Effect of defoliation on patterns of carbon exudation from Agrostis capillaris

Grassland ecosystems are important global sinks and sources of atmospheric carbon (C). In this study, we used an in‐situ ¹³CO₂ tracer approach to quantify differences in short‐term C exudation from defoliated and non‐defoliated Agrostis capillaris (L.) plants subjected to natural diurnal light and temperature regimes and rainfall events. Results showed: 1. There was no significant difference in overall carbon exudation from the plants as a result of defoliation; 2 . defoliation significantly increased exudation of recent photosynthate (i.e., ¹³C labeled); 3 . there was a distinct and statistically significant diurnal trend in C exudation with root C exudation increasing during the day and early evening and decreasing during the night and early morning. The importance of light/temperature and defoliation as drivers of patterns of root C exudation and the contribution of recent assimilate C to atmosphere‐plant‐soil carbon flow are discussed.     

Isoflavone aglycon and glucoconjugate content of high- and low-soy U.K. foods used in nutritional studies

The isoflavone aglycon and glucoconjugate content of commercially prepared and "home-prepared" high- and low-soy foods selected for use in an on-going nutritional study were measured by LC-MS. The daidzin, daidzein, 6"-O-malonyldaidzin, 6"-O-acetyldaidzin, genistein, genistin, 6"-O-malonylgenistin, 6"-O-acetylgenistin, glycitin, glycitein, 6"-O-malonylglycitin, and 6"-O-acetylglycitin content are expressed in terms of individual isoflavones, total isoflavone equivalents, and milligrams of isoflavones per portion served. Soybeans (774 mg x kg(-1) total isoflavones) and soybean-containing foods had the highest isoflavone content of the foods examined. The low-soy foods all contained very low concentrations (<8 mg x kg(-1) total isoflavones) of the isoflavone aglycons and glucoconjugates. High- and low-soy 11 day rotating menus were constructed from the analyzed foods to deliver 100.0 and 0.5 mg of isoflavones per day, respectively.     

The implications of snow-based recreation for small mammals in the subnivean space in south-east Australia

The increasing popularity of snow-based recreation activities and the development of ski resorts and associated infrastructure have the potential to affect adversely small mammal fauna that over-winter in the subnivean space. We investigated the effects of human activities on the maintenance of the subnivean space, which is critical to the over-winter survival of small terrestrial mammals in Kosciuszko National Park, south-eastern Australia.The creation of ski pistes, surface ski lifts and over-snow routes involves compression of the snowpack and resulted in small or absent subnivean spaces (average 1.2 cm) and high snow cover densities (generally over 0.5 g cm⁻³ and 0.35 g cm⁻³ respectively). By contrast, the subnivean spaces associated with unmodified snow cover averaged 8-20 cm depending on vegetation type. The density of unmodified snowpack was less than 0.35 g cm⁻³ in June but increased throughout the season to levels comparable to those of compressed snow. When the snowpack was experimentally compressed at 22 sites, destroying the subnivean space, detections of two small mammal species (Rattus fuscipes and Antechinus swainsonii) significantly (p < 0.0001) declined by 75-80%. These species remain active below the snow throughout the winter and depend on the presence of an adequate subnivean space.The removal of vegetation by fire significantly (p < 0.0001) reduced the size of the subnivean space regardless of habitat type. Vegetation clearing occurs as part of ground preparation prior to establishing ski runs. Supergrooming, in which surface soil is also disturbed, is likely to have similar (if not more extreme) effects.Nival areas used for snow-based recreation should be managed to minimise negative effects on subnivean fauna, by maintaining natural features associated with subnivean space formation (dense shrubs, boulders and/or microtopography) and confining developments to areas where these features are not present.     

