Structure and meiotic behaviour of B chromosomes in Sphaerium corneum/S. nucleus complex (Bivalvia: Sphaeriidae)

Kořínková, Tereza; Král, Jaroslav

doi:10.1007/s10709-010-9533-1

Cited by 5 publications

(2 citation statements)

References 45 publications

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“…Alternative mechanisms are present in different organisms with achiasmatic meiosis to maintain homologous chromosomes associated until metaphase I, ensuring the regular disjunction of the bivalents (e.g. Debus 1978;Oakley 1982;Marec 1996;Kor ˇı ´nkova ´and Kra ´l 2011;McKee et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Male and female meiosis in the mountain scorpion Zabius fuscus (Scorpiones, Buthidae): heterochromatin, rDNA and TTAGG telomeric repeats

et al. 2015

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All cytogenetically studied scorpions present male achiasmatic meiosis and lack heteromorphic sex chromosomes. In contrast, information about female meiosis in scorpions is scarce due to the difficulty of finding meiotic cells. The genus Zabius includes three described species and no chromosome studies have been performed on it until now. We analyzed the constitutive heterochromatin distribution, NORs and telomeric sequences in mitosis and meiosis of males and females of different populations of Zabius fuscus. All specimens presented 2n = 18 holokinetic chromosomes that gradually decreased in size. Male meiosis presented nine bivalents and a polymorphism for one reciprocal translocation in one population. Telomeric signals were detected at every terminal region, confirming also the presence of a (TTAGG) n motif in Buthidae. Constitutive heterochromatin was found in three chromosome pairs at a terminal region; moreover, NORs were embedded in the heterochromatic region of the largest pair. Chromosome size and landmarks allowed us to propose the chromosomes involved in the rearrangement. In four females, cells at different prophase I stages were analyzed. We describe a diffuse stage and the presence of ring-shaped bivalents. We discuss the possible origin of these bivalents in the framework of chiasmatic or achiasmatic female meiosis. These results contribute to increase the scarce evidence of female meiosis in scorpions and raise new questions about its mechanism.

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Section: Discussionmentioning

confidence: 99%

Male and female meiosis in the mountain scorpion Zabius fuscus (Scorpiones, Buthidae): heterochromatin, rDNA and TTAGG telomeric repeats

et al. 2015

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“…nucleus in order to find species-specific karyological characters and to compare it to S . corneum were unsuccessful [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

Comments on species divergence in the genus Sphaerium (Bivalvia) and phylogenetic affinities of Sphaerium nucleus and S. corneum var. mamillanum based on karyotypes and sequences of 16S and ITS1 rDNA

Petkevičiūtė¹,

Stunžėnas²,

Stanevičiūtė³

2018

PLoS ONE

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Chromosome, 16S and ITS1 rDNA sequence analyses were used to obtain reliable diagnostic characters and to clarify phylogenetic relationships of sphaeriid bivalves of the genus Sphaerium. The species studied were found to be diploid, with modal number 2n = 28 in S. nucleus and 2n = 30 in S. corneum var. mamillanum. Small, biarmed, C- negative B chromosomes were found in all studied populations of both species. Karyological and molecular markers revealed no differences between S. corneum s. str. and S. corneum var. mamillanum. No intraspecific differences were found in the basic karyotype of S. nucleus. Molecular analyses, however, uncovered three genetically distinct ITS1 lineages: one comprised of samples from Lithuania, Slovakia, and Russia, another from Czech, and a third from Ukraine. Additionally to known 16S haplotype from Ukraine, three new 16S haplotypes of S. nucleus were detected: one in the samples from Lithuania and Russia, one in Slovakian and one in Czech population. In the ITS1 phylogenetic tree, all branches of S. nucleus clustered in one clade. In the 16S phylogenetic tree, however, the haplotype of Czech S. nucleus formed a separate branch, distant from three other haplotypes of S. nucleus. Molecular results indicate that in the context of the Evolutionary Species Concept the S. nucleus morphospecies may represent a complex of separate taxa, however referring on the Biological Species Concept the genetic lineages could represent the intraspecific variability.

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Off the conservation radar: the hidden story of Europe's tiny pea clams (Bivalvia: Sphaeriidae)

Halabowski,

Sousa,

Lopes-Lima

et al. 2024

Biodivers Conserv

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This study highlights the conservation problems faced by the tiny freshwater bivalves of the family Sphaeriidae, also known as pea, pill, or fingernail clams (or mussels) in Europe. Despite their global distribution, assumed ecological importance, and potential uses, basic knowledge about their taxonomy, biology, and ecology is very limited and much lower than for the larger freshwater bivalve taxa. Immediate scientific priorities are required to fill knowledge gaps regarding their taxonomy, genetic diversity, distribution, reproductive cycle, ecosystem functions, and population trends. Such fundamental knowledge is necessary to identify specific threats and develop appropriate conservation actions. Deploying environmental DNA analysis at a large scale could be a valuable way to fill gaps in distribution and strengthen monitoring in areas where local taxonomic knowledge is lacking. Until taxon-specific management plans can be developed, we recommend that efforts concentrate on the general protection and restoration of wetland habitats, implementing pollution control measures, and managing invasive species. These actions should be complemented by community engagement through citizen science initiatives. Additionally, prioritising data collection to fill existing knowledge gaps and updating conservation statuses (Red Lists) based on comprehensive assessments will be crucial. Implementing these actions will provide a starting point for the broader protection of freshwater ecosystems, thus benefiting pea clams and other interconnected species within these habitats.

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Structure and meiotic behaviour of B chromosomes in Sphaerium corneum/S. nucleus complex (Bivalvia: Sphaeriidae)

Cited by 5 publications

References 45 publications

Male and female meiosis in the mountain scorpion Zabius fuscus (Scorpiones, Buthidae): heterochromatin, rDNA and TTAGG telomeric repeats

Male and female meiosis in the mountain scorpion Zabius fuscus (Scorpiones, Buthidae): heterochromatin, rDNA and TTAGG telomeric repeats

Comments on species divergence in the genus Sphaerium (Bivalvia) and phylogenetic affinities of Sphaerium nucleus and S. corneum var. mamillanum based on karyotypes and sequences of 16S and ITS1 rDNA

Off the conservation radar: the hidden story of Europe's tiny pea clams (Bivalvia: Sphaeriidae)

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