- Jorge Herkovits is an Argentine ecotoxicologists, president of the PROSAMA Foundation, professor of ecology and envi... moreJorge Herkovits is an Argentine ecotoxicologists, president of the PROSAMA Foundation, professor of ecology and environmental health and member of the Argentinean Academy of Environmental Sciences, whose work has contributed to a better understanding of the adverse effects of environmental stressors in the early life stages, the establishment of toxicity criteria for a sustainable management of water quality and the complex interrelation between living organisms and the environment from an evolutionary perspective.edit
Although the relationship between environmental toxicity and infectious diseases is poorly studied, it is probably more common than is recognized, since the chemical substances could be associated with pre-existing pathologies. For... more
Although the relationship between environmental toxicity and infectious diseases is poorly studied, it is probably more common than is recognized, since the chemical substances could be associated with pre-existing pathologies. For example, some conditions that influence the progression of COVID-19 could have toxicological causes such as cancer, endocrine, neurological, and inflammatory disorders, kidney failure, etc. This contribution highlights that SARS-CoV-2 and some high-volume organic and inorganic chemicals could also exert dysfunctions in the same homeostatic regulators such as HIF-1 and ACE2, with a potential synergistic effect that could affect the severity of COVID-19. This potential synergy is illustrated with adverse effects acquired through bioassays performed with free-living vertebrate embryos indicating that their use as sentinel organisms for environmental contamination could be beneficial both for the ecosystem and human health.
Research Interests:
Research Interests:
The water quality based toxics control is essential to evaluate the aggregate toxicity, bioavailability as well as for the detection and/or prediction of ecological impacts. Reconquista River valley is situated in the north area of Great... more
The water quality based toxics control is essential to evaluate the aggregate toxicity, bioavailability as well as for the detection and/or prediction of ecological impacts. Reconquista River valley is situated in the north area of Great Buenos Aires with a population of three million inhabitants. The river is loaded with industrial and municipal waste water. In the present preliminary study the authors report the toxicity found in surface water at a 6 sample stations (including a reference point and a stream) all of them downstream from mixing zone areas. The ecotoxicological study was performed with three native species (Bufo arenarum embryos, Cnesterodon decemmaculatus and a species of shrimp collected in an upstream reference site) during a 7 day renewal toxicity test conducted with 10 individuals (by duplicate) for each condition plus control. The results point out that the Bufo arenarum embryos test is the most sensitive to toxic substances as well as the better adapted species to the changing physico-chemical conditions of this river. The results obtained with embryos, expressed in Acute and Chronic Toxicity Units (according USEPA) range between <0.3--2 and <1--5 respectively (recommended magnitudes for industrial effluents according USEPA: 0.3 and 1 toxicity units respectively). Therefore, the toxicitymore » found in Reconquista River ecosystem was up to 6 times higher than the maximal value recommended for industrial effluents. It is noteworthy that in the place where toxicity starts to rise, a large number of dead fishes were found and from that place downstream, no macroorganisms were found in the river. The results confirm the high sensitivity of Bufo arenarum embryos for continental waters ecotoxicological studies and the possibility of using this test as a short-term chronic toxicity method for water quality-based toxics control.« less
Research Interests:
Research Interests:
Research Interests:
The protective effect of zinc against slight teratogenical action, exerted by low cadmium concentrations, was evaluated in Bufo arenarum embryos treated simultaneously with both cations or preincubated with Zn before Cd treatment. Data on... more
The protective effect of zinc against slight teratogenical action, exerted by low cadmium concentrations, was evaluated in Bufo arenarum embryos treated simultaneously with both cations or preincubated with Zn before Cd treatment. Data on survival, malformations, and delay in development pointed out that Zn could prevent the deleterious effects of Cd in previous and simultaneous treatments with that heavy metal.
