159 research outputs found
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Brazil’s bilateral investment treaties: More than a new investment treaty model?
After resisting ratifying investment treaties in the 1990s, Brazil has now become a player in the international investment regime. This Perspective argues that the new Brazilian investment treaties are part of an alternative investment policy, and that policy’s future depends on its success and ability to influence other international negotiations
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巴西的双边投资条约:不仅仅是一种新的投资协议模式?
After resisting ratifying investment treaties in the 1990s, Brazil has now become a player in the international investment regime. This Perspective argues that the new Brazilian investment treaties are part of an alternative investment policy, and that policy’s future depends on its success and ability to influence other international negotiations
Trypanosoma cruzi mitochondrial maxicircles display species- and strain-specific variation and a conserved element in the non-coding region
BACKGROUND: The mitochondrial DNA of kinetoplastid flagellates is distinctive in the eukaryotic world due to its massive size, complex form and large sequence content. Comprised of catenated maxicircles that contain rRNA and protein-coding genes and thousands of heterogeneous minicircles encoding small guide RNAs, the kinetoplast network has evolved along with an extreme form of mRNA processing in the form of uridine insertion and deletion RNA editing. Many maxicircle-encoded mRNAs cannot be translated without this post-transcriptional sequence modification. RESULTS: We present the complete sequence and annotation of the Trypanosoma cruzi maxicircles for the CL Brener and Esmeraldo strains. Gene order is syntenic with Trypanosoma brucei and Leishmania tarentolae maxicircles. The non-coding components have strain-specific repetitive regions and a variable region that is unique for each strain with the exception of a conserved sequence element that may serve as an origin of replication, but shows no sequence identity with L. tarentolae or T. brucei. Alternative assemblies of the variable region demonstrate intra-strain heterogeneity of the maxicircle population. The extent of mRNA editing required for particular genes approximates that seen in T. brucei. Extensively edited genes were more divergent among the genera than non-edited and rRNA genes. Esmeraldo contains a unique 236-bp deletion that removes the 5'-ends of ND4 and CR4 and the intergenic region. Esmeraldo shows additional insertions and deletions outside of areas edited in other species in ND5, MURF1, and MURF2, while CL Brener has a distinct insertion in MURF2. CONCLUSION: The CL Brener and Esmeraldo maxicircles represent two of three previously defined maxicircle clades and promise utility as taxonomic markers. Restoration of the disrupted reading frames might be accomplished by strain-specific RNA editing. Elements in the non-coding region may be important for replication, transcription, and anchoring of the maxicircle within the kinetoplast network
Members of a Large Retroposon Family Are Determinants of Post-Transcriptional Gene Expression in Leishmania
Trypanosomatids are unicellular protists that include the human pathogens Leishmania spp. (leishmaniasis), Trypanosoma brucei (sleeping sickness), and Trypanosoma cruzi (Chagas disease). Analysis of their recently completed genomes confirmed the presence of non–long-terminal repeat retrotransposons, also called retroposons. Using the 79-bp signature sequence common to all trypanosomatid retroposons as bait, we identified in the Leishmania major genome two new large families of small elements—LmSIDER1 (785 copies) and LmSIDER2 (1,073 copies)—that fulfill all the characteristics of extinct trypanosomatid retroposons. LmSIDERs are ∼70 times more abundant in L. major compared to T. brucei and are found almost exclusively within the 3′-untranslated regions (3′UTRs) of L. major mRNAs. We provide experimental evidence that LmSIDER2 act as mRNA instability elements and that LmSIDER2-containing mRNAs are generally expressed at lower levels compared to the non-LmSIDER2 mRNAs. The considerable expansion of LmSIDERs within 3′UTRs in an organism lacking transcriptional control and their role in regulating mRNA stability indicate that Leishmania have probably recycled these short retroposons to globally modulate the expression of a number of genes. To our knowledge, this is the first example in eukaryotes of the domestication and expansion of a family of mobile elements that have evolved to fulfill a critical cellular function
Microarray analysis of gene expression induced by sexual contact in Schistosoma mansoni
