A comparison of experience-dependent locomotory behaviors and biogenic amine neurons in nematode relatives of Caenorhabditis elegans

Background: Survival of an animal depends on its ability to match its responses to environmental conditions. To generate an optimal behavioral output, the nervous system must process sensory information and generate a directed motor output in response to stimuli. The nervous system should also store information about experiences to use in the future. The diverse group of free-living nematodes provides an excellent system to study macro- and microevolution of molecular, morphological and behavioral character states associated with such nervous system function. We asked whether an adaptive behavior would vary among bacterivorous nematodes and whether differences in the neurotransmitter systems known to regulate the behavior in one species would reflect differences seen in the adaptive behavior among those species. Caenorhabditis elegans worms slow in the presence of food; this 'basal' slowing is triggered by dopaminergic mechanosensory neurons that detect bacteria. Starved worms slow more dramatically; this 'enhanced' slowing is regulated by serotonin. Results: We examined seven nematode species with known phylogenetic relationship to C. elegans for locomotory behaviors modulated by food (E. coli), and by the worm's recent history of feeding (being well-fed or starved). We found that locomotory behavior in some species was modulated by food and recent feeding experience in a manner similar to C. elegans, but not all the species tested exhibited these food-modulated behaviors. We also found that some worms had different responses to bacteria other than E. coli. Using histochemical and immunological staining, we found that dopaminergic neurons were very similar among all species. For instance, we saw likely homologs of four bilateral pairs of dopaminergic cephalic and deirid neurons known from C. elegans in all seven species examined. In contrast, there was greater variation in the patterns of serotonergic neurons. The presence of presumptive homologs of dopaminergic and serotonergic neurons in a given species did not correlate with the observed differences in locomotory behaviors. Conclusions: This study demonstrates that behaviors can differ significantly between species that appear morphologically very similar, and therefore it is important to consider factors, such as ecology of a species in the wild, when formulating hypotheses about the adaptive significance of a behavior. Our results suggest that evolutionary changes in locomotory behaviors are less likely to be caused by changes in neurotransmitter expression of neurons. Such changes could be caused either by subtle changes in neural circuitry or in the function of the signal transduction pathways mediating these behaviors

A continental rift model for the La Grande greenstone belt

Stratigraphic relationships and the geochemistry of volcanic rocks contrain the nature and timing of the tectonic and magmatic processes in the pre-deformational history of the La Grande greenstone belt in the Superior Province of north-central Quebec. The lowermost supracrustals in this belt are obscured by syntectonic granitoid intrusives. The supracrustal succession in the western part of the belt consists of a lower sequence of immature clastic sediments and mafic volcanoclastics, overlain by pillowed and massive basalts. Further east, along tectonic strike, a lower sequence of mafic volcanoclastics and immature clastic sediments is overlain by a thick sequence of pillowed and massive basalts, and resedimented coarse clastic sediments and banded iron formation. These are overlain by assive basaltic andesites, andesites and intermediate volcanoclastics intercalated with immature clastic sediments. In contrast, in the eastern part of the belt lenses of felsic volcanics and volcanoclastics occur at the base of the succession and pillowed and massive basalts are overlain by komatiites at the top. The La Grande greenstone belt can be explained as the product of continental rifting. The restricted occurence of komatiites, and eastwardly directed paleocurrents in clastic sediments in the central part of the belt are consistent with rifting commencing in the east and propagating westward with time. The increase in depth of emplacement and deposition with time of the lower three units in the central part of the belt reflects deposition in a subsiding basin. These supracrustal rocks are believed to represent the initial rift succession

Parenting Stress in Immigrant Families of Children With an Autism Spectrum Disorder: A Comparison With Families From the Host Culture

Immigrant families of children with autism spectrum disorders (ASD) face significant challenges in accessing and using rehabilitation services appropriate for their child’s disorder. Compared to families native to their host country, the stress experienced by these families in relation to their child’s condition may be magnified by their immigrant status. This study compared self-reported parenting stress levels among 24 mothers and 17 fathers who had immigrated to Canada to income-matched, Canadian-born parents. Overall, Canadian-born parents tended to report higher stress levels than immigrant parents, but this may be primarily due to the high stress levels among Canadian-born fathers relative to immigrant fathers and mothers from both types of families. These findings highlight the necessity of using supplemental and specialized stress measures when focusing on immigrant families, for whom stress associated with the immigration process may compound or manifest separately from parenting stress. Cultural influences on the perception of ASD (its causes, treatment, and prognosis), children’s place in the family, and parents’ roles in childrearing may also impact stress

Stimulation of tPA-dependent provisional extracellular fibrin matrix degradation by human recombinant soluble melanotransferrin

