Two karyotypes and heteromorphic sex chromosomes in Physalaemus petersi (Anura, Leptodactylidae)

1999 ◽  
Vol 77 (4) ◽  
pp. 624-631 ◽  
Author(s):  
Luciana B Lourenço ◽  
Shirlei M Recco-Pimentel ◽  
Adão J Cardoso
Keyword(s):  
Meiotic Division ◽  
Sex Chromosome ◽  
Chromosome Complement ◽  
Heteromorphic Sex Chromosomes ◽  
Karyological Evolution ◽  
Cytogenetic Analyses ◽  
Sex Chromosome System ◽  
Relationship Of ◽  
The Relationship ◽  
Two Populations

Cytogenetic analyses were performed on specimens from two populations of Physalaemus petersi from three locations in Brazilian West Amazon. Chromosomes from the testis and intestinal epithelium were stained conventionally with Giemsa or C-banded. All animals studied showed a full chromosome complement of 2n = 22, but two distinct karyotypes (I and II) were detected among specimens from one of the populations. Karyotype I specimens showed a XX/XY sex chromosome system and C-band polymorphism. Bivalent chromosomes with heterozygous C-banding frequently lacked chiasmata in the region of this heterochromatin during the first meiotic division. The less common karyotype (II) had a heteromorphic pair of chromosomes, but the relationship of this pair to sex determination could not be elucidated because of the absence of female specimens. Karyotype II was observed in males whose call differed from those of other males in the same population, suggesting that a reevaluation of the taxon P. petersi may be necessary. These results suggest that, in these populations, karyological evolution occurs faster than anatomical evolution.

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.

Heteromorphic Sex Chromosomes and Their DNA Content in Fish: An Insight through Satellite DNA Accumulation in Megaleporinus elongatus

2020 ◽  
Vol 160 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Carolina Crepaldi ◽  
Patricia P. Parise-Maltempi
Keyword(s):  
Sex Chromosomes ◽  
Dna Content ◽  
Satellite Dna ◽  
Sex Chromosome ◽  
Neotropical Fish ◽  
High Throughput Analysis ◽  
Multiple Sex Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Graph Based Clustering

The repetitive DNA content of fish sex chromosomes provides valuable insights into specificities and patterns of their genetic sex determination systems. In this study, we revealed the genomic satellite DNA (satDNA) content of Megaleporinuselongatus, a Neotropical fish species with Z1Z1Z2Z2/Z1W1Z2W2 multiple sex chromosomes, through high-throughput analysis and graph-based clustering, isolating 68 satDNA families. By physically mapping these sequences in female metaphases, we discovered 15 of the most abundant satDNAs clustered in its chromosomes, 9 of which were found exclusively in the highly heterochromatic W1. This heteromorphic sex chromosome showed the highest amount of satDNA accumulations in this species. The second most abundant family, MelSat02-26, shared FISH signals with the NOR-bearing pair in similar patterns and is linked to the multiple sex chromosome system. Our results demonstrate the diverse satDNA content in M. elongatus, especially in its heteromorphic sex chromosome. Additionally, we highlighted the different accumulation patterns and distribution of these sequences across species by physically mapping these satDNAs in other Anostomidae, Megaleporinusmacrocephalus and Leporinusfriderici (a species without differentiated sex chromosomes).

scholarly journals The role of the ameiotic1 gene in the initiation of meiosis and in subsequent meiotic events in maize.

Genetics ◽  
1993 ◽  
Vol 135 (4) ◽  
pp. 1151-1166 ◽  
Author(s):  
I Golubovskaya ◽  
Z K Grebennikova ◽  
N A Avalkina ◽  
W F Sheridan
Keyword(s):  
Meiotic Division ◽  
Higher Plants ◽  
Gene Interaction ◽  
Microtubule Organizing Center ◽  
Spindle Fiber ◽  
Chromosome Synapsis ◽  
Organizing Center ◽  
Relationship Of ◽  
The Relationship

