Polytene Chromosome Bands Research Articles

Polytene Chromosome Banding Pattern three Drosophila species from Bangladesh

Polytene Chromosome Banding Pattern three Drosophila species from Bangladesh

DIFFERENT PROTEIN GROUPS INVOLVED IN TRANSCRIPTION REGULATION IN GENES OF DEVELOPMENT AND HOUSEKEEPING IN <i>DROSOPHILA</i>

Antibodies to histone modifications and an insulator protein involved in the processes of transcription initiation and elongation are mapped in Drosophila polytene chromosomes. The CHRIZ protein (chromatin insulator) and H3K36me3 histone modification (RNA elongation) are detected only in the localization of housekeeping genes (interbands and gray bands of polytene chromosomes) and never in the regions of development genes (black bands and large puffs arising from them). Antibodies to H3S10P histone modification, which is associated with the initial elongation of the RNA strand during transcription, are found exclusively in small puffs, but not in housekeeping gene localization sites or large ecdysone-induced puffs, where housekeeping genes are localized. Antibodies to H4R3me2 histone modification (a co-repressor of the ecdysone receptor) are detected only in large α-induced puffs.

Conservative Protein RCC1 Is a New Component of Black Bands of <i>Drosophila</i> <i>melanogaster</i> Polytene Chromosomes

Previously, the RCC1 gene (Regulator of Chromosome Сondensation 1) was characterized, which is considered a regulator of chromosome condensation in the cell cycle. This gene encodes a nuclear protein whose amino acid sequence is highly conserved among all eukaryotes and consists of seven repeating units. We have shown that all the most prominent black bands of polytene chromosomes (about 250) and the chromocenter bind antibodies to this protein. We found that antibodies to the xenopus RCC1 protein specifically bind to the Drosophila and human RCC1 protein, while in Drosophila lines with under replication suppression, the relative amount of the RCC1 protein increases compared to the wild type.

The Chironomus species studied by Letha Karunakaran in Singapore, with a review of the status of selected South-East Asian Chironomus

In the 1960s Letha Karunakaran studied the chironomid fauna of Singapore but faced a lack of sufficiently detailed descriptions to enable identification of her material with any certainty. She recognized seven species of Chironomus (s.s) but sent me fixed larval material of only four of these which she tentatively identified as C. apicatus Johannsen 1932, C. costatus Johannsen 1932, C. javanus Kieffer 1924, and C. stupidus Johannsen 1932. She sent fixed larvae to me for confirmation of her identifications, but died before I was able to determine accurate identities from morphology alone. With additional comparative material, along with polytene chromosome banding patterns and DNA barcode sequence from the mitochondrial COI gene, the species have been identified as a form of C. flaviplumus (auct, not Tokunaga)(here called C. flaviplumus Type B), C. circumdatus Kieffer 1916, probably C. striatipennis Kieffer 1910, and Kiefferulus barbatitarsis (Kieffer 1911), respectively. The identification of one species as a form of C. flaviplumus required an assessment of the present state of knowledge of this species where the name has been applied to at least five different species. Determination of a valid name for this species is not currently possible. The confusion of species identification is an indication that there are a number of closely related species which constitute a “C. flaviplumus group”.

A new species of black fly, formerly cytoform C of the Simulium angulistylum complex (Diptera: Simuliidae), from a high mountain in northeastern Thailand.

Cytoform C, one of three cytoforms in the Simulium angulistylum Takaoka & Davies complex from a high mountain in northeastern Thailand was morphologically and molecularly investigated. All known life stages (larva, pupa, adult male and female except egg) were morphologically similar to, but distinguishable from S. angulistylum s. str. and S. isanense Takaoka, Srisuka & Saeung in the adults by the relative length of the fore and hind basitarsi and relative length of the tooth to the claw. It is also morphologically distinct from other species of the S. epistum species-group. Here, it is formally described as a new species, S. prayooki. Molecular genetic data based on mitochondrial cytochrome c oxidase subunit I (COI) also supported the morphological similarity between the new species and the two related known species (S. angulistylum s. str. and S. isanense) as phylogenetic analysis retrieved them all from a single clade and with a low level of interspecific genetic divergence (1.74%). This might possibly have resulted from incomplete lineage sorting as they are likely to share a recent common ancestor. Despite limitation of molecular genetic differentiation, the new species was distinctly different from two other cytoforms of S. angulistylum complex based on polytene chromosome banding patterns and ecology of the immature stages. Thus, this study highlights the necessity of using an integrated approach for fully understanding black fly biodiversity.

