Spermiogenesis and spermatozoon ultrastructure in the Nile catfish Chrysichthys auratus are described using transmission electron microscopy. Spermiogenesis involves some unique peculiarities such as ： the developmen...Spermiogenesis and spermatozoon ultrastructure in the Nile catfish Chrysichthys auratus are described using transmission electron microscopy. Spermiogenesis involves some unique peculiarities such as ： the development of the centriolar complex and the initial segment of the flagellum in a position directly perpendicular to the basal pole of the nucleus, as a result of absence of nuclear rotation ; lack of a cytoplasmic canal during differentiation of the spermatids into spermatozoa; the base of the basal body is not traversed by the basal plate; a basal foot anchors the basal body to the nucleus; and the presence of numerous vesicles around the midpiece and base of the flagellum. In addition, spermiogenesis includes some common features such as： chromatin compaction; formation of a medial shallow nuclear fossa; and elimination of excess cytoplasm. The mature spermatozoon has an elongate conical-shaped head with no acrosome or acrosomal vesicle, a long midpiece with numerous vesicles that continue backwards around the base of the flagellum and a long tail or flagellum, which has no lateral fins or a membranous compartment. The mitochondria lie close to the nucleus basal pole and surround the initial segment of the axoneme and are separated from the flagellum by the inner mitochondrial envelope due to disappearance of the cytoplasmic canal. The flagellum has the classical axoneme structure of a 9 ＋ 2 microtubular pattern. On the basis of the peculiar features mentioned above, it is concluded that spermiogenesis in this Nile catfish is a synapomorphic type derived from types Ⅰ and Ⅱ spermiogenesis, which are common among teleosts. Accordingly, this type could be considered as a novel type of spermiogenesis and could be termed as ＂type Ⅲ＂.展开更多
The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 ...The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 genes were encoded on the heavy strand, while 9 genes were transcribed on the light strand. The non-coding regions of A. dispar included a control region, a light strand replication and another 11 intergenic spacers. The CR of A. dispar contained 8 conserved sequence blocks(CSBs), a termination-associated sequence(TAS) and a pyrimidine tract. Phylogenetic analysis based on 12 PCGs revealed that A. dispar was genetically closest to Arius arius. The families Schilbeidae, Claroteidae, Mochokidae, and Ariidae formed a closely evolved clade. Molecular information from this research introduces mitogenomice data of A. dispar and suggests the phylogenetic relationships among Siluriformes.展开更多
Occurrence of neurotoxic chemicals in the aquatic environment is on the rise posing a potential threat to aquatic biota including fish.In teleosts,zebrafish has become a popular model organism for toxicological studie...Occurrence of neurotoxic chemicals in the aquatic environment is on the rise posing a potential threat to aquatic biota including fish.In teleosts,zebrafish has become a popular model organism for toxicological studies and testing strategies.However,over the decade,siluriformes(catfish)are also finding ever increasing application being robust as well as their adaptability to adverse ecological conditions,surgical interventions,and tolerant models for toxicity studies and manipulations.Such information can infer potential effects occurring to other species exposed to neurotoxins in their aquatic environment and predicting potential risks of a chemical for the aquatic ecosystem.The aim of this review is to compare and interpret recent results published concerning neuro-behavioral and morphological disturbances caused by toxicants/pollutants providing a holistic view of potential neurotoxic outcomes in catfish.Overall,this review summarizes various effects of toxicants/pollutants in terms of neurotoxicity and neurodegeneration associated with behavioral phenotypes.展开更多
文摘Spermiogenesis and spermatozoon ultrastructure in the Nile catfish Chrysichthys auratus are described using transmission electron microscopy. Spermiogenesis involves some unique peculiarities such as ： the development of the centriolar complex and the initial segment of the flagellum in a position directly perpendicular to the basal pole of the nucleus, as a result of absence of nuclear rotation ; lack of a cytoplasmic canal during differentiation of the spermatids into spermatozoa; the base of the basal body is not traversed by the basal plate; a basal foot anchors the basal body to the nucleus; and the presence of numerous vesicles around the midpiece and base of the flagellum. In addition, spermiogenesis includes some common features such as： chromatin compaction; formation of a medial shallow nuclear fossa; and elimination of excess cytoplasm. The mature spermatozoon has an elongate conical-shaped head with no acrosome or acrosomal vesicle, a long midpiece with numerous vesicles that continue backwards around the base of the flagellum and a long tail or flagellum, which has no lateral fins or a membranous compartment. The mitochondria lie close to the nucleus basal pole and surround the initial segment of the axoneme and are separated from the flagellum by the inner mitochondrial envelope due to disappearance of the cytoplasmic canal. The flagellum has the classical axoneme structure of a 9 ＋ 2 microtubular pattern. On the basis of the peculiar features mentioned above, it is concluded that spermiogenesis in this Nile catfish is a synapomorphic type derived from types Ⅰ and Ⅱ spermiogenesis, which are common among teleosts. Accordingly, this type could be considered as a novel type of spermiogenesis and could be termed as ＂type Ⅲ＂.
基金supported by the National Natural Science Foundation of China (Nos.41806127 and 41906111)the Natural Science Foundation of Guangdong Province (No.2018A030313956)。
文摘The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 genes were encoded on the heavy strand, while 9 genes were transcribed on the light strand. The non-coding regions of A. dispar included a control region, a light strand replication and another 11 intergenic spacers. The CR of A. dispar contained 8 conserved sequence blocks(CSBs), a termination-associated sequence(TAS) and a pyrimidine tract. Phylogenetic analysis based on 12 PCGs revealed that A. dispar was genetically closest to Arius arius. The families Schilbeidae, Claroteidae, Mochokidae, and Ariidae formed a closely evolved clade. Molecular information from this research introduces mitogenomice data of A. dispar and suggests the phylogenetic relationships among Siluriformes.
基金supported partially by grant-in-aid(Ref.No.EMR/2017/000718)and(Ref.No.CRG/2022/000540)from the Science and Engineering Research Board,India to BSAuthors acknowledge BUILDER Grant from DBT,India(Ref.No.BUILDER-DBT-BT/INF/22/SP41176/2020)India to School of Life Sciences,University of Hyderabad.
文摘Occurrence of neurotoxic chemicals in the aquatic environment is on the rise posing a potential threat to aquatic biota including fish.In teleosts,zebrafish has become a popular model organism for toxicological studies and testing strategies.However,over the decade,siluriformes(catfish)are also finding ever increasing application being robust as well as their adaptability to adverse ecological conditions,surgical interventions,and tolerant models for toxicity studies and manipulations.Such information can infer potential effects occurring to other species exposed to neurotoxins in their aquatic environment and predicting potential risks of a chemical for the aquatic ecosystem.The aim of this review is to compare and interpret recent results published concerning neuro-behavioral and morphological disturbances caused by toxicants/pollutants providing a holistic view of potential neurotoxic outcomes in catfish.Overall,this review summarizes various effects of toxicants/pollutants in terms of neurotoxicity and neurodegeneration associated with behavioral phenotypes.
