Photoreactivation of superoxide dismutase by intensive red (laser) light

The effects of helium-neon laser (HNL) on activity, absorption spectra, and ESR signals of superoxide dismutase (SOD; E Cul. 15.1.1) from bovine erythrocytes in acid medium were investigated. It was found that incubation during 2 hours at pH 5.9 led to inactivation of the enzyme. The subsequent illumination of SOD by HNL brought about the enzyme reactivation. Both absorption and ESR spectra were changed after incubation at pH 5.9 and restored after laser irradiation. In a model system, copper-histidine complex, absorption maximum was shifted from 632–633 nm at pH 5.8 to 639–640 nm at pH 8.5–9.0. The similar shift of the maximum was observed after illumination by HNL at pH 5.8. It may be postulated that the photoreactivation of SOD consists essentially in deprotonation of His-61 residue in the enzyme active site and subsequent recovery of imidasol bridge between copper and zinc which had been destroyed at low pH.

Since many other enzymes possess similar histidine-copper structures in their active sites, one may expect diverse effects of red (laser) light on the enzyme activity. Heme-containing enzyme, catalase was also found to be photoreactivated by HNL after inactivation at pH 6.0.     

Simultaneous determination of Fe(III) and Fe(II) in water solutions and tissue homogenates using desferal and 1,10-phenanthroline

At neutral pH values 1,10-phenanthroline forms a colored complex with Fe(II), but it does not form such a complex with Fe(III). On the contrary, only Fe(III) forms with desferal a yellow complex with a g = 4.3 electron paramagnetic resonance (EPR) signal, but Fe(II) is rapidly oxidized by desferal to Fe(III), which gives then a yellow complex. On the basis of these facts, a method for simultaneous determination of both Fe(II) and Fe(III) ions was elaborated using a desferal-phenanthroline mixture. Two ways of detecting Fe(II) and Fe(III) have been suggested: (1) the spectrophotometric method for transparent water solutions, and (2) the EPR-spectrometric method for turbid solutions and tissue homogenates. The latter method was applied for determination of free and weakly bound iron in rat liver. The Fe(II) amount in intact liver was 22.2 ± 7.6 nmol/g of wet tissue; free Fe(III) was not found.     

Use of NMR metabolomics to analyze the targets of D-cycloserine in mycobacteria: role of D-alanine racemase

D-Cycloserine (DCS) is only used with multidrug-resistant strains of tuberculosis because of serious side effects. DCS is known to inhibit cell wall biosynthesis, but the in vivo lethal target is still unknown. We have applied NMR-based metabolomics combined with principal component analysis to monitor the in vivo effect of DCS on Mycobacterium smegmatis. Our analysis suggests DCS functions by inhibiting multiple protein targets.     

Genetic diversity within and among two Argentinean and one Mexican species of Acacia (Fabaceae)

Acacia is a pantropical genus comprising > 1450 species. Following Vassal's treatment Acacia is considered as a single genus with three subgenera (Acacia, Aculeiferum and Phyllodineae). Acacia caven, A. curvifructa and A. farnesiana belong to subgenus Acacia and the relationship between them is controversial. The aim of this study was to elucidate the relationship between the three species using amplified fragment length polymorphism, analysing 15 populations of these species, and to compare the results obtained with those from a morphological analysis. Genetic diversity indices (percentage of polymorphic loci, genetic diversity) showed that genetic variation in A. caven is higher than that in A. curvifructa and A. farnesiana. Of the total genetic diversity in A. caven and A. farnesiana, most is found within populations (∼70%). Analysis with STRUCTURE showed that the optimal number of clusters (K) was ten, and in all cases where populations were grouped they were geographically close and/or belong to the same variety. The morphological canonical discriminant analysis did not result in a separation between all individuals, indicating that they do not harbour consistent morphological discontinuities. Altogether, the results of our molecular analyses showed the existence of significant differences between A. caven, A. curvifructa and A. farnesiana, which argues for recognizing them as different species. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 593–606.     

Do assortative mating and immigrant inviability help maintain population genetic structuring of an herbivore on a crop and a wild relative?

Population genetic structuring is common among herbivorous insects and frequently is associated with divergent host plants, such as crops and their wild relatives. Previous studies showed population genetic structuring in corn leafhopper Dulbulus maidis in Mexico, such that the species consists of two sympatric, host plant-associated populations: an abundant and widespread "pestiferous” population on maize (Zea mays mays), and a small and localized "wild" population on perennial teosinte (Zea diploperennis). a maize wild relative with a limited distribution. This study addressed whether assortative mating and immigrant inviability mediate genetic structuring of corn leafliopper by comparing the mating and reproductive successes of pestiferous and wild females that colonize their nonassociated host plants against the successes of females colonizing their associated host plants. Assortative mating was assessed by comparing mating frequencies and premating and mating times among females of each population on each host plant: immigrant inviability was assessed by comparing, across two generations, the fecundity, survival, development time, sex ratio, and population growth rate among leafhopper populations and host plants. Our results showed that on maize, and compared to resident, pestiferous females, wild females were more likely to mate, and greater proportions of their offspring survived to adult stage and were daughters;consequently, the per-generation population growth rate on maize was greater for immigrant, wild leafhoppers compared to resident, pestiferous leafhoppers. Our results suggested that wild leafhoppers emigrating to maize have a fitness advantage over resident, pestiferous leafhoppers, while immigrant pestiferous and resident wild leafhoppers on teosinte have similar fitnesses.     

