Extracellular Events Induced by γ-Hydroxybutyrate in Striatum: A Microdialysis Study

The modification of dopamine release and accumulation induced by gamma-hydroxybutyrate (GHB) was studied using both striatal slices and in vivo microdialysis of caudate-putamen. GHB inhibited dopamine release for approximately 5-10 min in vitro, and this was associated with an accumulation of dopamine in the tissue. Subsequently, there was an increase in dopamine release. In the microdialysis experiments, low doses of GHB inhibited dopamine release, whereas higher doses strongly increased release; the initial decrease seen in slices could not be detected in vivo. Thus, GHB had a biphasic effect on the release of dopamine: An initial decrease in the release of transmitter was followed by an increase. A time-dependent biphasic effect was observed when GHB was added to brain slices, and a dose-dependent biphasic effect was seen in dialysate after systemic administration of GHB. Naloxone blocked GHB-induced dopamine accumulation and release both in vitro and in vivo. GHB also increased the release of opioid-like substances in the striatum. A specific antagonist of GHB receptors completely blocked both the dopamine response and the release of opioid-like substances. These data suggest that GHB increases dopamine release via specific receptors that may modulate the activity of opioid interneurons.     

Isolation of DNA markers informative in purebred dog families by genomic representational difference analysis (gRDA)

Genomic Representational Difference Analysis (gRDA) is a subtractive DNA method to clone the differences between two related genomes, called tester and driver. We have evaluated this method to obtain polymorphic DNA markers for pedigree dogs. Amplified size-selected genomic restriction fragments (amplicons) of two dog littermates were repeatedly hybridized to each other in order to remove (subtract) those restriction fragments common to both sibs. Already after two rounds of subtractive hybridization, a clear enrichment of presumably tester-specific restriction fragments was observed, which was even more pronounced after the third round of subtraction. A plasmid library of 3000 recombinant clones was constructed of the second round and of the third round difference product. DNA sequence determination of randomly chosen clones of each difference product showed that approximately 1000 unique clones were obtained in the second-round difference product and approximately 500 in the third-round difference product. About half of the clones identified in the second-round difference product were also present in the third-round difference product. Of the second-round difference product, 39 different gRDA fragments could be identified, of which 21 were tester specific. In the third-round difference product, 22 different gRDA fragments were identified, of which 18 were tester specific. There were 13 fragments in common, resulting in a total of 48 different fragments. In order to establish the localization of these markers, we performed mapping using the dog radiation hybrid panel RHDF5000. Of 39 mapped clones, 29 were mapped to 20 existing RH groups, and 10 remained unlinked. It is concluded that gRDA is suitable to generate DNA markers to track disease genes within lines of pedigree dogs. Received: 26 April 2000 / Accepted: 11 May 2000     

Colonization of Pacific islands by parasites of low dispersal ability: phylogeography of two monogenean species parasitizing butterflyfishes in the South Pacific Ocean

Aim To investigate the phylogeographical patterns of two poorly dispersing but widely distributed monogenean species, Haliotrema aurigae and Euryhaliotrematoides grandis, gill parasites of coral reef fishes from the family Chaetodontidae. Location South Pacific Ocean (SPO). Methods Sequence data from the mitochondrial cytochrome oxidase subunit I (COI) gene were obtained from samples from five localities of the SPO (Heron Island, Lizard Island, Moorea, Palau and Wallis) for the two parasite species. Phylogenetic and genetic diversity analyses were used to reconstruct phylogeographical patterns, and dates of cladogenetic events were estimated. Results Overall, 50 individuals of 17 Haliotrema aurigae and 33 of Euryhaliotrematoides grandis were sequenced from five localities of the SPO for COI mtDNA (798 bp). Our results revealed a deep phylogeographical structure in the species Euryhaliotrematoides grandis. The molecular divergence between individuals from Moorea and individuals from the remaining localities (7.7%) may be related to Pleistocene sea‐level fluctuations. In contrast, Haliotrema aurigae shows no phylogeographical patterns with the presence of most of the mitochondrial haplotypes in every locality sampled. Main conclusions Our study shows contrasting phylogeographical patterns of the two monogenean parasite species studied, despite many shared characteristics. Both parasites are found on the same host family, share the same geographical range and ecology, and are phylogenetically close. We propose two hypotheses that may help explain the diparity: the hypotheses involve differences in the evolutionary age of the parasite species and their dispersal capabilities. Additionally, the lack of phylogeographical structure in Haliotrema aurigae contrasts with its apparently restricted dispersion, which is likely to occur during the egg stage of the life cycle, inducing a passive dispersal mechanism in butterflyfish monogeneans.     

Human metabolic phenotypes link directly to specific dietary preferences in healthy individuals

Individual human health is determined by a complex interplay between genes, environment, diet, lifestyle, and symbiotic gut microbial activity. Here, we demonstrate a new "nutrimetabonomic" approach in which spectroscopically generated metabolic phenotypes are correlated with behavioral/psychological dietary preference, namely, "chocolate desiring" or "chocolate indifferent". Urinary and plasma metabolic phenotypes are characterized by differential metabolic biomarkers, measured using 1H NMR spectroscopy, including the postprandial lipoprotein profile and gut microbial co-metabolism. These data suggest that specific dietary preferences can influence basal metabolic state and gut microbiome activity that in turn may have long-term health consequences to the host. Nutrimetabonomics appears as a promising approach for the classification of dietary responses in populations and personalized nutritional management.     

