Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review

An historical review is given of American visceral leishmaniasis (AVL), with particular reference to the eco-epidemiology of the disease in Brazil. Following the first records of AVL in this country, in 1934, the sandfly Lutzomyia longipalpis (Lutz and Neiva, 1912) was incriminated as the principal vector. It is now generally accepted, however, that there exist a number of cryptic species under the name of Lu. longipalpis s.l. and that variations in the quantity of the vasodilatory peptide maxadilan in the saliva of flies from different populations of Lu. longipalpis s.l., may account for the variable clinical manifestations of AVL seen in different geographic regions. Distribution of AVL has been shown to extend throughout most of South and Central America, with the domestic dog serving as the principal reservoir of infection for man. However, while one hypothesis suggests that the causative parasite is Leishmania infantum, imported from Europe with the Portuguese and Spanish colonists, the demonstration of a high rate of benign, inapparent infection in foxes in Amazonian Brazil raised an opposing suggestion that the parasite is indigenous to the Americas. Recent reports of similar infections in native marsupials, and possibly rodents, tend to support this view, particularly as Lu. longipalpis is primordially a silvatic sandfly. Although effective control measures in foci of the disease will diminish the number of canine and human infections, the presence of such an enzootic in a variety of native animals will render the total eradication of AVL unlikely.

Performance levels of four Latin American laboratories for the serodiagnosis of Chagas disease in Mexican sera samples

In nearly all of the previous multicentre studies evaluating serological tests for Trypanosoma cruzi infection, sera samples from Central or South American countries have been used preferentially. In this work we compared the reliability of the serological tests using Mexican sera samples that were evaluated in four independent laboratories. This included a reference laboratory in Brazil and three participant laboratories, including one in Central America and two in Mexico. The kappa index between Brazilian and Honduran laboratories reached 1.0 and the index for the Mexican laboratories reached 0.94. Another finding of this study was that the source of antigen did not affect the performance of the serological tests.

Serologic survey of West Nile virus in horses from Central-West, Northeast and Southeast Brazil

Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.

Molecular typing of mycobacteria isolated from extrapulmonary tuberculosis patients at Debre Birhan Referral Hospital, central Ethiopia.

Abstract Background: Extrapulmonary tuberculosis (EPTB) constitutes about 10% to 20% of all cases of tuberculosis in immunocompetent patients and more than 50% of the cases in HIV-positive individuals worldwide. Little information is available on the clonal diversity of Mycobacterium species in Ethiopia from EPTB. Methods: This study was carried out on smear-negative EPTB patients to molecularly characterize Mycobacterium tuberculosis complex strains. A questionnaire, smear staining, culture, deletion typing, and spoligotyping were employed. Results: The proportional distribution of EPTB and isolates did not vary substantially (p > 0.05) amongst the socio-demographic parameters considered in the current investigation. Out of 98 fine needle aspirates processed for culture, 36.7% (36/98) were positive for mycobacterial growth. Further speciation of those culture-positive isolates showed that 88.9% were M. tuberculosis and the remaining could be non-tuberculous mycobacterial species. Spoligotyping revealed 16 clusters out of which 2 were new to the SITVIT database. The most dominant spoligotypes were SIT54, SIT53, and SIT149 in decreasing order. SIT54, SIT134, SIT173, SIT345, SIT357, SIT926, SIT91088, and SIT1580 were reported for the first time in Ethiopia. The family with the highest frequency identified was M. tuberculosis family T1, followed by family 33. Most of the strains belonged to Euro-American (61.4%) and Indo-Oceanic (36.3%) lineages. Conclusions: The present study shows the importance of M. tuberculosis as a major cause of EPTB in the study area. Moreover, the majority of isolates of M. tuberculosis were found in clusters, suggesting the possibility of the existence of recent transmission. This warrants strengthening of the control programs for EPTB in the study area.

New validated prognostic models and prognostic calculators in patients with low-grade gliomas diagnosed by central pathology review: a pooled analysis of EORTC/RTOG/NCCTG phase III clinical trials.

