The effects of the fungicide methyl thiophanate on adrenal gland morphophysiology of the lizard, Podarcis sicula

Wildlife ecotoxicology of plant protection products: knowns and unknowns about the impacts of currently used pesticides on terrestrial vertebrate biodiversity

Agricultural practices are a major cause of the current loss of biodiversity. Among postwar agricultural intensification practices, the use of plant protection products (PPPs) might be one of the prominent drivers of the loss of wildlife diversity in agroecosystems. A collective scientific assessment was performed upon the request of the French Ministries responsible for the Environment, for Agriculture and for Research to review the impacts of PPPs on biodiversity and ecosystem services based on the scientific literature. While the effects of legacy banned PPPs on ecosystems and the underlying mechanisms are well documented, the impacts of current use pesticides (CUPs) on biodiversity have rarely been reviewed. Here, we provide an overview of the available knowledge related to the impacts of PPPs, including biopesticides, on terrestrial vertebrates (i.e. herptiles, birds including raptors, bats and small and large mammals). We focused essentially on CUPs and on endpoints at the subindividual, individual, population and community levels, which ultimately linked with effects on biodiversity. We address both direct toxic effects and indirect effects related to ecological processes and review the existing knowledge about wildlife exposure to PPPs. The effects of PPPs on ecological functions and ecosystem services are discussed, as are the aggravating or mitigating factors. Finally, a synthesis of knowns and unknowns is provided, and we identify priorities to fill gaps in knowledge and perspectives for research and wildlife conservation.

The Adrenal Gland of Squamata (Reptilia): A Comparative Overview

The adrenal gland is a complex endocrine organ composed of two components: a steroidogenic tissue, which produces steroid hormones, and a chromaffin tissue, which mainly produces norepinephrine and epinephrine. Through evolution, their relationships with each other changed. They begin as isolated chromaffin and steroidogenic cell aggregates, typical of fish, and end with the advanced compact gland, typical of mammals, which consists of an external steroidogenic cortical zone and an internal chromaffin medullary zone. The adrenal gland of reptiles is unique because, with few exceptions, it is near the gonads and genital ducts, and the chromaffin and steroidogenic tissues are closely associated. However, the degree of mixing is variable. For example, in Squamata, the mixing degree of chromaffin and steroidogenic tissues, their reciprocal position in the gland, and the relative quantities of norepinephrine and epinephrine secreted by the chromaffin cells are extremely variable. This variability could be related to the phylogenetic history of the species. After a brief discussion of the adrenal gland and its main functions in vertebrates, this overview will examine the general characteristics of the adrenal gland of squamates, the differences in morphology of the gland, and the possible relationships with the phylogeny of the different species.

Does environmental pollution affect male reproductive system in naturally exposed vertebrates? A systematic review

Due to environmental contamination, the environment constantly receives pollutants from various anthropic actions. These pollutants put ecological health at risk due to contamination and accumulation in living organisms, including wild animals and humans. Exposure can cause physiological, morphological, and behavioral changes in living beings. In this context, laboratory studies have frequently investigated how environmental contaminants affect the male reproductive system and gametes. However, few studies have examined how these contaminants affect male reproduction in naturally exposed animals. To better understand this topic, we conducted a systematic review of the effects of exposing male vertebrate animals to polluted environments on their reproductive functions. After an extensive search using the PubMed/MEDLINE, Scopus, and Web of Science databases, 39 studies met our inclusion criteria and were eligible for this review. This study showed that reproductive damages were frequent in fishes, amphibians, reptiles, birds, and mammals exposed to contaminated environments. Wild animals are exposed mainly to endocrine-disrupting compounds (EDCs), toxic metals, and radiation. Exposure to pollutants causes a reduction in androgen levels, impaired spermatogenesis, morphological damage to reproductive organs, and decreased sperm quality, leading to reduced fertility and population decline. Although several species have been studied, the number of studies is limited for some groups of vertebrates. Wildlife has proven valuable to our understanding of the potential effects of environmental contaminants on human and ecosystem health. Thus, some recommendations for future investigations are provided. This review also creates a baseline for the understanding state of the art in reproductive toxicology studies.

