Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Accumulation of intracellular trehalose and lactose in Lactobacillus plantarum WCFS1 during pulsed electric field treatment and subsequent freeze and spray drying
Vaessen, Evelien M.J. ; Besten, Heidy M.W. den; Esveld, Erik D.C. ; Schutyser, Maarten A.I. - \ 2019
Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 115 (2019). - ISSN 0023-6438
Disaccharide - Electroporation - Lactic acid bacteria - Probiotics - Survival

Survival of bacteria during drying processes is required for products such as probiotics or starter cultures. In earlier studies high intracellular trehalose concentrations have been related to processing robustness during freezing and drying for several cell types. In this study we evaluated pulsed electric field (PEF) pre-treatment to increase intracellular trehalose in Lactobacillus plantarum WCFS1 and subsequent survival during freeze drying and storage in a trehalose matrix. Surprisingly, despite increased intracellular trehalose by PEF pre-treatment no enhanced survival was observed after drying and storage. Additional analysis of intracellular trehalose before and after freeze drying and spray drying revealed that during the drying process intracellular trehalose concentrations increased. Due to this increase the intracellular trehalose concentrations in the PEF pre-treated and control samples did not differ anymore. To explain what happens during the drying processes, results for trehalose were compared to similar experiments with lactose. A remarkable difference was observed between transfer of trehalose and lactose into cells during the freezing step before freeze drying, while both disaccharides gave similar cellular protection when used as freezing and drying matrix. Generated knowledge on transport of disaccharides into bacterial cells during freezing and drying can benefit processing of living bacterial formulations.

Effect of overwintering on survival and vector competence of the West Nile virus vector Culex pipiens
Koenraadt, Constantianus J.M. ; Möhlmann, Tim W.R. ; Verhulst, Niels O. ; Spitzen, Jeroen ; Vogels, Chantal B.F. - \ 2019
Parasites & Vectors 12 (2019)1. - ISSN 1756-3305
Diapause - Longevity - Mosquito - Overwintering - Survival - Vector competence - West Nile virus

Background: West Nile virus (WNV) is a mosquito-borne virus that is mainly transmitted among birds by Culex pipiens mosquitoes. The species Cx. pipiens consists of two biotypes named pipiens and molestus, which together can form hybrids. One of the major distinctions between the biotypes is their overwintering behaviour. Adults of biotype pipiens diapause during winter, whereas biotype molestus remains actively blood-feeding. Diapausing may affect survival and vector competence of biotype pipiens. The aims of this study were therefore to identify the biotype composition of diapausing Cx. pipiens mosquitoes, to quantify survival throughout the autumn and winter months, and to determine effects of overwintering on vector competence of emerging Cx. pipiens mosquitoes for WNV. Methods: Diapausing mosquitoes were collected at two typical overwintering locations in the Netherlands. A selection of Cx. pipiens mosquitoes was identified to biotype using real-time PCR. Survival of diapausing Cx. pipiens mosquitoes during autumn and winter was monitored by placing cages with either field-collected or laboratory-reared females in houses and sheds. Vector competence of field-collected (diapausing) and laboratory-reared (non-diapausing) Cx. pipiens mosquitoes was determined to gain insight in the effect of overwintering on WNV transmission. Results: The majority (92%) of diapausing Cx. pipiens females were identified as biotype pipiens. More than 70% of diapausing Cx. pipiens mosquitoes was able to survive for more than four months in sheds, whereas diapausing in houses resulted in 100% mortality in that same period. In contrast, non-diapausing Cx. pipiens biotype pipiens mosquitoes reared in the laboratory died within a week in both houses and sheds. Vector competence of Cx. pipiens mosquitoes that had diapaused during the autumn and winter months was comparable to non-diapausing laboratory-reared mosquitoes. Conclusions: This study confirms that the majority of Cx. pipiens mosquitoes in their typical overwintering site belongs to the pipiens biotype. It shows that more than two-third of diapausing Cx. pipiens mosquitoes is able to survive winter under sheltered winter conditions. Finally, vector competence for WNV of mosquitoes that emerge from overwintering sites is not affected by their relatively old age.

