Gender difference in the relationship of performance in the handgrip and standing long jump tests to lean limb volume in young adults

Groups of young, adult males and females performed the handgrip and standing long jump tests. Their total forearm and leg volumes were calculated from a series of circumference and length measurements, and the lean volumes (bone + muscle) calculated by taking the skinfold thickness into consideration. In the handgrip, the mean female performance was 298 N compared with 496 N for the males. In the standing long jump, mean performance expressed as distance x body mass was 87.3 kg.m for females compared with 137.7 kg.m for males. These superior performances of males could simply reflect their greater muscle mass, as the mean lean volumes of female and male limbs respectively were 0.54 l and 0.89 l for forearms, and 11.82 l and 14.82 l for the two legs. However, when the performances of males and females were grouped by lean limb volume, it was found that while in both tests there were linear relationships, males and females did not share a common line. In both tests the male relationship was at a higher level than the female; therefore, for a given lean volume, the male performance was significantly superior to that of the female. The gender difference found in this study has not been seen in other studies in which the performance of skeletal muscle has been related to the cross-sectional area of the active muscles and the possible reasons for the differences are considered.     

The relationship between glucose transport and the production of succinoglucan exopolysaccharide by Agrobacterium radiobacter

Agrobacterium radiobacter NCIB 11883 was grown in ammonia-limited continuous culture at low dilution rate with glucose as the carbon source. Under these conditions the organism produced an extracellular succinoglucan polysaccharide and transported glucose using the same periplasmic glucose-binding proteins (GBP1 and GBP2) as during glucose-limited growth. Transition from glucose- to ammonia-limited growth was accompanied by a very rapid decrease in glucose uptake capacity, whereas the glucose-binding proteins were diluted out much more slowly (t1/2 approximately 1 h and 14 h respectively). Although the rate of glucose uptake and the concentrations of GBP1 and GBP2 were much lower during ammonia limitation, the activities of enzymes involved in the early stages of glucose metabolism and in the production of succinoglucan precursors were essentially unchanged. Glucose transport was also investigated in two new strains of A. radiobacter which had been isolated following prolonged growth under glucose limitation. Glucose uptake by strain AR18 was significantly less repressed during ammonia limitation compared with either the original parent strain or strain AR9, and this was reflected both in its relatively high concentration of GBP1 and in its significantly higher rate of succinoglucan synthesis. Flux control analysis using 6-chloro-6-deoxy-D-glucose as an inhibitor of glucose transport showed that the latter was a major kinetic control point for succinoglucan production. It is concluded that glucose uptake by A. radiobacter, particularly via the GBP1-dependent system, is only moderately repressed during ammonia-limited growth and that the organism avoids the potentially deleterious effects of accumulating excess glucose by converting the surplus into succinoglucan.     

Phylogenetic relationships of Blepharisma americanum and Colpoda inflata within the phylum ciliophora inferred from complete small subunit rRNA gene sequences

The complete small subunit rRNA gene sequences of the heterotrich Blepharisma americanum and the colpodid Colpoda inflata were determined to be 1719 and 1786 nucleotides respectively. The phylogeny produced by comparisons with other ciliates indicated that C. inflata is allied more closely with the nassophoreans and oligohymenophoreans than the spirotrichs. This is consistent with the placement of the colpodids in the Class Copodea. Blepharisma americanum was not grouped with the hypotrichs but instead was placed as the earliest branching ciliate. The distinct separation of B. americanum supports the elevation to class status given the heterotrichs based on morphological characters.     

Why do some African children develop severe malaria?

Malaria is still a major cause of death and severe illness among children in many parts of tropical Africa, but only a small proportion of children, perhaps 1-2%, who become ill with malaria develop severe disease. Why only, some children experience a severe or fatal attack is not understood clearly. In this article, Brian Greenwood, Kevin Marsh and Robert Snow review some of those characteristics of the parasite and the host that may influence the outcome of a malaria infection. Identification of the relative importance of the many factors likely to be involved is needed in order to develop rational strategies for the prevention of deaths from malaria among children in malaria-endemic areas.     

The cellular and molecular regulation of 1,25(OH)2D3 production

The synthesis of 1,25(OH)₂D₃ is a critical control point in the regulation of calcium metabolism, and possibly in the growth and differentiation of a number of cell types. This paper reviews our current understanding of the regulation of this process at the cellular and molecular levels, with the emphasis on the mechanisms of feedback control 1,25(OH)₂D₃ itself, control of parathyroid hormone, the roles of cyclic AMP dependent protein kinase and protein kinase C, and the interaction between the various intracellular regulators of 1,25(OH)₂D₃ production.     