Research Interests: Chemistry, Morphogenesis, Medicine, Female, Animals, and 10 moreHeavy Metal, Male, Anura, Zinc, Cadmium, Gills, Teratogens, Indexation, Embryos, and Cadmium Poisoning
Research Interests: Environmental Science, Chemistry, Argentina, Public Health, Environmental Pollution, and 15 moreMedicine, Multidisciplinary, Cities, Humans, Animals, Ground Water, Human health, Bufonidae, Embryonic Development, Industrial Waste, Acute Toxicity, Reference Values, Embryos, Soil Pollutants, and Chronic Toxicity
Test of early life stages are very sensitive to toxic effects and moreover a good predictive correlation between embryo-larval survival and independent ecological parameters such as species richness and diversity have been established.... more
Test of early life stages are very sensitive to toxic effects and moreover a good predictive correlation between embryo-larval survival and independent ecological parameters such as species richness and diversity have been established. The main purpose of this preliminary study is to report that Bufo arenarum embryos are very sensitive to contaminants from a variety of sources such as leachates, industrial effluents, surface and ground water. The toxicity of 30 samples (five from each category plus controls of surface and ground water from reference places) was evaluated during a 14 day renewal toxicity test at 20 C, conducted with 10 embryos (by triplicate) from stage 23--25 onwards using six concentrations (V/V) of each sample of Holtfreter`s solution. For industrial effluents and leachates the results range from a concentration of 0.6% resulting in 24hs LC100 up to a sample which exert 20% of lethality after 14 days of treatment. The survival of controls and in samples from reference places was over 90% for 7 days and over 80% for 14 days. The results with Bufo arenarum embryos confirm that a 7 day Short-term Chronic Toxicity Test is appropriate for toxicity screening of industrial effluents (as it was established by EPA formore » whole effluent toxicity test for aquatic life protection performed with other species) as well as for leachates. On the other hand, for freshwater (surface and ground), it is convenient to extend the exposure period until 14 days in order to record situations of low, but significant levels of toxicity, which could be of particular value for surface as well as ground water quality criteria.« less
Research Interests:
Research Interests:
Research Interests:
Research Interests: Environmental Remediation, Ecotoxicology, Toxicology, Biology, Environmental Chemistry, and 15 moreRisk assessment, Medicine, Multidisciplinary, Embryo, Animals, Amphibian, Amphibians, Nickel, Fresh water, Biological markers, Risk Assessment, Toxicity Tests, Embryos, Environmental Exposure, and Adverse effect
Although the relationship between environmental toxicity and infectious diseases is poorly studied, it is probably more common than is recognized, since the chemical substances could be associated with pre-existing pathologies. For... more
Although the relationship between environmental toxicity and infectious diseases is poorly studied, it is probably more common than is recognized, since the chemical substances could be associated with pre-existing pathologies. For example, some conditions that influence the progression of COVID-19 could have toxicological causes such as cancer, endocrine, neurological, and inflammatory disorders, kidney failure, etc. This contribution highlights that SARS-CoV-2 and some high-volume organic and inorganic chemicals could also exert dysfunctions in the same homeostatic regulators such as HIF-1 and ACE2, with a potential synergistic effect that could affect the severity of COVID-19. This potential synergy is illustrated with adverse effects acquired through bioassays performed with free-living vertebrate embryos indicating that their use as sentinel organisms for environmental contamination could be beneficial both for the ecosystem and human health.
1. The development was studied of embryos in which dramatic deformations were produced by physical means during the period in which they are highly susceptible to teratogenesis. 2. In spite of the deformations histogenesis as a whole as... more
1. The development was studied of embryos in which dramatic deformations were produced by physical means during the period in which they are highly susceptible to teratogenesis. 2. In spite of the deformations histogenesis as a whole as well as cytodifferentiation seems to be normal. 3. With only few exceptions the embryos showing dramatic deformations ultimately recover a normal morphology. 4. The shape recovering capacity raises the question whether morphogenesis and shape are not in fact more or less independent phenomena.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
SEM studies on amphibian gastrulation have shown the overall shape and arrangement of several cell types (e. g. bottle cells, mesodermal cells, ectodermal cells, etc. ) as well as the cellular activities in the blastocoel cavity during... more
SEM studies on amphibian gastrulation have shown the overall shape and arrangement of several cell types (e. g. bottle cells, mesodermal cells, ectodermal cells, etc. ) as well as the cellular activities in the blastocoel cavity during archenteron floor descent. The main purpose of the present communication is to show the internal structure of Bufo arenarum gastrula as viewed in sagittal dissection at the stage when the ventral blastoporal groove starts forming.Material and Methods: Bufo arenarum gastrula were fixed in 2, 5% glutaraldehyde in phosphate buffer for 2, 5 hrs. After removing the vitelline membrane the embryos were fractured and then dissected near the mid-sagittal plane. The specimens were dehydrated through an acetone series, dried according to the critical point technique, coated with evaporated gold-platinum and observed in a Jeol JSM-U3 scanning electron microscope operated at 5-15 kW.Observations: The internal structure of a Bufo arenarum gastrula at the ventral blastoporal groove stage is illustrated in Fig. 1. Blastocoel cavity (B), internal endodermal yolky cells (Y), prospective ectoderm (PE), archenteron (A), dorsal blastoporal lip (L), ventral blastoporal groove (V).
