Comparison of the Level(s) of DNA Damage Using Comet Assay in Bovine Oocytes Subjected to Selected Vitrification Methods

It was suggested that the cryodamage to oocytes' DNA has been responsible for the compromised developmental competence of cryopreserved oocytes. Vitrification of bovine oocytes affected not only cellular components, but also nuclear material. A significant rate of DNA fragmentation was found in bovine frozen or vitrified oocytes analysed by Comet assay regardless of cryopreservation method. Our method of vitrification using droplet system after gentle pre-equilibration treatment is one of the most effective cryopreservation methods employed for bovine oocytes so far, making it possible to develop 30% blastocyst stage embryos. In this study, the extent of DNA damage in bovine oocytes vitrified using three vitrification methods (droplet system, Open Pulled Straw and traditional vitrification in 0.25 ml insemination straws) was compared using Comet assay. Vitrification in droplet system and Open Pull Straws vitrification did not result in detectable cryoinjuries of DNA of bovine oocytes. On the contrary, DNA fragmentation was found in four of 26 oocytes vitrified in 0.25 ml straws (15.4%, p   ≤ 0.05 in comparison with the other vitrification methods).     

Acid–Base Changes in Canine Neonates Following Normal Birth or Dystocia

There are limited data concerning blood gas parameters in neonatal dogs. Knowledge of the normal physiology may facilitate effective therapeutic intervention and potentially reduce neonatal mortality. This study examined acid–base parameters in pups born at normal parturition (n = 27) compared with those born after obstetrical assistance or caesarean operation (n = 13) and those born following oxytocin (OXY) administration for treatment of uterine inertia (n = 11). Pups were subjected to an objective scoring method of neonatal health adapted from use in humans (the Apgar score) at birth and again at 5 and 60 min after birth. Venous blood samples were collected at 5 and 60 min after birth for evaluation of blood gas parameters. At birth, all pups had low Apgar scores and a mixed acidosis. The base excess was lowest for pups delivered after OXY administration. The Apgar score improved for all pups after 5 min of birth and there was an improvement in carbon dioxide tension, base excess and venous blood pH at 1 h, although in all pups a metabolic acidosis persisted. These data provide an important insight into neonatal physiology and the variability of blood gas parameters in pups born at normal and abnormal parturition and provide the basis for clinical decision making following dystocia.     

Ligation of the caudal mesenteric artery during resection and anastomosis of the colorectal junction for annular adenocarcinoma in two dogs

An 8-year-old terrier cross and a 10-year-old German Shorthaired Pointer presented to the University Veterinary Centre, Sydney, for investigation of long-standing tenesmus and dyschezia. Both patients had an annular adenocarcinoma at the colorectal junction. Exploratory laparotomy was performed and the affected large intestinal segment was removed by resection and anastomosis. In both dogs, the caudal mesenteric artery was intimately associated with the mass, necessitating its ligation and transection. Postoperatively, there was no evidence of anastomosis breakdown in either case and both animals recovered well from surgery. The dogs were euthanased 8 and 10 months, respectively, after surgery because of clinical signs relating to metastatic disease.     

A herd-level analysis of risk factors for antibodies to Sarcocystis neurona in Michigan equids

Equine protozoal myeloencephalitis (EPM) is a neurological disease of horses and ponies caused by infection of the central nervous system with the protozoan parasite Sarcocystis neurona. A herd-level analysis of a cross-sectional study of serum antibodies to S. neurona in Michigan equids was conducted, using data collected in 1997 for study that included 1121 equids from 98 Michigan horse farms. Our objective was to identify specific herd-level risk factors associated with seropositivity. We tested associations between herd seroprevalence and various farm-management practices (including feed-storage methods and wildlife control). Multivariable models were developed for three strata based on relative opossum abundance (opossum districts). Herd seroprevalence ranged from 0 to 100% (median=57%). No risk factor was significantly associated with herd seroprevalence at P< or = 0.05 in all opossum districts. Our results suggest that equids living in areas with large opossum populations might be infected with S. neurona from multiple sources.     

Canberra''s Urban Forest: Evolution and planning for future landscapes

Canberra, Australia's national capital, is a planned city established on grazing lands in the southern tablelands of New South Wales. Over the past nine decades it has grown into a garden city of 300,000 people. Landscaping was an early priority as much of the chosen site for the city was a treeless plain. Major tree planting began in the 1920's and today the urban forest on public lands contains 400,000 trees from over 200 species in streets and parklands. The species used have changed over time with exotic deciduous trees and conifers dominating early plantings. By the 1970's native species, mostly eucalypts, were planted. Today fewer species comprising an equal mix of native and exotics are used. Trees in the earlier plantings are now mature and given the harshness of the local climate many will come to the end of their ‘safe life’ in the early decades of this century. This provides new challenges for urban tree managers as to how to effect tree replacement that is aesthetically pleasing, ecologically sound and socially acceptable. To assist in this planning a tree data base and modeling system has been assembled. This system – Decision Information System for Managing Urban Trees or DISMUT – facilitates the development of forest-level management programs by allowing the projection of change and work requirements that the result from historical and current plantings over the entire urban forest.     

导管螺旋桨在拖网渔船上的设计与应用

根据目前拖网渔船在节能方面的需要,采用导管螺旋桨以改善渔船的推进性能,并对导管螺旋桨的设计和具体应用的优的缺点作初步的探讨。