Olfactory basis of floral preference of the malaria vector Anopheles gambiae (Diptera: Culicidae) among common African plants

Mosquitoes of both sexes feed on plants to obtain sugar. Nocturnal species probably locate the plants primarily by their volatile semiochemicals that also form the basis for the mosquitoes’ innate plant‐species preferences. To evaluate these olfactory preferences quantitatively, we used a two‐choice wind‐tunnel olfactometer to measure the upwind orientation of Anopheles gambiae Giles, an important vector of malaria in equatorial Africa, toward odor plumes produced by nine plant species common where this mosquito occurs. These plants are reported to induce feeding behaviors in An. gambiae and to produce floral or extrafloral nectar. Results presented here demonstrated that the volatiles of S. didymobotrya, P. hysterophorus, S. occidentalis, and L. camara, in descending order of numbers of mosquitoes responding, were all attractive, compared to a control plant species, whereas D. stramonium, R. communis, S. bicapsularis, T. stans, and T. diversifolia were not. As expected, chromatographic analysis of the headspace of attractive plants whose volatiles were captured by stir‐bar sorptive extraction revealed a wide range of compounds, primarily terpenoids. Once their bioactivity and attractiveness for An. gambiae, alone and in blends, has been firmly established, some of these semiochemicals may have applications in population sampling and control.     

Rapid Discrimination between Anopheles gambiae s.s. and Anopheles arabiensis by High-Resolution Melt (HRM) Analysis

There is a need for more cost-effective options to more accurately discriminate among members of the Anopheles gambiae complex, particularly An. gambiae and Anopheles arabiensis. These species are morphologically indistinguishable in the adult stage, have overlapping distributions, but are behaviorally and ecologically different, yet both are efficient vectors of malaria in equatorial Africa. The method described here, High-Resolution Melt (HRM) analysis, takes advantage of minute differences in DNA melting characteristics, depending on the number of incongruent single nucleotide polymorphisms in an intragenic spacer region of the X-chromosome-based ribosomal DNA. The two species in question differ by an average of 13 single-nucleotide polymorphisms giving widely divergent melting curves. A real-time PCR system, Bio-Rad CFX96, was used in combination with a dsDNA-specific dye, EvaGreen, to detect and measure the melting properties of the amplicon generated from leg-extracted DNA of selected mosquitoes. Results with seven individuals from pure colonies of known species, as well as 10 field-captured individuals unambiguously identified by DNA sequencing, demonstrated that the method provided a high level of accuracy. The method was used to identify 86 field mosquitoes through the assignment of each to the two common clusters with a high degree of certainty. Each cluster was defined by individuals from pure colonies. HRM analysis is simpler to use than most other methods and provides comparable or more accurate discrimination between the two sibling species but requires a specialized melt-analysis instrument and software.     

Intraspecific transfer of cantharidin within selected members of the family Meloidae (Insecta: Coleoptera)

The use of deuterium-labelled cantharidin (CAN-D(2)) to study details of cantharidin transfer in blister beetles indicates that the dynamics of organ-selective cantharidin accumulation may differ over time. Although the accessory glands absorb a high amount of CAN-D(2) in the short term, they ultimately accumulate less than the testes. Confirming previous studies, the last steps in the pathway of biosynthesis of cantharidin occur in the male's body distantly from the reproductive system but the ultimate product, cantharidin, is transported into the male reproductive tract via the membrane of the accessory glands. From there it first transfers preferentially to the epididimis and the vas deferens, followed by final deposition in the testes. Most, if not all, of the cantharidin passes internally within the sexual organs; hemolymph transport is not involved. In female meloids, cantharidin enters the genitalia from the male as a nuptial gift. High amounts are first absorbed by the spermatophoral receptacle followed by spreading through the ovaries and an ultimate accumulation in the eggs. The amount taken up by the ovaries remains considerably lower than that of the receptacle. Over time these two organs stop accumulating cantharidin, while the bursa copulatrix starts to incorporate the gift actively. The accumulated amount taken up by bursa is mainly supplied by the receptacle and ovaries suggesting that an internal transfer of cantharidin is used in females as the main transport route.     

Netrin-1 protects the SH-SY5Y cells against amyloid beta neurotoxicity through NF-κB/Nrf2 dependent mechanism

Molecular Biology Reports - Many evidence confirms that amyloid beta 1–42 fragment (Aβ1–42) causes neuroinflammation, oxidative stress, and cell death, which are related to...