Do Seasonal Glucocorticoid Changes Depend on Reproductive Investment? A Comparative Approach in Birds

Animals go through different life history stages such as reproduction, moult, or migration, of which some are more energy-demanding than others. Baseline concentrations of glucocorticoid hormones increase during moderate, predictable challenges and thus are expected to be higher when seasonal energy demands increase, such as during reproduction. By contrast, stress-induced glucocorticoids prioritize a survival mode that includes reproductive inhibition. Thus, many species down-regulate stress-induced glucocorticoid concentrations during the breeding season. Interspecific variation in glucocorticoid levels during reproduction has been successfully mapped onto reproductive investment, with species investing strongly in current reproduction (fast pace of life) showing higher baseline and lower stress-induced glucocorticoid concentrations than species that prioritize future reproduction over current attempts (slow pace of life). Here we test the >glucocorticoid seasonal plasticity hypothesis>, in which we propose that interspecific variation in seasonal changes in glucocorticoid concentrations from the non-breeding to the breeding season will be related to the degree of reproductive investment (and thus pace of life). We extracted population means for baseline (for 54 species) and stress-induced glucocorticoids (for 32 species) for the breeding and the non-breeding seasons from the database >HormoneBase>, also calculating seasonal glucocorticoid changes. We focused on birds because this group offered the largest sample size. Using phylogenetic comparative methods, we first showed that species differed consistently in both average glucocorticoid concentrations and their changes between the two seasons, while controlling for sex, latitude, and hemisphere. Second, as predicted seasonal changes in baseline glucocorticoids were explained by clutch size (our proxy for reproductive investment), with species laying larger clutches showing a greater increase during the breeding season-especially in passerine species. In contrast, changes in seasonal stress-induced levels were not explained by clutch size, but sample sizes were more limited. Our findings highlight that seasonal changes in baseline glucocorticoids are associated with a species' reproductive investment, representing an overlooked physiological trait that may underlie the pace of life

Monthly sunspot number time series analysis and its modeling through autoregressive artificial neural network

This study reports a statistical analysis of monthly sunspot number time series and observes non homogeneity and asymmetry within it. Using Mann-Kendall test a linear trend is revealed. After identifying stationarity within the time series we generate autoregressive AR(p) and autoregressive moving average (ARMA(p,q)). Based on minimization of AIC we find 3 and 1 as the best values of p and q respectively. In the next phase, autoregressive neural network (AR-NN(3)) is generated by training a generalized feedforward neural network (GFNN). Assessing the model performances by means of Willmott's index of second order and coefficient of determination, the performance of AR-NN(3) is identified to be better than AR(3) and ARMA(3,1).Comment: 17 pages, 4 figure

Pseudorabies Virus Infection Alters Neuronal Activity and Connectivity In Vitro

Alpha-herpesviruses, including human herpes simplex virus 1 & 2, varicella zoster virus and the swine pseudorabies virus (PRV), infect the peripheral nervous system of their hosts. Symptoms of infection often include itching, numbness, or pain indicative of altered neurological function. To determine if there is an in vitro electrophysiological correlate to these characteristic in vivo symptoms, we infected cultured rat sympathetic neurons with well-characterized strains of PRV known to produce virulent or attenuated symptoms in animals. Whole-cell patch clamp recordings were made at various times after infection. By 8 hours of infection with virulent PRV, action potential (AP) firing rates increased substantially and were accompanied by hyperpolarized resting membrane potentials and spikelet-like events. Coincident with the increase in AP firing rate, adjacent neurons exhibited coupled firing events, first with AP-spikelets and later with near identical resting membrane potentials and AP firing. Small fusion pores between adjacent cell bodies formed early after infection as demonstrated by transfer of the low molecular weight dye, Lucifer Yellow. Later, larger pores formed as demonstrated by transfer of high molecular weight Texas red-dextran conjugates between infected cells. Further evidence for viral-induced fusion pores was obtained by infecting neurons with a viral mutant defective for glycoprotein B, a component of the viral membrane fusion complex. These infected neurons were essentially identical to mock infected neurons: no increased AP firing, no spikelet-like events, and no electrical or dye transfer. Infection with PRV Bartha, an attenuated circuit-tracing strain delayed, but did not eliminate the increased neuronal activity and coupling events. We suggest that formation of fusion pores between infected neurons results in electrical coupling and elevated firing rates, and that these processes may contribute to the altered neural function seen in PRV-infected animals

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Modulation of Antigen Expression in B-Cell Precursor Acute Lymphoblastic Leukemia During Induction Therapy is Partly Transient: Evidence for a Drug-Induced Regulatory Phenomenon. Results of the AIEOP-BFM-ALL-FLOW-MRD-Study Group

BACKGROUND: Changes of antigen expression on residual blast cells of acute lymphoblastic leukemia (ALL) occur during induction treatment. Many markers used for phenotyping and minimal residual disease (MRD) monitoring are affected. Glucocorticoid (GC)-induced expression modulation has been causally suspected, however, subclone selection may also cause the phenomenon. METHODS: We investigated this by following the phenotypic evolution of leukemic cells with flow cytometry from diagnosis to four time points during and after GC containing chemotherapy in the 20 (of 360 consecutive) B-cell precursor patients with ALL who had persistent MRD throughout. RESULTS: The early expression changes of CD10 and CD34 were reversible after stop of GC containing chemotherapy. Modulation of CD20 and CD45 occurred mostly during the GC phase, whereas CD11a also changed later on. Blast cells at diagnosis falling into gates designed according to "shifted" phenotypes from follow-up did not form clusters and were frequently less numerous than later on. CONCLUSIONS: Our data support the idea that drug-induced modulation rather than selection causes the phenomenon. The good message for MRD assessment is that modulation is transient in at least two (CD10 and CD34) of the five prominent antigens investigated and reverts to initial aberrant patterns after stop of GC therapy, whereas CD20 expression gains new aberrations exploitable for MRD detection

