- Ctra. Majadahonda - Pozuelo Km 2
E - 28220 Majadahonda (Madrid)
Tel.: +34 918 223 540 - +34 918 223 540
Myriam Catalá
Instituto de Salud Carlos III, National Centre for Environmental Health, Department Member
- Prof. Myriam Catala holds a Ms. in Chemistry and a PhD Biochemistry and Molecular Biology by Complutense University a... moreProf. Myriam Catala holds a Ms. in Chemistry and a PhD Biochemistry and Molecular Biology by Complutense University at Madrid. From 2012 she holds tenure as Associate Professor in Cell Biology in URJC. On December 1st 2015 she was designated as head of the Environmental Toxicology Area of the Spanish National Center for Environmental Health. She has published 34 articles in prestigious international journals and 3 chapters of international books. The mean impact factor of the journals is 2.859, belonging most of them to the first quartile of the JCR. Her current h factor is 13 according to Scopus and 16 according to Google Scholar. She has been the main researcher of 2 projects funded by companies and have participated as researcher in 6 projects funded in competitive calls, both by public entities (MEC, FIS, FISCAM) and private companies (Mutua Madrileña). She holds two biotechnological patents and has registered a third one which is pending. She been awarded with 2 “Sexenios” by the Spanish Agency of Research Assessment in recognition for her investigation activity. Her doctorate dealt with the mechanisms of response of liver to oxidative stress in endotoxic shock. As post-doctoral fellow she investigated cancer proteomics and later she worked on tissue engineering and the development of biodegradable vascular grafts for newborns. During her tenure-track she moved her interests to the application of biochemical and cell biology biomarkers to Ecotoxicology, the development of biologically and ecologically relevant testing methods and the characterization of the environmental pollution by emerging substances (pharmaceuticals and drugs of abuse). She approached the study of lichen symbiosis and lichen microalgae tolerance to abiotic stress using cell biology techniques and she is involved in the assessment of lichen microalgae as source of high added value products including anticancer drugs. Recently, she has been designated as Head of the Environmental Toxicology Area of the National Center of Environmental Health of the National Institute of Health Carlos III:edit
- Argelia Castañoedit
This paper investigates the elimination of drugs of abuse fromsix different chemical classes and their metabolites in natural fluvial waters (nearby the output of a sewage system). Mineralization of these substances and toxicological... more
This paper investigates the elimination of drugs of abuse fromsix different chemical classes and their metabolites
in natural fluvial waters (nearby the output of a sewage system). Mineralization of these substances and toxicological
characterization before and after treatment by a heterogeneous photo-Fenton systemhas been evaluated.
This advanced oxidation technologywas able to significantly reduce the concentration of the drugs of abuse in all
the tested conditions (different hydrogen peroxide and catalyst loadings). However, toxicological analyses
measured as inhibition of fern spore mitochondrial activity, showed only a complete elimination of acute and
chronic toxicity when a higher solid catalyst loading was used (0.6 g/L). A lower catalyst loading of 0.2 g/L was
not enough for toxicity elimination. These results evidence the need for combining toxicological tests and
chemical analyses in order to establish the effectiveness of thewater treatment technologies based on advanced
oxidation processes.
in natural fluvial waters (nearby the output of a sewage system). Mineralization of these substances and toxicological
characterization before and after treatment by a heterogeneous photo-Fenton systemhas been evaluated.
This advanced oxidation technologywas able to significantly reduce the concentration of the drugs of abuse in all
the tested conditions (different hydrogen peroxide and catalyst loadings). However, toxicological analyses
measured as inhibition of fern spore mitochondrial activity, showed only a complete elimination of acute and
chronic toxicity when a higher solid catalyst loading was used (0.6 g/L). A lower catalyst loading of 0.2 g/L was
not enough for toxicity elimination. These results evidence the need for combining toxicological tests and
chemical analyses in order to establish the effectiveness of thewater treatment technologies based on advanced
oxidation processes.
