Photoperiodic induction of diapause in an insect is vitamin A dependent

Summary A photoperiodic response was found to be absent in larvae of the parasitoid waspApanteles glomeratus when its host (caterpillars ofPieris brassicae) was reared on a low-carotenoid artificial diet. Addition of vitamin A to the host's diet restored the response to short-day photoperiods in the wasp larvae, thus showing that vitamin A is essential for photoperiodic induction of diapause. Possibly vitamin A or a derivative of vitamin A functions as the photoreceptor pigment for the photoperiodic reaction in this species of insect.     

Thermoperiodically induced diapause in a mite in constant darkness is vitamin A dependent

Summary By rearing the predacious miteAmblyseius potentillae in a daily temperature cycle in constant darkness it could be shown that diapause may be thermoperiodically induced. When the same experiments were performed using diets without vitamin A it appeared that vitamin A is necessary to achieve a state of reproductive diapause in this mite.2 February 1987     

The regeneration of newt limbs deformed in nature

Summary The regeneration of abnormal limbs from a wild newt population was examined. The abnormalities were: mirror symmetrical reduplications of digit parts, deformed wrists, or limbs with supernumerary digits. Normal regeneration resulted after amputation of the abnormal parts, regardless of the original deformity. The results suggest that the abnormalities are probably the result of local trauma to the limbs.     

Occurrence of retinal and 3-hydroxyretinal in a possible photoreceptor of the silkworm brain involved in photoperiodism

Summary Deficiency of dietary carotenoid and vitamin A caused an absence of photoperiodic response of diapause induction in the silkworm,Bombyx mori, and an addition of vitamin A to the diet restored the response. By high pressure liquid chromatography (HPLC) a possible photoperiodic receptor of the silkworm brain was found to contain both retinal and 3-hydroxyretinal which are chromophores of insect visual pigments. These pieces of evidence suggest that a retinoid protein might function in the photoperiodic response of the silkworm.     

Effect of a dipeptide inhibiting ubiquitin-mediated protein degradation on nerve-dependent limb regeneration in the newt

The dipeptide Leu-Ala, which inhibits ubiquitin-mediated protein degradation, has been shown to act in vitro as an inhibitor of neurite outgrowth of PC12 cells (Hondermarck et al. [1992] Biochem. Biophys. Res. Commun.189: 280). Using agarose beads as vehicles, we tested, in vivo, the effect of this dipeptide (and the inactive inverse, Ala-Leu, as a control) on limb regeneration in the newt (Triturus cristatus), a nerve-dependent developmental process. Leu-Ala inhibited the growth of mid-bud blastemas without altering blastema differentiation, while Ala-Leu had no effect. Cytological observations of dipeptide-treated blastemas using Bodian staining or neurofilament antibodies showed that all the blastema tissues were unmodified except with regard to innervation. Leu-Ala-treated blastemas were devoid of nerve fibers in the epidermal cap, while the mesenchyme distal to the dipeptide impregnated bead exhibited fewer nerve fibers than did Ala-Leu-treated blastemas, which were similar to the control nontreated blastemas. Thus, Leu-Ala, in reducing blastema innervation, inhibits its growth in the same manner as surgical denervation.     

Messenger RNA differential display strategies in birds and amphibians

As an inroad to the discovery of genes involved in important biological activities, various techniques have been developed for detecting genes based on their expression levels. Arbitrary amplification of different messenger RNA (mRNA) populations and their comparison on display autoradiograms made mRNA differential display one of the most straightforward approaches to identification of differentially regulated mRNAs. Over the past decade this strategy has been employed in many in vitro and in vivo systems. The use of the method in bird and amphibian model systems is reviewed here, emphasizing several unique combinations of model system and design of differential display screen.     

Maternal vitamin A restriction alters biochemical development of the brain in rats.

The biochemical development of the fetal brain in relation to maternal vitamin A restriction was studied in rats. The vitamin A status of pregnant rats was varied by supplying low, medium and adequate amounts (6, 40, and 100 micrograms retinol/day/kg body weight, respectively) of vitamin A during pregnancy and suckling. The maternal vitamin A restriction caused an altered brain development in terms of tissue weight, DNA, RNA and protein levels, and biosynthesis of DNA and protein from [3H]-thymidine and [3H]-leucine, respectively. A dose-dependent effect of maternal vitamin A restriction on the metabolism of DNA, RNA and protein was noticed in the developing fetal brain of rats.     

Chemical evidence for interactions between vitamins E and C

Summary Experimental proof is provided for interactions between radicals of vitamin E/vitamin C as generated by air-oxidized lipids (liquid fraction of subcutaneous chicken fat). Using ESR spectroscopy, hydrogen atom exchange is shown to take place between vitamin C and the radical of vitamin E. Sequential consumption of these two vitamins in oxidized lipid, first vitamin C then vitamin E, is demonstrated by means of differential pulse polarography. These results elucidate the in vitro radical scavenging functions attributed to vitamin E and vitamin C as well as their synergism in lipid antioxidation.The authors very much thank Dr A. Dieffenbacher and P. Ducret for the preparation of the chicken fat fraction.     

Transdifferentiation of larvalXenopus laevis iris implanted into the amputated hindlimb

Summary Fragments of larvalXenopus laevis iris, autoplastically implanted into the stump of the amputated hindlimb, transdifferentiated into neural retina. However, when such iris fragments were implanted into the caudal fin, no transdifferentiative process was observed.Supported by grant from the P.I. ministry.     

