Modifiers of bx1 alter the distribution of Ubx proteins in haltere imaginal discs of Drosophila.

The bithorax (bx) mutations in the Ultrabithorax (Ubx) gene of Drosophila melanogaster cause homeotic transformations of anterior third thoracic structures (T3a) toward anterior second thoracic structures (T2a) in the adult fly. A corresponding loss of Ubx protein expression in T3a of bx imaginal discs has been observed (White and Wilcox, 1985). We describe two genetic loci which modify the bx-induced transformation. A locus which we map very close to the pink peach (pp) gene suppresses the bx1 phenotype. In contrast, mutations in the suppressor of sable (su(s)) gene enhance the bx1 phenotype. A correlation was observed between patterns of Ubx protein expression and the phenotypic transformations observed.     

Quantitative immunoassay of total cellular GAP junction protein connexin32 during liver regeneration using antibodies specific to the COOH-terminus.

A radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) were used to determine relative concentrations of liver connexin32 (CX32) in rats. The RIA and ELISA utilize synthetic peptides corresponding to regions of the carboxyl-terminus and antibodies raised in rabbits against these peptides. Assuming that affinities of antisera are similar for peptide and native CX32, total cellular CX32 was found to exceed the amount of gap junction protein at the cell surface calculated from morphometric analyses by 1.5-2.0 fold. This finding raises the possibility that some of the protein is present in cytoplasmic compartments or as occult precursors in the plasma membrane. Studies of CX32 content in regenerating rat liver support this conclusion and show a time course of loss and recovery of CX32 that agrees with those reported in studies using other techniques.     

Use of dual wavelength spectrophotometry and continuous enzymatic depletion of oxygen for determination of the oxygen binding constants of hemoglobin

A small stopped-flow cuvette was built into a computer-controlled Cary 210 spectrophotometer. The enzymatic depletion of oxygen in solutions of hemoglobin and myoglobin was initiated by flowing the hemeproteins with the enzyme against a solution of the hemeproteins containing the appropriate substrate. The deoxygenation was homogeneous throughout the solution. Oxygen activity was calculated at each instant of time from the fractional saturation of Mb, determined from observations at the Hb/HbO2 isosbestic wavelength. Fractional saturation of Hb was determined from absorbances at the Mb/MbO2 isosbestic wavelength. The spectrophotometer cycled between these two wavelengths during the deoxygenation. The deoxygenation of HbO2 was largely complete in 20-25 min, whereas the deoxygenation of MbO2 was allowed to proceed for about 1 h. This procedure eliminates equilibration of Hb solutions with a gas phase and replaces oxygen electrode readings with spectrophotometric sensing by Mb, providing essentially instantaneous determinations of oxygen activity and hence 250-500 or more independent data points per run. The Mb and Hb data vectors require several manipulations to correct for small relative displacements in time and for small non-isosbestic effects. Detailed consideration of the enzyme kinetics allowed oxygen activities to be determined in regions where Mb is a poor sensor. Studies of HbO2 deoxygenation as a function of wavelength show that the determination of the four Adair constants requires in addition the determination of three spectroscopic parameters. Values of the apparent Adair constants, determined without these spectroscopic parameters, depend strongly on the monitoring wavelength.     

Chlamydia trachomatis contains a protein similar to the Legionella pneumophila mip gene product

A 27kDa Chlamydia trachomatis L2 protein was characterized by the use of monoclonal antibodies and by two-dimensional gel electrophoresis. The protein was shown to be located in the membrane of reticulate bodies as well as elementary bodies. Its synthesis could be detected from 10 hours post-infection. Cloning and sequence analysis of the distal part of the gene revealed an open reading frame of 175 amino acids. Comparison of the deduced amino acid sequence with the NBRF data base revealed significant homology between the 27 kDa chlamydial membrane protein and the product of the macrophage infectivity potentiator (mip) gene of Legionella pneumophila.     

