Shell-boring species Polydora brevipalpa Zachs, 1933 is redescribed based on morphological observations and molecular approach for future unambiguous identification. Genetic distance analyses showed that the interspec...Shell-boring species Polydora brevipalpa Zachs, 1933 is redescribed based on morphological observations and molecular approach for future unambiguous identification. Genetic distance analyses showed that the interspecific polydorid variation (16.7%–25.6%) was at least 15 times higher than the intraspecific one (0.2%–0.9%) based on the cytochrome c oxidase subunit I (CO1) gene sequences of polydorids. However, 18S rDNA variation pattern demonstrated a rather narrow barcoding gap, with the interspecific polydorid variation (0.5%–5.6%) being very close to the intraspecific one (0.0%–0.4%). As such, the CO1 gene exhibited better DNA barcode for identification of polydorids than the 18S rDNA gene because of the sufficiently large barcoding gaps. Analysis of molecular variance results based on CO1 gene sequences showed that most variations in sequences (97.79%) lay within groups of adult worms and egg capsules rather than between them. This indicated that egg capsules from Crassostrea gigas (Thunberg, 1793) in Ningbo and Nantong were related to the adult worms from Patinopecten yessoensis (Jay, 1857) in Dalian, and both of them belonged to P . brevipalpa . This result was further supported by parsimony network analysis, which showed that egg capsules collected from diff erent localities and adult worms shared a single haplotype. This study was the first to report both P . brevipalpa infestation on C . gigas and to utilise the known CO1 sequences of the adult polydorids to validate morphologically unidentified egg capsules or early larvae. P . brevipalpa was most possibly brought to Chinese waters through transportation of Pa . yessoensis brood stock from Japan.展开更多
Spionid worms of Polydora ciliata inhabit the shells of many commercially important bivalves and cause disease in molluscan aquaculture. Their sperm structure is closely related to their fertilization method. To give ...Spionid worms of Polydora ciliata inhabit the shells of many commercially important bivalves and cause disease in molluscan aquaculture. Their sperm structure is closely related to their fertilization method. To give an insight into the sperm structure and spermatogenesis, ultrastructure details of the subcellular components of germ cells during spermiogenesis of Polydora ciliata are detected by transmission electron microscopy(TEM). In P. ciliata, during spermiogenesis, chromatin is regularly arranged as dense fibrils and becomes more condensed when the nucleus elongates. Microtubules do not surround the nucleus during its elongation. The Golgi phase is characterized by the formation of proacrosomal granules within the Golgi apparatus. The proacrosomal granules fuse to form a single, spherical acrosomal vesicle that migrates to the anterior pole of the cell. At the time of nuclear condensation, mitochondria become reduced in number but increased in size, causing deep indentation at the base of the nucleus. The mid-piece has a few mitochondria. The cap phase includes the spreading of the acrosomal granule over the surface of the nucleus of the differentiating spermatid. The acrosomal phase of spermiogenesis is typically associated with changes in the shape of the nucleus, acrosome and tail. The relationship of sperm ultrastructure to spermiogenesis in spionidae species was discussed.展开更多
基金Supported by the National Natural Science Foundation of China(No.31301863)the Pearl River S&T Nova Program of Guangzhou(No.201710010166)+2 种基金the Natural Science Foundation of Guangdong Province(No.2018A030313349)the Special Scientific Research Funds for Central Non-profit Institutes,South China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences(No.2017YB08)the earmarked fund for Modern Agro-industry Technology Research System(No.CARS-49)
文摘Shell-boring species Polydora brevipalpa Zachs, 1933 is redescribed based on morphological observations and molecular approach for future unambiguous identification. Genetic distance analyses showed that the interspecific polydorid variation (16.7%–25.6%) was at least 15 times higher than the intraspecific one (0.2%–0.9%) based on the cytochrome c oxidase subunit I (CO1) gene sequences of polydorids. However, 18S rDNA variation pattern demonstrated a rather narrow barcoding gap, with the interspecific polydorid variation (0.5%–5.6%) being very close to the intraspecific one (0.0%–0.4%). As such, the CO1 gene exhibited better DNA barcode for identification of polydorids than the 18S rDNA gene because of the sufficiently large barcoding gaps. Analysis of molecular variance results based on CO1 gene sequences showed that most variations in sequences (97.79%) lay within groups of adult worms and egg capsules rather than between them. This indicated that egg capsules from Crassostrea gigas (Thunberg, 1793) in Ningbo and Nantong were related to the adult worms from Patinopecten yessoensis (Jay, 1857) in Dalian, and both of them belonged to P . brevipalpa . This result was further supported by parsimony network analysis, which showed that egg capsules collected from diff erent localities and adult worms shared a single haplotype. This study was the first to report both P . brevipalpa infestation on C . gigas and to utilise the known CO1 sequences of the adult polydorids to validate morphologically unidentified egg capsules or early larvae. P . brevipalpa was most possibly brought to Chinese waters through transportation of Pa . yessoensis brood stock from Japan.
基金supported by the National Key Technology Support Program (2011BAD13B05)
文摘Spionid worms of Polydora ciliata inhabit the shells of many commercially important bivalves and cause disease in molluscan aquaculture. Their sperm structure is closely related to their fertilization method. To give an insight into the sperm structure and spermatogenesis, ultrastructure details of the subcellular components of germ cells during spermiogenesis of Polydora ciliata are detected by transmission electron microscopy(TEM). In P. ciliata, during spermiogenesis, chromatin is regularly arranged as dense fibrils and becomes more condensed when the nucleus elongates. Microtubules do not surround the nucleus during its elongation. The Golgi phase is characterized by the formation of proacrosomal granules within the Golgi apparatus. The proacrosomal granules fuse to form a single, spherical acrosomal vesicle that migrates to the anterior pole of the cell. At the time of nuclear condensation, mitochondria become reduced in number but increased in size, causing deep indentation at the base of the nucleus. The mid-piece has a few mitochondria. The cap phase includes the spreading of the acrosomal granule over the surface of the nucleus of the differentiating spermatid. The acrosomal phase of spermiogenesis is typically associated with changes in the shape of the nucleus, acrosome and tail. The relationship of sperm ultrastructure to spermiogenesis in spionidae species was discussed.
基金This study was supported by research grants from the National Natural Science Foundation of China(No.40906084)Special Research Fund for the National Non-profit(No.2008M16)~~
