Latest Articles from Comparative Cytogenetics Latest 7 Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Fri, 29 Mar 2024 01:34:16 +0200 Pensoft FeedCreator https://compcytogen.pensoft.net/i/logo.jpg Latest Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Differentiation of the frog sculpin Myoxocephalus stelleri Tilesius, 1811 (Actinopterygii, Cottidae) based on mtDNA and karyotype analyses https://compcytogen.pensoft.net/article/63207/ Comparative Cytogenetics 15(2): 179-197

DOI: 10.3897/CompCytogen.v15.i2.63207

Authors: Irina N. Moreva, Olga A. Radchenko, Anna V. Petrovskaya

Abstract: A molecular genetic and karyological study of the frog sculpin Myoxocephalus stelleri Tilesius, 1811 was carried out on an extensive sample from a large area of the species’ range. A total of 42 specimens was sampled from the Sea of Japan, Sea of Okhotsk, and coastal waters off the southern Kuril Islands, which makes this sampling scheme the most comprehensive to date. The level of mtDNA polymorphism was found to be low. The haplotypes of the species formed three phylogenetic groups. The unique M. stelleri haplotype from the coast of Shikotan Island linked all the studied groups, indicating that it is likely ancestral. Robertsonian polymorphism was identified in the species. In all five cytotypes (I – 2n = 44, II – 2n = 43, III – 2n = 42, IV – 2n = 41, V – 2n = 40; NF = 44+2) were identified, all of which were present in the Sea of Japan. Only one (cytotype I) was found in the Sea of Okhotsk, which is probably the closest to the ancestral karyotype. The significant chromosomal polymorphism and the presence of common haplotypes in the studied samples indicate their recent origin from a common ancestor and/or relatively recent contacts within the range. The discrepancies between mtDNA and karyotypes in assigning the ancestral M. stelleri to the coastal waters off Shikotan Island (southern Kuril Islands) and the Sea of Okhotsk, respectively, can be explained by the different inheritance mechanisms and the rates of evolution of molecular genetic and karyological traits.

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Research Article Mon, 14 Jun 2021 13:38:10 +0300
Cytogenetic characterization, rDNA mapping and quantification of the nuclear DNA content in Seriolella violacea Guichenot, 1848 (Perciformes, Centrolophidae) https://compcytogen.pensoft.net/article/53087/ Comparative Cytogenetics 14(3): 319-328

DOI: 10.3897/CompCytogen.v14i3.53087

Authors: Cristian Araya-Jaime, Claudio Palma-Rojas, Elisabeth Von Brand, Alfonso Silva

Abstract: Seriolella violacea Guichenot, 1848 is an important component of the fish fauna of the Chilean coast and is of great economic interest. Cytogenetic information for the family Centrolophidae is lacking and the genomic size of five of the twenty-eight species described for this family are is barely known. This study aimed to describe for the first time the karyotype structure via classical and molecular cytogenetics analysis with the goal of identifying the constitutive heterochromatin distribution, chromosome organization of rDNA sequences and quantification of nuclear DNA content. The karyotype of S. violacea is composed of 48 chromosomes, with the presence of conspicuous blocks of heterochromatin on chromosomal pairs one and two. FISH assay with a 5S rDNA probe, revealed the presence of fluorescent markings on the heterochromatic block of pair one. The 18S rDNA sites are located exclusively on pair two, characterizing this pair as the carrier of the NOR. Finally, the genomic size of S. violacea was estimated at 0.59 pg of DNA as C-value. This work represents the first effort to document the karyotype structure and physical organization of the rDNA sequences in the Seriolella genome, contributing with new information to improve our understanding of chromosomal evolution and genomic organization in marine perciforms.

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Research Article Tue, 14 Jul 2020 12:20:33 +0300
Differential hypomethylation of the repetitive Tol2/Alu-rich sequences in the genome of Bodianus species (Labriformes, Labridae) https://compcytogen.pensoft.net/article/21830/ Comparative Cytogenetics 12(2): 145-162

DOI: 10.3897/CompCytogen.v12i2.21830

Authors: Clóvis C. Motta-Neto, André Marques, Gideão W.W.F. Costa, Marcelo B. Cioffi, Luiz A.C. Bertollo, Rodrigo X. Soares, Kátia C. Scortecci, Roberto F. Artoni, Wagner F. Molina

