Showing papers on "Polytene chromosome published in 1999"
TL;DR: It is proposed that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure and together with human MSKs defines a separate family of tandem kinases.
184 citations
TL;DR: The end of a telomeric DNA sequence isolated from a polytene chromosome of a hypotrichous ciliate folds back and hybridizes with downstream telomersic sequence to form a t loop that is stable in the absence of protein and DNA cross-linking.
Abstract: The end of a telomeric DNA sequence isolated from a polytene chromosome of a hypotrichous ciliate folds back and hybridizes with downstream telomeric sequence to form a t loop that is stable in the absence of protein and DNA cross-linking The single-stranded, telomeric DNA sequence at the end of a macronuclear molecule does not form a t loop but, instead, is complexed with a heterodimeric, telomere-binding protein Thus, two mechanisms for capping the ends of DNA molecules are used in the same cell
170 citations
TL;DR: The sting mutation, caused by a P element inserted into polytene region 32D, was isolated by a screen for male sterile insertions in Drosophila melanogaster and was cloned and shown to code for a putative protein that is 866 amino acids long.
Abstract: The sting mutation, caused by a P element inserted into polytene region 32D, was isolated by a screen for male sterile insertions in Drosophila melanogaster. This sterility is correlated with the presence of crystals in spermatocytes and spermatids that are structurally indistinguishable from those produced in males carrying a deficiency of the Y-linked crystal (cry) locus. In addition, their morphology is needle-like in Ste+ flies and star-shaped in Ste flies, once again as observed in cry- males. The sti mutation leads to meiotic drive of the sex chromosomes, and the strength of the phenomenon is correlated with the copy number of the repetitive Ste locus. The same correlation is also true for the penetrance of the male sterile mutation. A presumptive sti null allele results in male sterility and lethal maternal effect. The gene was cloned and shown to code for a putative protein that is 866 amino acids long. A C-terminal domain of 82 amino acids is identified that is well conserved in proteins from different organisms. The gene is expressed only in the germline of both sexes. The interaction of sting with the Ste locus can also be demonstrated at the molecular level. While an unprocessed 8-kb Ste primary transcript is expressed in wild-type males, in X/Y homozygous sti males, as in X/Y cry- males, a 0.7-kb mRNA is produced.
154 citations
TL;DR: Observed changes in Drosophila nurse cell chromosomes suggest that euchromatin begins to condense during late S phase and that nurse cell polytene chromosome structure is controlled by regulating whether events characteristic of late S and M phase are incorporated or skipped within a given endocycle.
Abstract: Polytene chromosomes exhibit intricate higher order chromatin structure that is easily visualized due to their precisely aligned component strands. However, it remains unclear if the same factors determine chromatin organization in polyploid and diploid cells. We have analyzed one such factor, the cell cycle, by studying changes in Drosophila nurse cell chromosomes throughout the 10 to 12 endocycles of oogenesis. We find that nurse cells undergo three distinct types of endocycle whose parameters are correlated with chromosome behavior. The first four endocycles support complete DNA replication; poorly banded polytene euchromatin progressively condenses during the late S phases to produce blob-like chromosomes. During the unique fifth endocycle, an incomplete late S phase is followed by a mitosis-like state during which the 64C chromosomes dissociate into 32 chromatid pairs held together by unreplicated regions. All the subsequent endocycles lack any late S phase; during these cycles a new polytene chromosome grows from each 2C chromatid pair to generate 32-ploid polytene nuclei. These observations suggest that euchromatin begins to condense during late S phase and that nurse cell polytene chromosome structure is controlled by regulating whether events characteristic of late S and M phase are incorporated or skipped within a given endocycle.
152 citations
TL;DR: It is shown by transient transfection experiments with genes expressing wild-type and mutant forms of CHD1 that both the C and H domains are essential for its proper association with chromatin.
