Boosting life sciences research in Brazil: building a case for a local Drosophila stock center

Drosophila melanogaster is undoubtedly one of the most useful model organisms in biology. Initially used in solidifying the principles of heredity, and establishing the basic concepts of population genetics and of the synthetic theory of evolution, it can currently offer scientists much more: the possibility of investigating a plethora of cellular and biological mechanisms, from development and function of the immune system to animal neurogenesis, tumorigenesis and beyond. Extensive resources are available for the community of Drosophila researchers worldwide, including an ever-growing number of mutant, transgenic and genomically-edited lines currently carried by stock centers in North America, Europe and Asia. Here, we provide evidence for the importance of stock centers in sustaining the substantial increase in the output of Drosophila research worldwide in recent decades. We also discuss the challenges that Brazilian Drosophila scientists face to keep their research projects internationally competitive, and argue that difficulties in importing fly lines from international stock centers have significantly stalled the progression of all Drosophila research areas in the country. Establishing a local stock center might be the first step towards building a strong local Drosophila community that will likely contribute to all areas of life sciences research.

Responsible Science Assessment: downplaying indexes, boosting quality

Scientists are facing enormous pressures posed by growing scientific communities and stagnant/reduced funding. In this scenario, mechanisms of knowledge achievement and management, as well as how recruitment, progression and evaluation are carried out should be reevaluated. We argue here that knowledge has become a profitable commodity and, as a consequence, excessive academic quantification, individual output assessment problems and abusive editorial market strategies have reached unsustainable levels. We propose to reinforce existing guidelines and to establish new ones to overcome these issues. Our proposal, the Initiative for Responsible Scientific Assessment (IRSA), has the main goal to strengthen and expand previous movements in the scientific community to promote higher quality research assessment, focused on better Science.

Clinical Frailty Scale: Translation and Cultural Adaptation into the Brazilian Portuguese Language

BACKGROUND

Frailty is a biological syndrome that causes adverse events in the health of older adults. However, the Clinical Frailty Scale has not yet been culturally adapted and validated into Brazilian Portuguese language.

OBJECTIVES

Our aim was to translate, reproduce and validate the Clinical Frailty Scale (CFS) for the Brazilian Portuguese language.

DESIGN

An observational cross-sectional study with senior patients was conducted between Jan 2018 and Nov 2018.

SETTING AND PARTICIPANTS

Volunteers aged >60 and living in Brazil. The translation and cultural adaptation of the CFS into the Portuguese language, the principles and good practices were followed.

MEASUREMENTS

To conduct the validation and determine the reproducibility of an inter-observer evaluation, the patients answered the scale questions in Portuguese on two occasions, delivered by two separate examiners and separated by a 10-minute interval, on their first visit; the 36-item Short Form Survey quality-of-life questionnaire (SF-36) was also applied. Seven days later, a second visit was undertaken to perform an intra-observer reproducibility assessment.

RESULTS

A total of 66 older individuals were enrolled (72 ± 8 years), the majority of which did not present frailty (63.6%) and reported a low physical limitation level in the SF-36. The CFS showed a significant correlation with the SF-36 quality-of-life questionnaire (r= -0.663; p<0.0001) and no statistical difference was observed between intra-rater (p=0.641) and inter-rater (p=0.350) applications, demonstrating the reproducibility and applicability of the instrument. The standard error estimate (SEE) was evaluated and there were no differences between the CFS and the SF-36 (SEE= 1.13 points).

CONCLUSION

The Brazilian Portuguese language version of the CFS is a valid, reproducible and reliable instrument for evaluating the impact of frailty on the lives of senior patients.

Steroidogenesis during prenatal testicular development in Spix's cavy Galea spixii

Spix's cavy is a potentially good experimental model for research on reproductive biology and sexual development. The aim of the present study was to evaluate the ontogeny of the steroidogenic enzymes involved in testicular androgen synthesis during prenatal development. Testes were investigated on Days 25, 30, 40 and >50 of gestation. Immunohistochemistry and immunoblotting were used to establish the site and relative amount of androgenic enzymes, including 5α-reductase, cytosolic 17β-hydroxysteroid dehydrogenase (17β-HSDI) and mitochondrial microsomal 3β-hydroxysteroid dehydrogenase (3β-HSDII), throughout prenatal development. The testicular parenchyma began to organise on Day 25 of gestation, with the development of recognisable testicular cords. The mesonephros was established after Day 25 of gestation and the ducts differentiated to form the epididymis, as testicular cords were beginning to proliferate and the interstitium to organise by Day 30 of gestation, continuing thereafter. The androgen-synthesising enzymes 5α-reductase, 17β-HSDI and 3β-HSDII were evident in Leydig cells as they differentiated at all subsequent gestational ages studied. In addition, immunoblotting showed an increase in immunoreactivity for the enzymes at Days 30 and 40 of gestation (P<0.05) and a decrease at Day 50 of gestation (P<0.05). It is concluded that the increase in androgenic enzymes in Leydig cells coincides with the functional differentiation of the testes, and with the stabilisation and differentiation of mesonephric ducts forming the epididymis.

Mechanical Permeabilization as a New Method for Assessment of Mitochondrial Function in Insect Tissues

Respirometry analysis is an effective technique to assess mitochondrial physiology. Insects are valuable biochemical models to understand metabolism and human diseases. Insect flight muscle and brain have been extensively used to explore mitochondrial function due to dissection feasibility and the low sample effort to allow oxygen consumption measurements. However, adequate plasma membrane permeabilization is required for substrates/modulators to reach mitochondria. Here, we describe a new method for study of mitochondrial physiology in insect tissues based on mechanical permeabilization as a fast and reliable method that do not require the use of detergents for chemical permeabilization of plasma membrane, while preserves mitochondrial integrity.

Assessment of mitochondrial physiology of murine white adipose tissue by mechanical permeabilization and lipid depletion

White adipose tissue (WAT) represents a major site of triacylglycerol energy storage and is directly associated with metabolic disorders. Mitochondria regulate cellular energy expenditure and are active in WAT. Although isolated mitochondria have been classically used to assess their functions, several artifacts can be introduced by this approach. Furthermore, important limitations exist in the available methods to determine mitochondrial physiology in permeabilized WAT. Here, we established and validated a method for functional evaluation of mice mesenteric WAT (mWAT) mitochondria by using MEchanical Permeabilization and LIpid DEpletion (MEPLIDE) coupled to high-resolution respirometry. We observed that mild stirring of mWAT for 20 min at room temperature with 4% fatty acid-free albumin (FAF-BSA) followed by 50 min without FAF-BSA selectively permeabilized white adipocytes plasma membrane. In these conditions, mWAT mitochondria were intact, exhibiting succinate-induced respiratory rates that were sensitive to classical oxidative phosphorylation modulators. Finally, the respiratory capacity of mWAT in female mice was significantly higher than in males, an observation that agrees with reported data. Therefore, the functional assessment of mWAT mitochondria through MEPLIDE coupled to high resolution respirometry proposed here will contribute to a better understanding of WAT biology in several pathophysiological contexts.

