Developmental variation in copper,zinc and metallothionein mRNA in brindled mutant and nutritionally copper deficient mice

The concentrations of copper, zinc and metallothionein-I (MT-I) mRNA were determined in the liver, kidney and brain of the brindled mutant mouse from birth until the time of death. Despite accumulation of copper in the kidney of the mutant, MT-I mRNA concentrations were normal. There was no difference between the MT-I mRNA in the brain of mutant and normal in the first 10 days of life, but after day 10 metallothionein mRNA levels were increased in the mutant. The concentration of copper was very low in the liver of the mutant, and on day 6 after birth the metallothionein mRNA was also reduced by about 50%. This reduction was not seen in copper-deficient 6-day-old pups, despite very low hepatic copper levels. This suggests that the lower hepatic MT-I mRNA in the day 6 brindled mouse was not simply due to the reduction in hepatic copper and also that hepatic copper is not regulating metallothionein gene expression the liver of neonatal mice. After day 12 hepatic MT-I mRNA levels were elevated in mutant and in copper deficient mice, both of which die at 14 to 16 days. These increases and the increase in brain MT-I mRNA in older mutant mice are likely to be caused by stress. Overall the results support the conclusions that the brindled mutation does not cause a constitutive activation of the metallothionein genes, and that the differences in metallothionein mRNA between mutant and normal are most probably secondary consequences of the mutation.     

Earliest mechanical evidence of cross-bridge activity after stimulation of single skeletal muscle fibers.

The stiffness of single fibers from frog skeletal muscle was measured by the application of small 2-kHz sinusoidal length oscillations during twitch and tetanic contractions at a range of initial sarcomere lengths. The earliest mechanical signs of activation were a fall in tension (latency relaxation) and a rise in stiffness. The earliest stiffness increase and the earliest tension fall occurred simultaneously at all sarcomere lengths. This suggests a cross-bridge origin for the latency relaxation. The lead of stiffness over tension seen during the rise of tension was substantially established during the latent period. Reducing the size of the twitch by reducing calcium release with D-600 (methoxyverapamil) reduced the latency relaxation and the stiffness development during latency much less than it reduced the twitch tension. For very small twitches the peak of the stiffness response occurred during the latent period and the times of onset of both latency relaxation and stiffness rise were delayed, but remained coincident. This suggests a strong connection between the latency relaxation and the rise of stiffness during the latent period, whereas the connection between these events and positive tension generation appears to be less strong.     

Psychological treatment of essential hypertension: A controlled comparison of meditation and meditation plus biofeedback

Twenty-one patients with essential hypertension were randomly allocated to eight 1-hour sessions of meditation training, meditation plus biofeedback-aided relaxation, or a no-treatment control group. Statistically significant falls in systolic and diastolic blood pressure occurred after both training programs, although overall reductions in blood pressure were not significantly greater in either program than in the control group. Meditation plus biofeedback-aided relaxation produced falls in diastolic blood pressure earlier in the training program than did meditation alone. All patients practiced meditation regularly between training sessions: The amount of practice did not correlate with the amount of blood pressure reduction after training. On questionnaire measures of psychological symptoms and personality, sex differences emerged, with females showing significant abnormalities in hostility scores and males showing significantly raised levels of somatopsychic symptoms. In females, outward-directed hostility fell significantly and assertiveness increased after training, but in males, somatopsychic symptoms were unchanged.The author is grateful for financial support from the research fund of St. George's Hospital, London, where this project was conducted, and from the Society for Psychosomatic Research. He is indebted to Dr. Chandra H. Patel for invaluable help in conducting the meditation and biofeedback training.     

The identification of unbranched enzyme kinetic mechanisms by computer analysis of qualitative information: Logic of the method

The paper describes the logic of a computer method for identifying unbranched enzyme kinetic mechanisms on the basis of observed initial velocity and product inhibition patterns (Cleland, 1963). The method establishes initially an acceptable order of reactant addition and release, proceeds to list all the mechanisms consistent with that order and the data, and finally determines which of these can also explain data which require either non-competitive or dead-end inhibition.     

Seasonal changes in plasma testosterone and ejaculatory capacity in squirrel monkeys (Saimiri sciureus)

Seasonal changes in body weight, plasma testosterone and ejaculatory capacity were observed in five intact and two testosterone-implanted castrated squirrel monkeys for a total of 13 months. Electroejaculation was employed for obtaining data concerning ejaculation. In the intact animals, there were significant increases in body weight, ejaculate volume and plasma testosterone during the breeding season. With the exception of one animal, there was also a decrease in ejaculation latency during the season. Seasonal differences in the sperm count and sperm motility were not observed. Testosterone-implanted castrates showed changes in both ejaculate volume and ejaculation latency similar to those seen in intact monkeys during the breeding season. The body weight and plasma testosterone of the castrates remained quite constant throughout the year. Supported by NIH grants HD 00778, MH 21178 and MH 23645.     

Studies of ribosomal proteins of yeast species and their hybrids gel electrophoresis and immunochemical cross-reactions

Summary The cytoplasmic ribosomal proteins (r-proteins) of seventeen yeast species of the genera Saccharomyces and Kluyveromyces were analyzed by one-dimensional gradient polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The electrophoretic patterns of cytoplasmic r-proteins from different species display extensive differences in both the 40S and the 60S subunit. Relatedness of species suggested by r-protein patterns correlates well with that based on DNA/DNA homology (Bicknell and Douglas 1970). Immunochemical cross-reactions and antibiotic susceptibility tests were also used to compare different species.Analyses of r-proteins from two different interspecific hybrids showed that their ribosomes were hybrid, containing r-proteins from both parents. These findings are discussed in relation to the evolution of yeast species and the regulation of expression of r-proteins in cucaryotes.     

A new species of Eugenia (Myrtaceae) from Venezuela

Eugenia mcvaughii is described from a forest remnant of the Jardin Botánico of Caracas, Venezuela. Found also in the hills adjacent to Caracas, it may be considered as an endemic species of the Interior Coastal Cordillera.     

New species from the summit of Cerro Guaiquinima,Venezuela

Three new species,Lubaria szczerbanii (Rutaceae),Croton guaiquinimae (Euphorbiaceae), andStomatochaeta colveei (Asteraceae), are described from the summit of Cerro Guaiquinima, Venezuela. The generic affinities betweenLubaria andMyllanthus, and betweenStomatochaeta andStenopadus are discussed.