Requirement of Host Signaling Mechanisms for the Action of Ptr ToxA in Wheat

Ptr ToxA, the host-selective toxin produced by Pyrenophora tritici-repentis, is genetically associated with the development of tan spot disease of wheat. The toxin was shown previously to cause a programmed cell death in the host that requires de novo mRNA and protein synthesis. In the present study, inhibitors of plant signaling mechanisms protected wheat leaves from toxin action, as determined by electrolyte leakage bioassays, when applied to leaves with toxin. Okadaic acid, calyculin A and phenylarsine oxide, all inhibitors of protein phosphatase activity, reduced toxin-induced electrolyte leakage by more than 90%. Inorganic calcium channel blockers (LaCl₃ and CoCl₂ reduced toxin-induced electrolyte leakage by 78–95%, depending on inhibitor and time of measurement. By comparison, about 50% protection was achieved by the application of the protein kinase inhibitors staurosporine and K-252A. Nonetheless, the reduction in toxin-induced electrolyte leakage by protein kinase inhibitors was reproduced in multiple trials and was statistically significant. The data indicate that host signaling mechanisms, including calcium fluxes and a protein phosphorylation cascade, are required for the Ptr ToxA-induced cell death in wheat. Our current model holds that the signaling events occur between toxin perception by the cell and the toxin-directed gene expression in the host associated with cell death. As an alternative, the toxin-induced mRNA synthesis required for cell death may be for protein phosphatase and/or protein kinase genes. Additional work is required to resolve these possibilities.     

Resolution of hyphaema following intracameral injection of tenecteplase in a Stock Horse

Intracameral injection of tissue plasminogen activator has been suggested as a means of hastening the clearance of blood from the anterior chamber and reducing the risk of synechia and fibrotic membrane formation in horses with hyphaema. The following report describes a case of ocular trauma in which intracameral injection of tenecteplase (TNK), a new‐generation plasminogen activator, resulted in rapid resolution of hyphaema and successful outcome. However, a large dose (1 mg) was administered and may have been associated with retinopathy and keratopathy. TNK may be an effective treatment for equine hyphaema and further controlled clinical or experimental studies are required to determine its efficacy and safety profiles.     

Effects of temporal and spatial hunting control in waterbird reserves

Experiments were conducted in two Danish coastal wetland areas to assess the applicability of regulating wildfowling in marsh areas by restricting shooting to a period of the day as an alternative to apply spatial regulation. Teal (Anas crecca) showed a 2-97-fold increase when shore-based shooting was totally banned, compared with years when shore-based shooting was unregulated or diurnally regulated. The same result was found for common snipe (Gallinago gallinago) at its one studied area (15-39-fold increase). Shelduck (Tadorna tadorna), teal and mallard (A. platyrhynchos) spent more time in the zones nearest to the shoreline when shore-based shooting was totally banned than when evening shooting was permitted. It is concluded (1) that disturbance levels were not sufficiently reduced by temporal regulation to prevent teal and snipe from abandoning otherwise attractive staging areas, and (2) that reserves should incorporate adjacent marshes in the non-shooting refuge to ensure high species diversity.     

AFLP analysis of Solanum phureja DNA introgressed into potato dihaploids

Introgression of Solanum phureja DNA into S. tuberosum dihaploids was analysed by the use of amplified fragment length polymorphism (AFLP) markers. Five dihaploids, derived from crosses between S. tuberosum cv. Pentland Crown and two different S. phureja pollinators (IVP48 and EC90) were investigated by use of 17 AFLP primer pairs. Also 30 dihaploids, derived from pollination of five different S. tuberosum seed parents with S. phureja IVP101, were investigated for the presence of S. phureja‐specific markers. In total approximately 680 and 850 AFLP products were detected in the diploid S. phureja clones and in the tetraploid S. tuberosum genotypes, respectively. A total of 68 S. phureja IVP48‐specific markers were detected, while the total number of S. phureja IVP101‐specific markers was in the range of 72‐96, depending on the S. tuberosum seed parent. Introgression of DNA in the S. tuberosum cv. Pentland Crown dihaploids, after pollination with S. phureja IVP48 and S. phureja EC90, was demonstrated by the detection of 14 of 68 IPV48‐specific markers in the dihaploids. However, no DNA introgression was found in any of the 30 S. tuberosum dihaploids derived from S. phureja IVP101. Hence, S. phureja IVP101 is regarded as an excellent pollinator in the production of S. tuberosum dihaploids in potato breeding programmes because of the high yield of dihaploids per 100 berries, and because no introgression of DNA into the S. tuberosum dihaploids was evidenced.     

