Acute exposure to isoflurane impairs sperm parameters in mice

Isoflurane, an inhalational anesthetic from the halogenated group, has been increasingly used in the medical and scientific fields. Due to its characteristics, it is capable of inducing anesthesia quickly and quietly; however, the adverse effects resulting from its use have not yet been fully elucidated, especially with regard to reproductive aspects. Considering its common use in research laboratories, whether for performing surgical procedures or for prior exposure to euthanasia, knowledge about its interference in sperm parameters of experimental models characterizes an important study goal. The aim of the present study was to determine the interference of acute exposure to isoflurane on the sperm quality of mice, both immediately previous to euthanasia and in later evaluation, twenty days after a single anesthetic exposure. Our results demonstrate that acute anesthetic exposure reduces sperm motility and is responsible for the formation of damaged sperm cells that are prone to apoptosis, which may affect the outcome of reproductive experiments even 20 days after exposure.

Chlorothalonil as a potential endocrine disruptor in male zebrafish (Danio rerio): Impact on the hypothalamus-pituitary-gonad axis and sperm quality

Chlorothalonil is a broad-spectrum organochlorine fungicide widely employed in agriculture to control fungal foliar diseases. This fungicide enters aquatic environments through the leaching process, leading to toxicity in non-target organisms. Organic contaminants can impact organism reproduction as they have the potential to interact with the neuroendocrine system. Although there are reports of toxic effects of chlorothalonil, information regarding its impact on reproduction is limited. The aim of the present study was to evaluate the influence of chlorothalonil on male reproductive physiology using the zebrafish (Danio rerio) as ecotoxicological model. Zebrafish were exposed for 7 days to two concentrations of chlorothalonil (0.1 and 10 μg/L) along with a control group (with DMSO - 0.001%). Gene expression of hypothalamus-pituitary-gonad axis components (gnrh2, gnrh3, lhr, fshr, star, hsd17b1, hsd17b3, and cyp19a1), as well as hepatic vitellogenin concentration were assessed. In sperm cells, reactive oxygen species (ROS) content, lipid peroxidation (LPO), mitochondrial functionality, and membrane integrity and fluidity were evaluated. Results indicate that exposure to the higher concentration of chlorothalonil led to a reduction in brain gnr2 expression. In gonads, mRNA levels of lhr, star, and hsd17b1 were decreased at both chlorothalonil concentrations tested. Similarly, hepatic vitellogenin concentration was reduced. Regarding sperm cells, a decreased ROS level was observed, without significant difference in LPO level. Additionally, a higher mitochondrial potential and lower membrane fluidity were observed in zebrafish exposed to chlorothalonil. These findings demonstrate that chlorothalonil acts as an endocrine disruptor, influencing reproductive control mechanisms, as evidenced by changes in expression of genes HPG axis, as well as hepatic vitellogenin concentration. Furthermore, our findings reveal that exposure to this contaminant may compromise the reproductive success of the species, as it affected sperm quality parameters.

Static Magnetic Stimulation Induces Changes in the Oxidative Status and Cell Viability Parameters in a Primary Culture Model of Astrocytes

Astrocytes play an important role in the central nervous system function and may contribute to brain plasticity response during static magnetic fields (SMF) brain therapy. However, most studies evaluate SMF stimulation in brain plasticity while few studies evaluate the consequences of SMF at the cellular level. Thus, we here evaluate the effects of SMF at 305 mT (medium-intensity) in a primary culture of healthy/normal cortical astrocytes obtained from neonatal (1 to 2-day-old) Wistar rats. After reaching confluence, cells were daily subjected to SMF stimulation for 5 min, 15 min, 30 min, and 40 min during 7 consecutive days. Oxidative stress parameters, cell cycle, cell viability, and mitochondrial function were analyzed. The antioxidant capacity was reduced in groups stimulated for 5 and 40 min. Although no difference was observed in the enzymatic activity of superoxide dismutase and catalase or the total thiol content, lipid peroxidation was increased in all stimulated groups. The cell cycle was changed after 40 min of SMF stimulation while 15, 30, and 40 min led cells to death by necrosis. Mitochondrial function was reduced after SMF stimulation, although imaging analysis did not reveal substantial changes in the mitochondrial network. Results mainly revealed that SMF compromised healthy astrocytes' oxidative status and viability. This finding reveals how important is to understand the SMF stimulation at the cellular level since this therapeutic approach has been largely used against neurological and psychiatric diseases.

