Disjunction of homologous chromosomes in meiosis I depends on proteolytic cleavage of the meiotic cohesin Rec8 by separin

It has been proposed but never proven that cohesion between sister chromatids distal to chiasmata is responsible for holding homologous chromosomes together while spindles attempt to pull them toward opposite poles during metaphase of meiosis I. Meanwhile, the mechanism by which disjunction of homologs is triggered at the onset of anaphase I has remained a complete mystery. In yeast, cohesion between sister chromatid arms during meiosis depends on a meiosis-specific cohesin subunit called Rec8, whose mitotic equivalent, Sccl, is cleaved at the metaphase to anaphase transition by an endopeptidase called separin. We show here that cleavage of Rec8 by separin at one of two different sites is necessary for the resolution of chiasmata and the disjunction of homologous chromosomes during meiosis.

Phenotypic variation in a large Swedish pedigree due toSNCAduplication and triplication

BACKGROUND

The "Lister family complex," an extensive Swedish family with autosomal dominant Parkinson disease, was first described by Henry Mjönes in 1949. On the basis of clinical, molecular, and genealogic findings on a Swedish and an American family branch, we provide genetic evidence that explains the parkinsonism in this extended pedigree.

METHODS

Clinical methods included a detailed neurologic exam of the proband of the Swedish family branch, MRI, and ([123]I)-beta-CIT SPECT imaging. Genomic analysis included alpha-synuclein sequencing, SNCA real-time PCR dosage, chromosome 4q21 microsatellite analysis, and high-resolution microarray genotyping. The geographic origin and ancestral genealogy of each pedigree were researched in the medical literature and Swedish Parish records.

RESULTS

The proband of the Swedish family branch presented with early dysautonomia followed by progressive parkinsonism suggestive of multiple system atrophy. Molecular analysis identified a genomic duplication of <0.9 Mb encompassing alpha-synuclein and multimerin 1 (SNCA-MMRN1), flanked by long interspersed repeat sequences (LINE L1). Microsatellite variability within the genomic interval was identical to that previously described for a Swedish American family with an alpha-synuclein triplication. Subsequent genealogic investigation suggested that both kindreds are ancestrally related to the Lister family complex.

CONCLUSION

Our findings extend clinical, genetic, and genealogical research on the Lister family complex. The genetic basis for familial parkinsonism is an SNCA-MMRN11 multiplication, but whereas SNCA-MMRN1 duplication in the Swedish proband (Branch J) leads to late-onset autonomic dysfunction and parkinsonism, SNCA-MMRN1 triplication in the Swedish American family (Branch I) leads to early-onset Parkinson disease and dementia.

Cohesin ensures bipolar attachment of microtubules to sister centromeres and resists their precocious separation

The multisubunit protein complex cohesin is required to establish cohesion between sister chromatids during S phase and to maintain it during G2 and M phases. Cohesin is essential for mitosis, and even partial defects cause very high rates of chromosome loss. In budding yeast, cohesin associates with specific sites which are distributed along the entire length of a chromosome but are more dense in the vicinity of the centromere. Real-time imaging of individual centromeres tagged with green fluorescent protein suggests that cohesin bound to centromeres is important for bipolar attachment to microtubules. This cohesin is, however, incapable of resisting the consequent force, which leads to sister centromere splitting and chromosome stretching. Meanwhile, cohesin bound to sequences flanking the centromeres prevents sister chromatids from completely unzipping and is required to pull back together sister centromeres that have already split. Cohesin therefore has a central role in generating a dynamic tension between microtubules and sister chromatid cohesion at centromeres, which lasts until chromosome segregation is finally promoted by separin-dependent cleavage of the cohesin subunit Scc1p.

AVONET: morphological, ecological and geographical data for all birds

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species-level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, including six ecological variables, 11 continuous morphological traits, and information on range size and location. Raw morphological measurements are presented from 90,020 individuals of 11,009 extant bird species sampled from 181 countries. These data are also summarised as species averages in three taxonomic formats, allowing integration with a global phylogeny, geographical range maps, IUCN Red List data and the eBird citizen science database. The AVONET dataset provides the most detailed picture of continuous trait variation for any major radiation of organisms, offering a global template for testing hypotheses and exploring the evolutionary origins, structure and functioning of biodiversity.

