Cytogenetic comparison of Cuscuta psorothamnensis and C. veatchii (Convolvulaceae), two species originated from recurrent hybridization between the same diploid parents

Plant Systematics and Evolution, Journal Year: 2025, Volume and Issue: 311(2)

Published: Feb. 14, 2025

Language: Английский

---

Chromosome homologies and polymorphisms in a Neotropical species complex of frogs revealed by the U2 snRNA gene

Genome, Journal Year: 2025, Volume and Issue: 68, P. 1 - 11

Published: Jan. 1, 2025

The Physalaemus cuvieri–Physalaemus ephippifer species complex is a Neotropical frog group that encompasses seven well-supported major clades. Although very similar morphologically, the five lineages previously karyotyped show notorious cytogenetic signatures. There also evidence of ancient secondary contact between P. ephippifer, which has heteromorphic sex chromosomes, and lineage known as L1B, lacks chromosome heteromorphism. Here, to aid comparative analysis within this complex, we mapped U2 small nuclear RNA (snRNA) gene using fluorescent in situ hybridization (FISH). All samples presented snRNA cluster terminally short arm 6. Additional FISH signals were revealed, particularly one with noted polymorphism nucleolar organizer regions. Moreover, additional site contributed for since Z harbors signal, absent W chromosome. In 9—which homologous chromosomes ephippifer—is polymorphic did derived from these lineages. Finally, nucleotide sequence revealed some truncated sequences, suggesting presence pseudogenes frogs.

Language: Английский

---

Cytogenetic insights into Sosippinae (Araneae, Lycosidae) reveal pronounced diploid number reduction in Aglaoctenus and elevated number of rDNA loci in two unrelated species

Zoology, Journal Year: 2025, Volume and Issue: 170, P. 126269 - 126269

Published: April 17, 2025

Language: Английский

---

Evolving Together: Cassandra Retrotransposons Gradually Mirror Promoter Mutations of the 5S rRNA Genes

Molecular Biology and Evolution, Journal Year: 2024, Volume and Issue: 41(2)

Published: Jan. 23, 2024

Abstract The 5S rRNA genes are among the most conserved nucleotide sequences across all species. Similar to preservation we observe occurrence of 5S-related nonautonomous retrotransposons, so-called Cassandras. Cassandras harbor highly rDNA-related within their long terminal repeats, advantageously providing them with internal promoter. However, dynamics Cassandra retrotransposon evolution in context gene sequence information and structural arrangement still unclear, especially: (1) do repeated or gradual domestication promoter by (2) changes organization such as linked 35S-5S rDNA arrangements impact evolution? Here, show evidence for co-evolution corresponding rDNAs. To follow variability on TEs, investigate Asteraceae family where variable rDNAs, including shifts both separated have been reported. mirror mutations host genome, likely an adaptation host's specific transcription factors hence compensating evolutionary sequence. Changes seem uncorrelated linked/separated arrangements. We place these observations into angiosperm rDNA-Cassandra evolution, discuss Cassandra's origin hypotheses (single multiple) possible plant genome organization, giving new insights interplay ribosomal transposable elements.

Language: Английский

---

Structure and Evolution of Ribosomal Genes of Insect Chromosomes

Insects, Journal Year: 2024, Volume and Issue: 15(8), P. 593 - 593

Published: Aug. 4, 2024

Currently, clusters of 45S and 5S ribosomal DNA (rDNA) have been studied in about 1000 100 species the class Insecta, respectively. Although number insect with known rDNA (also referred to as nucleolus-organizing regions, or NORs) constitutes less than 0.1 percent described members this enormous group, certain conclusions can already be drawn. Since haploid karyotypes single predominate both basal derived groups, character state is apparently ancestral for Insecta general. Nevertheless, number, chromosomal location, other characteristics sites substantially vary across different species, sometimes even within same species. There are several main factors molecular mechanisms that either maintain these parameters alter them on short-term and/or long-term scale. Chromosome structure (i.e., monocentric vs. holokinetic chromosomes), excessive numbers rRNA gene copies per cluster, interactions transposable elements, pseudogenization, meiotic recombination perhaps most important among them.

