菜粉蝶对两种迁地保护的兰科植物传粉和繁殖成功的作用

迁地保护是防止物种灭绝的有效措施。为了解在新栖息地兰科植物与昆虫之间的关系, 从而为兰科植物的保护提供借鉴, 作者对迁地栽培于深圳市全国兰科植物种质资源保护中心的本地种血叶兰(Ludisia discolor)和外来种银带虾脊兰(Calanthe argenteo-striata)的传粉系统和繁殖策略进行了观察和研究。血叶兰和银带虾脊兰都具有白色小花组成的花序, 且花有距。在开放栽培条件下, 菜粉蝶(Pieris rapae)是这两种兰科植物唯一有效的传粉者。菜粉蝶携带血叶兰和银带虾脊兰花粉块的部位分别是降落时平衡身体的左侧足部和取食花蜜的喙。两种兰科植物传粉效率较高, 花粉移走与沉降的比值分别为1.14 : 1和0.74 : 1。血叶兰的结实率在2007和2008两年间无显著差异, 且均高于银带虾脊兰。究其原因, 一方面是由于它为传粉者提供报酬; 另一方面是因为血叶兰的花期与菜粉蝶的盛发期相吻合, 有利于充分利用传粉者; 而银带虾脊兰的花期滞后于菜粉蝶的盛发期, 传粉者缺失使得部分花未能授粉。血叶兰和银带虾脊兰都是高度自交亲和的物种, 但不存在无融合生殖和自动自花授粉的现象; 自交和异交的繁殖成功率无显著差异。这两种兰科植物可能存在由传粉者导致的自交现象。血叶兰和银带虾脊兰在迁地栽培到兰科中心后生长良好, 每年花期都有自然结果的现象, 植株周围有新生幼苗的建立, 种群有逐渐扩大的趋势, 显示出迁地保护的可行性。可以预测若干年后, 这两个种在兰科中心具有建立稳定种群的可能性。     

Combined Antibacterial Activity of Phage Lytic Proteins Holin and Lysin from Streptococcus suis Bacteriophage SMP

Development of novel antibacterial agents is required to control infection with multidrug-resistant Streptococcus suis. HolSMP and LySMP, the holin and lysin of S. suis serotype 2 bacteriophage, named SMP, are responsible for lysis of host cells and release of progeny phage. HolSMP and LySMP expressed in Escherichia coli BL21(DE3) exerted efficient activity at 37?°C, pH 5.2, with addition of 0.8?% β-mercaptoethanol. Lytic spectra of purified HolSMP, LySMP or HolSMP?+?LySMP mixture were investigated. HolSMP, exhibiting a narrow lytic spectrum, was effective against Staphylococcus aureus and Bacillus subtilis, which were insensitive to LySMP. Moreover, HolSMP was identified as a promising antibacterial agent which was able to extend the spectrum of LySMP. The data suggest that combined use of holin and lysin could be a candidate strategy for resolution of drug resistance.     

MicroRNA-25 promotes cell migration and invasion in esophageal squamous cell carcinoma

MicroRNAs (miRNAs) as a species of small non coding single stranded RNA of about 21-25 nucleotides have important roles in the development of different cancers. In present study, we found that the expression of miR-25 was up-regulated in 60 esophageal squamous cell carcinoma (ESCC) tissues compared with matched adjacent non-cancer tissues. Moreover, we demonstrated that the up-regulation of miR-25 was significantly correlated with the status of lymph node metastasis and TNM (Tumor, Node and Metastasis) stage. Furthermore, over-expression of miR-25 markedly promoted migration and invasion of ESCC cells. On the contrary, down-regulation of miR-25 inhibited the migration and invasion of cells. E-cadherin(CDH1) is a very important tumor metastasis suppressor. We further identified that miR-25 directly targeted CDH1 3'-untranslated region (3'UTR) and repressed the expression of CDH1. These results, for the first time, demonstrate that miR-25 promotes ESCC cell migration and invasion by suppressing CDH1 expression.     