<p>Abstract</p> <p>Background</p> <p>The parasitic trematode <it>Schistosoma mansoni </it>is one of the major causative agents of Schistosomiasis, a disease that affects approximately 200 million people, mostly in developing countries. Since much of the pathology is associated with eggs laid by the female worm, understanding the mechanisms involved in oogenesis and sexual maturation is an important step towards the discovery of new targets for effective drug therapy. It is known that the adult female worm only develops fully in the presence of a male worm and that the rates of oviposition and maturation of eggs are significantly increased by mating. In order to study gene transcripts associated with sexual maturation and oviposition, we compared the gene expression profiles of sexually mature and immature parasites using DNA microarrays.</p> <p>Results</p> <p>For each experiment, three amplified RNA microarray hybridizations and their dye swaps were analyzed. Our results show that 265 transcripts are differentially expressed in adult females and 53 in adult males when mature and immature worms are compared. Of the genes differentially expressed, 55% are expressed at higher levels in paired females while the remaining 45% are more expressed in unpaired ones and 56.6% are expressed at higher levels in paired male worms while the remaining 43.4% are more expressed in immature parasites. Real-time RT-PCR analysis validated the microarray results. Several new maturation associated transcripts were identified. Genes that were up-regulated in single-sex females were mostly related to energy generation (i.e. carbohydrate and protein metabolism, generation of precursor metabolites and energy, cellular catabolism, and organelle organization and biogenesis) while genes that were down-regulated related to RNA metabolism, reactive oxygen species metabolism, electron transport, organelle organization and biogenesis and protein biosynthesis.</p> <p>Conclusion</p> <p>Our results confirm previous observations related to gene expression induced by sexual maturation in female schistosome worms. They also increase the list of <it>S. mansoni </it>maturation associated transcripts considerably, therefore opening new and exciting avenues for the study of the conjugal biology and development of new drugs against schistosomes.</p
Molecular Genetic Variability Of Commercial And Wild Accessions Of Passion Fruit (passiflora Spp.) Targeting Ex Situ Conservation And Breeding.
Passiflora species are distributed throughout Latin America, and Brazil and Colombia serve as the centers of diversity for this genus. We performed cross-species amplification to evaluate 109 microsatellite loci in 14 Passiflora species and estimated the diversity and genetic structure of Passiflora cincinnata, Passiflora setaceae and Passiflora edulis. A total of 127 accessions, including 85 accessions of P. edulis, a commercial species, and 42 accessions of 13 wild species, were examined. The cross-species amplification was effective for obtaining microsatellite loci (average cross-amplification of 70%). The average number of alleles per locus (five) was relatively low, and the average diversity ranged from 0.52 in P. cincinnata to 0.32 in P. setacea. The Bayesian analyses indicated that the P. cincinnata and P. setacea accessions were distributed into two groups, and the P. edulis accessions were distributed into five groups. Private alleles were identified, and suggestions for core collections are presented. Further collections are necessary, and the information generated may be useful for breeding and conservation.1522933-5
Magnetically Driven Outflows in a Starburst Environment
We here investigate the possibility that the observed collimated outflows in
luminous infrared galaxies (LIGs) and some Seyfert galaxies can be produced in
a starburst (SB) environment. A nuclear disk can be quickly produced by gas
infall during star formation in a rotating, stellar cluster. We find that
massive nuclear SBs with core disk masses M_d \sim 10^8 - 10^9 M_{\odot}, and
supernova rates \nu_{SN} \simeq 5 \times 10^{-3} - 2 yr^{-1} (which are
consistent with the \nu_{SN} values inferred from the observed non-thermal
radio power in source candidates) may inject kinetic energies which are high
enough to blow out directed flows from the accreting disk surface, within the
SB lifetimes. In our models, the acceleration and collimation of the nuclear
outflow are provided by magnetic fields anchored into the rotating SB-disk. The
emerging outflow carries a kinetic power that is only a small fraction (a few
percent) of the supernovae energy rate produced in the SB. Based on conditions
determined from observed outflows and disks, we find that moderate disk
magnetic fields (\gtrsim 8 \times 10^{-4} G) are able to accelerate the
outflows up to the observed terminal velocities (\lesssim few 100 km s^{-1} in
the case of the Seyfert galaxies, and \sim 400 - 950 km s^{-1} in the case of
the LIGs). The outflow is produced within a wind zone in the disk of radius
\lesssim 100 pc in the LIGs, and \lesssim 10 pc in the Seyferts, with wind mass
loss to disk accretion rate ratios \dot M_w /\dot M_d \gtrsim 0.1 (where \dot
M_d \sim 100 M_{\odot} yr^{-1}). The observation of rotating nuclear disks of
gas within few 100 pc scales in source candidates like the LIG Arp 220, and
magnetized outflows provide observational support for the picture drawn here.Comment: 31 pages, Latex file, 1 Figure, accepted for publication in the
Astrophys. Journa
Genetic structure and molecular diversity of cacao plants established as local varieties for more than two centuries: the genetic history of cacao plantations in Bahia, Brazil