The phenology ofProcladius crassinervis (Zett),Procladius signatus (Zett) andProcladius choreus (Mg) (Diptera,Chironomidae) at Lake Hald,Denmark

In an investigation of the phenology of the chironomid species of Lake Hald, Denmark, a very late flight activity (September–November) of the univoltine speciesProcladius choreus (Mg.) was observed. Among observations of the phenological patterns of univoltine chironomids inhabiting lakes of the Baltic type in Denmark, the phenological pattern ofProcladius choreus stands alone (JÓNSSON, 1987; LARSEN, 1991). Further two species of the genusProcladius Skuse,viz. Procladius crassinervis (Zett) andProcladius signatus (Zett), were found in the investigation and the phenological pattern of the three congeneric species was clearly allochronic, withProcladius crassinervis flying in spring,Procladius signatus flying in summer andProcladius choreus flying in autumn.     

Resonance Raman investigation of a soluble cytochrome c552 from alkaliphilic Bacillus firmus RAB

The environment of the heme site of a low-potential soluble cytochrome (c552) from alkaliphilic Bacillus firmus RAB has been characterized with resonance Raman scattering and compared to that of horse heart cytochrome c. The Raman data indicate that vibrational bands sensitive to the axial ligation of the heme, as well as modes sensitive to the heme peripheral environment in cytochrome c552, are distinct from those of horse heart cytochrome c. The spectra of cytochrome c552 display resonance Raman modes indicative of a methionine as the sixth ligand in the oxidized form, while the reduced form appears to contain a nitrogenous-based sixth ligand. In addition, Q-band excitation reveals differences among vibrational modes in cytochrome c552 that are sensitive to the amino acid environment surrounding the heme.     

Kinetics and specificity of alginate lyases: Part I, A case study

Purified preparations of alginate lyase from Klebsiella aerogenes and Haliotis sp. were investigated for activity and degradation patterns with alginate and alginate fragments having different compositions and sequences. With fragments approaching homopolymers of guluronate and mannuronate, Michaelis-Menten kinetics were obeyed and kinetic parameters could be obtained. Degradation of alginates containing all four possible linkages in various proportions, followed by isolation of the fragments and identification of the end groups by n.m.r. spectroscopy, indicated that the enzyme preparations can attack more than one type of linkage. The results are discussed with reference to the concept of specificity for enzymes with copolymeric substrates having non-regular distributions of units.     

A quantitative and qualitative study of blood monocytes in patients with bronchogenic carcinoma

Summary Absolute circulating number and functions of blood monocytes (i.e., pinocytosis, phagocytosis, and chemotaxis) were studied in 25 patients with untreated bronchogenic carcinoma and in 28 control subjects. The absolute circulating monocyte count was increased in 20 (80%) of the patients. There was no difference in the pinocytic and phagocytic activity of patient and control monocytes. In contrast, patient monocytes showed depressed chemotactic responsiveness. This defect was more severe in small cell anaplastic carcinoma than in the other histologic types of bronchogenic carcinoma (P=0.001), and may explain the difference in macrophage infiltration seen in solid tumours of the lung. There was no correlation between chemotaxis and clinical stage. Depressed chemotaxis may be related to a plasma factor, since patient plasma inhibited the chemotaxis of control monocytes as well as the activity of chemotactic agents. The defective chemotaxis and the presence of plasma inhibitory activity may interfere with the ability of blood monocytes to accumulate as macrophages in tumour sites. Abbreviations used in this paper are: MCR, monocyte chemotactic response; SAC, small cell anaplastic bronchogenic carcinoma; OBC, non-small cell bronchogenic carcinoma MEM, Eagle's minimal essential medium; CFI, chemotactic factor inhibitor(s); HSA, human serum albumin     

Amino Acid Synthesis in Photosynthesizing Spinach Cells : EFFECTS OF AMMONIA ON POOL SIZES AND RATES OF LABELING FROM CO(2)

Isolated cells from leaves of Spinacia oleracea have been maintained in a state capable of high rates of photosynthetic CO₂ fixation for more than 60 hours. The incorporation of ¹⁴CO₂ under saturating CO₂ conditions into carbohydrates, carboxylic acids, and amino acids, and the effect of ammonia on this incorporation have been studied. Total incorporation, specific radioactivity, and pool size have been determined as a function of time for most of the protein amino acids and for γ-aminobutyric acid. The measurements of specific radio-activities and of the approaches to ¹⁴C “saturation” of some amino acids indicate the presence and relative sizes of metabolically active and passive pools of these amino acids.