Antigenic determinants distinctive of Methanospirillum hungatei and Methanogenium cariaci identified by monoclonal antibodies

Monoclonal antibodies were prepared against two species of Methanomicrobiaceae. Antibody 1A is specific for Methanospirillum hungatei strain JF1 and the determinant it recognizes is expressed on the surface of JF1 cells, where it is exposed and accessible to antibody. The determinant is found in a polypeptide (MW<12,000) in the sheath that covers the bacterial cell; it is not present in Methanospirillum hungatei strain GP1; and it is not expressed on the surface of whole cells of the other 24 methanogenic bacteria tested. It is therefore a marker of strain JF1, consequently, antibody 1A is potentially useful for tracking JF1 and fragments thereof in a variety of samples. Antibody 7A is specific for Methanogenium cariaci JR1c. It did not react with any other methanogen tested, not even with Mg. marisnigri or Ms. hungatei JF1, although these cross-react with Mg. cariaci if tested with polyclonal antisera. Therefore antibody 7A recognizes specifically a marker of Mg. cariaci JR1c.Abbreviations SIA slide immunoenzymatic assay - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis     

Regulation and structure of an Escherichia coli gene coding for an outer membrane protein involved in export of K88ab fimbrial subunits.

The nucleotide sequence of the faeD gene of Escherichia coli and the amino acid sequence of its product is presented. The faeD product is an outer membrane protein required for transport of K88ab fimbrial subunits across the outer membrane. The protein is synthesized as a precursor containing a signal peptide, and the tentative mature protein comprises 777 amino acid residues. The distribution of amino acids in the faeD protein is similar to that of other outer membrane proteins; showing a fairly even distribution of charged residues and the absence of extensive hydrophobic stretches. Secondary structure predictions revealed a region of 250 amino acid residues which might be embedded in the outer membrane. The 5'-end of faeD is located within a region showing dyad symmetry. This region serves to couple translation of faeD to the translation of the gene preceding it (faeC). The 3'-end of faeD shows an overlap of 5 bases with the next gene (faeE).     

Secondary structure as primary determinant of the efficiency of ribosomal binding sites in Escherichia coli.

Using a previously described vector (pKL203) we fused several heterologous ribosomal binding sites (RBSs) to the lacZ gene of E. coli and then studied the variation in expression of the fusions. The RBSs originated from bacteriophage Q beta and MS2 genes and the E. coli genes for elongation factor EF-Tu A and B and ribosomal protein L11 (rplK). The synthesis of the lacZ fusion proteins was measured by an immuno precipitation method and found to vary at least 100-fold. Lac-specific mRNA synthesis follows the variation in protein production. It appears that there is a correlation between the efficiency of an RBS to function in the expression of the fused gene and the lack of secondary structure, involving the Shine and Dalgarno nucleotides (SDnts) and/or the initiation codon. This efficiency is context dependent. The sequence of the SD nts and the length and sequence of the spacer region up to the initiation codon alone are not able to explain our results. Deletion mutations, created in the phage Q beta replicase RBS, reveal a complex pattern of control of expression, probably involving the use of a "false" initiation site.     

Maternal 3:1 disjunction in a tranlocation 9/17

Summary An isochromosome of 15(q12) was found in a mentally retarded patient with behaviour disorders which included hyperactivity, short attention span, aggression, and autistic behaviour. There were only minor physical anomalies; he did not have the Prader-Willi syndrome.     

Immune reactivity in cattle with ocular squamous cell carcinoma after intralesional BCG immunotherapy

