Fecal glucocorticoid analysis as a health monitoring tool for endangered African penguins (Spheniscus demersus)

African penguins (Spheniscus demersus) are an endangered species, with approximately 70,000 mature adults remaining in the wild. Population loss is linked to a combination of environmental and anthropogenic stressors. The aim of the study was to validate a commercially available enzyme immunoassay (EIA) to assess adrenal activity and measure the response to stressors in the feces of African penguins. Fecal samples (n = 609) were collected from 12 African penguins housed at Mystic Aquarium throughout their natural lifecycle, including breeding and molt, where measurable changes in fecal glucocorticoid metabolite (FGM) levels are predicted to occur. Fecal samples collected post-veterinary exam were used for biological validation. Longitudinal analysis shows a significant difference (p = <0.0001) between the average FGM levels during baseline and breeding season, 33.97 ± 1.30 ng/g and 50.21 ± 3.18 ng/g, respectively. Females displayed significantly higher FGM levels than males during both baseline (p = 0.0386; females = 38.80 ± 2.19 ng/g; males = 29.34 ± 1.37 ng/g) and breeding periods (p = 0.0175; females = 57.53 ± 4.84 ng/g; males = 42.69 ± 3.95 ng/g). Average FGM levels decreased significantly over the three-week molting period, from 85.40 ± 20.35 ng/g at week one to 20.23 ± 5.30 ng/g at week three. A seasonal difference in FGM levels was observed in both male and female fecal samples, with Fall having the highest average FGM levels, 54.38 ± 3.64 ng/g, and Summer the lowest, 30.87 ± 2.21 ng/g. General linear mixed model analysis determined that lifecycle (females) and visitor presence (males) were the two factors which best explained the variation in FGM levels observed, however neither factor was found to be significant. These results show FGM analysis can detect physiologically meaningful changes in endocrine activity in African penguins and can be used to monitor health for penguins in aquaria and in the wild, thus contributing to conservation efforts for the survival of the species.

Serological Detection of Marine Origin Brucella Exposure in Two Alaska Beluga Stocks

Simple Summary

Brucellosis, the disease caused by Brucella bacteria, is of emerging concern in marine-mammal populations worldwide due to its potential link to reproductive failure, yet is less well-studied than in terrestrial animals, such as cattle. To understand Brucella exposure and disease in two populations of beluga, in Bristol Bay and the eastern Chukchi Sea, Alaska, USA, this study screened animals for the presence of antibodies against the bacterium (serology), as well as tested for the direct presence of bacterial DNA or bacterial growth from tissue samples. More than half of all animals tested, from both populations, were positive for the presence of antibodies, providing evidence of exposure to Brucella. Few animals, however, were positive for the direct detection of Brucella DNA and none resulted in successful bacterial growth, suggesting a lack of active clinical disease. The high rate of exposure in these populations supports the need for long-term monitoring of beluga populations, particular those that are threatened or endangered, such as the Cook Inlet belugas.

Abstract

Among emerging threats to the Arctic is the introduction, spread, or resurgence of disease. Marine brucellosis is an emerging disease concern among free-ranging cetaceans and is less well-studied than terrestrial forms. To investigate marine-origin Brucella sp. exposure in two beluga stocks in Alaska, USA, this study used serological status as well as real-time polymerase chain reaction (rtPCR) and bacterial culture. In total, 55 live-captured–released belugas were tested for Brucella exposure in Bristol Bay (2008–2016) and 112 (8 live-captured; 104 subsistence-harvested) whales were tested in the eastern Chukchi Sea (2007–2017). In total, 73% percent of Bristol Bay live captures, 50% of Chukchi Sea live captures, and 66% of Chukchi Sea harvested belugas were positive on serology. Only 10 of 69 seropositive belugas were rtPCR positive in at least one tissue. Only one seropositive animal was PCR positive in both the spleen and mesenteric lymph node. All animals tested were culture negative. The high prevalence of seropositivity detected suggests widespread exposure in both stocks, however, the low level of rtPCR and culture positive results suggests clinical brucellosis was not prevalent in the belugas surveyed. Continued detection of Brucella exposure supports the need for long-term monitoring of these and other beluga populations.

Evaluating beluga (Delphinapterus leucas) blow samples as a potential diagnostic for immune function gene expression within the respiratory system

Evaluating respiratory health is important in the management of cetaceans, which are vulnerable to respiratory diseases. Quantifying the expression of genes related to immune function within the respiratory tract could be a valuable tool for directly assessing respiratory health. Blow (exhale) samples allow DNA analysis, and we hypothesized that RNA could also be isolated from blow samples for gene expression studies of immune function. We evaluated the potential to extract RNA from beluga blow samples and tested whether transcripts associated with immune function could be detected with endpoint polymerase chain reaction. A total of 54 blow samples were collected from clinically healthy aquarium belugas (n = 3), and 15 were collected from wild belugas temporarily restrained for health assessment in Bristol Bay, Alaska (n = 9). Although RNA yield varied widely (range, 0-265.2 ng; mean = 85.8; SD = 71.3), measurable RNA was extracted from 97% of the samples. Extracted RNA was assessed in 1-6 PCR reactions targeting housekeeping genes (Rpl8, Gapdh or ActB) or genes associated with immune function (TNFα, IL-12p40 or Cox-2). Fifty of the aquarium samples (93%) amplified at least one transcript; overall PCR success for housekeeping genes (96/110, 87%) and genes associated with immune function (90/104, 87%) were similarly high. Both RNA yield and overall PCR success (27%) were lower for wild beluga samples, which is most likely due to the reduced forcefulness of the exhale when compared with trained or free-swimming belugas. Overall, the high detection rate with PCR suggests measuring gene expression in blow samples could provide diagnostic information about immune responses within the respiratory tract. While further study is required to determine if quantitative gene expression data from blow samples is associated with disease states, the non-invasive nature of this approach may prove valuable for belugas, which face increasing anthropogenic disturbances.

