Phytochemical composition of Cymbopogon citratus and Eucalyptus citriodora essential oils and their anti-inflammatory and analgesic properties on Wistar rats

Cymbopogon citratus and Eucalyptus citriodora are widely used herbs/plants as a source of ethnomedicines in tropical regions of the world. In this work, we studied the anti-inflammatory and gastroprotective effects of C. citratus and E. citriodora essential oils on formol-induced edema, and acetic acid induced abdominal cramps in Wistar rats. To fully understand the chemically induced anti-inflammatory properties of these plants, we first analyzed the chemical composition of the essential oils. A total of 16 chemical constituents accounting for 93.69 % of the oil, were identified in C. citratus among which, Geranial (27.04 %), neral (19.93 %) and myrcene (27.04 %) were the major constituents. For E. citriodora, 19 compounds representing 97.2 % of the extracted oil were identified. The dominant compound of E. citriodora essential oil was citronellal (83.50 %). In vivo analysis and histological assay showed that the two essential oils displayed significant dose dependent edema inhibition effect over time. They displayed strong analgesic and antipyretic properties similar to that induced by 50 mg/kg of acetylsalicylate of lysine. However, the E. citriodora essential oil was more effective than that of C. citratus. We identified significant numbers of aldehyde molecules in both essential oils mediating antioxidant activity that may contribute to the anti-inflammatory effects observed on the rats. Altogether, this work demonstrates the anti-inflammatory property of C. citratus and E. citriodora suggesting their potential role as adjuvant therapeutic alternatives in dealing with inflammatory-related diseases.     

Isolation and characterization of tetranucleotide microsatellite markers in a mouth‐brooding haplochromine cichlid fish (Pseudocrenilabrus multicolor victoriae) from Uganda

Eight tetranucleotide microsatellite loci were isolated from the haplochromine cichlid fish, Pseudocrenilabrus multicolor victoriae, an important model species for studies in respiratory ecology, conservation, and evolution. We surveyed variation at these loci in 23 individuals from western Uganda, finding four to 19 alleles per locus and an average expected heterozygosity of 0.8575. These microsatellite loci will be used to examine gene flow and population structure in Ugandan P. m. victoriae.     

Uncovering the Mechanisms of Shrimp Innate Immune Response by RNA Interference

Because of the importance of shrimp in world aquaculture, there is much interest in understanding their immune system in order to improve their resistance to pathogenic microorganisms. An effective tool in studying genes involved in the immune response in shrimp is RNA interference (RNAi). RNAi, first recognized as an antiviral response against RNA viruses, is a cellular mechanism that is triggered by double-stranded RNAs and results in the degradation of homologous genes. In this review, we describe the current studies of genes in shrimp that employed RNAi technology to elucidate or confirm their functions. We also review the potential of RNAi to elicit antiviral response in shrimp.     

Role of cell-to-cell variability in activating a positive feedback antiviral response in human dendritic cells

In the first few hours following Newcastle disease viral infection of human monocyte-derived dendritic cells, the induction of IFNB1 is extremely low and the secreted type I interferon response is below the limits of ELISA assay. However, many interferon-induced genes are activated at this time, for example DDX58 (RIGI), which in response to viral RNA induces IFNB1. We investigated whether the early induction of IFNBI in only a small percentage of infected cells leads to low level IFN secretion that then induces IFN-responsive genes in all cells. We developed an agent-based mathematical model to explore the IFNBI and DDX58 temporal dynamics. Simulations showed that a small number of early responder cells provide a mechanism for efficient and controlled activation of the DDX58-IFNBI positive feedback loop. The model predicted distributions of single cell responses that were confirmed by single cell mRNA measurements. The results suggest that large cell-to-cell variation plays an important role in the early innate immune response, and that the variability is essential for the efficient activation of the IFNB1 based feedback loop.     

Foraging and pollination behaviour of Xylocopa calens Lepeletier (Hymenoptera: Apidae) on Phaseolus coccineus L. (Fabaceae) flowers at Yaounde (Cameroon)

To evaluate impact of carpenter bee, Xylocopa calens, on pod and seed set of Phaseolus coccineus, its foraging and pollinating activities were studied in Yaounde, for two seasons (May–July 2008 and April–June 2009). Observations were made on 40 inflorescences per treatment. The treatments included unlimited floral access by all visitors, bagged flowers to deny all visits, and limited visits by X. calens only. In addition, all flower visitors were recorded. The carpenter bee's seasonal rhythm of activity, its foraging behavior on flowers, its pollination efficiency, the fructification rate and the number of seeds per pod were recorded. Individuals from 16 species of insects were recorded visiting flowers of P. coccineus in the 2 years. Xylocopa calens was the most frequent, followed by Chalicodoma cincta cincta and Apis mellifera. Apart from bees, wasps were also recorded as likely predators. Xylocopa calens mainly foraged for nectar resources. The mean foraging speed was 9.62 flowers/min. Flowers visited by X. calens had higher fruiting rate compared with others, while those bagged had the lowest. In addition, seed formation was higher in X. calens‐visited flowers compared with all others. The results show that this crop experiences pollination deficit even under normal circumstances, considering that flowers visited by X. calens had higher yields compared with those under unlimited access by all visitors. The fruiting rate, the number of seeds/pod and the percentage of normal seeds of unprotected inflorescences were significantly higher than those of inflorescences protected from insects. X. calens foraging resulted in a significant increment of the fruiting rate by 25.80%, as well as the number of seeds/pod by 14.97% and the percentage of normal seeds by 27.75% in 2008 and 18.39% in 2009. Conservation of X. calens nests close to P. coccineus fields could be recommended to improve pod and seed production in the region.     