Language: Английский

---

Chromosomal organization of different repetitive sequences in four wasp species of the genus Trypoxylon Latreille (Hymenoptera: Crabronidae) and insights into the composition of wasp telomeres

Genome, Journal Year: 2024, Volume and Issue: 67(7), P. 243 - 255

Published: April 9, 2024

This study characterizes the chromosomal organization of DNA repetitive sequences and karyotypic evolution in four representatives solitary wasp genus Trypoxylon using conventional molecular cytogenetic techniques. Our findings present first data for rogenhoferi (2 n = 30) albonigrum 32), while karyotypes nitidum lactitarse were similar to those previously described. Fluorochrome staining microsatellite distribution revealed differences constitutive heterochromatin composition among species. T. exhibited one major rDNA cluster, potentially representing an ancestral pattern aculeate Hymenoptera, showed two pericentromeric rRNA gene sites, suggesting amplification events their clade. The (TCAGG) motif hybridized terminal regions chromosomes all species, which may suggest that this sequence represents telomeric repeat. Notably, presence centromeric certain chromosome pairs species supports hypothesis fusions or inversions karyotype Trypoxylon. expands mapping wasps offers insights into dynamic evolutionary landscape these insects.

Language: Английский

---

LINE1 elements at distal junctions of rDNA repeats regulate nucleolar organization in human embryonic stem cells

Genes & Development, Journal Year: 2024, Volume and Issue: 39(3-4), P. 280 - 298

Published: Dec. 20, 2024

The nucleolus is a major subnuclear compartment where ribosomal DNA (rDNA) transcribed and ribosomes are assembled. In addition, recent studies have shown that the dynamic organizer of chromatin architecture modulates developmental gene expression. rDNA units assembled into arrays located in p-arms five human acrocentric chromosomes. Distal junctions (DJs) ∼400 kb sequences adjacent to thought anchor them at nucleolus, although underlying regulatory elements remain unclear. Here we show DJs display chromosome conformation profile embryonic stem cells (hESCs). We identified primate-specific, full-length insertion retrotransposon long interspersed nuclear element 1 (LINE1) conserved position across all DJs. This DJ-LINE1 locus interacts with specific regions DJ upregulated naïve hESCs. CRISPR-based deletion interference approaches revealed contributes nucleolar positioning Moreover, found expression required for maintenance structure transcriptional output Silencing leads loss self-renewal, disruption landscape accessibility, derepression earlier programs work uncovers LINE1 fundamental role organization hESCs provides new insights how functions as key genome-organizing hub.

Language: Английский

---

Cytogenetic comparison of Cuscuta psorothamnensis and C. veatchii (Convolvulaceae), two species originated from recurrent hybridization between the same diploid parents

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: April 19, 2024

Genus Cuscuta L. (Convolvulaceae) exhibits cases of hybridization and allopolyploidy. Section Denticulatae, subg. Grammica, includes four species: the allopolyploids, C. veatchii psorothamnensis (2n = 60), which originated from two independent reticulation events between diploids, denticulata nevadensis 30). The allopolyploids are morphologically similar, but differing in their geographical distribution host specificity. While cytogenetic data have been reported for veatchii, this study aims to provide a comparative analysis with psorothamnensis. To characterize chromosomal complement compare it we used CMA/DAPI banding, FISH, GISH. karyotypes both species displayed similarity chromosome number, size, symmetry, interphase nucleus organization. Both exhibited pair 5S 35S rDNA sites adjacent on same chromosome. number is variable, some individuals displaying four, five, six sites. Our results show: 1) carrying retained polyploids; 2) loss occurred tetraploids; 3) part complex, successive nevadensis; 4) probably more recent origin than based degree diploidization. This comparison allows us understand processes involved emergence new polyploid by hybridization.

Language: Английский

---

Comparative cytogenetics of kenaf (Hibiscus cannabinus L.) breeding lines reveal chromosomal variability and instability

Genetic Resources and Crop Evolution, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 12, 2024

Language: Английский

---

Repeatome Analysis and Satellite DNA Chromosome Patterns in Hedysarum Species

International Journal of Molecular Sciences, Journal Year: 2024, Volume and Issue: 25(22), P. 12340 - 12340

Published: Nov. 17, 2024

The cosmopolitan genus

Language: Английский

---