Mycosporine-like Amino Acids Provide Protection Against Ultraviolet Radiation in Eggs of the Green Sea Urchin Strongylocentrotus droebachiensis

A photoprotective role of ultraviolet radiation-absorbing mycosporine-like amino acids (MAAs) in eggs of the green sea urchin Strongylocentrotus droebachiensis was demonstrated by comparing UV-induced delays in the first division of embryos having either high or low concentrations of MAAs. Embryos from adult urchins fed Laminaria saccharina (no MAAs) had low concentrations of MAAs and experienced a significantly longer UV-induced delay in cleavage (25.1%) than MAA-rich embryos from adults fed Mastocarpus stellatus (12.8% delay) or a combination diet of both macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentration in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects. Concentrations of MAAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short-term UV exposure in vivo or long-term exposure in vitro; such photostability is a useful attribute of a natural sunscreen.     

Oxidative Damage in Response to Natural Levels of UV-B Radiation in Larvae of the Tropical Sea Urchin Tripneustes gratilla

To assess the effects of UV radiation (280–400 nm) on development, oxidative damage and antioxidant defence in larvae of the tropical sea urchin Tripneustes gratilla, a field experiment was conducted at two depths in Aitutaki, Cook Islands (18.85°S, 159.75°E) in May 2008. Compared with field controls (larvae shielded from UV-R but exposed to VIS-radiation), UV-B exposure resulted in developmental abnormality and increases in oxidative damage to proteins (but not lipids) in embryos of T. gratilla held at 1 m depth. Results also indicated that larvae had the capacity to increase the activities of protective antioxidant enzymes when exposed to UV-B. The same trends in oxidative damage and antioxidant defence were observed for embryos held at 4 m, although the differences were smaller and more variable. In contrast to UV-B exposure, larvae exposed to UV-A only showed no significant increases in abnormality or oxidative damage to lipids and proteins compared with field controls. This was true at both experimental depths. Furthermore, exposure to UV-A did not cause a significant increase in the activities of antioxidants. This study indicates that oxidative stress is an important response of tropical sea urchin larvae to exposure to UV radiation.     

Oxidative Stress and DNA Damage Effect of Dioscorea hispida Dennst. on Placental Tissues of Rats

Dioscorea hispida Dennst. locally known as “ubi gadung” has been used as a traditional remedy and source of carbohydrate among Malaysians. To assess the effect of Dioscorea hispida aqueous extract (DHAE) on the production of reactive oxygen species (ROS) and their effects on DNA damage in Sprague Dawley rat’s placental tissues, pregnant rats were randomly divided into four groups. The animals were orally treated with distilled water (negative control) and three different concentrations of DHAE (250, 500 and 1000 mg/kg body weight (BW)) from gestation day 6 until 20. The oxidative stress in placental tissues was evaluated at day 21 by measuring the level of ROS, superoxide dismutase (SOD) and lipid peroxidation biomarker, malondialdehyde (MDA) while comet assay was used for DNA damage. There was no significant production of ROS and SOD activities in all groups. Significant changes were observed in the MDA level at 1000 mg/kg BW DHAE. Comet assay revealed a significant increase (p < 0.05) of DNA damage on animals treated with 250 and 500 mg/kg BW DHAE but not at the highest concentration. It was postulated that the placental cells could have undergone necrosis which destroys all components including DNA. This occurrence simultaneously reduces the levels of DNA damage which can be represented by lower level of tail moments. This finding correlates with our histopathological examination where necrotic cells of spongiotrophoblast were observed in the basal zone of placental tissue. The high amount of hydrogen cyanide and other compounds in 1000 mg/kg BW DHAE could elevate the lipid peroxidation and directly induce cell necrosis which requires further investigation.     

