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41.
Background
Fluorescence activated cell sorting (FACS) is a powerful technique for the qualitative and quantitative detection of biomolecules used widely in both basic research and clinical diagnostic applications. Beads displaying a specific antigen are used to bind antibodies which are then fluorescently labelled using secondary antibodies. As the individual suspension bead passes through the sensing region of the FACS machine, fluorescent signals are acquired and analysed. Currently, antigens are tediously purified and chemically cross-linked to preformed beads. Purification and coupling of proteins often renders them inactive and they will not be displayed in its native configuration. As an alternative, we genetically engineered Escherichia coli to produce biopolyester (polyhdroxyalkanoate=PHA) granules displaying diagnostically relevant antigens in their native conformation and suitable for FACS analysis. 相似文献42.
MicroRNAs show a wide diversity of expression profiles in the developing and mature central nervous system 总被引:7,自引:0,他引:7
Background
MicroRNA (miRNA) encoding genes are abundant in vertebrate genomes but very few have been studied in any detail. Bioinformatic tools allow prediction of miRNA targets and this information coupled with knowledge of miRNA expression profiles facilitates formulation of hypotheses of miRNA function. Although the central nervous system (CNS) is a prominent site of miRNA expression, virtually nothing is known about the spatial and temporal expression profiles of miRNAs in the brain. To provide an overview of the breadth of miRNA expression in the CNS, we performed a comprehensive analysis of the neuroanatomical expression profiles of 38 abundant conserved miRNAs in developing and adult zebrafish brain. 相似文献43.
MARTYN C. LUCAS DAMIAN H. BUBB MIN-HO JANG KYONG HA JEROME E. G. MASTERS 《Freshwater Biology》2009,54(3):621-634
1. Conservation of freshwater animal populations requires their access to, as well as sufficient availability of, critical habitats, such as those for reproduction. Abundant small-scale barriers may cause extensive fragmentation of freshwater habitat but, by comparison to larger structures their effects are rarely considered by catchment managers. The relationship between the distribution of, and access to, spawning habitat in a regulated river, characterized by abundant small barriers, was examined for river lamprey Lampetra fluviatilis , a threatened migratory fish.
2. Telemetry of adult lamprey in the River Derwent, North East England was used to quantify upriver migration and access to spawning habitat, together with surveys of spawning habitat availability and spawning activity between 2002 and 2007.
3. Access in to the Derwent appeared severely restricted by a tidal barrage, beyond which lamprey migrated rapidly in unobstructed reaches. Of all lamprey tagged in the lower 4 km of river, or ascending the barrage, 64% and 17% passed the first and second weirs respectively, with high flows crucial for this. Although over 98% of lamprey spawning habitat occurred more than 51 km upstream, on average just 1.8% of river lamprey spawners were recorded there.
4. In order to protect or rehabilitate species or species assemblages, greater attention needs to be paid to the relative spatial distribution of low-head barriers and the resultant availability of key habitats within individual catchments. This is particularly important given the renewed emphasis internationally on low-head hydropower solutions as a source of renewable energy, and the rapid growth in numbers of low-head barriers in many catchments. 相似文献
2. Telemetry of adult lamprey in the River Derwent, North East England was used to quantify upriver migration and access to spawning habitat, together with surveys of spawning habitat availability and spawning activity between 2002 and 2007.
3. Access in to the Derwent appeared severely restricted by a tidal barrage, beyond which lamprey migrated rapidly in unobstructed reaches. Of all lamprey tagged in the lower 4 km of river, or ascending the barrage, 64% and 17% passed the first and second weirs respectively, with high flows crucial for this. Although over 98% of lamprey spawning habitat occurred more than 51 km upstream, on average just 1.8% of river lamprey spawners were recorded there.
4. In order to protect or rehabilitate species or species assemblages, greater attention needs to be paid to the relative spatial distribution of low-head barriers and the resultant availability of key habitats within individual catchments. This is particularly important given the renewed emphasis internationally on low-head hydropower solutions as a source of renewable energy, and the rapid growth in numbers of low-head barriers in many catchments. 相似文献
44.