Abstract: CHD1, an M
r∼200,000 protein that contains a chromodomain (C), an ATPase/helicase-like domain (H) and a DNA-binding domain (D), was previously shown to be associated with decompacted interphase chromatin in mammalian cells and with transcriptionally active puffs and interbands in Drosophila polytene chromosomes. We now show by transient transfection experiments with genes expressing wild-type and mutant forms of CHD1 that both the C and H domains are essential for its proper association with chromatin. We also present evidence for an in vivo interaction between CHD1 and a novel HMG box-containing protein, SSRP1, which involves an amino-terminal segment of CHD1 that does not include the chromodomain. Immunocytochemical analyses indicated that CHD1 and SSRP1 colocalize in both mammalian nuclei and Drosophila polytene chromosomes.
137 citations
TL;DR: The results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators.
Abstract: In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each ;400 bp) contain both TRXand Polycomb-group response elements (TREs and PREs) and that in the context of the endogenous Ultrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (;90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group gene pleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators. Body segment identity in many organisms is achieved, in large part, through the activities of homeotic genes during development. In Drosophila, the establishment and maintenance of their patterns of expression are critical for the determination of the fates of embryonic cells. Two groups of genes, the trithorax group (trxG) (reviewed in reference 19) and the Polycomb group (PcG) (reviewed in references 3, 25, 29, and 38), play a predominant role in maintenance of the on and off states, respectively, of homeotic gene expression during development. It has been proposed that the products of different PcG genes assemble in a multimeric complex only at target genes that are not actively being transcribed, ostensibly locking these genes in an inactive state. This presumably imprints a determined state of the chromatin which could be inherited by the cellular progeny (25). Indeed, several Polycomb-group (PcG) proteins analyzed thus far colocalized at a large number of sites on salivary gland polytene chromosomes, suggesting that they often function together (11, 23, 33). Moreover, it was shown that the Polycomb (Pc) and polyhomeotic products are constituents of a large multimeric protein complex (15). Contrasting with PcG repression is activation by trxG genes. The trxG includes trithorax (trx), brahma (brm), Trithorax-like (Trl), ash1, ash2, and more than 10 additional members, many of which are only minimally characterized. The products of these genes function as transcriptional activators that sustain particular patterns of homeotic gene expression which act antagonistically to those of the PcG. It has been shown that in trx mutant embryos, expression of all bithorax complex (BX-C) genes and several Antennapedia complex (ANT-C) genes are affected in a tissue-, parasegment (PS)-, and promoter-specific fashion (4, 24, 36). Like PcG gene products, those of the trxG have been found at multiple sites on polytene chromosomes, suggesting that targets of these proteins are not limited to the genes of the homeotic complexes. Indeed, it was shown that the region-specific homeotic gene fork head is a direct target gene of trx based on Trithorax protein (TRX) binding on polytene chromosomes (21).
121 citations
TL;DR: The authors showed that the difference between these two morphs is due to variation at a single segregating factor located on the right arm of chromosome 3 near map position 51·5 and cytological position 87C-D. This is precisely the position of a desaturase gene previously sequenced using primers derived from yeast and mouse and localized by in situ hybridization to the polytene chromosomes of D. melanogaster.
Abstract: Drosophila melanogaster is polymorphic for the major cuticular hydrocarbon of females. In most populations this hydrocarbon is 7,11-heptacosadiene, but females from Africa and the Caribbean usually possess low levels of 7,11-heptacosadiene and high quantities of its position isomer 5,9-heptacosadiene. Genetic analysis shows that the difference between these two morphs is due to variation at a single segregating factor located on the right arm of chromosome 3 near map position 51·5 and cytological position 87C–D. This is precisely the position of a desaturase gene previously sequenced using primers derived from yeast and mouse, and localized by in situ hybridization to the polytene chromosomes of D. melanogaster . Alleles of this desaturase gene may therefore be responsible for producing the two hydrocarbon morphs. Mating tests following the transfer of these isomers between females of the two morphs show that, in contrast to previous studies, the hydrocarbon profiles have no detectable effect on mating behaviour or sexual isolation.
