Enzymatic responses of Drosophila melanogaster to long- and short-term exposures to ethanol

The effects of environmental ethanol on larva-to-pupa survival and on the activities of four enzymes were investigated in three Drosophila melanogaster strains. The strains had different allelic combinations at the Odh and Aldox loci on their third chromosomes, but they all carried the Adh ^S -Gpdh ^F allelic combination on the second chromosome. Replicates of each of the strains were exposed to three different ethanol treatments: (i) no ethanol in the medium (control); (ii) 5% ethanol for a single generation (short-term exposure); (iii) 5% ethanol for 20 generations (long-term exposure). In all experiments, the activities of four enzymes (ADH, ODH, GPDH and AOX) were measured in larvae, pupae and adults. The results showed that (i) the larval and adult metabolic responses to environmental ethanol were different; (ii) enzyme activity changes under short-term exposure differed from those measured under long-term exposure; (iii) the activities of the allozymes common to all strains (ADH-S and GPDH-F), differed depending on the genetic background. Changes in larva-to-pupa survival were seen when the larvae of control and exposed lines of the three strains were confronted with various concentrations of ethanol. In all three strains, the exposed lines had significantly higher initial survival rate and ethanol tolerance than the control lines. Strain-specific differences were observed in the ethanol tolerance of both types of line.     

Paucimannose N-glycans in Caenorhabditis elegans and Drosophila melanogaster

There is a rich diversity of paucimannose N-glycans in worms and flies, and these may play a role in the survival of these organisms. Although paucimannose N-glycans are not expressed in vertebrates, complex N-glycans may take over some of the functions of paucimannose N-glycans. Identification of the target proteins of β-1,2-N-acetylglucosaminyltransferase I (GnTI) in worms and flies and elucidation of their functions may thus lead to a better understanding of the role of GnTI-dependent glycoproteins in the survival/longevity of both invertebrates and vertebrates.     

Tissue-specific expression of the acetylcholinesterase gene in Drosophila melanogaster embryos

Summary Acetylcholinesterase activity is present in both particulate and soluble forms in wild-type Drosophila melanogaster embryos. The particulate form of the enzyme is localized in the CNS, while the soluble forms are non-CNS-specific. Deletion mapping studies show that all AChE activity is abolished if the cytological region between 87E1-2 and 87E4 is missing. An additional region mapping to the proximal part of the 87E4 band is needed for CNS-specific AChE activityAbbreviations AChE acetylcholinesterase (acetylcholine acetyl hydrolase, EC 3.1.1.7) - ChE pseudocholinesterase (acetylcholine acylhydrolase, EC 3.1.1.8) - BAP 1,5-bis(allyldimethylammoniumphenyl)-pentan-3-one dibromide - i-OMPA tetraisopropylpyrophosphoramide - CNS central nervous system     

Carnitine suppression of position-effect variegation in Drosophila melanogaster

Carnitine is a well-known naturally occurring compound, very similar to butyrate, with an essential role in intermediary metabolism mainly at the mitochondrial level. Since butyrate inhibits the enzyme histone deacetylase and is capable of suppressing position-effect variegation in Drosophila melanogaster, we tested a further possible function of carnitine in the nucleus, using an assay for the suppression of position-effect variegation. We tested three physiological forms of carnitine (l-carnitine, l-propionylcarnitine, l-acetylcarnitine) for the ability to suppress two different chromosomal rearrangements, inducing variegation of the white ⁺ and brown ⁺ genes. The results show that the carnitine derivatives are capable of suppressing the position-effect variegation, albeit with different efficiencies. The carnitine derivatives interact lethally with Su-var(2)1 ⁰¹, a mutation that induces hyperacetylation of histones, whilst hyperacetylated histories accumulated in both the nuclei of HeLa cells and Drosophila polytene chromosomes treated with the same compounds. These results strongly suggest that the carnitine derivatives suppress position-effect variegation by a mechanism similar to that of butyrate. It is suggested that carnitines may have a functional role in the nucleus, probably at the chromatin level.     

Constitutive heterochromatin in early embryogenesis of Drosophila melanogaster

Summary The formation of constitutive heterochromatin was studied during the embryonic development of Drosophila melanogaster, using the C-banding technique. During embryonic cleavage, C-banded material is not seen in mitotic chromosomes; the differentiation between euchromatin and heterochromatin only occurs at blastoderm. This event correlates with the establishment of position-effect variegation.     

