Thermal requirement for development of Sancassania rodionovi (Acari: Acaridae) on mushrooms

The free-living mite species Sancassania rodionovi (Zachvatkin) (Acari: Acaridae), is a serious pest of mushrooms in Iran. Studies were conducted to examine the development of this mite in relation to temperature on two mushroom species: Agaricus bisporus Lange (button mushroom) and Pleurotus ostreatus Kummer (oyster mushroom). The developmental time of this acarid mite was studied at eight constant temperatures, ranging from 5 to 40 degrees C, and developmental rates were modeled as a function of temperature. Sancassania rodionovi completed immature development in 17.35 +/- 0.58 and 20.17 +/- 0.88 d at 25 degrees C on button and oyster mushrooms, respectively. When the mite fed on button mushroom, the rate of development increased gradually from 10 to 35 degrees C. Using a linear model, the developmental zero was estimated to be 3.50 degrees C with a thermal constant of 357.14 degree-days. The Logan 10, Briere 1, and Thermodynamic models adequately described the data for this mite and yielded R2 values >0.95; these models provided estimates of optimum temperature for development of 33.244, 32.145, and 32.148 degrees C, respectively. Understanding the influence of temperature on development of S. rodionovi is discussed with respect to pest management in mushroom production.     

A theoretical elucidation of bilirubin interaction with HSA's lysines: first electrostatic binding site in IIA subdomain

The electrostatic interaction of amino acid lysines 190, 195 and 199 of human serum albumin (HSA) with bilirubin have been investigated using molecular dynamic simulations, QM and QM/MM minimization methods. In this study two methodological approaches have been employed. In the first approach X-ray structure and the structure obtained from the molecular dynamic simulation of subdomain IIA of HSA in vacuum have been utilized. Interactions have been evaluated with the segment 186-200 of the cited subdomain. Calculations on the X-ray structure of above segment indicate an effective interaction of the lysine 195 with bilirubin, although that of the lysine 190 is also found considerable in this structure. Performing simulation in vacuum, it has been revealed that except for the lysine 195, the other two lysine residues (190 and 199) could not be considered as centers of interaction. Such finding, which is in accord with experimental data, lends support to the procedure employed in this study. NBO analyses suggest that tasks to achieve a structure indicating bilirubin interaction with the lysine 195 from the 186-200 segment extracted from X-ray structure, results in a structure that lacks any electrostatic interaction. In fact, it has been found that the stability of the latter species can be attributed to the H-bonding interaction of the glutamate 188 with both bilirubin and the lysine 195. Further NBO analysis on the structure of the same species, while achieved after molecular dynamic simulation on subdomain IIA in vacuum has revealed that a favorable electrostatic interaction between the lysine 195 and bilirubin has occurred. Besides, H-bonding interaction of the glutamate 188 with bilirubin has been evident in the same species. For the second approach, presence of water molecules and ions has been considered to simulate condensed medium. Applying docking, conformational sampling, and QM/MM minimization steps in sequence, a structure has been achieved which presents a specific interaction between epsilon-NH3(+) group of the lysine 195 residue and the lactam oxygen atom of bilirubin. NBO analyses suggest that above electrostatic interaction is combined with hydrogen bonding interaction between same two groups. Moreover, a hydrogen bond between oxygen atom of bilirubin's acetate group and alpha-NH group of lysine 195 has been observed. Molecular orbital calculations have been presented which support the NBO analyses.     

Probing the gamma2 calcium-binding site: studies with gammaD298,301A fibrinogen reveal changes in the gamma294-301 loop that alter the integrity of the "a" polymerization site

To determine the significance of the gamma2 calcium-binding site in fibrin polymerization, we synthesized the fibrinogen variant, gammaD298,301A. We expected these two alanine substitutions to prevent calcium binding in the gamma2 site. We examined the influence of calcium on the polymerization of gammaD298,301A fibrinogen, evaluated its plasmin susceptibility, and solved 2.7 and 2.4 A crystal structures of the variant with the peptide ligands Gly-Pro-Arg-Pro-amide (GPRP) and Gly-His-Arg-Pro-amide (GHRP), respectively. We found that thrombin-catalyzed polymerization of gammaD298,301A fibrinogen was modestly impaired, whereas batroxobin-catalyzed polymerization was significantly impaired relative to normal fibrinogen. Notably, the influence of calcium on polymerization was the same for the variant and for normal fibrinogen. Fibrinogen gammaD298,301A was more susceptible to plasmin proteolysis in the presence of GPRP. This finding suggests structural changes in the near-by "a" polymerization site. Comparisons of the structures revealed minor conformational changes in the gamma294-301 loop that are likely responsible for the weakened "a" site. When considered altogether, the data suggest that the gamma2 calcium-binding site does not significantly modulate polymerization. We cannot, however, rule out the possibility that the weakened "a" polymerization site masks an important role for the gamma2 calcium-binding site in normal polymerization. Somewhat unexpectedly, the structure data showed that GPRP bound to the "b" site and induced the same local conformational changes as GHRP to this site. This structure shows that "A:b" interactions can occur and suggests that these may participate in normal polymerization.     

