MSc Astrid de Haan academic dissertation is presented, with the permission of the Faculty of Veterinary Medicine, Univerity of Helsinki, for public examination in Auditorium Walter (Agnes Sjöbergin katu 2), Helsinki on 28th of September 2012.

Title of thesis is  “Molecular typing and source attribution of Finnish Campylobacter jejuni isolates” and it belongs to the field of environmental health.

The opponent is professor Dr. Birgitta Duim (Utrecht University, Netherlands) and the custos is professor Marja-Liisa Hänninen.

An electronic version of the dissertation.

MSc Manuel González Jiménez’s academic dissertation was presented, with the permission of the Faculty of Veterinary Medicine, Univerity of Helsinki, for public examination in Auditorium Walter (Agnes Sjöbergin katu 2), Helsinki on 14th of September 2012.

Title of thesis is  ”Characterization of Campylobacter jejuni strains from different hosts and modelling the survival of C. jejuni on chicken meat and in water” and it belongs to the field of environmental health.

The opponent was professor Sonja Smole-Mozina (University of Ljubljana, Slovenia) and the custos was professor Marja-Liisa Hänninen.

An electronic version of the dissertation.

The Academy of Finland has granted funding worth 367 729 euro for the research project: ´Exploring the Physiological and Toxicological Functions of the AH Receptor: Involvement in Avoidance of Novel Food Items, Regulation of Circadian Rhytms, and Transgenerational Effects´. The project leader is professor Raimo Pohjanvirta from the Department of Food Hygiene and Environmental Health.

The aryl hydrocarbon receptor (AHR) is a protein that is best-known as the mediator of the toxic effects of the environmental contaminants dioxins and PAH compounds. In recent years, it has been found out that the AHR plays important roles in normal physiological processes including liver development, heart function and immunological responses (e.g. autoimmunity). In the present set of studies, the physiological and toxicological functions of the AHR will be further explored. The focus will be on the following three phenomena:

1.  Possible causal relationship between hepatic induction of  drug-metabolizing enzymes and a behavioral change, avoidance of novel food items
2. Involvement of the AHR in regulation of circadian rhythms
3. Whether or not the harmful impacts caused by activated AHR can be transmitted to future generations.

The findings of these studies can be expected to significantly further our understanding of this intriguing protein which can be both beneficial and deleterious.

The main collaborator is Dr. Paul Boutros’s research group in the Ontario Institute of Cancer Research, Toronto, Kanada.

>> The first book on the AH receptor: The AH Receptor in Biology and Toxicology

The Academy of Finland granted funding 326 344 € for the research project ´Molecular epidemiology and environmental reservoirs for β-lactamase- and carbapenemase producing Enterobacteriaceae in Finland.´

The funding is for three years and the project leader is DVM, PhD, Postdoctoral Researcher Annamari Heikinheimo from the Department of Food Hygiene and Environmental Health.

Antibiotic resistance is rapidly spreading worldwide, and one of great concerns is the rapid growth of extended-spectrum β-lactamase (ESBL) and carbapenemase resistance in Enterobacteriaceae family, especially in Klebsiella pneumoniae and Escherichia coli. They cause different infections such as urinary tract infection and soft tissue infections, and resist wide range of antibiotics. These bacteria spread now rapidly in Finnish hospitals and also in community.

Due to global trade and travel, antibiotic resistant bacteria spread rapidly to distant countries and continents by human travelers, animal reservoirs, and foods. Food chain may serve as a transmission route for these infections. Recently found panresistant NDM-1 bacteria possess a worrisome problem if entering the food chain. The transmission routes of ESBL bacteria to humans via foods and food producing animals is being elucidated in this project.

This research project is conducted in collaboration with professor Martti Vaara’s research group from Helsinki Univeristy Hospital (HUSLAB) and professor Frank Aarestrup’s research group from Danish Technical University (DTU). The laboratory in Copenhagen serves as WHO World Health Organization’s collaboration centre and European Union’s reference laboratory for antibiotic resistance in animals and foods.

University of Helsinki has its research and doctoral training evaluated every sixth year. In the recent evaluation covering the years 2005-2010, the research groups of the Department of Food Hygiene and Environmental Health formed a research community (CoE-MiFiSaPLUS) together with the microbiological groups of the Department of Veterinary Biosciences.