101 citations
TL;DR: Results suggest that TRX and ASH1 are components that interact either within trxG protein complexes or between complexes that act in close proximity on regulatory DNA to maintain Ubx transcription.
Abstract: Trithorax (TRX) and ASH1 belong to the trithorax group (trxG) of transcriptional activator proteins, which maintains homeotic gene expression during Drosophila development. TRX and ASH1 are localized on chromosomes and share several homologous domains with other chromatin-associated proteins, including a highly conserved SET domain and PHD fingers. Based on genetic interactions between trx and ash1 and our previous observation that association of the TRX protein with polytene chromosomes is ash1 dependent, we investigated the possibility of a physical linkage between the two proteins. We found that the endogenous TRX and ASH1 proteins coimmunoprecipitate from embryonic extracts and colocalize on salivary gland polytene chromosomes. Furthermore, we demonstrated that TRX and ASH1 bind in vivo to a relatively small (4 kb) bxd subregion of the homeotic gene Ultrabithorax (Ubx), which contains several trx response elements. Analysis of the effects of ash1 mutations on the activity of this regulatory region indicates that it also contains ash1 response element(s). This suggests that ASH1 and TRX act on Ubx in relatively close proximity to each other. Finally, TRX and ASH1 appear to interact directly through their conserved SET domains, based on binding assays in vitro and in yeast and on coimmunoprecipitation assays with embryo extracts. Collectively, these results suggest that TRX and ASH1 are components that interact either within trxG protein complexes or between complexes that act in close proximity on regulatory DNA to maintain Ubx transcription. The control of body segment identity in many organisms is achieved in large part by the activities of homeotic genes. In Drosophila, the combined activities of the transiently expressed segmentation genes initiate the pattern of expression of the homeotic genes at the blastoderm stage, and additional factors and mechanisms are required to preserve these patterns at later stages of development. Two groups of genes, the trithorax group (trxG) (reviewed in reference 12) and the Polycomb group (PcG) (reviewed in references 2, 18, and 24) play major roles in the maintenance of the active and the repressed state, respectively. It is thought that trxG and PcG proteins are assembled into multiprotein complexes, which function by maintaining either open or closed domains of chromatin structure. This chromatin association has been established for several trxG proteins. The yeast and human homologues of the Drosophila trxG proteins BRAHMA, SNR1, and MOIRA have been shown to be components of a 2-MDa yeast and human SWI-SNF chromatin remodeling complex (7, 17, 32), and a similar Drosophila complex was recently characterized (16). GAGA factor, a DNA binding protein encoded by the trxG gene Trithorax-like (10), is required for the function of another Drosophila chromatin remodeling complex, the NURF complex (30). These protein complexes possess ATP-dependent activities that facilitate the binding of other transcription fac
81 citations
TL;DR: The purification and characterization of DDP1, a single‐stranded DNA‐binding protein of high molecular mass that specifically binds the unstructured dodeca‐satellite C‐strand is presented and the results are discussed in view of the possible contribution of DNA structure to the structural organization of pericentric heterochromatin.
Abstract: The centromeric dodeca-satellite of Drosophila forms altered DNA structures in vitro in which its purinerich strand (G-strand) forms stable fold-back structures, while the complementary C-strand remains unstructured. In this paper, the purification and characterization of DDP1, a single-stranded DNA-binding protein of high molecular mass (160 kDa) that specifically binds the unstructured dodeca-satellite C-strand, is presented. In polytene chromosomes, DDP1 is found located at the chromocentre associated with the pericentric heterochromatin but its distribution is not constrained to the dodeca-satellite sequences. DDP1 also localizes to heterochromatin in interphase nuclei of larval neuroblasts. During embryo development, DDP1 becomes nuclear after cellularization, when heterochromatin is fully organized, being also associated with the condensed mitotic chromosomes. In addition to its localization at the chromocentre, in polytene chromosomes, DDP1 is also detected at several sites in the euchromatic arms co-localizing with the heterochromatin protein HP1. DDP1 is a multi-KH domain protein homologous to the yeast Scp160 protein that is involved in the control of cell ploidy. Expression of DDP1 complements a Δscp160 deletion in yeast. These results are discussed in view of the possible contribution of DNA structure to the structural organization of pericentric heterochromatin.