Chemopreventive and renal protective effects for docosahexaenoic acid (DHA): implications of CRP and lipid peroxides 总被引:2,自引:0,他引:2
Background
The fish oil-derived ω-3 fatty acids, like docosahexanoic (DHA), claim a plethora of health benefits. We currently evaluated the antitumor effects of DHA, alone or in combination with cisplatin (CP) in the EAC solid tumor mice model, and monitored concomitant changes in serum levels of C-reactive protein (CRP), lipid peroxidation (measured as malondialdehyde; MDA) and leukocytic count (LC). Further, we verified the capacity of DHA to ameliorate the lethal, CP-induced nephrotoxicity in rats and the molecular mechanisms involved therein.Results
EAC-bearing mice exhibited markedly elevated LC (2-fold), CRP (11-fold) and MDA levels (2.7-fold). DHA (125, 250 mg/kg) elicited significant, dose-dependent reductions in tumor size (38%, 79%; respectively), as well as in LC, CRP and MDA levels. These effects for CP were appreciably lower than those of DHA (250 mg/kg). Interestingly, DHA (125 mg/kg) markedly enhanced the chemopreventive effects of CP and boosted its ability to reduce serum CRP and MDA levels. Correlation studies revealed a high degree of positive association between tumor growth and each of CRP (r = 0.85) and leukocytosis (r = 0.89), thus attesting to a diagnostic/prognostic role for CRP. On the other hand, a single CP dose (10 mg/kg) induced nephrotoxicity in rats that was evidenced by proteinuria, deterioration of glomerular filtration rate (GFR, -4-fold), a rise in serum creatinine/urea levels (2–5-fold) after 4 days, and globally-induced animal fatalities after 7 days. Kidney-homogenates from CP-treated rats displayed significantly elevated MDA- and TNF-α-, but reduced GSH-, levels. Rats treated with DHA (250 mg/kg, but not 125 mg/kg) survived the lethal effects of CP, and showed a significant recovery of GFR; while their homogenates had markedly-reduced MDA- and TNF-α-, but -increased GSH-levels. Significant association was detected between creatinine level and those of MDA (r = 0.81), TNF-α ) r = 0.92) and GSH (r = -0.82); implying causal relationships.Conclusion
DHA elicited prominent chemopreventive effects on its own, and appreciably augmented those of CP as well. The extent of tumor progression in various mouse groups was highly reflected by CRP levels (thus implying a diagnostic/prognostic role for CRP). Further, this study is the first to reveal that DHA can obliterate the lethal CP-induced nephrotoxicity and renal tissue injury. At the molecular level, DHA appears to act by reducing leukocytosis, systemic inflammation, and oxidative stress. 相似文献45.
毛乌素沙地南缘沙丘生物结皮中微生物分布特征 总被引:4,自引:0,他引:4
为探明半干旱沙区生物结皮中微生物分布特征,对毛乌素沙地南缘沙丘生物结皮中微生物数量进行了测定。结果表明:微生物总数从丘顶到丘间地呈递增趋势,除丘顶与迎风坡、迎风坡与背风坡结皮层微生物总数差异不显著外,其他各地貌部位结皮层微生物数量之间差异显著。同一地貌部位结皮层、0~5和5~10cm土层微生物垂直分布有变化,其变化规律为:除迎风坡放线菌数量呈先增加后递减、迎风坡微生物总数、细菌、真菌和丘顶真菌数量随剖面的加深呈递减外,其他各地貌部位微生物数量均呈先降低,后增加的趋势。微生物类群的组成表现为细菌最多,放线菌次之,真菌最少。在丘间地细菌所占微生物总数的比例与丘顶相比有所增加,而放线菌和真菌的比例有所减少。结皮下0~5和5~10cm土层微生物分布与土壤含水量的变化同步,说明土壤水分可能是影响微生物垂直分布的重要因子。 相似文献
46.
Taniguchi Y Takeda S Furutani-Seiki M Kamei Y Todo T Sasado T Deguchi T Kondoh H Mudde J Yamazoe M Hidaka M Mitani H Toyoda A Sakaki Y Plasterk RH Cuppen E 《Genome biology》2006,7(12):R116-14
We have established a reverse genetics approach for the routine generation of medaka (Oryzias latipes) gene knockouts. A cryopreserved library of N-ethyl-N-nitrosourea (ENU) mutagenized fish was screened by high-throughput resequencing for induced point mutations. Nonsense and splice site mutations were retrieved for the Blm, Sirt1, Parkin and p53 genes and functional characterization of p53 mutants indicated a complete knockout of p53 function. The current cryopreserved resource is expected to contain knockouts for most medaka genes. 相似文献
47.
van Can HJ te Braake HA Bijman A Hellinga C Luyben KC Heijnen JJ 《Biotechnology and bioengineering》1999,62(6):666-680
There is a need for efficient modeling strategies which quickly lead to reliable mathematical models that can be applied for design and optimization of (bio)-chemical processes. The serial gray box modeling strategy is potentially very efficient because no detailed knowledge is needed to construct the white box part of the model and because covenient black box modeling techniques like neural networks can be used for the black box part of the model. This paper shows for a typical biochemical conversion how the serial gray box modeling strategy can be applied efficiently to obtain a model with good frequency extrapolation properties. Models with good frequency extrapolation properties can be applied under dynamic conditions that were not present during the identification experiments. For a given application domain of a model, this property can be used to considerably reduce the number of identification experiments. The serial gray box modeling strategy is demonstrated to be successful for the modeling of the enzymatic conversion of penicillin G In the concentration range of 10-100 mM and temperature range of 298-335 K. Frequency extrapolation is shown by using only constant temperatures in the (batch) identification experiments, while the model can be used reliable with varying temperatures during the (batch) validation experiments. No reliable frequency extrapolation properties could be obtained for a black box model, and for a more knowledge-driven white box model reliable frequency extrapolation properties could only be obtained by incorporating more knowledge in the model. Copyright 1999 John Wiley & Sons, Inc. 相似文献
48.
