Interhemispheric ice-sheet synchronicity during the Last Glacial Maximum

The timing of the last maximum extent of the Antarctic ice sheets relative to those in the Northern Hemisphere remains poorly understood. We develop a chronology for the Weddell Sea sector of the East Antarctic Ice Sheet that, combined with ages from other Antarctic ice-sheet sectors, indicates that the advance to and retreat from their maximum extent was within dating uncertainties synchronous with most sectors of Northern Hemisphere ice sheets. Surface climate forcing of Antarctic mass balance would probably cause an opposite response, whereby a warming climate would increase accumulation but not surface melting. Our new data support teleconnections involving sea-level forcing from Northern Hemisphere ice sheets and changes in North Atlantic deep-water formation and attendant heat flux to Antarctic grounding lines to synchronize the hemispheric ice sheets.     

Basaltic rocks analyzed by the Spirit Rover in Gusev Crater

The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain 相似文献   

Effects of Pioglitazone on Insulin Sensitivity and Serum Lipids in Obese Cats

Background

Pioglitazone is a thiazolidinedione (TZD) insulin sensitizer approved for use in human type 2 diabetes mellitus. Therapeutic options for diabetes in cats are limited.

Objective

To evaluate the effects of pioglitazone in obese cats, which are predisposed to insulin resistance, to assess its potential for future use in feline diabetes mellitus.

Animals

A total of 12 obese purpose‐bred research cats (6 neutered males and 6 spayed females, 5–7 years of age, weighing 5.4–9.8 kg).

Methods

Randomized, placebo‐controlled 3‐way crossover study. Oral placebo or pioglitazone (Actos™; 1 or 3 mg/kg) was administered daily for 7‐week periods, with IV glucose tolerance testing before and after each period.

Results

Three mg/kg pioglitazone significantly improved insulin sensitivity (geometric mean [95% CI] 0.90 [0.64–1.28] to 2.03 [1.49–2.78] min ⁻¹pmol⁻¹L; P = .0014 versus change with placebo), reduced insulin area under the curve during IVGTT (geometric mean [range] 27 [9–64] to 18 [6–54] min∙nmol/L; P = .0031 versus change with placebo), and lowered serum triglyceride (geometric mean [range] 71 [29–271] to 48 [27–75] mg/dL; P = .047 versus change with placebo) and cholesterol (geometric mean [range] 187 [133–294] to 162 [107–249] mg/dL; P = .0042 versus change with placebo) concentrations in the obese cats. No adverse effects attributable to pioglitazone were evident in the otherwise healthy obese cats at this dosage and duration.

Conclusions and Clinical Importance

Results of this study support a positive effect of pioglitazone on insulin sensitivity and lipid metabolism in obese cats, and suggest that further evaluation of the drug in cats with diabetes mellitus or other metabolic disorders might be warranted.     

Sterol requirement of juvenile lobsters, Homarus sp.

Juvenile lobsters were fed purified or unrefined diets in which the qualitative and quantitative sterol composition varied. Dietary cholesterol was required. A level of dietary cholesterol as low as 0.12% (dry weight) in a purified diet was satisfactory for normal growth and survival. No significant increases in growth were observed when lobsters were fed unrefined diets with cholesterol levels ranging from 0.19 to 0.59% (dry weight). Total cholesterol content of the whole body tissue lipid ranged from 0.012 to 0.046% (wet weight), lowest values being characteristically associated with those animals fed purified diets virtually devoid of cholesterol. Serum sterol levels were similar except for reduced levels associated with the sterol-free diet.Total replacement of cholesterol with a mixture of phytosterols composed primarily of β-sitosterol did not yield good growth and survival. Phytosterols composed large proportions of the total body sterols of those lobsters fed diets containing phytosterols exclusively. At least a portion and possibly all of the sterol requirement of juvenile lobsters is specific for cholesterol.     

Eradication of potato virus X from potato by ribavirin treatment of cultured potato shoot tips

Ribavirin treatment of cultured potato shoot tips was tested as a means of eradicating potato virus X (PVX) from two potato cultivars. Shoot tips were cultured on liquid medium containing 0, 1, 10 or 100μg/ml ribavirin. Cultures were evaluated periodically for viability, and scored for vigor on a relative growth scale. Developed plantlets were assayed for PVX by transmission tests toGomphrena globosa. Ribavirin treatment was phytotoxic at all tested concentrations, and lethal to all cultivars treated at 100 μg/ml. Treatment also delayed plantlet development by up to 2 months at 1 and 10 μg/ml as compared with nontreated controls. PVX assays indicated that 80 and 83% of the plantlets were free of PVX following treatment with 10 μg/ml for cultivars Russet Burbank and Red McClure, respectively. Five and 6% of the plantlets developed from the 1 μg/ml treatment were PVX-free, whereas 0 and 2% of the controls were PVX-free for the same cultivars. Six to 8 months were required to develop plants from shoot-tip cultures treated with 10 μg/ml ribavirin.     

Effects of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on abundance and activity of ammonia oxidizers in soil

Biology and Fertility of Soils - Recent evidence from several environments suggest that besides autotrophic ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) are also able to...