73 citations
TL;DR: Analysis of cosmid clones from chromosome 4, and elsewhere in the genome, revealed that the euchromatic locations of DINE-1 are almost exclusively confined to chromosome 4 and supports the contention that repeats accumulate in regions of diminished crossing over.
Abstract: The banded portion of chromosome 4 (the "dot" chromosome) in Drosophila melanogaster displays some properties of beta-heterochromatin, which is normally found within the centric domain of the chromosomes. The nature and distribution of repetitive elements on chromosome 4 could play a role in the establishment of this unusual chromatin configuration. We describe here one such element: a short, interspersed repetitive sequence named DINE-1. Determination of a consensus sequence for the element reveals that there are two conserved regions (A and B) separated by a highly variable spacer. The conserved sequences are approximately 400 bp long but degenerate at both ends, opening the possibility that a yet-to-be-discovered mother element may be present in the genome. DINE-1 bears few of the properties of the mammalian short interspersed elements (SINEs) to which it bears a superficial resemblance in size. It does not appear to be the product of reverse transcription and lacks any polymerase III promoter consensus. The elements are not flanked by target site duplications and their termini lack direct or inverted repeats, suggesting that they themselves are not transposable. Our analysis of cosmid clones from chromosome 4, and elsewhere in the genome, revealed that the euchromatic locations of DINE-1 are almost exclusively confined to chromosome 4. In situ hybridization of a DINE-1 probe to polytene chromosomes confirmed the preferential distribution along 4, in addition to its presence in the centric heterochromatin. This unusual genomic distribution of bias toward chromosome 4 is also seen in the sibling species, D. simulans, whose dot chromosomes exhibit poorly resolved polytene bands and lack crossing over during meiosis like those of D. melanogaster. However, the dot chromosome of D. virilis, which exhibits a well-defined banded structure on polytene chromosomes and can cross over, has only a single, discrete site of DINE-1 element hybridization. The presence of DINE-1 within these regions suggests a role in the heterochromatic nature of chromosome 4 in D. melanogaster and supports the contention that repeats accumulate in regions of diminished crossing over.
53 citations
TL;DR: The sequence of activation of the hormone-induced puffs conforms to a cascade pattern, and the nucleoli, Balbiani rings, and DNA puffs are specific types of active regions in the polytene chromosomes.
Abstract: Publisher Summary The interphase polytene chromosome is morphologically differentiated into tightly compacted (the chromomeric) and decompacted (the interchomomeric) regions, as the chromatid from telomere to telomere has the appearance of a string with threaded beads, the chromomeres. During the activation of transcription of genes located within chromomeres, the constituent material of a chromomere loosens and a large swelling, the puff, is formed. Study of the sequence of the appearance of puffs in the course of development and other experiments have led to the concept that hormones are involved in regulating puff activity. Thus, the sequence of activation of the hormone-induced puffs conforms to a cascade pattern. The nucleoli, Balbiani rings, and DNA puffs are specific types of active regions in the polytene chromosomes. Their morphology differs to a large extent from that of the usual puffs. The nucleolar organizer contains a gene block, organized in a complex manner and encoding ribosomal RNA. Balbiani rings are composed of numerous repetitive elements, and they encode RNA molecules of a giant size. The amplification of DNA takes place in the DNA puffs.
TL;DR: The isolation and characterization of the L82 gene corresponding to the extensively characterized late puff at 82F is reported here, a complex gene that spans at least 50 kb of genomic DNA, produces at least seven different nested mRNAs, and has homology to a novel gene family.
