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Journal of Genetics 2020is native to East and Southeast Asia and spread very fast around the world being considered an invasive pest species. Many demographic, population genetics and genomic...
is native to East and Southeast Asia and spread very fast around the world being considered an invasive pest species. Many demographic, population genetics and genomic studies have been recently developed, but so far no analysis has been carried out regarding the presence of chromosomal inversions in natural populations. In this research, we studied polytene chromosomes of flies collected from the Font Groga (Barcelona) population. The chromosomes and many of their segments were characterized for their similarity with those from . This is the report of one paracentric inversion (in heterozygous condition) in the right arm of the third chromosome (3R). As far as we know, it is the first time that an inversion has been observed in a natural population. Finally, the evolutionary significance of the finding of inversions in this species is discussed.
Topics: Animals; Centromere; Chromosome Inversion; Drosophila; Genetics, Population; Introduced Species; Karyotype; Polytene Chromosomes; Spain; Telomere
PubMed: 33361634
DOI: No ID Found -
Cells Nov 2020Dipterans exhibit a remarkable diversity of chromosome end structures in contrast to the conserved system defined by telomerase and short repeats. Within dipteran...
BACKGROUND
Dipterans exhibit a remarkable diversity of chromosome end structures in contrast to the conserved system defined by telomerase and short repeats. Within dipteran families, structure of chromosome termini is usually conserved within genera. With the aim to assess whether or not the evolutionary distance between genera implies chromosome end diversification, this report exploits two representatives of Sciaridae, , and .
METHODS
Probes and plasmid microlibraries obtained by chromosome end microdissection, in situ hybridization, cloning, and sequencing are among the methodological approaches employed in this work.
RESULTS
The data argue for the existence of either specific terminal DNA sequences for each chromosome tip in , or sequences common to all chromosome ends but their extension does not allow detection by in situ hybridization. Both sciarid species share terminal sequences that are significantly underrepresented in chromosome ends of .
CONCLUSIONS
The data suggest an unusual terminal structure in chromosomes compared to other dipterans investigated. A putative, evolutionary process of repetitive DNA expansion that acted differentially to shape chromosome ends of the two flies is also discussed.
Topics: Animals; Base Sequence; Chromosomes, Insect; DNA; Diptera; Gene Library; Microdissection; Plasmids; Polytene Chromosomes
PubMed: 33167604
DOI: 10.3390/cells9112425 -
Insects Oct 2020Polymorphic chromosomal inversions have been implicated in local adaptation. In anopheline mosquitoes, inversions also contribute to epidemiologically relevant...
Polymorphic chromosomal inversions have been implicated in local adaptation. In anopheline mosquitoes, inversions also contribute to epidemiologically relevant phenotypes such as resting behavior. Progress in understanding these phenotypes and their mechanistic basis has been hindered because the only available method for inversion genotyping relies on traditional cytogenetic karyotyping, a rate-limiting and technically difficult approach that is possible only for the fraction of the adult female population at the correct gonotrophic stage. Here, we focus on an understudied malaria vector of major importance in sub-Saharan Africa, . We ascertain and validate tag single nucleotide polymorphisms (SNPs) using high throughput molecular assays that allow rapid inversion genotyping of the three most common inversions at scale, overcoming the cytogenetic karyotyping barrier. These same inversions are the only available markers for distinguishing two ecotypes that differ in indoor resting behavior, Folonzo and Kiribina. Our new inversion genotyping tools will facilitate studies of ecotypic differentiation in and provide a means to improve our understanding of the roles of Folonzo and Kiribina in malaria transmission.
PubMed: 33065978
DOI: 10.3390/insects11100693 -
Saudi Journal of Biological Sciences Oct 2020The study presents data on the karyotype characteristics and features of chromosomal polymorphism of Keyl, 1961 (Diptera, Chironomidae) from seven natural populations...
The study presents data on the karyotype characteristics and features of chromosomal polymorphism of Keyl, 1961 (Diptera, Chironomidae) from seven natural populations of Caucasus (Northwest, Central and East Caucasus). We found 16 banding sequences in the Caucasian populations. We observed inversion polymorphism almost in all chromosome arms except for arms C and E. The genetic distances between all the studied populations of were calculated using Nei criteria (1972). In spite of relative geographic proximity, the genetic distances between populations of the Caucasus are quite big, and they do not form a single cluster of Caucasian populations. The population of the Northwest Caucasus goes to European cluster; the populations of Central and East Caucasus form their own separate clusters. The principal component analysis (PCA) shows the similar picture. We suggest that such a clear separation of Caucasian populations in distinct clusters is a result of differences of collection sites in terms of geography and climate (complex diverse terrain and microclimate conditions). Four of the Caucasian populations do not follow Hardy-Weinberg expectation. In two populations, there being a marked deficiency of heterozygotes in arms B, F and G. In two other populations, there being a marked excess of heterozygotes in arms B and G. One can suggest that observed pictures could be a reflection of multi-directional selection of heterozygotes in different populations. The populations of from different parts of the Caucasus possibly diverged from each other at the level of subspecies. All the obtained data are indicative of the complex genetic structure of Caucasian populations of and total complexity of microevolution processes occurring in the Caucasus region.