Characterizing the culturable surface microbiomes of diverse marine animals

Biofilm-forming bacteria have the potential to contribute to the health, physiology, behavior and ecology of the host and serve as its first line of defense against adverse conditions in the environment. While metabarcoding and metagenomic information furthers our understanding of microbiome composition, fewer studies use cultured samples to study the diverse interactions among the host and its microbiome, as cultured representatives are often lacking. This study examines the surface microbiomes cultured from three shallow-water coral species and two whale species. These unique marine animals place strong selective pressures on their microbial symbionts and contain members under similar environmental and anthropogenic stress. We developed an intense cultivation procedure, utilizing a suite of culture conditions targeting a rich assortment of biofilm-forming microorganisms. We identified 592 microbial isolates contained within 15 bacterial orders representing 50 bacterial genera, and two fungal species. Culturable bacteria from coral and whale samples paralleled taxonomic groups identified in culture-independent surveys, including 29% of all bacterial genera identified in the Megaptera novaeangliae skin microbiome through culture-independent methods. This microbial repository provides raw material and biological input for more nuanced studies which can explore how members of the microbiome both shape their micro-niche and impact host fitness.

Variation in the hemostatic complement (C5a) responses to in vitro nitrogen bubbles in monodontids and phocids

Immune responses to nitrogen gas bubbles, particularly activation of inflammation via the complement cascade, have been linked to the development of symptoms and damage associated with decompression sickness (DCS) in humans. Marine mammals were long thought not to be susceptible to such dive-related injury, yet evidence of DCS-like injury and new models of tissue nitrogen super-saturation suggest that bubbles may routinely form. As such, it is possible that marine mammals have protective adaptations that allow them to deal with a certain level of bubble formation during normal dives, without acute adverse effects. This work evaluated the complement response, indicative of inflammation, to in vitro nitrogen bubble exposures in several marine mammal species to assess whether a less-responsive immune system serves a protective role against DCS-like injury in these animals. Serum samples from beluga (Delphinapterus leucas), and harbor seals (Phoca vitulina) (relatively shallow divers) and deep diving narwhal (Monodon monoceros), and Weddell seals (Leptonychotes weddellii) were exposed to nitrogen bubbles in vitro. Complement activity was evaluated by measuring changes in the terminal protein C5a in serum, and results suggest marine mammal complement is less sensitive to gas bubbles than human complement, but the response varies between species. Species-specific differences may be related to dive ability, and suggest moderate or shallow divers may be more susceptible to DCS-like injury. This information is an important consideration in assessing the impact of changing dive behaviors in response to anthropogenic stressors, startle responses, or changing environmental conditions that affect prey depth distributions.

Effects of health status on pressure-induced changes in phocid immune function and implications for dive ability

The ability of marine mammals to cope with environmental challenges is a key determining factor in strandings and successful release of rehabilitated animals. Dive behavior is related to foraging and thus survival. While dive adaptations have been well studied, it is unknown how the immune system responds to diving and whether health status impacts immune function during diving. This study investigated the functional response of ex situ immune cells from stranded phocids to in vitro increased pressure, over the course of rehabilitation. Blood samples were drawn from stranded harbor seals (Phoca vitulina), gray seals (Halichoerus grypus) and harp seals (Phoca groenlandica) at the time of admit to the Mystic Aquarium, Mystic, CT and again after rehabilitation (pre-release). Phagocytosis, lymphocyte proliferation and immune cell activation were measured in vitro, with and without exposure to 2000 psi (simulated dive depth of 1360 m). Plasma epinephrine and norepinephrine, and serum cortisol were measured in vivo. All hormone values decreased between admit and release conditions. Under admit or release conditions, pressure exposures resulted in significant changes in granulocyte and monocyte phagocytosis, granulocyte expression of CD11b and lymphocyte expression of the IL2 receptor (IL2R). Overall, pressure exposures resulted in decreased phagocytosis for admit conditions, but increased phagocytosis in release samples. Expression of leukocyte activation markers, CD11b and IL2R, increased and the response did not differ between admit and release samples. Specific hematological and serum chemistry values also changed significantly between admit and release and were significantly correlated with pressure-induced changes in immune function. Results suggest (1) dive duration affects the response of immune cells, (2) different white blood cell types respond differently to pressure and (3) response varies with animal health. This is the first study describing the relationship between diving, immune function and health status in phocids.

Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.

Behavioral responses of beluga whales (Delphinapterus leucas) to environmental variation in an Arctic estuary

Some Arctic estuaries serve as substrate rubbing sites for beluga whales (Delphinapterus leucas) in the summer, representing a specialized resource for the species. Understanding how environmental variation affects the species' behavior is essential to management of these habitats in coming years as the climate changes. Spatiotemporal and environmental variables were recorded for behavioral observations, during which focal groups of whales in an estuary were video-recorded for enumeration and behavioral analysis. Multiple polynomial linear regression models were optimized to identify the effects of spatiotemporal and environmental conditions on group size, composition, and the frequency of behaviors being performed. Results suggest that belugas take advantage of environmental variation to express behaviors that 1) protect young, e.g., bringing calves close to shore during cloudier days, obscuring visualization from terrestrial predators; 2) avoid predation, e.g., rubbing against substrates at higher Beaufort sea states to obscure visualization, and resting during low tides while swimming on outgoing tides to avoid stranding; and 3) optimize bioenergetic resources, e.g., swimming during lower Beaufort sea states and clearer days. Predictive models like the ones presented in this study can inform conservation management strategies as environmental conditions change in future years.