Standardization of Flow Cytometric Minimal Residual Disease Evaluation in Acute Lymphoblastic Leukemia: Multicentric Assessment Is Feasible

BACKGROUND: Single-laboratory experience showed that flow cytometric (FCM) assessment of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL) is feasible in most patients and gives independent prognostic information. It is, however, not known whether FCM analysis can reliably be standardized for multicentric application. METHODS: An extensive standardization program was installed in four collaborating laboratories, which study FCM-MRD in children treated with the AIEOP-BFM-ALL 2000 protocol. This included methodological alignment, continuous quality monitoring, as well as personnel education by exchange and performance feed-back. RESULTS: Blinded inter-laboratory tests of list-mode data interpretation concordance (n = 202 blood and bone marrow samples from follow-up during induction of 31 randomly selected patients of a total series of n = 395) showed a very high degree of inter-rater agreement among the four centers despite differences in cytometers and software usage (intraclass correlation coefficient [ICC] 0.979 based on n= 800 single values). Lower concordance was reached with amounts of MRD below 0.1%. Comparing data from sample exchange experiments (n = 42 samples; ICC 0.98) and from independent patient cohorts from the four centers (regarding positive samples per time-point of follow-up as well as risk estimates) concordance was also good

Oxidative stress responses in blood and gills of Carassius auratus exposed to the mancozeb-containing carbamate fungicide Tattoo

Intensive use of pesticides, particularly dithiocarbamates, in agriculture often leads to contamination of freshwater ecosystems. To our knowledge, the mechanisms of toxicity to fish by the carbamate fungicide Tattoo that contains mancozeb [ethylenebis(dithiocarbamate)] have not been studied. The present study aimed to evaluate the effects of Tattoo on goldfish gills and blood, tissues that would have close early contact with the pollutant. Exposure of goldfish Carassius auratus to 3, 5 or 10mgL-1 of Tattoo for 96h resulted in moderate lymphopenia (by 8 percent) with a concomitant increase in both stab (by 66-88 percent) and segmented (by 166 percent) neutrophils. An increase in the content of protein carbonyl groups in blood (by 137-184 percent) together with decreased levels of protein thiols (by 23 percent) and an enhancement of lipid peroxide concentrations (by 29 percent) in gills after exposure to 10mgL-1 of Tattoo demonstrated the induction of mild oxidative stress in response to Tattoo exposure. At the same time, the activities of selected antioxidant enzymes were enhanced in gills: superoxide dismutase by 18-25 percent and catalase by 27 percent. A 34 percent increment in low molecular mass thiol concentrations (mainly represented by glutathione) also occurred in gills and could be related to increased activity (by 13-30 percent) of glucose-6-phosphate dehydrogenase. The results indicate that Tattoo exposure perturbs free radical processes, i.e. induces mild oxidative stress and enhances the activity of certain antioxidant and associated enzymes in goldfish gills. It is clear that goldfish respond to the presence of waterborne pesticide by adjusting antioxidant defenses through upregulation of activities of antioxidant and associated enzymes

Species-Specific Means and Within-Species Variance in Glucocorticoid Hormones and Speciation Rates in Birds

At macroevolutionary scales, stress physiology may have consequences for species diversification and subspecies richness. Populations that exploit new resources or undergo range expansion should cope with new environmental challenges, which could favor higher mean stress responses. Within-species variation in the stress response may also play a role in mediating the speciation process: in species with broad variation, there will always be some individuals that can tolerate an unpredictable environment, whereas in species with narrow variation there will be fewer individuals that are able to thrive in a new ecological niche. We tested for the evolutionary relationship between stress response, speciation rate, and subspecies richness in birds by relying on the HormoneBase repository, from which we calculated within- and among-species variation in baseline (BL) and stress-induced (SI) corticosterone levels. To estimate speciation rates, we applied Bayesian analysis of macroevolutionary mixtures that can account for variation in diversification rate among clades and through time. Contrary to our predictions, lineages with higher diversification rates were not characterized by higher BL or SI levels of corticosterone either at the tips or at the deeper nodes of the phylogeny. We also found no association between mean hormone levels and subspecies richness. Within-species variance in corticosterone levels showed close to zero repeatability, thus it is highly unlikely that this is a species-specific trait that influences diversification rates. These results imply that stress physiology may play a minor, if any, role in determining speciation rates in birds

Spatial disaggregation and intensity correction of TRMM-based rainfall time series for hydrological applications in dryland catchments

A novel approach is presented for combining spatial and temporal detail from newly available TRMM-based data sets to derive hourly rainfall intensities at 1-km spatial resolution for hydrological modelling applications. Time series of rainfall intensities derived from 3-hourly 0.25° TRMM 3B42 data are merged with a 1-km gridded rainfall climatology based on TRMM 2B31 data to account for the sub-grid spatial distribution of rainfall intensities within coarse-scale 0.25° grid cells. The method is implemented for two dryland catchments in Tunisia and Senegal, and validated against gauge data. The outcomes of the validation show that the spatially disaggregated and intensity corrected TRMM time series more closely approximate ground-based measurements than non-corrected data. The method introduced here enables the generation of rainfall intensity time series with realistic temporal and spatial detail for dynamic modelling of runoff and infiltration processes that are especially important to water resource management in arid regions