Research Interests:
As a result of their aquatic embryonic and larval development, many species of amphibians are potentially affected by adverse environmental conditions. In this study the possibility of reducing the lethal effect of aluminum (ALC13,... more
As a result of their aquatic embryonic and larval development, many species of amphibians are potentially affected by adverse environmental conditions. In this study the possibility of reducing the lethal effect of aluminum (ALC13, Mallinckrodt) in Bufo arenarum embryos by means of simultaneous zinc (ZnSO4) treatment is reported. The aluminum hazard was evaluated in a 7 day renewal toxicity testing study conducted with batches of 10 individuals (by quadruplicate) in six concentrations of aluminum plus the control at 20 C. The pH of the experimental solutions were measured. The LC100 expressed as Al(3 +) mg/L at 24 and up till 168 hours of treatment were 0.9 (the pH of the solution was 6.2 while in control Holtfreter solution the pH was 6.8). Therefore, aluminum exert a lethal effect on amphibian embryos in concentrations which reduce only slightly the pH of the maintaining solution. The lethal effect of aluminum could be reduced 100% by means of simultaneous treatment with 2 mg Zn(2 +)/L. The results point out the high sensibility of the amphibian embryos to aluminum (LC100/24hs:0.9mg Al(3 +)/L) and therefore, episodic increases in dissolved aluminum, usually concomitant with surface water pH decreases, could produce very harmful effects during embryonic stagesmore » of amphibians. The noteworthy beneficial effect of zinc against the lethal effect of aluminum could be of practical value in reducing the harmful effects exerted by aluminum. The conspicuous Al-Zn antagonism points out the need of biological test systems for recording the integrated effects of substances released to the environment.« less
Research Interests:
Although crustaceans, fish and algae are receiving increasing attention as test organisms in short-term tests, it is important to note that other species could be more than order of magnitude more susceptible la xenobiotics and therefore,... more
Although crustaceans, fish and algae are receiving increasing attention as test organisms in short-term tests, it is important to note that other species could be more than order of magnitude more susceptible la xenobiotics and therefore, profitable for toxicity screening for a proper protection of the diversity and complexity of the ecosystems. In this report the sensitivity of Bufo arenarum (embryos) and Cnesterodon decemmaculatus to aluminum (AIC1 3) is evaluated in a renewal toxicity test system at 20 C and informed as LC100, LC50 and NOEC for 24 and up till 96 hours of exposure (acute Toxicity Profile -- TPa -- for aluminum). The tests with fish were conducted maintaining 10 individuals in 1 liter of EPA water (by quadruplicate) in six concentration of Al(3+). The pH of the experimental solutions were measured. The LC100, LC50 and NOEC for fishes expressed in Al(3+) mg/L were: 7.5 (the pH of this solutions was 4.3), 7 and 6 at 24 as well as for 48, 72 and 96 hours of exposure, while for Bufo arenarum embryos the LC100, LC50 and NOEC were 0.9 (pH 6.2), 0.6 and 0.1 for 24 hours and up till 96 hours of exposure. Therefore, Bufo arenarum (embryos) more » seems to be about one order of magnitude more sensitive than the solution is adjusted from 4.3 to 6.2, no lethal effect on fish was registered. The TPa shows that the most toxic period is within the first 24 hours of exposure while on the other hand in fishes as well as in amphibian embryos the LC50 is closer to the LC100 value that to NOEC and therefore, exposure around LC50 concentrations, in the case of aluminum, represents a risk for the whole population. « less
Research Interests:
Research Interests:
Research Interests:
ABSTRACT 1. The development was studied of embryos in which dramatic deformations were produced by physical means during the period in which they are highly susceptible to teratogenesis. 2. In spite of the deformations histogenesis as a... more
ABSTRACT 1. The development was studied of embryos in which dramatic deformations were produced by physical means during the period in which they are highly susceptible to teratogenesis. 2. In spite of the deformations histogenesis as a whole as well as cytodifferentiation seems to be normal. 3. With only few exceptions the embryos showing dramatic deformations ultimately recover a normal morphology. 4. The shape recovering capacity raises the question whether morphogenesis and shape are not in fact more or less independent phenomena.