Background In a previous study, the European Organisation for Research and Treatment of Cancer (EORTC) reported a scoring system to predict survival of patients with low-grade gliomas (LGGs). A major issue in the diagnosis of brain tumors is the lack of agreement among pathologists. New models in patients with LGGs diagnosed by central pathology review are needed. Methods Data from 339 EORTC patients with LGGs diagnosed by central pathology review were used to develop new prognostic models for progression-free survival (PFS) and overall survival (OS). Data from 450 patients with centrally diagnosed LGGs recruited into 2 large studies conducted by North American cooperative groups were used to validate the models. Results Both PFS and OS were negatively influenced by the presence of baseline neurological deficits, a shorter time since first symptoms (<30 wk), an astrocytic tumor type, and tumors larger than 5 cm in diameter. Early irradiation improved PFS but not OS. Three risk groups have been identified (low, intermediate, and high) and validated. Conclusions We have developed new prognostic models in a more homogeneous LGG population diagnosed by central pathology review. This population better fits with modern practice, where patients are enrolled in clinical trials based on central or panel pathology review. We could validate the models in a large, external, and independent dataset. The models can divide LGG patients into 3 risk groups and provide reliable individual survival predictions. Inclusion of other clinical and molecular factors might still improve models' predictions.

Synchronous and baroceptor-sensitive oscillations in skin microcirculation: evidence for central autonomic control.

To determine whether skin blood flow is local or takes part in general regulatory mechanisms, we recorded laser-Doppler flowmetry (LDF; left and right index fingers), blood pressure, muscle sympathetic nerve activity (MSNA), R-R interval, and respiration in 10 healthy volunteers and 3 subjects after sympathectomy. We evaluated 1) the synchronism of LDF fluctuations in two index fingers, 2) the relationship with autonomically mediated fluctuations in other signals, and 3) the LDF ability to respond to arterial baroreflex stimulation (by neck suction at frequencies from 0.02 to 0.20 Hz), using spectral analysis (autoregressive uni- and bivariate, time-variant algorithms). Synchronous LDF fluctuations were observed in the index fingers of healthy subjects but not in sympathectomized patients. LDF fluctuations were coherent with those obtained for blood pressure, MSNA, and R-R interval. LDF fluctuations were leading blood pressure in the low-frequency (LF; 0.1 Hz) band and lagging in the respiratory, high-frequency (HF; approximately 0.25 Hz) band, suggesting passive "downstream" transmission only for HF and "upstream" transmission for LF from the microvessels. LDF fluctuations were responsive to sinusoidal neck suction up to 0.1 Hz, indicating response to sympathetic modulation. Skin blood flow thus reflects modifications determined by autonomic activity, detectable by frequency analysis of spontaneous fluctuations.

Localization and characterization of an active fault in an urbanized area in central Guatemala by means of geoelectrical imaging

The Polochic and Motagua faults define the active plate boundary between the North American and Caribbean plates in central Guatemala. A splay of the Polochic Fault traverses the rapidly growing city of San Miguel Uspantan that is periodically affected by destructive earthquakes. This fault splay was located using a 2D electrical resistivity tomography (ERT) survey that also characterized the fault damage zone and evaluated the thickness and nature of recent deposits upon which most of the city is built. ERT images show the fault as a similar to 50 m wide, near-vertical low-resistivity anomaly, bounded within a few meters by high resistivity anomalies. Forward modeling reproduces the key aspects of the observed electrical resistivity data with remarkable fidelity thus defining the overall location, geometry, and internal structure of the fault zone as well as the affected lithologies. Our results indicate that the city is constructed on a similar to 20 m thick surficial layer consisting of poorly consolidated, highly porous, water-logged pumice. This soft layer is likely to amplify seismic waves and to liquefy upon moderate to strong ground shaking. The electrical conductivity as well as the major element chemistry of the groundwater provides evidence to suggest that the local aquifer might, at least in part, be fed by water rising along the fault. Therefore, the potential threat posed by this fault splay may not be limited to its seismic activity per se, but could be compounded its potential propensity to enhance seismic site effects by injecting water into the soft surficial sediments. The results of this study provide the basis for a rigorous analysis of seismic hazard and sustainable development of San Miguel Uspantan and illustrate the potential of ERT surveying for paleoseismic studies.

