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991.
992.
Hwang IK Lee CH Li H Yoo KY Choi JH Kim DW Kim DW Suh HW Won MH 《Neurochemical research》2008,33(7):1309-1315
Similarities between age-related changes in the canine and human brain have resulted in the general acceptance of the canine brain as a model of human brain aging. The hippocampus is essentially required for intact cognitive ability and appears to be particularly vulnerable to the aging process. We observed changes in ionized calcium-binding adapter molecule 1 (Iba-1, a microglial marker) immunoreactivity and protein levels in the hippocampal dentate gyrus and CA1 region of adult (2-3 years) and aged (10-12 years) dogs. We also observed the interferon-gamma (IFN-gamma), a pro-inflammatory cytokine, protein levels in these groups. In the dentate gyrus and CA1 region of the adult dog, Iba-1 immunoreactive microglia were well distributed and their processes were highly ramified. However, in the aged dog, the processes of Iba-1 immunoreactive microglia were hypertrophied in the dentate gyrus. Moreover, Iba-1 protein level in the dentate gyrus in the aged dog was higher than in the adult dog. IFN-gamma expression was increased in the dentate gyrus homogenates of aged dogs than adult dogs. In addition, we found that some neurons were positive to Fluoro-Jade B (a marker for neuronal degeneration) in the dentate polymorphic layer, but not in the hippocampal CA1 region in the aged dog. These results suggest that Iba-1 immunoreactive microglia are hypertrophied in the dentate gyrus in the aged dog. 相似文献
993.
Shibin Gao Carlos Martinez Debra J. Skinner Alan F. Krivanek Jonathan H. Crouch Yunbi Xu 《Molecular breeding : new strategies in plant improvement》2008,22(3):477-494
Leaf collection from the field, labeling and tracking back to the source plants after genotyping are rate limiting steps in
leaf DNA-based genotyping. In this study, an optimized genotyping method using endosperm DNA sampled from single maize seeds
was developed, which can be used to replace leaf DNA-based genotyping for both genetic studies and breeding applications.
A similar approach is likely to be suitable for all plants with relatively large seeds. Part of the endosperm was excised
from imbibed maize seeds and DNA extracted in 96-tube plates using individuals from eight F2 populations and seven inbreds. The quality of the resultant DNA was functionally comparable to DNA extracted from leaf tissue.
Extraction from 30 mg of endosperm yields 3–10 μg DNA, which is sufficient for analysis of 200–400 agarose-gel PCR-based markers,
with the potential for several million chip-based SNP marker analyses. By comparing endosperm DNA and leaf DNA for individuals
from an F2 population, genotyping errors caused by pericarp contamination and hetero-fertilization were found to average 3.8 and 0.6%,
respectively. Endosperm sampling did not affect germination rates under controlled conditions, although under normal field
conditions the germination rate, seedling establishment, and growth vigor were significantly lower than that of non-sampled
controls for some genotypes. However, careful field management can compensate for these effects. Seed DNA-based genotyping
lowered costs by 24.6% compared to leaf DNA-based genotyping due to reduced field plantings and labor costs. A substantial
advantage of this approach is that it can be used to select desirable genotypes before planting. As such it provides an opportunity
for dramatic improvements in the efficiency and selective gain of breeding systems based on optimum combinations of marker-assisted
selection and phenotypic selection within and between generations. 相似文献
994.
Efficiency,thermodynamic and kinetic stability of marketed gadolinium chelates and their possible clinical consequences: a critical review 总被引:1,自引:0,他引:1
Marc Port Jean-Marc Idée Christelle Medina Caroline Robic Monique Sabatou Claire Corot 《Biometals》2008,21(4):469-490
Gadolinium-based contrast agents are widely used to enhance image contrast in magnetic resonance imaging (MRI) procedures. Over recent years, there has been a renewed interest in the physicochemical properties of gadolinium chelates used as contrast agents for MRI procedures, as it has been suggested that dechelation of these molecules could be involved in the mechanism of a recently described disease, namely nephrogenic systemic fibrosis (NSF). The aim of this paper is to discuss the structure-physicochemical properties relationships of marketed gadolinium chelates in regards to their biological consequences. Marketed gadolinium chelates can be classified according to key molecular design parameters: (a) nature of the chelating moiety: macrocyclic molecules in which Gd3+ is caged in the pre-organized cavity of the ligand, or linear open-chain molecules, (b) ionicity: the ionicity of the complex varies from neutral to tri-anionic agents, and (c) the presence or absence of an aromatic lipophilic residue responsible for protein binding. All these molecular characteristics have a profound impact on the physicochemical characteristics of the pharmaceutical solution such as osmolality, viscosity but also on their efficiency in relaxing water protons (relaxivity) and their biodistribution. These key molecular parameters can also explain why gadolinium chelates differ in terms of their thermodynamic stability constants and kinetic stability, as demonstrated by numerous in vitro and in vivo studies, resulting in various formulations of pharmaceutical solutions of marketed contrast agents. The concept of kinetic and thermodynamic stability is critically discussed as it remains a somewhat controversial topic, especially in predicting the amount of free gadolinium which may result from dechelation of chelates in physiological or pathological situations. A high kinetic stability provided by the macrocyclic structure combined with a high thermodynamic stability (reinforced by ionicity for macrocyclic chelates) will minimize the amount of free gadolinium released in tissue parenchymas. 相似文献
995.
