The Emperor Seamounts: southward motion of the Hawaiian hotspot plume in Earth's mantle

The Hawaiian-Emperor hotspot track has a prominent bend, which has served as the basis for the theory that the Hawaiian hotspot, fixed in the deep mantle, traced a change in plate motion. However, paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating that the Emperor Seamount trend was principally formed by the rapid motion (over 40 millimeters per year) of the Hawaiian hotspot plume during Late Cretaceous to early-Tertiary times (81 to 47 million years ago). Evidence for motion of the Hawaiian plume affects models of mantle convection and plate tectonics, changing our understanding of terrestrial dynamics.     

Design, validation, and absolute sensitivity of a novel test for the molecular detection of avian pneumovirus.

This study describes attempts to increase and measure sensitivity of molecular tests to detect avian pneumovirus (APV). Polymerase chain reaction (PCR) diagnostic tests were designed for the detection of nucleic acid from an A-type APV genome. The objective was selection of PCR oligonucleotide combinations, which would provide the greatest test sensitivity and thereby enable optimal detection when used for later testing of field materials. Relative and absolute test sensitivities could be determined because of laboratory access to known quantities of purified full-length DNA copies of APV genome derived from the same A-type virus. Four new nested PCR tests were designed in the fusion (F) protein (2 tests), small hydrophobic (SH) protein (1 test), and nucleocapsid (N) protein (1 test) genes and compared with an established test in the attachment (G) protein gene. Known amounts of full-length APV genome were serially diluted 10-fold, and these dilutions were used as templates for the different tests. Sensitivities were found to differ between the tests, the most sensitive being the established G test, which proved able to detect 6,000 copies of the G gene. The G test contained predominantly pyrimidine residues at its 3' termini, and because of this, oligonucleotides for the most sensitive F test were modified to incorporate the same residue types at their 3' termini. This was found to increase sensitivity, so that after full 3' pyrimidine substitutions, the F test became able to detect 600 copies of the F gene.     

Training veterinary personnel for effective identification and diagnosis of exotic animal diseases

The requirements for exotic animal disease (EAD) training were considered at a workshop organized for those with responsibilities for EAD response management in the different states of Australia, with the objective of identifying the optimum strategy for training veterinarians to identify and act upon EADs. It was concluded that there should be specialized within-country training in EAD recognition for an elite group of diagnostic veterinarians who are required to recognize the major exotic diseases of animals, instigate the correct procedures to confirm the diagnosis of the disease, and undertake appropriate measures for effective initial management of the disease. The use of live, deliberately infected animals for demonstration purposes is not currently supported by any research indicating an improved learning outcome compared with that from alternatives, such as videos, necropsy specimens, and dedicated computer-aided learning packages. Therefore, ethical requirements to minimize the use of animals in teaching and research may prevent live-animal use. It is concluded that training should take place within each country via a course of instruction that includes an initial intensive course followed by continued professional development, with examination of knowledge at the end of each.     

Age and growth in southern bluefin tuna, Thunnus maccoyii (Castelnau): Direct estimation from otoliths, scales and vertebrae

In the early 1990s, the spawning biomass of the southern bluefin tuna (SBT) population was estimated to be less than 10% of its historical level. However, major uncertainties surrounding the age composition of the catch confounded the virtual population analysis assessment models. To eliminate these uncertainties, validated estimates of the age composition of the catch were required.We examined scales, caudal vertebrae and sagittal otoliths to determine which structure produced the most accurate age estimates in SBT. Scales proved useful for estimating ages of SBT only up to 4 years. Marginal increment analysis verified that the zones of dense circuli visible on the scales were deposited annually up to this age. In larger fish, the compression of circuli on the margin of scales and high incidence of regenerated scales made estimation of age very difficult. Obvious increments were present on both the vertebrae and otoliths. Age estimates from the two structures matched closely for the first 10 years of life. However, in larger (older) fish the counts diverged, otoliths consistently providing higher age estimates. We determined that annual increments are formed on sagittal otoliths throughout life but that this is not the case in vertebrae, where bands are formed less frequently. Thus, vertebrae were unreliable for estimating age beyond 10 years, which corresponds approximately to the age-at-first maturity.Ages were estimated from otoliths of 1121 fish from throughout the species’ size range. These data indicate that SBT live to at least 40 years of age, twice the longevity previously accepted; that age at recruitment is 1 year, not 2; and that mean age-at-maturity is approximately 11 years, not 7.The age distribution of SBT catches by the Japanese longline fishery in the Tasman Sea indicate that a significant proportion of the SBT population in this area is over 25 years of age and that cohorts spawned in the late 1970s and early 1980s are markedly under-represented in the population. The latter is thought to result from intense exploitation on these cohorts by the Australian surface fishery soon after recruitment.     

