Effects of gonadal hormones on the lipid contents of the frogRana esculenta

Summary The effects of exogenous gonadal hormones on the lipid contents of the liver and ovary and also on water content in the frog,Rana esculenta, were studied. Estrogen treatment significantly enhanced, whereas testosterone treatment reduced, the lipid and cholesterol contents. Water content of the frogs increased significantly after treatment by either hormone.Acknowledgment. I wish to thank Dr Hussain Al-Adhub, College of Science for providing all necessary laboratory facillities. Present address: Physiology Laboratory, Department of Zoology, Patna University, Patna-80005, Bihar (India).     

Genetic variation in human NPY expression affects stress response and emotion

Understanding inter-individual differences in stress response requires the explanation of genetic influences at multiple phenotypic levels, including complex behaviours and the metabolic responses of brain regions to emotional stimuli. Neuropeptide Y (NPY) is anxiolytic and its release is induced by stress. NPY is abundantly expressed in regions of the limbic system that are implicated in arousal and in the assignment of emotional valences to stimuli and memories. Here we show that haplotype-driven NPY expression predicts brain responses to emotional and stress challenges and also inversely correlates with trait anxiety. NPY haplotypes predicted levels of NPY messenger RNA in post-mortem brain and lymphoblasts, and levels of plasma NPY. Lower haplotype-driven NPY expression predicted higher emotion-induced activation of the amygdala, as well as diminished resiliency as assessed by pain/stress-induced activations of endogenous opioid neurotransmission in various brain regions. A single nucleotide polymorphism (SNP rs16147) located in the promoter region alters NPY expression in vitro and seems to account for more than half of the variation in expression in vivo. These convergent findings are consistent with the function of NPY as an anxiolytic peptide and help to explain inter-individual variation in resiliency to stress, a risk factor for many diseases.     

Isolation and quantification of soluble Alzheimer's beta-peptide from biological fluids.

Cerebral deposition of the beta-amyloid peptide (A beta) is an invariant feature of Alzheimer's disease. Since the original isolation and characterization of A beta (ref. 1) and the subsequent cloning of its precursor protein, no direct evidence for the actual production of discrete A beta has been reported. Here we investigate whether A beta is present in human biological fluids using antibodies specific for an epitope within A beta that spans the site of normal constitutive cleavage. These antibodies were used to construct a sandwich-type enzyme-linked immunosorbent assay that detects A beta in cerebrospinal fluid, plasma and conditioned medium of human mixed-brain cells grown in vitro (see also ref. 14). By affinity chromatography, we have purified and sequenced A beta and a novel A beta fragment from human cerebrospinal fluid and conditioned medium of human mixed-brain cell cultures. These findings demonstrate that A beta is produced and released both in vivo and in vitro. These observations offer new opportunities for developing diagnostic tests for Alzheimer's disease and therapeutic strategies aimed at reducing the cerebral deposition of A beta.     

Certain biochemical changes in the ovary of a migratory bird, Calandrella acutirostris tibetana.

The changes in the ovarian cholesterol, glycogen and ascorbic acid of Bagheri, Calandrella acutirostris tibetana, during its non-breeding and breeding periods were studied. There was a significant increase in all the 3 biochemical constituents during the breeding period.     

Development of longitudinal retraction of carotid arteries in neonatal dogs.

Longitudinal retraction of carotid arteries, was examined in 105 neonatal puppies as a measure of longitudinal traction. Percent vessel retraction increased linearly with age. This was attributed to stretching of the vessels by growth and to changes in connective tissue composition. The mechanical significance of artery retraction was discussed.     

Chromosome preparations of opossum leucocytes

Résumé C'est la première fois que l'on décrit une technique pour la préparation des chromosomes de leucocytes d'opossum. Cette technique a l'avantage d'être simple et elle permet en outre de préciser les détails morphologiques de certains chromosomes de l'opossum. Par exemple, les chromosomesX de la femelle de l'opossum laineux (Caluromys derbianus) sont aisément identifiés comme étant la plus petite paire submétacentrique du complément.

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Supported in part by grants from U. S. Public Health Service (No. HD 00033-02) and Baylor University College of Medicine General Research Grant (No. P-66-6) and a grant from the James Picker Foundation.     

Invertase activity in the midgut ofSarcophaga ruficornis andMusca domestica (diptera: Insecta)

Summary The pH for the optimum activity of the midgut invertase was 5.5 in the adults ofS. ruficornis, 6.0 in its larvae and adults ofM. domestica and 6.5 in the larvae of the latter fly. The optimum temperature was 50°C. Enzyme activity was retarded by the addition of glucose and fructose.     

Dissecting the architecture of a quantitative trait locus in yeast

Most phenotypic diversity in natural populations is characterized by differences in degree rather than in kind. Identification of the actual genes underlying these quantitative traits has proved difficult. As a result, little is known about their genetic architecture. The failures are thought to be due to the different contributions of many underlying genes to the phenotype and the ability of different combinations of genes and environmental factors to produce similar phenotypes. This study combined genome-wide mapping and a new genetic technique named reciprocal-hemizygosity analysis to achieve the complete dissection of a quantitative trait locus (QTL) in Saccharomyces cerevisiae. A QTL architecture was uncovered that was more complex than expected. Functional linkages both in cis and in trans were found between three tightly linked quantitative trait genes that are neither necessary nor sufficient in isolation. This arrangement of alleles explains heterosis (hybrid vigour), the increased fitness of the heterozygote compared with homozygotes. It also demonstrates a deficiency in current approaches to QTL dissection with implications extending to traits in other organisms, including human genetic diseases.