The genome sequence of Trypanosoma cruzi, etiologic agent of Chagas disease

Whole-genome sequencing of the protozoan pathogen Trypanosoma cruzi revealed that the diploid genome contains a predicted 22,570 proteins encoded by genes, of which 12,570 represent allelic pairs. Over 50% of the genome consists of repeated sequences, such as retrotransposons and genes for large families of surface molecules, which include trans-sialidases, mucins, gp63s, and a large novel family (>1300 copies) of mucin-associated surface protein (MASP) genes. Analyses of the T. cruzi, T. brucei, and Leishmania major (Tritryp) genomes imply differences from other eukaryotes in DNA repair and initiation of replication and reflect their unusual mitochondrial DNA. Although the Tritryp lack several classes of signaling molecules, their kinomes contain a large and diverse set of protein kinases and phosphatases; their size and diversity imply previously unknown interactions and regulatory processes, which may be targets for intervention.     

Evaluation of the recombinant Heat shock protein B (HspB) of Coxiella burnetii as a potential antigen for immunodiagnostic of Q fever in goats

Coxiella burnetii is an intracellular bacterium that causes a worldwide zoonosis, the Q fever. Currently, to diagnose the infection in ruminants, whole cell antigens-based ELISAs are used. In this study a heat shock protein, the HspB, was evaluated for its ability to be recognized by the goat immune system and its capacity to sign a stage of infection. The htpB gene of C. burnetii was cloned and sequenced. A high identity (>90%) was observed among the htpB genes of four ruminant strains tested. A recombinant protein was expressed in a prokaryotic expression system. The rHspB protein was used to determine the IgG reactivity by ELISA. Sera from experimentally and naturally infected goats were tested. The rHspB is recognized early during the infection course, at 18 days post-infection. Moreover, 80-90% of the animals tested were positive at 39-60dpi. In addition, animals presenting a reactivation of the infection displayed a higher reactivity, statistically significant (p<0.05), than that of the animals in latent infection. These findings suggest that the rHspB could be a good candidate for the development of an ELISA test making possible the detection of recent C. burnetii infection in goats as well as reactivation in those with latent infection.     

Genetic Diversity of Pathogenic and Nonpathogenic Populations of Fusarium oxysporum Isolated from Carnation Fields in Argentina

ABSTRACT In order to elucidate the origin of Fusarium oxysporum f. sp. dianthi in Argentina, the genetic diversity among pathogenic isolates together with co-occurring nonpathogenic isolates on carnation was investigated. In all, 151 isolates of F. oxysporum were obtained from soils and carnation plants from several horticultural farms in Argentina. The isolates were characterized using vegetative compatibility group (VCG), intergenic spacer (IGS) typing, and pathogenicity tests on carnation. Seven reference strains of F. oxysporum f. sp. dianthi also were analyzed and assigned to six different IGS types and six VCGs. Twenty-two Argentinean isolates were pathogenic on carnation, had the same IGS type (50), and belonged to a single VCG (0021). The 129 remaining isolates were nonpathogenic on carnation and sorted into 23 IGS types and 97 VCGs. The same VCG never occurred in different IGS types. Our results suggest that the pathogen did not originate in the local populations of F. oxysporum but, rather, that it was introduced into Argentina. Given the genetic homogeneity within Argentinean isolates of F. oxysporum f. sp. dianthi, either IGS type or VCG can be used for the identification of the forma specialis dianthi currently in Argentina.     

Landscape genetics matches with behavioral ecology and brings new insight on the functional connectivity in Mediterranean mouflon

Context

In natural populations, gene flow often represents a key factor in determining and maintaining genetic diversity. In a worldwide context of habitat fragmentation, assessing the relative contribution of landscape features to gene flow thus appears crucial for sustainable management of species.

Objective

We addressed this issue in Mediterranean mouflon (Ovis gmelini musimon?×?Ovis sp.) by combining previous knowledge on behavioral ecology with landscape genetics. We also assessed how sex-specific behavioral differences translated in term of functional connectivity in both sexes.