Summary Lymphocyte stimulation with Con A and specific immune reactivity to BCG (antibody formation to BCG and DTH reaction to PPD) were determined in BCG-treated, surgically treated and untreated cows with ocular squamous cell carcinoma. In tumor-bearing cows the Con A-induced proliferation of lymphocytes was reduced when compared to healthy controls. This suppression consisted of a reduced blastogenic response to Con A of lymphocytes from tumor-bearing cows, and the presence of a factor in the sera of these animals, as these sera suppressed the blastogenic response of lymphocytes from healthy cows. BCG had only a minor influence on the suppressive activity. Antibodies to BCG were demonstrated in 50% of the BCG-treated animals. The formation of antibodies was not influenced by intradermal injection of PPD of Mycobacterium bovis. Absorption of a BCG antibody containing serum with BOSCC tumor extracts did not reveal the existence of cross reacting antigens between BCG and BOSCC. Pretherapeutic and posttherapeutic Con A reactivity could not be correlated with clinical response. Of the 30 BCG treated cows 29 developed a positive DTH reaction to PPD. Correlation between clinical response and immune reactivity was seen only with regard to the DTH reaction to PPD: this reaction remained positive for a longer period after treatment in animals with a favorable clinical outcome than in nonresponding animals.Animals were maintained under the guidelines laid down by the Faculty of Veterinary Medicine, State University, Utrecht, The NetherlandsGrant recipient of the Koningin Wilhelmina Fonds (Netherlands Cancer Foundation) Abbreviations used: BCG, Bacillus Calmette-Guerin; BOSCC, bovine ocular squamous cell carcinoma PBL peripheral blood leukocytes; PPD, purified protein derivative of Mycobacteria; DTH, delayed type hypersensitivity Con A, concanavalin A; PHA, phytohemagglutinin; PWM, pokeweed mitogen     

Spectral sensitivity of photoreceptors in insect compound eyes: Comparison of species and methods

Summary Three different methods were used to determine the spectral sensitivity of retinula cells in the compound eyes of three species of hymenopteran insects (Apis mellifera, Melipona quadrifasciata, Osmia rufa). The conventional flash method gives the least reliable results. Sensitivity is extremely sensitive to small fluctuations of the resting potential and long lasting changes induced by preceding test flashes. The ramp method, which speeds up a spectral scan to about 1 min and keeps effective illumination constant at every flash, determines S() much more reliably. The best results are obtained with the spectral scan method, which provides the experimenter with aS() function of high spectral resolution within 20 s. Using this method we demonstrate that the high observed variability inS() of individual receptors is the result of the inadequacy of the flash method, which was the only method used in earlier studies.Double microelectrode experiments and variations of the stimulus conditions reveal that field potentials and return flow of electric current produced by activated neighboring cells have no effect in the bee eye. We conclude that the model of Shaw (1975, 1981) of current flow in the locust and fly eye does not apply to the bee eye. Very rare recordings (about 1%) of UV receptors with hyperpolarizing responses to long wavelength light are interpreted as having a synaptic inhibitory connection to green receptors.The improvement of spectral measurements of single receptors allows us for the first time to model the spectral input to a color-coding network with great precision.     

Spontaneous binding ofYersinia enterocolitica to murine leukocytes

Twelve strains ofYersinia enterocolitica were examined for their ability to bind spontaneously to murine leukocytes. Each of eight HeLa cell invasive strains exhibited nonselective binding to peritoneal leukocytes, lymph node leukocytes, and thymocytes, whereas four noninvasive strains lacked binding properties. Like the HeLa cell invasion, the binding ofY. enterocolitica to leukocytes was much less efficient for bacteria grown at 37°C than for bacteria grown at 22°C. The binding properties were not influenced by the virulence plasmid that codes for Vwa⁺ phenotype. This leukocyte binding test is proposed as a simple assay for invasive properties ofY. enterocolitica.     

Stability of neuronal and glial marker enzymes in post-mortem rat brain

The enzymatic activities in post-mortem rat brain kept at 4°C and at 25°C were determined for a number of enzymes localized in specific cell types in the central nervous system. Choline acetyltransferase (CAT), glycerol-3-phosphate dehydrogenase (GPDH), glutamine synthetase (GS), lactate dehydrogenase (LDH) and 2,3-cyclic nucleotide phosphohydrolase (CNPase) were found to be very stable at both 4°C and 25°C with only slight, if any, losses of activity being seen even at periods as long as 72 hr. Glutamic acid decarboxylase (GAD) activity was less stable than that of the other enzymes. In brains kept at 4°C GAD activity was stable out to 24 hr after which it began to decline rapidly to 65% of control at 72 hr. In brains kept at 25°C, GAD activity was stable for 6–8 hr and then began to steadily decline to 58% of control at 24 hr and 29% of control at 72 hr. Assuming that these enzymes have similar stabilities in post-mortem human brain, the effect of post-mortem delay in processing tissues may be of lesser significance than other factors with regard to the measured enzyme activities in human brain samples.