A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, the...A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, their prevalences, and mean intensities. Collected parasites were identified as, Isopoda (praniza larva of Gnathia sp.), Copepoda (Hatschekia sp.) Monogenea (Diplectanum sp.) and Digenea (Lecithoclaster and Bucephalus spp). Out of 30 specimens of fish caught from Jeddah coast 13 (43.4%) were infested by 90 parasites comprising of two parasite species, praniza larva and Hatschekia sp., with prevalence of infestation 40% and 3.33%, and mean intensity 7 and 6 parasites per fish respectively. 19 (63.3%) of Scarus fish caught from Rabigh coast were infested by 205 parasites representing 4 parasite spp. Diplectanum sp. represents the most commonly encountered parasite with prevalence (53.3%) and mean intensity (10.94%), followed by (Lecithoclaster sp. then praniza larva, prevalances (16.66% and 13.3%) and mean inentisities (3.4. and 1.75) respectively. Bucephalus sp. showed the minor, prevalence (3.33%) and mean intensity (6). Generally Scarus fish species from Rabigh had higher prevalence and mean intensity (63.3% and 7.59%) than Scarus fish species from Jeddah (43.4% and 6.92%). Female fish from Jeddah showed no parasitic infestation, while males were infested (prevalence 65% and mean intensity 6.92). Female fish from Rabigh had higher prevalence (84.21) and lower intensity (6.43) than males which showed prevalence (27.27%) and intensity (19). Relationship between parasitic infestation and fish species and sex were also studied in the two different localities and discussed.展开更多
As lower vertebrates, fishes have complex modes of sex determination. From the cytogenetic perspective, only a small proportion of fish species have heteromorphic sex chromosomes. At the present stage sex determinatio...As lower vertebrates, fishes have complex modes of sex determination. From the cytogenetic perspective, only a small proportion of fish species have heteromorphic sex chromosomes. At the present stage sex determination can only be explained via "genetics" rather than "genes" in most species. Nevertheless, genes associated with sex determination and male development were identified in a model fish medaka, Oryzias latipes. Sequences or genetic markers specific to certain sex chromosomes were reported in some fishes. These findings lay the groundwork for further studies on the function and regulation of sex genes aiming at elucidation of the mechanism of sex determination, and provide potential tool for sexing fish. In this minireview, progress in the past few decades in both cytogenetic and molecular genetic studies on sex determination of fish were summarized. Prospects, significance and possible future directions of the studies on fish sex determination were also discussed.展开更多
文摘A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, their prevalences, and mean intensities. Collected parasites were identified as, Isopoda (praniza larva of Gnathia sp.), Copepoda (Hatschekia sp.) Monogenea (Diplectanum sp.) and Digenea (Lecithoclaster and Bucephalus spp). Out of 30 specimens of fish caught from Jeddah coast 13 (43.4%) were infested by 90 parasites comprising of two parasite species, praniza larva and Hatschekia sp., with prevalence of infestation 40% and 3.33%, and mean intensity 7 and 6 parasites per fish respectively. 19 (63.3%) of Scarus fish caught from Rabigh coast were infested by 205 parasites representing 4 parasite spp. Diplectanum sp. represents the most commonly encountered parasite with prevalence (53.3%) and mean intensity (10.94%), followed by (Lecithoclaster sp. then praniza larva, prevalances (16.66% and 13.3%) and mean inentisities (3.4. and 1.75) respectively. Bucephalus sp. showed the minor, prevalence (3.33%) and mean intensity (6). Generally Scarus fish species from Rabigh had higher prevalence and mean intensity (63.3% and 7.59%) than Scarus fish species from Jeddah (43.4% and 6.92%). Female fish from Jeddah showed no parasitic infestation, while males were infested (prevalence 65% and mean intensity 6.92). Female fish from Rabigh had higher prevalence (84.21) and lower intensity (6.43) than males which showed prevalence (27.27%) and intensity (19). Relationship between parasitic infestation and fish species and sex were also studied in the two different localities and discussed.
文摘As lower vertebrates, fishes have complex modes of sex determination. From the cytogenetic perspective, only a small proportion of fish species have heteromorphic sex chromosomes. At the present stage sex determination can only be explained via "genetics" rather than "genes" in most species. Nevertheless, genes associated with sex determination and male development were identified in a model fish medaka, Oryzias latipes. Sequences or genetic markers specific to certain sex chromosomes were reported in some fishes. These findings lay the groundwork for further studies on the function and regulation of sex genes aiming at elucidation of the mechanism of sex determination, and provide potential tool for sexing fish. In this minireview, progress in the past few decades in both cytogenetic and molecular genetic studies on sex determination of fish were summarized. Prospects, significance and possible future directions of the studies on fish sex determination were also discussed.
