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1.
A series of oligonucleotides containing biotin-11-dUMP at various positions were synthesized and compared in quantitative, colorimetric hybridization-detection studies. A deoxyuridine phosphoramidite containing a protected allylamino sidearm was synthesized and used in standard, automated synthesis cycles to prepare oligonucleotides with allylamino residues at various positions within a standard 17-base sequence. Biotin substituents were subsequently attached to the allylamino sidearms by reaction with N-biotinyl-6-aminocaproic acid N-hydroxysuccinimide ester. These oligomers were hybridized to target DNA immobilized on microtiter wells (ELISA plates), and were detected with a streptavidin-biotinylated horseradish peroxidase complex using hydrogen peroxide as substrate and o-phenylenediamine as chromogen. We found that the sensitivity of detection of target DNA by biotin-labeled oligonucleotide probes was strongly dependent upon the position of the biotin label. Oligonucleotides containing biotin labels near or off the ends of the hybridizing sequence were more effective probes than oligonucleotides containing internal biotin labels. An additive effect of increasing numbers of biotin-dUMP residues was found for some labeling configurations. 相似文献
2.
The activity of a 7.3S-8.3S Drosophila DNA polymerase was characterized in detail using poly dA.p(dT)[unk] and poly rA.p(dT)[unk]. With poly dA.p(dT)[unk], Mg(2+) ion was the preferred divalent cation, and enzyme activity was inhibited by K(+) ion and by spermidine. With poly rA.p(dT)[unk], Mn(2+) ion was the preferred divalent cation and enzyme activity was stimulated by K(+) ion and by spermidine. The dependence of enzyme activity on the concentration of primer-template and on the ratio of primer to template was the same in both reactions. The two enzyme activities were identically inhibited by N-ethylmaleimide. Poly dA was replicated extensively and poly rA was replicated partially. The activation energy for poly dA replication was twice that for poly rA replication. Enzyme activity with poly dA.p(dT)[unk] was more stable to thermal inactivation than was enzyme activity with poly rA.p(dT)[unk]. These studies suggest that the same enzyme responds to both the deoxy- and the ribohomopolymer template but that the mechanisms of replication may be different. 相似文献
3.
Jaap H. Waterborg Hermanus F. W. van Brakel Charles M. A. Kuyper 《Archives of microbiology》1979,122(2):195-200
During the sclerotization of microplasmodia of Physarum polycephalum in non-nutrient salt medium or in salt medium supplemented by glucose, RNA or nucleotides a 6-fold increase in the specific activity of an alkaline endonuclease was found within 6 h after the induction. The increase was based on de novo synthesis of the enzyme and it was strongly correlated to the sharp drop in the level of cellular RNA in the first hours of the process of scerotization. The induction in exhausted growth medium or in salt medium supplemented by protein or mannitol showed a gradual 2-3-fold increase of the endonuclease in 30 h, parallel to the gradual decrease of the RNA. No changes in the specific activity of the endonuclease were found during logarithmic growth or under conditions of starvation without the induction to sclerotization.The alkaline, polyA-specific endonuclease could possibly regulate the turnover of RNA. 相似文献
4.
Faisan Joseph P. Luhan Ma. Rovilla J. Sibonga Rema C. Mateo Jonalyn P. Ferriols Victor Marco Emmanuel N. Brakel Janina Ward Georgia M. Ross Stuart Bass David Stentiford Grant D. Brodie Juliet Hurtado Anicia Q. 《Journal of applied phycology》2021,33(4):2391-2405
Journal of Applied Phycology - Farmed eucheumatoids are the top aquaculture commodity in the Philippines, contributing more than 60% of total national aquaculture production by volume. Despite... 相似文献
5.
A redundant role of the CD3 gamma-immunoreceptor tyrosine-based activation motif in mature T cell function 总被引:1,自引:0,他引:1
Haks MC Cordaro TA van den Brakel JH Haanen JB de Vries EF Borst J Krimpenfort P Kruisbeek AM 《Journal of immunology (Baltimore, Md. : 1950)》2001,166(4):2576-2588
At least four different CD3 polypeptide chains are contained within the mature TCR complex, each encompassing one (CD3gamma, CD3delta, and CD3epsilon) or three (CD3zeta) immunoreceptor tyrosine-based activation motifs (ITAMs) within their cytoplasmic domains. Why so many ITAMs are required is unresolved: it has been speculated that the different ITAMs function in signal specification, but they may also serve in signal amplification. Because the CD3zeta chains do not contribute unique signaling functions to the TCR, and because the ITAMs of the CD3-gammadeltaepsilon module alone can endow the TCR with normal signaling capacity, it thus becomes important to examine how the CD3gamma-, delta-, and epsilon-ITAMs regulate TCR signaling. We here report on the role of the CD3gamma chain and the CD3gamma-ITAM in peripheral T cell activation and differentiation to effector function. All T cell responses were reduced or abrogated in T cells derived from CD3gamma null-mutant mice, probably because of decreased expression levels of the mature TCR complex lacking CD3gamma. Consistent with this explanation, T cell responses proceed undisturbed in the absence of a functional CD3gamma-ITAM. Loss of integrity of the CD3gamma-ITAM only slightly impaired the regulation of expression of activation markers, suggesting a quantitative contribution of the CD3gamma-ITAM in this process. Nevertheless, the induction of an in vivo T cell response in influenza A virus-infected CD3gamma-ITAM-deficient mice proceeds normally. Therefore, if ITAMs can function in signal specification, it is likely that either the CD3delta and/or the CD3epsilon chains endow the TCR with qualitatively unique signaling functions. 相似文献
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7.
