scholarly journals Heterozygosity and Chain Multivalents during Meiosis Illustrate Ongoing Evolution as a Result of Multiple Holokinetic Chromosome Fusions in the Genus Melinaea (Lepidoptera, Nymphalidae)

2017 ◽  
Vol 153 (4) ◽  
pp. 213-222 ◽  
Author(s):  
Melanie McClure ◽  
Bernard Dutrillaux ◽  
Anne-Marie Dutrillaux ◽  
Vladimir Lukhtanov ◽  
Marianne Elias
Keyword(s):  
Chromosome Evolution ◽  
Taxonomic Revision ◽  
Variable Number ◽  
Chromosome Fusion ◽  
Meiotic Chromosomes ◽  
In Captivity ◽  
Chromosome Fusions ◽  
The Common ◽  
Multiple Spindle ◽  
Complex Chromosome

Mitotic and meiotic chromosomes from 2 taxa of the genus Melinaea, M. satevis cydon and M. “satevis” tarapotensis (Lepidoptera: Nymphalidae), and from hybrids produced in captivity were obtained using an improved spreading technique and were subsequently analyzed. In one of the taxa, the presence of trivalents and tetravalents at diakinesis/metaphase I is indicative of heterozygosity for multiple chromosome fusions or fissions, which might explain the highly variable number of chromosomes previously reported in this genus. Two large and complex multivalents were observed in the meiotic cells of the hybrid males (32 chromosomes) obtained from a cross between M. “s.” tarapotensis (28 chromosomes) and M. s. cydon (40-43 chromosomes). The contribution of the 2 different haploid karyotypes to these complex figures during meiosis is discussed, and a taxonomic revision is proposed. We conclude that chromosome evolution is active and ongoing, that the karyotype of the common ancestor consisted of at least 48 chromosomes, and that evolution by chromosome fusion rather than fission is responsible for this pattern. Complex chromosome evolution in this genus may drive reproductive isolation and speciation, and highlights the difficulties inherent to the systematics of this group. We also show that Melinaea chromosomes, classically considered as holocentric, are attached to unique, rather than multiple, spindle fibers.

scholarly journals Epigenetic dynamics of centromeres and neocentromeres in Cryptococcus deuterogattii

PLoS Genetics ◽  
2021 ◽  
Vol 17 (8) ◽  
pp. e1009743
Author(s):  
Klaas Schotanus ◽  
Vikas Yadav ◽  
Joseph Heitman
Keyword(s):  
Dna Methylation ◽  
Transposable Element ◽  
Fungal Pathogen ◽  
Fusion Partner ◽  
Epigenetic Memory ◽  
Chromosome Fusion ◽  
Human Fungal Pathogen ◽  
Chromosome Fusions ◽  
The Impact ◽  
Active Centromere

Deletion of native centromeres in the human fungal pathogen Cryptococcus deuterogattii leads to neocentromere formation. Native centromeres span truncated transposable elements, while neocentromeres do not and instead span actively expressed genes. To explore the epigenetic organization of neocentromeres, we analyzed the distribution of the heterochromatic histone modification H3K9me2, 5mC DNA methylation and the euchromatin mark H3K4me2. Native centromeres are enriched for both H3K9me2 and 5mC DNA methylation marks and are devoid of H3K4me2, while neocentromeres do not exhibit any of these features. Neocentromeres in cen10Δ mutants are unstable and chromosome-chromosome fusions occur. After chromosome fusion, the neocentromere is inactivated and the native centromere of the chromosome fusion partner remains as the sole, active centromere. In the present study, the active centromere of a fused chromosome was deleted to investigate if epigenetic memory promoted the re-activation of the inactive neocentromere. Our results show that the inactive neocentromere is not re-activated and instead a novel neocentromere forms directly adjacent to the deleted centromere of the fused chromosome. To study the impact of transcription on centromere stability, the actively expressed URA5 gene was introduced into the CENP-A bound regions of a native centromere. The introduction of the URA5 gene led to a loss of CENP-A from the native centromere, and a neocentromere formed adjacent to the native centromere location. Remarkably, the inactive, native centromere remained enriched for heterochromatin, yet the integrated gene was expressed and devoid of H3K9me2. A cumulative analysis of multiple CENP-A distribution profiles revealed centromere drift in C. deuterogattii, a previously unreported phenomenon in fungi. The CENP-A-binding shifted within the ORF-free regions and showed a possible association with a truncated transposable element. Taken together, our findings reveal that neocentromeres in C. deuterogattii are highly unstable and are not marked with an epigenetic memory, distinguishing them from native centromeres.

scholarly journals Brief Mating Behavior at Dawn and Dusk and Long Nocturnal Matings in the Butterfly Melanitis leda

