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PubMed2006

Oral susceptibility to bluetongue virus of Culicoides (Diptera: Ceratopogonidae) from the United Kingdom.

Oral susceptibility to infection with bluetongue virus (family Resviridae, genus Orbivirus, BTV) serotype 9 was characterized in three Palaearctic species of Culicoides (Diptera: Ceratopogonidae). Variation in susceptibility to infection by using a recently described feeding technique was shown to occur between populations of Culicoides obsoletus Meigen complex midges from different geographic regions of the United Kingdom with virus infection rates varying from 0.4 to 7.4% of those tested. Susceptibility to infection was consistent on an annual basis at selected sites. Prevalence of infection in the most susceptible populations of both the C. obsoletus and Culicoides pulicaris L. complexes was comparable with that of Culicoides imicola Kieffer, the major vector of BTV in southern Europe and throughout Africa, when using the same feeding method and virus. These results are discussed with reference to the potential threat of the virus to susceptible livestock in northern Europe.

Animals↗
PubMed1996

Purification of the cytosolic CuZn-superoxide dismutase (CuZn-SOD) of Marchantia paleacea var. diptera and its resemblance to CuZn-SOD from chloroplasts.

Suspension-cultured cells of Marchantia paleacea var. diptera contain a single form of CuZn-superoxide dismutase (SOD; EC 1.15.1.1) which is localized in the cytosol. SOD activity was found in cells cultured under heterotrophic, photoheterotrophic and photoautotrophic conditions. The CuZn-SOD was purified to homogeneity from liverwort cells that had been cultured heterotrophically. Its molecular mass was 32.6 kDa, and it contained 17.5 dDa subunits, an indication that the enzyme is a homodimer. The enzyme had peaks of absorption at 252, 258 and 264 nm in the ultraviolet region, due to the presence of phenylalanine, and a peak at 680 nm in the visible region, which is characteristic of CuZn-SODs from chloroplasts. The amino acid sequence of the amino-terminal region of the enzyme exhibited a very high degree of homology to those of chloroplast CuZn-SODs. An antiserum raised against the CuZn-SOD from liverwort cross-reacted more strongly with the enzyme from spinach chloroplasts, than with the enzyme from spinach cytosol. These results indicate that the CuZn-SOD of liverwort resembles CuZn-SOD in chloroplasts even though the former is located in the cytosol.

Amino Acid Sequence↗
PubMed1998

Characterization of a cDNA encoding CuZn-superoxide dismutase from the liverwort Marchantia paleacea var. diptera.

Suspension-cultured cells of the liverwort Marchantia paleacea var. diptera contain a cytosolic CuZn-superoxide dismutase (SOD) whose N-terminal amino acid sequence is similar to those of the isozymes found in chloroplasts of higher plants [Tanaka et al. (1996) Plant Cell Physiol. 37: 523]. A cDNA (MSODCc) encoding the cytosolic CuZn-SOD was isolated from cDNA library constructed from a liverwort cell suspension culture. The deduced amino acid sequence showed a higher degree of homology with the sequences of CuZn-SODs in chloroplasts than those in the cytosol of higher plants and an unique additional peptide in the C-terminal region, but no plastid transit sequence. Northern blotting using MSODCc as a probe and immunoblot analysis with antiserum against the enzyme revealed that the steady state level of transcript was not affected by copper, but both CuZn-SOD protein and its activity increased.

Amino Acid Sequence↗
PubMed1999

Differential light regulation of the rbcS gene expression in two cell lines of the liverwort Marchantia paleacea var. diptera.

A cDNA of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gene (rbcS) was isolated from cells of the liverwort Marchantia paleacea var. diptera. The rbcS was expressed light-independently in a green line, but light-dependently in a yellow line. The accumulation of the large subunit of RuBisCO was regulated cooperatively with that of the small subunit.

Amino Acid Sequence↗
PubMed2001

Characterization of cDNA of the liverwort phytochrome gene, and phytochrome involvement in the light-dependent and light-independent protochlorophyllide oxidoreductase gene expression in Marchantia paleacea var. diptera.

The cDNA of the phytochrome gene in the liverwort Marchantia paleacea var. diptera (MpdPHY1) was isolated. MpdPHY1 encoded a conventional phytochrome apoprotein. The MpdPHY1 transcript was accumulated in the dark and suppressed in the light. The degradation of the MpdPHY1 transcript by red light irradiation had red/far-red reversibility, suggesting that the liverwort phytochrome gene expression was regulated by a phytochrome. Northern blot analysis of the transcripts in cells irradiated by red/far-red light revealed that the liverwort phytochrome was involved in the expressions of chlB, chlL, chlN, or por, which encode subunits of light-independent and light-dependent protochlorophyllide oxidoreductase, respectively.