Dense sampling of bird diversity increases power of comparative genomics

Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity1-4. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species.

The Spirodela polyrhiza genome reveals insights into its neotenous reduction fast growth and aquatic lifestyle

The subfamily of the Lemnoideae belongs to a different order than other monocotyledonous species that have been sequenced and comprises aquatic plants that grow rapidly on the water surface. Here we select Spirodela polyrhiza for whole-genome sequencing. We show that Spirodela has a genome with no signs of recent retrotranspositions but signatures of two ancient whole-genome duplications, possibly 95 million years ago (mya), older than those in Arabidopsis and rice. Its genome has only 19,623 predicted protein-coding genes, which is 28% less than the dicotyledonous Arabidopsis thaliana and 50% less than monocotyledonous rice. We propose that at least in part, the neotenous reduction of these aquatic plants is based on readjusted copy numbers of promoters and repressors of the juvenile-to-adult transition. The Spirodela genome, along with its unique biology and physiology, will stimulate new insights into environmental adaptation, ecology, evolution and plant development, and will be instrumental for future bioenergy applications.

Spirodela, or duckweed, is a basal monocotyledonous plant with both pharmaceutical and commercial value. Here, the authors sequence the genome of Spirodela polyrhiza, suggesting its genome has evolved by neotenous reduction and clonal propagation, and provide a platform for future comparative genomic studies in angiosperms.

Centromere clustering is a major determinant of yeast interphase nuclear organization

During interphase in the budding yeast, Saccharomyces cerevisiae, centromeres are clustered near one pole of the nucleus as a rosette with the spindle pole body at its hub. Opposite to the centromeric pole is the nucleolus. Chromosome arms extend outwards from the centromeric pole and are preferentially directed towards the opposite pole. Centromere clustering is reduced by the ndc10 mutation, which affects a kinetochore protein, and by the microtubule poison nocodazole. This suggests that clustering is actively maintained or enforced by the association of centromeres with microtubules throughout interphase. Unlike the Rabl-orientation known from many higher eukaryotes, centromere clustering in yeast is not only a relic of anaphase chromosome polarization, because it can be reconstituted without the passage of cells through anaphase. Within the rosette, homologous centromeres are not arranged in a particular order that would suggest somatic pairing or genome separation.

Impairment of enzymic and nonenzymic antioxidants in skin by UVB irradiation

Antioxidants may play a significant role in ameliorating or preventing photobiologic damage in skin that could lead to cutaneous disorders such as cancer and premature aging. The objective of this study was to assess the acute cutaneous enzymic and nonenzymic antioxidant response to a single exposure of large fluence (300 mJ/cm2) ultraviolet radiation (greater than 280 nm) in hairless mice. This treatment caused an immediate and statistically significant inhibition of glutathione reductase and catalase activity. Glutathione peroxidase and superoxide dismutase were not affected. Glutathione levels decreased and, conversely glutathione disulfide concentrations increased. A slight depletion of the total glutathione was observed, while the content of total ascorbic acid did not change. The lipophilic antioxidants alpha-tocopherol, ubiquinol 9 and ubiquinone 9 also decreased significantly, and the concentration of malondialdehyde remained constant. The free radical scavenging activity of epidermis, as assessed by reduction of the stable, cationic nitroxide radical [2,2,6,6-tetramethyl-1-piperidinoxy-4-(2',4',6'-trimethyl) methylpyridinium perchlorate] was considerably inhibited. The study indicates that immediately after exposure to a large fluence of ultraviolet radiation the enzymic and nonenzymic antioxidant capacity of skin decreases significantly.