Research Interests:
Research Interests:
The acute and chronic toxicity of bisphenol A (BPA) was evaluated on the common South American toad Rhinella arenarum embryos and larvae by means of continuous and pulse exposure treatments. Embryos were treated continuously from early... more
The acute and chronic toxicity of bisphenol A (BPA) was evaluated on the common South American toad Rhinella arenarum embryos and larvae by means of continuous and pulse exposure treatments. Embryos were treated continuously from early blastula (S.4) up to complete operculum (S.25), during early larval stages and by means of 24 h pulse exposures of BPA in concentrations ranging between 1.25 and 40 mg L(-1) , in order to evaluate the susceptibility to this compound in different developmental stages. For lethal effects, S.25 was the most sensitive and gastrula was the most resistant to BPA. The Teratogenic Index for neurula, the most sensitive embryonic stage for sublethal effects was 4.7. The main morphological alterations during early stages were: delayed or arrested development, reduced body size, persistent yolk plug, microcephaly, axial/tail flexures, edemas, blisters, waving fin, underdeveloped gills, mouth malformations, and cellular dissociation. BPA caused a remarkable narcotic effect from gill circulation stage (S.20) onwards in all the organisms exposed after 3 h of treatment with 10 mg L(-1) BPA. After recovering, the embryos exhibited scarce response to stimuli, erratic or circular swimming, and spasmodic contractions from 5 mg L(-1) onwards. Our results highlight the lethal and sublethal effectsof BPA on R. arenarum embryos and larvae, in the last case both at structural and functional levels.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Although several theoretical approaches consider general methods for dealing with shape, recent observations and experimental data show that embryos exhibit marked changes in the properties of the biological material involved in shape... more
Although several theoretical approaches consider general methods for dealing with shape, recent observations and experimental data show that embryos exhibit marked changes in the properties of the biological material involved in shape development and shape regulation capacity. In vivo experiments have shown that the amphibian embryo gradually develops from a situation in which it is not able to maintain its shape to one in which it can not only maintain its shape but also possesses a maximal tolerance towards deformation together with a maximal shape regulation capacity. So far two especially clear conclusions have emerged: (i) the form of the embryo appears to be determined by cell activities intrinsic to each stage, and (ii) the morphogenetic programme can be executed normally within wide limits notwithstanding dramatic deformations of the embryo during quite a long period. Thus the hypothesis may be advanced that shape and morphogenesis to some extent become independent phenomena during embryonic development.
