Band 3 protein of the red cell membrane of the llama: crosslinking and cleavage of the cytoplasmic domain

Comparative studies were done on the cytoplasmic domain of the band 3 protein in the red cell membranes of the the human and the llama. Two approaches were used: crosslinking with o-phenanthroline/CuSO4, and cleavage with 2-nitro-5-thiocyanobenzoate. o-Phenanthroline/CuSO4 crosslinks the band 3 polypeptide chains in the human; in contrast band 3 in the llama is minimally crosslinked by this agent. 2-Nitro-5-thiocyanobenzoate cleaves band 3 in the human into a 23,000-dalton fragment; a similar fragment is not generated from the llama band 3. These studies show that the cysteine residue located 23,000 daltons from the N-terminus of band 3 in the human involved in these reactions is unavailable for crosslinking and cleavage in the llama. Species differences in the cytoplasmic domain of band 3 may contribute to the unusual resistance of llama red cells to osmotic, chemical and physically-induced deformation.     

Active state-like conformational elements in the beta2-AR and a photoactivated intermediate of rhodopsin identified by dynamic properties of GPCRs

G-Protein-coupled receptors (GPCRs) adopt various functionally relevant conformational states in cell signaling processes. Recently determined crystal structures of rhodopsin and the beta 2-adrenergic receptor (beta 2-AR) offer insight into previously uncharacterized active conformations, but the molecular states of these GPCRs are likely to contain both inactive and active-like conformational elements. We have identified conformational rearrangements in the dynamics of the TM7-HX8 segment that relate to the properties of the conserved NPxxY(x)5,6F motif and show that they can be used to identify active state-like conformational elements in the corresponding regions of the new structures of rhodopsin and the beta 2-AR.     

High-nitrogen compost as a medium for organic container-grown crops

Compost was tested as a medium for organic container-grown crops. Nitrogen (N) loss during composting of separated cow manure (SCM) was minimized using high C/N (wheat straw, WS; grape marc, GM) or a slightly acidic (orange peels, OP) additives. N conservation values in the resultant composts were 82%, 95% and 98% for GM-SCM, OP-SCM and WS-SCM, respectively. Physical characteristics of the composts were compatible with use as growing media. The nutritional contribution of the composts was assessed using cherry tomato (Lycopersicon esculantum Mill.) and by means of incubation experiments. Media were either unfertilized or fertilized with guano (sea-bird manure). Plant responses suggest that N availability is the main variable affecting growth. Unfertilized OP-SCM and WS-SCM supplied the N needed for at least 4 months of plant growth. Root-galling index (GI) of tomato roots and number of eggs of the nematode Meloidogyne javanica were reduced by the composts, with the highest reduction obtained by OP-SCM and WS-SCM, at 50% concentrations. These composts, but not peat, reduced the incidence of crown and root-rot disease in tomato as well as the population size of the causal pathogen, Fusarium oxysporum f. sp. radicis-lycopersici.     

A genetic screen for top3 suppressors in Saccharomyces cerevisiae identifies SHU1, SHU2, PSY3 and CSM2: four genes involved in error-free DNA repair

Helicases of the RecQ family and topoisomerase III are evolutionarily conserved proteins important for maintenance of genome stability. In Saccharomyces cerevisiae, loss of the TOP3 gene, encoding topoisomerase III, results in a phenotype of slow growth, DNA damage sensitivity, meiotic defects, and hyperrecombination. The sole RecQ helicase in budding yeast, Sgs1, interacts with Top3 both physically and genetically, and the two proteins are thought to act in concert in vivo. Much recent genetic and biochemical evidence points to the role of RecQ helicases and topoisomerase III in regulating homologous recombination (HR) during DNA replication. Previously, we found that mutations in HR genes partially suppress top3 slow growth. Here, we describe the analysis of four additional mutational suppressors of top3 defects: shu1, shu2, psy3, and csm2. These genes belong to one epistasis group and their protein products interact with each other, strongly suggesting that they function as a complex in vivo. Their mutant phenotype indicates that they are important for error-free repair of spontaneous and induced DNA lesions, protecting the genome from mutation. These mutants exhibit an epistatic relationship with rad52 and show altered dynamics of Rad52-YFP foci, suggesting a role for these proteins in recombinational repair.     

Body proportions in ancient Andeans from high and low altitudes

Living human populations from high altitudes in the Andes exhibit relatively short limbs compared with neighboring groups from lower elevations as adaptations to cold climates characteristic of high-altitude environments. This study compares relative limb lengths and proportions in pre-Contact human skeletons from different altitudes to test whether ecogeographic variation also existed in Andean prehistory. Maximum lengths of the humerus, radius, femur, and tibia, and femoral head breadth are measured in sex-specific groups of adult human skeletons (N = 346) from the central (n = 80) and the south-central (n = 123) Andean coasts, the Atacama Desert at 2,500 m (n = 102), and the southern Peruvian highlands at 2,000-3,800 m (n = 41). To test whether limb lengths vary with altitude, comparisons are made of intralimb proportions, limb lengths against body mass estimates derived from published equations, limb lengths against the geometric mean of all measurements, and principal component analysis. Intralimb proportions do not statistically differ between coastal groups and those from the Atacama Desert, whereas intralimb proportions are significantly shorter in the Peruvian highland sample. Overall body size and limb lengths relative to body size vary along an altitudinal gradient, with larger individuals from coastal environments and smaller individuals with relatively longer limbs for their size from higher elevations. Ecogeographic variation in relation to climate explains the variation in intralimb proportions, and dietary variation may explain the altitudinal cline in body size and limb lengths relative to body size. The potential effects of gene flow on variation in body proportions in Andean prehistory are also explored.