Flow Cytometry Identification of X- and Y-Chromosome-Bearing Goat Spermatozoa

Flow cytometric sorting technology was used to measure the difference in DNA content between X- and Y-chromosome-bearing spermatozoa in bucks. Spermatozoa were analysed by flow cytometry to characterize X- and Y-chromosome-bearing sperm populations and to quantify the DNA difference between them. Two symmetrical, overlapping and clearly separated peaks, corresponding to X- and Y-bearing spermatozoa, were detected. The difference in fluorescence intensity between the peaks was 4.4 +/- 0.03% without any significant inter- or intra-animal variations. Therefore, the identification and selection of high-purity samples of sperm populations for sex sorting is easier in bucks compared with other domestic species.     

Review: The strobilurin fungicides

The original article to which this Correction refers was published in Pest Management Science 58 (7): 649–662 (2002).Copyright © 2004 Society of Chemical Industry     

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.     

Effect of bovine seminal plasma on bovine endometrial epithelial cells in culture

The purpose of this study was to investigate the effect of seminal plasma (SP) from bulls of known fertility on bovine endometrial epithelial cells (bEEC) in culture. The bEEC from passage 5, approximately 5.0–13 × 10⁵ cells per flask, were challenged with SP from bulls of high or low fertility (n = 3 and 2, respectively) or PBS (control), at 1% (75 μl) or 4% (300 μl) and were incubated for 72 hr (n = 13 per challenge). Total cell number and viability of bEEC after challenge with 1% SP from either high‐ or low‐fertility bulls (75H or 75L, respectively) did not differ from controls. In contrast, challenge with 4% of SP from high‐ or low‐fertility bulls (300H or 300L) negatively affected bEEC cell number and viability. Challenge with 300 L had a greater adverse effect than 300H. These results suggest that the negative effect of bovine SP on bEEC is both dose‐dependent and fertility‐dependent.     

A framework for evaluation of on-farm mastitis diagnostics in Australia

Numerous culture-based diagnostics are available on the Australian and international markets for on-farm detection of bacterial pathogens in milk. Use of such diagnostics may provide an opportunity to improve the prudent use of antimicrobials in udder health management. Farms are low-resource settings in terms of diagnostic microbiology capacity. The World Health Organisation has identified criteria for the evaluation of diagnostic tests in low resource settings based on Accuracy, Sensitivity, Specificity, User-friendliness, being Rapid or Robust, Equipment-free and being Deliverable (ASSURED). Here, we review how those criteria can be interpreted in the context of microbiological diagnosis of mastitis pathogens, and how on-farm diagnostics that are currently available in Australia perform relative to ASSURED criteria. This evaluation identifies multiple trade-offs, both with regard to scientific criteria and with regards to convenience criteria. More importantly, the purpose of testing may differ between farms, and test performance should be evaluated relative to its intended use. The ability of on-farm mastitis diagnostics to inform mastitis treatment decision-making in a timely and cost-effective manner depends not just on test characteristics but also on farm-specific pathogen prevalence, and on the farm enterprise's priorities and the farm manager's potential courses of action. With most assay evaluations to date conducted in professional laboratories, there is a surprising dearth of information on how well any of the diagnostic tests perform on-farm and, indeed, of the on-farm decision-making processes that they aim to inform.     

Multilocus sequence typing detects new Piscirickettsia salmonis hybrid genogroup in Chilean fish farms: Evidence for genetic diversity and population structure

Piscirickettsia salmonisis the causative bacterial pathogen of piscirickettsiosis, a salmonid disease that causes notable mortalities in the worldwide aquaculture industry. Published research describes the phenotypic traits, virulence factors, pathogenicity and antibiotic‐resistance potential for various P. salmonisstrains. However, evolutionary and genetic information is scarce for P. salmonis. The present study used multilocus sequence typing (MLST) to gain insight into the population structure and evolution of P. salmonis. Forty‐two Chilean P. salmonisisolates, as well as the type strain LF‐89^T, were recovered from diseased Salmo salar, Oncorhynchus kisutchand Oncorhynchus mykissfrom two Chilean Regions. MLST assessed the loci sequences of dnaK, efp, fumC, glyA, murG, rpoD and trpB. Bioinformatics analyses established the genetic diversity among P. salmonis isolates (H = 0.5810). A total of 23 sequence types (ST) were identified, 53.48% of which were represented by ST1, ST5 and ST2. Population structure analysis through polymorphism patterns showed few polymorphic sites (218 nucleotides from 4,010 bp), while dN/dS ratio analysis indicated purifying selection for dnaK, epf, fumC, murG, and rpoD but neutral selection for the trpB loci. The standardized index of association indicated strong linkage disequilibrium, suggesting clonal population structure. However, recombination events were detected in a group of seven isolates. Findings included genogroups homologous to the LF‐89^T and EM‐90 strains, as well as a seven‐isolate hybrid genogroup recovered from both assessed regions (three O. mykiss and four S. salar isolates). The presented MLST scheme has comparative potential, with promising applications in studying distinct P. salmonis isolates (e.g., from different hosts, farms, geographical areas) and in understanding the epidemiology of this pathogen.     

Analysing the growth of turbot (<Emphasis Type="Italic">Psetta maxima</Emphasis>) in a commercial recirculation system with the use of three different growth models

The growth data of a commercial aquaculture recirculation system were analysed to investigate the growth performance of reared turbot (Psetta maxima). Three common growth models (von Bertalanffy, Gompertz and Schnute) were fitted to the growth data documented over a time period of 6 years. To determine the most suitable model, three different criteria were used: (1) the Akaike index criterion, (2) the sum of squared residuals and (3) the average daily deviation between the estimated final weight and the observed final weight. The evaluation of the growth models showed that the Schnute model had the lowest Akaike index, the lowest sum of squared residuals and the lowest daily deviation between estimated and real weight of all tested growth models. The Schnute model produced sigmoid growth curves. The estimated growth coefficients were the most realistic ones in regard to biological interpretation. In contrast, the von Bertalanffy growth model and the Gompertz model estimated inaccurate exponential growth curves and are therefore unable to simulate the growth data as well as the Schnute model. The results indicate that the von Bertalanffy growth model is not the optimal model to simulate the present growth data and that the growth potential of reared turbot has probably not yet been fully exploited in the aquaculture system(s) examined (so far).