Diel Cycles of DNA Damage and Repair in Eggs and Larvae of Northern Anchovy, Engraulis mordax, Exposed to Solar Ultraviolet Radiation

Abstract— Damage from UVB radiation (280–320 nm) in the form of cyclobutane pyrimidine dimers (CPD) in DNA and the capacity for their repair were measured in newly spawned eggs and yolk-sac larvae of northern anchovy, Engraulis mordax, exposed to natural diel cycles of sunlight. The CPD were measured by a newly developed chemiluminescent immunoblot assay capable of measuring CPD in samples as small as 50 ng DNA. Eggs and yolk-sac larvae exposed to full irradiance levels died. At lower dose rates, equivalent to deeper more natural locations in the water column, there was a diel cycle of dimer concentration that tracked solar intensity. This diel cycle was due to the interaction of damage and repair processes. Repair of CPD in anchovy eggs and larvae could be attributed to true photodependent repair that could be stopped by moving samples into the dark. The CPD present at sunset remained until the following morning. The diel cycles of damage and repair were maintained over at least 4 days without a long-term upward or downward trend in dimer concentration. This indicates that at the UVB doses used for these experiments, there was no long-term accumulation of CPD nor an induction of increased repair capacity. Unhatched embryos spawned in the dark also exhibited a strong photorepair response, suggesting that photolyase expression was innate and not dependent on previous light exposure. The diel cycle observed here indicates that, at least for northern anchovy, the CPD concentration at the time of sampling is a good indicator of dose rate but a poor indicator of cumulative dose (i.e. late afternoon samples have the highest cumulative dose but relatively low CPD concentrations). The CPD immunoassay described here has the required sensitivity for measuring DNA damage in wild populations of ichthyoplankton exposed to natural sunlight. These results will guide the collection and interpretation of field data on natural levels of CPD in wild larvae collected at different depths and times of the day.     

Effects of Salinity and Ultraviolet Radiation on the Bioaccumulation of Mycosporine‐like Amino Acids in Artemia from Lake Urmia (Iran)

We investigated the effects of salinity and artificial UV radiation on the accumulation of mycosporine‐like amino acids (MAAs) in sexual and parthenogenetic Artemia from Lake Urmia. The nauplii hatched from the cysts were cultured until adulthood under two salinities (150 and 250 g L^?1) and two light treatments (PAR and PAR+UVR) in the laboratory. Finally, the Artemia were analyzed for their concentration of MAAs. In most of the cases, the higher salinity level applied was found to increase the MAA concentrations in both Artemia populations significantly. The acquisition efficiency of MAAs in both Artemia populations increased under exposure to UVR‐supplemented photosynthetically active radiation (PAR) compared to those raised under PAR, except for Porphyra‐334. It was observed that combination of UV radiation and elevated salinity significantly increased the bioaccumulation of MAAs. Thus, the presence of these compounds in these populations of Artemia may increase their adaptability for living in high‐UV and high‐salinity conditions prevailing in Lake Urmia. Higher concentrations of MAAs in the parthenogenetic population of Artemia could be probably attributed to its mono sex nature and higher adaptation capacities to extreme environmental conditions.     

Photorepair of Ultraviolet Radiation (UVR)-lnduced Pyrimidine Dimers in Lens Epithelial DNA of Monodelphis domestica

Abstract— The repair of UV radiation-induced pyrimidine dimers has been measured in lens epithelial DNA of the marsupial Monodelphis domestica using a pyrimidine dimerspecific endonuclease from Micrococcus luteus. Approximately 40% of the initially induced dimers were repaired during 90 min exposures to photoreactivating light. This capacity of the lens epithelium to photorepair pyrimidine dimers may provide a means with which to determine whether pyrimidine dimers in lens epithelial DNA are involved in UV radiation-induced pathologic changes of the lens.     

稀土对UV-B辐射伤害植物的影响Ⅰ. Ce(Ⅲ)对UV-B胁迫下油菜幼苗生长及光合作用影响

用水培法研究了Ce(Ⅲ)对紫外辐射(UV-B, 280～320 nm)胁迫下油菜幼苗生长与光合作用的影响. 实验表明, 在紫外辐射(T1/0.15 W·m-2和T2/0.35 W·m-2)胁迫下, 油菜幼苗生长受到严重抑制. 地上部茎(株)高、叶片数、叶面积、叶鲜(干)重、茎鲜(干)重等生长指标均低于对照植株13.2%～44.1%(T1), 21.4%～49.3%(T2); 地下部除根系活跃吸收面积降幅不明显外, 主根长、根体积、根鲜(干)重均低于对照14.1%～35.6%(T1), 20.3%～42.6%(T2). Ce处理油菜幼苗, 上述各项指标降幅均低于未用Ce处理植株(地上部, Ce+T1降低4.1%～23.6%, Ce+T2降低10.8%～28.4%; 地下部, Ce+T1降低5.2%～23.3%, Ce+T2降低 7.0%～27.8%). 表明Ce对紫外辐射伤害油菜幼苗有防护效应,且对低剂量UV-B伤害的防护效果更优. 光合参数测定显示, UV-B胁迫下植株Chl含量, Pn, En, Gs及WUE降低, Ci增高. Ce处理植物的5项参数降幅减小, 表明对光合作用的改善是Ce防护效应的生态生理学基础. 光合参数动态测定显示, Ce介导使油菜光致修复历程缩短(逼向CK的拐点前置), 或各时段变幅陡减.     