Blocking mitochondrial pyruvate import in brown adipocytes induces energy wasting via lipid cycling

Combined fatty acid esterification and lipolysis, termed lipid cycling, is an ATP‐consuming process that contributes to energy expenditure. Therefore, interventions that stimulate energy expenditure through lipid cycling are of great interest. Here we find that pharmacological and genetic inhibition of the mitochondrial pyruvate carrier (MPC) in brown adipocytes activates lipid cycling and energy expenditure, even in the absence of adrenergic stimulation. We show that the resulting increase in ATP demand elevates mitochondrial respiration coupled to ATP synthesis and fueled by lipid oxidation. We identify that glutamine consumption and the Malate‐Aspartate Shuttle are required for the increase in Energy Expenditure induced by MPC inhibition in Brown Adipocytes (MAShEEBA). We thus demonstrate that energy expenditure through enhanced lipid cycling can be activated in brown adipocytes by decreasing mitochondrial pyruvate availability. We present a new mechanism to increase energy expenditure and fat oxidation in brown adipocytes, which does not require adrenergic stimulation of mitochondrial uncoupling.

A simple and reliable method for longitudinal assessment of untethered mosquito induced flight activity

Aedes aegypti adult females are key vectors of several arboviruses and flight activity plays a central role in mosquito biology and disease transmission. Available methods to quantify mosquito flight usually require special devices and mostly assess spontaneous locomotor activity at individual level. Here, we developed a new method to determine longitudinal untethered adult A. aegypti induced flight activity: the INduced FLight Activity TEst (INFLATE). This method was an adaptation of the "rapid iterative negative geotaxis" assay to assess locomotor activity in Drosophila and explore the spontaneous behavior of mosquitoes to fly following a physical stimulus. Insects were placed on a plastic cage previously divided in four vertical quadrants and flight performance was carried out by tapping cages towards the laboratory bench. After one minute, the number of insects per quadrant was registered by visual inspection and categorized in five different scores. By using INFLATE, we observed that flight performance was not influenced by repeated testing, sex or 5% ethanol intake. However, induced flight activity was strongly affected by aging, blood meal and inhibition of mitochondrial complex I. This simple and rapid method allows the longitudinal assessment of induced flight activity of multiple untethered mosquitoes and may contribute to a better understanding of A. aegypti dispersal biology.

NCLX prevents cell death during adrenergic activation of the brown adipose tissue

A sharp increase in mitochondrial Ca2+ marks the activation of brown adipose tissue (BAT) thermogenesis, yet the mechanisms preventing Ca2+ deleterious effects are poorly understood. Here, we show that adrenergic stimulation of BAT activates a PKA-dependent mitochondrial Ca2+ extrusion via the mitochondrial Na+/Ca2+ exchanger, NCLX. Adrenergic stimulation of NCLX-null brown adipocytes (BA) induces a profound mitochondrial Ca2+ overload and impaired uncoupled respiration. Core body temperature, PET imaging of glucose uptake and VO2 measurements confirm a thermogenic defect in NCLX-null mice. We show that Ca2+ overload induced by adrenergic stimulation of NCLX-null BAT, triggers the mitochondrial permeability transition pore (mPTP) opening, leading to a remarkable mitochondrial swelling and cell death. Treatment with mPTP inhibitors rescue mitochondrial function and thermogenesis in NCLX-null BAT, while calcium overload persists. Our findings identify a key pathway through which BA evade apoptosis during adrenergic stimulation of uncoupling. NCLX deletion transforms the adrenergic pathway responsible for thermogenesis activation into a death pathway.

Composition of semen and foreskin mucosa aerobic microbiota and its impact on sperm parameters of captive collared peccaries (Pecari tajacu)

AIM

To evaluate the bacterial composition of collared peccary semen and foreskin mucosa, and to verify the sensitivity of isolates to antimicrobials used in semen conservation and to Aloe vera gel, which is an alternative external cryoprotectant.

METHODS AND RESULTS

Nine foreskin mucosa and ejaculate samples from adult animals were used. Sperm characteristics and bacterial load were evaluated in fresh semen. The preputial mucosa and semen bacterial isolates were identified and tested against five concentrations of each antimicrobial (streptomycin-penicillin and gentamicin) and A. vera gel. Corynebacterium sp. and Staphylococcus sp. were isolated in greater numbers than others in both semen (64·10 and 20·51%, respectively) and the foreskin mucosa (60·60 and 24·25%, respectively), and ranged from 0·4 to 21 × 10⁵ colony-forming units (CFU) per ml. The average load of Corynebacterium sp. was negatively correlated (P < 0·05) with the sperm membrane integrity (r = -0·73055) and curvilinear velocity (r = -0·69048). Streptomycin-penicillin and gentamicin inhibited most micro-organisms, and A. vera showed lower antimicrobial activity.

CONCLUSION

Several Gram-positive bacteria are present in semen and foreskin mucosa of collared peccary, and the benefits of using primarily penicillin-streptomycin and gentamicin antimicrobials in the bacterial control of diluted semen of these animals are strongly indicated.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides insight into the reproductive microbiota of captive male-collared peccary. This work provides a theoretical basis to assist reproductive biotechnologies for ex situ conservation of the species.

Emerging roles of β-cell mitochondria in type-2-diabetes

Type-2-Diabetes (T2D) is the most common metabolic disease in the world today. It erupts as a result of peripheral insulin resistance combined with hyperinsulinemia followed by suppression of insulin secretion from pancreatic β-cells. Mitochondria play a central role in β-cells by sensing glucose and also by mediating the suppression of insulin secretion in T2D. Here, we will summarize the evidence accumulated for the roles of β-cells mitochondria in T2D. We will present an updated view on how mitochondria in β-cells have been associated with T2D, from the genetic, bioenergetic, redox and structural points of view. The emerging picture is that mitochondrial structure and dysfunction directly contribute to β-cell function and in the pathogenesis of T2D.

