Immunodominant antigens of Leishmania chagasi associated with protection against human visceral leishmaniasis

Background

Protection and recovery from visceral leishmaniasis (VL) have been associated with cell-mediated immune (CMI) responses, whereas no protective role has been attributed to humoral responses against specific parasitic antigens. In this report, we compared carefully selected groups of individuals with distinct responses to Leishmania chagasi to explore antigen-recognizing IgG present in resistant individuals.

Methodology and Principal Findings

VL patients with negative delayed-type hypersensitivity (DTH) were classified into the susceptible group. Individuals who had recovered from VL and converted to a DTH+ response, as well as asymptomatic infected individuals (DTH+), were categorized into the resistant group. Sera from these groups were used to detect antigens from L. chagasi by conventional and 2D Western blot assays. Despite an overall reduction in the reactivity of several proteins after DTH conversion, a specific group of proteins (approximately 110–130 kDa) consistently reacted with sera from DTH converters. Other antigens that specifically reacted with sera from DTH+ individuals were isolated and tandem mass spectrometry followed by database query with the protein search engine MASCO were used to identify antigens. The serological properties of recombinant version of the selected antigens were tested by ELISA. Sera from asymptomatic infected people (DTH+) reacted more strongly with a mixture of selected recombinant antigens than with total soluble Leishmania antigen (SLA), with less cross-reactivity against Chagas disease patients'' sera.

Significance

Our results are the first evidence of leishmania proteins that are specifically recognized by sera from individuals who are putatively resistant to VL. In addition, these data highlight the possibility of using specific proteins in serological tests for the identification of asymptomatic infected individuals.     

Hydrolase-catalysed synthesis of peroxycarboxylic acids: Biocatalytic promiscuity for practical applications

The enzymatic promiscuity concept involves the possibility that one active site of an enzyme can catalyse several different chemical transformations. A rational understanding of the mechanistic reasons for this catalytic performance could lead to new practical applications. The capability of certain hydrolases to perform the perhydrolysis was described more than a decade ago, and recently its molecular basis has been elucidated. Remarkably, a similarity between perhydrolases (cofactor-free haloperoxidases) and serine hydrolases was found, with both groups of enzymes sharing a common catalytic triad, which suggests an evolution from a common ancestor. On the other hand, several biotechnological applications derived from the capability of hydrolases to catalyse the synthesis of peracids have been reported: the use of hydrolases as bleaching agents via in situ generation of peracids; (self)-epoxidation of unsaturated fatty acids, olefins, or plant oils, via Prileshajev epoxidation; Baeyer-Villiger reactions. In the present review, the molecular basis for this promiscuous hydrolase capability, as well as identified applications are reviewed and described in detail.     

Self-aggregation of free base porphyrins in aqueous solution and in DMPC vesicles

Free base porphyrin (PPhe), derivatized with aminosulfonyl groups linked to the aromatic amino acid phenylalanine at the meso-positions, was mixed with DMPC vesicles. The resulting interaction was studied by absorption, steady-state and transient state fluorescence, at different pHs. At pH=2 to pH=9, the aforementioned porphyrin predominates as an aggregated species, with a co-facial arrangement of the molecules taking into account the blue shift of the Soret band (414 nm for the monomer and 401 nm for the aggregate). Upon interaction with DMPC vesicles, the competing hydrophobic interactions with the bilayer destabilize the aggregated species in favor of monomer incorporation. Fluorescence lifetimes also show that the long component assigned to the monomer contributes only 30% to the overall decay in solution (e.g. pH=7.0) whereas in DMPC vesicles this contribution increases up to 85% independent of the solution pH, which confirms a location of the probe in an environment "protected" from free water. The picture changes completely in the case of TSPP, an anionic porphyrin which does not incorporate in DMPC vesicles. Remarkably, at pH=2.5 all the experimental findings point to the self-assembling of the porphyrin units in J-aggregates induced at the surface of the DMPC vesicle. In fact, upon removal of the aqueous solvent, we could define by fluorescence lifetime imaging microscopy (FLIM) regions where the fluorescence lifetime is that characteristic of the J-aggregate ( 0.11 ns).     

