Biomedical subjects
Publications and source records attributed to G Morgenegg.
Guinea pigs are gaining popularity as companion animals. However, their enormous reproduction rate often leads to problems. We describe a method with which male guinea pigs can be castrated at the age of two to three weeks, which is clearly before sexual maturity and sale in the pet shops.
A single-stranded DNA-binding protein of Mr 35,000 (35K protein) was isolated from calf cerebral cortex by affinity chromatography on immobilized double-stranded and single-stranded DNA. Its localization in the nuclear compartment was demonstrated by immunohistochemistry. Previous studies had uncovered a homologous nonhistone chromosomal protein in the nuclei of rat cerebral cortex neurons, cerebellar neurons, oligodendrocytes, and liver cells. The rat protein accumulated in the nuclear compartment of neurons in exact temporal coincidence with the arrest of cell division and the initiation of terminal differentiation. Therefore, in the present work, the 35K protein was tested for an activating role in RNA transcription. During the course of this study we became aware that the 35K protein was identical to a glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12). When authentic GAPDH from rabbit skeletal muscle was injected into Xenopus laevis oocytes, it greatly stimulated RNA polymerase II transcription, whereas the 35K protein from calf brain did not. This apparent discrepancy was partially resolved by the finding that rabbit muscle GAPDH could be fractionated into two components by affinity chromatography on single-stranded DNA cellulose. Only 5% of the applied protein was retained on the column and could be eluted with a shallow salt gradient identical to the one used for the isolation of the 35K protein. This single-stranded DNA-binding component of rabbit muscle GAPDH did not stimulate transcription. Apparently, the 35K protein from calf brain corresponded to this single-stranded DNA-binding subfraction, which explained its failure to activate transcription.(ABSTRACT TRUNCATED AT 250 WORDS)
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Recently, it has been shown that natural and synthetic deoxynucleotide polymers can adopt a left-handed helical structure (termed Z-DNA) in appropriate conditions (see, for example, refs 1 and 2 and the references therein). In contrast to the more familiar right-handed B-DNA, Z-DNA is strongly immunogenic, and polyclonal and monoclonal antibodies against Z-DNA have been elicited. By using such antibodies, immunoreactivity for Z-DNA has been detected in the polytene chromosomes of two dipteran species, in the macronucleus of a ciliated protozoon, and in certain plant nuclei (cited in ref. 11). In view of the possible importance of Z-DNA as a genomic regulatory signal, it would be highly desirable to know whether Z-DNA also occurs in mammals. We have therefore initiated an immunohistochemical study of various rat tissues by using three antisera specific for Z-DNA, and the peroxidase-antiperoxidase technique for visualization of tissue-bound antibodies. Here we demonstrate that the nuclei of many, but not all, types of rat cells exhibit Z-DNA immunoreactivity, suggesting that Z-DNA may exist naturally in mammalian chromatin.