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141.
Alexander W. Pfaff Alejandra de-la-Torre Elise Rochet Julie Brunet Marcela Sabou Arnaud Sauer Tristan Bourcier Jorge E. Gomez-Marin Ermanno Candolfi 《International journal for parasitology》2014
Retinal lesions or other ocular manifestations are serious consequences of infection with the protozoan parasite Toxoplasma gondii. Whilst classically considered a consequence of congenital transmission, recent screening studies estimated that 2% of T. gondii seropositive persons in Europe and North America have retinal lesions, most of them persisting unnoticed. The situation is more dramatic in South America, probably due to the predominance of virulent strains. Some of these strains seem to exhibit ocular or neuronal tropism and are responsible for severe ocular lesions. Despite the medical importance, the physiopathological mechanisms have only recently begun to be elucidated. The particular immune-privileged situation in the eye has to be considered. Studies on French patients showed low or undetectable ocular parasite loads, but a clear Th1/Th17 type immune reaction. Suitable mouse models have appeared in the last few years. Using such a model, IL-17A proved to impair parasite control and induce pathology. In contrast, in South American patients, the parasite seems to be much less efficiently controlled through a Th2 type or suppressive immune response that favors parasite replication. Finally, several host genetic markers controlling immune response factors have been associated with ocular involvement of T. gondii infection, mainly in South America. 相似文献
142.
Rafael Prados-Rosales Brian C. Weinrick Daniel G. Piqué William R. Jacobs Jr. Arturo Casadevall G. Marcela Rodriguez 《Journal of bacteriology》2014,196(6):1250-1256
Mycobacterium tuberculosis releases membrane vesicles packed with molecules that can modulate the immune response. Because environmental conditions often influence the production and content of bacterial vesicles, this study examined M. tuberculosis microvesicles released under iron limitation, a common condition faced by pathogens inside the host. The findings indicate that M. tuberculosis increases microvesicle production in response to iron restriction and that these microvesicles contain mycobactin, which can serve as an iron donor and supports replication of iron-starved mycobacteria. Consequently, the results revealed a role of microvesicles in iron acquisition in M. tuberculosis, which can be critical for survival in the host. 相似文献
143.
144.
Lia Frenkel Beatriz Dimant Enrique L. Portiansky Hans Imboden Héctor Maldonado Alejandro Delorenzi 《Cell and tissue research》2010,341(1):181-195
The angiotensins constitute a neuropeptidergic system that emerged early in evolution. Their classical osmoregulatory and dipsogenic functions and their mnemonic actions have been demonstrated both in vertebrates and in some invertebrates. Previously, we have shown that, in the euryhaline and semiterrestrial crab Chasmagnathus granulatus, water deprivation correlates with an increased level of brain angiotensin-II-like neuropeptide/s (ANGII-like) and improves memory processes through ANGII receptors. We have proposed that the release of brain angiotensins in response to water shortages is an ancient mechanism for coordinating various functions that, together, enable organisms to tolerate this environmental change. Here, we have evaluated the physiological changes in ANGII-like levels in diverse structures of the central nervous system of these animals during water deprivation. The neuroanatomical distribution of ANGII-like is described in the optic lobes and brain of Chasmagnathus granulatus and the physiological changes in ANGII-like distribution in various brain neuropils is evaluated after water deprivation. Our results indicate that ANGII-like is widely distributed, especially in the medial protocerebrum. After 2 h of water deprivation, ANGII-like immunoreactivity increases in the central body and decreases in the olfactory neuropil and, after 6 h of water deprivation, is markedly reduced in several brain areas. Although further experiments are needed to establish that the angiotensinergic system is involved in the balance of body fluids in this crab, our results suggest that ANGII regulates several functions during water shortages. 相似文献
145.