Research Interests:
Bioassays constitute a tool for pollution analysis providing a holistic approach and high-quality indication of the toxicity. Microbioassays allow evaluating the toxicity of many samples, implying lower costs and enabling routine... more
Bioassays constitute a tool for pollution analysis providing a holistic approach and high-quality indication
of the toxicity. Microbioassays allow evaluating the toxicity of many samples, implying lower costs
and enabling routine monitoring and pollution control. But tests conducted so far are limited to the use
of a small number of taxa. Lichens are excellent bioindicators of pollution with great ecological
significance. Studies show that the phycobiont is more sensitive to pollutants than the mycobiont.
Phycobiont have features such as adaptation to anhydrobiosis and relatively rapid growth in vitro,
making them suitable for microbioassays. Our aim is to determine the sensitivity of phycobionts to the
pharmaceutical micropollutants carbamazepine and diclofenac as a preliminary step for the development
of a toxicity microbioassay based on phycobionts. Optical dispersion and chlorophyll autofluorescence
were used as endpoints of toxicity on two algal species showing that suspensions present cyclic
and taxon specific patterns of aggregation. Trebouxia TR9 suspensions present a very high grade of
aggregation while Asterochloris erici cells do not. Both micropollutants alter optical properties of the
suspensions of both species. No significant alteration of chlorophyll autofluorescence by carbamazepine
is observed. A. erici chlorophyll autofluorescence is extremely sensitive to diclofenac but the effect is not
dependent on the drug concentration or on the time of exposure. Differently, TR9 only shows punctual
chlorophyll alterations. Fluctuations in optical dispersion may indicate changes in the population
structure of the species, including reproductive strategy. A. erici seems more sensitive to micropollutants,
is better characterized and is available from commercial collections.
of the toxicity. Microbioassays allow evaluating the toxicity of many samples, implying lower costs
and enabling routine monitoring and pollution control. But tests conducted so far are limited to the use
of a small number of taxa. Lichens are excellent bioindicators of pollution with great ecological
significance. Studies show that the phycobiont is more sensitive to pollutants than the mycobiont.
Phycobiont have features such as adaptation to anhydrobiosis and relatively rapid growth in vitro,
making them suitable for microbioassays. Our aim is to determine the sensitivity of phycobionts to the
pharmaceutical micropollutants carbamazepine and diclofenac as a preliminary step for the development
of a toxicity microbioassay based on phycobionts. Optical dispersion and chlorophyll autofluorescence
were used as endpoints of toxicity on two algal species showing that suspensions present cyclic
and taxon specific patterns of aggregation. Trebouxia TR9 suspensions present a very high grade of
aggregation while Asterochloris erici cells do not. Both micropollutants alter optical properties of the
suspensions of both species. No significant alteration of chlorophyll autofluorescence by carbamazepine
is observed. A. erici chlorophyll autofluorescence is extremely sensitive to diclofenac but the effect is not
dependent on the drug concentration or on the time of exposure. Differently, TR9 only shows punctual
chlorophyll alterations. Fluctuations in optical dispersion may indicate changes in the population
structure of the species, including reproductive strategy. A. erici seems more sensitive to micropollutants,
is better characterized and is available from commercial collections.