Genetic diversity and relationship in American and African oil palm as revealed by RFLP and AFLP molecular markers

The objective of this work was to evaluate the genetic diversity, its organization and the genetic relationships within oil palm (Elaeis oleifera (Kunth) Cortés, from America, and E. guineensis (Jacq.), from Africa) germplasm using Restriction Fragment Length Polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP). In complement to a previous RFLP study on 241 E. oleifera accessions, 38 E. guineensis accessions were analyzed using the same 37 cDNA probes. These accessions covered a large part of the geographical distribution areas of these species in America and Africa. In addition, AFLP analysis was performed on a sub-set of 40 accessions of E. oleifera and 22 of E. guineensis using three pairs of enzyme/primer combinations. Data were subjected to Factorial Analysis of Correspondence (FAC) and cluster analysis, with parameters of genetic diversity being also studied. Results appeared congruent between RFLP and AFLP. In the E. oleifera, AFLP confirmed the strong structure of genetic diversity revealed by RFLP, according to geographical origin of the studied material, with the identification of the same four distinct genetic groups: Brazil, French Guyana/Surinam, Peru, north of Colombia/Central America. Both markers revealed that genetic divergence between the two species is of the same magnitude as that among provenances of E. oleifera. This finding is in discrepancy with the supposed early tertiary separation of the two species.

The number of planar central configurations for the 4-body problem is finite when 3 mass positions are fixed

In the n{body problem a central con guration is formed when the position vector of each particle with respect to the center of mass is a common scalar multiple of its acceleration vector. Lindstrom showed for n = 3 and for n > 4 that if n ? 1 masses are located at xed points in the plane, then there are only a nite number of ways to position the remaining nth mass in such a way that they de ne a central con guration. Lindstrom leaves open the case n = 4. In this paper we prove the case n = 4 using as variables the mutual distances between the particles.

On the existence of bi-pyramidal central configurations of the n + 2-body problem with an n-gon base

Abstract. In this paper we prove the existence of central con gurations of the n + 2{body problem where n equal masses are located at the vertices of a regular n{gon and the remaining 2 masses, which are not necessarily equal, are located on the straight line orthogonal to the plane containing the n{gon passing through its center. Here this kind of central con gurations is called bi{pyramidal central con gurations. In particular, we prove that if the masses mn+1 and mn+2 and their positions satisfy convenient relations, then the con guration is central. We give explicitly those relations.

Mesozoic oceanic terranes of southern Central America : geology, geochemistry and gedynamics

