The disease status of Australian salmonids: bacteria and bacterial diseases

Abstract. Eleven freshwater salmonid hatcheries in southern Australia were surveyed for bacterial pathogens and diseases between 1981 and 1985, Twenty-five populations of fish were examined in the study, representing a total of 2755 fish, from which kidney, liver, spleen, and in some cases peritoneum, blood and faeces were cultured. Bacteria of pathogenic significance isolated included Aeromonas hvdrophila, Streptococcus sp., Lactobacillus piscicola, Yersinia ruckeri, Mycobacterium fortuitum, M. chelonei and a filamentous acid-fast organism of uncertain taxonomic position. Lacto-bacillus piscicola and Streptococcus sp. were associated with clinical and subclinical peritonitis. Mycobacterium chelonei was isolated from visceral granulomas in an externally normal fish. Aeromonas salmonicida, Renibacterium salmoninarum and Edwardsiella tarda were not isolated, indicating that the diseases furunculosis, bacterial kidney disease and edwardsiellosis are exotic to Australian salmonids. Similarly, while Y. ruckeri was isolated, enteric redmouth disease had not been recorded and is considered an exotic disease.     

Deaths in Australian freshwater fishes associated with Chilodonella hexasticha infection

The cause of the deaths of bony bream and other native fish in the Finke River near Alice Springs in winter 1984 was infection with the protozoan ciliate Chilodonella hexasticha. The parasites induced severe generalised epithelial hyperplasia in the gills, which would have compromised respiratory exchange and killed the fish through hypoxaemia. It is suggested that similar winter epizootics of ectoparasites have contributed to previous deaths of fish observed in the Finke River, in association with dry season conditions of low water temperatures and flow rates.     

Industrial Development Groups,Organizational Resources,and the Prospects for Effecting Growth in Local Economies

Using data from a survey of directors of not-for-profit industrial development groups in the United States and from a variety of secondary sources, we test the hypothesis that the presence of an active industrial development group was a significant factor in the economic growth of its service area over the 1977-to-1982 period. The data permit us to control for different levels of organizational resources among growth promotion groups as well as other traditional factors of local economic change in a regression analysis. While growth promotion groups are judged to be effective in terms of the number of jobs that are created or preserved relative to their direct expenditures of resources, neither their presence nor the levels of their organizational resources are significantly related to service area net employment change. The efforts of growth promotion groups are simply overwhelmed in importance by factors such as population size, metropolitan accessibility, location in a growth region, and manufacturing wage rates that characterize the respective service areas.     

关于内蒙古大兴安岭林区大径材培育的探讨

文章通过对内蒙古大兴安岭林区培育大径材的目的、意义、必要性及方法等方面的分析,论述了大径级材培育是促进林区生态、经济和社会协调发展的有力措施。     

Isotopic fractionation of stratospheric nitrous oxide

We propose an isotopic fractionation mechanism, based on photolytic destruction, to explain the 15N/14N and 18O/16O fractionation of stratospheric nitrous oxide (N2O) and reconcile laboratory experiments with atmospheric observations. The theory predicts that (i) the isotopomers 15N14N16O and 14N15N16O have very different isotopic fractionations in the stratosphere, and (ii) laboratory photolysis experiments conducted at 205 nanometers should better simulate the observed isotopic fractionation of stratospheric N2O. Modeling results indicate that there is no compelling reason to invoke a significant chemical source of N2O in the middle atmosphere and that individual N2O isotopomers might be useful tracers of stratospheric air parcel motion.     

Biophysical approach toward tumor regression in mice

An external electrical source of low magnitude was used in a series of experiments to alter inherent tumor potentials in mice. While no significant increase of tumor growth was noted in the acceleration group, total tumor regressions were obtained in the inhibition group. Preliminary studies with leukemia did not yield significant results.