Survey of domestic food handling practices in New Zealand.

The purpose of this survey was to obtain information on the domestic meat and poultry handling practices of New Zealanders in order to support the development of quantitative risk models, as well as providing data to underpin food safety campaigns to consumers. A sample of 1000 New Zealand residents, over 18 years of age, were randomly selected from the electoral roll and asked to participate in a national postal food safety study during 2005. Three hundred and twenty six respondents completed and returned questionnaires containing usable answers, and most of these respondents 'always' prepared the main meal within the household. The majority of meat (84.6%) and poultry (62.9%) purchased by New Zealanders was fresh (rather than frozen), and most consumers (94.4%) claimed that the time taken from food selection to reaching their home was 1 h or less. The majority (approximately 64%) of fresh meat and poultry was frozen in the home and the most favoured method of thawing was at room temperature for up to 12 h. The most common time period for storing cooked or raw meat and poultry in domestic refrigerators was up to 2 days. Most survey respondents preferred their meat and poultry to be cooked either medium or well done. The most popular cooking method for chicken was roasting or baking, while most respondents preferred to pan-fry steak/beef cuts, minced beef or sausages/hamburgers. The potential for undercooking was greatest with pan-fried steak with 19.8% of respondents preferring to consume this meat raw or rare. In answer to questions relating to food handling hygiene practices, 52.2% of respondents selected a hand washing sequence that would help prevent cross contamination. However, it was estimated that 41% and 28% of respondents would use knives and kitchen surfaces respectively in a manner that could allow cross contamination. The data in this survey are self-reported and, particularly for the hygiene questions, respondents may report an answer that they perceive as being correct rather than reflecting their actual behaviour. Nevertheless, the data on food processing, transport, storage and cooking preferences represent useful inputs into the assessment of food safety along the meat and poultry food chains.

An electro-active system of immuno-assay (EASI assay) utilising self assembled monolayer modified electrodes.

Most immunoassays currently rely on optical methods for signal generation e.g. in ELISA and rapid assay formats. It has become apparent as in the Glucose sensor market that there is a need for simple direct electrical immuno-sensors. We have investigated the novel use of organic conducting monolayers used as a direct electrochemical detection support for an immuno-reaction. It was found that antibodies raised to a carbazole dimer monolayer could increase the charge movement across that monolayer surface. Antibody fragments were taken from a specific anti-carbazole antibody fragment library and combined with an antibody fragment directed to the hormone estrone 3 glucuronide (E3G), the target antigen to form a bispecific antibody fragment. The device utilised these specific antibody fragments and incorporated them on the top plate of a capillary fill format as the immuno-assay components. The immuno-reaction utilised a competition assay. Free E3G analyte in the sample displaced the bispecific antibody fragment from the immuno-surface leaving it free to bind the carbazole monolayer surface. There the binding was detected using amperometric or coulometric methods. By combining all there element it was possible to develop a sensitive immuno-assay that could detect E3G in a reproducible calibrated fashion down to 10 ng/ml.

Analysis of single-chain antibody production in Pichia pastoris using on-line methanol control in fed-batch and mixed-feed fermentations.

In the last few years the Pichia pastoris expression system has been gaining more and more interest for the expression of recombinant proteins. Many groups have employed fermentation technology in their investigations because the system is fairly easy to scale up and suitable for the production in the milligram to gram range. A large number of heterologous proteins from different sources has been expressed, but the fermentation process technology has been investigated to a lesser extent. A large number of fermentations are carried out in standard bioreactors that may be insufficiently equipped to meet the demands of high-cell-density fermentations of methylotrophic yeasts. In particular, the lack of on-line methanol analysis leads to fermentation protocols that may impair the optimal expression of the desired products. We have used a commercially available methanol sensor to investigate in detail the effects of supplementary glycerol feeding while maintaining a constant methanol concentration during the induction of a Mut(+) strain of Pichia pastoris. Specific glycerol feed rates in the range of 38-4.2 mg. g(-1). h(-1) (mg glycerol per gram fresh weight per hour) were investigated. Expression of the recombinant scFv antibody fragment was only observed at specific feed rates below 6 mg. g(-1). h(-1). At low specific feed rates, growth was even lower than with methanol as the sole carbon source and the harvest expression level of the scFv was only half of that found in the control fermentation. These results show that glycerol inhibits expression driven by the AOX1 promoter even at extremely limited availability and demonstrate the benefits of on-line methanol control in Pichia fermentation research.

Unidentified parasitic cysts in cattle.

Between February 18, 1995, and July 1, 1996, 38 cysts derived from New Zealand cattle were subjected to a diagnostic polymerase chain reaction (PCR) designed to identify genomic Taenia saginata DNA. No Tsaginata DNA was identified but an amplification product of 1078 bp was obtained consistently from several of the cysts. In Switzerland, suspect Tsaginata cysts are commonly positive for Tsaginata by PCR, but recently three cysts have also given a PCR fragment of 1078 bp, originating from a putatively unknown Taenia species.

Tissue- and species-specific promoter elements of rat gamma-crystallin genes.

The 5' flanking regions of the six rat gamma-crystallin genes (gamma A-gamma F) are all capable of conferring lens-specific expression to the bacterial chloramphenicol acetyl transferase (CAT) reporter gene in either transdifferentiating chicken neural retina cells or mouse lens epithelial cells. Deletion mapping of the most active gamma-crystallin promoter region, the gamma D region, showed that at least three elements are required for maximal expression in mouse lens epithelial cells: element(s) located between -200 and -106, a conserved CG rich region around position -75, and a CG stretch around -15. The region between -200 and -106 was dispensable in transdifferentiating chicken neural retina cells, which instead required the region between -106 and -78. The maximal activity of the gamma E and gamma F promoters was also dependent upon the integrity of the conserved CG region located around -75. A synthetic oligonucleotide containing this sequence was capable of lens-specific enhancement of the activity of the tk promoter in transdifferentiating chicken neural retina cells but not in mouse lens epithelial cells. Our results further show that this region may contain a silencer element, active in non-lens tissues, as well.