Drosophila headlines.

Recent genetic and molecular data from Drosophila support the long-standing observations of morphology in suggesting that segmentation of the insect embryo proceeds in two phases. Organization of the cephalic segments uses a mechanism distinct from the familiar bierarchical cascade of segmentation genes that subdivides the trunk of the embryo.     

Drosophila microarray platforms.

The advent of high throughput microarrays and the complete sequencing of the Drosophila melanogaster genome have enabled global gene expression analysis in this powerful genetic model organism. Currently, researchers are using three main Drosophila array platform types, with elements composed of cDNA amplicons, oligonucleotides (short and long) or genomic amplicons. This paper provides a broad overview of these platforms.     

Insertional mutagenesis in Drosophila. II. P element mediated transformation of Drosophila yakuba.

Drosophila yakuba, a member of melanogaster subgroup being free of P element, acquired resistance to an antibiotic neomycin by the transformation utilizing P element. In this species, the transformation frequency was comparable to that of D. melanogaster. Further, the occurrence of 8 base pairs duplication upon the insertion of the element was confirmed. These facts suggest that the P element could be inserted into the genome in the same manner, even in D. yakuba. Any consensus for preferential insertion could not be found on the nucleotide sequence as in D. melanogaster. However, it is noticeable that a series of the short palindromic stretches was common around the insertion sites in both species. It suggests that a structural feature of DNA plays a role as a landmark for P element insertion.     

Proteomics in Drosophila melanogaster.

To be able to understand cellular mechanisms, we require fully integrated data sets combining information about gene expression, protein expression, post-translational modification states, sub-cellular location and complex formation. Proteomics is a very powerful technique that can be applied to interrogate changes at the protein level. Studying this effectively requires specialised facilities within research institutes. Here, we describe the setting up and operation of such a facility, providing a resource for the Arabidopsis and Drosophila research communities.     

Drosophila MCM protein complexes.

MCM genes encode a family of evolutionarily conserved proteins required for DNA replication. In Saccharomyces cerevisiae, where they were first identified, MCM genes interact genetically with each other. Allele specificity in these interactions suggests that MCM proteins physically associate with one another and that this association is essential for function. We describe here an analysis of physical interactions among three Drosophila MCM proteins. Using specific antibodies we detect Drosophila MCMs almost exclusively in 600-kDa protein complexes. Co-immunoprecipitation data demonstrate the existence of at least two distinct types of 600-kDa complexes, one that contains DmCDC46 and one that appears to contain both DmMCM2 and Dpa (a CDC54 homologue). These complexes are stable throughout embryonic division cycles, are resistant to treatments with salt and detergent, and are present during development in tissues undergoing mitotic DNA replication as well as endoreplication. When extracts are prepared under low salt conditions all three MCM proteins co-immunoprecipitate. Consequently, we suggest that the 600-kDa complexes interact in a higher order complex.     

Cell migration in Drosophila.

Recent genetic studies in Drosophila have identified signals that direct cell movement, mechanisms that transduce such signals within migrating cells and some of the molecular machinery underlying cell motility. Activation of the fibroblast growth factor receptor signaling pathway is required for migration of the cells of the developing respiratory system and mesoderm. A signal dependent on 3-hydroxy-3-methylglutanyl Coenzyme A reductase attracts migrating primordial germ cells to the somatic gonad, whereas the phosphohydrolase, phosphatidic acid phosphatase type 2, repels germ cells. In the female germline, the migratory path of border cells is directed by the homophilic adhesion molecule E cadherin.     

Bristle patterning in Drosophila.

The 5000 bristles that protrude from the cuticle of a Drosophila adult function as either mechanosensors or chemosensors, and they are arranged in surprisingly intricate patterns. Development of the patterns appears to involve five stages: (1) establishment of a coordinate system of 'positional information'; (2) partitioning of the epidermis into areas where bristles either can or cannot originate; (3) selection of one or more bristle mother cells within each permissible area; (4) suppression of bristle development in the neighborhood of each mother cell; and (5) differentiation of the mother cell to produce four or more descendant cells, each of which forms part of the bristle apparatus. Some of the genes that control these events participate in more than one stage, and others play key roles in seemingly unrelated developmental pathways, including embryonic neurogenesis, body segmentation, and sex determination.     

Peptidomics in Drosophila melanogaster.

