Mouse immunoglobulin A: nucleotide sequence of the structural gene for the alpha heavy chain derived from cloned cDNAs

The cDNAs complementary to mouse immunoglobulin alpha heavy chain mRNAs have been cloned into the PstI site of the plasmid vector pBR322. Recombinant plasmids have been identified by hybrid-arrested translation and purification of alpha heavy chain mRNA on DNA-DBM filters. The nucleotide sequence of the inserts encodes the constant and 3' untranslated regions of the alpha heavy chain mRNA. The CH3 domains of human and mouse alpha chains are highly homologous, including a 36 amino acid fragment not reported in the protein sequence (Robinson and Appella, 1980). As in the case of the mu secreted heavy chain, the alpha heavy chain contains a carboxy terminal piece of 20 amino acids.     

Clone banks of cDNA from the parasite Schistosoma mansoni: isolation of clones containing a potentially immunodiagnostic antigen gene

We have constructed a small vector specifically for blunt-end cloning of fragments of DNA. Both the PvuII site and the EcoRI site allow the detection of recombinants using a simple and inexpensive colour screen. We have used this vector to construct cDNA clone banks from polyadenylated messenger RNA [poly(A)+mRNA] from several life cycle stages of the human parasite Schistosoma mansoni and have identified clones encoding an immunodiagnostic antigen gene by a combination of Southern blotting and mRNA hybrid-selection and in vitro translation. Antibodies against this antigen are only present in patients infected with S. mansoni.     

Variation in mouse major urinary protein (MUP) genes and the MUP gene products within and between inbred lines

The mouse major urinary proteins (MUPs) and the unprocessed in vitro translation products of MUP mRNA were each resolved by isoelectric focusing (IEF). The urinary MUPs showed about 15 distinct components, and the unprocessed MUPs about 20. In each case wide variation was observed in the relative intensities of individual bands. A comparison of three inbred lines (C57BL, BALB/c and JU) showed inter-line variation in the patterns both of the urinary MUPs and of the unprocessed MUPs. A series of experiments was carried out with a cloned MUP cDNA probe. All three inbred lines contain the same number (about 20) of MUP genes per haploid genome. In Southern blot analysis of genomic DNA the MUP genes displayed complex patterns which we interpret as showing variation on a common basic MUP gene sequence. For each combination of restriction enzymes tested, one size of fragment carried more than half of the total label, and this fragment was always the same in the three inbred lines. Inter-line differences were observed in the patterns of some of the less reactive fragments. MUP mRNA consists of at least two distinct species with sizes of 1 and 1.2 kb, which reacted with the probe in a label ratio of about 0.5 to 1. In the three inbred lines this ratio was essentially the same.     

Cloning and expression of genes for lysozyme and a 20-kDal protein of colitis bacteriophage

BamHI fragments of colitis phage DNA were cloned in pBR322 DNA, and the recombinant clones carrying the lysozyme gene were identified by lysozyme activity. The inserted DNA was 1.2 kb long and when expressed in minicells it produced lysozyme and a 20-kDal protein. Colitis-phage-specific mRNAs which hybridized to the insert were 0.5 kb and 0.7 kb long and were translated into lysozyme and a 20-kDal protein, respectively, in a cell-free system derived from rice embryos. They were transcribed as monocistronic mRNAs using the internal promoters present on the inserted DNA.