Maternal vitamin A restriction alters biochemical development of the brain in rats

Summary The biochemical development of the fetal brain in relation to maternal vitamin A restriction was studied in rats. The vitamin A status of pregnant rats was varied by supplying low, medium and adequate amounts (6, 40, and 100 g retinol/day/kg body weight, respectively) of vitamin A during pregnancy and suckling. The maternal vitamin A restriction caused an altered brain development in terms of tissue weight, DNA, RNA and protein levels, and biosynthesis of DNA and protein from [³H]-thymidine and [³H]-leucine, respectively. A dose-dependent effect of maternal vitamin A restriction on the metabolism of DNA, RNA and protein was noticed in the developing fetal brain of rats.     

Joint effects of dietary protein levels and vitamin A additions on the induction of cytochrome P450 by DDT in rats]

A 5 P. 100 level of protein from casein in a diet does not allow vitamin A to modify significantly induction of cytochrome P 450 on the Rat receiving or not receiving DDT. When the protein increases to a 15 p. 100 level, the induction is better providing vitamin A is to be given. If protein and vitamin A are necessary for cytochrom P 450 induction, an increase of protein level remains inefficient without vitamin A.     

Effect of vitamin A on tumor development in burned, unburned, and glucocorticoid-treated mice inoculated with an oncogenic virus.

High doses of vitamin A decreased the severity of tumor development in mice inoculated with a murine sarcoma virus; the same doses of vitamin A had no effect on the increased tumorigenesis seen in animals severely stressed with thermal injury or the increased tumorigenesis induced by exogenous glucocorticoid administration.     

Liver vitamin A stores in chronic alcoholism in rats: effect of propylthiouracil treatment

Administration of alcohol to rats through drinking water for 8 weeks produced a significant decrease in the liver vitamin A stores without causing any change in the plasma vitamin A levels. Treatment of the alcoholic rats with propylthiouracil for 2 weeks restored the liver vitamin A reserves to control levels.     

Liver vitamin A stores in chronic alcoholism in rats: Effect of propylthiouracil treatment

Summary Administration of alcohol to rats through drinking water for 8 weeks produced a significant decrease in the liver vitamin A stores without causing any change in the plasma vitamin A levels. Treatment of the alcoholic rats with propylthiouracil for 2 weeks restored the liver vitamin A reserves to control levels.     

Growth inhibition and occurrence of cleft palates due to hypervitaminosis A

Summary DNA synthesis in palatal processes obtained from fetal rats was 36% lower in the presence of excess vitamin A, but vitamin A-exposed maxillary explants showed only a modest decrease. Scanning electron micrographs of fetuses exposed to hypervitaminosis A in utero demonstrated both decreased head size and stunted palatal processes. The results suggest that cleft palates occur in this model system because the palatal processes are more sensitive to the actions of vitamin A than are the surrounding maxillary tissues.Acknowledgments. We thank Dr Samuel M. Meller, Assistant Professor of Anatomy, Harvard Medical School, for his assistance in obtaining the scanning electron micrographs. This project was supported in part by grant DE-04684 from the National Institute of Dental Research.     

Effect of aspirin and vitamins C and E on synovial rheumatoid arthritic and other cells

Summary Normal and rheumatoid arthritic human synovial cells, normal rat muscle and bone cells, were cultured with combinations of aspirin (acetylsalicytic acid), vitamins C and E. Aspirin reduced percent growth of all cells by about 1/5 relative to controls. High vitamin C eradicated arthritic cells. In combinations, vitamin C was most important in eradicating arthritic cells. A low-aspirin, low-vitamin C combination was most effective in reducing arthritic cell populations, while having little effect on normal cells. Vitamin E retarded but did not prevent the action of vitamin C.Acknowledgment. This work was supported by NRC grant No. A 6445 to Dr Bhakthan, Department of Kinesiology, Simon Fraser University.     

Comparison of wing margin structures ofvestigial and wild-typeDrosophila melanogaster grown at 31°C

Summary The development of the middle row of triple row wing bristles was examined in flies homozygous for thevestigial mutant, grown at 31°C. While bristle number, length and spacing all improved toward the wild-type condition, the mean values for both sexes were only about 10% of those of wild-type, although development in males was significantly more complete than in females. The results suggest an explanation for the apparent lack of regenerative ability in this tissue.     

The effects of vitamin A nutritional status on glutathione levels and microsomal lipid peroxidation in rat lung

In vitamin A-deficient rats, the glutathione level in lung was diminished and microsomal lipid peroxidation much increased. In vitamin A-loaded animals, however, both were depressed below control. Thus vitamin A protection against lipid peroxidation is independent of glutathione.     

Effect of aspirin and vitamins C and E on synovial rheumatoid arthritic and other cells.

Normal and rheumatoid arthritic human synovial cells, normal rat muscle and bone cells, were cultured with combinations of aspirin (acetylsalicytic acid), vitamins C and E. Aspirin reduced percent growth of all cells by about 1/5 relative to controls. High vitamin C eradicated arthritic cells. In combinations, vitamin C was most important in eradicating arthritic cells. A low-vitamin C combination was most effective in reducing arthritic cell populations, while having little effect on normal cells. Vitamin E retarded but did not prevent the action of vitamin C.