Abstract The Northwestern edge of the modern Caribbean Plate, located in central Middle America (S-Guatemala to N-Costa Rica), is characterized by a puzzle of oceanic and continental terranes that belonged originally to the Pacific façade of North America. South of the Motagua Fault Zone, the actual northern strike slip boundary of the Caribbean Plate, three continental slivers (Copán, Chortis s. str. and Patuca) are sandwiched between two complex suture zones that contain HP/LT mafic and ultramafic oceanic rocks: The Motagua Mélanges to the North, extensively studied in the last ten years and the' newly defined Mesquito Composite Oceanic Terrane (MCOT) to the South. No modem geological data were available for the oceanic terrane located in the southern part of the so called continental "Chortis Block". Classically, the southern limit of this block with the Caribbean Large Igneous Province (CLIP) was placed at a hypothetical fault line connecting the main E-W fault in the Santa Elena Peninsula (N-Costa Rica) with the Hess Escarpment. However, our study in eastern Nicaragua and northwestern Costa Rica evidences an extensive assemblage of oceanic upper mantle and crustal rocks outcropping between the Chortis/Patuca continental blocks and the CLIP. They comprise collided and accreted exotic terranes of Pacific origin recording a polyphased tectonic history. We distinguish: 1- The MCOT that comprises a Late Triassic to Early Cretaceous puzzle of oceanic crust and arc-derived rocks set in a serpentinite matrix, and 2- The Manzanillo and Nicoya Terranes that are made of Cretaceous plateau-like rocks associated with oceanic sediments older than the CLIP. This study has been focused on the rocks of the MCOT. The MCOT comprises the southern half of the former "Chortis Block" and is defined by 4 comer localities characterized by ultramafic and mafic oceanic rocks of Late Triassic, Jurassic and Early Cretaceous age: 1- The Siuna Serpentinite Mélange (NE-Nicaragua), 2- The El Castillo Mélange (Nicaragua/Costa Rica border), 3- DSDP Legs 67 and 84 (Guatemala fore-arc basin), and 4- The Santa Elena Peridiotite (NW-Costa Rica). The Siuna Serpentinite Mélange (SSM) is a HP/LT subduction zone mélange set in a serpentinite matrix that contains oceanic crust and arc-related greenschist to blueschist/eclogite facies metamafic and metasedimentary blocks. Middle Jurassic (Bajocian-Bathonian) radiolarites are found in original sedimentary contact with arc-derived greenstones. Late Jurassic black detrital chert possibly formed in a marginal (fore-arc?) basin shortly before subduction. A phengite 40Ar/39Ar -cooling age dates the exhumation of the high pressure rocks as 139 Ma. The El Castillo Mélange (ECM) is composed of serpentinite matrix with OIB metabasalts and Late Triassic (Rhaetian) red and green radiolarite blocks. Recent studies of the DSDP Legs 67/84 show that the Guatemala/Nicaragua fore-arc basin is composed of a pile of ultramafic, mafic (OIB-like) and arc related rocks with ages ranging from Late Triassic to Campanian. Finally, the Santa Elena peridiotites that mark the limit of the MCOT with the Manzanillo/Nicoya Terranes and correspond to an association of ultramafic rocks that comprise peridiotites, dunites and chromites of abyssal and fore-arc origin. The SSM is the result of a collision between a Middle Jurassic island arc and the Patuca Terrane, a fragment of the Western N-American active continental margin. The Siuna Mélange (SSM) and the South Montagna Mélange share common characteristics with the Pacific N-American suture zone (E-Franciscan and Vizcaino mélanges), in particular, the Mesozoic ages of HP/LT metamorphic and the arc-derived blocks. For us, these mélanges imply an originally continuous, but slightly diachronous suture that affected the entire W-American active margin. It may imply the arrival and collision of an exotic intraoceanic arc (Guerrero-Phoenix) related to the origin of the Pacific Plate that initiated as a back arc basin of this arc. The present disposition of the fragments of this suture zone is the result of a northward shift of the active left-lateral strike slip motion between the N-American and the Caribbean Plates. Résumé Le coin nord-ouest de la Plaque Caraïbe moderne se trouve en Amérique Centrale, entre le sud du Guatemala et le nord du Costa Rica. Cette région est composée d'un puzzle de terrains océaniques et continentaux dont les origines se situent sur la façade pacifique de l'Amérique du Nord. Au sud de la faille de Motagua, la limite septentrionale actuelle, décrochante, de la Plaque Caraïbe, se trouvent 3 copeaux continentaux (Copàn, Chortis s. str. et Patuca) coincés entre deux zones de suture complexes à roches mafiques et ultramafiques qui ont subi un métamorphisme de haute pression/basse température (HP/LT). Il s'agit des Mélanges de Motagua au nord, largement étudiés ces dernières années, et du Mesquito Composite Oceanic Terrane (MCOT), récemment défini par nous, au sud. En vue de l'absence de données géologiques modernes concernant les terrains océaniques qui se trouvent dans la partie sud du "Chortis Block" considérée comme continentale, nous avons dédié cette étude à cette région. Classiquement, la limite méridionale entre le "Chortis Block" et la "Caribbean Large Igneous Province" (CLIP) a été associée à une faille hypothétique reliant la faille E-W de Santa Elena (nord du Costa Rica) à l'Escarpement de Hess. Notre étude au Nicaragua oriental et au Costa Rica nord-occidental a révélé l'existence de larges terrains composés d'assemblages de roches mantéliques et océaniques qui se placent entre les blocs continentaux Chortis/Patuca et le CLIP. Ces assemblages révèlent des terrains collisionnés et accrétés d'origine pacifique enregistrant une histoire tectonique polyphasée. Nous distinguons: 1- Le MCOT, un puzzle de roches océaniques d'arc d'âge Triassique supérieur au Crétacée inférieur, 2- Les terrains de Manzanillo et de Nicoya, des morceaux de plateaux océaniques associés à des sédiments océaniques plus âgés que le CLIP. Cette étude se focalisera sur les roches du MCOT. Le MCOT occupe la moitié sud de l'ancien "Chortis Block" et peut se définir par 4 localités de référence qui montrent des roches mafiques et ultramafiques océaniques d'âges compris entre le Trias supérieur et le Crétacée inférieur. 