Microbial growth on carbon monoxide

The utilization of carbon monoxide as energy and/or carbon source by different physiological groups of bacteria is described and compared. Utilitarian CO oxidation which is coupled to the generation of energy for growth is achieved by aerobic and anaerobic eu- and archaebacteria. They belong to the physiological groups of aerobic carboxidotrophic, facultatively anaerobic phototrophic, and anaerobic acetogenic, methanogenic or sulfate-reducing bacteria. The key enzyme in CO oxidation is CO dehydrogenase which is a molybdo iron-sulfur flavoprotein in aerobic CO-oxidizing bacteria and a nickel-containing iron-sulfur protein in anaerobic ones. In carboxidotrophic and phototrophic bacteria, the CO-born CO₂ is fixed by ribulose bisphosphate carboxylase in the reductive pentose phosphate cycle. In acetogenic, methanogenic, and probably in sulfate-reducing bacteria, CODH/acetyl-CoA synthase directly incorporates CO into acetyl-CoA.In plasmid-harbouring carboxidotrophic bacteria, CO dehydrogenase as well as enzymes involved in CO₂ fixation or hydrogen utilization are plasmid-encoded. Structural genes encoding CO dehydrogenase were cloned from carboxidotrophic, acetogenic and methanogenic bacteria. Although they are clustered in each case, they are genetically distinct.Soil is a most important biological sink for CO in nature. While the physiological microbial groups capable of CO oxidation are well known, the type and nature of the microorganisms actually representing this sink are still enigmatic. We also tried to summarize the little information available on the nutritional and physicochemical requirements determining the sink strength. Because CO is highly toxic to respiring organisms even in low concentrations, the function of microbial activities in the global CO cycle is critical.     

Lotus japonicus, an autogamous, diploid legume species for classical and molecular genetics

In the Leguminosae plant family, few of the individual plant species have been used for plant molecular biology research. Among the species investigated no obvious representative ‘model’ legume has emerged. Here a member of the tribe Loteae, Lotus japonicus (Regel) Larsen is proposed as a candidate. L. japonicus is a diploid, autogamous species, with a good seed set, and a generation time of approximately 3 months. The haploid genome consists of six chromosomes and the genome size was estimated to be relatively small (0.5 pg per haploid complement). L. japonicus is susceptible to Agrobacterium tumefaciens and transgenic plants can be regenerated after hygromycin or kanamycin selection. Tissue culture conditions and procedures for transformation and regeneration are described. Stable transformation is demonstrated by segregation of the hygromycin selectable marker after selfing of transgenic plants or test crosses. The possibility of mapping polymorphic DNA markers inbred lines of L. japonicus is also discussed.     

Molecular cloning of the mouse 46-kDa mannose 6-phosphate receptor (MPR 46).

A cDNA clone for the mouse 46-kDa mannose 6-phosphate receptor (MPR 46) was isolated from an embryonic mouse cDNA library. Its single open reading frame codes for a protein of 278 residues. It shows an over-all amino-acid identity of 93% with the human receptor. Nine non-conservative amino-acid exchanges are found in the luminal domain, one non-conservative exchange of hydrophobic amino acids is in the transmembrane domain, while the cytoplasmic receptor tails are identical. All five potential N-glycosylation sites are conserved as well as amino acids that are important for ligand binding (Arg 137 and His 131) and disulfide pairing (Cys 32 and 78, Cys 132 and Cys 167, Cys 145 and Cys 179). The absolute identity in the cytoplasmic MPR 46 tail suggests the importance of this amino-acid sequence for the intracellular routing of the MPR 46.     

Expression of the core antigen gene of hepatitis B virus (HBV) in Acetobacter methanolicus using broad-host-range vectors

Summary Using the broad-host-range promoter probe vector pRS201 for cloning of phage Acm1 promoters, we established a convenient vector system for expression of heterologous genes in different Gram-negative bacteria. The usefulness of this system was demonstrated by expression of the HBV core gene in Acetobacter methanolicus. Plasmids carrying the HBV core gene downstream of different Acm1-phage promoters were transferred to A. methanolicus, a new potential host for recombinant DNA expression. Using enzyme immunoassay and immunoblot techniques, the amount and composition of core antigen produced in A. methanolicus were compared with that derived from Escherichia coli. The expression of immunoreactive core antigen in A. methanolicus exceeds by sevenfold that in E. coli using an expression system with tandemly arranged promoters. Morphological observations by electron microscopy show that the HBV core gene products isolated from both hosts are assembled into regular spherical particles with a diameter of about 28 nm that are comparable to original viral nucleocapsids. Offprint requests to: R. Schröder     

Changes in the distribution of intermediate filament proteins and collagen IV in fetal and adult human pancreas. I. Localization of cytokeratin polypeptides

The expression patterns of individual cytokeratin polypeptides in foetal and adult human pancreatic tissues were examined using monoclonal antibodies. We demonstrated that human pancreatic epithelia in early stages of development (14 weeks of gestation) contain cytokeratins 7, 8, 18 and 19, which are typical of simple epithelia, as well as cytokeratin 4 and 17, which are characteristic of stratified epithelia. In the pancreatic ducts, most of these cytokeratins appeared to be expressed together. Cytokeratins 1, 5, 10, 13, 16 and 20 were not detectable. In contrast, the pancreatic parenchyma was only positive for cytokeratins 8 and 18, except a transient expression of cytokeratins 7 and 19 in pancreatic islets and acinar cells during the foetal development. A focal cytokeratin 7 staining of single acinar cells was seen in newborn and in adult islets. In the stromal tissue, vascular smooth muscle cells were partly reactive with cytokeratin 8 and 18 specific antibodies. The results are discussed in the light of differentiation-dependent changes in the expression of individual cytokeratin polypeptides in developing epithelia.     