Eric Bautista-Guerrero Jose Luis Carballo Manuel Maldonado 《Invertebrate Biology》2010,129(4):285-296
Abstract. Individuals of the recently described demosponge Thoosa mismalolli are common on Mexican Pacific coral reefs, excavating burrows in living corals and in other calcareous substrata. To better understand the propagative abilities of this sponge, we conducted a histological study over an 18-month period (May 2007–November 2008) to identify sexual and asexual reproductive structures. Members of the species are viviparous and hermaphroditic, with various developmental stages of oocytes, spermatic cysts, and embryos co-occurring in the mesohyl for most of the year. This nearly continuous reproductive activity intensified during the warm season. Fertilization was internal, and embryos developed inside the parental sponge to produce an unciliated hoplitomella larva, characterized by a peculiar siliceous skeleton. In addition to the sexually generated larvae, adults of T. mismalolli formed gemmules for asexual reproduction. Gemmules occurred within the mesohyl during all months of the year, but were most abundant in the coldest months. This combination of sexual and asexual processes enables individuals of T. mismalolli to reproduce almost continuously. This strategy may facilitate both long-term persistence within reefs and effective dispersal between distant reefs. 相似文献
146.
Kap‐Hoon Han Yoon‐Hee Chun Bárbara De Castro Pimentel Figueiredo Frederico Marianetti Soriani Marcela Savoldi Agostinho Almeida Fernando Rodrigues Charlie Timothy Cairns Elaine Bignell Jaqueline Moisés Tobal Maria Helena S. Goldman Jong‐Hwan Kim Yong‐Sun Bahn Gustavo Henrique Goldman Márcia Eliana Da Silva Ferreira 《Molecular microbiology》2010,75(6):1372-1388
Carbon dioxide (CO2) and its hydration product bicarbonate (HCO3‐) are essential molecules in various physiological processes of all living organisms. The reversible interconversion between CO2 and HCO3‐ is in equilibrium. This reaction is slow without catalyst, but can be rapidly facilitated by Zn2+‐metalloenzymes named carbonic anhydrases (CAs). To gain an insight into the function of multiple clades of fungal CA, we chose to investigate the filamentous fungi Aspergillus fumigatus and A. nidulans. We identified four and two CAs in A. fumigatus and A. nidulans, respectively, named cafA‐D and canA‐B. The cafA and cafB genes are constitutively, strongly expressed whereas cafC and cafD genes are weakly expressed but CO2‐inducible. Heterologous expression of the A. fumigatus cafB, and A. nidulans canA and canB genes completely rescued the high CO2‐requiring phenotype of a Saccharomyces cerevisiaeΔnce103 mutant. Only the ΔcafAΔcafB and ΔcanB deletion mutants were unable to grow at 0.033% CO2, of which growth defects can be restored by high CO2. Defects in the CAs can affect Aspergilli conidiation. Furthermore, A. fumigatusΔcafA, ΔcafB, ΔcafC, ΔcafD and ΔcafAΔcafB mutant strains are fully virulent in a low‐dose murine infection. 相似文献
147.
Tobias Manigold Andrés Mori Rebecca Graumann Elena Llop Valeska Simon Marcela Ferrés Francisca Valdivieso Constanza Castillo Brian Hjelle Pablo Vial 《PLoS pathogens》2010,6(2)
In man, infection with South American Andes virus (ANDV) causes hantavirus cardiopulmonary syndrome (HCPS). HCPS due to ANDV is endemic in Southern Chile and much of Argentina and increasing numbers of cases are reported all over South America. A case-fatality rate of about 36% together with the absence of successful antiviral therapies urge the development of a vaccine. Although T-cell responses were shown to be critically involved in immunity to hantaviruses in mouse models, no data are available on the magnitude, specificity and longevity of ANDV-specific memory T-cell responses in patients. Using sets of overlapping peptides in IFN-γ ELISPOT assays, we herein show in 78 Chilean convalescent patients that Gn-derived epitopes were immunodominant as compared to those from the N- and Gc-proteins. Furthermore, while the relative contribution of the N-specific response significantly declined over time, Gn-specific responses remained readily detectable ex vivo up to 13 years after the acute infection. Tetramer analysis further showed that up to 16.8% of all circulating CD3+CD8+ T cells were specific for the single HLA-B*3501-restricted epitope Gn465–473 years after the acute infection. Remarkably, Gn465–473–specific cells readily secreted IFN-γ, granzyme B and TNF-α but not IL-2 upon stimulation and showed a ‘revertant’ CD45RA+CD27−CD28−CCR7−CD127− effector memory phenotype, thereby resembling a phenotype seen in other latent virus infections. Most intriguingly, titers of neutralizing antibodies increased over time in 10/17 individuals months to years after the acute infection and independently of whether they were residents of endemic areas or not. Thus, our data suggest intrinsic, latent antigenic stimulation of Gn-specific T-cells. However, it remains a major task for future studies to proof this hypothesis by determination of viral antigen in convalescent patients. Furthermore, it remains to be seen whether Gn-specific T cells are critical for viral control and protective immunity. If so, Gn-derived immunodominant epitopes could be of high value for future ANDV vaccines. 相似文献
148.
