Synthetic muO-conotoxin MrVIB blocks TTX-resistant sodium channel NaV1.8 and has a long-lasting analgesic activity

MuO-conotoxin MrVIB is a blocker of voltage-gated sodium channels, including TTX-sensitive and -resistant subtypes. A comprehensive characterization of this peptide has been hampered by the lack of sufficient synthetic material. Here, we describe the successful chemical synthesis and oxidative folding of MrVIB that has made an investigation of the pharmacological properties and therapeutic potential of the peptide feasible. We show for the first time that synthetic MrVIB blocks rat NaV1.8 sodium channels and has potent and long-lasting local anesthetic effects when tested in two pain assays in rats. Furthermore, MrVIB can block propagation of action potentials in A- and C-fibers in sciatic nerve as well as skeletal muscle in isolated preparations from rat. Our work provides the first example of analgesia produced by a conotoxin that blocks sodium channels. The emerging diversity of antinociceptive mechanisms targeted by different classes of conotoxins is discussed.     

大别山区黑沟绿太阳鱼种群的形态特征研究

绿太阳鱼是2015年4月在大别山区淠河流域支流中新发现的入侵鱼类。利用2015年7月从黑沟中采集的78尾绿太阳鱼标本,对该物种的形态特征进行了详细测量和分析。结果发现绿太阳鱼种群内的形态相似性较高,但还存在一定的形态差异。相比性别,年龄是造成这种形态差异的主要原因。雄性从Ⅰ龄开始出现显著的形态分化,而雌性差异并不显著。这种形态学的差异完全符合雄鱼筑巢护卵的习性,具体表现在雄鱼头部指标（D1-2、D2-3、眼间距、眼后头长、头长）、臀鳍附近指标（D5-7、D5-8）、背鳍基部指标（D6-8）和尾柄处指标（D9-10）增大。同时相比Ⅰ龄以上的雄鱼,雌鱼和0龄雄鱼的尾柄指标（D8-10、D8-9）较长,身体更适于流水环境。这种雌雄体型上的变化,将有助于雄鱼占领溪流环境中的静水区（深潭）,而雌鱼和0龄鱼占领流水区（急滩、湍流）,这为该种群适应山区溪流的水文环境,合理分配生态位提供了便利条件,同时也使其对大别山区其他鱼类具有较大的生态危害潜力。     

假单胞菌YL11对扩展青霉的抑制作用及其机理初探

【背景】苹果青霉病是由扩展青霉引起的一种重要的果实采后病害,影响果实品质导致苹果腐烂从而造成经济损失。【目的】研究假单胞菌YL11对扩展青霉的抑制作用和苹果采后青霉病的防治效果,并对抑菌机理进行初步探讨。【方法】以扩展青霉为供试菌株,研究不同浓度的假单胞菌YL11无菌发酵液对扩展青霉菌落直径、孢子萌发率、菌丝体干重、苹果损伤接种病斑直径扩展的影响,利用对电导率、核酸及蛋白释放量、AKP含量、SDH活性、ATP酶活性和ATP含量的影响对抑菌机理进行探究。【结果】假单胞菌YL11无菌发酵液能有效抑制扩展青霉生长,抑菌圈直径为22.33±0.27 mm,抑菌效价为71.67 mm/mL;能有效抑制孢子萌发,100%无菌发酵液对孢子萌发抑制率达到80.2%;对扩展青霉的生物量也有一定抑制作用,体积分数为100%时,菌丝体干重为4.7mg/mL,抑制率达到39.74%;无菌发酵液处理能有效抑制苹果青霉病病斑的扩展,3d时对病斑扩展的抑制率最大,达到47.1%;无菌发酵液处理均能引起电导率升高、胞内核酸和蛋白释放量增大、胞外AKP含量升高、SDH活性降低、ATP酶活性和ATP含量均降低,且随着发酵液浓度的增加效果越明显。【结论】假单胞菌YL11能显著抑制扩展青霉的生长,破坏细胞膜结构、降低能量代谢酶活性,从而扰乱扩展青霉的正常生长,对苹果青霉病有较好的生防效果,具有潜在的开发价值。     

