Genomic organization of GB viruses A and B: two new members of the Flaviviridae associated with GB agent hepatitis.

The genomes of two positive-strand RNA viruses have recently been cloned from the serum of a GB agent-infected tamarin by using representational difference analysis. The two agent, GB viruses A and B (GBV-A and GBV-B, respectively), have genomes of 9,493 and 9,143 nucleotides, respectively, and single large open reading frames that encode potential polyprotein precursors of 2,972 and 2,864 amino acids, respectively. The genomes of these agents are organized much like those of other pestiviruses and flaviviruses, with genes predicted to encode structural and nonstructural proteins located at the 5' and 3' ends, respectively. Amino acid sequence alignments and subsequent phylogenetic analysis of the RNA-dependent RNA polymerases (RdRps) of GBV-A and GBV-B show that they possess conserved sequence motifs associated with supergroup II RNA polymerases of positive-strand RNA viruses. On the basis of similar analyses, the GBV-A- and GBV-B-encoded helicases show significant identity with the supergroup II helicases of positive-strand RNA viruses. Within the supergroup II RNA polymerases and helicases, GBV-A and GBV-B are most closely related to the hepatitis C virus group. Across their entire open reading frames, the GB agents exhibit 27% amino sequence identity to each other, approximately 28% identity to hepatitis C virus type 1, and approximately 20% identity to either bovine viral diarrhea virus or yellow fever virus. The degree of sequence divergence between GBV-A and GBV-B and other Flaviviridae members demonstrates that the GB agents are representatives of two new genera within the Flaviviridae family.     

Aulacotheca collicola n.sp. (medullosaceae) from the early Pennsylvanian of the Illinois basin

Compressed synangia referable to the medullosan pollen organ genus Aulacotheca Halle have been discovered in Early Pennsylvanian sediments from Rock Island County, Illinois, U.S.A. Specimens were recovered from localized shales containing floral elements suggesting an upland environment. Based on synangial size, morphology, sporangial number, and prepollen type, two distinct forms, A. collicola n.sp. and Aulacotheca sp., are recognized. Synangia of A. collicola are 11–17 × 2.5 – 4.0 mm and have four to six sporangia. Free sporangial tips are acutely pointed and dehiscence is through a longitudinal slit to the inside of the synangium. Prepollen averages 181 × 129 μm and has a monolete suture with median deflection. Sexine on proximal and distal surfaces shows narrow, closely spaced, anastomosing inpockets; distal and lateral walls are separated by a deep, encircling fold. Synangia of Aulacotheca sp. are 21–33 × 3.8 – 5.5 mm and have 4–6 sporangia. Distally, free sporangial tips have a narrow extension, giving a mucronate appearance. Features of these species suggest that greater morphological diversity in synangial and pollen structure occurs in Aulacotheca and the medullosan pteridosperms than previously recognized.     

Effect of nutrient variations on growth and brefeldin A formation inCurvularia lunata

The highest level of secreted brefeldin A was present in glucose-grown cultures, intermediate levels in glucose-fructose, and xylose cultures and low levels in fructose- and galaotose-grown cultures ofCurvularia lunata. The biomass decreased from glucose, fructose, xylose, glucose-fructose to galactose cultures. Brefeldin A levels and mycelial yields were low in citrate-, gluconate-, and succinate-grown cultures. Inorganic phosphate-limited cultures supported a high level of brefeldin A. Intermediate levels were present in trace elements-, and inorganic phosphate-trace elements-limited cultures.     

The effect of prostaglandins A2,E1,E2,15 methyl E2, 16, 16 dimethyl E2 and F2α on erythropoiesis

Prostaglandins A₂, E₁, E₂, methylated E₂s and F₂α affected erythropoiesis and/or erythropoietin (Ep) production. This action is indicated in the exhypoxic, polycythemic mouse where radioiron incorporations into RBC increased after administration of these compounds. The kidney and liver have been indicated through previous studies, to actively participate in Ep production. By the removal of one of these active sites in a murine system treated with prostaglandins it is shown that a response is reflected in Ep levels. Interference of the action of prostaglandins (PG) is altered by the removal of one of these target sites of Ep production. The erythropoietic responses elicited by PGA₂, E₁, and perhaps the methylated PGE₂s act through the liver whereas PGE₂ may operate through a renal pathway for its response. PGF_2α reveals no effect on erythropoietic activity and is no different than that observed for vehicle-treated controls. The prostaglandins tested appear to act primarily through the kidney or liver but the possibility exists that some yet undetermined organ site may also be involved.     