High-speed centrifugation of extender of freeze-thaw boar semen

In semen cryopreservation, egg yolk is still widely used as a non-penetrating cryoprotectant. Much has been developed in the search for alternatives for this biological product. This work aimed to evaluate the processed egg yolk through ultracentrifugation and/or sonication in the cryopreservation of swine semen. Twenty-seven semen doses were purchased from a commercial boar stud and processed for cryopreservation using egg yolk lactose 11% (control) extender, processed using two different methods: high-speed centrifugation and sonication. Then, they were submitted to freeze-thawing protocol and were assessed for kinematic and cell structural parameters. Samples in which extenders underwent centrifugation had better results in velocity parameters, meanwhile those that only sonication was performed had poorest results in this parameter. The preservation of the membrane and mitochondria structure had better results when the diluent was only centrifuged in comparison with the other treatments. Therefore, centrifugation of extender containing egg yolk is important for better cryopreservation of swine semen.

Impacts of the biocide chlorothalonil on biomarkers of oxidative stress, genotoxicity, and sperm quality in guppy Poecilia vivipara

Chlorothalonil is a fungicide present in antifouling paints and other formulations used in agriculture, although studies have shown this chemical to be toxic to fish species. To clarify the deleterious effects of chlorothalonil for these non-target organisms, the present study evaluated the toxic effects of this biocide for the estuarine guppy Poecilia vivipara in terms of an acute mortality test (96 h) and the analysis of biomarkers of oxidative stress, genotoxicity, and sperm quality. The LC₅₀ calculated for P. vivipara was 40.8 μg/L of chlorothalonil. For the analysis of biomarkers, fish were exposed (96 h) to 1 and 10 μg/L of chlorothalonil. It was observed that chlorothalonil alters the levels of pro- and antioxidants towards oxidative stress. In the gills, a negative effect on total antioxidant capacity (ACAP) was detected, while there was a reduction in the activity of glutathione S-transferase (GST) in the liver. However, levels of glutathione (GSH) and the activity and glutamate-cysteine-ligase (GCL) increased in both tissues, as a possible detoxification response. Following chlorothalonil exposure, oxidative damage measured by lipoperoxidation (LPO) significantly increased at the cellular level only (red blood cells (RBCs) and sperm cells). An increase in fluidity of membranes, reactive oxygen species concentration and micronuclei (MNs) incidence were also seen in RBCs. In sperm cells, LPO increased, while membrane and mitochondrial functionality as well as sperm motility decreased. Based on these results, chlorothalonil can be considered as a toxic compound for fish, causing genotoxicity and affecting the RBCs physiology and the fertility of males of P. vivipara.