Abstract: Representatives of the order Labriformes show karyotypes of extreme conservatism together with others with high chromosomal diversification. However, the cytological characterization of epigenetic modifications remains unknown for the majority of the species. In the family Labridae, the most abundant fishes on tropical reefs, the genomes of the genus Bodianus Bloch, 1790 have been characterized by the occurrence of a peculiar chromosomal region, here denominated BOD. This region is exceptionally decondensed, heterochromatic, argentophilic, GC-neutral and, in contrast to classical secondary constrictions, shows no signals of hybridization with 18S rDNA probes. In order to characterize the BOD region, the methylation pattern, the distribution of Alu and Tol2 retrotransposons and of 18S and 5S rDNA sites, respectively, were analyzed by Fluorescence In Situ Hybridization (FISH) on metaphase chromosomes of two Bodianus species, B. insularis Gomon & Lubbock, 1980 and B. pulchellus (Poey, 1860). Immunolocalization of the 5-methylcytosine revealed hypermethylated chromosomal regions, dispersed along the entire length of the chromosomes of both species, while the BOD regions exhibited a hypomethylated pattern. Hypomethylation of the BOD region is associated with the precise co-location of Tol2 and Alu elements, suggesting their active participation in the regulatory epigenetic process. This evidence underscores a probable differential methylation action during the cell cycle, as well as the role of Tol2/Alu elements in functional processes of fish genomes.

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Research Article Wed, 28 Mar 2018 09:07:19 +0300
The Mugil curema species complex (Pisces, Mugilidae): a new karyotype for the Pacific white mullet mitochondrial lineage https://compcytogen.pensoft.net/article/11579/ Comparative Cytogenetics 11(2): 225-237

DOI: 10.3897/CompCytogen.v11i2.11579

Authors: Mauro Nirchio, Claudio Oliveira, Zoila R. Siccha-Ramirez, Viviani F. de Sene, Luciana Sola, Valentina Milana, Anna Rita Rossi

Abstract: Recent molecular phylogenetic analyses have shown that the Mugil curema Valenciennes, 1836 species complex includes M. incilis Hancock, 1830, M. thoburni (Jordan & Starks, 1896) and at least four “M. curema” mitochondrial lineages, considered as cryptic species. The cytogenetic data on some representatives of the species complex have shown a high cytogenetic diversity. This research reports the results of cytogenetic and molecular analyses of white mullet collected in Ecuador. The analyzed specimens were molecularly assigned to the Mugil sp. O, the putative cryptic species present in the Pacific Ocean and showed a 2n = 46 karyotype, which is composed of 2 metacentric and 44 subtelocentric/acrocentric chromosomes. This karyotype is different from the one described for M. incilis (2n = 48) and from those of the two western Atlantic lineages Mugil curema (2n = 28), and Mugil margaritae (2n = 24). Data suggest the need for a morphological analysis to assign a species name to this Pacific lineage.

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Research Article Fri, 7 Apr 2017 11:25:44 +0300
Co-located 18S/5S rDNA arrays: an ancient and unusual chromosomal trait in Julidini species (Labridae, Perciformes) https://compcytogen.pensoft.net/article/10227/ Comparative Cytogenetics 10(4): 555-570

DOI: 10.3897/CompCytogen.v10i4.10227

Authors: Karlla Danielle Jorge Amorim, Marcelo de Bello Cioffi, Luiz Antônio Carlos Bertollo, Rodrigo Xavier Soares, Allyson Santos Souza, Gideão Wagner Werneck Félix da Costa, Wagner Franco Molina

Abstract: Wrasses (Labridae) are extremely diversified marine fishes, whose species exhibit complex interactions with the reef environment. They are widely distributed in the Indian, Pacific and Atlantic oceans. Their species have displayed a number of karyotypic divergent processes, including chromosomal regions with complex structural organization. Current cytogenetic information for this family is phylogenetically and geographically limited and mainly based on conventional cytogenetic techniques. Here, the distribution patterns of heterochromatin, GC-specific chromosome regions and Ag-NORs, and the organization of 18S and 5S rDNA sites of the Atlantic species Thalassoma noronhanum (Boulenger, 1890), Halichoeres poeyi (Steindachner, 1867), Halichoeres radiatus (Linnaeus, 1758), Halichoeres brasiliensis (Bloch, 1791) and Halichoeres penrosei Starks, 1913, belonging to the tribe Julidini were analyzed. All the species exhibited 2n=48 chromosomes with variation in the number of chromosome arms among genera. T. noronhanum has 2m+46a, while species of the genus Halichoeres Rüppell, 1835 share karyotypes with 48 acrocentric chromosomes. The Halichoeres species exhibit differences in the heterochromatin distribution patterns and in the number and distribution of 18S and 5S rDNA sites. The occurrence of 18S/5S rDNA syntenic arrangements in all the species indicates a functionally stable and adaptive genomic organization. The phylogenetic sharing of this rDNA organization highlights a marked and unusual chromosomal singularity inside the family Labridae.

