Effect of thienyl groups on the photoisomerization and rotamerism of symmetric and asymmetric diaryl-ethenes and diaryl-butadienes.

Five symmetric (bis-substituted) and asymmetric (mono-substituted) analogues of E-stilbene and EE-1,4-diphenylbutadiene, where one or both the side aryls are 2'-thienyl or 3'-thienyl groups, have been studied by stationary and pulsed fluorimetric techniques, laser flash photolysis, conventional photochemical methods and theoretical calculations. The results obtained for these compounds and the comparison with those previously reported for three other compounds of the same series, allowed the effects of the position of the heteroatom and of the extension of the olefin chain on the excited state relaxation properties to be understood. The presence of one or two thienyl groups and their positional isomerism affect the spectral behaviour, the relaxation properties (radiative/reactive competition), the photoisomerization mechanism (singlet/triplet) and the ground state rotamerism. For the dienes containing the 3'-thienyl substituent(s), two rotamers were evidenced whose radiative and photochemical properties were obtained by selective excitation.     

Computational Modeling,Formal Analysis,and Tools for Systems Biology

As the amount of biological data in the public domain grows, so does the range of modeling and analysis techniques employed in systems biology. In recent years, a number of theoretical computer science developments have enabled modeling methodology to keep pace. The growing interest in systems biology in executable models and their analysis has necessitated the borrowing of terms and methods from computer science, such as formal analysis, model checking, static analysis, and runtime verification. Here, we discuss the most important and exciting computational methods and tools currently available to systems biologists. We believe that a deeper understanding of the concepts and theory highlighted in this review will produce better software practice, improved investigation of complex biological processes, and even new ideas and better feedback into computer science.     

Triterpenoids of Terminalia sericea

The structures of sericic acid and sericoside, the major constituents of the roots of Terminalia sericea, have been determined. Sericic acid is 2α,3β,19α,24-tetrahydroxy-olean-12-en-28-oic acid and sericoside the corresponding C-28 D-glucosyl ester.     

Immunosuppressive activity of human chorionic gonadotrophin preparations in vivo: evidence for gonadal dependence

Human chorionic gonadotrophin preparations (hCG), when injected ip daily for 4 days, suppress the delayed-type hypersensitivity (DTH) response of mice to sheep red blood cells. Preparations of crude hCG, purified hCG subunits, and hCG that was formed by recombining the purified subunits showed immunosuppressive activity in accord with their gonadotrophic activity. The immunosuppressive effects in male and female mice were comparable. However, removal of the gonads completely abrogated the immunosuppressive activity of hCG in both males and females, suggesting that the effect of hCG is mediated by a factor released from the gonads. We conclude that the hCG molecule itself exhibits immunosuppressive activity in vivo in both male and female mice and that the gonads are required for the expression of this activity.     

Reduction of cytochrome c by NADH induced by light

We have studied the behaviour of Fe(III) cytochrome c upon irradiation in the 290-360 nm wavelength range either in the presence or in the absence of NADH; in both cases the photoexcitation caused the reduction of the heme iron. When the irradiation was performed in the absence of NADH, the iron reduction was coupled to a non reversible modification in the protein structure; the photoreduction quantum yield was decreasing with the increase of the irradiation wavelength. Irradiation in the presence of NADH gave heme iron reduction coupled to NADH oxidation and the protein resulted finally unmodified; the quantum yield depended on the irradiation wavelength in a way similar to the observed in the absence of NADH, but it was tenfold higher. We propose that in both cases the active species is an electronic excited state of the heme iron.     