2020 ◽  
Vol 33 (2-4) ◽  
pp. 138-147
Author(s):  
Freerk Molleman ◽  
Sridhar Halali ◽  
Ullasa Kodandaramaiah
Keyword(s):  
Mating System ◽  
Mating Behavior ◽  
South India ◽  
Territorial Defense ◽  
Warm Up ◽  
Male Territoriality ◽  
In Captivity ◽  
In The Wild ◽  
The Common ◽  
Insight Into

Abstract Information on the mating system of an insect species is necessary to gain insight into sexual selection and population structure. Male territoriality of the common evening brown butterfly Melanitis leda has been studied in the wild, but other aspects of its mating system remain largely unknown. For a population of M. leda in South India, we observed male-male and male-female interactions in captivity, measured mating duration and spermatophore mass, and also determined the degree of polyandry in the wild. We found that mating behavior takes place for short periods of time around dawn and dusk. Our observations corroborate that males compete in aerial combats (twirling) and interfere with mating pairs. In the morning, they may use shivering to warm up. Females can twirl with males and refuse mating by pointing their abdomens upwards or by flying away. Males court females by fluttering their wings while perched behind females, and then initiate copulation by curling their abdomens ca. 180 degrees sideways to make genital contact. While in the morning, matings lasted on average one hour and twenty-three minutes and never exceeded three hours, in the evening, matings could be of similar duration, but 42% of butterflies only separated when dawn was approaching. However, such long nocturnal matings did not result in heavier spermatophores. The first spermatophore of a male tended to be larger than subsequent spermatophores. Together with previous studies on this species, our findings suggest that males compete mainly through territorial defense (as reported before), courtship performance, and interference, and to a lesser extent by providing spermatophores, while females exert some control over the mating system by the timing of their receptivity and mate choice.

Oestrous cycle of the common wombat, Vombatus ursinus, in Victoria, Australia

2004 ◽  
Vol 16 (3) ◽  
pp. 339 ◽  
Author(s):  
M. West ◽  
D. Galloway ◽  
J. Shaw ◽  
A. Trouson ◽  
M. C. J. Paris
Keyword(s):  
Epithelial Cells ◽  
Average Length ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Vaginal Smears ◽  
Plasma Progesterone ◽  
In Captivity ◽  
Common Wombat ◽  
Vaginal Cytology ◽  
The Common

Wild-caught female common wombats from Victoria, Australia, were studied in captivity to investigate the oestrous cycle by assessing vaginal cytology and peripheral plasma progesterone concentrations. Eight wombats, five adults (21–29 kg) and three subadults (19–23 kg), which were held for between 2 weeks and 11 months did not cycle in captivity. Their progesterone concentrations were consistently low (≤6.9 nmol L–1) and vaginal smears contained predominantly superficial epithelial cells. Three wombats (21–27 kg), held in captivity for >1 year, regularly cycled (when bodyweights exceeded 23.5 kg). Information gathered from four consecutive cycles in each of these three wombats revealed a follicular phase with low progesterone concentrations (≤6.9 nmol L–1) and vaginal smears with a high percentage of superficial epithelial cells alternating with periods of high progesterone concentrations (range 41.6–123.8 nmol L–1) and smears in which parabasal–intermediate epithelial cells predominated. The average length of the monitored oestrous cycles was 47.2 days (35–60 days). The follicular phase lasted ~19 days and the luteal phase lasted ~28 days. In conclusion, wombats can cycle regularly in captivity even under conditions of intensive monitoring.

Care and Maintenance of the Common Vampire in Captivity

1961 ◽  
Vol 42 (4) ◽  
pp. 449 ◽  
Author(s):  
William A. Wimsatt ◽  
Anthony Guerriere
Keyword(s):  
In Captivity ◽  
The Common

scholarly journals Neocentromeres lack epigenetic memory and hallmarks of native centromeres in Cryptococcus deuterogattii

2020 ◽  
Author(s):  
Klaas Schotanus ◽  
Vikas Yadav ◽  
Joseph Heitman
Keyword(s):  
Dna Methylation ◽  
Transposable Element ◽  
Fungal Pathogen ◽  
Fusion Partner ◽  
Epigenetic Memory ◽  
Chromosome Fusion ◽  
Human Fungal Pathogen ◽  
Dna Modifications ◽  
Chromosome Fusions ◽  
Active Centromere