P element excision in Drosophila melanogaster and related drosophilids

Summary The frequency of P element excision and the structure of the resulting excision products were determined in three drosophilid species, Drosophila melanogaster, D. virilis, and Chymomyza procnemis. A transient P element mobility assay was conducted in the cells of developing insect embryos, but unlike previous assays, this mobility assay permitted the recovery of excision products from plasmids regardless of whether the excision event was precise or imprecise. Both quantitative and qualitative differences between the products of excision in the various species studied were observed. The frequency with which P element excision products were recovered from D. melanogaster was 10-fold greater than from D. virilis and C. procnemis; however, the proportion of all excision events resulting in the reversion of a P-induced mutant phenotype was the same. Virtually all excision products recovered, including those resulting in a reversion of the mutant phenotype, did not result in the exact restoration of the original target sequence. Sequence analysis suggested that duplex cleavage at the 3 and 5 termini of the P element, or their subsequent modification, occurred asymmetrically and interdependently. P element-encoded transposase was not absolutely required for P element excision.     

Characterization of permissivity for hobo -mediated gonadal dysgenesis in Drosophila melanogaster

The hobo transposon is responsible for one of the three hybrid dysgenic systems that have been described in Drosophila melanogaster. Most studies on the hobo dysgenic system have been carried out using the PM system as a reference. However, these two systems differ significantly. In particular, several studies have failed to find any correlation between the molecular structures of hobo elements, the instability of the transposon and the incidence of gonadal dysgenic (GD) sterility. On the other hand, no study of the ability of females to permit hobo activity in their progeny when they are crossed with males harboring active hobo elements (permissivity) has yet been reported. In order to investigate the parameters involved in hobo permissivity, four E strains were studied with regard to the molecular nature of their hobo sequences and the GD sterility induced by a controlled source of hobo transposase. We show that hobo permissivity varies both within and between E strains. Moreover, permissivity decreases with age in E females. Our results are discussed with respect to similar phenomena that have been described in relation to the reactivity of the IR dysgenic system. Received: 17 August 1998 / Accepted: 17 December 1998     

Developmental studies on Drosophila melanogaster glutathione s-transferase and its induction by oxadiazolone

Glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene was detected in various developmental stages of Drosophila melanogaster. The specific activity of the enzyme was 110, 35, 25 and 15 nmol/min/mg protein in crude extracts prepared from eggs, larvae, pupae and adult stages respectively. The enzymes from larval, pupal and adult stages were purified and compared. Incorporation of the widely used herbicide oxadiazolone at concentrations of 375 and 563 part/million into the culture media caused 4- and 2.5-fold increase in the enzyme activity in pupal and adult stages respectively.     

Aurora, a non-mobile retrotransposon in Drosophila melanogaster heterochromatin

A novel retrotransposon, aurora, containing 324 by long terminal repeats (LTRs) was detected in Drosophila melanogaster as a 5 kb insertion in the heterochromatic Stellate gene. This insertion causes a 5 bp duplication of the integration site. Southern analysis and in situ hybridization data show that all detectable copies of aurora are immobilized in the D. melanogaster heterochromatin. However, mobile copies of aurora were revealed in the cuchromatin of D. simulans. The element was also found in various species of the melanogaster subgroup and in the D. virilis genome.The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers X70361 and X70362     

High levels of recombination induced by homologous P elements in Drosophila melanogaster

Summary P element transposons in Drosophila melanogaster are capable of mobilizing incomplete P elements elsewhere in the genome, and of inducing recombination. This recombination is usually only of the order of 1% or less. We show that two P elements, located at exactly homologous sites, induce levels of recombination of 20% or higher. The recombination appears to be exact, as determined by the lack of phenotypic effects in recombinant products and the lack of size changes detectable by Southern hybridization. Female recombination is increased, but to a lesser extent than male recombination. Somatic recombination levels are also elevated. Alternative explanations for the high recombination levels are given in terms of the consequences of repair of an excision site and in terms of recombination as part of the replicative transposition process.     

Detection of the lipid-linked precursor oligosaccharide of N-linked protein glycosylation in Drosophila melanogaster

The presence of a glycan of the same molecular size as the lipid linked precursor oligosaccharide (Glc₃Man₉GlcNAc₂) of the N-linked protein glycosylation pathway in mammalian cells has been detected in a glycolipid fraction of cultured Drosophila melanogaster cells. Oligosaccharide sequencing studies were consistent with the existence of a glucosylated high mannose containing structure, which may be the common precursor for N-linked protein glycosylation in insect cells.     

Stage and organ specificity of the degree of variegation of the 6-phosphogluconate dehydrogenase gene in Drosophila melanogaster

Summary The effects of chromosomal rearrangements pn2, pn3, TE100 and TE101 on variegation of the gene Pgd, which controls the synthesis of 6-phosphogluconate dehydrogenase (PGD), were studied in Drosophila melanogaster. The electrophoretic patterns of PGD activity were first examined at different developmental stages. The degree of variegation of Pgd caused by pn2 and pn3 was higher in adult flies (the calculated percentage of cells with inactive Pgd was 70%–80%) as compared with larvae (about 50%). This difference can be explained by the tissue-specific mosaicism of Pgd expression; variegation was high in the neural ganglia, imaginal discs, and posterior gut but relatively low in the salivary glands, fat bodies and Malpighian tubes. In the case of TE100, neither tissue specificity, nor marked differences in the degree of variegation between larvae and adults were found. None of the rearrangements examined had an effect on the expression of Pgd in the ovary cells, but repression was seen in some cells of the male gonads. The data obtained suggest that the timing of clonal initiation is influenced by the rearrangements studied. The possible mechanisms preventing changes in the expression of the Pgd gene in the nurse cells caused by these rearrangements are discussed.     

