Age-related alterations of enzyme activities and subunits of hepatic glutathione S-transferases in male and female Fischer-344 rats

Enzyme activities of glutathione S-transferases (GSTs) toward five different substrates (benzalacetone (PBO), styrene oxide (STOX), sulfobromophthalein (BSP), 1,2-dichloro-4-nitrobenzene (DCNB) and 1-chloro-2,4-dinitrobenzene (CDNB)) as well as concentrations of four subunits of GST isozymes (1, 2, 3 and 4) were determined using cytosol fractions obtained from livers of young (6 months) and old (26 months) Fischer-344 rats of both sexes. Values for enzyme activities for three substrates (DCNB, BSP and PBO) in young male rats were significantly higher than the corresponding values in female rats. In old male rats, values were generally lower than the corresponding values in young male rats, becoming close to corresponding values in young female rats. Old female rats, however, exhibited values close to those in young female rats, except for DCNB and STOX values, which were slightly lower in old female rats. GST subunits 3 and 4, as determined by high-performance liquid chromatography after purification by affinity chromatography using S-hexyl-glutathione, were predominant in young males, whereas concentrations of subunits 1 and 2 were higher in females than in males. In male rat livers, concentrations of subunits 3 and 4 decreased considerably with age while those of subunits 1 and 2 increased, so that the subunit pattern in old male rats tended to be similar to that of young female rats. In old females, a decrease in the concentration of subunits 3 and 4 and an increase in the concentration of subunit 1 were also observed as in old male rats, while the subunit 2 concentration tended to decline. Furthermore, the elution pattern of affinity chromatography changed with age, yielding an earlier elution of most subunits in old male rats and of subunit 1 in old female rats. The results suggest that age-related changes that occur with GSTs in livers of male rats are essentially a feminization of the isozyme pattern. However, despite rather unremarkable changes in enzyme activities with age in females, considerable changes of subunit pattern (a general decrease in concentration of subunits 2, 3 and 4 and an increase in the concentration of subunit 1) were also observed in female rats, and these were much greater than could be predicted from enzyme activity changes with age in this sex.     

Response of epilithic diatom communities to environmental gradients along an Ecuadorian Andean River

Epilithic diatom communities are particularly suitable for the evaluation of freshwater quality. In Ecuador, however, no water quality index includes this biotic parameter. This work is the first attempt in the country to determine the composition of epilithic diatom communities associated with different degrees of eutrophication. This was accomplished by measuring physical, chemical and microbiological variables at five sampling sites along the Pita River, Ecuador, from August to December 2016. The results indicate a clear gradient of eutrophication from sampling sites P1 (good water) in the upper reaches to P5 (bad water) located in the lower reaches. Concerning diatom analyses, the results indicated a high diversity for tropical areas in terms of species richness, varying from S = 34 in headwaters to S = 42 downstream. Moreover, the results obtained suggest a lack of concordance with the trophic values given to some of the epilithic diatoms in the literature. There were also species that seem to be sensitive to downstream nutrient increases that were not considered as bioindicators in previous studies. We concluded that the trophic values of diatom species available in the scientific literature are not directly applicable to their sites in the Pita River. Hence, it is necessary to establish a trophic diatom index for the Andean region of Ecuador.     

Morphometric and molecular differences among Calvertius tuberosus (Coleoptera: Curculionidae) populations associated with Andean and coastal populations of Araucaria araucana in the La Araucanía Region,Chile

Calvertius tuberosus (Curculionidae) lives exclusively on Araucaria araucana trees (commonly known as pehuen) in southern Chile. In this study, morphometric and molecular genetic analyses of Andean and coastal populations of C. tuberosus were performed to evaluate evolutionary divergence associated with the discontinuity of the Araucaria forest between the coastal and Andean regions. Specimens of C. tuberosus were collected in Nahuelbuta National Park, Villa Las Araucarias, and Malalcahuello National Reserve and were classified and stored at the Animal Biotechnology Researching Laboratory (LINBA), University of La Frontera, Temuco, Chile. Thirteen morphometric parameters and the expression patterns of ISSR (inter-simple sequence repeat) markers were analyzed. Morphometric data revealed high phenotypic similarity between coastal populations. The genetic analysis revealed a high similarity between coastal populations (genetic identity, 93%), which were differentiated from the Andean population (genetic identity, 84%). This study contributes new genotypic and phenotypic data for the C. tuberosus populations in forest ecosystems of A. araucana, and clarifies the associations between these characteristics and the geographic distributions of populations.     