Amino Acid Sequence↗
PubMed2002

Photosynthetic electron transport regulates the stability of the transcript for the protochlorophyllide oxidoreductase gene in the liverwort, Marchantia paleacea var. diptera.

The transfer of Marchantia paleacea var. diptera cells to darkness caused a reversible repression in the accumulation of transcript for a gene, por, encoding the NADPH: protochlorophyllide oxidoreductase (EC 1.3.1.33). The photosynthetic inhibitor DCMU and DBMIB repressed the accumulation in light. In the presence of transcription inhibitor cordycepin, not only incubation in the dark but also addition of DCMU or DBMIB in light stimulated the degradation of the por transcript. These findings suggest that photosynthetic electron transport is involved in regulating the stability of the por transcript.

Darkness↗
PubMed2004

Photosynthetic electron transport differentially regulates the expression of superoxide dismutase genes in liverwort, Marchantia paleacea var. diptera.

Liverwort, Marchantia paleacea var. diptera, contains Mn-superoxide dismutase (Mn-SOD) in mitochondria, Fe-SOD in chloroplast and CuZn-SOD in cytosol. An Mn-SOD gene (MpMnSOD) was isolated from the liverwort. Using this clone together with the liverwort Fe-SOD and CuZn-SOD genes as probes, the expression of three SOD genes was investigated. Under heterotrophic conditions, the transcript of three SOD genes was accumulated light independently. On the other hand, under photoautotrophic conditions, the transcript levels of Fe-SOD and Mn-SOD increased in the light while that of CuZn-SOD decreased. The reverse occurred in the dark. In contrast to the transcript level, the activity of the three SODs was barely affected by light. The transcription inhibitor, cordycepin, inhibited either the light-promoted accumulation of Fe-SOD and Mn-SOD transcript or the light-induced reduction of the CuZn-SOD transcript. Photosynthetic electron transport inhibitors, DCMU and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, inhibited the photo-response in three SOD genes. These results suggest that the transcript abundance of three SOD genes in liverwort is regulated by photosynthetic electron transport but the mechanism regulating the transcript abundance of the CuZn-SOD gene is different from that of the Fe-SOD and Mn-SOD genes.

Amino Acid Sequence↗
PubMed2025

Dating the origin of a viral domestication event in parasitoid wasps attacking Diptera.

Over the course of evolution, hymenopteran parasitoids have developed a close relationship with heritable viruses, sometimes integrating viral genes into their chromosomes. For example, in Drosophila parasitoids belonging to the Leptopilina genus, 13 viral genes from the Filamentoviridae family have been domesticated to deliver immunosuppressive factors to host immune cells, thereby protecting parasitoid offspring from the host immune response. The present study aims to comprehensively characterize this domestication event in terms of the viral genes involved, the wasp diversity affected by this event and its chronology. Our genomic analysis of 41 Cynipoidea wasps from six subfamilies revealed 18 viral genes that were endogenized during the early radiation of the Eucoilini/Trichoplastini clade around 75 million years ago. Wasps from this highly diverse clade develop not only from Drosophila but also from a variety of Schizophora. This event coincides with the radiation of Schizophora, a highly speciose Diptera clade, suggesting that viral domestication facilitated wasp diversification in response to host diversification. Additionally, in one of the species, at least one viral gene was replaced by another gene derived from a related filamentovirus. This study highlights the impact of viral domestication on the diversification of parasitoid wasps.

Animals↗
PubMed2000

Different mechanisms underlie phenotypic plasticity and interspecific variation for a reproductive character in drosophilids (Insecta: Diptera).

The insect ovary is a modular structure, the functional unit of which is the ovariole. Ovariole number is positively correlated with potential reproductive output. Among drosophilids (Insecta: Diptera), ovariole number shows both phenotypic plasticity and substantial interspecific and interpopulational variation. Here we examine the mechanistic connection between phenotypic plasticity and genetically fixed variation in ovariole number within the melanogaster species group. When a laboratory population of Drosophila melanogaster was reared under reduced food conditions, differences in ovariole number were entirely due to alterations in cell differentiation during the wandering stage at the very end of larval development. Cell growth and cell death were not affected. When these same flies were reared under a variety of temperatures, ovariole number differences arose during the latter half of the third (final) larval instar. Cell differentiation was affected, although cell number was not, and ovariole number differences were established before metamorphosis. In contrast, genetically fixed, interspecific and interpopulational variability in ovariole number was caused by alterations in the dynamics of cell differentiation and by cell number differences. Furthermore, the stages affected were different in different species and populations in the melanogaster species group, ranging from the first (D. sechellia) through the middle of the third (D. simulans and D. mauritiana) larval stage. Therefore, the mechanistic bases for plasticity-based variability are largely distinct from the mechanistic bases for interspecific and interpopulational variability. Our results suggest that phenotypic plasticity indicates evolutionary flexibility in underlying ontogenetic processes.