Abstract Understanding the initiation of meiosis and the relationship of this event with other key cytogenetic processes are major goals in studying the genetic control of meiosis in higher plants. Our genetic and structural analysis of two mutant alleles of the ameiotic1 gene (am1 and am1-praI) suggest that this locus plays an essential role in the initiation of meiosis in maize. The product of the ameiotic1 gene affects an earlier stage in the meiotic sequence than any other known gene in maize and is important for the irreversible commitment of cells to meiosis and for crucial events marking the passage from premeiotic interphase into prophase I including chromosome synapsis. It appears that the period of ameiotic1 gene function in meiosis at a minimum covers the interval from some point during premeiotic interphase until the early zygotene stage of meiosis. To study the interaction of genes in the progression of meiosis, several double meiotic mutants were constructed. In these double mutants (i) the ameiotic1 mutant allele was brought together with the meiotic mutation (afd1) responsible for the fixation of centromeres in meiosis; and with the mutant alleles of the three meiotic genes that control homologous chromosome segregation (dv1, ms43 and ms28), which impair microtubule organizing center organization, the orientation of the spindle fiber apparatus, and the depolymerization of spindle filaments after the first meiotic division, respectively; (ii) the afd1 mutation was combined with two mutations (dsy1 and as1) affecting homologous pairing; (iii) the ms43 mutation was combined with the as1, the ms28 and the dv1 mutations; and (iv) the ms28 mutation was combined with the dv1 mutation and the ms4 (polymitotic1) mutations. An analysis of gene interaction in the double mutants led us to conclude that the ameiotic1 gene is epistatic over the afd1, the dv1, the ms43 and the ms28 genes but the significance of this relationship requires further analysis. The afd gene appears to function from premeiotic interphase throughout the first meiotic division, but it is likely that its function begins after the start of the ameiotic1 gene expression. The afd1 gene is epistatic over the two synaptic mutations dsy1 and as1 and also over the dv1 mutation. The new ameiotic*-485 and leptotene arrest*-487 mutations isolated from an active Robertson's Mutator stocks take part in the control of the initiation of meiosis.

scholarly journals First Report of Sex Chromosomes in Night Lizards (Scincoidea: Xantusiidae)

2020 ◽  
Vol 111 (3) ◽  
pp. 307-313 ◽  
Author(s):  
Stuart V Nielsen ◽  
Brendan J Pinto ◽  
Irán Andira Guzmán-Méndez ◽  
Tony Gamble
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Restriction Site ◽  
Sex Chromosome ◽  
Chromosome 2 ◽  
Squamate Reptiles ◽  
Determining Modes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Cytogenetic Methods

Abstract Squamate reptiles (lizards, snakes, and amphibians) are an outstanding group for studying sex chromosome evolution—they are old, speciose, geographically widespread, and exhibit myriad sex-determining modes. Yet, the vast majority of squamate species lack heteromorphic sex chromosomes. Cataloging the sex chromosome systems of species lacking easily identifiable, heteromorphic sex chromosomes, therefore, is essential before we are to fully understand the evolution of vertebrate sex chromosomes. Here, we use restriction site-associated DNA sequencing (RADseq) to classify the sex chromosome system of the granite night lizard, Xantusia henshawi. RADseq is an effective alternative to traditional cytogenetic methods for determining a species’ sex chromosome system (i.e., XX/XY or ZZ/ZW), particularly in taxa with non-differentiated sex chromosomes. Although many xantusiid lineages have been karyotyped, none possess heteromorphic sex chromosomes. We identified a ZZ/ZW sex chromosome system in X. henshawi—the first such data for this family. Furthermore, we report that the X. henshawi sex chromosome contains fragments of genes found on Gallus gallus chromosomes 7, 12, and 18 (which are homologous to Anolis carolinensis chromosome 2), the first vertebrate sex chromosomes to utilize this linkage group.

CYTOTAXONOMIC STUDIES ON THE GENUS BOONACRIS: I. The "eastern" taxa and a comparison with the related genera Dendrotettix and Appalachia (Orthoptera: Catantopidae: Podismini)

1976 ◽  
Vol 18 (4) ◽  
pp. 625-652 ◽  
Author(s):  
P. G. Fontana ◽  
V. R. Vickery
Keyword(s):  
Sex Chromosome ◽  
Chromosome Complement ◽  
The United States ◽  
Sympatric Species ◽  
Structural Differences ◽  
Cytogenetic Evidence ◽  
Phenetic Classification ◽  
Two Populations ◽  
Heterochromatin Content

Thirteen populations of four distinct taxa in the wingless grasshopper genus Boonacris with an eastern distribution in Canada and the United States had a chromosome complement of 2n ♀; ♂ = 20A + XO;XX. A detailed analysis of chromosome lengths and of the heterochromatin content and distribution in the karyotypes of the populations sampled revealed extreme endophenotypic stability and conservatism. Two populations were found to contain heterochromatically variant karyomorphs, one being polymorphic with respect to a complex pattern of autosome and sex-chromosome heterochromatin expression, the other for the occurrence of a large heterochromatic supernumerary chromosome. The cytogenetic system of Boonacris species was compared with those of the related, largely sympatric species Appalachia arcana and Dendrotettix quercus. The last two species have 2n ♀; ♂ = 22A + XO;XX but their complements show structural differences. The available evidence from a number of podismine species suggests that the forms with the lower chromosome number (i.e. 21 ♀; 22 ♂) may have originated from a common 'proto-Podisma' ancestor with 23 chromosomes (♀) via evolutionary loss or elimination of a small, unstable megameric pair. This dichotomy of major phyletic lineages and other cytogenetic evidence is discussed in relation to a phenetic classification of the tribe.

