Biosynthesis of bacterial glycogen: purification and characterization of ADPglucose pyrophosphorylase with modified regulatory properties from Escherichia coli B mutant CL1136-504

The l-thyroxine binding site in human serum thyroxine-binding globulin was investigated by affinity labeling with N-bromoacetyl-l-thyroxine (BrAcT₄). Competitive binding studies showed that, in the presence of 100 molar excess of BrAcT₄, binding of thyroxine to thyroxine-binding globulin was nearly totally abolished. The reaction of BrAcT₄ to form covalent binding was inhibited in the presence of thyroxine and the affinity-labeled thyroxinebinding globulin lost its ability to bind thyroxine. These results indicate BrAcT₄ and thyroxine competed for the same binding site. Affinity labeling with 2 mol of BrAcT₄/mol of thyroxine-binding globulin resulted in the covalent attachment of 0.7 mol of ligand. By amino acid analysis and high voltage paper electrophoresis, methionine was identified as the major residue labeled (75%). Lysine, tyrosine, and histidine were also found to be labeled to the extent of 8, 8, and 5%, respectively.     

The structure of 180° supernumerary limbs and a hypothesis of their formation

The results of a detailed analysis of 100 supernumerary limbs generated by 180° ipsilateral rotation (on the same limb stump) of regeneration blastemas is presented. The limbs were analyzed in terms of their position of origin, frequency, cartilage structure by Victoria blue staining, and muscle structure by serial sections. Single, double, or triple supernumeraries can be produced at no unique position of origin, although the posterodorsal quadrant was preferred. Four classes of supernumerary limbs were generated by such operations—normal; double dorsal or double ventral; part normal/part mirror imaged; part normal/part inverted in approximately equal frequencies. After amputation of these supernumeraries the same muscle patterns are faithfully regenerated. A hypothesis to explain the production of these abnormal limbs is proposed based on the observed phenomenon of fusion of supernumerary blastemata, but their regenerative behaviour presents problems for current models of pattern formation. Similar results have been obtained with developing limb buds and the relation between development and regeneration is discussed.     

In vitro growth of murine T cells. IV. Use of T-cell growth factor to clone lymphoid cells

Murine bone marrow cells can suppress the in vitro primary antibody response of normal spleen cells without apparent cytotoxicity. The bone marrow cells suppress the response to both T-dependent (SRBC) and T-independent (DNP-Ficoll) antigens. When bone marrow cells are fractionated on a sucrose density gradient, the suppressive activity is found in the residue rather than the lymphocyte fraction. The suppressive activity is either unaffected or enhanced by treatment with anti-T- and anti-B-cell serums. Pretreatment of mice with phenylhydrazine which reduces the number of pre-B cells did not reduce the suppressive activity of their bone marrow cells. Suppressive activity is abolished by irradiation of the marrow cells in vitro with 1000 R prior to assay. The activity is present in the marrow of thymus deficient (nude) mice, infant mice, and mice which have been made polycythemic by transfusion. Furthermore, the suppressor cell can phagocytize iron carbonyl particles, is slightly adherent to plastic and Sephadex G-10, and can bind to EA monolayers. We conclude that the suppressor cell is not a mature lymphocyte or granulocyte nor a member of the erythrocytic series, but is likely to be an immature cell possibly of the myeloid series. We speculate on the physiologic role of this cell.     

Salinity and germination of annual Melilotus from the Guadalquivir delta (SW Spain)

The germination response to NaCl treatments has been studied in Melilotus seed populations collected from saline and non-saline soils in the Guadalquivir delta. The rank orders for salt tolerance and seed weight were the same in the threeMelilotus species living in this area:Melilotus messanensis>M. segetalis>M. indica. Within the species, differences in germination response to salinity were found inM. indica (6 populations) andM. segetalis (8 populations). The relationship between salt tolerance during germination and salinity of maternal habitat is discussed.     

The ecology of a beech forest on Mt. Sanpoiwadake,Hakusan National Park,Japan I. Braun-Blanquet,TWINSPAN and DCA analysis

The Lindero membranaceae-Fagetum crenatae association on Mt. Sanpoiwadake, Hakusan National Park, Japan, has been classified using traditional Braun-Blanquet methods. The association was floristically sub-divided into six communities, all of which had been included as four subassociations by Hukusima (1982). The resulting table was compared with an analogous community table derived using computer-based TWINSPAN analysis. This dual approach was shown to provide a fully objective classification by method, the subjective element in the Braun-Blanquet method thus being substantiated TWINSPAN. Subsequent ordination of the data using DCA then provided a further degree of objective evaluation allowing any misclassified stand or species to be re-examined, and at the same time displaying the detailed inter-relationships between all species or stands.     

Interferon affects the formation of adhesion plaques in human monocyte cultures

When monocytes isolated from human blood adhere to glass substratum, actin- and vinculin-containing punctate plaques rapidly appear at the ventral surface of the cells. We show here that highly purified human leukocyte interferon (IFN) can inhibit formation of these adhesion plaques in a dose-dependent manner. Complete inhibition was obtained when 300 IU/ml IFN were added into the cell-seeding medium. Plaques already formed in the absence of IFN were only partially affected by subsequent addition of IFN into the culture medium. Prevention by IFN of the formation of the adhesion plaques was associated with loosened attachment of the cells to the substratum. Effect of IFN on cellular morphology was complex. At higher doses, IFN added to the cultures within 24 h of seeding almost completely inhibited the differentiation of monocytes to macrophages and most of the cells remained rounded. At lower doses, however, an enhancement of the bipolar spreading was seen and the end result was a culture with predominantly elongated fibroblastoid cells. The latter cells, unlike the fibroblastoid cells in untreated monocyte-macrophage cultures, were completely devoid of the actin plaques, while the reorganization of vimentin-type intermediate filaments took place in a normal manner. These results further support the view that the actin- and vinculin-containing plaques have a role in mediating firm adherence of human monocytes to growth substratum.