Comparison of three enzyme-linked immunosorbant assays with the indirect immunofluorescent antibody test for the diagnosis of canine infection with Ehrlichia canis

The aim of this study was to compare three different enzyme-linked immunosorbant assays (recombinant major antigenic protein 2 (rMAP2)-ELISA, the Immunocomb (Biogal, Israel) and the Snap 3Dx assay (IDEXX Laboratories Inc., USA)) with the indirect immunofluorescent antibody test in detecting anti-Ehrlichia canis immunoglobulin-G (IgG) antibodies. Samples tested were collected from dogs suspected to be naturally infected with E. canis and from experimentally infected dogs.When qualitative results (positive/negative) were compared, there was an overall agreement of 81% (54/67) between the indirect immunofluorescence antibody (IFA) test and the rMAP2-ELISA. An overall agreement of 94% (63/67) was found between the IFA test and the Immunocomb, and an overall agreement of 91% (61/67) was found between the IFA test and the Snap 3Dx assay. In 50 of 67 (74.6%) samples tested, complete agreement in the qualitative results was found in all four tests. Sixteen of 17 samples with disagreement in the qualitative results were found to have IFA titers of 1:320 or less. The sensitivities and specificities of the tests were found to be 0.71 and 0.85 for the rMAP2-ELISA, 0.86 and 0.98 for the Immunocomb, and 0.71 and 1.00 for the Snap 3Dx assay.The tests performed in this study were found to be highly specific in detecting E. canis antibodies. Their sensitivity was found to be low with sera having IFA titers of < or =1:320, while high with sera having titers greater than 1:320. Repeating the serological tests 1-2 weeks after the first antibody assay may overcome the sensitivity problem with titers of < or =1:320.     

Polyglandular endocrinopathy type II (Schmidt's syndrome) in a Dobermann pinscher

A three‐year‐old, female neutered, Dobermann pinscher was presented for investigation of lethargy, episodic collapse, ataxia and myxoedema. Primary hypothyroidism and primary cortisol‐deficient hypoadrenocorticism were diagnosed based on history, physical examination and compatible hormonal analysis. Increased serum concentrations of thyroglobulin autoantibodies and 21‐hydroxylase autoantibodies indicated an immune‐mediated aetiology. The case was complicated by lymphadenopathy with hand‐mirror lymphocytes, classically identified in lymphoma. A polymerase chain reaction test for antigen receptor rearrangement indicated polyclonality and therefore reactive lymphadenopathy. The dog's clinical signs resolved following introduction of levothyroxine and prednisolone. Prioritising the problem‐based approach in this case facilitated the diagnosis of hypoadrenocorticism in addition to hypothyroidism due to the persistence of clinical signs despite thyroxine replacement. Importantly, atypical adrenal gland dysfunction was not misinterpreted as inadequate therapeutic response to thyroxine supplementation. The observation that polyglandular endocrinopathy type II can occur in dogs suggests that in dogs with a suboptimal response to treatment for hypothyroidism or hypoadrenocorticism comorbid endocrinopathies should be investigated.     

Synthesis and characterization of canola oil-stearic acid-based trans-free structured lipids for possible margarine application

Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta' crystal forms for tub margarine, although these may be suitable for light margarine formulation.     

A male-fertile Lycopersicon esculentum × Solanum lycopersicoides hybrid enables direct backcrossing to tomato at the diploid level

Solanum lycopersicoides Dun. is a wild nightshade native to Chile and Peru that possesses many traits of potential interest to tomato breeders, including environmental stress tolerance, resistances to disease and insect pests, and certain fruit quality characteristics. Sexual and somatic hybrids with the cultivated tomato (Lycopersicon esculentum Mill.) are readily obtained, yet have a strong tendency towards male-sterility combined with unilateral incompatibility, barriers that have deterred breeding efforts in the past. We report herein the synthesis of a partially male-fertile F₁ hybrid by sexual crosses between tomato and a recently collected population of S. lycopersicoides. Over 280 BC₁ plants were obtained by directed backcrossing to tomato at the diploid level, of which 58 were sufficiently fertile to permit selfing or additional backcrosses. The transmission of S. lycopersicoides genetic markers into a uniform L. esculentum background was confirmed with 24 isozyme or morphological loci on 11 of the 12 alien chromosomes. Potentially useful tolerance to gray mold (Botrytis cinerea) was demonstrated by inoculation of stem cuttings with mycelial plugs: at 6 days post-inoculation, the intergeneric hybrid showed little evidence of disease progression and the length of stem lesions averaged only one third that of susceptible controls. This revised version was published online in July 2006 with corrections to the Cover Date.     

