scholarly journals Karyotype description of three species of Loricariidae (Siluriformes) and occurrence of the ZZ/ZW sexual system in Hemiancistrus spilomma Cardoso & Lucinda, 2003

2006 ◽  
Vol 4 (1) ◽  
pp. 93-97 ◽  
Author(s):  
Renildo Ribeiro de Oliveira ◽  
Issakar Lima Souza ◽  
Paulo Cesar Venere
Keyword(s):  
Chromosome Pair ◽  
Sex Chromosome ◽  
Sexual System ◽  
Freshwater Systems ◽  
Phylogenetic Studies ◽  
Cytogenetic Data ◽  
Sex Chromosome System

The neotropical freshwater systems have a high number of catfish species (Siluriformes), and many of those are denominated "cascudos" in Brazil. Cytogenetic data about three "cascudos" species fished in the rio Araguaia are described in the present study. The Pterygoplichthys joselimaianus showed 2n=52, with 28 metacentrics (M) chromosomes, 16 submetacentrics (SM) and 8 subtelocentrics/acrocentrics (ST/A) in both sexes. Hemiancistrus spinosissimus showed 2n=52, with karyotype formulae 26M+22SM+4ST, in both sexes. Hemiancistrusspilomma also showed 2n=52, but in this species a ZZ/ZW sex chromosome system (25M+21SM+6ST in females and 24M+22SM+6ST in males) was observed. The cells from H. spinosissimus and P. joselimaianus showed one chromosome pair bearing Ag-NORs, while in the H. spilomma three chromosome pairs bearing Ag-NORs were detected. The data showed in this work reveal particular chromosomal characteristics, important for a good recognition of both Hemincistrus species, and also show the importance of the insertion of cytogenetic data on taxonomic phylogenetic studies.

scholarly journals Chromosomal analysis of Centromochlus heckelii (Siluriformes: Auchenipteridae), with a contribution to Centromochlus definition

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Samantha Kowalski ◽  
Leonardo Marcel Paiz ◽  
Maelin da Silva ◽  
Amanda de Souza Machado ◽  
Eliana Feldberg ◽  
...  
Keyword(s):  
River Basin ◽  
Chromosome Pair ◽  
Diploid Number ◽  
Sex Chromosome ◽  
Chromosomal Analysis ◽  
Amazon River Basin ◽  
Terminal Position ◽  
Chromosomal Markers ◽  
Sex Chromosome System ◽  
Acrocentric Chromosomes

ABSTRACT Historically, there are divergences in the species allocation between Centromochlus and Tatia. This study aimed to generate the first cytogenetic data about Centromochlus and, by analyzing a population of Centromochlus heckelii from the Amazon River basin, to contribute as evidence to a historical taxonomic dilemma. Diploid number of 46 chromosomes and a heteromorphic pair was found in the female karyotypes, thus characterizing a ZZ/ZW sex chromosome system. Pale blocks of heterochromatin were located in centromeric regions of some chromosomes; however, the exclusive female chromosome (W) is almost entirely heterochromatic. AgNORs were detected in terminal position on the short arms of one acrocentric pair in males and two chromosome pairs in females, the acrocentric plus the sex chromosome pair. Notable differences between Centromochlus heckelii and previous data about species of Tatia are: lower diploid number, presence of a sex chromosome system and multiple AgNORs in Centromochlus, while species of Tatia have simple AgNORs and the absence of acrocentric chromosomes. Results in this study show that chromosomal markers could contribute as evidence to taxonomic delimitation studies.

scholarly journals Interspecific chromosomal divergences in the genus Characidium (Teleostei: Characiformes: Crenuchidae)

2010 ◽  
Vol 8 (1) ◽  
pp. 77-86 ◽  
Author(s):  
José Carlos Pansonato Alves ◽  
Luiz Ricardo de Souza Paiva ◽  
Claudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Chromosome Pair ◽  
Diploid Number ◽  
Constitutive Heterochromatin ◽  
Sex Chromosome ◽  
Way Of Life ◽  
Geographical Isolation ◽  
Relevant Role ◽  
Sex Chromosome System ◽  
Morphological Differences ◽  
First Time

