Search

The dominant corticosteroid in elasmobranchs, 1α-hydroxycorticosterone (1α-OHB), has a described role in mineral regulation but a presumptive role in energy balance. Energy demand in vertebrates following exposure to a stressor typically involves an immediate but transient release of glucocorticoids as a means of mobilizing available energy stores, usually in the form of glucose. Although a glucocorticoid role for 1α-OHB would be expected, direct glucocorticoid function of this steroid has yet to be reported in any elasmobranch. In addition, elasmobranchs also utilize the metabolite β-hydroxybutyrate (β-HB), which is thought to replace the role fatty acids play in most vertebrates as a predominant fuel source in extrahepatic tissues. To determine the mobilization of metabolites and corticosteroids during a stress event, North Pacific spiny dogfish, Squalus acanthias suckleyi, were cannulated and held in a darkened isolation box to recover (24-48 h) before being subjected to an acute air exposure or corticosterone injection. Dogfish were then serially blood sampled at nine timepoints over 48 h. Glucose, β-HB, 1α-OHB, corticosterone, as well as lactate, pH, and osmolality were quantified in plasma samples. All measured variables increased in control and treatment groups within 48 h from the start of experimentation, and β-HB and 1α-OHB remained elevated for the duration of the experiment. There was no linear correlation between glucose and 1α-OHB, but there was a weak (R 2  = 0.230) although significant (p = 0.001), positive correlation between β-HB and 1α-OHB. Interestingly, there were also significant correlations between increasing circulating glucose and corticosterone (R 2  = 0.349; p < 0.001), and decreasing β-HB and corticosterone concentrations (R 2  = 0.180; p = 0.008). Our data suggest that following successive stressors of capture, surgery, and confinement, 1α-OHB was not correlated with circulating glucose, only weakly correlated with circulating β-HB concentrations (R 2  = 0.230; p = 0.001), and that corticosterone may also serve a role in energy mobilization in this species., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Russian Sturgeon Acipenser gueldenstaedtii are an important, critically endangered, roe-producing species. Despite a wealth of knowledge pertaining to other members of family Acipenseridae, there is very limited published information regarding baseline blood analytes in Russian Sturgeon. The objectives of this study were (1) to establish reference intervals for a suite of hematological and biochemical data and (2) to compare plasma chemistry data to two point-of-care (POC) cartridges, tested on the VetScan iSTAT 1 analyzer, that use heparinized whole blood for the assessment of clinically normal, aquacultured adult Russian Sturgeon sedated with eugenol (AQUI-S 20E) at a single institution. Reference intervals are reported. The calculated hematocrit measured by the POC analyzer tended 4-5% lower than the spun packed cell volume, confirming the importance of spun packed cell volume as a reliable measurement of red blood cell mass. Various analytes, notably whole-blood urea nitrogen, glucose, sodium, total carbon dioxide, chloride, ionized calcium, and anion gap, were significantly different by both POC cartridges. This study successfully produced reference intervals for blood analytes in adult Russian Sturgeon under managed care and creates a foundation for future studies into the effects of extrinsic and intrinsic factors and variations of analytical methodologies on blood analytes in this species., (© 2020 American Fisheries Society.)

The objectives of this study were to describe a minimally invasive coelomic fluid sampling technique in elasmobranchs, to characterize the coelomic fluid composition in clinically normal and abnormal animals, and to compare findings from wild and managed populations. Fluid was collected via the coelomic pore in 89 individuals from 16 species spanning clinically normal and abnormal patients within a managed population (n = 54), a semi-managed open-lagoon population (n = 18), and a wild population (n = 17). Biochemical and cytological fluid analyses were performed on all samples, and bacterial and fungal culture, protein electrophoresis, and cholesterol electrophoresis were performed on a subset of samples. The presence of a variable volume of colorless to white and clear to slightly turbid coelomic fluid was consistent with a normal finding; however, the cytological and chemical makeup of coelomic fluid was found to provide additional clinically relevant information. The coelomic fluid from some of the abnormal samples (n = 37) contained white blood cells (n = 15) and concurrent bacteria (n = 7), the latter suggestive of bacterial coelomitis. Yolk was identified in both clinically normal and abnormal females. Of the biochemical parameters tested, calcium, chloride, cholesterol, osmolality, phosphorus, salinity, sodium, specific gravity, total protein, and urea nitrogen have clinical utility. Abnormal samples were mostly associated with reproductive disease, but to a lesser extent with coelomitis and hemocoelom. The wild and semi-managed groups had biochemical differences presumably reflective of the higher salinity of ocean water compared with that in the managed habitat. Aerobic bacteria were identified in normal (n = 7) and abnormal (n = 11) animals. Positive bacterial culture without inflammation may be normal. This study contributes to a further understanding of elasmobranch coelomic fluid analysis and its use as a diagnostic modality for the evaluation of elasmobranch health., (© 2019 American Fisheries Society.)

Large flying foxes (Pteropus vampyrus) are a socially complex species. In situ colonies typically comprise thousands of individuals in small harems of one male to many females. In ex situ environments, all-male colonies are becoming more common due to a surplus of males in the population. There is limited information describing the hormonal and behavioral patterns of all-male colonies during the breeding season. We assessed seasonal changes in hormones and behavior in an all-male colony of 12 large flying foxes at Disney's Animal Kingdom ® . We validated hormone assays using morning urine and fecal samples to assess seasonal changes in excreted immunoreactive testosterone and glucocorticoid metabolites. We collected behavior data using an all-occurrence method, recording agonistic behaviors related to territorial defense (hooking, biting, wing flexing, vocalizing, and wrestling), and sexual behavior (mounting and frontal grabbing). Results indicated that (i) we could reliably measure testosterone and glucocorticoid metabolites concentrations from fecal and urine samples collected from individual bats; (ii) there were distinct relationships between changes in levels of agonism and hormone concentrations throughout the year; and (iii) three agonistic behaviors (chasing, wrestling, and open-mouth threat) peaked prior to the increase in testosterone and glucocorticoid hormones measured during the breeding season. These three behaviors could potentially be used as early indicators to signal the onset of the breeding season and allow time to implement ex situ management changes to reduce the incidence of agonism between individuals., (© 2018 Wiley Periodicals, Inc.)

During amphibian metamorphosis dramatic changes occur in the morphogenesis and differentiation of the epidermis. Concurrently with these changes, the 63 kDa keratin gene is upregulated from low basal levels to high levels. What makes these processes unique is that they are controlled by triiodothyronine (T3) and can be duplicated in cultures of purified epidermal cells. Since there is a 2 day lag period between the addition of T3 and the upregulation of keratin gene expression and terminal differentiation, recent studies have focused on identifying the genes activated during the lag period. We assume that the transcription factors required for upregulation of the keratin gene are induced by T3 during the lag period, and therefore we have cloned the keratin gene so that promoter analyses can be conducted. S1 mapping assays have shown that the same transcription start sites are used during premetamorphosis when the keratin gene is basally expressed, during metamorphosis when it is T3-upregulated, and in the adult epidermis where it is expressed independently of T3. During the early part of the lag period TR beta and AP-2 mRNA levels are upregulated in the epidermis by T3. The transcription factor AP-2 is expressed at high levels in the skin of premetamorphic larvae and induced about fivefold by T3 but is not induced in an epithelial cell line (XL-177). Since the keratin mRNA, AP-2 mRNA, and other genes induced during the lag period are expressed in premetamorphic larvae it appears that T3 functions by upregulating the expression of genes previously activated by a T3-independent process. This preprogramming may account for the tissue specificity of T3 action during metamorphosis.