The sense of smell, its signalling pathways, and the dichotomy of cilia and microvilli in olfactory sensory cells

Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existance of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use

Parent Programs for Reducing Adolescent’s Antisocial Behavior and Substance Use: A Randomized Controlled Trial

Two theoretically based parent training programs, delivered in real-world settings by the social services, were examined in this randomized controlled trial for effectiveness in reducing adolescents’ antisocial behavior and substance use. Two hundred and thirty-seven (237) adolescents in ages between 12 and 18 and their parents were assigned to one of two programs or to a wait-list control condition. The programs were the nine weekly group sessions program Comet 12–18 (Swedish Parent Management Training Program) and the six weekly ParentSteps (Swedish shortened version by Strengthening Families Program 10–14). Outcome measures were antisocial behavior, substance use, and delinquency, and psychosocial dysfunction. Data based on adolescents’ and parents’ ratings of the adolescents’ problem behavior at baseline and 6 months later were analyzed with repeated measures ANVOA, Logistic regression, and Kruskal–Wallis H test. The results showed that parents’ ratings of adolescents’ antisocial behaviors decreased significantly over time, but no time by group effect emerged. No program effects were found in the adolescents’ self-reported antisocial behavior, delinquency, or psychosocial functioning. A threefold risk of illicit drug use was found in both intervention groups. The results suggest that neither Comet nor ParentSteps had beneficial effects on adolescent’s antisocial or delinquent behavior, or on alcohol use. The only significant group difference found was a threefold risk of drug use in the intervention adolescents at follow-up, but for several reasons this finding should be interpreted with caution. Trial registration number: ISRCTN76141538

Prolonged Gq activity triggers fly rhodopsin endocytosis and degradation, and reduces photoreceptor sensitivity

Rapid deactivation of the Drosophila light receptor rhodopsin, through a visual arrestin Arr2 and a pathway that involves a transcription factor dCAMTA, is required for timely termination of light responses in the photoreceptor neuron. Here we report that this process is also critical for maintenance of the photoreceptor sensitivity. In both dCAMTA- and arr2-mutant flies, the endocytosis of the major rhodopsin Rh1 was dramatically increased, which was mediated by a Gq protein that signals downstream of rhodopsin in the visual transduction pathway. Consequently, the Rh1 level was downregulated and the photoreceptor became less sensitive to light. Remarkably, the Gq-stimulated Rh1 endocytosis does not require phospholipase C, a known effector of Gq, but depends on a tetraspanin protein. Our work has identified an arrestin-independent endocytic pathway of G protein-coupled receptor in the fly. This pathway may also function in mammals and mediate an early feedback regulation of receptor signaling