31P NMR of tissue phospholipids: a comparison of three tissue pre-treatment procedures

Extracted tissue phospholipid 31P NMR profiles, obtained from individual porcine lenses subjected to two preservation procedures (acetone desiccation and freeze-drying) and a perchloric acid-extraction procedure, were compared to those from freshly excised lens specimens. Each profile yielded quantitative data on 12 lens phospholipids: PC, LPC, PC plas, PE, LPE, PE plas, PS, SPH, PI, LPI, PG, and CL. A specimen group size of at least 9 lenses was required for secure statistical inter-group comparisons by the Scheffé procedure, due to specimen 31P NMR profile variability, interpreted as arising from specimen biological variability. The phospholipid profiles of lenses preserved by acetone desiccation were essentially identical to those from the freshly excised control lenses. Freeze-dried lens profiles differed significantly in four components, while profiles from perchloric acid-extracted lenses differed in six. It is concluded that specimen preservation by acetone disiccation is a useful method for preserving tissue phospholipids for subsequent 31P NMR profile analysis, while freeze-drying is not. Lipid extraction following a tissue acid extraction is also of little or no value in the determination of tissue phospholipid profiles.     

Antiulcer activity of ethanolic extract of Encholirium spectabile Mart. ex Schult & Schult f. (Bromeliaceae) in rodents

This study evaluated the antiulcer activity of an ethanolic extract of Encholirium spectabile (ES-EtOH) by using different standard experimental models of induced acute gastric ulceration. ES-EtOH (100 mg/kg p.o) protected the gastric mucosa against ulceration that was induced by absolute ethanol (53%), ethanol/HCl (75%), ibuprofen (52 %) and ischemia/reperfusion (43 %). It also restored catalase activity and non-protein sulfhydryl group concentration in the gastric wall of mice that had been treated with ethanol. The pre-treatment of mice with N-nitro-L-arginine (70 mg/kg i.p.) abolished the protective activity of ES-EtOH, which indicates that prostaglandins, antioxidant compounds and nitric oxide synthase activity are involved in the gastroprotective activity of the extract.     

Is allometry of sexual traits adaptive? A field test with territorial damselflies

Recent studies have linked static allometry of sexual traits to selective advantages, in terms of sexual selection. An underlying, yet untested, assumption is that the allometry of sexual traits confers higher mating success and/or survival. Here, we investigated whether the allometry of two sexual traits is related to male mating success and survival in two species of damselflies: wing size in Paraphlebia zoe and the red‐pigmented wing spot in Hetaerina americana. We used large field‐based data sets of marked‐recaptured animals, in which we recorded male mating success and survival. Both sexual traits exhibited hyperallometric patterns; however, allometry was not linked to either mating success or survival. These results indicate that, at least during the period of sexual competition, allometry does not seem to be adaptive. Although our results may only apply to our damselfly study subjects (which nevertheless would require further tests in different seasons and/or study sites), our findings should encourage researchers to evaluate at least whether the assumed adaptiveness of sexual trait allometry holds for their study animals. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 327–334.     

Biochemical comparison of two Hypostomus populations (Siluriformes, Loricariidae) from the Atlântico Stream of the upper Paraná River basin, Brazil

Two syntopic morphotypes of the genus Hypostomus - H. nigromaculatus and H. cf. nigromaculatus (Atlantico Stream, Paraná State) - were compared through the allozyme electrophoresis technique. Twelve enzymatic systems (AAT, ADH, EST, GCDH, G3PDH, GPI, IDH, LDH, MDH, ME, PGM and SOD) were analyzed, attributing the score of 20 loci, with a total of 30 alleles. Six loci were diagnostic (Aat-2, Gcdh-1, Gpi-A, Idh-1, Ldh-A and Mdh-A), indicating the presence of interjacent reproductive isolation. The occurrence of few polymorphic loci acknowledge two morphotypes, with heterozygosity values He = 0.0291 for H. nigromaculatus and He = 0.0346 for H. cf. nigromaculatus. F(IS) statistics demonstrated fixation of the alleles in the two morphotypes. Genetic identity (I) and distance (D) of Nei (1978) values were I = 0.6515 and D = 0.4285. The data indicate that these two morphotypes from the Atlantico Stream belong to different species.     

