Effect of the Shellfish Proteinase K Digestion Method on Norovirus Capsid Integrity

Norovirus outbreaks are associated with the consumption of contaminated shellfish, and so efficient methods to recover and detect infectious norovirus in shellfish are important. The Proteinase K digestion method used to recover norovirus from shellfish, as described in the ISO 15216, would be a good candidate but its impact on the virus capsid integrity and thus infectivity was never examined. The aim of this study was to assess the impact of the Proteinase K digestion method, and of the heat treatment component of the method alone, on norovirus (genogroups I and II) and MS2 bacteriophage capsid integrity. A slightly modified version of the ISO method was used. RT-qPCR was used for virus detection following digestion of accessible viral RNA using RNases. MS2 phage infectivity was measured using a plaque assay. The effect of shellfish digestive glands (DG) on recovery was evaluated. In the presence of shellfish DG, a reduction in MS2 phage infectivity of about 1 log₁₀ was observed after the Proteinase K digestion method and after heat treatment component alone. For norovirus GII and MS2 phage, there was no significant loss of genome following the Proteinase K digestion method but there was a significant 0.24 log₁₀ loss of norovirus GI. In the absence of shellfish DG, the reduction in MS2 phage infectivity was about 2 log₁₀, with the addition of RNases resulting in a significant loss of genome for all tested viruses following complete Proteinase K digestion method and the heat treatment alone. While some protective effect from the shellfish DG on viruses was observed, the impact on capsid integrity and infectivity suggests that this method, while suitable for norovirus genome detection, may not completely preserve virus infectivity.     

Vorschl?ge zur Charakterisierung und quantifizierung pfadübergreifender Schadstoffexpositionen

Zusammenfassung  Um zu einer sachgerechten und nachvollziehbar quantifizierbaren Beurteilung der m?glichen Gesundheitsbelastungen des Menschen durch Schadstoffe zu gelangen, ist es von grundlegender Bedeutung dessen ?u?ere Schadstoffexposition absch?tzen zu k?nnen. Um die Durchführung derartiger Absch?tzungen zu erm?glichen, werden nutzergruppen- und expositionsszenariospezifisch orale, inhalative und dermale Aufnahmeraten für die Kontaktmedien Boden, Pflanzen aus Haus- und Schreberg?rten, Trinkwasser, Staub, Hausstaub und Innenraumluft vorgeschlagen. Diese Aufnahmeraten dienen, gemeinsam mit gemessenen oder berechneten Schadstoffkonzentrationen in den entsprechenden Kontaktmedien, zur Absch?tzung der von Menschen aufgenommenen Schadstoffdosen und erm?glichen durch einen Vergleich mit tolerierbaren Schadstoffdosen eine stoff-, nutzungs- und standortbezogene Beurteilung von Schadstoffexpositionen, auch für komplexe Nutzungen.      

Very slow development in two Antarctic bivalve molluscs,the infaunal clam <Emphasis Type="Italic">Laternula elliptica</Emphasis> and the scallop <Emphasis Type="Italic">Adamussium colbecki</Emphasis>

Embryos of the large infaunal clam Laternula elliptica and the scallop Adamussium colbecki, from Antarctica, were cultured over an 18-month period. Their development rates were extremely slow, taking 240 and 177 h, respectively, to reach the trochophore stage. This is ×4 to ×18 slower than related clams and scallops from temperate latitudes. The relationship between temperature and development rate for bivalve molluscs shows the expected slowing with reduced temperature (Q ₁₀ in the range 2–4) for temperate and tropical species. However, the slowing at polar latitudes is much stronger than at warmer waters, and all of the limited data for Antarctic species are well above the Arrhenius plot for the overall bivalve data, and the Q ₁₀ value for Antarctic to cool temperate species is 11.8, well outside the expected range for biological systems. Either the relationships describing the effects of temperature on the kinetics of biological systems do not apply to Antarctic bivalve molluscs, or some other factor that cannot be compensated for becomes important at low temperature. In the laboratory, L. elliptica embryos stayed viable in very sticky egg capsules for up to 18 months without hatching. However, even the disturbance of removing eggs using a pipette ruptured some egg capsules allowing embryo release. Gametogenesis in Antarctic marine invertebrates is almost universally slowed compared to temperate species, with nearly all cases documented requiring more than 1 year to complete oogenesis. The only exception so far appears to be A. colbecki, which has a 1-year gametogenic cycle. The data here indicate that it has been unable to adapt embryonic development in a similar way, and we are not aware of any exceptions to the markedly slowed development at low temperature rule.     

