[Karyological study on persian gulf banana shrimp, Penaeus [Fenneropenaeus] merguiensis]

ABSTRACT

Because of limits in applicable karyological techniques and also the presence of a large number of small chromosomes in Penaidae family, the study on the number, structure, and the formula of the chromosomes in these shrimps in difficult. The present cytogenetic study was conducted on Penaeus [Fenneropenaeus] merguiensis native to Persian Gulf and Oman Sea by preparing spreads from various early stages of this species including embryos, nauplii, protozoa, myses, postlarvae as well as adult tissues such as gill, hepatopancreas, testis and ovary. For this purpose, two methods of splashing of cell suspension and squashing of tissues on warm and cold slides were used. Different doses of colchicines and incubation periods on obtaining and the quality of chromosomes were examined as well. It was only possible to obtain acceptable quality metaphase chromosomes using adult testis. The testicular tissue contained both mitotic and meiotic cells, so diploid and haploid chromosome numbers could be counted, respectively. The modal diploid number of this species was found to be 2n=88 which was confirmed by the modal haploid chromosome number of n=44 in the adult testes. Tentative karyotype of Penaeus [Fenneropenaeus] merguiensis contained 21 pairs of meta- and submetacentric chromosomes and 23 pairs of acro- and telocentric chromosomes. The chromosome arm number was calculated NF=130