Allelic variants of Ly-5 in inbred and natural populations of mice

Allelic variants of Ly-5 in inbred commensal and other natural populations of mice were analyzed by patterns of restriction fragment length polymorphisms (RFLP) and Southern hybridization using an Ly-5 cDNA probe and by cell-surface staining with a panel of antibodies directed against polymorphic and nonpolymorphic Ly-5 determinants. New Ly-5 alleles were defined by RFLPs generated by both Eco RI and Bam HI restriction enzyme digests. The Mus musculus subspecies and other species within the genus Mus showed a strong correlation between allelic variants defined by restriction enzymes and serologic specificities. The data also suggest the conservation of the Ly-5 gene throughout the genus Mus.     

The interaction of yeast citrate synthase with yeast mitochondrial inner membranes

The specific interaction of yeast citrate synthase with yeast mitochondrial inner membranes was characterized with respect to saturability of binding, pH optimum, effect of ionic strength, temperature response, and inhibition by oxalacetate. The binding ability of the inner membranes is inhibited by proteolysis and heat treatment, which implies that the membrane component(s) responsible for binding is a protein. A protein fraction from inner membranes when added to liposomes will bind citrate synthase. In addition, the binding of yeast fumarase, mitochondrial malate dehydrogenase, and cytosolic malate dehydrogenase to yeast inner membranes was examined. For these studies the yeast mitochondrial matrix enzymes, citrate synthase (from two types of yeast), malate dehydrogenase, and fumarase, as well as cytosolic malate dehydrogenase, were purified using rapid new techniques.     

Demonstration of up-regulated IL 2 receptor expression on an in vitro cloned BCL1 subline

We have established BCL1 CL-3 cells capable of responding to B15-TRF and interleukin 2 (IL 2). This clone has both high affinity and low affinity receptors for IL 2 (IL 2R), but IL 2 by itself did not stimulate either proliferation or immunoglobulin (Ig) secretion. B15-TRF, which possesses both growth and differentiation activity, causes an increase in size of CL-3 cells and renders CL-3 cells responsive to IL 2, including an increased expression of IL 2R (eight-fold to 10-fold) and the differentiation of CL-3 cells into Ig secretion (60 to 80% of cultured cells). CL-3 cells pretreated with B15-TRF for 12 hr become competent to respond to IL 2 by up-regulation of IL 2R within 12 hr. In contrast CL-3 cells pretreated with IL 2 for 12 hr required 24 hr B15-TRF stimulation to result in IL 2R up-regulation. Thus the ordered action of B15-TRF and IL 2 is the most effective operational pathway for the up-regulation of IL 2R. This IL 2-mediated IL 2R up-regulation and induction of Ig synthesis depends upon the concentration of IL 2 in the culture. Both responses seem to be caused by IL 2 molecules bound to high affinity IL 2R. However, the possibility of involvement of low affinity IL 2R can not be vigorously excluded. In fact the level of IL 2 required for a response is far higher than that needed for activated T cell proliferation. This cloned BCL1 subline promises to be a useful tool for studying the regulation and mechanisms of B cell responses.     

Development of the nervous system of the pluteus larva of Strongylocentrotus droebachiensis

Summary Development of the nervous system of the pluteus larva of Strongylocentrotus droebachiensis was investigated using indirect immunofluorescence with antibodies against dopamine, GABA, and serotonin, and glyoxylic acid-induced fluorescence of catecholamines. Serotonergic cells first appear in full gastrulae; dopaminergic and GABAergic cells are present in early four-arm plutei. The number of neurons and the complexity of the nervous system increases through development of the pluteus. In the pluteus the dopaminergic component of the nervous system includes a ganglion in the lower lip of the mouth and a pair of ganglia at the base of the post-oral arms which extend axons along the base of the circumoral ciliary band. The distribution of cells visualized by glyoxylic acid-induced fluorescence is similar to that of dopaminergic cells. GABAergic neurons occur in the upper lip and in the wall of the esophagus. Serotonergic neurons are present in the lower lip; the pre-oral hood contains an apical ganglion which extends axons along the base of the epidermis overlying the blastocoel. The dopaminergic and GABAergic components of the nervous system are associated with effectors involved in feeding and swimming. The serotonergic component is not associated with any apparent effectors but may have a role in metamorphosis.     