TL;DR: UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the D mXPDprotein is recruited intensively in the chromosomes as a response to DNA damage.
Abstract: The XPD/ERCC2/Rad3 gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair. Mutations in the XPD gene generate the cancer-prone syndrome, xeroderma pigmentosum, Cockayne’s syndrome, and trichothiodystrophy. XPD has a 5′- to 3′-helicase activity and is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. We present here the characterization of the Drosophila melanogaster XPD gene (DmXPD). DmXPD encodes a product that is highly related to its human homologue. The DmXPD protein is ubiquitous during development. In embryos at the syncytial blastoderm stage, DmXPD is cytoplasmic. At the onset of transcription in somatic cells and during gastrulation in germ cells, DmXPD moves to the nuclei. Distribution analysis in polytene chromosomes shows that DmXPD is highly concentrated in the interbands, especially in the highly transcribed regions known as puffs. UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the DmXPD protein is recruited intensively in the chromosomes as a response to DNA damage. This is the first time that the response to DNA damage by UV-light irradiation can be visualized directly on the chromosomes using one of the TFIIH components.
TL;DR: This is the first extensive sequence analysis of noncoding DNA from chromosome 4, and the distribution of the various repeats suggests its organization is similar to the beta-heterochromatic regions near the base of the major chromosome arms.
Abstract: Chromosome 4 from Drosophila melanogaster has several unusual features that distinguish it from the other chromosomes. These include a diffuse appearance in salivary gland polytene chromosomes, an absence of recombination, and the variegated expression of P-element transgenes. As part of a larger project to understand these properties, we are assembling a physical map of this chromosome. Here we report the sequence of two cosmids representing ∼5% of the polytenized region. Both cosmid clones contain numerous repeated DNA sequences, as identified by cross hybridization with labeled genomic DNA, BLAST searches, and dot matrix analysis, which are positioned between and within the transcribed sequences. The repetitive sequences include three copies of the mobile element Hoppel, one copy of the mobile element HB, and 18 DINE repeats. DINE is a novel, short repeated sequence dispersed throughout both cosmid sequences. One cosmid includes the previously described cubitus interruptus (ci) gene and two new genes: that a gene with a predicted amino acid sequence similar to ribosomal protein S3a which is consistent with the Minute(4)101 locus thought to be in the region, and a novel member of the protein family that includes plexin and met–hepatocyte growth factor receptor. The other cosmid contains only the two short 5′-most exons from the zinc-finger-homolog-2 (zfh-2) gene. This is the first extensive sequence analysis of noncoding DNA from chromosome 4. The distribution of the various repeats suggests its organization is similar to the β-heterochromatic regions near the base of the major chromosome arms. Such a pattern may account for the diffuse banding of the polytene chromosome 4 and the variegation of many P-element transgenes on the chromosome.
TL;DR: In this paper, the Drosophila homologue of human transcription factor AP-4 (dAP-4) was cloned and identified as one of these helix-loop-helix proteins.
TL;DR: Nine specific DNA probes from Ceratitis capitata have been mapped by in situ hybridization to the salivary gland polytene chromosomes of the olive fruit fly Bactrocera oleae, thus establishing molecular markers for the 5 autosomal chromosomes.
Abstract: Nine specific DNA probes (genomic or cDNA) from Ceratitis capitata have been mapped by in situ hybridization to the salivary gland polytene chromosomes of the olive fruit fly Bactrocera oleae, a ma...
TL;DR: The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus and a correlation with transcription was seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.
Abstract: The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus. The antibodies used were raised against a recombinant protein containing phylogenetically conserved motifs of reverse transcriptases and derived from an abundant non-LTR element previously identified in Chironomus. Immunoreactive protein was found in some telomeres, in a centromeric region, in a few interstitial bands and in Balbiani ring 3. The telomeric signal was probably dependent on transcription and increased dramatically when telomeric heat shock puffs were induced. A correlation with transcription was also seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.
