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PubMed2003

The UV responsive elements in the human mimecan promoter: a functional characterization.

PURPOSE: A major environmental stress encountered by humans is solar UV light, which can cause a spectrum of eye diseases, such as photokeratitis, cataract, pterygia, and ocular neoplasms. Mammalian defense mechanisms in response to adverse effects of UV light result in induction of a number of genes. Studies on the transcriptional regulation of genes that are expressed in the eye will increase understanding of both the physiological functions of these genes in the mammalian UV response, and the molecular bases for abnormalities associated with the above diseases. Mimecan is an extracellular matrix proteoglycan that is abundantly expressed in the cornea. The purpose of this study was to determine and characterize the UV responsive regulatory elements of the human mimecan promoter. METHODS: Transcriptional activity of the promoter was evaluated, before and after UV irradiation, using transient transfection of human mimecan promoter/luciferase reporter constructs into corneal keratocytes and non-corneal cells. Site directed mutagenesis and corresponding functional assays were used to determine the contribution of UV responsive regions to human mimecan transcription. Co-transfection experiments were used to investigate the role of transcription factors that bind these elements in the promoter and mediate the UV response. mRNA expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The shortest promoter construct that was strongly activated following UV irradiation contained three initiator elements, an E-box element that is conserved between species, and the entire first intron of the human mimecan gene. Deletion of the intronic p53 binding site from this construct considerably diminished transcription and the UV response of the promoter. Surprisingly, deletion of the E-box sequence from this construct completely abolished both transcription and UV response of the promoter. These results demonstrated that the E-box is essential to transcription of the human mimecan gene and also is required for activation by p53. The role of the E-box, and the E-box binding protein, USF-1, in transcription and UV responses of the human mimecan promoter were confirmed by co-transfection experiments using dominant negative transcription factor, A-USF. In addition to these positive regulators, we demonstrate that the region between nucleotides -1314 and -1907 contains a transcriptional repressor site that is active in a time dependent manner following UV irradiation. Finally, we show that UV irradiation results in changes in mimecan mRNA levels in bovine corneal keratocytes in a time-dependent manner. CONCLUSIONS: The human mimecan promoter contains several UV responsive regulatory elements that are conserved between human and bovine species and include the intronic p53 DNA binding site, the E-box in the proximal promoter, and the region between nucleotides -1314 and -1907. The E-box plays an important role in transcription and UV response of the human mimecan promoter. UV irradiation modulates expression of mimecan mRNA in bovine corneal keratocytes and non-corneal cells.

Animals↗
PubMed2003

Cystine urinary lithiasis in Thailand: a report of five cases.

Cystine urinary stone is an autosomal recessive hereditary disease, frequently recurring and resisting fragmentation by Shockwave lithotripsy. As cases have never been reported before in Thailand, five cases of renal cystine stones at Ramathibodi Hospital were reported. Two were in the same family. In all cases the stones were removed by open surgery or percutaneous nephrolithotomy. Postoperatively, all the stones were analyzed by infrared spectroscopy for cystine. In two cases, cystine stones were also identified by scanning electron microscopy. Urine was analyzed for cystine by sodium cyanide-nitroprusside test, its concentration by spectrophotometry and cystine crystals were identified by the new crystal induction technique under light microscopy. By high-performance liquid chromatography (HPLC) test, urinary dibasic amino acids (ornithine, lysine, arginine) in these cases were also found to be significantly elevated. Clinical findings, diagnosis, treatment and prevention of cystine stones are reviewed.

Adult↗
PubMed1986

The role of dominant visibles in mutagenicity testing.

Our results suggest that inclusion of growth retardation as one of the components of the dominant visible category will make this a useful end-point for mutational studies in which it is important to gauge the extent to which transmissible genetic damage of a particularly relevant kind is induced in mammals. These visibles are easily scored and the use of an automated weighing device would lessen subjectivity. In the present experiment with 5Gy + 5Gy spermatogonial X-irradiation (24h interval) 7309 offspring have been examined at weaning age and 23 heritable dominant visibles identified. These included 12 with growth retardation, one of which was mutant at the steel (S1) locus, as were 3-4 others of normal size. However, only 46 out of 112 offspring recorded as small were actually kept for genetic tests, while only 30 (65%) of these could be fully tested because of death or infertility in the others. Thus this experiment throws some light on the induction of presumptive dominant sub-lethals which survive until weaning age, a little-studied category. Twelve out of the 30 fully tested small mice (40%) proved to carry dominant visible mutations. If this proportion is applied to the total recorded as small then we can derive an overall total of about 45 mutations for growth retardation. It is hoped to determine the actual rate of induction of these by further work.