Natural variation in tolerance to sub-zero temperatures among populations of Arabidopsis lyrata ssp. petraea
Davey, Matthew P. ; Palmer, Ben G. ; Armitage, Emily ; Vergeer, Philippine ; Kunin, William E. ; Woodward, F.I. ; Quick, W.P. - \ 2018
BMC Plant Biology 18 (2018)1. - ISSN 1471-2229
Acclimation - Arabidopsis lyrata ssp. petraea - Chlorophyll fluorescence - Marginal populations - Survival

BACKGROUND: Temperature is one of the most important abiotic factors limiting plant growth and productivity. Many plants exhibit cold acclimation to prepare for the likelihood of freezing as temperatures decrease towards 0 °C. The physiological mechanisms associated with enabling increased tolerance to sub-zero temperatures vary between species and genotypes. Geographically and climatically diverse populations of Arabidopsis lyrata ssp. petraea were examined for their ability to survive, maintain functional photosynthetic parameters and cellular electrolyte leakage integrity after being exposed to sub-zero temperatures. The duration of cold acclimation prior to sub-zero temperatures was also manipulated (2 and 14 days). RESULTS: We found that there was significant natural variation in tolerances to sub-zero temperatures among populations of A. petraea. The origin of the population affected the acclimation response and survival after exposure to sub-zero temperatures. Cold acclimation of plants prior to sub-zero temperatures affected the maximum quantum efficiency of photosystem II (PSII) (Fv/Fm) in that plants that were cold acclimated for longer periods had higher values of Fv/Fm as a result of sub-zero temperatures. The inner immature leaves were better able to recover Fv/Fm from sub-zero temperatures than mature outer leaves. The Irish population (Leitrim) acclimated faster, in terms of survival and electrolyte leakage than the Norwegian population (Helin). CONCLUSION: The ability to survive, recover photosynthetic processes and cellular electrolyte leakage after exposure to sub-zero temperatures is highly dependent on the duration of cold acclimation.

Low radiographic muscle density is associated with lower overall and disease-free survival in early-stage colorectal cancer patients
Baar, Harm van; Beijer, S. ; Bours, M.J.L. ; Weijenberg, M.P. ; Zutphen, M. van; Duijnhoven, F.J.B. van; Slooter, G.D. ; Pruijt, J.F.M. ; Dronkers, J.J. ; Haringhuizen, A. ; Spillenaar Bilgen, E.J. ; Hansson, B.M.E. ; Wilt, J.H.W. de; Kampman, E. ; Winkels, R.M. - \ 2018
Journal of Cancer Research and Clinical Oncology 144 (2018)11. - ISSN 0171-5216 - p. 2139 - 2147.
Colorectal cancer - Mortality - Skeletal muscle density - Survival

Background: In cancer patients with a poor prognosis, low skeletal muscle radiographic density is associated with higher mortality. Whether this association also holds for early-stage cancer is not very clear. We aimed to study the association between skeletal muscle density and overall mortality among early-stage (stage I–III) colorectal cancer (CRC) patients. Furthermore, we investigated the association between skeletal muscle density and both CRC-specific mortality and disease-free survival in a subset of the study population. Methods: Skeletal muscle density was assessed in 1681 early-stage CRC patients, diagnosed between 2006 and 2015, using pre-operative computed tomography images. Adjusted Cox proportional hazard models were used to evaluate the association between muscle density and overall mortality, CRC-specific mortality and disease-free survival. Results: The median follow-up time was 48 months (range 0–119 months). Low muscle density was detected in 39% of CRC patients. Low muscle density was significantly associated with higher mortality (low vs. normal: adjusted HR 1.91, 95% CI 1.53–2.38). After stratification for comorbidities, the association was highest in patients with ≥ 2 comorbidities (HR 2.11, 95% CI 1.55–2.87). Furthermore, low skeletal muscle density was significantly associated with poorer disease-free survival (HR 1.68, 95% CI 1.14–2.47), but not with CRC-specific mortality (HR 1.68, 95% CI 0.89–3.17) in a subset of the study population. Conclusion: In early-stage CRC patients, low muscle density was significantly associated with higher overall mortality, and worse disease-free survival.