TL;DR: The standard photographic maps of five blackfly species from northern Thailand were constructed from larval salivary gland polytene chromosomes and are described herein, although some banding sequences in chromosome arm IIIS show homology.
Abstract: The standard photographic maps of five blackfly species from northern Thailand : i.e., Simulium (Nevermannia) caudisclerum, S. (Simulium) fenestratum, S. (S.) nakhonense, S. (S.) rufibasis and S. (Montisimulium) sp. G were constructed from larval salivary gland polytene chromosomes and are described herein. All the five species have three pairs of chromosomes (2n=6) which are arranged from the longest to the shortest. Chromosome I of all species are metacentric while most of the chromosome II and III are submetacentric. The centromeric regions of all chromosomes of S. (S.) nakhonense and S. (S.) rufibasis were expanded whereas the heavy centromeric bands were presented in S. (N) caudisclerum, S. (S.) fenestratum and S. (M.) sp. G. The nucleolar organizer of S. (N.) caudisclerum, S. (S.) fenestratum, S. (S.) nakhonense and S. (M.) sp. G is situated near the centromeric band of chromosome I. On the other hand, S. (S.) rufibasis has the nucleolar organizer on chromosome II. The Balbiani ring and double bubble are located near the tip of short arm of chromosome III in all species except for S. (S.) fenestratum, in which they are detected on chromosome II. Moreover, two types of B chromosomes and pseudochromocenters were also found in some larvae of S. (S.) nakhonense. There are no inversion polymorphisms detected in wild populations of these species. The five Simulium species have specific and fixed standard banding sequences which are different among species, although some banding sequences in chromosome arm IIIS show homology.
TL;DR: The size and number of secretory granules in late larval salivary glands of Drosophila melanogaster have been related to interecdysial and early metamorphic development represented by well‐known puffs in polytene chromosomes.
TL;DR: The results suggest that both the CK2α and RAP74 subunits travel with the elongating pol II molecules along the DNA template during the entire transcription cycle, consistent with the possibility that in living Chironomus salivary gland cells, DRB interferes with the recruitment ofTFIIF, but not of TFIIH, to the promoter.
Abstract: In a previous report, we documented that a major portion of the nuclear protein kinase CK2α (CK2α) subunit does not form heterooligomeric structures with the β subunit, but it binds tightly to nuclear structures in an epithelial Chironomus cell line [1]. We report here that the CK2α, but not β, subunit is co-localized with productively transcribing RNA polymerase II (pol II) on polytene chromosomes of Chironomus salivary gland cells. Likewise, the RAP74 subunit of TFIIF, a potential substrate for CK2, is co-localized with pol II. The occupancies of chromosomes with the CK2α and RAP74 subunits are sensitive to DRB, an inhibitor of pol II-based transcription and the activity of CK2 and pol II carboxyl-terminal kinases. DRB alters the chromosomal distribution of the CK2α and RAP74 subunits: there is a time-dependent clearance from the chromosomes of CK2α and RAP74 subunits, which coincides in time the completion and release of preinitiated transcripts after addition of DRB. The results suggest that both the CK2α and RAP74 subunits travel with the elongating pol II molecules along the DNA template during the entire transcription cycle. No detectable re-association of CK2α and RAP74 with the promoters takes, however, place after the completion of the preinitiated transcripts in the presence of DRB. In contrast, the binding of hypophosporylated pol II and TFIIH to the active gene loci is not abolished by the DRB regimen. Our data are consistent with the possibility that in living Chironomus salivary gland cells, DRB interferes with the recruitment of TFIIF, but not of TFIIH, to the promoter by interference with the activity of the CK2α subunit enzyme and phosphorylation of RAP74 and thereby DRB blocks transcription initiation. (Mol Cell Biochem 191: 149–159, 1999)
TL;DR: The RRM protein NonA, an ubiquitous nuclear protein present in puffs on polytene chromosomes, has been immunopurified as a RNA-protein complex from Drosophila Kc cells and is enriched for certain protein encoding RNAs, notably, histone H3 and H4 RNA.