Processes involved in biochemical response to pesticides by lizard Podarcis siculus (Rafinesque-Schmaltz, 1810) – A field study

Although reptiles are non-target organisms of pesticide applications, their ecological niche and trophic role suggest that the use of these compounds in agriculture can have toxicological effects on them. Our recent field study on Italian wall lizard Podarcis siculus in hazelnut orchards evidenced that the use of pesticides-mixtures, consisting of thiophanate-methyl (TM), tebuconazole (TEB), deltamethrin (DM), lambda-cyhalothrin (LCT), besides copper sulphate, induced an increase of the total antioxidant capacity toward hydroxyl radicals and caused DNA damage; however, it did not cause neurotoxicity, and did not induce the glutathione-S-transferases' activities. These results raised some questions which were answered in this study by carrying out analyses on 4 biomarkers and 5 chemical substances in the tissues of non-target organisms coming from treated fields: cytochrome P450, catalase, total glutathione, and malondialdehyde, TM, TEB, DM, LCT and Cu. Our results highlighted a partial accumulation of different chemicals, the involvement of two important mechanisms of defence, and some cellular damages after exposure to the considered pesticides. In details, 1) LCT and DM were not accumulated in lizard muscle, copper remained at basal levels, whereas TM and TEB were uptaken with a partial metabolization of TM; 2) the cytochrome P450 and the catalase were involved in lizard biochemical responses to pesticides-mixtures used for "conventional" farming treatment; 3) "conventional" treatment with pesticides caused damage to lipids, besides DNA, probably related to the excess of hydroxyl radicals.

Biological responses in pesticide exposed lizards (Podarcis siculus)

The release of contaminants as herbicides, fungicides and insecticides into the environment has been listed as one of the six major contributors to the global decline of reptiles. Although reptiles may face severe risk from contaminants due to their ecology and physiology, they are currently less studied than other vertebrate groups. In the present work, we investigated if and how different types of field treatment (conventional and organic) affected the health status of Italian wall lizard (Podarcis siculus) individuals in central Italy. We chose a multi-biomarker approach that evaluated the biological responses of lizards to the treatment by means of AChE activity in the nervous system, biotransformation enzymes activities and oxidative stress in the liver, micronuclei frequency measured in the erythrocytes, and rate of intestinal parasitic infection. Our findings showed evidence of effects of treatment in conventional areas and between sexes with significant oxidative stress due to hydroxyl radicals, that caused DNA damage. No difference of intestinal parasite infections was found among treatments. Podarcis siculus seems to be a good bioindicator in ecotoxicological studies and potentially in risk assessment of pesticides, although further analyses in laboratory and in the field are needed to achieve more accurate quantification of specific pesticide effects in relation to known exposure history and to understand if other mechanisms were involved in the toxicity and detoxification process of pesticides for this species.

Enantioselective accumulation, elimination and metabolism of fenbuconazole in lizards (Eremias argus)

The enantioselective accumulation, elimination and metabolism of fenbuconazole in lizards were determined following a single-dose (25 mg/kg^bw) exposure to racemic or enantiomeric fenbuconazole. Accumulation of fenbuconazole was found in lizard fat with rac-form > enantiopure enantiomers. The enantiomer fractions (EFs) were higher than 0.5 in the blood, while EFs were less than 0.5 in the liver, brain, skin and stomach. There was conversion from (+)-fenbuconazole to (-)-fenbuconazole in lizard liver and conversion from (-)-fenbuconazole to (+)-fenbuconazole in lizard liver and blood. The results showed that enantioselective accumulation appeared in lizards, but the direction varied among blood and different tissues. The elimination half-lives (t_1/2) of (+)-fenbuconazole were higher than those of (-)-fenbuconazole in the blood and liver, suggesting that (-)-fenbuconazole eliminated faster than (+)-fenbuconazole in these tissues. In addition, both (+)-fenbuconazole and (-)-fenbuconazole eliminated faster in the liver and stomach exposed to racemate than those exposed to enantiopure enantiomers. On the contrary, the form of racemate decreased the elimination rate of fenbuconazole in lizard fat. Synergistic elimination may occur when two enantiomers coexisted in lizard liver and stomach, while the racemate produced antagonistic elimination in lizard fat. Simultaneously, three metabolites, RH-6467, RH-9029&RH-9030 and keto-mchlorophenol, were discovered in lizard liver. Only two metabolites, RH-6467 and RH-9029&RH-9030, were found in lizard blood. RH-9029&RH-9030 were the major metabolites. The discovered enantiomers of (+)-fenbuconazole metabolites were different from those of (-)-fenbuconazole. The findings of this study may provide a better understanding of the enantioselective behaviors of chiral triazole fungicides in reptiles.

