Noleto Rafael Bueno, Vicari Marcelo Ricardo, Cipriano Roger Raupp, Artoni Roberto Ferreira, Cestari Marta Margarete
Departamento de Genética, Centro Politécnico, Universidade Federal do Paraná, Caixa Postal 19071, 81531-990, Curitiba, PR, Brazil.
Genetica. 2007 Jun;130(2):133-8. doi: 10.1007/s10709-006-9000-1. Epub 2006 Aug 4.
Chromosomal features, location and variation of the major and minor rDNA genes cluster were studied in three pufferfish species: Sphoeroides greeleyi and Sphoeroides testudineus (Tetraodontidae) and Cyclichthys spinosus (Diodontidae). The location of the major rDNA was revealed with an 18S probe in two loci for all species. The minor rDNA loci (5S rDNA) was found in one chromosome pair in tetraodontid fishes and four sites located on two distinct chromosomal pairs in C. spinosus. A syntenical organization was not observed among the ribosomal genes. Signal homogeneity for GC/AT-DNA specific fluorochromes was observed in diodontid fish except in the NORs regions, which were CMA3-positive. Giemsa karyotypes of tetraodontid species presents 2n=46, having the same diploid value of other Sphoeroides species that have been investigated. On the other hand, the karyotype of C. spinosus, described for the first time, shows 2n=50 chromosomes (4m+18sm+12st+16a). The foreknowledge of the karyotypic structure of this group and also the physical mapping of certain genes could be very helpful for further DNA sequence analysis.
对三种河豚进行了研究，包括格氏圆鲀和龟圆鲀（四齿鲀科）以及棘圆鲀（二齿鲀科），分析了其主要和次要核糖体DNA基因簇的染色体特征、位置及变异情况。所有物种的主要核糖体DNA在两个位点通过18S探针得以揭示。在四齿鲀科鱼类中，次要核糖体DNA位点（5S核糖体DNA）位于一对染色体上，而在棘圆鲀中，该位点位于两个不同染色体对的四个位点上。核糖体基因之间未观察到同线性组织。除了核仁组织区（NORs）呈CMA3阳性外，在二齿鲀科鱼类中观察到了针对GC/AT - DNA特异性荧光染料的信号均匀性。四齿鲀科物种的吉姆萨核型显示2n = 46，与已研究的其他圆鲀属物种具有相同的二倍体值。另一方面，首次描述的棘圆鲀核型显示有2n = 50条染色体（4条中着丝粒染色体 + 18条亚中着丝粒染色体 + 12条近端着丝粒染色体 + 16条端着丝粒染色体）。该类群核型结构的先验知识以及某些基因的物理图谱对于进一步的DNA序列分析可能非常有帮助。
