Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell differentiation during spermatogenesis in the rat has been analyzed in terms of the formation of specific "marker" enzymes. Hyaluronidase and other acrosomal enzymes are formed in spermatids according to a highly predictable time schedule which may be termed a "molecular biological clock". The acrosomal enzymes beta-galactosidase and N-acetyl-beta-glucosaminidase exist as isoenzyme forms distinct from enzymes with similar substrate specificities in the lysosomes of precursor cells. Differentiation of spermatids thus involves the loss of gene expression for lysosomal enzymes and the activation of genes for acrosomal isoenzymes. Spermatogenesis is characterized by the sequential loss of expression of many genes, as evidenced by the loss of beta-glucuronidase in the differentiation of spermatogonia to spermatocytes, and the loss of uridine diphosphatase activity in the differentiation of spermatocytes to spermatids. The apparent absence of ornithine decarboxylase activity from spermatids suggests a dependence of these cells upon Sertoli cells for the provision of putrescine and/or spermidine. Such biochemical cooperativity among germinal cells may be necessary as the genes of spermatids are repressed and late spermatids become metabolically inactive. Spermatogenesis is also characterized by changes in the cellular content and rates of synthesis and phosphorylation of specific acidic chromatin proteins. It is hypothesized that these proteins may participate in the activation or repression of genes during spermatogenesis.
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PMID:Gene activation during spermatogenesis. 112 12

We developed and evaluated an in vivo athymic nude mouse model for tumor growth, angiogenesis, metastasis, and antineoplastic drug development. Melanoma cell lines expressing beta-galactosidase encoded by the Escherichia coli lac Z gene have been created by infecting an immortal murine melanocyte cell line with a recombinant retrovirus expressing the v-Ha-ras oncogene and lac Z to generate the MRB (melanoma, ras, beta-galactosidase) cell lines. The amelanotic, phorbol ester-independent, transformed melanoma cell lines developed tumors rapidly when injected subcutaneously into nude mice, as well as experimental lung metastases when injected i.v. into the tail vein. beta-galactosidase-expressing subcutaneous tumors and lung metastases stained blue with X-gal. The melanomas produced in nude mice have been characterized by using various histochemical and immunohistochemical staining methods to detect melanoma- and endothelial-cell-specific markers to determine the extent of neovascularization in MRB nude mouse tumors. Optimal staining of endothelial cells involved in tumor angiogenesis was observed by using ADPase activity and antiangiotensin-converting enzyme antibody staining. Attempts at indirect quantification of metastatic tumor cell number within the lung by either beta-galactosidase enzymatic activity or ELISA immunoreactivity were unsuccessful. However, the MRB cell lines should be useful in screening for and studying the mechanisms of action of antineoplastic, antimetastatic, and angiostatic drugs in vivo in athymic nude mice.
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PMID:Evaluation of a nude mouse tumor model using beta-galactosidase-expressing melanoma cells. 768 92