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排序方式: 共有473条查询结果,搜索用时 15 毫秒
41.
Nete Bernbom Yoke Yin Ng Stefan M?ller Olsen Lone Gram 《Applied and environmental microbiology》2013,79(22):6885-6893
The purpose of the present study was to determine if the monoculture antifouling effect of several pigmented pseudoalteromonads was retained in in vitro mesocosm systems using natural coastal seawater and when the bacteria were embedded in paint used on surfaces submerged in coastal waters. Pseudoalteromonas piscicida survived on a steel surface and retained antifouling activity for at least 53 days in sterile seawater, whereas P. tunicata survived and had antifouling activity for only 1 week. However, during the first week, all Pseudoalteromonas strains facilitated rather than prevented bacterial attachment when used to coat stainless steel surfaces and submerged in mesocosms with natural seawater. The bacterial density on surfaces coated with sterile growth medium was 105 cells/cm2 after 7 days, whereas counts on surfaces precoated with Pseudoalteromonas were significantly higher, at 106 to 108 cells/cm2. However, after 53 days, seven of eight Pseudoalteromonas strains had reduced total bacterial adhesion compared to the control. P. piscicida, P. antarctica, and P. ulvae remained on the surface, at levels similar to those in the initial coating, whereas P. tunicata could not be detected. Larger fouling organisms were observed on all plates precoated with Pseudoalteromonas; however, plates coated only with sterile growth medium were dominated by a bacterial biofilm. Suspensions of a P. piscicida strain and a P. tunicata strain were incorporated into ship paints (Hempasil x3 87500 and Hempasil 77500) used on plates that were placed at the Hempel A/S test site in Jyllinge Harbor. For the first 4 months, no differences were observed between control plates and treated plates, but after 5 to 6 months, the control plates were more fouled than the plates with pseudoalteromonad-based paint. Our study demonstrates that no single laboratory assay can predict antifouling effects and that a combination of laboratory and real-life methods must be used to determine the potential antifouling capability of new agents or organisms. 相似文献
42.
Morten Poulsen Michael V.W. Kofoed Lone H. Larsen Andreas Schramm Peter Stief 《Systematic and applied microbiology》2014
Benthic invertebrates affect microbial processes and communities in freshwater sediment by enhancing sediment-water solute fluxes and by grazing on bacteria. Using microcosms, the effects of larvae of the widespread midge Chironomus plumosus on the efflux of denitrification products (N2O and N2 + N2O) and the diversity and abundance of nitrate- and nitrous-oxide-reducing bacteria were investigated. Additionally, the diversity of actively nitrate- and nitrous-oxide-reducing bacteria was analyzed in the larval gut. The presence of larvae increased the total effluxes of N2O and N2 + N2O up to 8.6- and 4.2-fold, respectively, which was mostly due to stimulation of sedimentary denitrification; incomplete denitrification in the guts accounted for up to 20% of the N2O efflux. Phylotype richness of the nitrate reductase gene narG was significantly higher in sediment with than without larvae. In the gut, 47 narG phylotypes were found expressed, which may contribute to higher phylotype richness in colonized sediment. In contrast, phylotype richness of the nitrous oxide reductase gene nosZ was unaffected by the presence of larvae and very few nosZ phylotypes were expressed in the gut. Gene abundance of neither narG, nor nosZ was different in sediments with and without larvae. Hence, C. plumosus increases activity and diversity, but not overall abundance of nitrate-reducing bacteria, probably by providing additional ecological niches in its burrow and gut. 相似文献
43.
Lone Gram Jette Melchiorsen Jesper Bartholin Bruhn 《Marine biotechnology (New York, N.Y.)》2010,12(4):439-451
The purpose of the present study was to isolate marine culturable bacteria with antibacterial activity and hence a potential
biotechnological use. Seawater samples (244) and 309 swab samples from biotic or abiotic surfaces were collected on a global
Danish marine research expedition (Galathea 3). Total cell counts at the seawater surface were 5 × 105 to 106 cells/ml, of which 0.1–0.2% were culturable on dilute marine agar (20°C). Three percent of the colonies cultured from seawater
inhibited Vibrio anguillarum, whereas a significantly higher proportion (13%) of colonies from inert or biotic surfaces was inhibitory. It was not possible
to relate a specific kind of eukaryotic surface or a specific geographic location to a general high occurrence of antagonistic
bacteria. Five hundred and nineteen strains representing all samples and geographic locations were identified on the basis
of partial 16S rRNA gene sequence homology and belonged to three major groups: Vibrionaceae (309 strains), Pseudoalteromonas spp. (128 strains), and the Roseobacter clade (29 strains). Of the latter, 25 strains were identified as Ruegeria mobilis or pelagia. When re-testing against V. anguillarum, only 409 (79%) retained some level of inhibitory activity. Many strains, especially Pseudoalteromonas spp. and Ruegeria spp., also inhibited Staphylococcus aureus. The most pronounced antibacterial strains were pigmented Pseudoalteromonas strains and Ruegeria spp. The inhibitory, pigmented Pseudoalteromonas were predominantly isolated in warmer waters from swabs of live or inert surfaces. Ruegeria strains were isolated from all ocean areas except for Arctic and Antarctic waters and inhibitory activity caused by production
of tropodithietic acid. 相似文献
44.
