The effects of dietary carotenoid supplementation and retinal carotenoid accumulation on vision-mediated foraging in the house finch

Background

For many bird species, vision is the primary sensory modality used to locate and assess food items. The health and spectral sensitivities of the avian visual system are influenced by diet-derived carotenoid pigments that accumulate in the retina. Among wild House Finches (Carpodacus mexicanus), we have found that retinal carotenoid accumulation varies significantly among individuals and is related to dietary carotenoid intake. If diet-induced changes in retinal carotenoid accumulation alter spectral sensitivity, then they have the potential to affect visually mediated foraging performance.

Methodology/Principal Findings

In two experiments, we measured foraging performance of house finches with dietarily manipulated retinal carotenoid levels. We tested each bird''s ability to extract visually contrasting food items from a matrix of inedible distracters under high-contrast (full) and dimmer low-contrast (red-filtered) lighting conditions. In experiment one, zeaxanthin-supplemented birds had significantly increased retinal carotenoid levels, but declined in foraging performance in the high-contrast condition relative to astaxanthin-supplemented birds that showed no change in retinal carotenoid accumulation. In experiments one and two combined, we found that retinal carotenoid concentrations predicted relative foraging performance in the low- vs. high-contrast light conditions in a curvilinear pattern. Performance was positively correlated with retinal carotenoid accumulation among birds with low to medium levels of accumulation (∼0.5–1.5 µg/retina), but declined among birds with very high levels (>2.0 µg/retina).

Conclusion/Significance

Our results suggest that carotenoid-mediated spectral filtering enhances color discrimination, but that this improvement is traded off against a reduction in sensitivity that can compromise visual discrimination. Thus, retinal carotenoid levels may be optimized to meet the visual demands of specific behavioral tasks and light environments.     

The discovery of potent and long-acting oral factor Xa inhibitors with tetrahydroisoquinoline and benzazepine P4 motifs

The discovery and evaluation of potent and long-acting oral sulfonamidopyrrolidin-2-one factor Xa inhibitors with tetrahydroisoquinoline and benzazepine P4 motifs are described. Unexpected selectivity issues versus tissue plasminogen activator in the former series were addressed in the later, delivering a robust candidate for progression towards clinical studies.     

Selective and dual action orally active inhibitors of thrombin and factor Xa

The synthetic entry to new classes of dual fXa/thrombin and selective thrombin inhibitors with significant oral bioavailability is described. This was achieved through minor modifications to the sulfonamide group in our potent and selective fXa inhibitor (E)-2-(5-chlorothien-2-yl)-N-{(3S)-1-[(1S)-1-methyl-2-(morpholin-4-yl)-2-oxoethyl]-2-oxopyrrolidin-3-yl}ethenesulfonamide and these observed activity changes have been rationalised using structural studies.     

Two clonal cell populations (mosaicism) in a 46,XY male with mucolipidosis II (I-cell disease)--an autosomal recessive disorder.

Cultured fibroblasts from a 46,XY male with an atypical form of mucolipidosis II (I-cell disease) had two distinct phenotypes. One population of these fibroblasts had the morphological and biochemical features characteristic of I-cell disease, while the remaining cells were indistinguishable from normal fibroblasts. Direct evidence that the patient was a mosaic, having two cell populations, was provided by the establishment of pure, stable clones of both wild type and I-cell fibroblasts from each of two biopsies obtained several months apart. Additionally, it was shown that the I-cell fibroblasts lacked UDP-N-acetylglucosamine:lysosomal enzyme N-acetylglucosaminylphosphotransferase while the morphologically normal cells contained levels of this enzyme just below or at the lower end of the normal range.     

A high risk twin study of combat-related PTSD comorbidity.

Combat-related posttraumatic stress disorder (PTSD) is highly comorbid with other mental disorders. However, the nature of the relationship between PTSD and other mental disorders remains unclear. A discordant high-risk twin design was used on data from a sub-sample of the male-male twin pair members of the Vietnam Era Twin Registry to examine whether patterns of comorbidity are consistent with a psychopathological response to combat exposure or reflect familial vulnerability to psychopathology. Mental disorders were assessed via the Mental Health Diagnostic Interview Schedule Version III - Revised. Discordant monozygotic within-pair comparisons revealed that PTSD probands had higher symptom counts and diagnostic prevalences of mood and anxiety disorders than their non-combat exposed co-twins. Monozygotic co-twins of PTSD probands had significantly more mood disorder symptoms than monozygotic co-twins of combat controls or dizygotic co-twins of veterans with PTSD. These findings suggest that a) major depression, generalized anxiety disorder and panic disorder are part of a post-combat response syndrome; b) a shared familial vulnerability also contributes to the association between PTSD and major depression, PTSD and dysthymia, and c) this shared vulnerability is mediated by genetic factors.     

Proteolytic enzymes of the K-1 strain of Streptomyces griseus obtained from a commercial preparation (Pronase). Purification and characterization of the carboxypeptidase.

We described earlier the facilitated purifications of the trypsin and aminopeptidase components present in Pronase (Vosbeck, K. D., Chow, K. -F., and Awad, W. M., Jr. (1973) J. Biol. Chem. 248, 6029-6034). A partially resolved protein mixture left over after one of the steps in that procedure was passed through a Sephadex G-75 column. By this means, a component with carboxypeptidase activity was separated from associated serine endopeptidases. Further purification of this exopeptidase to apparent homogeneity was acheived by refiltration through the same Sephadex column and by CM-cellulose chromatography. A single protein band was observed after acrylamide gel electrophoresis; analysis by sedimentation equilibrium using the meniscus depletion method gave a molecular weight of 30,300. This enzyme demonstrates activity against Nalpha-benzyloxycarbonylglycyl-L-leucine and hippuryl-D,L-phenyllactate; no activity was found against Nalpha-acetyl-L-tyrosine ethyl ester, Nalpha-benzoyl-D,L-arginine-p-nitroanilide, or L-leuckne-p-nitroanilide. The maximum activity lies between pH values of 7 and 8; the enzyme is stable between pH values of 6 and 10. At room temperature 1,10-phenanthroline inactivates the enzyme completely whereas EDTA has no effect. Of the many cations tested, only Co2+, Ni2+, or Zn2+ restores activity to the 1,10-phenanthroline-treated enzyme; Co2+ provided 3 times the native activity. The metal in the native protein was found to be zinc. These findings are similar to those recorded with bovine pancreatic carboxypeptidase A, and suggest the possibility that the present enzyme may ge genetically related to the mammalian protein, as in previously noted examples of homology of three Pronase endopeptidases to pancreatic serine enzymes.