Engineering genetic circuits: advancements in genetic design automation tools and standards for synthetic biology

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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.     

Orientation and Shape Discrimination in Juveniles and Adults of the Mangrove Crab Aratus pisonii (H. Milne Edwards, 1837): Effect of Predator and Chemical Cues

Behavioral responses of juveniles and adults of the mangrove crab Aratus pisonii (H. Milne Edwards, 1837) to black geometric shapes of equal surface area was measured. Crabs were tested either in presence or absence of chemicals generated from two common predator species, the portunid crab Callinectes ornatus Ordway, and the soapfish Haemulon aurolineatum Cuvier, 1830. The present study tested the hypothesis that A. pisonii (1) has the capacity to orient to visual cues; (2) it discriminates between different visual objects based on a combination of chemical and visual information and (3) this behavior changes with age. When presented with single black targets in background water, juveniles oriented toward all shapes. This behavioral response was interpreted as visual orientation toward potential shelter. Among shapes, juveniles showed preference for the vertical rectangle, probably due to the recognition of natural visual elements like mangrove roots. In predator conditioned water, juveniles exhibited a stronger response than in background water. Thus, juveniles were able to detect by odor the potential presence of predators. Change in responsiveness between adults and juveniles was also demonstrated.     

Aminoadamantanes containing monoterpene-derived fragments as potent tyrosyl-DNA phosphodiesterase 1 inhibitors

The ability of a number of nitrogen-containing compounds that simultaneously carry the adamantane and monoterpene moieties to inhibit Tdp1, an important enzyme of the DNA repair system, is studied. Inhibition of this enzyme has the potential to overcome chemotherapeutic resistance of some tumor types. Compound (+)-3c synthesized from 1-aminoadamantane and (+)-myrtenal, and compound 4a produced from 2-aminoadamantane and citronellal were found to be most potent as they inhibited Tdp1 with IC₅₀ values of 6 and 3.5 µM, respectively. These compounds proved to have low cytotoxicity in colon HCT-116 and lung A-549 human tumor cell lines (CC₅₀ > 50 µM). It was demonstrated that compound 4a at 10 µM enhanced cytotoxicity of topotecan, a topoisomerase 1 poison in clinical use, against HCT-116 more than fivefold and to a lesser extent of 1.5 increase in potency for A-549.     

Focal contacts of spreading platelets with the substratum

Contacts with glass substratum formed by the spreading rabbit platelets were examined by an antibody-exclusion method; monoclonal antibodies against 80 kD bovine serum protein were used. It was found that platelets form focal contacts in the course of spreading. The size of the largest focal contacts formed by platelets is smaller than that of the contacts formed by fibroblasts. The antibody-exclusion method revealed focal contacts of platelets much more clearly than interference reflection microscopy (IRM). The similarity of reactions involved in spreading platelets and of large nucleus-containing tissue cells is discussed.     

Essential oil of Ayapana triplinervis from Reunion Island: A good natural source of thymohydroquinone dimethyl ether

Three specimens of Ayapana triplinervis (Vahl) R.M. King & H. Rob from Reunion Island (Indian Ocean) collected at two distant locations (North of the island; samples 1 and 2, South of the island; sample 3), in different growth phases (flowering; samples 1 and 3, vegetative; sample 2) were investigated for their leaf essential oil composition. This study reports the chemical character of this species on the island and investigates the relationship between essential oil composition, developmental stage and geographic location. Analysis by GC–FID and GC–MS enabled us to identify and quantify a total of 39 constituents accounting for 97.1–98.0% of the oils. The three essential oil samples, all obtained by hydrodistillation, showed a high percentage of the aromatic compound thymohydroquinone dimethyl ether (89.9–92.8%). All other minor components remained more or less unchanged both qualitatively and quantitatively with respect to the stage of growth. On the contrary, variations were observed with geographic distribution. The geographical variation of the chemical composition of the volatile oil of A. triplinervis from several sites in the world is also briefly discussed.     

Physical and chemical variability in sugarcane fields infested with the red-striped soft scale insect,Pulvinaria Tenuivalvata (Newstead)

The red-striped soft scale insect Pulvinaria tenuivalvata (Newstead) (Hemiptera: Coccidae) started to infest sugarcane plants (Saccharum officinarum L.) in different districts in Egypt during the last decade. The percentage of infestation was recorded in El-Wakf area, Qena Governorate (Naghhamadi mill zone) Upper Egypt in some fields. There are three levels of infestation, low, intermediate and high. From these fields, samples were selected for physical and chemical studies. The results obtained show that the stalks of infested plants decreased in weight, the sugar content (glucose and sucrose) drastically reduced and as the percentage of infestation increased the percentage of glucose and sucrose content significantly decreased. The primary and secondary humidity and the cellulose content also increased in the healthy plants compared to the infested ones. All the physical character of the infested plants was significantly affected in comparison with the healthy ones.     

Chemical constituents of the roots of Scorzonera divaricata and their chemotaxonomic significance

The phytochemical study of the roots of Scorzonera divaricata Turcz led to the isolation of 27 compounds, including eight sterols (1–8), one lignan (9), two cumarins (10, 11), five phenylpropanoids (12–16), six benzene derivatives (17–22), methyl-β-D-fructofuranoside (23), monolinolein (24), and three aliphatic acids (25–27). The structures of isolated compounds were identified using NMR and ESI-MS spectroscopic methods and comparing them with those previously reported. Except for β-daucosterol (8), scopoletin (10) and caffeic acid (16) from S. divaricata, this is the first report of the other 24 compounds from S. divaricata. Among them, eleven compounds (2–6, 11, 17, 19, 20, 23, 25) were reported from genus Scorzonera for first time, suggesting that they could be used to distinguish S. divaricata from the other species of Scorzonera. Furthermore, the chemotaxonomic significance of isolated compounds from S. divaricata has also been discussed.     

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.     

Synthesis of ABO histo-blood group type I and II antigens

The ABO histo-blood group system is one of the most clinically important antigen families. As part of our overall goal to prepare the entire set of the A, B and H type I-VI antigens for a range of biochemical investigations, we report herein the synthesis of the type I and II antigens with a 7-octen-1-yl aglycone. This linker was chosen to facilitate not only the future conjugation of the antigens to a protein or solid support but also the synthesis of the H type I and II octyl glycosides for enzyme kinetic studies.