Seasonal and geographic variation in packed cell volume and selected serum chemistry of platypuses

Platypuses (Ornithorhynchus anatinus) inhabit the permanent rivers and creeks of eastern Australia, from north Queensland to Tasmania, but are experiencing multiple and synergistic anthropogenic threats. Baseline information of health is vital for effective monitoring of populations but is currently sparse for mainland platypuses. Focusing on seven hematology and serum chemistry metrics as indicators of health and nutrition (packed cell volume (PCV), total protein (TP), albumin, globulin, urea, creatinine, and triglycerides), we investigated their variation across the species' range and across seasons. We analyzed 249 unique samples collected from platypuses in three river catchments in New South Wales and Victoria. Health metrics significantly varied across the populations' range, with platypuses from the most northerly catchment, having lower PCV, and concentrations of albumin and triglycerides and higher levels of globulin, potentially reflecting geographic variation or thermal stress. The Snowy River showed significant seasonal patterns which varied between the sexes and coincided with differential reproductive stressors. Male creatinine and triglyceride levels were significantly lower than females, suggesting that reproduction is energetically more taxing on males. Age specific differences were also found, with juvenile PCV and TP levels significantly lower than adults. Additionally, the commonly used body condition index (tail volume index) was only negatively correlated with urea, and triglyceride levels. A meta-analysis of available literature revealed a significant latitudinal relationship with PCV, TP, albumin, and triglycerides but this was confounded by variation in sampling times and restraint methods. We expand understanding of mainland platypuses, providing reference intervals for PCV and six blood chemistry, while highlighting the importance of considering seasonal variation, to guide future assessments of individual and population condition.

Hematologic and serum biochemical reference intervals for wild eastern quolls (Dasyurus viverrinus): Variation by age, sex, and season

BACKGROUND

The eastern quoll (Dasyurus viverrinus) is an endangered carnivorous marsupial that has recently suffered significant population declines. Several small captive breeding populations have been established, with plans to translocate wild and captive individuals to areas of their former distribution. Accordingly, hematologic and serum biochemical reference intervals (RIs) established from wild eastern quoll populations are essential for monitoring the health and disease status of both captive and wild populations, and to evaluate the health of individuals before, during, and after translocation.

OBJECTIVES

We aimed to establish hematologic and serum biochemical RIs for wild eastern quolls, and examine the effects of age, sex, and season.

METHODS

We collected a total of 202 hematologic samples, 309 packed cell volume samples, and 335 serum biochemical samples from 168 individual quolls between May 2011 and November 2013. Species-level RIs were established, as well as RIs of groups separated by age (juvenile, adult) and sex (adult male, adult female) using nonparametric, robust, and parametric methods. Seasonal variation in age- and sex-specific reference values was also assessed.

RESULTS

Strong age and seasonal variation were evident in many hematologic and serum biochemical analytes, with significant variation observed in serum biochemical analytes between the sexes.

CONCLUSIONS

The observed age, sex, and seasonal variation reflect differences in the timing of growth and reproductive stressors, which interact with seasonal energetic demands. Our findings highlight the importance of using age-, sex-, and season-specific RIs for clinical evaluation of eastern quolls, as species-level RIs will inadvertently smooth and mask important seasonal fluctuations that reflect reproductive status at different times.

Leptin levels, seasonality and thermal acclimation in the Microbiotherid marsupial Dromiciops gliroides: Does photoperiod play a role?

Mammals of the Neotropics are characterized by a marked annual cycle of activity, which is accompanied by several physiological changes at the levels of the whole organism, organs and tissues. The physiological characterization of these cycles is important, as it gives insight on the mechanisms by which animals adjust adaptively to seasonality. Here we studied the seasonal changes in blood biochemical parameters in the relict South American marsupial Dromiciops gliroides ("monito del monte" or "little mountain monkey"), under semi-natural conditions. We manipulated thermal conditions in order to characterize the effects of temperature and season on a battery of biochemical parameters, body mass and adiposity. Our results indicate that monitos experience an annual cycle in body mass and adiposity (measured as leptin levels), reaching a maximum in winter and a minimum in summer. Blood biochemistry confirms that the nutritional condition of animals is reduced in summer instead of winter (as generally reported). This was coincident with a reduction of several biochemical parameters in summer, such as betahydroxybutyrate, cholesterol, total protein concentration and globulins. Monitos seem to initiate winter preparation during autumn and reach maximum body reserves in winter. Hibernation lasts until spring, at which time they use fat reserves and become reproductively active. Sexual maturation during summer would be the strongest energetic bottleneck, which explains the reductions in body mass and other parameters in this season. Overall, this study suggests that monitos anticipate the cold season by a complex interaction of photoperiodic and thermal cues.

Profound changes in blood parameters during torpor in a South American marsupial

Seasonal torpor or hibernation is a phenomenon characterized by a physiological transition to dormancy (torpor) during challenging periods in terms of energy availability or metabolic load. Extensive physiological reprogramming and changes in gene-expression, immune function, oxygen transport and intermediate metabolism, occur during eutherian hibernation. Here we studied the seasonality of blood parameters, and during daily torpor, in a South American marsupial (Dromiciops gliroides). Seasonal trends in blood parameters showed an increase in hematological parameters during winter, and increases in total proteins, albumin and globulin during autumn. In contrast, torpor induced a drastic drop during most blood parameters. PCV dropped significantly 60%, as well as RBC (58%), hemoglobin concentration (58%), WBC (79%), including neutrophils (51%), eosinophils (84%) and lymphocytes (82%). Biochemical parameters also showed reductions: triglycerides (81%), proteins (32%), albumin (24%), globulins (38%), albumin (24%), creatinine (48%) and glucose (42%). Our results confirm some patterns observed in hibernating eutherians, such as leukopenia, probably caused by sequestration of white blood cells in organs. However, red blood cells and hemoglobin concentration also were reduced, which is to the best of our knowledge has not been reported for marsupials. The observed reduction in biochemical parameters suggests that marsupials, as in eutherians, change from carbohydrate-based to lipid-based metabolism during hibernation. However, the absence of increases in beta-hydroxybutyrate is puzzling. Finally, we found an increase (although non-significant after statistical correction for multiple comparisons) of creatine kinase which together with an increase in neutrophil/lymphocyte ratio could be indicative of muscle lysis and inflammation. These results indicate profound changes in standard physiological processes during torpor.

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

BACKGROUND

Vertebrate alpha (alpha)- and beta (beta)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the alpha- and beta-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil beta-globin gene (omega) in the marsupial alpha-cluster, however, suggested that duplication of the alpha-beta cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous alpha- and beta-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation.

RESULTS

The platypus alpha-globin cluster (chromosome 21) contains embryonic and adult alpha- globin genes, a beta-like omega-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-zeta-zeta'-alphaD-alpha3-alpha2-alpha1-omega-GBY-3'. The platypus beta-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-epsilon-beta-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate alpha-globin clusters are flanked by MPG-C16orf35 and LUC7L, whereas all bird and mammal beta-globin clusters are embedded in olfactory genes. Thus, the mammalian alpha- and beta-globin clusters are orthologous to the bird alpha- and beta-globin clusters respectively.

CONCLUSION

We propose that alpha- and beta-globin clusters evolved from an ancient MPG-C16orf35-alpha-beta-GBY-LUC7L arrangement 410 million years ago. A copy of the original beta (represented by omega in marsupials and monotremes) was inserted into an array of olfactory genes before the amniote radiation (>315 million years ago), then duplicated and diverged to form orthologous clusters of beta-globin genes with different expression profiles in different lineages.