Meroanencephaly in an English Pointer Neonate

Background: Malformations are structural or functional abnormalities in the organs and structures present at birth. These conditions are rarely described in the newborns of dogs and can lead to their death. Meroanencephaly is a defect of the neural tube closure malformation. This study aims to characterize the clinical-pathological aspects of neonatal meroanencephaly since brain malformations are rare in newborn dogs.Case: A two-day-old English Pointer canine was sent for a necropsy. The newborn belonged to a litter of eight puppies, and only this one had macroscopic cranial alterations. Another puppy that died as a consequence of being trampled by the bitch was also necropsied. The newborn was alive for 48 h until death and presented apathy, crying, sucking reflex and opisthotonus. Macroscopic examination of the baby revealed flattening of the skull, with a slit at the site of bone symphysis fusion, and a slit in the skin of the parietal region, covered by thin, translucent meningeal tissue. The heads of the two animals were examined by radiography to identify the features of anencephaly in one of the animals by visualizing skull bone flattening. Upon removing the skin and exposing the cranial cavity, an irregular reddish mass was revealed, that corresponded microscopically to area cerebrovasculosa, composed of neurons, rudimentary glial tissue, vascular neoformations, as well as hemorrhagic areas.Discussion: Meroanencephaly is a type of anencephaly, a congenital malformation originating from abnormal neurulation, which results from the absence of neural fold fusion during neural tube formation. Live-born anencephalics have some brainstem-driven functions such as spontaneous breathing and some reflex responses, for instance, suction. Several genetic or teratogenic factors, such as viruses, radiation, drugs administered during pregnancy and other pathologies transmitted from bitch to fetus, can lead to this defect. The reports on anatomopathological findings and the presence of area cerebrovasculosa are rare.

Life-time exposure to waterborne copper IV: Sperm quality parameters are negatively affected in the killifish Poecilia vivipara

In previous studies, we have shown that copper (Cu) is significantly accumulated in various tissues of killifish Poecilia vivipara following chronic exposure. Also, we showed that chronic metal exposure disrupted energy production and growth in this species. In the present study, we aimed to evaluate if chronic exposure to this metal could also affect reproductive parameters of P. vivipara males (sperm quality). In order to test that, newborn (<24 h-old) fish were exposed to two concentrations of waterborne Cu (5 and 9 μg/L) for 345 days. After exposure, fish were euthanized and the testes were collected for sperm analysis. We could observe that exposed animals had reduced sperm motility and period of motility. Also, the sperm of exposed fish had reduced plasma membrane integrity, mitochondrial functionality and DNA integrity when compared to sperm of control animals. It is suggested that the well-known association of Cu with elevated oxidative damage, endocrine disruption and energetic disturbance are involved with the observed outcomes. The results obtained in the present study show that chronic exposure to environmentally relevant concentrations of waterborne Cu caused reductions in all parameters used to evaluate sperm quality. Therefore, it is concluded that life-time exposure to this metal may disrupt fish reproduction and negatively affect the maintenance of its populations.

MALE ADULT RAT SPERM PARAMETERS AFTER SKELETAL MUSCLE INJURY

ABSTRACT Introduction: Skeletal muscle injuries stimulate a systemic inflammatory response which may interfere in species reproduction. Objective: To evaluate the effects caused by skeletal muscle injuries on the inflammatory response and sperm parameters of male adult rats. Methods: The sample group was composed of 30 Wistar rats distributed evenly across control and injury groups. Muscle injury was induced by bruising, caused by the release of a 200 g weight from a height of 30 cm onto the gastrocnemius muscle. Blood (CBC and damage/muscle inflammation markers), muscle (oxidative stress) and gonad (sperm parameters) samples were collected 72h after the injury. Results: The muscle injury increased monocytes, creatine kinase, C-reactive protein, reactive oxygen species (ROS) concentration and lipid peroxidation. In contrast, the injury reduced antioxidant capacity against peroxyl radicals (ACAP), membrane integrity (36%) and sperm acrosome (33%). Membrane integrity and acrosome (p<0.05) correlate directly with ACAP (ρ=0.602; ρ=0.513 respectively) and inversely with monocytes (ρ=-0.703; ρ=-0.635, respectively), creatine kinase (ρ=-0.450; ρ=-0.603), C-reactive protein (ρ=-0.511; ρ=-0.703) and parameters of oxidative stress (ROS ρ=-0.703; ρ=-0.635; lipid peroxidation ρ=-0.494; ρ=-0.559). Conclusion: The acute systemic inflammatory response arising from skeletal muscle injury interferes in the male reproductive cell organelles (membrane and acrosome). Level of Evidence V; Experimental study.