Measuring chess experts' single-use sequence knowledge: an archival study of departure from 'theoretical' openings

The respective roles of knowledge and search have received considerable attention in the literature on expertise. However, most of the evidence on knowledge has been indirect--e.g., by inferring the presence of chunks in long-term memory from performance in memory recall tasks. Here we provide direct estimates of the amount of monochrestic (single use) and rote knowledge held by chess players of varying skill levels. From a large chess database, we analyzed 76,562 games played in 2008 by individuals ranging from Class B players (average players) to Masters to measure the extent to which players deviate from previously known initial sequences of moves ("openings"). Substantial differences were found in the number of moves known by players of different skill levels, with more expert players knowing more moves. Combined with assumptions independently made about the branching factor in master games, we estimate that masters have memorized about 100,000 opening moves. Our results support the hypothesis that monochrestic knowledge is essential for reaching high levels of expertise in chess. They provide a direct, quantitative estimate of the number of opening moves that players have to know to reach master level.     

Inhibition of human-type 1 3beta-hydroxysteroid deshydrogenase/Delta(5)-Delta(4)-isomerase expression using siRNA

Specific inhibition of type 1 3beta-HSD is of particular interest since it will allow us to control the formation of androgens and estrogens in peripheral target tissues without affecting type 2 3beta-HSD, which is responsible for the biosynthesis of glucocorticoids and mineralocorticoids in the adrenals. The high homology between types 1 and 2 3beta-HSD is a major difficulty in the development of specific inhibitors through classical chemical synthesis. In this report, we describe the use of small interference RNA (siRNA) to specifically inhibit human type 1 3beta-HSD. We have constructed three DNA vector-based RNAi vectors that allow us to produce three RNA duplexes of 21 nucleotides targeting three different coding regions of human type 1 3beta-HSD mRNA. The resulting constructs were co-transfected into HEK-293 cells with a vector expressing type 1 3beta-HSD. The results indicate that while the two duplexes that target sequences in the 5'-region do not have a strong inhibitory effect, the duplex that targets the 3'-region efficiently inhibits 3beta-HSD activity. Up to 98% inhibition has been observed. To our knowledge, this is the first report showing successful inhibition of steroidogenic enzymes using siRNA technology.     

Comparison of crystal structures of human type 3 3alpha-hydroxysteroid dehydrogenase reveals an "induced-fit" mechanism and a conserved basic motif involved in the binding of androgen

The aldo-keto reductase (AKR) human type 3 3alpha-hydroxysteroid dehydrogenase (h3alpha-HSD3, AKR1C2) plays a crucial role in the regulation of the intracellular concentrations of testosterone and 5alpha-dihydrotestosterone (5alpha-DHT), two steroids directly linked to the etiology and the progression of many prostate diseases and cancer. This enzyme also binds many structurally different molecules such as 4-hydroxynonenal, polycyclic aromatic hydrocarbons, and indanone. To understand the mechanism underlying the plasticity of its substrate-binding site, we solved the binary complex structure of h3alpha-HSD3-NADP(H) at 1.9 A resolution. During the refinement process, we found acetate and citrate molecules deeply engulfed in the steroid-binding cavity. Superimposition of this structure with the h3alpha-HSD3-NADP(H)-testosterone/acetate ternary complex structure reveals that one of the mobile loops forming the binding cavity operates a slight contraction movement against the citrate molecule while the side chains of many residues undergo numerous conformational changes, probably to create an optimal binding site for the citrate. These structural changes, which altogether cause a reduction of the substrate-binding cavity volume (from 776 A(3) in the presence of testosterone/acetate to 704 A(3) in the acetate/citrate complex), are reminiscent of the "induced-fit" mechanism previously proposed for the aldose reductase, another member of the AKR superfamily. We also found that the replacement of residues Arg(301) and Arg(304), localized near the steroid-binding cavity, significantly affects the 3alpha-HSD activity of this enzyme toward 5alpha-DHT and completely abolishes its 17beta-HSD activity on 4-dione. All these results have thus been used to reevaluate the binding mode of this enzyme for androgens.