不同细菌对家蝇幼虫抗菌蛋白/肽的诱导效应

利用抑菌圈测量法和毛细管电泳研究、比较不同细菌对家蝇Musca domesticaL.幼虫抗菌蛋白/肽的诱导效应。结果表明,家蝇幼虫受细菌诱导后抗菌活性比对照都有不同程度的增加,同时不同细菌诱导表达样品对于相应的诱导菌均表现很高的抗菌活性。毛细管电泳图谱表明鼠伤寒沙门氏菌Salmonella typhimurium50013诱导后抗菌蛋白/肽表达强度增加了50倍,其它细菌诱导后抗菌蛋白/肽表达强度增加了1～40倍。与G+细菌相比,G-细菌具有更强的诱导效应。结论:家蝇幼虫对不同的细菌刺激有特异性反应,即不同细菌诱导抗菌蛋白/肽的强度、种类和数量都不一致。     

The mechanism of background extinction

Following publication of On the Origin of Species, biologists concentrated on and resolved the mechanisms of adaptation and speciation, but largely ignored extinction. Thus, extinction remained essentially a discipline of palaeontology. Adequate language is not available to describe extinction phenomena because they must be discussed in the passive voice, wherein populations simply ‘go extinct’ without reference to process, specifics, effects, or causality. Extinction is also described typically in terms of its dynamics (including rate or risk), and although correlative variables enhance our ability to predict extinction, they do not necessarily enable an understanding of process. Yet background extinction, like evolution, is a process requiring a functional explanation, without which it is impossible to formulate mechanisms. We define the mechanism of background extinction as a typically long‐term, multi‐generational loss of reproductive fitness. This simple concept has received little credence because of a perception that excess generation of progeny ensures population sustainability, and perhaps the misconception that the loss of reproductive fitness somehow constitutes selection against reproduction itself. During environmental shifts, reproductive fitness is compromised when biotic or abiotic extremes consistently exceed existing norms of reaction. Subsequent selection will now favour individual survival over reproductive fitness, initiating long‐term negative selection pressure and population decline. Background extinction consists typically of two intergrading phases: habitat attenuation and habitat dissolution. These processes generate the relict populations that characterize many species undergoing background extinction. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 255–268.     

双价抗病基因导入籽瓜的遗传转化研究

以籽瓜主栽品种新籽瓜2号、五原籽瓜等为研究材料,用苗龄1-3d的子叶切块作外植体,不定芽诱导培养基为MS 6-BA2mg/L IBA 0.1mg/L,芽伸长培养基为MS KT0．2mg／L,诱导生根的培养基是MS IAA0．5mg／L。籽瓜遗传转化研究结果表明农杆菌感染时间以10min,共培养时间以2d为合适。共获得抗卡那霉素100mg／L的试管苗41个,PCR检测呈阳性的有15株,转化率为34．9％。该研究初步建立了籽瓜的遗传转化体系和转化体的检测体系。     

外源质粒pcDNA3s疫苗在小鼠体内组织代谢动力学研究

为分析外源质粒pcDNA3s肌肉注射后在小鼠体内的组织分布及评价整合到宿主基因组上的可能性．通过PCR方法检测质粒pcDNA3s经肌肉注射在各组织中的分布及随时间变化的情况．检测外源质粒在基因组DNA上的整合情况．注射后3h所有的组织均能检测到质粒,至第3周时只有胸腺和生殖器官能检测到质粒的存在,至第6周后各组织均为阴性、各组织基因组DNA经PCR扩增均为阴性．肌注外源质粒后,外源质粒在小鼠细胞内逐渐被清除,外源质粒不会整合到宿主染色体上．     

多效唑（MET）对啤酒花试管苗生长和移栽的影响

在培养基中加入0.1-0.2mg/L浓度的多效唑（MET）,啤酒花试管苗植株矮壮,单株生根数量增加、移栽成活率提高13％。0．5－2．0mg/L时,试管苗基部愈伤组织增多,枝叶失绿,生长受到抑制。初步发现多将唑对啤酒花试管苗的效力与葡萄糖用量呈正相关。