Karyotypes of seven fish species of the genus Characidium, three of them studied for the first time, were characterized using conventional cytogenetic techniques (Giemsa staining, Ag-NOR, and C-banding). All species presented a diploid number of 2n=50, with only metacentric and submetacentric chromosomes, as observed in all Characidium species studied. In two species cells with one to three B chromosomes were observed. All species analyzed have a single NOR-bearing chromosome pair with morphological differences among them. Characidium cf. zebra shows heterochromatic blocks restricted to the pericentromeric regions of all chromosomes denoting the absence of a sex chromosome system. On the other hand, the species Characidium lanei, C. pterostictum, C. lauroi, C. oiticicai, C. schubarti, and Characidium sp., besides presenting pericentromeric heterochromatic blocks, exhibited large interstitial and/or terminal heterochromatic blocks, and a ZZ/ZW sex chromosome system. The constitutive heterochromatin seems to play a relevant role in the chromosome differentiation process of the studied species, mainly in relation to the sex chromosomes. The geographical isolation of the rivers in which the species were sampled, associated with their way of life restricted to headwaters environments, may have favored the process of fixation of different karyotypes found in each of the analyzed species.

Diversity of Sex Chromosome Systems in Ancistrini (Loricariidae, Hypostominae): ZZ/ZW in Ancistrus taunayi Miranda Ribeiro, 1918

2015 ◽  
Vol 146 (4) ◽  
pp. 306-310 ◽  
Author(s):  
Jocicléia Thums Konerat ◽  
Vanessa Bueno ◽  
Vladimir P. Margarido ◽  
Ana L.B. Portela-Castro ◽  
Isabel C. Martins-Santos
Keyword(s):  
18S Rdna ◽  
Chromosome Pair ◽  
Sex Chromosome ◽  
Acrocentric Chromosome ◽  
5S Rdna ◽  
Paracentric Inversion ◽  
Origin And Evolution ◽  
Agnor Staining ◽  
Rdna Fish ◽  
Sex Chromosome System

The karyotype of the Ancistrini catfish Ancistrus taunayi was analyzed by conventional (Giemsa staining, AgNOR staining and C-banding) and molecular cytogenetic (5S and 18S rDNA-FISH) methods. The diploid chromosome number was 2n = 50 (22 metacentrics + 10 submetacentrics + 10 subtelocentrics + 8 acrocentrics) for both sexes. A single NOR-bearing acrocentric chromosome pair (No. 24) was detected after Ag-staining and 18S rDNA-FISH, while 5S rDNA was found only in the subtelocentric pair No. 21. Conspicuous GC-rich heterochromatin blocks corresponded to the NOR sites and were also observed in the distal regions of the acrocentric chromosome pairs Nos. 22 and 25. Chromosome pair No. 22 differed between males and females; in males, only a small interstitial block of GC-rich heterochromatin was present in both chromosomes, whereas in females, 2 blocks of GC-rich heterochromatin flanked a euchromatic region in one of the homologues, suggesting the occurrence of a ZZ/ZW sex chromosome system. Two mechanisms for the origin and evolution of this simple ZZ/ZW sex chromosome system in A. taunayi are proposed: (1) a paracentric inversion followed by amplification of the proximal heterochromatin and (2) amplification of the interstitial heterochromatin followed by a paracentric inversion. Although ZZ/ZW systems have already been described for other Ancistrus species, our results do not show the same pattern, suggesting an independent origin.

scholarly journals Evolution of a Multiple Sex-Chromosome System by Three-Sequential Translocations among Potential Sex-Chromosomes in the Taiwanese Frog Odorrana swinhoana

