Expression of Apoptosis Regulatory Genes and Incidence of Apoptosis in Different Morphological Quality Groups of In Vitro‐produced Bovine Pre‐implantation Embryos

Apoptosis occurs during early development in both in vivo‐ and in vitro‐produced embryos, and is considered as one of the causes of embryonic loss. The objectives of this study were, therefore, investigating stage‐specific expression profiles of apoptosis regulatory genes in three quality groups of in vitro‐produced bovine pre‐implantation embryos; and analysing the relationship between cell number and DNA fragmentation with expressions of those genes. The relative abundance of mRNA of 9 pro‐ (Bax, caspase‐9, Bcl‐xs, P53, Caspase‐3 and Fas) and anti‐ (Bcl‐w and Mcl‐1) apoptotic genes was analysed. Differential cell staining and terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end labelling were performed to analyse the variation in cell numbers and detect apoptotic nuclei respectively. Expression of Bax and Caspase‐3 genes was significantly (p < 0.05) higher in poor quality pre‐implantation embryos as compared with that of morphologically good quality embryos of the same developmental stages. Moreover, Mcl‐1 expression was significantly higher in good quality immature oocytes than that in the poor quality group. Moreover, higher DNA fragmentation was evidenced in morphologically poor quality blastocysts. In conclusion, our study demonstrates that Bax, caspase‐3 and Mcl‐1 can be used as potential markers of embryo quality to evaluate in vitro‐produced bovine embryos. Further studies are required to investigate specific molecular signatures that can be used in evaluating in vivo‐derived embryos.     

Growth and nutrition of Pinus radiata in response to fertilizer applied after thinning and interaction with defoliation associated with Essigella californica

Infestations of Essigella californica following the installation of post-thinning fertilizer trials in Pinus radiata plantations provided an opportunity to examine the impact of repeated defoliation over a period of 8 years (1997–2005). Replicated treatments (n = 4) of nil fertilizer (control), N (300 kg ha⁻¹) as urea, P (80 kg ha⁻¹) and S (45 kg ha⁻¹) as superphosphates were applied immediately after thinning at three sites and this was followed by a second application of NPS fertilizers 6 years later with N applied at 300 kg ha⁻¹ as urea and ammonium sulphate and P at 80 or 120 kg ha⁻¹. Defoliation of untreated P. radiata gradually increased to 50% over a period of 8 years. Basal area growth was negatively correlated with average defoliation for two consecutive post-fertilizer periods of 6 and 2 years. Growth responses to fertilizer varied considerably between sites but the largest improvement in growth was due to NPS fertilizer, this increased basal area by 30–80%. Application of N fertilizer raised total N levels in foliage and increased defoliation with a commensurate loss in growth under conditions of deficiencies of S or P. Repeated infestations gradually increased the percentage of trees with severe defoliation (>80% loss of foliage) indicating that nutrient-deficient trees have a reduced capacity for foliage recovery between episodes of peak infestation. In contrast, treatment with N fertilizer in combination with S- and P-corrected deficiencies of these nutrients, raised levels of total N in foliage and reduced defoliation to approximately 20%. Basal area growth responses to NPS fertilizers reflected improved nutrition as well as reduced insect damage. The reduction in defoliation under conditions of balanced tree nutrition was most likely due to enhanced needle retention following correction of P deficiency as well as greater availability of nutrients enabling a more vigorous recovery of P. radiata after an episode of E. californica activity. Treatment with fertilizer therefore reduced the long-term impact of aphid damage and improved growth of P. radiata.     

Evaluating the risk of the establishment of screwworm fly in Australia

Objective To investigate probabilities of establishment of screwworm fly throughout the year, for several locations around Australias coastline.
Methods A simulation model that predicts the spread and economic impact of an established screwworm fly population was modified to include stochastic survival functions, to investigate the risks of the pest actually establishing in this country. The effects of time of year, climate, vegetation and the number of incoming flies or larvae were investigated for four locations around Australia.
Results Analysis of variance identified a dominant three-way interaction between site, time, and the number of introduced flies. These probabilities are graphed.
Discussion In southern areas, as exemplified by Fremantle, the cold winters limit survival. A high probability of establishment exists year round in tropical regions, except in areas around the Gulf of Carpentaria and in the Northern Territory where dry weather mid-year would limit survival. Despite these comparatively lower risks, there were no areas or times where reductions in quarantine efforts could be justified.     