PubMed: 32994716
DOI: 10.1016/j.sjbs.2020.05.032 -
Environmental Science and Pollution... Jan 2021This study focuses on the Dombrovska pit lake, near the city of Kalush in Ukraine, which is a former potassium salt mine filled with brine and freshwater. The water...
Physicochemical characteristics of the Dombrovska pit lake (Ukraine) formed in an opencast potassium salt mine and the genome response of Chironomus salinarius Kieffer (Chironomidae, Diptera) to these conditions.
This study focuses on the Dombrovska pit lake, near the city of Kalush in Ukraine, which is a former potassium salt mine filled with brine and freshwater. The water level is still increasing and as a result the salinity is decreasing. We analyzed the benthic fauna communities and the genome instability by assessing the rearrangements in the polytene chromosomes of Chironomus salinarius and the physicochemical parameters of the near-bottom water (pH, conductivity, mineralization, major ions, NO, NH, metals Cd, Pb, Cu, Mn, and Fe) and sediment (pH, organic matter and metals Cd, Pb, Cu, Zn, Mn, and Fe) at four sites. The water mineralization ranged from 17.3 to 26.2 g dm which are classified as mesohaline and polyhaline waters, respectively. The biodiversity of the benthic fauna was low, and the dominant species was C. salinarius. The density of C. salinarius varied spatially and changed from 637 ind./m at a depth of 5 m to 8167 ind./m at a depth of 2.5 m. The genome instability was analyzed by examining the structural and functional changes in the salivary gland chromosomes of C. salinarius. The exposure of C. salinarius damaged the chromosomes and the activities of key structures, such as the Balbiani ring and nucleolar organizer, were partially or completely suppressed.
Topics: Animals; Chironomidae; Lakes; Larva; Metals, Heavy; Potassium; Ukraine; Water Pollutants, Chemical
PubMed: 32815011
DOI: 10.1007/s11356-020-10465-0 -
G3 (Bethesda, Md.) Sep 2020Chromosomal inversion polymorphisms have special importance in the complex of malaria vector mosquitoes, due to their role in local adaptation and range expansion. The...
Chromosomal inversion polymorphisms have special importance in the complex of malaria vector mosquitoes, due to their role in local adaptation and range expansion. The study of inversions in natural populations is reliant on polytene chromosome analysis by expert cytogeneticists, a process that is limited by the rarity of trained specialists, low throughput, and restrictive sampling requirements. To overcome this barrier, we ascertained tag single nucleotide polymorphisms (SNPs) that are highly correlated with inversion status (inverted or standard orientation). We compared the performance of the tag SNPs using two alternative high throughput molecular genotyping approaches traditional cytogenetic karyotyping of the same 960 individual and mosquitoes sampled from Burkina Faso, West Africa. We show that both molecular approaches yield comparable results, and that either one performs as well or better than cytogenetics in terms of genotyping accuracy. Given the ability of molecular genotyping approaches to be conducted at scale and at relatively low cost without restriction on mosquito sex or developmental stage, molecular genotyping via tag SNPs has the potential to revitalize research into the role of chromosomal inversions in the behavior and ongoing adaptation of and to environmental heterogeneities.
Topics: Africa, Western; Animals; Anopheles; Chromosome Inversion; Genotype; Malaria; Mosquito Vectors
PubMed: 32680855
DOI: 10.1534/g3.120.401418 -
Cells Jun 2020In salivary gland polytene chromosomes, a substantial portion of heterochromatin is underreplicated. The combination of mutations and results in the polytenization of...
In salivary gland polytene chromosomes, a substantial portion of heterochromatin is underreplicated. The combination of mutations and results in the polytenization of a substantial fraction of unique and moderately repeated sequences but has almost no effect on satellite DNA replication. The Rap1 interacting factor 1 (Rif) protein is a conserved regulator of replication timing, and in , it affects underreplication in polytene chromosomes. We compared the morphology of pericentromeric regions and labeling patterns of in situ hybridization of heterochromatin-specific DNA probes between wild-type salivary gland polytene chromosomes and the chromosomes of mutants and double mutants. We show that, despite general similarities, heterochromatin zones exist that are polytenized only in the mutants, and that there are zones that are under specific control of . In the mutants, we found additional polytenization of the largest blocks of satellite DNA (in particular, satellite 1.688 of chromosome X and simple satellites in chromosomes X and 4) as well as partial polytenization of chromosome Y. Data on pulsed incorporation of 5-ethynyl-2'-deoxyuridine (EdU) into polytene chromosomes indicated that in the mutants, just as in the wild type, most of the heterochromatin becomes replicated during the late S phase. Nevertheless, a significantly increased number of heterochromatin replicons was noted. These results suggest that regulates the activation probability of heterochromatic origins in the satellite DNA region.
