Comparison of ozone and UV-C treatments on the postharvest stilbenoid monomer, dimer, and trimer induction in var. 'Superior' white table grapes

Postharvest treatment of seedless white table grapes (var. 'Superior') with different gas ozone concentrations (3.88 and 1.67 g/h) for 1, 3, and 5 h induced an increase in stilbenoid biosynthesis [trans-resveratrol, piceatannol, and viniferinas (resveratrol dehydrodimers and dehydrotrimers)] during storage at 22 degrees C and 95% relative humidity. The maximal resveratrol concentration was reached after 2 days of storage, and this amount was similar to that induced by optimized UV-C treatments (1 min, 510 W, 40 cm). Although similar resveratrol concentrations accumulated in grapes after both UV-C and O3 treatments (maximum ozone production and time), the ozone treatment was more efficient in inducing viniferins accumulation in grape berries. A sequence in the biosynthesis of stilbenoids was observed, starting with the resveratrol monomer, continuing with the resveratrol dehydrodimers epsilon-viniferin and delta-viniferin, and ending with four different resveratrol dehydrotrimers. These trimers were different from alpha-viniferin, a trimer previously reported to be induced in grapes after biotic and abiotic stresses. Two alpha-viniferin isomers were also detected in the ozone-treated grapes, although at very low concentrations that prevented their quantification.     

Extracellular matrix expression by equine oral and limb fibroblasts in in vitro culture

Wounds on the limbs of horses are notoriously difficult to heal, with over production of TGFβ1 thought to be responsible for excessive scarring; in contrast, wounds in the oral cavity heal rapidly with minimal scarring. This experiment aimed to determine the effect of TGFβ1 on the production of mRNA and proteins for various extracellular matrix components by two equine fibroblast cell lines isolated from the oral mucosa and distal limb. Fibronectin mRNA was up-regulated by TGFβ1 in the limb but not the oral cells. TGFβ1 increased the ratio of mRNA for collagen types I-III for the oral cells only. mRNA expression for TGFβ receptors-I and -II was significantly lower in limb fibroblasts, and treatment of either cell line with TGFβ1 down-regulated mRNA expression for both receptors. These differences may account for the improved healing seen in oral wounds compared to the excessive scarring seen in limb wounds.     

Unique clones of the pitch canker fungus, <Emphasis Type="Italic">Fusarium circinatum,</Emphasis> associated with a new disease outbreak in South Africa

Pitch canker of pines is caused by the fungus Fusarium circinatum. In South Africa, this pathogen has mostly been a nursery problem. From 2005, however, outbreaks of pitch canker have been reported from established Pinus radiata and P. greggii in the Western and Eastern Cape Provinces. Most recently, pitch canker-like symptoms were observed on 10-year-old P. greggii trees in a plantation in the midlands of the KwaZulu-Natal (KZN) Province. The aim of this study was to: (i) identify the causal agent of the observed symptoms, (ii) determine the genetic diversity, and (iii) the mode of reproduction of this fungal population. Furthermore, the aggressiveness of isolates from these trees was compared with that of isolates obtained previously from P. patula in South Africa. Isolates from the P. greggii trees in KZN were confirmed as F. circinatum based on both morphology and DNA sequence analyses. Microsatellite marker analyses revealed the presence of five genotypes of F. circinatum, not previously reported from other plantations in South Africa, with one of these genotypes being dominant. These genotypes were all pathogenic to P. patula and P. elliottii. No evidence of sexual reproduction was detected in the KZN population of the fungus. This was consistent with the fact that isolates from P. greggii were all of the MAT-2 mating type, in contrast to previously collected isolates from across South Africa that included both mating types. The results suggest that the outbreak of pitch canker on P. greggii in KZN represents a separate introduction of F. circinatum into the region with important implications for managing the disease.     

Role of sex steroids in gonadal differentiation of the mussel Choromytilus chorus (Bivalvia Mytilidae) (Molina 1782)

In Chile, the species Choromytilus chorus stands out for its ecological and economic importance. This mussel has a very particular condition in the colour of the gonad, being cream‐yellow colour the male gonad and dark brown the female which is hardly desired by the consumers. In this context, the aim of this research is to determine the role that sex steroids have in gonadal differentiation of the mussel C. chorus. For this, juveniles with sizes 15–22 mm were selected, which were subjected to acute exposure in the form of bath for 60 days to four treatments: T1: dihydrotestosterone (DHT); T2: 17β‐estradiol (E2), T3: fadrozole (F) and T4: DHT‐F (DF), plus a control without chemicals. Each treatment as well as control included three replicates with 90 individuals each. The mussels undergoing treatment with E2 had a sex ratio (male:female) of 0.47 compared to 1:1 in the control group. In contrast, in the groups treated with DHT, F and DF the sex ratio changed to 2.0, 1.60 and 1.70 respectively. In the fertilization trials, all the mussels produced functional gametes, as they were able to generate gametes that were developed to morula, and veliger larva. Nevertheless, it should be noted that the size of oocytes from the group exposed to estradiol (61.12 ± 2.40 μm) was significantly higher than in other groups. These results support the hypothesis that sex steroids would be involved in sexual differentiation of marine bivalves.     

Competition for nitrogen by three sympatric species of Eucalyptus

? Nitrogen (N) exists in the soil in a variety of different forms and thus plants may avoid competition by taking up N as different chemical forms.

