Site-specific integration of an F'' lac pro factor in the region of the replication origin (oriC) of E. coli

Summary An episome, F 128, which carries approximately 8x10⁴ base pairs of chromosomal DNA homologous to the lac pro region of the E. coli chromosome, has been found to integrate into the oriC region of the chromosome in a site specific reaction. While the event appears to be recA-dependent, no homology between the episome and this region of the chromosome was detected. The Hfr strains formed result from the integration of intact F 128 molecules. The structure of the Hfr strains generated has been determined and their transfer properties analyzed.     

Immunogenicity of outer membrane derivatives ofHaemophilus influenzae type b

We prepared outer membrane derivatives ofHaemophilus influenzae type b to determine whether the residual capsular and noncapsular surface components are immunogenic and protective. These fragments consist primarily of six major proteins and lipopolysaccharide. By transmission electron microscopy, they appeared as small, membrane-like fragments or larger, cellshaped double-track ghosts. Rabbits immunized with ghosts responded with increases in serum anticapsular antibody and bactericidal activity. Antisera absorbed with capsular antigen to remove anticapsular antibody remained bactericidal and passively protected infant rats. These data suggest that antibodies to noncapsular surface antigens are protective, and that outer membrane derivatives retain some of the constituents responsible for stimulating immunity.     

Control mechanisms regulating gene expression during normal differentiation of myeloid leukemic cells: Differentiation defective mutants blocked in mRNA production and mRNA translation

Regulation of gene expression during myeloid cell differentiation has been analyzed using clones of myeloid leukemic cells that differ in their competence to be induced to differentiate by the normal macrophage- and granulocyte-inducing protein MGI. Changes in the relative rate of synthesis for specific proteins were compared to changes in the relative amounts of corresponding translatable poly(A)⁺ mRNAs, assayed in the reticulocyte cell-free translation system, using two-dimensional gel electrophoresis. Of the 217 proteins which changed during MGI-induced differentiation of normally differentiating MGI⁺D⁺ leukemic cells, 136 could be identified as products of cell-free translation. Eighty-four percent of the 70 decreases in synthesis, most of which occurred early during differentiation, were not accompanied by a parallel decrease in the amount of translatable mRNA, but were accompanied by a parallel shift of the corresponding mRNAs from the polysomal to the monosomal and free mRNA fractions. These results indicate that most of the early decreases in the synthesis of proteins were translationally regulated. In contrast, 81% of the proteins which increased in synthesis and 71% of the proteins that were induced de novo were regulated at the level of mRNA production. Experiments with differentiation defective mutants have shown that they were blocked both at the level of mRNA production and mRNA translation. The data with these mutants have suggested that there were different subsets of translationally regulated proteins which were separately regulated. The translational blocks for several proteins in these mutant clones have also made it possible to identify additional translational sites of regulation for protein changes that were controlled at the level of mRNA production during normal differentiation. The results indicate that translational regulation may predominantly have a different function in cell differentiation than regulation by mRNA production, and that differentiation-defective mutants can be blocked at either level.     

Trois nouvelles especes du genre mixtacandona (ostracoda,cyprididae, candoninae)

The authors describe Mixtacandona elegans n. sp.,M. pietrosanii n. sp., M. tabacarui n. sp. and present new data on the systematics and biogeography of the following Mixtacandona groups: ljovuschkini,hvarensis and riongessa. Mixtacandona elegans n. sp. belongs to the group ljovuschkini. The carapace is very elongated and has markedly assymetrical valves. The species has been found in a porous aquifer in southeastern Bulgaria. M. pietrosanii n. sp. belongs to the group hvarensis. The 3rd antennular segment and the 2nd endopodial segment of the cleaning leg have each two setae. The species lives in porous aquifers in the Danube plain in Roumania. M. tabacarui n. sp. (gr. riongessa) has a triangular left valve with a pointed dorsal protuberance. The species has been found in wells fed by karstic water in southern dobrodgea (Roumania), on the Black Sea coast.     

A unique course in anthropology

The course in forensic anthropology presented at Florida State University is designed to train criminal investigators in the application of physical anthropological and archaeological techniques to the investigation of buried bodies. Modification of archaeological field techniques by experimentation using artificial graves allows the recovery of fragile and easy to overlook evidence and ensures the recovery of all possible material for analysis by the physical anthropologist. An introduction to physical anthropology enables the criminal investigator to effectively communicate his needs and understand the type of information required for adequate identification of remains by a physical anthropologist.     

Permeability properties of the membrane of vesicular stomatitis virions

Observations of the light-scattering properties of several enveloped viruses indicate that virions (vesicular stomatitis, SV5 and influenza), in common with other membrane systems, are osmotically active, responding to NaCl gradients by swelling in hypo-osmolar solutions and shrinking in hyperosmolar solutions. The permeability barrier responsible for this osmotic response in vesicular stomatitis virions was modified both by protease treatment to remove the viral glycoprotein and by treatment with the polyene antibiotic filipin, an agent known to interact with cholesterol in liposomes and membranes. Filipin altered the kinetic and equilibrium permeability behavior of virions but the extent of leakage of osmotic shocking agent was less than that in lecithin/cholesterol and lecithin/ergosterol liposomes and in ergosterol-containing ciliary membranes. Negative-staining electron microscopy revealed that filipin treatment caused structural changes in the viral membrane. Intact virions exhibited appreciably larger responses to osmotic change than did protease-treated virus particles. Thus, the osmotic barrier in intact vesicular stomatitis virions may not be exclusively lipid in nature.