Henrik Lütken James R. Lloyd Mikkel A. Glaring Lone Baunsgaard Kristian Holst Laursen Anna Haldrup Jens Kossmann Andreas Blennow 《Planta》2010,232(5):1127-1139
Two glucanotransferases, disproportionating enzyme 1 (StDPE1) and disproportionating enzyme 2 (StDPE2), were repressed using
RNA interference technology in potato, leading to plants repressed in either isoform individually, or both simultaneously.
This is the first detailed report of their combined repression. Plants lacking StDPE1 accumulated slightly more starch in
their leaves than control plants and high levels of maltotriose, while those lacking StDPE2 contained maltose and large amounts
of starch. Plants repressed in both isoforms accumulated similar amounts of starch to those lacking StDPE2. In addition, they
contained a range of malto-oligosaccharides from maltose to maltoheptaose. Plants repressed in both isoforms had chlorotic
leaves and did not grow as well as either the controls or lines where only one of the isoforms was repressed. Examination
of photosynthetic parameters suggested that this was most likely due to a decrease in carbon assimilation. The subcellular
localisation of StDPE2 was re-addressed in parallel with DPE2 from Arabidopsis thaliana by transient expression of yellow fluorescent protein fusions in tobacco. No translocation to the chloroplasts was observed
for any of the fusion proteins, supporting a cytosolic role of the StDPE2 enzyme in leaf starch metabolism, as has been observed
for Arabidopsis DPE2. It is concluded that StDPE1 and StDPE2 have individual essential roles in starch metabolism in potato and consequently
repression of these disables regulation of leaf malto-oligosaccharides, starch content and photosynthetic activity and thereby
plant growth possibly by a negative feedback mechanism. 相似文献
45.
46.
Shabir A. Lone A.S. Yadav A. Bajaj Ajit K. Sharma Yogesh Badkhane D.K. Raghuwanshi 《Archives Of Phytopathology And Plant Protection》2013,46(11):1327-1340
Over-utilisation and continuous depletion of medicinal plants have affected their supply and loss of genetic diversity. Hence the current study is based on conservation strategies for threatened medicinal plants with special reference to Barleria prionitis L. using in vitro and ex vitro propagation techniques. We have developed here a protocol for plant regeneration of Barleria prionitis L. We have also developed an efficient system of vegetative propagation of Barleria prionitis L. through stem cuttings using revive rooting hormones. These studies can be useful for conservation strategies of this important medicinal plant. 相似文献
47.
Karin A. W. Wadt Lauren G. Aoude Lotte Krogh Lone Sunde Anders Bojesen Karen Gr?nskov Nine Wartacz Jakob Ek Morten Tolstrup-Andersen Mette Klarskov-Andersen ?ke Borg Steffen Heegaard Jens F. Kiilgaard Thomas V. O. Hansen Kerenaftali Klein G?ran J?nsson Krzysztof T. Drzewiecki Morten Dun? Nicholas K. Hayward Anne-Marie Gerdes 《PloS one》2015,10(3)
Both environmental and host factors influence risk of cutaneous
melanoma (CM), and worldwide, the incidence varies depending on constitutional determinants of skin type and pigmentation, latitude, and patterns of sun exposure. We performed genetic analysis of CDKN2A, CDK4, BAP1, MC1R, and MITFp.E318K in Danish high-risk melanoma cases and found CDKN2A germline mutations in 11.3% of CM families with three or more affected individuals, including four previously undescribed mutations. Rare mutations were also seen in CDK4 and BAP1, while MC1R variants were common, occurring at more than twice the frequency compared to Danish controls. The MITF p.E318K variant similarly occurred at an approximately three-fold higher frequency in melanoma cases than controls. To conclude, we propose that mutation screening of CDKN2A and CDK4 in Denmark should predominantly be performed in families with at least 3 cases of CM. In addition, we recommend that testing of BAP1 should not be conducted routinely in CM families but should be reserved for families with CM and uveal melanoma, or mesothelioma. 相似文献
48.