? This study examined the uptake of nitrate, ammonium and glycine by three co-occurring species of Eucalyptus (E. obliqua, E. radiata and E. rubida) from dry sclerophyll forest in south-eastern Australia. Species preference for N forms was determined by measuring uptake of glycine, nitrate and ammonium from ¹⁵N-labelled solutions containing equimolar 100 μmol L^? concentrations of all three N forms. KCl extracts were used to assess the relative abundance of the different forms of N in the soil’s exchangeable pool.

? KCl extracts of soil indicated that amino acids comprised 30–40% of the soluble non-protein N, while ammonium varied from 10–70% and nitrate from 5–70%. In all species, ammonium was the preferred source of nitrogen and was taken up 2.5–4.5 times faster than glycine, and 30–50 times faster than nitrate. Species did not differ in preference for N-forms (species*N-form interaction, not significant).

? This study indicates that nitrate, ammonium and amino acids are all present in soil, and thus there is the potential for niche differentiation based on chemical forms of N. However, there is no evidence that co-occurring Eucalyptus avoid competition for N by taking up different chemical forms.

     

Assessment of first-year veterinary students' clinical skills using objective structured clinical examinations

The DVM program at the University of Calgary offers a Clinical Skills course each year for the first three years. The course is designed to teach students the procedural skills required for entry-level general veterinary practice. Objective Structured Clinical Examinations (OSCEs) were used to assess students' performance on these procedural skills. A series of three OSCEs were developed for the first year. Content was determined by an exam blueprint, exam scoring sheets were created, rater training was provided, a mock OSCE was performed with faculty and staff, and the criterion-referencing Ebel method was used to set cut scores for each station using two content experts. Each station and the overall exam were graded as pass or fail. Thirty first-year DVM students were assessed. Content validity was ensured by the exam blueprint and expert review. Reliability (coefficient α) of the stations from the three OSCE exams ranged from 0.0 to 0.71. The three exam reliabilities (Generalizability Theory) were, for OSCE 1, G=0.56; OSCE 2, G=0.37; and OSCE 3, G=0.32. Preliminary analysis has suggested that the OSCEs demonstrate face and content validity, and certain stations demonstrated adequate reliability. Overall exam reliability was low, which reflects issues with first-time exam delivery. Because this year was the first that this course was taught and this exam format was used, work continues in the program on the teaching of the procedural skills and the development and revision of OSCE stations and scoring checklists.     

Intravenous Administration of Azumolene to Reverse Malignant Hyperthermia in Swine

Background: The efficacy of intravenous (IV) administration of azumolene (Az), an analogue 30‐fold more soluble than dantrolene, on pigs susceptible to malignant hyperthermia (MH) is incompletely understood. Objective: To evaluate efficacy of Az on MH crisis in pigs. Animals: Eight normal (MHN) and 7 susceptible to MH (MHS) pigs (Landrace × Large White × Pietran). Methods: Prospective, laboratory trial. Hypermetabolic crisis was observed in MHS pigs, but not in MHN pigs, after a combined administration of inhaled halothane (1.5%) and IV injection of succinylcholine (SCh; 2.5 mg/kg). Susceptibility was confirmed using a caffeine and halothane contracture test. Az was administered 15 minutes after administration of SCh. Results: Respiratory acidosis (pH 7.16 ± 0.02; Pco ₂, 46.2 ± 9.1 mmHg, HCO₃, 22.5 ± 2.3 mmol/L), fever (38.2 ± 1.1°C), cardiac arrhythmias, and muscle contracture were observed in MHS pigs. MHS pigs (n = 5) treated with Az (2 mg/kg IV) survived the crisis with attenuation of signs (pH 7.30 ± 0.10; Pco ₂, 36.3 ± 4.5 mmHg; HCO₃, 22.9 ± 2.3 mmol/L) and recovery of normal muscle tone and cardiac rhythm. Conclusions and Clinical Importance: Az represents a possible substitute for dantrolene to reverse MH crisis in susceptible pigs.     

Avian Community Response to Grazing Intensity on Monoculture and Mixed Florida Pastures

Monoculture and mixed pastures in Florida provide habitat for a variety of resident and migratory bird species. The objectives of this study were to investigate the effects of grazing on vegetation structure and bird species richness and abundance in grazed monoculture and mixed pastures. Study pasture units were subject to four cattle grazing intensities: 0 = nongrazed (control), 15 = low, 20 = medium, or 35 = high animal units (AU) per pasture unit (no cattle, 1.3, 1.0, and 0.6 ha · AU^?1, on monoculture pastures and no cattle, 2.1, 1.6, and 0.9 ha · AU^?1, on mixed pastures). Monoculture pastures displayed a greater decrease in spatial heterogeneity of the vegetative community in the presence of grazing than mixed pastures. An increase in grazing intensity led to declines in total avian species richness and abundance and species richness within short-distance migrant, neotropical migrant, and permanent resident guilds on monoculture pastures. Declines in total species richness and abundance and neotropical migrant guild species richness and abundance were observed on mixed pastures subject to increasing grazing intensity. However, species richness within short-distance migrant and urban guilds and abundance within the grassland guild increased on this pasture type in the presence of grazing. Loss of spatial heterogeneity typically results in a lack of suitable habitat for birds that occupy the extremes of the vegetation structure gradient. This can lead to a loss of species richness and abundance. For the majority of avian guilds, a low grazing intensity of 1.3 ha · AU^?1 and 2.1 ha · AU^?1 on monoculture and mixed pasture, respectively, is recommended to maintain abundance. However, these grazing intensities may result in declines in species richness. Ultimately, if a range of avian species are to be supported on monoculture and mixed pastures, spatial heterogeneity of plant structure and composition must be maintained.