			Home About us Contact

Equal Role (equal + role)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Bacterial community structure of glacier forefields on siliceous and calcareous bedrock

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2009
A. Lazzaro
Summary Forefields of retreating glaciers represent unique opportunities to investigate the initial phases of soil formation and microbial interactions with mineral surfaces. An open question concerns the physical and chemical driving-factors affecting the establishment of microbial communities in these young ecosystems. In this study we compared the bacterial community structure of six glacier forefield soils belonging to two contrasting bedrock categories (calcareous and siliceous) through T-RFLP profiling of the 16S rRNA gene. The community profiles were correlated with an array of physical (soil texture, water holding capacity, hours of sunshine, temperature, rainfall and exposure) and chemical (TC, TN, DOC, extractable nutrients and pH) factors using canonical correspondence analysis (CCA). A first comparison of the T-RFLP profiles suggested that the degree of operational taxonomic unit (OTU) diversity of these soils was similar, and that community structure was dominated by ubiquitous taxa. CCA showed that both physical (e.g. hours of sunshine or rainfall) and chemical factors (e.g. SO2,4 or PO3,4) played an equal role in shaping the soil bacterial communities. OTUs unique to specific sites appeared to be strongly influenced by the climatic regime and by texture. Overall, the community structure of the six glacial forefields showed no clear dependence on the bedrock categories. [source]

Duetting,A mechanism to strengthen pair bonds in a dispersed pair-living primate (Lepilemur edwardsi)?

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009
Maria G. Méndez-Cárdenas
Abstract Duetting is defined as an interactively organized pair display in which one pair partner coordinates its vocalizations in time with those of the other. It is widespread among tropical birds and cohesive pair-living primates, in which it is suggested to strengthen pair bonds. We know very little about the presence and function of duetting in dispersed pair-living mammals. We studied duetting behavior in a solitary foraging, but pair-sleeping, primate, the Milne Edwards' sportive lemur, in a dry deciduous forest of north-western Madagascar. We radio-tracked six pairs throughout 1 year and recorded their sleeping sites and associations, home-range use, and vocal and behavioral interactions. Three different periods were covered (mating, pregnancy, and offspring care). Sleeping partners form long-term pair bonds, indicated by an almost exclusive pair-specific usage of sleeping sites and home-ranges across periods. We explored three functional hypothesis of duetting: mate reunion, pair reunion, and joint-territorial defense. Pairs regularly engaged in duet calling. Duetting increased significantly during the offspring care period. Duetting occurred significantly more often at feeding sites than at sleeping sites. Pair partners synchronized behavioral activities after duetting. The activity most often synchronized was locomotion. Pair partners played an equal role in duetting with no difference between sexes in starting or terminating duetting. Altogether, our results provide support for the hypothesis that in dispersed pair-living primates, duetting evolved as a mechanism to coordinate activities between pair partners dispersed in space, to strengthen pair bonds, and, perhaps, to limit infanticide and nutritional stress in lactating females. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

,2 -Adrenoceptor subtypes involved in the regulation of catecholamine release from the adrenal medulla of mice

BRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2006
E Moura
Background and purpose: This study was carried out to elucidate which ,2 -adrenoceptor subtypes mediated the inhibition of noradrenaline and adrenaline release from the adrenal medulla of mice. Experimental approach: Isolated adrenal medullae from wild-type and ,2A, ,2B and ,2C -adrenoceptor knockout (KO) mice were placed in superfusion chambers. Catecholamine overflow was evoked by 1,1-dimethyl-4-phenylpiperazinium (500 ,M) in absence or in presence of the ,2 -adrenoceptor agonist medetomidine. The effect of medetomidine was tested in presence of the ,-adrenoceptor antagonists rauwolscine, WB 4101, spiroxatrine, phentolamine and prazosin. Key results: In wild-type mice, medetomidine reduced noradrenaline and adrenaline overflow in a concentration-dependent manner (EC50 in nM: 1.54 and 1.92; Emax in % of inhibition: 91 and 94, for noradrenaline and adrenaline, respectively). The pKD values of the antagonists for noradrenaline overflow did not correlate with pKD values at ,2A, ,2B, or ,2C binding sites. The pKD values of the antagonists for adrenaline overflow correlated positively with pKD values at ,2C binding sites (opossum kidney cells). The effect of medetomidine (100 nM) on noradrenaline overflow was significantly reduced in all three ,2KO mice (57, 54, 44 % inhibition, for ,2A, ,2B, and ,2C, respectively), whereas the effect of medetomidine on adrenaline overflow was greatly reduced in ,2CKO mice (14 % inhibition). Conclusions and implications: In the adrenal medulla of mice, all three ,2 -adrenoceptor subtypes (,2A, ,2B, and ,2C) play an equal role in the inhibition of noradrenaline overflow, whereas the ,2C -adrenoceptor is the predominant ,2 -adrenoceptor subtype involved in the inhibitory mechanism controlling adrenaline overflow. British Journal of Pharmacology (2006) 149, 1049,1058. doi:10.1038/sj.bjp.0706950 Published online 30 October 2006 [source]

Changes in yearling rhesus monkeys' relationships with their mothers after sibling birth

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2001
B.J. Devinney
Abstract The birth of a new sibling is believed to signify an abrupt and important transition in a young primate's relationship with its mother,one that is of potential importance from at least three theoretical perspectives: attachment theory, parent,offspring conflict theory, and dynamic assessment models. This study examines changes in relationships between free-ranging yearling rhesus monkeys (Macaca mulatta) and their mothers concomitant with the birth of the mother's next infant, and tests predictions derived from each theoretical perspective. We observed 31 yearling rhesus on Cayo Santiago, Puerto Rico, 3 months before and 3 months after their siblings' births, using focal animal sampling methods. Changes in measures related to mother,yearling interaction and yearling distress were examined using repeated-measures analysis of variance. After sibling birth, mothers and yearlings abruptly reduced amounts of time in contact and increased amounts of time at a distance and out of sight of one another. Mothers and yearlings played approximately equal roles in bringing about decreases in proximity, and yearlings took the primary roles in bringing about decreases in contact. Rates of maternal aggression toward yearlings increased immediately and markedly after birth, possibly providing yearlings with early cues regarding subsequent decreased levels of maternal care. There were no marked increases in overt signs of yearling distress (e.g., vocalizations or tantrums) following the births. We conclude that yearlings generally acquiesced to reduced levels of care, responding behaviorally with increased independence and maturity. In this sense, our study provides preliminary support for dynamic assessment models over attachment theory and parent,offspring conflict theory models. Am. J. Primatol. 54:193,210, 2001. © 2001 Wiley-Liss, Inc. [source]