Serologic survey for selected viral pathogens in free-ranging endangered European mink (Mustela lutreola) and other mustelids from south-western France

To investigate the possible role of selected pathogens in the decline of endangered European mink (Mustela lutreola) populations and the potential for these pathogens to affect mink survival, a serologic survey was conducted using serum samples collected from March 1996 to March 2003 in eight departments of south-western France. In total, 481 free-ranging individuals of five mustelid species (including the European mink) were tested. Sympatric mustelids can serve as sentinels to determine the presence of antibodies to viruses in the study area that could potentially infect mink. Antibodies to Canine distemper virus (CDV) were detected in all species; 9% of 127 European mink, 20% of 210 polecats (Mustela putorius), 5% of 112 American mink (Mustela vison), 33% of 21 stone marten (Martes foina) and 5% of 20 pine marten (Martes martes). Antibody prevalence was significantly higher in stone marten and polecats, possibly because their ranges overlap more closely with that of domestic species than that of the other species tested. Antibodies to Canine adenovirus were detected in all species but the pine marten; antibody prevalence estimates ranging from 2% to 10%. Antibodies to canine parainfluenza virus were detected in 1% of European mink, 1% of American mink and 5% of tested polecats but were not detected in Martes species. Antibodies to Rabies virus (RV) were detected in three animals, possibly because of interspecies transmission of bat lyssaviruses as the sampling area is considered to be free of RV, or to a lack of test specificity, as antibody titers were low. The high antibody prevalence to potentially lethal CDV suggests that this pathogen could have significant effects on the free-ranging populations and has implications for the conservation efforts for the endangered European mink.     

Integrating biogeography,threat and evolutionary data to explore extinction crisis in the taxonomic group of cycads

Will the ongoing extinction crisis cause a severe loss of evolutionary information accumulated over millions of years on the tree of life? This question has been largely explored, particularly for vertebrates and angiosperms. However, no equivalent effort has been devoted to gymnosperms. Here, we address this question focusing on cycads, the gymnosperm group exhibiting the highest proportion of threatened species in the plant kingdom. We assembled the first complete phylogeny of cycads and assessed how species loss under three scenarios would impact the cycad tree of life. These scenarios are as follows: (1) All top 50% of evolutionarily distinct (ED ) species are lost; (2) all threatened species are lost; and (3) only all threatened species in each IUCN category are lost. Finally, we analyzed the biogeographical pattern of cycad diversity hotspots and tested for gaps in the current global conservation network. First, we showed that threatened species are not significantly clustered on the cycad tree of life. Second, we showed that the loss of all vulnerable or endangered species does not depart significantly from random loss. In contrast, the loss of all top 50% ED , all threatened or all critically endangered species, would result in a greater loss of PD (Phylogenetic Diversity) than expected. To inform conservation decisions, we defined five hotpots of diversity, and depending on the diversity metric used, these hotspots are located in Southern Africa, Australia, Indo‐Pacific, and Mexico and all are found within protected areas. We conclude that the phylogenetic diversity accumulated over millions of years in the cycad tree of life would not survive the current extinction crisis. As such, prioritizing efforts based on ED and concentrating efforts on critically endangered species particularly in southern Africa, Australia, Indo‐Pacific, and Mexico are required to safeguarding the evolutionary diversity in the cycad tree of life.     

Advances in proteomic technologies and their scope of application in understanding plant–pathogen interactions