Animals↗
PubMed2004

Behavioural and electrophysiological responses of the malaria mosquito Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) to human skin emanations.

Behavioural and electrophysiological responses of Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) to human skin emanations collected on glass beads were studied using a dual-port olfactometer and electroantannography. Glass beads to which skin emanations from human hands had been transferred elicited a level of attraction similar to a human hand. The attractiveness of these handled glass beads faded away 4 h after transfer onto the beads. Storage at -20 degrees C for up to 8 weeks showed a decreased but still attractive effect of the beads. In a choice test between one individual and four others, the emanations from the reference individual were significantly more attractive in three out of four cases. The headspace of handled glass beads elicited a dose-dependent EAG response. The substances causing EAG activity could be removed partially by dichloromethane, ethanol and pentane-ether. Glass beads provide a suitable neutral substrate for the transfer of human odour to enable chemical analysis of the human skin emanations for identification of kairomones of anthropophilic mosquitoes.

Animals↗
PubMed1997

Phylogeny and potential transmission routes of midgut-associated endosymbionts of tsetse (Diptera:Glossinidae).

Many tsetse species (Diptera: Glossinidae) harbour two morphologically different intracellular endosymbiotic microorganisms associated with gut tissue: primary (P) and secondary (S) endosymbionts. The P-endosymbionts of tsetse (Wigglesworthia glossinidia) are sequestered in specialized epithelial cells, bacteriocytes, which form a structure (bacteriome) in the anterior portion of the gut. Phylogenetic characterization of P-endsymbionts from the three subgenera of genus Glossina has shown that these organisms constitute a distinct lineage within the gamma-subdivision of Proteobacteria and have evolved concordantly with their insect host species, suggesting an evolutionarily ancient association for this symbiosis. The S-endosymbiont is a smaller (1-2 micron) gram-negative rod and is harboured in midgut epithelial cells. Its phylogenetic characterization from Glossina morsitans morsitans had shown that it is a member of the family Enterobacteriaceae within the gamma-3 subdivision of the Proteobacteria, closely related to enteric bacteria. Some tsetse species harbour a third bacterium in their reproductive tissue, which was shown phylogenetically to belong to to the Wolbachia pipientis assemblage of microorganisms. Here, we show that S-endosymbionts from five tsetse species, representing all three subgenera, form a cluster of closely related microorganisms, based on their almost identical 16S rRNA gene sequences. The high similarity provides strong evidence of recent independent acquisition of S-endosymbionts by individual tsetse species, unlike Wigglesworthia which displays concordant evolution with host insect species. A PCR-based assay and restriction fragment length polymorphism (RFLP) analysis was developed to localize the S-endosymbionts and Wigglesworthia in ovary, egg, milk-gland and spermatheca tissues in order to investigate the potential routes for the vertical transmission of these symbionts to the intrauterine larvae. Only S-endosymbionts were found to infect milk gland tissue, suggesting that milk gland secretions represent a route of transmission for these symbionts into the developing larva. The ovary tissue was found to harbour only Wolbachia, confirming its transovarial transmission, whereas the mode of transmission of Wigglesworthia remains unknown.

Animals↗
PubMed1988

Allergens of non-biting midges (Diptera: Chironomidae): a systematic survey of chironomid haemoglobins.

Various genera of non-biting midges (Diptera: Chironomidae) possess haemoglobins in larvae and adults. For certain species, these haemoglobins have been implicated in human allergic disease in several countries. The present study confirms and extends observations that haemoglobin is present in many species of Chironomidae, establishes that it is retained from the larval to the adult stage and shows that haemoglobin persists both in live and in dead dry flies. Previous suggestions that Chironomidae should be seen as important environmental and occupational allergens are clearly substantiated.

Allergens↗
PubMed1989

Assessment of a silhouette trap for sampling zoophilic blackflies (Diptera: Simuliidae).

A collapsible animal-type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1-hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r = +0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between the Onchocerca spp. infection rates of flies caught by either method.

Animals↗
PubMed1993

Description and biology of Trichopria painteri n.sp. (Hymenoptera: Diapriidae), a solitary parasitoid of Stomoxys calcitrans (Diptera: Muscidae) from Harare, Zimbabwe.