Testosterone and progesterone concentrations in blow samples are biologically relevant in belugas (Delphinapterus leucas)

Steroid hormone analysis in blow (respiratory vapor) may provide a minimally invasive way to assess the reproductive status of wild cetaceans. Biological validation of the method is needed to allow for the interpretation of hormone measurements in blow samples. Utilizing samples collected from trained belugas (Delphinapterus leucas, n=20), enzyme immunoassays for testosterone and progesterone were validated for use with beluga blow samples. Testosterone concentrations in 40 matched blood and blow samples collected from 4 male belugas demonstrated a positive correlation (R²=0.52, p<0.0001). Progesterone concentrations in 64 matching blood and blow samples from 11 females were also positively correlated (R²=0.60, p<0.0001). Testosterone concentrations (mean±SD) in blow samples collected from adult males (119.3±14.2pg/ml) were higher (p<0.01) than that of a juvenile male (<8years) (59.4±6.5pg/ml) or female belugas (54.1±25.7pg/ml). Among adult males, testosterone concentrations in blow demonstrated a seasonal pattern of secretion, with peak secretion occurring during the breeding season (February-April, 136.95±33.8pg/ml). Progesterone concentrations in blow varied by reproductive status; pregnant females (410.6±87.8pg/ml) and females in the luteal phase of the estrous cycle (339.5±51.0pg/ml) had higher (p<0.0001) blow progesterone concentrations than non-pregnant females without a corpus luteum (242.5±27.3pg/ml). Results indicate that blow sample analysis can be used to detect variation in reproductive states associated with large differences in circulating testosterone or progesterone in belugas.

The environment as a driver of immune and endocrine responses in dolphins (Tursiops truncatus)

Immune and endocrine responses play a critical role in allowing animals to adjust to environmental perturbations. We measured immune and endocrine related markers in multiple samples from individuals from two managed-care care dolphin groups (n = 82 samples from 17 dolphins and single samples collected from two wild dolphin populations: Indian River Lagoon, (IRL) FL (n = 26); and Charleston, (CHS) SC (n = 19). The immune systems of wild dolphins were more upregulated than those of managed-care-dolphins as shown by higher concentrations of IgG and increases in lysozyme, NK cell function, pathogen antibody titers and leukocyte cytokine transcript levels. Collectively, managed-care care dolphins had significantly lower levels of transcripts encoding pro-inflammatory cytokine TNF, anti-viral MX1 and INFα and regulatory IL-10. IL-2Rα and CD69, markers of lymphocyte activation, were both lower in managed-care care dolphins. IL-4, a cytokine associated with TH2 activity, was lower in managed-care care dolphins compared to the free-ranging dolphins. Differences in immune parameters appear to reflect the environmental conditions under which these four dolphin populations live which vary widely in temperature, nutrition, veterinary care, pathogen/contaminant exposures, etc. Many of the differences found were consistent with reduced pathogenic antigenic stimulation in managed-care care dolphins compared to wild dolphins. Managed-care care dolphins had relatively low TH2 lymphocyte activity and fewer circulating eosinophils compared to wild dolphins. Both of these immunologic parameters are associated with exposure to helminth parasites which is uncommon in managed-care care dolphins. Less consistent trends were observed in a suite of hormones but significant differences were found for cortisol, ACTH, total T4, free T3, and epinephrine. While the underlying mechanisms are likely multiple and complex, the marked differences observed in the immune and endocrine systems of wild and managed-care care dolphins appear to be shaped by their environment.

Pressure Induced Changes in Adaptive Immune Function in Belugas (Delphinapterus leucas); Implications for Dive Physiology and Health

Increased pressure, associated with diving, can alter cell function through several mechanisms and has been shown to impact immune functions performed by peripheral blood mononuclear cells (PBMC) in humans. While marine mammals possess specific adaptations which protect them from dive related injury, it is unknown how their immune system is adapted to the challenges associated with diving. The purpose of this study was to measure PBMC activation (IL2R expression) and Concanavalin A induced lymphocyte proliferation (BrdU incorporation) in belugas following in vitro pressure exposures during baseline, Out of Water Examination (OWE) and capture/release conditions. Beluga blood samples (n = 4) were obtained from animals at the Mystic Aquarium and from free ranging animals in Alaska (n = 9). Human blood samples (n = 4) (Biological Specialty Corporation) were run for comparison. In vivo catecholamines and cortisol were measured in belugas to characterize the neuroendocrine response. Comparison of cellular responses between controls and pressure exposed cells, between conditions in belugas, between belugas and humans as well as between dive profiles, were run using mixed generalized linear models (α = 0.05). Cortisol was significantly higher in Bristol Bay belugas and OWE samples as compared with baseline for aquarium animals. Both IL2R expression and proliferation displayed significant pressure induced changes, and these responses varied between conditions in belugas. Both belugas and humans displayed increased IL2R expression, while lymphocyte proliferation decreased for aquarium animals and increased for humans and Bristol Bay belugas. Results suggest beluga PBMC function is altered during diving and changes may represent dive adaptation as the response differs from humans, a non-dive adapted mammal. In addition, characteristics of a dive (i.e., duration, depth) as well as neuroendocrine activity can alter the response of beluga cells, potentially impacting the ability of animals to fight infection or avoid dive related pathologies.

Beluga (Delphinapterus leucas) granulocytes and monocytes display variable responses to in vitro pressure exposures

While it is widely known that marine mammals possess adaptations which allow them to make repetitive and extended dives to great depths without suffering ill effects seen in humans, the response of marine mammal immune cells to diving is unknown. Renewed interest in marine mammal dive physiology has arisen due to reports of decompression sickness-like symptoms and embolic damage in stranded and by-caught animals, and there is concern over whether anthropogenic activities can impact marine mammal health by disrupting adaptive dive responses and behavior. This work addresses the need for information concerning marine mammal immune function during diving by evaluating granulocyte and monocyte phagocytosis, and granulocyte activation in belugas (n = 4) in comparison with humans (n = 4), with and without in vitro pressure exposures. In addition, the potential for additional stressors to impact immune function was investigated by comparing the response of beluga cells to pressure between baseline and stressor conditions. Granulocyte and monocyte phagocytosis, as well as granulocyte activation, were compared between pressure exposed and non-exposed cells for each condition, between different pressure profiles and between conditions using mixed generalized linear models (α = 0.05). The effects of pressure varied between species as well by depth, compression/decompression rates, and length of exposures, and condition for belugas. Pressure induced changes in granulocyte and monocyte function in belugas could serve a protective function against dive-related pathologies and differences in the response between humans and belugas could reflect degrees of dive adaptation. The alteration of these responses during physiologically challenging conditions may increase the potential for dive-related in jury and disease in marine mammals.