Wearable slot antenna at 2.45 GHz for off‐body radiation: Analysis of efficiency,frequency shift,and body absorption

The interaction of body‐worn antennas with the human body causes a significant decrease in antenna efficiency and a shift in resonant frequency. A resonant slot in a small conductive box placed on the body has been shown to reduce these effects. The specific absorption rate is less than international health standards for most wearable antennas due to small transmitter power. This paper reports the linear relationship between power absorbed by biological tissues at different locations on the body and radiation efficiency based on numerical modeling (r = 0.99). While the ?10 dB bandwidth of the antenna remained constant and equal to 12.5%, the maximum frequency shift occurred when the antenna was close to the elbow (6.61%) and on the thigh (5.86%). The smallest change was found on the torso (4.21%). Participants with body‐mass index (BMI) between 17 and 29 kg/m² took part in experimental measurements, where the maximum frequency shift was 2.51%. Measurements showed better agreement with simulations on the upper arm. These experimental results demonstrate that the BMI for each individual had little effect on the performance of the antenna. Bioelectromagnetics. 39:25–34, 2018. © 2017 Wiley Periodicals, Inc.     

Linkage mapping of ‘25-kDa globulin’ genes on homoeologous group-1 chromosomes of bread and durum wheat

Acid polyacrylamide-gel electrophoresis (A-PAGE) of ethanol-soluble proteins from the endosperm of bread and durum wheats reveals some bands encoded by genes on the homoeologous group-1 chromosomes with higher mobility than the -gliadins. The isolation of these proteins showed that they were the previously described 25-kDa globulins encoded by genes at the Glo-A1, Glo-B1, and Glo-D1 loci. The variability found among a collection of 51 bread and 81 durum wheats was very low: two allelic variants at Glo-A1 and no variants at Glo-B1 in each of the two species, and two allelic variants at Glo-D1 in bread wheat. Inheritance studies of 25-kDa globulin genes on group-1 chromosomes of bread and durum wheat were carried out on the F₂ progeny from four crosses, two in bread wheat and two in durum wheat. The linkage mapping of the 1A 25-kDa globulin genes of bread wheat was done based on four prolamin loci: Glu-A1, Glu-A3, Gli-A1 and Gli -A3. The percentages of recombination and the distances found allowed a re-evaluation of the linkage map of endosperm protein loci on this chromosome. The Glo-A1 locus was found to be located at the distal end of the short arm of 1A chromosome, at a distance of 5.23±1.99 cM from Gli-A1, 6.85±2.22 cM from Glu-A3, 22.64±3.62 cM from Gli-A1, and at a recombination percentage of 49.30±4.40 from Glu-A1. A similar distance between Gli-A1 and Glo-A1 (4.82±1.75 and 6.66±2.26 cM) was found in durum wheat. The distance between Gli-D1 and Glo-D1 on chromosome 1D was 2.86±1.39 cM.     

Analysis of an autonomous phase model for neuronal parabolic bursting

An understanding of the nonlinear dynamics of bursting is fundamental in unraveling structure-function relations in nerve and secretory tissue. Bursting is characterized by alternations between phases of rapid spiking and slowly varying potential. A simple phase model is developed to study endogenous parabolic bursting, a class of burst activity observed experimentally in excitable membrane. The phase model is motivated by Rinzel and Lee's dissection of a model for neuronal parabolic bursting (J. Math. Biol. 25, 653–675 (1987)). Rapid spiking is represented canonically by a one-variable phase equation that is coupled bi-directionally to a two-variable slow system. The model is analyzed in the slow-variable phase plane, using quasi steady-state assumptions and formal averaging. We derive a reduced system to explore where the full model exhibits bursting, steady-states, continuous and modulated spiking. The relative speed of activation and inactivation of the slow variables strongly influences the burst pattern as well as other dynamics. We find conditions of the bistability of solutions between continuous spiking and bursting. Although the phase model is simple, we demonstrate that it captures many dynamical features of more complex biophysical models.This research was partially supported by NSF-JOINT RESEARCH grant 8803573, grant from CONCYT and DGAPA(UNAM) Mexico for H. Carrillo, and for the S. M. Baer NSF DMS-9107538     

