The mutual exclusivity principle, which states that an object category can have only one name, has been shown to be used by toddlers and preschoolaged children (M arkman, 1991). Studies of the mutual exclusivity principle in bilingual children aged over 3.5 years have generally found a tendency to honor the principle within languages, but not across languages. To date, younger bilinguals'adherence to this principle has not been investigated. In the present cross-sectional study, monolingual and bilingual children aged 27 and 35 months were tested. Both monolingual and bilingual children were presented with two novel labels for the same object, a violation of the mutual exclusivity principle within a language. They were then tested on their comprehension of the two labels. Bilingual children participated in an additional task in which mutual exclusivity was violated across languages. Results indicated that across both language groups, the older children honored mutual exclusivity more than the younger children. No differences were found between monolinguals and bilinguals in adherence to mutual exclusivity. In addition, bilingual children performed similarly when mutual exclusivity was violated within a language and across languages. The proportion of translation equivalents in the bilingual children's vocabulary did not predict their performance on the mutual exclusivity task. These results suggest that bilingual language experience does not significantly alter adherence to the mutual exclusivity principle before the age of three years.

Endophytes are microorganisms that live inside the plant tissue without causing external symptoms. All plants in nature harbor endophytes. Some endophytes produce and secrete biologically active compounds, known as secondary metabolites, which can help the host plant cope with bacterial, fungal, and other pest pathogens. Endophytes are isolated from aquatic plants and algae. Diseases are detrimental in the aquaculture industry where chemical pesticides and antibiotics are widely used in an attempt to cope with fish pathogens. However, the ability to prevent disease outbreaks in aquaculture is currently extremely limited. Here, we isolated 173 bacterial and fungal endophytes from 16 Mediterranean seaweed and 4 algae from fresh or thermo-mineral water. We found 88 endophytes (51%) with biological activity against four common aquaculture pathogens. Fifty endophytes (29%) caused mortality of at least one of these four pathogens. We identified 23 bioactive endophytes, 18 of which are from the Bacilli class. Our findings suggest that macroalgae from different aquatic environments can serve as a good source of potential biocontrol agents against aquaculture diseases. To the best of our knowledge, there are no published studies demonstrating the use of algal endophytes to control aquaculture diseases. Our study may lead to finding new molecules for use as novel environmentally friendly products that will solve one of the most challenging problems for the growing aquaculture industry: pathogens and pests.

The taxonomic assumption, or noun-category bias, is thought to facilitate word learning by focusing children's attention on taxonomic categories as likely candidates for word meanings. Three experiments were conducted to disentangle the role of taxonomic relations and shape similarity in 18-and 24-month-olds' responses on a noun category bias task. The relationship between vocabulary composition and performance on these tasks was also examined. Results indicated that both 18-and 24-month-old children were predominantly guided by shape similarity when extending novel labels. However, some evidence that taxonomic information can be used to guide word extension was found in the 24-month-old group. Those children with a larger proportion of nouns in their vocabulary were more likely to use information about category membership when extending words, even in the absence of shape similarity.

The purpose of this study was to explore the quality of daycare by examining interactions between caregivers and young children. Across 49 Israeli daycare centers, 299 children aged 18-30 months were observed naturalistically in groups of four to eight, together with their main caregiver. Caregivers' behavior was defined in terms of mediation and was assessed using the Mediated Learning Experience Scale developed by Lidz. Mediated learning, a concept developed by Feuerstein, is a reciprocal process wherein an attentive adult sensitively uses didactic skills to mediate between a child and the world. It was hypothesized that caregivers' mediation behavior would be linked to children's affective responses. No correlation was found between mediation behavior and children's positive approaches to the caregiver. There was a tendency toward more crying episodes in daycare centers in which the caregiver mediated less. Two mediation subscales were created, one emphasizing cognitive elements of mediation and the other emotional elements. Episodes of crying were found to be significantly fewer in daycare centers in which caregivers' cognitive mediation skills were higher. Children were found to initiate fewer approaches to their main caregiver when other caregivers were present. A tendency was also found toward fewer approaches the larger the group size of the children, supporting previous findings on the importance of group size for quality of daycare.