Equine pituitary pars intermedia dysfunction: current understanding and recommendations from the Australian and New Zealand Equine Endocrine Group

The purpose of this article is to provide a review of the current knowledge and opinions about the epidemiology, clinical findings (including sequelae), diagnosis, treatment and monitoring of equine pituitary pars intermedia dysfunction, particularly in the Australian context. This information and the recommendations provided will assist practitioners in making informed decisions regarding the diagnosis and management of this disorder.     

Assessing opportunity and relocation costs of marine protected areas using a behavioural model of longline fleet dynamics

Increasing use of spatial management tools in fisheries requires an understanding of fleet response, and in particular to where displaced fishing effort is likely to move. We develop a state‐dependent decision‐making model to address the spatial allocation of effort in an Australian tuna longline fishery. We assume that fishers have an economic objective in deciding where to fish, but that decisions in any period are also influenced by the remaining quota held at the time of the decision. Key features of the model include endogenous price dynamics, a moving stock and a competitive pool of different vessel types operating from different port locations. We utilize this model to illustrate fleet responses to marine reserves and limits on fishing effort. The results illustrate that the model framework provides advantages over statistically based models in that decisions made in response to the imposition of a reserve are not consistent with a proportional reallocation of effort. Rather, the stochastic dynamic model yielded an overall profit level of ～4% higher relative to scenarios with no reserve. Incorporating the opportunity cost of a quota into the model resulted in an optimal utilization of effort, in which effort was concentrated in time periods and locations yielding maximized profit. Under a low level of effort relative to the season length, the model indicated an overall profit level 43% greater than the highest obtained when the same level of effort was applied solely within any given quarter of the season.     

Flowing solution culture system maintains uniform root environment composition

Flowing solution culture enables the researcher to study effects of root environment variables independently. This flowing solution culture system utilizes air pressure and syphoning or a peristaltic pump to circulate the nutrient solution. Because this system is inexpensive, simple in design, and compact, several factors can be studied concurrently, treatments can be replicated to test for system effects, nutrient deviations, and block for growth effects due to environment. These systems have been used successfully with experiments in N form, plant growth regulators, salt stress, and mechanical stress. Non‐destructive measurements of root growth and nutrient uptake are possible.     

Evidence for the Predisposition of Fungicide-Resistant Isolates of Venturia inaequalis to a Preferential Selection for Resistance to Other Fungicides

In the United States, populations of the apple scab pathogen Venturia inaequalis have progressed through three consecutive rounds of fungicide resistance development, first to dodine, then to the benzimidazoles, and most recently to the sterol demethylation inhibitors (DMIs). Analysis of extensive monitoring data have to date provided no indication of detectable cross-resistance or partial cross-resistance of V. inaequalis populations to the three unrelated classes of fungicides prior to the selection of resistant subpopulations. However, in this study, resistance to both benomyl and DMIs developed to significantly higher frequencies within the previously established dodine-resistant population than in the population sensitive to dodine. Accelerated selection of phenotypes double resistant to dodine and the DMI fenarimol was apparent over the course of distinct seasons of apple scab management with either dodine or fenarimol. The data provide evidence for an accelerated speed of resistance development among phenotypes of V. inaequalis already resistant to an unrelated fungicide. This finding represents a departure from the previous model, which assumed entirely independent rounds of resistance developments. The data indicate that phenotypes of V. inaequalis might not only be selected for the trait of fungicide resistance but also for traits allowing a more flexible response to changes in the environment where they compete.     

Evaluation of PCR,IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4–6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given. © 2001 Society of Chemical Industry     

Intracellular regulation of endometrial PGF(2a) and PGE(2) production in dairy cows during early pregnancy and following treatment with recombinant interferon-tau

Objectives were to examine how the conceptus and recombinant bovine interferon-tau (rbIFN-tau) regulate intracellular components of the PGF(2a) synthetic pathway and to determine if arachidonic acid (AA) is limiting in endometrial tissue of pregnant cows. In Experiment 1, uteri were collected from either cyclic or pregnant dairy cows on Day 17 post-estrus. Intercaruncular explants were dissected and incubated for 60 min to quantify PGF(2a) production in response to oxytocin (10(-6) M), A23187 (10(-5) M), melittin (10(-5) M), and phorbol 12, 13 dibutyrate (PDBu, 10(-6) M). Additional explants from the same cows were incubated for 24 h with and without AA. Oxytocin and A23187 did not stimulate PGF(2a) in explants from either cyclic or pregnant cows. Both PDBu, melittin, and A23187 + melittin stimulated PGF(2a) production in explants of cyclic cows, but not in explants of pregnant cows. The addition of AA to explant cultures for 24 hr did not increase PGF(2a) production during a subsequent 60-min incubation. In Experiment 2, explants were collected from cows that received intrauterine infusions of either BSA (1.9 mg/1.2 ml) or rbIFN-tau (0.2 mg rbIFN-tau + 1.7 mg BSA/1.2 ml) twice a day from Days 14 to 17 of the estrous cycle. Treatments of rbIFN-tau attenuated PGF(2a) secretion induced by in vitro PDBu and A23187 treatments. However, rbIFN-tau treatment in vivo had no effect on the in vitro induction of PGF(2a) secretion by melittin. IFN-tau may regulate the PGF(2a) synthetic pathway by reducing activity of PKC or PKC mediated events.     

Nutritional stress as a cause of thymic atrophy in broiler chickens

A study was conducted to examine the effect of nutritional stress on the development of the thymus, bursa, and pancreas of 7-to-14-day-old commercial meat-type chickens. One group of 7-day-old chickens was given access to food for only 30 minutes daily for 7 days. The birds were necropsied, and the thymus, pancreas, and bursa were compared with those of the control chickens fed ad libitum and necropsied at 7 and 14 days of age. The thymuses from birds on the restricted diet were atrophied (0.45 +/- 0.08 g) and congested compared with the thymuses from chickens fed ad libitum (1.32 +/- 0.31 g). The bursae from chickens on a restricted diet were also smaller (0.26 +/- 0.08 g) than the bursae from birds with free access to food (0.74 +/- 0.11 g). The restricted diet did not appear to cause any gross or histological pancreatic changes. The thymic lesions produced by nutritional stress were similar to those observed in the runting/stunting syndrome.