Survival of Phytophthora cinnamomi and Fusarium verticillioides in commercial potting substrates for ornamental plants
Puértolas, Alexandra ; Boa, Eric ; Bonants, Peter J.M. ; Woodward, Steve - \ 2018
Journal of Phytopathology 166 (2018)7-8. - ISSN 0931-1785 - p. 484 - 493.
Fusarium - Ornamental plants - Peat - Peat-free - Phytophthora - Potting substrates - Survival
Live plants, particularly when accompanied by soil or potting substrates, are considered the main pathway for international spread of plant pathogens. Modern, rapid shipping technologies for international plant trade increase the probability of plant pathogen survival during transport and the subsequent chances of disease outbreaks in new locations. The survival of two model pathogens, an Oomycete, Phytophthora cinnamomi, and a filamentous fungus, Fusarium verticillioides, was studied in two different commercial potting substrates (peat and peat-free) under glasshouse conditions in the absence of a plant host. Survival rates were analysed at 2, 7, 12 and 17 months after substrate inoculation. Fusarium verticillioides had the longest survival rate, and was still present at 17 months. In contrast, P. cinnamomi survived up to 7 months but was not recovered after 12 or 17 months. There was no significant difference in the number of colony-forming units (CFUs) of either pathogen in the two substrates, except at 2 months, when higher numbers were recovered from peat substrates.
Impact of prediagnostic smoking and smoking cessation on colorectal cancer prognosis : A meta-analysis of individual patient data from cohorts within the CHANCES consortium
Ordóñez-Mena, J.M. ; Walter, V. ; Schöttker, B. ; Jenab, M. ; O'Doherty, M.G. ; Kee, F. ; Bueno-de-Mesquita, B. ; Peeters, P.H.M. ; Stricker, B.H. ; Ruiter, R. ; Hofman, A. ; Söderberg, S. ; Jousilahti, P. ; Kuulasmaa, K. ; Freedman, N.D. ; Wilsgaard, T. ; Wolk, A. ; Nilsson, L.M. ; Tjønneland, A. ; Quirós, J.R. ; Duijnhoven, F.J.B. van; Siersema, P.D. ; Boffetta, P. ; Trichopoulou, A. ; Brenner, H. - \ 2018
Annals of Oncology 29 (2018)2. - ISSN 0923-7534 - p. 472 - 483.
Colorectal neoplasms - Meta-analysis - Smoking - Smoking cessation - Survival
Background: Smoking has been associated with colorectal cancer (CRC) incidence and mortality in previous studies and might also be associated with prognosis after CRC diagnosis. However, current evidence on smoking in association with CRC prognosis is limited. Patients and methods: For this individual patient data meta-analysis, sociodemographic and smoking behavior information of 12 414 incident CRC patients (median age at diagnosis: 64.3 years), recruited within 14 prospective cohort studies among previously cancer-free adults, was collected at baseline and harmonized across studies. Vital status and causes of death were collected for a mean follow-up time of 5.1 years following cancer diagnosis. Associations of smoking behavior with overall and CRC-specific survival were evaluated using Cox regression and standard meta-analysis methodology. Results: A total of 5229 participants died, 3194 from CRC. Cox regression revealed significant associations between former [hazard ratio (HR)=1.12; 95 % confidence interval (CI)=1.04-1.20] and current smoking (HR=1.29; 95% CI=1.04-1.60) and poorer overall survival compared with never smoking. Compared with current smoking, smoking cessation was associated with improved overall (HR<10 years=0.78; 95% CI=0.69-0.88; HR≥10 years=0.78; 95% CI=0.63-0.97) and CRC-specific survival (HR≥10 years=0.76; 95% CI=0.67-0.85). Conclusion: In this large meta-analysis including primary data of incident CRC patients from 14 prospective cohort studies on the association between smoking and CRC prognosis, former and current smoking were associated with poorer CRC prognosis compared with never smoking. Smoking cessation was associated with improved survival when compared with current smokers. Future studies should further quantify the benefits of nonsmoking, both for cancer prevention and for improving survival among CRC patients, in particular also in terms of treatment response.
Body Composition in Relation to Clinical Outcomes in Renal Cell Cancer : A Systematic Review and Meta-analysis
Vrieling, Alina ; Kampman, Ellen ; Knijnenburg, Nathalja C. ; Mulders, Peter F. ; Sedelaar, J.P.M. ; Baracos, Vickie E. ; Kiemeney, Lambertus A. - \ 2018
European Urology Focus 4 (2018)3. - ISSN 2405-4569 - p. 420 - 434.
Body composition - Perinephric fat - Perioperative outcomes - Recurrence - Renal cell cancer - Skeletal muscle - Survival - Toxicity - Visceral adipose tissue
Context: Several studies suggest that body composition (ie, body proportions of muscle and fat defined by computed tomography) is associated with clinical outcomes of several cancer types, including renal cell cancer (RCC). Objective: To conduct a systematic review and meta-analysis of the evidence on body composition in relation to clinical outcomes in RCC. Evidence acquisition: Literature was reviewed through October 2016 using PubMed and Embase. We included studies investigating computed tomography-measured cross-sectional areas of visceral adipose tissue (VAT), perinephric fat, subcutaneous adipose tissue (SAT), skeletal muscle index (SMI), and skeletal muscle radiodensity (SMD) in relation to perioperative outcomes, treatment toxicity, and survival in RCC patients. Evidence synthesis: We included 28 studies with a total of 6608 patients. Binary classification of body composition was used in most studies. In metastatic RCC (mRCC) patients treated with antiangiogenic drugs, dose-limiting toxicity was more frequent in patients with low versus high SMI (four studies, risk difference = 16%, 95% confidence interval [CI]: 2-31%, p = 0.03, I2 = 26%). Low versus high SMI (six studies, hazard ratio = 1.48, 95% CI: 1.08-2.03, p = 0.02, I2 = 28%) and SMD (four studies, HR = 1.56, 95% CI: 1.20-2.03, p = 0.0008, I2 = 0%) were associated with an increased risk of overall mortality in mRCC. Low versus high VAT and perinephric fat were not consistently associated with perioperative outcomes and survival. No associations for SAT were found. Conclusions: Low SMI is associated with increased dose-limiting toxicity, and low SMI and SMD are associated with increased overall mortality in mRCC. The association of VAT, perinephric fat, and SAT with clinical outcomes needs further investigation, also in localized RCC. Patient summary: We reviewed studies assessing the association of body composition with clinical outcomes in renal cell cancer. We demonstrated higher risk of dose-limiting toxicity and overall mortality for metastatic renal cell cancer patients with low versus high skeletal muscle index or skeletal muscle radiodensity, but observed inconsistent associations with visceral adipose tissue and perinephric fat. This review shows that low skeletal muscle mass is associated with increased dose-limiting toxicity and overall mortality in metastatic renal cell cancer. Visceral adipose tissue and perinephric fat were not consistently associated with clinical outcomes in renal cell cancer.
Lifestyle after Colorectal Cancer Diagnosis in Relation to Survival and Recurrence : A Review of the Literature
Zutphen, Moniek van; Kampman, Ellen ; Giovannucci, Edward L. ; Duijnhoven, Fränzel J.B. van - \ 2017
Current Colorectal Cancer Reports 13 (2017)5. - ISSN 1556-3790 - p. 370 - 401.
Alcohol - Body composition - Body mass index - Colorectal cancer - Diet - Lifestyle - Physical activity - Sedentary behavior - Smoking - Survival
Purpose of Review: This review summarizes the evidence regarding diet, physical activity, smoking, and body composition after colorectal cancer (CRC) diagnosis in relation to all-cause and CRC-specific mortality and disease recurrence and gives suggestions for future research directions. Recent Findings: Overall, this review suggests that some, albeit not all, of the well-known modifiable risk factors for cancer incidence might also be associated with CRC survival. CRC prognosis appears to be worse with increased physical inactivity, smoking, or being underweight after CRC diagnosis. Emerging evidence suggests that diets associated with a positive energy balance, e.g., high consumption of sugar-sweetened beverages, may negatively impact survival in CRC survivors. In contrast, there is currently little evidence to support the recommendation to limit red and processed meat or alcohol intake after CRC diagnosis. Whether being overweight and obese after CRC diagnosis improves or worsens CRC prognosis remains controversial and may depend on the measure used to assess body fatness. Summary: Further research on post-diagnosis lifestyle patterns is needed to understand the multifactorial influence on CRC prognosis. Disease recurrence and the development of comorbidities should be included as key outcomes in future studies and lifestyle should preferably be repeatedly measured.
Drought responses, phenotypic plasticity and survival of Mediterranean species in two different microclimatic sites
Bongers, F.J. ; Olmo, M. ; Lopez-Iglesias, B. ; Anten, N.P.R. ; Villar, R. - \ 2017
Plant Biology 19 (2017)3. - ISSN 1435-8603 - p. 386 - 395.
Cistus - Leaf traits - Photosynthesis - Quercus - SLA - Slope orientations - Survival - Water potential