Effects of alkylphenols mixture on the adrenal gland of the lizard Podarcis sicula

Alkylphenols (AP) are widespread environmental compounds belonging to the large family of substances known as Endocrine Disrupting Chemicals (EDCs). The present study was carried out to assess the effects of Octylphenol (OP) alone and in combination with Nonylphenol (NP) on the hypothalamus-pituitary-adrenal gland (HPA) axis of the lizard Podarcis sicula. Lizards are good bioindicators due to their features such as wide distribution, large population and good sensitivity to contaminants. Results obtained showed a time and dose-dependent stimulation of the HPA together with a high variation of both catecholamine plasma levels and greater vascularization and hypertrophy of steroidogenic cord of adrenal gland after both OP and OP + NP treatments. Interestingly, the OP + NP mixture treatment has provoked a state of stress of the adrenal gland which in fact appeared to be characterized by the presence of a marked macrophage infiltration which can be seen especially close to the connective capsule surrounding the gland. This macrophage infiltration could be an evidence of a particularly pronounced inflammatory state to indicate, probably, an animal's response to a non-physiological situation.

Adrenal gland response to endocrine disrupting chemicals in fishes, amphibians and reptiles: A comparative overview

The adrenal gland is an essential component of the body stress response; it is formed by two portions: a steroidogenic and a chromaffin tissue. Despite the anatomy of adrenal gland is different among classes of vertebrates, the hormones produced are almost the same. During stress, these hormones contribute to body homeostasis and maintenance of ion balance. The adrenal gland is very sensitive to toxic compounds, many of which behave like endocrine-disruptor chemicals (EDCs). They contribute to alter the endocrine system in wildlife and humans and are considered as possible responsible of the decline of several vertebrate ectotherms. Considering that EDCs regularly can be found in all environmental matrices, the aim of this review is to collect information about the impact of these chemical compounds on the adrenal gland of fishes, amphibians and reptiles. In particular, this review shows the different behavior of these "sentinel species" when they are exposed to stress condition. The data supplied in this review can help to further elucidate the role of EDCs and their harmful impact on the survival of these vertebrates.

Immunomodulatory effect of mancozeb, chlorothalonil, and thiophanate methyl pesticides on macrophage cells

Mancozeb (MZ), chlorothalonil (CT), and thiophanate methyl (TM) are pesticides commonly used in agriculture due to their efficacy, low acute toxicity to mammals, and short environmental persistence. Although the toxic effects of these pesticides have been previously reported, studies regarding their influence on the immune system are limited. As such, this study focused on the immunomodulatory effect of MZ, CT, and TM pesticides on macrophage cells. RAW 264.7 cells were exposed to a range of concentrations (0.1-100 μg/mL) of these pesticides. CT exposure promoted an increase in reactive oxygen species (ROS) and nitric oxide (NO) levels. The MTT and ds-DNA assay results demonstrated that MZ, CT, and TM exposure induced macrophage proliferation. Moreover, MZ, CT, and TM promoted cell cycle arrest at S phase, strongly suggesting macrophage proliferation. The levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IFN-γ) and caspases (caspase 1, 3, and 8) in macrophages exposed to MZ, CT, and TM pesticides increased, whereas the anti-inflammatory cytokine levels decreased. These results suggest that MZ, CT, and TM exert an immunomodulatory effect on the immune system, inducing macrophage activation and enhancing the inflammatory response.

Scientific Opinion on the state of the science on pesticide risk assessment for amphibians and reptiles

Following a request from EFSA, the Panel on Plant Protection Products and their Residues developed an opinion on the science to support the potential development of a risk assessment scheme of plant protection products for amphibians and reptiles. The coverage of the risk to amphibians and reptiles by current risk assessments for other vertebrate groups was investigated. Available test methods and exposure models were reviewed with regard to their applicability to amphibians and reptiles. Proposals were made for specific protection goals aiming to protect important ecosystem services and taking into consideration the regulatory framework and existing protection goals for other vertebrates. Uncertainties, knowledge gaps and research needs were highlighted.

