Deciphering the GPER/GPR30-agonist and antagonists interactions using molecular modeling studies,molecular dynamics,and docking simulations

The G-protein coupled estrogen receptor 1 GPER/GPR30 is a transmembrane seven-helix (7TM) receptor involved in the growth and proliferation of breast cancer. Due to the absence of a crystal structure of GPER/GPR30, in this work, molecular modeling studies have been carried out to build a three-dimensional structure, which was subsequently refined by molecular dynamics (MD) simulations (up to 120 ns). Furthermore, we explored GPER/GPR30’s molecular recognition properties by using reported agonist ligands (G1, estradiol (E2), tamoxifen, and fulvestrant) and the antagonist ligands (G15 and G36) in subsequent docking studies. Our results identified the E2 binding site on GPER/GPR30, as well as other receptor cavities for accepting large volume ligands, through GPER/GPR30 π–π, hydrophobic, and hydrogen bond interactions. Snapshots of the MD trajectory at 14 and 70 ns showed almost identical binding motifs for G1 and G15. It was also observed that C107 interacts with the acetyl oxygen of G1 (at 14 ns) and that at 70 ns the residue E275 interacts with the acetyl group and with the oxygen from the other agonist whereas the isopropyl group of G36 is oriented toward Met141, suggesting that both C107 and E275 could be involved in the protein activation. This contribution suggest that GPER1 has great structural changes which explain its great capacity to accept diverse ligands, and also, the same ligand could be recognized in different binding pose according to GPER structural conformations.     

HRV spectral estimation based on constrained Gaussian modeling in the nonstationary case

The heart rate variability (HRV) spectral parameters are classically used for studying the autonomic nervous system, as they allow the evaluation of the balance between the sympathetic and parasympathetic influences on heart rhythm. However, this evaluation is usually based on fixed frequency regions, which does not allow possible variation, or is based on an adaptive individual time dependent spectral boundaries (ITSB) method sensitive to noisy environments. In order to overcome these difficulties, we propose the constrained Gaussian modeling (CGM) method that dynamically models the power spectrum as a two Gaussian shapes mixture. It appeared that this procedure was able to accurately follow the exact parameters in the case of simulated data, in comparison with a parameter estimation obtained with a rigid frequency cutting approach or with the ITSB algorithm. Real data results obtained on a classical stand-test and on the Fantasia database are also presented and discussed.     

Old and new host-parasitoid associations: parasitism of the invasive fruit fly Bactrocera invadens (Diptera: Tephritidae) and five African fruit fly species by Fopius arisanus,an Asian opiine parasitoid

Fopius arisanus (Sonan), a solitary koinobiont endoparasitoid of fruit flies, was introduced for testing and final release against the recently discovered species Bactrocera invadens Drew, Tsuruta and White in Africa. Laboratory experiments were conducted to assess host preference, host acceptability for oviposition, and physiological suitability of B. invadens and five other indigenous tephritid fruit fly species, namely, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), C. cosyra (Walker), C. rosa Karsch, C. fasciventris (Bezzi), and C. anonae Graham. Females of F. arisanus visited all host egg patches, but showed a stronger preference to eggs of B. invadens, which was also most accepted for oviposition. Successful development of parasitoid progenies varied greatly across hosts, with B. invadens yielding the highest parasitoid progeny and C. fasciventris yielding no F. arisanus progeny. Most of the parasitoid eggs laid in C. rosa and C. fasciventris were encapsulated. Sex ratio was not influenced by host species and it was female biased in all hosts that produced parasitoid progeny. Fopius arisanus was able to establish a new association with C. capitata, C. cosyra and to a lesser extent C. anonae. The results are discussed in the light of the potential use of F. arisanus as a biological control agent of B. invadens.     

Impact of Next Generation Sequencing Techniques in Food Microbiology

Understanding the Maxam-Gilbert and Sanger sequencing as the first generation, in recent years there has been an explosion of newly-developed sequencing strategies, which are usually referred to as next generation sequencing (NGS) techniques. NGS techniques have high-throughputs and produce thousands or even millions of sequences at the same time. These sequences allow for the accurate identification of microbial taxa, including uncultivable organisms and those present in small numbers. In specific applications, NGS provides a complete inventory of all microbial operons and genes present or being expressed under different study conditions. NGS techniques are revolutionizing the field of microbial ecology and have recently been used to examine several food ecosystems. After a short introduction to the most common NGS systems and platforms, this review addresses how NGS techniques have been employed in the study of food microbiota and food fermentations, and discusses their limits and perspectives. The most important findings are reviewed, including those made in the study of the microbiota of milk, fermented dairy products, and plant-, meat- and fish-derived fermented foods. The knowledge that can be gained on microbial diversity, population structure and population dynamics via the use of these technologies could be vital in improving the monitoring and manipulation of foods and fermented food products. They should also improve their safety.     

Extension of the transmission area of kala-azar caused by Leishmania infantum (Nicolle 1908) to the center and south of Tunisia]

Seventeen (17) parasitologically confirmed cases of infantile kala azar (KA) are reported from 1982 to 1991 in Tunisia, in areas (Gouvernorates of Sidi Bouzid, Kasserine, Sfax, Gafsa and Tozeur) where the disease has never (or exceptionally) been reported before. This tendency to the extension of the KA areas from Northern Tunisia to the Central and Southern parts could be explained by the ecological modifications that occurred in these zones following agriculture development programs that included an important increase of water resources (wells, dams etc...). These modifications probably contributed to the enhancement of the Leishmania infantum vector population densities making it possible for transmission cycles to be implemented and maintained in these areas; the parasite could have been brought with dogs from the North of the country.     

Overproduction and properties of lipase by a wild strain of Burkholderia lata LBBIO-BL02 using chicken fat

In this work, we report the overproduction of lipases by a new wild strain of Burkholderia lata (LBBIO-BL02) in submerged fermentation to seek an economically attractive bioprocess. The best fermentation medium composition was containing chicken fat (12.5 mL/L) and ammonium phosphate (15 g/L) at 35 ºC and pH 7.0, resulting in a lipase titer of 1137.82 U/mL and 2146.83 U/mg. The lipase characterization exhibited maximum activity at 55 °C and pH 8.0. The lipase retained 100, 93 and 85 % of its maximum activity at 45, 50 and 60 °C, respectively, and 78, 82 and 100 % at pH 2.2, 3 and 10, respectively. The enzyme was successfully immobilized on Celite by adsorption and showed a promising future for various organic syntheses because of its stability in organic solvents. All the results shows that Burkholderia lata LBBIO-BL02 is a superior lipase-producing bacterium and its enzyme showed good potential for industrial and biotechnology application.     

Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Precise control of mRNA translation is fundamental for eukaryotic cell homeostasis, particularly in response to physiological and pathological stress. Alterations of this program can lead to the growth of damaged cells, a hallmark of cancer development, or to premature cell death such as seen in neurodegenerative diseases. Much of what is known concerning the molecular basis for translational control has been obtained from polysome analysis using a density gradient fractionation system. This technique relies on ultracentrifugation of cytoplasmic extracts on a linear sucrose gradient. Once the spin is completed, the system allows fractionation and quantification of centrifuged zones corresponding to different translating ribosomes populations, thus resulting in a polysome profile. Changes in the polysome profile are indicative of changes or defects in translation initiation that occur in response to various types of stress. This technique also allows to assess the role of specific proteins on translation initiation, and to measure translational activity of specific mRNAs. Here we describe our protocol to perform polysome profiles in order to assess translation initiation of eukaryotic cells and tissues under either normal or stress growth conditions.