Immunolocalization of Leptin and its Receptor (ObR-b) in Equine Placenta at Term and Plasma Level Measurement in the Late Gestation

Placental tissues from humans, rodents, and farm animal contain leptin and its receptor. Expression of leptin has already been described in horses, although there is no description about immunolocalization of leptin and its receptor. The aim of the present study was to investigate the presence and distribution of leptin and ObR-b in the equine placenta at term by immunofluorescence staining, and the changes on plasma leptin concentrations during late gestation. The present study involved eight Criollo-type mares carrying healthy pregnancies. Blood samples were collected during the third trimester of gestation, at foaling, and at 24 hours after foaling. Leptin concentrations were analyzed via radioimmunoassay. Plasma leptin concentrations did not change from the 8th to the 10th month of gestation and displayed a discrete decrease 24 hours after parturition (P = .07). The expression of leptin and ObR-b was observed in the cytoplasm of pseudostratified epithelial cells in the areolar region and in the epithelium of microcotyledons. Also, leptin receptor was allocated in the apical surface of the cells. The presence of leptin and its receptor (ObR-b) in the placenta of mares at term supports an endocrine and autocrine/paracrine action of leptin within this organ.

Use of trehalose in the semen cryopreservation of Amazonian catfish Leiarius marmoratus

The current study assessed a semen cryopreservation protocol in the Amazonian catfish Leiarius marmoratus, a freshwater fish, of rheophilic behavior, and of great importance for Brazilian fish farming. Eight males (n = 8) were stripped and the semen was cryopreserved if total motility in fresh semen was higher than 80%. The external cryoprotectant Trehalose was then diluted in Beltsvile Thawing Solution (BTS) extender in the following concentrations: 50, 100, 150, and 200 mM. Semen samples were diluted in the media (1:9 v/v) being tested, then frozen in a container with nitrogen vapor (dryshipper), and stored in liquid nitrogen at -196 °C. Motility parameters assessed post-thawing were performed by CASA-system and sperm cell integrity analyses (membrane integrity, DNA integrity, and mitochondrial function) were performed through fluorescence microscopy. As a result, no significant statistical difference was observed between treatments, independently of Trehalose concentrations tested in the following post-thawing analysis: membrane integrity, DNA integrity, mitochondrial functionality, and sperm motility duration. As of total and progressive motilities, the treatment containing 50 mM trehalose (15.6 and 9.5%, respectively), exhibited inferior results when compared to treatments with 150 mM (22.9 and 17.7%, respectively) and 200 mM (31.4 and 26.3%, respectively) trehalose concentrations (P < 0.05); however, it did not differ from the treatment with 100 mM trehalose (18.6 and 15.3%, respectively). Therefore, treatments with trehalose at higher concentrations exhibited superior results when compared to other treatments in in vitro motility parameters for L. marmoratus.

Roundup® Herbicide Decreases Quality Parameters of Spermatozoa of Silversides Odontesthes Humensis

The silverside (Odontesthes humensis) is a very interesting model for toxicological studies due its high sensitivity and need for good water quality. The aim of this study was to evaluate the effects of Roundup on spermatozoa of O. humensis, after acute exposure. The fish were exposed to 0 and 7.8 mg L-1 (a.e.) of glyphosate, respectively. Through computer-assisted sperm analysis, a significant decrease in concentration, total and progressive motility, average path distance, straight line distance, path average velocity, curved line velocity, straight line velocity linearity, wobble, amplitude of lateral head displacement, cross beat frequency, and motility period of silverside spermatozoa exposed to Roundup was observed. Also, increase in membrane fluidity, ROS production and lipid peroxidation and a decrease in the mitochondrial functionality was observed in spermatozoa of Roundup exposed silversides. It was demonstrated that Roundup exposure in a concentration that can be achieve in natural water bodies soon after its application in fields is able to cause losses in several sperm quality parameters, consequently decreasing the fertilization potential of O. humensis spermatozoa.

