in different conditions. Functional studies revealed that, although both variants are activated by intracellular sodium ([Na⁺]_i), NCX3-AC has a higher [Na⁺]_i sensitivity, as Ca²⁺ influx is observed in the presence of extracellular Na⁺. This effect could be partially mimicked for NCX3-B by mutating several glutamate residues in its cytoplasmic loop. In addition, NCX3-AC displayed a higher capacity of both Ca²⁺ extrusion and uptake compared with NCX3-B, together with an increased sensitivity to intracellular Ca²⁺. Strikingly, substitution of Glu⁵⁸⁰ in NCX3-B with its NCX3-AC equivalent Lys⁵⁸⁰ recapitulated the functional properties of NCX3-AC regarding Ca²⁺ sensitivity, Lys⁵⁸⁰ presumably acting through a structure stabilization of the Ca²⁺ binding site. The higher Ca²⁺ uptake capacity of NCX3-AC compared with NCX3-B is in line with the necessity to restore Ca²⁺ levels in the sarcoplasmic reticulum during prolonged exercise. The latter result, consistent with the high expression in the slow-twitch muscle, suggests that this variant may contribute to the Ca²⁺ handling beyond that of extruding Ca²⁺.     

C-terminal binding: an expanded repertoire and function of 14-3-3 proteins

Amino and carboxyl termini are unique positions in a polypeptide. They tend to be exposed in folded three dimensional structures. Diversity and functional significance of C-terminal sequences have been appreciated from studies of PDZ and PEX domains. Signaling 14-3-3 protein signaling by recognizing phosphorylated peptides plays a critical role in a variety of biological processes, including oncogenesis. The preferential binding of 14-3-3 to phosphorylated C-terminal sequences, mode III, provides a means of regulated binding and considerably expands the substrate repertoire of 14-3-3 interaction partners.     

Characterization of protein matrix motions in the Rb. sphaeroides photosynthetic reaction center

We use Normal Mode Analysis to investigate motions in the photosynthetic reaction center (RC) protein. We identify the regions involved in concerted fluctuations of the protein matrix and analyze the normalized amplitudes and the directionality of the first few dominant modes. We also seek to quantify the coupling of normal modes to long-range electron transfer (ET). We find that a quasi-continuous spectrum of protein motions rather than one individual mode contributes to light-driven electron transfer. This is consistent with existing theoretical models (e.g. the spin-boson/dispersed polaron model) for the coupling of the protein and solvent "bath" to charge separation events. [Figure: see text].     

在转基因植物中利用植物凝集素防治害虫的研究

植物凝集素对包括同翅目在内的害虫具有有效抗性。本文就同翅目害虫的危害性、植物凝集素定义的不断深入认识、植物凝集素在植物体内的生理作用、对害虫的作用机理、并对人工饲喂害虫实验及转凝集素的抗虫基因工程研究进展、存在总是等方面作一阐述。     

不同分娩方式对晚期早产儿肠道菌群的影响

目的 探讨不同分娩方式对晚期早产儿肠道菌群定植的影响。方法 以胎龄（周）为340/7～366/7的15例晚期早产儿为研究对象,根据分娩方式分为自然分娩组（n=8）和剖宫产组（n=7）。收集早产儿出生后3 d、7 d、14 d的粪便标本,应用高通量测序技术对细菌16S rRNA可变区中的V4区进行测序,分析肠道菌群多样性及组成结构。结果 （1）自然分娩组晚期早产儿粪便标本菌群多样性指数逐渐上升,剖宫产组的多样性指数较平稳,两组相比差异无统计学意义;（2）45份粪便标本中共检测出10个菌门,均以变形菌门、厚壁菌门、放线菌门和拟杆菌门为优势菌门,两组晚期早产儿生后变形菌门、拟杆菌门所占比例逐渐降低,厚壁菌门、放线菌门呈增多趋势。两组相比,剖宫产组7 d、14 d时拟杆菌门的相对丰度显著低于自然分娩组（Z=‒2.896,P=0.004;Z=‒2.120,P=0.040）,变形菌门相对丰度仅在7 d时显著高于自然分娩组（Z=‒2.190,P=0.030）;（3）两组研究对象中,除自然分娩组14 d时以双歧杆菌属为优势菌属外,余下均以肠杆菌属为优势菌属。相比于自然分娩组,在7 d时剖宫产组拟杆菌属所占比例显著降低（Z=‒2.806,P=0.005）,肠杆菌属所占比例显著升高（Z=‒2.199,P=0.030）。结论 剖宫产能显著影响婴儿早期肠道菌群的定植,降低肠道中早期拟杆菌的水平。     

Kinetics of 8-2 fluorotelomer alcohol and its metabolites, and liver glutathione status following daily oral dosing for 45 days in male and female rats

