Ultraviolet radiation and Vitamin D3 in amphibian health, behaviour, diet and conservation

Amphibians are currently suffering a period of mass extinction with approximately 20% of species under severe threat and more than 120 species already extinct. In light of this crisis there is an urgency to establish viable ex situ populations and also find the causes of in situ declines. The role of ultraviolet radiation and Vitamin D₃ in amphibian health directly influences both ex situ and in situ populations. Vitamin D₃ can be photosynthesised endogenously via UV-B radiation (UV-B), or acquired through the diet, and then metabolised to calcitriol the biologically active hormonal form. Although, there is a lack of literature concerning Vitamin D₃ requirements and calcitriol synthesis in amphibians, amphibians are likely to have similar Vitamin D₃ requirements and metabolic processes as other vertebrates due to the phylogenetically conservative nature of calcitriol biosynthesis. Deficiencies in calcitriol in amphibians result in nutritional metabolic bone disease (NMBD) and could compromise reproduction and immunity. However, excess biologically active UV radiation has also proven detrimental across all three amphibian life stages and therefore could impact both in situ and ex situ populations. Here we review the role and necessity of UV-B and calcitriol in amphibians and the potential for negative impacts due to excessive exposure to UV radiation. We also identify priorities for research that could provide critical information for maintaining healthy in ex situ and in situ populations of amphibians.     

Effects of experimental design and nitrogen on cabbage butterfly oviposition

Summary To test the prediction that P. rapae egg densities increase with N fertilizer in large-scale systems as they do in model systems with potted plants, we used field experiments with Brassica oleracea var. acephala L. (collards and kale) planted in pots or large field plots, and treated with different levels of nitrogen fertilizer. In small-scale field experiments with potted kale and collards, egg densities were significantly higher on plants with high N than those with low N. But in larger scale experiments with field-grown collards, average seasonal P. rapae egg densities were not significantly correlated with leaf N content. These differences among experiments did not depend on the magnitude of the difference in foliage N levels.     

Analysis of the carbohydrate composition of glycoproteins by high-performance liquid chromatography

A procedure for rapid and sensitive analysis of carbohydrate in glycoproteins is described. After methanolysis and benzoylation of the monosaccharides and carbohydrates of a glycoprotein, the derivatized sugars were analyzed by reverse-phase high-performance chromatography using a Vydac C₁₈ stationary phase and a mobile phase composed of a water/acetonitrile gradient. The advantages of this procedure over previously described methods are (1) the simple binary solvent system which is used requires no buffering salts and (2) separate sets of peaks from individual sugars obviate the usual need to reacetylate sugar amino groups.