Comprehensive proteomic profiling of adult Angiostrongylus costaricensis, a human parasitic nematode

Angiostrongylus costaricensis is a nematode helminth that causes an intestinal acute inflammatory process known as abdominal angiostrongyliasis, which is a poorly understood human disease occurring in Latin America. Our aim was to study the proteomic profiles of adult parasites focusing on immunogenic proteins. Total cellular extracts from both genders showed similar 2-DE profiles, with 60% of all protein spots focused between pH 5-7 and presenting molecular masses from 20.1 to 66 kDa. A total of 53 different dominant proteins were identified in our dataset and were mainly associated with the following over-represented Gene Ontology Biological Process terms: "macromolecule metabolic process", "developmental process", "response to stress", and "biological regulation". Female and male immunoblots showed similar patterns of reactive proteins. Immunoreactive spots identified by MALDI-PSD were found to represent heat shock proteins, a putative abnormal DAuer Formation family member, and galectins. To date, very few biochemical analyses have focused on the nematode Angiostrongylus costaricensis. As such, our results contribute to a better understanding of its biology and the mechanisms underlying the host-parasite relationship associated with this species. Moreover, our findings represent a first step in the search for candidate proteins for diagnostic assays and the treatment of this parasitic infection.     

Characterization of an RNase with two catalytic centers. Human RNase6 catalytic and phosphate-binding site arrangement favors the endonuclease cleavage of polymeric substrates

Background

Human RNase6 is a small cationic antimicrobial protein that belongs to the vertebrate RNaseA superfamily. All members share a common catalytic mechanism, which involves a conserved catalytic triad, constituted by two histidines and a lysine (His15/His122/Lys38 in RNase6 corresponding to His12/His119/Lys41 in RNaseA). Recently, our first crystal structure of human RNase6 identified an additional His pair (His36/His39) and suggested the presence of a secondary active site.

The transmembrane domain of podoplanin is required for its association with lipid rafts and the induction of epithelial-mesenchymal transition

Podoplanin is a transmembrane glycoprotein that is upregulated in cancer and was reported to induce an epithelial-mesenchymal transition (EMT) in MDCK cells. The promotion of EMT was dependent on podoplanin binding to ERM (ezrin, radixin, moesin) proteins through its cytoplasmic (CT) domain, which led to RhoA-associated kinase (ROCK)-dependent ERM phosphorylation. Using detergent-resistant membrane (DRM) assays, as well as transmembrane (TM) interactions and ganglioside GM1 binding, we present evidence supporting the localization of podoplanin in raft platforms important for cell signalling. Podoplanin mutant constructs harbouring a heterologous TM region or lacking the CT tail were unable to associate with DRMs, stimulate ERM phosphorylation and promote EMT or cell migration. Similar effects were observed upon disruption of a GXXXG motif within the TM domain, which is involved in podoplanin self-assembly. In contrast, deletion of the extracellular (EC) domain did not affect podoplanin DRM association. Together, these data suggest that both the CT and TM domains are required for podoplanin localization in raft platforms, and that this association appears to be necessary for podoplanin-mediated EMT and cell migration.     

Experiencia con el uso del registrador implantable de eventos en una serie de personas mayores con caídas y sospecha de síncopes de origen arrítmico

Objective

To review our experience on using an implantable loop recorder (ILR) in patients with recurrent falls, when an arrhythmogenic cause is suspected.

Material and methods

This is a retrospective, observational study of patients with repetitive unexplained falls, suspected syncope, or electrocardiographic abnormalities. All of them had been evaluated by a cardiologist, who decided to implant a loop recorder (ILR) for an accurate diagnosis.

Results

A total of 13 patients received an ILR. The average falls rate for the sample was 3.3. The mean age was 78 years, and 46% were female, with a mean follow-up period of 24 months. During this time, three patients did not suffer from a new fall. An arrhythmogenic diagnosis was obtained in 5 patients: bradycardia was identified in 4 cases, and tachycardia in one of them. The symptoms did not coincide with a documented arrhythmia in the rest of the patients.

