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D M Glover

Publications and source records attributed to D M Glover.

At least 19 recordsLinked to original sources
PubMed1992

twine, a cdc25 homolog that functions in the male and female germline of Drosophila.

twine is the second homolog of the fission yeast gene cdc25 to be found in Drosophila. Both string and twine cDNAs can rescue a temperature-sensitive cdc25 mutation in fission yeast, but not a deletion. We detect the expression of string but not twine transcripts in the proliferating cells of newly cellularized embryos, in third instar larval brains, and in imaginal discs. Both genes are abundantly expressed in nurse cells during oogenesis, the maternal transcripts persisting throughout the syncytial stage of embryonic development. In the testis, twine transcripts are seen in the growing stage of premeiotic cysts. Analysis of a twine mutant suggests a requirement for the gene during oogenesis, during syncytial embryonic development, and for male meiosis. Meiosis does not occur in homozygous twine males, which produce cysts containing 16 rather than 64 spermatids.

Amino Acid Sequence↗
PubMed1992

Dodeca satellite: a conserved G+C-rich satellite from the centromeric heterochromatin of Drosophila melanogaster.

To identify sequences from the centromeric region, we have constructed a Drosophila melanogaster yeast artificial chromosome (YAC) library and screened it with purified DNA from the minichromosome Dp(1;f)1187 derived from the X chromosome. We describe the structure of one clone isolated in this way. This YAC is structurally unstable and contains tandemly repeated G+C-rich 11-mer and 12-mer units, which we call dodeca satellite. Most of this satellite is located near the centromere of an autosome. Cross-hybridizing sequences are found in the genomes of organisms as distant as Arabidopsis thaliana and Homo sapiens.

Animals↗
PubMed1992

Regulation of the G1-S transition in postembryonic neuronal precursors by axon ingrowth.

In the newly cellularized Drosophila embryo, progress through the cell cycle is regulated at the G2-M transition. We have examined cell-cycle regulation later in Drosophila development, in a group of postembryonic neuronal precursors. The S-phase precursor cells, which generate photoreceptor target neurons (lamina neurons) in the central nervous system, are not present in the absence of photoreceptor innervation. Here we report that axons selectively approach G1-phase precursors. Without axon ingrowth, lamina precursors do not enter their final S phase and by several criteria, arrest in the preceding G1 phase. These findings provide evidence that at this stage in development the control of cell division can occur at the G1-S transition.

Animals↗
PubMed1992

Cyclins A and B associate with chromatin and the polar regions of spindles, respectively, and do not undergo complete degradation at anaphase in syncytial Drosophila embryos.

Maternally contributed cyclin A and B proteins are initially distributed uniformly throughout the syncytial Drosophila embryo. As dividing nuclei migrate to the cortex of the embryo, the A and B cyclins become concentrated in surface layers extending to depths of approximately 30-40 microns and 5-10 microns, respectively. The initiation of nuclear envelope breakdown, spindle formation, and the initial congression of the centromeric regions of the chromosomes onto the metaphase plate all take place within the surface layer occupied by cyclin B on the apical side of the blastoderm nuclei. Cyclin B is seen mainly, but not exclusively, in the vicinity of microtubules throughout the mitotic cycle. It is most conspicuous around the centrosomes. Cyclin A is present at its highest concentrations throughout the cytoplasm during the interphase periods of the blastoderm cycles, although weak punctate staining can also be detected in the nucleus. It associates with the condensing chromosomes during prophase, segregates into daughter nuclei in association with chromosomes during anaphase, to redistribute into the cytoplasm after telophase. In contrast to the cycles following cellularization, neither cyclin is completely degraded upon the metaphase-anaphase transition.

Anaphase↗
PubMed1992

Molecular cloning and developmental expression of the catalytic and 65-kDa regulatory subunits of protein phosphatase 2A in Drosophila.

cDNA clones encoding the catalytic subunit and the 65-kDa regulatory subunit of protein phosphatase 2A (PR65) from Drosophila melanogaster have been isolated by homology screening with the corresponding human cDNAs. The Drosophila clones were used to analyze the spatial and temporal expression of the transcripts encoding these two proteins. The Drosophila PR65 cDNA clones contained an open reading frame of 1773 nucleotides encoding a protein of 65.5 kDa. The predicted amino acid sequence showed 75 and 71% identity to the human PR65 alpha and beta isoforms, respectively. As previously reported for the mammalian PR65 isoforms, Drosophila PR65 is composed of 15 imperfect repeating units of approximately 39 amino acids. The residues contributing to this repeat structure show also the highest sequence conservation between species, indicating a functional importance for these repeats. The gene encoding Drosophila PR65 was located at 29B1,2 on the second chromosome. A major transcript of 2.8 kilobase (kb) encoding the PR65 subunit and two transcripts of 1.6 and 2.5 kb encoding the catalytic subunit could be detected throughout Drosophila development. All of these mRNAs were most abundant during early embryogenesis and were expressed at lower levels in larvae and adult flies. In situ hybridization of different developmental stages showed a colocalization of the PR65 and catalytic subunit transcripts. The mRNA expression is high in the nurse cells and oocytes, consistent with a high equally distributed expression in early embryos. In later embryonal development, the expression remains high in the nervous system and the gonads but the overall transcript levels decrease. In third instar larvae, high levels of mRNA could be observed in brain, imaginal discs, and in salivary glands. These results indicate that protein phosphatase 2A transcript levels change during development in a tissue and in a time-specific manner.