Research Interests:
• Benzoylecgonine toxicity was tested on zebrafish embryo/larva and fern spores. • No effects on zebrafish embryos or larvae toxicity endpoints were observed. • Benzoylecgonine altered mitochondrial activity and DNA levels in fern spores.... more
• Benzoylecgonine toxicity was tested on zebrafish embryo/larva and fern spores. • No effects on zebrafish embryos or larvae toxicity endpoints were observed. • Benzoylecgonine altered mitochondrial activity and DNA levels in fern spores. • Phytotoxicity was evidenced at environmentally relevant concentrations. • Anthropogenic dispersed allelochemicals may pose unacceptable environmental risks. a b s t r a c t Several studies have found cocaine and its main active metabolite benzoylecgonine (BE) in the aquatic environment and drinking water, derived from its consumption by humans as well as the inability of water treatment processes to eliminate it. A few studies have already investigated the ecotoxicology of BE to aquatic invertebrates, but none has still addressed the effects of BE on aquatic vertebrates or vascular plants. The goal of this publication is to provide information on the toxicity of environmental concentrations of BE during animal and vascular plant development, in order to contribute to a better understanding of the potential risk of this substance for the environment. BE induced alterations in mito-chondrial activity and DNA levels of fern spores at environmental concentrations (1 ng L −1), which could disrupt gametophyte germination. However, BE at concentrations ranging from 1 ng L −1 to 1 mg L −1 did not disturb morphogenesis, hatching, heartbeat rate or larval motility in a zebrafish embryo–larval model. Adverse effects on ferns agree with the allelophathic role described for alkaloids and their unspecific interference with plant germination. Therefore, the anthropogenic dispersion of alkaloid allelochemicals may pose a risk for biodiversity and irrigated food production that should be further investigated.
Research Interests:
Research Interests: Herpetology, Ornithology, Conservation Biology, Environmental Toxicology, Wildlife Biology, and 18 moreEcotoxicology, Ecology, Water Treatment, Mammalogy, Environmental Monitoring, Rivers, Risk assessment, Multidisciplinary, Spain, Water Supply, Caffeine, Waste water treatment, Nicotine, Drinking Water, Surface Water, Water quality monitoring, Risk Assessment, and Pharmaceutical preparations
Research Interests:
Venlafaxine hydrochloride is a structurally novel antidepressant. Its occurrence in surface waters and drinking water has only been reported in recent works. The aim of this work is to assess the acute and chronic sublethal toxicity of... more
Venlafaxine hydrochloride is a structurally novel antidepressant. Its occurrence in surface waters and drinking water has only been reported in recent works. The aim of this work is to assess the acute and chronic sublethal toxicity of venlafaxine in relevant taxa of riparian ecosystems. We used the fern Polystichum setiferum during the critical life stage of development.
Research Interests:
Abstract Background and Aims The aquatic moss Fontinalis antipyretica requires a slow rate of dehydration to survive a desiccation event. The present work examined whether differences in the dehydration rate resulted in corresponding... more
Abstract Background and Aims The aquatic moss Fontinalis antipyretica requires a slow rate of dehydration to survive a desiccation event. The present work examined whether differences in the dehydration rate resulted in corresponding differences in the production of reactive oxygen species (ROS) and therefore in the amount of cell damage.
Research Interests:
Research Interests:
The development of efficient bioassays is a necessary step for cost-effective environmental monitoring and evaluation of novel decontamination technologies. Marine Vibrio fischeri kits have demonstrated to be extremely sensitive but lack... more
The development of efficient bioassays is a necessary step for cost-effective environmental monitoring and evaluation of novel decontamination technologies. Marine Vibrio fischeri kits have demonstrated to be extremely sensitive but lack of ecological relevance, especially when assessing impacts on freshwater higher organisms. A novel riparian are fern spore microbioassay could merge higher ecological relevance and reduced costs. The aim of this work is the comparative evaluation of the V.
Research Interests:
Research Interests:
The presence of pharmaceuticals in surface and drinking water has been evidenced in numerous studies. Despite representing one of the most common consumption sources, to the best of our knowledge, this is the first report on the presence... more
The presence of pharmaceuticals in surface and drinking water has been evidenced in numerous studies. Despite representing one of the most common consumption sources, to the best of our knowledge, this is the first report on the presence of pharmaceutical compounds in bottled mineral water. Pollution of these sources not only could pose a serious human health risk, but would also warn about the quality of the water in our aquifers, a vital and vulnerable source of water, essential for the future water supply.