AbstractDeletion of native centromeres in the human fungal pathogen Cryptococcus deuterogattii leads to neocentromere formation. Native centromeres span truncated transposable elements, while neocentromeres span actively expressed genes. Neocentromeres in cen10Δ mutants are unstable and chromosome-chromosome fusions occur. After chromosome fusion, the neocentromere is silenced and the native centromere of the chromosome fusion partner remains as the sole active centromere. In the present study, the active centromere of a fused chromosome was deleted to investigate if epigenetic memory promoted re-activation of a silenced neocentromere. Our results show that the silenced neocentromere is not re-activated and instead a novel neocentromere forms directly adjacent to the deleted centromere of the fused chromosome. To explore the epigenetic organization of neocentromeres, we characterized the distribution of the heterochromatic histone modification H3K9me2 and 5mC DNA methylation. Native centromeres were enriched for both H3K9me2 and 5mC DNA methylation marks, while neocentromeres lacked these specific histone and DNA modifications. To study centromere dynamics, the actively expressed URA5 gene was introduced into a native centromere. Introduction of the URA5 gene led to loss of CENP-A from the native centromere, and a neocentromere formed directly adjacent to the native centromere location. Remarkably, the silenced native centromere remained enriched for heterochromatin, yet the integrated gene was expressed and devoid of H3K9me2. Analysis of multiple CENP-A distribution profiles revealed centromere drift in C. deuterogattii, a previously unknown phenomenon in fungi. The CENP-A-enriched region shifted within the pericentric regions, and a truncated transposable element in centromere 5 acted as a barrier between the CENP-A-associated regions of chromatin. Interestingly, this truncated transposable element was devoid of CENP-A binding or H3K9me2 modification and was instead marked by 5mC DNA methylation. Taken together, our findings reveal novel aspects about the epigenetic mechanisms that distinguish native centromeres and neocentromeres.

scholarly journals Whole-chromosome fusions in the karyotype evolution of Sceloporus (Iguania, Reptilia) are more frequent in sex chromosomes than autosomes

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200099
Author(s):  
Artem P. Lisachov ◽  
Katerina V. Tishakova ◽  
Svetlana A. Romanenko ◽  
Anna S. Molodtseva ◽  
Dmitry Yu. Prokopov ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Recombination Rate ◽  
Complex Analysis ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Synaptonemal Complex Analysis ◽  
Chromosome Fusions ◽  
Chromosome Formation ◽  
Pseudoautosomal Regions

Whole-chromosome fusions play a major role in the karyotypic evolution of reptiles. It has been suggested that certain chromosomes tend to fuse with sex chromosomes more frequently than others. However, the comparative genomic synteny data are too scarce to draw strong conclusions. We obtained and sequenced chromosome-specific DNA pools of Sceloporus malachiticus , an iguanian species which has experienced many chromosome fusions. We found that four of seven lineage-specific fusions involved sex chromosomes, and that certain syntenic blocks which constitute the sex chromosomes, such as the homologues of the Anolis carolinensis chromosomes 11 and 16, are repeatedly involved in sex chromosome formation in different squamate species. To test the hypothesis that the karyotypic shift could be associated with changes in recombination patterns, we performed a synaptonemal complex analysis in this species and in Sceloporus variabilis (2 n = 34). It revealed that the sex chromosomes in S. malachiticus had two distal pseudoautosomal regions and a medial differentiated region. We found that multiple fusions little affected the recombination rate in S. malachiticus . Our data confirm more frequent involvement of certain chromosomes in sex chromosome formation, but do not reveal a connection between the gonosome–autosome fusions and the evolution of recombination rate. 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)’.

scholarly journals Reconstruction of ancestral diploid karyotype and evolutionary trajectories leading to the formation of Camelina sativa chromosomes

2020 ◽  
Author(s):  
Zhikang Zhang ◽  
Fanbo Meng ◽  
Pengchuan Sun ◽  
Jiaqing Yuan ◽  
Ke Ge ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Karyotype Evolution ◽  
Camelina Sativa ◽  
End Joining ◽  
Chromosome Fusion ◽  
Evolutionary Trajectories ◽  
Chromosome Fusions ◽  
Circular Chromosomes ◽  
Insight Into ◽  
Lines Of Evidence

Abstract Background: Belonging to lineage Ⅰ of Brassicaceae, Camelina sativa is formed by two hybridizations of three species (three sub-genomes). The three sub-genomes were diverged from a common ancestor, likely derived from lineage Ⅰ (Ancestral Crucifer karyotype, ACK). The karyotype evolutionary trajectories of the C. sativa chromosomes are currently unknown. Here, we managed to adopt a telomere-centric theory proposed previously to explain the karyotype evolution in C. sativa. Results: By characterizing the homology between A. lyrate and C. sativa chromosomes, we inferred ancestral diploid karyotype of C. sativa (ADK), including 7 ancestral chromosomes, and reconstructed the karyotype evolutionary trajectories leading to the formation of C. sativa genome. The process involved 2 chromosome fusions. We found that sub-genomes Cs-G1 and Cs-G2 may share a closer common ancestor than Cs-G3. Together with other lines of evidence from Arabidopsis, we propose that the Brassicaceae plants, even the eudicots, follow a chromosome fusion mechanism favoring end-end joining of different chromosomes, rather than a mechanism favoring the formation circular chromosomes and nested chromosome fusion preferred by the monocots. Conclusions: The present work will contribute to understanding the structural and functional innovation of C. sativa chromosomes, providing insight into Brassicaceae karyotype evolution.