Methods

We relied on 239 individuals genotyped at 16 microsatellite markers. We applied a model optimization approach in a causal modeling framework of landscape genetics to test for the effects on gene flow of habitat types and linear landscape features previously identified as important for movements and habitat selection in both sexes. Five resistance values were alternately assigned to these landscape characteristics leading to a comprehensive set of resistance surfaces.

Results

Isolation by resistance shaped female gene flow, supporting the central role of linear landscape features as behavioral barriers for animal movements. Conversely, no isolation by resistance was detected in males. Although a lack of statistical power cannot be discarded to explain this result, it tended to confirm that males are less influenced by landscape structures during the mating period.

Conclusions

Combining previous knowledge on behavioral ecology with results from landscape genetics was decisive in assessing functional landscape connectivity in both sexes. These results highlighted the need to perform sex-specific studies for management and conservation of dimorphic species.

     

Widespread lateral gene transfer from intracellular bacteria to multicellular eukaryotes

Although common among bacteria, lateral gene transfer-the movement of genes between distantly related organisms-is thought to occur only rarely between bacteria and multicellular eukaryotes. However, the presence of endosymbionts, such as Wolbachia pipientis, within some eukaryotic germlines may facilitate bacterial gene transfers to eukaryotic host genomes. We therefore examined host genomes for evidence of gene transfer events from Wolbachia bacteria to their hosts. We found and confirmed transfers into the genomes of four insect and four nematode species that range from nearly the entire Wolbachia genome (>1 megabase) to short (<500 base pairs) insertions. Potential Wolbachia-to-host transfers were also detected computationally in three additional sequenced insect genomes. We also show that some of these inserted Wolbachia genes are transcribed within eukaryotic cells lacking endosymbionts. Therefore, heritable lateral gene transfer occurs into eukaryotic hosts from their prokaryote symbionts, potentially providing a mechanism for acquisition of new genes and functions.     

Dynamics of serum antibodies to and load of porcine circovirus type 2 (PCV2) in pigs in three finishing herds,affected or not by postweaning multisystemic wasting syndrome

Background

Despite that PMWS commonly affects pigs aged eight to sixteen weeks; most studies of PMWS have been conducted during the period before transfer to finishing herds. This study focused on PCV2 load and antibody dynamics in finishing herds with different PMWS status.

Methods

Sequentially collected blood samples from 40 pigs in each of two Swedish (A and B) and one Norwegian (C) finishing herds were analysed for serum PCV2-load and -antibodies and saliva cortisol. The two Swedish herds differed in PMWS status, despite receiving animals from the same sow pool (multi-site production). However, the PMWS-deemed herd (A) had previously also received pigs from the spot market. ResultsThe initial serum PCV2 load was similar in the two Swedish herds. In herd A, it peaked after two weeks in the finishing herd and a high number of the pigs had serum PCV2 levels above 10⁷ per ml. The antibody titres increased continually with exception for the pigs that developed PMWS, that had initially low and then declining antibody levels. Pigs in the healthy herd B also expressed high titres of antibodies to PCV2 on arrival but remained at that level throughout the study whereas the viral load steadily decreased. No PCV2 antibodies and only low amounts of PCV2 DNA were detected in serum collected during the first five weeks in the PMWS-free herd C. Thereafter a peak in serum PCV2 load accompanied by an antibody response was recorded. PCV2 from the two Swedish herds grouped into genotype PCV2b whereas the Norwegian isolate grouped into PCV2a. Cortisol levels were lower in herd C than in herds A and B.

Conclusions

The most obvious difference between the Swedish finishing herds and the Norwegian herd was the time of infection with PCV2 in relation to the time of allocation, as well as the genotype of PCV2. Clinical PMWS was preceded by low levels of serum antibodies and a high load of PCV2 but did not develop in all such animals. It is notable that herd A became affected by PMWS after errors in management routine, emphasising the importance of proper hygiene and general disease-preventing measures.     