Climate models predict a further drying of the Mediterranean summer. One way for plant species to persist during such climate changes is through acclimation. Here, we determine the extent to which trait plasticity in response to drought differs between species and between sites, and address the question whether there is a trade-off between drought survival and phenotypic plasticity. Throughout the summer we measured physiological traits (photosynthesis - Amax, stomatal conductance - gs, transpiration - E, leaf water potential - ψl) and structural traits (specific leaf area - SLA, leaf density - LD, leaf dry matter content - LDMC, leaf relative water content - LRWC) of leaves of eight woody species in two sites with slightly different microclimate (north- versus south-facing slopes) in southern Spain. Plant recovery and survival was estimated after the summer drought period. We found high trait variability between species. In most variables, phenotypic plasticity was lower in the drier site. Phenotypic plasticity of SLA and LDMC correlated negatively with drought survival, which suggests a trade-off between them. On the other hand, high phenotypic plasticity of SLA and LDMC was positively related to traits associated with rapid recovery and growth after the drought period. Although phenotypic plasticity is generally seen as favourable during stress conditions, here it seemed beneficial for favourable conditions. We propose that in environments with fluctuating drought periods there can be a trade-off between drought survival and growth during favourable conditions. When climate become drier, species with high drought survival but low phenotypic plasticity might be selected for.