Ionizing radiation induces a Yap1-dependent peroxide stress response in yeast

Repair of DNA damage is fundamental for cellular tolerance to ionizing radiation (IR) and many IR-induced DNA lesions are thought to occur as a result of oxidative stress. We investigated the physiological effects of IR in Saccharomyces cerevisiae by performing protein expression profiles in cells exposed to electron pulse irradiation. Transient induction of several antioxidant enzymes in wild-type cells, but not in cells lacking the oxidative stress regulator Yap1, indicated that IR exposure causes cellular oxidative stress. Yap1 activation involved oxidation to the intramolecular disulfide bond, a signature of activation by peroxide, and was dependent on the Yap1 peroxide sensor Orp1/Gpx3. H(2)O(2) was produced in the culture medium of irradiated cells and was both necessary and sufficient for IR-induced Yap1 activation. When IR was performed in the presence of N(2)O, obviating H(2)O(2) production and increasing hydroxyl radical ((*)OH) production, the Yap1 response was lost, indicating that Yap1 was unable to respond to (*)OH or (*)OH-induced damage. However, the Yap1 response to IR did not seem to be a primary determinant of cellular IR tolerance. Altogether, these data provide a molecular demonstration that cells experience in vivo peroxide stress during IR and indicate that the H(2)O(2) produced cannot account for IR toxicity.     

Stock identification of the sciaenid fish Micropogonias undulatus in the western North Atlantic Ocean using parasites as biological tags

Proper fisheries management of the Atlantic croaker Micropogonias undulatus is necessary in the United States due to the commercial and recreational importance of this fish species. Croaker stock structure in the western North Atlantic has been investigated in the past by various authors, with inconclusive results. In this study, macroparasites were used as biological tags to identify putative croaker stocks in the area between New Jersey and Florida, which encompasses the Mid Atlantic Bight and the South Atlantic Bight separated at Cape Hatteras, North Carolina. The macroparasite community of the fish was identified, showing the presence of 30 species in four phyla, of which several were new host records, and one species, a monogenean, was new to science. A canonical correspondence analysis was applied to determine the variables responsible for parasite species composition, to resolve the question of croaker stock structure in the western North Atlantic Ocean. This analysis showed that latitude was the deciding variable delineating the parasite community composition of the Atlantic croaker. Among the 30 parasites, 15 were identified as putative tags according to qualitative criteria, and then 10 out of those 15 were selected as being appropriate tags using quantitative criteria. These parasite tags support the presence of two stocks roughly separated at the known biogeographical barrier at Cape Hatteras.     

Polyploidization mechanisms: temperature environment can induce diploid gamete formation in Rosa sp

Polyploidy is an important evolutionary phenomenon but the mechanisms by which polyploidy arises still remain underexplored. There may be an environmental component to polyploidization. This study aimed to clarify how temperature may promote diploid gamete formation considered an essential element for sexual polyploidization. First of all, a detailed cytological analysis of microsporogenesis and microgametogenesis was performed to target precisely the key developmental stages which are the most sensitive to temperature. Then, heat-induced modifications in sporad and pollen characteristics were analysed through an exposition of high temperature gradient. Rosa plants are sensitive to high temperatures with a developmental sensitivity window limited to meiosis. Moreover, the range of efficient temperatures is actually narrow. 36 °C at early meiosis led to a decrease in pollen viability, pollen ectexine defects but especially the appearance of numerous diploid pollen grains. They resulted from dyads or triads mainly formed following heat-induced spindle misorientations in telophase II. A high temperature environment has the potential to increase gamete ploidy level. The high frequencies of diplogametes obtained at some extreme temperatures support the hypothesis that polyploidization events could have occurred in adverse conditions and suggest polyploidization facilitating in a global change context.     

Novel phenylamino acetamide derivatives as potent and selective kappa opioid receptor agonists

A novel series of phenylamino acetamide derivatives was synthesized. These amides were shown to be potent and selective kappa opioid receptor agonists.     

Estimating Orangutan Densities Using the Standing Crop and Marked Nest Count Methods: Lessons Learned for Conservation

Reliable estimates of great ape abundance are needed to assess distribution, monitor population status, evaluate conservation tactics, and identify priority populations for conservation. Rather than using direct counts, surveyors often count ape nests. The standing crop nest count (SCNC) method converts the standing stock of nests into animal densities using a set of parameters, including nest decay rate. Nest decay rates vary greatly over space and time, and it takes months to calculate a site-specific value. The marked nest count (MNC) method circumvents this issue and only counts new nests produced during a defined period. We compared orangutan densities calculated by the two methods using data from studies in Sumatra and Kalimantan, Indonesia. We show how animal densities calculated using nest counts should be cautiously interpreted when used to make decisions about management or budget allocation. Even with site-specific decay rates, short studies using the SCNC method may not accurately reflect the current population unless conducted at a scale sufficient to include wide-ranging orangutan movement. Density estimates from short studies using the MNC method were affected by small sample sizes and by orangutan movement. To produce reliable results, the MNC method may require a similar amount of effort as the SCNC method. We suggest a reduced reliance on the traditional line transect surveys in favor of feasible alternative methods when absolute abundance numbers are not necessary or when site-specific nest decay rates are not known. Given funding constraints, aerial surveys, reconnaissance walks, and interview techniques may be more cost-effective means of accomplishing some survey goals.