Male recombination with single and homologous P elements in Drosophila melanogaster

It has previously been shown that, in the presence of a source of P element transposase, male recombination in Drosophila melanogaster is induced at a rate of about 1% in the region of a single P[CaSpeR] element. This paper shows that recombinant chromosomes retain unaltered P[CaSpeR] elements at the original site in a high proportion of cases. This result is incompatible with a simple model in which recombination occurs by resolution of a Holliday junction following P element excision and repair. It has also previously been shown that homozygous regions containing a P element produce male recombination levels of 10–20%, an order of magnitude higher than that given by a single element. This paper shows that reciprocal recombinant chromosomes retaining P[CaSpeR] elements can be combined to produce similarly high levels of recombination. This result potentially allows for recombinant chromosomes from homologous recombination to be analysed at the molecular level in the region of the inserted element.     

Tissue specific expression of the acetylcholinesterase gene in Drosophila melanogaster

Summary Acetylcholinesterase (AChE) is mainly membrane bound in the central nervous system (CNS) of larvae and in the head and thorax of adults of Drosophila melanogaster; it is mostly soluble in the larval carcass, the adult abdomen, similar to that of the embryos (Zador et al. 1986). The enzyme shows the same number of isozymes (four or five) in larvae and adults as in the head of the fly or in embryos (Zador et al. 1986). In the Df(3R)GE26/MKRS stock both the membrane bound and the soluble enzyme are at about half normal levels while in the Df(3R)Ace ^HD1/MKRS stock this is true only for the membrane bound AChE. Therefore the effect of the above deficiencies in larvae and adults is consistent with that in embryos (Zador et al. 1986). In heat-sensitive combinations of certain Ace mutant alleles both the membrane bound and the soluble enzyme has reduced activity.Abbreviations AChE acetylcholinesterase (acetylcholine acetyl hydrolase, EC 3.1.1.7) - BAP 1,5-bis(allyldimethylammonium-phenyl)-pentan-3-one dibromide - CNS central nervous system     

模拟微重力效应对果蝇运动及睡眠的影响

本研究旨在探讨利用模拟微重力效应研究微重力对果蝇运动及睡眠影响的可行性.通过研制能够在模拟微重力环境下实时监测果蝇行为的随机定位仪,监测短时间(3 d)模拟微重力处理过程中,及长时间(10 d、20 d、30 d)处理后雄蝇运动和睡眠的变化;选取受影响较显著的短时间处理组,研究模拟微重力效应对生物钟核心基因(period (per)、timeless(tim)、clock (clk)、cycle (cyc)、cryptochrome (cry))、神经递质多巴胺(dopamine,DA)和5-羟色胺(5-hydroxytryptamine,5-HT)关键合成酶(多巴脱羧酶、酪氨酸羟化酶、色氨酸羟化酶)的编码基因ddc、pale和trh表达水平及DA和5-HT含量的影响.结果显示:短时间暴露下,雄蝇夜晚的运动量增加、单位时间运动次数增加、睡眠时间和次数减少、生物钟基因tim、clk、cyc、cry及神经递质合成相关编码基因ddc、pale和trh的表达水平均显著上升;长时间处理后对雄蝇运动和睡眠的影响较小.本研究认为利用模拟微重力效应研究微重力对果蝇运动及睡眠的影响是可行的,相关研究结果对航天医学研究具有借鉴意义.     

Doc and copia instability in an isogenic Drosophila melanogaster stock

A high degree of heterogeneity and an overall increase in number of insertion sites of the mobile elements Doc and copia were revealed in one substock of an isogenic Drosophila melanogaster stock, while in two other substocks the distribution of copia sites was highly homogenous, but that of Doc sites was again heterogenous. We therefore concluded that copia was unstable in one of the substocks and Doc was unstable in all. Doc instability presumably arose earlier than copia instability. Doc and copia transpositions were directly observed in experiments with one substock. An abundance of copia insertions was revealed in the X chromosome where insertions with deleterious effects are exposed to selection in hemizygous condition. The locations of many other mobile elements (mdg1, mdg2, mdg3, mdg4, 297, B104, H.M.S. Beagle, I, P, BS, FB) were found to be conserved in each substock and did not differ between them, indicating that these mobile elements were stable. This homogeneity is a strong argument against any possibility of inadvertent contamination.