Numerical and structural chromosome polimorphism in fish species: Carassius auratus gibelio b. and alburnus alburnus L.

Abstract

The paper presents the results of cytogenetic investigations of the fish species Carassius auratus gibelio, B. and Alburnus alburnus, L. Karyotype definitions are given for fish caught at different localities in Serbia. Within the bisexual population of the silver carp Carassius auratus gibelio B., we observed variability in the number of the last, smallest akrocentrics (2n=100_ 22-4). These variating accessory chromosomes were called Banalogues. We established the number of chromosomes (3n=150+8 and 3n=150+10) and gave the karyotype characteristics for gynogenetic lines of triploid females. We pointed out that the existing clones differ in the number of chromosomes, i.e. in the number of Banalogues, which are also probably the cause of the occurence of - gynogenetic karyoclones. In the species Alburnus alburnus, L., we established the existence of modified karyotipes with a large metacentric - Robertson's fusion, translocation probably formed by the two biggest akrocentrics. We examined the possibility of maintaining variability in populations of this specie. The results are discussed in comparison to disorders which result from these changes in reproduction, and the possible consequences that can be expected in the offispring.

Prikazani su rezultati citogenetičkih istraživanja riba vrste Carassius auratus gibelio B. i vrste Alburnus alburnus L. Definisan je kariotip riba koje su uhvaćene na različitim lokalitetima vodâ u Srbiji. U okviru biseksualne populacije srebrnog karaša Carasius auratus gibelio B., uočena je varijabilnost u broju poslednjih, najsitnijih akrocentrika (2n= 100±2-4). Ovi varirajući akcesorni hromozomi nazvani su B-analozima. Ustanovljen je broj hromozoma (3n=150+8 i 3n=150+10) i date su karakteristike kariotipa kod ginogenetskih linija triploidnih ženki. Ukazano je na to da se postojeći klonovi razlikuju u broju hromozoma, tj. u broju B-analoga, koji su, verovatno, i uzrok nastanka – ginogenetskih karioklonova. Kod vrste Alburnus alburnus L. (uklije), ustanovljeno je da postoje izmenjeni kariotipovi sa velikim metacentrikom – Robertsonovom fuzijom, translokacijom, koju, verovatno, čine dva najveća akrocentrika. Razmatrana je mogućnost održanja varijabilnosti u populacijama ove vrste. Rezultati su diskutovani u odnosu na poremećaje do kojih ove promene dovode u reprodukciji i moguće posledice koje mogu da se očekuju u potomstvu.