Research Interests:
Interest in the presence of pharmaceuticals in wastewater, in the water of our rivers and, to a lesser extent, in our drinking water, has been growing in recent decades. Many of these substances, currently classified as “emerging... more
Interest in the presence of pharmaceuticals in wastewater, in the water of our rivers and, to a lesser extent, in our drinking water, has been growing in recent decades. Many of these substances, currently classified as “emerging pollutants”, are biologically active compounds and continuously released in effluents. As sewage treatment plants (STPs) are not adequately equipped to eliminate all of these substances completely, some are discharged directly into rivers.
Research Interests:
Concentrations of pharmaceutically active compounds (PhACs) in the order of ngL− 1 to μgL− 1 have been reported worldwide in waste, fluvial and even drinking water, raising concern about the efficacy of the currently employed waste water... more
Concentrations of pharmaceutically active compounds (PhACs) in the order of ngL− 1 to μgL− 1 have been reported worldwide in waste, fluvial and even drinking water, raising concern about the efficacy of the currently employed waste water treatments in the elimination of this kind of compounds. Despite ranking 29th in terms of population, Spain is currently the 8th country on pharmaceutical prescription with an expense of 14× 109 euros in 2008.
Research Interests:
There are a number of reports in the literature which describe the occurrence of so-called emerging pollutants, such as pharmaceuticals, in surface water. Few of these studies have reported values from large cities in relatively arid... more
There are a number of reports in the literature which describe the occurrence of so-called emerging pollutants, such as pharmaceuticals, in surface water. Few of these studies have reported values from large cities in relatively arid areas, such as in Spain. The persistence of some pharmaceuticals to usual wastewater treatments allows their discharge into surface waters. It is increasingly evident that mental health problems are of special concern for public health since psychiatric drugs are used in large amounts. Compared to other countries, Spain has a high pharmaceutical consumption rate, and Madrid metropolitan area is one of the most densely populated areas in Europe. The aim of the present study was to determine the presence of different psychoactive pharmaceuticals and metabolites in the main rivers of Madrid metropolitan area: Jarama, Manzanares, Guadarrama, Henares and Tajo. Sampling was done downstream of ten sewage treatment plants (STP) discharging into these rivers. Control points upstream of STPs discharge points were also sampled. Pharmaceutical compounds and metabolites for analysis were selected according to human consumption and prescription rates in Madrid, and the availability of valid techniques for detection. We observed residues of the antidepressants fluoxetine (80% of the sampling sites), citalopram (60%) and venlafaxine (100%), the anxiolytics nordiazepam (90%), oxazepam (80%) and 7-aminoflunitrazepam (10%) and the anticonvulsant carabamazepine (70%). Measured concentrations equalled or exceeded those reported for other geographical areas, although there is a pronounced lack of information for the anxiolytics and venlafaxine. This is of special concern given that Wyeth–Ayerst's venlafaxine, Effexor, was the 10th greatest selling pharmaceutical worldwide in 2006. We conclude that the origin of pharmaceutical pollution in the rivers of Madrid is mainly the discharge of sewage treatment plants in Madrid's metropolitan area and a comprehensive monitoring program should be implemented.
Research Interests:
Fifty-six pharmaceuticals of various chemical groups, such as anti-inflammatory, antibacterial and cardiovascular drugs, were detected in four selected river waters receiving sewage effluents in the Community of Madrid (Spain). A... more
Fifty-six pharmaceuticals of various chemical groups, such as anti-inflammatory, antibacterial and cardiovascular drugs, were detected in four selected river waters receiving sewage effluents in the Community of Madrid (Spain). A promising approach for the degradation of those residues is the application of a photo-Fenton treatment.
Research Interests:
Background Reactive oxygen species (ROS) are normally produced in respiratory and photosynthetic electron chains and their production is enhanced during desiccation/rehydration. Nitric oxide (NO) is a ubiquitous and multifaceted molecule... more
Background Reactive oxygen species (ROS) are normally produced in respiratory and photosynthetic electron chains and their production is enhanced during desiccation/rehydration. Nitric oxide (NO) is a ubiquitous and multifaceted molecule involved in cell signaling and abiotic stress. Lichens are poikilohydrous organisms that can survive continuous cycles of desiccation and rehydration.
