Abundance of mRNAs encoding HMG1/HMG2 class high-mobility-group DNA-binding proteins are differentially regulated in cotyledons of Pharbitis nil

The abundance of an mRNA encoding an HMG1/2 protein from Pharbitis nil (HMG1) has been previously shown to be regulated by light and an endogenous rhythm in cotyledons. A second Pharbitis nil HMG cDNA (HMG2) was characterized. The sequence of HMG2 was 82% and 86% identical to HMG1 at the nucleotide and amino acid level, respectively. As with HMG1, HMG2 mRNA was detected in all vegetative tissues and was most abundant in roots. However, unlike HMG1, HMG2 mRNA abundance did not increase upon transfer of cotyledons to darkness and did not exhibit regulation by an endogenous circadian rhythm when maintained in continuous darkness over a 68 h period. Similarly, while the abundance of HMG1 mRNA during a dark period that induced photoperiodically controlled flowering was dramatically affected by brief light exposure (night break), this treatment had no effect on HMG2 mRNA abundance. Collectively, these data are consistent with a role of HMG1 in contributing to the circadian-regulated and/or dark-regulated gene expression with constitutive expression of HMG2 playing a housekeeping role in the general regulation of gene expression in Pharbitis nil cotyledons.     

Preadipocyte Recruitment in Stromal Vascular Cultures After Depletion of Committed Preadipocytes by Immunocytotoxicity

Glucocorticoids or the glucocorticoid analog dexamethasone (DEX) enhances the differentiation of preadipocytes in the presence of insulin and influences preadipocyte proliferation. The purpose of the present study was to determine if DEX can induce the recruitment of preadipocytes. Using monoclonal antibodies for complement-mediated cytotoxicity, preadipocytes were removed from porcine stromal vascular (S-V) cell cultures. Our experiments demonstrated for the first time that after removal of preadipocytes by cytotoxicity, preadipocytes or fat cells could be induced by DEX or DEX plus insulin but not by insulin alone. However, many more fat cells were induced (258 ± 15/unit area) when DEX was added with fetal bovine serum (FBS) followed with insulin treatment, compared to DEX with insulin (21.3 ± 5.1/ unit area) after removal of preadipocytes. Immunocyto-chemistry with AD-3, a preadipocyte marker, showed that DEX with FBS for 3 days after seeding (i.e., the proliferation phase) produced many more preadipocytes (AD-3 positive, 223 ± 45/unit area) than FBS alone (10.5 ± 1.4/unit area). Bromodeoxyuridine (BrdU) incorporation assays demonstrated that the efficiency of DEX with FBS (i.e., during proliferation) was mitosis dependent. Accordingly, we conclude that: porcine S-V cultures contain preadipocytes at different stages of differentiation and that DEX induced early preadipocyte differentiation depends on mitosis.     

Reaction of ozone with phospholipid vesicles and human erythrocyte ghosts

Phospholipid vesicles (unilamellar) and liposomes (multilamellar) made from egg phosphatidylcholine reacted similarly with ozone, producing hydrogen peroxide and malonaldehyde. On the basis of amount of ozone reacted, there was a 20% yield of hydrogen peroxide and 2.4% yield of malonaldehyde. The reactivity of the egg phosphatidylcholine membranes was a function of exposed membrane surface area. Large amounts of ozone caused no change in erythrocyte ghost phospholipid, fatty acid, or cholesterol composition. Thiobarbituric acid-positive material and conjugated dienes were present in very small quantities, suggesting some lipid oxidation which was below the limits of chromatographic detection. Ozone inhibited glyceraldehyde 3-phosphate dehydrogenase more than (Na⁺ + K⁺) adenosine triphosphate in exposed unsealed erythrocyte ghosts. The (Na⁺ + K⁺) adenosine triphosphatase activity sensitive to ozone was the ouabain-insensitive activity. Acetylcholinesterase activity was not significantly inhibited.     

Somatic Expression and Autosomal Inheritance of Phosphoglycerate Kinase B in Kangaroos

The PGK-B isozyme, currently known as PGK-2 in the mouse nomenclature, is the predominant PGK isozyme in mammalian sperm. In many species it is detectable only in sperm, in spermatogenic testes and in epididymides containing sperm. In this paper, we provide evidence that some kangaroo species express low PGK-B activity in somatic tissues, in addition to high activity in testes. Three kangaroo species, M. rufogriseus, M. robustus and M. giganteus, exhibit polymorphism of PGK-B. Breeding data support the hypothesis of autosomal co-dominant inheritance, as is the case in mice. Population data for the three polymorphisms are discussed. PGK-B is not detectable in somatic tissues or spermatogenic testis extracts of monotreme mammals, birds or lizards; it is probably restricted to therian mammals.     