Combined application of nitrogen and phosphorus to enhance nitrogen use efficiency and close the wheat yield gap on varying soils in semi‐arid conditions

A primary driver of the wheat yield gap in Australia and globally is the supply of nitrogen (N) and options to increase N use efficiency (NUE) are fundamental to closure of the yield gap. Co‐application of N with phosphorus (P) is suggested as an avenue to increase fertiliser NUE, and inputs of N and P fertiliser are key variable costs in low rainfall cereal crops. Within field variability in the response to nutrients due to soil and season offers a further opportunity to refine inputs for increased efficiency. The response of wheat to N fertiliser input (0, 10, 20, 40 and 80 kg N ha^‐1) under four levels of P fertiliser (0, 5, 10 and 20 kg P ha^?1) was measured on three key low rainfall cropping soils (dune, mid‐slope and swale) across a dune‐swale system in a low rainfall semi‐arid environment in South Australia, for three successive cropping seasons. Wheat on sandy soils produced significant and linear yield and protein responses across all three seasons, while wheat on a clay loam only produced a yield response in a high rainfall season. Responses to P fertiliser were measured on the sandy soils but more variable in nature and a consistent effect of increased P nutrition leading to increased NUE was not measured.     

Sampling and monitoring of biogenic emissions by eucalyptus leaves using membrane extraction with sorbent interface (MESI)

Membrane extraction with sorbent interface (MESI) has been applied to monitor plant fragrance volatiles emitted into indoor air. The main components of the MESI system are a membrane module and a trap, which can be connected directly to a GC or GC-MS for simultaneous multicomponent extraction and monitoring. A polydimethylsiloxane (PDMS) membrane and two different traps, PDMS and Tenax, as well as a DC current supply for trap desorption have been applied in this research. After the membrane module is placed in contact with the plant, the MESI/GC-MS provides semicontinuous characterization of volatile compounds emitted. The MESI device has been applied to monitor the biogenic volatile organic compounds released during the first 8 h after a branch was cut from a Eucalyptus dunnii tree. The study demonstrates that the MESI system is a simple and useful tool for monitoring changes in emission processes as a function of time.     

Hydraulic conductivity in roots of ponderosa pine infected with black-stain (Leptographium wageneri) or annosus (Heterobasidion annosum) root disease

Roots from healthy and diseased mature ponderosa pine, Pinus ponderosa Laws., trees were excavated from a site near Burns, Oregon. The diseased trees were infected with black-stain root disease, Leptographium wageneri Kendrick, or annosus root disease, Heterobasidion annosum (Fr.) Bref., or both. Axial hydraulic conductivity of the roots was measured under a positive head pressure of 5 kPa, and the conducting area was stained with safranin dye to determine specific conductivity (k(s)). In diseased roots, only 8-12% of the cross-sectional xylem area conducted water. Resin-soaked xylem completely restricted water transport and accounted for 13-16% of the loss in conducting area. In roots with black-stain root disease, 17% of the loss in conducting area was associated with unstained xylem, possibly resulting from occlusions or embolisms. Based on the entire cross-sectional area of infected roots, the k(s) of roots infected with black-stain root disease was 4.6% of that for healthy roots, whereas the k(s) of roots infected with annosus root disease was 2.6% of that for healthy roots. Although these low values were partly the result of the presence of a large number of diseased roots (72%) with no conducting xylem, the k(s) of functional xylem of diseased roots was only 33% of that for healthy roots. The low k(s) values of functional xylem in diseased roots may be caused by fungus induced occlusions preceding cavitation and embolism of tracheids. The k(s) of disease-free roots from diseased trees was only 70% of that for healthy roots from healthy trees. The disease-free roots had the same mean tracheid diameter and tissue density as the healthy roots, suggesting that the lower k(s) in disease-free roots of diseased trees may also have been caused by partial xylary occlusions.     

Conserving genomic variability in large mammals: Effect of population fluctuations and variance in male reproductive success on variability in Yellowstone bison

Loss of genetic variation through genetic drift can reduce population viability. However, relatively little is known about loss of variation caused by the combination of fluctuating population size and variance in reproductive success in age structured populations. We built an individual-based computer simulation model to examine how actual culling and hunting strategies influence the effective population size (N_e) and allelic diversity in Yellowstone bison over 200 years (～28 generations). The N_e for simulated populations ranged from 746 in stable populations of size 2000 up to 1165 in fluctuating populations whose census size fluctuates between 3000 and 3500 individuals. Simulations suggested that ～93% of allelic diversity, for loci with five alleles will be maintained over 200 years if the population census size remains well above ～2000 bison (and if variance in male reproductive success is high). However for loci with 20 alleles, only 83% of allelic diversity will be maintained over 200 years. Removal of only juveniles (calves and yearlings) resulted in longer generation intervals which led to higher maintenance of allelic diversity (96%) after 200 years compared to the culling of adults (94%) when the mean census size was 3250 (for loci with five alleles). These simulations suggest that fluctuations in population census size do not necessarily accelerate the loss of genetic variation, at least for the relatively large census size and growing populations such as in Yellowstone bison. They also suggest that the conservation of high allelic diversity (>95%) at loci with many alleles (e.g., ?5) will require maintenance of a populations size greater than approximately 3250 and removal of mainly or only juveniles.