Mitochondrial glycerol phosphate oxidation is modulated by adenylates through allosteric regulation of cytochrome c oxidase activity in mosquito flight muscle

The huge energy demand posed by insect flight activity is met by an efficient oxidative phosphorylation process that takes place within flight muscle mitochondria. In the major arbovirus vector Aedes aegypti, mitochondrial oxidation of pyruvate, proline and glycerol 3-phosphate (G3P) represent the major energy sources of ATP to sustain flight muscle energy demand. Although adenylates exert critical regulatory effects on several mitochondrial enzyme activities, the potential consequences of altered adenylate levels to G3P oxidation remains to be determined. Here, we report that mitochondrial G3P oxidation is controlled by adenylates through allosteric regulation of cytochrome c oxidase (COX) activity in A. aegypti flight muscle. We observed that ADP significantly activated respiratory rates linked to G3P oxidation, in a protonmotive force-independent manner. Kinetic analyses revealed that ADP activates respiration through a slightly cooperative mechanism. Despite adenylates caused no effects on G3P-cytochrome c oxidoreductase activity, COX activity was allosterically activated by ADP. Conversely, ATP exerted powerful inhibitory effects on respiratory rates linked to G3P oxidation and on COX activity. We also observed that high energy phosphate recycling mechanisms did not contribute to the regulatory effects of adenylates on COX activity or G3P oxidation. We conclude that mitochondrial G3P oxidation in A. aegypti flight muscle is regulated by adenylates through the allosteric modulation of COX activity, underscoring the bioenergetic relevance of this novel mechanism and the potential consequences for mosquito dispersal.

Highly aggressive behavior induced by social stress is associated to reduced cytochrome c oxidase activity in mice brain cortex

Violence and aggression represent severe social problems, with profound impacts on public health. Despite the development of experimental models to study aggressive behavior is highly appreciated, the underlying mechanisms remain poorly understood. Given the key contribution of mitochondria to central nervous system bioenergetics, we hypothesized that mitochondrial function in brain would be altered by social stress. Using a model of spontaneous aggression, we investigated here the effects of social stress on brain mitochondrial function in prefrontal cortex of Swiss mice. Animals were categorized as highly aggressive, subordinate and non-aggressive (harmonic) after stress induced by regrouping and compared them with non-regrouped animals. Despite social stress did not affect brain cortex oxygen consumption rates and NADH:cytochrome c oxidoreductase activity, cytochrome c oxidase expression and activity were significantly lower in highly aggressive animals compared to non-regrouped ones. These changes were not observed in ATP synthase and adenine nucleotide translocator content suggesting a selective effect of social stress on cytochrome c oxidase. Therefore, aggressive behavior generated upon social stress associates to selective reduction in cytochrome c oxidase activity, with potential detrimental effects on brain bioenergetics and function.

Environmental effects on collared peccaries (Pecari tajacu) serum testosterone, testicular morphology, and semen quality in the Caatinga biome

The objective of the study was to understand the influence of climatic variations in a semiarid environment on serum testosterone, testicular morphology and semen quality in collared peccaries (Pecari tajacu). Reproductive metrics (semen quality, testicular morphometry and testosterone serum profiles) of 10 mature males were measured monthly for 18 months. Meteorological data (rainfall, air temperature, relative humidity, wind speed and radiant heat load) also were recorded during the same period. Rainfall regimes were classified in different classes (Class 1: months with no rain; Class 2: months with up to 50 mm of rain; and Class 3: months with >50 mm of rain). Among rainfall classes, average air temperature (°C) and relative humidity (%) were different. Climatic changes between rainfall classes did not lead to overall variations of testicular size, testosterone production, and semen metrics. However, relative humidity recorded before semen collection (one day, one week, or over 51-55 days) was positively correlated (P < 0.05) with semen motility metrics (total motility, beat cross frequency and straightness) and sperm subpopulations (medium and static sperm), as well as with volume. Negative correlations (P < 0.05) were revealed between air temperature and the same semen motility patterns and volume. Additionally, radiant head load measured on the day of semen collection negatively influenced (P < 0.05) sperm straightness. This study demonstrates for the first time that no seasonal changes could be detected overt the 18-month period on the serum testosterone, testicular morphology and semen quality of collared peccaries raised in the Caatinga biome; however, it is expected that long term environmental changes will influence the reproductive physiology of species leaving in that habitat.

Heme crystallization in a Chagas disease vector acts as a redox-protective mechanism to allow insect reproduction and parasite infection

Heme crystallization as hemozoin represents the dominant mechanism of heme disposal in blood feeding triatomine insect vectors of the Chagas disease. The absence of drugs or vaccine for the Chagas disease causative agent, the parasite Trypanosoma cruzi, makes the control of vector population the best available strategy to limit disease spread. Although heme and redox homeostasis regulation is critical for both triatomine insects and T. cruzi, the physiological relevance of hemozoin for these organisms remains unknown. Here, we demonstrate that selective blockage of heme crystallization in vivo by the antimalarial drug quinidine, caused systemic heme overload and redox imbalance in distinct insect tissues, assessed by spectrophotometry and fluorescence microscopy. Quinidine treatment activated compensatory defensive heme-scavenging mechanisms to cope with excessive heme, as revealed by biochemical hemolymph analyses, and fat body gene expression. Importantly, egg production, oviposition, and total T. cruzi parasite counts in R. prolixus were significantly reduced by quinidine treatment. These effects were reverted by oral supplementation with the major insect antioxidant urate. Altogether, these data underscore the importance of heme crystallization as the main redox regulator for triatomine vectors, indicating the dual role of hemozoin as a protective mechanism to allow insect fertility, and T. cruzi life-cycle. Thus, targeting heme crystallization in insect vectors represents an innovative way for Chagas disease control, by reducing simultaneously triatomine reproduction and T. cruzi transmission.

Chagas disease is a fatal illness caused by Trypanosoma cruzi parasites, which are transmitted by blood sucking triatomine insect vectors. Although blood is a natural food source for these insects, its digestion releases toxic products, which poses a dietary challenge for both triatomine insects and trypanosomes. To overcome this, triatomines eliminate these toxic blood products by a unique process of heme crystallization into hemozoin that take place in their digestive tract. Here we describe that this detoxification process represents the major mechanism for redox balance control, and is necessary to allow triatomine insect reproduction, and Trypanosoma cruzi infection. Disruption of heme crystallization in triatomine insects thus represents a new venue for Chagas disease control, by targeting at the same time insect reproduction and parasite transmission.

Mitochondria Bound to Lipid Droplets Have Unique Bioenergetics, Composition, and Dynamics that Support Lipid Droplet Expansion

Mitochondria associate with lipid droplets (LDs) in fat-oxidizing tissues, but the functional role of these peridroplet mitochondria (PDM) is unknown. Microscopic observation of interscapular brown adipose tissue reveals that PDM have unique protein composition and cristae structure and remain adherent to the LD in the tissue homogenate. We developed an approach to isolate PDM based on their adherence to LDs. Comparison of purified PDM to cytoplasmic mitochondria reveals that (1) PDM have increased pyruvate oxidation, electron transport, and ATP synthesis capacities; (2) PDM have reduced β-oxidation capacity and depart from LDs upon activation of brown adipose tissue thermogenesis and β-oxidation; (3) PDM support LD expansion as Perilipin5-induced recruitment of mitochondria to LDs increases ATP synthase-dependent triacylglyceride synthesis; and (4) PDM maintain a distinct protein composition due to uniquely low fusion-fission dynamics. We conclude that PDM represent a segregated mitochondrial population with unique structure and function that supports triacylglyceride synthesis.