Effects of Ultraviolet Radiation (UVA+UVB) and Copper on the Morphology,Ultrastructural Organization and Physiological Responses of the Red Alga Pterocladiella capillacea

The effect of ultraviolet (UV) radiation and copper (Cu) on apical segments of Pterocladiella capillacea was examined under two different conditions of radiation, PAR (control) and PAR+UVA+UVB (PAR+UVAB), and three copper concentrations, ranging from 0 (control) to 0.62, 1.25 and 2.50 μm . Algae were exposed in vitro to photosynthetically active radiation (PAR) at 70 μmol photons m^?2 s^?1, PAR + UVB at 0.35 W m^?2 and PAR +UVA at 0.70 W m^?2 during a 12‐h photocycle for 3 h each day for 7 days. The effects of radiation and copper on growth rates, content of photosynthetic pigments and photosynthetic performance were analyzed. In addition, samples were processed for light and transmission electron microscopy. The content of photosynthetic pigments decreased after exposure to radiation and Cu. Compared with PAR radiation and copper treatments modified the kinetics patterns of the photosynthesis/irradiance curve. The treatments also caused changes in the ultrastructure of cortical and subcortical cells, including increased cell wall thickness and accumulation of plastoglobuli, as well as changes in the organization of chloroplasts. The results indicate that the synergistic interaction between UV radiation and Cu in P. capillacea, led to the failure of protective mechanisms and causing more drastic changes and cellular imbalances.     

不同波段的紫外辐射对DNA构象影响的拉曼光谱研究

研究了小牛胸腺DNA水溶液经不同时问不同波段紫外辐射后的拉曼光谱。结果表明：仅仅经过9min强度为18．68W／m^2。的全波段紫外辐射,DNA就遭到了严重损伤：表征PO2^-对称伸张振动的1094cm^-1谱线分裂成4条谱线．说明DNA构象遭到破坏,构型发生了变化。UV—A＆UV—B波段的紫外辐射对DNA的影响比全波段的紫外辐射对DNA的影响小得多,但经过较长时间辐射后,仍对DNA构型构象产生了影响,即A型构象增强,B型构象减弱．经过2h的UV—A辐射,出现了表征A型构象的805cm^-1和816cm^-1谱线,且816cm^-1峰与未经辐射的表征A型的803cm^-1峰相比,强度大得多。经过16h的UV—A辐射后,805cm^-1谱线消失,816cm^-1谱线移到了813cm^-1,且强度减弱50％,表明水溶液中的DNA在UV—A照射中A型构象不稳定,处于变化之中。     

Electrochemical Characterization of (ZnO/dsDNA)n Layer-by-layer Films and Detection of Natural DNA Oxidative Damage

The positively charged nano‐ZnO and negatively charged natural DNA were alternately adsorbed on the surface of a gold electrode, forming (ZnO/dsDNA)_nlayer‐by‐layer films. Valuable dynamic information for controlling the formation and growth of the films was obtained by cyclic voltammetry and electrochemical impedance spectroscopy. Differential pulse voltammetric (DPV) measurements showed that the electroactive probe methylene blue (MB) could be loaded in the (ZnO/dsDNA)_nfilms from its solution, and then released from the films into Britton‐Robinson (B‐R) buffer. The complete reloading of MB in the films could be realized by immersing the films in MB solution again. However, after incubation in the solution of carcinogenic metal nickel, the damaged (ZnO/dsDNA)_n films could not return to their original and fully‐loaded state, and showed smaller DPV peak currents. The results demonstrated that the DNA damage induced by the hydroxyl radical could be achieved by electrochemistry.     