Stereoselective degradation and thyroid endocrine disruption of lambda-cyhalothrin in lizards (Eremias argus) following oral exposure

The disturbance of the thyroid system and elimination of chiral pyrethroid pesticides with respect to enantioselectivity in reptiles have so far received limited attention by research. In this study, bioaccumulation, thyroid gland lesions, thyroid hormone levels, and hypothalamus-pituitary-thyroid axis-related gene expression in male Eremias argus were investigated after three weeks oral administration of lambda-cyhalothrin (LCT) enantiomers. In the lizard liver, the concentration of LCT was negatively correlated with the metabolite-3-phenoxybenzoic acid (PBA) level during 21 days of exposure. (+)-LCT exposure induced a higher thyroid follicular epithelium height than (-)-LCT exposure. The thyroxine levels were increased in both treated groups while only (+)-LCT exposure induced a significant change in the triiodothyronine (T3) level. In addition, the expressions of hypothalamus-pituitary-thyroid axis-related genes including thyroid hormone receptors (trs), deiodinases (dios), uridinediphosphate glucuronosyltransferase (udp), and sulfotransferase (sult) were up-regulated after exposure to the two enantiomers. (+)-LCT treatment resulted in higher expression of trs and (-)-LCT exposure led to greater stimulation of dios in the liver, which indicated PBA-induced antagonism on thyroid hormone receptors and LCT-induced disruption of thyroxine (T4) deiodination. The results suggest the (-)-LCT exposure causes higher residual level in lizard liver while induces less disruption on lizard thyroid activity than (+)-LCT.

Increased adrenal responsiveness and delayed hatching date in relation to polychlorinated biphenyl exposure in Arctic-breeding black-legged kittiwakes (Rissa tridactyla)

High levels of environmental contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and mercury (Hg) have been reported in some Arctic top predators such as seabirds. Chronic exposure to these contaminants might alter the response to environmental changes through interference with the regulation of corticosterone (CORT), a glucocorticoid stress hormone released by the hypothalamo-pituitary-adrenal (HPA) axis. Positive and negative relationships between CORT and environmental contaminants have been reported in polar seabirds. However, patterns appear inconclusive and it is difficult to attribute these relationships to a dysfunction of the HPA axis or to other confounding effects. In order to explore the relationships between the HPA axis activity and contaminants, we tested whether different aspects of the HPA axis of an Arctic seabird, the black-legged kittiwakes Rissa tridactyla, would be related to blood Hg, PCB and OCP concentrations. Male kittiwakes were caught during the incubation period in Svalbard and were subjected to different stress series: (1) a capture-restraint stress protocol, (2) an injection of dexamethasone (DEX) that enabled to test the efficacy of the HPA negative feedback and (3) an injection of adrenocorticotropic hormone (ACTH) that informed on the adrenal responsiveness. The HPA axis activity was unrelated to ΣOCPs and Hg. However, birds with high concentrations of ΣPCBs released more CORT after the ACTH injection. It is suggested that ΣPCBs may increase the number of ACTH-receptors on the adrenals. Additionally, hatching date was delayed in males with higher concentrations of ΣPCBs and ΣOCPs. This study gives new evidence that PCBs and adrenal activity may be related. Thus high PCB burden may make individuals more prone to other stressors such as ongoing climate change.

Interferences of an environmental pollutant with estrogen-like action in the male reproductive system of the terrestrial vertebrate Podarcis sicula

Nonylphenol (NP) is classified among the endocrine disruptor chemicals with estrogen-like properties. It is widely used in many industries and to dilute pesticides in agriculture, and is known to affect the reproductive system of many aquatic and semi-aquatic organisms. This study aimed to verify how NP, administered via food and water, may interfere with the reproductive cycle of a terrestrial vertebrate. Our model was the male Italian wall lizard Podarcis sicula, a seasonal breeding species that may be naturally exposed to environmental pollution. From our findings it emerges that an NP-polluted diet administered during the mating period causes in this lizard a slowdown of spermatogenesis and affects the testicular and epididymal structure, making it similar to that of the non-reproductive period. The distribution in the testis and epididymis of mRNA for steroid hormone receptors, i.e., estrogen α and β and androgen receptors, was also investigated. NP treatment inhibits the expression of AR, ERα, and ERβ-mRNA in spermatogonia and primary spermatocytes and causes a switch-off of the secretory activity of the epididymal corpus by inducing the expression of ERα.