Hemoglobin metabolism by-products are associated with an inflammatory response in patients with hemorrhagic stroke

Objective

To evaluate the relationships of brain iron and heme with the inflammatory response of the systemic and central nervous systems and to investigate the role of defensive systems against the toxicity of iron and heme in the central nervous system.

Methods

We assessed a prospective cohort of patients presenting with intracerebral and subarachnoid hemorrhage. We assayed plasma and cerebrospinal fluid samples for the presence of iron, heme, hemopexin, haptoglobin, enolase, S100-β and cytokines for the first three days following hemorrhagic stroke. We also analyzed the dynamic changes in these components within both fluids and their relationship with early mortality rates.

Results

Hemopexin and haptoglobin concentrations were nearly negligible in the brain after intracerebral and subarachnoid hemorrhage. Cerebrospinal fluid iron and heme concentrations correlated with a pro-inflammatory response in the central nervous system, and plasmatic and cerebrospinal fluid inflammatory profiles on the third day after hemorrhagic stroke were related to early mortality rates. Interleukin 4 levels within the cerebrospinal fluid during the first 24 hours after hemorrhagic stroke were found to be higher in survivors than in non-survivors.

Conclusion

Iron and heme are associated with a pro-inflammatory response in the central nervous system following hemorrhagic stroke, and protections against hemoglobin and heme are lacking within the human brain. Patient inflammatory profiles were associated with a poorer prognosis, and local anti-inflammatory responses appeared to have a protective role.

Modulation of mitochondrial metabolism as a biochemical trait in blood feeding organisms: the redox vampire hypothesis redux

Hematophagous organisms undergo remarkable metabolic changes during the blood digestion process, increasing fermentative glucose metabolism, and reducing respiratory rates, both consequence of functional mitochondrial remodeling. Here, we review the pathways involved in energy metabolism and mitochondrial functionality in a comparative framework across different hematophagous species, and consider how these processes regulate redox homeostasis during blood digestion. The trend across distinct species indicate that a switch in energy metabolism might represent an important defensive mechanism to avoid the potential harmful interaction of oxidants generated from aerobic energy metabolism with products derived from blood digestion. Indeed, in insect vectors, blood feeding transiently reduces respiratory rates and oxidant production, irrespective of tissue and insect model. On the other hand, a different scenario is observed in several unrelated parasite species when exposed to blood digestion products, as respiratory rates reduce and mitochondrial oxidant production increase. The emerging picture indicates that re-wiring of energy metabolism, through reduced mitochondrial function, culminates in improved tolerance to redox insults and seems to represent a key step for hematophagous organisms to cope with the overwhelming and potentially toxic blood meal.

Steroidogenesis during postnatal testicular development of Galea spixii

The androgen/estrogen balance is essential for normal sexual development and reproduction in mammals. Studies performed herein investigated the potential for estrogen synthesis in cells of the testes of a hystricomorph rodent, Galea spixii. The study characterized the expression of the key enzymes responsible for estrogen and androgen synthesis, cytochromes P450 aromatase (P450arom), 17α-hydroxylase/17,20-lyase (P450c17) respectively, as well as the redox partner NADPH cytochrome P450 oxido-reductase (CPR) required to support electron transfer and catalysis of these P450s, by immunohistochemistry (IHC) and quantitative polymerase chain reaction (qPCR) analysis, throughout postnatal sexual development. Testes (immature, pre-pubertal, pubertal and post-pubertal) were collected, fixed for IHC (CYP19, CYP17 and CPR) and stored frozen for qPCR for the relevant gene transcripts (Cyp19a1 and Cyp17a1). Expression of P450c17 was significantly elevated at the pre-pubertal and pubertal stages. Based on IHC, P450c17 was expressed only in Leydig cell clusters. The expression of P450arom was detectable at all stages of sexual development of Galea spixii. IHC data suggest that estrogen synthesis was not restricted to somatic cells (Leydig cells/Sertoli cells), but that germ cells may also be capable of converting androgens into estrogens, important for testicular function and spermatogenesis.

Current Trends and Research Challenges Regarding "Preparation for Oxidative Stress"

Survival under stress, such as exposure to hypoxia, anoxia, freezing, dehydration, air exposure of water breathing organisms, and estivation, is commonly associated to enhanced endogenous antioxidants, a phenomenon coined "preparation for oxidative stress" (POS). The regulation of free radical metabolism seems to be crucial under these selective pressures, since this response is widespread among animals. A hypothesis of how POS works at the molecular level was recently proposed and relies on two main processes: increased reactive species production under hypoxia, and activation of redox-sensitive transcription factors and signaling pathways, increasing the expression of antioxidants. The present paper brings together the current knowledge on POS and considers its future directions. Data indicate the presence of POS in 83 animal species (71.6% among investigated species), distributed in eight animal phyla. Three main research challenges on POS are presented: (i) to identify the molecular mechanism(s) that mediate/induce POS, (ii) to identify the evolutionary origins of POS in animals, and (iii) to determine the presence of POS in natural environments. We firstly discuss the need of evidence for increased RS production in hypoxic conditions that underlie the POS response. Secondly, we discuss the phylogenetic origins of POS back 700 million years, by identifying POS-positive responses in cnidarians. Finally, we present the first reports of the POS adaptation strategy in the wild. The investigation of these research trends and challenges may prove useful to understand the evolution of animal redox adaptations and how they adapt to increasing stressful environments on Earth.

Heme modulates Trypanosoma cruzi bioenergetics inducing mitochondrial ROS production

Trypanosoma cruzi is the causative agent of Chagas disease and has a single mitochondrion, an organelle responsible for ATP production and the main site for the formation of reactive oxygen species (ROS). T. cruzi is an obligate intracellular parasite with a complex life cycle that alternates between vertebrate and invertebrate hosts, therefore the development of survival strategies and morphogenetic adaptations to deal with the various environments is mandatory. Over the years our group has been studying the vector-parasite interactions using heme as a physiological oxidant molecule that triggered epimastigote proliferation however, the source of ROS induced by heme remained unknown. In the present study we demonstrate the involvement of heme in the parasite mitochondrial metabolism, decreasing oxygen consumption leading to increased mitochondrial ROS and membrane potential. First, we incubated epimastigotes with carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), an uncoupler of oxidative phosphorylation, which led to decreased ROS formation and parasite proliferation, even in the presence of heme, correlating mitochondrial ROS and T. cruzi survival. This hypothesis was confirmed after the mitochondria-targeted antioxidant ((2-(2,2,6,6 Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride (MitoTEMPO) decreased both heme-induced ROS and epimastigote proliferation. Furthermore, heme increased the percentage of tetramethylrhodamine methyl ester (TMRM) positive parasites tremendously-indicating the hyperpolarization and increase of potential of the mitochondrial membrane (ΔΨm). Assessing the mitochondrial functional metabolism, we observed that in comparison to untreated parasites, heme-treated epimastigotes decreased their oxygen consumption, and increased the complex II-III activity. These changes allowed the electron flow into the electron transport system, even though the complex IV (cytochrome c oxidase) activity decreased significantly, showing that heme-induced mitochondrial ROS appears to be a consequence of the enhanced mitochondrial physiological modulation. Finally, the parasites that were submitted to high concentrations of heme presented no alterations in the ultrastructure. Consequently, our results suggest that heme released by the insect vector after the blood meal, modify epimastigote mitochondrial physiology to increase ROS as a metabolic mechanism to maintain epimastigote survival and proliferation.

