Regional heterogeneity for the intracranial self-administration of ethanol and acetaldehyde within the ventral tegmental area of alcohol-preferring (P) rats: involvement of dopamine and serotonin.

The meso-limbic dopamine (DA) system has an important role in regulating alcohol drinking. Previous findings from our laboratory indicated that Wistar rats self-administered ethanol (EtOH) directly into the posterior, but not anterior, ventral tegmental area (VTA), and that coadministration of a DA D(2,3) receptor agonist or a serotonin-3 (5-HT3) receptor antagonist blocked EtOH self-administration. In addition, we reported that alcohol-preferring (P) rats self-administered acetaldehyde (ACD), the first metabolite of EtOH, into the posterior VTA. The objectives of this study were to compare the reinforcing effects of EtOH and ACD within the VTA of P rats to examine the possibility that the reinforcing effects of EtOH within the VTA may be mediated by its conversion to ACD. Adult female P rats were stereotaxically implanted with guide cannulae aimed at either the posterior or anterior VTA. At 1 week after surgery, rats were placed in standard two-lever (active and inactive) experimental chambers for a total of seven to eight sessions. The 4-h sessions were conducted every other day. The results indicated that (a) 75-300 mg% (17-66 mM) EtOH and 6-90 microM ACD were self-administered into the posterior, but not anterior, VTA; (b) the self-administration of 150 mg% EtOH was not altered by coinfusion of a catalase inhibitor; (c) coadministration of the D(2/3) agonist quinpirole (100 microM) blocked the self-infusions of 150 mg% EtOH and 23 microM ACD into the posterior VTA; and (d) coadministration of 200 microM ICS205,930 (5-HT3 receptor antagonist) prevented the self-infusion of 150 mg% EtOH, whereas concentrations of ICS 205,930 up to 400 microM had no effect on the self-infusion of 23 microM ACD into the posterior VTA. Overall, the results of this study indicate that EtOH and ACD can independently produce reinforcing effects within the posterior VTA, and that activation of DA neurons mediates these effects. Furthermore, activation of 5-HT3 receptors within the posterior VTA is involved in the self-infusion of EtOH, but not ACD.     

Biogeography of Burkholderia pseudomallei in the Torres Strait Islands of Northern Australia

It has been hypothesized that biogeographical boundaries are a feature of Burkholderia pseudomallei ecology, and they impact the epidemiology of melioidosis on a global scale. This study examined the relatedness of B. pseudomallei sourced from islands in the Torres Strait of Northern Australia to determine if the geography of isolated island communities is a determinant of the organisms'' dispersal. Environmental sampling on Badu Island in the Near Western Island cluster recovered a single clone. An additional 32 clinical isolates from the region were sourced. Isolates were characterized using multilocus sequence typing and a multiplex PCR targeting the flagellum gene cluster. Gene cluster analysis determined that 69% of the isolates from the region encoded the ancestral Burkholderia thailandensis-like flagellum and chemotaxis gene cluster, a proportion significantly lower than that reported from mainland Australia and consistent with observations of isolates from southern Papua New Guinea. A goodness-of-fit test indicated that there was geographic localization of sequence types throughout the archipelago, with the exception of Thursday Island, the economic and cultural hub of the region. Sequence types common to mainland Australia and Papua New Guinea were identified. These findings demonstrate for the first time an environmental reservoir for B. pseudomallei in the Torres Strait, and multilocus sequence typing suggests that the organism is not randomly distributed throughout this region and that seawater may provide a barrier to dispersal of the organism. Moreover, these findings support an anthropogenic dispersal hypothesis for the spread of B. pseudomallei throughout this region.     

Development and characterization of 36 novel microsatellite markers for lake chub (Couesius plumbeus) using illumina paired-end sequencing

Lake chub is a common freshwater cyprinid found throughout Canada and parts of the northern United States. Here we describe 36 novel microsatellite loci, 25 of which are polymorphic, exhibiting between 2 and 17 alleles each, while the remaining 11 loci are monomorphic. Observed and expected heterozygosities for the polymorphic markers ranged from 0.125 to 0.875 and 0.146 to 0.878, respectively. There was no evidence of linkage disequilibrium between any locus pairs, nor was there any evidence of null alleles. There were however, six markers deviating from Hardy–Weinberg Equilibrium, a result we attribute to relatively small sample size.