Topics: Animals; Carrier Proteins; Drosophila Proteins; Drosophila melanogaster; Heterochromatin; Mutation; Polytene Chromosomes; Salivary Glands; Telomere-Binding Proteins
PubMed: 32575592
DOI: 10.3390/cells9061501 -
Genetics Aug 2020() is a naturally occurring male meiotic drive system in , characterized by almost exclusive transmission of the chromosome owing to dysfunction of sperm receiving the...
() is a naturally occurring male meiotic drive system in , characterized by almost exclusive transmission of the chromosome owing to dysfunction of sperm receiving the homolog. Previous studies identified at least three closely linked loci on chromosome required for distortion: , the primary distorting gene; (), which increases the strength of distortion; and (), the apparent target of Strength of distortion is also influenced by linked upward modifiers including () and (), and by various unlinked suppressors. Although is known to encode a mutant RanGAP protein, none of the modifiers have been molecularly identified. This work focuses on the genetic and cytological characterization of a strong -linked suppressor, , capable of restoring Mendelian transmission in males. and its cohort of positive modifiers appear to act semiquantitatively in opposition to with distortion strength depending primarily on the total number of distorting elements rather than which particular elements are present. can also suppress male sterility observed in certain genotypes. To facilitate its eventual molecular identification, was localized by deletion mapping to polytene region These studies highlight the polygenic nature of distortion and its dependence on a constellation of positive and negative modifiers, provide insight into the stability of Mendelian transmission in natural populations even when a drive system arises, and pave the way for molecular characterization of whose identity should reveal new information about the mechanism of distortion.
Topics: Animals; Chromosome Segregation; Crosses, Genetic; Drosophila melanogaster; Female; Infertility; Male; Meiosis; Mutation; Recombination, Genetic; Suppression, Genetic
PubMed: 32561521
DOI: 10.1534/genetics.120.303150 -
BMC Molecular and Cell Biology Mar 2020dADD1 and dXNP proteins are the orthologs in Drosophila melanogaster of the ADD and SNF2 domains, respectively, of the ATRX vertebrate's chromatin remodeler, they...
BACKGROUND
dADD1 and dXNP proteins are the orthologs in Drosophila melanogaster of the ADD and SNF2 domains, respectively, of the ATRX vertebrate's chromatin remodeler, they suppress position effect variegation phenotypes and participate in heterochromatin maintenance.
RESULTS
We performed a search in human cancer databases and found that ATRX protein levels were elevated in more than 4.4% of the samples analyzed. Using the Drosophila model, we addressed the effects of over and under-expression of dADD1 proteins in polytene cells. Elevated levels of dADD1 in fly tissues caused different phenotypes, such as chromocenter disruption and loss of banding pattern at the chromosome arms. Analyses of the heterochromatin maintenance protein HP1a, the dXNP ATPase and the histone post-translational modification H3K9me3 revealed changes in their chromatin localization accompanied by mild transcriptional defects of genes embedded in heterochromatic regions. Furthermore, the expression of heterochromatin embedded genes in null dadd1 organisms is lower than in the wild-type conditions.
CONCLUSION
These data indicate that dADD1 overexpression induces chromatin changes, probably affecting the stoichiometry of HP1a containing complexes that lead to transcriptional and architectural changes. Our results place dADD1 proteins as important players in the maintenance of chromatin architecture and heterochromatic gene expression.
Topics: Animals; Chromatin; Chromosomal Position Effects; Chromosomal Proteins, Non-Histone; DNA Helicases; Drosophila Proteins; Drosophila melanogaster; Gene Expression; Heterochromatin; Transcription Factors; X-linked Nuclear Protein
PubMed: 32293240
DOI: 10.1186/s12860-020-00257-2 -
Genes Apr 2020The polytene chromosomes are the best model for studying the genome organization during interphase. Despite of the long-term studies available on genetic organization...
The polytene chromosomes are the best model for studying the genome organization during interphase. Despite of the long-term studies available on genetic organization of polytene chromosome bands and interbands, little is known regarding long gene location on chromosomes. To analyze it, we used bioinformatic approaches and characterized genome-wide distribution of introns in gene bodies and in different chromatin states, and using fluorescent in situ hybridization we juxtaposed them with the chromosome structures. Short introns up to 2 kb in length are located in the bodies of housekeeping genes (grey bands or chromatin). In the group of 70 longest genes in the genome, 95% of total gene length accrues to introns. The mapping of the 15 long genes showed that they could occupy extended sections of polytene chromosomes containing band and interband series, with promoters located in the interband fragments ( chromatin). Introns ( and chromatin) in polytene chromosomes form independent bands, which can contain either both introns and exons or intron material only. Thus, a novel type of the gene arrangement in polytene chromosomes was discovered; peculiarities of such genetic organization are discussed.
Topics: Animals; Chromatin; Drosophila Proteins; Drosophila melanogaster; Genome; Introns; Polytene Chromosomes
PubMed: 32290448
DOI: 10.3390/genes11040417