Fly pollination in Cypripedium: a case study of sympatric C. sichuanense and C. micranthum

Most Cypripedium spp. are known to be pollinated by bees. However, myiophilous traits are found in some species, especially in sections Trigonopedia and Sinopedilum. Here we chose C. micranthum and C. sichuanense, two sympatric species endemic to Sichuan, China, to test whether these orchids are fly pollinated. Artificial pollination showed that both flowers are self‐compatible but need pollen vectors for successful reproduction. Field observation showed that C. micranthum was pollinated by fruit flies and C. sichuanense by dung flies, both novel pollinators of Cypripedium orchids. These sympatric Cypripedium spp. are also cross‐compatible, but hybrids were not found in nature. The pollination syndromes of C. sichuanense and C. micranthum fit into the complex sapromyiophily pattern. It appears that pollinator specificity is responsible for their reproductive isolation. The discovery of fly pollination in C. sichuanense and C. micranthum, which belong to the related sections Trigonopedia and Sinopedilum, suggests a shift from bee to fly pollination in the genus Cypripedium. Unlike most Cypripedium spp., the anthers of C. micranthum release discrete pollinia with narrow stalks instead of the usual amorphous pollen smears. This ‘proto‐pollinarium’ is described, probably for the first time. These pollinia are most likely an adaptation for pollination by microdiptera, so the fly can carry the contents of both chambers in the same anther. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 50–58.     

Nudel is crucial for the WAVE complex assembly in vivo by selectively promoting subcomplex stability and formation through direct interactions

The WAVE regulatory complex (WRC), consisting of WAVE, Sra, Nap, Abi, and HSPC300, activates the Arp2/3 complex to control branched actin polymerization in response to Rac activation. How the WRC is assembled in vivo is not clear. Here we show that Nudel, a protein critical for lamellipodia formation, dramatically stabilized the Sra1-Nap1-Abi1 complex against degradation in cells through a dynamic binding to Sra1, whereas its physical interaction with HSPC300 protected free HSPC300 from the proteasome-mediated degradation and stimulated the HSPC300-WAVE2 complex formation. By contrast, Nudel showed little or no interactions with the Sra1-Nap1-Abi1-WAVE2 and the Sra1-Nap1-Abi1-HSPC300 complexes as well as the mature WRC. Depletion of Nudel by RNAi led to general subunit degradation and markedly attenuated the levels of mature WRC. It also abolished the WRC-dependent actin polymerization in vitro and the Rac1-induced lamellipodial actin network formation during cell spreading. Therefore, Nudel is important for the early steps of the WRC assembly in vivo by antagonizing the instability of certain WRC subunits and subcomplexes.     

花颜色和花气味的量化研究方法

花颜色和花气味是花部构成的重要内容。在已开展的传粉生态学研究中对二者的报道主要是描述性的,而其量化研究可以为揭示传粉机制提供有力的实验证据。本文主要介绍了花颜色的测量和标定方法,包括比色卡、分光色差仪和便携式光谱仪等;花气味的采集方法,包括动态顶空套袋-吸附采集法、吸附-溶剂洗脱法和固相微萃取法等;花气味的检测和分析方法,包括气相色谱-质谱联用仪分析和电子鼻型超速气相色谱仪分析等;以及昆虫行为学实验方法,包括气相色谱-昆虫触角电位联用技术、Y型嗅觉仪和飞行箱实验等。科研人员可以根据实验材料的特点和实验目的选择适合的量化研究方法。     

余氯对水生生物的影响

氯是滨河、滨海企业冷却水常用的防治污损生物的处理剂。总结近年来国内外氯在企业冷却水中的应用、氯对浮游植物、浮游动物、贝类、鱼类等影响的研究成果,为制定冷却水余氯排放标准和水产养殖的合理布局提供了参考,针对我国大量滨海电厂即将建立的现状,分析了余氯研究在中国海域研究的不足,提出了氯对我国海洋生物影响不同层面的研究方向。认为氯对生物种群的毒性,氯对生物群落组成、结构和生态演替的影响,以及减轻或避免余氯污染的对策是需要进一步解决的科学问题。