Chemical and organoleptic changes in poultry meat resulting from the growth of psychrophylic spoilage bacteria at 1 degree C.56. Volatile aroma constituents

Changes in the volatile constituents of raw chicken muscle resulting from aseptic autolysis and from the growth of micro‐organisms in pure culture at 1° C have been studied. Of 37 gas chromatographic peaks measured, 30 were tentatively identified and 14 confirmed by mass spectra. Ethanol was by far the largest individual component, accounting for 70–90 per cent of the total chromatogram area. Pigmented Pseudomonas and Pseudomonas putrefaciens both produced small and inconsistent changes, which were usually less than those resulting from autolysis. Small amounts of dimethyl sulphide resulted from the growth of Pseudomonas putrefaciens.     

Effect of seed treatment in preventing transmission of dwarf bunt of winter wheat to new areas

The effectiveness of various fungicide formulations containing carboxin and thiabendazole in eradicating teliospores of Tilletia controversa (dwarf bunt) from winter wheat seed was evaluated in the laboratory and the field. In the laboratory tests, the viability of teliospores washed from treated infested seed was greatly reduced as compared to the viability of teliospores washed from untreated infested seed, suggesting that carboxin and thiabendazole were primarily fungicidal. Field tests in two different years were established to determine if teliospores from treated infested seed could infect nearby untreated noninfested seed. Formulations containing carboxin were highly effective in reducing infection of healthy seed. No dwarf bunt infected plants developed in either year from seed treated with ‘Vitaflo 250’. Furthermore, seedborne common bunt caused by Tilletia foetida was nearly eradicated by carboxin-containing formulations in one field test. Carboxin treatment of winter wheat seed infested with dwarf bunt teliospores will greatly reduce the danger of introducing this pathogen into new areas.     

A root-injection method to assess verticillium wilt resistance of peppermint ( Mentha × piperita L.) and its use in identifying resistant somaclones of cv. Black Mitcham

Three studies were initially conducted using five mint cultivars with known disease reactions to verticillium wilt to determine if inoculation method, root-dip as compared to root-injection, had an affect on the plant growth and disease reaction. The planting media did not affect the development of wilt symptoms in susceptible varieties, however, the soil/peat based medium resulted in higher shoot fresh weight at harvest than the perlite/vermiculite medium. Black Mitcham had the highest susceptible disease rating and greatest reduction in fresh shoot weight from inoculation with Verticillium dahliae at two inoculum concentrations, 104 or 106 microconidia/ml. Native spearmint was resistant and Mentha crispa was moderately resistant, whereas, Murray Mitcham peppermint and Scotch spearmint were moderately susceptible to verticillium wilt with a corresponding lower fresh shoot weight. Scotch spearmint was less susceptible at the low inoculum concentration than at a higher level of microconidia, indicating a low level of disease resistance. Overall, the two inoculation methods resulted in similar cultivar responses to verticillium wilt, although the root-injection method was more applicable for large plant populations. Thus, the root-injection method of inoculation was utilized to screen 743 Black Mitcham derived somaclones for wilt resistance, of which nine somaclones were found resistant in repeated inoculation tests. This revised version was published online in July 2006 with corrections to the Cover Date.     

Autologous peptides constitutively occupy the antigen binding site on Ia

Low molecular weight material associated with affinity-purified class II major histocompatibility complex (MHC) molecules of mouse (Ia) had the expected properties of peptides bound to the antigen binding site of Ia. Thus, the low molecular weight material derived from the I-Ad isotype was efficient in inhibiting the binding of 125I-labeled I-Ad-specific peptide to I-Ad, but did not significantly inhibit the binding of an I-Ed-specific peptide to I-Ed; the reciprocal isotype-specific inhibition was demonstrated with low molecular weight material derived from I-Ed. The inhibitory material was predominantly peptide in nature, as shown by its susceptibility to protease digestion. It was heterogeneous as measured by gel filtration (mean molecular weight approximately 3000), and when characterized by high-performance liquid chromatography, it eluted over a wide concentration of solvent. Such self peptide-MHC complexes may have broad significance in the biology of T cell responses, including generation of the T cell repertoire, the specificity of mixed lymphocyte responses, and the immune surveillance of self and nonself antigens in peripheral lymphoid tissues.     