Conclusion

ILR is a helpful tool to establish an arrhythmogenic cause of unexplained and recurrent falls, in this selected sample of older adults.     

Comparative Phenomenology of Ataques de Nervios,Panic Attacks,and Panic Disorder

This article examines a clinicalsample of 66 Dominican and Puerto Ricansubjects who reported ataques de nerviosand also psychiatric disorder, and disentanglesthe phenomenological experiences of ataquede nervios, panic attacks, and panic disorder. In-depth cultural interviews assessed thesymptomatic phenomenology of ataqueepisodes from the local perspective as well asin terms of key panic features, such asrecurrence, rapid peaking of symptoms, and lackof provocation. Independent diagnosticassessments of panic attacks and disorder werealso used to establish the phenomenologicaloverlap between ataque and panic. Ourfindings indicate that 36 percent ofataques de nervios fulfill criteria for panicattacks and between 17 percent and 33 percentfor panic disorder, depending on the overlapmethod used. The main features distinguishingataques that fulfill panic criteria fromataques that do not include whether theepisodes were provoked by an upsetting event inthe person's life and the rapidity of crescendoof the actual attack. A key finding is thatataques often share individualphenomenological features with panic episodes,but that these features usually do not ``runtogether' during the ataque experience.This confirms previous findings thatataque is a more inclusive construct thanpanic disorder. The importance of thesefindings for the clinical diagnosis andtreatment of persons with ataques isdiscussed.     

Life history of Amblyseius herbicolus (Chant) (Acari: Phytoseiidae) on coffee plants

The predaceous mite Amblyseius herbicolus (Chant) is the second most abundant phytoseiid on coffee plants (Coffea arabica L), after Euseius alatus DeLeon, in Lavras, MG, Brazil, associated to the vector of the coffee ring spot virus, Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae). Its life history was studied taking into account biological aspects, life table, predatory activity and functional and numerical responses in relation to the density of the prey. The adult female has longevity of 38 days when supplied with B. phoenicis. The intrinsic rate of population increase (r m) was 0.150 and the mean generation time (T) 25.3 days. The population doubles every 4.6 days. Thirty mites B. phoenicis /3-cm diameter coffee leaf arenas were separately offered to one specimen of each predator phase. Adult females were more efficient in killing all developmental phases of B. phoenicis, followed by the nymph stages. For the functional and numerical responses studies, from 0.14 to 42.3 immature specimens of the prey /cm(2) of arena were submitted to the predator, the preferred phase for predation. Predation and the oviposition of A. herbicolus increased with increasing prey density, with a positive and highly significant correlation. Regression analysis suggests a functional type II response, with a maximum daily predation near 35 B. phoenicis /cm(2) /one adult female.     

Role for Rhizobium rhizogenes K84 cell envelope polysaccharides in surface interactions

Rhizobium rhizogenes strain K84 is a commercial biocontrol agent used worldwide to control crown gall disease. The organism binds tightly to polypropylene substrate and efficiently colonizes root surfaces as complex, multilayered biofilms. A genetic screen identified two mutants in which these surface interactions were affected. One of these mutants failed to attach and form biofilms on the abiotic surface although, interestingly, it exhibited normal biofilm formation on the biological root tip surface. This mutant is disrupted in a wcbD ortholog gene, which is part of a large locus predicted to encode functions for the biosynthesis and export of a group II capsular polysaccharide (CPS). Expression of a functional copy of wcbD in the mutant background restored the ability of the bacteria to attach and form normal biofilms on the abiotic surface. The second identified mutant attached and formed visibly denser biofilms on both abiotic and root tip surfaces. This mutant is disrupted in the rkpK gene, which is predicted to encode a UDP-glucose 6-dehydrogenase required for O-antigen lipopolysaccharide (LPS) and K-antigen capsular polysaccharide (KPS) biosynthesis in rhizobia. The rkpK mutant from strain K84 was deficient in O-antigen synthesis and exclusively produced rough LPS. We also show that strain K84 does not synthesize the KPS typical of some other rhizobia strains. In addition, we identified a putative type II CPS, distinct from KPS, that mediates cell-surface interactions, and we show that O antigen of strain K84 is necessary for normal cell-cell interactions in the biofilms.     

