DISTRIBUTION OF THE XANTHOPHYLL LOROXANTHIN IN DESMIDS (CHAROPHYCEAE,CHLOROPHYTA)1

Forty-seven species of desmids, representing all four families, were examined for the presence of the xanthophyll loroxanthin by reverse-phase high-performance liquid chromatography. In the Desmidiaceae 28 of the 35 species examined possessed loroxanthin, and in the Mesotaeniaceae two of the six examined had loroxanthin present. All six species of the families Peniaceae and Closteriaceae examined possessed loroxanthin. Although the distribution of loroxanthin appears to be disjunct in the desmids and does not have strict taxonomic significance, it does follow a coherent pattern consistent with current ideas on desmid phylogeny. This pattern suggests that loroxanthin synthesis probably evolved once in the desmid lineage, with one or more subsequent reversals.     

Sex determination of Red-tailed Hawks (Buteo jamaicensis calurus) using DNA analysis and morphometrics

ABSTRACT.   Currently, the sex of Red-tailed hawks ( Buteo jamaicensis ) cannot be determined by in-hand methods. Males and females do not differ in plumage and overlap in size. We collected feather samples and morphological measurements from migrating birds at four sites in the western United States. Sex was determined for individual birds using sex-specific DNA markers and polymerase chain reaction was used to identify these DNA markers. Using discriminant function analysis, we created equations for determining the sex of Red-tailed Hawks using in-hand measurements based on the DNA-determined sexes. We formed two equations, one for adults that was 98% accurate, and one for hatch-year birds that was 97% accurate. The ability to determine the sex of western Red-tailed Hawks using morphological measurements will be useful to investigators examining possible intra- or intersexual differences.     

Changes in α-melanotropin in discrete brain areas of isolated aggressive mice

Adult male Swiss-Webster (NIH) mice were isolated for 6 weeks. Aggressive behavior was tested on 2 occasions, 24 hours apart. Immediately following the 2nd test period, aggressors and isolated non-aggressors (controls) were decapitated and α-MSH concentration was measured in discrete areas of the brain. Only the nucleus accumbens and preoptic lateralis of the aggressors, showed a higher level of α-MSH when compared to the controls. The significance of these changes is discussed.     

Link between the Membrane-Bound Pyridine Nucleotide Transhydrogenase and Glutathione-Dependent Processes in Rhodobacter sphaeroides

The presence of a glutathione-dependent pathway for formaldehyde oxidation in the facultative phototroph Rhodobacter sphaeroides has allowed the identification of gene products that contribute to formaldehyde metabolism. Mutants lacking the glutathione-dependent formaldehyde dehydrogenase (GSH-FDH) are sensitive to metabolic sources of formaldehyde, like methanol. This growth phenotype is correlated with a defect in formaldehyde oxidation. Additional methanol-sensitive mutants were isolated that contained Tn5 insertions in pntA, which encodes the alpha subunit of the membrane-bound pyridine nucleotide transhydrogenase. Mutants lacking transhydrogenase activity have phenotypic and physiological characteristics that are different from those that lack GSH-FDH activity. For example, cells lacking transhydrogenase activity can utilize methanol as a sole carbon source in the absence of oxygen and do not display a formaldehyde oxidation defect, as determined by whole-cell (13)C-nuclear magnetic resonance. Since transhydrogenase can be a major source of NADPH, loss of this enzyme could result in a requirement for another source for this compound. Evidence supporting this hypothesis includes increased specific activities of other NADPH-producing enzymes and the finding that glucose utilization by the Entner-Doudoroff pathway restores aerobic methanol resistance to cells lacking transhydrogenase activity. Mutants lacking transhydrogenase activity also have higher levels of glutathione disulfide under aerobic conditions, so it is consistent that this strain has increased sensitivity to oxidative stress agents like diamide, which are known to alter the oxidation reduction state of the glutathione pool. A model will be presented to explain the role of transhydrogenase under aerobic conditions when cells need glutathione both for GSH-FDH activity and to repair oxidatively damaged proteins.