Animals↗
PubMedDate not supplied

[Results of autotransplantation of hepatocytes in hepatectomized rats].

With a view of clarifying the mechanism whereby the beneficial effect of hepatocyte transplantation is obtained, an autologous transplant was made of hepatocytes in the peritoneum of a surgical model of acute hepatic insufficiency in the rat, highly reproducible to the detriment of its reversibility. The cells were prepared in accordance with the non-perfusional enzymatic method proposed by Fry. The cell yield from 3 g of liver tissue was 4 X 10(6), with an index of viability of over 70%. There was no difference in survival between the treated animals and the control group, though coma appeared significantly later in the former. The conclusion is therefore drawn that transplantation offers no metabolic support to the anhepatic animal. Further investigation is required of the biochemical and metabolic aspects of the function of the hepatocyte in the light of its induction of a significant delay in the appearance of coma.

Animals↗
PubMed1984

Diurnal rhythm of rat liver mRNAs encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase. Correlation of functional and total mRNA levels with enzyme activity and protein.

Rat liver 3-hydroxy-3-methylglutaryl coenzyme A reductase exhibits a diurnal rhythm of activity which coincides with a diurnal rhythm of reductase protein and reductase mRNA levels. This diurnal rhythm of reductase activity, polypeptide mass, and mRNA exists in rats fed a normal diet (unsupplemented rat chow) and in rats fed a diet supplemented with cholestyramine plus or minus mevinolin. Levels of reductase protein were determined by 8 M urea/sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. Reductase mRNA was measured by in vitro translation or blot hybridization of liver RNA. Functional reductase mRNA levels in rats fed a normal diet were approximately 10-fold higher during the middle of the dark cycle than during the middle of the light cycle. Maximum induction of functional reductase mRNA was observed in rats fed cholestyramine and mevinolin. This latter level was 157-fold higher than the level measured at the diurnal low point in rats fed a normal diet. Blot hybridization of liver RNA showed two predominant mRNAs of 4.6 and 4.2 kilobase pairs and a minor species at 6.9 kilobase pairs. These mRNAs exhibited a diurnal rhythm for rats on all three diets and reached peak levels during the 12-h dark period. These data indicate that the diurnal rhythm of reductase mass and activity is closely paralleled by the level of its mRNA.

Animals↗
PubMed1993

[UV exposure, skin cancer and decrease in the ozone layer].

All over the world a remarkable increase in malignant tumors of the skin is reported. More than 90% of them are localized in areas of the skin exposed to sunlight. The incidence of malignant melanomas of the skin is tenfold higher today than 40 years ago. Experimental data and results of epidemiological studies indicate two different risk patterns of UV exposure for the development of skin cancer. The cumulative UV-light exposure during lifetime induces--especially in light-sensitive individuals older than 60 years--actinic elastosis, precanceroses and squamous cell carcinomas as well as lentigo maligna melanomas. Intense UV exposure in childhood and youth may lead to development of superficial spreading melanomas and nodular melanomas between the age of 20 and 40. The reduction of ozone in the stratosphere could still contribute to a higher incidence of tumors of the skin in the next decades. The evident role of UVB light in the induction of tumors of the skin offers the possibility for preventive strategies.

Atmosphere↗
PubMed1981

The role of chromosomal proteins in the induction of a differential staining of sister chromatids by light.

Fixed chromosomes of human lymphocytes, cultured in the presence of bromodeoxyuridine (BrdU) during two cell cycles, were exposed to near-ultraviolet irradiation, stained with Giemsa, and after destaining, were subjected to either Coomassie Blue or Feulgen--Schiff staining. A differential reaction of sister chromatids was first revealed by Coomassie Blue staining. Differential staining with Giemsa required a longer irradiation time. This appeared to be reduced after the addition of dithiodipyridine to the cells during their last few hours of culture. The differential pattern obtained after Coomassie Blue staining was the inverse of that obtained after Giemsa staining. From these findings we concluded that the induction of sister chromatid differentiation by light in BrdU-substituted DNA containing chromosomes occurs primarily via chromosomal proteins, presumably by differential breakage of their disulphide bonds. The results of the Feulgen--Schiff staining indicated that differential depurination of BrdU-containing DNA could occur, although only after very prolonged irradiation. A faint though distinctly differential Feulgen--Schiff pattern of sister chromatid staining, resulting from differential removal of DNA, was observed after photosensitization by specific DNA-binding dyes. Thus, DNA seems to be affected only under more extreme conditions.