Field evaluation of tolerance to Tobacco streak virus in sunflower germplasm,and observations of seasonal disease spread

Strong statistical evidence was found for differences in tolerance to natural infections of Tobacco streak virus (TSV) in sunflower hybrids. Data from 470 plots involving 23 different sunflower hybrids tested in multiple trials over 5 years in Australia were analysed. Using a Bayesian Hierarchical Logistic Regression (BHLR) model for analysis provided: (a) a rigorous method for investigating the relative effects of hybrid, seasonal rainfall and proximity to inoculum source on the incidence of severe TSV disease; (b) a natural method for estimating the probability distributions of disease incidence in different hybrids under historical rainfall conditions; and (c) a method for undertaking all pairwise comparisons of disease incidence between hybrids while controlling the familywise error rate without any drastic reduction in statistical power. The tolerance identified in field trials was effective against the main TSV strain associated with disease outbreaks, TSV‐parthenium. Glasshouse tests indicate this tolerance to also be effective against the other TSV strain found in central Queensland, TSV‐crownbeard. The use of tolerant germplasm is critical to minimise the risk of TSV epidemics in sunflower in this region. We found strong statistical evidence that rainfall during the early growing months of March and April had a negative effect on the incidence of severe infection with greatly reduced disease incidence in years that had high rainfall during this period.     

Modeling Sustainability of Arctic Communities: An Interdisciplinary Collaboration of Researchers and Local Knowledge Holders

How will climate change affect the sustainability of Arctic villages over the next 40 years? This question motivated a collaboration of 23 researchers and four Arctic communities (Old Crow, Yukon Territory, Canada; Aklavik, Northwest Territories, Canada; Fort McPherson, Northwest Territories, Canada; and Arctic Village, Alaska, USA) in or near the range of the Porcupine Caribou Herd. We drew on existing research and local knowledge to examine potential effects of climate change, petroleum development, tourism, and government spending cutbacks on the sustainability of four Arctic villages. We used data across eight disciplines to develop an Arctic Community Synthesis Model and a Web-based, interactive Possible Futures Model. Results suggested that climate warming will increase vegetation biomass within the herd’s summer range. However, despite forage increasing, the herd was projected as likely to decline with a warming climate because of increased insect harassment in the summer and potentially greater winter snow depths. There was a strong negative correlation between hypothetical, development-induced displacement of cows and calves from utilized calving grounds and calf survival during June. The results suggested that climate warming coupled with petroleum development would cause a decline in caribou harvest by local communities. Because the Synthesis Model inherits uncertainties associated with each component model, sensitivity analysis is required. Scientists and stakeholders agreed that (1) although simulation models are incomplete abstractions of the real world, they helped bring scientific and community knowledge together, and (2) relationships established across disciplines and between scientists and communities were a valuable outcome of the study. Additional project materials, including the Web-based Possible Futures Model, are available at http://www.taiga.net/sustain.     

The effects of amino acid supplementation on muscular performance during resistance training overreaching

The purpose of this study was to examine the effects of amino acid supplementation on muscular strength, power, and high-intensity endurance during short-term resistance training overreaching. Seventeen resistance-trained men were randomly assigned to either an amino acid (AA) or placebo (P) group and underwent 4 weeks of total-body resistance training consisting of two 2-week phases of overreaching (phase 1: 3 x 8-12 repetitions maximum [RM], 8 exercises; phase 2: 5 x 3-5 RM, 5 exercises). Muscle strength, power, and high-intensity endurance were determined before (T1) and at the end of each training week (T2-T5). One repetition maximum squat and bench press decreased at T2 in P (5.2 and 3.4 kg, respectively) but not in AA, and significant increases in 1 RM squat and bench press were observed at T3-T5 in both groups. A decrease in the ballistic bench press peak power was observed at T3 in P but not AA. The fatigue index during the 20-repetition jump squat assessment did not change in the P group at T3 and T5 (fatigue index = 18.6 and 18.3%, respectively) whereas a trend for reduction was observed in the AA group (p = 0.06) at T3 (12.8%) but not T5 (15.2%; p = 0.12). These results indicate that the initial impact of high-volume resistance training overreaching reduces muscle strength and power, and it appears that these reductions are attenuated with amino acid supplementation. In addition, an initial high-volume, moderate-intensity phase of overreaching followed by a higher intensity, moderate-volume phase appears to be very effective for enhancing muscle strength in resistance-trained men.