Effects of dietary microencapsulated Cymbopogon flexuosus essential oil on reproductive-related parameters in male Rhamdia quelen

In aquaculture, nutrition and supplemented diets have been shown to affect broodstock reproductive performance. In this study, we investigated the effects of dietary supplementation with Cymbopogon flexuosus essential oil (CFEO) microcapsules on reproductive-related parameters in silver catfish (Rhamdia quelen) male broodfish. Adult male broodstocks were separated into three groups according to the concentrations of supplemented CFEO (0.0 = control; 1.0 or 3.0 mL per kg of diet). After 20 days under experimental conditions, the animals were euthanized and the gonads were harvested for gonadosomatic index, sperm analysis, oxidative stress, and histopathology; testosterone levels were measured in the plasma; gene expression of prl, smtl, pomca, and pomcb was assessed in the pituitary gland by real-time PCR. The results showed no alterations on reproductive parameters in R. quelen males treated with Cymbopogon flexuosus essential oil compared to the control-diet animals. In conclusion, CFEO microcapsules supplied for 20 days in the concentrations of 1.00 or 3.00 mL per kilogram of diet did not affect the reproduction criteria evaluated in this study in male silver catfish.

The herbicide atrazine affects sperm quality and the expression of antioxidant and spermatogenesis genes in zebrafish testes

The herbicide atrazine (ATZ) is used worldwide in the control of annual grasses and broad-leaved weeds. The present study evaluated sperm quality parameters in zebrafish Danio rerio after 11-day exposure to nominal ATZ concentrations of 2, 10, and 100 μg L^-1. All ATZ concentrations caused a decrease in motility, mitochondrial functionality, and membrane integrity, as measured using conventional microscopy or fluorescence microscopy with specific probes. The DNA integrity of sperm was not affected. The levels of expression of genes related to spermatogenesis, antioxidant defenses, and DNA repair were also investigated using RT-qPCR. The ATZ caused transcriptional repression of the spermatogenesis-related genes SRD5A2 and CFTR, the antioxidant defense genes SOD2 and GPX4B, and the DNA repair gene XPC. This is the first study to show that environmentally relevant concentrations of ATZ significantly affect the sperm quality in fish, possibly resulting in reduced fertility rates. In addition, we showed that the repression of genes related to spermatogenesis and cellular defense could be part of the mechanisms involved in the ATZ toxicity in the testes of male fish.

Evaluation of Reference Genes to Analyze Gene Expression in Silverside Odontesthes humensis Under Different Environmental Conditions

Some mammalian reference genes, which are widely used to normalize the qRT-PCR, could not be used for this purpose due to its high expression variation. The normalization with false reference genes leads to misinterpretation of results. The silversides (Odontesthes spp.) has been used as models for evolutionary, osmoregulatory and environmental pollution studies but, up to now, there are no studies about reference genes in any Odontesthes species. Furthermore, many studies on silversides have used reference genes without previous validations. Thus, present study aimed to was to clone and sequence potential reference genes, thereby identifying the best ones in Odontesthes humensis considering different tissues, ages and conditions. For this purpose, animals belonging to three ages (adults, juveniles, and immature) were exposed to control, Roundup®, and seawater treatments for 24 h. Blood samples were subjected to flow-cytometry and other collected tissues to RNA extraction; cDNA synthesis; molecular cloning; DNA sequencing; and qRT-PCR. The candidate genes tested included 18s, actb, ef1a, eif3g, gapdh, h3a, atp1a, and tuba. Gene expression results were analyzed using five algorithms that ranked the candidate genes. The flow-cytometry data showed that the environmental challenges could trigger a systemic response in the treated fish. Even during this systemic physiological disorder, the consensus analysis of gene expression revealed h3a to be the most stable gene expression when only the treatments were considered. On the other hand, tuba was the least stable gene in the control and gapdh was the least stable in both Roundup® and seawater groups. In conclusion, the consensus analyses of different tissues, ages, and treatments groups revealed that h3a is the most stable gene whereas gapdh and tuba are the least stable genes, even being considered two constitutive genes.