Fluorotelomer alcohols (FTOHs) are raw materials used in the manufacture of polymeric and surfactant products. Based on previous findings from single oral dosing in rats with radiolabeled 8-2 FTOH, glutathione (GSH) depletion and/or the presence of perfluorinated/polyfluorinated acids and aldehyde metabolites was hypothesized to account for the hepatocellular lesions observed in male rats from a 90-day subchronic oral dosing study. Further, the reported nephropathy in female rats from the subchronic experiment was hypothesized to have been initiated by a thiol metabolite produced by degradation of GSH conjugates. In the current investigation, the kinetics of 8-2 FTOH and its metabolites along with liver GSH status were evaluated in the rat following daily oral dosing with 8-2 FTOH for 45 days at 5 and 125 mg/kg/day. Liver GSH stores 1-2 h after dosing were unaffected, suggesting that GSH depletion is not likely a relevant mode of action in the liver. The tissue metabolite data indicate that the liver toxicity mode of action is likely associated with elevated levels of perfluoroalkyl acids found in males, since other polyfluorinated metabolites and 8-2 FTOH were present in livers from female rats at comparable or higher levels. Detection of the N-acetyl cysteine conjugate of the unsaturated parent telomer alcohol in urine from female rats and not male rats provides some evidence to support the mechanistic basis for the observed kidney effects. Further, the increasing levels of perfluorooctanoic acid (PFOA) in plasma from female rats over the 45-day dosing phase, while unexpected, may reflect an increased net absorption of 8-2 FTOH, slow elimination of intermediates in the metabolic pathway between 8-2 FTOH and PFOA, or altered kidney clearance. The results of this study have enhanced our understanding of 8-2 FTOH kinetics and metabolism and potential modes of action in the rat, which will guide the design of future studies for FTOHs and our need to define the mechanistic basis for the observed effects.     

The Lower Paleolithic of the Indian subcontinent

This broad overview highlights the Indian subcontinent as an important and exciting source of new discoveries regarding Lower Paleolithic hominins and their biological and behavioral evolution. Broadly situated in the center of the Old World, the region arbitrarily encompasses Pakistan, India, Nepal, Sri Lanka, Bangladesh, and Bhutan; it represents the richest easternmost domain of classic Acheulean bifaces in the Old World. 1 The region comprises diverse ecological zones with complex geological and climatic histories, including a bi‐annual monsoon prevalent since the Miocene, all of which had major impacts on faunal and floral distributions and associated hominin adaptations.     

Vanucizumab mode of action: Serial biomarkers in plasma,tumor, and skin-wound-healing biopsies

Vanucizumab is a novel bispecific antibody inhibiting vascular endothelial growth factor (VEGF-A) and angiopoietin-2 (Ang-2) that demonstrated safety and anti-tumor activity in part I of a phase I study of 42 patients with advanced solid tumors. Part II evaluated the pharmacodynamic effects of vanucizumab 30 or 15 mg/kg every 2 weeks in 32 patients. Serial plasma samples, paired tumor, and skin-wound-healing biopsies were taken over 29 days to evaluate angiogenic markers. Vanucizumab was associated with marked post-infusion reductions in circulating unbound VEGF-A and Ang-2. By day 29, tumor samples revealed mean reductions in density of microvessels (−32.2%), proliferating vessels (−47.9%) and Ang-2 positive vessels (−62.5%). Skin biopsies showed a mean reduction in density of microvessels (−49.0%) and proliferating vessels (−25.7%). Gene expression profiling of tumor samples implied recruitment and potential activation of lymphocytes. Biopsies were safely conducted. Vanucizumab demonstrated a consistent biological effect on vascular-related biomarkers, confirming proof of concept. Skin-wound-healing biopsies were a valuable surrogate for studying angiogenesis-related mechanisms.     

Potential of using mineral oils for the control of the mosquito bugs Helopeltis theivora (Hemiptera: Miridae) in cashew plantations

This study investigated the influence of an nC24 mineral oil (MO) on some biological characteristics of a mosquito bug, Helopeltis theivora, reared on cashew under laboratory and greenhouse conditions. Aqueous emulsions of the oil were applied as sprays to eggs at four daily intervals after oviposition to assess impacts on egg hatch, and to cashew seedlings to assess adult longevity and female fecundity reared on the plants. Field applications were also carried out to assess the impacts of sprays on populations of the bug in a cashew orchard. The results of the laboratory study indicated that 1% (v/v) of the MO application reduced egg hatch when applied to eggs on cashew seedlings, in separate treatments, 1, 2, 3, and 4 days after oviposition (DAO). Egg mortality showed a negative linear correlation with egg maturity (DAO). The pre-oviposition period of adult females placed on sprayed cashew seedling, after deposits of 1% (v/v) sprays dried, was significantly prolonged. The longevity of males and females on dry oil-spray deposits was lower than on seedlings sprayed with water. The fecundity of females was also lower. Field sprays significantly reduced populations of the bug on mature cashew trees. Mixtures of MO and abamectin were more effective than oil alone. The results of the study indicate that mineral oils can be used to suppress populations of H. theivora in cashew plantations.