Mammalian carbamyl phosphate synthetase (CPS). DNA sequence and evolution of the CPS domain of the Syrian hamster multifunctional protein CAD

Glutamine-dependent carbamoyl-phosphate synthetase (EC 6.3.5.5) catalyzes the first step in de novo pyrimidine biosynthesis. The mammalian enzyme is part of a 240-kDa multifunctional protein which also has the second (aspartate carbamoyltransferase, EC 2.1.3.2), and third (dihydroorotase, EC 3.5.2.3) activities of the pathway. Shigesada et al. (Shigesada, K., Stark, G.R., Maley, J.A., and Davidson, J.N. (1985) Mol. Cell Biol. 175, 1-7) produced a truncated cDNA clone from a Syrian hamster cell line that contained most of the coding region for this protein. We have completed sequencing this clone, known as pCAD142. The cDNA insert contained all of the coding region for the glutaminase (GLN) and carbamyl phosphate synthetase (CPS) domains but lacked a short amino-terminal segment. By comparing the primary structure of the mammalian chimera to monofunctional proteins we have identified the borders of the functional domains. The GLN domain is 21 kDa, close to the size of the functionally similar polypeptide products of the Escherichia coli pabA and hisH genes. The domain has the three regions of homology common to trpG-type glutamine amidotransferases, as well as a fourth region specific to the carbamyl phosphate synthetases. The CPSase domain is similar to other reported CPSases in size (120 kDa), primary structure (37-67% amino acid identity), and homology between its amino and carboxyl halves. Analysis of the nucleotide and amino acid sequence identities among the various carbamyl phosphate synthetases suggests that the gene fusion which joined the GLN and CPS domains was an early event in the evolution of eukaryotic organisms and that the Saccharomyces cerevisiae enzyme consisting of separate subunits arose by defusion from an ancestral multifunctional protein.     

Systematic Screening of Drosophila Deficiency Mutations for Embryonic Phenotypes and Orphan Receptor Ligands

This paper defines a collection of Drosophila deletion mutations (deficiencies) that can be systematically screened for embryonic phenotypes, orphan receptor ligands, and genes affecting protein localization. It reports the results of deficiency screens we have conducted that have revealed new axon guidance phenotypes in the central nervous system and neuromuscular system and permitted a quantitative assessment of the number of potential genes involved in regulating guidance of specific motor axon branches. Deficiency “kits” that cover the genome with a minimum number of lines have been established to facilitate gene mapping. These kits cannot be systematically analyzed for phenotypes, however, since embryos homozygous for many deficiencies in these kits fail to develop due to the loss of key gene products encoded within the deficiency. To create new kits that can be screened for phenotype, we have examined the development of the nervous system in embryos homozygous for more than 700 distinct deficiency mutations. A kit of ∼400 deficiency lines for which homozygotes have a recognizable nervous system and intact body walls encompasses >80% of the genome. Here we show examples of screens of this kit for orphan receptor ligands and neuronal antigen expression. It can also be used to find genes involved in expression, patterning, and subcellular localization of any protein that can be visualized by antibody staining. A subset kit of 233 deficiency lines, for which homozygotes develop relatively normally to late stage 16, covers ∼50% of the genome. We have screened it for axon guidance phenotypes, and we present examples of new phenotypes we have identified. The subset kit can be used to screen for phenotypes affecting all embryonic organs. In the future, these deficiency kits will allow Drosophila researchers to rapidly and efficiently execute genome-wide anatomical screens that require examination of individual embryos at high magnification.     

Endurance training amplifies the pulsatile release of growth hormone: effects of training intensity.

The effects of intensity of run training on the pulsatile release of growth hormone (GH) were investigated in 21 eumenorrheic untrained women. The O2 consumption (VO2) at the lactate threshold (LT); fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM; peak VO2; maximal VO2; body composition; and pulsatile release of GH were measured. Subjects in both the at-lactate threshold (/LT, n = 9) and above-lactate threshold (greater than LT, n = 7) training groups increased VO2 at LT and FBLC of 2.0, 2.5, and 4.0 mM and VO2max after 1 yr of run training. However, the increase observed in the greater than LT group was greater than that in the /LT group (P less than 0.05). No change was observed for the control group (n = 5). No among- or within-group differences were observed for body weight, although trends for reductions in percent body fat (P less than 0.06) and fat weight (P less than 0.15) were observed in the greater than LT group, and both training groups significantly increased fat-free weight (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

The semidian rhythm in flowering response of Pharbitis nil in relation to dark period time measurement and to a circadian rhythm

When seedlings of Pharbitis nil Choisy, cv. Violet, are exposed to a single inductive dark period at 27°C, brief interruptions with red light (R) can be promotive after 2–3 h of darkness but increasingly inhibitory to flowering up to the 8–9th h of darkness. This rhythmic response to R interruptions can be advanced in phase by > 1 h when the preceding light period is interrupted with far-red (FR) 2 h before darkness (FR -2 h) or with FR – 15 h, whereas FR –8 h or FR–22 h retard the rhythm. These shifts in the R interruption rhythm are paralleled by equal shifts in the length of the dark period required for flowering. Brief FR interruptions of darkness displayed a similar rhythm which was also advanced by FR –2 h and retarded by FR –8 h. We conclude therefore that the semidian rhythm in the light, which we have previously described, continues through at least the first 12 h of darkness, is manifested in the R interruption rhythm, and determines the critical night length. A circadian rhythm with a marked effect on flowering was also identified, but several lines of evidence suggest that the circadian and semidian rhythms have independent additive effects on flowering and do not appear to show phase interaction.     

The Sex Ratio of Heterodera glycines at Low Population Densities

The sex ratio of the Arkansas 1 isolate of Heterodera glycines was determined in experiments in which ''Lee'' soybean was inoculated with either one or two larvae. A 3:1 male to female sex ratio was established for this isolate under the test conditions used. No influence of one nematode on the penetration and development to adult of another nematode in the same root was detected in double larval inoculations.     

Spider mites of sugarcane in Australia: a review of grass-feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae)

Abstract In many areas of the world, spider mites are significant pests of sugarcane. Australia is currently fortunate in lacking the most destructive species, and usually suffers only sporadic damage. Herein, we provide a key to the genera of spider mites associated with sugarcane, review the most significant genus, Oligonychus Berlese, and provide a key to the species of grass-feeding Oligonychus in the Australasian region. The species O. araneum Davis, O. digitatus Davis, O. grypus Baker and Pritchard, O. orthius Rimando, and O. oryzae (Hirst) are redescribed, while the Australian O. zanclopes sp. n. Beard and Walter from sugarcane and rice, O. turbelli sp. n. Beard and Walter, O. ephamnus sp. n. Beard and Walter and O. festucolus sp. n. Beard and Walter from other grasses, are newly described. Previous records of O. grypus in Australia appear to be misidentifications of what is described here as the new species O. zanclopes .