Thermogenic effect of adrenaline: interaction with insulin

The contribution of insulin (3.6 pmol.kg body mass-1.min-1) to adrenaline-induced (0.164 nmol.kg fat free mass-1.min-1) thermogenesis was studied in ten postabsorptive healthy volunteers using two sequential protocols. Variables considered were oxygen consumption as well as carbon dioxide production, heart rate, blood pressure, plasma concentrations of glucose, insulin, glycerol, free fatty acids, beta-HO-butyrate and lactate. Adrenaline increased plasma concentrations of glucose, glycerol, free fatty acids, and beta-HO-butyrate, and heart rate and metabolic rate during normo-insulinaemia [61.3 (SEM 6.6) pmol.l-1]. Similar effects were observed during hyperinsulinaemia [167.9 (SEM 18.7) pmol.l-1], but the effect of adrenaline on oxygen consumption was reduced. On average, metabolic rate increased by 12.9% during normo-insulinaemia and by 8.9% during hyperinsulinaemia. We concluded that relative hyperinsulinaemia resulted in decreased adrenaline-induced thermogenesis and therefore increased whole body anabolism.     

Specific eradication of micrometastases by transfer of tumour-immune T cells from major-histocompatibility-complex congenic mice

Summary DBA/2 (H-2^d) mice bearing a transplanted highly metastatic lymphoma (ESb) in a state of widely disseminated disease could be successfully treated by a combination of surgery (removal of the local tumour), irradiation (5 Gy) and adoptive immunotherapy. The immunotherapy was achieved by transfer of anti-ESb-immune spleen cells from B10.D2 mice, which express the same major histocompatibility complex (MHC) molecules as DBA/2. In contrast, anti-ESb-immune cells from MHC-disparate C57BL/6 mice did not confer protective immunity. The B10.D2 anti-ESb-immune T cells contain two types of cytolytic specificity as detected by limiting-dilution analysis: (1) clones with specificity for the ESb-tumour-associated transplantation antigen (TATA) (at low frequency), and (b) clones with specificity for minor DBA/2 histocompatibility (H) antigens (at high frequency). Immune B10.D2 cells raised against different tumour lines or against TATA^– ESb tumour variants did not confer the 100% protection seen with immune cells against ESb TATA⁺ cells. Finally we demonstrate that the allogeneic immune cells are more potent in terms of protective immunity than corresponding syngeneic immune cells. The data suggest that the strong graft-versus-leukemia effect with immune T cells from allogeneic MHC-identical but not from MHC-disparate mice was due to T cells with MHC-restricted specificity for an ESb-associated TATA. A graft-versus-host reactivity that developed much later and could not be prevented was most likely due to T cells sensitized against normal minor H antigens of the host. Our results are of potential relevance for allogeneic bone marrow transplantation and adoptive immunotherapy protocols.     

Genome analysis ofElymus angulatus andE. patagonicus (Poaceae) and their hybrids with N. and S. AmericanHordeum spp.

The results of genome analysis of five hybrids, viz.Elymus patagonicus ×Hordeum procerum, E. patagonicus ×H. tetraploidum, E. angulatus ×H. jubatum, E. angulatus ×H. lechleri, andE. angulatus ×H. parodii, are reported. The genomic constitution ofHordeum tetraploidum andH. jubatum is best given as H₁H₁H₂H₂, ofH. lechleri andH. parodii as H₁H₁H₂H₂H₄H₄, ofH. procerum as H₁H₁H₂H₂H₃H₃, and ofElymus patagonicus andE. angulatus as SSH₁H₁H₂H₂.     

Malignant ascites of serous papillary ovarian adenocarcinoma. An immunocytochemical study of the tumor cells

In 17 malignant peritoneal effusions due to papillary serous adenocarcinoma of the ovary, the reaction patterns of the tumor cells to monoclonal antibodies (MAbs) against surface antigens were studied and compared with the reaction patterns of mesothelial cells in the same effusions. The following surface markers were used with the adhesive slide method: epithelial membrane antigen (EMA), human epithelium-specific cell surface antigen (HEA-125), human endothelial antigen (BMA-120), carcinoembryonic antigen (CEA 3-13), an antibody against natural killer cells and cytotoxic cells (BMA-070), granulocyte antigen (Leu M1) and leukocyte antigen of class I (HLA-1). In all cases, from 30% to 95% of the tumor cells reacted with EMA and HEA-125. Tumor cells showed a positive staining with CEA 3-13 in only five cases. In all cases, from 75% to 95% of the tumor cells reacted positively with BMA-120. The reactivity of a few mesothelial cells with EMA and of all mesothelial cells with BMA-120 did not interfere with the identification of positive tumor cells since the reaction patterns were different. Interestingly, our study demonstrated that BMA-070, an MAb identifying natural killer cells and cytotoxic cells, is also a most useful tumor marker. The same was found to be true for Leu M1, an MAb originally thought to react only with granulocytes. The tumor cells showed a partial or total loss of the expression of HLA-1 reactivity. Since all cases were immunocytochemically positive for tumor cells while conventional cytology was positive in only 13 of the cases, the immunocytochemical analysis of malignant peritoneal effusions due to papillary serous adenocarcinoma of the ovary seems able to improve the cytologic diagnosis of the fluids.