Pentapeptide (proctolin) associated with an identified neuron

Individual neurons can be recognized and identified anatomically, physiologically, and biochemically in the insect central nervous system. Biochemical analyses of extracts prepared from one such identified neuron show it to be associated with a bioactive pentapeptide called proctolin. This peptide may be a neurotransmitter, and a preparation is established in which its physiological action can be studied at the cellular level.     

Differential reactivity of bovine lymphocytes to species of Brucella

The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P less than 0.01) and with B melitensis (P less than 0.001).     

Fats and oils. Determination of fat in body tissues and in food mixtures.

The official final action acid hydrolysis method, 14.019, for the determination of fat in foods was successfully applied, with slight modifications, to the analysis of homogenates of food, feces, and animal tissues as well as dry samples of mixed foods. In samples containing sucrose or fructose, it was necessary to carry out a fermentation procedure before acid hydrolysis to avoid problems encountered when these sugars were present.     

Epidemiology of fungally-transmitted viruses

Abstract. The recent spread of sugar-beet rhizomania and barley yellow mosaic virus in Europe has stimulated fresh interest in plant viruses with soil-borne fungal vectors. Although there are at least 20 such viruses, most of which cause diseases of important field crops, there are many gaps in our knowledge of their epidemiology because much research has concentrated exclusively on the viruses. The vectors are lower fungi that are obligate parasites of plant roots and are therefore difficult to study experimentally. Resting spores containing virus can survive indefinitely in soils but effects of rotation have not been greatly studied. There is no quantitative information relating inoculum levels of fungus and virus to disease development. Only limited information is available about inoculum distribution in soil and factors affecting its potency. The diseases are mostly dispersed by soil movement during agricultural operations but some features of disease distribution in infested fields await adequate explanation. Little is known about interactions with other micro-organisms.     

Carbon dioxide concentration in soil. Effects on nitrification,denitrification and associated nitrous oxide production

Experiments were conducted to study the effects of a range of CO₂ concentrations (ambient to 100%) on nitrification, denitrification and associated nitrous oxide (N₂O) production in a silt loam soil. It was found that increase in CO₂ concentration from 0.3 to 100% CO₂ increasingly retarded the rate of nitrification. No nitrification occurred at 100% CO₂. Nitrous oxide production associated with nitrification increased as CO₂ increased from 0.3 to 2.6% and tended to be greater as CO₂ concentration increased to 73%. At 100% CO₂, no N₂O was produced during 7 days at 25°C.Carbon dioxide did not affect N₂O production or reduction in a saturated NO₃^?amended soil or the rate of N₂O reduction in anaerobic environments.     

Protein and energy nutrition of brook trout (Salvelinus fontinalis) at optimal and elevated temperatures

The digestible protein (DP) and digestible energy (DE) requirements for maintenance and growth of brook trout (Salvelinus fontinalis) were determined using a factorial model at either optimum (15 °C) or elevated temperature (19 °C). Several key parameters of the factorial model were measured using a series of inter‐related studies. The maintenance requirements for DP and DE were 0.10 gDP kg^?0.69 day^?1 (15 °C) and 0.31 gDP kg^?0.78 day^?1 (19 °C), and 34.86 kJDE kg^?0.84 day^?1 (15 °C) and 46.14 kJDE kg^?0.86 day^?1 (19 °C). The total requirements for DP were 0.10 gDP kg^?0.69 day^?1 + 2.14PG (protein gain) (15 °C) and 0.31 gDP kg^?0.78 day^?1 + 1.98PG (19 °C). The total requirements for DE were 36.86 kJDE kg^?0.84 day^?1 + 1.58EG (energy gain) (15 °C) and 46.14 kJDE kg^?0.86 day^?1 + 1.64EG (19 °C). The partial efficiencies for growth were 0.47 (15 °C) and 0.51 (19 °C) for protein, and 0.63 (15 °C) and 0.61 (19 °C) for energy. Nutrient gain was lower at the elevated temperature; however, feed formulation for brook trout should be adjusted to match changes in nutrient requirements at different culture temperatures. The protein and energy requirements model will be useful for developing commercial feeds and feeding charts for brook trout.