Nurse species and indirect facilitation through grazing drive plant community functional traits in tropical alpine peatlands

Facilitation among plants mediated by grazers occurs when an unpalatable plant extends its protection against grazing to another plant. This type of indirect facilitation impacts species coexistence and ecosystem functioning in a large array of ecosystems worldwide. It has nonetheless generally been understudied so far in comparison with the role played by direct facilitation among plants. We aimed at providing original data on indirect facilitation at the community scale to determine the extent to which indirect facilitation mediated by grazers can shape plant communities. Such experimental data are expected to contribute to refining the conceptual framework on plant–plant–herbivore interactions in stressful environments. We set up a 2‐year grazing exclusion experiment in tropical alpine peatlands in Bolivia. Those ecosystems depend entirely on a few, structuring cushion‐forming plants (hereafter referred to as “nurse” species), in which associated plant communities develop. Fences have been set over two nurse species with different strategies to cope with grazing (direct vs. indirect defenses), which are expected to lead to different intensities of indirect facilitation for the associated communities. We collected functional traits which are known to vary according to grazing pressure (LDMC, leaf thickness, and maximum height), on both the nurse and their associated plant communities in grazed (and therefore indirect facilitation as well) and ungrazed conditions. We found that the effect of indirectly facilitated on the associated plant communities depended on the functional trait considered. Indirect facilitation decreased the effects of grazing on species relative abundance, mean LDMC, and the convergence of the maximum height distribution of the associated communities, but did not affect mean height or cover. The identity of the nurse species and grazing jointly affected the structure of the associated plant community through indirect facilitation. Our results together with the existing literature suggest that the “grazer–nurse–beneficiary” interaction module can be more complex than expected when evaluated in the field.     

Mechanical characterization of 3D printed mimic of human artery affected by atherosclerotic plaque through numerical and experimental methods

Biomechanics and Modeling in Mechanobiology - This paper proposes a novel experimental investigation based on 3D printing to validate numerical models for biomechanics simulations. Soft elastomeric...     

Characterization of a Leishmania stage‐specific mitochondrial membrane protein that enhances the activity of cytochrome c oxidase and its role in virulence

Leishmaniasis is caused by the dimorphic protozoan parasite Leishmania. Differentiation of the insect form, promastigotes, to the vertebrate form, amastigotes, and survival inside the vertebrate host accompanies a drastic metabolic shift. We describe a gene first identified in amastigotes that is essential for survival inside the host. Gene expression analysis identified a 27 kDa protein‐encoding gene (Ldp27) that was more abundantly expressed in amastigotes and metacyclic promastigotes than in procyclic promastigotes. Immunofluorescence and biochemical analysis revealed that Ldp27 is a mitochondrial membrane protein. Co‐immunoprecipitation using antibodies to the cytochrome c oxidase (COX) complex, present in the inner mitochondrial membrane, placed the p27 protein in the COX complex. Ldp27 gene‐deleted parasites (Ldp27^?/?) showed significantly less COX activity and ATP synthesis than wild type in intracellular amastigotes. Moreover, the Ldp27^?/? parasites were less virulent both in human macrophages and in BALB/c mice. These results demonstrate that Ldp27 is an important component of an active COX complex enhancing oxidative phosphorylation specifically in infectious metacyclics and amastigotes and promoting parasite survival in the host. Thus, Ldp27 can be explored as a potential drug target and parasites devoid of the p27 gene could be considered as a live attenuated vaccine candidate against visceral leishmaniasis.     

Micro-geographical variation among male populations of the sandfly, Lutzomyia (Nyssomyia) intermedia, from an endemic area of American cutaneous leishmaniasis in the state of Rio de Janeiro, Brazil

The genetic relationships among male Lutzomyia (Nyssomyia) intermedia (Lutz & Neiva) (Diptera: Psychodidae) from three populations from the same endemic area of American cutaneous leishmaniasis (ACL) in the state of Rio de Janeiro, Brazil, were compared. The sandflies were collected in three ecologically different habitats: domestic, extra-domestic and sylvatic over a total range of 800 m. Three molecular markers were employed to assess population variation. Based on MLEE markers, it could not be concluded that the three populations do not belong to the same gene pool (F(st) = 0.005). No within-population departure from Hardy-Weinberg equilibrium was detected (P < 0.05) and they presented the same level of gene variation. The number of migrants (Nm) indicated that at least 50 individuals per generation migrated between the three habitats. RAPD-PCR markers revealed that, except for the primer five, all were polymorphic. Phenetic analysis of the genotypes showed the presence of two principal clusters corresponding to: (1) domestic plus extra-domestic and (2) sylvatic. Unique genotypes were observed in each population. The sylvatic population was the most polymorphic, showing the largest number of genotypes and low level of similarity between them. Three mtDNA gene markers were studied by SSCP analysis. The most frequent haplotype for each marker ranged in frequency from 60 to 87% and individuals with unique haplotypes varied from 1 to 5%. Interestingly, the SSCP analysis showed a low level of polymorphism within populations. The disagreement between the different molecular markers observed and the hypothesis that L. intermedia could be participating in the transmission cycle of Leishmania (Viannia) braziliensis in environments ranging from the interior of human dwellings to the forest, are discussed.