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Cells Oct 2021Although heterochromatin makes up 40% of the genome, its organization remains little explored, especially in polytene chromosomes, as it is virtually not represented in...
Although heterochromatin makes up 40% of the genome, its organization remains little explored, especially in polytene chromosomes, as it is virtually not represented in them due to underreplication. Two all-new approaches were used in this work: (i) with the use of a newly synthesized line that carries three mutations, , and , suppressing the underreplication of heterochromatic regions, we obtained their fullest representation in polytene chromosomes and described their structure; (ii) 20 DNA fragments with known positions on the physical map as well as molecular genetic features of the genome (gene density, histone marks, heterochromatin proteins, origin recognition complex proteins, replication timing sites and satellite DNAs) were mapped in the newly polytenized heterochromatin using FISH and bioinformatics data. The borders of the heterochromatic regions and variations in their positions on arm 3L have been determined for the first time. The newly polytenized heterochromatic material exhibits two main types of morphology: a banding pattern (locations of genes and short satellites) and reticular chromatin (locations of large blocks of satellite DNA). The locations of the banding and reticular polytene heterochromatin was determined on the physical map.
Topics: Animals; Antibodies; Carrier Proteins; Chromosomal Proteins, Non-Histone; DNA Replication; DNA-Binding Proteins; Drosophila Proteins; Drosophila melanogaster; Genes, Essential; Genome, Insect; Guanine Nucleotide Exchange Factors; Heterochromatin; Histones; Introns; Models, Biological; Mutation; Nuclear Proteins; Polytene Chromosomes; Protein Processing, Post-Translational; Repetitive Sequences, Nucleic Acid; Replication Origin; Repressor Proteins
PubMed: 34831030
DOI: 10.3390/cells10112809 -
Open Biology Nov 2021Gap junctions mediate communication between adjacent cells and are fundamental to the development and homeostasis in multicellular organisms. In invertebrates, gap...
Gap junctions mediate communication between adjacent cells and are fundamental to the development and homeostasis in multicellular organisms. In invertebrates, gap junctions are formed by transmembrane proteins called innexins. Gap junctions allow the passage of small molecules through an intercellular channel, between a cell and another adjacent cell. The dipteran has contributed to studying the biology of invertebrates and the study of the interaction and regulation of genes during biological development. Therefore, this paper aimed to study the innexin-2 by molecular characterization, analysis of the expression profile and cellular localization. The molecular characterization results confirm that the message is from a gap junction protein and analysis of the expression and cellular localization profile shows that innexin-2 can participate in many physiological processes during the development of .
Topics: Animals; Chromosome Mapping; Computational Biology; Connexins; Gene Expression Regulation, Developmental; Insect Proteins; Models, Molecular; Nematocera; Polytene Chromosomes; Protein Conformation; Sequence Analysis, DNA; Tissue Distribution
PubMed: 34753320
DOI: 10.1098/rsob.210224 -
Journal of Genetics 2021Early genetic studies with revealed similar mutant phenotypes for many X-linked genes, in males with one and in females with two copies of the mutant allele following...
Early genetic studies with revealed similar mutant phenotypes for many X-linked genes, in males with one and in females with two copies of the mutant allele following the XY/XX mode of sex determination. These observations led to evocation of the phenomenon of dosage compensation. By the 1960s, contrasting theories were advanced by H. J. Muller and R. B. Goldschmidt to explain the equalized expression of many X-linked genes despite their dosage difference in male and female flies. Evidence from genetic studies led Muller to propose existence of many modifiers whose action on individual X-linked genes resulted, through a 'piecemeal' regulation, in equalized expression of the dosage compensated X-linked genes, while Goldschmidt believed that invocation of multiple modifiers or compensators was unnecessary since dosage compensation was a direct outcome of the sex-specific physiologies of male and female flies. Muller did not agree with some cytological studies that suggested that the single X-chromosome in male cells works twice as hard as each of the two X-chromosomes in female cells (hyperactive male X model), but preferred partial repression of each X-chromosome in female flies. This historical perspective relates these divergent theories with my own doctoral work in A. S. Mukherjee's laboratory at Calcutta University, which, while ruling out Golschmidt's sex-physiology theory, established cell-autonomous regulation of the earlier proposed hyperactivity of the single X in male in a piecemeal manner.