Loud calls as indicators of dominance in male baboons (Papio cynocephalus ursinus)

Adult male baboons (Papio cynocephalus) give loud two-syllable 'wahoo' calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. These 'contest' wahoos are acoustically different from 'alarm' wahoos given to predators. In a study of free-ranging baboons in the Okavango Delta, Botswana, we found no significant correlations between the acoustic features of wahoos and adult male size; however, acoustic features were correlated with male dominance rank, age, and calling bout length. Here we show that other measures of calling behavior also appear to function as honest indicators of stamina and competitive ability. High-ranking males were more likely than middle- or low-ranking males to participate in wahoo bouts. They called at significantly higher rates, and their bouts were longer and contained more calls. All males were significantly more likely to participate in wahoo bouts with another male if their opponent's rank was similar to their own. Bouts involving males of similar ranks were longer, contained more wahoos, and involved calling at higher rates, than other bouts. In contests between males of similar ranks, the subordinate and dominant were equally likely to end the bout, whereas in contests involving males of disparate ranks, subordinates were significantly more likely to end the bout. Bouts involving males of similar rank were significantly more likely than others to escalate and result in physical fighting.     

Sex linkage among genes controlling sexually selected traits

Using literature data on reciprocal crosses I estimated the influence of sex-chromosomal genes on morphological and behavioral traits. To determine a special role of the sex chromosomes for sexually selected traits, I compared the estimated influence of X-chromosomal genes on sexually selected traits with their estimated influence on traits not under sexual selection. About one-third of the phenotypic variation in sexually selected traits is caused by X-chromosomal genes. There was, in contrast, no significant influence of X-chromosomal genes on traits that were classified as not sexually selected. Sexually selected traits thus seem to be influenced significantly more by X-chromosomal genes than traits not under sexual selection. Though this differential influence of X-chromosomal genes cannot readily be explained with current theoretical knowledge, it may shed some light on X-linked hybrid sterility and on the discussion between arbitrary and good-gene models for the evolution of female choice. Received: 30 January 1998 / Accepted after revision: 20 June 1998     

Expositionsszenarien nach REACH

Object and Background

Production and use of substances and formulations can result in exposures on humans and the environment. In October 2003, the European Commissions presented a proposal for the registration, evaluation, assessment and restriction of chemicals (REACH). Assessment of exposures will become an essential element of REACH for certain substances. For many manufacturers and users of substances and formulations these tasks are new. Pilot projects to REACH have shown so far that solutions and instruments for these tasks which meet the requirements of real life situations have yet to be developed.

Discussion and Conclusions

Within the REACH proposal, exposure scenarios are a main element of the chemical safety assessment. This article outlines the contents of exposure scenarios. It reflects experiences with exposure scenarios and discusses possibilities of standardization. It covers exposure steps/categories and possibilities to build product groups. Non-branch specific types of exposure situations are an important element of exposure scenarios. Therefore, exposure steps/categories should be contained in exposure scenarios. Nevertheless, these elements structure only a specific part of the information contained in exposure scenarios. Hence they cannot replace exposure scenarios. Exposure categories do not reveal the uses, the processes and the activities connected with the intended use of substances. These information are important parts of a complete exposure scenario. They are the basis for the following step of risk characterisation. In addition, they provide the necessary transparency regarding the use patteern of substances.