Imidacloprid induces morphological and molecular damages on testis of lizard (Podarcis sicula)

The insecticide imidacloprid was evaluated under laboratory conditions in the adult male Italian wall lizards (Podarcis sicula) to assess its potential toxicity. By an acute oral test, LD50 was 503.76 mg/kg. Changes in spermatogenesis, plasma sex hormone levels and androgen and oestrogen receptor mRNAs were analysed by subchronic test and simulated environmental exposure. 15-days subchronic test, in which lizards were orally dosed on alternate days at 0, 10, 50, 100 mg/kg bw, showed a dose-dependent changes of testicular architecture and an increase of apoptotic processes. In a 30-days simulated environmental exposure spermatogenesis was arrested at secondary spermatocyte level and only few primary spermatocytes were TUNEL-positive. In all experimental groups imidacloprid was able to decrease both the level of sex hormones and the steroid receptor mRNAs. The results demonstrate that imidacloprid affects reproduction function of male lizards therefore precautions must be taken to minimize the harmful effects of this compound.

Stereoselective metabolism, distribution, and bioaccumulation brof triadimefon and triadimenol in lizards

In this research, Chinese lizards (Eremias argus) were chosen as laboratory animal to evaluate the stereoselectivity in the processes of metabolism, distribution, and bioaccumulation of triadimefon. A validated chiral high-performance liquid chromatography coupled with triple quadruple mass spectrometry (HPLC-MS/MS) method was developed for determining enantiomers' residues of parent compound triadimefon and its metabolite triadimenol in lizard blood and tissues. Pharmacokinetic results of single-does exposure suggested that S-(+)-triadimefon was metabolized easier than R-(-)-triadimefon, and RR-(+)-triadimenol was the main metabolic product of triadimefon. During the continuous exposure of two dose (40mg/kg(bw)·d and 200mg/kg(bw)·d), enantiomers of triadimefon and triadimenol were detected in all body compartments, with the highest triadimefon concentrations in brain. However, the triadimenol concentrations were not significantly different among the compartments. The concentrations of RS-(+)-triadimenol were negative correlated with concentrations of RR-(+)-triadimenol both in blood (r=-0.775, p=0.024) and liver (r=-0.834, p=0.02) in 200mg/kg(bw)·d group, which indicates that chiral conversion between enantiomers of triadimenol might exist in the metabolic process of triadimefon. In all the processes, the enantiomer fractions (EFs) of R-(-)-triadimefon and RR-(+)-triadimenol were significantly different from their natural ratios, 0.5 and 0.1, respectively, which proved that metabolism, bioaccumulation, and distribution of triadimefon and triadimenol in lizards were enantioselective. These results help enrich and supplement the knowledge of the stereoselective behaviour of triadimefon and triadimenol in reptile.

Nonylphenol effects on the HPA axis of the bioindicator vertebrate, Podarcis sicula lizard

Nonylphenol (NP) is an endocrine disruptor widely distributed in the environment. It accumulates in the lipids of living organisms and enters the human food chain. The main source of human exposure is expected to be food, drinking water and foodstuff contaminated through leaching from packaging or pesticide formulation applications. NP acts as an estrogenic compound and it is able to mimic the action of estradiol 17β (E2) by binding to the estrogen receptor (ER). The aim of the present study was to investigate the NP effects on the hypothalamic-pituitary-adrenal gland (HPA) axis of the bioindicator Podarcis sicula lizard. A time-dependent stimulation of the HPA axis and variations of both catecholamine plasma levels were showed. Moreover, NP effects on adrenal gland morphology were evaluated by light and transmission electron microscopy. Clear morphological signs of adrenal gland stimulation such as an increase of steroidogenic cord diameter and vascularization, a strong escalation of adrenaline cell number and a decrease of noradrenaline cells were observed. The notably elevated levels of adrenal hormones suggested a permanent turning on of hypothalamic corticotropin releasing factor (CRF) secretion together with a lack of the negative feedback of HPA axis, perturbing systemic responses of the organism. Our data may help to predict the biological alterations induced by NP and to extend its impact upon adrenal function.