A number of studies have suggested that the anionic phospholipid (anPL)-binding protein annexin II may play a role in cytomegalovirus (CMV) infection. Since annexin II has been shown to mediate aggregation and fusion of certain membranes, we investigated whether these properties could be exploited by CMV directly. The experiments showed that purified annexin II, but not the homologous protein annexin V (AnV), can mediate the binding of 35S-CMV (strain AD169) to anPL-coated microtiter wells. This association required Ca2+, could be titrated by varying either annexin II (apparent Kd = 4 x 10(-)8 M) or 35S-CMV, was inhibited by unlabeled CMV, and was observed for the heterotetrameric or monomeric form of annexin II. In experiments utilizing the fluorescence dequenching of octadecyl rhodamine incorporated into the CMV envelope, annexin II was furthermore found to enhance the rate of virus-anPL vesicle fusion. The observed fusion was dependent on the concentration of annexin II, Ca2+, and anPL and was mediated principally by the heterotetramer. Interestingly, AnV was observed to inhibit the effects of annexin II on CMV fusion but not binding to anPL, which indicates that annexin II enhances these processes by distinct mechanisms. The results presented here provide the first direct evidence that annexin II has the capacity to bridge CMV to a phospholipid membrane and to enhance virus-membrane fusion. These observations furthermore suggest that AnV may regulate the fusogenic function of annexin II. 相似文献
49.
N-Linked glycosylation of a baculovirus-expressed recombinant glycoprotein in insect larvae and tissue culture cells 总被引:5,自引:3,他引:2
The potential of insect cell cultures and larvae infected with recombinant
baculoviruses to produce authentic recombinant glycoproteins cloned from
mammalian sources was investigated. A comparison was made of the N-linked
glycans attached to secreted alkaline phosphatase (SEAP) produced in four
species of insect larvae and their derived cell lines plus one additional
insect cell line and larvae of one additional species. These data survey
N-linked oligosaccharides produced in four families and six genera of the
order Lepidoptera. Recombinant SEAP expressed by recombinant isolates of
Autographa californica and Bombyx mori nucleopolyhedroviruses was purified
from cell culture medium, larval hemolymph or larval homogenates by
phosphate affinity chromatography. The N-linked oligosaccharides were
released with PNGase-F, labeled with 8- aminonaphthalene-1-3-6-trisulfonic
acid, fractionated by polyacrylamide gel electrophoresis, and analyzed by
fluorescence imaging. The oligosaccharide structures were confirmed with
exoglycosidase digestions. Recombinant SEAP produced in cell lines of
Lymantria dispar (IPLB-LdEIta), Heliothis virescens (IPLB-HvT1), and Bombyx
mori (BmN) and larvae of Spodoptera frugiperda, Trichoplusia ni ,
H.virescens , B.mori , and Danaus plexippus contained oligosaccharides that
were structurally identical to the 10 oligosaccharides attached to SEAP
produced in T.ni cell lines. The oligosaccharide structures were all
mannose-terminated. Structures containing two or three mannose residues,
with and without core fucosylation, constituted more than 75% of the
oligosaccharides from the cell culture and larval samples.
相似文献
50.
Unusual pattern of bacterial ice nucleation gene evolution 总被引:5,自引:0,他引:5
Edwards AR; Van den Bussche RA; Wichman HA; Orser CS 《Molecular biology and evolution》1994,11(6):911-920
Bacterial ice nucleation activity (INA+ phenotype) can be traced to the
product of a single gene, ina. A remarkably sparse distribution of this
phenotype within three bacterial genera indicates that the ina gene may
have followed an unusual evolutionary path. Southern blot analyses, coupled
with assays for ice-nucleating ability, revealed that within four bacterial
species an ina gene is present in some strains but absent from others.
Results of hybridization experiments using DNA fragments that flank the ina
gene suggested that the genotypic dimorphism of ina may be anomalous. A
phylogenetic analysis of 16S ribosomal RNA gene sequences from a total of
14 ina+ and ina- bacterial strains indicated that the ina+ bacteria are not
monophyletic but instead phylogenetically interspersed among ina- bacteria.
The relationships of ina+ bacteria inferred from ina sequence did not
coincide with those inferred from the 16S data. These results suggest the
possibility of horizontal transfer in the evolution of bacterial ina genes.
相似文献