Sharma VK Lone SR Mathew D Goel A Chandrashekaran MK 《Chronobiology international》2004,21(2):297-308
The locomotor activity rhythm of the media workers of the ant species Camponotus compressus was monitored under constant conditions of the laboratory to understand the role of circadian clocks in social organization. The locomotor activity rhythm of most ants entrained to a 24 h light/dark (12:12 h; LD) cycle and free-ran under constant darkness (DD) with circadian periodicities. Under entrained conditions about 75% of media workers displayed nocturnal activity patterns, and the rest showed diurnal activity patterns. In free-running conditions these ants displayed three types of activity patterns (turn-around). The free-running period (τ) of the locomotor activity rhythm of some ants (10 out of 21) showed period lengthening, and those of a few (6 out of 21) showed period shortening, whereas the locomotor activity rhythm of the rest of the ants (5 out of 21) underwent large phase shifts. Interestingly, the pre-turn-around τ of those ants that showed nocturnal activity patterns during earlier LD entrainment was shorter than 24 h, which became greater than 24 h after 6-9 days of free-run in DD. On the other hand, the pre-turn-around τ of those ants, which exhibited diurnal patterns during earlier LD entrainment, was greater than 24 h, which became shorter than 24 h after 6-9 days of free-run in DD. The patterns of activity under LD cycles and the turn-around of activity patterns in DD regime suggest that these ants are shift workers in their respective colonies, and they probably use their circadian clocks for this purpose. Circadian plasticity thus appears to be a general strategy of the media workers of the ant species C. compressus to cope with the challenges arising due to their roles in the colony constantly exposed to a fluctuating environment. 相似文献
49.
Sortilin and SorLA are members of the Vps10p domain receptor family, the Sortilins, which comprise five type I transmembrane
receptors differentially expressed in neuronal tissues of the central and peripheral nervous system. Since the identification
of sortilin in 1997, members of this receptor family are recognized as sorting receptors primarily in the trans-Golgi network,
interacting with a wide range of ligands comprising other transmembrane receptors as well as soluble proteins from neurotrophic
factors to enzymes targeted for lysosomes. Specifically, the involvement of sortilin in neutrophin signaling in healthy and
injured neurons is increasingly recognized, as well as the impact of SorLA on the cellular processing of amyloid precursor
protein, an important component in Alzheimer’s disease. The current understanding of these issues as well as the recent recognition
of a molecular link between sortilin and frontotemporal dementia is addressed in this present review. 相似文献
50.
Kirsten Christoffersen Bo Riemann Lone R. Hansen Annette Klysner Helle B. Sørensen 《Microbial ecology》1990,20(1):253-272
Plankton community structure and major pools and fluxes of carbon were observed before and after culmination of a bloom of cyanobacteria in eutrophic Frederiksborg Slotssø, Denmark. Biomass changes of heterotrophic nanoflagellates, ciliates, microzooplankton (50 to 140 μm), and macrozooplankton (larger than 140 μm) were compared to phytoplankton and bacterial production as well as micro- and macrozooplankton ingestion rates of phytoplankton and bacteria. The carbon budget was used as a means to examine causal relationships in the plankton community. Phytoplankton biomass decreased and algae smaller than 20 μm replacedAphanizomenon after the culmination of cyanobacteria. Bacterial net production peaked shortly after the culmination of the bloom (510 μg C liter?1 d?1 and decreased thereafter to a level of approximately 124 μg C liter?1 d?1. Phytoplankton extracellular release of organic carbon accounted for only 4–9% of bacterial carbon demand. Cyclopoid copepods and small-sized cladocerans started to grow after the culmination, but food limitation probably controlled the biomass after the collapse of the bloom. Grazing of micro- and macrozooplankton were estimated from in situ experiments using labeled bacteria and algae. Macrozooplankton grazed 22% of bacterial net production during the bloom and 86% after the bloom, while microzooplankton (nauplii, rotifers and ciliates larger than 50 μm) ingested low amounts of bacteria and removed 10–16% of bacterial carbon. Both macro-and microzooplankton grazed algae smaller than 20 μm, although they did not control algal biomass. From calculated clearance rates it was found that heterotrophic nanoflagellates (40–440 ml?1) grazed 3–4% of the bacterial production, while ciliates smaller than 50 μm removed 19–39% of bacterial production, supporting the idea that ciliates are an important link between bacteria and higher trophic levels. During and after the bloom ofAphanizomenon, major fluxes of carbon between bacteria, ciliates and crustaceans were observed, and heterotrophic nanoflagellates played a minor role in the pelagic food web. 相似文献