Aerial Dispersal and Epiphytic Survival of Pseudomonas syringae during a Pretest for the Release of Genetically Engineered Strains into the Environment

Prospective experimental field evaluation of genetically engineered microorganisms, such as microbial pest control agents, raises issues of how to properly ascertain their fate and survival in the environment. Field trials with recombinant organisms must reflect requirements for sampling and monitoring. Field trials were conducted at Tulelake, Calif., to monitor the numbers of viable cells of a nonrecombinant strain of Pseudomonas syringae that entered the atmosphere and landed on plants and soil during and after an aerosol spray application. An exponential decrease in numbers of viable cells deposited at increasing distances from three sprayed plots was observed. The relative rate of survival of cells sprayed directly on plants was more than 10 times higher than that of cells dispersed through the air to similar adjacent plants. Results are being used to gain experience with the characteristics of a release site that influence containment or dispersal and to develop appropriate sampling methodologies for evaluating survival and dispersal characteristics of genetically engineered bacteria released into the environment. The ability to make predictions about microbial dispersal and survival will reduce the uncertainties associated with environmental releases of recombinant organisms.     

Use of diathermy for weeding heterogeneous tissue cultures

Summary Cultures generated from tissues consisting of multiple types of cells are often heterogeneous. Unless the cell type of interest has or can be given some selective growth advantage it may be overgrown by other cells. While developing techniques for the tissue culture of microvascular endothelial cells we evaluated an electrosurgical generator (diathermy) to selectively kill nonendothelail cells. Primary cell cultures were observed at ×100 magnification under phase contrast microscopy and a needle electrode apposed to the cell to be destroyed. A return electrode was constructed by placing a sterile clip in contact with the culture medium. The diathermy power setting controlled the area of lysis. Use of this technique allowed weeding of unwanted cells without damage to endothelial cells, which were able to grow to confluence in pure culture. Dr. Marks receives a Medical Postgraduate Research Scholarship from the National Health and Medical Research Council of Australia. Financial support was received from the Leo Leukaemia and Cancer Research Trust and the Scleroderma Association of New South Wales.     

Response of potatoes to N fertilizer: Quantitative relations for components of growth

Summary Quantitative relationships for key processes influencing N response were derived from measurements of inorganic N in soil, the weights and N contents of foliage and tubers made at intervals during growth of maincrop potatoes in 11 N fertilizer experiments.Apparent mineralization rates (calculated from measurements of N uptake and inorganic N in the top metre and averaged over the growth period) were remarkably similar from site to site despite wide differences in the textures, water contents and organic matter contents of the soils. They were mostly about 0.78 kg N ha^–1 m^–1 d^–1.Inorganic N in the top 50 cm of soil was rapidly removed by the crop until it fell on all sites to a low value (about 4 g N cm^–3) which was maintained for the remainder of the growth period. When N fertilizer was applied, growth rate until at least the end of July was always well defined by a single coefficient in a previously derived equation. Average values of this coefficient for each of the soil types and for each of the years in which the experiments were carried out were within 20% of each other.The minimum %N in the dry matter needed to permit maximum growth rate declined with increase in plant weight in a similar manner to that previously found for other crops.Equations were found for the partition of assimilate and of nitrogen between the foliage and tubers. The coefficients in them were little affected by whether or not N fertilizer was applied.According to these relationships the maximum potential dry weight yield of tubers is 20 t ha^–1 and requires the crop to contain at least 290 kg N ha^–1.     

Correct targeting of the bean storage protein phaseolin in the seeds of transformed tobacco

The storage protein phaseolin accumulates during seed development in protein bodies in cotyledons of the common bean Phaseolus vulgaris. Hall et al. (In L Van Vloten-Doting, TC Hall, eds, Molecular Form and Function of the Plant Genome, 1985 Plenum Press, In press) recently reported the expression of a gene coding for phaseolin and the accumulation of phaseolin protein in developing seeds of tobacco plants regenerated from transformed callus cells. The protein did not accumulate in other organs of the plants. Mature seeds from normal and transformed tobacco plants were obtained and the subcellular distribution of phaseolin in the seeds was examined using both light and electron microscopic immunocytochemical methods. Phaseolin was found in six of seven transformed tobacco embryos examined, but was present in only one endosperm of five. When present, phaseolin was located exclusively in the protein bodies of the embryonic and endospermic cells. Furthermore, phaseolin was restricted solely to the amorphous matrix of the protein bodies and was excluded from the globoid and proteinaceous crystalloid components of these organelles. The subcellular location of phaseolin in seeds from transformed tobacco plants is similar to that seen in mature seeds of the common bean indicating that in the transformed cells the protein is targeted to the right subcellular compartment.