1- Le Siuna Serpentinite Mélange (NE-Nicaragua), 2- Le El Castillo Mélange (Nicaragua/Costa Rica border), 3- Le DSDP Legs 67/84 (Guatemala fore-arc basin) et 4- La Santa Elena Peridiotite (nord-ouest du Costa Rica). Le Siuna Serpentinite Mélange (SSM) est un mélange de subduction HP/BT dans une matrice de serpentinite. On y trouve des éléments de croûte océanique et d'arc insulaire en faciès de schistes verts et schistes bleus. Des radiolarites du Jurassique moyen se trouvent en contact sédimentaire sur des roches vertes d'arc. En revanche, des cherts noirs détritiques datent du Jurassique supérieur et sont probablement issus d'un bassin marginal (fore-arc ?) peu avant leur subduction, car un âge 40Ar/39Ar de refroidissement des phengites date l'exhumation des roches de haute pression à 139 Ma. Le Mélange d'El Castillo (ECM) est constitué d'une matrice serpentinitique et contient des blocs de metabasaltes OIB et des blocs de radiolarites du Trias terminal. Des études récentes ont repris les roches forées lors des DSDP Legs 67 et 84 et montrent que le soubassement du bassin d'avant-arc du Guatemala-Nicaragua est composé de roches ultramafiques et mafiques (OIB et arc), dont les âges isotopiques vont du Trias au Crétacé supérieur. Finalement, les péridiotites de Santa Elena forment la limite sud du MCOT par rapport aux terrains de Manzanillo et Nicoya. Elles contiennent des serpentinites et localement des dunites et chromites à affinité abyssale et de fore-arc. Le SSM témoigne d'une collision entre un arc insulaire d'âge Jurassique moyen et le Patuca Terrane, un fragment de la marge active nord-américaine. Le SSM et le South Motagua Mélange ont des caractéristiques en commun avec les zones de suture de la façade pacifique de l'Amérique du nord (E-Franciscan et Vizcaino mélanges), notamment les âges Mésozoïques du métamorphisme HP/BT et les blocs de roches d'arc. Ce fait nous conduit à penser qu'il s'agit d'une grande zone de suture qui était à l'origine continue sur toute la marge ouest-américaine, mais légèrement diachrone. Cette suture implique l'arrivée et la collision d'un arc intraocéanique exotique (Guerrero-Phoenix) qui est à l'origine de la Plaque Pacifique qui s'ouvrait en back arc par rapport à celui-ci. La disposition actuelle des fragments de cette suture est due à la migration vers le nord du décrochement actif senestre entre la Plaque nord-américaine et la Plaque Caraïbe. K. Flores, 2009 Mesozoic oceanic terranes of southern central America Résumé Grand Public La présente thèse est le résultat de travaux de terrain effectués de 2005 à 2008 au nord-est et au sud du Nicaragua et au nord du Costa Rica, en Amérique Centrale, des analyses pétrologiques et géochimiques en laboratoire ainsi que de la modélisation de l'évolution géodynamique. La région étudiée se situe en bordure nord - ouest de la Plaque Caraïbe moderne. Dans la majorité des publications récentes cette région est représentée comme un vaste bloc continental (le "Bloc Chortis") qui serait limité, (i) au nord, par la faille décrochante de Motagua, la limite actuelle entre la Plaque Nord-Américaine et la Plaque Caraïbe, et (ii) au sud, par une suture hypothétique qui se trouverait aux confins entre le Nicaragua et le Costa Rica. La région du Costa Rica a été considérée presque entièrement comme une partie du Plateau Caraïbe ("Caribbean Large Igneous Province" (CLIP)). L'étude détaillée des affleurements nous a permis de mettre en évidence : - Au nord-est du Nicaragua (Siuna) : Des roches océaniques datées du Jurassique moyen, grâce aux faunes à radiolaires qui ont été extraites des radiolarites rouges. Ces roches ont subi un métamorphisme de haute pression typique des zones de collision. L'étude radio-isotopique Ar/Ar a permis de dater la collision du Crétacé basal (139 Ma). - Au sud du Nicaragua : Des roches océaniques d'âge Trias terminal (200 millions d'années), également datées à l'aide de faunes à radiolaires. Il s'agit actuellement des roches océaniques les plus anciennes connues de l'Amérique Centrale. - L'étude géochimique et les âges des fossiles démontrent que le tiers septentrional du Costa Rica possède un soubassement construit d'au moins deux terrains (Nicoya et Manzanillo), qui ont des caractéristiques de Plateau océanique (Nicoya) et d'arc volcanique du Crétacé moyen (Manzanillo). Ces deux terrains sont plus anciens que le CLIP. En conclusion, nous constatons que la région étudiée est constituée d'un puzzle de 3 blocs continentaux et d'un vaste terrain océanique composite que nous appelons Mesquito Composite Oceanic Terrane (MCOT). En plus, nous définissons les terrains de Nicoya et de Manzanillo comme plus âgés et distincts du CLIP. Le MCOT est caractérisé par la présence de roches du manteau supérieur (les serpentinites) et de la croûte océanique, ainsi que des morceaux d'arcs, d'âge allant du Trias supérieur au Crétacé. Ce terrain est comparable à d'autres zones de suture de la façade pacifique de l'Amérique du nord, notamment en ce qui concerne les âges Mésozoïques, le métamorphisme de haute pression et l'association de roches mantéliques et crustales océaniques. Ce fait nous conduit à penser qu'il s'agit d'une grande zone de suture qui était à l'origine continue sur toute la marge ouest-américaine. Cette suture implique l'arrivée et la collision d'un arc infra-océanique exotique qui serait à l'origine de la Plaque Pacifique qui se serait ouverte en bassin d'arrière arc par rapport à celui-ci. La disposition actuelle des fragments de cette suture est due à la migration vers le nord du décrochement actif senestre entre la Plaque nord-américaine et la Plaque Caraïbe.

