Introduction of an amylose-free (amf) mutant into breeding of cultivated potato,Solanum tuberosum L.

Summary Using an amylose-free (amf)mutant of diploid potato (Solanum tuberosum), diploid and tetraploid clones with different genotypes at the amf-locus were produced. In order to make use of the diploid material in analytic breeding of amf-potatoes, clones were selected that produced a considerable frequencies of 2n-pollen and 2n-eggs. Successful attempts were made to select normal synaptic as well as desynaptic clones producing 2n-gametes. Based on the phenotype of starch in the microspores, tetraploid clones with nulliplex, simplex and duplex genotypes at the amf-locus were selected. Prospects of using this material in conventional as well as in analytic breeding of potato are discussed.     

Persistence of oxytetracycline in sediments from fish farms

The persistence of oxytetracycline, an antibacterial agent, in bottom deposits from fish farms was investigated. The drug was found in concentrations capable of causing antimicrobial effects up to 12 weeks after administration. A half-life of approximately 10 weeks was estimated through a pilot study. Possible effects on sulphide ion activity are suggested.     

Clinical skills and knowledge used by veterinary graduates during their first year in small animal practice

Objective To determine the clinical skills and areas of knowledge used by veterinarians in small animal practice during their first year after graduation and the degree of assistance and supervision they received while developing these skills. Design A postal survey was sent in December 1999 to 59 veterinarians who completed their training at Murdoch University in December 1998. Procedure The first part of the survey asked for information on veterinary work patterns since leaving university. The second part consisted of a list of diagnostic and therapeutic skills of varying complexity and the graduates were asked to indicate whether they had used these skills in practice and whether they had been assisted or supervised while doing them. The respondents were also asked if they had had the opportunity to practise these skills as undergraduates at university or during extramural experience. In the third part the areas of knowledge used in practice were assessed by analysis of a series of consecutive cases. Results Forty replies were received but since three graduates had done no small animal work the analysis of the skills section is based on 37 responses. Thirty graduates supplied information on 994 canine cases and 308 feline cases. The distribution of the mean work time was dogs and cats 69%, horses 13%, farm animals 11%, birds 3% and others 4%. Skills used by over 90% of graduates included general anaesthesia, examination of the tympanic membrane, taking and interpreting an abdominal radiograph, catheterising a male cat, fine needle aspiration of a mass, neutering dogs and cats, tooth scaling and extraction and treating an aural haematoma. The survey also identified the opportunities for undergraduates to practise some of these skills during extramural experience and the extent of assistance given to new graduates during their first year in practice. The areas of knowledge used in over 10% of the cases included vaccination, anaesthesia/sedation, skin/coat problems, general advice on pet health, neutering and musculoskeletal diseases. Conclusion Veterinarians, in their first year after graduation, use a wide range of complex diagnostic and therapeutic skills. Although many of these skills are acquired during the undergraduate training, a significant contribution is made by extramural practical work undertaken during the clinical years of the undergraduate course and in the first year following graduation. Practising veterinarians play an important role in providing opportunities and supervision for clinical training.     

Oxidation in fish oil enriched mayonnaise: ascorbic acid and low pH increase oxidative deterioration

The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil-water interface into the aqueous phase at all pH levels, but this effect of ascorbic acid was strongest at low pH (pH 3.8-4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced due to the reduction of Fe(3+) to Fe(2+) that rapidly catalyzes lipid oxidation via lipid hydroperoxide decomposition at the oil-water interface in mayonnaise.     

Partitioning of selected antioxidants in mayonnaise.

This study examined partitioning of alpha-, beta-, and gamma-tocopherol and six polar antioxidants (Trolox, ferulic acid, caffeic acid, propyl gallate, gallic acid, and catechin) in mayonnaise. Partitioning of antioxidants between different phases was determined after separation of mayonnaise by either (a) centrifugation + ultracentrifugation or (b) centrifugation + dialysis. Antioxidants partitioned in accordance with their chemical structure and polarity: Tocopherols were concentrated in the oil phase (93-96%), while the proportion of polar antioxidants in the oil phase ranged from 0% (gallic acid and catechin) to 83% (Trolox). Accordingly, proportions of 6% (Trolox) to 80% (gallic acid and catechin) were found in the aqueous phase. Similar trends were observed after dialysis. After ultracentrifugation, large proportions of polar antioxidants were found in the "emulsion phase" and the "precipitate" (7-34% and 2-7%, respectively). This indicated entrapment of antioxidants at the oil-water interface in mayonnaise. The results signify that antioxidants partitioning into different phases of real food emulsions may vary widely.