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At least 271 records · Page 15Linked to original sources
PubMed1991

Transient expression of foreign DNA during embryonic and larval development of the medaka fish (Oryzias latipes).

Species of small fish are becoming useful tools for studies on vertebrate development. We have investigated the developing embryo of the Japanese medaka for its application as a transient expression system for the in vivo analysis of gene regulation and function. The temporal and spatial expression patterns of bacterial chloramphenicol acetyltransferase and galactosidase reporter genes injected in supercoiled plasmid form into the cytoplasm of one cell of the two-cell stage embryo was promoter-specific. The transient expression was found to be mosaic within the tissue and organs reflecting the unequal distribution of extrachromosomal foreign DNA and the intensive cell mixing movements that occur in fish embryogenesis. The expression data are consistent with data on DNA fate. Foreign DNA persisted during embryogenesis and was still detectable in some 3- and 9-month-old adult fish; it was found in high molecular weight form as well as in circular plasmid conformations. The DNA was replicated during early and late embryogenesis. Our data indicate that the developing medaka embryo is a powerful in vivo assay system for studies of gene regulation and function.

Animals↗
PubMed1992

Apical secretion and association of the Drosophila yellow gene product with developing larval cuticle structures during embryogenesis.

The yellow (y) gene of Drosophila melanogaster is required for the pigmentation of larval and adult cuticle structures. The deduced y protein sequence includes two putative N-linked glycosylation sites and a putative signal peptide, suggesting that it might be a secreted molecule. Consistent with the characteristics of a secreted protein, our in vitro translation studies using RNA synthesised from the y cDNA demonstrate that the nascent y polypeptide is a preprotein that cotranslationally translocates into the endoplasmic reticulum (ER) membrane and becomes glycosylated. The N-terminal peptide is cleaved from the preprotein between the two alanine residues at positions 21 and 22, to release the final product into the lumen of the ER. Antibodies raised against the y polypeptide detect the protein starting at 13 h post-fertilization in epidermal cells and in the cuticle structures secreted by them that later become pigmented; in addition, yellow protein is detected in the cuticle structures associated with Keilin's organs. The embryonic beta-galactosidase staining pattern of a transgene, bearing a construct in which expression of the lacZ gene is driven by the y promoter, is also described and is similar to that of the y protein. Our results indicate that the y gene product is an apically secreted protein which becomes an immobilised structural component of the pigmented cuticle.

Amino Acid Sequence↗
PubMed1992

Echinococcus multilocularis: immunological study on the "Em2-positive" laminated layer during in vitro and in vivo post-oncospheral and larval development.

Echinococcus multilocularis oncospheres, primary vesicular cysts, and protoscolices were assessed in vitro and in vivo for their potential to synthesize a PAS-positive laminated layer containing monoclonal antibody (mAb) G11-binding Em2 antigen. The presence of Em2 antigen in developed oncospheres and cysts was subsequently correlated to the potential of in vivo development into a secondary metacestode in recipient host mice, which also responded by anti-Em2 serum antibody formation. In contrast, protoscolices failed to develop the "Em2-positive" layer in vitro under the selected experimental conditions. The failure to develop subsequently in vivo into a secondary metacestode was underlined by a lack of anti-Em2 serum antibody formation by the hosts. We furthermore developed a technique to obtain E. multilocularis clones by inoculating single oncospheres into recipient mice.

Animals↗
PubMed1982

Fertilization and larval development in sea urchins following exposure of gametes and embryos to cadmium.

The gametes and embryos of three sea urchin species were exposed to cadmium chloride at concentrations ranging from 10(-8) M to 10(-3) M. When zygotes were reared in the presence of Cd2+, skeletal differentiation displayed some severe abnormalities or was suppressed, as a function of Cd2+ level. The embryotoxic action of Cd2+ was inversely related to salinity and to Ca2+ concentration. Cadmium-exposed larvae displayed similar abnormalities if Cd2+ was present throughout development or only after hatching, while pre-hatching exposure produced no developmental defects. No aberrations in mitotic figures were observed in cleaving eggs following acute exposure to Cd2+. The pretreatment of sperm or eggs did not affect the ensuing development of embryos, both for acutely toxic Cd2+ levels (up to 10(-2) M), and for prolonged exposures in relatively low Cd2+ levels. The fertilization rate was differently affected depending on whether sperm or eggs were pretreated; i.e., the exposure of eggs to Cd2+ promoted fertilization at relatively high Cd2+ levels. If sperm was exposed to Cd2+, a depression of fertilizing capacity was observed at high Cd2+ levels, while lower Cd2+ levels, displayed an opposite action, resulting in an increase in fertilization rate after prolonged sperm exposure.

Animals↗
PubMed2001

Spatio-temporal expression of a gene encoding a putative RNA-binding protein during the early larval development of the mollusc Patella vulgata.

In the mollusc Patella vulgata a cDNA clone named Esther 32 (E32) was found to be expressed in a specific spatio-temporal pattern. DNA sequence analysis showed that E32 represents a putative RNA-binding protein containing a KH domain. In early trochophore larvae, expression of E32 was found in all cells except the already differentiated trochoblasts and the apical tuft cells. Later on in development, expression was also abolished in the presumptive shell gland and restricted to specific areas, among which were the head and foot anlage. This suggests that E32 is involved in maintaining cells in an undifferentiated state via a post-transcriptional mechanism.

Amino Acid Sequence↗
PubMed2005

Dietary phospholipids are more efficient than neutral lipids for long-chain polyunsaturated fatty acid supply in European sea bass Dicentrarchus labrax larval development.

We evaluated the effects of dietary lipid class (phospholipid vs. neutral lipid) and level of n-3 long-chain PUFA (LC-PUFA) on the growth, digestive enzymatic activity, and histological organization of the intestine and liver in European sea bass larvae. Fish were fed from the onset of exogenous feeding at 7 to 37 d post-hatch with five isoproteic and isolipidic compound diets with different levels of EPA and DHA. Diet names indicated the percentage of EPA and DHA contained in the phospholipids (PL) and neutral lipids (NL), as follows: PL5, PL3, PL1, NL1, and NL3. Histological observations showed different patterns of lipid absorption and accumulation in the intestinal mucosa depending on the level and nature of the dietary lipid fraction. Fish fed high levels of neutral lipids (11%, NL3 diet: 2.6% of EPA + DHA in the NL fraction) showed large intracellular and intercellular lipid deposits in the anterior intestine, but no such lipid accumulation was detected when larvae were fed with low and moderate levels of EPA and DHA in the phospholipid and neutral lipid fractions of the diet (PL and NL1 diets). PL were preferentially absorbed in the postvalvular intestine, and the accumulation of marine PL was inversely correlated to their dietary level. The postvalvular intestinal mucosa and liver showed signs of steatosis; large lipid vacuoles were observed in this region of the intestine and in the liver and were inversely correlated with the level of dietary neutral lipids. The best results in terms of growth, survival, and development (maturation of the digestive system and histological organization of the liver and intestinal mucosa) were obtained in the group fed with 2.3% of EPA and DHA in the PL fraction of the diet (PL3 diet), revealing that European sea bass larvae use the LC-PUFA contained in the PL fraction more efficiently than those from the NL fraction of the diet.

Animal Nutritional Physiological Phenomena↗