DNA Damage and Effects on Antioxidative Enzymes in Earthworm (Eisenia fetida) Induced by Flumorph

Flumorph is an Oomycete fungicide, which is used extensively as an effective fungicide in vegetables and fruits, but little is known about its effect on nontarget soil organisms. In the present study, biochemical responses including changes in the activity of antioxidative enzymes catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), malondialdehyde (MDA), and DNA damage induced by flumorph were investigated in earthworms (Eisenis fetida). The CAT concentrations were stimulated at 5.0 mg kg^?1 over 28 days and inhibited at 10 and 20 mg kg^?1, except 10 mg kg^?1 on days 21 and 28 compared with the controls. The overall SOD activities were inhibited except 5 mg kg^?1 on day 28 and 10 mg kg^?1 on days 7 and 14. Meanwhile, the GST activities were stimulated on day 7 and decreased on the other days in summary. The MDA activities were increased notably at 5, 10, and 20 mg kg^?1 after 14 days. Clear dose-dependent DNA damage to Eisenia fetida was observed by olive tail moments in comet assay compared with controls. The results demonstrate that flumorph induces oxidative stress and DNA damage to earthworms, and the effects may be the important mechanisms of its toxicity.     

Oxidative DNA Damage in the Photolysis of Af-Hydroxy-2-Pyridone, a Specific Hydroxyl-Radical Source

Abstract The photooxidative DNA damage by iV-hydroxy-2-pyri-done (1) is caused by hydroxyl radicals, as confirmed by electron paramagnetic resonance studies with the spin trap 5,5-dimethylpyrroline JV-oxide. Irradiation of the pyridone 1 at 300 nm induced strand breaks in super-coiled pBR322 DNA, while in calf-thymus DNA and 2'-deoxyguanosine (dG), respectively, 8-oxoguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine were formed. Time-dependent control experiments disclosed that photoprod-ucts of pyridone 1, e.g. 2-pyridone (3), are not responsible for the modification of DNA. Also the photosensitization by the pyridine-2-one chromophore was excluded, because JV-methylpyridine-2-one (2), which cannot generate hydroxyl radicals, was ineffective in the photooxidation of DNA and dG. Thus, the photolysis of pyridone 1 serves as a specific source of hydroxyl radicals for DNA damage, both strand breaks and base modifications.     

Distribution and occurence of polycyclic aromatic hydrocarbons (PAHs) in sediments from the Mar Grande and Gulf of Taranto (Ionian Sea, southern Italy)

Marine sediments from the Mar Grande and Gulf of Taranto were analysed for 17 parent PAHs, with molecular weight from 128 to 278 Daltons. The analyses were performed by gas chromatography coupled to mass spectrometry (GC-MS). Total PAHs content in sediments ranged from 464 to 12522 microg kg(-1) dry wt for Mar Grande and from 593 to 72275 microg kg(-1) dry wt for Gulf of Taranto. The analytical results were compared with the published results for other coastal areas in the Mediterranean Sea. PAHs levels in the Gulf of Taranto sediments were the highest in the Mediterranean sea, while PAHs concentrations in Mar Grande were higher than the ones reported in the Adriatic and Cretan Sea and with the same order of magnitude of the ones known for coastal areas of the Western and the Eastern Mediterranean Sea. PAHs concentration ratios were consistent with the main source of these compounds, in most areas, being pyrolysis. Based on the comparison of both the individual and the total PAHs concentrations with proposed sediment quality guidelines, the acute biological effects on the marine organisms were probable, especially for the Gulf of Taranto, in which almost all PAHs concentrations in sediments were higher than the guidelines limit values. The statistical analysis effected by HCA and PCA methods was used in order to classify sediment samples and to identify accumulation areas.     