β-Cyclodextrin polymer binding to DNA: Modulating the physicochemical parameters

Cyclodextrins and cyclodextrins-modified molecules have interesting and appealing properties due to their capacity to host components that are normally insoluble or poorly soluble in water. In this work, we investigate the interaction of a β-cyclodextrin polymer (poly-β-CD) with λ-DNA. The polymers are obtained by the reaction of β-CD with epichlorohydrin in alkaline conditions. We have used optical tweezers to characterize the changes of the mechanical properties of DNA molecules by increasing the concentration of poly-β-CD in the sample. The physical chemistry of the interaction is then deduced from these measurements by using a recently developed quenched-disorder statistical model. It is shown that the contour length of the DNA does not change in the whole range of poly-β-CD concentration (<300μM). On the other hand, significant alterations were observed in the persistence length that identifies two binding modes corresponding to the clustering of ∼2.6 and ∼14 polymer molecules along the DNA double helix, depending on the polymer concentration. Comparing these results with the ones obtained for monomeric β-CD, it was observed that the concentration of CD that alters the DNA persistence length is considerably smaller when in the polymeric form. Also, the binding constant of the polymer-DNA interaction is three orders of magnitude higher than the one found for native (monomeric) β-CD. These results show that the polymerization of the β-CD strongly increases its binding affinity to the DNA molecule. This property can be wisely used to modulate the binding of cyclodextrins to the DNA double helix.

Mfn2 deletion in brown adipose tissue protects from insulin resistance and impairs thermogenesis

BAT‐controlled thermogenic activity is thought to be required for its capacity to prevent the development of insulin resistance. This hypothesis predicts that mediators of thermogenesis may help prevent diet‐induced insulin resistance. We report that the mitochondrial fusion protein Mitofusin 2 (Mfn2) in BAT is essential for cold‐stimulated thermogenesis, but promotes insulin resistance in obese mice. Mfn2 deletion in mice through Ucp1‐cre (BAT‐Mfn2‐KO) causes BAT lipohypertrophy and cold intolerance. Surprisingly however, deletion of Mfn2 in mice fed a high fat diet (HFD) results in improved insulin sensitivity and resistance to obesity, while impaired cold‐stimulated thermogenesis is maintained. Improvement in insulin sensitivity is associated with a gender‐specific remodeling of BAT mitochondrial function. In females, BAT mitochondria increase their efficiency for ATP‐synthesizing fat oxidation, whereas in BAT from males, complex I‐driven respiration is decreased and glycolytic capacity is increased. Thus, BAT adaptation to obesity is regulated by Mfn2 and with BAT‐Mfn2 absent, BAT contribution to prevention of insulin resistance is independent and inversely correlated to whole‐body cold‐stimulated thermogenesis.

Molecular, Cellular and Clinical Aspects of Intracerebral Hemorrhage: Are the Enemies Within?

Hemorrhagic stroke is a disease with high incidence and mortality rates. In addition to the mass lesions that result from hemorrhagic stroke, substances such as the blood-derived products (BDP) (hemoglobin (Hb), heme and iron) induce a potent inflammatory response and exert direct toxic effects on neurons, astrocytes, and microglia. In the present review, we discuss the mechanisms of brain injury secondary to hemorrhagic stroke, focusing on the involvement of BDP as major players of cellular redox imbalance, inflammation, and glutamate excitotoxicity. Potential natural mechanisms of protection against free Hb and heme such as haptoglobin and hemopexin, respectively, are highlighted. We finally discuss the experimental and clinical trials targeting free iron and heme scavenging as well as inflammation, as potential new therapies to minimize the devastating effects of hemorrhagic stroke on brain structure and function.

Extracellular Redox Regulation of Intracellular Reactive Oxygen Generation, Mitochondrial Function and Lipid Turnover in Cultured Human Adipocytes

Background

Many tissues play an important role in metabolic homeostasis and the development of diabetes and obesity. We hypothesized that the circulating redox metabolome is a master metabolic regulatory system that impacts all organs and modulates reactive oxygen species (ROS) production, lipid peroxidation, energy production and changes in lipid turnover in many cells including adipocytes.

Methods

Differentiated human preadipocytes were exposed to the redox couples, lactate (L) and pyruvate (P), β–hydroxybutyrate (βOHB) and acetoacetate (Acoc), and the thiol-disulfides cysteine/ cystine (Cys/CySS) and GSH/GSSG for 1.5–4 hours. ROS measurements were done with CM-H₂DCFDA. Lipid peroxidation (LPO) was assessed by a modification of the thiobarbituric acid method. Lipolysis was measured as glycerol release. Lipid synthesis was measured as ¹⁴C-glucose incorporated into lipid. Respiration was assessed using the SeaHorse XF24 analyzer and the proton leak was determined from the difference in respiration with oligomycin and antimycin A.

Results

Metabolites with increasing oxidation potentials (GSSG, CySS, Acoc) increased adipocyte ROS. In contrast, P caused a decrease in ROS compared with L. Acoc also induced a significant increase in both LPO and lipid synthesis. L and Acoc increased lipolysis. βOHB increased respiration, mainly due to an increased proton leak. GSSG, when present throughout 14 days of differentiation significantly increased fat accumulation, but not when added later.

Conclusions

We demonstrated that in human adipocytes changes in the external redox state impacted ROS production, LPO, energy efficiency, lipid handling, and differentiation. A more oxidized state generally led to increased ROS, LPO and lipid turnover and more reduction led to increased respiration and a proton leak. However, not all of the redox couples were the same suggesting compartmentalization. These data are consistent with the concept of the circulating redox metabolome as a master metabolic regulatory system.

Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology

Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult S. mansoni worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute to redox biology among parasite sexes.

