Melatonin receptors and signal transduction during development in Siberian hamsters (Phodopus sungorus).

Maternal melatonin communicates daylength information to the fetus in Siberian hamsters. Fetal sensitivity to melatonin declines near birth. In this report, we describe melatonin receptor distribution and a second messenger response to melatonin in Siberian hamsters during the perinatal period. The sites of high-affinity 2-[125I]iodomelatonin ([125I]MEL) binding were generally similar throughout the perinatal period. The non-hydrolyzable GTP analog, guanosine-5'-O-(3-thiotriphosphate) (100 microM) inhibited [125I]MEL binding at each age, suggesting the melatonin receptors are associated with guanine nucleotide binding proteins (G proteins). Furthermore, melatonin (10 nM) inhibited forskolin-stimulated cAMP accumulation in median eminence/pars tuberalis (ME/PT) explants as early as 4 days before birth, when sensitivity to melatonin in vivo is high. The cAMP regulatory system appeared disrupted on the day of birth, in that forskolin (10 microM) stimulation of cAMP accumulation was reduced, and melatonin did not inhibit cAMP accumulation stimulated by forskolin. A higher forskolin dose (100 microM) elevated cAMP levels more clearly on the day of birth, and melatonin inhibited forskolin-stimulated cAMP accumulation. These results suggest that the decreased physiological responsiveness to melatonin at the end of gestation may be due to alterations in the cAMP regulatory system.     

Isolation and characterization of an olfactory mutant in Drosophila with a chemically specific defect.

A Drosophila mutant was isolated and shown to exhibit defective response to the chemical odorant benzaldehyde in two distinctly different behavioral assays. The defect exhibited chemical specificity: response to three other chemicals was normal. The mutant also showed abnormalities in pigmentation and fertility. Genetic mapping and complementation analysis provide evidence that the olfactory, pigmentation, and fertility defects arise as a result of a lesion at the pentagon locus. The specificity of the olfactory defect suggests the possibility that the mutation may define a molecule required in reception, transduction, or processing of a specific subset of chemical information in the olfactory system.     

Health locus of control and participation in physical activity

Abstract The purpose of this study was to determine the physical activity participation patterns of college students when defined by their Health Locus of Control orientation. One thousand thirty-three college-aged students completed the Wellness Activity Profile, a questionnaire that yielded data on Health Locus of Control and self-reported frequency of participation in physical activities. Discriminant analyses indicated that the combination of physical activities associated with internally and externally oriented students were different for both males and females. Participation in high caloric expenditure activities was more frequent among internal subjects (Male: bicycling, volleyball, other individual sports, and snorkel/scuba diving; Female: basketball, weight training, tennis, fast walking/jogging/running, and judo/karate), while low caloric expenditure activities were associated with an external orientation (Male: baseball/softball, sailing, fishing, golf, and other recreational sports; Female: track and field jumping and fishing).     

The nucleophosmin-anaplastic lymphoma kinase fusion protein induces c-Myc expression in pediatric anaplastic large cell lymphomas

The majority of pediatric anaplastic large cell lymphomas (ALCLs) carry the t(2;5)(p23;q35) chromosomal translocation that juxtaposes the dimerization domain of nucleophosmin with anaplastic lymphoma kinase (ALK). The nucleophosmin-ALK fusion induces constitutive, ligand-independent activation of the ALK tyrosine kinase leading to aberrant activation of cellular signaling pathways. To study the early consequences of ectopic ALK activation, a GyrB-ALK fusion was constructed that allowed regulated dimerization with the addition of coumermycin. Expression of the fusion protein caused a coumermycin-dependent increase in cellular tyrosine phosphorylation and c-Myc immunoreactivity, which was paralleled by a rise in c-myc RNA. To assess the clinical relevance of this observation, c-Myc expression was determined in pediatric ALK-positive and -negative lymphomas. Co-expression of c-Myc and ALK was seen in tumor cells in 15 of 15 (100%) ALK-positive ALCL samples, whereas no expression of either ALK or c-Myc was seen in six of six cases of ALK-negative T-cell lymphoma. C-Myc may be a downstream target of ALK signaling and its expression a defining characteristic of ALK-positive ALCLs.     

Pattern of Sequence Variation Across 213 Environmental Response Genes

To promote the clinical and epidemiological studies that improve our understanding of human genetic susceptibility to environmental exposure, the Environmental Genome Project (EGP) has scanned 213 environmental response genes involved in DNA repair, cell cycle regulation, apoptosis, and metabolism for single nucleotide polymorphisms (SNPs). Many of these genes have been implicated by loss-of-function mutations associated with severe diseases attributable to decreased protection of genomic integrity. Therefore, the hypothesis for these studies is that individuals with functionally significant polymorphisms within these genes may be particularly susceptible to genotoxic environmental agents. On average, 20.4 kb of baseline genomic sequence or 86% of each gene, including a substantial amount of introns, all exons, and 1.3 kb upstream and downstream, were scanned for variations in the 90 samples of the Polymorphism Discovery Resource panel. The average nucleotide diversity across the 4.2 MB of these 213 genes is 6.7 × 10^-4, or one SNP every 1500 bp, when two random chromosomes are compared. The average candidate environmental response gene contains 26 PHASE inferred haplotypes, 34 common SNPs, 6.2 coding SNPs (cSNPs), and 2.5 nonsynonymous cSNPs. SIFT and Polyphen analysis of 541 nonsynonymous cSNPs identified 57 potentially deleterious SNPs. An additional eight polymorphisms predict altered protein translation. Because these genes represent 1% of all known human genes, extrapolation from these data predicts the total genomic set of cSNPs, nonsynonymous cSNPs, and potentially deleterious nonsynonymous cSNPs. The implications for the use of these data in direct and indirect association studies of environmentally induced diseases are discussed.     