Carnitine uptake and fatty acid utilization by diploid cells aging in culture

Uptake of carnitine by cultured human fetal lung flbroblasts (WI-38 and IMR-90) and by smooth muscle cells from calf aorta and from human uterus was found to be temperature dependent and saturable. IMR-90 cells showed an apparent K_m of 6–8 μM and a V of 21–28 pmol/h/10⁶ cells for l-carnitine. Transport was abolished by N-ethylmaleimide and was inhibited variably by octanoyl-d-carnitine, d-carnitine, and carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Although WI-38 and IMR-90 cells accumulate lipids as they age in culture, they take up carnitine as rapidly as do smooth muscle cells of aorta and uterus that do not exhibit such accumulation. Comparison of the rates of carnitine uptake by IMR-90 fibroblasts during the logarithmic phase of growth shows no difference between “young” and “old” cultures. In contrast, when confluent or postconfluent monolayers were compared and uptake expressed as a function of cell number, cells grown from late passages took up carnitine more rapidly than did cells grown from early passages. However, when account was taken of cell size, and carnitine expressed as a function of cell volume, the differences in carnitine uptake between early and late passages were no longer apparent for the confluent or postconfluent monolayers examined. Moreover, late passage fibroblasts took up and oxidized radioactive palmitate at least as rapidly as did cells from early passages. Our results suggest that accumulation of lipid in aging fibroblasts is not due to decreased carnitine uptake or fatty acid oxidation.     

A study of deoxyribonucleotide metabolism and its relation to DNA synthesis

A model system (2) was established to analyze purine and pyrimidine metabolism. This system has been expanded to include macrosimulation of DNA synthesis and the study of its regulation by terminal deoxynucleoside triphosphates (dNTPs) via a complex set of interactions. Computer experiments reveal that our model exhibits adequate and reasonable sensitivity in terms of dNTP pool levels and rates of DNA synthesis when inputs to the system are varied. These simulation experiments reveal that in order to achieve maximum DNA synthesis (in terms of purine metabolism), a proper balance is required in guanine and adenine input into this metabolic system. Excessive inputs will become inhibitory to DNA synthesis. In addition, studies are carried out on rates of DNA synthesis when various parameters are changed quantitatively. The current system is formulated by 110 differential equations.     

A new species of Ionactis (Asteraceae: Astereae) from Southern Nevada and an overview of the genus

Ionactis caelestis Leary & Nesom is a new species known from a single population that occurs on the Aztec Sandstone near Bridge Mountain in the Spring Mountains of Clark County, Nevada. It is placed in the genus Ionactis (=Aster subg. Ianthe) on the basis of its crowded, multicipital crown, lack of persistent basal leaves and presence of densely arranged cauline ones, strongly carinate phyllaries, blue rays, disc style branches with linear-lanceolate appendages, asymmetric carpopodia, double pappus, and chromosome number of 2n = 9 II. A key to the four species of the genus emphasizes the distinction of the new species in its taproot, the abundant, large, glandular trichomes on its stems and leaves, and disc flowers with sterile ovaries. Ionactis is more similar to the goldenaster (Heterotheca) lineage than to Aster, with which it has been allied formerly. The core of the goldenaster genera differ from Ionactis primarily in their yellow-rayed heads, the crystal complement within cells of their disc corollas, and their primarily multinerved achenes.     

Expression of glucoamylase gene usingSUC2 promoter inSaccharomyces cerevisiae

Summary The cloning of glucoamylase geneSTA using theSUC2 promoter intoSaccharomyces cerevisiae was performed. The signal sequence ofSTA gene was used for the secretion of glucoamylase protein. The plasmid constructed in this way was named YEpSUCSTA and its expression was identified. The expression of YEpSUCSTA was repressed in the presence of glucose in growth medium, but derepressed when glucose became depleted. YEpSUCSTA showed the similar efficiency of glucoamylase secretion as YEpSTA-F which has the entireSTA gene. Glucoamylase activity in starch-glucose medium was largely increased because cell mass and plasmid stability were high in biosynthesis phase compared to extracellular glucoamylase activities in media which starch or glucose was the only carbon source.     

Induced feeding preferences in dicofol-resistant two-spotted spider mites (Acari: Tetranychidae)

Preadult rearing conditions affected the behavior of dicofol-resistant two-spotted spider mites (Tetranychus urticae). Resistant spider mites reared on dicofol-treated leaves initiated a significantly greater number of feeding bouts on dicofol-treated leaves than did genetically identical spider mites reared on residue-free leaves. Therefore the prior exposure of resistant spider mites resulted in induced feeding preferences that could exacerbate the potential outcome of the resistance by resulting in greater amounts of feeding by resistant individuals on dicofol-treated areas. Since resistant individuals that had not experienced dicofol in their lifetime did not display this feeding preference, avoidance of this phenomenon of induced feeding preference may be an undescribed value of rotations of pesticides.