Volker Stefanski

Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus)

Changes in concentration of pollutants and pathogen distribution can vary among ecotypes (e.g. marine versus terrestrial food resources). This may have important implications for the animals that reside within them. We examined 1) canid pathogen presence in an endangered arctic fox (Vulpes lagopus) population and 2) relative total mercury (THg) level as a function of ecotype (‘coastal’ or ‘inland’) for arctic foxes to test whether the presence of pathogens or heavy metal concentration correlate with population health. The Bering Sea populations on Bering and Mednyi Islands were compared to Icelandic arctic fox populations with respect to inland and coastal ecotypes. Serological and DNA based pathogen screening techniques were used to examine arctic foxes for pathogens. THg was measured by atomic absorption spectrometry from hair samples of historical and modern collected arctic foxes and samples from their prey species (hair and internal organs). Presence of pathogens did not correlate with population decline from Mednyi Island. However, THg concentration correlated strongly with ecotype and was reflected in the THg concentrations detected in available food sources in each ecotype. The highest concentration of THg was found in ecotypes where foxes depended on marine vertebrates for food. Exclusively inland ecotypes had low THg concentrations. The results suggest that absolute exposure to heavy metals may be less important than the feeding ecology and feeding opportunities of top predators such as arctic foxes which may in turn influence population health and stability. A higher risk to wildlife of heavy metal exposure correlates with feeding strategies that rely primarily on a marine based diet.

Family matters: maternal and litter-size effects on immune parameters in young laboratory rats.

A functional immune system is important for the survival of mammalian young, particularly at weaning when they lose the immunological support provided by the mothers colostrum and milk. In altricial mammals, litter size and maternal characteristics are important components of an animals early environment, which affect postnatal growth and development. In a study of unculled litters of Long-Evans laboratory rats (Rattus norvegicus), we asked whether such parameters are also associated with the immune status of the young shortly before weaning. On postnatal day 17, we assessed numbers of several leukocyte and lymphocyte subsets, the activity of the complement system, and immunoglobulin G (IgG) concentrations in the serum. Averaging the values of all pups per litter, we found negative correlations between litter size and lymphocyte counts, complement system activity and IgG concentration. Maternal effects were seen in the positive correlation between maternal postpartum body mass and granulocyte and monocyte counts. In addition, lymphocyte and monocyte counts as well as complement activity were lower for the young of multiparous than of primiparous mothers. This suggests a trend towards a better developed immune system in such offspring, which may be relevant for their immediate and long-term survival. The effects described here have potential implications for the design and interpretation of biomedical studies of immune parameters in laboratory rats.

Social confrontation in male guinea pigs: Behavior, experience, and complement activity

Because aggressive encounters are known to affect immune function in rodents, we hypothesized that individual behavior and social experience would contribute importantly to the impact of confrontation on the activity of the complement system (CA) in guinea pigs. CA was determined by lysis of Euglena gracilis cells (triggered by alternative pathway mechanisms). Males with different social experience were used: i) individually housed males (IH), ii) socially less-experienced males (LE), raised in large groups in the absence of adult animals; and iii) socially experienced males (EX) with additional fighting experience. An IH and LE male, respectively, was introduced into a group of EX residents (consisting of one male and two females). During a 26-day confrontation period the behavior of all animals was quantitatively recorded. IH and LE males showed a significant and persistent decrease in CA after confrontation (mean +/- SEM lysed cells/100 cells; IH: -16.5 +/- 4.0, LE: -16.5 +/- 3.5), whereas no significant changes from baseline were observed in EX males (-2.5 +/- 3.0). However, in social situations characterized by unstable dominance, EX males showed a lowered CA (-11.3 +/- 4.0) as well. Plasma cortisol concentrations determined in LE males were significantly elevated 4 h after confrontation but did not correlate with the long-term decrease in CA. The data indicate that the activity of the complement system can be influenced by psychosocial stressors, and suggest the importance of prior social experience for the guinea pigs ability to cope with social conflicts.

Pre-slaughter conditions influence skatole and androstenone in adipose tissue of boars

Boar taint in carcasses may vary between farms and abattoirs, although the underlying mechanisms are not yet fully understood. In the present study, 169 boars from three farms were split into two groups and slaughtered at two abattoirs. Duration of transport and the time between arrival at the abattoir and unloading (pre-unloading time) were recorded. During slaughter, blood, feces, and urine were collected to measure testosterone and cortisol levels. Carcasses were classified according to the number of skin lesions, and fat samples were taken to determine skatole, indole and androstenone levels. Androstenone in fat and testosterone in blood, feces, and urine were mainly influenced by the duration of transport. Skatole and indole concentrations were increased by both pre-unloading time and duration of transport, but were also related to skin lesions. Thus it is concluded that androstenone and skatole concentrations in fat are significantly modified by pre-slaughter conditions.

The impact of phosphorus on the immune system and the intestinal microbiota with special focus on the pig.

