Classification and nomenclature of endogenous retroviral sequences (ERVs): Problems and recommendations

The genomes of many species are crowded with repetitive mobile sequences. In the case of endogenous retroviruses (ERVs) there is, for various reasons, considerable confusion regarding names assigned to families/groups of ERVs as well as individual ERV loci. Human ERVs have been studied in greater detail, and naming of HERVs in the scientific literature is somewhat confusing not just to the outsider. Without guidelines, confusion for ERVs in other species will also probably increase if those ERVs are studied in greater detail. Based on previous experience, this review highlights some of the problems when naming and classifying ERVs, and provides some guidance for detecting and characterizing ERV sequences. Because of the close relationship between ERVs and exogenous retroviruses (XRVs) it is reasonable to reconcile their classification with that of XRVs. We here argue that classification should be based on a combination of similarity, structural features, (inferred) function, and previous nomenclature. Because the RepBase system is widely employed in genome annotation, RepBase designations should be considered in further taxonomic efforts. To lay a foundation for a phylogenetically based taxonomy, further analyses of ERVs in many hosts are needed. A dedicated, permanent, international consortium would best be suited to integrate and communicate our current and future knowledge on repetitive, mobile elements in general to the scientific community.     

Interactions of Salmonella enterica with lettuce leaves

Aims:  To investigate the interactions of Salmonella enterica with abiotic and plant surfaces and their effect on the tolerance of the pathogen to various stressors.
Methods and Results:  Salmonella strains were tested for their ability to form biofilm in various growth media using a polystyrene plate model. Strong biofilm producers were found to attach better to intact Romaine lettuce leaf tissue compared to weak producers. Confocal microscopy and viable count studies revealed preferential attachment of Salmonella to cut-regions of the leaf after 2 h at 25°C, but not for 18 h at 4°C. Storage of intact lettuce pieces contaminated with Salmonella for 9 days at 4°C resulted only in small changes in population size. Exposure of lettuce-associated Salmonella cells to acidic conditions (pH 3·0) revealed increased tolerance of the attached vs planktonic bacteria.
Conclusions:  Biofilm formation on polystyrene may provide a suitable model to predict the initial interaction of Salmonella with cut Romaine lettuce leaves. Association of the pathogen with lettuce leaves facilitates its persistence during storage and enhances its acid tolerance.
Significance and Impact of the Study:  Understanding the interactions between foodborne pathogens and lettuce might be useful in developing new approaches to prevent fresh produce-associated outbreaks.     

Evaluation of efficacy of disinfectants against Salmonella from the feed industry

Aims:  To evaluate disinfectants against Salmonella under conditions relevant for the feed industry.
Materials and Results:  A survey on the use of disinfectants in feed industry showed that a range of different types was used. Nine disinfectants, reflecting the most commonly used active ingredients, were tested for bactericidal activity on Salmonella isolated from the feed industry. All disinfectants were efficient against Salmonella in suspension. The bactericidal effect varied considerably between different types of active compounds on bacteria dried on surfaces or grown as biofilm. Tenside-based disinfectants and hypochlorite were found to have low bactericidal activity and the efficiency was significantly reduced when the ratio of amount disinfectant per cell decreased. It was shown that concentrations of 70–80% ethanol were effective against Salmonella. Among the disinfectants tested a product containing 70% ethanol was most efficient followed by Virkon S.
Conclusions:  Many disinfectants had low bactericidal activity against Salmonella at surfaces while Virkon S and a product containing 70% ethanol were most effective. Another advantage of ethanol-based disinfectants is evaporation of ethanol, resulting in low residual water after use.
Significance and Impact of the Study:  Use of the disinfectants found to be efficient against surface associated Salmonella , may assist the industry in combating Salmonella .     

Model systems allowing quantification of sensitivity to disinfectants and comparison of disinfectant susceptibility of persistent and presumed nonpersistent Listeria monocytogenes

Aims:  To determine if Listeria monocytogenes persistent strains differ from presumed nonpersistent strains in disinfection susceptibility and to examine the influence of attachment and NaCl on susceptibility.
Methods and Results:  Two model-systems that allowed quantitative inter-strain comparison of disinfectant sensitivity were developed. Persistent L. monocytogenes were not more tolerant to the disinfectants Incimaxx DES and Triquart SUPER than presumed nonpersistent isolates. When calibrating the systems with respect to presence of biological material and cell density, attached bacteria were as sensitive to disinfectants as were planktonic bacteria. Growth with 5% NaCl increased the tolerance of planktonic cells to Incimaxx DES. All strains of spot inoculated L. monocytogenes survived well 20 h of drying when protected by growth media and 5% NaCl, but were not protected by NaCl against disinfection.
Conclusions:  Persistent strains of L. monocytogenes are as susceptible to disinfectants as are presumed nonpersistent strains and attachment does not render the strains more tolerant to disinfectants. Growth with NaCl affected the susceptibility of the planktonic L. monocytogenes to Incimaxx DES and protected spot inoculated cells during drying.
Significance and Impact of the Study:  Attachment to surfaces does not per se offer protection to L. monocytogenes against disinfectants and disinfection tolerances do not appear to influence the ability of a strain to persist.     

Mitochondrial dysfunction leads to reduced chronological lifespan and increased apoptosis in yeast

We previously isolated a Saccharomyces cerevisiae mutant (HsTnII), which displays 40% reduced chronological lifespan as compared to the wild type (WT). In this study, we found HsTnII cultures to be characterized by fragmented and dysfunctional mitochondria, and by increased initiation of apoptosis during chronological aging as compared to WT. Expression of genes encoding subunits of mitochondrial electron transport chain and ATP synthase is significantly downregulated in HsTnII, and as a consequence, HsTnII is not able to respire ethanol. All these data confirm the importance of functional mitochondria and respiration in determining yeast chronological lifespan and apoptosis.     

Recent findings in pulsed light disinfection

Nonthermal disinfection technologies are gaining increasing interest in the field of minimally processed food in order to improve the microbial safety or to extend the shelf life. Especially fresh‐cut produce or meat and fish products are vulnerable to microbial spoilage, but, due to their sensitivity, they require gentle preservation measures. The application of intense light pulses of a broad spectral range comprising ultraviolet, visible and near infrared irradiation is currently investigated as a potentially suitable technology to reduce microbial loads on different food surfaces or in beverages. Considerable research has been performed within the last two decades, in which the impact of various process parameters or microbial responses as well as the suitability of pulsed light (PL) for food applications has been examined. This review summarizes the outcome of the latest studies dealing with the treatment of various foods including the impact of PL on food properties as well as recent findings about the microbicidal action and relevant process parameters.     

Decorin gene expression and its regulation in human keratinocytes

In various cell types, including cancer cells, decorin is involved in regulation of cell attachment, migration and proliferation. In skin, decorin is seen in dermis, but not in keratinocytes. We show that decorin gene (DCN) is expressed in the cultured keratinocytes, and the protein is found in the cytoplasm of differentiating keratinocytes and in suprabasal layers of human epidermis. RT-PCR experiments showed that DCN expression is regulated by pro-inflammatory and proliferative cytokines. Our data suggest that decorin should play a significant role in keratinocyte terminal differentiation, cutaneous homeostasis and dermatological diseases.