Mortality in patients with rheumatoid arthritis : a 15-year prospective cohort study
Hoek, J. van den; Boshuizen, H.C. ; Roorda, L.D. ; Tijhuis, G.J. ; Nurmohamed, M.T. ; Bos, G.A.M. van den; Dekker, J. - \ 2017
Rheumatology International 37 (2017)4. - ISSN 0172-8172 - p. 487 - 493.
Cause of death - Cohort study - Comorbidity - Longitudinal studies - Mortality - Rheumatoid arthritis - Survival
The aim of this study was to investigate (a) the mortality in a clinical cohort of patients with established rheumatoid arthritis in comparison with the general Dutch population over 15 years, (b) the trend in the mortality ratio during the study period, and (c) causes of death and compare these with the general population. In 1997, a sample of 1222 patients was randomly selected from the register of a large rheumatology outpatient clinic. Their mortality and primary causes of death between 1997 and 2012 were obtained from Statistics Netherlands. The standardized mortality ratio (SMR) for all-cause mortality and the number of life-years lost in the study period, adjusted for age, sex, and calendar year, were calculated. A linear poisson regression analysis was performed to evaluate change in all-cause SMR over time. Finally, the SMRs for cause-specific mortality were calculated. The mean age of the population at baseline was 60.4 (SD 15.4) years, and 72.6% of the patients were women. The estimated SMR (95% CI) for all-cause mortality was 1.54 (1.41, 1.67) with about one life-year lost over the study period. There was a trend to decreasing SMR (2% annually, p = .07). Mortality was higher compared with the general population for circulatory system diseases, respiratory system diseases, musculoskeletal system diseases, and digestive system diseases (p <.05). The observed mortality among patients with RA was 54% higher than in the general population after adjustment for age, sex and calendar year. More than one life-year was lost over 15 years, and the mortality tended to decrease over time. The mortality was higher for cardiovascular, respiratory, musculoskeletal and digestive diseases.
Genetic variants determining survival and fertility in an adverse African environment: A population-based large-scale candidate gene association study
Koopman, Jacob J.E. ; Pijpe, Jeroen ; Böhringer, Stefan ; Bodegom, David van; Eriksson, Ulrika K. ; Sanchez-Faddeev, Hernando ; Ziem, Juventus B. ; Zwaan, Bas ; Eline Slagboom, P. ; Knijff, Peter de; Westendorp, Rudi G.J. - \ 2016
Aging-US 8 (2016)7. - ISSN 1945-4589 - p. 1364 - 1383.
Africa - Aging - Evolution - Fertility - Gene - Human - Life history - SNP - Survival