An analysis on the divergence of Chironomid spp. based on the study of 18S rRNA and polytene chromosome organization in the species revealing the role of environment on speciation

BackgroundNine species of Chironomus evolved throughout the world were measured for their divergence with regard to their DNA sequences concerning 18S rRNA since it is conserved for a specific species. With the advancement of the field of molecular evolution, cytogenetics requires further correlation between molecular architecture and morphological features of a species to compare amongst others to decipher their role in speciation. Therefore, divergence of DNA sequences of the Chironomus were compared with differences in the polytene chromosome features of most of the species under this investigation to evaluate underlying correlation among them, if any, to finally establish a novel method of molecular classification broadly applicable in cytogenetics studies.ResultsWhen Chironomus javanus Kieffer was considered as a reference organism, an in silico pair-wise alignment of sequences for the 18S rRNA gene regions of the other eight different species of the same genus exhibited nucleotide sequence homology ranging from 67 to 98%. This divergence of the species under consideration might be due to environmental impact causing alteration of nitrogenous bases probably due to mismatch pairing in DNA replication. This may be suggested as a cause of evolution of species in nature. A concomitant study on the polytene chromosome band patterns of majority of these species belonging to this series also indicated a divergence ranging from 10% to 30%.ConclusionsSequence analysis based on 18S rRNA of nine species of Chironomus under this investigation shows a similarity in the polytene chromosome organization in most of the Chironomid species of the series. Hence, molecular divergence in the species is consistent with cytological difference among Chironomid species. Therefore, molecular data based on 18S rRNA and cytological characters based on the polytene chromosome features of the Chironomid species may be useful for their taxonomical recognition. Moreover, variations concerning two aspects of this study may be correlated to their environmental distinctions.

Genes Containing Long Introns Occupy Series of Bands and Interbands In Drosophila melanogaster polytene Chromosomes.

The Drosophila melanogaster 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 lazurite chromatin). In the group of 70 longest genes in the Drosophila 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 (aquamarine chromatin). Introns (malachite and ruby 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.

Specific Features of the Cytogenetic Structure of the Population of Chironomus plumosus (L.) (Diptera, Chironomidae) in a Small Creek (Udmurt Republic, Russia)

Chromosomal polymorphism is investigated in samples of Chironomus plumosus L., (1758) (Diptera, Chironomidae) from a pond on the Chemoshur creek in Udmurtia for the first time. The pool of polytene chromosome banding sequences of this species includes 12 banding sequences forming 17 zygotic combinations. The pluF2 sequence is found with a high frequency of 0.17. The cytogenetic distance between the known populations is determined.

A cytogenetic photomap from ovarian nurse cell polytene chromosome of Anopheles stephensi (Diptera: Culicidae): a comparative study

Polytene chromosome banding patterns have long been used to infer the degree of relatedness among taxa and as a standard reference for locating genes, puffs, and inversion breakpoints of unique gene arrangements. Chromosome comparisons between the species over the time have shown organizational changes in patterns which have resulted in adaptive advantages. An attempt has been made to prepare chromosome map from the ovarian nurse cell of Anopheles (Cellia) stephensi Liston, and to re-evaluate the physical map of this species. The photomaps prepared, were compared with other available maps of the past for the same species. The images of the polytene chromosomes have been straightened and divided by numbered divisions and lettered subdivisions. Tentative inversion breakpoints occurring naturally and that recorded from different insecticide resistant strains of An. stephensi is described in the present map. Some of the re-arrangements acquired have been highlighted in the paper in view to provide an overview of the importance of cytogenetic maps to Anopheles biology and the concept of chromosome evolution.

Tethering of CHROMATOR and dCTCF proteins results in decompaction of condensed bands in the Drosophila melanogaster polytene chromosomes but does not affect their transcription and replication timing.

Instulator proteins are central to domain organization and gene regulation in the genome. We used ectopic tethering of CHROMATOR (CHRIZ/CHRO) and dCTCF to pre-defined regions of the genome to dissect the influence of these proteins on local chromatin organization, to analyze their interaction with other key chromatin proteins and to evaluate the effects on transcription and replication. Specifically, using UAS-GAL4DBD system, CHRO and dCTCF were artificially recruited into highly compacted polytene chromosome bands that share the features of silent chromatin type known as intercalary heterochromatin (IH). This led to local chromatin decondensation, formation of novel DHSes and recruitment of several “open chromatin” proteins. CHRO tethering resulted in the recruitment of CP190 and Z4 (PZG), whereas dCTCF tethering attracted CHRO, CP190, and Z4. Importantly, formation of a local stretch of open chromatin did not result in the reactivation of silent marker genes yellow and mini-white immediately adjacent to the targeting region (UAS), nor did RNA polII become recruited into this chromatin. The decompacted region retained late replicated, similarly to the wild-type untargeted region.

Taxonomic status of the black fly Prosimulium italicum Rivosecchi(Diptera: Simuliidae) based on genetic evidence.

