A portable pump sampler for lotic periphyton

A sampling technique for collecting lotic periphyton on sedimentary substrates using a peristaltic pump is described. Quantitative samples of periphyton standing crop and colonization rate are collected by the same procedure. The technique eliminates human disturbance problems associated with floating artificial samplers by establishing permanent sampling sites directly on submerged substances.     

Social hierarchy in relation to adrenocortical activity in Xiphophorus helleri Heckel

A study of the epideictic behaviour patterns of male Xiphophorus helleri Heckel was made, and the social rank of individual fish in 12 groups of three was assessed over a ten-day period. Straight-line hierarchies were established in most groups. An anatomical study was made to locate the adrenocortical tissue, and the adrenocortical activity of each fish was assessed by measuring mean nuclear diameter of 25 adrenocortical cells. Although results were somewhat variable, the highest-ranking fish in 7 out of 12 groups showed the least adrenocortical activity. The remaining two fish showed no significant difference from each other in adrenocortical activity, though their rank was in most cases clearly distinguishable on behavioural grounds.     

Advances in our understanding of vitamin E

Vitamin E is an essential nutrient for animals and man since it is not synthesized in the body. The level of vitamin E in the lipoproteins of plasma and in the phospholipids of vital mitochondria, microsomes, and plasma membranes in humans depends (as in experimental animals) on the amount of biologically active vitamin E being consumed, the levels of dietary prooxidants and antioxidants, and the adequacy of dietary selenium. Studies with chicks have demonstrated an important mode of action of both vitamin E and selenium in metabolism, and provide a solution to the long-term enigma of the true role of vitamin E in the diet of all animals, including man. The biochemical actions of vitamin E and selenium are concerned with prevention of peroxidative damage to cells and subcellular elements, thereby aiding the body in maintaining its normal defense mechanisms against disease and environmental insult.     

Copper regulation of ceruloplasmin in copper-deficient rats.

In copper-deficient rats, oral intubation of copper increases the rate of ceruloplasmin synthesis without affecting general synthesis of plasma or liver proteins. It also restores the enzyme from half to full activity. Copper given by injection at doses commonly employed has additional nonspecific effects on protein synthesis and in some strains of rats produces severe hemolysis. In contrast to deficient rats, in normal rats copper does not elevate plasma ceruloplasmin unless hemolysis also occurs. Thus, at least in deficiency, copper availability controls the rate of synthesis, acitvation, and plasma concentration of ceruloplasmin.     

Effect of fixation time on measurement of 2''-deoxyribonucleoside 5''-triphosphate pools in the rat embyro.

Values for the concentrations of deoxyribonucleoside triphosphates in rat embryos on day 12 of gestation, determined by high-pressure liquid chromatography, were artifactually two to three times as high in embryos fixed by cooling in ice/water followed by freezing on solid CO2, in 20s, as in those more rapidly/fixed in liquid N2, in 1 s.     

Analysis of the principles underlying chemo-immunotherapy of mouse tumours

Summary A CBA mouse fibrosarcoma (M4) growing as a solid tumour was treated with a single high dose (200 mg/kg) of cyclophosphamide (CY) followed by C. parvum (CP) immunotherapy. The optimal time for the administration of both nonspecific (CP IV) and active specific (SC CP-irradiated tumour cell mixtures) immunotherapy after CY was 4 days, compared with 1, 8, or 12 days. Optimal combinations of CY and CP were synergistic in that they provided a stronger antitumour effect than the sum of the individual effects of the two agents. In keeping with the finding that a 4-day interval between CY and CP was better than only 1 day, studies in normal mice show that when CP is given early during the suppressive phase of CY the onset of both specific and nonspecific antitumour effects are delayed. CY increased the susceptibility of mice to the toxic effects of a subsequent high systemic dose of CP.