Comparison of central macular thickness (CMT) measurement between time domain and spectral domain (SD) optical coherence tomography (OCT) and reproducibility of SD OCT in active neovascular AMD

Purpose: To evaluate the reproducibility of Cirrus-SD OCT measurements and to compare central macular thickness (CMT) measurements between TD-Stratus and SD-Cirrus OCT in patients with active exudative AMD. Methods: Consecutive case series of patients with active exudative AMD seen in the Medical Retina Department. Patients underwent 1 scan with Stratus (macular thickness map protocol) and 5 scans with Cirrus (Macular Cube protocol) at the same visit by the same experienced examiner. To be included, patients best-corrected visual acuity (BCVA) had to be >20/200 while all scans had to be of sufficient quality, well-centered and at least one Cirrus scan with CMT >300 microns. The repeatability of the SD Cirrus was estimated by using all 5 CMT measurements and the mean of the Cirrus measurements was compared with the CMT obtained by TD Stratus. Results: Cirrus OCT demonstrated high intraobserver repeatability at the central foveal region (ICC 96%). The mean of the CMT measurements was 321microns for Stratus and 387 microns for Cirrus. The average difference was 65m (SD=30). The coefficient of concordance between Stratus and Cirrus CMT measurements was rho=0,749 with a high precision and a moderate accuracy. The equation of the line of regression between Stratus and meanCirrus is given by the following: M_stratus = 0,848 x m_cirrus - 4,496 (1).Conclusions: The Cirrus macular cube protocol allows reproducible CMT measurements in patients with active exudative AMD. In cases of upgrading from TD to SD use and vice versa, there is the possibility to predict the measurements by using the equation (1). These real life data and conclusions can help in improving our clinical management of patients with neovascular AMD.

Grx5 glutaredoxin plays a central role in protection against protein oxidative damage in Saccharomyces cerevisiae

Glutaredoxins are members of a superfamily of thiol disulfide oxidoreductases involved in maintaining the redox state of target proteins. In Saccharomyces cerevisiae, two glutaredoxins (Grx1 and Grx2) containing a cysteine pair at the active site had been characterized as protecting yeast cells against oxidative damage. In this work, another subfamily of yeast glutaredoxins (Grx3, Grx4, and Grx5) that differs from the first in containing a single cysteine residue at the putative active site is described. This trait is also characteristic for a number of glutaredoxins from bacteria to humans, with which the Grx3/4/5 group has extensive homology over two regions. Mutants lacking Grx5 are partially deficient in growth in rich and minimal media and also highly sensitive to oxidative damage caused by menadione and hydrogen peroxide. A significant increase in total protein carbonyl content is constitutively observed in grx5cells, and a number of specific proteins, including transketolase, appear to be highly oxidized in this mutant. The synthetic lethality of the grx5 and grx2 mutations on one hand and ofgrx5 with the grx3 grx4 combination on the other points to a complex functional relationship among yeast glutaredoxins, with Grx5 playing a specially important role in protection against oxidative stress both during ordinary growth conditions and after externally induced damage. Grx5-deficient mutants are also sensitive to osmotic stress, which indicates a relationship between the two types of stress in yeast cells.

Radio Imaging of the Very-High-Energy γ-Ray Emission Region in the Central Engine of a Radio Galaxy

The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 1012 electron volts and are bright sources of very-high-energy (VHE) γ-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE γ-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

An Alternative American Approach to Repositories

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014