TL;DR: Analysis of polytene chromosomes was made from wild larvae collected from the four populations at Doi Inthanon National Park, Chiang Mai Province, northern Thailand suggesting the existence of two gene pools in this population of S. feuerborni.
Abstract: A standard photographic map of Simulium feuerborni (Diptera: Simuliidae) was constructed from larval salivary gland polytene chromosomes and is described herein. Analysis of polytene chromosomes was made from wild larvae collected from the four populations at Doi Inthanon National Park, Chiang Mai Province, northern Thailand. Simulium feuerborni has three pairs of chromosomes (2n = 6) which are arranged from the longest to the shortest. Chromosome I is metacentric while chromosomes II and III are submetacentric. A total of six simple paracentric inversions have been detected in these natural populations of S. feuerborni. These inversions (IS-1, IL-1, IIL-1, IIL-2, IIIS-1, IIIL-1) occurred in all chromosome arms except for the arm IIS. Significant deviation from Hardy-Weinberg equilibrium has been observed in inversion IIIL-1 at Hui Sai Luaeng suggesting the existence of two gene pools in this population. There is no indication of sex linkage associated with an inversion sequence in these populations. Thus...
Journal Article•
TL;DR: The Stil protein accumulates in the nucleus of all female germ cells throughout development, and is transiently expressed during early stages of male germline differentiation, and changes of Stil subnuclear localization during oogenesis suggest an association with chromatin.
Abstract: The Drosophila gene stand still (stil) encodes a novel protein required for survival, sexual identity and differentiation of female germ cells. Using specific antibodies, we show that the Stil protein accumulates in the nucleus of all female germ cells throughout development, and is transiently expressed during early stages of male germline differentiation. Changes of Stil subnuclear localization during oogenesis suggest an association with chromatin. Several mutant alleles, which are point mutations in the Stil N-terminal domain, encode proteins that no longer co-localized with chromatin. We find that Stil binds to many sites on polytene chromosomes with strong preference for decondensed chromatin. This localization is very similar to that of RNA polymerase II. We show that Stil is required for high levels of transcription of the ovarian tumor gene in germ cells. Expression of ovarian tumor in somatic cells can be induced by ectopic expression of Stil. Finally, we find that transient ubiquitous somatic expression of Stil results in lethality of the fly at all stages of development.
TL;DR: Anopheles annularis van der Wulp populations from 6 districts in India were cytologically examined and an ovarian nurse cell polytene chromosome map for 5 arms is presented, finding j1 inversion on arm 2 took as evidence for reproductive isolation between 2 populations.
Abstract: Anopheles annularis van der Wulp populations from 6 districts in India were cytologically examined An ovarian nurse cell polytene chromosome map for 5 arms is presented Nine inversions—w,i1, j1, and k1 on chromosome arm 2; j1 and z in arm 3; h1 and s1 on arm 4; and k on arm 5—were polymorphic in these populations In districts Shahjahanpur and Ghaziabad populations, for j1 inversion on arm 2, there were no heterozygotes This was taken as evidence for reproductive isolation between 2 populations The 2 were provisionally designated as species A and B, characterized respectively by +j1and j1 arrangements in chromosome arm 2 The other 4 populations were identified as species A
TL;DR: In this article, the region 20 of the polytene X chromosome of Drosophila melanogaster was studied in salivary glands (SG) and pseudonurse cells (PNC) of otu mutants.
