Estimates of site potential for Douglas-fir based on site index for several southwestern habitat types

Estimates of site potential for Douglas-fir based on measured site indexes in 450 stands are compared between 10 southwestern habitat types. Significant differences in site potential are found between the habitat types studied.     

Foliage age as a factor in food utilization by the western spruce budworm, Choristoneura occidentalis

The influence of current year foliage age on food consumption and utilization by the western spruce budworm, Choristoneura occidentalis (Lepidoptera:Tortricidae), was examined. Larvae were fed immature foliage of Douglas-fir ( Pseudotsuga menziesii var. glauca ), Engelmann spruce ( Picea engelmannii ), and corkbark fir ( Abies lasiocarpa var. arizonica ) in June and August of 1981 and Douglas fir in June and July of 1982. All larvae feeding on early season (June) foliage reached maturity. Larvae feeding on middle (July) and late (August) season foliage died before reaching pupation. Relative growth rate and efficiency of conversion of ingested food decreased with foliage age in both the 1981 and 1982 experiments. Relative consumption rate increased with foliage age in the 1981 and decreased in the 1982 experiment.     

Winter stomach contents of South Dakota badgers

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Stomach contents of 33 hunter and trapper killed badgers, Taxidea taxus, from northeastern South Dakota were examined during the 1980–81 fur season. Mammal prey species made up the bulk of the ingested food, followed by plant materials. Approximately 40 percent of stomach contents were mammals, 35 percent were of plant origin, 10 percent were birds, 10 percent were insects, while the remainder was mostly inorganic materials. Little significant difference was found in variety of food items consumed by each sex. South Dakota badgers are opportunistic foragers in the wintertime when food is scarce. Individual food items are usually taken in quantity when encountered by badgers.     

Growth inhibitory,insecticidal and antifeedant effects of some antileukemic and cytotoxic quassinoids on two species of agricultural pests

Summary Several quassinoids, obtained by isolation and derivatization fromSimaba multiflora andSoulamea soulameoides, were evaluated for growth inhibitory and insecticidal effects against the tobacco budworm (Heliothis virescens) and for antifeedant effects againstH. virescens and the fall armyworm (Spodoptera frugiperda). The relative activity of the quassinoids as insect growth inhibitors generally paralleled their known relative potency as antileukemic and cytotoxic agents.Phytochemical aspects of this work were supported by Contract CM-97295 with the Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Md. Insects were kindly supplied by the agency of the United States Department of Agriculture at Brownsville, TX.     

Vitamin K-dependent blood coagulation proteins form hetero-dimers

The later stages of the blood coagulation cascade are characterized by the presence of vitamin K-dependent proteins and their involvement in membrane-bound, multi-protein converting complexes with an essential requirement for calcium ions. Specific interactions between zymogens and activating enzymes have not yet been identified. Here we describe a crystallographic study of prothrombin fragment 1 (residues 1-156 of prothrombin) which indicates that vitamin K-dependent coagulation proteins have specific association sites that allow them to form hetero-dimers. The calcium-induced formation of a hetero-dimer between fragment 1 and factor X is demonstrated by cross-linking. Such hetero-dimers of vitamin K-dependent proteins could be significant in the coagulation system.     

Molecular cloning of cDNAs encoding a guanine-nucleotide-releasing factor for Ras p21.

The stimulation of a variety of cell surface receptors promotes the accumulation of the active, GTP-bound form of Ras proteins in cells. This is a critical step in signal transduction because inhibition of Ras activation by anti-Ras antibodies or dominant inhibitory Ras mutants blocks many of the effects of these receptors on cellular function. To reach the active GTP-bound state, Ras proteins must first release bound GDP. This rate-limiting step in GTP binding is thought to be catalysed by a guanine-nucleotide-releasing factor (GRF). Here we report the cloning of complementary DNAs from a rat brain library that encode a approximately 140K GRF for Ras p21 (p140Ras-GRF). Its carboxy-terminal region is similar to that of CDC25, a GRF for Saccharomyces cerevisiae RAS. This portion of Ras-GRF accelerated the release of GDP from RasH and RasN p21 in vitro, but not from the related RalA, or CDC42Hs GTP-binding proteins. A region in the amino-terminal end of Ras-GRF is similar to both the human breakpoint cluster protein, Bcr, and the dbl oncogene product, a guanine-nucleotide-releasing factor for CDC42Hs. An understanding of Ras-GRF function will enhance our knowledge of the many signal transduction pathways mediated by Ras proteins.     

Long-term decline of global atmospheric ethane concentrations and implications for methane

After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s.