小地老虎雄蛾中胚层生殖腺缢缩瓣膜结构和功能

该文通过光镜、电镜和生化分析等方法,详细观察了小地老虎雄蛾中胚层生殖腺缢缩的形态、数目、位置和细胞特化的瓣膜结构,并研究了缢缩的瓣膜结构和隔离中胚层生殖腺分泌物的功能。结果表明：缢缩是雄蛾中胚层生殖腺上显著收缩段,有7个,分别在雄性附腺—贮精囊、贮精囊—精包腺1段、精包腺1～5各段之间,精包腺5段—C形管;缢缩自内向外为4层,即瓣膜细胞、底膜、肌肉和围膜,肌肉层发达;缢缩瓣膜结构是细胞极度伸长特化形成的,其特点是：多数细胞伸长超过原长度的一倍以上,顶区膨大呈蘑菇突,纵横交错堵塞管腔,其顶段的微绒毛致密而细长,稠密的粗面内质网和稀疏的高尔基体环绕在核的四周,细胞间隙发达;缢缩瓣膜结构具有隔离相邻区段中胚层生殖腺分泌物的功能,致使各区段分泌物在蛋白质电泳谱带数和迁移率,以及经PAS染色后在腺腔横切面上的构象存在显著差异。     

Ecological and phylogenetic variability in the spinalis muscle of snakes

Understanding the origin and maintenance of functionally important subordinate traits is a major goal of evolutionary physiologists and ecomorphologists. Within the confines of a limbless body plan, snakes are diverse in terms of body size and ecology, but we know little about the functional traits that underlie this diversity. We used a phylogenetically diverse group of 131 snake species to examine associations between habitat use, sidewinding locomotion and constriction behaviour with the number of body vertebrae spanned by a single segment of the spinalis muscle, with total numbers of body vertebrae used as a covariate in statistical analyses. We compared models with combinations of these predictors to determine which best fit the data among all species and for the advanced snakes only (N = 114). We used both ordinary least‐squares models and phylogenetic models in which the residuals were modelled as evolving by the Ornstein–Uhlenbeck process. Snakes with greater numbers of vertebrae tended to have spinalis muscles that spanned more vertebrae. Habitat effects dominated models for analyses of all species and advanced snakes only, with the spinalis length spanning more vertebrae in arboreal species and fewer vertebrae in aquatic and burrowing species. Sidewinding specialists had shorter muscle lengths than nonspecialists. The relationship between prey constriction and spinalis length was less clear. Differences among clades were also strong when considering all species, but not for advanced snakes alone. Overall, these results suggest that muscle morphology may have played a key role in the adaptive radiation of snakes.     

Monoamine oxidases (MAO) in the pathogenesis of heart failure and ischemia/reperfusion injury

Recent evidence highlights monoamine oxidases (MAO) as another prominent source of oxidative stress. MAO are a class of enzymes located in the outer mitochondrial membrane, deputed to the oxidative breakdown of key neurotransmitters such as norepinephrine, epinephrine and dopamine, and in the process generate H₂O₂. All these monoamines are endowed with potent modulatory effects on myocardial function. Thus, when the heart is subjected to chronic neuro-hormonal and/or peripheral hemodynamic stress, the abundance of circulating/tissue monoamines can make MAO-derived H₂O₂ production particularly prominent. This is the case of acute cardiac damage due to ischemia/reperfusion injury or, on a more chronic stand, of the transition from compensated hypertrophy to overt ventricular dilation/pump failure. Here, we will first briefly discuss mitochondrial status and contribution to acute and chronic cardiac disorders. We will illustrate possible mechanisms by which MAO activity affects cardiac biology and function, along with a discussion as to their role as a prominent source of reactive oxygen species. Finally, we will speculate on why MAO inhibition might have a therapeutic value for treating cardiac affections of ischemic and non-ischemic origin. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.     

Crucial points within the pore as determinants of K⁺ channel conductance and gating

While selective for K⁺, K⁺ channels vary significantly among their rate of ion permeation. Here, we probe the effect of steric hindrance and electrostatics within the ion conduction pathway on K⁺ permeation in the MthK K⁺ channel using structure-based mutagenesis combined with single-channel electrophysiology and X-ray crystallography. We demonstrate that changes in side-chain size and polarity at Ala88, which forms the constriction point of the open MthK pore, have profound effects on single-channel conductance as well as open probability. We also reveal that the negatively charged Glu92s at the intracellular entrance of the open pore form an electrostatic trap, which stabilizes a hydrated K⁺ and facilitates ion permeation. This electrostatic attraction is also responsible for intracellular divalent blockage, which renders the channel inward rectified in the presence of Ca²⁺. In light of the high structural conservation of the selectivity filter, the size and chemical environment differences within the portion of the ion conduction pathway other than the filter are likely the determinants for the conductance variations among K⁺ channels.     

