Variation among New Zealand isolates of Sphaeropsis sapinea

Sphaeropsis sapinea is a pathogen of many coniferous species and causes significant losses to the plantation forestry industries of many countries. New Zealand isolates of S. sapinea were examined for colony and morphological characteristics, and pathogenicity to Pinus radiata seedlings. Considerable variation was observed in colony growth form and colour, and in the growth rates on four agar media. The conidial dimensions, carbon and nitrogen utilization, and pathogenicity also varied among the isolates. The variation observed was such that the isolates could not be placed within previously described distinct morphotypes and the present results concur with previous studies cautioning the use of morphological criteria alone to partition the species. These results contrast markedly with previous reports and seemingly indicate a change in the New Zealand S. sapinea population. This difference may reflect the re‐introduction or spread of additional isolates or a shift in the structure of the resident population.     

Application of high-resolution melt curve analysis for classification of infectious bronchitis viruses in field specimens

Objective A real-time polymerase chain reaction (PCR)/high-resolution melt (HRM) curve analysis protocol was developed in our laboratory to differentiate infectious bronchitis (IB) virus reference strains. In the current study, this method was used to detect and classify IB viruses in field submissions. Procedure Over an 11-month period samples from 40 cases of suspected IB virus were received and 17 submissions were positive for IB virus by polymerase chain reaction. HRM curve analysis classified each strain as subgroup 1, 2 or 3 strain (12 submissions) or a strain that was unable to be classified (5 submissions). The 3′ untranslated region (UTR) and partial S1 gene nucleotide sequences for the 17 IB virus strains were determined and their identity with those of the relative reference strains compared to confirm the classifications generated using the HRM curve analysis. Results Of the 12 IB field viruses classified as subgroup 1, 2, or 3 using HRM curve analysis, the 3′UTR and S1 gene nucleotide sequences had identities ≥99% with the respective subgroup reference strain. Analysis of the 3′ UTR and S1 gene nucleotide sequences for the five IB virus strains that could not be classified indicated that four belonged to one of the subgroups, and one was a potential recombinant strain (between strains from subgroups 2 and 3). A novel recombinant strain was also detected. Conclusion HRM curve analysis can rapidly assign the majority of IB viruses present in field submissions to known subgroups. Importantly, HRM curve analysis also identified variant genotypes that require further investigation.     

Effect of unionized ammonia, viscosity and protozoan contamination on the enzyme activity of the rotifer Brachionus plicatilis

Substrates that are cleaved to yield fluorescent products can be used to quickly quantify enzyme activity in vivo with image analysis or in vitro with fluorometry. This study was carried out to determine whether enzyme activity in rotifers is useful for assessing the physiological condition of rotifers. Neonates of Brachionus plicatilis Müller hatched from cysts were exposed to a concentration series of unionized ammonia ranging from 0 to 9.8 p.p.m., increasing seawater viscosity relative to 1.17 to control sea water by the addition of methyl cellulose and the addition of the protozoan Euplotes sp. to a density of 40 mL^?1. Rotifer glucosidase and esterase activities decreased with increasing unionized ammonia and viscosity respectively. Activities of glucosidase and phospholipase decreased with increasing protozoan contamination. There was a significant relationship between enzyme activities and rotifer population growth. In vivo activities of certain rotifer enzymes can therefore serve as biomarkers for the rapid assessment of environmental stressors in rotifer mass cultures.     

Bacterial spores: chemical sensitization to heat

Spore heat resistance is largely an inducible property, chemically reversible between a sensitive and resistant state. Therefore, the constitutive assumption and common practices based on it, such as direct testing of spores for heat resistance without prior treatment and the assumption of logarithmic death for spores in general, are no longer appropriate. A new approach is reported to the reduction of heating severity for a given survivor reduction of bacterial spores suspended in complex biological mixtures at their ordinary pH. Heating time advantages amount to severalfold and do not involve antimicrobial additives.     