Detergent-Mediated Formation of β-Hematin: Heme Crystallization Promoted by Detergents Implicates Nanostructure Formation for Use as a Biological Mimic

Hemozoin is a unique biomineral that results from the sequestration of toxic free heme liberated as a consequence of hemoglobin degradation in the malaria parasite. Synthetic neutral lipid droplets (SNLDs) and phospholipids were previously shown to support the rapid formation of β-hematin, abiological hemozoin, under physiologically relevant pH and temperature, though the mechanism by which heme crystallization occurs remains unclear. Detergents are particularly interesting as a template because they are amphiphilic molecules that spontaneously organize into nanostructures and have been previously shown to mediate β-hematin formation. Here, 11 detergents were investigated to elucidate the physicochemical properties that best recapitulate crystal formation in the parasite. A strong correlation between the detergent's molecular structure and the corresponding kinetics of β-hematin formation was observed, where higher molecular weight polar chains promoted faster reactions. The larger hydrophilic chains correlated to the detergent's ability to rapidly sequester heme into the lipophilic core, allowing for crystal nucleation to occur. The data presented here suggest that detergent nanostructures promote β-hematin formation in a similar manner to SNLDs and phospholipids. Through understanding mediator properties that promote optimal crystal formation, we are able to establish an in vitro assay to probe this drug target pathway.

Primary brain calcification in patients undergoing treatment with the biphosphanate alendronate

Brain calcification might be associated with various metabolic, infectious or vascular conditions. Clinically, brain calcification can include symptons such as migraine, parkinsonism, psychosis or dementia. The term Primary Brain Calcification was recently used for those patients without an obvious cause (formerly idiopathic) while Primary Familial Brain Calcifications was left for the cases with autosomal dominant inheritance. Recent studies found mutations in four genes (SLC20A2, PDGFRB, PDGFB and XPR1). However, these gene represent only 60% of all familial cases suggesting other genes remain to be elucidated. Studies evaluating treatments for such a devastating disease are scattered, usually appearing as single case reports. In the present study, we describe a case series of 7 patients treated with Alendronate, a widely prescribed biphosphanate. We observed good tolerance and evidence of improvements and stability by some patients. No side effects were reported and no specific symptoms related to medication. Younger patients and one individual continuing a prescription (prior to study commencement) appeared to respond more positively with some referred improvements in symptoms. Biphosphanates may represent an excellent prospect for the treatment of brain calcifications due to their being well tolerated and easily available. Conversely, prospective and controlled studies should promptly address weaknesses found in the present analysis.

Classical ROS-dependent and early/rapid ROS-independent release of Neutrophil Extracellular Traps triggered by Leishmania parasites

Neutrophil extracellular traps (NETs) extruded from neutrophils upon activation are composed of chromatin associated with cytosolic and granular proteins, which ensnare and kill microorganisms. This microbicidal mechanism named classical netosis has been shown to dependent on reactive oxygen species (ROS) generation by NADPH oxidase and also chromatin decondensation dependent upon the enzymes (PAD4), neutrophil elastase (NE) and myeloperoxidase (MPO). NET release also occurs through an early/rapid ROS-independent mechanism, named early/rapid vital netosis. Here we analyze the role of ROS, NE, MPO and PAD4 in the netosis stimulated by Leishmania amazonensis promastigotes in human neutrophils. We demonstrate that promastigotes induce a classical netosis, dependent on the cellular redox imbalance, as well as by a chloroamidine sensitive and elastase activity mechanism. Additionally, Leishmania also induces the early/rapid NET release occurring only 10 minutes after neutrophil-parasite interaction. We demonstrate here, that this early/rapid mechanism is dependent on elastase activity, but independent of ROS generation and chloroamidine. A better understanding of both mechanisms of NET release, and the NETs effects on the host immune system modulation, could support the development of new potential therapeutic strategies for leishmaniasis.

Ultrastructure of spermatogenesis and spermatozoa in agoutis during sexual development

The aim was to study the ultrastructure of testicular parenchyma and define the morphological ultrastructure of spermatozoa of agoutis kept in captivity. Segments of testes from eight agouti males at prepubescence, prepuberty, pubescence and sexual maturity were fixed in glutaraldehyde. Laboratory procedures were performed for transmission electron microscopy. Spermatogonial cells of Type A - pale, Type A - dark, intermediate and Type B were found. Spermatocytes in the pachytene phase were abundant among primary spermatocytes. From the prepubertal phase, Sertoli cells exhibited invaginations in the nuclear membrane and lipid inclusions in the cytoplasm due to their phagocytic function. Leydig cells displayed higher metabolic activity during puberty as evidenced by the presence of lipid droplets. Spermatozoa were fully formed morphologically at prepuberty. The centriolar complex had partially degenerated and featured a centriolar space as in rodents. Sperm heads were tapered, without prominence of the acrosome or evidence of the perforatorium, differing from cavies, rats and mice. This is the first study to describe the ultrastructure of agouti spermatozoa. This research may assist as a basis for future work related to fertility and other biotechnologies applied to reproductive biology in agoutis.

Histology and Immunohistochemistry of the Cardiac Ventricular Structure in the Green Turtle (Chelonia mydas)

This study describes the implications of cardiac ventricular microscopy in Chelonia mydas relating to its ability to dive. For this work, 11 specimens of the marine turtle species C. mydas found dead on the coast of Rio Grande do Norte (Northeast Brazil) were used. After necropsy, fragments of the cardiac ventricular wall were fixed in 10% buffered formaldehyde solution for 24 h and then subjected to routine processing for light and scanning electron microscopy (SEM). The ventricle in this species is formed by the epicardium, myocardium and endocardium. The subepicardial layer consists of highly vascularised connective tissue that emits septa to reinforce the myocardium surface. There is an abundant and diffuse subepicardial nerve plexus shown by immunostaining technique. The thickness of the spongy myocardium and the nature of its trabeculae varied between the heart chambers. The endocardium shows no characteristic elements of the heart conduction system. The valves have a hyaline cartilage skeleton, coated by dense irregular connective tissues characterised by elastic fibres. These findings in the green turtle ventricular microscopy are related to hypoxia resistance during diving.

Interactions Among Different Devices and Electrical Stimulus on the Electroejaculation of Captive Agoutis (Dasyprocta leporina)

The interactions among different electroejaculation devices associated with serial or continuous stimuli were investigated to improve the efficiency of the electroejaculation for semen collection in agoutis. Ten sexually matured male Dasyprocta leporina were restrained by the intramuscular administration of xylazine-ketamine association. Each individual was randomly subjected to four electroejaculation protocols, by combining two devices (one presenting longitudinal electrodes emitting square waves and other presenting ring electrodes emitting sine waves) and two electrical stimuli protocols (serial or continuous). A total of 40 attempts for electroejaculation were conducted in agoutis, being 10 per treatment. The most efficient treatment in providing ejaculates containing sperm (p < 0.05) was that using and electroejaculator connected to a probe with ring electrodes and associated with serial stimuli (4/7; 57%). In spite of semen parameters obtained by sine waves were adequate for using the samples for assisted reproduction, higher values for sperm motility and functional membrane integrity were obtained in the use of the square wave, independently of the electric stimulation protocol used (p < 0.05). In conclusion, we verified that the use of a device presenting a probe with ring electrodes and emitting sine waves, associated with a serial stimuli protocol, improves the efficiency for semen obtaining by electroejaculation in adults D. leporina.