In analogy with proteomics technology, where all proteins expressed in a cell or tissue are analysed, the peptidomic approach aims at the simultaneous visualisation and identification of the whole peptidome of a cell or tissue, ie all expressed peptides with their post-translational modifications. With nanoscale liquid chromatography (nanoLC), combined with mass spectrometry and subsequent database searching, the peptidome of the Drosophila larval brain has been identified at the amino acid sequence level. In a single experiment involving only 50 Drosophila larval brains, one can obtain a display of the expressed peptides. In this paper, current peptidomics technology will be explained, using Drosophila as an example. Compared with the 400,000 Drosophila whole bodies that were required as a starting material for traditional biochemical peptide purification rounds, the authors are convinced that peptidomics technology, which in the future will certainly be applied to the analysis of different physiological states, has the inherent potential to bring about a true revolution in the study of the molecular physiology of Drosophila.     

Photoreceptor structures. III. Drosophila melanogaster

The eyes of three eye mutants of Drosophila melanogaster were fixed and thin sections studied for its structural detail in the electron microscope. Each ommatidium was found to have seven retinula cells with an equal number of rhabdomeres (visual units). The rhabdomeres average 1.2 micro in diameter and 60 micro in length. Each rhabdomere consists of osmium-fixed dense bands averaging 120 A in thickness, and with less dense interspaces 200 to 400 A. There is an average of 23 dense bands or 46 interfaces per micron within the rhabdomere. The rhabdomere as we have presented it is a single structure of packed rods or tubes. The "fine structure" within the rhabdomere is similar to that observed by electron microscopy for the retinula of the house fly, and to the retinal rods of the vertebrate eye, and to the chloroplasts of plant cells in a variety of animal and plant photoreceptor structures. In addition, the radial arrangements within the ommatidium of radially unsymmetrical units, the rhabdomeres, is probably related to the analysis of polarized light in the insect eye.     

Comparative morphology of nucleolar DNA in Drosophila. II. Drosophila fulvimaculoides and drosophila tumiditarsus

This paper reports the demonstration, using fluorescence microscopy, of nucleolar DNA in two species of Drosophila. In Drosophila fulvimaculoides, the nucleolar DNA presents a variable morphology, suggestive of puffing activity. This material, which sometimes shows a banded structure like that of the polytene chromosomes, is shown not to be coextensive with the Y chromosome. Nucleolar DNA is demonstrated in Drosophila tumiditarsus also, and previous reports of an association of the dot chromosome with the nucleolus in this species are confirmed. The special usefulness of these two species for various sorts of investigation in pointed out.     

Purification and enzyme stability of alcohol dehydrogenase from Drosophila simulans, Drosophila virilis and Drosophila melanogaster adhS.

Three alcohol dehydrogenases from Drosophila simulans, Drosophila virillis and Drosophila melanogaster adhS (which possesses an alloenzyme with slow electrophoretic mobility) were purified essentially to homogeneity. The purification procedure involves a new step of affinity chromatography, which efficiently lowers the amount of contaminants in the final preparation, producing a very stable enzyme. The purification procedure developed consists of a salmine sulphate precipitation, two CM-Sepharose CL-6B colume-chromatography steps, an affinity-chromatography step and a Sephacryl gel filtration. A minimum of 30-fold purification is obtained and the yield is not less than 34%. The isoelectric points and molar absorption coefficients were determined.     

Neurotrophic factor-like activity in Drosophila.

The NGF-family of neurotrophic factors are structurally similar peptides with related functional properties. So far, this family of neurotrophic factors has only been identified in the vertebrate nervous system. We have determined that cultured Drosophila embryonic cells produce and secrete into medium, an activity which stimulates neurite outgrowth of embryonic chick sensory ganglia. This Drosophila activity can be blocked by antibodies to mouse NGF, indicating an immunological relationship between the Drosophila factor, mouse NGF and possibly other vertebrate neurotrophic factors. Addition of mouse NGF to Drosophila embryonic cells in culture results in increased cell number and enrichment of the neuronal phenotype, indicating that Drosophila cells have the ability to respond to the vertebrate factor. In addition, poly(A)+RNA extracted from Drosophila contains a single 1.4 Kb band which cross-hybridizes with a mouse NGF cRNA probe. These results indicate that vertebrate neurotrophic factor-like functions may operate in a genetically defined invertebrate species.     

Complex mitochondrial DNA in Drosophila.

The larval mtDNA isolated from D. virilis, D. simulans and D. melanogaster exists in complex molecular forms in addition to the simple monomeric circular form. The frequency of circular dimers and oligomers is highly elevated in apparently normal larval tissues. These complex forms of mtDNA are separable on agarose gels. Hind III restriction endonuclease and electron microscopic analyses used in the present study have revealed that circular dimers are simply the circular concatemers of two monomeric circles which are arranged in a head-to-tail structure with no detectable heterologous regions such as insertions or deletions. The electrophoretic patterns of Hind III digested mtDNAs of D. simulans and D. melanogaster (sibling species) are identical and distinguishable from that of distantly related species, D. virilis.