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MARÍA DE LOURDES MU
OZ MARCOS ROJKIND JESÚS CALDER
N MIGUEL TANIMOTO SERGIO ARIAS-NEGRETE ADOLFO MARTÍNEZ-PALOMO 《The Journal of eukaryotic microbiology》1984,31(3):468-470
Several axenic strains of pathogenic and nonpathogenic Entamoeba histolytica were tested for their capacity to digest native radioactive type I collagen gels and to produce liver abscesses when injected into the liver of newborn hamsters. The results demonstrate that the pathogenic strains of amebas (HM1:IMSS, HM3:IMSS, HM38:IMSS, and HK9) have a collagenolytic activity that closely correlates with their in vivo capacity to produce liver lesions. The nonpathogenic isolate (Laredo) did not show collagenolytic activity and failed to produce lesions in the liver of newborn hamsters. The results also demonstrate that type I collagen obtained from rodents and cats is degraded less by amebic collagenase than is bovine collagen, which is similar to human collagen. These findings suggest that species susceptibility to invasive infection may depend, among other factors, on the characteristics of the extracellular components of host tissues. 相似文献
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SERGIO MOLINARI 《The Annals of applied biology》1991,119(2):373-379
The effect of nematode infestation on the alternative pathway respiration of mitochondria isolated from resistant and susceptible tomato roots greatly depended on the oxidisable substrate tested. The percentage of alternative respiration in NADH, malate and succinate oxidation was markedly different between the resistant (Rossol) and the susceptible (Roma VF) cultivars before infestation. Only the percentage of malate alternative oxidation in mitochondria from the resistant roots was influenced by nematode invasion. Conversely, attacked roots showed consistent variations in the content of mitochondria per unit fresh weight and in the phosphorylation efficiency (ADP/O) of the organelles. Expression of the alternative pathway (ρ' value) was found to be unchanged in intact roots and isolated mitochondria six days after nematode inoculation. 相似文献
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CYRIL BONTEMPS GEOFFREY N. ELLIOTT† MARCELO F. SIMON‡ FÁBIO B. DOS REIS JÚNIOR § EDUARDO GROSS¶ REBECCA C. LAWTON NICOLAU ELIAS NETO MARIA de FÁTIMA LOUREIRO SERGIO M. DE FARIA†† JANET I. SPRENT‡‡ EUAN K. JAMES§§ J. PETER W. YOUNG 《Molecular ecology》2010,19(1):44-52
Burkholderia has only recently been recognized as a potential nitrogen-fixing symbiont of legumes, but we find that the origins of symbiosis in Burkholderia are much deeper than previously suspected. We sampled 143 symbionts from 47 native species of Mimosa across 1800 km in central Brazil and found that 98% were Burkholderia . Gene sequences defined seven distinct and divergent species complexes within the genus Burkholderia . The symbiosis-related genes formed deep Burkholderia -specific clades, each specific to a species complex, implying that these genes diverged over a long period within Burkholderia without substantial horizontal gene transfer between species complexes. 相似文献
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FERNANDO P. RODRIGUES FLVIA S. ROCHA JOS E. GARCIA JOS F. GARCIA MARIO DE VIVO SERGIO R. MATIOLI 《Molecular ecology resources》2006,6(3):686-688
Five microsatellite loci were isolated and characterized within the woolly mouse opossum (Micoureus paraguayanus), a Neotropical marsupial, using an enrichment cloning procedure. Between four and seven alleles were detected per locus, with expected heterozygosity ranging from 0.358 to 0.560. These microsatellites should provide useful markers in a variety of genetic analyses to examine parentage, inbreeding, population structure and population dynamics in fragmented forest habitats. 相似文献
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SERGIO ROSSI HUBERT MORIN ANNIE DESLAURIERS PIERRE‐Y. PLOURDE 《Global Change Biology》2011,17(1):614-625
In the next century, the boreal ecosystems are projected to experience greater rates of warming than most other regions of the world. As the boreal forest constitutes a reservoir of trees of huge ecological importance and only partially known economic potential, any possible climate‐related change in plant growth and dynamics has to be promptly predicted and evaluated. A model for assessing xylem phenology in black spruce [Picea mariana (Mill.) B.S.P.] using daily temperatures and thermal thresholds was defined and applied to predict changes in onset, ending and duration of xylem growth under different warming scenarios with temperatures rising by up to 3 °C. This was achieved by collecting and analyzing a dataset obtained from a 7‐year monitoring of cambium phenology and wood formation on a weekly time‐scale in trees growing in four sites at different latitudes and altitudes in the Saguenay‐Lac‐Saint‐Jean region (Quebec, Canada). The onset of xylem growth occurred between mid‐May and early June while the end ranged between mid‐September and early October, resulting in a growing season of 101–141 days. The model predicted longer duration of xylem growth at higher temperatures, with an increase of 8–11 days/ °C, because of an earlier onset and later ending of growth. With an increase of 3 °C in the mean temperature during the year, the duration of xylem growth changed on average from 125 to 160 days. The predicted changes in cambial phenology could significantly affect future wood production of the boreal ecosystems. 相似文献
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GUILLERMO DEBANDI VALERIA CORBALÁN JOSÉ ALEJANDRO SCOLARO SERGIO ALBERTO ROIG‐JUÑENT 《Austral ecology》2012,37(3):392-400