Effect of Moniliformis moniliformis density on distribution within the definitive host population (Rattus norvegicus)

The population dynamics of Moniliformis moniliformis was studied in ‘free-ranging’ laboratory rats, Rattus norvegicus, presented with different relative density levels of M. moniliformis in cockroaches, Periplaneta americana. Changes in selected population parameters of the negative binomial distribution were evaluated as indicators of changes in aggregation. A significant increase in the degree of aggregation of parasites occurred as a result of the increase in relative density of infective stages available to the rats. This increase in aggregation was due to the increase in over-dispersion that occurred in female rats only. The degree of aggregation in females was found to be significantly higher than that in males at both treatment levels. The best indicators of the degree of aggregation were found to be the ratio of the variance to the relative density and the ratio of the log-variance to log-relative density. Changes in k were not correlated with changes in over-dispersion or the relative density.     

Gut fungi

Herbivores consume large quantities of cellulose and other plant cell wall (fibre) carbohydrates yet generally lack the enzymes to digest them. This has led to the evolution of specialized portions of the gut, such as the rumen and caecum, which contain large populations of digestive anaerobic microorganisms. Diverse bacteria and protists from this environment have been studied for over a hundred years but it is only recently that a significant population of highly specialized flagellate fungi have been identified. These fungi are important in fibre digestion. Their diversity, properties, activities, phylogeny and possible economic significance are the subjects of this review.     

Field evaluation of starter N and delayed inoculation ofLespedeza cuneata grown in minesoil

A field study was conducted on freshly reclaimed surface-mined area to determine response of sericea lespedeza (Lespedeza cuneata [Dumont] G. Don.) to delayed rhizobial inoculation. Soybeans (Glycine max L.) were used as a control legume. Plots were inoculated with spray applications of rhizobial suspensions at seeding, cotyledon stage or second trifoliate leaf stage, or not inoculated. Starter N at 0, 10 or 20 kg ha^?1 was applied preplant in a factorial arrangement with inoculation timings.G. max. was grown for 92 days andL. cuneata for 121 days. Starter N increased plant growth and total shoot N in both species. However, % shoot N was found to increase only inL. cuneata. Delaying inoculation had no significant effect upon total shoot N or % shoot N accumulation inL. cuneata. Inoculation ofG. max at planting produced greater plant growth and N accumulation than delayed inoculation treatments. Application of inoculum as a surface spray appeared to be an effective method for delayed inoculation as evidenced by nodule formation. Lack of increased plant growth, regardless of time of inoculation, suggests that delayed inoculation does not improve establishment and growth ofL. cuneata in minesoil.     

Recovery of plants from leaf protoplasts of hybrid-poplar and aspen clones

Leaf protoplasts were isolated from shoot cultures of two hybrid poplar clones (Populus alba × P. grandidentata Crandon, NC-5339 and P. nigra Betulifolia × P. trichocarpa, NC-5331) and the Upright European Aspen (P. tremula Erecta) and were cultured in contact with screen discs floated in liquid medium. Protoplast culture was influenced by the growth medium of the source shoot cultures, the protoplast purification procedure, the plating density, and the presence or absence of a coconut water and casein hydrolysate supplement added to the culture medium. The protoplast-derived cells divided more quickly and with higher incidence than previously reported for hybrid poplars. Shoots were regenerated from the protoplast-derived calli and were maintained as shoot cultures. Plants were developed from microcuttings rooted ex vitro and were grown-on in the greenhouse and field.Abbreviations BA benzyladenine - NAA 1-naphthaleneacetic acid - TDZ thidiazuron - WPM Woody Plant Medium, Lloyd and McCown (1980) - MS Murashige and Skoog Medium (1962) - NC-XXXX North Central Forest Experiment Station accession number assigned to hybrid poplar clones.     

Sequences encoding the protein and RNA components of ribonuclease P from Streptomyces bikiniensis var. zorbonensis.

The genes encoding the RNA (rnpB) and protein (rnpA) subunits of ribonuclease P (RNase P) of Streptomyces bikiniensis var. zorbonensis have been cloned by complementing the temperature-sensitive growth phenotype of Escherichia coli strains that carry mutations in these genes. The rnpB sequence of S. bikiniensis includes new covariations that lead to refinement of the previous secondary structure models for RNase P RNAs. The deduced amino acid sequence of S. bikiniensis RNase P is conserved with that of other known RNase P proteins only to a limited extent. Immediately upstream from rnpA is an open reading frame that codes for the highly conserved ribosomal protein, L34. This same gene arrangement occurs in all bacteria studied to date.