Bromodeoxyuridine↗
PubMed2005

Light-induced fluorescence of the human cervix decreases after prostaglandin application for induction of labor at term.

OBJECTIVE: To define the changes in cervical light-induced fluorescence (LIF), an index of cross-linked collagen, after the use of locally applied prostaglandin preparations for labor induction at term and the correlation between LIF and Bishop-Score. STUDY DESIGN: The characteristic LIF of cervical collagen was measured from the surface of the cervix using a specially designed instrument (collascope) in 41 gravidas undergoing labor induction at term by prostaglandins. LIF and Bishop-Score were obtained directly before and 4h after the administration of prostaglandin. Paired Student's t-test, Wilcoxon Signed Rank test, Linear Regression, Spearman correlation and Fisher Exact test were used as appropriate. RESULTS: Cervical LIF decreased significantly after prostaglandin application (0.982+/-0.04 [before] to 0.885+/-0.037 [after], p=0.025). The decrease in LIF correlated with the initial LIF before PG-application (r=0.61). The Bishop-Score increased in all 41 patients. No correlation was found between LIF versus Bishop-Score. CONCLUSIONS: Cervical application of prostaglandins decreases the amount of cross-linked collagen as measured by LIF. This effect was observed only in patients with a prior high cross-linked collagen.

Administration, Topical↗
PubMed1986

Variation in sister chromatid exchange frequencies between human and pig whole blood, plasma leukocyte, and mononuclear leukocyte cultures.

Sister chromatid exchange (SCE) induction by ultraviolet (UV) light was studied in both human and pig whole blood cultures (WBC) and plasma leukocyte cultures (PLC). No variation in SCE frequency was observed between pig WBC and PLC in control as well as in treated cells. Conversely, SCE frequencies of human PLC were consistently higher than those of WBC in control and UV-exposed cells. Thus, red blood cells (RBCs) do not influence the sensitivity of lymphocytes to UV light exposure, and there must be some different culture condition(s) in the induction of SCEs between human WBC and PLC but not in swine lymphocyte cultures. Since the BrdUrd/lymphocyte ratio of WBC was halved in PLC, the effect of BrdUrd concentration in inducing the SCE baseline frequency of PLC may be ruled out. Also, Ficoll-Hypaque-separated human mononuclear leukocytes in culture (MLC), but not pig MLC, showed a two-fold increase in SCE frequency over WBC values. Thus, neither the cell separation technique nor polymorphonuclear leukocytes had a significant role in the elevated SCE frequency of human PLC or MLC. Experiments where human RBCs were titrated into human PLC showed that the induction of an elevated SCE frequency of PLC was suppressed in a dose-dependent manner by the presence of RBCs in the culture medium. Since the incorporation of pig or human RBCs into human PLC as well as into MLC reduced the SCE frequency to that of WBC, a common component and/or function existing in these cells is suggested. Analysis of different RBC components showed that RBCs, specifically RBC ghosts, release a diffusible but not dialyzable "corrective" factor into culture medium that is able to reduce the SCE frequencies of PLC. Antioxidant enzymes such as catalase and horseradish peroxidase were unable to reduce the SCE frequency of human PLC to WBC values.

Animals↗
PubMed1998

Use of prostaglandin E2 to ripen the cervix of the mare prior to induction of parturition.

