Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Chiasmatic and achiasmatic inverted meiosis of plants with holocentric chromosomes.

ABSTRACT: Meiosis is a specialized cell division in sexually reproducing organisms before gamete formation. Following DNA replication, the canonical sequence in species with monocentric chromosomes is characterized by reductional segregation of homologous chromosomes during the first and equational segregation of sister chromatids during the second meiotic division. Species with holocentric chromosomes employ specific adaptations to ensure regular disjunction during meiosis. Here we present the analysis of two closely related plant species with holocentric chromosomes that display an inversion of the canonical meiotic sequence, with the equational division preceding the reductional. In-depth analysis of the meiotic divisions of Rhynchospora pubera and R. tenuis reveals that during meiosis I sister chromatids are bi-oriented, display amphitelic attachment to the spindle and are subsequently separated. During prophase II, chromatids are connected by thin chromatin threads that appear instrumental for the regular disjunction of homologous non-sister chromatids in meiosis II.

SUBMITTER: Cabral G

PROVIDER: S-EPMC4190664 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Versatility of multivalent orientation, inverted meiosis, and rescued fitness in holocentric chromosomal hybrids.

Project description:Chromosomal rearrangements (e.g., fusions/fissions) have the potential to drive speciation. However, their accumulation in a population is generally viewed as unlikely, because chromosomal heterozygosity should lead to meiotic problems and aneuploid gametes. Canonical meiosis involves segregation of homologous chromosomes in meiosis I and sister chromatid segregation during meiosis II. In organisms with holocentric chromosomes, which are characterized by kinetic activity distributed along almost the entire chromosome length, this order may be inverted depending on their metaphase I orientation. Here we analyzed the evolutionary role of this intrinsic versatility of holocentric chromosomes, which is not available to monocentric ones, by studying F1 to F4 hybrids between two chromosomal races of the Wood White butterfly (Leptidea sinapis), separated by at least 24 chromosomal fusions/fissions. We found that these chromosomal rearrangements resulted in multiple meiotic multivalents, and, contrary to the theoretical prediction, the hybrids displayed relatively high reproductive fitness (42% of that of the control lines) and regular behavior of meiotic chromosomes. In the hybrids, we also discovered inverted meiosis, in which the first and critical stage of chromosome number reduction was replaced by the less risky stage of sister chromatid separation. We hypothesize that the ability to invert the order of the main meiotic events facilitates proper chromosome segregation and hence rescues fertility and viability in chromosomal hybrids, potentially promoting dynamic karyotype evolution and chromosomal speciation.

| S-EPMC6187165 | biostudies-literature

Holocentric chromosomes.

Project description:Holocentric chromosomes possess multiple kinetochores along their length rather than the single centromere typical of other chromosomes [1]. They have been described for the first time in cytogenetic experiments dating from 1935 and, since this first observation, the term holocentric chromosome has referred to chromosomes that: i. lack the primary constriction corresponding to centromere observed in monocentric chromosomes [2]; ii. possess multiple kinetochores dispersed along the chromosomal axis so that microtubules bind to chromosomes along their entire length and move broadside to the pole from the metaphase plate [3]. These chromosomes are also termed holokinetic, because, during cell division, chromatids move apart in parallel and do not form the classical V-shaped figures typical of monocentric chromosomes [4-6]. Holocentric chromosomes evolved several times during both animal and plant evolution and are currently reported in about eight hundred diverse species, including plants, insects, arachnids and nematodes [7,8]. As a consequence of their diffuse kinetochores, holocentric chromosomes may stabilize chromosomal fragments favouring karyotype rearrangements [9,10]. However, holocentric chromosome may also present limitations to crossing over causing a restriction of the number of chiasma in bivalents [11] and may cause a restructuring of meiotic divisions resulting in an inverted meiosis [12].

| S-EPMC7392213 | biostudies-literature

Flow cytometry may allow microscope-independent detection of holocentric chromosomes in plants.

Project description:Two chromosomal structures, known as monocentric and holocentric chromosomes, have evolved in eukaryotes. Acentric fragments of monocentric chromosomes are unequally distributed to daughter cells and/or lost, while holocentric fragments are inherited normally. In monocentric species, unequal distribution should generate chimeras of cells with different nuclear DNA content. We investigated whether such differences in monocentric species are detectable by flow cytometry (FCM) as (i) a decreased nuclear DNA content and (ii) an increased coefficient of variance (CV) of the G1 peak after gamma radiation-induced fragmentation. We compared 13 monocentric and 9 holocentric plant species. Unexpectedly, monocentrics and holocentrics did not differ with respect to parameters (i) and (ii) in their response to gamma irradiation. However, we found that the proportion of G2 nuclei was highly elevated in monocentrics after irradiation, while holocentrics were negligibly affected. Therefore, we hypothesize that DNA-damaging agents induce cell cycle arrest leading to endopolyploidy only in monocentric and not (or to much lesser extent) in holocentric plants. While current microscope-dependent methods for holocentrism detection are unreliable for small and numerous chromosomes, which are common in holocentrics, FCM can use somatic nuclei. Thus, FCM may be a rapid and reliable method of high-throughput screening for holocentric candidates across plant phylogeny.

| S-EPMC4891681 | biostudies-literature

Holocentric plant meiosis: first sisters, then homologues.

