Pinocytic uptake of divinyl ether-maleic anhydride (pyran copolymer) and its failure to stimulate pinocytosis

The effect of DIVEMA (pyran copolymer) and three DIVEMA derivatives on the pinocytic uptake of ¹²⁵I-labelled PVP and colloidal ¹⁹⁸Au by the rat visceral yolk sac and by rat peritoneal macrophages was studied in vitro. Contrary to expectations from some earlier data, there was no enhancement of pinocytosis and in some cases inhibition was seen. [¹⁴C]DIVEMA and ¹²⁵I-labelled DIVEMA were accumulated rapidly by rat peritoneal macrophages, the results indicating that this is by an adsorptive pinocytic mechanism.     

Sensitive detection of RNA using strand-specific M13 probes

We have extended the method of Hu and Messing (Gene 17 (1982) 271-277) to prepare highly radioactive M13 probes suitable for use in RNA-DNA hybridization experiments. Single strands of M13 DNA carrying cloned sequences are rendered partially double-stranded by primed synthesis using a synthetic oligonucleotide primer complementary to a region 5' to the cloning site. The newly synthesized radioactive complementary strand is then covalently cross-linked to the M13 phage DNA by UV irradiation in the presence of 4,5,8-trimethylpsoralen (trioxsalen). Since the cross-linked probe is stable to heat denaturation, and the region of cloned sequence is kept single-stranded, these complexes may be used as strand-specific hybridization probes to detect RNA sequences under conditions which would denature DNA-DNA duplexes.