Blow collection as a non-invasive method for measuring cortisol in the beluga (Delphinapterus leucas)

Non-invasive sampling techniques are increasingly being used to monitor glucocorticoids, such as cortisol, as indicators of stressor load and fitness in zoo and wildlife conservation, research and medicine. For cetaceans, exhaled breath condensate (blow) provides a unique sampling matrix for such purposes. The purpose of this work was to develop an appropriate collection methodology and validate the use of a commercially available EIA for measuring cortisol in blow samples collected from belugas (Delphinapterus leucas). Nitex membrane stretched over a petri dish provided the optimal method for collecting blow. A commercially available cortisol EIA for measuring human cortisol (detection limit 35 pg ml-1) was adapted and validated for beluga cortisol using tests of parallelism, accuracy and recovery. Blow samples were collected from aquarium belugas during monthly health checks and during out of water examination, as well as from wild belugas. Two aquarium belugas showed increased blow cortisol between baseline samples and 30 minutes out of water (Baseline, 0.21 and 0.04 µg dl-1; 30 minutes, 0.95 and 0.14 µg dl-1). Six wild belugas also showed increases in blow cortisol between pre and post 1.5 hour examination (Pre 0.03, 0.23, 0.13, 0.19, 0.13, 0.04 µg dl-1, Post 0.60, 0.31, 0.36, 0.24, 0.14, 0.16 µg dl-1). Though this methodology needs further investigation, this study suggests that blow sampling is a good candidate for non-invasive monitoring of cortisol in belugas. It can be collected from both wild and aquarium animals efficiently for the purposes of health monitoring and research, and may ultimately be useful in obtaining data on wild populations, including endangered species, which are difficult to handle directly.

Stress response of wild bottlenose dolphins (Tursiops truncatus) during capture-release health assessment studies

There is a growing concern about the impacts of stress in marine mammals as they face a greater array of threats. The stress response of free-ranging dolphins (Tursiops truncatus) was examined by measuring their physiologic response to capture and handling. Samples were collected from 168 dolphins during capture-release health assessments 2003-2007 at two study sites: Charleston, SC (CHS) and the Indian River Lagoon, FL (IRL). Adrenocorticotropic hormone (ACTH), cortisol, aldosterone (ALD) and catecholamines (epinephrine (EPI), norepinephrine (NOR), dopamine (DA)), were measured in blood and cortisol in urine. Mean time to collect pre-examination samples after netting the animals was 22min; post-examination samples were taken prior to release (mean 1h 37min). EPI and DA concentrations decreased significantly with increased time to blood sampling. ACTH and cortisol levels increased from the initial capture event to the post-examination sample. EPI concentrations increased significantly with increasing time to the pre-examination sample and decreased significantly with time between the pre- and post-examination sample. Cortisol concentrations increased between the pre- and post-examination in CHS dolphins. Age- and sex-adjusted mean pre-examination values of catecholamines were significantly higher in CHS dolphins; ALD was higher in IRL dolphins. Significant differences related to age or sex included higher NOR concentrations in males; higher ALD and urine cortisol levels in juveniles than adults. Wild dolphins exhibited a typical mammalian response to acute stress of capture and restraint. Further studies that relate hormone levels to biological and health endpoints are warranted.

Clinicoimmunopathologic findings in Atlantic bottlenose dolphins Tursiops truncatus with positive Chlamydiaceae antibody titers

Sera from free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL), Florida, and coastal waters of Charleston (CHS), South Carolina, USA, were tested for antibodies to Chlamydiaceae as part of a multidisciplinary study of individual and population health. A suite of clinicoimmunopathologic variables was evaluated in Chlamydiaceae-seropositive dolphins (n = 43) and seronegative healthy dolphins (n = 83). Fibrinogen, lactate dehydrogenase, amylase, and absolute numbers of neutrophils, lymphocytes, and basophils were significantly higher, and serum bicarbonate, total alpha globulin, and alpha-2 globulin were significantly lower in dolphins with positive Chlamydiaceae titers compared with seronegative healthy dolphins. Several differences in markers of innate and adaptive immunity were also found. Concanavalin A-induced T lymphocyte proliferation, lipopolysaccharide-induced B lymphocyte proliferation, and granulocytic phagocytosis were significantly lower, and absolute numbers of mature CD 21 B lymphocytes, natural killer cell activity and lysozyme concentration were significantly higher in dolphins with positive Chlamydiaceae antibody titers compared to seronegative healthy dolphins. Additionally, dolphins with positive Chlamydiaceae antibody titers had significant increases in ELISA antibody titers to Erysipelothrix rhusiopathiae. These data suggest that Chlamydiaceae infection may produce subclinical clinicoimmunopathologic perturbations that impact health. Any potential subclinical health impacts are important for the IRL and CHS dolphin populations, as past studies have indicated that both dolphin populations are affected by other complex infectious and neoplastic diseases, often associated with immunologic perturbations and anthropogenic contaminants.

Episodic and semantic components of autobiographical memories and imagined future events in post-traumatic stress disorder

Individuals with post-traumatic stress disorder (PTSD) tend to retrieve autobiographical memories with less episodic specificity, referred to as overgeneralised autobiographical memory. In line with evidence that autobiographical memory overlaps with one's capacity to imagine the future, recent work has also shown that individuals with PTSD also imagine themselves in the future with less episodic specificity. To date most studies quantify episodic specificity by the presence of a distinct event. However, this method does not distinguish between the numbers of internal (episodic) and external (semantic) details, which can provide additional insights into remembering the past and imagining the future. This study employed the Autobiographical Interview (AI) coding scheme to the autobiographical memory and imagined future event narratives generated by combat veterans with and without PTSD. Responses were coded for the number of internal and external details. Compared to combat veterans without PTSD, those with PTSD generated more external than internal details when recalling past or imagining future events, and fewer internal details were associated with greater symptom severity. The potential mechanisms underlying these bidirectional deficits and clinical implications are discussed.

