A canine DNM1 mutation is highly associated with the syndrome of exercise-induced collapse

Labrador retrievers are the most common dog breed in the world, with over 200,000 new kennel club registrations per year. The syndrome of exercise-induced collapse (EIC) in this breed is manifested by muscle weakness, incoordination and life-threatening collapse after intense exercise. Using a genome-wide microsatellite marker scan for linkage in pedigrees, we mapped the EIC locus to canine chromosome 9. We then used SNP association and haplotype analysis to fine map the locus, and identified a mutation in the dynamin 1 gene (DNM1) that causes an R256L substitution in a highly conserved region of the protein. This first documented mammalian DNM1 mutation is present at a high frequency in the breed and is a compelling candidate causal mutation for EIC, as the dynamin 1 protein has an essential role in neurotransmission and synaptic vesicle endocytosis.     

Thioridazine and EKG anomalies

Acute i.v. infusion but not daily oral administration of thioridazine-HCl in the dog produced EKG anomalies similar to those reported in psychiatric patients taking this drug. Lack of EKG effects after thioridazine-5-sulfoxide infusion and presence of anomalies after thioridazine at equivalent doses suggests further evaluation of the relationship between reported plasma levels of thioridazine and its ring-sulfoxide in association with EKG changes.     

Variability among five riparian cottonwood ( Populus fremontii Wats.) populations: an examination of size, density, and spatial distribution

Various abiotic and biotic factors are known to affect tree size, including age, genetics, and environment. Knowledge of size variation within natural riparian tree populations has both ecological and restorative importance. We determined tree sizes, basal area densities, and spatial distributions of 5 Populus fremontii Wats. populations within the Rio Grande watershed in New Mexico. At each site 10 randomly spaced plots, perpendicular to the river and extending from the river to the end of the forest, were established. Diameter at breast height (DBH) and distance to the river were determined for 1803 trees within the 5 populations, and stand cover (measured as basal area [BA] per hectare) was determined for each population. Significant variation in tree size and basal area density existed among sites. Mean DBH per site ranged from 11.7 to 58.4 cm and differed significantly ( P P 2 ha -1 . Spatial distribution of trees in relation to the river also differed among sites. Mean distance from the river ranged from 50 to 353 m and differed significantly ( P P. fremontii populations may be influenced by differences in water availability across a site; trees farthest from water sources may experience greater water stress and, therefore, growth limitation. Increasing BA cover with increasing tree size indicated no real thinning of mature trees within a population. Recruitment and establishment of cottonwood seedlings and saplings was evident only at sites with newly formed floodplains. For these 5 populations tree size appeared to be affected by environmental factors.     

Close linkage of c-Harvey-ras-1 and the insulin gene to affective disorder is ruled out in three North American pedigrees

Affective disorder (AD) is one of the major forms of functional psychoses. Although the mode of transmission is uncertain, family, twin and adoption studies strongly suggest a genetic involvement. Because a basic biochemical abnormality is not known, direct analysis of the disease using a probe for the defective gene is not possible. However, a specific locus can be tested for its relevance to the aetiology of AD by genetic linkage, using restriction fragment length polymorphisms (RFLPs). Using probes for the c-Ha-ras-1 oncogene and the insulin gene, Gerhard et al. and Egeland et al. found convincing evidence for close linkage between these markers and a locus for AD in a large Old Order Amish pedigree. In an attempt to confirm this finding, we examined three bipolar pedigrees outside the Amish population. Our results indicate the absence of linkage from 0 to 15% recombination frequency between AD and the insulin gene-HRAS1 region in these pedigrees.     

Thermodynamic control by frequent quantum measurements

Heat flow between a large thermal 'bath' and a smaller system brings them progressively closer to thermal equilibrium while increasing their entropy. Fluctuations involving a small fraction of a statistical ensemble of systems interacting with the bath result in deviations from this trend. In this respect, quantum and classical thermodynamics are in agreement. Here we predict a different trend in a purely quantum mechanical setting: disturbances of thermal equilibrium between two-level systems (TLSs) and a bath, caused by frequent, brief quantum non-demolition measurements of the TLS energy states. By making the measurements increasingly frequent, we encounter first the anti-Zeno regime and then the Zeno regime (namely where the TLSs' relaxation respectively speeds up and slows down). The corresponding entropy and temperature of both the system and the bath are then found to either decrease or increase depending only on the rate of observation, contrary to the standard thermodynamical rules that hold for memory-less (Markov) baths. From a practical viewpoint, these anomalies may offer the possibility of very fast control of heat and entropy in quantum systems, allowing cooling and state purification over an interval much shorter than the time needed for thermal equilibration or for a feedback control loop.