Hematology of Indian rhacophorid tree frog Polypedates maculatus Gray, 1833 (Anura: Rhacophoridae)

Morphology and cytochemical patterns of peripheral blood cells of tiger frog (Rana rugulosa)

Background

Tiger frog (Rana rugulosa) is a national second-class protected amphibian species in China with an important ecological and economic value. In recent years, due to excessive human hunting, pollution and habitat loss, the wild population of tiger frog has declined sharply. To protect wildlife resources, the artificial breeding of tiger frogs has rapidly developed in China. Diseases are increasing and spreading among tiger frogs due to the increasing scale of artificial farming. The blood examination is the most straightforward and less invasive technique to evaluate the animal health condition. Thus, it is essential to obtain the normal hematological indicators of tiger frogs. The objective of this study was to investigate the morphometry, microstructure and cytochemical patterns of peripheral blood cells in tiger frogs.

Methods

The number of blood cells in tiger frogs was counted on a blood count board, and the cell sizes were measured by a micrometer under light microscope. The morphology and classification of blood cells were studied by Wright-Giemsa staining, and the cytochemical pateerns was investigated by various cytochemical staining including periodic acid-Schiff (PAS), Sudan black B (SBB), peroxidase (POX), alkaline phosphatase (AKP), acid phosphatase (ACP), chloroacetic acid AS-D naphthol esterase (CAE) and α-naphthol acetate esterase (ANAE) staining.

Results

Besides erythrocytes and thrombocytes, five types of leukocytes were identified in tiger frogs: neutrophils, eosinophils, basophils, lymphocytes and monocytes. The mean erythrocyte, leukocyte and thrombocyte counts were 1.33 ± 0.15 million/mm³, 3.73 ± 0.04 × 10⁴/mm³ and 1.7 ± 0.01 × 10⁴/mm³, respectively. Small lymphocytes were the most abundant leukocytes, followed by large lymphocytes, Neutrophils, eosinophils and monocytes, basophils were the fewest. Eosinophils were strongly positive for PAS, positive for SBB, POX, ACP, CAE, ANAE, while weakly positive for AKP staining; basophils were strongly positive for PAS, ACP, positive for SBB, CAE, weakly positive for ANAE, negative for AKP, POX staining; neutrophils were strongly positive for ACP, SBB, positive for PAS, POX, weakly positive for AKP, CAE and ANAE staining; monocytes were positive for PAS, SBB, ANAE, weakly positive for ACP, AKP, POX, CAE staining; large lymphocytes and thrombocytes were positive for PAS, ACP, weakly positive for ANAE, while negative for SBB, POX, AKP, CAE; small lymphocytes were similar to large lymphocytes, except for strongly positive for PAS and ACP staining.

Conclusions

The blood cell types and morphology of tiger frogs were generally similar to those of other amphibians, while their cytochemical patterns had some notable species specificity.Our study could enrich the knowledge of peripheral blood cell morphology and cytochemistry in amphibians, and provide baseline data for health condition evaluation and disease diagnosis of tiger frogs.

Hematological parameters of a Neotropical wild frog population, with a phylogenetic perspective on blood cell composition in Anura

Hematological parameters can provide key information to an animal health status. However, this information is usually hard to obtain. Here, we described the hematological parameters of Leptodactylus podicipinus in the Brazilian Pantanal. We measured red blood cell morphometrics, erythrogram, and leukogram. We also tested for phylogenetic signal in the erythrogram and leukogram of 48 frog species from 15 families, testing if body size explains their variation. Lymphocytes were the most abundant leukocytes (>60%) in L. podicipinus, followed by neutrophils (∼10%). Given that L. podicipinus is an abundant and widely distributed species in central Brazil, knowing its hematological pattern can help establish a baseline and improve its use as a bioindicator of environmental degradation. Mean corpuscular hemoglobin and value contributed more to the phylomorphospace of erythrogram, in which Leptodactylus spp. and Hypsiboas raniceps had lower values of these variables, whereas Bufotes viridis and Hyla arborea had high values. The phylogenetic signal was spread throughout the dimensions of the leukogram phylomorphospace. The variables that most contributed to it were total leukocytes counts, lymphocytes, and neutrophils. We also found a moderate phylogenetic signal for both the erythrogram and leukogram. Accordingly, body size accounted for a low proportion of variation in both the leukogram (4.7%) and erythrogram (0.57%). By applying phylogenetic comparative methods to hematological parameters, our results add a new perspective on the evolution of blood cell physiology in frogs.