The black fly Prosimulium italicum Rivosecchi, distributed in the Apennines and Sicily, was described as a subspecies of Prosimulium hirtipes (Fries), based on a few morphological details. It subsequently was considered conspecific with P. hirtipes and the name was synonymized. Analyses of polytene chromosome banding patterns and sequences of mitochondrial DNA (COI and COII) revealed deep genetic divergence between P. italicum from Italy and P. hirtipes from northern and central Europe and confirmed the species status of P. italicum. Populations of P. italicum either lack chromosomal inversion IS-9 or carry it as an X-chromosome polymorphism, whereas all analyzed populations of P. hirtipes (Slovakia, Sweden, England, and Scotland) are fixed for IS-9. The average K2P genetic distance was 3.7% between P. italicum and P. hirtipes from northern Europe (Sweden) and 4.3 % between P. italicum and P. hirtipes from central Europe (Slovakia). Cytogenetic analysis showed the presence of two cytoforms of P. hirtipes ('A' in Sweden and Slovakia and 'B' in England and Scotland) and two cytoforms of P. italicum ('A' in Sicily and 'B' in Campania and Basilicata), all of which differ in their sex chromosomes and autosomal polymorphisms, suggesting that P. hirtipes and P. italicum might each be a complex of cryptic species.

Chironomus strenzkei Fittkau, 1968 is a junior synonym of C. striatipennis Kieffer, 1910

Two species of Chironomus with essentially identical adult wing patterns, C. strenzkei and C. striatipennis, have been reported from Brazil. Specimens were collected from the same region in the Manaus area some 50 years apart. Morphological, cytological and DNA Barcode comparisons all confirm that these two species are inseparable on any of the characteristics studied. Moreover, for the mitochondrial COI region investigated, the sequences are completely identical, and polytene chromosome banding patterns are shared between C. strenzkei and C. striatipennis populations from Japan. I therefore argue that the former species must be a junior synonym of C. striatipennis. As a result of the synonymy, C. striatipennis now becomes a new record for California and North America, and hence has a Holarctic distribution. The DNA sequence comparisons suggest that the Brazilian population may have derived from China, rather than Korea as suggested previously, and that the Californian population may not have been introduced from South America, but could equally likely have come from Asia.

Tests of conspecificity for closely related black fly (Diptera: Simuliidae) species of the Simulium striatum group in Thailand.

Four black fly species of the Simulium striatum species group have been recorded in Thailand. These species are morphologically highly similar in all developmental stages except for the number and arrangement of the pupal gill filaments. In this study, we used multiple characters sources, including morphology, cytology, molecular biology and ecology, to test the hypothesis of conspecificity for S. quinquestriatum (Shiraki), S. nakhonense Takaoka & Suzuki and S. chiangmaiense Takaoka & Suzuki. A molecular study based on the cytochrome c oxidase subunit I (COI) was unable to separate these taxa. In contrast, the elongation complex protein 1 (ECP1) sequences clearly differentiate S. quinquestriatum from S. chiangmaiense and S. nakhonense. However, the latter two taxa could not be differentiated based on molecular DNA sequences. Simulium chiangmaiense and S. nakhonense are also similar in the larval habitat characteristics and have undifferentiated polytene chromosome banding patterns. Morphological examination of the number and arrangement of the pupal gill filaments found a number of intermediate forms. Therefore, S. chiangmaiense and S. nakhonense are apparently the same biological species that is polymorphic for the number and arrangement of gill filaments. Thus, we synonymized S. chiangmaiense with S. nakhonense.

Drosophila polytene chromosome bands formed by gene introns.

Genetic organization of bands and interbands in polytene chromosomes has long remained a puzzle for geneticists. It has been recently demonstrated that interbands typically correspond to the 5'-ends of house-keeping genes, whereas adjacent loose bands tend to be composed of coding sequences of the genes. In the present work, we made one important step further and mapped two large introns of ubiquitously active genes on the polytene chromosome map. We show that alternative promoter regions of these genes map to interbands, whereas introns and coding sequences found between those promoters correspond to loose grey bands. Thus, a gene having its long intron "sandwiched" between to alternative promoters and a common coding sequence may occupy two interbands and one band in the context of polytene chromosomes. Loose, partially decompacted bands appear to host large introns.

<span>Sporozoite Infection Rate and Identification of the Infective and Refractory Species of <i>Anopheles gambiae</i> (Giles) Complex</span>

The ability of Anopheles gambiae complex mosquitoes to transmit Plasmodium infection is known to be variable within sibling species of the complex with strains that cannot transmit the parasite. High sporozoite infection rate recorded showed that A. gambiae mosquitoes are potent malaria vectors in southwestern Nigeria. The aim of this study was to identify the infective and refractory strains of A. gambiae mosquitoes and to determine the sporozoite infection rate in this area. The infective strains were A. gambiae (sensu stricto) and A. arabiensis, while the refractory strains were A. gambiae (sensu stricto). However, ovarian polytene chromosome banding patterns could not be used to distinguish between the infective and refractory strains of A. gambiae (sensu stricto). This study showed that the refractory strains of Anopheles gambiae complex are present, but in low frequencies, in southwestern Nigeria, and that the sibling species of Anopheles gambiae (A. gambiae s.s. and A. arabiensis) are potent malaria vectors.

