Meiotic studies in<i>Brachistosternus alienus</i>(Scorpiones; Bothriuridae)

Adilardi, Renzo Sebastián; Ojanguren‐Affilastro, Andrés A.; Gil, Sergio Gustavo Rodríguez; Scioscia, Cristina Luisa; Mola, Liliana M.

doi:10.1636/b12-77.1

Cited by 3 publications

(1 citation statement)

References 16 publications

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“…Interestingly, in N. parvulus , we observed that chromosomal pairs of regular size have a higher amount of constitutive heterochromatin (CH) in relation to microchromosomes. This pattern is unusual for monocentric Scorpiones chromosomes, which have low heterochromatic content, generally restricted to small pericentromeric blocks [ 2 , 28 , 39 , 70 , 71 ]. Thus, we suggest that CH amplification in some karyotype pairs of N. parvulus may contribute to the maintenance of the bimodality of the karyotype of this species.…”

Section: Discussionmentioning

confidence: 99%

High Chromosomal Reorganization and Presence of Microchromosomes in Chactidae Scorpions from the Brazilian Amazon

Almeida

Malcher

Costa

et al. 2023

Biology

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Scorpions are of particular interest in cytogenomic studies, as they can present a high incidence of chromosomal rearrangements heterozygous in natural populations. In this study, we cytogenetically analyzed four species of Chactidae. In Brotheas, 2n = 40 was observed in Brotheas silvestris, 2n = 48 in Brotheas paraensis, and 2n = 50 (cytotype A) or 2n = 52 (cytotype B) among populations of Brotheas amazonicus. Our results showed a bimodal karyotype in Neochactas parvulus, 2n = 54, with microchromosomes and a concentration of constitutive heterochromatin in macrochromosomes. The 45S rDNA is located in only one pair of the karyotype, with different heteromorphisms of clusters of this rDNA in the cytotype B of B. amazonicus, with NOR-bearing chromosomes involved in multi-chromosomal associations during meiosis I. The U2 snDNA was mapped in the interstitial region of distinct karyotype pairs of three Chactidae species. Our results indicate the possible formation of cryptic species in B. amazonicus; the different 45S rDNA configurations in the genome of this species may result from amplification and degeneration. We suggest that the bimodal karyotype in N. parvulus results from fusion/fission events and that the unequal distribution of repetitive DNAs between macro and microchromosomes contributes to the maintenance of its asymmetry.

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Section: Discussionmentioning

confidence: 99%

High Chromosomal Reorganization and Presence of Microchromosomes in Chactidae Scorpions from the Brazilian Amazon

Almeida

Malcher

Costa

et al. 2023

Biology

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Bridging the cytogenetic gap in Trichoptera (Insecta): first karyotypic data on Neotropical species and insights into chromosomal evolution in caddisflies

Lovaglio Diez,

Bressa,

Rodríguez Gil

et al. 2023

Biological Journal of the Linnean Society

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Trichoptera are a diverse group of insects with aerial adults and aquatic immature stages. Despite their importance in freshwater environments, fundamental aspects of their biology are unknown, and no chromosomal studies have been performed in Neotropical species. The aim of this study was to provide the first cytogenetic analysis of four Trichoptera species from the Neotropics. We analysed the meiotic development and chromosome behaviour in Smicridea (Rhyacophylax) pampeana Flint (Annulipalpia: Hydropsychidae), Marilia flexuosa Ulmer (Integripalpia: Odontoceridae), Triplectides misionensis Holzenthal (Integripalpia: Leptoceridae), and Grumicha grumicha (Vallot) (Integripalpia: Sericostomatidae) by conventional cytogenetic procedures. The chromosome numbers are 2n = 31/32 (female/male) in S. (R.) pampeana, 2n = 57 (female) in M. flexuosa, 2n = 47 (female) in T. misionensis, and 2n = 35 (female) in G. grumicha. All four species have a simple sex chromosome system Z/ZZ (female/male). Females are the heterogametic sex, and their meiosis is achiasmatic. Our results together with available cytogenetic data provide more information on the karyology of Trichoptera and contribute to the current scientific knowledge of the possible mechanisms involved in chromosomal evolution. Based on all the evidence, we propose the existence of possible positive relationships between biological traits, ecological strategies, and cytogenetic features in Trichoptera.

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Sex-Linked Chromosome Heterozygosity in Males of Tityus confluens (Buthidae): A Clue about the Presence of Sex Chromosomes in Scorpions

Adilardi¹,

Ojanguren‐Affilastro²,

Mola³

2016

PLoS ONE

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Scorpions of the genus Tityus show holokinetic chromosomes, achiasmatic male meiosis and an absence of heteromorphic sex chromosomes, like all Buthidae. In this work, we analysed the meiotic behaviour and chromosome rearrangements of a population of the scorpion Tityus confluens, characterising the cytotypes of males, females and embryos with different cytogenetic techniques. This revealed that all the females were structural homozygotes, while all the males were structural heterozygotes for different chromosome rearrangements. Four different cytotypes were described in males, which differed in chromosome number (2n = 5 and 2n = 6) and meiotic multivalent configurations (chains of four, five and six chromosomes). Based on a detailed mitotic and meiotic analysis, we propose a sequence of chromosome rearrangements that could give rise to each cytotype and in which fusions have played a major role. Based on the comparison of males, females and a brood of embryos, we also propose that the presence of multivalents in males and homologous pairs in females could be associated with the presence of cryptic sex chromosomes, with the male being the heterogametic sex. We propose that the ancestral karyotype of this species could have had homomorphic XY/XX (male/female) sex chromosomes and a fusion could have occurred between the Y chromosome and an autosome.

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Meiotic studies inBrachistosternus alienus(Scorpiones; Bothriuridae)

Cited by 3 publications

References 16 publications

High Chromosomal Reorganization and Presence of Microchromosomes in Chactidae Scorpions from the Brazilian Amazon

High Chromosomal Reorganization and Presence of Microchromosomes in Chactidae Scorpions from the Brazilian Amazon

Bridging the cytogenetic gap in Trichoptera (Insecta): first karyotypic data on Neotropical species and insights into chromosomal evolution in caddisflies

Sex-Linked Chromosome Heterozygosity in Males of Tityus confluens (Buthidae): A Clue about the Presence of Sex Chromosomes in Scorpions

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