AbstractTissue-type plasminogen activator (tPA) and its substrate plasminogen (Plg) are key components in the fibrinolytic system. We have recently demonstrated, that truncated human recombinant soluble melanotransferrin (sMTf) could stimulate the activation of Plg by urokinase plasminogen activator and inhibit angiogenesis. Since various angiogenesis inhibitors were shown to stimulate tPA-mediated plasminogen activation, we examined the effects of sMTf on tPA-dependent fibrinolysis. This study demonstrated that sMTf enhanced tPA-activation of Plg by 6-fold. sMTf also increased the release of [125I]-fibrin fragments by tPA-activated plasmin. Moreover, we observed that the interaction of sMTf with Plg provoked a change in the fibrin clot structure by cleaving the fibrin α and β chains. Overall, the present study shows that sMTf modulates tPA-dependent fibrinolysis by modifying the clot structure. These results also suggest that sMTf properties could involve enhanced dissolution of the provisional extracellular fibrin matrix

Sexual behaviour and condom use among university students in Madagascar

Although the number of known HIV-infected students in Madagascar increased significantly between 1989 and 1995, very little is known about student behaviour with regard to AIDS. The study objectives were: to describe Malagasy students\' sexual behaviour and condom use; to document students\' perceptions about condoms; and to study the relationships between students\' socio-demographic characteristics, their perceptions about condoms, and their condom use. The survey used a cross-sectional design and was conducted at the Antananarivo\'s university campus sites. Anonymous questionnaires were self-administered to 320 randomly selected students. Descriptive statistics and 95% confidence intervals were calculated. Logistic regressions were performed to identify the predictors of condom use. Participants\' average age was 24 years. Approximately 80% of the participants reported sexual experiences, and the average age at sexual debut was 19 years. Only 5.7% reported consistent condom use. Common reasons for non-use were steady relationships (75.6%), the perception that condoms were useful only during ovulation periods (8.7%), and the decrease of pleasure (6.4%). The predictors of condom use were male gender, and the perception that condoms were useful during ovulation periods. Risky sexual behaviours with regard to AIDS were prevalent in this community. An HIV prevention programme is recommended. Bien que le nombre connu des étudiants malgaches infectés par le VIH ait largement augmenté entre 1989 et 1995, l\'information sur le comportement des étudiants par rapport au SIDA est très limitée. Les objectifs de cette étude furent: 1) décrire le comportement sexuel des étudiants malgaches et l\'utilisation du préservatif, 2) documenter les perceptions des étudiants envers les préservatifs, 3) examiner dans quelle mesure l\'utilisation du préservatif par les étudiants varie en fonction de leurs caractéristiques sociodémographiques et leurs perceptions envers les préservatifs. Cette étude a été menée dans les sites du campus universitaire d\'Antananarivo en utilisant un devis transversal. Un questionnaire anonyme a été auto-administré à 320 étudiants sélectionnés au hasard. Des statistiques descriptives et intervalles de confiance à 95% ont été calculés. La régression logistique a été utilisée pour identifier les déterminants de l\'utilisation du préservatif. La moyenne d\'âge des participants était de 24 ans. Environ 80% des répondants ont signalé avoir eu des rapports sexuels et l\'âge moyen de premiers rapports était de 19 ans. Seulement 5,7% ont rapporté l\'utilisation systématique du préservatif. Les raisons de non utilisation furent les suivantes : être dans une relation stable (75,6%), la perception que le préservatif est uniquement utile durant la période d\'ovulation (8,7%) et la réduction du plaisir (6,4%). Le genre masculin et l\'argument d\'ovulation ont été identifiés comme prédicteurs d\'utilisation de préservatifs. Les comportements sexuels à risque vis-à-vis du SIDA étaient prédominants dans cette communauté. Un programme de prévention du VIH est recommandé. Keywords: Sexual behaviour, condoms, HIV, students, Madagascar. SAHARA J Vol. 5 (1) 2008: pp. 28-3

A modeling study of heterogeneity and surface water-groundwater interactions in the Thomas Brook catchment, Annapolis Valley (Nova Scotia, Canada)

A modelling study of the impacts of subsurface\ud heterogeneity on the hydrologic response of a small catchment\ud is reported. The study is focused in particular on the\ud hydraulic connection and interactions between surface water\ud and groundwater. A coupled (1-D surface/3-D subsurface)\ud numerical model is used to investigate, for a range of scenarios,\ud the spatio-temporal patterns of response variables such\ud as return flow, recharge, groundwater levels, surface saturation,\ud and streamflow. Eight scenarios of increasing geological\ud complexity are simulated for an 8 km2 catchment in\ud the Annapolis Valley (eastern Canada), introducing at each\ud step more realistic representations of the geological strata\ud and corresponding hydraulic properties. In a ninth scenario\ud the effects of snow accumulation and snowmelt are also considered.\ud The results show that response variables and significant\ud features of the catchment (e.g. springs) can be adequately\ud reproduced using a representation of the geology and\ud model parameter values that are based on targeted fieldwork\ud and existing databases, and that reflect to a sufficient degree\ud the geological and hydrological complexity of the study area.\ud The hydraulic conductivity values of the thin surficial sediment\ud cover (especially till) and of the basalts in the upstream\ud reaches emerge as key elements of the basin’s heterogeneity\ud for properly capturing the overall catchment response