Influence of Cross-linked Waxy Maize Starch on the Aggregation Behavior of Casein Micelles During Acid-induced Gelation 总被引:1,自引:0,他引:1
The influence of cross-linked waxy maize starch on the aggregation behavior of casein micelles was investigated using a combination
of physico-chemical techniques. Milk was homogenized at two different temperatures (55 and 65 °C) and then heated at 95 °C
for 5 min in a pilot scale system. The possible interactions between modified starch and milk proteins during lactic acid
fermentation were evaluated. While 1% starch did not show differences in the whey protein complexes formed during heating
compared to milk with no starch (as measured by size exclusion chromatography), a higher (2.5%) concentration of starch clearly
showed an increased amount of heat-induced whey protein aggregates. The gelation pH also increased significantly with 2.5%
starch compared to that of the control samples. The storage modulus (G′) increased with increasing levels of starch, and confocal
microscopy confirmed that the microstructure of the casein gels was altered by the presence of modified starch. Milk-starch
mixtures preheated and homogenized at 55 or 65 °C exhibited similar physico-chemical behavior during acidification. The results
suggested a lack of interaction between starch granules and casein micelles during acidification, and scanning electron microscopy
images collected with a self-assembled monolayer technique also confirmed that starch granules were not attached to milk caseins
but only embedded in the protein gel matrix. 相似文献
149.
The physico-chemical properties of skim milk containing κ-carrageenan (in the concentration range 0–0.06% w/v), flaxseed gum (in the concentration range 0–0.40% w/v), or a mixture of both polysaccharides were studied using dynamic light scattering, under diluted conditions, as well as
in situ, undiluted, using diffusing wave spectroscopy (DWS) and ultrasonic spectroscopy. Flaxseed gum causes phase separation in
milk mixtures, because of thermodynamic incompatibility between the casein micelles and the polysaccharide chains. Confocal
microscopy and ultrasonic spectroscopy showed that while the addition of 0.01% κ-carrageenan was not sufficient to hinder
phase separation, when 0.03% was added, the helix–helix interactions between κ-carrageenan molecules were sufficient to form
a network and stabilize the system. DWS clearly demonstrated that clusters of casein micelles still form even at very low
concentrations of polysaccharides (below the visible phase separation threshold) and that κ-carrageenan hinders visible phase
separation by decreasing the mobility of the casein micelles. 相似文献
150.
Elizabeth A. Archie Tammy Henry Jesus E. Maldonado Cynthia J. Moss Joyce H. Poole Virginia R. Pearson Suzan Murray Susan C. Alberts Robert C. Fleischer 《Immunogenetics》2010,62(2):85-100
Genes of the vertebrate major histocompatibility complex (MHC) are crucial to defense against infectious disease, provide
an important measure of functional genetic diversity, and have been implicated in mate choice and kin recognition. As a result,
MHC loci have been characterized for a number of vertebrate species, especially mammals; however, elephants are a notable
exception. Our study is the first to characterize patterns of genetic diversity and natural selection in the elephant MHC.
We did so using DNA sequences from a single, expressed DQA locus in elephants. We characterized six alleles in 30 African
elephants (Loxodonta africana) and four alleles in three Asian elephants (Elephas maximus). In addition, for two of the African alleles and three of the Asian alleles, we characterized complete coding sequences
(exons 1–5) and nearly complete non-coding sequences (introns 2–4) for the class II DQA loci. Compared to DQA in other wild
mammals, we found moderate polymorphism and allelic diversity and similar patterns of selection; patterns of non-synonymous
and synonymous substitutions were consistent with balancing selection acting on the peptides involved in antigen binding in
the second exon. In addition, balancing selection has led to strong trans-species allelism that has maintained multiple allelic
lineages across both genera of extant elephants for at least 6 million years. We discuss our results in the context of MHC
diversity in other mammals and patterns of evolution in elephants. 相似文献