The Prospective Use of Brazilian Marine Macroalgae in Schistosomiasis Control.

Schistosomiasis is a parasitic disease that affects more than 250 million people. The treatment is limited to praziquantel and the control of the intermediate host with the highly toxic molluscicidal niclosamide. Marine algae are a poorly explored and promising alternative that can provide lead compounds, and the use of multivariate analysis could contribute to quicker discovery. As part of our search for new natural compounds with which to control schistosomiasis, we screened 45 crude extracts obtained from 37 Brazilian seaweed species for their molluscicidal activity against Biomphalaria glabrata embryos and schistosomicidal activities against Schistosoma mansoni. Two sets of extracts were taxonomically grouped for metabolomic analysis. The extracts were analyzed by GC-MS, and the data were subjected to Pattern Hunter and Pearson correlation tests. Overall, 22 species (60%) showed activity in at least one of the two models. Multivariate analysis pointed towards 3 hits against B. glabrata veliger embryos in the Laurencia/Laurenciella set, 5 hits against B. glabrata blastula embryos, and 31 against S. mansoni in the Ochrophyta set. Preliminary annotations suggested some compounds such as triquinane alcohols, prenylated guaianes, dichotomanes, and xenianes. Despite the putative identification, this work presents potential candidates and can guide future isolation and identification.

Brazilian begomovirus populations are highly recombinant, rapidly evolving, and segregated based on geographical location.

The incidence of begomovirus infections in crop plants sharply increased in Brazil during the 1990s following the introduction of the invasive B biotype of the whitefly vector, Bemisia tabaci. It is believed that this biotype transmitted begomoviruses from noncultivated plants to crop species with greater efficiency than indigenous B. tabaci biotypes. Either through rapid host adaptation or selection pressure in genetically diverse populations of noncultivated hosts, over the past 20 years various previously unknown begomovirus species have became progressively more prevalent in cultivated species such as tomato. Here we assess the genetic structure of begomovirus populations infecting tomatoes and noncultivated hosts in southeastern Brazil. Between 2005 and 2010, we sampled and sequenced 126 DNA-A and 58 DNA-B full-length begomovirus components. We detected nine begomovirus species in tomatoes and eight in the noncultivated host samples, with four species common to both tomatoes and noncultivated hosts. Like many begomoviruses, most species are obvious interspecies recombinants. Furthermore, species identified in tomato have probable parental viruses from noncultivated hosts. While the population structures of five well-sampled viral species all displayed geographical subdivision, a noncultivated host-infecting virus was more genetically variable than the four predominantly tomato-infecting viruses.

Recombination and pseudorecombination driving the evolution of the begomoviruses Tomato severe rugose virus (ToSRV) and Tomato rugose mosaic virus (ToRMV): two recombinant DNA-A components sharing the same DNA-B.

BACKGROUND: Begomoviruses are dicot-infecting, whitefly-transmitted viruses with a genome comprised of one or two molecules of circular, single-stranded DNA. In Brazil, tomato-infecting begomoviruses have emerged as serious pathogens since the introduction of a new biotype of the insect vector in the mid-1990's. Tomato rugose mosaic virus (ToRMV) and Tomato severe rugose virus (ToSRV) are often found in tomato fields. The complete sequence of the DNA-B components of ToSRV and ToRMV show an identity of 98.2%. Additionally, the high nucleotide identity (96.2%) between their common regions indicates that these two viruses may share the same DNA-B. METHODS: Tomato seedlings were biolistically inoculated with ToSRV (DNA-A and DNA-B) and ToRMV (DNA-A and DNA-B) infectious clones in every possible combination of single or mixed infection. Symptom expression was evaluated for up to 35 days post-inoculation (dpi). DNA was extracted at 28 dpi and the presence of each viral genomic component was examined by rolling circle amplification (RCA) followed by digestion, as well as by quantitative, real-time PCR. Sequence comparisons, recombination and phylogenetic analyzes were performed using EMBOSS needle, RDP program and maximum likelihood inference, respectively. RESULTS: Symptoms in tomato plants inoculated with the different combinations of ToRMV and ToSRV DNA-A and DNA-B components consisted of a typical mosaic in all combinations. Pseudorecombinants were formed in all possible combinations. When two DNA-A or two DNA-B components were inoculated simultaneously, the ToRMV components were detected preferentially in relation to the ToSRV components. The combination of minor changes in both the Rep protein and the CR may be involved in the preferential replication of ToRMV components. Recombination and phylogenetic analyzes support the exchange of genetic material between ToRMV and ToSRV. CONCLUSIONS: ToRMV and ToSRV form viable pseudorecombinants in their natural host (Solanum lycopersicum) and share the same DNA-B. ToRMV DNA components are preferentially replicated over ToSRV components. These results indicate that the emergence of ToRMV involved both recombination and pseudorecombination, further highlighting the importance of these mechanisms in the emergence and adaptation of begomoviruses.

A Phytoplasma Belonging to a 16SrIII-A Subgroup and dsRNA Virus Associated with Cassava Frogskin Disease in Brazil.

Cassava frogskin disease (CFSD) is a particular threat in cassava because symptoms remain hidden until harvest and losses can be total. The information related to the etiological agent of this disease is contradictory, because some authors believe it is caused by phytoplasmas while others believe that it is caused by a virus. In order to refine detection protocols and to characterize organisms associated with CFSD in Brazil, 32 symptomatic and 20 asymptomatic cassava plants were collected in Minas Gerais state. Total DNA was extracted and used for nested polymerase chain reaction (PCR) to detect phytoplasmas. Because endophytic Bacillus spp. led to false positives, primers were designed to facilitate the detection of phytoplasma in the presence of bacteria. In addition, double-stranded (ds)RNA was extracted from tubers and used in reverse-transcription PCR for the detection of the RNA-dependent RNA polymerase gene from Cassava frogskin virus segment 4. The detected phytoplasma was identified as belonging to the group 16SrIII-A by restriction fragment length polymorphism (RFLP), sequencing, and RFLP in silico. This is the first report of a phytoplasma belonging to the 16SrIII-A group associated with cassava plants, the first molecular characterization of a phytoplasma associated with CFSD in Brazil, and a first report of phytoplasma and a dsRNA virus (possible reovirus) co-infecting cassava plants with CFSD symptoms.

