Neurophysiological defects in temperature-sensitive paralytic mutants of Drosophila melanogaster

A new temperature-sensitive paralytic mutant of Drosophila, comatose, is compared behaviorally and physiologically with the previously known types, para and shi. All three have different properties with respect to kinetics of paralysis at high temperature and recovery from paralysis; com is hypersensitive to paralysis by cooling. Neurophysiological experiments indicate different mechanisms for paralysis in each of the mutants

Proteins of the brain and body wall in larvae of Drosophila melanogaster

Proteins of the brain and body wall cells of third instar larvae ofDrosophila melano-gaster have been examined by two-dimensional gel electrophoresis. Out of over 600 [35S]-labelled peptide spots seen in brain or body wall extracts, 517 were common to both; 61 spots were unique to brain and 66 unique to muscle. Glycoproteins were identified by soaking the gels in radioactive iodinated Concanavalin-A. Forty four Con-A binding glycoproteins were identifiable in the brain and 41 in the muscle extracts. Out of these, 8 glycoproteins of the brain and 8 of muscles appear to be tissue-specific

Odour avoidance learning in the larva of Drosophila melanogaster

Drosophila larvae can be trained to avoid odours associated with electric shock. We describe here, an improved method of aversive conditioning and a procedure for decomposing learning retention curve that enables us to do a quantitative analysis of memory phases, short term (STM), middle term (MTM) and long term (LTM) as a function of training cycles. The same method of analysis when applied to learning mutants dunce, amnesiac, rutabaga and radish reveals memory deficits characteristic of the mutant strains

Reduced odor responses from antennal neurons of G<SUB>q</SUB>&#945;, phospholipase C&#946;, and rdgA mutants in Drosophila support a role for a phospholipid intermediate in insect olfactory transduction

Mechanisms by which G-protein-coupled odorant receptors transduce information in insects still need elucidation. We show that mutations in the Drosophila gene for Gq&#945; (dgq) significantly reduce both the amplitude of the field potentials recorded from the whole antenna in responses to odorants as well as the frequency of evoked responses of individual sensory neurons. This requirement for Gq&#945; is for adult function and not during antennal development. Conversely, brief expression of a dominant-active form of Gq&#945; in adults leads to enhanced odor responses. To understand signaling downstream of Gq&#945; in olfactory sensory neurons, genetic interactions of dgq were tested with mutants in genes known to affect phospholipid signaling. dgq mutant phenotypes were further enhanced by mutants in a PLC&#946; (phospholipase C&#946;) gene, plc21C. Interestingly although, the olfactory phenotype of mutant alleles of diacylglycerol kinase (rdgA) was rescued by dgq mutant alleles. Our results suggest that Gq&#945;-mediated olfactory transduction in Drosophila requires a phospholipid second messenger the levels of which are regulated by a cycle of phosphatidylinositol 1,4-bisphosphate breakdown and regeneration

Osmotropotaxis in larvae of Drosophila melanogster

The larvae of Drosophila exhibit osmotropotaxis. At high concentrations of the odorant, chemotactic response is strongly oriented. At low concentrations oriented crawl is replaced by quasi-random turning. If the olfactory sensillum is ablated unilaterally, the larvae turn so as to present the ablated side to the odour source

Neurogenetics of olfaction in Drosophila melanogaster

A number of genes involved in olfactory behaviour of Drosophila have been identified. The understanding of the physiology and anatomy of the first few stages of the olfactory pathway promises a reliable diagnosis of genetic lesions. The stage is thus set for studies on the molecular biology of olfaction

INCORPORATION OF PARENTAL DNA INTO GENETIC RECOMBINANTS OF E. COLI

Two kinds of mechanisms have been considered to account for genetic recombination in bacteriophage and bacteria. One involves exchange of pre-existing genetic material between homologous chromosomes (breakage and reunion), and the other implies exchange of genetic information without exchange of pre-existing genetic material (copy choice). Experiments by Meselson and Weigle2 and Kellenberger, Zichichi, and Weigle have shown that when a strain of bacteriophage X containing labeled DNA is crossed with an unlabeled and genetically distinguishable strain, the genetic recombinants arising from such a mating contain discrete amounts of the parental DNA. We present evidence which indicates that recombinants arising from the mating of an Hfr with an F- strain of Escherichia coli inherit labeled DNA from the F- parent. Bacterial conjugation involves a progressive transfer of genetic markers from the Hfr to the recipient F-. There is a concomitant transfer of DNA from the Hfr to the F-. The recipient subsequently gives rise to recombinants. The present procedure for detecting the incorporation of parental DNA into recombinants involves the mating of a T6-resistant Hfr to a T6-sensitive F- carrying specifically labeled DNA. When the mated cells are exposed to a high multiplicity of the phage T6, the sensitive cells are rapidly lysed. The T6-resistant F- recombinants can then be separated by filtration and examined for the presence of the parental label

The fine genetic structure of the pabal region of Aspergillus nidulans

The linear relationship between fourteen allelic p-aminobenzoic-acid-requiring mutants of Aspergillus nidulans was investigated. The mutants were assigned to twelve different mutational sites within one functional region. No case of intra-cistron complementation was found. The order of sites as determined by the distribution of the outside markers in different crosses between paba alleles is consistent and the recombination fractions between the sites are approximately additive. Crossing-over between alleles is associated with strong localized negative interference. The topography of the pabal region is characterized by a marked concentration of the mutational sites in a small part of the cistron