Muller's Ratchet and the evolution of supernumerary chromosomes

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 818-824 ◽  
Author(s):  
David M. Green
Keyword(s):  
Genetic Information ◽  
Sex Chromosome ◽  
Chromosome Complement ◽  
Evolutionary Constraint ◽  
Supernumerary Chromosomes ◽  
Muller's Ratchet ◽  
Heteromorphic Sex Chromosomes ◽  
Muller’S Ratchet ◽  
Over Time ◽  
Chromosome Heteromorphism

Supernumerary chromosomes arise from portions of the normal chromosome complement through nondisjunction, fragmentation, or other mechanisms. Once present in the genome, they are subject to virtually the same genetic conditions that affect the evolutionary degeneration of heteromorphic sex chromosomes. Y or W chromosomes occur only in the presence of X or Z chromosomes, respectively, just as supernumeraries never occur except in the presence of the complete regular karyotype containing their progenitor sequences. Thus, mechanisms that can account for the evolution of sex-chromosome heteromorphism can also be invoked to explain the degeneration process of supernumerary chromosomes after their origination. Incipient supernumeraries initially have genes identical with those on progenitor chromosomes. This frees them from the evolutionary constraint of carrying nonduplicated genetic information, just as in Y and W chromosomes during early stages of sex-chromosome differentiation. The degeneration of supernumerary chromosomes may thus proceed via the mechanism of Muller's Ratchet. This hypothesis predicts that supernumerary chromosomes should lose functional loci, lose sequence homology with the regular genome, and gain heterochromatin over time, resulting in multiple heteromorphic forms of degenerate supernumeraries within and between populations, as is commonly observed.Key words: supernumerary chromosomes, B chromosomes, evolution, origin, Muller's Ratchet.

scholarly journals Sex chromosome evolution from a heteromorphic to a homomorphic system by inter-population hybridization in a frog

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200105 ◽  
Author(s):  
Mitsuaki Ogata ◽  
Kazuo Suzuki ◽  
Yoshiaki Yuasa ◽  
Ikuo Miura
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Extended Period ◽  
Sex Chromosome Evolution ◽  
Opposite Case ◽  
Mitochondrial Haplotypes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Edge Populations

Sex chromosomes generally evolve from a homomorphic to heteromorphic state. Once a heteromorphic system is established, the sex chromosome system may remain stable for an extended period. Here, we show the opposite case of sex chromosome evolution from a heteromorphic to a homomorphic system in the Japanese frog Glandirana rugosa. One geographic group, Neo-ZW, has ZZ-ZW type heteromorphic sex chromosomes. We found that its western edge populations, which are geographically close to another West-Japan group with homomorphic sex chromosomes of XX-XY type, showed homozygous genotypes of sex-linked genes in both sexes. Karyologically, no heteromorphic sex chromosomes were identified. Sex-reversal experiments revealed that the males were heterogametic in sex determination. In addition, we identified another similar population around at the southwestern edge of the Neo-ZW group in the Kii Peninsula: the frogs had homomorphic sex chromosomes under male heterogamety, while shared mitochondrial haplotypes with the XY group, which is located in the east and bears heteromorphic sex chromosomes. In conclusion, our study revealed that the heteromorphic sex chromosome systems independently reversed back to or turned over to a homomorphic system around each of the western and southwestern edges of the Neo-ZW group through hybridization with the West-Japan group bearing homomorphic sex chromosomes. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

A cytological study of species in Cnephia s. str. (Diptera: Simuliidae)

1982 ◽  
Vol 60 (11) ◽  
pp. 2866-2878 ◽  
Author(s):  
William S. Procunier
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Cytological Study ◽  
Chromosome Complement ◽  
Nucleolar Organizer ◽  
Sympatric Speciation ◽  
Basic Chromosome ◽  
Y Chromosomes ◽  
Norwegian Population ◽  
Sex Chromosome System