Overgeneralized autobiographical memory and future thinking in combat veterans with posttraumatic stress disorder

BACKGROUND

Studies show that individuals with Posttraumatic Stress Disorder (PTSD) tend to recall autobiographical memories with decreased episodic specificity. A growing body of research has demonstrated that the mechanisms involved in recalling autobiographical memories overlap considerably with those involved in imagining the future. Although shared autobiographical deficits in remembering the past and imagining the future have been observed in other clinical populations, this has yet to be examined in PTSD. This study examined whether, compared to combat trauma-exposed individuals without PTSD, those with combat-related PTSD would be more likely to generate overgeneralized autobiographical memories and imagined future events.

METHOD

Operation Enduring/Iraqi Freedom (OEF/OIF) veterans with and without PTSD were presented with neutral word cues and were instructed to generate memories or imagine future autobiographical events. Responses were digitally recorded and were coded for level of episodic specificity and content related to combat trauma.

RESULTS

Individuals with PTSD were more likely to generate overgeneral autobiographical memories and future events than individuals without PTSD, and were more likely to incorporate content associated with combat when remembering the past or thinking about the future.

LIMITATION

Limitations of the study include a cross-sectional design, precluding causality; the lack of a non-trauma exposed group, relatively small sample, and almost all-male gender of participants, limiting the generalizability to other populations.

CONCLUSION

These findings suggest that individuals with PTSD show similar deficits when generating personal past and future events, which may represent a previously unexamined mechanism involved in the maintenance of PTSD symptoms.

Neuroimmunological response of beluga whales (Delphinapterus leucas) to translocation and a novel social environment

This study assessed changes in phagocyte function and activation of the sympatho-adrenal medullary and hypothalamo-pituitary adrenal axes of beluga whales (Delphinapterus leucas) in response to translocation and introduction to a novel social environment. Transported belugas exhibited increases in epinephrine (E), norepinephrine (NE), and cortisol levels in response to the translocation process. In response to the introduction of the transported belugas, resident belugas exhibited an increase in E and NE but not cortisol. Moreover, the increase in E and NE shown by the transported belugas was significantly greater than the increase exhibited by the resident belugas. Resident belugas exhibited a concomitant decrease in neutrophil and monocyte phagocytosis associated with the introduction of the transported belugas. In contrast, transported belugas exhibited an attendant increase in phagocytosis and respiratory burst activity immediately following transport. Differences in phagocyte response may derive from differences in hormonal milieu, stressor modality and/or intensity, or phagocyte priming. Investigating the complex interactions between types of stressors, neuroendocrine response, and immunocompetence will lead to a better understanding of the impacts of environmental challenges, including anthropogenic perturbations, on the health of cetacean populations.

Clinicoimmunopathologic findings in Atlantic bottlenose dolphins Tursiops truncatus with positive cetacean morbillivirus antibody titers

Sera from free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL), Florida were tested for antibodies to cetacean morbilliviruses from 2003 to 2007 as part of a multidisciplinary study of individual and population health. A suite of clinicoimmunopathologic variables were evaluated in morbillivirus-seropositive dolphins (n = 14) and seronegative healthy dolphins (n = 49). Several important differences were found. Serum alkaline phosphatase, creatine phosphokinase, chloride, albumin and albumin/globulin ratios were significantly lower in seropositive dolphins. Innate immunity appeared to be upregulated with significant increases in lysozyme concentration and marginally significant increases in monocytic phagocytosis. Adaptive immunity was also impacted in dolphins with positive morbillivirus antibody titers. Mitogen-induced T lymphocyte proliferation responses were significantly reduced in dolphins with positive morbillivirus antibody titers, and marginally significant decreases were found for absolute numbers of CD4+ lymphocytes. The findings suggest impairment of cell-mediated adaptive immunity, similar to the immunologic pattern reported with acute morbillivirus infection in other species. In contrast, dolphins with positive morbillivirus antibody titers appeared to have at least a partially upregulated humoral immune response with significantly higher levels of gamma globulins than healthy dolphins, which may represent an antibody response to morbillivirus infection or other pathogens. These data suggest that subclinical dolphin morbillivirus infection in IRL dolphins may produce clinicoimmunopathologic perturbations that impact overall health.

Evaluation of an alternative to feeding whole frozen fish in belugas (Delphinapterus leucas)

Feeding fish to captive piscivores can be challenging owing to cost, availability, variability in nutrient, and caloric composition, as well as handling and storage concerns. This trial evaluated the response of three belugas to being fed Fish Analog, an alternative to frozen fish. Body condition, gut transit time, serum chemistry and metabolic hormone analytes, immune function, and behavioral motivation were the dependent variables. Belugas (n=3) were fed various levels of Fish Analog (0-50%) over a 6-month period, and follow-up studies were conducted to further examine several dependent variables. When provided in gradually increasing amounts, belugas consumed the Fish Analog, with only minor fecal consistency changes and without behavioral responses indicative of gastric discomfort. Axillary girth and blubber thickness were positively correlated, and did not differ significantly with changes in the percentage of Fish Analog fed. Individual animal variation in initial passage time, some serum chemistry analytes, and immune function differences were noted following feeding of Fish Analog. Feeding Fish Analog reduced blood n9 fatty acids compared with captive belugas fed no Fish Analog. Feeding a DHA-enriched Fish Analog increased several n3 fatty acids, including eicosapentaenoic acid, but not DHA, compared with whales fed no Fish Analog or non-DHA-enriched Fish Analog. Fish Analog was shown to be a viable alternative to feeding fish at up to 50% of the dietary caloric density.