Taxonomic description and life history are given of Trichopria painteri n.sp. (Hymenoptera: Diapriidae), a solitary endoparasitoid that emerged from Stomoxys calcitrans (L.) (Diptera: Muscidae) pupae collected at an agricultural installation near Harare, Zimbabwe, Africa. Although its low level of parasitism. high immature mortality and short adult life span would require augmentative releases of T.painteri, this parasitoid could reduce isolated field populations of S.calcitrans to an acceptable level within several weeks.

Animals↗
PubMed1994

Factors influencing nuisance blackfly (Diptera: Simuliidae) activity in the Scottish Highlands.

The nuisance activity of blackflies (Diptera: Simuliidae) was investigated in several habitats on Speyside, near Kincraig (57 degrees 08'N, 3 degrees 56'W), Invernesshire, in central Scotland during May-October 1987-89. The main blackfly species caught landing/biting on humans were Simulium reptans, S. argyreatum, S. variegetum and the S. tuberosum complex, in order of prevalence. Blackfly biting activity occurred from mid-May to mid-September. Numbers of female blackflies attracted to volunteers were correlated with their body posture, habitat and the season. Overall, Simulium activity was greatest in mixed birch/juniper forest, least in spruce plantations and at intermediate levels on pasture, moorland and in Scots Pine forest. Compared with an adult, a child experienced twice as many Simulium bites per hour (12.2 v 6.3) in the birch forest. On the child's body, 69% of blackflies landed on the head, neck and back, whereas the majority landed on the legs (48%) and arms (28%) of adults. Bending over, especially during the exertion of gardening, was more attractive to anthropophilic blackflies than standing or kneeling.

Adult↗
PubMed1996

The roles of Phlebotomus martini and P.celiae (Diptera: Phlebotominae) as vectors of visceral leishmaniasis in the Aba Roba focus, southern Ethiopia.

During field studies (December 1988 to April 1990) to determine the vectors of visceral leishmaniasis (kala-azar) in the Aba Roba (Segen Valley) focus of southern Ethiopia, a total of 40,770 sandflies (Diptera: Psychodidae: Phlebotominae) were collected and identified as six species of Phlebotomus and seventeen Sergentomyia spp. Nine of these species were anthropophilic (four Phlebotomus and five Sergentomyia spp.), the dominant being Phlebotomus (Synphlebotomus) martini, P.(S.)celiae and Sergentomyia (Sergentomyia) schwetzi. P.celiae adult populations increased during the rainy season. Of 2326 P.martini and 1044 P.celiae dissected, the parous rate was 29.9% and 24.4%, respectively. Leishmania promastigotes were detected in sixteen P.martini (eleven identified as L.donovani by isoenzyme analysis and/or a DNA probe) and in three P.celiae (two identified by DNA probe), giving overall infection rates of 0.7% (1.9% parous infection rate) and 0.3% (1.2% parous infection rate), respectively. Four isolates from P.martini were typed by their isoenzyme profile as L.donovani zymodeme MON-37 = LON-44, identical to one of the zymodemes isolated from patients in this focus. This is the first evidence that P.celiae is a vector and the first time that P.martini has been implicated in Ethiopia. Based on observations of abundance, seasonality and prevalence of infection of the two Synphlebotomus spp., it is concluded that P.martini is the major vector and P.celiae a secondary vector in the Aba Roba focus. The risk of infection with L.donovani is greatest during the wet season.

Animals↗
PubMed1996

Molecular phylogeny and typing of blackflies (Diptera: Simuliidae) that serve as vectors of human or bovine onchocerciasis.

A subregion of the mitochondrial large subunit (16s) rRNA gene was amplified by polymerase chain reaction (PCR) from nine species of blackflies (Diptera: Simuliidae) which serve as natural or experimental vectors of human or bovine Onchocerca parasites. PCR products from each species of blackfly were tested by directed heteroduplex analysis (DHDA), and their genotypes established according to diagnostic banding patterns of the heteroduplex products. Three alleles of mitochondrial 16s rRNA were found to exist in members of the Simulium (Ewardsellum) damnosum sensu lato complex from West Africa, and two alleles were found in the Neotropical Simulium (Psilopelmia) ochraceum Walker complex and the Simulium (Simulium) metallicum Bellardi complex. Different single alleles were detected in Austrosimulium bancrofti, in English S.(S)noelleri and in two North American laboratory vectors: Simulium (Psilozia) vittatum Zetterstedt and S.(S.)decorum Walker. Phylogenetic analysis of 16s sequences indicated that blackflies from West Africa and the Americas formed distinct clades. Neotropical onchocerciasis vectors were found to be more closely related to Nearctic and Palaearctic non-vector Simulium species than to the African vectors of onchocerciasis.

Animals↗