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Research Article Fri, 4 Nov 2016 11:39:50 +0200
Discriminatory profile of rDNA sites and trend for acrocentric chromosome formation in the genus Trachinotus Lacépède, 1801 (Perciformes, Carangidae) https://compcytogen.pensoft.net/article/1775/ Comparative Cytogenetics 6(4): 359-369

DOI: 10.3897/compcytogen.v6i4.3062

Authors: Uedson Jacobina, Marcelo Vicari, Luiz Bertollo, Wagner Molina

Abstract: Chromosomal traits have provided valuable information for phylogeny and taxonomy of several fish groups. Three Atlantic Carangidae species of the genus Trachinotus Lacépède, 1801 (T. goodei Jordan et Evermann, 1896, T. carolinus (Linnaeus, 1766) and T. falcatus (Linnaeus, 1758)) were investigated,2n=48 chromosomes but different chromosomal arms (FN number), i.e., 52, 56 and 58, respectively, in view of the different number of two-armed chromosomes found in their karyotypes. Thus, T. goodei, T. carolinus and T. falcatus present a progressive distance from the probable basal karyotype proposed for Perciformes (2n=48 acrocentrics, FN=48). At first sight, these findings do not agree with the phylogenetic hypothesis based on mitochondrial sequences, where T. goodei appear as the most derived species, followed by T. falcatus and T. carolinus, respectively. However, the chromosomal mapping of ribosomal DNAs was informative for clarifying this apparent conflict. Indeed, the multiple 5S and 18S rDNA sites found in T. goodei corroborate the most derived condition for this species. In this sense, the occurrence of the unexpected number of two-armed chromosomes and FN value for this species, as well as for T. carolinus, must be due to additional rounds of acrocentric formation in these species, modifying the macrostructure of their karyotypes.

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Research Article Wed, 31 Oct 2012 00:00:00 +0200
Cytogenetic characterization of three Balistoidea fish species from the Atlantic with inferences on chromosomal evolution in the families Monacanthidae and Balistidae https://compcytogen.pensoft.net/article/1713/ Comparative Cytogenetics 5(1): 61-69

DOI: 10.3897/compcytogen.v5i1.1141

Authors: Lorena Lima, Pablo Martinez, Wagner Molina

Abstract: The Tetraodontiformes are the most derived group of teleostean fish. Among other apomorphies, they are characterized by a high degree of fusions or significant bone loss in the head and body. In the early phylogenetic proposals presented for this order, the families Balistidae and Monacanthidae have been unanimously considered to be closely related. Although they have moderate species diversity, they are scarcely known in cytogenetic aspect and chromosomal pattern comparisons between these groups have yet to be established. The species Cantherhines macrocerus (Hollard,1853), C. pullus (Ranzani, 1842) (Monacanthidae) and Melichthys niger (Bloch, 1786) (Balistidae) were cytogenetically analyzed using conventional (Ag-impregnation, C-banding, CMA3- and DAPI-fluorescence) and molecular (FISH with an 18S rDNA probe) cytogenetic protocols. The karyotypes of all three species were very similar possessing diploid chromosome numbers 2n = 40 and composed exclusively of acrocentric chromosomes. Single NOR-bearing pair as well as positive heterochromatic blocks at pericentromeric regions were identified in the karyotypes of the three species studied. NOR-bearing sites were positively labeled after Ag-impregnation, C-banding, CMA3-fluorescence and FISH with an 18S rDNA probe but were negative after DAPI-fluorescence. Such remarkable shared conspicuous chromosomal characters corroborate either close phylogenetic relationship of these families, previously established by morphological and molecular data, or rather conservative nature of karyotype differentiation processes. The later hypothesis, however, appears less probable due to centric or in tandem fusions documented for another Balistoidea species.

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Research Article Thu, 5 May 2011 00:00:00 +0300