Quantitation of adenine nucleotides in equine colonic mucosal tissue using high performance liquid chromatography.

The objectives were to use high performance liquid chromatography (HPLC) to validate an established method for adenine nucleotide separation in equine colonic mucosal tissue, to determine the inherent variability in the tissue and extraction method, and to determine the stability of ATP, ADP, and AMP in the tissue with time. Equine colonic mucosal tissue obtained from a single horse was immediately submersed in liquid nitrogen, and stored at -70 degrees C. Samples were lyophilized, extracted, and separated by HPLC. The limit of quantitation was 0.05 microg/mL. The coefficient of variation for the instrument was less than 10% for all nucleotides measured. When the tissue was not homogenized prior to sampling, there were significant differences in adenine nucleotide content between samples. However, when the tissue was homogenized prior to analysis, these differences were no longer significant. There was no significant decrease in ATP, ADP, or AMP content over a 54-day analysis period.     

Suppression of Verticillium Wilt in Eggplant by Some Fungal Root Endophytes

One hundred and twenty-three fungal isolates were obtained from 225 root segments of eggplants, melon, tomato, strawberry and Chinese cabbage, grown as bait plants in a mixed soil made up of samples from different fields in Shizuoka, Japan. Isolates belonging to Mycelium radicis atrovirens (MRA), including Phialocephala fortinii, were the most prevalent in all the five bait plants. Eleven of the 123 isolates, after being inoculated onto axenically reared eggplant seedlings, almost completely suppressed the pathogenic effects of a post-inoculated, virulent strain of Verticillium dahliae. Seven of these 11 isolates had come from the roots of eggplant and included Heteroconium chaetospira, P. fortinii, and unidentified species of Fusarium, Penicillium, Trichoderma and MRA. P. fortinii, H. chaetospira, a non-sporulating isolate with white mycelium (SWM) and MRA were easily reisolated from root segments. Hyphae of H. chaetospira, P. fortinii and SWM colonized the root tissues of eggplant without causing apparent pathogenic symptoms. The mechanisms by which these endophytes confer resistance to infection by V. dahliae are unknown but the effectiveness of these fungi in a laboratory setting indicates that they have potential as biocontrol agents and merit further investigation.     

Biological and sequence comparisons of Potato virus Y isolates associated with potato tuber necrotic ringspot disease

The biological and molecular relationships between a large number of Potato virus Y (PVY) isolates were examined, concentrating mainly on isolates associated with potato tuber necrotic ringspot disease (PTNRD). Following detailed analysis of the coat-protein gene, four main groups were identified which broadly corresponded to the phenotype of the different isolates. The groups comprised the ordinary strain (PVY^O), the necrotic strain (PVY^N), the C strain (PVY^C) and a group of recombinant (between ordinary and necrotic) isolates. In the latter group, all members were associated with PTNRD. However, four nonrecombinant isolates were also identified which were associated with PTNRD or tuber necrosis. Three were from tubers showing PTNRD symptoms in the field, while the fourth originated from symptomless tubers, but could cause necrotic rings on tubers under glasshouse conditions. The results show that although coat-protein recombination is always found associated with the PTNRD phenotype, some nonrecombinant isolates have very similar biological properties.     

A coat protein transgene from a Scottish isolate of potato mop-top virus mediates strong resistance against Scandinavian isolates which have similar coat protein genes

Resistance tests were made on seedlings of transformed lines of Nicotiana benthamiana which contain a transgene encoding the coat protein (CP) gene of a Scottish isolate of potato mop-top virus (PMTV). This transgene has been reported to confer strong resistance to the PMTV isolate from which the transgene sequence was derived and also to a second Scottish isolate. Plants of lines of the transgenic N. benthamiana were as resistant to two Swedish and two Danish PMTV isolates as to a Scottish isolate, and of five lines tested, greater than 93.5% of transgenic plants were immune. The coat protein gene sequences of these four Scandinavian isolates were very similar to those of the two Scottish isolates. The greatest divergence between the isolates was three amino acid changes and there was less than 2% change in CP gene nucleotide sequence. It is concluded that the PMTV CP transgene used in these experiments could confer resistance against isolates from different geographical areas because it is becoming apparent that the CP genes of PMTV isolates are highly conserved.     

Can epidemiology and economics make a meaningful contribution to national animal-disease control?

The general role of veterinary epidemiology and economics to national animal-disease control throughout the world is considered for the four main groupings of animal diseases: zoonotic, food-borne, endemic and epidemic diseases. This is done by considering how veterinary epidemiology and economics has contributed to priority setting (which diseases come first?), decision-making (for a given disease, which strategy is best?), and disease control implementation (how can optimal delivery and adoption of selected interventions best be achieved?). Within each of these categories, progress made and future opportunities are discussed. In addition, a review is made of how veterinary epidemiology and economics has been institutionalised. We conclude that veterinary epidemiology and economics holds a unique role in the development of national policies and strategies for improved animal health world-wide. However, we consider that we must capitalise more on the unique comparative advantage of the partnership between veterinarians and agricultural economists. We believe that much remains to be done to improve the "institutionalisation" of veterinary epidemiology and economics, and the adoption and impact of the products of our unique partnership, particularly in countries of the developing world.     

Quantitative analysis of production traits in saltwater crocodiles (Crocodylus porosus): II. age at slaughter

Crocodile morphometric (head, snout‐vent and total length) measurements were recorded at three stages during the production chain: hatching, inventory [average age (±SE) is 265.1 ± 0.4 days] and slaughter (average age is 1037.8 ± 0.4 days). Crocodile skins are used for the manufacture of exclusive leather products, with the most common‐sized skin sold having 35–45 cm in belly width. One of the breeding objectives for inclusion into a multitrait genetic improvement programme for saltwater crocodiles is the time taken for a juvenile to reach this size or age at slaughter. A multivariate restricted maximum likelihood analysis provided (co)variance components for estimating the first published genetic parameter estimates for these traits. Heritability (±SE) estimates for the traits hatchling snout‐vent length, inventory head length and age at slaughter were 0.60 (0.15), 0.59 (0.12) and 0.40 (0.10) respectively. There were strong negative genetic (?0.81 ± 0.08) and phenotypic (?0.82 ± 0.02) correlations between age at slaughter and inventory head length.     

Evaluation of PCR,IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4–6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given. © 2001 Society of Chemical Industry     

Production and evaluation of monoclonal antibodies for the detection of beet mild yellowing luteovirus and related strains

A sugar-beet-infecting isolate of beet mild yellowing luteovirus (BMYV), and aBrassica-infecting isolate of beet western yellows luteovirus (BWYV) were used to produce monoclonal antibodies for epidemiological studies with BMYV and related field strains. Thirty-four monoclonal antibodies were tested for their reaction with 9 luteoviruses in triple-antibody-sandwich enzyme-linked immunosorbent assay. One (MAFF 24) is now routinely used in the UK for detecting BMYV and BWYV in plants and aphids, although it does not discriminate between them. Heterologous reactions were detected between some of the monoclonal antibodies and potato leafroll virus (PLRV), bean leafroll virus (BLRV) and barley yellow dwarf virus (BYDV-RPV). 38% of antibodies raised to BWYV reacted with PLRV compared with 4% of those raised to BMYV. Monoclonal antibodies were produced which distinguished a sugar-beet-infecting isolate of BMYV with differing host range and serological properties from the commonly-occurring field strain.