CoE-MiFiSaPLUS was an extended research community based on the Center of Excellence in Microbiological Food Safety Research led by Professor Palva. Research in CoE-MiFiSaPLUS was evaluated outstanding (scores 24/25) by the international scientific panel. University of Helsinki allocated 390000 € for CoE-MiFoSaPLUS during 2013-2016. In the last evaluation the Department of Food Hygiene and Environmental Health got maximum scores (7/).

The evaluation report concerning CoE-MiFiSaPLUS

The summary report on the evaluation of University of Helsinki

A recent study by DVM Annukka Markkula and colleagues showed that three DEAD-box RNA helicases are needed for cold-temperature growth of Listeria monocytogenes. Deletion of single DEAD-box RNA helicase genes increased the minimum growth temperature and dramatically decreased the growth rate of L. monocytogenes at 3˚C. In addition, deletion of helicase genes reduced the motility of L. monocytogenes. The study was published in valued Environmental Microbiology journal.

Environ Microbiol 2012, Early View, doi:10.1111/j.1462-2920.2012.02761.x

Markkula A, Mattila M, Lindström M, and Korkeala H.

Department of Food Hygiene and Environmental Health, University of Helsinki

Genes encoding putative DEAD-box RNA helicases in Listeria monocytogenes EGD-e are needed for growth and motility at 3˚C

The study showed that the relative expression of all four DEAD-box RNA helicase-encoding genes of L. monocytogenes EGD-e was increased at 3˚C. The growth rate of three deletion mutant strains was decreased at 25˚C compared to that of the wild type L. monocytogenes EGD-e. At 3˚C the growth of three mutant strains was virtually impaired. Deletion of the genes increased the minimum growth temperature of strains by 4.9-8.8˚C. A total of two cold sensitive deletion mutant strains were impaired in motility. Motility of a cold-sensitive strain was decreased approximately by half compared to the wild type EGD-e.

The study shows that three DEAD-box RNA helicases have an important role in cold tolerance and motility of L. monocytogenes EGD-e. The role of one DEAD-box RNA in cold tolerance and motility is negligible.

DEAD-box RNA helicases are found in most living organisms and are involved in various aspects of RNA metabolism from transcription to RNA decay. DEAD-box RNA helicases have recently been linked to cold tolerance of some bacteria. At cold temperatures stability of RNA secondary structures, like RNA duplexes increases. DEAD-box proteins function as helicases that separate short duplex regions of RNA.

The research was carried out at the Finnish Centre of Excellence in Microbial Food Safety Research and supported by the Finnish Graduate School on Applied Bioscience and the Walter Ehrström Foundation.

Academy of Finland granted funding 240 000€ for the research project ‘The Pathogenic Mechanisms of Clostridium botulinum type E ‘. The project leader is DVM, PhD, Professor Miia Lindström from the Department of Food Hygiene and Environmental Health. The main collaborators are Professor Yukako Fujinaga and Dr. Yo Sugawara from Osaka University, Japan.

Botulinum neurotoxin, the most potent natural poison, is produced by the spore-forming soil and food bacterium Clostridium botulinum. The toxin causes life-threatening paralysis, botulism. Countries with type E toxin causing a serious public health risk via traditional fish products include Finland and Japan. Cases of intestinal botulism due to toxigenic growth in the gut of small babies are also reported. At the same time, types A and B neurotoxins are applied in therapeutics to treat spastic muscular disorders from torticollis to genitourinary disorders and migraine. Due to unfavourable immunity development, interest towards alternative toxin types is increasing. However, the structure and function of types E and F neurotoxins are poorly known. This project will characterize neurotoxin type E protein complex. This helps to prevent human botulism and develop novel therapeutic toxins. Multiple medical applications and thus highly beneficial impacts on public health are expected.

A new book on the aryl hydrocarbon (AH) receptor has recently been published; the title of the book is The AH Receptor in Biology and Toxicology. Professor of  Toxicology, Raimo Pohjanvirta, from the Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, is the editor of the book. Nowadays the AH receptor is a hot research subject in the biomedical research field, such as research of autoimmune diseases, physiological intestinal immune defense, blood vessel development, tumor cell proliferation, and functional regulation of the testicles,  as well as in toxicological research topics, like toxicity mechanism of dioxins and PAH compounds, natural AH receptor ligands in food, and effects of ultraviolet light.