Manual of Veterinary Dietetics

BSAVA Manual of Canine and Feline Endocrinology Eds Carmel Mooney and Mark Peterson Published by BSAVA, 2004. Paperback, 240 pages Price £75.00. ISBN 0-905214-72-2     

Identification of the antifungal compound,trans-cinnamic acid,produced by Photorhabdus luminescens,a potential biopesticide against pecan scab

Pecan scab (caused by Fusicladium effusum) limits the productivity of pecan in the southeastern USA. Alternatives to conventional fungicides should be biorational, of low environmental risk with a lower risk of fungicide resistance. Research showed that metabolites from the nematode symbiont Photorhabdus luminescens suppress pecan scab, but the bioactive molecules had not been identified. Extracts from P. luminescens were investigated using a bioactivity-directed fractionation approach to identify the constituent(s) responsible for the activity. High throughput antifungal bioautography assays against Colletotrichum gloeosporioides, C. fragariae, and C. acutatum were used to guide the fractionation. One of the metabolites was purified and identified as trans-cinnamic acid (TCA) using silica gel chromatography followed by semi-preparative high-performance liquid chromatography. In vitro tests confirmed toxicity of TCA to C. gloeosporioides, C. fragariae, and C. acutatum at 10 and 100 μg mL^?1 using fungal bioautography inhibition screening plates. The antimycotic activity of TCA was tested in vitro against F. effusum. Zone of inhibition tests, and tests with TCA incorporated into agar showed TCA toxicity to F. effusum at concentration 148–200+ μg mL^?1. Further tests incorporating TCA into liquid media demonstrated that TCA arrested all growth of F. effusum at a concentration even as low as 64 μg mL^?1. Naturally occurring antimicrobial products might offer an alternative to disease control in crops, helping in minimizing the risk of fungicide resistance, while also minimizing any negative impact on the environment. Additional research is warranted to determine the potential to use TCA as a suppressive agent for pecan scab and other diseases.     

Evaluating drought resistance in germplasm of meadow fescue

Summary The drought resistance of 25 accessions of meadow fescue (Festuca pratensis Huds.) from seven countries was investigated in four experiments: two in the glasshouse using pot-grown plants from which water was withheld for various periods, and two in controlled environments under osmotic stress.There were significant differences between populations (broad-sense heritabilities or repeatabilities) in all four experiments. In the glasshouse there was a large residual effect of yield potential on production during and after slight-to-moderate drought, and different susceptibilities appeared only after very severe drought. The most consistently high-yielding accessions were from the Bergamo alps in Italy. Recovery after drought was strongly correlated with tiller survival. Continued production under moderate drought was considered important in wetter climates, whereas survival and recovery under severe drought was often associated with low production or flowering in the seeding year, and more typical of summer-drought climates.Leaf growth rates of plants subjected to zero or moderate osmotic stress were correlated with yields of irrigated or moderately-stressed plants in the glasshouse, although there was no differential susceptibility to mild stress. Under severe osmotic stress there were very large differences in survival between populations, but there was no relationship with survival under glasshouse conditions.The inconsistency of population rankings across experiments shows that no one technique gives a full evaluation of drought resistance, and emphasizes the complex nature of the phenomenon. It was possible, however, to identify (a) regions meriting further collections, and (b) ecotypes that had desirable responses in all experiments and could contribute to variety improvement.     

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Book reviews and notices