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 661
Author(s):  
Ikuo Miura ◽  
Foyez Shams ◽  
Si-Min Lin ◽  
Marcelo de Bello Cioffi ◽  
Thomas Liehr ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Rare Case ◽  
Sex Chromosome ◽  
Sex Chromosome System ◽  
Brown Frog ◽  
Male Specific

Translocation between sex-chromosomes and autosomes generates multiple sex-chromosome systems. It happens unexpectedly, and therefore, the evolutionary meaning is not clear. The current study shows a multiple sex chromosome system comprising three different chromosome pairs in a Taiwanese brown frog (Odorrana swinhoana). The male-specific three translocations created a system of six sex-chromosomes, ♂X1Y1X2Y2X3Y3 -♀X1X1X2X2X3X3. It is unique in that the translocations occurred among three out of the six members of potential sex-determining chromosomes, which are known to be involved in sex-chromosome turnover in frogs, and the two out of three include orthologs of the sex-determining genes in mammals, birds and fishes. This rare case suggests sex-specific, nonrandom translocations and thus provides a new viewpoint for the evolutionary meaning of the multiple sex chromosome system.

scholarly journals Evolutionary transitions between mechanisms of sex determination in vertebrates

2011 ◽  
Vol 7 (3) ◽  
pp. 443-448 ◽  
Author(s):  
Alexander E. Quinn ◽  
Stephen D. Sarre ◽  
Tariq Ezaz ◽  
Jennifer A. Marshall Graves ◽  
Arthur Georges
Keyword(s):  
Sex Determination ◽  
Chromosome Pair ◽  
Sex Chromosome ◽  
Molecular Pathways ◽  
Genetic Contribution ◽  
Temperature Dependent ◽  
Trait Evolution ◽  
Evolutionary Transitions ◽  
Dichotomous Outcome ◽  
Threshold Trait

Sex in many organisms is a dichotomous phenotype—individuals are either male or female. The molecular pathways underlying sex determination are governed by the genetic contribution of parents to the zygote, the environment in which the zygote develops or interaction of the two, depending on the species. Systems in which multiple interacting influences or a continuously varying influence (such as temperature) determines a dichotomous outcome have at least one threshold. We show that when sex is viewed as a threshold trait, evolution in that threshold can permit novel transitions between genotypic and temperature-dependent sex determination (TSD) and remarkably, between male (XX/XY) and female (ZZ/ZW) heterogamety. Transitions are possible without substantive genotypic innovation of novel sex-determining mutations or transpositions, so that the master sex gene and sex chromosome pair can be retained in ZW–XY transitions. We also show that evolution in the threshold can explain all observed patterns in vertebrate TSD, when coupled with evolution in embryonic survivorship limits.

scholarly journals Telomere-to-telomere assembly of a fish Y chromosome reveals the origin of a young sex chromosome pair

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Lingzhan Xue ◽  
Yu Gao ◽  
Meiying Wu ◽  
Tian Tian ◽  
Haiping Fan ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Chromosome Pair ◽  
Sex Chromosome ◽  
Structural Variations ◽  
Recombination Suppression ◽  
Chromosome Differentiation ◽  
Y Chromosomes ◽  
Recent Origin ◽  
Mastacembelus Armatus

Abstract Background The origin of sex chromosomes requires the establishment of recombination suppression between the proto-sex chromosomes. In many fish species, the sex chromosome pair is homomorphic with a recent origin, providing species for studying how and why recombination suppression evolved in the initial stages of sex chromosome differentiation, but this requires accurate sequence assembly of the X and Y (or Z and W) chromosomes, which may be difficult if they are recently diverged. Results Here we produce a haplotype-resolved genome assembly of zig-zag eel (Mastacembelus armatus), an aquaculture fish, at the chromosomal scale. The diploid assembly is nearly gap-free, and in most chromosomes, we resolve the centromeric and subtelomeric heterochromatic sequences. In particular, the Y chromosome, including its highly repetitive short arm, has zero gaps. Using resequencing data, we identify a ~7 Mb fully sex-linked region (SLR), spanning the sex chromosome centromere and almost entirely embedded in the pericentromeric heterochromatin. The SLRs on the X and Y chromosomes are almost identical in sequence and gene content, but both are repetitive and heterochromatic, consistent with zero or low recombination. We further identify an HMG-domain containing gene HMGN6 in the SLR as a candidate sex-determining gene that is expressed at the onset of testis development. Conclusions Our study supports the idea that preexisting regions of low recombination, such as pericentromeric regions, can give rise to SLR in the absence of structural variations between the proto-sex chromosomes.

