Finding horse meat in beef products--a global problem.

The Food Safety Authority of Ireland (FSAI) oversees the implementation of food safety controls in Ireland which are set out in EU and Irish law. The FSAI, a science-based consumer protection organization, has nurtured a close relationship with the scientific community allowing it to utilize the best scientific advice available to underpin risk assessments. In early 2013, a 2-month long investigation in to the authenticity of beef products culminated in the publication of results that demonstrated the presence of horse meat in a frozen burger produced in Ireland. The events that followed revealed a pan-European food fraud which will likely result in significant changes in the way this small section of the meat industry will be regulated in the future in the EU. Although revelations of implicated products and food businesses have relented, the EU-wide investigation is continuing in an effort to determine how a food fraud of this scale could have occurred in such a highly regulated industry and who was involved. The FSAI initially received some criticism after publication of the results, but was also commended for its scientific approach as well as its openness and transparency. The end result of this incident is likely to be that the complexity of the food chain will be addressed again and DNA-based or similar methods will become a regular feature in verifying the authenticity of meat-based foods.

Isolation of Arabidopsis mutants lacking components of acquired thermotolerance.

Acquired thermotolerance is a complex physiological phenomenon that enables plants to survive normally lethal temperatures. This study characterizes the temperature sensitivity of Arabidopsis using a chlorophyll accumulation bioassay, describes a procedure for selection of acquired thermotolerance mutants, and provides the physiological characterization of one mutant (AtTS02) isolated by this procedure. Exposure of etiolated Arabidopsis seedlings to 48 degrees C or 50 degrees C for 30 min blocks subsequent chlorophyll accumulation and is eventually lethal. Arabidopsis seedlings can be protected against the effects of a 50 degrees C, 30-min challenge by a 4-h pre-incubation at 38 degrees C. By the use of the milder challenge, 44 degrees C for 30 min, and protective pretreatment, mutants lacking components of the acquired thermotolerance system were isolated. Putative mutants isolated by this procedure exhibited chlorophyll accumulation levels (our measure of acquired thermotolerance) ranging from 10% to 98% of control seedling levels following pre-incubation at 38 degrees C and challenge at 50 degrees C. The induction temperatures for maximum acquired thermotolerance prior to a high temperature challenge were the same in AtTS02 and RLD seedlings, although the absolute level of chlorophyll accumulation was reduced in the mutant. Genetic analysis showed that the loss of acquired thermotolerance in AtTS02 was a recessive trait. The pattern of proteins synthesized at 25 degrees C and 38 degrees C in the RLD and AtTS02 revealed the reduction in the level of a 27-kD heat shock protein in AtTS02. Genetic analysis showed that the reduction of this protein level was correlated with the acquired thermotolerance phenotype.

Characterization of a desiccation-responsive small GTP-binding protein (Rab2) from the desiccation-tolerant grass Sporobolus stapfianus.

We have used differential display to detect altering mRNA levels in response to desiccation and rehydration in leaves of the desiccation tolerant grass Sporobolus stapfianus. One of the RT-PCR products identified was used to isolate a cDNA of 999 bp which encodes a protein of 210 amino acids (predicted size 23 kDa). This protein displays considerable sequence similarity to mammalian and plant Rab2, a small GTP-binding protein, possessing several conserved motifs common to these regulatory proteins. Sporobolus Rab2 was expressed in Escherichia coli yielding a protein with an apparent molecular mass of ca. 30 kDa which was shown to have the ability to bind GTP. Rab2 transcript accumulated early in response to a decrease in relative water content (RWC) and remained high even in dried leaves. Rehydration of desiccated leaves resulted in a decrease in levels within 3 h of rewetting, with a brief increase at ca. 12 h. Accumulation of Rab2 transcript was also evident during drying and rehydration of the roots of S. stapfianus, as well as in leaves of the desiccation-sensitive grass Sporobolus pyramidalis. Earlier work on S. stapfianus concluded that the plant hormone ABA has little effect on inducing desiccation tolerance, however Rab2 transcript does exhibit a small increase in accumulation in response to exogenous ABA. A possible role for Rab2 with respect to desiccation tolerance and damage repair is discussed.

The involvement of ubiquitin in vegetative desiccation tolerance.

We have isolated a polyubiquitin cDNA from the modified desiccation-tolerant grass Sporobolus stapfianus. This cDNA, along with a commercially available polyclonal ubiquitin antibody, was used to characterize desiccation/rehydrated-associated changes in ubiquitin-mediated protein degradation in S. stapfianus and the fully desiccation-tolerant moss Tortula ruralis. Northern analysis demonstrated that in S. stapfianus leaves two ubiquitin transcripts, of ca. 1.4 and 1.2 kb, accumulated above control levels during drying and rehydration but were barely detectable in desiccated tissue. The peak in rehydration-associated transcript accumulation coincided with a depletion in ubiquitin monomer levels indicating an increase in protein degradation. Analysis of T. ruralis revealed three ubiquitin transcripts of ca. 1.9, 1.3 and 0.65 kb, with only the 1.3 kb transcript level varying in response to drying and rehydration and all transcripts being stable in dried tissue. Western analysis revealed that conjugated ubiquitin, indicative of proteins targeted for removal, was evident in all samples of Sporobolus but detectable only in slow-drying Tortula which also displayed reduced levels of ubiquitin monomer. These results demonstrate that desiccated T. ruralis gametophyte possesses stable ubiquitin transcripts which can be translated upon rehydration enabling rapid initiation of cellular repair through degradation of certain proteins. This is in contrast to S. stapfianus which requires several hours to replenish depleted ubiquitin transcripts. The ubiquitin response to drying and rehydration in evolutionarily diverse systems is characterized, and the role of repair mechanisms such as ubiquitin-mediated protein degradation in desiccation tolerance is assessed.

Regulation of juvenile hormone esterase gene transcription by juvenile hormone.

Juvenile hormone (JH) is a major hormone regulating insect development. We have obtained a cDNA and a genomic clone for juvenile hormone esterase (JHE), the enzyme that is involved in the degradation of juvenile hormone and which is critical for insect development. Analysis of the regulation of JHE during the final larval stadium in the cabbage looper, Trichoplusia ni, showed that the JHE mRNA levels are maximal on days 2 and 4 of the final stadium. Nuclear run-on analyses demonstrated that changes in JHE mRNA levels are primarily due to changes in the transcription rate of the gene, which may be a single copy in the genome. Treatment with a JH analog resulted in induction of JHE gene transcription, which could be detected within three hours after treatment. Salient features present in the 5' flanking region of this JH-sensitive gene are presented, including the presence of sequences closely resembling binding sites for members of the family of nuclear receptors. This report is the first direct demonstration, by nuclear run-on analysis, of JH induction of gene transcription.