Plasma devices to guide and collimate a high density of MeV electrons

The development of ultra-intense lasers has facilitated new studies in laboratory astrophysics and high-density nuclear science, including laser fusion. Such research relies on the efficient generation of enormous numbers of high-energy charged particles. For example, laser-matter interactions at petawatt (10(15) W) power levels can create pulses of MeV electrons with current densities as large as 10(12) A cm(-2). However, the divergence of these particle beams usually reduces the current density to a few times 10(6) A cm(-2) at distances of the order of centimetres from the source. The invention of devices that can direct such intense, pulsed energetic beams will revolutionize their applications. Here we report high-conductivity devices consisting of transient plasmas that increase the energy density of MeV electrons generated in laser-matter interactions by more than one order of magnitude. A plasma fibre created on a hollow-cone target guides and collimates electrons in a manner akin to the control of light by an optical fibre and collimator. Such plasma devices hold promise for applications using high energy-density particles and should trigger growth in charged particle optics.

Modulation of UV-light-induced skin inflammation by D-alpha-tocopherol and L-ascorbic acid: a clinical study using solar simulated radiation

OBJECTIVE

In this clinical trial we studied whether oral supplementation with D-alpha-tocopherol (alpha-Toc), L-ascorbic acid (Asc), or alpha-Toc combined with Asc influenced the solar simulated radiation (SSR) induced skin inflammation in healthy volunteers.

METHODS

We investigated the following groups in a prospective, randomized and placebo controlled study: Group (1) alpha-Toc 2 g/day, group (2) Asc 3 g/day, group (3) alpha-Toc 2 g/day combined with Asc 3 g/day, and group (4) placebo. Before and 50 days after supplementation we analyzed alpha-Toc and Asc concentrations in keratinocytes. The dose response curve of UV erythema was determined by reflectance spectrophotometry and the minimal erythema dose (MED) by visual grading before and after supplementation.

RESULTS

50 days after supplementation alpha-Toc keratinocyte levels were increased in groups (1) and (3), Asc concentrations were elevated in groups (2) and (3), and the a/gamma-Toc ratio increased in groups (1) and (3). The dose response curve of UVR induced erythema showed a significant flattening and the MED increased from 103 +/- 29 mJ/cm2 (before supplementation) to 183 +/- 35 mJ/cm2 (after supplementation) in group (3), while there were no significant changes in groups (1) and (2) after vitamin supplementation.

CONCLUSION

Alpha-Toc and Asc act synergistically in suppression of the sunburn reaction.

Assessing remission in clinical practice

OBJECTIVE

Remission constitutes the best achievable state in patients with rheumatoid arthritis. We aimed at evaluating sustained remission in a large cohort of patients followed prospectively in clinical practice and to evaluate available instruments to define remission for their stringency in defining this state.

PATIENTS AND METHODS

We analysed remission and sustained remission in 621 patients who had two consecutive and complete clinical observations; the average period between the two visits was 92 days (median; quartiles: 82; 105). Remission was evaluated according to modified ACR (mACR), 28 Joint Disease Activity Score (DAS28), Simplified Disease Activity Index (SDAI) and Clinical Disease Activity Index (CDAI) criteria. Sustained remission was defined as remission at both consecutive visits. Patients were treated with traditional disease- modifying antirheumatic drugs, mainly methotrexate, and partly with biological agents (approximately 11%).

RESULTS

Remissions at any one of the two visits were seen in 33.5% of patients by SDAI or CDAI, 42.7% by DAS28, and 38.6% by mACR criteria (P < 0.01). Sustained remission was observed in much lower proportions of patients (between 16.7 and 19.6%, dependent on the instrument). Agreement between classifications of remission by kappa-statistics was very good for SDAI vs CDAI, good for DAS28 vs SDAI or CDAI, and only moderate for mACR vs the three other scores. Residual swollen joints were observed in 15% of patients in DAS28 remission (range 1-9), 6% of patients in mACR remission (range 1-8), but only approximately 5% of patients in CDAI or SDAI remission (range 1-2) (P < 0.01).

CONCLUSION

Sustained remission can be observed in 17-20% of patients in clinical practice. CDAI and SDAI remission criteria are more stringent than DAS28 and mACR criteria, since they allow for lesser residual disease activity. Consequently, smaller proportions of patients are classified as in remission by SDAI and CDAI than by DAS28 and mACR criteria. Sustained remission is an achievable goal in clinical practice even with the most stringent of the definitions studied.

