Leukocyte profile variation in Dupont’s Lark (Chersophilus duponti) in Spain and Morocco

Stress in birds has been widely studied through the measurement of heterophil-to-lymphocyte ratio (H/L ratio). In this study we aimed to assess for the first time the potential variation of stress, measured as H/L ratio, associated to geography (between-country variation) and seasonality (between seasons and within the breeding season), as well as the leukocyte profiles, in the threatened Dupont’s Lark (Chersophilus duponti), using samples from Spain and Morocco. Furthermore, we tested whether variation in H/L ratio was associated with variables such as population density, presence of blood parasites and individual body condition. We found that H/L ratio did not vary between countries, but individuals captured during the breeding season showed higher values of H/L compared to non-breeding ones. Neither male density, nor date within the breeding season had an effect on the H/L ratio. In Spain, individuals with higher body condition showed lower H/L ratio regardless of whether they were malaria-infected. In Morocco, malaria-infected individuals showed higher values of H/L ratio than the non-infected birds. Moreover, we found that our average values of H/L ratio in Morocco were within the ranges of other passerines, but not in Spain. Individuals with higher H/L ratios may be more stressed or present higher capability to face stressful situations. Although H/L ratio is a useful and relatively easy way to obtain measure of stress, the impact that the environment might have on stress and the way it is explained by H/L ratio must be addressed carefully. This study provides new insight for this species’ biology and provides useful reference information to test the status and survival of other populations.

The Effect of Insect Repellent Exposure on Leukocyte Profile and Histopathologic Findings in Lungs

Organophosphate compounds in insect repellent have a role in contributing to mosquito mortality but have toxic effects for humans when exposed for a long time. The research is aimed to analyze the effect of insect repellent exposure in blood leukocyte profile and histopathologic findings in lungs. The study used thirty males Rattus novergicus, which were divided into three groups, such as electric liquid insect repellent (P1) with contain 0.031% dimefluthrin, anti-mosquito coils (P2) with 0.014% dimefluthrin, and electric mat mosquito repellent with 0.566% dimefluthrin for 8 hours in 20 days respectively. Leukocyte profiles were determined by using the blood smear method, and the lung’s health was identified by histopathologic findings. Based on the results study showed mosquito coils exposure increase the lymphocytes count. Meanwhile, the electric liquid-repellent increased the basophil’s numbers. The electric mat exposure had more eosinophils, neutrophils stab, neutrophils segment, and monocytes in the blood. The leukocyte profile of each group showed there were no statistically significant differences (P-value > 0.05). Based on histopathology, lung findings showed that the electric mat exposure contributed to cells degeneration 7.5% and pleural thickening 30%. The higher dimefluthrin concentrations in insect repellents could affect leukocyte profile and lungs health.

The distribution and effects of microbeads on host-parasite interactions of Ontario wetland fauna: tadpoles, snails and trematodes

Plastic microbeads pose an environmental problem as they easily enter into waterbodies, take a long time to break down, and their ingestion can have negative effects on aquatic organisms. I found that microbead consumption had a significant negative effect on the growth of northern leopard frog (Lithobates pipiens) tadpoles, as well as their susceptibility to trematode parasite (Echinostoma trivolvis) infection, but minimal effects on leukocyte profiles and infection tolerance. Freshwater snails (Stagnicola elodes) given microbead diets exhibited a non-monotonic response in their production of trematode (Haematolechus parviplexus) infectious stages, with those in the highest microbead treatment tending to exhibit greater growth and shorter longevity. I also found that algae (Chlorella pyrenoidosa) and microbeads created density-dependent aggregations that could be a potential ingestion pathway for herbivorous fauna. Lastly, I found many particles in Ontario wetlands and ponds that may be used for controlled pesticide release, thus potentially posing a threat.