Amino Acid Sequence↗
PubMed1992

3' non-translated sequences in Drosophila cyclin B transcripts direct posterior pole accumulation late in oogenesis and peri-nuclear association in syncytial embryos.

We have characterised forms of the Drosophila cyclin B transcript that differ as a result of a splicing event which removes a nucleotide segment from the 3' untranslated region. In oogenesis, both cyclin A RNA and a shorter form of the cyclin B transcript are seen in the cells of the germarium that are undergoing mitosis. The shorter cyclin B transcript alone is then detectable in the presumptive oocyte until stages 7-8 of oogenesis. Both cyclin A RNA and a longer form of the cyclin B RNA are then synthesised in the nurse cells during stages 9-11, to be deposited in the oocyte during stages 11-12. These transcripts become evenly distributed throughout the oocyte cytoplasm but, in addition, those of cyclin B become concentrated at the posterior pole. Examination of the distributions of RNAs transcribed from chimeric cyclin genes indicates that sequences in the 3' untranslated region of the larger cyclin B RNA are required both for it to become concentrated at the posterior pole and to direct those transcripts in the body of the syncytial embryo to their peri-nuclear localisation. These sequences are disrupted by the splicing event which generates smaller cyclin B transcripts.

Animals↗
PubMed1991

Low-resolution genome map of the malaria mosquito Anopheles gambiae.

We have microdissected divisions of the Anopheles gambiae polytene chromosomes, digested the DNAs with a restriction enzyme, and PCR-amplified the DNA fragments to generate a set of pooled probes, each corresponding to approximately 2% of the mosquito genome. These divisional probes were shown to have high complexity. Except for those derived from near the centromeres, they hybridize specifically with their chromosomal sites of origin. Thus, they can be used to map cloned DNAs by a dot blot procedure, which is much more convenient than in situ hybridization to polytene chromosomes. We discuss additional potential uses of these probes, such as easier isolation of molecular markers and genes, including those that cross-hybridize with clones available from other insects. It is expected that the probes will substantially accelerate molecular genetic analysis of this most important malaria vector.

Animals↗
PubMed1991

Molecular cloning and characterization of two voltage-gated K+ channel cDNAs from human ventricle.

K+ channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. In the heart these channels are responsible for the rapid repolarizing phases of the action potential and are the targets of several antiarrhythmic drugs. Full-length cDNA clones were isolated from human ventricular libraries that encode two voltage-gated K+ channels. These two cDNAs, designated HK1 and HK2, encode proteins of 653 and 605 amino acids, respectively. HK1 is the human equivalent (98% identity) of an inactivating K+ channel previously described in rat heart (RHK1) whereas the HK2 channel is 86% identical to a cloned rat brain K+ channel (Kv1). The only amino acid sequence identity (72%) between HK1 and HK2 is within the central region containing the membrane spanning domains. Northern blot analysis of human mRNA indicated that HK1 is slightly more abundant in ventricle than atrium whereas HK2 is much more abundant in atrium relative to ventricle. Both channel transcripts are present in ventricle at levels equivalent to voltage-gated Na+ channels. Analysis of the gene encoding HK1 suggests the coding sequence is intronless and is represented once in the human genome.

Amino Acid Sequence↗
PubMed1991

The major serum protein of Drosophila larvae, larval serum protein 1, is dispensable.

Null alleles of all three genes (alpha, beta and gamma) coding for the major serum protein of Drosophila larvae, larval serum protein 1, have been characterized at the protein level and by analysis of their RNA and DNA. Each allele completely lacks one polypeptide chain. beta shows an unaltered gene but reduced levels of RNA, alpha shows restriction-fragment-length polymorphism and shows low levels of transcript, while gamma is a deletion. The three null alleles have been combined to give a strain without the gene for larval serum protein 1 which survives.

Alleles↗
PubMed1991

Integrated maps of the Drosophila genome: progress and prospects.

A physical map of the Drosophila melanogaster genome is being assembled, consisting of ordered overlapping cosmid clones. The map is constructed in steps, separately for each chromosomal division. Gaps in this map are to be bridged with yeast artificial chromosome clones. Hybridization to previously cloned genes and extensive use of in situ hybridization to polytene chromosomes ensure that the cosmid map is firmly anchored to the wealth of available genetic and cytogenetic information. The intention is to make the physical map widely available as part of an overall, integrated genetic resource for the Drosophila research community.

Animals↗
PubMed1991

Mitosis in the Drosophila embryo--in and out of control.

