Molecular characterization and experimental host-range of two begomoviruses infecting <Emphasis Type="Italic">Clerodendrum cyrtophyllum</Emphasis> in China

Two begomovirus isolates (YX2-I and YX2-II) were identified from Clerodendrum cyrtophyllum showing yellow mosaic symptoms collected in Jiangsu province of China. Sequence analysis reveals that YX2-I is a distinct begomovirus species for which the name Clerodendrum golden mosaic Jiangsu virus (ClGMJSV-[CN:YX2:08]) is proposed. YX2-II is an isolate of bipartite begomovirus Clerodendrum golden mosaic China virus (ClGMCNV-[CN:YX2:08]). Infectious clones of the two viruses were constructed and agroinoculated into Nicotiana benthamiana, N. glutinosa, N. tabacum Samsun, Petunia hybrida, Solanum lycopersicum, Capsicum annuum, S. melongena, Glycine max and Gossypium hirsutum plants. ClGMJSV induced leaf curling and stunting symptoms in N. benthamiana, N. glutinosa, N. tabacum Samsun, and P. hybrida, and ClGMCNV infected N. benthamiana, N. glutinosa, and N. tabacum Samsun with severe symptoms and P. hybrida without obvious symptom. Latent infection in N. benthamiana, N. glutinosa, N. tabacum Samsun, and P. hybrida plants was observed when plants were inoculated with ClGMCNV DNA-A alone. In addition, we illustrated that ClGMCNV DNA-A was capable of interacting with the betasatellite associated with Tobacco curly shoot virus (TbCSB) to produce symptoms in N. benthamiana and N. glutinosa plants, and ClGMJSV could interact with TbCSB but not with ClGMCNV DNA-B in N. benthamiana plants.     

Molecular characterization and evolutionary analysis of <Emphasis Type="Italic">soybean mosaic virus</Emphasis> infecting <Emphasis Type="Italic">Pinellia ternata</Emphasis> in China

Twenty-nine Pinellia ternata specimens were collected from representative areas in China, including the major production provinces of Zhejiang, Henan, Shanxi, Hunan, Shandong and Hubei. Seven isolates related to soybean mosaic virus (SMV), which could be pathogenic on P. ternata and some soybean [Glycine max (L.) Merr.] cultivars, were detected using double antibody sandwich immunosorbent assay (DAS-ELISA) and RT-PCR amplification performed with degenerate primer of potyviruses. It is revealed that the common potyvirus infecting P. ternata is, indeed, only SMVs rather than Dasheen mosaic virus (DsMV) as previously reported. Further molecular phylogenetic analysis of the coat protein (CP) genes of these SMV isolates from P. ternata and G. max, along with some other potyvirus members, such as DsMV and Watermelon mosaic virus (WMV) reconstructed the evolutionary route on both nucleotide and amino acid levels. Similarity and homology of nucleotide sequences for SMV CP genes demonstrated high host correlation and low partial habitat correlation, while those of amino acid sequences also showed that the host correlation was more notable than the habitat correlation. The amino acid sequence of conserved region within CP determines the main function, which shows high homology between species. This study outspreaded from the viruses themselves and their relationship to the infected hosts and revealed the evolutionary strategies, especially the rapid variation or recombination of SMV of P. ternata, in order to adapt itself naturally to the special host. The GenBank Accession numbers of the sequences reported in this article are DQ360817-DQ360823.     

Strains of <Emphasis Type="Italic">Peru tomato virus</Emphasis> infecting cocona (<Emphasis Type="Italic">Solanum sessiliflorum</Emphasis>), tomato and pepper in Peru with reference to genome evolution in genus <Emphasis Type="Italic">Potyvirus</Emphasis>

Summary. Two isolates (SL1 and SL6) of Peru tomato virus (PTV, genus Potyvirus) were obtained from cocona plants (Solanum sessiliflorum) growing in Tingo María, the jungle of the Amazon basin in Peru. One PTV isolate (TM) was isolated from a tomato plant (Lycopersicon esculentum) growing in Huaral at the Peruvian coast. The three PTV isolates were readily transmissible by Myzus persicae. Isolate SL1, but not SL6, caused chlorotic lesions in inoculated leaves of Chenopodium amaranticolor and C. quinoa. Isolate TM differed from SL1 and SL6 in causing more severe mosaic symptoms in tomato, and vein necrosis in the leaves of cocona. Pepper cv. Avelar (Capsicum annuum) showed resistance to the PTV isolates SL1 and SL6 but not TM. The 5- and 3-proximal sequences of the three PTV isolates were cloned, sequenced and compared to the corresponding sequences of four PTV isolates from pepper, the only host from which PTV isolates have been previously characterised at the molecular level. Phylogenetic analyses on the P1 protein and coat protein amino acid sequences indicated, in accordance with the phenotypic data from indicator hosts, that the PTV isolates from cocona represented a distinguishable strain. In contrast, the PTV isolates from tomato and pepper were not grouped according to the host. Inclusion of the sequence data from the three PTV isolates of this study in a phylogenetic analysis with other PTV isolates and other potyviruses strengthen the membership of PTV in the so-called PVY subgroup of Potyvirus. This subgroup of closely related potyvirus species was also distinguishable from other potyviruses by their more uniform sizes of the protein-encoding regions within the polyprotein.The first two authors contributed equally.     

