The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species.
The authors review the clinical, radiological, electrophysiological, pathological, and molecular aspects of Nasu-Hakola disease (polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy or PLOSL). Nasu-Hakola disease is a unique disease characterized by multiple bone cysts associated with a peculiar form of neurodegeneration that leads to dementia and precocious death usually during the fifth decade of life. The diagnosis can be established on the basis of clinical and radiological findings. Recently, molecular analysis of affected families revealed mutations in the DAP12 (TYROBP) or TREM2 genes, providing an interesting example how mutations in two different subunits of a multi-subunit receptor complex result in an identical human disease phenotype. The association of PLOSL with mutations in the DAP12 or TREM2 genes has led to improved diagnosis of affected individuals. Also, the possible roles of the DAP12/TREM2 signaling pathway in microglia and osteoclasts in humans are just beginning to be elucidated. Some aspects of this peculiar signaling pathway are discussed here.
Background Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.Methodology/Principal FindingsThe T. rangeli haploid genome is ∼24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heat-shock proteins.Conclusions/SignificancePhylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets.
Ten chalcones were synthesized and tested as potential leishmanicidal and trypanocidal agents. All tested compounds caused concentration-dependent inhibition of the in vitro growth of Leishmania braziliensis and Trypanosoma cruzi with no significant toxic effect towards host macrophages. Our results show that the positions of the substituents seem to be critical for their antiprotozoal activities.Among the kinetoplastid protozoa, which infect invertebrates, mammals, and plants, some species are of particular interest due to their medical importance. These include Trypanosoma cruzi (the agent of Chagas' disease), the African trypanosome responsible for sleeping sickness, and several species of Leishmania, which cause the various forms of leishmaniasis (9). The World Health Organization has identified Chagas' disease and leishmaniasis as major and increasing public health problems, particularly in Latin America (14,15,16,18). In spite of the socioeconomic importance of these tropical infectious diseases, efforts directed towards the discovery of new drugs and/or vaccines against them are underdeveloped (10, 13). In addition, most of the drugs currently in use (i) were developed several decades ago, (ii) show variable efficacy, (iii) have serious side effects, (iv) are expensive, (v) can require long-term treatment, (vi) may have low activity in immunosuppressed patients, and (vii) present and/or induce resistance in parasites (9, 10, 16). Thus, the need for the development of new, effective, cheap, and safe drugs for the treatment of leishmaniasis and Chagas' disease is very important.Chalcones, or 1,3-diaryl-2-propen-1-ones, are natural or synthetic compounds belonging to the flavonoid family. Chalcones possess a broad spectrum of biological activities, including antibacterial, anthelmintic, amoebicidal, antiulcer, antiviral, insecticidal, antiprotozoal, anticancer, cytotoxic, and immunosuppressive activities (for reviews, see references 11 and 12). The present study was designed to determine the in vitro leishmanicidal and trypanocidal activities of the 10 substitutioncontaining chalcones and to investigate the cytotoxic effects of these chalcones on mouse peritoneal macrophages in vitro.The chalcones used in the present study were synthesized in our laboratory by reaction of the appropriate aryl methyl ketone and aryl aldehyde (in a 1:1 ratio) in the presence of sodium hydroxide and ethanol. The products were then added to cooled diluted acetic acid according to the methodology previously described (8). The synthetic reaction gave substantial yields (55 to 98%) of all the chalcones, and these were characterized by 1 H nuclear magnetic resonance and infrared analyses and by microanalysis. The substitution-containing chalcones were dissolved in 0.5% Tween 80 in phosphatebuffered saline to prepare a working solution with a 0.1 M concentration before being passed through 0.22-m-pore-size Millipore filters. The structures of the chalcones are shown in Table 1.Cultures of promastigote forms of Leishmania braziliensis...
Avian malaria is a mosquito-borne disease caused by Plasmodium spp. Avian plasmodia are recognized conservation-threatening pathogens due to their potential to cause severe epizootics when introduced to bird populations with which they did not co-evolve. Penguins are considered particularly susceptible, as outbreaks in captive populations will often lead to high morbidity and rapid mortality. We used a multidisciplinary approach to investigate an outbreak of avian malaria in 28 Magellanic penguins (Spheniscus magellanicus) at a rehabilitation center during summer 2009 in Florianópolis, Brazil. Hemosporidian infections were identified by microscopic and molecular characterization in 64% (18/28) of the penguins, including Plasmodium (Haemamoeba) tejerai, Plasmodium (Huffia) elongatum, a Plasmodium (Haemamoeba) sp. lineage closely related to Plasmodium cathemerium, and a Haemoproteus (Parahaemoproteus) sp. lineage closely related to Haemoproteus syrnii. P. tejerai played a predominant role in the studied outbreak and was identified in 72% (13/18) of the hemosporidian-infected penguins, and in 89% (8/9) of the penguins that died, suggesting that this is a highly pathogenic parasite for penguins; a detailed description of tissue meronts and lesions is provided. Mixed infections were identified in three penguins, and involved P. elongatum and either P. tejerai or P. (Haemamoeba) sp. that were compatible with P. tejerai but could not be confirmed. In total, 32% (9/28) penguins died over the course of 16 days despite oral treatment with chloroquine followed by sulfadiazine-trimethoprim. Hemosporidian infections were considered likely to have occurred during rehabilitation, probably from mosquitoes infected while feeding on local native birds, whereas penguin-mosquito-penguin transmission may have played a role in later stages of the outbreak. Considering the seasonality of the infection, rehabilitation centers would benefit from narrowing their efforts to prevent avian malaria outbreaks to the penguins that are maintained throughout summer.
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