Computed tomography of proximal metatarsal and concurrent third tarsal bone fractures in a Thoroughbred racehorse

A 2‐year‐old Thoroughbred filly presented to the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California at Davis for whole body nuclear scintigraphic evaluation after an acute onset of nonweightbearing right hindlimb lameness post race. The use of computed tomography (CT) enabled visualisation of additional pathology that was not initially appreciable using combined imaging modalities of nuclear scintigraphy and digital radiography, which ultimately altered the selected course of treatment. Computed tomography in horses with fractures of the cuboidal bones of the hock can provide valuable additional information regarding fracture configuration and radiographically occult pathology, which may help to guide clinical decisions about treatment.     

Low reproductive success of leatherback turtles, Dermochelys coriacea, is due to high embryonic mortality

We examined the mechanism responsible for low reproductive success in leatherback turtles (Dermochelys coriacea) at Playa Grande, Costa Rica: low egg fertilization versus high rates of embryonic death. Leatherbacks at this beach had a high rate of fertility (=93.3%±2.5%, n=819). We incubated 10 eggs from every clutch encountered of 19 females during 3 months of the 1998-1999 nesting season. Fertility rate of some females decreased during the nesting season, but overall was high. Detection of fertility was difficult using standard methods because fertility rates cannot be determined accurately from nests excavated after hatching because of egg decomposition. Removal and incubation of eggs from nests provided a better estimate. Embryonic death, particularly in the beginning of incubation before embryos are visible to the unaided eye, was the cause of low hatching success in this population. Hatching success increased with increasing fertility and differed between females, with some mothers having 71-81% success and others 23-32%. Embryonic death and not low egg fertility drives poor recruitment at Playa Grande. Improved conservation of this species at Playa Grande will require a better understanding of the mechanism behind embryonic death.     

Invertase storage stability and sucrose hydrolysis in solids as affected by water activity and glass transition

Research continues to differentiate the impact of water activity (a(W)) and the glass transition temperature (T(g)) on chemical reactions. Invertase with and without sucrose was incorporated into low and high molecular weight poly(vinylpyrrolidone) model systems (PVP-LMW and PVP-K30, respectively). Invertase activity and sucrose hydrolysis were monitored during storage at a(W) = 0.32-0.75 and 30 degrees C. Pseudo-first-order rate constants for activity loss in PVP-K30 were not different, regardless of the system being glassy or rubbery. In PVP-LMW, invertase stability decreased with increasing a(W). An a(W) > 0.62 was required for sucrose hydrolysis to occur in PVP-LMW. PVP molecular weight appeared to affect invertase stability and reactivity. No dramatic change around T(g) was found in either invertase stability or sucrose hydrolysis, suggesting that T(g)-dictated mobility has a minimal effect on these reactions in amorphous solids.     

水分状况及硼素营养对油菜苗期根系生长及硼营养效率的影响

采用温室盆栽试验 ,研究了不同土壤水分条件下施硼对油菜苗期根系生长、硼吸收、利用及其移动性的影响。结果表明 ,随土壤含水量、施硼量的下降 ,油菜根长、根体积、根系生长速率、根 /冠比减小 ,根系及地上部干物质积累降低 ,植株地上部硼浓度及含硼量下降。而硼利用效率、硼运移指数则随土壤含水量、施硼量的下降而升高。不同油菜品种的根系形态参数 (包括根长、根体积、根干重、根冠比及根系生长速率 )、硼利用效率及运移指数存在明显差异 ,即在相同条件下 ,V1根系较发达 ,硼利用效率、运移指数均高于V4 。研究认为 ,根系发达程度、硼利用效率及硼移动性大小是不同基因型油菜耐缺硼差异的重要因素。     

Cloning and expression of desoxyhemigossypol-6-O-methyltransferase from cotton (Gossypium barbadense)

Terpenoids play an important role in defense against insects and pathogens in cotton. These terpenoids contain phenolic groups. Metabolites in which the phenolic group has been converted to a methoxy group are less toxic to most insects and pathogens and thus may alter resistance. Here is reported the cloning of a gene from Gossypium barbadense that encodes the enzyme that methylates the phenolic group of desoxyhemigossypol (dHG) exclusively at the 6-position, dHG-6-O-methyltransferase (dHG-6-OMT). Partial peptide sequences from digests of purified dHG-6-OMT were used to design primers for RT-PCR amplification of cDNA fragments from poly(A) mRNA. Fragments were extended to full length using 5' and 3' RACE. The resulting cDNA codes for a 365-residue polypeptide with a calculated molecular weight of 40.6 kDa, in agreement with the molecular mass of purified dHG-6-OMT. When expressed in Escherichia coli, the bacterial lysates showed a high specificity for the methylation of desoxyhemigossypol, differentiating the cloned gene from other pathogen-induced methyltransferases.     

