Cloning and restriction map of the E. coli apt gene

The apt gene coding for Escherichia coli adenine phosphoribosyl transferase has been cloned in pBR322. The restriction map of a 1.6-kb fragment containing the apt gene is presented.     

Isolation of the origin of replication of the IncW-group plasmid pSa

The origin of replication of the IncW plasmid pSa has been cloned and the function of this origin in Escherichia coli examined. A 1.9-kb region of DNA is required for efficient autonomous replication, and a 0.47-kb fragment within this region can initiate replication only in the presence of an autonomously replicating derivative of pSa. An Mr 35,000 protein (repA) is encoded adjacent to the origin and is required for efficient initiation of replication. The derivatives examined provide information suggesting a direct role of partition factors in plasmid replication and incompatibility.     

A common sequence in the inverted terminal repetitions of human and avian adenoviruses

The termini of the avian chick embryo lethal orphan (CELO) virus DNA have been sequenced. The results revealed a 63-bp-long inverted terminal repetition (ITR) which shared the sequence ATAATA with all adenovirus termini, thus far analyzed. The CELO virus ITR differed from those of the mammalian adenoviruses in two major aspects: (i) it is not a perfect duplication; (ii) it begins with a 5'-guanylic acid residue instead of the cytidylic acid normally observed in adenoviruses.     

Molecular cloning of the gene for dihydrofolate reductase from Lactobacillus casei

The Lactobacillus casei gene for dihydrofolate reductase has been cloned in Escherichia coli using the multicopy vector pBR322. A restriction map of the cloned DNA has been prepared. The cloned DNA directs the synthesis of L. casei dihydrofolate reductase in E. coli and confers trimethoprim and methotrexate resistance.     

Molecular cloning and characterization of double-stranded cDNA coding for bovine chymosin

A full-length cDNA copy of the mRNA encoding calf chymosin (also known as rennin), a proteolytic enzyme with commercial importance in the manufacture of cheese, has been cloned in an f1 bacteriophage vector. The nucleotide sequence of the cDNA was determined, and translation of that sequence into amino acids predicts that the zymogen prochymosin is actually synthesized in vivo as preprochymosin with a 16 amino acid signal peptide. In vitro translation of total poly(A)-enriched RNA from the calf fourth stomach (abomasum) and immunoprecipitation with antichymosin antiserum revealed that a form of chymosin (probably preprochymosin judging from the M_r-value) is the major in vitro translation product of RNA from that tissue. Gel-transfer hybridization of restriction endonuclease-cleaved bovine chromosomal DNA with labeled cDNA probes indicated that the two known forms of chymosin, A and B, must be products of two different alleles of a single chymosin gene.     

Metrical analysis of the basicranium of extant hominoids and Australopithecus

The size and shape of the basicranium (seen in norma basilaris) in Homo, Gorilla, Pan, Pongo, and Australopithecus have been studied by recording the relative disposition of midline and bilateral bony landmarks. Fifteen linear measurements and two angles were used to relate the landmarks. The relatively longer and narrower cranial base of Gorilla, Pan, and Pongo is clearly contrasted with the wider, shorter cranial base in Homo sapiens. When the same observations were made on two “robust” and two “gracile” australopithecine crania, marked differences were found between the taxa. In the two “robust” specimens, the foramen magnum is located relatively further forward, and the axis of the petrous temporal bone is aligned more nearly with the coronal plane than in the two “gracile” crania. The implications of this apparent parallelism in basicranial morphology between Homo sapiens and the “robust” australopithecines are discussed.     

Mg2+ restores membrane potential in rat liver mitochondria deenergized by Ca2+ and phosphate movements

Cellular ornithine biosynthesis could be expected to play a significant role in putrescine formation and hence in growth. Two enzymes are involved in ornithine biosynthesis: arginase and transamidinase. These enzyme activities were studied in two human melanoma cell lines differing in their K_m of diamine oxidase for putrescine and in their tumorigenicity in nude mice. Arginase activity accounts for the majority of ornithine formed in the highly tumorigenic cell line, while the majority of ornithine is derived from transamidinase action in the poorly tumorigenic cell line, with concomitant formation of methyl guanidine, a potent inhibitor of diamine oxidase.     

Construction and characterization of a bacterial clone containing the hemagglutinin gene of the WSN strain (HON1) of influenza virus

A synthetic dodecadeoxynucleotide primer has been used to prepare a double-stranded DNA form of the hemagglutinin (HA) gene of a human influenza virus (WSN strain, HON1). This DNA has been inserted in plasmid pBR322 and cloned in bacterial cells. The insert contains nearly the complete hemagglutinin gene. A restriction map of this insert has been determined and structurally important areas of the HA gene have been sequenced. Amino acid sequences of several regions of the HA protein were deduced from the DNA sequences and compared to the known amino acid sequences of other influenza A viruses. WSN HA shows extensive homology to all influenza A viruses in a few regions, namely the first 17 amino acids of the N-terminus of HA1 (N-terminal polypeptide of HA) and the first 24 amino acids of the N-terminus of HA2 (C-terminal polypeptide of HA). The sequence diverges extensively from other influenza A viruses in most other areas. The sequence of WSN virus HA is similar to that of other HON1 viruses with the exception of the C-terminus of the HA1 peptide. The change in this area may contribute to some of the unique properties of WSN virus among the HON1 viruses. In addition, WSN HA contains a 17-amino-acid precursor before the N-terminus of HA1 and a single amino acid, arginine, connecting HA1 and HA2.     

Location of ribosome-binding sites in the nin5 region of bacteriophage lambda

Seven ribosome-binding sites on DNA have been located within the region defined by the nin5 deletion as well as several ribosome-binding sites on each side of the nin5 region. These were mapped by electron microscopy relative to the end points of the nin5 deletion and two Tn903 transposons, one inserted into gene Rz and another inserted near gene Q. These ribosomes binding sites within the nin5 region may correspond to polypeptide initiation sites for up to seven new dispensible lambda genes.     

Isolation of recombinant plasmids and phage carrying the lexA gene of Escherichia coli K-12

The lexA gene of Escherichia coli K-12 was cloned from the plasmid pLC44-14 into pBR322. Plasmids carrying lexA+ were selected by their ability to complement a recessive tsl mutation, which is believed to be a mutation in lexA. The smallest lexA+ recombinant plasmid, pJL21, contained an EcoRI-PstI fragment 2.9 kilobases (kb) in length; two larger plasmids also contained this fragment, and genetic material to one or both sides of the EcoRI-PstI fragment. Plasmids homologous to pJL21, but carrying a dominant mutation, lexA3, or one of three recessive amber mutations in lexA, termed spr, were also isolated. To clone the EcoRI-PstI fragment onto a lambda vector, the PstI end was first converted to an EcoRI end by attachment of a 100-base pair PstI-EcoRI fragment isolated from the plasmid ColE1; the resultant EcoRI fragment was then cloned into the lambda vector lambda gt4. A restriction map of pLC44-14 was obtained for nine restriction enzymes. The orientation of this map was determined relative to the E. coli genetic map by complementation of the gene ubiA+ and by comparison with restriction enzyme digests of another plasmid, pLC11-9, which carries dnaB, a gene closely linked to lexA, but does not carry lexA.