Facilitated diffusion of fructose via the phosphoenolpyruvate/glucose phosphotransferase system of Escherichia coli

From mutants of Escherichia coli unable to utilize fructose via the phosphoenolpyruvate/glycose phosphotransferase system (PTS), further mutants were selected that grow on fructose as the sole carbon source, albeit with relatively low affinity for that hexose (Km for growth ≈8 mM but with Vmax for generation time ≈1 h 10 min); the fructose thus taken into the cells is phosphorylated to fructose 6-phosphate by ATP and a cytosolic fructo(manno)kinase (Mak). The gene effecting the translocation of fructose was identified by Hfr-mediated conjugations and by phage-mediated transduction as specifying an isoform of the membrane-spanning enzyme IIGlc of the PTS, which we designate ptsG-F. Exconjugants that had acquired ptsG+ from Hfr strains used for mapping (designated ptsG-I) grew very poorly on fructose (Vmax ≈7 h 20 min), even though they were rich in Mak activity. A mutant of E. coli also rich in Mak but unable to grow on glucose by virtue of transposon-mediated inactivations both of ptsG and of the genes specifying enzyme IIMan (manXYZ) was restored to growth on glucose by plasmids containing either ptsG-F or ptsG-I, but only the former restored growth on fructose. Sequence analysis showed that the difference between these two forms of ptsG, which was reflected also by differences in the rates at which they translocated mannose and glucose analogs such as methyl α-glucoside and 2-deoxyglucose, resided in a substitution of G in ptsG-I by T in ptsG-F in the first position of codon 12, with consequent replacement of valine by phenylalanine in the deduced amino acid sequence.

Cnr interferes with dimerization of the replication protein α in phage-plasmid P4

DNA replication of phage-plasmid P4 in its host Escherichia coli depends on its replication protein α. In the plasmid state, P4 copy number is controlled by the regulator protein Cnr (copy number regulation). Mutations in α (αcr) that prevent regulation by Cnr cause P4 over-replication and cell death. Using the two-hybrid system in Saccharomyces cerevisiae and a system based on λ immunity in E.coli for in vivo detection of protein–protein interactions, we found that: (i) α protein interacts with Cnr, whereas αcr proteins do not; (ii) both α–α and αcr–αcr interactions occur and the interaction domain is located within the C-terminal of α; (iii) Cnr–Cnr interaction also occurs. Using an in vivo competition assay, we found that Cnr interferes with both α–α and αcr–αcr dimerization. Our data suggest that Cnr and α interact in at least two ways, which may have different functional roles in P4 replication control.

Participation of Mitochondrial Metabolism in Photorespiration1 : Reconstituted System of Peroxisomes and Mitochondria from Spinach Leaves

In this study the interplay of mitochondria and peroxisomes in photorespiration was simulated in a reconstituted system of isolated mitochondria and peroxisomes from spinach (Spinacia oleracea L.) leaves. The mitochondria oxidizing glycine produced serine, which was reduced in the peroxisomes to glycerate. The required reducing equivalents were provided by the mitochondria via the malate-oxaloacetate (OAA) shuttle, in which OAA was reduced in the mitochondrial matrix by NADH generated during glycine oxidation. The rate of peroxisomal glycerate formation, as compared with peroxisomal protein, resembled the corresponding rate required during leaf photosynthesis under ambient conditions. When the reconstituted system produced glycerate at this rate, the malate-to-OAA ratio was in equilibrium with a ratio of NADH/NAD of 8.8 × 10−3. This low ratio is in the same range as the ratio of NADH/NAD in the cytosol of mesophyll cells of intact illuminated spinach leaves, as we had estimated earlier. This result demonstrates that in the photorespiratory cycle a transfer of redox equivalents from the mitochondria to peroxisomes, as postulated from separate experiments with isolated mitochondria and peroxisomes, can indeed operate under conditions of the very low reductive state of the NADH/NAD system prevailing in the cytosol of mesophyll cells in a leaf during photosynthesis.

Geometric incompatibility in a fault system.