利用高效液相色谱法分离和测定棉花组织培养过程中4种内源激素

目的：优化利用高效液相色谱法测定棉花组织培养过程中吲哚-3-乙酸（IAA）、玉米素（ZT）、赤霉素（GA3）和脱落酸（ABA）等4种植物内源激素的条件,了解棉花胚性愈伤组织发生过程中4种内源激素及激素含量比例的规律性变化,以及添加不同外源激素对内源激素和愈伤组织的影响,为棉花组织培养由经验型变为理论型提供基础。方法：采用高效液相色谱法。结果：棉花胚性愈伤组织发生过程中4种内源激素及激素含量比例呈规律性变化：ZT、ABA、ABA/GA3、ABA/IAA呈现先上升后下降的趋势,GA3呈现先上升后下降再上升的趋势,ZT/IAA呈现明显的上升-下降-上升-下降的趋势;不同激素组合诱导下愈伤组织中内源激素含量及愈伤组织状态也有较大差别。结论：研究结果对指导组织培养过程中激素的调整和配比、制定适宜的培养计划有一定的指导意义;4种不同的内源激素都是愈伤组织生长的重要因子,各自适宜的浓度和恰当的比例调节着外植体的脱分化和再分化,各种激素协同作用促进细胞的生长和分化。     

Interactions of uranyl ion with cytochrome <Emphasis Type="Italic">b</Emphasis><Subscript>5</Subscript> and its His39Ser variant as revealed by molecular simulation in combination with experimental methods

The biological toxicity of uranyl ion (UO₂²⁺) lies in interacting with proteins and disrupting their native functions. The structural and functional consequences of UO₂²⁺ interacting with cytochrome b ₅ (cyt b ₅), a small membrane heme protein, and its heme axial ligand His39Ser variant, cyt b ₅ H39S, were investigated both experimentally and theoretically. In experiments, although cyt b ₅ was only slightly affected, UO₂²⁺ binding to cyt b ₅ H39S with a K _D of 2.5 μM resulted in obvious alteration of the heme active site, and led to a decrease in peroxidase activity. Theoretically, molecular simulation proposed a uranyl ion binding site for cyt b ₅ at surface residues of Glu37 and Glu43, revealing both coordination and hydrogen bonding interactions. The information gained in this study provides insights into the mechanism of uranyl toxicity toward membrane protein at an atomic level.     

天鹅洲迁地保护江豚群体的遗传评估与发展预测

文章以2008年春季遭受严重雪灾的天鹅洲白鱀豚国家级自然保护区迁地保护江豚群体为研究对象,利用物种特异性微卫星遗传标记对该群体的遗传多样性进行了评估,并通过软件对其发展趋势进行了模拟和预测。研究结果表明,虽然2008年春季雪灾并未导致该群体遗传多样性的严重损失,灾后群体依然表现出中等水平的微卫星遗传多样性(18个座位的平均等位基因数为4.780,平均观察杂合度和期望杂合度分别为0.748和0.674);但模拟结果显示,该迁地保护江豚群体的遗传多样性将快速下降,100年后仅能保留约79%的等位基因和约84%的遗传杂合度。此外,模拟结果表明,通过增加群体数量和调整群体性比可有效减缓该群体遗传多样性的下降速度。根据研究结果,并结合长江江豚自然种群快速下降的现状,作者提出天鹅洲迁地保护江豚群体当前最重要的保护策略应该是尽早补充一定数量的、合适的野生个体,在加强遗传多样性保护的同时使其群体数量快速增长并形成一个更大规模的有效繁殖群体。     

The effect of bacteria on interspecific relationships between the euryhaline rotifer Brachionus rotundiformis and the harpacticoid copepod Tigriopus japonicus

Inconsistent results have been obtained on the population growth of Brachionus rotundiformis and Tigriopus japonicus, when results from single-species and two-species mixed cultures are compared. Bacteria growth was not regulated in these experiments, which could be the cause for this. In order to test this possibility, we conducted similar experiments under axenic and synxenic (with presence of one species of bacteria) conditions. The population growth of B. rotundiformis was suppressed by the presence of T. japonicus in axenic cultures. T. japonicus could not persist in axenic cultures, but its population increased when grown in synxenic cultures. T. japonicus used RT bacteria strain as a food source, while these bacteria were toxic to B. rotundiformis. These results suggest that bacteria can modify the interspecific relationship between B. rotundiformis and T. japonicus.     