The stress of being contaminated? Adrenocortical function and reproduction in relation to persistent organic pollutants in female black legged kittiwakes

High levels of environmental pollutants such as persistent organic pollutants (POPs) including PCB and DDT have been found in the Arctic and many of those pollutants may impair reproduction through endocrine disruption. Nevertheless, their effects on stress hormones remain poorly understood, especially in free-ranging birds. Corticosterone, the principal glucocorticoid in birds, can indirectly impair reproduction. The aim of the present study was to examine the relationships between POPs and reproduction through their potential consequences on different reproductive traits (breeding decision, egg-laying date, breeding success) and corticosterone secretion (baseline and stress-induced levels). We addressed those questions in an Arctic population of female black-legged kittiwakes during the pre-breeding stage and measured several legacy POPs (PCBs and pesticides: HCB, p,p'-DDE, CHL) in whole blood. POP levels were not related to breeding decision neither to breeding success, whereas females with high levels of pesticides laid their eggs earlier in the season. We found a negative relationship between POP levels and body condition index in non-breeding females. Black-legged kittiwakes with higher levels of PCB showed stronger adrenocortical response when subjected to a capture-handling stress protocol. We suggest that PCBs may disrupt corticosterone secretion whereas the positive relationship between pesticides and egg-laying date could either originate from a direct effect of pesticides or may be related to other confounding factors such as age or individual's quality. Although no direct negative reproduction output of POPs was found in this study, it is possible that the most contaminated individuals would be more sensitive to environmental stress and would be less able to maintain parental investment than less polluted individuals.

Testicular toxicity of methyl thiophanate in the Italian wall lizard (Podarcis sicula): morphological and molecular evaluation

The effects of the fungicide methyl thiophanate (MT) on testis were determined in the Italian wall lizard (Podarcis sicula) using morphological and molecular analyzes. Three experimental trials were performed: an acute test using six doses, a two-week chronic test, and "ecotoxicological" exposure (3 weeks). The minimal lethal dose (LD(50)) of pure MT, reached by the acute test, was 100 mg/kg body weight. Testicular histopathology of surviving animals showed a reduced lumen and several multinucleated giant cells 24 h after injection followed by large decreases in spermatogonia (72%) and secondary spermatocytes (58%) and a loss of spermatids and sperms 7 days after. In the chronic test, a dose equivalent to 1/100 of LD(50) was injected on alternate days. Complete shutting of the lumen and a great decrease in spermatogonia (82%) were observed. In "ecotoxicological" exposure, achieved with a commercial MT compound, testis showed a decrease in primary spermatocytes (20%) and several vacuoles. An increase in germ cell apoptosis was observed in all experimental groups using TUNEL assay. A decrease in expression of androgen and estrogen receptor (AR and ER) mRNAs was seen in all experimental groups. The reduction in AR and ER mRNAs was correlated to exposure time. Indeed, in the "ecotoxicological" treatment (30 days), the decrease reached 82 and 90% for AR and ER mRNAs, respectively. These data strongly indicate that treatment with MT, damaging the seminiferous epithelium and decreasing steroid receptor expression, might render exposed lizards infertile.

Histopathological effects of carbaryl on testes of snake-eyed lizard, Ophisops elegans

BACKGROUND, AIM AND SCOPE

Due to their ecological niche and insectivore nature, lizards are of increased risk of exposure to pesticides in agricultural areas. In addition to their potential direct effects on non-target species, insecticides can also result in indirect impacts on lizard population by reducing their food source. Carbaryl is a common insecticide that is widely used in areas of Turkey that are home to a variety of reptiles. However, to date, little is known about the potential effects of the exposure of reptiles such as lizards or snakes to this pesticide. The aim of the study was to investigate toxic effects of carbaryl on the testes of snake-eyed lizard, Ophisops elegans that is common to regions in Turkey where Carbaryl is applied and that it can be easily cultured in the laboratory.

MATERIAL AND METHODS

Adult male lizards were exposed to carbaryl once by oral gavage in concentrations of 2.5, 25 and 250 μg/g. After 96 h, lizards were euthanized and dissected. Histopathological changes were detected by randomly counting 100 tubules in each lizard. Seminiferous tubules were categorized as normal, sloughing and disorganized tubules. Diameters of tubules were also measured. The differences in histopathological changes and tubule diameters were compared for statistical significance by one-way ANOVA, using SPSS 16.0.

RESULTS AND DISCUSSION

Histopathological changes were more prominent in medium- (25 μg/g) and high-dose (250 μg/g) groups than in the low-dose (2.5 μg/g) group. In the medium-dose group, the hexagonal appearance of most tubules disappeared, and they took on an oval shape. Sloughing was the characteristic tubule appearance of the medium group. In the high-dose group, significant increases in the number of disorganized tubules and prominence of haemorrhages was observed.