There is increasing interest in dietary ingredients that are appropriate to support digestive and immune functions, but also maintain a stable microbial ecosystem in the gastrointestinal tract (GIT), particularly in weaned pigs. P is an essential nutrient for both microbes and their host, as it is involved, for example, in bone formation, energy metabolism, cellular signalling and stabilisation of cell membranes. Non-ruminant animals have limited access to phytate, the main storage form of P in plant seeds. The release of P bound to phytate requires phytase activity of plant or microbial origin, resulting in the formation of variable phosphorylated inositol phosphates (InsPs). The present review focuses on interactions between variations in dietary P supply, the immune system of the host, and the intestinal microbial ecosystem. Although results on the interaction between P and the immune system are inconsistent, several studies in different species have shown a positive impact of dietary P and phytase addition on the adaptive immune response. Recent studies with pigs suggest that P supply may influence intestinal microbial composition and activity. Individual InsPs or phosphate may also affect properties of pathogenic micro-organisms, such as metabolism or virulence. In conclusion, P may be considered as part of an integrated approach to support immune functions and maintain a stable microbial ecosystem in the GIT, thereby providing a barrier against potential pathogens. Within this regard, differences in phytate-P content and intrinsic phytase activity of plant feedstuffs, as well as the formation of individual InsPs, have to be taken into account.

Influence of sampling procedure, sampling location and skin contamination on skatole and indole concentrations in adipose tissue of pigs.

Skatole leads to off-odor in pork and is influenced by several factors such as sex and management conditions of pigs, but the causal relationships have not yet been clarified. In the present study, physiological skatole concentrations along the carcass were monitored and the transdermal diffusion of skatole was experimentally studied with skatole-spiked feces. Additionally, the impact of different biopsy techniques on skatole in fat and blood was studied. Monitoring of skatole along the carcass revealed higher skatole concentrations in the belly than in dorsal cuts. Topical application of spiked feces increased skatole in fat strictly at the application site. In contrast to punch biopsies, surgical biopsies significantly affected skatole and cortisol levels in blood, but not in fat. We conclude that biopsies for skatole measurements should be taken without anesthesia from the dorsal side of the animals. Fecal contaminations on the ventral side are not likely to influence overall concentrations.

Response of Vibrio cholerae to the Catecholamine Hormones Epinephrine and Norepinephrine

UNLABELLED In Escherichia coli or Salmonella enterica, the stress-associated mammalian hormones epinephrine (E) and norepinephrine (NE) trigger a signaling cascade by interacting with the QseC sensor protein. Here we show that Vibrio cholerae, the causative agent of cholera, exhibits a specific response to E and NE. These catecholates (0.1 mM) enhanced the growth and swimming motility of V. cholerae strain O395 on soft agar in a medium containing calf serum, which simulated the environment within the host. During growth, the hormones were converted to degradation products, including adrenochrome formed by autooxidation with O2 or superoxide. In E. coli, the QseC sensor kinase, which detects the autoinducer AI-3, also senses E or NE. The genome of V. cholerae O395 comprises an open reading frame coding for a putative protein with 29% identity to E. coli QseC. Quantitative reverse transcriptase PCR (qRT-PCR) experiments revealed increased transcript levels of the qseC-like gene and of pomB, a gene encoding a structural component of the flagellar motor complex, under the influence of E or NE. Phentolamine blocks the response of E. coli QseC to E or NE. A V. cholerae mutant devoid of the qseC-like gene retained the phentolamine-sensitive motility in the presence of E, whereas NE-stimulated motility was no longer inhibited by phentolamine. Our study demonstrates that V. cholerae senses the stress hormones E and NE. A sensor related to the histidine kinase QseC from E. coli is identified and is proposed to participate in the sensing of NE. IMPORTANCE Vibrio cholerae is a Gram-negative bacterium that may cause cholera, a severe illness with high mortality due to acute dehydration caused by diarrhea and vomiting. Pathogenic V. cholerae strains possess virulence factors like the cholera toxin (CTX) and the toxin-coregulated pilus (TCP) produced in response to signals provided by the host. In pathogenic enterobacteria, the stress-associated hormones epinephrine (E) and norepinephrine (NE) of the human host act as signal molecules for the production of virulence factors and promote bacterial growth by the sequestration of iron from the host. Here we show that V. cholerae, like some enterobacteria, benefits from these stress hormones and possesses a sensor to recognize them.

Differential effect of severe and moderate social stress on blood immune and endocrine measures and susceptibility to collagen type II arthritis in male rats.

