《环境昆虫学报》

作者	单位
罗生慧，随慧，包静，麦麦提艾力·阿卜杜纳斯尔，刘小宁	1. 新疆大学生命科学与技术学院，新疆生物资源基因工程重点实验室，乌鲁木齐 830046

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中文摘要:

几丁质酶（chitinase, CHT）在昆虫生长发育过程中主要有降解围食膜、外骨骼、角质层以及肠道内层的几丁质成分，从而参与昆虫的蜕皮和细胞增殖的功能。在本研究中，分析比较棉铃虫I型和Ⅶ型几丁质酶HaCHTⅠ、HaCHTⅦ的结构域及其时空表达特性，对的进一步功能研究提供重要的素材。首先利用生物信息学在线工具SMART对本课题组前期所获得的几丁质酶基因HaCHTⅠ、HaCHTⅦ的结构域进行分析；之后采用qRT-PCR方法研究棉铃虫6龄幼虫不同组织和幼虫不同龄期蜕皮前后的中肠中HaCHTⅠ、HaCHTⅦ的时空表达特性。结果表明：对几丁质酶HaCHTⅠ、HaCHTⅦ结构域进行分析，发现HaCHTⅠ和HaCHTⅦ均具有信号肽序列、催化区域、连接区域，且HaCHTⅠ有一个几丁质结合结构域，而HaCHTⅦ则无；棉铃虫Helicoverpa armigera几丁质酶基因HaCHTⅠ和HaCHTⅦ在6龄幼虫不同组织部位的均有表达，其中HaCHTⅠ在各个部位的表达量没有显著的差异，而HaCHTⅦ在头壳和体壁中表达显著高于其它组织；几丁质酶基因HaCHTⅠ、HaCHTⅦ在棉铃虫幼虫蜕皮前后中肠的表达量变化较大，其中HaCHTⅠ在3、4、5、6龄末期及蛹期时的表达量呈递减的趋势，在4、5、6龄初期时表达量则是先减后增的趋势，而HaCHTⅦ在3、4、5、6龄末期及蛹期时的表达量呈递增的趋势，恰与同一时期HaCHTⅠ的表达量相反，在4、5、6龄初期时HaCHTⅦ的表达量呈递减的趋势。棉铃虫HaCHTⅠ和HaCHTⅦ的结构域和时空表达都存在差异，据此我们测这些差异可能对其功能具有一定的影响。本结果为深入研究几丁质酶基因HaCHTⅠ和HaCHTⅦ的功能奠定了基础。

英文摘要:

Chitinase (CHT) mainly degrades chitin in peritrophic membrane, exoskeleton, cuticle, inner intestinal layer and participates in insect molting and cell proliferation during insect growth and development. In this study, we analyzed and compared the structural domains and spatiotemporal expression characteristics of two types of chitinases of H. armigera HaCHTⅠ and HaCHTⅦ, providing important materials for further study of their functions. First, both domains and spatio-temporal expression of chitinase HaCHTⅠ and HaCHTⅦ were analyzed by SMART, an online tool of bioinformatics, and qRT-PCR. The results showed that both HaCHTⅠ and HaCHTⅦ had signal peptide sequence, catalytic domain (CAD) and linker region, and HaCHTⅠ had a chitin-binding domain (CBD), but HaCHTⅦ had no CBD. The results of qRT-PCR showed that the two chitinase genes were expressed in different tissues of the 6th instar larvae of H. armigera. The expression of HaCHTⅠ in different tissues was no significantly difference, but the expression of HaCHTⅦ in the head capsule and integument was significantly higher than that in other tissue. The expression of chitinase genes HaCHTⅠ and HaCHTⅦ in the midgut of H. armigera larvae before and after molting are varied greatly. The expression of HaCHTⅠ decreased gradually at the end of 3rd, 4th, 5th, 6th instar larvae and pupal stage, and decreased firstly and then increased at the early stage of 4th, 5th and 6th instar larvae. On the contrary, the expression of HaCHTⅦ increased gradually at the end of 3rd, 4th, 5th, 6th instar larvae and pupal stage, and decreased gradually at the early stage of 4th, 5th and 6th instar larvae. Both domains and spatio-temporal expression characteristics between HaCHTⅠ and HaCHTⅦ from H. armigera have obvious differences, which indicated that might affect the function of HaCHTⅠ and HaCHTⅦ. The results will lay a foundation for the further study of HaCHTⅠ and HaCHTⅦ function.

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