The effect of local UVB skin irradiation on the rate of formazan deposition in the epidermis of hairless mice studied by means of a tetrazolium-reduction method
3
Citation
8
Reference
10
Related Paper
Abstract:
One-hundred-and-twenty hairless mice were irradiated with UVB (310 nm, exposure 60 mJ/cm2) on a limited area of the dorsal skin. At different time intervals after irradiation, the rate of endogenous dehydrogenase activity per mg dry epidermis was measured by the tetrazolium reduction method. The amount of formazan deposited remained normal for 18 h, and then increased, reaching a peak significantly higher than normal at 24 h, and thereafter returned to normal. At day 8 there was a new, probably significant peak. The reaction was followed for 14 days. It was concluded that UVB irradiation provokes a period of increased formazan deposition in the epidermis, similar to what has been observed after ionizing radiation and chemical carcinogens. The validity of the tetrazolium test for skin carcinogenic irritaments was thus also confirmed.Keywords:
Hairless
Formazan
Epidermis (zoology)
Hairless
Cite
Citations (42)
Formazan
Hydroxysteroid Dehydrogenases
Cite
Citations (0)
The Notch signaling pathway is fundamental to the regulation of many cell fate decisions in eumetazoans. Not surprisingly, members of this pathway are highly conserved even between vertebrates and invertebrates. There is one notable exception, Hairless, which acts as a general Notch antagonist in Drosophila. Hairless silences Notch target genes by assembling a repressor complex together with Suppressor of Hairless [Su(H)] and the co-repressors Groucho (Gro) and C-terminal binding protein (CtBP). Now with the availability of genomic databases, presumptive Hairless homologues are predicted, however only in insect species. To further our understanding of Hairless structure and function, we have cloned the Hairless gene from Apis mellifera (A.m.H) and characterized its functional conservation in Drosophila.The Apis Hairless protein is only one third of the size of the Drosophila orthologue. Interestingly, the defined Suppressor of Hairless binding domain is interrupted by a nonconserved spacer sequence and the N-terminal motif is sufficient for binding. In contrast to Apis Hairless, the Drosophila orthologue contains a large acidic domain and we provide experimental evidence that this acidic domain is necessary to silence Hairless activity in vivo. Despite the dramatic size differences, Apis Hairless binds to the Drosophila Hairless interactors Su(H), Gro, CtBP and Pros26.4. Hence, Apis Hairless assembles a repressor complex with Drosophila components that may have a different topology. Nevertheless, Apis Hairless is sufficient to repress the Notch target gene vestigial in Drosophila. Moreover, it is able to rescue Hairless mutant phenotypes, providing in vivo evidence for its function as a bona fide Notch antagonist.This is the first interspecies-complementation analysis of the Hairless gene. Guided by evolutionary comparisons, we hope to eventually identify all the relevant structural domains and cofactors of Hairless, thereby opening an avenue for further insights into the repressor-complexes that down-regulate Notch signaling also in other, higher eukaryotes.
Hairless
Cite
Citations (23)
Formazan
Tetrazolium chloride
Cite
Citations (63)
Formazan
Tetrazolium chloride
Phenazine
Cite
Citations (4)
Electronegative groups attached to either the N-2 phenyl or the N-3 phenyl rings are important in determining the readiness of enzymatic transfer of electrons to tetrazolium salts. The magnitude of the effects exerted by nitro, chloro, or cyano moieties are not identical when different dehydrogenase systems are compared. Furthermore, differences noted between several tetrazolium salts in any one dehydrogenase system are not necessarily reproduced when biochemical and histochemical preparations are compared. Although the reasons for these differences are not immediately apparent, preliminary observations with the succinoxidase system suggest that some clarification may follow closer inspection of site of transfer to tetrazolium salts in the chain of electron transport.
Formazan
Tetrazolium chloride
Cite
Citations (19)
Aim:To research the hairless gene mutation of Yuyi hairless mice.Methods:Partial hairless gene of Yuyi hairless mice and Kunming mice were cloned,sequenced,and compared with Mus musculus DNA.Results:The DNA fragment of Yuyi hairless mice contained 1 824 bp,that of Kunming mice contained 1 816 bp.There were 27 differences,including insertion,deletion,and point mutation.One nonsense mutation in exon 12 resulted in the introduction of a premature termination codon UGA.Conclusion:Hairless character is probably associated with the hairless gene mutation of Yuyi hairless mice.
Hairless
Nonsense mutation
Nonsense
Cite
Citations (1)
A cytochemical method for staining glucose-6-phosphate dehydrogenase (G6PD) activity in individual erythrocytes as reported previously has been optimized further by the incorporation of a number of technical improvements. Analysis of the enzyme content in erythrocytes of normal individuals as well as patients suffering from G6PD deficiency in the homozygous and heterozygous forms allows these three categories to be easily distinguished. Considerable formazan production occurs in most erythrocytes of a healthy person and only a small percentage of the cells appeared to be negative. Two cell populations of almost equal size could be discerned in heterozygotes for G6PD deficiency, one completely negative, the other with a variable amount of formazan per cell. Homozygous deficiency leads to a population of negative cells with a few positive ones after staining. It is concluded that a reliable method has been found for analysis of G6PD deficiency in erythrocytes at the single cell level.
Formazan
Heterozygote advantage
Glucosephosphate Dehydrogenase Deficiency
Red Cell
Cite
Citations (44)
Aim:To breed the new congenic strains of hairless mice, and study the expression of hairless gene in different hereditary backgrounds. Methods:Hairless gene was transferred into 615,C 57 BL/6,BALB/c, and DBA/2 inbred strains by cross intercross, respectively. Results:The 4th generation breeding had been accomplished. The mice of all 1st and 3rd hybrid generations all had hair and the 4 kinds of 615,C 57 BL/6,BALB/c, DBA/2 hairless mice had been bred successfully by intercrossing in the 2nd and 4th generations, whose regularity of hair losing was the same as YuYi hairless mice. Conclusion:The hairless gene can be expressed in different hereditary backgrounds.
Hairless
Congenic
Cite
Citations (0)
Formazan
Clonogenic assay
Colorimetry
MTT assay
Microtiter plate
Cite
Citations (5)