Transfer RNA genes of Euglena gracilis chloroplast DNA

Summary Transfer RNA genes have been mapped to at least nine different loci on the physical map of the Euglena gracilis chloroplast genome. One of these loci in the ribosomal RNA operons is present three times per genome. The DNA sequences of six of the nine different loci, containing 21 different tRNA genes, have been determined. Genes corresponding to the amino acids Ala, Arg, Asn, Cys, Gln, Gly (2), Glu, His, Ile, Leu (2), Met (2), Phe, Ser, Thr, Trp, Tyr, Val, and one unassigned species have been identified. All genes except one are found in clusters of 2–6 genes. None of the known genes contains introns, nor codes for the 3-CCA terminus. In addition to these genes, two pseudo tRNA genes are present in the rDNA leader region.     

The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

Cervical extensibility increased from Day 16 to term in the pregnant rat. Following ovariectomy on Day 16 of pregnancy the cervix became as inextensible by Day 20 as that of non-pregnant animals. Fetal growth was maintained in rats ovariectomized on Day 16 if given oestradiol benzoate plus progesterone but cervical extensibility only increased to a small extent. Relaxin given to these animals further increased cervical extensibility, suggesting a role for this hormone.     

N-Acetylglutamic acid: an extracellular nod signal of Rhizobium trifolii ANU843 that induces root hair branching and nodule-like primordia in white clover roots

An extracellular metabolite purified from Rhizobium trifolii ANU843 was established as N-acetylglutamic acid (GluNAc) by 1H NMR and Fourier transform IR spectroscopy, gas chromatography/mass spectrometry of its methylated product, and organic synthesis. TLC analyses indicated that extracellular accumulation of GluNAc by R. trifolii ANU843 grown in defined BIII culture medium was dependent on induction of its bacterial nodulation (nod) genes and the positive regulatory gene nodD on its symbiotic plasmid. 1H NMR analyses showed less GluNAc in fractionated culture supernatants of nodL and nodM mutant derivatives of R. trifolii ANU843. GluNAc induced three morphological responses on axenic roots of white clover seedlings: (i) root hair branching; (ii) tip swelling followed by resumed elongation of root hairs; and (iii) a slight increase in foci of cortical cell divisions, which developed into nodule-like primordia. These biological activities of extracellular GluNAc from R. trifolii ANU843 were confirmed with authentic standards of GluNAc. These results indicate that extracellular accumulation of N-acetylglutamic acid is linked to flavone-dependent metabolism involving nodD, nodL, and nodM in R. trifolii ANU843. This constitutes the first report on the structure of a nod-dependent extracellular signal from R. trifolii that can affect root hair and nodule development in white clover and whose biological activity on this host has been confirmed with authentic standards.     

Rhizobium meliloti chromosomal loci required for suppression of exopolysaccharide mutations by lipopolysaccharide.

Mutants of alfalfa symbiont Rhizobium meliloti SU47 that fail to make extracellular polysaccharide (exo mutants) induce the formation of nodules that are devoid of bacteria and consequently do not fix nitrogen. This Fix- phenotype can be suppressed by an R. meliloti Rm41 gene that affects lipopolysaccharide structure. Here we describe mutations preventing suppression that map at two new chromosomal loci, lpsY and lpsX, present in both strains. Two other lps mutations isolated previously from SU47 also prevented suppression.     

Cloning and sequencing of a human pancreatic tumor mucin cDNA

A monospecific polyclonal antiserum against deglycosylated human pancreatic tumor mucin was used to select human pancreatic mucin cDNA clones from a lambda gt11 cDNA expression library developed from a human pancreatic tumor cell line. The full-length 4.4-kilobase mucin cDNA sequence included a 72-base pair 5'-untranslated region and a 307-base pair 3'-untranslated region. The predicted amino acid sequence for this cDNA revealed a protein of 122,071 daltons containing 1,255 amino acid residues of which greater than 60% were serine, threonine, proline, alanine, and glycine. Approximately two-thirds of the protein sequence consisted of identical 20-amino acid tandem repeats which were flanked by degenerate tandem repeats and nontandem repeat sequences on both the amino-terminal and carboxyl-terminal ends. The amino acid sequence also contained five putative N-linked glycosylation sites, a putative signal sequence and transmembrane domain, and numerous serine and threonine residues (potential O-linked glycosylation sites) outside and within the tandem repeat position. The cDNA and deduced amino acid sequence of the pancreatic mucin sequence was over 99% homologous with a mucin cDNA sequence derived from breast tumor mucin, even though the native forms of these molecules are quite distinct in size and degree of glycosylation.     