Determination of Cobalt(II)-Hydrogen Peroxide-Induced DNA Oxidative Damage and Preventive Antioxidant Activity by CUPRAC Colorimetry

Abstract

The classical Fenton system composed of Fe(II) and H₂O₂ uses harsh oxidative conditions and cannot realistically simulate physiological oxidations which are less severe. Here, reactive oxygen species (ROS) were generated with a combination of CoSO₄ and H₂O₂ to provide milder conditions. DNA was used as a biologically meaningful probe for monitoring the oxidative conversion. Oxidative hazard on DNA was accomplished in ammonia/ammonium chloride buffer at 37?°C, and the Fenton reaction was stopped with trichloroacetic acid (TCA). A suitable aliquot of this solution was added to cupric ion reducing antioxidant capacity (CUPRAC) reaction mixture, and the absorbance at 450?nm was recorded. The oxidized species derived from DNA were CUPRAC-reactive while intact DNA was not. The protective effects of antioxidants (AOxs), known to have radical scavenging effects, were tested; green tea and a synthetic fetal bovine serum (FBS) were also successfully used as real ROS scavengers. Although the classical iron-based Fenton procedure applied in ethanol medium generated CUPRAC-responsive products, the proposed system was perfectly ethanol-tolerant, enabling the CUPRAC measurement of DNA oxidation products against an unaffected reagent blank. The protective effects of phenolic antioxidants, perfectly solubilized in ethanol, could also be measured.     

Ultraviolet Radiation Reduces the Photoprotective Capacity of the Marine Diatom Phaeodactylum tricornutum (Bacillariophyceae, Heterokontophyta)

This study demonstrates that UV radiation (UVR) reduces the photoprotective capacity of the diatom Phaeodactylum tricornutum by affecting xanthophyll cycle (XC) activity. The short‐term reduction of photosystem II (PSII) maximum efficiency of charge separation (F_v/F_m) in cells exposed to UVR could be explained mainly by a reduced photoprotective capacity under this condition. Phaeodactylum tricornutum cells acclimated to two different photosynthetically active radiation (PAR) intensities, high light (HL, 200 μmol quanta m^?2 s^?1) and low light (LL, 50 μmol quanta m^?2 s^?1), were exposed to saturating irradiance (1100 μmol quanta m^?2 s^?1) in the presence (PAR + UVR) and absence of UVR (PAR). HL cells exhibited a greater reduction in F_v/F_m in PAR + UVR when compared with the PAR treatment that was related to a reduction in the de‐epoxidation of XC pigments. In contrast, in LL cells, UVR did not considerably affect XC de‐epoxidation even though the reduction in F_v/F_m was greater than in HL cells. The negative effect of UVR on photoprotection was more pronounced in HL cells because they synthesized more XC pigments than LL cells. This was confirmed when XC activity was blocked with dithiothreitol and when PSII repair was inhibited with chloramphenicol (CAP). The differential reduction of F_v/F_m between PAR + UVR and PAR treatments disappeared when XC was blocked in HL cells. A higher reduction and an incomplete recovery of F_v/F_m were observed in cells incubated with CAP in the presence of UVR. Such responses confirm that UVR had a negative effect on photoprotective mechanisms causing an enhancement of damage by PAR, especially in HL‐acclimated cells in which heat dissipation is important for PSII regulation.     

Effects of Green Apple (Golden Delicious) and Its Three Major Flavonols Consumption on Obesity,Lipids, and Oxidative Stress in Obese Rats

Obesity is becoming increasingly common all over the world and global strategies are accordingly being developed to prevent it. In order to support the strategies, the effects of green apple (Golden Delicious) and the consumption of its three major flavonols (quercetin-3-glucoside, quercetin-3-D-galactoside, and quercetin-3-rhamnoside) on body weight; the weight of liver, kidney, and spleen; some lipid parameters in serum; and total lipid ratios of liver and kidney and oxidative stress parameters of obese rats were studied. This study was conducted on two experimental groups: one of which was given an apple, and the other was given flavonols, in addition to their high-energy diet; along with a sham and a control rat group, for 4 weeks. According to results, there was no difference in body and organ weights between groups. The liver and kidney weights increased in obese rats, but there was no difference between the total lipid ratios in these organs. The addition of green apple and selected flavonols to the high-energy diet of rats was not sufficient to prevent the increase in body and organ weights, but it supported the reduction in some lipid fractions and in oxidative stress parameters of obese rats. Moreover, this study supported the argument that obesity causes most of the lipid fractions increase in serum and induces oxidative stress.     