Eleven light-breed pregnant mares (335 to 347 d gestaton) were used to evaluate the use of prostaglandin E2 as a cervical ripening agent prior to induction of parturition during the months of April and May. Six hours prior to induction, each mare's cervix was examined per vagina for softness and dilation. Each mare was then assigned to 1 of 2 treatment groups: Group PGE mares (n = 7) received 2.0 to 2.5 mg prostaglandin E2 deposited intracervically; Group SAL mares (n = 4) received 0.5 mL of sterile NaCl deposited intracervically. Six hours later, the mares were readied for parturition by wrapping the tail, scrubbing and rinsing the perineum and udder, and examining the cervix as previously described. Each mare was then administered 15 U, i.v. oxytocin at 15-min intervals until the chorioallantois ruptured. Intervals from initial oxytocin injection until rupture of the chorioallantois, from initial oxytocin injection until delivery of the foal, from delivery of the foal until the foal stood unassisted, and from delivery of the foal until the foal suckled were recorded. Mean cervical dilation immediately prior to induction of parturition tended to be greater in Group PGE mares (3.9 +/- 1.7 cm) than in Group SAL mares (1.9 +/- 1.9 cm; P = 0.10). Mean change in cervical dilation over the 6-h period prior to induction (3.4 +/- 1.9 cm vs 1.5 +/- 2.1 cm), mean number of injections of oxytocin required until the chorioallantois ruptured (1.9 +/- 0.7 vs 2.5 +/- 1.0), and mean intervals from initial injection of oxytocin to rupture of the chorioallantois (20 +/- 10 min vs 28 +/- 19 min) and delivery of the foal (28 +/- 7 min vs 34 +/- 22 min) were not different between Group PGE and SAL mares, respectively (P > 0.10). The proportion of foals that stood within 1 h of birth also did not differ between Group PGE foals (6/7; 86%) and Group SAL foals (3/4; 75%; Chi-square = 0.17; P > 0.10). The proportion of foals that nursed within 2 h of birth was higher in Group PGE foals (6/7; 86%) than in Group SAL foals (1/4; 25%; Chi-square = 4.02; P < 0.05). Premature separation requiring manual rupture of the chorioallantois at the vulvar labia occurred in 1 Group PGE mare (cervical dilation of 1.5 cm at time of induction) and 1 Group SAL mare (cervix closed and firm at time of induction). Foals born from the 2 mares with premature placental separation had the longest intervals from initial oxytocin injection to delivery, delivery to ability to stand unassisted, and delivery to suckling within their respective treatment groups. In summary, it appears that cervical ripening prior to induction of parturition favors shorter deliveries and foal vigor. Intracervical administration of prostaglandin E2 may prove useful for ripening the cervix of the mare prior to induction of parturition. Further studies are indicated to determine optimal dosage and method of administration of prostaglandin E2.

Allantois↗
PubMed1993

Ultrastructural studies bearing on the mechanism of UVB-impaired induction of contact hypersensitivity to DNCB in man.

In both murine and human experimental systems, acute, low dose exposure of skin to ultraviolet B light (UVB) impairs the induction of allergic contact dermatitis (ACD) by haptens such as dinitrochlorobenzene (DNCB) in a significant proportion of individuals. By light microscopy, epidermal Langerhans cells (LC) have been reported to be depleted by UVB exposure as well as by epicutaneous hapten application, implying that LC may be the locus of action of the effects of both UVB and DNCB. However, light microscopy can not readily distinguish cell density changes secondary to LC necrosis from changes resulting from down-modulation of expression of LC surface molecules. Using a highly sensitive immunogold electron microscopic approach, we have evaluated the differential effects of UVB and/or DNCB on human epidermal LC. The results reveal that DNCB alone caused significant up-regulation of cell surface HLA class II expression on a very small number of LC, the major fraction of LC expressing normal levels of HLA class II. Furthermore, DNCB alone caused a modest reduction in the density of LC at the treated sites without evidence of cell necrosis. Treatment with UVB alone or UVB exposure followed by DNCB resulted in a reduction in the density of LC, with widespread evidence of LC necrosis. However, the few remaining intact LC were all intensely HLA class II-positive after UVB exposure followed by DNCB, whereas treatment with UVB alone did not result in changes in LC HLA class II expression. The findings that after DNCB painting only a small proportion of the LC were strongly HLA class II-positive, but after UVB exposure followed by DNCB all intact LC displayed significant up-regulation of cell surface HLA class II expression, imply that UVB exposure inhibits the migration of epidermal LC. This is consistent with the view that DNCB fails to induce ACD when hapten is painted on UVB-exposed skin because insufficient LC are available to initiate T cell activation in the draining lymph node.

Cell Count↗
PubMed1991

Short light-dark cycles influence sleep stages and EEG power spectra in the rat.