Complete mitochondrial genome of three Branchiostegus (Perciformes, Malacanthidae) species: genome description and phylogenetic considerations

We cloned and sequenced the complete mitochondrial DNA (mtDNA) of three tilefishes (Branchiostegus albus, Branchiostegus argentatus, and Branchiostegus japonicus) to characterize and compare their mitochondrial genomes (mitogenomes). The mitogenomes of B. albus, B. argentatus, and B. japonicus were 16,532, 16,550, and 16,541 bp long, respectively, and all consisted of 37 genes (13 protein-coding genes, 2 ribosomal RNA, and 22 transfer RNA (tRNAs)), which are typical for vertebrate mtDNA. As in other bony fishes, most genes were encoded on the H-strand, except for the nad6 and eight tRNA genes that were encoded on the L-strand. Among the 13 protein-coding genes of all three tilefishes, 2 reading-frame overlaps were found on the same strand: atp8 and atp6 overlapped by 10 nucleotides, and nad4L and nad4 overlapped by 7 nucleotides. The identity of the nad4 gene between B. albus and B. argentatus was the lowest at 87%. Conversely, the identity of the nad6 gene between B. albus and B. japonicus was the highest at 99%. Most tRNA genes were similar in length among the three species, while the tRNA-Ser((AGY)) of B. japonicus was 9 bp longer than those of B. albus and B. argentatus. The control region of the mitogenome spanned 853, 862, and 856 bp in B. albus, B. argentatus, and B. japonicus, respectively. A maximum likelihood tree constructed using 11,035 sites contained five independent groups with bootstrap values of 100% in support of their divergence. All three tilefishes examined were clustered with the Pomacanthidae species in Group II.     

Blockade of CD86 signaling facilitates a Th2 bias at the maternal-fetal interface and expands peripheral CD4+CD25+ regulatory T cells to rescue abortion-prone fetuses

Intervention in B7 (CD80/CD86)/B7-ligand (CD28/CTLA-4) pathways is an effective way of preventing unwanted immune responses, such as allograft rejection. Pregnancy maintenance represents maternal tolerance to the fetal allograft, which is accompanied by a type 2 helper cell (Th2) bias at the maternal-fetal interface. Here, the costimulatory signal of CD86 was selectively blocked, and that of CD80 was kept unimpaired by administration of anti-murine CD86 monoclonal antibody at the early gestational stage in abortion-prone CBA/JxDBA/2 matings and normal pregnant CBA/JxBALB/c matings. It was demonstrated that in vivo blockade of CD86 costimulation could suppress maternal immune attack to the fetus by shifting cytokines from Th1 predominance to Th2 bias at the maternal-fetal interface, and expanding peripheral CD4+CD25+ regulatory T cells, which play an important role in the development and maintenance of maternal-fetal tolerance. Furthermore, the expression of CD28 and its ligands CD80/CD86 on peripheral lymphocytes was down-regulated, whereas that of CTLA-4 was up-regulated, which might facilitate the suppressive effect of CD4+CD25+ regulatory T cells on the alloreactive T cells. The maternal-fetal immunotolerance induced by CD86 blockade decreased fetal resorption in CBA/JxDBA/2 matings, but did not affect normal pregnant CBA/JxBALB/c matings. These results suggest that selective blockade of CD86 costimulation leads to maternal immune tolerance to embryo antigen, and might contribute to a rational immunoregulatory regimen for recurrent spontaneous abortion.