Fine scale variability in soil extracellular enzyme activity is insensitive to rain events and temperature in a mesic system

While soil extracellular enzyme assays (EEAs) are frequently used to infer soil microbial function, the data typically reflect a small number of sampling points across a season, and it is unclear to what extent soil EEA may vary on the time scale of days to weeks. Rain events, in particular, may cause rapid shifts in EEA, and fine scale temporal data are needed to properly assess the generality of EEA data collected at coarser time scales. We examined soil EEA 2-3 times per week in the field from June to November in the context of natural rain events and temperature fluctuations, and explored how long-term water addition altered EEA responses. We also tested the short-term effects of water addition on the distribution of EEA in intact soil mesocoms and leachate. There was little temporal variation in EEA for the hydrolases phosphatase, N-acetyl-glucosaminidase and β-glucosidase, despite the occurrence of multiple large rain events and large soil temperature fluctuations. Phenol oxidase activity correlated significantly with seasonal trends in temperature and soil moisture, but was highly variable at short time scales, and the latter did not correlate significantly with short-term changes in soil microclimate. EEA generally increased in response to long-term water addition, and in soil mesocosms water addition did not significantly redistribute EEA among the upper and lower soil layers, and leachate EEA was three orders of magnitude lower than soil EEA. Overall, our results reveal relatively minor short-term variation in EEA for hydrolase enzymes, and no discernable response to temperature fluctuations or precipitation over the short term. However, high short-term variation in phenol oxidase activity suggests that it may be difficult to infer temporal trends in EEA for this enzyme from a limited number of sampling points.     

Physiological and Morphological Responses of Locally Grown Malaysian Rice Cultivars (Oryza Sativa L.) to Different Ozone Concentrations

Malaysian rice (Oryza sativa L.) cultivars MR84 and MR185 were grown in greenhouse chambers and exposed to four different levels of ozone from 28th August, 2001 to 22nd January, 2002. Four ozone levels were selected in close relation to the Malaysian peri-urban ambient level (approximately 30 ppb, 8 hr mean), the Malaysian guideline level (approximately 60 ppb) and possible future higher ozone levels (approximately 90 ppb). Both morphological and physiological parameters showed distinctive impacts of ozone treatments. The plants treated with the highest ozone concentration showed different morphological development, probably induced by severe foliar injury and physiological adaptation of the plants to the ozone stress. The physiological measurements revealed a high sensitivity at the early and late vegetative stages. It was concluded that MR84, which was found to be physiologically sensitive, responded to ozone relatively quickly and altered its morphology to compensate for effects on growth and yield, while MR185, found to be physiologically insensitive, responded to ozone stress slowly which resulted in more severe impacts on growth and yield parameters. Slight growth stimulation was observed at the lowest (30 ppb) ozone level for MR185, whilst negative impacts on growth occurred at both of the higher ozone levels. The study provided useful insights into the earlier findings of an open-top chamber filtration study on the same cultivars in the field at a peri-urban site in Malaysia. The present study proved that yield could be reduced substantially when other parameters associated with grain yield were affected, which was accompanied by increasing yellowing of leaves and premature senescence.     

Concentration of methylprednisolone in the centrodistal joint after administration of methylprednisolone acetate in the tarsometatarsal joint

REASONS FOR PERFORMING STUDY: The centrodistal (CD) and tarsometatarsal (TMT) joints are often injected individually with a corticosteroid to resolve lameness caused by osteoarthritis (OA). There are no data available regarding diffusion of methylprednisolone (MP) from the TMT joint to the CD joint. HYPOTHESIS: A therapeutic concentration of MP diffuses into the CD joint after methylprednisolone acetate (MPA) is administered into the TMT joint. OBJECTIVE: To measure the concentration of MP in the CD joint after MPA was administered into the TMT joint. METHODS: MPA was administered into a TMT joint of 16 horses. At different times, the ipsilateral CD joint of these horses was injected with a small amount of saline and recovered saline was measured for concentration of MP using high performance liquid chromatography. RESULTS: Six hours after administration of MPA into the TMT joint, a therapeutic concentration of MP was found in all 10 CD joints sampled at this time. CONCLUSIONS: Horses with pain arising from the distal 2 joints of the hock can be treated by administering MPA into the TMT joint alone. POTENTIAL RELEVANCE: Administering MPA into the TMT joint only, to treat OA of the distal 2 hock joints, reduces the difficulties and risks associated with centesis of the CD joint.