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91.
María Lourdes Acosta Asterio Sánchez Francisco García Antonio Contreras Emilio Molina 《Cytotechnology》2007,54(3):189-200
Batch cultures were carried out to study the kinetic, stoichiometry, and regulation of glucose and glutamine metabolism of
a murine hybridoma line. Asymmetric logistic equations (ALEs) were used to fit total and viable cell density, and nutrient
and metabolite/product concentrations. Since these equations were analytically differentiable, specific rates and yield coefficients
were readily calculated. Asymmetric logistic equations described satisfactorily uncontrolled batch cultures, including death
phase. Specific growth rate showed a Monod-type dependence on initial glucose and glutamine concentrations. Yield coefficients
of cell and lactate from glucose, and cell and ammonium from glutamine were all found to change dramatically at low residual
glucose and glutamine concentrations. Under stoichiometric glucose limitation, the glucose-to-cell yield increased and glucose-to-lactate
yield decreased, indicating a metabolic shift. Under stoichiometric glutamine limitation the glutamine-to-cell and glutamine-to-ammonium
yields increased, but also glucose-to-cell yield increased and the glucose-to-lactate yield decreased. Monoclonal antibody
production was mainly non-growth associated, independently of glucose and glutamine levels. 相似文献
92.
Pedro Moral Esther Esteban Sergi Vives Neus Valveny Domingo I. Toja Emilio Gonzalez-Reimers 《American journal of physical anthropology》1997,102(3):337-349
Data on six protein polymorphisms (19 alleles) from the human population of Tenerife are presented and discussed along with other classical markers in relation to the origin of the Canarians. Genetic influences from three population groups were considered: the Iberians, and the Berbers and non-Berbers (Arabs) from north Africa. The systems examined show the Tenerife population lies within the limits of variation described for various Iberian groups, with a slight tendency towards the characteristics of north African populations. When blood groups, red cell enzymes and serum protein data were considered, the similarity of the Canary population to Iberians seems strengthened (70% estimated contribution of Iberian peninsula genes to the present-day Canarian pool), while some relation with north African groups is shown. Genetic distances between Canarians and Arabs and Canarians and Berbers are lower than those between the two north African groups, indicating a relative and comparable contribution of each to the present-day gene pool of the Canarian population. The Arab contribution could be attributable to the slaves who were introduced to these islands after the conquest in the 15th century, while the Berber contribution could be the remnants of the extinct aboriginal peoples of the islands (Guanches) or a more recent immigration due to slavery. Genetic data do not allow us to distinguish between these two possibilities. Am. J. Phys. Anthropol. 102:337–349, 1997. © 1997 Wiley-Liss, Inc. 相似文献
93.
Increased attention towards the Neotropical cats Leopardus guttulus and L. geoffroyi was prompted after genetic studies identified the occurrence of extensive hybridization between them at their geographic contact zone in southern Brazil. This is a region where two biomes intersect, each of which is associated with one of the hybridizing species (Atlantic Forest with L. guttulus and Pampas with L. geoffroyi). In this study, we conducted in-depth analyses of multiple molecular markers aiming to characterize the magnitude and spatial structure of this hybrid zone. We also performed a morphological assessment of these species, aiming to test their phenotypic differentiation at the contact zone, as well as the correlation between morphological features and the admixture status of the individuals. We found strong evidence for extensive and complex hybridization, with at least 40% of the individuals sampled in Rio Grande do Sul state (southernmost Brazil) identified as hybrids resulting from post-F1 generations. Despite such a high level of hybridization, samples collected in this state still comprised two recognizable clusters (genetically and morphologically). Genetically pure individuals were sampled mainly in regions farther from the contact zone, while hybrids concentrated in a central region (exactly at the interface between the two biomes). The morphological data set also revealed a strong spatial structure, which was correlated with the molecular results but displayed an even more marked separation between the clusters. Hybrids often did not present intermediate body sizes and could not be clearly distinguished morphologically from the parental forms. This observation suggests that some selective pressure may be acting on the hybrids, limiting their dispersal away from the hybrid zone and perhaps favoring genomic combinations that maintain adaptive phenotypic features of one or the other parental species. 相似文献
94.