A Magnetic Signature at Io: Initial Report from the Galileo Magnetometer

During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by Io. A field decrease, of nearly 40 percent of the background jovian field at closest approach to Io, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at Io would explain the observations. It seems plausible that Io, like Earth and Mercury, is a magnetized solid planet.     

The occurrence of Dirofilaria immitis in dogs in South Australia

Heart, lung and samples of blood from 230 dogs were examined for infections of filarial parasites. Dirofilaria immitis worms and microfilariae were detected in one dog. Blood samples from a further 1428 dogs were examined for microfilariae and 22 were found to be infected. Eighteen dogs were infected with D immitis microfilariae and four with Dipetolonema reconditum microfilariae. The histories were available for 18 of the dogs infected with heartworm and only seven dogs had not travelled outside South Australia. It was concluded that heartworm infection was endemic in South Australia but the apparent prevalence was only about 1%.     

Ice crystal observations and the degree of riming in winter precipitation

Since snow crystals provide information on the processes leading to their formation and growth, their observation gives insight to the microphysics of cloud and precipitation. The capture of supercooled cloud droplets by snow crystals (riming) forms an important link between precipitation and cloudwater and thus plays an important role in wet deposition. In the project ‘Winter Precipitation at Mount Rigi’ ice crystals are collected at two stations at different elevations. The shape, size and degree of riming of each crystal are analyzed for more than 10000 crystals. Differences in the degree of riming of the crystals between the higher and the lower station are discussed. With the aid of Doppler radar data the location of snow crystal origin is estimated. Furthermore a relationship between the degree of riming of snow crystals and the vertical Doppler velocities is established.     

Modelling the potential impact of exotic diseases on regional Australia

SUMMARY: Recent international initiatives for disease control suggest that, in the future, the consequences for trade of an exotic disease outbreak may not be as severe as estimated in the past. If zoning were to be accepted by Australia's trading partners, then the major effects may be felt at the regional rather than the national level. A study, using an integrated epidemiological/economic model, was undertaken to compare the impacts of 3 important exotic diseases (foot-and-mouth disease, classical swine fever and sheep pox) in 3 different regions of Australia. The study demonstrated that there are significant differences between the size and effect of different disease outbreaks. Regional factors influence not only the way that the disease will spread and manifest itself, but also the effects on local communities. Foot-and-mouth disease caused more economic losses than sheep pox or classical swine fever. The major determinant of differences in the effects of the diseases between regions was the nature of the regional economies. The less diversified the economy, the greater the effect of an exotic disease outbreak in relation to the size of that economy.     

Advances in pasture management for animal productivity and health

A wide range of management techniques is available to enhance quantity and quality of forage supply to grazing animals throughout the annual production cycle. Within broad limits, dry matter (DM) production is relatively insensitive to management of defoliation frequency, severity and duration. However defoliation management has effects on feed quality which can be enhanced, in particular, by control of pasture growth in the spring through maintenance of relatively low average pasture masses. Treading damage can have significant immediate and ongoing effects on pasture production and farmers can use a range of management techniques to minimise these.

Fertiliser application practices have a potent influence on pasture production and seasonality of that production. Available soil nitrogen is the primary nutrient deficiency limiting production in New Zealand's characteristically grass-dominant pastures. Nitrogen fertiliser usage has increased markedly in recent years, particularly to grow substantially greater amounts of forage during the cool season, and this trend looks set to continue. However, the use of nitrogen fertiliser has important environmental implications.

Pasture renewal and forage crop use has also increased in recent years. Care needs to be taken in conducting cost-benefit analyses, selecting the options that best meet the needs, and in establishment and subsequent management practices. Ryegrass (perennial and hybrids) and white clover remain the primary choice for permanent pasture renewal, the availability of safe endophytes having largely alleviated effects of endophyte toxicosis. Special-purpose mixtures are used, especially in dry environments. Italian ryegrasses, brassicas and chicory are common choices for forage crops. A range of management techniques can be used to alleviate deleterious effects of some forages, including ryegrass endophyte toxicosis, facial eczema, and toxins associated with Fusarium fungi. Generally these techniques are not totally effective. More research is required to increase our understanding of these disorders, and in order to develop more effective and reliable management practices.