Cytological descriptions and phylogenetic relationships are presented for the genus Cnephia s. str. All members are male achiasmate. Cnephia lapponica is unique in that its basic chromosome complement is reduced from n = 3 to n = 2 metacentrics as a result of a fusion of chromosomes II and III. Sex chromosome differentiation varies from nonobservable in C. ornithophilia and C. eremites through C. pecuarum in which the standard and IS-5 sequences are distributed differentially over X and Y chromosomes, to the polytypic system of C. lapponica in which the X chromosome is fixed for expression of the nucleolar organizer (NO) and the Y chromosome for nonexpression. Further, in a Norwegian population of C. lapponica, males are additionally interchange heterozygotes. Thus, a multiple sex chromosome system exists in which all the chromosomes are sex chromosomes. Closest members occur sympatrically and differ by sex chromosomes and at least one fixed inversion; more distant taxa differ by a number of fixed inversions as well as sex chromosomes. The identical bands 17B and 24C, which appear in a thin or enhanced form, are polymorphic, sex-linked, fixed, or lost in different members of the group. This study supports a model for sympatric speciation.

Mixed-Up Sex Chromosomes: Identification of Sex Chromosomes in the X1X1X2X2/X1X2Y System of the Legless Lizards of the Genus Lialis (Squamata: Gekkota: Pygopodidae)

2016 ◽  
Vol 149 (4) ◽  
pp. 282-289 ◽  
Author(s):  
Michail Rovatsos ◽  
Martina Johnson Pokorná ◽  
Marie Altmanová ◽  
Lukáš Kratochvíl
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
X Chromosomes ◽  
Telomeric Sequences ◽  
Multiple Sex Chromosomes ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Cytogenetic Analyses ◽  
Male Heterogamety

Geckos in general show extensive variability in sex determining systems, but only male heterogamety has been demonstrated in the members of their legless family Pygopodidae. In the pioneering study published more than 45 years ago, multiple sex chromosomes of the type X1X1X2X2/X1X2Y were described in Burton's legless lizard (Lialisburtonis) based on conventional cytogenetic techniques. We conducted cytogenetic analyses including comparative genomic hybridization and fluorescence in situ hybridization (FISH) with selected cytogenetic markers in this species and the previously cytogenetically unstudied Papua snake lizard (Lialis jicari) to better understand the nature of these sex chromosomes and their differentiation. Both species possess male heterogamety with an X1X1X2X2/X1X2Y sex chromosome system; however, the Y and one of the X chromosomes are not small chromosomes as previously reported in L. burtonis, but the largest macrochromosomal pair in the karyotype. The Y chromosomes in both species have large heterochromatic blocks with extensive accumulations of GATA and AC microsatellite motifs. FISH with telomeric probe revealed an exclusively terminal position of telomeric sequences in L. jicari (2n = 42 chromosomes in females), but extensive interstitial signals, potentially remnants of chromosomal fusions, in L.burtonis (2n = 34 in females). Our study shows that even largely differentiated and heteromorphic sex chromosomes might be misidentified by conventional cytogenetic analyses and that the application of more sensitive cytogenetic techniques for the identification of sex chromosomes is beneficial even in the classical examples of multiple sex chromosomes.

scholarly journals Relationship between chromosome content and nuclear diameter in early spermatids of Drosophila melanogaster

1989 ◽  
Vol 54 (3) ◽  
pp. 205-212 ◽  
Author(s):  
Cayetano González ◽  
José Casal ◽  
Pedro Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Light Microscopy ◽  
Sex Chromosome ◽  
Chromosome Complement ◽  
Wild Type ◽  
Male Sterile ◽  
Nuclear Diameter ◽  
Early Spermatid ◽  
The Relationship

SummaryWe have studied, using light microscopy, the relationship between chromosome content and nuclear diameter in early spermatids of males carrying different combinations of wild-type and compound chromosomes in Drosophila melanogaster. By using these genotypes we have been able to observe spermatid nuclei bearing various numbers of chromosomes ranging from only one sex chromosome and no major autosomes to almost twice the normal chromosome complement. We have found that variations in the chromosome content are accompanied by increasing the variance in early spermatid nuclear diameter; the more gametic classes produced, the higher the variance of nuclear diameters. These results indicate that measuring nuclear diameters in early spermatids represents a useful way to estimate the levels of meiotic non-disjunction and thereby to improve the characterization of lethal or male sterile mutants in which analysis of meiotic chrosome non-disjunction cannot be achieved by conventional genetic methods.

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