To investigate the influence of light on sleep and the electroencephalogram (EEG), chronically implanted rats were continuously recorded during a baseline day under 12-h light-12-h dark (LD 12:12) conditions, and an experimental day with short LD (LD 1:1) cycles. The percentage of non-REM sleep (NREMS) was higher and the percentage of REM sleep (REMS) lower in the 1-h light [corrected] intervals than in the 1-h dark intervals. The maximum of NREMS induction by 1-h light occurred in the habitual 12-h dark period (activity period), while the largest enhancement of REMS by 1-h darkness occurred in the second half of the habitual 12-h light period (rest period). The EEG of waking, NREMS and REMS was subjected to spectral analysis to determine the power density of the frequency components in the range of 0.25-25.0 Hz. The overall 24-h time course of the EEG-spectra in NREMS was similar under baseline and experimental conditions. Nevertheless, the spectra were modified by the short LD-cycle. In NREMS, the values in the middle and high frequencies (greater than 6 Hz in the rest period; greater than 11 Hz in the activity period) were lower in the 1-h light intervals than in the 1-h dark intervals. In contrast, activity in some frequency bands during waking and REMS was higher in the light than in the dark intervals. It is concluded that the short LD-cycle modulates the vigilance states and induces state-specific changes in the EEG, whereas circadian aspects of sleep are little affected.

Animals↗
PubMed2003

Light-induced carotenogenesis in Myxococcus xanthus: functional characterization of the ECF sigma factor CarQ and antisigma factor CarR.

Illumination of dark-grown Myxococcus xanthus with blue light leads to the induction of carotenoid synthesis. Central to this response is the activation of the light-inducible promoter, PcarQRS, and the transcription of three downstream genes, carQ, carR and carS. Sequence analysis predicted that CarQ is a member of the ECF (extracytoplasmic function) subfamily of RNA polymerase sigma factors, and that CarR is an inner membrane protein. Genetic analysis strongly implied that CarR is an antisigma factor that sequesters CarQ in a transcriptionally inactive complex. Using in vitro transcription run-off assays, we present biochemical evidence that CarQ functions as a bacterial sigma factor and is responsible for transcription initiation at PcarQRS. Similar experiments using the crtI promoter failed to implicate CarQ in direct transcription of the crtI gene. Experiments using the yeast two-hybrid system demonstrated a protein-protein interaction between CarQ and CarR, providing evidence of a CarQ-CarR complex. The yeast two-hybrid system data also indicated that CarR is capable of oligomerization. Fractionation of M. xanthus membranes with the detergent sarkosyl showed that CarR was associated with the inner membrane. Furthermore, CarR was found to be unstable in illuminated stationary phase cells, providing a possible mechanism by which the CarR-CarQ complex is disrupted.

Bacterial Proteins↗
PubMed1966

Light induced concentration changes of adenosine-triphosphate in phycomyces sporangiophores.

The concentrations of extractable adenosine triphosphate (ATP) following the induction of positive light-growth responses in Phycomyces sporangiophores by blue light stimuli have been measured by means of the luciferin-luciferase assay. The ATP concentration in the light-sensitive growing zone increases 30 to 50% within 30 seconds after the start of a light stimulus and returns to the normal adapted level within 1 minute after stimulation. The ATP concentration is constant for any level of light adaptation and is uniform along the length of sporangiophores even though the light sensitivity is confined to a growing zone less than 5 mm long. These results suggest that one of the initial biochemical steps after a light stimulus is the production of extractable ATP.

Adenosine Triphosphate↗
PubMed1989

Translational regulation of the synthesis of euglena fumarase by light and ethanol.

Ethanol addition or the exposure of dark-grown resting Euglena to light produced a transient increase in the rate of fumarase synthesis as measured by pulse-labeling with [(35)S]sulfate and immunoprecipitation. The half-life of fumarase in the dark and in the light was similar. In the plastidless mutant W(3)BUL, fumarase synthesis was transiently induced by light indicating that fumarase induction is regulated by a nonchloroplast photoreceptor. In the plastidless mutant W(10)BSmL, light exposure did not increase the rate of fumarase synthesis while the addition of ethanol transiently induced fumarase synthesis. The nonchloroplast photoreceptor regulating fumarase synthesis appears to be absent or nonfunctional in W(10)BSmL. In vitro translation of Euglena RNA in a rabbit reticulocyte lysate showed that fumarase is synthesized as a precursor of 61.5 kilodaltons which is 1.5 kilodaltons larger than the mature protein. The levels of translatable RNA for fumarase were similar in the dark and after light exposure or ethanol addition. The transient increase in the in vivo rate of fumarase synthesis after light exposure or organic carbon addition was not accompanied by a concomitant increase in the level of translatable RNA for fumarase. The synthesis of fumarase in dark grown resting Euglena upon light exposure and ethanol addition is controlled at the translational rather than at the transcriptional level.

