Nirchio Mauro, Ehemann Nicolás, Siccha-Ramirez Raquel, Ron Ernesto, Pérez Julio Eduardo, Rossi Anna Rita, Oliveira Claudio
Rev Biol Trop. 2014 Dec;62(4):1365-73. doi: 10.15517/rbt.v62i4.13029.
The genus Pterois includes nine valid species, native to the Red Sea and Indian Ocean throughout the Western Pacific. P. volitans and P. miles are native to the Indo-Pacific, and were introduced into Florida waters as a result of aquarium releases, and have been recently recognized as invaders of the Western Atlantic and Caribbean Sea (Costa Rica to Venezuela). Thus far, cytogenetic studies of the genus Pterois only cover basic aspects of three species, including P. volitans from Indo-Pacific Ocean. Considering the lack of more detailed information about cytogenetic characteristics of this invasive species, the objective of the present study was to investigate the basic and molecular cytogenetic characteristics of P. volitans in Venezuela, and compare the results with those from the original distribution area. For this, the karyotypic characteristics of four lionfish caught in Margarita Island, Venezuela, were investigated by examining metaphase chromosomes by Giemsa staining, C-banding, Ag-NOR, and two-colour-Fluorescent in situ hybridization (FISH) for mapping of 18S and 5S ribosomal genes. Comparing the sequences of the 16S gene of the specimens analyzed, with sequences already included in the Genbank, we corroborated that our specimens identified as P. volitans are in fact this species, and hence exclude the possibility of a misidentification of P. miles. The diploid number was 2n = 48 (2m + 10sm + 36a) with FN = 60. Chromosomes uniformly decreased in size, making it difficult to clearly identify the homologues except for the only metacentric pair, and the pairs number two, the largest of the submetacentric series. C-banding revealed only three pairs of chromosomes negative for C-band, whereas all remaining chromosomes presented telomeric and some interstitial C-positive blocks. Only two chromosomes were C-banding positive at the pericentromeric regions. Sequential staining revealed Ag-NOR on the tips of the short arms of chromosome pair number two and the FISH assay revealed that 18S rDNA and 5S rDNA genes are co-located on this chromosome pair. The co-localization of 5S rDNA and 45S rDNA is discussed. Both constitutive heterochromatin and NOR location detected in samples examined in this study, differ from those reported for P. volitans in previous analysis of specimens collected in Indian Ocean (Java), suggesting the occurrence of chromosome microrearrangements involving heterochromatin during the spread of P. volitans.
蓑鲉属包括9个有效物种，原产于红海、印度洋直至西太平洋。翱翔蓑鲉和勒氏蓑鲉原产于印度-太平洋地区，因水族箱放生而被引入佛罗里达海域，最近被认定为西大西洋和加勒比海（从哥斯达黎加到委内瑞拉）的入侵物种。迄今为止，蓑鲉属的细胞遗传学研究仅涵盖了3个物种的基本方面，包括来自印度-太平洋地区的翱翔蓑鲉。鉴于缺乏关于这种入侵物种细胞遗传学特征的更详细信息，本研究的目的是调查委内瑞拉翱翔蓑鲉的基本和分子细胞遗传学特征，并将结果与原产分布区的结果进行比较。为此，通过吉姆萨染色、C带、银染核仁组织区（Ag-NOR）以及用于18S和5S核糖体基因定位的双色荧光原位杂交（FISH）来检查中期染色体，从而研究在委内瑞拉玛格丽塔岛捕获的4条狮子鱼的核型特征。将分析标本的16S基因序列与Genbank中已有的序列进行比较，我们证实我们鉴定为翱翔蓑鲉的标本确实是该物种，因此排除了误鉴定为勒氏蓑鲉的可能性。二倍体数为2n = 48（2m + 10sm + 36a），臂数为60。染色体大小均匀递减，除了唯一的中着丝粒对以及亚中着丝粒系列中最大的第二对染色体外，难以清晰识别同源染色体。C带显示只有三对染色体C带阴性，而其余所有染色体均呈现端粒和一些居间的C带阳性块。只有两条染色体在着丝粒周围区域C带阳性。连续染色显示银染核仁组织区位于第二对染色体短臂的末端，荧光原位杂交分析显示18S rDNA和5S rDNA基因共定位于这对染色体上。讨论了5S rDNA和45S rDNA的共定位情况。本研究检测到的组成型异染色质和核仁组织区位置与之前对在印度洋（爪哇）采集的标本进行分析时报道的翱翔蓑鲉不同，这表明在翱翔蓑鲉扩散过程中发生了涉及异染色质的染色体微重排。
