浙江大学农学院昆虫研究所陈学新教授课题组在一项关于蜜蜂的研究中发现，中华蜜蜂之所以比意大利蜜蜂具有更强的抗寒能力和抗病能力，是因为意大利蜜蜂在更为长期的驯化过程中丧失了某些基因。据悉，这一发现首次用实验的方式证实了长期驯化可能导致生物基因多样性降低的理论假设。
中华蜜蜂
据介绍，中华蜜蜂和意大利蜜蜂都起源于约1000万年前的亚洲，是一对非常相近的“姐妹”物种。由于蜂蜜产量高，易于管理，意大利蜜蜂很早就被人类驯化饲养，目前驯养范围遍及全世界，已经没有野生种群。而作为中国土生土长的重要蜜蜂种类，中华蜜蜂虽然也被人类驯化饲养，但目前仍然存在野生种群。此前科学家在研究中发现，中华蜜蜂比意大利蜜蜂更加耐寒，更能抵御病害浸染和螨虫危害，并能为更多种类的植物尤其是高山植物传授花粉。
陈学新教授课题组经过四年的研究认为，蜜蜂体内与免疫相关的物质——抗菌肽是导致这对“姐妹”物种存在差异的重要线索。该课题组利用分子生物学、比较基因组学和生物信息学等手段，克隆并鉴定了中华蜜蜂和意大利蜜蜂的体内基因都来自4个抗菌肽基因家族。这些基因对革兰氏阴性和阳性菌，其中包括一些人类疾病的致病菌都具有抗菌活性。其不同之处在于，中华蜜蜂体内存在87个不同的基因，共编码26种不同的抗菌肽；意大利蜜蜂则为16个基因、11种抗菌肽。
陈学新说，抗菌肽是生物体内普遍存在的、在免疫防御体系中发挥重要作用的生物活性物质。由于这两种蜜蜂的抗菌肽家族具有明显的不同，当他们同时受到病原侵袭时，中华蜜蜂会因其具有明显的抗菌肽基因优势和更为丰富的抗菌肽物质免受其害。
该课题组的相关论文近日发表在美国《公共科学图书馆·综合》（PLoS ONE）杂志上。杂志的评审专家认为，该研究首次全部鉴定了一个物种所有抗菌肽因家族的系统研究，获得了有趣的科学发现并富有重要价值，在实践上为进一步保护和利用蜜蜂及其重要的抗菌类物质提供了重要的科学依据。（生物谷Bioon.com）
生物谷推荐原始出处：
PLoS ONE 4(1): e4239. doi:10.1371/journal.pone.0004239
Antimicrobial Peptide Evolution in the Asiatic Honey Bee Apis cerana
Peng Xu, Min Shi, Xue-xin Chen*
Institute of Insect Sciences, Zhejiang University, Hangzhou, Zhejiang, China
Abstract
The Asiatic honeybee, Apis cerana Fabricius, is an important honeybee species in Asian countries. It is still found in the wild, but is also one of the few bee species that can be domesticated. It has acquired some genetic advantages and significantly different biological characteristics compared with other Apis species. However, it has been less studied, and over the past two decades, has become a threatened species in China. We designed primers for the sequences of the four antimicrobial peptide cDNA gene families (abaecin, defensin, apidaecin, and hymenoptaecin) of the Western honeybee, Apis mellifera L. and identified all the antimicrobial peptide cDNA genes in the Asiatic honeybee for the first time. All the sequences were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). In all, 29 different defensin cDNA genes coding 7 different defensin peptides, 11 different abaecin cDNA genes coding 2 different abaecin peptides, 13 different apidaecin cDNA genes coding 4 apidaecin peptides and 34 different hymenoptaecin cDNA genes coding 13 different hymenoptaecin peptides were cloned and identified from the Asiatic honeybee adult workers. Detailed comparison of these four antimicrobial peptide gene families with those of the Western honeybee revealed that there are many similarities in the quantity and amino acid components of peptides in the abaecin, defensin and apidaecin families, while many more hymenoptaecin peptides are found in the Asiatic honeybee than those in the Western honeybee (13 versus 1). The results indicated that the Asiatic honeybee adult generated more variable antimicrobial peptides, especially hymenoptaecin peptides than the Western honeybee when stimulated by pathogens or injury. This suggests that, compared to the Western honeybee that has a longer history of domestication, selection on the Asiatic honeybee has favored the generation of more variable antimicrobial peptides as protection against pathogens.
