Dynamical Systems Approach to Higher-level Heritability

To explain higher-level heritability, we propose a dynamical systems approach, based on simulations of the high-dimensional replicator equation with mutation dynamics. We assume that all variants are generated from within the groups of variants through mutations. Simulating the equation with a random interaction matrix and possible variants, we report that this system tends to have many attractors, of fixed point, chaotic and quasiperiodic type. In a chaotic attractor, special gene-like variants appear to control the heritability ofthe system, in the sense that removal of the variants would easily enable the system to depart from the attractor. Those variants do not predominate in thepopulation size, but have the lowest net reproduction and mutation rates on average. Because their rate of growth is small, they are named neutral phenotypes. Additionally, combinatorial effects of these neutral variants to the entire system are reported.     

New gene assignments using a complete, characterized sheep-hamster somatic cell hybrid panel

The generation and characterization of new sheep-hamster cell hybrids is reported from the fusion of sheep white blood cells with six different hamster auxotrophs. Selection from these and previously generated cell hybrids has led to the production of a panel of 30 hybrids covering the complete sheep genome of 28 chromosomes. Over half of the cell hybrids in this panel contain single sheep chromosomes. By complementation, the following new assignments have been made using the panel: phosphoribosyl N-formylglycinamide amidotransferase (PRFGA) to sheep chromosome (chr) 11; adenylosuccinate synthetase (ADSS) to sheep chr 12; adenylosuccinate lyase (ADSL) to sheep chr 3q; 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGCS) to sheep chr 16; dihydrofolate reductase (DHFR) to sheep chr 5; and adenine phosphoribosyltransferase (APRT) to sheep chr 14. The gene phosphoribosylaminoinidazole-carboxamide formyltransferase/Inosinicase (PRACFT) has now been regionally assigned to chr 2q. By isozyme analysis, phosphogluconate dehydrogenase (PGD) was assigned to sheep chr 12, anchoring the sheep syntenic group U1 to this chromosome, and mannose phosphate isomerase (MPI) was assigned to sheep chr 18. Furthermore, the chromosomal assignment of 110 microsatellites was confirmed using this cell panel.     

Vegetation mapping with the aid of low-altitude aerial photography

Abstract. A technique for fine-scale vegetation mapping with the aid of low-altitude aerial photography was developed. The procedure is as follows: 1. The site is divided into a lattice pattern - in case the site is too large to fit into a single photograph with satisfactory resolution. The coordinates of every lattice point are surveyed to be used as control points for geometric correction. A photograph of each block of the lattice is taken using a remote-controlled camera system lifted by a captive helium balloon. 2. The vegetation is classified on the basis of a phytosociological survey. 3. The shapes and locations of vegetation patches appearing in the photographs are entered into a computer, using a digitizer. A geometric correction is carried out through coordinate transformation referring to the coordinates of the control points and subsequently a draft vegetation map is produced. Finally, discrepancies are corrected and the map is coloured to produce the final version of the vegetation map. This technique was applied to vegetation mapping at a bar, 500 m wide and 2 km long, in the river Yoshino in Shikoku, Japan. A fine-scale vegetation map was obtained and used to analyse the influence of plants on geomorphic processes and community-specific hydrogeomorphic conditions on the bar.     

Fine mapping of the chicken salmonellosis resistance locus (SAL1)

Salmonella enterica serovar Typhimurium is a Gram-negative bacterium that has a significant impact on both human and animal health. It is one of the most common food-borne pathogens responsible for a self-limiting gastroenteritis in humans and a similar disease in pigs, cattle and chickens. In contrast, intravenous challenge with S. Typhimurium provides a valuable model for systemic infection, often causing a typhoid-like infection, with bacterial replication resulting in the destruction of the spleen and liver of infected animals. Resistance to systemic salmonellosis in chickens is partly genetically determined, with bacterial numbers at systemic sites in resistant lines being up to 1000-fold fewer than in susceptible lines. Identification of genes contributing to disease resistance will enable genetic selection of resistant lines that will reduce Salmonella levels in poultry flocks. We previously identified a novel resistance locus on Chromosome 5, designated SAL1 . Through the availability of high-density SNP panels in the chicken, combined with advanced back-crossing of the resistant and susceptible lines, we sought to refine the SAL1 locus and identify potential positional candidate genes. Using a 6^th generation backcross mapping population, we have confirmed and refined the SAL1 locus as lying between 54.0 and 54.8 Mb on the long arm of Chromosome 5 ( F  = 8.72, P  = 0.00475). This region spans 14 genes, including two very striking functional candidates; CD27-binding protein ( Siva ) and the RAC -alpha serine/threonine protein kinase homolog , AKT1 ( protein kinase B , PKB ).     

A linkage group on pig chromosome 4 comprising the loci for blood group L, GBA, ATP1B1 and three microsatellites

Restriction fragment length polymorphisms (RFLPs) were described for the porcine loci for β-glucosidase (GBA) and the β-polypeptide 1 of the Na⁺, K⁺-transporting ATPase (ATP1B1). Linkage analyses using a three-generation pedigree provided evidence for the assignment of ATP1B1, GBA and two microsatellite loci (S0001 and S0067) to a previously described linkage group comprising the loci for blood group L (EAL) and an anonymous microsatellite (S0097). The linear order of the six markers was determined with confidence by multipoint analyses and the length of the linkage group was estimated at 88 CM. This linkage group was assigned to pig chromosome 4 on the basis of a previous physical localization of the ATP1B1 gene. In situ hybridization data for S0001 presented in this study were consistent with a localization on chromosome 4 and suggested a regional localization to 4pl2-pl3. The present study reveals conflicting data concerning the genetic localization of the K88 loci controlling the expression of the receptors for the E. coli pilus antigens. One group has reported data suggesting a loose linkage between K88 and EAL, now mapped to chromosome 4, whereas two other groups have found linkage between K88 and the transferrin locus (TF), mapped to chromosome 13 by in situ hybridization.     

Aroid scarabs in the genus Peltonotus Burmeister (Coleoptera,Scarabaeidae, Dynastinae): key to species and new distributional data

The southeast Asian scarab beetle genus Peltonotus Burmeister (Scarabaeidae, Dynastinae, Cyclocephalini) is reviewed. New country records for Peltonotus morio Burmeister (Myanmar and Vietnam), Peltonotus nasutus Arrow (southern China and Cambodia), and Peltonotus favonius Jameson and Wada (Myanmar) are reported, including a new record in the Palearctic/Sino-Japanese biogeographic region. The first female specimen of Peltonotus favonius is described. Biological associations with aroid inflorescences are reviewed, and human consumption of Peltonotus beetles is reported. A key to all species, paralectotype designations for Peltonotus nasutus, diagnoses, and distributions using dynamic mapping tools are included.