Research Interests:
In this paper, data are presented on the characterization of uterus draining lymph nodes (UDLN) B and T lymphocytes of virgin rats at estrus (E) and diestrus (D). We established that the T/B lymphocyte relationship in the UDLN is less... more
In this paper, data are presented on the characterization of uterus draining lymph nodes (UDLN) B and T lymphocytes of virgin rats at estrus (E) and diestrus (D). We established that the T/B lymphocyte relationship in the UDLN is less than one at estrus and more than one at diestrus. This is due to a decrease in the percentage and in the total number of mature T cell population in association with a decrease in the percentage of the OX8 subset in the UDLN at estrus. This situation may be related to an increase in estrogens known to produce thymic involution. These changes were not observed when we studied peripheral (popliteal) lymph nodes. The changes observed in the UDLN T cell population at estrus could be under hormonal control and we think that this condition may be important to prepare the immune system for an eventual pregnancy.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Evolutionary Biology, Physical Chemistry, Coevolution, Biology, Ecology, and 15 moreEnvironmental Pollution, Medicine, Environmental Change, Environmental Sciences, Fossils, Animals, Living fossil, Biological evolution, Organism, Embryonic Development, Oxygen, Biological markers, Living Fossil, Environment, and Medical and Health Sciences
Research Interests: Ecotoxicology, Biology, Medicine, Environmental Sciences, Female, and 5 moreAnimals, Cadmium, CHEMICAL SCIENCES, Bufo, and Embryos
Microcystin-LR (MC-LR) is a cyanobacterial toxin generated by the organism Microcystis aeruginosa. Although the hepatotoxicity of this chemical has been characterized, the potential developmental toxicity in vertebrates has not been well... more
Microcystin-LR (MC-LR) is a cyanobacterial toxin generated by the organism Microcystis aeruginosa. Although the hepatotoxicity of this chemical has been characterized, the potential developmental toxicity in vertebrates has not been well studied. The purpose of this study was to elucidate the effects of this toxin on the in vivo and in vitro development of mammals and the development of an Anuran (toad). Initial acute toxicity experiments with female CD-1 mice were accomplished with MC-LR administered i.p. in saline. Lethality occurred at 128 and 160 microg kg (-1) and histopathology revealed massive hepatic necrosis with diffuse hemorrhage. Developmental toxicity studies were done with MC-LR administered i.p. for 2-day periods: gestation days 7-8, 9-10 or 11-12. Doses used ranged from 2 to 128 microg kg(-1). On gestation day 17, fetuses were weighed and analyzed for gross morphological and skeletal defects. No treatment-related differences were seen in litter size, viability, weight or the incidence of anomalies. Groups of dams dosed with 32-128 microg kg(-1) on gestation days 7-8, 9-10 or 11-12 were allowed to give birth and the growth and development of their pups were followed postnatally. There were no significant effects noted in the offspring of the treated dams. Neurulation-staged CD-1 mouse conceptuses were exposed to 50-1000 nM MC-LR in whole embryo culture for 24 h. No significant increase in abnormalities or developmental delays was observed. Finally, exposure of the developing toad. Bufo arenarum was done from stage 17 (tail bud) for 10 days at concentrations of 1-20 mg l(-1). No effect on morphological development or survival was noted in any exposed groups. These data indicate that microcystin does not appear to affect development adversely in the mouse (in vivo or in vitro) or the toad at the doses and exposure parameters used.
Research Interests: Andrology, Biology, Cyanobacteria, Enzyme Inhibitors, Medicine, and 15 moreMice, Female, Animals, Cyclic peptides, Microcystins, Survival Rate, Fetus, Lethal Dose, Offspring, Gestation, Applied Toxicology, Developmental toxicity, Maternal Exposure, Pharmacology and pharmaceutical sciences, and In Vitro Techniques
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Abstract: The acclimation possibilities to copper in Bufo arenarum embryos was evaluated by means of three different low level copper exposure conditions during 14 days. By the end of the acclimation period the copper content in control... more
Abstract: The acclimation possibilities to copper in Bufo arenarum embryos was evaluated by means of three different low level copper exposure conditions during 14 days. By the end of the acclimation period the copper content in control embryos was 1.04 ± 0.09 µg.g-1 (wet weight) while in all the acclimated embryos a reduction of about 25% of copper was found. Thus copper content could be considered as a biomarker of low level exposure conditions. Batches of 10 embryos (by triplicate) from each acclimation condition were challenged with three different toxic concentrations of copper. As a general pattern, the acclimation protocol to copper exerted a transient beneficial effect on the survival of the Bufo arenarum embryos. The acclimation phenomenon could be related to the selection of pollution tolerant organisms within an adaptive process and therefore the persistence of information within an ecological system following a toxicological stressor.