Abstract: Region 20 of the polytene X chromosome of Drosophila melanogaster was studied in salivary glands (SG) and pseudonurse cells (PNC) of otu mutants. In SG chromosomes the morphology of the region strongly depends on two modifiers of position effect variegation: temperature and amount of heterochromatin. It is banded in XYY males at 25° C and β-heterochromatic in X0 males at 14° C, i.e. it shows dynamic transitions. In PNC chromosomes region 20 is not heterochromatic, but demonstrates a clear banding pattern. Some molecular markers of mitotic heterochromatin were localized by means of in situ hybridization on PNC chromosomes: DNA of the gene su(f) in section 20C, the nucleolar organizer and 359-bp satellite in 20F. The 359-bp satellite, which has been considered to be specific for heterochromatin of the mitotic X chromosome, was found at two additional sites on chromosome 3L, proximally to 80C. The right arm of the X chromosome in SG chromosomes was localized in the inversion In(1LR)pn2b: the telomeric HeT-A DNA and AAGAG satellite from the right arm are polytenized, having been relocated from heterochromatin to euchromatin.
TL;DR: It is concluded that the two hydrazine compounds studied are able to duplicate in Drosophila larvae the complex of qualitative biological effects that are a prerequisite for ecdysteroid hormones.
TL;DR: The DNA of three previously cloned interband regions of Drosophila melanogaster polytene chromosomes has been tested for the presence of matrix association regions (MAR), using the in vitro matrix‐binding assay of Cockerill and Garrard.
Abstract: The DNA of three previously cloned interband regions (85D9/D10, 86B4/B6, and 61C7/C8) of Drosophila melanogaster polytene chromosomes has been tested for the presence of matrix association regions (MAR), using the in vitro matrix-binding assay of Cockerill and Garrard. MARs were found in all three interband regions under study. These results are discussed in frames of a model postulating that interband regions of polytene chromosomes correspond to the chromosomal DNA loop borders, which can be identified in interphase nuclei using biochemical approaches.
TL;DR: It is proposed that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure, and Skeletor is a novel protein participating in structural nuclear remodeling during the cell cycle.
Abstract: Nuclear architecture is remodeled during interphase in response to changes in gene activity as well as to changing structural and functional requirements during cell division. Using the monoclonal antibody mAb2A, we have identified two proteins that appear to play important roles in these processes: JIL-1 is a tandem serine-threonine kinase implicated in the regulation of chromatin structure, whereas Skeletor is a novel protein participating in structural nuclear remodeling during the cell cycle. Antibody staining and live imaging of JIL-1-GFP transgenic flies show that JIL-1 localizes to the gene-rich interband regions of larval polytene chromosomes and is upregulated almost twofold on the hypertranscribed male X chromosome compared with autosomes. We propose that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure. The other mAb2A antigen, Skeletor, is distributed in a nuclear meshwork pattern that can be observed in stereo pair images to reorganize during the cell cycle to form a spindle-like structure at prometaphase that is distinct from the microtubule spindle apparatus. Taking advantage of the powerful molecular and genetic approaches offered in Drosophila, the study of these two proteins promises to yield new insight into what defines nuclear architecture at the molecular level and how its remodeling is regulated.
TL;DR: The Drosophila homologue of AP50, the medium chain of clathrin-associated protein complex AP-2, was identified and characterized from the Drosophile Expressed Sequence Tag database and its function is discussed.
Journal Article•
TL;DR: A method of microcloning, which involves microsurgical excision of chromosome fragments, DNA amplification by means of a polymerase chain reaction (PCR), and ligation of amplified products with plasmids, was employed in studying Drosophila polytene chromosomes for the first time.
Abstract: A method of microcloning, which involves microsurgical excision of chromosome fragments, DNA amplification by means of a polymerase chain reaction (PCR), and ligation of amplified products with plasmids, was employed in studying Drosophila polytene chromosomes for the first time. Clones of the DNA library thus obtained contained inserts varying in size from 0.1 to 0.5 kb. DNA sequencing of five clones of the library showed that pericentromeric heterochromatin contained the 176 and 297 retrotransposons; the ninja retrotransposon characteristic of D. simulans; and two Drosophila repetitive elements, ag and a12, the function of which remains unknown.