Infection of gill and kidney of Fraser River sockeye salmon, Oncorhynchus nerka (Walbaum), by Parvicapsula minibicornis and its effect on host physiology.

Adult sockeye salmon, Oncorhynchus nerka (Walbaum), migrating upstream in the Fraser River, British Columbia, are exposed to the myxozoan parasite Parvicapsula minibicornis when they enter the river from the ocean. Infections are initially localized in the kidney but have recently been associated with branchitis in one population. Adult fish from five locations in the watershed were sampled to determine whether branchitis was widespread. P. minibicornis infections in kidney glomeruli were prevalent in all samples except for a sample of fish that had just entered the Fraser River from the ocean. For fish captured in spawning streams, parasites were observed in the renal tubules and gill, and branchitis was observed in 70% of fish. Plasma osmolality was negatively correlated with the number of parasites in the kidney tubules, which we hypothesize to be caused by the breach of glomerular membranes as the parasite leaves the fish. Plasma lactate values increased with increasing levels of pathology in gills. These findings support the hypothesis that P. minibicornis impacts the physiology of migrating fish, which may in turn affect the likelihood that adults will be able to migrate and spawn successfully.

A quantitative genetic analysis of phenotypic plasticity of diapause induction in the cricket Allonemobius socius.

Although numerous studies have indicated that diapause is heritable and phenotypically plastic, none of them has examined the quantitative genetic basis of this plasticity. In this paper we report such an analysis for egg diapause in the cricket Allonemobius socius, the induction of which appears to be largely determined by the mother. We analysed the quantitative genetic basis of the phenotypically plastic response of female A. socius to age and environmental conditions. We measured the production of diapause eggs on four occasions over a 16-day period, and in two environments; one mimicking an 'early' period of the year and another mimicking a 'late' period. We analysed genetic variation in phenotypic plasticity using the character-state approach. Diapause proportion was heritable (h2 ranged from 0.17 to 0.49, being larger in the 'early' environment), and the genetic correlation between ages in proportion of diapausing eggs was close to 1 but showed a decrease with increased difference between ages. There were significant genetic correlations between environments for all ages. Because of the reduction in genetic correlation as the difference in ages increases, selection will be more effective at changing the overall shape of the reaction norm than causing local changes. Furthermore, the high genetic correlations may constrain the evolution of the reaction norm. When the two environments are converted into the estimated days in the year the two reaction norms form approximately a single curve as predicted from previous theoretical analysis of the optimal reaction norm.

Older age and elevated blood pressure are risk factors for intracerebral hemorrhage after thrombolysis.

Intracerebral hemorrhage is an important concern after thrombolytic therapy for acute myocardial infarction, but risk factors are controversial. Accordingly, we assessed risk factors in 107 treated patients of whom 4 had intracerebral hemorrhage. Intracerebral hemorrhage occurred at a mean of 25 hours (range 3.5 to 48) after therapy and was fatal in 2 patients. Significant differences were found between patients with and without intracerebral hemorrhage for age (77 +/- 7 vs 62 +/- 11 years, p less than or equal to 0.01), and initial (161 +/- 23 vs 135 +/- 23 mm Hg, p less than or equal to 0.03) and maximal (171 +/- 30 vs 146 +/- 20, p less than or equal to 0.02) systolic blood pressures. Initial and maximal diastolic blood pressures also tended to be higher (101 +/- 25 vs 86 +/- 16, p less than or equal to 0.07; 104 +/- 24 vs 90 +/- 13, p less than or equal to 0.06). Differences did not achieve significance for comparisons of gender, height, weight, site of infarction, time to therapy, specific thrombolytic agent used, concomitant therapy, interventions and partial thromboplastin time. It is concluded that age (greater than or equal to 70 years) and elevated blood pressure (greater than or equal to 150/95 mm Hg) are important risk factors for intracerebral hemorrhage. The overall balance of benefit and risk of thrombolysis should continue to be assessed by large mortality trials.

Wind Speed and Mortality Rate of a Marine Fish, the Northern Anchovy (Engraulis mordax).

Large variability in recruitment of marine fishes creates challenging management problems. In northern anchovy (Engraulis mordax), there is a significant linear relation between larval mortality rate and the frequency of calm, low wind speed periods during the spawning season, possibly because calm winds permit maintenance of concentrated patches of larval food. Neither cannibalism on larvae nor offshore transport contributed significantly to interannual variation in early larval mortality. These results are consistent with the hypothesis that wind-driven turbulent mixing affects variability in survival of young fish larvae. However, abundance of recruits does not necessarily reflect abundance of larvae surviving through this early stage.

Study of purine metabolism in a xanthinuric female.

A case of xanthinuria is briefly described, and the results of in vivo studies with (14)C-labeled oxypurines are discussed. The data demonstrate that the rate of the turnover of uric acid is normal, despite an extremely small uric acid pool. Xanthine and hypoxanthine pools were measured and their metabolism evaluated. The bulk of the daily pool of 276 mg of xanthine, but only 6% of the 960 mg of hypoxanthine, is excreted. Thus, xanthine appears to be a metabolic end product, whereas hypoxanthine is an active intermediate. Biochemical implications of this finding are discussed.