Determination of argininosuccinate in normal blood serum and liver

Argininosuccinate has been determined in normal serum and liver extract of rats by chromatographic analysis on Dowex-1-acetate after a brief period of in vivo labeling with l-[U-¹⁴C] citrulline. The amounts found were within the range of other amino acid intermediates of the ornithine cycle, determined in the same samples. Both ¹⁴C and ninhydrin color were measured. Chromatography on Amberlite columns, subsequent to fractionation on Dowex, allowed determination of the other amino acids. Fractionation on Dowex-1-acetate provides a reliable and highly selective method for the analysis of minute amounts of argininosuccinate in biological samples containing other amino acids.     

Nf1-deficient mouse Schwann cells are angiogenic and invasive and can be induced to hyperproliferate: reversion of some phenotypes by an inhibitor of farnesyl protein transferase.

We have developed a potential model of Schwann cell tumor formation in neurofibromatosis type 1 (NF1). We show that mouse Schwann cells heterozygous or null at Nf1 display angiogenic and invasive properties, mimicking the behavior of Schwann cells from human neurofibromas. Mutations at Nf1 are insufficient to promote Schwann cell hyperplasia. Here we show that Schwann cell hyperplasia can be induced by protein kinase A activation in mutant cells. Removal of serum from the culture medium also stimulates hyperplasia, but only in some mutant cells. After serum removal, clones of hyperproliferating Schwann cells lose contact with axons in vitro, develop growth factor-independent proliferation, and exhibit decreased expression of the cell differentiation marker P0 protein; hyperproliferating cells develop after a 1-week lag in Schwann cells heterozygous at Nf1. The experiments suggest that events subsequent to Nf1 mutations are required for development of Schwann cell hyperplasia. Finally, an anti-Ras farnesyl protein transferase inhibitor greatly diminished both clone formation and hyperproliferation of null mutant cells, but not invasion; farnesyl transferase inhibitors could be useful in treating benign manifestations of NF1.     

Human Immunodeficiency Virus Type 2 Vpx-Gag Interaction

Incorporation of Vpx into human immunodeficiency virus type 2 (HIV-2) virus-like particles is mediated by the Gag polyprotein. We have identified residues 15 to 40 of Gag p6 and residues 73 to 89 of Vpx as being necessary for virion incorporation. In addition, we show enhanced in vitro binding of Vpx to a chimeric HIV-1/HIV-2 Gag construct containing residues 2 to 49 of HIV-2 p6 and demonstrate that the presence of residues 73 to 89 of Vpx allows for in vitro binding to HIV-2 Gag.     

American and korean ginseng tissue cultures: Growth,chemical analysis,and plantlet production

Summary Roots, stems, or leaves of American (Panax quinquefolium) and Korean (Panax ginsing) ginseng were grown as callus or supension tissue cultures. Tissue cultures ofP. ginseng would occasionally form plantlets. The fundamental chemical composition, inorganic analysis, and saponin (panaquilin) content of American and Korean ginseng plants and tissue cultures were determined. The crude saponin content is very similar to, but approximately one-half (1.3%, fresh weight) of that present in ginseng roots. Two-dimensional thin layer chromatographic analysis revealed minor differences in the panaquilins present in American and Korean ginseng tissue cultures. The sapogenin, panaxadiol, was isolated from Korean ginseng callus.     

The effect of autonomic nerve stimulation cyclic adenosine monophosphate in skeletal muscle

The effect of electrical stimulation of autonomic nerves on c-AMP levels in the tibial muscle of rats was studied after pretreatment with a phosphodiesterase inhibitor and a muscle paralyzant. Cyclic-AMP levels in the skeletal muscle increase significantly. This increase is not the result of changes in muscle blood flow which might have resulted from autonomic nerve stimulation. These studies indicate that the adenyl cyclase-cyclic AMP system in skeletal muscle may be controlled by the autonomic nervous system.     

Ground wētā in vines of the Awatere Valley,Marlborough: biology,density and distribution

The endemic New Zealand ground wētā (Hemiandrus sp. ‘promontorius’) has a Naturally Uncommon conservation status. This is because of the paucity of information on its density and distribution. Here, the biology, density and distribution of a population of this wētā found in and around vineyards in the Awatere Valley, Marlborough was studied. Wētā density was assessed in vineyards, paddocks and shrublands in this valley. Soil moisture, penetration resistance, pH and organic matter were recorded at locations with and without wētā. Wētā density in vineyards was significantly higher than in either paddocks or shrub habitats. In vineyards, the density of this insect was significantly higher under-vines than in the inter-rows. Higher numbers of this wētā were found in moist soils that required lower force to burrow. Females laid an average of 55 eggs between March and April, which hatched in September. These findings highlight the intersection between agriculture and conservation.     

Haplotyping cryptic Adélie penguin taxa using low-cost,high-resolution melt curves

Distinguishing morphologically cryptic taxa, by definition, requires genetic data such as DNA sequences. However, DNA sequences may not be obtained easily for taxa from remote sites. Here we provide the details of a high-resolution melt-curve-based method using taxon-specific primers that can distinguish two taxa of Adélie penguins, and that will be usable in Antarctica when combined with some of the newly developed field-deployable thermal cyclers. We suggest that the wider adoption of field-deployable polymerase-chain-reaction-based techniques will enable faster assignation of haplotype to individuals in situ, and so allow the targeting of observations and sample collection to specimens relevant to the research question. Targeting individuals will also reduce the need to repeatedly handle animals and reduce the time and travel required to complete field work.