Mitochondrial physiology in the major arbovirus vector Aedes aegypti: substrate preferences and sexual differences define respiratory capacity and superoxide production

Adult females of Aedes aegypti are facultative blood sucking insects and vectors of Dengue and yellow fever viruses. Insect dispersal plays a central role in disease transmission and the extremely high energy demand posed by flight is accomplished by a very efficient oxidative phosphorylation process, which take place within flight muscle mitochondria. These organelles play a central role in energy metabolism, interconnecting nutrient oxidation to ATP synthesis, but also represent an important site of cellular superoxide production. Given the importance of mitochondria to cell physiology, and the potential contributions of this organelle for A. aegypti biology and vectorial capacity, here, we conducted a systematic assessment of mitochondrial physiology in flight muscle of young adult A. aegypti fed exclusively with sugar. This was carried out by determining the activities of mitochondrial enzymes, the substrate preferences to sustain respiration, the mitochondrial bioenergetic efficiency and capacity, in both mitochondria-enriched preparations and mechanically permeabilized flight muscle in both sexes. We also determined the substrates preferences to promote mitochondrial superoxide generation and the main sites where it is produced within this organelle. We observed that respiration in A. aegypti mitochondria was essentially driven by complex I and glycerol 3 phosphate dehydrogenase substrates, which promoted distinct mitochondrial bioenergetic capacities, but with preserved efficiencies. Respiration mediated by proline oxidation in female mitochondria was strikingly higher than in males. Mitochondrial superoxide production was essentially mediated through proline and glycerol 3 phosphate oxidation, which took place at sites other than complex I. Finally, differences in mitochondrial superoxide production among sexes were only observed in male oxidizing glycerol 3 phosphate, exhibiting higher rates than in female. Together, these data represent a significant step towards the understanding of fundamental mitochondrial processes in A. aegypti, with potential implications for its physiology and vectorial capacity.

Ultrastructure of the epididymis and vas deferens of agoutis at different stages of sexual development

The agouti (Dasyprocta spp.) is a rodent found predominantly in the Brazilian Caatinga and has importance as an alternative source of protein. In this study, the objective was to describe the ultrastructure of components of sperm pathways, especially the epididymis and vas deferens, during sexual development of agoutis kept in captivity. Segments of the vas deferens and epididymis of 8 agouti males at different stages of sexual development (prepubescent, prepubertal, pubescent, and adult) were fixed in glutaraldehyde. The following laboratory procedures were performed: histology following the standard protocol for semithin cut (toluidine blue), and transmission electron microscopy. This was a pioneer study in which it was observed that the epididymis of agoutis is composed of principal, basal, halogen, apical, and clean cells. During prepubescent and prepubertal stages, clean cells were observed in addition to principal, basal, and halogen cells. Once puberty was reached, apical cells were also present, and clean cells were no longer visible. This epithelial change during sexual development is possibly due to physiological functions. The interaction between these cells supports this, and age probably influenced the change. With regard to the vas deferens, this study was also a pioneer to note that before pubescence there were two muscle layers, differing from older animals, which had three muscle layers. This may be due to lack of sperm transit in younger animals. We concluded that the pseudostratified stereociliated epithelium of the epididymis and vas deferens of agoutis kept in captivity undergo morphological and functional changes during sexual development.

Unsaturated glycerophospholipids mediate heme crystallization: biological implications for hemozoin formation in the kissing bug Rhodnius prolixus

Hemozoin (Hz) is a heme crystal produced by some blood-feeding organisms, as an efficient way to detoxify heme derived from hemoglobin digestion. In the triatomine insect Rhodnius prolixus, Hz is essentially produced by midgut extracellular phospholipid membranes known as perimicrovillar membranes (PMVM). Here, we investigated the role of commercial glycerophospholipids containing serine, choline and ethanolamine as headgroups and R. prolixus midgut lipids (RML) in heme crystallization. All commercial unsaturated forms of phospholipids, as well as RML, mediated fast and efficient β-hematin formation by means of two kinetically distinct mechanisms: an early and fast component, followed by a late and slow one. The fastest reactions observed were induced by unsaturated forms of phosphatidylethanolamine (uPE) and phosphatidylcholine (uPC), with half-lives of 0.04 and 0.7 minutes, respectively. β-hematin crystal morphologies were strikingly distinct among groups, with uPE producing homogeneous regular brick-shaped crystals. Interestingly, uPC-mediated reactions resulted in two morphologically distinct crystal populations: one less representative group of regular crystals, resembling those induced by uPE, and the other largely represented by crystals with numerous sharp edges and tapered ends. Heme crystallization reactions induced by RML were efficient, with a heme to β-hematin conversion rate higher than 70%, but clearly slower (t1/2 of 9.9-17.7 minutes) than those induced by uPC and uPE. Interestingly, crystals produced by RML were homogeneous in shape and quite similar to those mediated by uPE. Thus, β-hematin formation can be rapidly and efficiently induced by unsaturated glycerophospholipids, particularly uPE and uPC, and may play a role on biological heme crystallization in R. prolixus midgut.

Protein profile of the seminal plasma of collared peccaries (Pecari tajacu Linnaeus, 1758)

This study was conducted to characterize the major proteins of the peccary seminal plasma, based on the semen samples collected from nine adult and reproductively sound animals. Our approach included the use of two-dimensional electrophoresis followed by Coomassie blue staining and analysis of polypeptide maps with PDQuest Software (Bio-Rad). Proteins were identified by tandem mass spectrometry (LC-MS/MS). We detected 179 protein spots per gel and 98 spots were identified by mass spectrometry, corresponding to 23 different proteins. The combined intensity of those spots accounted for 56.2±6% of the intensities of all spots and 60.9% of the intensities of spots presented in every protein map. Protein spots identified as clusterin represented 19.7±8.3% of the integrated optical densities of all spots detected in the seminal plasma maps. There was a negative association (r=-0.87; P<0.05) between the intensity of a clusterin spot and the percentage of sperm with functional membrane. Spermadhesin porcine seminal plasma protein 1 and bodhesin 2 comprised 5.4±1.9 and 8.8±3.9% of the total intensity of all spots respectively. Many proteins appeared in a polymorphic pattern, such as clusterin (27 spots), epididymal secretory glutathione peroxidase (ten spots), inter-α-trypsin inhibitor (12 spots), and IgG-binding protein (ten spots), among others. In conclusion, we presently describe the major seminal plasma proteome of the peccary, which exhibits a distinct high expression of clusterin isoforms. Knowledge of wild species reproductive biology is crucial for an understanding of their survival strategies and adaptation in a changing environment.

