Gut contents of 2,500 stonefly nymphs, comprising 10 species, from the Gunnison and Dolores Rivers, Colorado were examined from Dec., 1974-Oct., 1975. Perlidae species were carnivorous feeding primarily on chironomids, mayflies and caddisflies. Seasonal patterns of ingestion and preference varied among species and predator sizes and between rivers. Early instar polyphagous species utilized detritus in the fall, eventually shifting to carnivorous habits as they grew through winter-spring. Pteronarcids fed predominantly on detritus. Dietary overlap of predators was greatest in the Gunnison River, with subtle mechanisms such as prey species and size selectivity, temporal succession and seasonal shifts to detritus-plant material in some, providing reduction of competition. A more complete partitioning of prey resources was evident in the Dolores River.

Drumming was recorded for 11 of 13 Nearctic stonefly species, representing 4 families. Both male and female signals were obtained from 5 species, and were either 2-way or 3-way communications. Signals were species-specific; those of males and females varied from 3-39 and 1-14 beats/ signal, respectively. Duration of male signals varied from 105-8,016 ms; those of females, except Perlinella drymo (1 beat), varied from 402-1318 ms. Signals among related taxa showed greatest similarities. Duration of male signals of Perlinella drymo became progressively shorter at each of 4 temperatures from 7-29 0C. Females of Perlinella drymo would only repeatedly answer male signals recorded at near their own temperature, and would not repeatedly answer recorded male signals of 8 other species.

A model for the study of the relationship of immunity to cancer is found in AKR mice which harbor Gross virus. This genetically transmitted virus is present in a latent form for months before it spontaneously induces leukemia. Many investigators have demonstrated near normal humoral responses, but abnormal cellular immunity in the preleukemic animal. With increasing age, pathology of the disease is expressed, reflecting diminished immunity. In this study, the ontogeny of humoral antibodies of AKR/J and SWR/J mice was assayed by microagglutination techniques in response to thymus-independent, thymus-dependent, and solubilized antigens. Simultaneous injections of thymusdependent and -independent antigens provided data suggesting an impaired humoral response in the AKR mouse.

Azotobacter and various fungi were grown together in nitrogen-free media. Maximal fungal growth in the medium used was possible only at the expense of Azotobacter cells and growth was always accompanied by acid production. When the medium reached a pH of 2, the bacterial cells were aggregated on fungal hyphae and the culture fluid appeared to be free of Azotobacter. Aspergillus niger grew well at the expense of viable bacteria and other fungi grew well on heat-killed cells of A. vinelandii. Members of the genus Hormodendrum, although not causing significant decrease in pH, were also able to clear turbid cultures of Azotobacter. However, clearing, which involved the attachment of bacteria to fungal hyphae, was dependent on acid production by the fungi. Bacterial aggregation was followed by hyphal attachment, bacterial inactivation, and finally, bacterial cell lysis.

Data on the life cycle of Hydropezrla crosbvi were collected from January, 1974, to March, 1976, in Clear Creek, Denton County, Texas. Laboratory investigation helped in establishing instar number, egg incubation and description, and first instar descriptions. Adult Hydroperla crosbyi emerge in February - March when water temperature increases to a mean of 15 C. Eggs undergo a diapause, hatching when decreasing water temperature reaches 18 C in October - November. Maximum growth occurs when water temperatures are coldest. Male and female nymphs undergo ca. 12 and 14 instars, respectively. Larvae of Simuliidae and Chironomidae are the preferred food items of nymphs throughout the growth season.

The peptidoglycan layer of Vitreoscilla stercoraria, ATCC 15218, was isolated from intact cells after treatment with sodium lauryl sulfate (SLS) and digestion with Pronase. Amino acid and amino sugar content was analyzed and 67% of the total present was made up of glutamic acid, alanine, diaminopimelic acid (DAP), and glucosamine in a molar ratio of 1:1.7:1:0.7. Electron microscopy of the final peptidoglycan product showed a thin, delicately folded sacculus which exhibited a morphology different from that of the intact vegetative cells. Within these sacculi occurred electron-dense structures which were assayed and found to be poly- 3-hydroxybutyrate (PHB) granules. The final yield of peptidoglycan was 2.9% of the dry weight of the intact vegetative cell.

Aryl hydrocarbon hydroxylase activity was studied in cultured human lymphocytes using 3-methylcholanthrene, 1,2- benzanthracene, and 4'-bromoflavone as inducers. The substrates used to run the 60 minute assay were benzo(α)pyrene and diphenyloxazole. At the optimum bromoflavone concentration for induction of aryl hydrocarbon hydroxylase, the induced enzymatic activity compared favorably with that of aryl hydrocarbon hydroxylase induced by 3MC in a 96 hour lymphocyte culture using BP as the assay substrate. The whole cell human lymphocyte system was found to have as much or more activity in 20 ml vials using Joklik's-Modified Minimum Essential Medium at a pH optimum of 7.5 with no co-factor added as did the Roswell Park assay system. The whole cell assay showed that levels of aryl hydrocarbonhydroxylase inducibility in lumphocytes from smokers and non-smokers varied without regard to the subjects' smoking habits. The assay system also indicated that intact lymphocytes generate a similar group of benzo(α)pyrene metabolites as that produced by a hepatic microsomal preparation from C57B1/6J mice.