Formation of Diapause Cyst Shell in Brine Shrimp, Artemia parthenogenetica, and Its Resistance Role in Environmental Stresses
Formation of Diapause Cyst Shell in Brine Shrimp, Artemia parthenogenetica, and Its Resistance Role in Environmental Stresses
复制标题
丰年虾滞育囊壳的形成及其对环境胁迫的抵抗作用
DOI：
10.1074/jbc.m109.004051
复制
发表时间：
2009-06-19
影响因子：
4.8
通讯作者：
Yang, Wei-Jun
中科院分区：
文献类型：
--
作者：
Liu, Yu-Lei;Zhao, Yang;Yang, Wei-Jun
卤虫在极端恶劣的环境条件下产生包裹在保护壳中的包囊胚胎的能力引起了人们的广泛关注。然而，囊壳是由什么合成的，以及形成过程是如何进行的，迄今为止，在很大程度上仍然是未知的。通过对卵生和卵胎生卤虫cDNA消减文库的筛选，获得了20多个卵生卤虫特异表达基因。其中，壳腺特异表达基因（SGEG）已被发现参与囊壳的形成。缺乏SGEG蛋白（通过RNA干扰）导致囊壳变得半透明，壳的绒毛膜层变得不那么致密和粉质，并显示壳内铁组成的显着减少。RNA干扰诱导有缺陷的滞育囊肿与完全妥协的可扩展性，紫外线照射，非常大的温差，渗透压，干燥，和有机溶剂应力。相比之下，天然囊肿将提供充分的保护，免受所有这些因素的影响。SGEG包含一个345 bp的开放阅读框，其相应翻译的肽段由一个33个氨基酸残基的推定信号肽和一个81个氨基酸残基的成熟肽组成。北方杂交和原位杂交结果表明，该基因在卵生卤虫滞育包囊形成期的壳腺细胞中特异表达。这项调查增加了强大的洞察卤虫囊壳形成的机制，并可能适用于极端微生物生物学的其他研究领域。
Artemia has attracted much attention for its ability to produce encysted embryos wrapped in a protective shell when subject to extremely harsh environmental conditions. However, what the cyst shell is synthesized from and how the formative process is performed remains, as yet, largely unknown. Over 20 oviparous specifically expressed genes were identified through screening the subtracted cDNA library enriched between oviparous and ovoviviparous Artemia ovisacs. Among them, a shell gland-specifically expressed gene (SGEG) has been found to be involved in the cyst shell formation. Lacking SGEG protein (by RNA interference) caused the cyst shell to become translucent and the chorion layer of the shell to become less compact and pultaceous and to show a marked decrease of iron composition within the shell. The RNA interference induced defective diapause cysts with a totally compromised resistibility to UV irradiation, extremely large temperature differences, osmotic pressure, dryness, and organic solvent stresses. In contrast, the natural cyst would provide adequate protection from all such factors. SGEG contains a 345-bp open reading frame, and its consequentially translated peptide consists of a 33-amino acid residue putative signal peptide and an 81-amino acid residue mature peptide. The results of Northern blotting and in situ hybridization indicate that the gene is specifically expressed in the cells of shell glands during the period of diapause cyst formation of oviparous Artemia. This investigation adds strong insight into the mechanism of cyst shell formation of Artemia and may be applicable to other areas of research in extremophile biology.