Effects of Experimental Lead Exposure on Testis of the Chestnut Capped Blackbird Chrysomus ruficapillus

Lead (Pb) effects on testis histology, as well as sperm quality and oxidative status were evaluated in male Chestnut Capped Blackbird (Chrysomus ruficapillus). Wild blackbirds were captured, immediately sampled (field group) or kept in captivity and treated with a single intraperitoneal injection of saline solution (control) or saline solution with Pb acetate (50 or 100 mg/kg Pb). Seven days after injection, whole blood, ductus deferens and testis samples were collected. Increased Pb concentrations were observed in whole blood and testis of Pb-exposed blackbirds with respect to those from field and control blackbirds. Sperm cells of Pb-exposed blackbirds showed loss of membrane integrity, mitochondrial functionality, and DNA integrity. Also, oxidative damage was observed in testis of blackbirds injected with 100 mg/kg Pb. These findings indicate that Pb is accumulated in testis of C. ruficapillus, inducing severe morphological and biochemical injury that can compromise the reproductive performance of male blackbirds. Although the exposure scenario (Pb acetate, high dosage and intraperitoneal injection) tested in the present study would likely not occur in the wild, it was adequate to show potential and relevant toxic effects of Pb in wild birds.

Effects of exposure to cadmium in sperm cells of zebrafish, Danio rerio

Cadmium is a natural element found in the earth’s crust; it is usually associated with other metals, but due to the impacts caused by human activity, its concentration has increased in the aquatic environment. This metal may damage aquatic animal reproduction, decreasing the rate of fertilization of organisms such as fish. Thus, this study aimed to evaluate the in vitro toxicity of different concentrations of cadmium (0 (control), 0.5, 5, and 10 μg/L) using sperm cells of model organism zebrafish, Danio rerio. Structural parameters, including integrity and fluidity of the plasma membrane, concentration of oxygen species, mitochondrial function and DNA fragmentation were measured by flow cytometry. The following sperm movement parameters were also measured using the computer assisted sperm analysis (CASA) system: motility, time of motility, curvilinear velocity, average path velocity and straight line velocity in μm/s. Significant effects were observed on path speed, straight speed, curvilinear velocity, motility time, progressive and total motility, and plasma and DNA integrity. The results showed that cadmium can negatively affect some reproductive parameters in D. rerio, which may reduce the fertility rate of these animals.

Maternal Transfer of Bisphenol A During Nursing Causes Sperm Impairment in Male Offspring

The health effects of environmental chemicals on animals and humans are of growing concern. Human epidemiological and animal study data indicate that reproductive disorders and diseases begin early during prenatal and postnatal development. An increase of human male reproductive disturbance in the past several decades was associated to chemicals called endocrine disruptors (ED). Bisphenol A (BPA) is a ubiquitous organic environmental contaminant with ED activity. This study verified the effect of BPA exposure via breast milk during the lactation (early postnatal) period in male mice. Dams were exposed to oral BPA (300, 900, and 3000 µg/kg/BW/day) during the breastfeeding period (21 days). BPA at all concentrations significantly impaired sperm parameters in adult mice (8 months old), but mitochondrial functionality was more affected at BPA 3000. The acrosome membrane parameter was affected by BPA concentrations from 900 to 3000, and DNA integrity showed pronounced impairment at BPA 900 and 3000. BPA 3000 treatment also induced testicular degeneration and complete aplasia in some seminiferous tubules. Testicular oxidative damage was observed, and the total antioxidant capacity was impaired in BPA 900 and 3000 treatment groups. Taken together, the present study demonstrated long-term adverse effects of BPA in male mice, including reduced sperm quality, antioxidant capacity, and changes in testicular tissue. Our results clearly demonstrate the danger of BPA transferred via lactation on sperm quality registered even after a long time-elapsed from exposure to this harmful chemical.

