Absorption of dissolved and dispersed nutrients from sea-water by Panulirus japonicus phyllosoma larvae

This study examined the capacity of Japanese spiny lobster Panulirus japonicus phyllosoma larvae to absorb nutrients directly from the surrounding water. For this purpose, 48-, 81-, 124-, 160-, and 264-day-old intermoult larvae were starved for 48 h, held for 30 min to 4 h in 0.05 g L^–1 solutions or dispersions of cholesterol, peanut oil, saccharose and horseradish peroxidase in seawater, and subsequently examined by histological and ultrastructural methods. Lipids, carbohydrate, and protein were detected in either the lumen of the midgut gland tubules, the midgut gland cells, the haemolymph or in the cells of the epidermis of all larvae examined after each experimental period, with general improvement of the cell and tissue characteristics over unfed controls. The lipids were also found in the cuticle. Thus, the results provide evidence of nutrient absorption via the digestive tract, and possibly also via the integument. Structural adaptations that may be involved in the process of absorption were tentatively identified. Our observations suggest the possibility that particulate organic matter (POM) and dissolved organic matter (DOM) can be utilized by the P. japonicus phyllosoma larvae, perhaps as supplementary sources of nutrients to macroscopic diets.     

Usefulness of histological criteria for assessing the adequacy of diets for Panulirus japonicus phyllosoma larvae

Mass seed production depends a great deal on the development of adequate artificial diets, which in turn depends on the development of methods to speedily and reliably assess the nutritional value of experimental diets. This study examined the sensitivity of light histological and ultrastructural criteria to detect differences in the nutritional value of diets for the Japanese spiny lobster, Panulirus japonicus (V. Siebold), phyllosoma larvae. The acceptability of diets, the apparent absorption of lipids and carbohydrates by the midgut gland cells, and the characteristics of various cell types were determined in 43-, 106- and 143-day-old intermoult phyllosoma fed diets of Mytilus edulis (L.) ovary alone (MO) or in combination with Anemia (MO+AR), which so far have given the best results in terms of growth and percentage of metamorphosis into puerulus, and two other diets considered less efficient, viz. Mytilus edulis testis (MT) and Artemia (AR). Acceptability of all diets attained 100% within 10 min of feeding as revealed by observation through the semitransparent cuticle of the larvae. Histological examination of larvae that ingested comparable amounts of food revealed pronounced variation in the absorption of lipids and carbohydrates by the midgut gland cells (AR相似文献   

Distribution, excretion and biotransformation of 14C-piromidic acid in goldfish Carassius aumtus (L.)

Abstract. The pharmacokinetic and metabolic disposition of piromidic acid (PA) was studied in goldfish orally administered a single dose of 40 mg/kg of PA or ¹⁴C-PA with the following results. PA was rapidly absorbed from the alimentary tract and became widely distributed to give maximal organ and tissue levels mostly after 1 h post dosing. Organ and tissue levels of PA as measured by the radioactivity were 1.4–2.2 times as high as those obtained by the bioassay, though their distribution patterns were similar. PA was partly biotransformed to unconjugated antibacterial metabolites, i.e., α -OHPA and β -OHPA and partly to more hydrophilic glucuronides which were excreted into bile. Bioactive metabolites along with PA disappeared almost entirely from the fish within 48 h post dosing. The antibacterial activity of α -OHPA and β -OHPA against major pathogenic bacteria isolated from fish showed two to four-fold greater activity as compared with PA. This pharmacokinetic and metabolic disposition, together with the antibacterial activity of PA and its active metabolites, suggest a possible practical application of PA against bacterial fish diseases.