Growth and feed utilisation of rainbow trout subjected to changes in feed lipid concentrations

Rainbow trout Oncorhynchus mykiss grew from 44 to 326 g in 96days when held at 12 °C. Fish were fed to satiation twice dailywith either high (L₁: 30.8%, L₂:31.4%) or lower-lipid feeds (C₁: 18.8%,C₂: 21.8%). Four feeding treatments were studied.Group C₁C₂ received feed C₁ for 43 days(days 0–43) and C₂ thereafter (days 44–96).Groups L₁L₂, L₁C₂ andC₁L₂ were subjected to dietary changes asindicated by the feed designations. After a short period of feedadaptation, fish ingested similar amounts of feed energy i.e., they ateless by weight of the lipid-rich (L) feeds. Feed lipid content did notaffect growth but fish fed L-feed had reduced feed conversion ratio(FCR) compared to fish fed C-feed (0.731 vs. 0.773) during days0–43 (P < 0.01). After 96 days,L₁L₂-fish were lower in body protein(15.8%) than the C₁C₂-fish (16.8%)(P < 0.01). L-feeds also tended to increase percentage lipidand reduce percentage whole body moisture and ash. A higher net proteinutilisation (NPU) was recorded in fish fed L-feeds (43.6%)compared to fish fed C-feeds (38.8%) in days 0–43(P < 0.05). This seemed to be the result of a lower proteinintake rather than a protein-sparing effect of feed lipid. Above athreshold value of approximately 6.5 mg protein eaten·g bodywt_{minus 1}·day_–1, NPU decreased.     

Movements of two strains of radio tagged Altlantic salmon, Salmo salar L., smolts through a reservoir

Smolt migration through a shallow and turbid hydro-reservoir in a major Danish river system was investigated using radiotelemetry. Hatchery-reared 1+-year-old Atlantic salmon, Salmo salar L., smolts of equal size from two different non-native strains were radio-tagged and followed during their downstream migration through the 12-km-long reservoir. A total of 50 salmon smolts, 25 of Swedish (Øtran River) and 25 of Irish (Burrishoole River) origin, were surgically implanted with miniature radiotransmitters. The tagged smolts were tracked daily over a 3-week period in May 1996. The Øtran smolts initiated migration first ( P  < 0.001), moved faster ( P  < 0.01), were delayed less when passing a culvert ( P  < 0.001) and were more successful in moving through the reservoir than the Burrishoole smolts. The observed differences in migratory behaviour are interpreted as evidence of a genetic component influencing smolt migration.     

Fatty Acid Composition of U.S. West Coast Albacore Tuna (Thunnus alalunga) and the Effects of Canning and Short-Term Storage

ABSTRACT

Changes in the fatty acid composition of 13 bled and blast-frozen U.S. West Coast albacore tuna (Thunnus alalunga) were determined following custom-canning and 5 weeks of canned storage. In accordance with typical custom-canning procedures, no additional packing materials were used, and the product did not undergo a precooking step. Raw albacore tuna was found to be rich in n-3 polyunsaturated fatty acids (PUFAs), with an average of 9.1% (% wt of total fatty acids) EPA and 33.8% DHA. Canning and short-term storage did not cause major fluctuations in the fatty acid profiles of the albacore tuna, with no significant changes in the total fractions of saturated fatty acids (30–31%), monounsaturated fatty acids (19%), PUFAs (50%), or n-3 PUFAs (46–47%). On a tissue weight basis, U.S. West Coast albacore tuna was found to contain high levels of total n-3 PUFAs, with 3.3 g/100 g tissue in raw tuna and 4.0–4.1 g/100 g tissue in products that were canned and stored for 5 weeks.     

Resistance to synthetic pyrethroids in South Australian populations of sheep lice (Bovicola ovis)

SUMMARY Lice were collected from 71 flocks detected as Infested at market Inspection in 1990 and 1991, from 16 flocks where resistance was suspected and from 31 flocks from Kangaroo Island. Susceptibility to cypermethrin was measured by a treated surface technique and survival of lice at 5 ppm or greater was taken as an indication of resistance. The prevalence of resistance was 34% in louse populations from the market inspection sample, 50% in flocks in which resistance was suspected and 68% in flocks from Kangaroo Island. Most resistance factors were in the range 1 to 20 although one louse population with a resistance factor of 91 was found on Kangaroo Island.