Effect of phosphorus concentration of the nutrient solution on the volatile constituents of leaves and bracts of Origanum dictamnus

The chemical composition of the essential oils obtained from the leaves and bracts of hydroponically cultivated Origanum dictamnus were analyzed by GC-MS techniques. Three different concentrations of phosphorus (5, 30, and 60 mg/L) in the nutrient solution were used for the cultivation, using the nutrient film technique (NFT). A total of 46 different compounds were identified and significant differences (qualitative and quantitative) were observed between the samples. Carvacrol and p-cymene were identified as the main compounds in all samples analyzed, whereas thymoquinone was found in higher percentage in the leaves than in bracts. The essential oils were tested for their antibacterial activity against Gram-positive and Gram-negative bacteria. The oils obtained from the bracts were found to be more active. The results obtained from GC-MS analyses were submitted to chemometric analysis.     

Antimicrobial properties of Quercus ilex L. proanthocyanidin dimers and simple phenolics: evaluation of their synergistic activity with conventional antimicrobials and prediction of their pharmacokinetic profile

The antibacterial and antifungal activities of an ample number of phenolic compounds isolated from Quercus ilex leaves, belonging to the classes of flavonoids, proanthocyanidins, and phenolic acids, are discussed. The isolation of A type proanthocyanidin, (+)-epigallocatechin-(2β→O→7, 4β→8)-(+)-catechin is reported for the first time. Its structure was established by means of highfield NMR (correlation spectroscopy, heteronuclear single quantum correlation, heteronuclear multiple bond correlation, and rotating frame Overhauser effect spectroscopy) and MS spectral analyses, while its absolute configuration was determined by circular dichroism measurements. The isolated compounds were tested for their antimicrobial effects against eight human bacterial species and 14 fungal species. In a second step, the most potent compounds were tested in combination with the conventional fungicides, bifonazole and ketoconazole, to evaluate possible synergistic effects. Results showed that proanthocyanidins 3 and 4 when combined with bifonazole and ketoconazole increase the activity of both of these conventional fungicides. Moreover, the pharmacokinetic profile of the isolated compounds was investigated using computational methods.     

The pharmacokinetics and pharmacodynamics of the injectable anaesthetic alfaxalone in the horse

ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin.Study designProspective experimental study.AnimalsTen (five male and five female), adult, healthy, Standardbred horses.MethodsHorses were premedicated with acepromazine (0.03 mg kg^?1 IV). Twenty minutes later they received xylazine (1 mg kg^?1 IV), then after 5 minutes, guaiphenesin (35 mg kg^?1 IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg^?1). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1–5 (1 very poor, 5 excellent).ResultsThe median (range) induction and recovery scores were 4 (3–5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1–5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t_1/2), plasma clearance (Clp) and volume of distribution (V_d) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute^?1 kg^?1 and 1.6 ± 0.4 L kg^?1, respectively.Conclusions and clinical relevanceAlfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse.     

Conjunctival bacterial and fungal flora in healthy horses in the UK

Objectives To describe the bacterial and fungal flora of the normal conjunctiva of horses in the UK; to determine the effect of horse age, sex, geographic location, and housing on this flora; and to determine the most appropriate antimicrobial drug(s) for prophylactic treatment of corneal ulcers. Animal studied A total of 60 adult healthy horses were studied. Procedure Swabs of the conjunctiva were obtained from 60 horses housed in two locations within the UK. Specimens were cultured for aerobic bacteria and fungi, and sensitivity against six ophthalmic antimicrobials assessed. The effect of age, sex, location and housing on the frequency of microbial isolation was evaluated. Results Fifty‐four bacterial isolates, representing thirteen genera of bacteria were cultured from 31 (52%) horses. The most frequently isolated bacterial species was Acinetobacter sp (17/32 horses). The majority of isolates (28/54: 52%) were gram‐positive. Three genera of fungi (Mucor, Absidia and Aspergillus spp) were isolated from eight (13%) horses. There was no significant effect of geographic location, sex, age or housing on frequency of microbial isolation. Horses from which gram‐negative bacteria were isolated were significantly older than horses from which gram‐positive bacteria were isolated. High efficacy (greater than 90% of isolates sensitive in vitro) was displayed by chloramphenicol, gentamicin and tetracycline. Conclusions The microbial species isolated are comparable with studies performed in other countries, although the frequency of Acinetobacter isolation was higher which may reflect a geographic difference. The topical antimicrobials gentamicin and chloramphenicol are appropriate first line antimicrobials for empirical treatment of corneal ulcers in the UK.