Life-cycles of some invertebrate taxa in a small pond together with changes in their numbers over a period of three years

1. Monthly quantitative samples of the invertebrate fauna (except Protozoa) in a small pond were taken over a period of three years. During one year, insect emergence traps were in operation. Water temperatures were recorded during the investigation.
2. The most abundant organisms in the pond were Phaenocora typhlops, Limnodrilus hoffmeisteri and Chaoborus crystallinus. Certain species of Micro-Crustacea and Chironomidae were also abundant but these groups have been dealt with elsewhere (see p. 66). Dendrocoelum lacteum, Polycelis nigra, Helobdella stagnalis, Lumbriculus aariegatus, Tubifex tubifex, Planorbis complanatus, and Asellus meridianus also occurred in considerable though lower numbers; other species occurred in low numbers.
3. The life-cycles and changes in numbers of the more numerous species are considered. The life-histories of D. lacteum, P. nigra, H. stagnalis, P. complanatus, A. meridianus are in agreement with published information. P. typhlops is seasonal in occurrence, being active from May to Sept. inclusive. Times of emergence of adults of various insect species agree with information available in the literature.
4. The life-cycle of L. hoffmeisteri in the pond is as follows: young worms hatch in spring/summer and form the bulk of the population from April to July/Aug; they mature from Aug. onwards and breeding starts in earnest from Feb./March. The life-cycle of T. tubifex is as follows: breeding starts in Feb., recruitment of young takes place from April till June, and these start to mature in Nov./Dec. It is not certain if some animals which breed in the spring/early summer survive to breed the following year.
5. The life-cycle of C. crystallinus appears to be as follows: first instars present from May to Oct., second instars from May to Dec., third instars from June till following Jan., fourth instars all the year round, pupae from May till Aug., and eggs from May to Sept. Adult emergence takes place from late April till mid-Sept.
6. A six-week drought in Oct/beginning Nov. in the second year of the investigation caused considerable mortality in most species, but most survived with only a few exceptions.

     

Sodium Content of Community Water Supplies in California

The amount of sodium ion in water used for ingestion may be critical in effective use of a low sodium dietary regimen. Waters containing not over 20 mg of sodium per liter are provided for in the sodium restricted diets set forth by the American Heart Association. For diets containing more than 500 mg of sodium a day, waters of greater sodium content may be used if proper dietary adjustments are made.While assessment of the long-term average sodium content of a community water supply is difficult, the determined values for sodium lend to classification within range categories. The larger community water supplies in California are presented within several range categories of sodium content.The more commonly used water softeners add sodium to water. The sodium-restricted patient should be cautioned against their use. Similar consideration should probably be given to water supplies of retirement communities where the potential for disorders requiring sodium restriction is greater than in the general population.     

Biochemical and antigenic characterization of the Mycobacterium tuberculosis 71 kD antigen, a member of the 70 kD heat-shock protein family

A 71 kiloDalton antigen from Mycobacterium tuberculosis is recognized by antibodies and by T lymphocytes during infection (Britton et al., 1986a). Partial sequence analysis indicates a relationship between this antigen and the highly conserved family of 70-kiloDalton heat shock proteins (hsp70) (Young et al., 1988). Biochemical and serological characterization of the protein confirms its membership of the hsp70 gene family, and metabolic labelling demonstrates that it is a major component of the mycobacterial response to heat stress. The role of stress proteins as antigens during infection is discussed.     

Direct evidence for an intracellular role for IFN-gamma. Microinjection of human IFN-gamma induces Ia expression on murine macrophages

An intracellular action for IFN-gamma was detected by using microinjection technology. Human IFN-gamma (huIFN-gamma) does not ordinarily act on murine cells because it fails to bind to murine cell surface receptors. However, when huIFN-gamma was microinjected into murine macrophages, a time and dose-dependent induction of Ia was detected by autoradiography on the surface of injected and neighboring cells. These results imply a direct role for internalized IFN-gamma and show that huIFN-gamma, although it fails to be recognized by murine cell surface receptors, can act internally on murine cells. The effect on Ia gene expression induced by microinjected huIFN-gamma was in part indirect: granulocyte/macrophage-CSF (GM-CSF) was released by IFN-gamma-injected macrophages, and this secondary mediator appeared to induce Ia on neighboring cells, inasmuch as anti-GM-CSF blocked Ia induction. Anti-GM-CSF also partially blocked Ia induction by extracellular murine IFN-gamma on murine macrophages. Thus, at least some of the Ia induction attributed to IFN-gamma was mediated by GM-CSF.     

Studies of cloned simian immunodeficiency virus-specific T lymphocytes. gag-specific cytotoxic T lymphocytes exhibit a restricted epitope specificity.

CD8+ CTL inhibit the replication of HIV and simian immunodeficiency virus of macaques (SIVmac) in PBL and, therefore, are likely to play an important role in containing the spread of the AIDS virus in infected individuals. We have generated a series of gag-specific lytic T lymphocyte clones from PBL: of an SIVmac-infected rhesus monkey. These T cell clones are CD3+CD8+ and are MHC class I-restricted in their target specificity. They are, therefore, CTL. Interestingly, all gag-specific CTL clones, as well as the gag-specific lytic activity of PBL of this monkey, demonstrated specificity for a single 25 amino acid fragment of the SIVmac gag protein. Moreover, they were restricted in their lytic function by a single MHC class I allele. These findings illustrate a powerful method for cloning AIDS virus-specific T lymphocytes and demonstrate a remarkably restricted epitope specificity of this AIDS virus-specific CTL response.     

Reductive biotransformations of organic compounds by cells or enzymes of yeast.

Saccharomyces cerevisiae catalyses the asymmetric reductive biotransformation of a variety of compounds containing a carbonyl group or carbon-carbon double bond. Oxidoreductases participating in these reactions which have commercial potential in biotransformation processes are likely to have relatively broad substrate specificity. Important carbonyl reductases falling into this category include YADH- and yeast NADP-dependent beta-ketoester reductases. The enoyl reductase component of the FAS complex may have a role in asymmetric yeast reduction of carbon-carbon double bonds of unnatural substrates. Other nicotinamide-requiring oxidoreductases of yeast are also surveyed to rationalize observed biotransformations of whole yeast cells in terms of specific enzymes. Genetic and protein engineering may enable enzymes to be tailored to accept new substrates. A greater understanding of the enzymes and reactions involved will facilitate further optimization and exploitation of these catalytic systems in industrial processes.