The effects of osmolality on sperm quality in Jenynsia multidentata (Cyprinodontiformes: Anablepidae)

Sperm quality tests on fish are classically used for evaluating cryopreservation procedures, and they are also promising to assess aquatic toxicity and biomarkers of xenobiotic effects on reproduction. Osmotic shock from the storage medium is one of the main factors affecting sperm quality during evaluation. Thus, the objective of this study was to evaluate the effects of different osmolalities (240-460 mOsm/kg) for at least 4 days on the sperm quality parameters of the viviparous fish Jenynsia multidentata. The level of significance was (P < 0.05). The plasma osmolality of J. multidentata is 326 ± 3.9 mOsm/kg. The motility of fresh semen was higher in osmolalities of 280 and 300 mOsm/kg but did not differ between osmolalities from 240 to 320 mOsm/kg. Above 380 mOsm/kg, the motility observed was 0%. Over the time period studied motility increased with increasing osmolality, and the most constant and long-lasting rates were between 300 and 320 mOsm/kg. On the 4th day of evaluation, higher membrane integrity rates were observed between 280 and 360 mOsm/kg, higher mitochondrial membrane potential was observed between 300 and 460 mOsm/kg, and higher DNA integrity rates were observed between 260 and 380 mOsm/kg. Moreover, osmolalities ≥460 and ≤240 resulted in the lowest motility and DNA integrity levels. Over 4 days, the plasma membrane integrity was significantly lower at ≤260 and ≥400 mOsm/kg, and the mitochondrial membrane potential was significantly lower only in osmolalities ≤240 mOsm/kg. Therefore, we conclude that for sperm quality preservation in J. multidentata, an osmolality of 300-320 mOsm/kg of the most suitable diluent is necessary. Furthermore, we conclude that the storage of sperm in a hyposmotic (<260 mOsm/kg) or hyperosmotic (>400 mOsm/kg) solution affects not only motility but also other sperm quality parameters.

Effect of glyphosate on the sperm quality of zebrafish Danio rerio

Glyphosate is a systemic, non-selective herbicide widely used in agriculture worldwide. It acts as an inhibitor of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase by interrupting the synthesis of essential aromatic amino acids. This pathway is not present in animals, although some studies have shown that the herbicide glyphosate can affect fish reproduction. In this study, the effect of glyphosate on sperm quality of the fish Danio rerio was investigated after 24 and 96 h of exposure at concentrations of 5mg/L and 10mg/L. The spermatic cell concentration, sperm motility and motility period were measured employing conventional microscopy. The mitochondrial functionality, membrane integrity and DNA integrity were measured by fluorescence microscopy using specific probes. No significant differences in sperm concentration were observed; however, sperm motility and the motility period were reduced after exposure to both glyphosate concentrations during both exposure periods. The mitochondrial functionality and membrane and DNA integrity were also reduced at the highest concentration during both exposure periods. The results showed that glyphosate can induce harmful effects on reproductive parameters in D. rerio and that this change would reduce the fertility rate of these animals.

Fluorescent transgenic zebrafish as a biosensor for growth-related effects of methyl parathion

Transgenic fish models are potential alternative subjects in toxicological studies, since they can provide in vivo information on the deleterious effects of different substances. Here, we used a transgenic zebrafish (Danio rerio) lineage, which expresses a destabilized fluorescent protein (DsRED) driven by the myosin light chain promoter (Mylz2), in order to propose a new research tool for environmental biomonitoring. For validating the MYO-RED lineage, we exposed fish to the organophosphorated pesticide methyl parathion (MP). The effect of MP on fish growth was assessed by evaluating weight, length, condition factor and muscle fiber diameter. All factors suffered reduction at both tested concentrations (0.13μM and 13μM of MP). Similarly, fluorescence intensity decreased in a concentration-dependent manner, suggesting muscle protein catabolism. However, DsRED gene expression lowered only at the higher MP concentration. Results indicate that the MYO-RED transgenic zebrafish is an interesting model for detecting the growth-related effects of pollutants. Destabilized proteins such as reporter genes are apparently sensitive biomarkers, since effects were observed even at the lower, environmentally acceptable concentration. Therefore, this transgenic fish is a promising candidate model for sensitive, fast, and easy environmental monitoring.