Studies on chromosome karyotype,Ag-NORs and C-banding patterns of Lutjanus sebae

Studies on karyotype,Ag-NORs,and C-banding of Lutjanus sebae were performed.The chromosomes were re-ceived from the head kidney by using a method of injecting with PHA and colchicines,air drying,and Giemsa staining.The results were as follows.1) The karyotypic formula of L.sebae was 2n=48t,NF=48.Meanwhile,a pair of chromosomes,with secondary constriction near the centromere,was found on chromosome 1.2) The Ag-NORs polymorphisms were individually specific in this fish.The silver staining pots were 1-4,and the number of Ag-NORs was mainly 2(79%).A pair of nucleolar organizer regions was observed on the secondary constriction of chromosome 1,and no Ag-NORs combination was found.3) Centromeres of most chromosomes were C-bandings positive,and heterochromatin was detected at the satellite zone of chro-mosome 1.Thus,we discussed the evolution of karyotype,the developing mechanism of Ag-NORs,and C-bandings for fish.The phylogenetic condition of L.sebae was evaluated as well.