Sex pheromone of the female currant borer, Synanthedon tipuliformis: Identification and field evaluation

(E,Z)-2,13-octadecadien-1-ol acetate and (Z)-13-octadecen-1-ol acetate have been identified from the ovipositor extracts of the currant borer, Synanthedon tipuliformis (Clerck), by capillary GC, and the structures were verified by GC-MS. The diene/monoene ratio in the extract was found to be 93:7. Mixtures of these two compounds as well as the diene alone attracted conspecific males in the field.

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Zusammenfassung (E,Z)-2,13-Octadecadienylacetat und (Z)-13-Octadecenylacetat wurden in Ovipositor-Extrakten des Johannisbeerglasflüglers Synanthedon tipuliformis kapillar-gaschromatographisch nachgewiesen. Die Strukturen wurden mittels Gaschromatographisch-Massenspektrometrie bestätigt. Das Verhältnis Dien/Monoen im Extrakt betrug 93:7. Mischungen der beiden Komponenten wie auch (E,Z)-2,13-Octadecadienylacetat allein lockten im Freiland Männchen dieser Glasflüglerart an.

     

L-Tyrosine-3-hydroxylase regulation in the brain: genetic aspects

Summary L-tyrosine-3-hydroxylase (TH) is the first and rate limiting enzyme in the biosynthetic pathway of catecholamine neurotransmitters (dopamine, noradrenaline, adrenaline). Implication of dopamine (DA) in various psychopathological phenomena, such as schizophrenia, has considerably contributed to the intensity of investigation of basic biochemical regulation of TH by activation and induction. Here we consider a third, constitutional (genotypic) aspect of regulation and present evidence that differences in mesencephalic (TH/SN), striatal (TH/CS), and hypothalamic (TH/HT) TH activity between virtually isogeneic strains of mice can be explained by segregating genetic factors. Biometrical genetic analysis of progenitor strains and their crosses indicated significant additive gene effects for TH/SN, TH/CS, and TH/HT, whereas dominance effects were statistically non-significant. A monogenic model of inheritance for TH/SN and TH/CS could not be rejected, while more than one gene was indicated for TH/HT. Significant positive phenotypic correlations were found in genetically segregating populations among mesencephalic, striatal and hypothalamic TH activities. This would suggest that some common genetic factors (or linked genes) are involved in the genetic variation of all three traits. A genetic selection experiment to elucidate the cellular and biochemical mechanisms underlying these variations is in progress.     

Analysis of the Mesotelencephalic Dopamine System by Quantitative-Trait Locus Introgression

One of the significant factors that affect brain dopamine function is the activity of tyrosine hydroxylase (TH), the first and rate-limiting enzyme in catecholamine biosynthesis. For the analysis of the genetically determined role of dopamine function and TH in behavior and in the regulatory mechanisms of the mesotelencephalic dopamine system we devised a novel genetic strategy (Vadasz; Mouse Genome 88:16–18; 1990). We hypothesized that phenotypic introgression and recombinant fixation could ensure the transfer of Quantitative Trait Loci (QTL) from one strain onto the genetic background of another strain, and new, genetically very similar quasi-congenic strains could be created that would carry individual QTLs, or QTLs in various combinations. Here we summarize the construction of the first set of QTL Introgression strains, and present evidence that QTLs that are responsible for the continuous variation of mesencephalic tyrosine hydroxylase activity (TH/MES), have been transferred onto the C57BL/6By (B6) strain background from BALB/cJ (C) and CXBI (I) donor strains with high and low TH/MES, respectively. The QTL transfer was carried out in two directions by repeated backcross-intercross cycles with concomitant selection for the extreme high and low expressions of TH/MES in replicates, resulting in four QTL Introgression lines. Analysis of regional brain TH activities in the course of the QTL introgression indicated that (a) TH activity in B6.I lines showed quite limited heritability, (b) TH/MES was not highly correlated with striatal TH, and (c) the control of hypothalamic and olfactory tubercle TH activities was largely independent from that of TH/MES. Examination of the open-field (OF) behavior data demonstrated that TH activity did not correlate significantly with OF behavior. After 5 backcross-intercross cycles, TH/MES in each replicate line was still significantly different from that of the B6 background strain. A genomewide scanning of microsatellite markers in the QTL introgression lines demonstrated that about 96% of the markers were of background (B6) type. These results indicate the successful transfer of TH/MES QTLs. After the QTL transfer phase of the experiment altogether more than 100 new RQI strains were initiated in the QTL Introgression lines by strict brother × sister mating. After fixing the introgressed QTLs, ten of the inbred RQI strains were tested for TH/MES. The results showed that in one of the new RQI strains TH/MES was restored to a level that is characteristic to the C donor strain, while TH/MES values in some other strains were between those of the background and donor strains, confirming our hypothesis that phenotypic introgression and recombinant fixation can ensure a virtually complete transfer of QTLs. We conclude from this study that complex, continuously distributed neural traits can successfully be subjected to QTL introgression, and the results raise the possibility that the RQI method can be efficiently applied for gene mapping of complex neural and behavioral traits even if their phenotypic expression is sensitive to confounding developmental and environmental variations, genetic interactions, and genotype-environment interactions.     

Differences in Nicotine-Induced Dopamine Release and Nicotine Pharmacokinetics Between Lewis and Fischer 344 Rats

Studies have shown a greater preference for the self-administration of drugs such as nicotine and cocaine in the Lewis rat strain than in the Fischer 344 strain. We examined some factors that could contribute to such a difference. The baseline level of extracellular dopamine in nucleus accumbens shell was about 3-times higher in Fischer rats than in Lewis rats (3.18 ± 0.26 vs. 1.09 ± 0.14 pg/sample). Nicotine (50-100 g/kg)-induced release of dopamine, expressed in absolute terms, was similar in the two strains. Dopamine release expressed in relative terms (as percent of baseline), however, was significantly greater in Lewis rats than in Fischer rats at 30 min after the first nicotine injection. We suggest that the relative increase is of more influence than the absolute level for determining preference; a lower physiological extracellular dopamine level thus represent a risk factor for increased preference. Amphetamine-induced dopamine release expressed in relative terms was not greater in the Lewis strain. In the initial time period of the microdialysis experiments, a sharper peak in nicotine-induced accumbal dopamine release in Lewis and a less but more sustained release in Fischer rats was observed. This release pattern paralleled the faster clearance of nicotine from blood of Lewis compared to Fischer rats. In tissue slices the electrically induced dopamine release was highest in the nucleus accumbens and lowest in the ventral tegmentum. A significant effect of nicotine was lowering the electrically induced release of dopamine in frontal cortex slices from Fischer brain and increasing this dopamine release in the ventral tegmentum of Lewis brain slices indicating that the ventral tegmentum, an area controlling dopamine release in the accumbens, is more responsive to nicotine in the Lewis rat. Nicotine levels tended to be more sustained in Fischer rats in different brain regions, although the difference in nicotine levels between the strains was not significant at any time period. Several factors contribute to nicotine preference, including the endogenous dopamine level, and the sensitivity of ventral tegmentum neurons to nicotine-induced dopamine release. Strain differences in pharmacokinetics of nicotine may also play a role.