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Biomedical subjects

L J Wangh

Publications and source records attributed to L J Wangh.

29 records · Page 2Linked to original sources
PubMed1983

Efficient recovery of functionally intact mRNA from agarose gels via transfer to an ion-exchange membrane.

A simple method is described for the efficient recovery of intact mRNA from high resolution agarose gels. Fractionation of RNA is accomplished by gel electrophoresis under denaturing conditions using methylmercuric hydroxide. The RNA in the gel is then transferred electrophoretically to a diethylaminoethyl (DEAE)-membrane. After reversing the methylmercuric modification of the RNA, the membrane is sliced into narrow sections and the RNA is eluted at 65 degrees with a high ionic strength buffer containing 6M guanidine hydrochloride. RNA isolated by this procedure is suitable for subsequent enzymatic reactions, including in vitro translation and reverse transcription. The major advantages offered by this procedure are: 1) The membrane-bound RNA is a replica of the high resolution fractionation pattern achieved in the gel. 2) The immobilization and concentration of RNA and the removal of gel matrix contaminants are all accomplished in one step. 3) Small quantities of RNA are efficiently recovered and are suitable for subsequent biochemical manipulations. The method is of general utility for any biological system. We have applied its use to the fractionation, recovery, and analysis of mRNA from Xenopus liver and have identified cDNA clones complementary to albumin mRNA.

Animals↗
PubMed1983

Xenopus fibrinogen. Characterization of subunits and hormonal regulation of biosynthesis.

In this paper we describe the purification and characterization of Xenopus plasma fibrinogen and the hormonal factors which regulate synthesis and secretion of fibrinogen in liver parenchymal cells in primary culture. As in other vertebrate species, Xenopus fibrinogen is composed of three nonidentical polypeptide chains, A alpha, B beta, and gamma. In contrast to mammalian fibrinogens, the B beta chain of Xenopus fibrinogen has a higher apparent molecular weight than the A alpha chain. The gamma chain has the lowest molecular weight in the frog protein, as in that of other species. The relatively large size of the frog B beta chain results from the unusually large size of the NH2-terminal B fibrinopeptide, which is released by thrombin cleavage of fibrinogen. Hormonal regulation of fibrinogen biosynthesis was examined using a primary cell culture system. Purified Xenopus liver parenchymal cells, maintained for several weeks in a defined culture medium, gradually decrease the synthesis and secretion of fibrinogen. Sustained production of this protein is dependent upon the addition of a glucocorticoid, dexamethasone, to the culture medium. Fibrinogen production is suppressed if an estrogen, estradiol-17 beta, is added to the culture medium together with dexamethasone and triiodothyronine. The Xenopus system provides new insight into the structure of fibrinogen, the evolution of this protein, and the hormonal factors which regulate its synthesis.

Animals↗
PubMed1975

Synthesis of vitellogenin in cultures of male and female frog liver regulated by estradiol treatment in vitro.

Using the frog Xenopus laevis, we show that the addition of physiological concentrations of estradiol to cultures of liver from untreated males rapidly induces the synthesis of large amounts of vitellogenin. Sustained synthesis of vitellogenin requires continuous exposure to estradiol. A nonestrogenic steroid, dexamethasone, does not induce vitellogenin synthesis but does induce increased synthesis of a different protein in liver cultures.

Animals↗