CotG controls spore surface formation in response to the temperature of growth in Bacillus subtilis

Bacterial spores of the Bacillus genus are ubiquitous in nature and are commonly isolated from a variety of diverse environments. Such wide distribution mainly reflects the spore resistance properties but some Bacillus species can grow/sporulate in at least some of the environments where they have been originally isolated. Growing and sporulating at different conditions is known to affect the structure and the resistance properties of the produced spore. In B. subtilis the temperature of growth and sporulation has been shown to influence the structure of the spore surface throughout the action of a sporulation-specific and heat-labile kinase CotH. Here we report that CotG, an abundant component of the B. subtilis spore surface and a substrate of the CotH kinase, assembles around the forming spore but also accumulates in the mother cell cytoplasm where it forms aggregates with at least two other coat components. Our data suggest that the thermo-regulator CotH contributes to the switch between the coat of 25°C and that of 42°C spores by controlling the phosphorylation levels of CotG that, in turn, regulates the assembly of at least two other coat components.     

A rapid diagnostic test for plague detects Yersinia pestis F1 antigen in ancient human remains

A rapid diagnostic dipstick test (RDT) that detects Yersinia pestis F1 antigen has been recently applied on 18 putative plague victims exhumed from four archaeological burial sites in southeastern France dating back to the 16(th), 17(th) and 18(th) centuries. The Y. pestis antigen F1 was detected in 12 ancient samples out of 18 (67%). Negative controls confirmed their negativity (100%). Our results emphasize that the detection threshold of the RDT for plague (0.5 ng/ml) is sufficient for a first retrospective diagnosis of Y. pestis infection in ancient remains, and confirm the high specificity and sensitivity of the assay. Double-blind analyses performed by using two different techniques (RDT and 'suicide PCR') led us to the identification of the Y. pestis F1 antigen and the Y. pestis pla and gplD genes. These data provide clear evidence of the presence of Y. pestis in the examined specimens.     

The ovipositing female of Ooencyrtus telenomicida relies on physiological mechanisms to mediate intrinsic competition with Trissolcus basalis

Ongoing studies by our group showed that the outcome of the intrinsic competition between two solitary egg parasitoids, Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), is dominated by O. telenomicida. In this article we investigated the role played by the ovipositing O. telenomicida female in the suppression of a T. basalis competitor. Laboratory experiments were conducted by allowing an O. telenomicida female to puncture the eggs of Nezara viridula (L.) (Heteroptera: Pentatomidae) with her ovipositor (= no oviposition) or to parasitize them. The results show that O. telenomicida relies on some physiological mechanisms to mediate its interspecific intrinsic competition with T. basalis. In fact, the emergence of T. basalis was strongly reduced in host eggs that were parasitized either before or after being punctured by O. telenomicida at fixed time intervals (5, 15, 30, or 45 h). The low percentage of emergence of T. basalis (ranging from approximately 4–20%) was a consequence of the delay and growth rate reduction of larval development. Furthermore, the percentage of eclosion of N. viridula nymphs was negatively affected by the O. telenomicida female’s punctures (96% from healthy host eggs, 4% from punctured host eggs). Host eggs punctured or oviposited in by O. telenomicida showed alterations in the ooplasm including some melanized‐like areas near the hole made with the ovipositor; such alterations indicate that the adult parasitoid releases substances that affect the host eggs survival. These results suggest that the O. telenomicida female influences both the physiological interspecific parasitoid‐parasitoid interaction, as well as the host‐parasitoid interaction, providing, for the first time in egg parasitoids, evidence that physiological suppression of some competitive egg parasitoids is mediated by the ovipositing female.     

Expression and display of UreA of <Emphasis Type="Italic">Helicobacter acinonychis</Emphasis> on the surface of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> spores

Background  

The bacterial endospore (spore) has recently been proposed as a new surface display system. Antigens and enzymes have been successfully exposed on the surface layers of the Bacillus subtilis spore, but only in a few cases the efficiency of expression and the effective surface display and have been determined. We used this heterologous expression system to produce the A subunit of the urease of the animal pathogen Helicobater acinonychis. Ureases are multi-subunit enzymes with a central role in the virulence of various bacterial pathogens and necessary for colonization of the gastric mucosa by the human pathogen H. pylori. The urease subunit UreA has been recognized as a major antigen, able to induce high levels of protection against challenge infections.