Ultrastructure of spermatogenesis in Spix's yellow-toothed cavy (Galea spixii)

This was a pioneer study of the spermatogenic process from the onset of puberty in Spix's yellow-toothed cavies (SYC,Galea spixii) bred in captivity. The study aimed to characterize fine structure of spermatogenesis. Twelve testes from pubertal and post-pubertal SYC males were studied using transmission electron microscopy. Spermatogenesis can be divided into three phases: proliferation, meiosis, and spermiogenesis. In proliferation phase, three types of spermatogonia were identified and characterized as Adark, Apale, and B. In the second phase, spermatocytes (2n) undergo meiotic divisions that generate spermatids (n); the process begins in spermatocytes in the preleptotene stage when they increase their nuclear size, differentiating into spermatocytes in the leptotene stage when cell division is initiated. In addition, we found chromatin condensation, and formation of a structure composed of proteins that formed a central shaft and two lateral bars associated with pairing of homologous chromosomes. During spermiogenesis, the following main events occurred: condensation of nuclear chromatin, formation of acrosome with perfuratorium, elimination of residual cytoplasm, and development of the flagellum. The sperm head is different from that of other rodents. The endoplasmic reticulum and the Golgi complex are the two main organelles demonstrated during this process. These organelles collaborate through synthesis of proteins and hormones for the development of germ cells during spermatogenesis in SYC.

In vivo detection of free radicals in mouse septic encephalopathy using molecular MRI and immuno-spin trapping

Free radicals are known to play a major role in sepsis. Combined immuno-spin trapping and molecular magnetic resonance imaging (MRI) was used to detect in vivo and in situ levels of free radicals in murine septic encephalopathy after cecal ligation and puncture (CLP). DMPO (5,5-dimethyl pyrroline N-oxide) was injected over 6h after CLP, before administration of an anti-DMPO probe (anti-DMPO antibody bound to albumin-gadolinium-diethylene triamine pentaacetic acid-biotin MRI targeting contrast agent). In vitro assessment of the anti-DMPO probe in oxidatively stressed mouse astrocytes significantly decreased T1 relaxation (p < 0.0001) compared to controls. MRI detected the presence of anti-DMPO adducts via a substantial decrease in %T1 change within the hippocampus, striatum, occipital, and medial cortex brain regions (p < 0.01 for all) in septic animals compared to shams, which was sustained for over 60 min (p < 0.05 for all). Fluorescently labeled streptavidin was used to target the anti-DMPO probe biotin, which was elevated in septic brain, liver, and lungs compared to sham. Ex vivo DMPO adducts (qualitative) and oxidative products, including 4-hydroxynonenal and 3-nitrotyrosine (quantitative, p < 0.05 for both), were elevated in septic brains compared to shams. This is the first study that has reported on the detection of in vivo and in situ levels of free radicals in murine septic encephalopathy.

Exercise-induced cardioprotection is impaired by anabolic steroid treatment through a redox-dependent mechanism

High doses of anabolic androgenic steroids (AAS) impair the cardioprotective effects of exercise against ischemia/reperfusion (I/R) insult, possibly through cellular redox imbalance. Here, the effect of nandrolone decanoate (DECA) treatment on heart redox metabolism was investigated during I/R in sedentary and exercised rats. DECA treatment significantly reduced superoxide dismutase and glutathione reductase activities in exercised rats after heart reperfusion. Catalase and glutathione peroxidase activities were not affected by DECA in both sedentary and trained rats, regardless the I/R period. DECA also induced myocardial oxidative stress, as evidenced by the reduced levels of total reduced thiols after heart reperfusion in exercised rats treated with the anabolic steroid. These results indicate that cardiotoxic effects of supraphysiological doses of AAS involve reduced heart antioxidant capacity.

Silencing of maternal heme-binding protein causes embryonic mitochondrial dysfunction and impairs embryogenesis in the blood sucking insect Rhodnius prolixus

The heme molecule is the prosthetic group of many hemeproteins involved in essential physiological processes, such as electron transfer, transport of gases, signal transduction, and gene expression modulation. However, heme is a pro-oxidant molecule capable of propagating reactions leading to the generation of reactive oxygen species. The blood-feeding insect Rhodnius prolixus releases enormous amounts of heme during host blood digestion in the midgut lumen when it is exposed to a physiological oxidative challenge. Additionally, this organism produces a hemolymphatic heme-binding protein (RHBP) that transports heme to pericardial cells for detoxification and to growing oocytes for yolk granules and as a source of heme for embryo development. Here, we show that silencing of RHBP expression in female fat bodies reduced total RHBP circulating in the hemolymph, promoting oxidative damage to hemolymphatic proteins. Moreover, RHBP knockdown did not cause reduction in oviposition but led to the production of heme-depleted eggs (white eggs). A lack of RHBP did not alter oocyte fecundation. However, produced white eggs were nonviable. Embryo development cellularization and vitellin yolk protein degradation, processes that normally occur in early stages of embryogenesis, were compromised in white eggs. Total cytochrome c content, cytochrome c oxidase activity, citrate synthase activity, and oxygen consumption, parameters that indicate mitochondrial function, were significantly reduced in white eggs compared with normal dark red eggs. Our results showed that reduction of heme transport from females to growing oocytes by RHBP leads to embryonic mitochondrial dysfunction and impaired embryogenesis.

Dengue induces platelet activation, mitochondrial dysfunction and cell death through mechanisms that involve DC-SIGN and caspases

BACKGROUND

Worldwide, dengue is the most prevalent human arbovirus disease. Dengue infection may cause a range of clinical manifestations from self-limiting febrile illness through to a life-threatening syndrome accompanied by both bleeding and shock. Thrombocytopenia is frequently observed in mild and severe disease; however, the mechanisms involved in DENV-induced platelet activation and thrombocytopenia are incompletely understood.

PATIENTS AND METHODS

Freshly isolated platelets from patients with dengue were evaluated for markers of activation, mitochondrial alteration and activation of cell death pathways. In parallel, we examined direct DENV-induced activation and apoptosis of platelets obtained from healthy subjects.

RESULTS

We found that platelets from DENV-infected patients exhibited increased activation by comparison to control subjects. Moreover, platelets from DENV-infected patients exhibited classic signs of the intrinsic pathway of apoptosis that include increased surface phosphatidylserine exposure, mitochondrial depolarization and activation of caspase-9 and -3. Indeed, thrombocytopenia was shown to strongly associate with enhanced platelet activation and cell death in DENV-infected patients. Platelet activation, mitochondrial dysfunction and caspase-dependent phosphatidylserine exposure on platelets were also observed when platelets from healthy subjects were directly exposed to DENV in vitro. DENV-induced platelet activation was shown to occur through mechanisms largely dependent on DC-SIGN.

CONCLUSIONS

Together our results demonstrate that platelets from patients with dengue present signs of activation, mitochondrial dysfunction and activation of the apoptosis caspase cascade, which may contribute to the development of thrombocytopenia in patients with dengue. Our results also suggest the involvement of DC-SIGN as a critical receptor in DENV-dependent platelet activation.