Selective predation by crevalle jack <Emphasis Type="Italic">Caranx caninus</Emphasis> on engraulid fishes in the SE Gulf of California,Mexico

Feeding habits determine many aspects of living organisms, where it lives, the time of day that it is active, energy flow, biomass consumed and intra- and interspecific interactions, it which provides information to make predictions about the effects of fisheries on predator-prey relationships. Accurate predictions require a thorough understanding of predator diets and prey selection. In this study, specimens of the crevalle jack Caranx caninus were obtained between October 2012 and October 2014 in the SE Gulf of California, Mexico, in order to determine its feeding habits and prey selection. A total of 238 specimens were obtained, of which 94 (39.5%) had stomachs containing food and 144 (60.5%) had empty stomachs. A total of 10 prey items were identified, corresponding to seven families that included fishes, crustaceans and cephalopods. According to the Index of Relative Importance (IRI) the most important prey were Anchoa spp. (IRI = 91.2%), Engraulis mordax (IRI = 1.8%), and fish from the Clupeidae family (IRI = 1.0%). The crevalle jack’s diet did not change with the season (warm or cold). The crevalle jack was considered a tertiary predator (trophic level = 4.3) that tends to feed on a reduced number of prey, characterizing it as a specialist and selective predator of engraulid fishes (Levin’s index, Bi = 0.08; E = 0.6).     

Mfn2 localization in the ER is necessary for its bioenergetic function and neuritic development

Mfn2 is a mitochondrial fusion protein with bioenergetic functions implicated in the pathophysiology of neuronal and metabolic disorders. Understanding the bioenergetic mechanism of Mfn2 may aid in designing therapeutic approaches for these disorders. Here we show using endoplasmic reticulum (ER) or mitochondria‐targeted Mfn2 that Mfn2 stimulation of the mitochondrial metabolism requires its localization in the ER, which is independent of its fusion function. ER‐located Mfn2 interacts with mitochondrial Mfn1/2 to tether the ER and mitochondria together, allowing Ca²⁺ transfer from the ER to mitochondria to enhance mitochondrial bioenergetics. The physiological relevance of these findings is shown during neurite outgrowth, when there is an increase in Mfn2‐dependent ER‐mitochondria contact that is necessary for correct neuronal arbor growth. Reduced neuritic growth in Mfn2 KO neurons is recovered by the expression of ER‐targeted Mfn2 or an artificial ER‐mitochondria tether, indicating that manipulation of ER‐mitochondria contacts could be used to treat pathologic conditions involving Mfn2.     

Histological and histochemical study of the duodenum of the plains viscacha (Lagostomus maximus) at different stages of its ontogenetic development

The general objective of this study focused on the duodenal histological and histochemical analysis of fetuses and adults of plains viscacha (Lagostomus maximus) from the Buenos Aires province (Argentina). Histological techniques, histochemical procedures for localizing and characterizing glycoproteins (GPs) and lectin histochemical techniques for the identification of specific sugar residues were used. The duodenal structure of all age groups here considered was typical of mammals. We identified a proliferation phase and an epithelial morphogenesis in mid‐gestational fetuses, an intermediate period of cell differentiation in at‐term fetuses and a posterior stage of physiological maturation in adults. According to histochemistry, the diverse GPs elaborated and secreted into the duodenum show a high degree of histochemical complexity related to the multiple functions of mucus in the digestive tract. The GPs in the duodenum of L. maximus and their glycosylation patterns varied according to the animal's age and the developmental state of the organ.     

A new species of Tzeltalia (Solanaceae) from Mexico

A new species of Tzeltalia (Solanaceae) from Chiapas, Mexico is described and illustrated: Tzeltalia esenbeckii. A key and a table, distinguishing the members of the genus, are included.     

Dietary n-3 polyunsaturated fatty acids modify fatty acid composition in hepatic and abdominal adipose tissue of sucrose-induced obese rats

The fatty acid profile of hepatocytes and adipocytes is determined by the composition of the dietary lipids. It remains unclear which fatty acid components contribute to the development or reduction of insulin resistance. The present work examined the fatty acid composition of both tissues in sucrose-induced obese rats receiving fish oil to determine whether the effect of dietary (n-3) polyunsaturated fatty acids (PUFAs) on the reversion of metabolic syndrome in these rats is associated to changes in the fatty acid composition of hepatocyte and adipocyte membrane lipids. Animals with metabolic syndrome were divided into a corn–canola oil diet group and a fish oil diet group, and tissues fatty acids composition were analyzed after 6 weeks of dietary treatment. Fatty acid profiles of the total membrane lipids were modified by the fatty acid composition of the diets fed to rats. N-3 PUFAs levels in animals receiving the fish oil diet plus sucrose in drinking water were significantly higher than in animals under corn–canola oil diets. It is concluded that in sucrose-induced obese rats, consumption of dietary fish oil had beneficial effects on the metabolic syndrome and that such effects would be conditioned by the changes in the n-3 PUFAs composition in hepatic and adipose tissues because they alter membrane properties and modify the type of substrates available for the production of active lipid metabolites acting on insulin resistance and obesity.