Research Interests:
One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns are the second largest group of vascular plants and are important components of numerous plant communities. Fern... more
One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns are the second largest group of vascular plants and are important components of numerous plant communities. Fern spores and gametophytes have long been recognized as useful models for plant research since they constitute a naturally miniaturized and low-cost higher plant model. Mitochondria are the main energy source in eukaryotic cells, and any toxic damage to this organelle will affect the whole organism. The reduction of tetrazolium salts to water-insoluble colored formazan salts by the NADH reductase complex (E.C.1.6.5.3) has been used for more than 50 years as a measure of cell mitochondrial activity and viability in eukaryotic organisms. Here, the reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by mitochondria is adapted and optimized to measure fern spore or gametophyte viability. We conclude that this method constitutes a promising low-cost bioassay for toxicity of higher plant during development.
Research Interests:
The use of an adequate range of taxa in ecotoxicological studies is a key point for the achievement of ecologically relevant results. Higher plants are an essential part of a healthy and balanced ecosystem and new plant models are... more
The use of an adequate range of taxa in ecotoxicological studies is a key point for the achievement of ecologically relevant results. Higher plants are an essential part of a healthy and balanced ecosystem and new plant models are essential in the evaluation of potential impacts of pollutants. With more than 10,000 living species, ferns are the second-largest group of vascular plants. Fern spores, and spore-developed gametophytes, have long been recognized as useful models for plant research in important areas. One of the main advantages of this model is its naturally miniature size. Fern spores are single meiotic cells which develop into gametophytes which are miniature mature higher plants. The use of microtubes and microplates is imposed by the natural model. Chronic toxicity testing involves longer periods of exposure to toxicants (>48 h) and assesses the ability of a substance to disrupt a significant portion of an organism’s life stage. DNA content in developing gametophytes is a biomarker of the disturbance that the toxicant provokes in gametophyte growth and development. The use of the DNA fluorescent probe Hoechst is a rapid, sensitive, and reliable method frequently used in cell biology which has been successfully applied to spores and gametophytes. Chlorophyll autofluorescence can also be used as a biomarker of the physiological state. Both biomarkers can easily be measured using 96 multiwell plates and plate readers. The combined use of these biomarkers in chronic toxicity tests using developing gametophytes of the riparian Polystichum setiferum is yielding very satisfactory results and is a promising new model for Ecotoxicology.
Research Interests:
One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns, with more than 10 000 living species, are the second largest group of vascular plants and are important components... more
One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns, with more than 10 000 living species, are the second largest group of vascular plants and are important components of numerous plant communities. Fern spores and gametophytes have long been recognized as useful models for plant research since they constitute a naturally miniaturised and economic higher plant model. Mitochondria are the main energy source in eukaryotic cells and any toxic damage will affect the whole organism. The reduction of tetrazolium salts to water-insoluble coloured formazan salts by the respiratory chain has been used for more than 50 years as a measure of cell mitochondrial activity and viability in eukaryotic organisms. Here, the reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by mitochondria is adapted and optimized to measure fern spore or gametophyte viability. Procedures selected as optimum in the model species Dryopteris guanchica are as follows: bleach sterilization, incubation without shaking at 20 °C in the dark for 1–4 h with 0.05–1.5% TTC in Dyer medium supplemented with 0.001–0.005% Tween 20 at pH 8. We conclude that this method constitutes a promising low cost bioassay for higher plant toxicity during development.
Research Interests:
Abstract The cellular proteome shows a dynamic profile and is subjected to changes in response to various stimuli and disease progression. Lung cancer remains the leading cause of cancer death in industrialized countries. In an attempt to... more
Abstract The cellular proteome shows a dynamic profile and is subjected to changes in response to various stimuli and disease progression. Lung cancer remains the leading cause of cancer death in industrialized countries. In an attempt to find new disease markers, patients suffering from lung carcinoma have been selected to achieve differential protein expression patterns between normal and neoplasic tissue.