Mosquito densonucleosis viruses cause dramatically different infection phenotypes in the C6/36 Aedes albopictus cell line

Mosquito densoviruses generally establish persistent infections in mosquito cell lines including the C6/36 Aedes albopictus cell line. In contrast, the closely related Haemagogus equinus densovirus (HeDNV) causes dramatic cytopathic effects in the C6/36 Aedes albopictus cell line. Infection of C6/36 cells by HeDNV causes internucleosomal fragmentation of host chromosomal DNA, changes in cellular morphology (membrane budding, apoptotic bodies), caspase activation and exposure of phosphatidylserine on the cellular membrane. This is accompanied by a higher rate of infection and more vigorous production of virus in these cells. These observations are consistent with the induction of apoptosis during infection. In contrast, expression of AeDNV proteins in C6/36 cells does not cause obvious cytopathic effects although NS1 expression causes accumulation of cells in G2 phase. C6/36 cells persistently infected with AeDNV were not protected from superinfection with HeDNV. Thus, there does not seem to be an antiviral state induced by AeDNV persistent infection.     

Comparison of in vitro and in vivo alpha/beta ratios for prostate cancer

Parallel in vitro and in vivo studies provide insight into the relationship between clinical response and intrinsic cellular radiosensitivity and may aid in the development of predictive assays. Compilations of radiosensitivity parameters from in vitro experiments can also be used to examine the potential effectiveness of alternative or new treatment plan designs until enough clinical data become available to directly estimate the requisite radiosensitivity parameters. In this work, survival data for six prostate cancer cell lines (ten datasets total) have been extracted from the literature and re-analysed using the linear-quadratic (LQ) survival model. The paired bootstrap technique for regression is used to compute 95% confidence intervals for the estimated radiosensitivity parameters. LQ radiosensitivity parameters derived from the in vitro data are then compared to radiosensitivity parameters derived from clinical data for prostate cancer. Estimates of alpha range from 0.09 to 0.35 Gy(-1) (all cell lines), and the alpha/beta ratio ranges from 1.09 to 6.29 Gy (all cell lines). Point estimates of the repair half-time (PPC-1, TSU-Pr1, PC-3 and DU-145 cell lines) range from 5.7 to 8.9 h (95% confidence interval from 0.26 h to 10.7 h). Differences in the radiosensitivity parameters determined from the data reported by different laboratories are as large as or larger than the differences in radiosensitivity parameters observed among the various prostate cell lines. The reported studies demonstrate that even seemingly small corrections for dose rate effects, such as those expected in high dose rate (HDR) experiments, can sometimes have a significant impact on estimates of alpha and alpha/beta. By neglecting dose rate effects in the analysis of HDR experiments, estimates of the alpha/beta, ratio may be too high by factors as large as 1.3 to 6.2. The half-time for repair derived from the in vitro experiments appears significantly larger (slower repair rate) than estimates derived from the clinical data. However, the prostate radiosensitivity parameters alpha and alpha/beta may be approximately the same in vitro and in vivo. Most of the in vitro data are consistent with an alpha/beta ratio for prostate cancer less than 3 or 4 Gy.     

Comparison of antiinflammatory and antiallergic drugs in the melittin- and D49 PLA2-induced mouse paw edema models

Melittin (MLT) (10 g/paw) and D49 (0.4 g/paw) were injected into the hind paw of male CD-1 mice and elicited 70–80% of maximal paw edema responses at 60 and 30 min after injection, respectively. D49 paw edema was significantly inhibited by anti-histamine/serotonin agents, a PAF antagonist, a PLA₂ inhibitor, and some but not all 5-LO and CO inhibitors, indicating that this edema is produced by several classes of inflammatory mediators with mast cell degranulation apparently playing a major role. In contrast, MLT paw edema was not inhibited effectively using the same pharmacological agents except theophylline, suggesting it was elicited via a different sequence of inflammatory events. In summary, D49 and MLT paw edema models were found to be ineffective models to identify experimental PLA₂ compounds in our laboratory.     

Rapid,non-genomic actions of progesterone and estradiol on steady-state calcium and resting calcium influx in lens epithelial cells

The effects of steroids on the steady-state intracellular [Ca(2+)] ([Ca(2+)](i)) and resting Ca(2+) influx in Fura-2-loaded bovine lens epithelial cells were examined to identify potential rapid, non-genomic actions. When administered in the presence of 1-2 mM extracellular Ca(2+) ([Ca(2+)](o)), 100 micro M progesterone produced large (up to 12-fold) and transient (5 min) increases in [Ca(2+)](i). These effects were abolished in EGTA-containing solutions, and were associated with large increases in the rate at which extracellularly administered Mn(2+) quenched the intracellular Fura signal. Lower concentrations of progesterone (10-100 micro M) produced smaller increases in [Ca(2+)](i) that were concentration dependent, and 17beta-estradiol induced large, rapid and brief increases in [Ca(2+)](i) at 100 nM and smaller oscillations in [Ca(2+)](i) at 10 nM. In cells pretreated with thapsigargin, 100 micro M progesterone produced slower increases in [Ca(2+)](i) that were maintained for several minutes. These results demonstrate rapid non-genomic actions of progesterone and estradiol on resting Ca(2+) influx and [Ca(2+)](i) that may involve specific interactions with a recently discovered steroid-binding protein in the plasma membrane of lens epithelial cells.