河西走廊酒泉地区盐碱土未培养放线菌多样性

采用免培养技术对河西走廊酒泉地区的原生盐碱土、次生盐碱土和农田土中的放线菌群落结构及其多样性进行分析.结果表明: 河西走廊酒泉地区原生盐碱土克隆文库分归于19个OTUs,分属于微球菌亚目、丙酸杆菌亚目、棒状杆菌亚目、弗兰克氏菌亚目、假诺卡氏菌亚目和放线菌目未知类群;次生盐碱土克隆文库分归于14个OTUs,分属于微球菌亚目、丙酸杆菌亚目和放线菌目未知类群;农田土克隆文库分归于7个OTUs,分属于微球菌亚目和棒状杆菌亚目;微球菌亚目是3种不同类型土壤中的共有种群,是原生盐碱土和农田土中的优势种群.多样性指数和稀释性曲线分析结果显示,3种不同类型土壤中放线菌种群丰富度为原生盐碱土>次生盐碱土>农田土;原生盐碱土、次生盐碱土的稀释性曲线均未趋于平稳,说明盐碱土中放线菌多样性比实际更加丰富.     

入侵植物加拿大一枝黄花与乡土植物芦苇的相互化感作用

以加拿大一枝黄花和芦苇的共优群落和各自单优群落的种子为化感受体,分析其分别在加拿大一枝黄花和芦苇5个浓度梯度(12.5、25、50、100和200mg·mL-1)浸提液处理下的发芽率和芽长差异,研究2种植物的相互化感作用规律.结果表明:2种植物在共优群落中的千粒重和蒸馏水培养下的发芽率均比单优群落大.加拿大一枝黄花的浸提液对自身种子发芽率在单优和共优群落中均具有在低浓度下(12.5、25 mg·mL-1)轻微促进、中高浓度下(50、100和200mg·mL-1)强烈抑制的作用,其中对共优群落种子的抑制作用尤为显著;而芦苇浸提液对加拿大一枝黄花种子的影响无明显规律.加拿大一枝黄花的种子芽长在单优和共优群落中均随自身浸提液浓度的升高趋于减小,随芦苇浸提液浓度的升高呈波动减小趋势.在芦苇和加拿大一枝黄花浸提液处理下,芦苇种子发芽率在单优群落中均显著大于共优群落(P＜0.05),但2种浸提液处理间无显著差异.     

基于钙黄绿素-铜（Ⅱ）荧光体系测定乙酰半胱氨酸

目的：基于钙黄绿素-铜（Ⅱ）荧光体系测定乙酰半胱氨酸。方法：在pH=8.0的Na2HPO.412H2O-KH2PO4缓冲液中,以492 nm为激发波长,520 nm为发射波长测定乙酰半胱氨酸溶液的荧光强度。结果：在pH=8.0的Na2HPO.412H2O-KH2PO4缓冲液中,二价铜离子与钙黄绿素配位引起荧光猝灭。由于乙酰半胱氨酸中巯基上的硫离子与Cu2＋的亲和力很强,可从钙黄绿素-铜（Ⅱ）的络合物中夺取铜离子而使钙黄绿素游离出来,从而使体系的荧光得以恢复,并且荧光恢复的程度与加入乙酰半胱氨酸的量在一定范围内成线性。结论：建立了一种测定乙酰半胱氨酸的荧光分析新方法,该方法的线性范围为6.0 10-6～1.4 10-5 mol/L,检出限为4.010-6 mol/L。     

结核病免疫机制及疫苗研究进展

结核病是一种棘手的重大传染病.虽然存在一些有一定疗效的治疗药物,亦有预防性疫苗--卡介苗(BCG);但结核病仍在世界范围流行,且发病率和病死率居高不下.结核病的免疫病理机制及疫苗研究近年来取得了一定的进展.结核分枝杆菌通过Toll样受体(TLR)等模式识别受体,激活巨噬细胞的天然免疫反应,清除细菌和调节获得性免疫反应....     