95.
Although Zygomycetes, Fusarium spp, and Scedosporium spp are far less frequent causes of invasive fungal disease than Aspergillus and Candida, they are emerging. These types of infections in severely immunocompromised patients have a common feature: a poor clinical
response to antifungal therapy. Infection is usually airborne, although local infections in cases of skin trauma are also
possible. These fungi are resistant to some common antifungal agents; therefore, surgical debridement of the necrotic tissue,
when possible, should be combined with specific systemic antifungal treatment in immunocompromised patients. In the absence
of randomized clinical trials, most experience in the treatment of these infections is with amphotericin B. Experience with
new antifungal agents is still limited, and recovery from neutropenia remains the main predictor of a favorable outcome. 相似文献
96.
Susana Suárez‐Seoane Emilio Virgós Olga Terroba Xosé Pardavila Jose M. Barea‐Azcón 《Ecography》2014,37(3):279-292
Scaling is a key process in modelling approaches since it allows for translating information from one scale to another. However, the success of this procedure may depend on ‘source’ and ‘target’ scales, but also on the biogeographic/ecological context of the study area. We aimed to quantify the performance and success of scaling species distribution model (SDM) predictions across spatial resolution and extent along a biogeographic gradient using the Iberian mole as study case. We ran separate MaxEnt models at two extents (national and regional) using independent datasets (species locations and environmental predictors) collected at 10 km and 50 m resolutions respectively. Model performance and success of scaling SDMs were quantified on the basis of accuracy measures and spatial predictions. Complementarily, we calculated marginality and tolerance as indicators of habitat availability and niche truncation along the biogeographic gradient. Model performance increased with resolution and extent, as well as from north to south (mainly for high resolution models). When regional models were validated at different scales, their performance reduced severely, particularly in the case of coarse resolution models (some of them performed worse than random). However, when the 10 km‐national model was downscaled within regions, it performed better (AUCtest: 0.82, 0.85 and 0.55 respectively for Galicia, Madrid and Granada) than models specifically calibrated within each region at 10 km (0.47, 0.65, 0.44). Indeed, it also had a better accuracy when projected at 50 m (0.77, 0.91, 0.79) than models fitted at that resolution (0.62, 0.83, 0.96) in two of the three cases. The success of scaling model predictions decreased along the biogeographic gradient, being these differences associated to niche truncation. Models representing non‐truncated niches were more successfully scaled across resolutions and extents (particularly in areas not offering all possible habitats for species), which has important implications for SDM applications. 相似文献
97.
Gil DF García-Fernández R Alonso-del-Rivero M Lamazares E Pérez M Varas L Díaz J Chávez MA González-González Y Mansur M 《FEMS yeast research》2011,11(7):575-586
Pichia pastoris is a highly successful system for the large-scale expression of heterologous proteins, with the added capability of performing most eukaryotic post-translational modifications. However, this system has one significant disadvantage - frequent proteolytic degradation by P. pastoris proteases of heterologously expressed proteins. Several methods have been proposed to address this problem, but none has proven fully effective. We tested the effectiveness of a broad specificity protease inhibitor to control proteolysis. A recombinant variant of the BPTI-Kunitz protease inhibitor ShPI-1 isolated from the sea anemone Stichodactyla helianthus, was expressed in P. pastoris. The recombinant inhibitor (rShPI-1A), containing four additional amino acids (EAEA) at the N-terminus, was folded similarly to the natural inhibitor, as assessed by circular dichroism. rShPI-1A had broad protease specificity, inhibiting serine, aspartic, and cysteine proteases similarly to the natural inhibitor. rShPI-1A protected a model protein, recombinant human miniproinsulin (rhMPI), from proteolytic degradation during expression in P. pastoris. The addition of purified rShPI-1A at the beginning of the induction phase significantly protected rhMPI from proteolysis in culture broth. The results suggest that a broad specificity protease inhibitor such as rShPI-1A can be used to improve the yield of recombinant proteins secreted from P. pastoris. 相似文献
98.