CONCLUSION

Carbaryl caused histopathological defects on the testes of O. elegans, so it is clear that carbaryl affects male fertility in O. elegans.

Genotoxic effects of the fungicide thiophanate-methyl on Podarcis sicula assessed by micronucleus test, comet assay and chromosome analysis

The increasing use of pesticides in modern agriculture has raised the need to evaluate their potential threat to animal and human health. In the present study, the genotoxic effects of environmentally relevant exposure to the fungicide thiophanate-methyl (TM) were assessed in the lizard Podarcis sicula (Reptilia, Lacertidae) using micronucleus test, chromosome aberration analysis and single-cell gel electrophoresis (comet) assay. The number of micronuclei increased significantly with exposure time in lizard specimens exposed to 1.5% TM for 30-40 days. In situ hybridization with the specific HindIII centromeric satellite was positive in 18.7% of the micronuclei observed, suggesting an aneugenic effect of TM during mitosis. DNA damage, evaluated by the comet assay, documented a significant gain in comet length in relation to exposure time that was paralleled by a reduction in head size. Finally, cytogenetic analysis showed a significant increase in chromosome aberrations in exposed animals compared with controls. Our data suggest that long-term TM exposure induces a genomic damage that is positively correlated to exposure time. If such genotoxic effects arise so clearly in an ectothermal vertebrate, such as P. sicula, prolonged exposure TM must be considered as a cytogenetic hazard.

The autonomic nervous system and chromaffin tissue: neuroendocrine regulation of catecholamine secretion in non-mammalian vertebrates

If severe enough, periods of acute stress in animals may be associated with the release of catecholamine hormones (noradrenaline and adrenaline) into the circulation; a response termed the acute humoral adrenergic stress response. The release of catecholamines from the sites of storage, the chromaffin cells, is under neuroendocrine control, the complexity of which appears to increase through phylogeny. In the agnathans, the earliest branching vertebrates, the chromaffin cells which are localized predominantly within the heart, lack neuronal innervation and thus catecholamine secretion in these animals is initiated solely by humoral mechanisms. In the more advanced teleost fish, the chromaffin cells are largely confined to the walls of the posterior cardinal vein at the level of the head kidney where they are intermingled with the steroidogenic interrenal cells. Catecholamine secretion from teleost chromaffin cells is regulated by a host of cholinergic and non-cholinergic pathways that ensure sufficient redundancy and flexibility in the secretion process to permit synchronized responses to a myriad of stressors. The complexity of catecholamine secretion control mechanisms continues through the amphibians, reptiles and birds although neural (cholinergic) regulation may become increasingly important in birds. Discrete adrenal glands are present in the non-mammalian tetrapods but unlike in mammals, there is no clear division of a steroidogenic cortex and a chromaffin cell enriched medulla. However, in all groups, there is an obvious intermingling of chromaffin and steroiodogenic cells. The association of the two cell types may be particularly important in the amphibians and birds because like in mammals, the enzyme catalysing the methylation of noradrenaline to adrenaline, PNMT, is under the control of the steroid cortisol.

Differential gene expression profiles in embryos of the lizard Podarcis sicula under in ovo exposure to cadmium

Screening for differentially expressed genes is a straightforward approach to study the molecular basis of contaminant toxicity. In this paper, the mRNA differential display technique was applied to analyze transcriptional regulation in response to cadmium exposure in the lizard embryos. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may interfere or disrupt normal physiological function in the developing embryo, including regulation of gene expression. Fertilized eggs of the lizard Podarcis sicula were incubated in cadmium-contaminated soil at 25 degrees C for 20 days. Gene expression profiling showed 5 down- and 9 up-regulated genes. Four cDNAs had no homology to known gene sequences, thus suggesting that may either encode not yet identified proteins, or correspond to untranslated regions of mRNA molecules. Four fragments exhibited significant sequence similarity with genes encoding novel proteins or ESTs derived from other vertebrates. The remaining genes are mainly involved in molecular pathways associated with processes such as membrane trafficking, signal transduction, cytoskeletal organization, cell proliferation and differentiation. Cadmium also affected the expression of factors actively involved in the regulation of the transcription machinery. Down-regulated genes are mainly associated with cellular metabolism and cell-cycle regulation and apoptosis. All of these differentially expressed genes may represent candidates that function in cadmium responses. The present study leads to an increased understanding of genes and/or the biochemical pathways involved in perturbation of embryo development following cadmium exposure.