Vanilloid Receptor-1 (TRPV1) Expression and Function in the Vasculature of the Rat

Transient receptor potential (TRP) cation channels are emerging in vascular biology. In particular, the expression of the capsaicin receptor (TRPV1) was reported in vascular smooth muscle cells. This study characterized the arteriolar TRPV1 function and expression in the rat. TRPV1 mRNA was expressed in various vascular beds. Six commercially available antibodies were tested for TRPV1 specificity. Two of them were specific (immunostaining was abolished by blocking peptides) for neuronal TRPV1 and one recognized vascular TRPV1. TRPV1 was expressed in blood vessels in the skeletal muscle, mesenteric and skin tissues, as well as in the aorta and carotid arteries. TRPV1 expression was found to be regulated at the level of individual blood vessels, where some vessels expressed, while others did not express TRPV1 in the same tissue sections. Capsaicin (a TRPV1 agonist) evoked constrictions in skeletal muscle arteries and in the carotid artery, but had no effect on the femoral and mesenteric arteries or the aorta. In blood vessels, TRPV1 expression was detected in most of the large arteries, but there were striking differences at level of the small arteries. TRPV1 activity was suppressed in some isolated arteries. This tightly regulated expression and function suggests a physiological role for vascular TRPV1.     

Super-resolution Imaging of the Cytokinetic Z Ring in Live Bacteria Using Fast 3D-Structured Illumination Microscopy (f3D-SIM)

Imaging of biological samples using fluorescence microscopy has advanced substantially with new technologies to overcome the resolution barrier of the diffraction of light allowing super-resolution of live samples. There are currently three main types of super-resolution techniques – stimulated emission depletion (STED), single-molecule localization microscopy (including techniques such as PALM, STORM, and GDSIM), and structured illumination microscopy (SIM). While STED and single-molecule localization techniques show the largest increases in resolution, they have been slower to offer increased speeds of image acquisition. Three-dimensional SIM (3D-SIM) is a wide-field fluorescence microscopy technique that offers a number of advantages over both single-molecule localization and STED. Resolution is improved, with typical lateral and axial resolutions of 110 and 280 nm, respectively and depth of sampling of up to 30 µm from the coverslip, allowing for imaging of whole cells. Recent advancements (fast 3D-SIM) in the technology increasing the capture rate of raw images allows for fast capture of biological processes occurring in seconds, while significantly reducing photo-toxicity and photobleaching. Here we describe the use of one such method to image bacterial cells harboring the fluorescently-labelled cytokinetic FtsZ protein to show how cells are analyzed and the type of unique information that this technique can provide.     

不同浓度沙利度胺对大鼠慢性坐骨神经缩窄模型的镇痛效果及机制

目的:比较不同剂量沙利度胺对大鼠慢性坐骨神经缩窄(chronic sciatic nerve constriction,CCI)的镇痛效果及可能机制。方法:将50只大鼠随机分为S组、C组、L组、M组及H组,S组作为假手术组,其余四组建立CCI模型,术后分别用20 mg/kg、50mg/kg、100 mg/kg沙利度胺处理L组、M组、H组。于术后第1、2、3、4周测量和比较各组大鼠机械性痛阈与热痛阈,采用蛋白质印迹法(Western blot)及实时荧光定量PCR(Q-PCR)检测各组大鼠肿瘤坏死因子受体(TNFR)的mRNA和蛋白表达,并分析沙利度胺浓度与TNFR mRNA相对表达的相关性。结果:S组术前术后的机械性痛阈与热痛阈均无明显改变(P0.05),其余四组术后痛阈均较术前明显下降(P0.05);C组术后第4周时机械性痛阈明显升高(P0.05),而术后其他时间点的机械性痛阈与热痛阈无明显差异(P0.05);L组、M组、H组术后机械性痛阈、热痛阈随时间的延长呈上升趋势,差异有统计学意义(P0.05)。术后,C组机械性痛阈与热痛阈对比S组明显降低(P=0.000),亦显著低于L组(P=0.000);而不同剂量组机械性痛阈、热痛阈相比,H组高于M组(P=0.000),M组高于L组(P=0.000)。相对于C组,L组、M组、H组术后第4周TNFR1 mRNA及蛋白相对含量显著下降(P0.05),其中H组下降最为明显,M组次之。Pearson相关性分析结果显示:沙利度胺浓度的增加与TNFR1表达水平的升高呈明显负相关关系(r=-0.497,P=0.036)。结论:沙利度胺可能通过影响TNFR表达水平对大鼠慢性坐骨神经缩窄发挥镇痛效应,其镇痛效应随剂量增加而加强,有望作为神经病理性疼痛的辅助镇痛药物之一。     

MiR‐150 alleviates neuropathic pain via inhibiting toll‐like receptor 5

MicroRNAs (miRNAs) are reported as vital participators in the pathophysiological course of neuropathic pain. However, the underlying mechanisms of the functional roles of miRNAs in neuropathic pain are largely unknown. This study was designed to explore the potential role of miR‐150 in regulating the process of neuropathic pain in a rat model established by chronic sciatic nerve injury (CCI). Overexpression of miR‐150 greatly alleviated neuropathic pain development and reduced inflammatory cytokine expression, including COX‐2, interleukin IL‐6, and tumor necrosis factor (TNF)‐α in CCI rats. By bioinformatic analysis, 3′‐untranslated region (UTR) of Toll‐like receptor (TLR5) was predicted to be a target of miR‐150. TLR5 commonly serves as an important regulator of inflammation. Overexpression of miR‐150 significantly suppressed the expression of TLR5 in vitro and in vivo. Furthermore, upregulation of TLR5 decreased the miR‐150 expression and downregulation of TLR5 increased miR‐150, respectively. Overexpression of TLR5 significantly reversed the miR‐150‐induced suppressive effects on neuropathic pain. In conclusion, our current study indicates that miR‐150 may inhibit neuropathic pain development of CCI rats through inhibiting TLR5‐mediated neuroinflammation. Our findings suggest that miR‐150 may provide a novel therapeutic target for neuropathic pain treatment.