Genes lost and genes found: evolution of bacterial pathogenesis and symbiosis

Traditionally, evolutionary biologists have viewed mutations within individual genes as the major source of phenotypic variation leading to adaptation through natural selection, and ultimately generating diversity among species. Although such processes must contribute to the initial development of gene functions and their subsequent fine-tuning, changes in genome repertoire, occurring through gene acquisition and deletion, are the major events underlying the emergence and evolution of bacterial pathogens and symbionts. Furthermore, pathogens and symbionts depend on similar mechanisms for interacting with hosts and show parallel trends in genome evolution.     

Three-dimensional polarimetric imaging of coronal mass ejections

We present three-dimensional reconstructions of coronal mass ejections (CMEs), which were obtained through polarization analysis of single-view images recorded with the use of the Large Angle and Spectrometric Coronagraph (LASCO) C2 coronagraph on board the Solar and Heliospheric Observatory (SOHO) spacecraft. Analysis of a loop-like CME shows a complex three-dimensional structure centered at 40 degrees from the plane of the sky, moving radially at 250 kilometers/second. Reconstruction of two halo CMEs suggests that these events are expanding loop arcades.     

Spatial Variability of Turbulent Mixing in the Abyssal Ocean

Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise. The diapycnal diffusivity there was estimated to be less than or approximately equal to 0.1 x 10(-4) meters squared per second. In contrast, mixing rates are large throughout the water column above the rough Mid-Atlantic Ridge, and the diffusivity deduced for the bottom-most 150 meters exceeds 5 x 10(-4) meters squared per second. Such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry.     

Comparison of qualitative and quantitative analyses of canine uroliths

A study was performed to compare qualitative test results of canine uroliths with quantitative test results. Qualitative test results were in agreement with quantitative test results in only 96 of 223 specimens (43 per cent). Lack of agreement was caused by false-negative qualitative test results (85 of 223), false-positive qualitative test results (15 of 233), and a combination of false-negative and false-positive qualitative test results (27 of 233). This study indicates that the veterinary profession should abandon exclusive use of qualitative chemical test kits for uroliths.     

Resolution of a Left Ureteral Stone Using Electrohydraulic Lithotripsy in a Thoroughbred Colt

A 3-year-old Thoroughbred colt was presented for evaluation of azotemia and anorexia. Physical examination revealed a ureterolith in the left ureter, approximately 10 cm from the bladder, which was thought to obstruct urine flow by approximately 90% when viewed cystoscopically. Ultrasonographic examination of both kidneys revealed indistinct corticomedullary junctions, and the right kidney was more hyperechoic. A percutaneous biopsy of the right kidney revealed chronic interstitial nephritis with marked interstitial medullary fibrosis. Medical therapy consisting of IV fluids, sodium chloride PO, and ammonium chloride PO was initiated. Ureteroscopic electrohydraulic lithotripsy via a perineal urethrostomy was used to successfully remove the stone. Klebsiella oxytoca , which responded to oral enrofloxacin therapy, was cultured from the urine after surgery. Azotemia resolved and the horse resumed training.     

The effect of absolute alterations in energy concentration of developing and finishing diets for the large white Turkey on performance and carcass quality with a note on the correlation of back skin fat and grade of finish 1

A commercial strain of large white turkey was fed maize‐soybean meal type rations from 8 to 21 (for hens) and 23 weeks of age (for toms). During the developing period (8–18 weeks) each sex was offered diets having either a “high” or “low” energy concentration. To assure energy as the only dietary variable while con‐comitantly effecting a reasonable separation in caloric density, 3 per cent tallow was substituted by an equal amount of cellulose. At 18 weeks of age, the birds representing each of the developing period treatments, were subdivided into 3 further groups and subsequently offered the experimental finishing rations. These terminal diets, through the use of tallow, glucose and cellulose, were altered in energy content (2202, 2642, and 3083 kcal ME/kg) and respectively rated “low”, “moderate” and “high” in caloric concent. All birds were slaughtered, their specific gravity determined, and the quantity of fat in skin taken from the dorsal surface determined.

Though there was a reduced weight gain with those birds fed the “low” energy finishing diet, growth of all other turkeys, irrespective of sex, was comparable regardless of treatment during the developing period while the F/G ratio was altered to accommodate caloric density alterations. Excepting those groups offered the “low” energy finisher, period and cumulative consumption of metabolisable calories, like weight gain, was near equal. Dressing percentage and grade of fleshing essentially paralleled what was obtained with growth. There were no obvious effects due to developing period treatment or with the upper two levels of energy in the finishing ration; however, both of the aforementioned parameters were noticeably poorer when the “low” energy finisher was fed. The grade of finish of both the breast and back was found to improve with an increasing dietary caloric density of the terminal ration. Though there were no apparent effects on breast finish due to development period treatment, differences were noticed with the quality of back finish.

It is speculated that the grade of back finish can be confounded by a subdermal fat depot. This additional lipid deposit is probably a carry‐over from the developing period; hence, dietary adequacy during this time could influence ultimate grade of back finish.

Back skin fat, expressed as a percentage of dry weight, was found to be highly correlated with grade of finish on both the breast and back. Calculation of linear least squares lines indicated little or no difference with area of finish assessment; however, the correlation coefficient, apparently because of variations caused by developmental period dietary energy alterations, was lower on the back than the breast (r = ‐0.756 vs r = ‐0.771).     

The occurrence of congenital heart defects in an inbred herd of pigs in Australia

OBJECTIVE: To report on the first case of congenital heart defects in pigs in Australia. DESIGN: Retrospective analysis of case records from an inbred herd of "Westran" pigs at the University of Sydney, between January 2001 and December 2004. Detailed gross and histological examination of 15 hearts from pigs that had died or were euthanased in 2004. CASE DETAILS: The necropsy records from a population of 471 pigs that had died (106 pigs) or were euthanased for research purposes (365 pigs) were analysed and the incidence of heart defects recorded, together with basic demographic data. No attempts were made to diagnose the condition in live pigs. RESULTS: Congenital heart defects were diagnosed in 6.4% of pigs but this is likely to be an underestimate of the incidence of the deformity. Eighteen pigs died on the farm as a result of the defect, and 12 pigs were diagnosed with the defect as an incidental finding. The most common abnormality seen at necropsy was a sac-like dilatation on the right lateral surface of the right atrium. This was associated with secondary deformity and hypoplasia of the adjacent left ventricle, interventricular region and part of the right ventricle. All hearts showed atrial septal defects of varying size. CONCLUSION: This is the first reported case of congenital heart defects in pigs in Australia, and one of less than five reported cases of atrial septal defects in pigs in the world. The authors conclude that there may be an element of genetic predisposition to the malformation, since it has only been reported in this inbred line of pigs.