Studer B Boller B Bauer E Posselt UK Widmer F Kölliker R 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(1):9-17
Crown rust, caused by Puccinia coronata f. sp. lolii, is one of the most important diseases of temperate forage grasses, such as ryegrasses (Lolium spp.), affecting yield and nutritional quality. Therefore, resistance to crown rust is a major goal in ryegrass breeding
programmes. In a two-way pseudo-testcross population consisting of 306 Lolium multiflorum individuals, multisite field evaluations as well as alternative methods based on artificial inoculation with natural inoculate
in controlled environments were used to identify QTLs controlling resistance to crown rust. Disease scores obtained from glasshouse
and leaf segment test (LST) evaluations were highly correlated with scores from a multisite field assessment (r = 0.66 and 0.79, P < 0.01, respectively) and thus confirmed suitability of these methods for crown rust investigations. Moreover, QTL mapping
based on a linkage map consisting of 368 amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers
revealed similar results across different phenotyping methods. Two major QTLs were consistently detected on linkage group
(LG) 1 and LG 2, explaining up to 56% of total phenotypic variance (V
p). Nevertheless, differences between position and magnitude of QTLs were observed among individual field locations and suggested
the existence of specific local pathogen populations. The present study not only compared QTL results among crown rust evaluation
methods and environments, but also identified molecular markers closely linked to previously undescribed QTLs for crown rust
resistance in Italian ryegrass with the potential to be applied in marker-assisted forage crop breeding.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
996.
Despite the great importance of Aureobasidium pullulans in biotechnology, the fungus had emerged as an opportunistic human pathogen, especially among immunocompromised patients.
Clinical detection of this rare human fungal pathogen presently relies on morphology diagnosis which may be misleading. Thus,
a sensitive and accurate quantitative molecular assay for A. pullulans remains lacking. In this study, we presented the microscopy observations of A. pullulans that reveals the phenotypic plasticity of the fungus. A. pullulans-specific primers and molecular beacon probes were designed based on the fungal 18S ribosomal RNA (rRNA) gene. Comparison
of two probes with varied quencher chemistry, namely BHQ-1 and Tamra, revealed high amplification efficiency of 104% and 108%,
respectively. The optimized quantitative real-time PCR (qPCR) assays could detect and quantify up to 1 pg concentration of
A. pullulans DNA. Both assays displayed satisfactory performance parameters at fast thermal cycling mode. The molecular assay has great
potential as a molecular diagnosis tool for early detection of fungal infection caused by A. pullulans, which merits future study in clinical diagnosis. 相似文献
997.
Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red
and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222
Received 12 July 2001/ Accepted in revised form 22 October 2001 相似文献
998.
Acaulescent species of Streptocarpus Lindl. show unusual patterns of growth, characterized by anisocotyly (i.e. the unequal growth of cotyledons after germination)
and lack of a conventional embryonic shoot apical meristem (SAM). A SAM-like structure appears during post-embryonic development
on the axis of the continuously growing cotyledon. Since we have shown previously that KNOX genes are involved in this unusual morphology of Streptocarpus rexii, here we investigated the expression pattern of WUSCHEL (WUS), which is also required for the indeterminacy of the SAM, but is expressed independently from KNOX in Arabidopsis thaliana. In A. thaliana WUSCHEL is involved in the maintenance of the stem cell fate in the organizing centre. The expression pattern of the WUS ortholog in S. rexii (SrWUS) strongly deviates from that of the model plant, suggesting a fundamentally different spatial and temporal regulation of signalling
involved in meristem initiation and maintenance. In S. rexii, exogenous application of growth regulators, i.e. gibberellin (GA3), cytokinin (CK) and a gibberellin biosynthesis inhibitor (PAC), prevents anisocotyly and relocates meristematic cells to
a position of conventional SAMs; this coincides with a re-localization of the two main pathways controlling meristem formation,
the SrWUS and the KNOX pathways. Our results suggest that the establishment of a hormone imbalance in the seedlings is the basis of
anisocotyly, causing a lateral dominance of the macrocotyledon over the microcotyledon. The peculiar morphogenetic program
in S. rexii is linked to this delicate hormone balance and is the result of crosstalk between endogenous hormones and regulatory genes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
999.
Alien plant invasions in tropical and sub-tropical savannas: patterns,processes and prospects 总被引:1,自引:0,他引:1
Llewellyn C. Foxcroft David M. Richardson Marcel Rejmánek Petr Pyšek 《Biological invasions》2010,12(12):3913-3933
Biological invasions affect virtually all ecosystems on earth, but the degree to which different regions and biomes are invaded,
and the quality of information from different regions, varies greatly. A large body of literature exists on the invasion of
savannas in the Neotropics and northern Australia where invasive plants, especially African grasses, have had major impacts.
Less has been published on plant invasions in African savannas, except for those in South Africa. Negative impacts due to
plant invasions in African savannas appear to be less severe than in other regions at present. As savannas cover about 60%
of the continent, with tens of millions of people relying on the services they provide, it is timely to assess the current
status of invasions as a threat to these ecosystems. We reviewed the literature, contrasting the African situation with that
of Neotropical and Australian savannas. A number of drivers and explanatory factors of plant invasions in savannas have been
described, mostly from the Neotropics and Australia. These include herbivore presence, residence time, intentional introductions
for pasture improvements, fire regimes, the physiology of the introduced species, and anthropogenic disturbance. After comparing
these drivers across the three regions, we suggest that the lower extent of alien plant invasions in African savannas is largely
attributable to: (1) significantly lower rates of intentional plant introductions and widespread plantings (until recently);
(2) the role of large mammalian herbivores in these ecosystems; (3) historical and biogeographical issues relating to the
regions of origin of introduced species; and (4) the adaptation of African systems to fire. We discuss how changing conditions
in the three regions are likely to affect plant invasions in the future. 相似文献
1000.