The genus Phymaturus (Reptilia: Liolaemidae) is distributed in the mountains and rocky plateaux of Argentina and Chile and comprises two groups of species, palluma and patagonicus. The two lineages have diverged early in the evolution of the genus and up to today, there is very little geographical overlap between them. We worked with records of localities from the literature, herpetological collections and field data to evaluate habitat suitability of the genus Phymaturus. We used 11 environmental variables to develop environmental niche models (ENMs) for each group within the genus using the Maxent software, and to determine those variables that best explain the distribution of each group. We also estimated measures of niche similarity using ENMTools to determine whether niche differentiation is real or apparent. The geographical overlap between the groups was very low considering the large geographical range of the genus. Some variables, such as mean annual temperature, soil type and bare soil cover, have a high contribution to the models for both groups. The current niche overlap between Phymaturus groups indicates that the environmental niches of the palluma and patagonicus groups are not equivalent. Based on background analysis, we cannot reject the hypothesis that similarity (or divergence) between groups of Phymaturus is no more than expected based on the availability of habitat. The results of this study are a first approximation to the knowledge of the environmental variables associated with the palluma and patagonicus groups, and reveal that the ecological differences found between these groups are more likely due to habitat availability in their respective regions than to differences in habitat preferences. 相似文献
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Intraguild predation in raptor assemblages: a review 总被引:6,自引:4,他引:2
Intraguild predation, the killing of species that use similar resources, has been largely overlooked in raptor investigations. To help fill this gap in knowledge, we conducted a literature review, focusing on studies that tested the behavioural and demographic impact of intraguild predation on individuals, populations, and assemblages of diurnal and nocturnal raptorial species. Overall, data were available for 39 empirical and experimental studies on 63 populations belonging to 11 killer species and 15 victim species. An overview of these studies suggested that intraguild predation was a widespread, size-based phenomenon. Results from multiple studies on the same species at different locations were usually consistent across wide geographical areas. Individual-level demographic impacts included reduced site-occupancy, breeding success and survival. Individuals of the prey species responded to predation pressure through direct spatial avoidance, risk-sensitive habitat selection, short-term behavioural avoidance (e.g. reduced vocal activity and escape to refugia after predator detection) and, possibly, temporal segregation. Population-level effects were common but mainly examined as spatio-temporal correlations between the abundance of killer and victim species. Correlative evidence also suggested that intraguild predation may have the potential to structure whole raptor assemblages. More studies on other species and different geographic areas are needed to increase our understanding of the causes and consequences of this widespread interaction. From a conservation point of view, intraguild predation may limit the success of raptor preservation programmes and could be used as a management tool through its effect on mesopredator release and its potentially positive, indirect effects on game species. 相似文献
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JAMES K. LIEBHERR JOHN W. M. MARRIS ROWAN M. EMBERSON PAULINE SYRETT SERGIO ROIG‐JUÑENT 《Systematic Entomology》2011,36(3):395-414
Orthoglymma Liebherr, Marris, Emberson, Syrett & Roig‐Juñent gen.n. (Coleoptera: Carabidae: Broscini) is described to accommodate the single type species Orthoglymma wangapeka Liebherr, Marris, Emberson, Syrett & Roig‐Juñent sp.n., known from the Wangapeka Track, Kahurangi National Park, north‐western South Island, New Zealand. Orthoglymma wangapeka sp.n. is analysed cladistically along with a comprehensive array of 42 other broscine generic terminals and four out‐group taxa, using information obtained from 73 morphological characters, and placed as adelphotaxon to the remainder of subtribe Nothobroscina, a clade distributed in New Zealand, southern South America and Australia. Based on fossil evidence for Carabidae, the occurrence of Orthoglymma wangapeka sp.n. on the Buller Terrane, a geological feature once situated on the eastern margin of Gondwana, and early cladistic divergence of Orthoglymma from the remaining Nothobroscina, Orthoglymma wangapeka sp.n. is interpreted as a Gondwanan relict. The New Zealand arthropod fauna is reviewed to identify other taxa in existence at the time of Cretaceous vicariance of New Zealand and Australia. These candidate Gondwanan taxa, all of which are specified using fossil data or molecular divergence‐based estimates, are analysed biogeographically. Where phylogenetic hypotheses are available, primordial distributions are optimized using event‐based, dispersal‐vicariance (DIVA) analysis. The hypothesized Gondwanan‐aged taxa demonstrate inordinate fidelity to the Gondwanan‐aged geological terranes that constitute the western portions of New Zealand, especially in the South Island. Persistence of these relicts through a hypothesized ‘Oligocene drowning’ event is the most parsimonious explanation for the concentration of Gondwanan relicts in the Nelson, Buller and Fiordland districts of the South Island. Geographic patterns of Gondwanan‐aged taxa are compared with distributions of taxa hypothesized to have colonized New Zealand across the Tasman Sea from Australia and New Caledonia, subsequent to Cretaceous vicariance. These post‐Gondwanan taxa exhibit very different patterns of distribution and diversification in New Zealand, including: (i) abundant endemism in Northland, and the islands and peninsulas of the North Island; (ii) species geographically restricted to areas underlain by the youngest Rakaia and Pahau geological terranes; and (iii) species exhibiting exceedingly widespread geographic distributions spanning geological terranes of disparate ages.
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