Mitotic recombination in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Mitotic homologous recombination (HR) is an important mechanism for the repair of double-strand breakS and errors occurring during DNA replication. It is likely that the recombinational repair of DNA lesions occurs preferentially by sister chromatid exchanges that have no genetic consequences. However, most genetically detectable HR events occur between homologous DNA sequences located at allelic positions in homologous chromosomes, or between DNA repeats located at ectopic positions in either the same, homologous or heterologous chromosomes. Mitotic recombination may occur by multiple mechanisms, including double-strand break repair, synthesis-dependent strand annealing, break-induced replication and single-strand annealing. The occurrence of one recombination mechanism versus another depends on different elements, including the position of the homologous partner, the initiation event, the length of homology of the recombinant molecules and the genotype. The genetics and molecular biology of the yeast Saccharomyces cerevisiae have proved essential for the understanding of mitotic recombination mechanisms in eukaryotes. Here, we review recent genetic yeast data that contribute to our understanding of the different mechanisms of mitotic recombination and the in vivo role of the recombination proteins.     

Cercarial shedding from <Emphasis Type="Italic">Galba</Emphasis><Emphasis Type="Italic">truncatula</Emphasis> infected with <Emphasis Type="Italic">Fasciola</Emphasis><Emphasis Type="Italic">gigantica</Emphasis> of distinct geographic origins

Galba truncatula snails were experimentally infected with either of two different isolates of Fasciola gigantica, originating from Egypt or China, to determine the influence of these isolates on the characteristics of snail infections. The survival rates of G. truncatula on day 30 post-exposure were 90.0% and 60.2% in the Egyptian and Chinese groups, respectively. The frequency of cercaria-shedding snails within the Egyptian group was 79.8%, whereas in the Chinese group it was 22.4%. The parasite origin had a significant effect on the durations of the prepatent and patent periods. The mean number of cercariae shed from the Egyptian group was significantly greater than that shed from the Chinese group (a mean of 275.5 per cercaria-shedding snail compared with 29.0). These results could be explained by the fact that G. truncatula might be a natural intermediate host for F. gigantica in Egypt, and the greater adaptability of the Egyptian miracidia of F. gigantica to unusual snail hosts. These results demonstrate the influence of the geographic origin of the parasite on the success of trematodes infecting snails.     

Cysteine proteinases from promastigotes of <Emphasis Type="Italic">Leishmania</Emphasis> (<Emphasis Type="Italic">Viannia</Emphasis>) <Emphasis Type="Italic">braziliensis</Emphasis>

Leishmania (Viannia) braziliensis is the major causative agent of American tegumentary leishmaniasis, a disease that has a wide geographical distribution and is a severe public health problem. The cysteine proteinase B (CPB) from Leishmania spp. represents an important virulence factor. In this study, we characterized and localized cysteine proteinases in L. (V.) braziliensis promastigotes. By a combination of triton X-114 extraction, concanavalin A-affinity, and ion exchange chromatographies, we obtained an enriched fraction of hydrophobic proteins rich in mannose residues. This fraction contained two proteinases of 63 and 43 kDa, which were recognized by a CPB antiserum, and were partially sensitive to E-64 in enzymatic assays with the peptide Glu-Phe-Leu. In confocal microscopy, the CPB homologues localized in the peripheral region of the parasite. This data together with direct agglutination and flow cytometry assays suggest a surface localization of the CPB homologues. The incubation of intact promastigotes with phospholipase C reduced the number of CPB-positive cells, while anti-cross-reacting determinant and anti-CPB antisera recognized two polypeptides (63 and 43 kDa) derived from phospholipase C treatment, suggesting that some CPB isoforms may be glycosylphosphatidylinositol-anchored. Collectively, our results suggest the presence of CPB homologues in L. braziliensis surface and highlight the need for further studies on L. braziliensis cysteine proteinases, which require enrichment methods for enzymatic detection.     

<Emphasis Type="Italic">Sida micrantha</Emphasis> mosaic is associated with a complex infection of begomoviruses different from <Emphasis Type="Italic">Abutilon mosaic virus</Emphasis>

Summary. We report on the nucleotide sequences of geminiviruses of the genus Bemogovirus infecting Sida micrantha Schr., a common weed in Brazil. For decades, the mosaic frequently associated with Sida plants was considered to be caused by a Brazilian strain of Abutilon mosaic virus (AbMV). By infection studies and sequence comparisons, we demonstrate that it is associated with a complex of at least two begomoviruses as different from AbMV as most South American geminiviruses. Two molecules of DNA A (A1, A2) and three of DNA B (B1, B2, B3) were cloned and sequenced. According to the high homology in their common regions, DNA A1 and DNA B3, as well as DNA A2 and DNA B2, are cognate components of two begomoviruses, which were infectious in Nicotiana benthamiana plants. No trans-replication was found for any other A/B combination. The intergenic region of DNA B2 appears to be the product of the recombination between DNA B1 and DNA A2. These results show that a coinfection of begomoviruses can persist over decades, producing a reservoir of partially recombined but distinct geminiviruses.     