Interdependence between geometry of a fault system, its kinematics, and seismicity is investigated. Quantitative measure is introduced for inconsistency between a fixed configuration of faults and the slip rates on each fault. This measure, named geometric incompatibility (G), depicts summarily the instability near the fault junctions: their divergence or convergence ("unlocking" or "locking up") and accumulation of stress and deformations. Accordingly, the changes in G are connected with dynamics of seismicity. Apart from geometric incompatibility, we consider deviation K from well-known Saint Venant condition of kinematic compatibility. This deviation depicts summarily unaccounted stress and strain accumulation in the region and/or internal inconsistencies in a reconstruction of block- and fault system (its geometry and movements). The estimates of G and K provide a useful tool for bringing together the data on different types of movement in a fault system. An analog of Stokes formula is found that allows determination of the total values of G and K in a region from the data on its boundary. The phenomenon of geometric incompatibility implies that nucleation of strong earthquakes is to large extent controlled by processes near fault junctions. The junctions that have been locked up may act as transient asperities, and unlocked junctions may act as transient weakest links. Tentative estimates of K and G are made for each end of the Big Bend of the San Andreas fault system in Southern California. Recent strong earthquakes Landers (1992, M = 7.3) and Northridge (1994, M = 6.7) both reduced K but had opposite impact on G: Landers unlocked the area, whereas Northridge locked it up again.

The invariant system of coordinates of antibody molecules: prediction of the "standard" C alpha framework of VL and VH domains.

A new approach of comparing protein structures that does not involve the procedure of superposition is suggested. An invariant system of coordinates for immunoglobulin molecules that is based on the geometrical symmetry inherent to the variable domain light-chain (VL)-heavy-chain (VH) complex is described. The coordinates of the Calpha atoms in 22 immunoglobulin structures are calculated in the invariant system of coordinates. We found that 76 identical positions in this Calpha framework are symmetrical about the twofold axis. Comparison of the identical positions in these molecules allows us to select 96 positions in the light chains and 87 positions in the heavy chains whose Calpha atom coordinates are approximately the same. To check whether the average coordinates of Calpha atoms in these positions complies with the stereochemical requirements, we calculated Calpha-Calpha distances. Seventy-three positions of the light chains and 72 positions of the heavy chains satisfy the Calpha-Calpha distance criterion. The Calpha atoms in these positions are used for constructing the "standard" Calpha framework of VL and VH complexes. The average coordinates of Calpha atoms are presented.

The Ste locus, a component of the parasitic cry-Ste system of Drosophila melanogaster, encodes a protein that forms crystals in primary spermatocytes and mimics properties of the beta subunit of casein kinase 2.

Males of Drosophila melanogaster lacking the Y chromosome-linked crystal locus show multiple meiotic alterations including chromosome disorganization and prominent crystal formation in primary spermatocytes. These alterations are due to the derepression of the X chromosome-linked Stellate sequences. To understand how the derepression of the Stellate elements gives rise to these abnormalities, we have expressed the protein encoded by the Stellate sequences in bacteria and produced an antibody against the fusion protein. Immunostaining of crystal- testes has clearly shown that the Stellate protein is a major component of the crystals. Moreover, in vitro experiments have shown that this protein can interact with the catalytic alpha subunit of casein kinase 2 enzyme, altering its activity.

Enhanced secretion of glycocholic acid in a specially adapted cell line is associated with overexpression of apparently novel ATP-binding cassette proteins.

Secretion of anionic endo- and xenobiotics is essential for the survival of animal and plant cells; however, the underlying molecular mechanisms remain uncertain. To better understand one such model system--i.e., secretion of bile acids by the liver--we utilized a strategy analogous to that employed to identify the multidrug resistance (mdr) genes. We synthesized the methyl ester of glycocholic acid (GCE), which readily enters cells, where it is hydrolyzed to yield glycocholic acid, a naturally occurring bile acid. The rat hepatoma-derived HTC cell line gradually acquired resistance to GCE concentrations 20-fold higher than those which inhibited growth of naive cells, yet intracellular accumulation of radiolabel in resistant cells exposed to [14C]GCE averaged approximately 25% of that in nonresistant cells. As compared with nonresistant cells, resistant cells also exhibited (i) cross-resistance to colchicine, a known mdr substrate, but not to other noxious substances transported by hepatocytes; (ii) increased abundance on Northern blot of mRNA species up to 7-10 kb recognized by a probe for highly conserved nucleotide-binding domain (NBD) sequences of ATP-binding cassette (ABC) proteins; (iii) increased abundance, as measured by RNase protection assay, of mRNA fragments homologous to a NBD cRNA probe; and (iv) dramatic overexpression, as measured by Western blotting and immunofluorescence, of a group of 150- to 200-kDa plasma membrane proteins recognized by a monoclonal antibody against a region flanking the highly conserved NBD of mdr/P-glycoproteins. Finally, Xenopus laevis oocytes injected with mRNA from resistant cells and incubated with [14C]GCE secreted radiolabel more rapidly than did control oocytes. Enhanced secretion of glycocholic acid in this cell line is associated with overexpression of ABC/mdr-related proteins, some of which are apparently novel and are likely to include a bile acid transport protein.