Participatory guarantee systems and the re-imagining of Mexico’s organic sector

Although it is the most widely accepted form of organic guarantee, third party certification can be inaccessible for small-scale producers and promotes a highly market-oriented vision of organics. By contrast, participatory guarantee systems (PGS) are based on principles of relationship-building, mutual learning, trust, context-specificity, local control, diversity, and collective action. This paper uses the case study of the Mexican Network of Local Organic Markets to explore how PGS can be used to support a more alternative vision of organics, grounded in the notion of food sovereignty. It presents some of the key challenges and opportunities associated with the approach, and highlights its potential to serve as a locally-based institution for collective action, thereby offering some structural support to alternative agri-food initiatives.     

Biotic changes in relation to local decrease in soil conduciveness to disease caused by <Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

The relationships between biotic changes and local decrease in soil conduciveness in disease patches towards the disease incited by Rhizoctonia solani AG 2-2 in a sugar beet field in France were investigated. Soil samples from healthy and diseased areas were analysed for bacterial and fungal densities, molecular and physiological microbial community structures, and antagonistic abilities of Trichoderma isolates collected from diseased and healthy areas. Although the inoculum density was higher inside the disease patches, the respective soil was less conducive towards disease incited by R. solani AG 2-2. It was concluded that the pathogen was present in healthy areas but did not incite disease in field conditions. Conversely, the response of the microflora to previous development of R. solani in diseased areas prevented further pathogenic activity. Indeed, genetic and physiological structures of the fungal communities and physiological structures of the bacterial communities were modified in disease patches compared to healthy areas. The terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the peaks corresponding to R. solani and Trichoderma spp. were higher inside the patches than in the healthy areas. Trichoderma isolates from the disease patches were more antagonistic than those from the healthy areas. These results suggest that disease caused by R. solani AG 2-2 induced changes in genetic and physiological structure of microbial populations and development of antagonists. The decreased conduciveness inside the patches may help explain patch mobility in the following season.     

COMPARISON BETWEEN SEDATION AND GENERAL ANESTHESIA FOR HIGH RESOLUTION COMPUTED TOMOGRAPHIC CHARACTERIZATION OF CANINE IDIOPATHIC PULMONARY FIBROSIS IN WEST HIGHLAND WHITE TERRIERS

Canine idiopathic pulmonary fibrosis is a progressive interstitial lung disease mainly affecting West Highland white terriers. Thoracic high‐resolution computed tomographic (T‐HRCT) findings for Canine idiopathic pulmonary fibrosis acquired under general anesthesia have been described previously. However, the use of general anesthesia may be contraindicated for some affected dogs. Sedation may allow improved speed and safety, but it is unknown whether sedation would yield similar results in identification and grading of Canine idiopathic pulmonary fibrosis lesions. The aim of this prospective, observational, method‐comparison, case‐control study was to compare findings from T‐HRCT images acquired under sedation versus general anesthesia for West Highland white terriers affected with Canine idiopathic pulmonary fibrosis (n = 11) and age‐matched controls (n = 9), using the glossary of terms of the Fleischner Society and a scoring system. Ground‐glass opacity was identified in all affected West Highland white terriers for both sedation and general anesthesia acquisitions, although the Ground‐glass opacity extent varied significantly between the two acquisitions (P < 0.001). Ground‐glass opacity was the sole lesion observed in control dogs (n = 6), but was less extensive compared with affected West Highland white terriers. Identification and grading of a mosaic attenuation pattern differed significantly between acquisitions (P < 0.001). Identification of lesions such as consolidations, nodules, parenchymal and subpleural bands, bronchial wall thickening, and bronchiectasis did not differ between acquisitions. The present study demonstrated that T‐HRCT obtained under sedation may provide different information than T‐HRCT obtained under general anesthesia for identification and grading of some Canine idiopathic pulmonary fibrosis lesions, but not all of them. These differences should be taken into consideration when general anesthesia is contraindicated and sedation is necessary for evaluating West Highland white terriers with Canine idiopathic pulmonary fibrosis.