The book provides an up-to-date overview of the AH receptor and its unique dual role in toxicology and biology. The coverage includes epigenetic mechanisms, gene expression, reproductive and developmental toxicity, signal transduction, and transgenic animal models.

The book is intended for the researchers and students in the disciplines of toxicology, pharmacology, physiology, cell biology and biochemistry, and also for everyone interested in getting more information on the subject.

 “Surprisingly, there has not been any book available solely focusing on this important receptor in the fields of physiology and toxicology before.  When a representative of the major American publishing company, John Wiley & Sons, contacted me at the end of spring 2009, and asked if I were interested in editing a book of this kind, I enthusiastically accepted the challenge.”  Raimo Pohjanvirta tells about the early stages of editing the book. “I made a preliminary table of contents and a brief description of each chapter´s contents, which were sent to six independent reviewers for  a scientific evaluation.  I invited some thirty globally renowned leading researchers to my “dream team”, and gladly almost everyone accepted my request to be the responsible author of an individual chapter.

The Finnish research is also well displayed in the book. Three out of 35 chapters were written by Finnish researchers.  “I thought that it is important to bring out the high quality of Finnish research on dioxins and the AH receptor.  In addition to this, I wrote one chapter and the preface myself. All this hard editing work was highly rewarding because the outcome is very successful in my opinion”, says Raimo Pohjanvirta. “Hopefully the book will be an important source of information for a long time to come for all those interested in the AH receptor.”

The AH Receptor in Biology and Toxicology (ed. by Raimo Pohjanvirta; Wiley & Sons, Inc. 2012; 531 p.)

DVM Sonja Virtanen has discovered that piglets are a major source of Yersinia enterocolitica on fattening-pig farms. Contaminated piglets from certain breeding farms bring the infection to fattening farms and the infection subsequently spreads through the whole unit. The study was done in research group of professor Hannu Korkeala. Results were recently published in Applied and Environmental Microbiology.

Appl Environ Microbiol. 2012, published online ahead of print on 3 February 2012

Virtanen S., Salonen L., Laukkanen-Ninios R., Fredriksson-Ahomaa M. and Korkeala H.

Department of Food Hygiene and Environmental Health, University of Helsinki

Piglets are a source of pathogenic Yersinia  enterocolitica on fattening-pig farms

Piglets (n=76) from 16 farrowing farms were monitored in a fattening farm in two separate units through the whole fattening time. Fecal samples were collected in two-week intervals and blood samples were taken both in the beginning and at the end of the study. Feces were cultured on CIN-agars after cold enrichment in PMB-broth. Y. enterocolitica isolates were genotyped using an MLVA method. Blood samples were tested for the presence of Yersinia antibodies with an ELISA test.

Certain piglets were found to be infected with Y. enterocolitica already in their original farm. Antibodies against Yersinia were found in their blood samples and farm-specific genotypes of the pathogen were isolated from their feces next day after arrival into the fattening farm.

Only a minority of piglets seemed to bring Y. enterocolitica into the fattening farm but these piglets soon transmitted the infection to the rest of the pigs. During the fattening time the infection was spreading through the whole herd. Each pig was shedding the pathogen in feces at some point.

Dominant Y. enterocolitica genotypes were detected within the pens.  Same genotypes circulated within each unit and were present through the whole fattening time. No additional genotypes emerged after the beginning of the follow-up.

The same genotype (type A) was found in both units. This genotype originated from a certain farm who delivered piglets into the two units. This farm seemed to be a reservoir of this genotype and apparently the piglets from this farm continuously transmit the contamination when delivered into different fattening farms.

Piglets from certain farms bring Y. enterocolitica into a fattening farm and the infections spreads through the whole unit. In order to prevent this pathogen in pig production, mixing Y. enterocolitica positive and negative piglets should be avoided and preventive methods should be targeted into contaminated farrowing farms.

The project is funded by the Ministry of Agriculture and Forestry.