A Ty3/gypsy retrotransposon-like sequence localizes to the centromeric regions of cereal chromosomes

A 745 bp sequence (pSau3A9) located at the centromeres of several cereal species was isolated from a sorghum BAC library by Jiang et al. (1996, Proc. Natl Acad. Sci. USA, 93, 14210-14213). We have amplified a partially homologous 809 bp sequence from barely genomic DNA by PCR and localized it to the centromeres of barley, wheat and rye chromosomes by fluorescent in situ hybridization (FISH). Sequence analysis showed this barley homolog of pSau3A9 to have high similarity to the integrase region of the polyprotein gene of Ty3/gypsy group retrotransposons. Using this integrase sequence as a probe, several clones were isolated from a lambda library constructed of genomic barley DNA. One of the lambda clones contained coding regions for all five catalytic sites characteristic of the retrotransposon polyprotein. Two direct repeats flanking the polyprotein gene are homologous to the cereal centromeric sequence described by Aragón-Alcaide et al. (1996, Chromosoma, 105, 261-268) and may represent all or part of the long-terminal repeats (LTRs). Different plasmid subclones containing various regions of the lambda clone were used in FISH to show that the entire polyprotein gene and upstream flanking sequences, including the presumed LTR, are present at barley centromeres. The preferential (or exclusive) localization of an apparently complete retroelement within the centromeric regions of several cereal species raises interesting questions about its role in karyotype evolution and centromere function.

Laboratory formation of a scaled protostellar jet by coaligned poloidal magnetic field

Although bipolar jets are seen emerging from a wide variety of astrophysical systems, the issue of their formation and morphology beyond their launching is still under study. Our scaled laboratory experiments, representative of young stellar object outflows, reveal that stable and narrow collimation of the entire flow can result from the presence of a poloidal magnetic field whose strength is consistent with observations. The laboratory plasma becomes focused with an interior cavity. This gives rise to a standing conical shock from which the jet emerges. Following simulations of the process at the full astrophysical scale, we conclude that it can also explain recently discovered x-ray emission features observed in low-density regions at the base of protostellar jets, such as the well-studied jet HH 154.

UV-induced free radicals in the skin detected by ESR spectroscopy and imaging using nitroxides

Reactive free radicals and reactive oxygen species (ROS) induced by ultraviolet irradiation in human skin are strongly involved in the occurrence of skin damages like aging and cancer. In the present work an ex vivo method for the detection of free radicals/ROS in human skin biopsies during UV irradiation is presented. This method is based on the Electron Spin Resonance (ESR) spectroscopy and imaging and uses the radical trapping properties of nitroxides. The nitroxides 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO), 3-Carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCM), and 3-Carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCA), were investigated for their applicability of trapping reactive free radicals and reactive oxygen species in skin during UV irradiation. As a result of the trapping process the nitroxides were reduced to the EPR silent hydroxylamins. The reduction rate of TEMPO was due to both the UV radiation and the enzymatic activity of the skin. The nitroxides PCM and PCA are sufficiently stable in the skin and are solely reduced by UV-generated free radicals/ROS. The nitroxide PCA was used for imaging the spatial distribution of UV-generated free radicals/ROS. As a result of the homogeneous distribution of PCA in the skin, it was possible to estimate the penetration of UVA and UVB irradiation: The UV irradiation decreased the PCA intensity corresponding to its irradiance and penetration into the skin. This reduction was shown to be caused mainly by UVA radiation (320-400 nm).

Ultralow emittance, multi-MeV proton beams from a laser virtual-cathode plasma accelerator

The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10(-4) eV s, i.e., at least 100-fold and may be as much as 10(4)-fold better than conventional accelerator beams. The fast acceleration being electrostatic from an initially cold surface, only collisions with the accelerating fast electrons appear to limit the beam laminarity. The ion beam source size is measured to be <15 microm (FWHM) for proton energies >10 MeV.

