Sculpins of the Cottidae family, being permanent inhabitants of the waters of Peter the Great Bay, Sea of Japan, play one of the leading roles in the bottom ichthyocoenes by their biomass and number [1,3,7]. The central position in this family belongs to a large group of sculpins of the Myoxocephalinae subfamily, which includes the snow sculpin Myoxocephalus brandti. Only morphological methods have heretofore been applied for study of major problems on the trends, mechanisms, and rates of evolution of species of that subfamily. Analysis of the features of the anatomy and outer morphology, including the seismosensory system, has enabled tracking of vectors of the morphological transformations in the evolution of species of the given subfamily and tracking of the pattern of their probable phylogenetic relations [6]. In particular, the species M. stelleri, M. polyacanthocephalus, and M. jaok and the slightly deviated, rather young species M. brandti have been referred to the phylogenicly more ancient group of species within the Myoxocephalinae subfamily. These species have not been studied karyologicaly, except for the Far Eastern sculpin M. stelleri (see [5]) and the European sculpin M. scorpius [2]. Analysis of the karyotypes of Myoxocephalinae species will enable tracking the direction of the karyological variations during their evolution and specification of the kin and phylogenetic relations within the given subfamily. The objective of the present work is to describe the karyotype of the snow sculpin M. brandti from Peter the Great Bay and to compare it with the karyotype of M. stelleri to reveal their similarities and distinctions. MATERIAL AND METHODSThe fishes were caught by set-net or gill-net in the east part of Amur Bay, in the vicinity of the Chaika and Sedanka railway stations. The species were determined by the morphological attributes described in Lindberg and Krasyukova's key [4].Preparations made by the method of air drying from a suspension of cells of the head kidney [8] served as work material. Right after catching, the fishes were administered a 0.5% colchicine solution (1 ml per kg of body weight) and kept in a well-aerated aquarium for 3-4 h. Then, the fishes were killed and the cell suspension was prepared with a syringe from small pieces of the head kidney in a 0.5% solution of potassium chloride. After settling of large pieces of the tissue, the suspension was transferred in centrifuge test tubes and kept at room temperature for 20-25 minutes for hypotonic treatment of cells. The cells were pelleted for 5 min at 1000 rev/min. The supernatant was poured out, and precipitate was fixed without breaking by a fresh, cooled mix of ethanol and glacial acetic acid (3 : 1) for 45 minutes, replacing the fixative every 15 minutes. In the final portion of the fixative, the precipitate was broken and the obtained suspension was set by drops on a cooled, wet slide. The slides were dried on a surface warmed up to 60 ° C or above a spirit-lamp. The chromosomes on trial preparations were stained with a 4% s...

Considerable differences in karyotypes of Tribolodon hakonensis from Primorye and the rivers of the Sea of Okhotsk drainage were demonstrated. These differences raise doubts that these fishes belong to one species and point to the necessity of more precise definition of the species status of the southern form of T. hakonensis. The karyological evidence is consistent with the data of mtDNA PCR RFLP analysis on genetic independence of the southern and the northern forms of T. hakonensis. In the northern form of T. hakonensis, variation of the chromosomal arm number was revealed. Specifically, the number of chromo somes was constant (2n = 50), whereas the number of chromosomal arms (NF) constituted 88, 92, and 94, which suggests genetic heterogeneity of the northern form. PCR RFLP analysis of mtDNA showed that hap lotypes of northern T. hakonensis split into two groups with 100% support. Based on comparative phyloge netic and karyological analyses of the Tribolodon species, independent divergence of the southern and the northern forms of T. hakonensis was suggested.

No abstract

No abstract