Topics: Animals; Chromosomes, Insect; Dosage Compensation, Genetic; Drosophila; Female; Genes, X-Linked; Genetics; History, 20th Century; India; Male; Models, Genetic; Polytene Chromosomes; X Chromosome
PubMed: 34622796
DOI: No ID Found -
Scientific Reports Oct 2021The inverse dosage effect caused by chromosome number variations shows global consequences in genomic imbalance including sexual dimorphism and an X chromosome-specific...
The inverse dosage effect caused by chromosome number variations shows global consequences in genomic imbalance including sexual dimorphism and an X chromosome-specific response. To investigate the relationship of the MSL complex to genomic imbalance, we over-expressed MSL2 in autosomal and sex chromosomal aneuploids, and analyzed the different transcriptomes. Some candidate genes involved in regulatory mechanisms have also been tested during embryogenesis using TSA-FISH. Here we show that the de novo MSL complex assembled on the X chromosomes in females further reduced the global expression level on the basis of 2/3 down-regulation caused by the inverse dosage effect in trisomy through epigenetic modulations rather than induced dosage compensation. Plus, the sexual dimorphism effect in unbalanced genomes was further examined due to the pre-existing of the MSL complex in males. All these results demonstrate the dynamic functions of the MSL complex on global gene expression in different aneuploid genomes.
Topics: Aneuploidy; Animals; Computational Biology; DNA-Binding Proteins; Drosophila; Drosophila Proteins; Ectopic Gene Expression; Female; Gene Expression Profiling; Gene Expression Regulation; Gene Regulatory Networks; Male; Multiprotein Complexes; Polytene Chromosomes; Sex Characteristics; Transcription Factors; X Chromosome
PubMed: 34608252
DOI: 10.1038/s41598-021-99268-y -
Vavilovskii Zhurnal Genetiki I Selektsii Sep 2021Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D...
Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 - LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams-Beuren Syndrome (WBS): a mutant of the locus (X:11AB) harboring the gene. The mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between and the wild type strain are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior.
PubMed: 34595370
DOI: 10.18699/VJ21.054 -
Insects Sep 2021By any measure, such as abundance, species diversity or geographic range, the species group is one of the most successful Palearctic taxa of black flies. To explore...
By any measure, such as abundance, species diversity or geographic range, the species group is one of the most successful Palearctic taxa of black flies. To explore potential diversity in this group in the Tian Shan range of Central Asia, we focused on Kyrgyzstan, in which three nominal morphospecies have been recorded. Among our samples, we morphologically identified Rubtsov and a second possible species tentatively identified as Rubtsov. By analyzing banding patterns of the larval polytene chromosomes, we discovered two fixed inversions, two sex-linked rearrangements, and 19 autosomal rearrangements, including supernumerary B chromosomes. The chromosomal data indicate minimal diversity of only one or two species across the surveyed area of nearly 50,000 km. Mitochondrial DNA (CO1) sequences fell into three distinct clusters, possibly representing separate species. The chromosomal, molecular, and morphological data indicate that Kyrgyz populations are unique within the group, but the data sets are not entirely congruent. Thus, reconciling data sets and assigning existing names is tentative. is linked with undifferentiated sex chromosomes, one of the three CO1 clades, and higher elevations, whereas is tenuously associated with differentiated sex chromosomes, a separate CO1 clade, and lower elevations. These associations leave one Kyrgyz larva, which is in a third CO1 clade, unlinked to a formal species name. Our analyses also indicate that Meigen , contrary to previous reports, does not occur in Kyrgyzstan and should be deleted from the country's faunal list.
PubMed: 34564256
DOI: 10.3390/insects12090817 -
Journal of Visualized Experiments : JoVE Aug 2021Visualization of heterochromatin aggregates by immunostaining can be challenging. Many mammalian components of chromatin are conserved in Drosophila melanogaster....
Visualization of heterochromatin aggregates by immunostaining can be challenging. Many mammalian components of chromatin are conserved in Drosophila melanogaster. Therefore, it is an excellent model to study heterochromatin formation and maintenance. Polytenized cells, such as the ones found in salivary glands of third instar D. melanogaster larvae, provide an excellent tool to observe the chromatin amplified nearly a thousand times and have allowed researchers to study changes in the distribution of heterochromatin in the nucleus. Although the observation of heterochromatin components can be carried out directly in polytene chromosome preparations, the localization of some proteins can be altered by the severity of the treatment. Therefore, the direct visualization of heterochromatin in cells complements this type of study. In this protocol, we describe the immunostaining techniques used for this tissue, the use of secondary fluorescent antibodies, and confocal microscopy to observe these heterochromatin aggregates with greater precision and detail.
