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At least 253 records · Page 14Linked to original sources
PubMed1996

Female germ cells of Drosophila require zygotic ovo and otu product for survival in larvae and pupae respectively.

Mutations in the genes ovo or otu can cause abnormal proliferation of XX germ cells, which leads to so-called ovarian tumors, or they can lead to the elimination of XX germ cells, such that adult females possess empty ovaries. Males carrying ovo or otu mutations are unaffected. To find out when this sexual dimorphism affects germ cells, we analyzed the requirement of embryos and larvae for zygotic ovo and otu products. We found that ovo is required for the survival of XX germ cells during larval stages, while XX germ cells lacking otu survive until metamorphosis. Furthermore, we found no sex-transformed mutant larval germ cells and no evidence for an early sex-specific vital process acting in germ cells of the embryo, contrary to what had been suggested earlier.

Animals↗
PubMed1989

A variant beta-tubulin isoform of Drosophila melanogaster (beta 3) is expressed primarily in tissues of mesodermal origin in embryos and pupae, and is utilized in populations of transient microtubules.

The beta 3-tubulin gene of Drosophila melanogaster codes for a variant tubulin isoform which is expressed at two distinct times during development: (1) during midembryogenesis from 8-16 hr postfertilization, and (2) during the 4 days of pupal development. We have determined the spatial pattern of beta 3-tubulin expression by localizing the beta 3 mRNA in paraffin sections using a 3' message-specific RNA probe and by localizing the beta 3 protein using a polyclonal antibody specific for Drosophila beta 3-tubulin. During embryogenesis beta 3 is restricted to and is expressed in all of the developing muscles. During pupal development beta 3 is also expressed at high levels in developing adult muscles. In addition, early in pupal development beta 3 is expressed in the imaginal discs, while at later times beta 3 is expressed in the epidermal cells of the wing blade, the optic lobe, the ovaries, and the testes. The expression of beta 3 tubulin ceases by the end of pupal development in all of these tissues except the ovaries and testes where expression persists into the adult. In both developing muscles and wings our results indicate that beta 3-tubulin is utilized in populations of specialized but transient cytoskeletal microtubules which are involved in establishing the final form of the tissue.

Animals↗
PubMed1999

Fly larvae and pupae as vectors for scrapie.

We analysed experimental transmissibility of the scrapie agent by natural vectors. A fly, Sacrophaga carnaria, fed with brains of scrapie-infected hamsters in different developmental stages caused scrapie in hamsters after they ate fly extracts.

Animals↗
PubMed2002

Differentially expressed genes in metamorphosis and after juvenile hormone application in the pupa of Galleria.

In Galleria mellonella, the pupal-adult transformation of epidermal cells is initiated at day 1 after pupal ecdysis by downregulation of pupal syntheses and loss of juvenile hormone (JH) sensitivity, indicating the change from pupal to adult commitment. To trace regulatory events as close as possible to the early steps of this process, we have analyzed, by differential display, changes in epidermal mRNA populations during the first day after pupal ecdysis in normal development as well as after JH injection. We isolated and cloned 20 cDNA 3'-fragments that are differentially expressed with regard to their developmental profile either in normal development or after injection of JH. Four clones could be verified by Northern blot hybridization. Screening of corresponding cDNA libraries with digoxigenin-labeled anti-sense mRNA probes yielded two full-length cDNA clones (9/27 and 23/86). Both of them represent genes that could be involved in the regulatory events during initiation of pupal metamorphosis or in the action of JH, respectively. The 9/27 mRNA is inducible by JH. It contains, in the 3' untranslated region, a consensus sequence for deadenylation and specific degradation. The corresponding protein possesses two PKC phosphorylation sites and is with high probability a nuclear protein. The 23/86 clone represents polyubiquitin, differentially regulated in normal development and after JH application.

Amino Acid Sequence↗
PubMed1999

Mass spectrometric profiling of glucosamine, glucosamine polymers and their catecholamine adducts. Model reactions and cuticular hydrolysates of Toxorhynchites amboinensis (Culicidae) pupae.

Glucosamine (Gln), glucosamine polymers, and their catecholamine adducts were characterized using positive ion electrospray mass spectrometry (ESMS) and tandem mass spectrometry (ESMS-MS). N-acetyldopamine (NADA), a catecholamine found in many insect cuticles, was oxidized using mushroom tyrosinase, and the resulting quinone derivatives were reacted with Gln, (Gln)3, and polymeric glucosamine (chitosan). Adducts of glucosamine and its trisaccharide with NADA were readily identified as [M + H]+ ions in ESMS spectra, and ESMS-MS of selected ions confirmed the condensation of 1-3 NADA residues with Gln. In addition to Gln modification by the quinone derivatives of NADA, other spectra were consistent with the formation of adducts with N-acetylnoradrenaline and moieties formed by intramolecular cyclization following oxidation. The primary amine of glucosamine was involved in initial adduct formation, but the sites for subsequent additions of oxidized NADA to glucosamine, presumably via hydroxyl groups, could not be identified by ESMS alone. The ESMS spectra of chitosan films infused into the spectrometer following solubilization in acidic methanol/water produced spectra similar to that of (Gln)3 up to m/z 502. Ions of gradually decreasing intensity consistent with (Gln)x, where x = 4-8, were observed. Modification of chitosan films following incubation with NADA plus tyrosinase rendered the films insoluble in dilute acid, simulating the cross-linking process proposed to occur during insect cuticle sclerotization. Acid hydrolysates of the pupal stage of the mosquito Toxorhynchites amboinensis, using only two pupal exuviae for the hydrolyses, were infused into the mass spectrometer without preliminary chromatography. Eight amino acids, glucosamine, N-acetylglucosamine, catecholamines, and a variety of polymers incorporating these compound classes were identified.

Animals↗