The effects of green and blue-green algal diets on the reproductive rate of the rotifer Brachionus plicatilis

The reproductive rate of the rotifer Brachionus plicatilis cultured on a variety of diets was investigated. Unialgal and mixed diets of the green alga Chlorella and the blue-green alga Schizothriz were compared. Rotifer reproductive rate was found to be an average of 2.7 times higher on a mixed diet of Chlorella and Schizothrix than on either Chlorella or Schizothrix as a unialgal diet. Enhancement of rotifer reproductive rate was not observed on a mixed diet of Chlorella and Dunaliella compared with a unialgal diet of Chlorella. Ingestion of Schizothrix was shown not to be required for enhancement of rotifer reproduction. It was further shown that the enhancing factor is a heat labile substance.     

Use of GABA to enhance rotifer reproduction in enrichment culture

Gamma‐aminobutyric acid (GABA) has been shown to enhance the reproduction of the rotifer Brachionus plicatilis Muller in stressful culture conditions. During the enrichment of rotifers for feeding to marine fish larvae, they are usually stressed as a result of exposure to different marine oils and high population densities. This typically results in decreased rotifer survival, reproduction and swimming activity. In the present study, we used GABA to increase rotifer reproduction and the swimming activity of rotifers in enrichment cultures. GABA treatment 24 h before high density enrichment enhanced reproduction during enrichment culture, but not when carried out simultaneously with enrichment. Swimming activity was not significantly affected by GABA treatment 24 h before or simultaneously with nutrient enrichment.     

Improvement in In Vitro Fertilization Rate,Decrease in Reactive Oxygen Species and Spermatozoa Death Incidence in Rams by Dietary Fish Oil

Our aim was to evaluate the effects of fish oil feeding on sperm classical parameters, level of reactive oxygen spices (ROS), spermatozoa death incidence and in vitro fertilization (IVF) rate in rams. We randomly assigned nine rams, into two experimental groups (isoenergetic and isonitrogenous rations with constant level of vitamin E supplement): control (CTR; n = 5) and fish oil (FO; n = 4, 35 g/day/ram). Diets were fed for 70 days during the physiological breeding season. After a 21‐day dietary adaptation period, semen was collected weekly from each ram by an artificial vagina. Sperm classical parameters were determined by the computer‐assisted sperm analyzer system (CASA), and it was prepared for IVF process by swim‐up technique. These evaluations were performed during the first and last weeks of sampling. Intracellular ROS level and spermatozoa death incidence were detected by flow cytometry on a weekly basis after adaptation. Data were analysed with SPSS 15. The volume, concentration (3.6 and 2.7 × 10⁹/ml) and sperm progressive motility (60 and 48%) were significantly improved in the FO group compared with the CTR (p < 0.05). A comparison of two‐cell stage embryos following IVF in the two groups showed a significantly higher fertilization rate in the FO group (56%) compared with the CTR (49%). Superoxide anion (O₂^?) rate was significantly lower (p < 0.05) at the third week of sampling in the FO. Although the H₂O₂ rate was numerically lower in the FO group compared with the CTR, this difference was not significant. In addition, apoptosis showed a significant difference in the third week of sampling (15 and 30% for FO and CTR, respectively; p < 0.05). Overall, adding fish oil to the ram diet not only improved sperm quality and IVF results, it also could reduce oxygen‐free radicals and the incidence of spermatozoa death.     

Fatal levamisole toxicosis of captive kiwi (Apteryx mantelli)

CASE HISTORY: Nine of 24 captive kiwi treated with oral levamisole at a dose between 25–43 mg/kg showed signs of respiratory distress. Six died within 4 h of treatment and the remaining three made a full recovery within 24 h.

CLINICAL AND PATHOLOGICAL FINDINGS: Within 3–4 h of treatment, the affected birds had an elevated respiratory rate, mucoid nasal discharge and rapidly became comatose. Post mortem examination revealed accumulation of thick mucus in the oral cavity and trachea. There was severe pulmonary congestion and oedema and early bronchopneumonia in the lungs of five of the birds. In two birds, there was acute hepatic degeneration and necrosis and one bird had acute pancreatic degeneration and necrosis.

DIAGNOSIS: Acute levamisole toxicity.

CLINICAL RELEVANCE: Kiwi were acutely sensitive to levamisole toxicity at doses that are well within the safe range for domestic poultry. Levamisole should not be used as an anthelmintic in kiwi.