Increasing levels of regulation act upon mitosis as the Drosophila embryo develops. The first 13 rapid cycles in the syncytial embryo rely on maternal gene products and lack feedback regulation to monitor the completion of S phase. Such regulation is introduced together with a G2 phase in cycle 14, and the network of universal mitotic regulators comes under the overall control of string, a cdc25 homologue, whose transcription is activated within mitotic domains.

Animals↗
PubMed1991

Source apportionment with site specific source profiles.

A receptor modeling study was performed to identify and apportion the sources of PM10 mass in Granite City, Illinois, an area of historic TSP nonattainment. Samples of the ambient aerosol were collected using a dichotomous sampler. Each sample was analyzed by x-ray fluorescence and instrumental neutron activation analysis. To begin the study, a factor analysis was performed. Two different chemical mass balance (CMB) analyses were then made. The first CMB analysis used only source profiles available from the literature while the second included twelve source profiles developed from dust samples collected in Granite City. Both CMB analyses used 20 of the 33 analyzed elements since many of the source profiles in the literature did not include the other thirteen elements. The results from both sets of CMB analyses were grouped by the predominate wind direction at the site during the time each sample was taken to identify the direction of each source relative to the sampler. It was found that regional sources were the primary contributors to the fine fraction while the coarse fraction was composed of material from local industries. These sources were generally the ones identified during the Regional Air Pollution Study previously conducted in the area. However, the emission profiles from these sources were observed to have changed between the studies. It was also found that the use of the locally generated profiles greatly improved the results of the CMB analysis.

Air↗
PubMed1991

Chromosome tangling and breakage at anaphase result from mutations in lodestar, a Drosophila gene encoding a putative nucleoside triphosphate-binding protein.

We describe a Drosophila maternal-effect gene, lodestar, mutations in which cause chromatin bridges at anaphase. lodestar maps to cytological position 84D13-14, and we identified the lodestar gene in germ-line transformation experiments by the ability of a genomic fragment to restore fertility to females homozygous for lodestar mutations. lodestar encodes a potential nucleoside triphosphate binding protein, which is a novel member of the D-E-A-H box family of proteins. Antibodies raised against the lodestar gene product detect a protein that undergoes cell cycle-dependent changes in distribution in the embryo. The protein is cytoplasmic at interphase, and rapidly enters the nucleus early in prophase. It is restricted to the region enclosed by the spindle envelope during metaphase and anaphase; but by telophase, the lodestar protein is contained entirely within the reforming nucleus.

Amino Acid Sequence↗
PubMed1991

polo encodes a protein kinase homolog required for mitosis in Drosophila.

We show that mutation in polo leads to a variety of abnormal mitoses in Drosophila larval neuroblasts. These include otherwise normal looking mitotic spindles upon which chromosomes appear overcondensed; normal bipolar spindles with polyploid complements of chromosomes; bipolar spindles in which one pole can be unusually broad; and monopolar spindles. We have cloned the polo gene from a mutant allele carrying a P-element transposon and sequenced cDNAs corresponding to transcripts of the wild-type locus. The sequence shows that polo encodes a 577-amino-acid protein with an amino-terminal domain homologous to a serine-threonine protein kinase. polo transcripts are abundant in tissues and developmental stages in which there is extensive mitotic activity. The transcripts show no obvious spatial pattern of distribution in relation to the mitotic domains of cellularized embryos but are specifically concentrated in dividing cells in larval discs and brains. In the cell cycles of both syncytial and cellularized embryos, the polo kinase undergoes cell cycle-dependent changes in its distribution: It is predominantly cytoplasmic during interphase; it becomes associated with condensed chromosomes toward the end of prophase; and it remains associated with chromosomes until telophase, whereupon it becomes cytoplasmic.

Amino Acid Sequence↗
PubMed1990

Towards a physical map of the Drosophila melanogaster genome: mapping of cosmid clones within defined genomic divisions.

A physical map of the D. melanogaster genome is being constructed, in the form of overlapping cosmid clones that are assigned to specific polytene chromosome sites. A master library of ca. 20,000 cosmids is screened with probes that correspond to numbered chromosomal divisions (ca. 1% of the genome); these probes are prepared by microdissection and PCR-amplification of individual chromosomes. The 120 to 250 cosmids selected by each probe are fingerprinted by Hinfl digestion and gel electrophoresis, and overlaps are detected by computer analysis of the fingerprints, permitting us to assemble sets of contiguous clones (contigs). Selected cosmids, both from contigs and unattached, are then localized by in situ hybridization to polytene chromosomes. Crosshybridization analysis using end probes links some contigs, and hybridization to previously cloned genes relates the physical to the genetic map. This approach has been used to construct a physical map of the 3.8 megabase DNA in the three distal divisions of the x chromosome. The map is represented by 181 canonical cosmids, of which 108 clones in contigs and 32 unattached clones have been mapped individually by in situ hybridization to chromosomes. Our current database of in situ hybridization results also includes the beginning of a physical map for the rest of the genome: 162 cosmids have been assigned by in situ hybridization to 129 chromosomal subdivisions elsewhere in the genome, representing 5 to 6 megabases of additional mapped DNA.

Animals↗