The Mondrian matrix: Culicoides biting midge abundance and seasonal incidence during the 2006-2008 epidemic of bluetongue in the Netherlands.

During the northern Europe epidemic of bluetongue (BT), Onderstepoort-type blacklight traps were used to capture Culicoides Latreille (Diptera: Ceratopogonidae) biting midges weekly between November 2006 and December 2008 on 21 livestock farms in the Netherlands. Proven and potential vectors for the bluetongue virus (BTV) comprised almost 80% of the midges collected: the Obsoletus complex, constituting C. obsoletus (Meigen) and C. scoticus Downes & Kettle (44.2%), C. dewulfi Goetghebuer (16.4%), C. chiopterus (Meigen) (16.3%) and C. pulicaris (Linnaeus) (0.1%). Half of the 24 commonest species of Culicoides captured completed only one (univoltine) or two (bivoltine) generations annually, whereas multivoltine species (including all BTV vectors) cycled through five to six generations (exceeding the one to four generations calculated in earlier decades). Whether this increment signals a change in the phenology of northern Europe Culicoides or simply is an adaptive response that manifests during warmer episodes, thus heightening periodically the incursive potential of midge-borne arboviruses, remains to be clarified. Culicoides duddingstoni Kettle & Lawson, C. grisescens Edwards, C. maritimus Kieffer, C. pallidicornis Kieffer and C. riethi Kieffer are new records for the biting midge fauna of the Netherlands. It is suggested that C. punctatus (Meigen) be added to the European list of vector Culicoides.

Characterization of the serotonin transporter knockout rat: a selective change in the functioning of the serotonergic system.

Serotonergic signaling is involved in many neurobiological processes and disturbed 5-HT homeostasis is implicated in a variety of psychiatric and addictive disorders. Here, we describe the functional characterization of the serotonin transporter (SERT) knockout rat model, that is generated by N-ethyl-N-nitrosurea (ENU)-driven target-selected mutagenesis. Biochemical characterization revealed that SERT mRNA and functional protein are completely absent in homozygous knockout (SERT-/-) rats, and that there is a gene dose-dependent reduction in the expression and function of the SERT in heterozygous knockout rats. As a result, 5-HT homeostasis was found to be severely affected in SERT-/- rats: 5-HT tissue levels and depolarization-induced 5-HT release were significantly reduced, and basal extracellular 5-HT levels in the hippocampus were ninefold increased. Interestingly, we found no compensatory changes in in vitro activity of tryptophan hydroxylase and monoamine oxidase, the primary enzymes involved in 5-HT synthesis and degradation, respectively. Similarly, no major adaptations in non-serotonergic systems were found, as determined by dopamine and noradrenaline transporter binding, monoamine tissue levels, and depolarization-induced release of dopamine, noradrenaline, glutamate and GABA. In conclusion, neurochemical changes in the SERT knockout rat are primarily limited to the serotonergic system, making this novel rat model potentially very useful for studying the behavioral and neurobiological consequences of disturbed 5-HT homeostasis.