Pauletto Marianna, Milan Massimo, de Sousa Joana Teixeira, Huvet Arnaud, Joaquim Sandra, Matias Domitília, Leitão Alexandra, Patarnello Tomaso, Bargelloni Luca
Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy.
IFREMER, Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire des Sciences de l'Environnement Marin, Plouzané, France; IPMA, Instituto Português do Mar e da Atmosfera, Olhão, Portugal.
PLoS One. 2014 Dec 3;9(12):e113925. doi: 10.1371/journal.pone.0113925. eCollection 2014.
The production of Venerupis decussata relies on wild seed collection, which has been recently compromised due to recruitment failure and severe mortalities. To address this issue and provide an alternative source of seed, artificial spawning and larval rearing programs were developed. However, hatchery-based seed production is a relatively new industry and it is still underdeveloped. A major hurdle in the European clam seed production is the control of spawning and reproduction, which is further hindered by the impossibility of obtaining fertile gametes by gonadal "stripping", as meiosis re-initiation is constrained to a maturation process along the genital ducts. In the present study, oocytes were collected from 15 females and microarray analyses was performed to investigate gene expression profiles characterizing released and stripped ovarian oocytes. A total of 198 differentially expressed transcripts between stripped and spawned oocytes were detected. Functional analysis carried out on these transcripts highlighted the importance of a few biological processes, which are most probably implicated in the control of oocyte competence. Significant differences were observed for transcripts encoding proteins involved in meiosis progression (e.g. dual specificity phosphatase CDC25), WNT signalling (e.g. frizzled class receptor 8, wingless-type MMTV integration site family member 4), steroid synthesis (e.g. progestin and adipoQ receptor family member 3, cytochrome P450-C17), mRNA processing (e.g. zinc finger protein XlCOF28), calcium regulation (e.g. regucalcin, calmodulin) and ceramide metabolism (ceramidase B, sphingomyelinase). This study provides new information on transcriptional profiles putatively associated with ovarian egg infertility, and suggests potential mechanisms regulating early oocyte development in clams. Genes which were differentially expressed between stripped and spawned oocytes might have a pivotal role during maturation process in the gonadal duct and could be interesting targets for further functional studies aiming to make ovarian oocytes fertilizable.
四角蛤蜊的生产依赖于野生种子采集，然而，由于补充失败和严重死亡，这一方式近来受到了影响。为了解决这一问题并提供种子的替代来源，人们开展了人工产卵和幼体培育计划。然而，基于孵化场的种子生产是一个相对较新的行业，仍不发达。欧洲蛤蜊种子生产的一个主要障碍是产卵和繁殖的控制，由于性腺“挤压”无法获得可育配子，这一障碍进一步加剧，因为减数分裂的重新启动被限制在沿着生殖管道的成熟过程中。在本研究中，从15只雌性蛤蜊中收集了卵母细胞，并进行了微阵列分析，以研究表征释放和挤压的卵巢卵母细胞的基因表达谱。在挤压和产卵的卵母细胞之间共检测到198个差异表达的转录本。对这些转录本进行的功能分析突出了一些生物学过程的重要性，这些过程很可能与卵母细胞能力的控制有关。在编码参与减数分裂进程的蛋白质（如双特异性磷酸酶CDC25）、WNT信号传导（如卷曲类受体8、无翅型MMTV整合位点家族成员4）、类固醇合成（如孕激素和脂联素受体家族成员3、细胞色素P450-C17）、mRNA加工（如锌指蛋白XlCOF28）、钙调节（如钙调蛋白、钙调素）和神经酰胺代谢（神经酰胺酶B、鞘磷脂酶）的转录本中观察到显著差异。本研究提供了与卵巢卵不育相关的转录谱的新信息，并提出了调节蛤蜊早期卵母细胞发育的潜在机制。在挤压和产卵的卵母细胞之间差异表达的基因可能在性腺管的成熟过程中起关键作用，并且可能是旨在使卵巢卵母细胞可受精的进一步功能研究的有趣靶点。