scholarly journals An updated explanation of ancestral karyotype changes and reconstruction of evolutionary trajectories to form Camelina sativa chromosomes

2020 ◽  
Author(s):  
Zhikang Zhang ◽  
Fanbo Meng ◽  
Pengchuan Sun ◽  
Jiaqing Yuan ◽  
Ke Ge ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Karyotype Evolution ◽  
Camelina Sativa ◽  
End Joining ◽  
Chromosome Fusion ◽  
Evolutionary Trajectories ◽  
Chromosome Fusions ◽  
Circular Chromosomes ◽  
Insight Into ◽  
Lines Of Evidence

Abstract Background: Belonging to lineage Ⅰ of Brassicaceae, Camelina sativa is formed by two hybridizations of three species (three sub-genomes). The three sub-genomes were diverged from a common ancestor, likely derived from lineage Ⅰ (Ancestral Crucifer karyotype, ACK). The karyotype evolutionary trajectories of the C. sativa chromosomes are currently unknown. Here, we managed to adopt a telomere-centric theory proposed previously to explain the karyotype evolution in C. sativa . Results: By characterizing the homology between A. lyrata and C. sativa chromosomes, we inferred ancestral diploid karyotype of C. sativa (ADK), including 7 ancestral chromosomes, and reconstructed the evolutionary trajectories leading to the formation of extant C. sativa genome. The process involved 2 chromosome fusions. We found that sub-genomes Cs-G1 and Cs-G2 may share a closer common ancestor than Cs-G3. Together with other lines of evidence from Arabidopsis, we propose that the Brassicaceae plants, even the eudicots, follow a chromosome fusion mechanism favoring end-end joining of different chromosomes, rather than a mechanism favoring the formation circular chromosomes and nested chromosome fusion preferred by the monocots. Conclusions: The present work will contribute to understanding the formation of C. sativa chromosomes, providing insight into Brassicaceae karyotype evolution.

scholarly journals Balancing under the high wire; a study into PTT antenna effects on the Common Guillemot Uria aalge

2016 ◽  
Author(s):  
Sylvie P Vandenabeele ◽  
Emily LC Shepard ◽  
Adam Grogan ◽  
Richard Thompson ◽  
Adrian C Gleiss ◽  
...  
Keyword(s):  
Uria Aalge ◽  
Common Guillemot ◽  
Critical Effect ◽  
In Captivity ◽  
First Results ◽  
The Common ◽  
The Impact

External tags fitted to diving birds can affect them in many ways with the most critical effect being an increase in drag. The effects of transmitters can be even more acute due to the presence of a protruding aerial. The study assesses the impact of PTT antenna on the behaviour and energetics of device-equipped guillemots (Uria aalge) in captivity. Birds with antenna-devices appeared to consume about 20% more energy than non-antenna birds during the descent phase of the dive. The balance of the birds while diving or resting on the water also appeared to be compromised by the presence of an antenna. Based on these first results and because transmitters are one of the most common methods used to track animals, it appears critical to determine what impact these devices, and particularly antenna, can have on their bearers and try minimize it.

A morphometric study of the gastrointestinal tract of the common brushtail possum in southern New Zealand.

2005 ◽  
Vol 27 (1) ◽  
pp. 61 ◽  
Author(s):  
A McDowell ◽  
BJ McLeod ◽  
EG Thompson ◽  
IG Tucker
Keyword(s):  
New Zealand ◽  
Diet Quality ◽  
Mucosal Surface ◽  
Morphometric Study ◽  
Brushtail Possum ◽  
Gi Tract ◽  
Average Mass ◽  
In Captivity ◽  
The Common ◽  
Common Brushtail Possum

The length and mass of sections of the gastrointestinal (GI) tract is reported for common brushtail possums (Trichosurus vulpecula) captured in the Otago region of New Zealand (n = 41). The pH of digesta (n = 12) and of the mucosal surface was also determined for specific sections of the GI tract of fed (n = 5) and fasted (n = 5) animals. Inter-animal variability in some morphometric characteristics was influenced by gender, live body mass, fur colour and time spent in captivity. Feeding significantly reduced the pH of the mucosal surface in the caecum only. GI tract morphology of T. vulpecula from southern New Zealand differs from that reported for Australian specimens, with average mass of the caecum in individuals from Otago being less than that of Australian specimens. Such differences in GI tract morphology may be due to improved diet quality in New Zealand compared with Australia.

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