Sampling the skin transcriptome of the North Atlantic right whale

As an initial step in defining the transcriptome of the North Atlantic right whale (Eubalaena glacialis) and developing functional genomic tools to study right whale health at the molecular physiological level, a cDNA library has been constructed from a skin biopsy. 2496 randomly selected clones (expressed sequence tags, ESTs) have been sequenced, and genes identified as important in the response to stress and immune challenges have been cloned by targeted RT-PCR from skin cDNA. The analysis of the EST collection (archived at www.marinegenomics.org and GenBank) showed a 34.79% redundancy, yielding 1578 unigenes and 27 potential microsatellite markers. 96 genes were cloned by targeted PCR; moreover, 52 of these genes are stress and immune function related. A Gene Ontology analysis of the unigene collection indicates that the skin is a rich source of expressed genes with diverse functions, suggesting an important role in multiple physiological processes including those related to immunity and stress response.

Immune dysfunction in Atlantic bottlenose dolphins (Tursiops truncatus) with lobomycosis

Lobomycosis (Lacaziosis) occurs only in humans and dolphins under natural conditions. We evaluated the immune status of eight dolphins with lobomycosis and 40 healthy dolphins from the Indian River Lagoon (IRL), Florida. Lobomycosis cases had multiple abnormalities in their immunologic parameters when compared to healthy dolphins. The absolute number of circulating lymphocytes and serum albumin concentration were reduced (P<0.05) while the segmented neutrophils, alpha 1, total beta, total gamma and total globulins were increased (P<0.05). Although innate immunity was relatively intact and phagocytosis and natural killer cell activity were not affected, the plasma lysozyme concentrations were elevated in dolphins with lobomycosis (P<0.05). Adaptive immunity was depressed with statistically significant decreases found in the absolute numbers of CD4(+) helper T cells and CD19(+) and CD21(+) B cells. The ratios of CD2(+) T cells to CD4(+) cells and CD2(+) to CD21(+) cells were increased (P=0.05 and P<0.05, respectively) and the numbers of lymphocytes expressing MHC class II molecules was decreased in dolphins with lobomycosis (P<0.05). Lymphocyte proliferation was reduced in response to stimulation with lipopolysaccharide and concanavalin A (P<0.05). Antibody titers to Erysipelas rhusiopathiae, a common marine micro-organism, were decreased (P<0.05). In summary, dolphins with lobomycosis exhibit significant impairment in adaptive immunity.

Characterization of the immunoglobulin A heavy chain gene of the Atlantic bottlenose dolphin (Tursiops truncatus)

Immunoglobulin constant region heavy chain genes of the dolphin (Tursiops truncatus) have been described for IgM and IgG but not for IgA. Here, the heavy chain sequence of dolphin IgA has been cloned and sequenced as cDNA. RT-PCR amplification from blood peripheral lymphocytes was carried out using degenerate primers and a single sequence was detected. The inferred heavy chain structure shows conserved features typical of mammalian IgA heavy chains, including three constant (C) regions, a hinge region between constant region domain 1 (C1) and constant region domain 2 (C2), and conserved residues for interaction with the Fc alpha R1 and N-glycosylation sites. Comparisons of the deduced amino acid sequences of the IgA heavy chain for the dolphin and the evolutionarily related artiodactyl species showed high similarity. In cattle and sheep, as in dolphins, a single IgA subclass has been identified. Southern blot analysis as well as genomic PCR confirmed the presence of multiple IGHA sequences suggesting that IGHA pseudogenes may be present in the dolphin genome.

A dolphin peripheral blood leukocyte cDNA microarray for studies of immune function and stress reactions

A microarray focused on stress response and immune function genes of the bottlenosed dolphin has been developed. Random expressed sequence tags (ESTs) were isolated and sequenced from two dolphin peripheral blood leukocyte (PBL) cDNA libraries biased towards T- and B-cell gene expression by stimulation with IL-2 and LPS, respectively. A total of 2784 clones were sequenced and contig analysis yielded 1343 unigenes (archived and annotated at ). In addition, 52 dolphin genes known to be important in innate and adaptive immune function and stress responses of terrestrial mammals were specifically targeted, cloned and added to the unigene collection. The set of dolphin sequences printed on a cDNA microarray comprised the 1343 unigenes, the 52 targeted genes and 2305 randomly selected (but unsequenced) EST clones. This set was printed in duplicate spots, side by side, and in two replicates per slide, such that the total number of features per microarray slide was 19,200, including controls. The dolphin arrays were validated and transcriptomic profiles were generated using PBL from a wild dolphin, a captive dolphin and dolphin skin cells. The results demonstrate that the array is a reproducible and informative tool for assessing differential gene expression in dolphin PBL and in other tissues.

The Immunoglobulin G Heavy Chain (IGHG) genes of the Atlantic bottlenose dolphin, Tursiops truncatus

Dolphin Immunoglobulin G Heavy Chain (IGHG) sequences were obtained by PCR amplification of cDNA from peripheral blood leukocytes using degenerate primers. Analysis of full-length sequences indicated the presence of two expressed isotypes, IGHG1 and IGHG2 that differ mainly in the hinge region of the molecule. Genomic Southern blot analysis indicated that the IGHG1 and IGHG2 genes are most likely present in single copies. The inferred amino acid sequences show greatest similarity between the dolphin and other closely related artiodactyl species. The genetic structure of the IGHG genes were deduced through genomic PCR and revealed that the hinge regions of both IGHG1 and IGHG2 are encoded by a single exon. The transmembrane region of the dolphin IGHG chain shows similarity to the transmembrane region of other mammalian IGHG chains with a canonical CART motif. This is in contrast to the unusual Ser to Gly substitution previously found in the dolphin IGHM transmembrane region, and the functional significance of this variation for B cell antigen-receptor dimer activation remains unknown.