Research Interests:
We have previously reported that endotoxin induces in vivo oxidative stress in liver and a significant increase in hepatic and plasma glutathione concentrations during the acute phase of reversible endotoxic shock in rats. In the present... more
We have previously reported that endotoxin induces in vivo oxidative stress in liver and a significant increase in hepatic and plasma glutathione concentrations during the acute phase of reversible endotoxic shock in rats. In the present study we examined the in vitro effects of E. coli 0111: B4 endotoxin (lipopolysaccharide, LPS), IL-1ß and TNF-a on antioxidant status of cultured hepatocytes in order to differentiate between the direct and mediated endotoxin action.
Research Interests:
Research Interests:
The duct system of murine submandibular gland is composed, in contrast with other mammals, by four types of ducts, among which the granular duct is unique for rodents. The granular duct shows a typical secretory structure with a clear... more
The duct system of murine submandibular gland is composed, in contrast with other mammals, by four types of ducts, among which the granular duct is unique for rodents. The granular duct shows a typical secretory structure with a clear intersex morphological diversity on which we carried out a morphometrical study in order to determine the relative area of each duct in rats in comparison with the rest of ducts and the whole gland.
Research Interests:
During the nineties it was described, as an original finding, the existence of afferent amyelinic nerve endings in animal dorsal root ganglia (DRG) caused by diverse experimental lesions. These works do not take into account the... more
During the nineties it was described, as an original finding, the existence of afferent amyelinic nerve endings in animal dorsal root ganglia (DRG) caused by diverse experimental lesions. These works do not take into account the historical studies carried out by Ehrlich (1886), Ramón y Cajal (1890) and Dogiel (1885) among others. Ramón y Cajal (1899) confirmed the existence of these nerve endings naming them after their discoverer as “Dogiel's arborisations”.
Research Interests:
Summary. An inadequate balance between oxidant species and antioxidant mechanisms may constitute the primary mechanisms of a number of pathologies. The liver plays a central role in this balance: parenchymal hepatic cells contain and... more
Summary. An inadequate balance between oxidant species and antioxidant mechanisms may constitute the primary mechanisms of a number of pathologies. The liver plays a central role in this balance: parenchymal hepatic cells contain and export especially high levels of the antioxidant glutathione and activated Kupffer cells release inflammation mediators and reactive oxygen species.
Research Interests:
Fontinalis antipyretica has increasingly been used as an environmental pollution biomonitor of stream water quality. This bryophyte goes through periodical desiccation especially in Mediterranean intermittent streams in the driest season.... more
Fontinalis antipyretica has increasingly been used as an environmental pollution biomonitor of stream water quality. This bryophyte goes through periodical desiccation especially in Mediterranean intermittent streams in the driest season. Although there is some information concerning the physiological effects of desiccation on terrestrial bryophytes, only few information is available on the aquatic ones. Thereby, the present study aimed to understand the effect of desiccation on the primary energy metabolism and oxidative stress of the aquatic moss Fontinalis antipyretica both during the desiccation process and recovery. Samples were dehydrated at different rates using controlled atmospheres with different relative humidity (RH) and rapidly rehydrated by immersion on water. Measurements were made before stress and immediately after rehydration. The results showed that desiccation stress induced membrane damage decreases of Gross Photosynthesis and of maximum photochemical efficiency of PSII (Fv/Fm). The data will be interpreted in terms of the effect of RWC and RWL. In this experiment a strong respiratory burst (circa 1200 µmol O2 g-1 DW h-1) was observed during rehydration which correlated better with RWL than with RWC. KCN, sodium azide and SHAM showed an inhibitory effect on oxygen consumption (about 60%, 40% and 25%, respectively) on unstressed samples. However, only KCN was able to totally suppress this respiratory burst in desiccated samples but not by SHAM or Na3N.