Biomarker and hematological fieldwork with amphibians: is it necessary to sample all night?

In the context of the global amphibian crisis, biomonitoring constitutes a valuable assessment tool to provide critical up to date information on the status and health of amphibians worldwide. The aim of the current study was to evaluate the possible confounding effects of sex, size, and time since capture on enzymatic biomarkers and hematologic parameters of the South American frog Leptodactylus latrans. Frogs were collected by hand between 9 pm and 12 am on two consecutive nights. On the first night, captured frogs were transported for 2 h by car to laboratory installations, maintained overnight in plastic containers, and blood and tissue sampled on the next morning. In contrast, frogs collected on the second night were blood and tissue sampled in the field, immediately after the capture period. Hematological parameters were analyzed, and enzymatic activities of catalase, cholinesterase (ChE), and glutathione S-transferase (GST) were determined in the plasma, liver, kidney, and muscle. A sex difference was observed only for total white blood cell counts (WBC), females exhibiting significantly greater values than males. The packed cell volume (PCV), mean corpuscular hemoglobin concentration (MCHC), WBC, and muscle ChE activity were significantly correlated with snout-vent length (SVL). The correlation was inversed in the case of MCHC, WBC, and muscle ChE, while the correlation was positive between PCV and SVL. Most examined parameters presented similar values when frogs were sampled at night following capture or the next morning. Total red blood cells (RBCs) count, and plasma enzymatic activities of ChE and GST were the only parameters that presented significantly increased values in morning samplings compared with night samplings. Overall, the current study indicates that it is best to sample the frogs as soon as possible after capture if hematologic or plasmatic biomarkers are examined. Nevertheless, it is possible to sample on the next morning if tissular biomarkers are employed.

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.

Hematology of wild caught Dubois's tree frog Polypedates teraiensis, Dubois, 1986 (Anura: Rhacophoridae)

Blood was analyzed from eighty (forty males and forty females) adult individuals of Polypedates teraiensis to establish reference ranges for its hematological and serum biochemical parameters. The peripheral blood cells were differentiated as erythrocytes, lymphocytes, eosinophils, neutrophils, monocytes, basophils, and thrombocytes, with similar morphology to other anurans. Morphology of blood cells did not vary according to sex. The hematological investigations included morphology and morphometry of erythrocytes, morphometry of leucocytes, packed cell volume (PCV), hemoglobin content (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), erythrocyte or red blood cell (RBC) count, leukocyte or white blood cell (WBC) count, differential leukocyte count, and neutrophil to lymphocyte (N/L) ratio. Besides, protein, cholesterol, glucose, urea, uric acid, and creatinine content of blood serum were assayed. Hematological parameters that differed significantly between sexes were RBC count, length and breadth of RBC, neutrophil %, N/L ratio, area occupied by basophils, and diameter of large lymphocyte and eosinophils. The level of glucose, urea, and creatinine in blood serum also significantly differed between sexes.

Blood cell profiles of the tadpoles of the Dubois's tree frog, Polypedates teraiensis Dubois, 1986 (Anura: Rhacophoridae)

The present paper describes a sequential study of the leukocyte profiles and the changes in morphometry and morphology of erythrocytes in the tadpoles of Polypedates teraiensis during their development and metamorphosis, that is, transfer from an aquatic mode to a terrestrial mode of life. Blood smears of 21 different stages (Gosner stage 26 to 46) of tadpoles were investigated. Population of erythrocytes was heterogeneous in population represented by various forms (oval, elliptical or rounded cells, comma shaped, teardrop shaped, schistocytes, senile erythrocytes, crenulated RBCs). Correlation between various morphometric values of erythrocytes was determined with different developing stages of tadpoles. Amongst the leucocytes, the lymphocytes were the most abundant cells followed by neutrophils. Neutrophils and monocytes showed varied morphologic forms. The percentage of lymphocytes and neutrophils showed a negative whereas percentage of eosinophil, basophil, and monocytes showed a positive correlation with the developmental stages of tadpoles. Blood platelets were also observed, which were rounded in shape and found in aggregates.