Louise Pierneef Anouk van Hooij Anneke Taal Raisa Rumbaut Mauricio Lisboa Nobre Wim van Brakel Annemieke Geluk 《PLoS neglected tropical diseases》2021,15(8)
BackgroundLeprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients’ households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas.Methods and findingsA literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels.ConclusionsQuantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination. 相似文献
8.
Mahasweta Saha Francisco R. Barboza Paul J. Somerfield Balsam Al‐Janabi Miriam Beck Janina Brakel Maysa Ito Christian Pansch Jennifer C. Nascimento‐Schulze Stina Jakobsson Thor Florian Weinberger Yvonne Sawall 《Global Change Biology》2020,26(2):417-430
Marine heatwaves have been observed worldwide and are expected to increase in both frequency and intensity due to climate change. Such events may cause ecosystem reconfigurations arising from species range contraction or redistribution, with ecological, economic and social implications. Macrophytes such as the brown seaweed Fucus vesiculosus and the seagrass Zostera marina are foundation species in many coastal ecosystems of the temperate northern hemisphere. Hence, their response to extreme events can potentially determine the fate of associated ecosystems. Macrophyte functioning is intimately linked to the maintenance of photosynthesis, growth and reproduction, and resistance against pathogens, epibionts and grazers. We investigated morphological, physiological, pathological and chemical defence responses of western Baltic Sea F. vesiculosus and Z. marina populations to simulated near‐natural marine heatwaves. Along with (a) the control, which constituted no heatwave but natural stochastic temperature variability (0HW), two treatments were applied: (b) two late‐spring heatwaves (June, July) followed by a summer heatwave (August; 3HW) and (c) a summer heatwave only (1HW). The 3HW treatment was applied to test whether preconditioning events can modulate the potential sensitivity to the summer heatwave. Despite the variety of responses measured in both species, only Z. marina growth was impaired by the accumulative heat stress imposed by the 3HW treatment. Photosynthetic rate, however, remained high after the last heatwave indicating potential for recovery. Only epibacterial abundance was significantly affected in F. vesiculosus. Hence both macrophytes, and in particular F. vesiculosus, seem to be fairly tolerant to short‐term marine heatwaves at least at the intensities applied in this experiment (up to 5°C above mean temperature over a period of 9 days). This may partly be due to the fact that F. vesiculosus grows in a highly variable environment, and may have a high phenotypic plasticity. 相似文献
9.
Poly(A) Polymerase from Vaccinia Virus-Infected Cells II. Product and Primer Characterization 总被引:2,自引:2,他引:0
The product of the in vitro reaction of a vaccinia virus-induced poly(A) polymerase (see preceding paper) with ATP is shown to be poly(A) by nuclease resistance and by annealing with poly(U). Polyacrylamide gel electrophoresis indicates that the in vitro synthesized poly(A) is associated with large RNA which is sensitive to RNase. RNA which co-purifies with the virus-induced enzyme is similar to vaccinia virus-specific RNA with respect to size and poly(A) content. Double labeling studies indicate that the RNA which co-purifies with the enzyme becomes associated with the poly(A) synthesized in vitro. The poly(A) formed in vitro is located on the 3′-OH terminus of this RNA. During in vitro poly(A) synthesis 32P from α-[32P]ATP is transferred to nucleosides other than 2′,3′-AMP, primarily to CMP. Inclusion of poly(U) in the in vitro reactions results in an increase in the transfer of 32P to UMP. 相似文献
10.
W. Cairns S. Smith Peter G. Nicholls Loretta Das Pramila Barkataki Sujai Suneetha Lavanya Suneetha Rupendra Jadhav P. S. S. Sundar Rao Einar P. Wilder-Smith Diana N. J. Lockwood Wim H. van Brakel 《PLoS neglected tropical diseases》2009,3(8)