scholarly journals Sex chromosome system ZZ/ZW in Apareiodon hasemani Eigenmann, 1916 (Characiformes, Parodontidae) and a derived chromosomal region

2012 ◽  
Vol 35 (4) ◽  
pp. 770-776 ◽  
Author(s):  
Elisangela Bellafronte ◽  
Michelle Orane Schemberger ◽  
Roberto Ferreira Artoni ◽  
Orlando Moreira Filho ◽  
Marcelo Ricardo Vicari
Keyword(s):  
Chromosomal Region ◽  
Sex Chromosome ◽  
Sex Chromosome System

scholarly journals A new species of the genus Rhaphidosoma Amyot et Serville, 1843 (Heteroptera, Reduviidae), with data on its chromosome complement

2021 ◽  
Vol 15 (4) ◽  
pp. 467-505
Author(s):  
Dmitry A. Gapon ◽  
Valentina G. Kuznetsova ◽  
Anna Maryańska-Nadachowska
Keyword(s):  
New Species ◽  
Fore Wing ◽  
Sex Chromosome ◽  
Complex Structure ◽  
Chromosome Complement ◽  
Morphological Description ◽  
Oriental Region ◽  
Western Asia ◽  
Sex Chromosome System ◽  
A New Species

A new species, Rhaphidosoma paganicumsp. nov. (Heteroptera: Reduviidae: Harpactorinae: Rhaphidosomatini), is described from the Dry Zone of Myanmar. It is the fifth species of Rhaphidosoma Amyot et Serville, 1843, known from the Oriental Region, and the first record of the genus for Myanmar and Indochina. The structure of the external and internal terminalia of the male and female is described and illustrated in detail. The completely inflated endosoma is described for the first time in reduviids. The complex structure of the ductus seminis is shown; it terminates with a voluminous seminal chamber which opens with a wide secondary gonopore and may be a place where spermatophores are formed. The new species is compared with all congeners from the Oriental Region and Western Asia. It is characterised by the absence of distinct tubercles on the abdominal tergites of the male, the presence only two long tubercles and small rounded ones on the abdominal tergites VII and VI, respectively, in the female, the presence of short fore wing vestiges which are completely hidden under longer fore wing vestiges, and other characters. In addition to the morphological description, an account is given of the male karyotype and the structure of testes of Rh. paganicumsp. nov. and another species of Harpactorinae, Polididus armatissimus Stål, 1859 (tribe Harpactorini). It was found that Rh. paganicumsp. nov. has a karyotype comprising 12 pairs of autosomes and a multiple sex chromosome system (2n♂=24A+X1X2X3Y), whereas P. armatissimus has a karyotype comprising five pairs of autosomes and a simple sex chromosome system (2n♂=10A+XY). The males of these species were found to have seven and nine follicles per testis, respectively. FISH mapping of 18S ribosomal DNA (major rDNA) revealed hybridisation signals on two of the four sex chromosomes (Y and one of the Xs) in Rh. paganicumsp. nov. and on the largest pair of autosomes in P. armatissimus. The presence of the canonical “insect” (TTAGG)n telomeric repeat was detected in the chromosomes of both species. This is the first application of FISH in the tribe Raphidosomatini and in the genus Polididus Stål, 1858.

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