Project description:Meiosis is a crucial process of sexual reproduction by forming haploid gametes from diploid precursor cells. It involves 2 subsequent divisions (meiosis I and meiosis II) after one initial round of DNA replication. Homologous monocentric chromosomes are separated during the first and sister chromatids during the second meiotic division. The faithful segregation of monocentric chromosomes is realized by mono-orientation of fused sister kinetochores at metaphase I and by bi-orientation of sister kinetochores at metaphase II. Conventionally this depends on a 2-step loss of cohesion, along chromosome arms during meiosis I and at sister centromeres during meiosis II.

| S-EPMC4613655 | biostudies-other

Evidence for centromere drive in the holocentric chromosomes of Caenorhabditis.

Project description:In monocentric organisms with asymmetric meiosis, the kinetochore proteins, such as CENH3 and CENP-C, evolve adaptively to counterbalance the deleterious effects of centromere drive, which is caused by the expansion of centromeric satellite repeats. The selection regimes that act on CENH3 and CENP-C genes have not been analyzed in organisms with holocentric chromosomes, although holocentrism is speculated to have evolved to suppress centromere drive. We tested both CENH3 and CENP-C for positive selection in several species of the holocentric genus Caenorhabditis using the maximum likelihood approach and sliding-window analysis. Although CENP-C did not show any signs of positive selection, positive selection has been detected in the case of CENH3. These results support the hypothesis that centromere drive occurs in Nematoda, at least in the telokinetic meiosis of Caenorhabditis.

| S-EPMC3264583 | biostudies-literature

Holocentric Chromosomes Probably Do Not Prevent Centromere Drive in Cyperaceae.

Project description:Centromere drive model describes an evolutionary process initiated by centromeric repeats expansion, which leads to the recruitment of excess kinetochore proteins and consequent preferential segregation of an expanded centromere to the egg during female asymmetric meiosis. In response to these selfish centromeres, the histone protein CenH3, which recruits kinetochore components, adaptively evolves to restore chromosomal parity and counter the detrimental effects of centromere drive. Holocentric chromosomes, whose kinetochores are assembled along entire chromosomes, have been hypothesized to prevent expanded centromeres from acquiring a selective advantage and initiating centromere drive. In such a case, CenH3 would be subjected to less frequent or no adaptive evolution. Using codon substitution models, we analyzed 36 CenH3 sequences from 35 species of the holocentric family Cyperaceae. We found 10 positively selected codons in the CenH3 gene [six codons in the N-terminus and four in the histone fold domain (HFD)] and six branches of its phylogeny along which the positive selection occurred. One of the positively selected codons was found in the centromere targeting domain (CATD) that directly interacts with DNA and its mutations may be important in centromere drive suppression. The frequency of these positive selection events was comparable to the frequency of positive selection in monocentric clades with asymmetric female meiosis. Taken together, these results suggest that preventing centromere drive is not the primary adaptive role of holocentric chromosomes, and their ability to suppress it likely depends on their kinetochore structure in meiosis.

| S-EPMC7933567 | biostudies-literature

Restructuring of Holocentric Centromeres During Meiosis in the Plant Rhynchospora pubera.

Project description:Centromeres are responsible for the correct segregation of chromosomes during mitosis and meiosis. Holocentric chromosomes, characterized by multiple centromere units along each chromatid, have particular adaptations to ensure regular disjunction during meiosis. Here we show by detecting CENH3, CENP-C, tubulin, and centromeric repeats that holocentromeres may be organized differently in mitosis and meiosis of Rhynchospora pubera Contrasting to the mitotic linear holocentromere organization, meiotic centromeres show several clusters of centromere units (cluster-holocentromeres) during meiosis I. They accumulate along the poleward surface of bivalents where spindle fibers perpendicularly attach. During meiosis II, the cluster-holocentromeres are mostly present in the midregion of each chromatid. A linear holocentromere organization is restored after meiosis during pollen mitosis. Thus, a not yet described case of a cluster-holocentromere organization, showing a clear centromere restructuration between mitosis and meiosis, was identified in a holocentric organism.

| S-EPMC5068846 | biostudies-literature

Correction: Evidence for Centromere Drive in the Holocentric Chromosomes of Caenorhabditis.

Project description: Not available

| S-EPMC4728075 | biostudies-literature

HIM-10 is required for kinetochore structure and function on Caenorhabditis elegans holocentric chromosomes.

Project description:Macromolecular structures called kinetochores attach and move chromosomes within the spindle during chromosome segregation. Using electron microscopy, we identified a structure on the holocentric mitotic and meiotic chromosomes of Caenorhabditis elegans that resembles the mammalian kinetochore. This structure faces the poles on mitotic chromosomes but encircles meiotic chromosomes. Worm kinetochores require the evolutionarily conserved HIM-10 protein for their structure and function. HIM-10 localizes to the kinetochores and mediates attachment of chromosomes to the spindle. Depletion of HIM-10 disrupts kinetochore structure, causes a failure of bipolar spindle attachment, and results in chromosome nondisjunction. HIM-10 is related to the Nuf2 kinetochore proteins conserved from yeast to humans. Thus, the extended kinetochores characteristic of C. elegans holocentric chromosomes provide a guide to the structure, molecular architecture, and function of conventional kinetochores.

| S-EPMC2192032 | biostudies-literature

Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution.

Project description:Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

| S-EPMC6561736 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data