Dislodgement effect of natural semiochemicals released by disturbed triatomines: a possible alternative monitoring tool

The quick detection of domestic and peridomestic triatomines in their environments becomes difficult without the use of dislodgement substances that flush them out from their shelters. At present, tetramethrin 0.2% is being widely used in control programs. Although it is an efficient dislodging agent, its toxicity might affect the health of captured triatomines, of other insects and, to a lesser extent, of other animals, including humans. Here, we tested if semiochemicals released by disturbed adults of Triatoma infestans and/or Rhodnius prolixus can make larvae of the same species exit from their refuges. In a walking olfactometer we found that: 1) larvae of T. infestans were repelled by the odors released by disturbed adults of their own species and of R. prolixus, 2) larvae of R. prolixus did not change their behavior in the presence of odors released by adults of both species, and 3) activity levels were not modulated by these odors in any of both species. Besides, in pseudo‐natural conditions we found an increased flushing‐out activity of larvae of T. infestans when their shelters were sprayed with isobutyric acid or 3‐pentanol, and of larvae of R. prolixus when sprayed with 3‐methyl1butanol. We succeeded in this work to dislodge larvae of triatomines from artificial shelters using natural volatile compounds, allowing the capture of live bugs for further investigations (e.g., xenodiagnosis or genetic studies) and favoring ecological aspects (e.g., minimizing environmental insecticide‐contamination and non‐targeted mortality).     

Structural insights into dehydratase substrate selection for the borrelidin and fluvirucin polyketide synthases

Engineered polyketide synthases (PKSs) are promising synthetic biology platforms for the production of chemicals with diverse applications. The dehydratase (DH) domain within modular type I PKSs generates an α,β-unsaturated bond in nascent polyketide intermediates through a dehydration reaction. Several crystal structures of DH domains have been solved, providing important structural insights into substrate selection and dehydration. Here, we present two DH domain structures from two chemically diverse PKSs. The first DH domain, isolated from the third module in the borrelidin PKS, is specific towards a trans-cyclopentane-carboxylate-containing polyketide substrate. The second DH domain, isolated from the first module in the fluvirucin B₁ PKS, accepts an amide-containing polyketide intermediate. Sequence-structure analysis of these domains, in addition to previously published DH structures, display many significant similarities and key differences pertaining to substrate selection. The two major differences between BorA DH M3, FluA DH M1 and other DH domains are found in regions of unmodeled residues or residues containing high B-factors. These two regions are located between α3–β11 and β7–α2. From the catalytic Asp located in α3 to a conserved Pro in β11, the residues between them form part of the bottom of the substrate-binding cavity responsible for binding to acyl-ACP intermediates.

     

Structural and Dynamic Properties of Allergen and Non-Allergen Forms of Tropomyosin

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Using unmanned aerial vehicle (UAV) surveys and image analysis in the study of large surface‐associated marine species: a case study on reef sharks Carcharhinus melanopterus shoaling behaviour

A novel image analysis‐based technique applied to unmanned aerial vehicle (UAV) survey data is described to detect and locate individual free‐ranging sharks within aggregations. The method allows rapid collection of data and quantification of fine‐scale swimming and collective patterns of sharks. We demonstrate the usefulness of this technique in a small‐scale case study exploring the shoaling tendencies of blacktip reef sharks Carcharhinus melanopterus in a large lagoon within Moorea, French Polynesia. Using our approach, we found that C. melanopterus displayed increased alignment with shoal companions when distributed over a sandflat where they are regularly fed for ecotourism purposes as compared with when they shoaled in a deeper adjacent channel. Our case study highlights the potential of a relatively low‐cost method that combines UAV survey data and image analysis to detect differences in shoaling patterns of free‐ranging sharks in shallow habitats. This approach offers an alternative to current techniques commonly used in controlled settings that require time‐consuming post‐processing effort.     

Variability of the mc1r Gene in Melanic and Non-Melanic Podarcis lilfordi and Podarcis pityusensis from the Balearic Archipelago

The association between polymorphism at the mc1r locus and colour variation was studied in two wall lizard species (Podarcis lilfordi and P. pityusensis) from the Balearic archipelago. Podarcis lilfordi comprises several deep mitochondrial lineages, the oldest of which originated in the Pliocene, while much shallower mitochondrial lineages are found in P. pityusensis. Here, we examined whether specific substitutions were associated with the melanic colouration found in islet populations of these species. Homologous nuclear sequences covering most of the mc1r gene were obtained from 73 individuals from melanic and non-melanic Podarcis from different populations (the entire gene was also sequenced in six selected individuals). MtDNA gene trees were also constructed and used as a framework to assess mc1r diversity. Mc1r showed greater polymorphism in P. lilfordi than in P. pityusensis. However, we observed no substitutions that were common to all melanic individuals across the two species. Only one significant association was detected in the mc1r partial sequence, but this was a synonymous A/G mutation with A alleles being more abundant in melanic populations. In addition, there were no associations between the main dominant phenotypes (green and brown, blue and yellow spots and ventral colour) and synonymous or non-synonymous substitutions in the mc1r gene. There was no statistical evidence of selection on mc1r. This study suggests no relationship between mc1r polymorphism and colour variation in Balearic Podarcis.     