Distribution of MHC II (+) cells in skin of the Atlantic bottlenose dolphin (Tursiops truncatus): an initial investigation of dolphin dendritic cells

The skin is an important tissue of the immune system; however, little is known about immune cells in dolphin skin, and very few cetacean-specific immunoreagents are available for investigative purposes. Therefore, in this study immunohistochemistry techniques were used with species-specific and non-species-specific antibodies to characterize immune cells, primarily focusing on Langerhans cells, in skin from the Atlantic bottlenose dolphin (Tursiops truncatus). An antibody to human major histocompatibility complex (MHC) class II molecules labeled cells with a dendritic-like morphology. The immunophenotype, morphology, and distribution of some of these cells are consistent with those of Langerhans cells. The cells were predominantly found in dermal papillae, primarily along the epidermal-dermal junction. Thus, the location of these cells was somewhat different from that in terrestrial mammals. Other MHC II (+) cells of varying morphology were observed deeper in the dermis, with a perivascular concentration, and had characteristics of macrophages and dermal dendritic cells. There was no immunostaining with cetacean-specific CD2 or CD21. In diseased skin, a subjective increase of MHC II (+) cells, most notably in the superficial skin layers, was associated with an ulcerative dermatitis. A few CD2 (+) cells were also present. Differences between dolphins and terrestrial mammals in terms of morphology, mechanisms of response to insult and repair, and environmental challenges may explain the modified distribution of MHC II (+) cells in dolphin skin. An elucidation of the immune cells in cetacean skin will contribute to our understanding of the evolution of functional adaptations to various environments, facilitate diagnosis of skin diseases, and define the potential for intradermal administration of vaccines and other immunotherapeutics.

Cloning of the IgM heavy chain of the bottlenose dolphin (Tursiops truncatus), and initial analysis of VH gene usage

Clones encoding the dolphin IgM heavy (micro) chain gene were isolated from a cDNA library of peripheral blood leukocytes. Genomic Southern blot analyses showed that the dolphin IGHM gene is most likely present in a single copy, and its sequence shows greatest similarity to those of the IGHM gene of the sheep, pig and cow, evolutionarily related artiodactyls. The transmembrane (TM) form of the IGHM chain was isolated by 3' RACE. While showing similarities to the TM regions of other mammalian IGHM chains, the highly conserved Ser residue of the CART motif is substituted with a Gly in the dolphin. In contrast to the pig and cow, which utilize only a single VH family, the dolphin expresses at least two distinct VH families, belonging to the mammalian VH clans I and III. At least two JH genes were identified in the dolphin. Some CDR3 regions of the dolphin VH are long (up to 21 amino acids), and contain multiple Cys residues, hypothesized to stabilize the CDR3 structure through disulfide bond formation.

The prevalence of osteopenia in pediatric renal allograft recipients varies with the method of analysis

BACKGROUND

Pediatric renal allograft recipients often suffer from osteopenia and the potential for increased fractures. Although modern densitometers are widely available, their use in children is complicated by lack of optimal interpretive criteria.

METHODS

We reviewed dual energy X-ray absorptiometry (DEXA) studies in 33 patients with functional renal allografts 4.4 +/- 3.6 years after transplantation. We interpreted our data using three previously described methods of assigning bone mineral density (BMD) Z scores.

RESULTS

BMD was directly related to age, height, weight, body surface area, and pubertal status (p < 0.001). Using gender-mixed reference data matched by chronological age, the mean BMD Z score was -0.9 +/- 1.3 vs. 0.4 +/- 1.4 when matched by height-age (p < 0.001). Height-age adjustment particularly increased the BMD Z score of pubertal adolescents. In a subset of 22 patients, gender-matched reference data led to different results from the gender-mixed reference population (mean BMD Z score 0.0 +/- 1.7 vs. -0.8 +/- 1.4, p < 0.001).

CONCLUSIONS

The perceived prevalence of osteopenia among pediatric kidney transplant recipients differs using analysis based on chronological age, height-age, or gender-matched reference data. Further studies are necessary to determine the clinical significance of measured bone density in this population.

Molecular cloning and characterization of CD4 in an aquatic mammal, the white whale Delphinapterus leucas

Given the importance of the cell surface recognition protein, CD4, in immune function, the cloning and characterization of CD4 at the molecular level from an odontocete cetacean, the white whale (Delphinapterus leucas), was carried out. Whale CD4 cDNA contains 2662 base pairs and translates into a protein containing 455 amino acids. Whale CD4 shares 64% and 51% identity with the human and mouse CD4 protein, respectively, and is organized in a similar manner. Unlike human and mouse, however, the cytoplasmic domain, which is highly conserved, contains amino acid substitutions unique to whale. Moreover, only one of the seven potential N-linked glycosylation sites present in whale is shared with human and mouse. Evolutionarily, the whale CD4 sequence is most similar to pig and structurally similar to dog and cat, in that all lack the cysteine pair in the V2 domain. These differences suggest that CD4 may have a different secondary structure in these species, which may affect binding of class II and subsequent T-cell activation, as well as binding of viral pathogens. Interestingly, as a group, species with these CD4 characteristics all have high constitutive expression of class II molecules on T lymphocytes, suggesting potential uniqueness in the interaction of CD4, class II molecules, and the immune response. Molecular characterization of CD4 in an aquatic mammal provides information on the CD4 molecule itself and may provide insight into adaptive evolutionary changes of the immune system.