Nitric oxide promotes MPK6‐mediated caspase‐3‐like activation in cadmium‐induced Arabidopsis thaliana programmed cell death

Nitric oxide (NO), a vital cell‐signalling molecule, has been reported to regulate toxic metal responses in plants. This work investigated the effects of NO and the relationship between NO and mitogen‐activated protein kinase (MAPK) in Arabidopsis (Arabidopsis thaliana) programmed cell death (PCD) induced by cadmium (Cd²⁺) exposure. With fluorescence resonance energy transfer (FRET) analysis, caspase‐3‐like protease activation was detected after Cd²⁺ treatment. This was further confirmed with a caspase‐3 substrate assay. Cd²⁺‐induced caspase‐3‐like activity was inhibited in the presence of the NO‐specific scavenger 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (cPTIO), suggesting that NO mediated caspase‐3‐like protease activation under Cd²⁺ stress conditions. Pretreatment with cPTIO effectively inhibited Cd²⁺‐induced MAPK activation, indicating that NO also affected the MAPK pathway. Interestingly, Cd²⁺‐induced caspase‐3‐like activity was significantly suppressed in the mpk6 mutant, suggesting that MPK6 was required for caspase‐3‐like protease activation. To our knowledge, this is the first demonstration that NO promotes Cd²⁺‐induced Arabidopsis PCD by promoting MPK6‐mediated caspase‐3‐like activation.     

The role of the blood meal in egg-laying periodicity and fecundity in Triatoma infestans

The number of eggs produced by Triatoma infestans is determined by the amount of blood ingested; the formation of one egg requires 16 mg blood. An exogenous supply of juvenile hormone, provided by the implantation of extra corpora aliata, increases egg production per unit of blood ingested. The corpus allatum is therefore implicated in the relationship between nutrition and fecundity. The rhythm of egg production is regulated by the nutritional state of the adult female: when the females are fed at frequent intervals, egg production becomes regular and continuous. This calls into question previous interpretations of egg-laying rhythms in the Triatominae as cyclic.     

Life history strategy of Leptinaria unilamellata (d'Orbigny, 1835) (Mollusca,Pulmonata, Subulinidae)

Abstract

Life history theory predicts that the patterns of resource allocation in animals are associated with different strategies, selected in the course of evolution. In the present study, the life history of Leptinaria unilamellata was characterized under laboratory conditions. We determined the growth, reproduction, and longevity patterns of this species and elucidated the strategy related to the development of embryos, through direct observations and examination of the morphology of the gravid uterus. Furthermore, we attempted to analyze the glycogen and galactogen contents of the albumen gland, digestive gland and cephalopedal mass in order to understand energy allocation to life history traits, for three life stages. Leptinaria unilamellata's life history is characterized by great longevity, a short juvenile phase, early sexual maturity, and repeated reproductive events, with little reproductive effort at each event and some mortality shortly after the first reproduction. In the terraria, we found juveniles but no eggs. However, the results of the anatomical study showed no morphological connection between the embryos and the parental organism. Thus, this species should be described as ovoviviparous rather than viviparous. Egg retention in the parent organism is the primary cause of the release of juveniles, instead of eggs, enabling the offspring to withstand environmental stress. The higher quantity of galactogen found in the adults' albumen gland, as compared to juveniles and senescent individuals, as well as the ratio of glycogen to galactogen, reveal the allocation of energy to reproduction rather than to growth. The remaining energy is directed to the maintenance of omeostasis. Such pattern was confirmed by the low levels of glycogen and galactogen observed in the senescent stage, compared to the juvenile and adult stages. In the life strategy of L. unilamellata, the distribution of the reproductive effort among many events associated with ovoviviparity indicates a long-term investment in reproductive success.     

胞外三磷酸腺苷对铅胁迫下植物细胞损伤和过氧化氢及其清除酶水平的调节

细胞外三磷酸腺苷（extracellular adenosine-5'-triphosphate）是植物细胞的重要信号分子。以烟草悬浮细胞BY-2（Nicotiana tabacum L.cv.Bright Yellow-2）为材料,探讨了胞外三磷酸腺苷对铅胁迫下细胞损伤、H₂O₂（过氧化氢）含量及H₂O₂清除酶活性的影响。结果显示,随着Pb（NO₃）₂浓度的不断提高（30~400 μmol·L^-1）,细胞外三磷酸腺苷含量呈现出逐渐下降的趋势,但胞内三磷酸腺苷含量及细胞的受损伤程度逐渐增大;同时,H₂O₂含量和过氧化氢酶的活性均有所上升,并在200 μmol·L^-1 Pb（NO₃）₂处理下达到最大值,而过氧化物酶的活性则不断降低。较之Pb（NO₃）₂胁迫下的细胞,对Pb（NO₃）₂胁迫的细胞加入外源三磷酸腺苷使得细胞受损伤程度显著降低,H₂O₂含量减少,过氧化氢酶活性减弱,而过氧化物酶活性增强。实验结果表明,Pb（NO₃）₂胁迫诱导的植物细胞损伤和H₂O₂及其清除酶水平的变化能受到细胞外三磷酸腺苷水平的调节。