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ABSTRACT. DDX6 belongs to a family of DEAD-box RNA helicases, which are RNA splicing proteins that ensure the correct folding and structure of mature RNA. Gametogenesis requires the participation of many kinds of RNA. To explore its functions during Eriocheir sinensis gametogenesis, we cloned a full-length DDX6 cDNA sequence from E. sinensis (Es-DDX6) which contains a 1536-nucleotide open reading frame encoding a 512-amino acid protein. Multiple sequence alignments showed that Es-DDX6 has ten conservative DEAD-box family motifs. Tissue expression analysis of Es-DDX6 mRNA and protein levels showed that Es-DDX6 was highly expressed in both the ovary and testis. qRT-PCR analysis revealed the widespread expression of Es-DDX6 mRNA during various stages of gonad development peaking in October. In addition, immunohistochemical studies showed that oocytes and the spermatogonium and primary spermatocytes of testes contained high levels of cytoplasmic Es-DDX6 and decreased expression levels in spermatids. Interestingly, there was no expression of Es-DDX6 in these cells as they matured along the male reproductive system. Since oocytes and spermatocytes are active in meiosis and oocytes undergo 4421 DDX6 characterization and expression during gametogenesis ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (2): 4420-4437 (2015) rapid growth in October, these results provide preliminary evidence that Es-DDX6 plays a role in E. sinensis gametogenesis and oocyte growth processes.

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Summary Length–weight relationships were determined for three fish species (Acanthopagrus latus Houttuyn, 1782; Acentrogobius caninus Valenciennes, 1837; and Nematalosa japonica Regan, 1917). Samples were collected from the East China Sea (N 27.306020, E 120.918026), from May to July in 2015–2016. Samples were collected using commercial trawls (5 cm main trawl and 3 cm codend mesh). Length–weight relationships for these three species were determined for the first time.

SummaryLength-weight relationships were determined for three fish species: Gymnodiptychus pachycheilus (Herzenstein, 1892), Discogobio yunnanensis (Regan, 1907), and Triplophysa pseudostenura (He, Zhang & Song, 2012). Samples were collected from the Yalong River, southwestern China using fishing gear (gillnets, 30 × 15 m, mesh-size 5 mm) and electroshock fishing (CWB-2000 P, 12 V, 250 HZ) in June 2007. Prior to this study, length-weight relationships for these three species were unknown. For two of the species [Discogobio yunnanensis (Regan, 1907) | INTRODUCTIONThe ichthyofauna of southwestern China is extremely diverse (Kang et al., 2014), and the Yalong River is one of its richest water resources with many endemic fish species (Chen, Chen, & He, 2002). However, information on the fishes in this region has been limited to the conservation and management of fishes in the river basin because of recently built hydroelectric power stations on the Yalong River (Dudgeon, 2011). In this study, the length-weight relationships (LWRs) for the three aforementioned fish species were determined. | MATERIALS AND METHODS Specimens | RESULTSSample size, size range, length-weight parameters a and b, and the correlation coefficient (r 2 ) are shown in | DISCUSSIONLWRs of three fish species were determined in this study for the first time. The values of parameter b remained within the expected range of 2.5-3.5 (Froese, 2006). By comparing our results