Expression of the DNA Repair Enzyme, Photolyase, in Developmental Tissues and Larvae, and in Response to Ambient UV-R in the Antarctic Sea Urchin Sterechinus neumayeri

Gene expression of the DNA repair enzyme, photolyase (E.C. 4.1.99.3) was examined in the gonads, eggs, embryos and larval stages of the Antarctic sea urchin, Sterechinus neumayeri . Partial sequencing of the gene revealed two highly conserved regions, including a 300 bp region representing the binding site for the cofactor flavin adenine dinucleotide. The second 1200 bp region, likely representing a second light-harvesting cofactor binding site, was identified in a second sea urchin species, Strongylocentrotus frascicanus . Probes for photolyase were developed from the shorter sequence, and expression in sea urchin developmental tissue and stages, and in response to in situ exposure to ultraviolet radiation was quantified using PCR and RT-qPCR, with concentrations of photolyase normalized to actin concentrations. Photolyase was expressed in all tissues and developmental stages examined. In controlled field-based experiments in McMurdo Sound, Antarctica, we found evidence of both constitutive expression of photolyase and induction in response to in situ exposure of embryos to UV-R. Induction of photolyase was observed in response to greater ambient UV-R (such as shallower water depths or sea ice-free regions).     

Ultraviolet Radiation Effects on a Microscopic Green Alga and the Protective Effects of Natural Dissolved Organic Matter

Abstract— The population and photosynthetic responses of a microscopic green alga ( Selenastrum capricornutum ) to realistic levels of UV radiation (UVA and UVB) were assessed in natural lake waters of different dissolved organic carbon (DOC) concentration. Specific growth rates and photosynthetic competence (as reflected by F_v/F_m [measure of maximal quantum efficiency of photosystem II] and t_1/2 [estimate of electrons transported to the plastoquinone pool] measured by in vivo variable chlorophyll a fluorescence) were compared between two exposure levels of UVR and two concentrations of DOC (2.5 mg C L⁻¹ 7.7 mg C L⁻¹). Exposure periods of 6–9 days (five to nine generations) were used. Exposure to UVA primarily affected the efficiency of photosystem II, as evidenced by significant decreases of F_v/F_m but not growth rates or t_1/2 Exposure to UVB, in the presence of UVA, did not cause significant additional decreases of F_v/F_m but did diminish growth rates. In the low DOC water, t_1/2 was also diminished, suggesting different proximate sites of action from those for UVA. The high DOC water decreased the effective exposure to both UVA and UVB and diminished the negative impact of UV radiation on the cells, but the apparent protection was not explicable solely by the shading action of the DOC. Control values for F_v/F_m, growth rates and t_1/2 were all lower in the high DOC water, suggesting a negative side effect to the apparent protective action of the DOC against UVB.     

Effects of Ultraviolet Radiation (UVA+UVB) on Young Gametophytes of Gelidium floridanum: Growth Rate,Photosynthetic Pigments,Carotenoids, Photosynthetic Performance,and Ultrastructure

This study investigated the effects of radiation (PAR+UVA+UVB) on the development and growth rates (GRs) of young gametophytes of Gelidium floridanum. In addition, photosynthetic pigments were quantified, carotenoids identified, and photosynthetic performance assessed. Over a period of 3 days, young gametophytes were cultivated under laboratory conditions and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m^?2 s^?1 and PAR+UVA (0.70 W m^?2)+UVB (0.35 W m^?2) for 3 h per day. The samples were processed for light and electron microscopy to analyze the ultrastructure features, as well as carry out metabolic studies of GRs, quantify the content of photosynthetic pigments, identify carotenoids and assess photosynthetic performance. PAR+UVA+UVB promoted increase in cell wall thickness, accumulation of floridean starch grains in the cytoplasm and disruption of chloroplast internal organization. Algae exposed to PAR+UVA+UVB also showed a reduction in GR of 97%. Photosynthetic pigments, in particular, phycoerythrin and allophycocyanin contents, decreased significantly from UV radiation exposure. This result agrees with the decrease in photosynthetic performance observed after exposure to ultraviolet radiation, as measured by a decrease in the electron transport rate (ETR), where values of ETRmax declined approximately 44.71%. It can be concluded that radiation is a factor that affects the young gametophytes of G. floridanum at this stage of development.