The effects of social stress on several blood immune measures and collagen-induced arthritis (CIA) were investigated in Wistar rats using the resident-intruder confrontation paradigm to induce stress of different intensity. Male intruders were exposed for one week to a dominant opponent either repeatedly for 4h daily (moderate stress) or continuously (severe stress). Arthritis was induced by intradermal injection of collagen type II (CII) into the tail skin at the end of day 3 of confrontation. Only severe stress was associated with decreased CD4 and CD8 T cells, and the increase in granulocyte numbers and body mass loss was more pronounced under these conditions. Only severe stress reduced the susceptibility to arthritis by about 50%. Severity scores did not differ in the first five days after disease onset between all groups. Subsequent experiments focused on severely stressed rats indicated that disease progressed until day 10 only in control animals, but not in severely stressed males. Stressor exposure resulted in increased blood monocyte numbers, but these males failed to accumulate macrophages into the skin at the site of CII injection. High numbers of attacks experienced by intruders correlated with delayed disease onset in severely stressed rats. We hypothesize that severe stress persisting after disease induction exhibits beneficial effects on the susceptibility of CIA and propose that the specific endocrine and immunological profile associated with severe stress is an important factor for disease outcome--a factor which probably explains many of the conflicting data of previous stress studies on CIA.

It takes two to tango: Phagocyte and lymphocyte numbers in a small mammalian hibernator.

Immunity is energetically costly and competes for resources with other physiological body functions, which may result in trade-offs that impair fitness during demanding situations. Endocrine mediators, particularly stress hormones, play a central role in these relationships and directly impact leukocyte differentials. To determine the effects of external stressors, energetic restraints and competing physiological functions on immune parameters and their relevance for fitness, we investigated leukocyte profiles during the active season of a small obligate hibernator, the edible dormouse (Glis glis), in five different study sites in south-western Germany. The highly synchronized yearly cycle of this species and the close adaptation of its life history to the irregular abundance of food resources provide a natural experiment to elucidate mechanisms underlying variations in fitness parameters. In contrast to previous studies on hibernators, that showed an immediate recovery of all leukocyte subtypes upon emergence, our study revealed that hibernation results in depleted phagocyte (neutrophils and monocytes) stores that recovered only slowly. As the phenomenon of low phagocyte counts was even more pronounced at the beginning of a low food year and primarily immature neutrophils were present in the blood upon emergence, preparatory mechanisms seem to determine the regeneration of phagocytes before hibernation is terminated. Surprisingly, the recovery of phagocytes thereafter took several weeks, presumably due to energetic restrictions. This impaired first line of defense coincides with lowest survival probabilities during the annual cycle of our study species. Reduced survival could furthermore be linked to drastic increases in the P/L ratio (phagocytes/lymphocytes), an indicator of physiological stress, during reproduction. On the other hand, moderate augmentations in the P/L ratio occurred during periods of low food availability and were associated with increased survival, but reproductive failure. In this case, the stress response probably represents an adaptive reaction that contributes to survival by activating energy resources. In contrast to our expectation, we could not detect an amplification of stress through high population densities. Summarized, results of our study clearly reveal that the leukocyte picture of active edible dormice responds sensitively to physiological conditions associated with hibernation, reproductive activity and food availability and can be linked to fitness parameters such as survival. Thus edible dormice represent an excellent model organism to investigate regulatory mechanisms of the immune system under natural conditions.

Influence of Different Housing Systems on Distribution, Function and Mitogen-Response of Leukocytes in Pregnant Sows

Simple Summary The European Union imposes housing of pregnant sows in social groups since 2013 for animal welfare reasons. Nevertheless, the consequences of different housing conditions for the immune system of pregnant sows remain poorly investigated. We therefore analyzed important aspects of blood cellular immunity and cortisol concentrations of sows either housed in individual crates or in a group during gestation. The results show that individually housed sows had lower T cell numbers, but higher cortisol concentrations. Obviously, common housing conditions can differentially affect key elements of the adaptive immune system and hormonal indicators of stress in pregnant sows. Abstract In pig production, pregnant sows are either housed in individual crates or in groups, the latter being mandatory in the EU since 2013. The consequences of different housing conditions on the immune system are however poorly investigated, although immunological alterations may have severe consequences for the animal’s health, performance, and welfare. This study assessed measures of blood celluar immunity with special emphasis on T cells in pregnant German Landrace sows either housed in individual crates or in a social group. Blood samples were taken at four samplings pre partum to evaluate numbers of lymphocyte subpopulations, mitogen-induced lymphocyte proliferation and cytokine-producing T cells. Plasma cortisol concentrations were evaluated as an indicator of stress. We found lower blood lymphocyte numbers (p < 0.01) in individually housed as opposed to group-housed sows, an effect due to lower numbers of cytotoxic T cells, naive TH cells, and CD8+ γδ-T cells. Individually housed sows showed higher cortisol concentrations (p < 0.01), whereas lymphocyte functionality did not differ between sows of both housing systems. Possible implications and underlying mechanisms for the endocrine and immunological differences are discussed. We favor the hypothesis that differences in the stressfulness of the environment contributed to the effects, with crate-housing being a more stressful environment—at least under conditions of this study.