Life cycle of <Emphasis Type="Italic">Sarcocystis camelicanis</Emphasis> infecting the camel (<Emphasis Type="Italic">Camelus dromedarius</Emphasis>) and the dog (<Emphasis Type="Italic">Canis familiaris</Emphasis>), light and electron microscopic study

In the present study, the heteroxeneous life cycle of Sarcocystis sp. infecting camels were studied. A total of 180 slaughtered camels collected from different localities in Egypt were investigated for sarcocysts. Only 116 animals were found to be infected (the infection rate was 64%). Muscle samples of esophagus, diaphragm, tongue, skeletal, and heart muscles were examined. Exclusively, microscopic sarcocysts were detected in all examined organs. The infection rates of the esophagus, diaphragm, tongue, skeletal, and heart muscles were 60%, 50%, 40%, 40%, and 10%, respectively. By means of transmission electron microscopy, details of the ultrastructure of the sarcocysts were studied. The specific architecture and ornaments of the cyst wall, its protrusions, and the cyst interior were recorded. Unique features of protrusions of the primary cyst wall, the knob-like structures, arise around each protrusion. Experimental infection of carnivores by feeding heavily infected camel muscles revealed that the dog, Canis familiaris, is the only final host of the present Sarcocystis species. Gamogony, sporogonic stages, and characteristics of sporulated oocysts were also investigated.     

Functional polymorphisms in <Emphasis Type="Italic">XRCC</Emphasis>-<Emphasis Type="Italic">1</Emphasis> and <Emphasis Type="Italic">APE</Emphasis>-<Emphasis Type="Italic">1</Emphasis> contribute to increased apoptosis and risk of ulcerative colitis

Objective  

The present study was designed to investigate the role of X-ray cross-complementing group 1 (XRCC1) and apurinic/apyrimidinic endonuclease 1 (APE1) polymorphisms in apoptosis and the risk of ulcerative colitis (UC).     

Selective activity of extracts of <Emphasis Type="Italic">Margaritaria discoidea</Emphasis> and <Emphasis Type="Italic">Homalium africanum</Emphasis> on <Emphasis Type="Italic">Onchocerca ochengi</Emphasis>

Background  

The current treatment of onchocerciasis relies on the use of ivermectin which is only microfilaricidal and for which resistant parasite strains of veterinary importance are increasingly being detected. In the search for novel filaricides and alternative medicines, we investigated the selective activity of crude extracts of Margaritaria discoidea and Homalium africanum on Onchocerca ochengi, a model parasite for O. volvulus. These plants are used to treat the disease in North West Cameroon.     

Redescription of <Emphasis Type="Italic">Lemuricola</Emphasis> (<Emphasis Type="Italic">Madoxyuris</Emphasis>) <Emphasis Type="Italic">bauchoti</Emphasis> (Nematoda,Oxyuridae) from <Emphasis Type="Italic">Lemur catta</Emphasis> in Madagascar

Lemuricola (Madoxyuris) bauchoti Chabaud, Brygoo et Petter, 1965 is redescribed from material collected from the ring-tailed lemur, Lemur catta, from the Beza Mahafaly Special Reserve in Madagascar using the scanning electron microscope. This is a new host record and the first oxyurid reported from the ring-tailed lemur. Previously, records of each species of the subgenus Madoxyuris have been restricted to a single host species, but the close relationship between these nematodes and their Strepsirrhini hosts will only be proven when additional records fill in the gaps in their distribution.     

<Emphasis Type="Italic">P</Emphasis>. <Emphasis Type="Italic">aeruginosa</Emphasis> Biofilms in CF Infection

Pseudomonas aeruginosa is an opportunistic pathogen of immunocompromised hosts. In cystic fibrosis (CF), P. aeruginosa causes acute and chronic lung infections that result in significant morbidity and mortality. P. aeruginosa possesses several traits that contribute to its ability to colonize and persist in acute and chronic infections. These include high resistance to antimicrobials, ability to form biofilms, plethora of virulence products, and metabolic versatility. In P. aeruginosa, a cell-to-cell communication process termed quorum sensing (QS) regulates many of these factors that contribute to its pathogenesis. Recent evidence suggests that the CF lung environment presents a specialized niche for P. aeruginosa. The relationship of P. aeruginosa QS, biofilm formation, and the CF lung environment is discussed.