Gene map for the Cyanophora paradoxa cyanelle genome.

The genes for the following proteins were localized by hybridization analysis on the cyanelle genome of Cyanophora paradoxa: the alpha and beta subunits of phycocyanin (cpcA and cpcB); the alpha and beta subunits of allophycocyanin (apcA and apcB); the large and small subunits of ribulose-1,5-bisphosphate carboxylase (rbcL and rbcS); the two putative chlorophyll alpha-binding apoproteins of the photosystem I-P700 complex (psaA and psaB); four apoproteins believed to be components of the photosystem II core complex (psbA, psbB, psbC, and psbD); the two apoprotein subunits of cytochrome b-559 which is also found in the core complex of photosystem II (psbE and psbF); three subunits of the ATP synthase complex (atpA and atpBE); and the cytochrome f apoprotein (petA). Eighty-five percent of the genome was cloned as BamHI, BglII, or PstI fragments. These cloned fragments were used to construct a physical map of the cyanelle genome and to localize more precisely some of the genes listed above. The genes for phycocyanin and allophycocyanin were not clustered and were separated by about 25 kilobases. Although the rbcL gene was adjacent to the atpBE genes and the psbC and psbD genes were adjacent, the arrangement of other genes encoding various polypeptide subunits of protein complexes involved in photosynthetic functions was dissimilar to that observed for known chloroplast genomes. These results are consistent with the independent development of this cyanelle from a cyanobacterial endosymbiont.     

Alcaligenes eutrophus CH34 is a facultative chemolithotroph with plasmid-bound resistance to heavy metals.

Alcaligenes eutrophus strain CH34, which was isolated as a bacterium resistant to cobalt, zinc, and cadmium ions, shares with A. eutrophus strain H16 the ability to grow lithoautotrophically on molecular hydrogen, to form a cytoplasmic NAD-reducing and a membrane-bound hydrogenase, and most metabolic attributes; however, it does not grow on fructose. Strain CH34 contains two plasmids, pMOL28 (163 kilobases) specifying nickel, mercury, and cobalt resistance and pMOL30 (238 kilobases) specifying zinc, cadmium, mercury, and cobalt resistance. The plasmids are self-transmissible in homologous matings, but at low frequencies. The transfer frequency was strongly increased with IncP1 plasmids RP4 and pUZ8 as helper plasmids. The phenotypes of the wild type, cured strains, and transconjugants are characterized by the following MICs (Micromolar) in strains with the indicated phenotypes: Nic+, 2.5; Nic-, 0.6; Cob+A, 5.0; Cob+B, 20.0; Cob-, less than 0.07; Zin+, 12.0; Zin-, 0.6; Cad+, 2.5; and Cad-, 0.6. Plasmid-free cells of strain CH34 are still able to grow lithoautotrophically and to form both hydrogenases, indicating that the hydrogenase genes are located on the chromosome, in contrast to the Hox structural genes of strain H16, which are located on the megaplasmid pHG1 (450 kilobases).     

Mechanism of glucagon inhibition of liver acetyl-CoA carboxylase. Interrelationship of the effects of phosphorylation, polymer-protomer transition, and citrate on enzyme activity

The short-term regulation of rat liver acetyl-CoA carboxylase by glucagon has been studied in hepatocytes from rats that had been fasted and refed a fat-free diet. Glucagon inhibition of the activity of this enzyme can be accounted for by a direct correlation between phosphorylation, polymer-protomer ratio, and activity. Glucagon rapidly inactivates acetyl-CoA carboxylase with an accompanying 4-fold increase in the phosphorylation of the enzyme and 3-fold increase in the protomer-polymer ratio of enzyme protein. Citrate, an allosteric activator of acetyl-CoA carboxylase required for enzyme activity, has no effect on these phenomena, indicating a mechanism that is independent of citrate concentration within the cell. The observation of these effects of glucagon on acetyl-CoA carboxylase activity is absolutely dependent upon the minimization of proteolytic degradation of the enzyme after cell lysis. Therefore, for the first time, an interrelationship has been demonstrated between phosphorylation, protomer-polymer ratio, and citrate for the inactivation of acetyl-CoA carboxylase by glucagon.     