Liver transplantation in a patient with cholangiocarcinoma and ulcerative colitis.

A 39 year-old patient with cholangiocarcinoma and pre-existing ulcerative colitis was successfully treated by orthotopic liver transplantation. He was given low doses of prednisone and azathioprine and survived for more than 9 months, dying with tumour metastases, thrombosis of the inferior vena cava and an intra-abdominal abscess. At autopsy the homograft showed little evidence of rejection. Preoperatively the patient had septicemia. Removal of his liver was difficult. The discrepancy between donor and recipient in size of blood vessels and the presence of two hepatic arteries in the donor caused problems during the vascular anastomoses. During the operation cardiac arrest occurred. Postoperatively there were several medical and surgical problems, including intraperitoneal and gastrointestinal hemorrhage, paralysis of the right dome of the diaphragm, sinus bradycardia, massive diuresis, peroneal nerve palsy, and one major and three minor episodes of rejection, which were reversed by giving pulse doses of methylprednisolone intravenously.     

Composition and Role of Extracellular Polymers in Methanogenic Granules

Methanobacterium formicicum and Methanosarcina mazeii are two prevalent species isolated from an anaerobic granular consortium grown on a fatty acid mixture. The extracellular polysaccharides (EPS) were extracted from Methanobacterium formicicum and Methanosarcina mazeii and from the methanogenic granules to examine their role in granular development. The EPS made up approximately 20 to 14% of the extracellular polymer extracted from the granules, Methanobacterium formicicum, and Methanosarcina mazeii. The EPS produced by Methanobacterium formicicum was composed mainly of rhamnose, mannose, galactose, glucose, and amino sugars, while that produced by Methanosarcina mazeii contained ribose, galactose, glucose, and glucosamine. The same sugars were also present in the EPS produced by the granules. These results indicate that the two methanogens, especially Methanobacterium formicicum, contributed significantly to the production of the extracellular polymer of the anaerobic granules. Growth temperature, substrates (formate and H(inf2)-CO(inf2)), and the key nutrients (nitrogen and phosphate concentrations) affected polymer production by Methanobacterium formicicum.     

Physiological function of alcohol dehydrogenases and long-chain (C(30)) fatty acids in alcohol tolerance of Thermoanaerobacter ethanolicus

A mutant strain (39E H8) of Thermoanaerobacter ethanolicus that displayed high (8% [vol/vol]) ethanol tolerance for growth was developed and characterized in comparison to the wild-type strain (39E), which lacks alcohol tolerance (<1.5% [vol/vol]). The mutant strain, unlike the wild type, lacked primary alcohol dehydrogenase and was able to increase the percentage of transmembrane fatty acids (i.e., long-chain C(30) fatty acids) in response to increasing levels of ethanol. The data support the hypothesis that primary alcohol dehydrogenase functions primarily in ethanol consumption, whereas secondary alcohol dehydrogenase functions in ethanol production. These results suggest that improved thermophilic ethanol fermentations at high alcohol levels can be developed by altering both cell membrane composition (e.g., increasing transmembrane fatty acids) and the metabolic machinery (e.g., altering primary alcohol dehydrogenase and lactate dehydrogenase activities).     

A nuclear factor that binds purine-rich, single-stranded oligonucleotides derived from S1-sensitive elements upstream of the CFTR gene and the MUC1 gene.

We have identified two regions of non-random purine/pyrimidine strand asymmetry that were nearly identical in sequence in the 5' flanking (promoter) regions of the human cystic fibrosis transmembrane conductance regulator (CFTR) gene and the human MUC1 gene. These regions contain perfect mirror repeat elements, a sequence motif previously found to be associated with the formation of H-DNA conformations. In this report we demonstrate that a single-stranded non-B DNA conformation exists at low pH in supercoiled plasmids containing the similar mirror repeat elements, and that S1 nuclease digestion maps the single-stranded region to the position of the mirror repeats. In addition, we identify a nuclear protein of approximately 27 kD that binds to single-stranded oligonucleotides corresponding to the purine-rich strand of this region, but not to the pyrimidine-rich strands or to double-stranded oligonucleotides with corresponding purine/pyrimidine strand asymmetry.