Sex Pheromone Biosynthesis in Trichoplusia ni: Key Steps Involve Delta-11 Desaturation and Chain-Shortening

In addition to the primary pheromone component (Z)-7-dodecenyl acetate, the sex pheromone gland of Trichoplusia ni contains the immediate fatty acyl precursor (Z)-7-dodecenoate and a large quantity of (Z)-11-hexadecenoate. Labeling experiments showed that (Z)-11-hexadecenoate is chain-shortened to (Z)-9-tetradecenoate, and that this in turn is chain-shortened to (Z)-7-dodecenoate. The same mechanism appears to explain the sex pheromone compositions of many other moth species.     

Allosteric activators of glucokinase: potential role in diabetes therapy

Glucokinase (GK) plays a key role in whole-body glucose homeostasis by catalyzing the phosphorylation of glucose in cells that express this enzyme, such as pancreatic beta cells and hepatocytes. We describe a class of antidiabetic agents that act as nonessential, mixed-type GK activators (GKAs) that increase the glucose affinity and maximum velocity (Vmax) of GK. GKAs augment both hepatic glucose metabolism and glucose-induced insulin secretion from isolated rodent pancreatic islets, consistent with the expression and function of GK in both cell types. In several rodent models of type 2 diabetes mellitus, GKAs lowered blood glucose levels, improved the results of glucose tolerance tests, and increased hepatic glucose uptake. These findings may lead to the development of new drug therapies for diabetes.     

Erosion of galilean satellite surfaces by jovian magnetosphere particles

The Galilean satellites of Jupiter-Io (J1), Europa (J2), Ganymede (J3), and Callisto (J4)-are embedded in the intense ion and electron fluxes of the Jovian magnetosphere. The effect of these particles on the icy surfaces of the outer three satellites depends on the fluxes and the efficiency of the sputtering of water ice by such particles. Recent laboratory measurements provided data on the erosion of water ice by energetic particles and showed that it occurs much faster than would be expected from normal sputtering theory. The Voyager spacecraft encounters with Jupiter provided the first measurements of ion fluxes (energies greater, similar 30 kiloelectron volts) in the vicinity of the Galilean satellites. Using the laboratory sputtering data together with particle measurements from the Voyager 1 low-energy charged particle experiment, the effects of erosion on the surfaces of J2 to J4 are estimated. It is shown that the surface of Europa could be eroded by as much as 100 meters over an eon (10(9) years). Column densities of water vapor that could be produced around the three satellites from particle bombardment of their surfaces are also calculated, and the sources and losses of oxygen in the gravitationally bound gas produced by sputtering or sublimation are estimated.     

X-ray-induced dissociation of H2O and formation of an O2-H2 alloy at high pressure

When subjected to high pressure and extensive x-radiation, water (H2O) molecules cleaved, forming O-O and H-H bonds. The oxygen (O) and hydrogen (H) framework in ice VII was converted into a molecular alloy of O2 and H2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrated that this crystalline solid differs from previously known phases. It remained stable with respect to variations in pressure, temperature, and further x-ray and laser exposure, thus opening new possibilities for studying molecular interactions in the hydrogen-oxygen binary system.     

胃泌素RT-PCR方法的建立及同源性分析

从猪胃窦和十二指肠提取总RNA,采用美国Am b ion RNA公司生产的Q uan tum RNA class ic 18S为内标,建立了半定量RT-PCR方法,并对胃窦和十二指肠胃泌素mRNA进行了定量检测、测序和比较分析。结果表明,扩增的猪胃窦和十二指肠胃泌素核苷酸序列与猪前胃泌素(propregastrin)核苷酸的同源性达到99%。将其与已发表的人、牛、大鼠和小鼠等物种相应序列的比较结果表明,无论是核苷酸水平,还是氨基酸水平,都显示出了较高的同源性(80%~99%)。另外,建立的RT-PCR方法灵敏度高,操作快捷方便,可用于定量检测少量的组织样品中低丰度表达的胃泌素mRNA。     

In Situ Northern Mid-Latitude Observations of ClO, O3, and BrO in the Wintertime Lower Stratosphere

In order to test photochemical theories linking chlorofluorocarbon derivatives to ozone(O(3)) depletion at high latitudes in the springtime, several related atmospheric species, including O(3), chlorine monoxide(ClO), and bromine monoxide (BrO) were measured in the lower stratosphere with instruments mounted on the NASA ER-2 aircraft on 13 February 1988. The flight path from Moffett Field, California (37 degrees N, 121 degrees W), to Great Slave Lake, Canada (61 degrees N, 115 degrees W), extended to the center of the polar jet associated with but outside of the Arctic vortex, in which the abundance of O(3) was twice its mid-latitude value, whereas BrO levels were 5 parts per trillion by volume (pptv) between 18 and 21 kilometers, and 2.4 pptv below that altitude. The ClO mixing ratio was as much as 65 pptv at 60 degrees N latitude at an altitude of 20 kilometers, and was enhanced over mid-latitude values by a factor of 3 to 5 at altitudes above 18 kilometers and by as much as a factor of 40 at altitudes below 17 kilometers. Levels of ClO and O(3) were highly correlated on all measured distance scales, and both showed an abrupt change in character at 54 degrees N latitude. The enhancement of ClO abundance north of 54 degrees N was most likely caused by low nitrogen dioxide levels in the flight path.     

Rainfall Enhancement by Dynamic Cloud Modification: Massive silver iodide seeding causes rainfall increases from single clouds over southern Florida

In summary, the following points are made: 1) There are essentially two approaches to seeding for rain inducement, static and dynamic. 2) The dynamic approach is effective in inducing growth and increasing precipitation from individually seeded convective clouds under specifiable conditions. 3) The static approach to seeding for precipitation increases is apparently not relevant to the summer cumuli of Florida and Missouri. 4) Regional seeding climatologies, including studies of natural freezing processes in convective clouds, should be completed before commencement of a seeding operation. 5) The results of a seeding operation are frequently better understood by stratification of the data, especially with respect to weather conditions. Precipitation increases from seeding are usually found under fair weather regimes with isolated showers, whereas decreases are often noted under naturally rainy conditions.