To elucidate this respiratory burst an approach in terms of oxidative stress involving production of nitric oxide (NO), reactive oxygen species (ROS) and hydrogen peroxide (H2O2) was investigated. Diaminobenzidine (DAB) staining showed an increased production in H2O2 on F. antipyretica tips upon immediate rehydration and also after 15 minutes rehydration. Quantification of H2O2 production showed an increase with decreasing RWC, but over a period of 25 minutes of rehydration, this rate slowly decreased. However this production is not enough to significantly explain the respiratory burst observed in stress conditions. In order to localize in the aquatic moss where the ROS and NO production was occurring, fluorescent probes and epifluorescence and confocal microscopy were used in the first moments after rehydration. Using 2,7-dichlorofluorescin diacetate (DCFH2-DA), a probe used for intracellular ROS detection, a generalized oxidation inside the cells was observed particularly in the chloroplasts. Some NO production was observed in the tissues applying the NO probe, 2,3-diamino naphthalene (DAN).
In what concerns the recovery, photosynthesis and respiration slowly recover 5 days after the end of desiccation, but recovery was slower when the mosses reached further lower RWC or when the desiccation rate was further higher. Photosynthesis and respiration did not fully achieved pre-desiccation values even after 5 days recovery from desiccation stress. Neverthelss, chlorophyll a fluorescence parameters recover almost completely, with the exception of NPQ values which remain lower than pre-desiccation ones.
These results show that the membrane integrity and the photosynthetic processes depend more on the amount than on the rate of water loss, although higher RWL exacerbate the stress effects. On the contrary, the non-specific respiratory burst is more dependent on the desiccation rate. This burst may be due to generalized oxidative processes and thereby could be the reason why the rate of desiccation seems to be crucial for recovery and survival. On the other hand, the rate of water loss also played an important role implying that a faster desiccation rate would not allow time for the activation of protective mechanisms against desiccation. The reactive species that are produced in stress conditions as a result of miscellaneous reactions can also have an important role in cell signaling and cell-to-cell communication for desiccation protection measures.
To elucidate this respiratory burst an approach in terms of oxidative stress involving production of nitric oxide (NO), reactive oxygen species (ROS) and hydrogen peroxide (H2O2) was investigated. Diaminobenzidine (DAB) staining showed an increased production in H2O2 on F. antipyretica tips upon immediate rehydration and also after 15 minutes rehydration. Quantification of H2O2 production showed an increase with decreasing RWC, but over a period of 25 minutes of rehydration, this rate slowly decreased. However this production is not enough to significantly explain the respiratory burst observed in stress conditions. In order to localize in the aquatic moss where the ROS and NO production was occurring, fluorescent probes and epifluorescence and confocal microscopy were used in the first moments after rehydration. Using 2,7-dichlorofluorescin diacetate (DCFH2-DA), a probe used for intracellular ROS detection, a generalized oxidation inside the cells was observed particularly in the chloroplasts. Some NO production was observed in the tissues applying the NO probe, 2,3-diamino naphthalene (DAN).
In what concerns the recovery, photosynthesis and respiration slowly recover 5 days after the end of desiccation, but recovery was slower when the mosses reached further lower RWC or when the desiccation rate was further higher. Photosynthesis and respiration did not fully achieved pre-desiccation values even after 5 days recovery from desiccation stress. Neverthelss, chlorophyll a fluorescence parameters recover almost completely, with the exception of NPQ values which remain lower than pre-desiccation ones.
These results show that the membrane integrity and the photosynthetic processes depend more on the amount than on the rate of water loss, although higher RWL exacerbate the stress effects. On the contrary, the non-specific respiratory burst is more dependent on the desiccation rate. This burst may be due to generalized oxidative processes and thereby could be the reason why the rate of desiccation seems to be crucial for recovery and survival. On the other hand, the rate of water loss also played an important role implying that a faster desiccation rate would not allow time for the activation of protective mechanisms against desiccation. The reactive species that are produced in stress conditions as a result of miscellaneous reactions can also have an important role in cell signaling and cell-to-cell communication for desiccation protection measures.