Enrichment of special Novikoff hepatoma and regenerating liver mRNA by hybridization to cDNA-cellulose

Characterization of lymphoid cells by two-dimensional mini gel electrophoresis of proteins

Cytosol proteins from normal lymphocytes, leukemic lymphocytes, and different cultured lymphoid cell lines were separated by two-dimensional mini gel electrophoresis. By staining with Coomassie blue, specific protein patterns were obtained. Very similar gel maps were produced by the cytosol proteins of chronic lymphocytic leukemia cells, hairy cells, and of in vitro grown B cells. Protein 36/6.2 (molecular weight/isoelectric point), consistently present in these cells, could not be demonstrated in normal lymphocytes. For the comparison of control Raji cells--an Epstein-Barr-Virus (EBV)-DNA carrying Burkitt's lymphoma cell line--with Raji cells induced for early antigen (EA) production, 35S-methionine-labelled total cell lysates were analyzed. In the induced cells, an additional protein (100/5.5) was found; this might be one of the immunologically defined EBV-associated antigens. These results demonstrate that two-dimensional mini gel electrophoresis can be useful for the characterization of leukemic cells in addition to the morphological, cytochemical, and surface marker analyses.

The isolation of ecdysterone inducible genes by hybridization subtraction chromatography

We have developed a procedure for selectively enriching a mRNA population for inducible sequences. Other than the induced mRNA species, the population of mRNA in control cells is approximately the same as the mRNA population in induced cells. Cytoplasmic mRNA from control cells is bound to oligo (dT)-cellulose and used as a template for reverse transcriptase, the oligo (dT) serving as a primer. After removing the template mRNAs, the cDNA-cellulose column is used to hybridize a population of mRNAs from induced cells. The non-hybridized poly A+ RNAs are greatly enriched in the inducible sequences. We have used this technique of hybridization subtraction chromatography to select a mRNA population enriched for the mRNAs inducible by ecdysterone in Schneider's Line 2 Drosophila cells. This population of RNAs was used to screen a recombinant library. Preliminary results indicate that approximately 10% of the RNA in the probe population represents ecdysterone inducible sequences. Methods are described for optimizing the cDNA synthesis reaction (we obtain greater than or equal to 30% efficiency) and hybridizing RNA to the cDNA-cellulose resin. This method can be used to select induced mRNAs regardless of the way in which the induction is brought about.

Comparison of polysomal and nuclear poly(A)-containing RNA populations from normal rat liver and Novikoff hepatoma

Polysomal and nuclear poly(A)-containing RNA of normal rat liver and Novikoff hepatoma cells have been compared by cDNA.RNA hybridization kinetics. Homologous hybridization reactions revealed at total kinetic complexity of about 1.6 X 10(10) and 1.38 X 10(10) daltons for liver and Novikoff mRNA respectively. The high abundance component present in liver cannot be detected in Novikoff. It was found from heterologous reactions that about 30% by weight of mRNA sequences are specific to liver. Determination of the nuclear poly(A)-containing RNA complexities revealed that about 5.5% and 4% of the haploid genome is expressed in the liver and Novikoff respectively. In a heterologous reaction, up to 30% of the liver cDNA failed to form hybrids with Novikoff nuclear RNA. Cross hybridizations have further revealed abundance shifts in both nuclear and polysomal RNA populations. Some sequences abundant in liver are less abundant in Novikoff and some rare liver sequences are relatively abundant in Novikoff.

Rapid changes in the synthesis of specific ovarian granulosa cell proteins induced by human choriogonadotropin

Total ovarian granulosa cell proteins were labeled in vitro with [35S]methionine and analyzed by two-dimensional polyacrylamide gel electrophoresis. Of the 100-150 distinct proteins resolved by this method, 1-2% demonstrated an observable change in their synthesis during the early phases of luteinization after hormone administration. Two specific proteins first appeared as early as 30 min after treatment with human choriogonadotropin, while four additional new proteins became apparent at 3 hr. These changes in the synthesis of specific proteins occurred far in advance of the morphological changes associated with luteinization, which occur 24-72 hr later, and thus may play an important role in this process of hormonally induced cell differentiation in the rat ovary.