Synonymous site variation due to recombination explains higher genetic variability in begomovirus populations infecting non-cultivated hosts.

Begomoviruses are ssDNA plant viruses that cause serious epidemics in economically important crops worldwide. Non-cultivated plants also harbour many begomoviruses, and it is believed that these hosts may act as reservoirs and as mixing vessels where recombination may occur. Begomoviruses are notoriously recombination-prone, and also display nucleotide substitution rates equivalent to those of RNA viruses. In Brazil, several indigenous begomoviruses have been described infecting tomatoes following the introduction of a novel biotype of the whitefly vector in the mid-1990s. More recently, a number of viruses from non-cultivated hosts have also been described. Previous work has suggested that viruses infecting non-cultivated hosts have a higher degree of genetic variability compared with crop-infecting viruses. We intensively sampled cultivated and non-cultivated plants in similarly sized geographical areas known to harbour either the weed-infecting Macroptilium yellow spot virus (MaYSV) or the crop-infecting Tomato severe rugose virus (ToSRV), and compared the molecular evolution and population genetics of these two distantly related begomoviruses. The results reinforce the assertion that infection of non-cultivated plant species leads to higher levels of standing genetic variability, and indicate that recombination, not adaptive selection, explains the higher begomovirus variability in non-cultivated hosts.

Complete Genome Sequence of a Novel Satellite Virus Associated with Cassava Plants.

A novel satellite virus of 1,228 bp in length was found in a single cassava plant. Bioinformatic analyses show that it has two open reading frames (ORFs) in its genome, probably encoding a coat protein of 156 and a putative protein of 90 amino acids.

The diversification of begomovirus populations is predominantly driven by mutational dynamics.

Begomoviruses (single-stranded DNA plant viruses) are responsible for serious agricultural threats. Begomovirus populations exhibit a high degree of within-host genetic variation and evolve as quickly as RNA viruses. Although the recombination-prone nature of begomoviruses has been extensively demonstrated, the relative contribution of recombination and mutation to the genetic variation of begomovirus populations has not been assessed. We estimated the genetic variability of begomovirus datasets from around the world. An uneven distribution of genetic variation across the length of the cp and rep genes due to recombination was evident from our analyses. To estimate the relative contributions of recombination and mutation to the genetic variability of begomoviruses, we mapped all substitutions over maximum likelihood trees and counted the number of substitutions on branches which were associated with recombination (ηr) and mutation (ηµ). In addition, we also estimated the per generation relative rates of both evolutionary mechanisms (r/µ) to express how frequently begomovirus genomes are affected by recombination relative to mutation. We observed that the composition of genetic variation in all begomovirus datasets was dominated by mutation. Additionally, the low correlation between the estimates indicated that the relative contributions of recombination and mutation are not necessarily a function of their relative rates. Our results show that, although a considerable fraction of the genetic variation levels could be assigned to recombination, it was always lower than that due to mutation, indicating that the diversification of begomovirus populations is predominantly driven by mutational dynamics.

Synergism and negative interference during co-infection of tomato and Nicotiana benthamiana with two bipartite begomoviruses.

In Brazil, at least eight begomoviruses including Tomato rugose mosaic virus (ToRMV) and Tomato yellow spot virus (ToYSV) infect tomatoes. ToYSV symptoms in tomato and Nicotiana benthamiana appear earlier and are more severe compared to those of ToRMV. We investigated the role of several factors in this differential adaptation. To analyze infection kinetics, a single leaf was inoculated and subsequently detached after different periods of time. Viral DNA accumulation was quantified in plants, viral replication was analyzed in protoplasts, and tissue tropism was determined by in situ hybridization. Results indicate that ToYSV establishes a systemic infection and reaches a higher concentration earlier than ToRMV in both hosts. ToRMV negatively interferes with ToYSV during the initial stages of infection, but once systemic infection is established this interference ceases. In N. benthamiana, ToYSV invades the mesophyll, while ToRMV is phloem-restricted. During dual infection in this host, ToYSV releases ToRMV from the phloem.

Modified lateral thoracodorsal flap: a way out of a difficult problem.

BACKGROUND: Breast deformities, often attributable to surgical mutilations as a result of mammary carcinoma treatment, still are a challenge to plastic surgeons. Interesting alternatives for the frequently used musculocutaneous flaps are local flaps such as the lateral thoracodorsal flap developed by Holmström in 1986. This flap is simple to raise and involves no sacrifice of important muscular structures. This report aims to demonstrate the use of the modified lateral thoracodorsal flap in an immediate mammary reconstruction for a patient who refused any other scar. METHODS: A case report describes a patient presenting with breast cancer after reduction mammaplasty who was treated with a skin-sparing mastectomy and immediate reconstruction. RESULTS: Satisfactory defect correction was accomplished with adequate silicone implant covering and a natural ptotic breast shape. CONCLUSIONS: The versatility of this flap and its simple execution make it an important option for diverse breast reconstruction situations. The lateral thoracodorsal flap provides aesthetic results similar to those with other reconstruction methods, but without major complexity. The authors believe that it could be an interesting tool for the treatment of a breast anomaly.