Biogenic amine degradation by homogenates of the bulb mite,Rhizoglyphus echinopus (Fumouze and Robin) (Acari: Astigmata: Acaridae)

Whole homogenates of bulb mites rapidly metabolized 2-phenylethylamine (PEA) but were appreciably less active against tryptamine, 5-hydroxytryptamine, and dopamine; no degradation of octopamine was detected. The rate of PEA degradation by bulb mites was dependent upon both substrate and homogenate concentrations. PEA degradation was inhibited by pargyline (pI₅₀, 6.7), tranylcypromine (pI_{50 6.2}), and harmaline (pI_{50 4.1}), but not by 5-chloro-2,4-dimethoxyformanilide. These results suggested that PEA metabolism by bulb mite homogenates was catalyzed mainly by Type B monoamine oxidase.Contribution from the Missouri Agricultural Experiment Station, Columbia, MO. Journal Series No. 9777     

Regeneration of the arterial wall in microporous,compliant, biodegradable vascular grafts after implantation into the rat abdominal aorta

Summary The ultrastructure of a new type of vascular graft, prepared from a mixture of polyurethane (95 weight %) and poly-L-lactic acid (5 weight %), was examined six weeks after implantation into the abdominal aorta of rats. These microporous, compliant, biodegradable, vascular grafts function as temporary scaffolds for the regeneration of the arterial wall.Smooth muscle cells, covering the grafts, regenerated a neo-media underneath an almost completely regenerated endothelial layer (neo-intima). These smooth muscle cells varied in morphology from normal smooth muscle cells to myofibroblasts. They were surrounded by elastic laminae and collagen fibers.Macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries were present in the disintegrating graft lattices. The epithelioid cells and multinucleated giant cells engulfed polymer particles of the disintegrating grafts.The regeneration of the endothelial and smooth muscle cells is similar to the natural response of arterial tissue upon injury. The presence of macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries in the graft lattices resembles the natural response of tissue against foreign body implants. Both of these responses result in the formation of a neo-artery that possesses sufficient strength, compliance and thromboresistance to function as a small caliber arterial substitute.Supported by Grant nr. 82.042 from the Dutch Heart Foundation     

Analysis of the sheep MHC using HLA class I,II, and C4 cDNA probes

Four cDNA probes for the human major histocompatibility complex (MHC) were used to investigate the sheep MHC, in conjunction with serological typing for ovine lymphocyte antigen (OLA). Lymphocytes from a family (two parents and five offspring) of Romanov sheep were subjected to genomic DNA digestion by the restriction endonuclease Eco RI, followed by gel electrophoresis. A single Southern blot representing all seven individuals was then consecutively hybridized with the class I, alpha-DC, beta-DR, and C4 probes, which were originally designed to identify HLA class I, class II (DC and DR), and C4 products, respectively. Using each of the three class I/class II probes, several bands showing DNA polymorphism were detected. The segregation of these bands in the five offspring exactly paralleled the OLA haplotype segregation established by serological typing. A further eight individuals carrying haplotypes which were phenotypically identical to those in the above-mentioned family showed bands in the corresponding positions when tested with the same three probes. Using the C4 probe, no polymorphism was detected in these fifteen individuals.Abbreviations used in this paper MHC major histocompatibility complex - OLA ovine lymphocyte antigen - kbp kilobase pair(s) - MLR mixed lymphocyte reaction - RFLP restriction fragment length polymorphism     

Racial and other characteristics of human T cell leukemia/lymphoma (HTLV-I) and AIDS (HTLV-III) in Trinidad.

Adult T cell leukaemia/lymphoma was first recognised as a clinical entity in southwest Japan. Subsequently the Caribbean has been found to be another area where the disease is endemic, and sporadic cases have been identified in different parts of the world. The human T cell leukaemia/lymphoma virus (HTLV-I) is causally related to adult T cell leukaemia/lymphoma. A subgroup of HTLV, designated HTLV-III, has recently been isolated from many patients with the acquired immunodeficiency syndrome (AIDS) and preAIDS, and there is now evidence that this variant is the primary cause of AIDS. This is the first report from Trinidad to describe 12 cases of adult T cell leukaemia/lymphoma and 14 of AIDS. All were in patients of African descent. No cases were seen in subjects of East Indian descent, who, like those of African descent, comprise as much as 40% of the population. West Indians of African descent may have increased susceptibility to infection with both HTLV-I and HTLV-III.     

International scientific meetings: relation between structure and function.

Increasing pressure is being placed on the scientific community to evaluate research activities. Scientific meetings consume a small but important fraction of the research budget. Audit of a well established series of scientific meetings showed that they met their immediate objectives in that they were international and multidisciplinary and provided a forum in which all participants actively contributed to discussion. The meetings had a positive outcome for the participants, leading in many cases to the subsequent exchange of research material (60% of participants) and to the establishment of collaborative research projects (31%). The impact of the meetings on the scientific community at large was assessed by citation analysis, which showed that the proceedings were cited early, often, and over a substantial period.