Human survival probability and fertility decline strongly with age. These life history traits have been shaped by evolution. However, research has failed to uncover a consistent genetic determination of variation in survival and fertility. As an explanation, such genetic determinants have been selected in adverse environments, in which humans have lived during most of their history, but are almost exclusively studied in populations in modern affluent environments. Here, we present a large-scale candidate gene association study in a rural African population living in an adverse environment. In 4387 individuals, we studied 4052 SNPs in 148 genes that have previously been identified as possible determinants of survival or fertility in animals or humans. We studied their associations with survival comparing newborns, middle-age adults, and old individuals. In women, we assessed their associations with reported and observed numbers of children. We found no statistically significant associations of these SNPs with survival between the three age groups nor with women's reported and observed fertility. Population stratification was unlikely to explain these results. Apart from a lack of power, we hypothesise that genetic heterogeneity of complex phenotypes and gene -environment interactions prevent the identification of genetic variants explaining variation in survival and fertility in humans.

Effect of a long-term high-protein diet on survival, obesity development, and gut microbiota in mice
Kiilerich, Pia ; Myrmel, Lene Secher ; Fjære, Even ; Hao, Qin ; Hugenholtz, Floor ; Sonne, Si Brask ; Derrien, Muriel ; Pedersen, Lone Møller ; Petersen, Rasmus Koefoed ; Mortensen, Alicja ; Licht, Tine Rask ; Rømer, Maria Unni ; Vogel, Ulla Birgitte ; Waagbø, Linn Jeanette ; Giallourou, Natasa ; Feng, Qiang ; Xiao, Liang ; Liu, Chuan ; Liaset, Bjørn ; Kleerebezem, Michiel ; Wang, Jun ; Madsen, Lise ; Kristiansen, Karsten - \ 2016
American Journal of Physiology. Endocrinology and Metabolism 310 (2016)11. - ISSN 0193-1849 - p. E886 - E899.
Gut microbiota - High-fat diet - High-protein diet - Obesity - Survival

Female C57BL/6J mice were fed a regular low-fat diet or high-fat diets combined with either high or low protein-to-sucrose ratios during their entire lifespan to examine the long-term effects on obesity development, gut microbiota, and survival. Intake of a high-fat diet with a low protein/sucrose ratio precipitated obesity and reduced survival relative to mice fed a low-fat diet. By contrast, intake of a high-fat diet with a high protein/sucrose ratio attenuated lifelong weight gain and adipose tissue expansion, and survival was not significantly altered relative to low-fat-fed mice. Our findings support the notion that reduced survival in response to high-fat/high-sucrose feeding is linked to obesity development. Digital gene expression analyses, further validated by qPCR, demonstrated that the protein/sucrose ratio modulated global gene expression over time in liver and adipose tissue, affecting pathways related to metabolism and inflammation. Analysis of fecal bacterial DNA using the Mouse Intestinal Tract Chip revealed significant changes in the composition of the gut microbiota in relation to host age and dietary fat content, but not the protein/sucrose ratio. Accordingly, dietary fat rather than the protein/sucrose ratio or adiposity is a major driver shaping the gut microbiota, whereas the effect of a high-fat diet on survival is dependent on the protein/sucrose ratio.

From artificial structures to self-sustaining oyster reefs
Walles, B. ; Troost, K. ; Ende, D. van den; Nieuwhof, S. ; Smaal, A.C. ; Ysebaert, T. - \ 2016
Journal of Sea Research 108 (2016). - ISSN 1385-1101 - p. 1 - 9.
Artificial reefs - Crassostrea gigas - Growth - Oyster reefs - Recruitment - Survival - Tidal emersion

