Essential Oils and Isolated Compounds from Lippia alba Leaves and Flowers: Antimicrobial Activity and Osteoclast Apoptosis

In the present study, essential oils extracted from the leaves and flowers of Lippia alba (Mill.) N.E.Br. (L. alba) were analyzed for their antimicrobial activity and their effects on osteoclasts. The periodontal pathogens, Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans; ATCC 43717), Fusobacterium nucleatum (F. nucleatum; ATCC 25586) and Porphyromonas gingivalis (P. gingivalis); ATCC 33277) were used in antimicrobial activity assays for determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC), whereas Bacteroides fragilis (B. fragilis; ATCC 25285) was used as the control microorganism. Osteoclast (OC) apoptosis was assessed by TUNEL assay and Fas receptor expression was detected by immunocytochemistry. The analysis of antimicrobial activity revealed that P. gingivalis had the lowest MIC values, whereas A. actinomycetemcomitans had the highest. L. alba essential oils were found to be toxic to human cells, although the compounds, carvone, limonene and citral, were non-toxic and induced apoptosis in the OCs. This study demonstrates that L. alba has potential biotechnological application in dentistry. In fact periodontal disease has a multifactorial etiology, and the immune response to microbial challenge leads to osteoclast activation and the resorption of the alveolar bone, resulting in tooth loss

Paenibacillus agarexedens sp nov., nom. rev., and Paenibacillus agaridevorans sp nov.

Twenty-two agarolytic, aerobic, spore-forming strains were characterized taxonomically by DNA-DNA reassociation experiments, riboprint analyses, 16S rDNA sequencing and phenetic similarity analyses. Based on riboprint analyses, the strains formed eight ribogroups, six of which contained 2-6 strains and two encompassed single strains. Within the multi-strain ribogroups, similarities ranged from 91-99%. Phylogenetic analyses of representatives of the eight groups by 16S rDNA sequence analysis showed that the strains were affiliated to the genus Paenibacillus, but relatedness to described Paenibacillus species was only moderate (<97.8% sequence similarity). Published DNA-DNA similarity values for most of the agarolytic strains, supplemented with new data, supported the distinctiveness of the eight ribogroups. Intragroup DNA-DNA similarity values ranged from 80 to 104%, while intergroup DNA-DNA similarities were <35%. Based on genomic distinctiveness and supported by the presence of distinguishing phenotypic properties, multi-strain groups 1 and 2 are proposed as novel species, Paenibacillus agarexedens sp. nov., nom. rev. (type strain, DSM 1327(T) = CIP 107437(T)) and Paenibacillus agaridevorans sp. nov. (type strain, DSM 1355(T) = CIP 107436(T)).5341051105

Diet and resource partitioning among anurans in irrigated rice fields in Pantanal, Brazil

Artificial ponds or irrigated systems scattered throughout farmlands can offer important habitats for anurans and can be interesting sites for research on species resources use in a changing landscape. This study describes the diet and resource partitioning among anurans inhabiting irrigated rice fields in the Pantanal region. Twenty categories of prey were found in the stomachs of Leptodactylus chaquensis, L. elenae, L. podicipinus and Rhinella bergi, the most frequent being Coleoptera, Hymenoptera, larvae of Hexapoda, Hemiptera, Diptera and Orthoptera. The great differences found in the diet of these species in rice fields compared to other locations, according to available records in the literature, was the increased importance of Hemipitera and Orthoptera and the decrease in importance of Hymenoptera in the diet of leptodactylids. These differences might be attributed to changes in the availability of resources in response to habitat modification. Although diet composition was very similar among species, niche overlap was larger than expected by chance, suggesting that the competition for food resources is not, or has not been, a significant force in determining the structure of this frog community. Two non-exclusive hypotheses could be considered as a justification for this result: 1) the high niche overlap could result from resource availability, which is sufficient to satisfy all species without any strong competition; 2) or the high values of niche overlap could be a selective force driving species to compete, but there has not been enough time to express a significant divergence in the species diet because the study area is characterised as a dynamic habitat influenced by frequent and cyclical changes