Noradrenergic and peptidergic innervation of lymphoid organs in the beluga, Delphinapterus leucas: an anatomical link between the nervous and immune systems

The presence of peptidergic and noradrenergic sympathetic nerve fibers in specific compartments of both primary and secondary lymphoid organs of the rodent is well established. These nerve fibers directly contact lymphocytes and macrophages, as well as vascular and trabecular smooth muscle. We investigated the noradrenergic and neuropeptide-Y innervation of lymphoid organs in the cetacean, Delphinapterus leucas (beluga whale). The spleen, thymus, tonsil, gut-associated lymphoid tissue, and assorted lymph nodes were collected from five belugas, obtained during sanctioned hunts, and processed for catecholamine fluorescence histochemistry and for tyrosine hydroxylase and neuropeptide-Y immunocytochemistry. Innervation studies revealed fluorescent nerve fibers, tyrosine hydroxylase, and neuropeptide-Y positive nerve fibers in parenchymal lymphoid compartments, where they were closely associated with cells of the immune system, and in vascular and trabecular compartments. In lymphoid zones, tyrosine hydroxylase and neuropeptide-Y positive nerve fibers were observed in the periarteriolar lymphatic sheath and marginal zone of the spleen; in the outermost portion of the cortex, the corticomedullary zone, and medulla of the lymph nodes; in the parafollicular zones, and diffuse lymphocyte layer below the epithelium of the tonsil; in the outermost portion of some thymic lobules; and in the lamina propria of the gut. These findings are similar to those described for other mammals and substantiate an anatomical link between the nervous and immune systems in the beluga, whereby central nervous system activity may influence autonomic outflow to lymphoid organs and effect immunologic reactivity.

A microscopic investigation of the lymphoid organs of the beluga, Delphinapterus leucas

Lymphoid organs from belugas, Delphinapterus leucas, ranging in age from less than one to 16 years, were harvested during a sanctioned hunt to investigate morphology. The spleen is divisible into red and white pulp and a stroma consisting of a reticular network, a collagenous capsule, and trabeculae containing smooth muscle bundles. White pulp areas appear to be devoid of follicles and consist mainly of periarteriolar lymphatic sheaths (PALS), that are larger in younger than in older belugas. Definitive marginal zones between red and white pulp are difficult to discern in older belugas. Lymph nodes are similar to those of other mammals; they possess a follicular cortex surrounding a vascular medulla composed of lymphatic cords and sinuses. Smooth muscle is abundant in the medullary region, usually in close proximity to sinuses. The expansive nodular mass at the root of the mesentery, often referred to as the "pseudopancreas," is similar to lymph nodes in microscopic architecture. Pharyngeal tonsils and gut-associated lymphoid tissue (GALT) are found along the digestive tract and display an "active" morphology. Tonsils are comprised of lobules of follicles separated by vascular connective tissue. Epithelial-lined crypts communicate with the pharyngeal lumen. GALT consists of diffuse and follicular lymphocytes within the intestinal mucosa and submucosa. The thymus is well developed in the younger belugas, with lobules divisible into densely packed cortical zones of thymocytes and more loosely arranged medullary lymphocytes. Hassall's corpuscles are occasionally visible within the medulla. Cetaceans diverged evolutionarily from other mammals over 55 million years ago. This study investigates changes in lymphoid organ morphology in a species that now inhabits a unique ecological niche. This study also lays the groundwork for functional investigation of the beluga immune system, particularly as it relates to differences between healthy and stranded animals.

MHC class II molecules and immunoglobulins on peripheral blood lymphocytes of the bottlenosed dolphin, Tursiops truncatus

The immune system of marine mammals is of comparative interest because of its adaptation to the aquatic environment. Little information, however, is available on its cellular and molecular components. Here, we used a cross-reactive antibody to MHC class II molecules and an immunoglobulin-specific antiserum for identifying these molecular species on lymphocytes of the bottlenosed dolphin, Tursiops truncatus. Limited structural analyses indicated that class II molecules and immunoglobulins of dolphin closely resemble those of other vertebrates. In the peripheral blood of most land mammals both class II and immunoglobulins are usually found on B but not T lymphocytes. Expression of immunoglobulins on dolphin peripheral blood lymphocytes suggests a ratio of B cells to T cells comparable to that of land mammals. However, unlike the majority of land mammals, virtually 100% of the peripheral T cells display pronounced expression of class II molecules, generally considered an indication of T cell activation. It is therefore possible that the physiology of T cell activation has unusual attributes in the dolphin. It is especially interesting that some land mammals, namely swine (ungulates) and dogs and cats (carnivores), also express class II molecules on peripheral blood T lymphocytes. Since ungulates and carnivores are thought to share a common distant ancestry with toothed whales, the evolutionary history may be more relevant than the environmental history in determining these unusual attributes.

Neuropeptide-Y innervation of the rat spleen: another potential immunomodulatory neuropeptide

Neuropeptide-Y (NPY) is a 36 amino acid peptide that acts as a chemical messenger in the central and peripheral nervous systems. NPY often is found colocalized with the classical neurotransmitter norepinephrine (NE) and can potentiate the effects of this neurotransmitter postsynaptically in many systems. Using immunocytochemistry for NPY and specific lymphoid cell markers, we mapped the distribution of NPY-positive nerve fibers in the rat spleen. NPY-positive nerve fibers were present along the vasculature, trabeculae, and capsule, and also were found associated with specific lymphoid parenchymal compartments of the spleen, in close contact with lymphocytes and macrophages. These contacts were investigated further at the electron microscopic level. NPY-positive nerve terminals were found in close apposition with lymphocytes in the periarteriolar lymphatic sheath, and with lymphocytes and macrophages in the marginal zone. Previous studies have reported that postganglionic noradrenergic nerve fibers innervate specific lymphoid compartments of the rat spleen, with nerve terminals forming direct appositions with cells of the immune system. The possible colocalization of NPY and NE in these nerve fibers was investigated by chemical sympathectomy with 6-hydroxydopamine, followed by immunocytochemical labeling of NPY and tyrosine hydroxylase (TH), the rate-limiting enzyme in norepinephrine synthesis. Colocalization also was investigated by labeling for NPY with a fluorescent label, eluting the NPY, and staining for TH with diaminobenzidine as the label. These studies demonstrate that norepinephrine and NPY are colocalized in the postganglionic sympathetic nerve fibers of the rat spleen.(ABSTRACT TRUNCATED AT 250 WORDS)