Fermentation of glycerol and production of valuable chemical and biofuel molecules

Glycerol has attracted the attention of scientific and industrial communities due to its generation in bulk quantities as a byproduct of biofuel industries. With the rapid growth of these industries in recent years, glycerol is frequently treated as a very low-value byproduct or even a waste product with a disposal cost associated to it. Glycerol is not only abundant and inexpensive but also can generate more reducing equivalents than glucose or xylose. This unique characteristic of glycerol offers a tremendous opportunity for its biological conversion to valuable products at higher yield. This review focuses on research efforts to utilize glycerol as a carbon source for the production of a variety of fuels and chemicals by both native and metabolically engineered microorganisms.     

2-Bromopalmitate Reduces Protein Deacylation by Inhibition of Acyl-Protein Thioesterase Enzymatic Activities

S-acylation, the covalent attachment of palmitate and other fatty acids on cysteine residues, is a reversible post-translational modification that exerts diverse effects on protein functions. S-acylation is catalyzed by protein acyltransferases (PAT), while deacylation requires acyl-protein thioesterases (APT), with numerous inhibitors for these enzymes having already been developed and characterized. Among these inhibitors, the palmitate analog 2-brompalmitate (2-BP) is the most commonly used to inhibit palmitoylation in cells. Nevertheless, previous results from our laboratory have suggested that 2-BP could affect protein deacylation. Here, we further investigated in vivo and in vitro the effect of 2-BP on the acylation/deacylation protein machinery, with it being observed that 2-BP, in addition to inhibiting PAT activity in vivo, also perturbed the acylation cycle of GAP-43 at the level of depalmitoylation and consequently affected its kinetics of membrane association. Furthermore, 2-BP was able to inhibit in vitro the enzymatic activities of human APT1 and APT2, the only two thioesterases shown to mediate protein deacylation, through an uncompetitive mechanism of action. In fact, APT1 and APT2 hydrolyzed both the monomeric form as well as the micellar state of the substrate palmitoyl-CoA. On the basis of the obtained results, as APTs can mediate deacylation on membrane bound and unbound substrates, this suggests that the access of APTs to the membrane interface is not a necessary requisite for deacylation. Moreover, as the enzymatic activity of APTs was inhibited by 2-BP treatment, then the kinetics analysis of protein acylation using 2-BP should be carefully interpreted, as this drug also inhibits protein deacylation.     

Developmental exposure to noninherited maternal antigens induces CD4+ T regulatory cells: relevance to mechanism of heart allograft tolerance

We hypothesize that developmental exposure to noninherited maternal Ags (NIMA) results in alloantigen-specific natural and adaptive T regulatory (T(R)) cells. We compared offspring exposed to maternal H-2(d) (NIMA(d)) with nonexposed controls. In vitro assays did not reveal any differences in T cell responses pretransplant. Adoptive transfer assays revealed lower lymphoproliferation and greater cell surface TGF-beta expression on CD4(+) T cells of NIMA(d)-exposed vs control splenocytes. NIMA(d)-exposed splenocytes exhibited bystander suppression of tetanus-specific delayed-type hypersensitivity responses, which was reversed with Abs to TGF-beta and IL-10. Allospecific T effector cells were induced in all mice upon i.v. challenge with B6D2F1 splenocytes or a DBA/2 heart transplant, but were controlled in NIMA(d)-exposed mice by T(R) cells to varying degrees. Some (40%) NIMA(d)-exposed mice accepted a DBA/2 allograft while others (60%) rejected in delayed fashion. Rejector and acceptor NIMA(d)-exposed mice had reduced T effector responses and increased Foxp3(+) T(R) cells (CD4(+)CD25(+)Foxp3(+) T(R)) in spleen and lymph nodes compared with controls. The key features distinguishing NIMA(d)-exposed acceptors from all other mice were: 1) higher frequency of IL-10- and TGF-beta-producing cells primarily in the CD4(+)CD25(+) T cell subset within lymph nodes and allografts, 2) a suppressed delayed-type hypersensitivity response to B6D2F1 Ags, and 3) allografts enriched in LAP(+), Foxp3(+), and CD4(+) T cells, with few CD8(+) T cells. We conclude that the beneficial NIMA effect is due to induction of NIMA-specific T(R) cells during ontogeny. Their persistence in the adult, and the ability of the host to mobilize them to the graft, may determine whether NIMA-specific tolerance is achieved.