Yolk protein is expressed in the insect testis and interacts with sperm.
Yolk protein is expressed in the insect testis and interacts with sperm.
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DOI：
10.1186/1471-213x-8-64
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发表时间：
2008-06-13
影响因子：
--
通讯作者：
Giebultowicz JM
中科院分区：
文献类型：
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作者：
Bebas P;Kotwica J;Joachimiak E;Giebultowicz JM
雄性和雌性配子遵循不同的发育途径，这取决于它们在受精过程中的不同作用。卵生动物的卵母细胞在细胞质中积累卵黄，而精子在个体化过程中会斯劳大部分细胞质。哺乳动物精子从睾丸中释放出来后，在精道中经历了广泛的修饰，包括各种糖蛋白。超微结构的研究表明，糖蛋白参与精子成熟在昆虫，然而，它们的表征在分子水平上是缺乏的。我们以前报道过，生物钟控制着几种昆虫精子的释放和成熟。在蛾，Spodoptera littoralis，糖蛋白分泌到精液中发生在每天的节奏模式。本研究的目的是在这个物种的精液糖蛋白的特点，并阐明其在精子成熟过程中的作用。我们收集了男性精液蛋白之前和之后的每日精子释放。这些样品通过2-D凝胶电泳分离，并且用糖蛋白检测探针处理凝胶。我们在精子释放后采集的样本中观察到一组丰富的糖蛋白，这在精子释放前采集的样本中是不存在的。通过质谱对这些糖蛋白进行测序，揭示了与蛋黄组分具有同源性的肽，已知蛋黄在发育中的卵母细胞中积累。这一意想不到的结果通过Western印迹证实，表明精液中含有对在发育卵母细胞周围的卵泡细胞中产生的卵黄蛋白YP 2的抗体具有免疫反应性的蛋白质。我们克隆了S. littoralis，并确定它在卵巢和睾丸中表达。在睾丸内包裹精子的体细胞囊胞中检测到yp 2 mRNA和YP 2蛋白。在精子释放期间，YP 2蛋白出现在精液中，并在精子上形成外被膜。其中一种卵黄蛋白前体YP 2在雌性中积累在卵母细胞中以提供发育中的胚胎，似乎具有第二种雄性特异性作用。它在睾丸中产生并释放到精液中，在那里它与精子相互作用。这些数据揭示了昆虫卵和精子成熟过程中意想不到的共同因素。
Male and female gametes follow diverse developmental pathways dictated by their distinct roles in fertilization. While oocytes of oviparous animals accumulate yolk in the cytoplasm, spermatozoa slough off most of their cytoplasm in the process of individualization. Mammalian spermatozoa released from the testis undergo extensive modifications in the seminal ducts involving a variety of glycoproteins. Ultrastructural studies suggest that glycoproteins are involved in sperm maturation in insects; however, their characterization at the molecular level is lacking. We reported previously that the circadian clock controls sperm release and maturation in several insect species. In the moth, Spodoptera littoralis, the secretion of glycoproteins into the seminal fluid occurs in a daily rhythmic pattern. The purpose of this study was to characterize seminal fluid glycoproteins in this species and elucidate their role in the process of sperm maturation. We collected seminal fluid proteins from males before and after daily sperm release. These samples were separated by 2-D gel electrophoresis, and gels were treated with a glycoprotein-detecting probe. We observed a group of abundant glycoproteins in the sample collected after sperm release, which was absent in the sample collected before sperm release. Sequencing of these glycoproteins by mass spectroscopy revealed peptides bearing homology with components of yolk, which is known to accumulate in developing oocytes. This unexpected result was confirmed by Western blotting demonstrating that seminal fluid contains protein immunoreactive to antibody against yolk protein YP2 produced in the follicle cells surrounding developing oocytes. We cloned the fragment of yp2 cDNA from S. littoralis and determined that it is expressed in both ovaries and testes. yp2 mRNA and YP2 protein were detected in the somatic cyst cells enveloping sperm inside the testis. During the period of sperm release, YP2 protein appears in the seminal fluid and forms an external coat on spermatozoa. One of the yolk protein precursors YP2, which in females accumulate in the oocytes to provision developing embryos, appears to have a second male-specific role. It is produced in the testes and released into the seminal fluid where it interacts with sperm. These data reveal unexpected common factor in the maturation of insect eggs and sperm.