Context-specific calls in wild chimpanzees, Pan troglodytes verus: analysis of barks

Context-specific calls, which have a distinct acoustic structure and are selectively produced in specific contexts, are a prerequisite for calls that function referentially. Functionally referential calls, which convey information to conspecifics about objects and events in the external world, have been found in a number of species, notably primates. Evidence of context-specific calls in apes, however, is largely absent. We analysed whether the barks of wild male chimpanzees in the Ta? Forest, Côte d'Ivoire, are context specific. We examined the acoustic structure of barks, and other calls produced in association with barks, in six contexts, using discriminant function analysis. Chimpanzees produced context-specific signals in two ways. First, they produced two acoustically graded bark subtypes, in hunt and snake contexts, respectively. Second, they produced context-specific signal combinations of barks with acoustically different call types or drums. These signal combinations increased specificity levels in three of the six contexts to over 90%, a level similar to the classic vervet monkey, Cercophithecus aethiops, predator alarm calls. Furthermore, specific chimpanzee signals were produced in contexts other than alarm, such as travel and hunting, where the potential benefits of evolving specific calls are less obvious. These signals may convey specific context information to listeners, and thus function referentially; however, to confirm this, analyses of listeners' responses are required. The results show that two strategies for producing context-specific signals seem to have evolved in a species other than humans: chimpanzees produce context-specific bark subtypes and context-specific signal combinations. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Design of a growth model for yeast

The study of the cell cycle of a yeast strain made it possible to define two parameters:T, the time elapsing between the appearance of two consecutive buds on a mother cell, and Θ, the time elapsing between the appearance of a bud and the beginning of the first mitotic cycle. The influence of these two parameters on the growth rate of the strain is studied.     

Distribution and microhabitats of native and non-native gammarids (Amphipoda, Crustacea) in Brittany, with particular reference to the endangered endemic sub-species Gammarus duebeni celticus

Aim  To assess temporal changes in gammarid distribution in Brittany and microhabitat-use overlap between the endangered endemic Gammarus duebeni celticus Stock & Pinkster, 1970 , the expanding natives G. pulex (Linnaeus, 1758) and Echinogammarus berilloni (Catta, 1878), and the introduced G. tigrinus Sexton, 1939.
Location  Brittany and adjacent regions in western France.
Methods  The spatial and temporal patterns in distribution of gammarids at the scale of Brittany were studied using 351 sites. Longitudinal distributions (from the source to the estuary of the river) and microhabitat-use (substratum type and water velocity) were also considered in selected rivers.
Results  At the regional scale, all species occurred together less often than expected statistically, with significant deviations from expected for G. pulex vs. both G. duebeni celticus and G. tigrinus , and for E. berilloni vs. both G. duebeni celticus and G. tigrinus . However, at the microhabitat scale, E. berilloni occurred significantly more often than expected with the endemic G. duebeni celticus , and this appears to be due to similar substratum and water velocity preferences, although at both the regional and microhabitat scales E. berilloni prefers wider streams than G. duebeni celticus . This study reveals a decline in the endangered G. duebeni celticus since 1970.
Main conclusions  The longitudinal and local distributions of G. duebeni celticus , and the higher-than-expected co-occurrence of the species with G. pulex , suggest that the decline of the endemic species may be due to changes in the environment and/or interference from native G. pulex , which is expanding its range in Brittany. The results are discussed as regards to the consequences for regional biodiversity.     

Conformational properties of Eu(III) complexes of 3,3′; 5,3″-polymethylene bridged derivatives of 2,2′; 6,2″-terpyridine

The complex [Eu(tpy)₃](ClO₄)₃ where TPY=2,2′; 6,2″-terpyridine, has been prepared and reexamined. The complex appears to be stable in acetonitrile solution with respect to decomplexation of the ligands but the addition of water does cause partial replacement of tpy. Analogous complexes have been prepared with 3,3′; 5,3″-polymethylene bridged derivatives of tpy having two or three carbons in the bridge. The bridging enforces a cisoid geometry of the ligand and prohibits its replacement by added water. An X-ray determination was carried out for [Eu(3b)₃](ClO₄)₃, where 3b=3,3′; 5,3″-dimethylene tpy, which crystallizes in the monoclinic space group P2₁/c with a=11.908(4), b=15.768(5), c=29.513(9) Å, β=93.60(2)°, μ=13.5 cm⁻¹ and Z=4. The complex forms a tricapped trigonal prism with each of the ligands adopting the same dl conformation. Variable temperature NMR analysis of the bridged ligand complexes indicates that conformational inversion of the bound ligand is not a concerted process and barriers for inversion of individual methylene units can be estimated from coalescence of the signals from the geminal methylene protons. The luminescence properties of the bridged tpy complexes are similar to the parent unbridged system.     

Analysis of human V H gene repertoire expression in peripheral CD19+ B cells

Using CD19 B-cell selection and polymerase chain reaction-amplified cDNA libraries, we analyzed the peripheral immunoglobulin heavy chain variable repertoire of three healthy adult donors. Here we report that most of the CD19+ circulating B cells expressed unmutated V _H-D-J_H rearrangements. By specific V _H family hybridization, we show that V _H gene family utilization in the periphery roughly corresponds to the complexity of these families in the germline and appears to be relatively constant among the analyzed subjects. However, sequence data of clones picked at random from one IgM cDNA library reveals that in spite of this random utilization, the V _H gene expression in naive circulating B cells is highly biased towards the expression of a limited set of V _H genes. As previously reported by others, this restricted mechanism is also found for the D and J _H segments.The nucleotide sequence data reported in this paper have been submitted to the GenBank/EMBL nucleotide sequence database and have been assigned the accession numbers Z47213-Z47243 and Z47349