Immunological self, nonself discrimination

The ability of immunodominant peptides derived from several antigen systems to compete with each other for T cell activation was studied. Only peptides restricted by a given transplantation antigen are mutually competitive. There is a correlation between haplotype restriction, ability to bind to the appropriate transplantation antigen, and ability to inhibit activation of other T cells restricted by the same transplantation antigen. An exception was noted in that a peptide derived from an antigen, bacteriophage lambda cI repressor, binds to the I-Ed molecule in a specific way, yet is not I-Ed-restricted. Comparison of the sequence of the repressor peptide with that of other peptides able to bind to (and be restricted by) I-Ed and a polymorphic region of the I-Ed molecule itself revealed a significant degree of homology. Thus, peptides restricted by a given class II molecule appear to be homologous to a portion of the class II molecule itself. The repressor-derived peptide is identical at several polymorphic residues at this site, and this may account for the failure of I-Ed to act as a restriction element. Comparison of antigenic peptide sequences with transplantation antigen sequences suggests a model that provides a basis for explaining self, nonself discrimination as well as alloreactivity.     

Extent and possible conservation implications of fish use for research,testing and education in North America

• 1. Fish species are used globally for fundamental research, product and environmental testing, and education, but this use has not hitherto been documented. The number of fish used for research and education in North America currently represents approximately one‐quarter of all animal use for these purposes; only mice are used in higher numbers. Data from the Canadian Council on Animal Care, various animal care committees from Canadian universities, and the United States Fish and Wildlife Service are collated and summarized.
• 2. In Canada nearly a half a million fish were used for research and education each year from 1996 to 2001. We estimated that the United States used over four times that amount for the same purposes, totalling approximately 2.8 million fish each year.
• 3. At least 100 fish species, representing 27 taxonomic orders, were used for research and education in North America from 1996 to 2001. Close to one‐third of the species had life‐history characteristics that might make them particularly susceptible to over‐exploitation. This potential vulnerability, coupled with data from animal care facilities in Canada suggesting that nearly half of all fish used for research and education were wild‐caught, should prompt further documentation of such fish uses in order to assess their sustainability.

Copyright © 2006 John Wiley & Sons, Ltd.     

Ontogeny and dietary specialization in brown trout (Salmo trutta L.) from Loch Ness, Scotland, examined using stable isotopes of carbon and nitrogen

Abstract – The trophic ecology of many fish species in cold temperate lakes is often characterized by a generalist or opportunist strategy. In this study, the diets of polytrophic brown trout in Loch Ness, Scotland, have been examined using stable isotopes of carbon and nitrogen to complement gut content analyses and aging by otolith annuli counts. Using the stable isotope ratios, it was possible to trace trout ontogeny from parr development in a natal river to piscivory in the pelagic. Potential dilution of maternal isotope signatures from eggs to parr was also demonstrated. Despite the low productivity of the loch, intraspecific variability in isotope ratios suggested dietary specialization, rather than opportunism, in some individuals.     

Field Method for Biosolids N Mineralization Using Porous Ceramic Cups

A new technique was developed for field determination of N mineralization from biosolids, which provides a simple, inexpensive test that yields accurate results. A residuals technique was used; mineralization was defined as the difference between the original and final mass of organic nitrogen. Biosolids were collected from a number of British Columbia wastewater treatment plants (WWTPs), placed in porous ceramic tubes and incubated under controlled conditions. Variables studied included wet versus dry biosolids, application rate, tube size, inoculation solution, and the effect of a soil addition mixed with biosolids. There was little difference in N mineralization between wet and dried biosolids, however variability was reduced using dried biosolids. No difference was observed using different amounts of biosolids. When dried biosolids were inoculated with supernatant obtained from a soil and biosolids mixture, decomposition was higher than with supernatant from the individual mediums alone. However, mineralization was fairly close with all inoculates. The addition of soil had little effect on biosolids decomposition other than resulting in a higher variability.