Determination of protein synthesis in rainbow trout, Oncorhynchus mykiss, using a stable isotope

It has been suggested (Houlihan, 1991) that the consumption of 1 g of protein in a variety of species of fish stimulates the synthesis of, approximately, an equal amount of protein. Although synthesis of protein may account for as much as 40 % of the wholeanimal oxygen consumption (Lyndon et al. 1992), only about 30 % of the synthesized proteins are retained as growth (Houlihan et al. 1988; Carter et al. 1993a,b). Thus, one focus of attention is the potential advantage gained by fish in allocating a considerable proportion of assimilated energy to protein turnover in contrast to relatively low-cost, low-turnover protein growth (Houlihan et al. 1993). Rates of protein synthesis in several species of fish have been measured using radioactively labelled amino acids, frequently given as a flooding dose (reviewed by Fauconneau, 1985; Houlihan, 1991). These measurements cannot be made for longer than a few hours because of the decline in specific radioactivity in the amino acid free pool. However, as protein synthesis rates vary during the course of a day as a result of the post-prandial stimulation, and since radiolabelled amino acid methodology is invasive, short-term and terminal, it has been difficult to be certain of the relationship between protein growth measured in the long term and protein synthesis rates measured in the short term. This paper addresses these problems by developing a method using 15N in orally administered protein to measure protein synthesis rates in fish over relatively long periods, the aim being to use procedures that are as non-invasive and repeatable as possible

Rotavirus hospitalisation in New Zealand children under 3 years of age

Objective: To describe the epidemiology of severe rotavirus gastroenteritis and to estimate the hospitalisation rates of this illness in New Zealand children under 3 years of age. Methods: Children under 3 years of age with acute diarrhoea admitted to 1 of 8 study hospitals between 1 May 1998 and 30 April 2000 were surveyed. Their socio-demographic, treatment and length-of-stay data were recorded and stool samples tested by a rotavirus-specific enzyme-linked immunoassay. National hospital discharge data for infectious diarrhoea (International Classification of Diseases, ninth revision, 003–009) were reviewed, allowing population-based estimates for rotavirus-related hospitalisation in New Zealand. Results: Of 2019 enrolled children, 1138 (56.4%) provided stools for testing, and of these 485 (42.6%) tested rotavirus positive. Rotavirus detection varied significantly by age (26.8% for 0 to 5 months, 42.5% for 6 to 11 months and 52.1% for children aged 12 to 35 months; P < 0.001), and by season (51.2% in winter/spring vs. 24.5% in summer/autumn; P < 0.001). While those infected with rotavirus were more likely to be dehydrated (50.6% vs. 37.4%; P < 0.001), their median hospital stay was similar (1.0 vs. 2.0 days; P = 0.09) to other children with acute gastroenteritis. The estimated national hospitalisation rate for rotavirus diarrhoea in children under 3 years, standardised for age and season, was 634 (95% CI 597, 672) per 100 000. In New Zealand, rotaviruses result in 1 in 52 children being hospitalised by 3 years of age. Conclusions: Rotavirus diarrhoea is an important, potentially vaccine-preventable cause of hospitalisation in New Zealand children, especially during winter and spring seasons

Chronic coral consumption by butterflyfishes

Interactions between predators and prey organisms are of fundamental importance to ecological communities. While the ecological impact that grazing predators can have in terrestrial and temperate marine systems are well established, the importance of coral grazers on tropical reefs has rarely been considered. In this study we estimate the biomass of coral tissue consumed by four prominent species of corallivorous butterflyfishes. Sub-adult butterflyfishes (60-70mm, 6-11g) remove between 0.6 and 0.9g of live coral tissue per day, while larger adults (>110mm, ~40-50g) remove between 1.5 and 3g of coral tissue each day. These individual consumption rates correspond to the population of coral-feeding butterflyfishes at three exposed reef crest habitats at Lizard Island, Great Barrier Reef consuming between 14.6g (±2.0) and 19.6g (±3.9).200m-2.day-1 of coral tissue. When standardised to the biomass of butterflyfishes present, a combined reef wide removal rate of 4.2g (±1.2) of coral tissue is consumed per 200m-2.kg-1 of coral-feeding butterflyfishes. The quantity of coral tissue removed by these predators is considerably larger than previously expected and indicates that coral-grazers are likely to play an important role in the transfer of energy fixed by corals to higher consumers. Chronic coral consumption by butterflyfishes is expected to exact a large energetic cost upon prey corals and contribute to an increased rate of coral loss on reefs already threatened by anthropogenic pressure and ongoing climate change