Deep Sequencing of HIV-1 near Full-Length Proviral Genomes Identifies High Rates of BF1 Recombinants Including Two Novel Circulating Recombinant Forms (CRF) 70_BF1 and a Disseminating 71_BF1 among Blood Donors in Pernambuco,Brazil

Background

The findings of frequent circulation of HIV-1 subclade F1 viruses and the scarcity of BF1 recombinant viruses based on pol subgenomic fragment sequencing among blood donors in Pernambuco (PE), Northeast of Brazil, were reported recently. Here, we aimed to determine whether the classification of these strains (n = 26) extends to the whole genome sequences.

Methods

Five overlapping amplicons spanning the HIV near full-length genomes (NFLGs) were PCR amplified from peripheral blood mononuclear cells (PBMCs) of 26 blood donors. The amplicons were molecularly bar-coded, pooled, and sequenced by Illumina paired-end protocol. The prevalence of viral variants containing drug resistant mutations (DRMs) was compared between plasma and PBMCs.

Results

Of the 26 samples studied, 20 NFLGs and 4 partial fragments were de novo assembled into contiguous sequences and successfully subtyped. Two distinct BF1 recombinant profiles designated CRF70_BF1 and CRF71_BF1, with 4 samples in profile I and 11 in profile II were detected and thus constitute two novel recombinant forms circulating in PE. Evidence of dual infections was detected in four patients co-infected with distinct HIV-1 subtypes. According to our estimate, the new CRF71_BF1 accounts for 10% of the HIV-1 circulating strains among blood donors in PE. Discordant data between the plasma and PBMCs-virus were found in 15 of 24 donors. Six of these strains displayed major DRMs only in PBMCs and four of which had detectable DRMs changes at prevalence between 1-20% of the sequenced population.

Conclusions

The high percentage of the new RF71_BF1 and other BF1 recombinants found among blood donors in Pernambuco, coupled with high rates of transmitted DRMs and dual infections confirm the need for effective surveillance to monitor the prevalence and distribution of HIV variants in a variety of settings in Brazil.     

Viral SPP1 DNA is infectious in naturally competent Bacillus subtilis cells: inter- and intramolecular recombination pathways

A proteolyzed bacteriophage (phage) might release its DNA into the environment. Here, we define the recombination functions required to resurrect an infective lytic phage from inactive environmental viral DNA in naturally competent Bacillus subtilis cells. Using phage SPP1 DNA, a model that accounts for the obtained data is proposed (i) the DNA uptake apparatus takes up environmental SPP1 DNA, fragments it, and incorporates into the cytosol different linear single-stranded (ss) DNA molecules shorter than genome-length; (ii) the SsbA-DprA mediator loads RecA onto any fragmented linear SPP1 ssDNA, but negative modulators (RecX and RecU) promote a net RecA disassembly from these ssDNAs not homologous to the host genome; (iii) single strand annealing (SSA) proteins, DprA and RecO, anneal the SsbA- or SsbB-coated complementary strands, yielding tailed SPP1 duplex intermediates; (iv) RecA polymerized on these tailed intermediates invades a homologous region in another incomplete molecule, and in concert with RecD2 helicase, reconstitutes a complete linear phage genome with redundant regions at the ends of the molecule; and (v) DprA, RecO or viral G35P SSA, may catalyze the annealing of these terminally redundant regions, alone or with the help of an exonuclease, to produce a circular unit-length duplex viral genome ready to initiate replication.