ahia is the most important cacao-producing state in Brazil, which is currently the sixth-largest country worldwide to produce cacao seeds. In the eighteenth century, the Comum, Pará and Maranhão varieties of cacao were introduced into southern Bahia, and their descendants, which are called ‘Bahian cacao’ or local Bahian varieties, have been cultivated for over 200 years. Comum plants have been used to start plantations in African countries and extended as far as countries in South Asia and Oceania. In Brazil, two sets of clones selected from Bahian varieties and their mutants, the Agronomic Institute of East (SIAL) and Bahian Cacao Institute (SIC) series, represent the diversity of Bahian cacao in germplasm banks. Because the genetic diversity of Bahian varieties, which is essential for breeding programs, remains unknown, the objective of this work was to assess the genetic structure and diversity of local Bahian varieties collected from farms and germplasm banks. To this end, 30 simple sequence repeat (SSR) markers were used to genotype 279 cacao plants from germplasm and local farms. The results facilitated the identification of 219 cacao plants of Bahian origin, and 51 of these were SIAL or SIC clones. Bahian cacao showed low genetic diversity. It could be verified that SIC and SIAL clones do not represent the true diversity of Bahian cacao, with the greatest amount of diversity found in cacao trees on the farms. Thus, a core collection to aid in prioritizing the plants to be sampled for Bahian cacao diversity is suggested. These results provide information that can be used to conserve Bahian cacao plants and applied in breeding programs to obtain more productive Bahian cacao with superior quality and tolerance to major diseases in tropical cacao plantations worldwide1012CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP620239/2008-5; 555432/2009-2PROCAD-NF20082008/52197-4; 2010/50033-4; 2013/08086-
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Genomics of Loa loa, a Wolbachia-free filarial parasite of humans
Loa loa, the African eyeworm, is a major filarial pathogen of humans. Unlike most filariae, Loa loa does not contain the obligate intracellular Wolbachia endosymbiont. We describe the 91.4 Mb genome of Loa loa, and the genome of the related filarial parasite Wuchereria bancrofti, and predict 14,907 Loa loa genes based on microfilarial RNA sequencing. By comparing these genomes to that of another filarial parasite, Brugia malayi, and to several other nematode genomes, we demonstrate synteny among filariae but not with non-parasitic nematodes. The Loa loa genome encodes many immunologically relevant genes, as well as protein kinases targeted by drugs currently approved for humans. Despite lacking Wolbachia, Loa loa shows no new metabolic synthesis or transport capabilities compared to other filariae. These results suggest that the role played by Wolbachia in filarial biology is more subtle than previously thought and reveal marked differences between parasitic and non-parasitic nematodes
New resources for functional analysis of omics data for the genus Aspergillus
<p>Abstract</p> <p>Background</p> <p>Detailed and comprehensive genome annotation can be considered a prerequisite for effective analysis and interpretation of omics data. As such, Gene Ontology (GO) annotation has become a well accepted framework for functional annotation. The genus <it>Aspergillus </it>comprises fungal species that are important model organisms, plant and human pathogens as well as industrial workhorses. However, GO annotation based on both computational predictions and extended manual curation has so far only been available for one of its species, namely <it>A. nidulans</it>.</p> <p>Results</p> <p>Based on protein homology, we mapped 97% of the 3,498 GO annotated <it>A. nidulans </it>genes to at least one of seven other <it>Aspergillus </it>species: <it>A. niger</it>, <it>A. fumigatus</it>, <it>A. flavus</it>, <it>A. clavatus</it>, <it>A. terreus</it>, <it>A. oryzae </it>and <it>Neosartorya fischeri</it>. GO annotation files compatible with diverse publicly available tools have been generated and deposited online. To further improve their accessibility, we developed a web application for GO enrichment analysis named FetGOat and integrated GO annotations for all <it>Aspergillus </it>species with public genome sequences. Both the annotation files and the web application FetGOat are accessible via the Broad Institute's website (<url>http://www.broadinstitute.org/fetgoat/index.html</url>). To demonstrate the value of those new resources for functional analysis of omics data for the genus <it>Aspergillus</it>, we performed two case studies analyzing microarray data recently published for <it>A. nidulans</it>, <it>A. niger </it>and <it>A. oryzae</it>.</p> <p>Conclusions</p> <p>We mapped <it>A. nidulans </it>GO annotation to seven other <it>Aspergilli</it>. By depositing the newly mapped GO annotation online as well as integrating it into the web tool FetGOat, we provide new, valuable and easily accessible resources for omics data analysis and interpretation for the genus <it>Aspergillus</it>. Furthermore, we have given a general example of how a well annotated genome can help improving GO annotation of related species to subsequently facilitate the interpretation of omics data.</p
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