Characterizing the diversity and structure of host–parasite communities is crucial to understandingtheir eco-evolutionary *** and related haemosporidian parasites are responsible forfitness loss and mortality in bird...
详细信息
Characterizing the diversity and structure of host–parasite communities is crucial to understandingtheir eco-evolutionary *** and related haemosporidian parasites are responsible forfitness loss and mortality in bird species ***,despite exhibiting the greatest ornithologicalbiodiversity,avian haemosporidians from Neotropical regions are quite ***,we analyze the genetic diversity of bird haemosporidian parasites(Plasmodium andHaemoproteus)in 1,336 individuals belonging to 206 bird species to explore for differences in diversityof parasite lineages and bird species across 5 well-differentiated Peruvian *** 70 different haemosporidian lineages infecting 74 bird *** showed that 25 out ofthe 70 haplotypes had not been previously ***,we also identified 81 new host–parasite interactions representing new host records for these haemosporidian *** outcomesrevealed that the effective diversity(as well as the richness,abundance,and Shannon–Weaver index)for both birds and parasite lineages was higher in Amazon basin ***,we also showed that ecoregions with greater diversity of bird species also had highparasite richness,hence suggesting that host community is crucial in explaining parasite *** parasites were found in ecoregions with lower bird diversity,implying that the abundanceand richness of hosts may shape the exploitation strategy followed by haemosporidian *** outcomes reveal that Neotropical region is a major reservoir of unidentified *** studies analyzing host distribution and specificity of these parasites inthe tropics will provide important knowledge about phylogenetic relationships,phylogeography,and patterns of evolution and distribution of haemosporidian parasites.
An 11 year old, hispanic girl with a history of B-cell acute lymphoblastic leukemia was admitted to the hospital for symptoms compatible with Bartonella henselae infection. The first molecularly diagnosed case of diss...
详细信息
An 11 year old, hispanic girl with a history of B-cell acute lymphoblastic leukemia was admitted to the hospital for symptoms compatible with Bartonella henselae infection. The first molecularly diagnosed case of disseminated Bartonella henselae infection was reported in an immunocompromised patient in Lima, Peru. The analysis was confirmed by Polymerase Chain Reaction and automated sequencing of a liver biopsy sample, even though the serologic tests were negative. In conclusion, Bartonella spp. infection should have a particular diagnostic consideration in immunocompromised patients with fever of unknown origin and further investigation regarding the patient's past exposures with cats should also be elicited.
Chitosan has a unique chemical structure with high charge density, reactive hydroxyl and amino groups, and extensive hydrogen bonding. Chitin deacetylase (EC 3.***.1.41) catalyzes the hydrolysis of the N-acetamido group...
详细信息
Chitosan has a unique chemical structure with high charge density, reactive hydroxyl and amino groups, and extensive hydrogen bonding. Chitin deacetylase (EC 3.***.1.41) catalyzes the hydrolysis of the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin, converting it to chitosan and releasing acetate. The entire ORF of the CDA2 gene encoding one of the two isoforms of chitin deacetylase from Saccharomyces cerevisiae was cloned in Pichia pastoris. The Tg (Cda2-6xHis)p was expressed at high levels as a soluble intracellular protein after induction of the recombinant yeast culture with methanol, and purified using nickel-nitrilotriacetic acid chelate affinity chromatography, resulting in a protein preparation with a purity of >98% and an overall yield of 79%. Chitin deacetylase activity was measured by a colorimetric method based on the O-phthalaldehyde reagent, which detects primary amines remaining in chitinous substrate after acetate release. The recombinant enzyme could deacetylate chitin, chitobiose, chitotriose and chitotetraose, with an optimum temperature of 50°C and pH 8.0, determined using oligochitosaccharides as the substrates. The recombinant protein was also able to deacetylate its solid natural substrate, shrimp chitin, to a limited extent, producing chitosan with a degree of acetylation (DA) of 89% as determined by Fourier transform infrared spectroscopy. The degree of deacetylation was increased by pre-hydrolysis of crystalline shrimp chitin by chitinases, which increased the deacetylation ratio triggered by chitin deacetylase, producing chito-oligosaccharides with a degree of acetylation of 33%. The results described here open the possibility to use the rCda2p, combined with chitinases, for biocatalytic conversion of chitin to chitosan with controlled degrees of deacetylation. We show herein that the crystalline chitin form can be cleanly produced in virtually quantitative yield if a combined and sequential enzyme treatment is performed.
暂无评论