A recipe for postfledging survival in great tits Parus major: be large and be early (but not too much) 下载免费PDF全文
Samuel Rodríguez Arie J. van Noordwijk Elena Álvarez Emilio Barba 《Ecology and evolution》2016,6(13):4458-4467
Survival of juveniles during the postfledging period can be markedly low, which may have major consequences on avian population dynamics. Knowing which factors operating during the nesting phase affect postfledging survival is crucial to understand avian breeding strategies. We aimed to obtain a robust set of predictors of postfledging local survival using the great tit (Parus major) as a model species. We used mark–recapture models to analyze the effect of hatching date, temperatures experienced during the nestling period, fledging size and body mass on first‐year postfledging survival probability of great tit juveniles. We used data from 5192 nestlings of first clutches ringed between 1993 and 2010. Mean first‐year postfledging survival probability was 15.2%, and it was lower for smaller individuals, as well as for those born in either very early or late broods. Our results stress the importance of choosing an optimum hatching period, and raising large chicks to increase first‐year local survival probability in the studied population. 相似文献
99.
Diana C. Tan Gavin R. Flematti Emilio L. Ghisalberti Krishnapillai Sivasithamparam Sukumar Chakraborty Friday Obanor Martin John Barbetti 《Mycotoxin Research》2011,27(2):123-135
Sheep grazing in Western Australia can partially or completely refuse to consume annual Medicago pods contaminated with a number of different Fusarium species. Many Fusarium species are known to produce trichothecenes as part of their array of toxigenic secondary metabolites, which are known to
cause feed refusal in animals. This study reports the identity of Fusarium species using species-specific PCR primers and a characterization of the toxigenic secondary metabolites produced by 24 Fusarium isolates associated with annual legume-based pastures and particularly those associated with sheep feed refusal disorders
in Western Australia. Purification of the fungal extracts was facilitated by a bioassay-guided fractionation using brine shrimp.
A number of trichothecenes (3-acetyldeoxynivalenol, deoxynivalenol, fusarenon-X, monoacetoxyscirpenols, diacetoxyscirpenol,
scirpentriol, HT-2 toxin and T-2 toxin), enniatins (A, A1, B, and B1), chlamydosporol and zearalenone were identified using
GC/MS and/or NMR spectroscopy. Some of the crude extracts and fractions showed significant activity against brine shrimp at
concentrations as low as 5 μg ml-1, and are likely to be involved in the sheep feed refusal disorders. This is the first report of chlamydosporol production
by confirmed Fusarium spp.; of the incidence of F. brachygibbosum and F. venenatum in Australia and of F. tricinctum in Western Australia; and of mycotoxin production by Fusarium species from Western Australia. 相似文献
100.
Emilio Maran Pedro Cermeo Daffne C. Lpez‐Sandoval Tamara Rodríguez‐Ramos Cristina Sobrino María Huete‐Ortega Jos María Blanco Jaime Rodríguez 《Ecology letters》2013,16(3):371-379
Phytoplankton size structure is key for the ecology and biogeochemistry of pelagic ecosystems, but the relationship between cell size and maximum growth rate (μmax) is not yet well understood. We used cultures of 22 species of marine phytoplankton from five phyla, ranging from 0.1 to 106 μm3 in cell volume (Vcell), to determine experimentally the size dependence of growth, metabolic rate, elemental stoichiometry and nutrient uptake. We show that both μmax and carbon‐specific photosynthesis peak at intermediate cell sizes. Maximum nitrogen uptake rate (VmaxN) scales isometrically with Vcell, whereas nitrogen minimum quota scales as Vcell0.84. Large cells thus possess high ability to take up nitrogen, relative to their requirements, and large storage capacity, but their growth is limited by the conversion of nutrients into biomass. Small species show similar volume‐specific VmaxN compared to their larger counterparts, but have higher nitrogen requirements. We suggest that the unimodal size scaling of phytoplankton growth arises from taxon‐independent, size‐related constraints in nutrient uptake, requirement and assimilation. 相似文献