Ontogenetic changes in erythrocyte morphology in larval mole salamanders, Ambystoma talpoideum, measured with image analysis

Blood cells and hematological parameters of Chiala Mountain Salamander, Batrachuperus karlschmidti (Urodela, Hynobiidae)

Hematological parameters are essential indices for assessing the function of blood and reflecting not only the health status of animal but also their physiological adaptation to the environment. Herein, the composition of blood cells and the hematological parameters of wild Batrachuperus karlschmidti were examined for the first time, and the effects of sex, body size, body mass, and age on the hematological parameters were explored. The morphology and morphometric data of the blood cells, as well as the hematological parameters, of B. karlschmidti were slightly differ from those of its congener. However, hematological differences between sexes were only found in erythrocyte and leukocyte count, and mean cell volume (MCV), which possibly reflecting the need for better oxygen distribution and stronger immune protection for reproduction. Hematocrit (Hct) and mean cell hemoglobin (MCH) were strongly dependent on body mass. These also might have been attributed to higher oxygen requirements with larger body masses. This is a pilot project exploring the hematology of this species that may help establish hematological parameters in future for supporting species protection and monitoring studies, as well as help understanding the physiological adaptation of this species.

Ecological and life-history correlates of erythrocyte size and shape in Lepidosauria

Blood oxygen‐carrying capacity is shaped both by the ambient oxygen availability as well as species‐specific oxygen demand. Erythrocytes are a critical part of oxygen transport and both their size and shape can change in relation to species‐specific life‐history, behavioural or ecological conditions. Here, we test whether components of the environment (altitude), life history (reproductive mode, body temperature) and behaviour (diving, foraging mode) drive erythrocyte size variation in the Lepidosauria (lizards, snakes and rhynchocephalians). We collected data on erythrocyte size (area) and shape (L/W: elongation ratio) from Lepidosauria across the globe (N = 235 species). Our analyses show the importance of oxygen requirements as a driver of erythrocyte size. Smaller erythrocytes were associated with the need for faster delivery (active foragers, high‐altitude species, warmer body temperatures), whereas species with greater oxygen demands (diving species, viviparous species) had larger erythrocytes. Erythrocyte size shows considerable cross‐species variation, with a range of factors linked to the oxygen delivery requirements being major drivers of these differences. A key future aspect for study would include within‐individual plasticity and how changing states, for example, pregnancy, perhaps alter the size and shape of erythrocytes in Lepidosaurs.

Blood cells and hematological parameters of the mountain dragon, Diploderma micangshanensis (Squamata: Lacertilia: Agamidae)

Hematological characteristics reflect the health status of animals and their physiological adaptation to the environment. However, few studies focused on the species of Diploderma. In this study, the blood cells and the hematological parameters of Diploderma micangshanensis, a species endemic to China, were examined based on 48 healthy adult (32 males and 16 females). The blood cells and hematological parameters of D. micangshanensis were similar to those of other lizard species. Although the values of erythrocyte morphometric characters and hematological parameters varied between males and females, the differences were only significant in the case of the hematocrit and erythrocyte size, which may allow for higher oxygen availability in males. Hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscle volume were strongly affected by the snout-vent length and/or body mass, which reflect the physiological adaptation to the oxygen requirement of different individuals. This is the first report of hematological data from a species of Diploderma, and the results will provide data for research on the adaptive evolution and health assessment in this species and other congeners.

Comparison of hematological parameters in two different high altitudinal populations of Batrachuperus pinchonii (Amphibian: Urodela)

Hematological parameters are key to reflect the health status of animals and their physiological adaptation to the environment. However, few studies focused on the inter- and intra-specific variations of hematological parameters in hynobiid salamanders. Here, we examined the hematological parameters of the stream salamander,Batrachuperus pinchonii, originating from two different altitudinal populations to explore their intra-specific variation. Sexual dimorphism is only present in the erythrocyte count and males have higher mean values than females. The morphometric values of erythrocyte, hemoglobin concentration, and erythrocyte count of the high altitudinal (Jiajin) population were smaller than those of the lower altitudinal (Sandaoping) population; however, a significant difference between two populations was only revealed in the case of erythrocyte length via ANOVA. The results of linear regression showed that a significant relationship was present between body condition and erythrocyte length as well as the erythrocyte length to erythrocyte width ratio. Our findings suggest that the features of hematological parameters inB. pinchoniiare reflected in the size of erythrocyte, and neither in erythrocyte count nor in hemoglobin concentration. These results provide a foundation for assessing and monitoring the health status of this salamander species, and furthermore, for understanding the physiological basis of altitudinal adaptation.

Inside the Redbox: applications of haematology in wildlife monitoring and ecosystem health assessment

Blood analyses have great potential in studies of ecology, ecotoxicology and veterinary science in wild vertebrates based on advances in human and domestic animal medicine. The major caveat for field researchers, however, is that the 'rules' for human or domestic animal haematology do not always apply to wildlife. The present overview shows the strengths and limitations of blood analyses in wild vertebrates, and proposes a standardisation of pre-analytical procedures plus some suggestions for a more systematic examination of blood smears to increase the diagnostic value of blood data. By discussing the common problems that field researchers face with blood variables, we also aim to highlight common ground enabling new researchers in the field to accurately collect blood samples and interpret and place their haematological findings into the overall picture of an ecological or eco-toxicological study. Besides showing the practicality and ecological relevance of simple blood variables, this study illustrates the suitability of blood samples for the application of cutting-edge analytical procedures for expanding the current repertoire of diagnostic tools in wildlife monitoring and ecosystem health assessment.

New findings from an old pathogen: intraerythrocytic bacteria (family Anaplasmatacea) in red-backed salamanders Plethodon cinereus

During a recent study of red-backed salamanders (Plethodon cinereus), we discovered an intraerythrocytic organism typified by violet-staining, intracellular inclusions, consistent with descriptions of Cytamoeba or Aegyptianella (bacteria). Here we characterize its taxonomic status using molecular techniques and ask basic questions about its nature. Blood smears from 102 salamanders were examined from Pennsylvania, New York, and Virginia to determine prevalence, and whole blood from several infected animals was tested using a PCR which targets the 16S rRNA gene of bacteria. Phylogenetic analysis of partial 16S rRNA gene sequence (1201 bp) indicated this organism was in the order Rickettsiales and is likely a member of the family Anaplasmatacea. The organism differed from currently described taxa and was clearly differentiated from Aegyptianella pullorum of birds and "Candidatus Hemobacterium ranarum" (formally A. ranarum) of frogs. Of all salamanders, 17 (16.7%) were infected and these were significantly larger (snout-vent length) and had higher body condition scores than uninfected ones, and males were more likely to be infected than females. Erythrocytes affected by the pathogen were 5% larger than unaffected ones, but otherwise similar in morphology. Infected animals tended to have a greater number of circulating white blood cells, based on estimates from smears, indicating a nonspecific response to the pathogen by the innate immune system. Given its phylogenetic position, this pathogen is likely transmitted by an arthropod vector, and the male-biased prevalence strongly implicates trombiculid mites, which also live in leaf litter and affect male salamanders more so than females.