اسم المؤلف:
اسماء سامي ابراهيم
اسم المشرف:
ندى عبد المجيد الانصاري | طه ياسين الدوري
المستخلص:
هدفت الدراسة الحالية التعرف على الطراز الكروموسومي ونظام تحديد الجنس والتمييز بين الجنسين مظهريا في ثلاثة انواع من اسماك المياه العذبة العراقية ممثلة بسمكة الحمري Barbus luteus والبنيني كبير الفم macrostomus Cyprinionوالبلعوط الملوكي Chondrostoma regius | These present studies were carried out to determine the karyotypes & the system of sex determination between the two sexes as well as the sexual morphological characteristics of three species of Iraqi fresh water fish Barbus luteus, Cyprinion macrostomus, & Chondrostoma regius that were fished from Tigris river at Baghdad during 2005. The cytogenetic studies revealed that the chromosome number of Barbus luteus is 2n = 148 & the karyotype of males is (80m + 52sm + 16st) while the females has (80m + 51sm + 17st). The chromosome number of Cyprinion macrostomus is 2n = 50 the males has (6m + 24sm + 12st + 8t) while the females has (6m + 23sm + 13st + 8t). The chromosome number of Chondrostoma regius is 2n = 48 and the karyotype is (14m + 30sm + 4st). Sex chromosomes were identified in Barbus luteus & in Cypinion macrostomus for the first time , the sex is determined by ZZ / ZW system, the female was considered as heterogametic (ZW) while the male was considered as homogametic (ZZ) , & the chromosome Z was represented as submetacentric chromosome & chromosome W as small subtelocentric chromosome. In spite of the difference in their chromosome number , the ratio between red blood cell diameter & it's nucleus was approximated in these species. The differences among these species in both of the diameter of cell and the nucleus didn't match with the differences at the polyploidy levels or with the difference in chromosome number within the same level. The liver & intestine were recommended as new sources for chromosomal studies , because of the good ratio of dividing cells (71.4 % & 58.2 %) respectively from the whole dividing cells in kidney that was considered as a control. The crude aqueous extract of fresh convolvulus arvensis leaves showed good effect in arresting the cell division of fish at metaphase , the concentration (0.4, 0.6, 0.8, ) mg / gm arrested kidney cells of carp fish at the metaphase in ratios 71.1 % , 88.1 % , 94 % respectively from the colchicines treated kidney cells (control). Positive significance correlation was found (r = 0.9518) between the percentages of arrested cells at metaphase & the concentrations of crude extract. Comparison between the females and males of the three species revealed that in Barbus luteus the distance from head edge to the anal orifice & from head edge to the dorsal fin were larger in males than females. The females have dark colored fins with reddish ventral aspect of head & body in comparison with the males during the whole months of study. So , they were considered as permanently sexual dimorphism characteristics. But , during the spawning seasons (May & June ) a more brighting color of male with reddish coloration of both sides of body were noticed in comparison with female with a golden orange corneal coloration in both sexes. Thus, they were considered as temporary sexual dimorphism characteristics. In Cyprinion macrostomus the distance from the head edge to the anal orifice was larger in females than males. The colors of anal & caudal fins were darker in females than in males during the whole monthes of study.So , they were considered as perminantly sexual dimorphism characteristics. While, during the spawning seasons ( May , June , July & August) , the gill operculum was of orange color only in male that extend to the end of pectoral fin. So , this was considered as a temporary sexual dimorphism characteristic. In Chondrostoma regius the distance from the head edge to the dorsal fin & from the dorsal to caudal fin as well as the pectoral fin base length were larger in females than in males during the whole months of study it was considered that they are permanently sexual dimorphism characteristics. Differential characteristics were not noticed during the spawning season (February & March). The permanently sexual dimorphism & the general characteristics were not affected by the differences of standard length , weight , age & season , because they were observed in fishes of different lengths , weights & ages & during the months of study 2005. But , the seasons affect the development of temporary characteristics in Barbus luteus & Cyprinion macrostomus , because these characteristics were observed during the spawning season only. Aging of Barbus luteus was accompanied by growth increase as indicated by the mean of standard length during May , July, August, September & December & by the mean of weight during May , August, September, October & December. A positive correlation was found between standard length & weight during the months of study , with the exception of January. While aging of Cyprinion macrostomus & Chondrostoma regius was not accompanied by growth increase as indicated by the means of standard length & weight , but a positive correlation between standard length & weight was found during the studied months. Same growth type were observed in the three species of fish , it was allometric in two sexes.