Proteomics, one of the major tools of ‘omics’ is evolving phenomenally since the development and application of two-dimensional gel electrophoresis coupled with mass spectrometry at the end of twentieth century. However, the adoption and application of advanced proteomic technologies in understanding plant–pathogen interactions are far less, when compared to their application in other related fields of systems biology. Hence, this review is diligently focused on the advances in various proteomic approaches and their gamut of applications in different facets of phyto-pathoproteomics. Especially, the scope and application of proteomics in understanding fundamental concepts of plant–pathogen interactions such as identification of pathogenicity determinants (effector proteins), disease resistance proteins (resistance and pathogenesis-related proteins) and their regulation by post-translational modifications have been portrayed. This review, for the first time, presents a critical appraisal of various proteomic applications by assessing all phyto-pathoproteomics-related research publications that were published in peer-reviewed journals, during the period 2000–2016. This assessment has revealed the present status and contribution of proteomic applications in different categories of phyto-pathoproteomics, namely, cellular components, host–pathogen interactions, model and non-model plants, and utilization of different proteomic approaches. Comprehensively, the analysis highlights the burgeoning application of global proteome approaches in various crop diseases, and demand for acceleration in deploying advanced proteomic technologies to thoroughly comprehend the intricacies of complex and rapidly evolving plant–pathogen interactions.     

Is succession in wet calcareous dune slacks affected by free sulfide?

Abstract. Consequences of sulfide toxicity on succession in wet calcareous dune slacks were investigated. Sulfide may exert an inhibitory effect on dune slack plants, but several pioneer species exhibit ROL (Radial Oxygen Loss) and thereby protect themselves against free sulfide. Under oxic conditions free sulfide will be oxiginated to harmless sulfate. However, successive species when not capable of ROL may be sensitive to free sulfide and cannot invade the area. Therefore, the occurrence of free sulfide may have a stabilizing effect on the pioneer vegetation. Data on the vertical distribution of oxygen, redox and sulfide were collected in mesocosms with Littorella uniflora or Carex nigra, with and without microbial mats and compared to control mesocosms. Also, in situ data were collected in a dune slack on the Frisian Island of Texel. In the mesocosms, free sulfide was detected only at nighttime in C. nigra populated mesocosms and in unvegetated units, but not in L. uniflora vegetated mesocosms. In the field, sulfide and redox profiles showed distinct differences between the groundwater exfiltration and infiltration site of the dune slack. At the exfiltration site, sulfide was only occasionally found; in contrast, measurable amounts of free sulfide were regularly found at the infiltration site of the slack. Since Phragmites australis dominates in the infiltration site of the slack, the results suggest that free sulfide accelerate the succession, rather than slowing it down by the exclusion of some plant species.     

Thyroid volume as measured by ultrasonography in patients With type 1 diabetes mellitus without thyroid dysfunction.

The aim of this cross-sectional study was to assess and compare thyroid volume and its derminants in a cohort of type 1 diabetes mellitus (DM1) and compare the results to a healthy control group. We studied 65 DM1 patients treated with an intensive insulin regimen and 65 matched controls. In all participants we evaluated weight, height, BMI, waist-hip ratio, body surface area and body composition variables determined by using a bioelectrical impedance analyser. Thyroid size was estimated by ultrasonography. We determined basal TSH, anti-thyroid antibodies and urinary iodine excretion. Body weight, height, BMI and body surface area were similar in DM1 patients and in controls. Fat-free mass was higher in both male and female DM1 patients than in controls (64.4 +/- 6.9 vs. 60.4 +/- 8.2 kg, p=0.03 and 48.3 +/- 5.7 vs. 45.4 +/- 6, p=0.04, respectively), and fat mass was lower in male DM1 patients than in controls (9.7 +/- 7 vs. 14.2 +/- 8.1 kg, p=0.01). Thyroid volume was greater in both male and female DM1 patients than in controls (11.12 +/- 2.87 vs. 9.63 +/- 2.27 ml, p=0.0001 and 9.5 +/- 2.3 vs. 7.7 +/- 2 ml, p=0.002, respectively). Urinary iodine excretion was similar in the two groups. In both DM1 patients and controls, thyroid volume correlated with weight, height, BMI, waist-hip ratio, body surface area, fat-free mass and the multivariate linear regression analysis with thyroid volume as the dependent variable showed that fat-free mass in either group was the only significant determinant of thyroid volume. We conclude that DM1 patients had larger thyroid volume compared with healthy controls with similar anthropometry; body composition is different in DM1 patients and that the anthropometric and body composition variables, especially fat-free mass and body surface area, predict thyroid volume either in DM1 patients or in healthy controls.