Topics: Animals; Chromosomes; Drosophila; Drosophila Proteins; Drosophila melanogaster; Heterochromatin; Salivary Glands; Staining and Labeling
PubMed: 34487109
DOI: 10.3791/62408 -
International Journal of Molecular... Aug 2021Chromatin 3D structure plays a crucial role in regulation of gene activity. Previous studies have envisioned spatial contact formations between chromatin domains with...
Chromatin 3D structure plays a crucial role in regulation of gene activity. Previous studies have envisioned spatial contact formations between chromatin domains with different epigenetic properties, protein compositions and transcription activity. This leaves specific DNA sequences that affect chromosome interactions. The polytene chromosomes are involved in non-allelic ectopic pairing. The mutant strain , a model for Williams-Beuren syndrome, has an increased frequency of ectopic contacts (FEC) compared to the wild-type strain (). Ectopic pairing can be mediated by some specific DNA sequences. In this study, using our Homology Segment Analysis software, we estimated the correlation between FEC and frequency of short matching DNA fragments (FMF) for all sections of the X chromosome of and strains. With fragment lengths of 50 nucleotides (nt), showed a specific FEC-FMF correlation for 20% of the sections involved in ectopic contacts. The correlation was unspecific in , which may indicate the alternative epigenetic mechanisms affecting FEC in the mutant strain. Most of the fragments that specifically contributed to FMF were related to 1.688 or 372-bp middle repeats. Thus, middle repetitive DNA may serve as an organizer of ectopic pairing.
Topics: Animals; Base Pairing; Chromatin; Computational Biology; DNA, Satellite; Disease Models, Animal; Drosophila melanogaster; Humans; Polytene Chromosomes; Software; Williams Syndrome; X Chromosome
PubMed: 34445413
DOI: 10.3390/ijms22168713 -
Doklady. Biochemistry and Biophysics Jul 2021Proteins MSL1 and MSL2 form the core of the Drosophila dosage compensation complex, which specifically binds to the X chromosome of males. Phosphorylation of certain...
Proteins MSL1 and MSL2 form the core of the Drosophila dosage compensation complex, which specifically binds to the X chromosome of males. Phosphorylation of certain amino acid residues was previously shown to regulate MSL1 activity. In the present work, transgenic lines of Drosophila expressing mutant variants of the MSL1 protein were obtained, in which amino acids undergoing phosphorylation were replaced. As a result, it was shown that inactivation of phosphorylation sites does not affect the efficiency of specific binding of the dosage compensation complex to the X chromosome of males and its functional activity.
Topics: Animals; Dosage Compensation, Genetic; Drosophila Proteins; Drosophila melanogaster; Mutation; Phosphorylation; X Chromosome
PubMed: 34426916
DOI: 10.1134/S1607672921040025 -
Planta Aug 2021During antipodal cells PCD, polytene chromosomes rearrangement, segregation of nucleoli components and extrusion of nuclear components occur, cytochrome c is released...
During antipodal cells PCD, polytene chromosomes rearrangement, segregation of nucleoli components and extrusion of nuclear components occur, cytochrome c is released from the mitochondria and DNA breaks appear. We studied in detail the nuclei of cells of the antipodal complex of wheat embryo sac (Triticum aestivum L.) during programmed cell death (PCD). The antipodal complex has been reported to be formed before double fertilisation of the embryo sac. Polyploidisation leads to the formation of giant polytene chromosomes in the nuclei of antipodal cells. These chromosomes are involved in secretory functions and are important for the development of cellular endosperm. Terminal deoxynucleotidyl transferase dUTP nick end labelling assay and immunodetection revealed DNA breaks in the nuclei and release of cytochrome c from mitochondria into the cytoplasm of antipodal cells during PCD. We used transmission electron microscopy, immunodetection and histochemistry to analyse the characteristic structural changes in the nuclei of antipodal cells during PCD. These included sequential structural changes in the nuclei containing polytene chromosomes, segregation of some components of the nucleolus into the bodies of polytene chromosomes, extrusion of nucleolar components and parts of chromosomes into the cytoplasm of antipodal cells and then into the endosperm coenocyte. The obtained results expand the understanding of the structural changes of plant cells with giant polytene chromosomes during PCD.
Topics: Apoptosis; Cell Nucleus; Endosperm; Mitochondria; Triticum
PubMed: 34379202
DOI: 10.1007/s00425-021-03701-5