Journal Article↗
PubMed1981

Differential retinoic acid inhibition of ornithine decarboxylase induction by 12-O-tetradecanoylphorbol-13-acetate and by germicidal ultraviolet light.

Several retinoids including retinoic acid effectively inhibit phorbol ester-mediated tumor promotion and ornithine decarboxylase (ODC) induction in mouse epidermis. To understand better the possible cellular site of action of retinoids, the inhibitory action of retinoic acid on the induction of ODC was compared for two distinctly different inducers, namely, 12-O-tetradecanoylphorbol-13-acetate (TPA) and germicidal ultraviolet light (UV), in primary mouse epidermal cell cultures. It was found that the induction of ODC by TPA is almost completely prevented by 0.1 to 1 microM retinoic acid while the induction by UV is only moderately inhibited. Maximum inhibition is achieved by treating cells continuously with retinoic acid from 4 hr after plating, although pretreatment or simultaneous treatment relative to either inducer is almost as effective. When added after the inducer, retinoic acid loses its effectiveness as an inhibitor more rapidly for TPA induction than for UV induction of ODC. The differential inhibition of enzyme induction cannot be accounted for by selective retinoid inhibition of DNA, RNA, or protein synthesis either alone or in concert with TPA or UV. Other agents known to modulate the induction of ODC by TPA (fluocinolone acetonide, tosyl-L-lysylchloromethane, and local anesthetics) do not act differentially on UV induction. These agents possibly act at transcription or translation, both of which are required for ODC induction by TPA or UV. The preferential inhibition by retinoic acid of ODC induction by TPA is interpreted to result from specific interference at a unique and early site of interaction of TPA with the cell.

Animals↗
PubMed1992

Induction of Nitrate Assimilatory Enzymes in the Tree Betula pendula.

The coordinate appearance of the bispecific NAD(P)H-nitrate reductase (NR; EC 1.6.6.2) and nitrite reductase (NiR; EC 1.7.7.1) was investigated in leaves and roots from European white birch seedlings (Betula pendula Roth). Induction by nitrate and light of both enzymes was analyzed by in vitro assays and by measuring NR- and NiR-encoding mRNA pools with homologous cDNAs as probes. When birch seedlings were grown on a medium containing ammonium as the sole nitrogen source, low constitutive expression of NR and NiR was observed in leaves, whereas only NiR was significantly expressed in roots. Upon transfer of the seedlings to a nitrate-containing medium, mRNA pools and activities of NR and NiR dramatically increased in leaves and roots, with a more rapid induction in leaves. Peak accumulations of mRNA pools preceded the maximum activities of NR and NiR, suggesting that the appearance of both activities can be mainly attributed to an increased expression of NR and NiR genes. Expression of NR was strictly light-dependent in leaves and roots and was repressed by ammonium in roots but not in leaves. In contrast with NR, constitutive expression of NiR was not affected by light, and even a slight induction following the addition of nitrate was found in the dark in roots but not in leaves. No effect of ammonium on NiR expression was detectable in both organs. In leaves as well as in roots, NiR was induced more rapidly than NR, which appears to be a safety measure to prevent nitrite accumulation.

Journal Article↗
PubMed1995

Induction of cyclobutane pyrimidine dimer photolyase in cultured fish cells by fluorescent light and oxygen stress.

The expression of a gene for photolyase in RBCF-1 cells, a line of cultured goldfish cells, is known to be enhanced by fluorescent light. We have now found that H2O2 is another strong inducer of cyclobutane pyrimidine dimer photolyase. Northern blot analysis suggested that regulation by H2O2 occurs at the transcriptional level and the time course of induction of photolyase by H2O2 was similar to that by fluorescent light. Treatment with fluorescent light in the presence of riboflavin, which is known as an endogenous photosensitizer, also enhanced the induction of photolyase. These results suggest the involvement of oxygen stress in the induction of photolyase by fluorescent light. A cell clone with high-level expression of the goldfish gene for photolyase was obtained by transfection with plasmids that expressed the goldfish photolyase in OL32 cells derived from another fish, the medaka (Oryzias latipes). The induction of the medaka gene for photolyase was not affected by the high-level expression of the goldfish gene for this enzyme.

Animals↗