Bionomic aspects of the Anopheles subpictus species complex in Sri Lanka.

Anopheles subpictus Grassi s.l. (Diptera: Culicidae) functions as a secondary malaria vector to Anopheles culicifacies Giles s.l. (Diptera: Culicidae) in Sri Lanka. The taxon A. subpictus is reported to exist as a species complex comprising four sibling species (A-D) that can be differentiated through polytene chromosome banding patterns and stage-specific morphometric traits in India. Based on the morphological characteristics described for the Indian Subpictus Complex, the presence of all four sibling species has been described in Sri Lanka. As sibling species show distinct bio-ecological characteristics that are important for devising appropriate vector control measures, a study was carried out in six districts in the dry zone of Sri Lanka. The results confirm the presence of all four sibling species, with species C predominating in inland areas and species B in coastal areas. Species C and D were indoor-resting and indoor-feeding, while species B was outdoor-resting with no significant preference for indoor- or outdoor-resting. Species B showed distinct morphological variation in the ornamentation of wings and palpi. Blood meal analysis revealed that species B, C, and D can feed on humans as well as cattle. The differential bio-ecological traits shown by the members of the Subpictus Complex are important for developing appropriate vector control measures in Sri Lanka.

Bionomic aspects of the Anopheles subpictus species complex in Sri Lanka

Anopheles subpictus Grassi s.l. (Diptera: Culicidae) functions as a secondary malaria vector to Anopheles culicifacies Giles s.l. (Diptera: Culicidae) in Sri Lanka. The taxon A. subpictus is reported to exist as a species complex comprising four sibling species (A–D) that can be differentiated through polytene chromosome banding patterns and stage-specific morphometric traits in India. Based on the morphological characteristics described for the Indian Subpictus Complex, the presence of all four sibling species has been described in Sri Lanka. As sibling species show distinct bio-ecological characteristics that are important for devising appropriate vector control measures, a study was carried out in six districts in the dry zone of Sri Lanka. The results confirm the presence of all four sibling species, with species C predominating in inland areas and species B in coastal areas. Species C and D were indoor-resting and indoor-feeding, while species B was outdoor-resting with no significant preference for indoor- or outdoor-resting. Species B showed distinct morphological variation in the ornamentation of wings and palpi. Blood meal analysis revealed that species B, C, and D can feed on humans as well as cattle. The differential bio-ecological traits shown by the members of the Subpictus Complex are important for developing appropriate vector control measures in Sri Lanka.

Universal intracellular transducer ras and its role in the development of drosophila

Ras genes were first identified in the 1960s as transforming oncogenes that caused tumors in rats infected with Harvey and Kirsten sarcoma viruses (Ha-ras and Ki-ras oncogenes, accordingly). Subsequently, transforming ras genes were found in human cancer cells. Further investigations of neuroblastoma cells resulted in the finding of the third ras gene in the human, which was called N-ras. Ras gene products play an important role in the processes of cellular proliferation and differentiation and are controlled by receptor tyrosine kinases. Using drosophila as a model object allowed us to perform a successful genetic analysis while studying the functions of ras genes. Three polytene chromosome bands were detected in D. melanogaster with the help of the v-Ha ras sampling. According to Bridges' map, all three bands (Dras1, Dras2, Dras3) were mapped to regions 85D, 64B, and 62B of chromosome 3. Among them, only Drasl has a common origin with ras genes of mammals. Although there are numerous investigations of the role played by ras genes in the de- velopment of insects, this problem is still not fully understood. The importance of ras gene variations in the course of the evolutionary process has been insufficiently studied as well. Currently, Ras target proteins are actively identified, their signal pathways, as well as effects of influencing these pathways in the drosophila tissues, are studied in the cells of yeast and mammals. The main functions of Ras protein is in the signaling pathways controlling mutations during drosophila's morphogenesis and the connections of ras gene with phenotypic symptoms of tumors.

Complexity decompositions in the problem of comparison of polytene chromosome banding sequences

Complexity decompositions in the problem of comparison of polytene chromosome banding sequences

Complexity decompositions in the problem of comparison of polytene chromosome banding sequences

The computation aspects of the problem of phylogenetic tree construction based on unique data of polytene chromosome banding sequences were considered. The possibilities of exact and approximate calculation of inversion distances were researched. The phylogenetic trees of relationships between 65 species of genus Chironomus (non-biting midge) were built and analyzed.