Potentials and limitations of the natural antioxidants RRR-alpha-tocopherol, L-ascorbic acid and beta-carotene in cutaneous photoprotection

Sun exposure has been linked to several types of skin damage including sun burn, photoimmunosuppression, photoaging and photocarcinogenesis. In view of the increasing awareness of the potentially detrimental long term side effects of chronic solar irradiation there is a general need for safe and effective photoprotectants. One likely hypothesis for the genesis of skin pathologies due to solar radiation is the increased formation of reactive oxidants and impairment of the cutaneous antioxidant system. Consequently, oral antioxidants that scavenge reactive oxidants and modulate the cellular redox status may be useful; systemic photoprotection overcomes some of the problems associated with the topical use of sunscreens. Preclinical studies amply illustrate the photoprotective properties of supplemented antioxidants, particularly RRR-alpha-tocopherol, L-ascorbate and beta-carotene. However, clinical evidence that these antioxidants prevent, retard or slow down solar skin damage is not yet convincing. The purpose of this review is to provide the reader with current information on cutaneous pathophysiology of photoxidative stress, to review the literature on antioxidant photoprotection and to discuss the caveats of the photo-oxidative stress hypothesis.

A small synthetic peptide, which inhibits the p53-hdm2 interaction, stimulates the p53 pathway in tumour cell lines

The hdm2 protein negatively regulates p53 tumour suppressor activity. Upon binding to p53, hdm2 stimulates p53 degradation and inhibits its transcriptional activity. Moreover, the hdm2 protein is overexpressed in various tumours inactivating p53. We report here that an octamer synthetic peptide derived from p53 inhibits the p53-hdm2 interaction in vitro. In cellular assays, this untagged peptide penetrates tumour cells and induces the accumulation of p53. The accumulation of p53 leads to its activation. Two gene products transcriptionally regulated by p53, p21Waf1/Cip1 and hdm2, are induced in the presence of the peptide. When used with tumour cells that overexpress hdm2, the peptide induces the death of these tumour cells by apoptosis. The mode of action of this peptide differs from that of DNA-damaging agents (e.g. cisplatin) in that it does not induce p53 phosphorylation on serine 15. This work validates with a low molecular mass molecule our current knowledge on the regulation of the p53 pathway by the hdm2 protein. It also shows that inhibitors of the p53-hdm2 interaction are very attractive candidates for the activation of the p53 pathway in tumours expressing wild-type p53.

Classic, atypically severe and neonatal Marfan syndrome: twelve mutations and genotype-phenotype correlations in FBN1 exons 24-40

Mutations in the gene for fibrillin-1 (FBN1) cause Marfan syndrome, an autosomal dominant disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular system. There is a remarkable degree of clinical variability both within and between families with Marfan syndrome as well as in individuals with related disorders of connective tissue caused by FBN1 mutations and collectively termed type-1 fibrillinopathies. The so-called neonatal region in FBN1 exons 24-32 comprises one of the few generally accepted genotype-phenotype correlations described to date. In this work, we report 12 FBN1 mutations identified by temperature-gradient gel electrophoresis screening of exons 24-40 in 127 individuals with Marfan syndrome or related disorders. The data reported here, together with other published reports, document a significant clustering of mutations in exons 24-32. Although all reported mutations associated with neonatal Marfan syndrome and the majority of point mutations associated with atypically severe presentations have been found in exons 24-32, mutations associated with classic Marfan syndrome occur in this region as well. It is not possible to predict whether a given mutation in exons 24-32 will be associated with classic, atypically severe, or neonatal Marfan syndrome.

How do Alliaceae stabilize their chromosome ends in the absence of TTTAGGG sequences?

The Arabidopsis-type telomeric repeats (5'-TTTAGGG-3) are highly conserved. In most families of different plant phyla they represent the basic sequence of telomeres that stabilize and protect the chromosome termini. The results presented here show that Alliaceae and some related liliaceous species have no tandemly repeated TTTAGGG sequences. Instead, their chromosomes reveal highly repetitive satellite and/or rDNA sequences at the very ends. These apparently substitute the original plant telomeric sequences in Alliaceae. Both sequence types are very active in homologous recombination and may contribute to the stabilization of chromosome termini via compensation of replication-mediated shortening.