The distribution and effects of microbeads on host-parasite interactions of Ontario wetland fauna: tadpoles, snails and trematodes

Plastic microbeads pose an environmental problem as they easily enter into waterbodies, take a long time to break down, and their ingestion can have negative effects on aquatic organisms. I found that microbead consumption had a significant negative effect on the growth of northern leopard frog (Lithobates pipiens) tadpoles, as well as their susceptibility to trematode parasite (Echinostoma trivolvis) infection, but minimal effects on leukocyte profiles and infection tolerance. Freshwater snails (Stagnicola elodes) given microbead diets exhibited a non-monotonic response in their production of trematode (Haematolechus parviplexus) infectious stages, with those in the highest microbead treatment tending to exhibit greater growth and shorter longevity. I also found that algae (Chlorella pyrenoidosa) and microbeads created density-dependent aggregations that could be a potential ingestion pathway for herbivorous fauna. Lastly, I found many particles in Ontario wetlands and ponds that may be used for controlled pesticide release, thus potentially posing a threat.

Leukocyte profile of the helmeted manakin, Antilophia galeata (Passeriformes: Pipridae) in a Cerrado forest fragment

Changes in the amounts and proportions of leukocytes, known as leucocyte profiles, have been documented for several bird species and have been used to measure stress levels in these animals. The present work ascertained the biological and ecological attributes that influence the leukocyte profile of Antilophia galeata (Lichtenstein, 1823), the helmeted manakin. This species has been deemed useful in ecological studies because it responds to environmental changes. Blood samples drawn from 89 individuals of A. galeata captured in a Cerrado forest fragment were subjected to analysis under optical microscopy to identify and quantify leukocytes and micronuclei. The number of lymphocytes was greater for males, non-reproductive individuals and individuals infected with ticks. None of the leukocyte components differed in relation to age, molting or body condition index. The amount of micronuclei was correlated with values for total leukocytes, H/L ratio, heterophils, basophils and monocytes. The results suggest that reproduction may be an immunosuppressive factor for the species, producing sexual differences in lymphocyte availability. In addition, biomarkers of genotoxic damage (micronuclei) were related to the amount of leukocytes, indicating that individuals may be sensitive to environmental disturbances. Leukocyte profiles can be considered a useful tool for addressing ecological questions that are relevant to the conservation of species in degraded environments.

Stress-related changes in leukocyte profiles and telomere shortening in the shortest-lived tetrapod, Furcifer labordi

Background Life history theory predicts that during the lifespan of an organism, resources are allocated to either growth, somatic maintenance or reproduction. Resource allocation trade-offs determine the evolution and ecology of different life history strategies and define an organisms’ position along a fast–slow continuum in interspecific comparisons. Labord’s chameleon (Furcifer labordi) from the seasonal dry forests of Madagascar is the tetrapod species with the shortest reported lifespan (4–9 months). Previous investigations revealed that their lifespan is to some degree dependent on environmental factors, such as the amount of rainfall and the length of the vegetation period. However, the intrinsic mechanisms shaping such a fast life history remain unknown. Environmental stressors are known to increase the secretion of glucocorticoids in other vertebrates, which, in turn, can shorten telomeres via oxidative stress. To investigate to what extent age-related changes in these molecular and cellular mechanisms contribute to the relatively short lifetime of F. labordi, we assessed the effects of stressors indirectly via leukocyte profiles (H/L ratio) and quantified relative telomere length from blood samples in a wild population in Kirindy Forest. We compared our findings with the sympatric, but longer-lived sister species F. cf. nicosiai, which exhibit the same annual timing of reproductive events, and with wild-caught F. labordi that were singly housed under ambient conditions. Results We found that H/L ratios were consistently higher in wild F. labordi compared to F. cf. nicosiai. Moreover, F. labordi already exhibited relatively short telomeres during the mating season when they were 3–4 months old, and telomeres further shortened during their post-reproductive lives. At the beginning of their active season, telomere length was relatively longer in F. cf. nicosiai, but undergoing rapid shortening towards the southern winter, when both species gradually die off. Captive F. labordi showed comparatively longer lifespans and lower H/L ratios than their wild counterparts. Conclusion We suggest that environmental stress and the corresponding accelerated telomere attrition have profound effects on the lifespan of F. labordi in the wild, and identify physiological mechanisms potentially driving their relatively early senescence and mortality.