Coastal ecosystems are increasingly recognized as essential elements within coastal defence schemes and coastal adaptation. The capacity of coastal ecosystems, like marshes and oyster reefs, to maintain their own habitat and grow with sea-level rise via biophysical feedbacks is seen as an important advantage of such systems compared to man-made hard engineering structures.Providing a suitable substrate for oysters to settle on offers a kick-start for establishment at places where they were lost or are desirable for coastal protection. Accumulation of shell material, through recruitment and growth, is essential to the maintenance of oyster reefs as it provides substrate for new generations (positive feedback loop), forming a self-sustainable structure. Insight in establishment, survival and growth thresholds and knowledge about the population dynamics are necessary to successfully implement oyster reefs in coastal defence schemes.The aim of this paper is to investigate whether artificial Pacific oyster reefs develop into self-sustaining oyster reefs that contribute to coastal protection. Reef development was investigated by studying recruitment, survival and growth rates of oysters on artificial oyster reefs in comparison with nearby natural Pacific oyster reefs. The artificial reef structure successfully offered substrate for settlement of oysters and therefore stimulated reef formation. Reef development, however, was hampered by local sedimentation and increasing tidal emersion. Tidal emersion is an important factor that can be used to predict where artificial oyster reefs have the potential to develop into self-sustaining reefs that could contribute to coastal protection, but it is also a limiting factor in using oyster reefs for coastal protection.

Survival and Elimination of Hepatitis E Virus : A Review
Cook, Nigel ; Poel, Wim H.M. van der - \ 2015
Food and Environmental Virology 7 (2015)3. - ISSN 1867-0334 - p. 189 - 194.
Elimination - Heat - Hepatitis E virus - HEV - Pork products - Survival

Recently, foodborne transmission of hepatitis E virus (HEV) has become a concern due to the identification of undercooked pork products as a risk factor for infection. The limited number of studies which have been performed indicate that HEV could remain infectious at temperatures used in some cooking regimes, although inactivation by heating at 71 °C for 20 min has been demonstrated. There are significant gaps in our knowledge regarding the survival of HEV in foods and the environment (including food contact surfaces), and also regarding the effect of elimination procedures used in food supply chain settings. The lack of a reliable infectivity assay has hampered extensive study. It is recommended that studies be undertaken to develop an efficient propagation system (based on in vitro cell culture), to facilitate the acquisition of extensive information on the survival of HEV in food and the environment, and its response to disinfection and elimination procedures.

Genetic analysis of longevity in Dutch dairy cattle using random regression
Pelt, M.L. van; Meuwissen, T.H.E. ; Jong, G. de; Veerkamp, R.F. - \ 2015
Journal of Dairy Science 98 (2015)6. - ISSN 0022-0302 - p. 4117 - 4130.
Dairy cattle - Longevity - Random regression - Survival

Longevity, productive life, or lifespan of dairy cattle is an important trait for dairy farmers, and it is defined as the time from first calving to the last test date for milk production. Methods for genetic evaluations need to account for censored data; that is, records from cows that are still alive. The aim of this study was to investigate whether these methods also need to take account of survival being genetically a different trait across the entire lifespan of a cow. The data set comprised 112,000 cows with a total of 3,964,449 observations for survival per month from first calving until 72. mo in productive life. A random regression model with second-order Legendre polynomials was fitted for the additive genetic effect. Alternative parameterizations were (1) different trait definitions for the length of time interval for survival after first calving (1, 3, 6, and 12. mo); (2) linear or threshold model; and (3) differing the order of the Legendre polynomial. The partial derivatives of a profit function were used to transform variance components on the survival scale to those for lifespan. Survival rates were higher in early life than later in life (99 vs. 95%). When survival was defined over 12-mo intervals survival curves were smooth compared with curves when 1-, 3-, or 6-mo intervals were used. Heritabilities in each interval were very low and ranged from 0.002 to 0.031, but the heritability for lifespan over the entire period of 72. mo after first calving ranged from 0.115 to 0.149. Genetic correlations between time intervals ranged from 0.25 to 1.00. Genetic parameters and breeding values for the genetic effect were more sensitive to the trait definition than to whether a linear or threshold model was used or to the order of Legendre polynomial used. Cumulative survival up to the first 6. mo predicted lifespan with an accuracy of only 0.79 to 0.85; that is, reliability of breeding value with many daughters in the first 6. mo can be, at most, 0.62 to 0.72, and changes of breeding values are still expected when daughters are getting older. Therefore, an improved model for genetic evaluation should treat survival as different traits during the lifespan by splitting lifespan in time intervals of 6. mo or less to avoid overestimated reliabilities and changes in breeding values when daughters are getting older.

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