The role of oxygen in cutaneous photodynamic therapy

Photodynamic therapy (PDT) is based on the dye-sensitized photooxidation of biological matter in the target tissue, and utilizes light activated drugs for the treatment of a wide variety of malignancies. Skin is a target organ for PDT, because of the increasing incidence of skin cancers and the easy accessibility to photosensitizing drugs and light. Skin oxygen tension changes dramatically during and after PDT and seems to be an important treatment parameter. Experimental approaches to modulate oxygen tension (e.g., hyperbaric oxygenation, hyperthermia, or perfluorocarbons) have been studied mainly in animals, and some of these techniques may have the potential to be applied in humans to improve the efficacy and safety of PDT. The main purpose of this review is to provide the reader with current information on cutaneous oxygen physiology and oximetry, the role of oxygen and singlet oxygen (1O2) in PDT, and approaches to modulate skin oxygen tension. The literature indicates that it may be possible to utilize transcutaneous oxygen measurements as a valuable measure of the clinical effectiveness of PDT and as an in situ predictor of the energy required to elicit a biological response. Consequently the effectiveness of PDT can be manipulated by modulating skin oxygen tension.

Measurements of UV-generated free radicals/reactive oxygen species (ROS) in skin

Free radicals/reactive oxygen species (ROS) generated in skin by UV irradiation were measured by electron spin resonance (ESR). To increase the sensitivity of measurement the short life free radicals/ROS were scavenged and accumulated by using the nitroxyl probe 3-carboxy-2,2,5,5-tetrametylpyrrolidine-1-oxyl (PCA). The spatial distribution of free radicals/ROS measured in pig skin biopsies with ESR imaging after UV irradiation corresponds to the intensity decay of irradiance in the depth of the skin. The main part of free radicals/ROS were generated by UVA (320-400 nm) so that the spatial distribution of free radicals reaches up to the lower side of the dermis. In vivo measurements on human skin were performed with a L-band ESR spectrometer and a surface coil integrating the signal intensities from all skin layers to get a sufficient signal amplitude. Using this experimental arrangement the protection of UVB and UVA/B filter against the generation of free radicals/ROS in skin were measured. The protection against ROS and the repair of damages caused by them can be realized with active antioxidants characterized by a high antioxidative power (AP). The effect of UV filter and antioxidants corresponding to their protection against free radicals/ROS in skin generated by UVAB irradiation can be quantified by the new radical sun protection factor (RSF). The RSF indicates the increase of time for staying in the sun to generate the same number of free radicals/ROS in the skin like for the unprotected skin. Regarding the amount of generated free radicals/ROS in skin as an biophysical endpoint the RSF characterizes both the protection against UVB and UVA radiation.

Acute effects of near ultraviolet and visible light on the cutaneous antioxidant defense system

Reactive oxygen species are considered to play an important role in cutaneous pathology. Enzymic and non-enzymic antioxidants can prevent oxidative damage but may be overcome by strong pro-oxidative stimuli. The acute effect of a single exposure to near ultraviolet (UVA)/visible radiation (greater than 320 nm) on various skin antioxidants was examined in hairless mice immediately after irradiation. Impairment of cutaneous catalase and glutathione reductase activity was observed. Superoxide dismutase and glutathione peroxidase were not significantly influenced. Inhibition of catalase may render skin more susceptible to the damaging effects of hydrogen peroxide and its reaction products such as the hydroxyl radical. Partially diminished glutathione reductase activity is not accompanied by a change in reduced/oxidized glutathione level immediately after irradiation. There was a tendential (not statistically significant) decrease in cutaneous tocopherol, ubiquinol + ubiquinone 9 and ascorbic acid levels, either indicating direct photodestruction or consumption by reaction products of photooxidative stress. This partial impairment of the cutaneous antioxidant defense system by near ultraviolet/visible light, showing that the most susceptible component in skin is catalase, suggests possible pharmacological interventions.