Barking foxes, Alopex lagopus: field experiments in individual recognition in a territorial mammal

During field studies on a wild population of Arctic foxes, Alopex lagopus, on the Commander Island Mednyi (Northern Pacific) we examined whether acoustic long-distance signals were used for individual recognition. Barks of 10 individually known animals from five neighbouring groups were tape recorded. The spectral characteristics of the barks were described in terms of averaged 1/12 octave spectra.With a discriminant function analysis, more than 90% of the calls could be assigned to the correct individual on the basis of the spectral parameters. Discrimination was only slightly improved when we added temporal parameters to the analysis. We carried out playback experiments with eight foxes near the territory boundary of their family groups. The foxes were significantly more likely to respond with territorial behaviour and longer barking bouts to playbacks of neighbours or strangers than to playbacks of group members. We conclude that individuals can distinguish between barks of members of their own social group and those of other foxes. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

No statistical support for correlation between the positions of protein interaction sites and alternatively spliced regions

Background  

Alternative splicing is an efficient mechanism for increasing the variety of functions fulfilled by proteins in a living cell. It has been previously demonstrated that alternatively spliced regions often comprise functionally important and conserved sequence motifs. The objective of this work was to test the hypothesis that alternative splicing is correlated with contact regions of protein-protein interactions.     

LDL receptor-related proteins 5 and 6 in Wnt/beta-catenin signaling: arrows point the way

Wnt signaling through the canonical beta-catenin pathway plays essential roles in development and disease. Low-density-lipoprotein receptor-related proteins 5 and 6 (Lrp5 and Lrp6) in vertebrates, and their Drosophila ortholog Arrow, are single-span transmembrane proteins that are indispensable for Wnt/beta-catenin signaling, and are likely to act as Wnt co-receptors. This review highlights recent progress and unresolved issues in understanding the function and regulation of Arrow/Lrp5/Lrp6 in Wnt signaling. We discuss Arrow/Lrp5/Lrp6 interactions with Wnt and the Frizzled family of Wnt receptors, and with the intracellular beta-catenin degradation apparatus. We also discuss the regulation of Lrp5/Lrp6 by other extracellular ligands, and LRP5 mutations associated with familial osteoporosis and other disorders.     

The Rhodobacter capsulatus genome

The genome of Rhodobacter capsulatus has been completely sequenced. It consists of a single chromosome containing 3.5 Mb and a circular plasmid of 134 kb. This effort, started in 1992, began with a fine-structure restriction map of an overlapping set of cosmids that covered the genome. Cosmid sequencing led to a gapped genome that was filled by primer walking on the chromosome and by using lambda clones. Methods had to be developed to handle strong stops in the high GC (68%) inserts. Annotation was done with the ERGO system at Integrated Genomics, as was the reconstruction of the cell's metabolism. It was possible to recognize 3709 orfs of which functional assignments could be made with high confidence to 2392 (65%). Unusual features include the presence of numerous cryptic phage genomes embedded in the chromosome. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Brassica MIP-MOD gene encodes a functional water channel that is expressed in the stigma epidermis

In crucifers, the ability of the stigma to differentially modulate hydration of pollen grains, depending on whether the pollen is recognized to be compatible or incompatible, represents a crucial stage in pollination. Our recent analysis of the mod mutation of Brassica, which results in a breakdown of the self-incompatibility response, led to the isolation of a gene linked to the MOD locus which is expressed at low levels in mod mutants. The gene is predicted to encode a plasma membrane-localized aquaporin-like protein and has been designated MIP-MOD. We utilized reporter gene analysis to demonstrate that the MIP-MOD promoter is active in Brassica papillar cells as well as in some vegetative tissues. The encoded protein is also likely to be plasma membrane-localized based on the observation that all plasma membrane-intrinsic aquaporin-like proteins in Brassica leaves are enriched in plasma membrane fractions. The MIP-MOD protein results in a low but measurable enhancement in osmotic water permeability of Xenopus oocytes and hence represents a functional aquaporin. The results are consistent with the notion that MIP-MOD is involved in the regulation of water transport across the stigma epidermal cell membrane.     

EGFP as a fusion partner for the expression and organic extraction of small polypeptides

Green fluorescent protein (GFP) is widely used as an excellent reporter module of the fusion proteins. The unique structure of GFP allows isolation of the active fluorescent protein directly from the crude cellular sources by extraction with organic solvents. We demonstrated the stable expression of four short polypeptides fused to GFP in Escherichia coli cells, including antimicrobial cationic peptides, which normally kill bacteria. EGFP module protected fusion partners from the intracellular degradation and allowed the purification of the chimerical proteins by organic extraction. The nature of the polypeptide fused to GFP, as opposed to the order of GFP and the polypeptide modules in the fusion protein, influenced the efficiency of the described purification technique.