Essential oil composition of Hypericum triquetrifolium Turra. aerial parts

The essential oil obtained by hydrodistillation from the aerial parts of Tunisian endemic Hypericum triquetrifolium Turra (Clusiaceae) was analyzed using GC and GC-MS. One hundred and nine compounds consisting of 92.2% of total detected constituents were identified. Sesquiterpene hydrocarbons were the main constituents (59.37%), Alpha-humulene, cis-calamenene, delta-cadinene, bicyclogermacrene, eremophilene, betacaryophyllene and (E)-gamma-bisabolene were found as the main ones. Alpha-pinene (10.33%) was detected as the main monoterpene hydrocarbons (12.19%). The oxygenated sesquiterpenes constituted (9.33%); caryophyllene oxide (1.38%) was reported as the main constituent of this fraction. The oxygenated monoterpenes were weakly represented (4.62%) and consisted of constituents in low percentages (<1%).     

Une nouvelle observation d’une métastase testiculaire d’un adénocarcinome prostatique: Aspects diagnostiques et éthiopathogéniques

Testicular metastases from prostatic adenocarcinoma are rare. They are often asymptomatic and diagnosed incidentally or at autopsy after orchidectomy in more advanced stages of the disease. The authors report a new case and review the diagnosis and aetiopathogenesis of these metastases. A 67-year-old patient with prostatic adenocarcinoma presented with painless right testicular mass for two months with no inflammatory signs. Germ cell tumour serum markers were negative. Scrotal ultrasound showed a large testicular tumour measuring 7×4×3cm. Histological examination revealed a solid non-differentiated tumour, not suggestive of primary testicular tumour. The immunohistochemical panel confirmed the prostate as the primary site due to the positivity of cytokeratins, PSA and PSAP and the negativity of classical markers of germ cell tumours. Testicular metastases from prostatic adenocarcinoma are rare, but their incidence is currently on the increase. They are often asymptomatic and discovered after pulpectomy. This diagnosis must be considered in the case of a testicular mass in patients over the age of 50 with a history of prostatic adenocarcinoma. The diagnosis was established after orchidectomy by histological examination and immunohistochemical tests.     

Endobrevin/VAMP-8 is the primary v-SNARE for the platelet release reaction

Platelet secretion is critical to hemostasis. Release of granular cargo is mediated by soluble NSF attachment protein receptors (SNAREs), but despite consensus on t-SNAREs usage, it is unclear which Vesicle Associated Membrane Protein (VAMPs: synaptobrevin/VAMP-2, cellubrevin/VAMP-3, TI-VAMP/VAMP-7, and endobrevin/VAMP-8) is required. We demonstrate that VAMP-8 is required for release from dense core granules, alpha granules, and lysosomes. Platelets from VAMP-8-/- mice have a significant defect in agonist-induced secretion, though signaling, morphology, and cargo levels appear normal. In contrast, VAMP-2+/-, VAMP-3-/-, and VAMP-2+/-/VAMP-3-/- platelets showed no defect. Consistently, tetanus toxin had no effect on secretion from permeabilized mouse VAMP-3-/- platelets or human platelets, despite cleavage of VAMP-2 and/or -3. Tetanus toxin does block the residual release from permeabilized VAMP-8-/- platelets, suggesting a secondary role for VAMP-2 and/or -3. These data imply a ranked redundancy of v-SNARE usage in platelets and suggest that VAMP-8-/- mice will be a useful in vivo model to study platelet exocytosis in hemostasis and vascular inflammation.     

Quantifying the metabolic capabilities of engineered <Emphasis Type="Italic">Zymomonas mobilis</Emphasis> using linear programming analysis

Background  

The need for discovery of alternative, renewable, environmentally friendly energy sources and the development of cost-efficient, "clean" methods for their conversion into higher fuels becomes imperative. Ethanol, whose significance as fuel has dramatically increased in the last decade, can be produced from hexoses and pentoses through microbial fermentation. Importantly, plant biomass, if appropriately and effectively decomposed, is a potential inexpensive and highly renewable source of the hexose and pentose mixture. Recently, the engineered (to also catabolize pentoses) anaerobic bacterium Zymomonas mobilis has been widely discussed among the most promising microorganisms for the microbial production of ethanol fuel. However, Z. mobilis genome having been fully sequenced in 2005, there is still a small number of published studies of its in vivo physiology and limited use of the metabolic engineering experimental and computational toolboxes to understand its metabolic pathway interconnectivity and regulation towards the optimization of its hexose and pentose fermentation into ethanol.     

A conserved Pol? binding module in Ctf18-RFC is required for S-phase checkpoint activation downstream of Mec1

Defects during chromosome replication in eukaryotes activate a signaling pathway called the S-phase checkpoint, which produces a multifaceted response that preserves genome integrity at stalled DNA replication forks. Work with budding yeast showed that the ‘alternative clamp loader’ known as Ctf18-RFC acts by an unknown mechanism to activate the checkpoint kinase Rad53, which then mediates much of the checkpoint response. Here we show that budding yeast Ctf18-RFC associates with DNA polymerase epsilon, via an evolutionarily conserved ‘Pol ϵ binding module’ in Ctf18-RFC that is produced by interaction of the carboxyl terminus of Ctf18 with the Ctf8 and Dcc1 subunits. Mutations at the end of Ctf18 disrupt the integrity of the Pol ϵ binding module and block the S-phase checkpoint pathway, downstream of the Mec1 kinase that is the budding yeast orthologue of mammalian ATR. Similar defects in checkpoint activation are produced by mutations that displace Pol ϵ from the replisome. These findings indicate that the association of Ctf18-RFC with Pol ϵ at defective replication forks is a key step in activation of the S-phase checkpoint.