The Natural History of Kidney Graft Cortical Microcirculation Determined by Real-Time Contrast-Enhanced Sonography (RT-CES)

Background

Kidney transplantation is the therapy of choice for end-stage kidney disease. Graft’s life span is shorter than expected due in part to the delayed diagnosis of various complications, specifically those related to silent progression. It is recognized that serum creatinine levels and proteinuria are poor markers of mild kidney lesions, which results in delayed clinical information. There are many investigation looking for early markers of graft damage. Decreasing kidney graft cortical microcirculation has been related to poor prognosis in kidney transplantation. Cortical capillary blood flow (CCBF) can be measured by real-time contrast-enhanced sonography (RT-CES). Our aim was to describe the natural history of CCBF over time under diverse conditions of kidney transplantation, to explore the influence of donor conditions and recipient events, and to determine the capacity of CCBF for predicting renal function in medium term.

Patients and Methods

RT-CES was performed in 79 consecutive kidney transplant recipients during the first year under regular clinical practice. Cortical capillary blood flow was measured. Clinical variables were analyzed. The influence of CCBF has been determined by univariate and multivariate analysis using mixed regression models based on sequential measurements for each patient over time. We used a first-order autoregression model as the structure of the covariation between measures. The post-hoc comparisons were considered using the Bonferroni correction.

Results

The CCBF values varied significantly over the study periods and were significantly lower at 48 h and day 7. Brain-death donor age and CCBF levels showed an inverse relationship (r: -0.62, p<0.001). Living donors showed higher mean CCBF levels than brain-death donors at each point in the study. These significant differences persisted at month 12 (54.5 ± 28.2 vs 33.7 ± 30 dB/sec, living vs brain-death donor, respectively, p = 0.004) despite similar serum creatinine levels (1.5 ± 0.3 and 1.5 ± 0.5 mg/dL). A sole rejection episode was associated with lower overall CCBF values over the first year. CCBF defined better than level of serum creatinine the graft function status at medium-term.

Conclusion

RT-CES is a non-invasive tool that can quantify and iteratively estimate cortical microcirculation. We have described the natural history of cortical capillary blood flow under regular clinical conditions.     

Influence of Snowmelt Timing on the Diet Quality of Pyrenean Rock Ptarmigan (Lagopus muta pyrenaica): Implications for Reproductive Success

The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) is the southernmost subspecies of the species in Europe and is considered threatened as a consequence of changes in landscape, human pressure, climate change, and low genetic diversity. Previous studies have shown a relationship between the date of snowmelt and reproductive success in the Pyrenean ptarmigan. It is well established that birds laying early in the breeding season have higher reproductive success, but the specific mechanism for this relationship is debated. We present an explicative model of the relationship between snowmelt date and breeding success mediated by food quality for grouse in alpine environments. From microhistological analyses of 121 faecal samples collected during three years in the Canigou Massif (Eastern Pyrenees), and the assessment of the chemical composition of the main dietary components, we estimated the potential quality of individual diets. Potential dietary quality was correlated with free-urate faecal N, a proxy of the digestible protein content ingested by ptarmigan, and both were correlated with phenological stage of consumed plants, which in turn depends on snowmelt date. Our findings suggest that the average snowmelt date is subject to a strong interannual variability influencing laying date. In years of early snowmelt, hens benefit from a longer period of high quality food resources potentially leading to a higher breeding success. On the contrary, in years of late snowmelt, hens begin their breeding period in poorer nutrient condition because the peaks of protein content of their main food items are delayed with respect to laying date, hence reducing breeding performance. We discuss the possible mismatch between breeding and snowmelt timing.