An Automatic Colorimeter and its use in Evaluating the Growth Response of an Anaerobic General Fatty Acid Auxotroph to cis- and trans-Octadecenoic Acids

The construction and mode of operation of an automatic colorimeter is described. In illustrating its use to assess bacterial growth, it was shown that trans -octadecenoates were more stimulatory to the growth of a fatty acid auxotrophic Butyrivibrio sp. than cis -octadecenoates.     

Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables

During daylight hours, the isotope composition of leaf water generally approximates steady‐state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady‐state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of ¹⁸O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non‐steady state. We show that non–steady‐state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents.     

Fifteen microsatellite loci characterized in the golden eagle Aquila chrysaetos (Accipitridae,Aves)

Polymorphic microsatellite loci were identified in order to study golden eagle (Aquila chrysaetos) population fragmentation. Twenty‐six published Aquila and eight published Haliaeetus microsatellite loci were tested for polymorphism in A. chrysaetos. Fifteen loci were polymorphic with between two and six alleles detected per locus. Observed heterozygosity ranged from 0.15 to 0.77 among 177 unrelated individuals from Scotland. There was no evidence for null alleles. Two pairs of loci (Hal‐10 & Aa15 and Hal‐10 & Aa26) displayed linkage disequilibrium.     

Fine-scale genetic structure and its consequence in breeding aggregations of a passerine bird

The pattern of fine-scale genetic structure in a population may reflect current biological processes of the species, such as natal dispersal, the breeding system and demography. We investigated the spatial distribution of nests and fine-scale genetic structure during two breeding seasons in a population of a weakly territorial, flock-living passerine bird, the vinous-throated parrotbill, Paradoxornis webbianus . Nest distribution was clustered. There were two peaks of egg laying within each breeding season, and spatial clustering of nests was more extreme during the second peak after controlling for breeding density. The patterns of genetic structure during the breeding season varied with parental sex and season. Genetic structure occurred during the second laying peak: males breeding within 200 m of one another at this time were significantly more closely related than males breeding farther apart. However, no apparent genetic structure was detected in males during the first laying peak or among females in either laying peak. These results reveal male-oriented kin affiliation during part of the breeding season in this species. Furthermore, juvenile recruitment into the winter flocks was positively related to this increased relatedness among males via kin affiliation. This study implies that fine-scale genetic structure during the breeding season could be a factor determining individual fitness and may play an important role in our understanding of the evolution of social systems.     

New genes of Xanthomonas citri subsp. citri involved in pathogenesis and adaptation revealed by a transposon-based mutant library

Background  

Citrus canker is a disease caused by the phytopathogens Xanthomonas citri subsp. citri, Xanthomonas fuscans subsp. aurantifolli and Xanthomonas alfalfae subsp. citrumelonis. The first of the three species, which causes citrus bacterial canker type A, is the most widely spread and severe, attacking all citrus species. In Brazil, this species is the most important, being found in practically all areas where citrus canker has been detected. Like most phytobacterioses, there is no efficient way to control citrus canker. Considering the importance of the disease worldwide, investigation is needed to accurately detect which genes are related to the pathogen-host adaptation process and which are associated with pathogenesis.     

The serendipitous origin of chordate secretin peptide family members

Background  

The secretin family is a pleotropic group of brain-gut peptides with affinity for class 2 G-protein coupled receptors (secretin family GPCRs) proposed to have emerged early in the metazoan radiation via gene or genome duplications. In human, 10 members exist and sequence and functional homologues and ligand-receptor pairs have been characterised in representatives of most vertebrate classes. Secretin-like family GPCR homologues have also been isolated in non-vertebrate genomes however their corresponding ligands have not been convincingly identified and their evolution remains enigmatic.     

Isolation of 18 polymorphic microsatellite loci from the North American red squirrel,Tamiasciurus hudsonicus (Sciuridae,Rodentia), and their cross‐utility in other species

We isolated 18 polymorphic microsatellite loci to be used for pedigree analysis in a wild population of North American red squirrels, Tamiasciurus hudsonicus. Allelic diversity and observed heterozygosity ranged from six to 13 and 0.39 to 0.89, respectively, in a sample of 93 individuals. Up to 13 sets of primers also amplify in other rodent species.     

Assessment of 17 new whiskered auklet (Aethia pygmaea) microsatellite loci in 42 seabirds identifies 5–15 polymorphic markers for each of nine Alcinae species

We isolated 17 microsatellite loci in the whiskered auklet (Aethia pygmaea) and tested them for amplification in 48 species from 13 seabird families (including 42 seabirds). Fifteen of these loci were also tested for polymorphism in 38 of the species, which included nine species of Alcinae (four auklets, Atlantic puffin, dovekie, razorbill and two murre species). On the average, nine loci were polymorphic per Alcinae species.