The Role of Education and Government in Shaping Muslim Women's Rights: Three Contemporary Case Studies

The rise in Muslim terrorist activities has encouraged the West to reevaluate its understanding of Islam, prompting concern for Muslim women's rights. In search of education-based solutions, this project explores three case studies of Muslims living under different government types: a secular state with a primarily Muslim population (Turkey); a secular state with a significant Muslim minority population (France); and a Muslim state with a powerful religious influence (Afghanistan). The type of government plays a significant role in Muslim women's rights, and solutions must be based on individual aspects of each unique place where Muslims live today. The results show that education is a universal solution when accepted at all levels: governmental, communal, and the individual.

Some problems in the translation of converted denominal verbs from nouns denoting animate beings

This research has been funded by the Galician Ministry of Education (Secrctaria Xeral de lnvestigación-PGIDT00PXI20407PR).

Model of Competencies for Decomposition of Human Behavior: Application to Control System of Robots

Humans and machines have shared the same physical space for many years. To share the same space, we want the robots to behave like human beings. This will facilitate their social integration, their interaction with humans and create an intelligent behavior. To achieve this goal, we need to understand how human behavior is generated, analyze tasks running our nerves and how they relate to them. Then and only then can we implement these mechanisms in robotic beings. In this study, we propose a model of competencies based on human neuroregulator system for analysis and decomposition of behavior into functional modules. Using this model allow separate and locate the tasks to be implemented in a robot that displays human-like behavior. As an example, we show the application of model to the autonomous movement behavior on unfamiliar environments and its implementation in various simulated and real robots with different physical configurations and physical devices of different nature. The main result of this study has been to build a model of competencies that is being used to build robotic systems capable of displaying behaviors similar to humans and consider the specific characteristics of robots.

Current Problems Involving the Dismantle of Asbestos- Cement Sheets in Buildings. The Case of Central Market in Alicante

The project and the works described in this article mainly deal with the removal of the current asbestos-cement covering of the roof of the Central Market in Alicante and its replacement with zinc diamond-shaped scales, similar to the originals which were implemented in 1921 when the building was put into service. These upgrades were necessary to avoid the causes (and consequences) of rainwater infiltration, as described in an earlier report in 2006, also drafted by the author of this article. The article illustrates the difficulties involving the practical application of Spanish Code RD 396/2006 (minimum safety and health requirements for work with risk of exposure to asbestos) in a complex case such as this, especially with regard to aspects such as economic (increasing costs), technical (increased difficulty of implementation), and the total duration of the work (total increase in duration due to interference with other trades).

Printed proposal and recommendation for a system of mensuration, 1796

This folder contains two newspaper clippings with the proposal for Croswell's "System of Mensuration," dated October 1796, as well as a printed recommendation for the work by Professor John Kemp.

Kinship system of the Seminole / by Alexander Spoehr.

v.33:no.2(1942)

Mathematics notebook, ca. 1714-1718, with chronology of the reign of Augustus

The first two pages of this notebook contain a comparative chronology of the reign of Augustus, outlined in two columns. One column outlines the chronology according to ecclesiastical scholar Laurence Echard, and the other column outlines the chronology according to William Cave. The rest of the notebook contains extensive entries on the following subjects, with related rules, problems, and illustrations: fractions, decimals, arithmetical progression, geometrical progression, "disjunct proportion, or ye Golden Rule," signs and symbols, integers, geometrical definitions, and Euclidian geometry.

The aboral nervous system of Marsupiocrinus Morris / C. R. C. Paul. --

v.16:no.18(1970)