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101.
The biochemical mechanisms underlying thidiazuron (TDZ)-induced regeneration in plant cells have not been clearly elucidated.
Exposure of leaf explants of Echinacea purpurea to a medium containing TDZ results in undifferentiated cell proliferation and differentiated growth as mixed shoot organogenesis
and somatic embryogenesis. The current studies were undertaken to determine the potential roles of auxin, indoleamines, and
ion signaling in the dedifferentiation and redifferentiation of plant cells. E. purpurea leaf explants were found to contain auxin and the related indoleamine neurotransmitters, melatonin, and serotonin. The levels
of these endogenous indoleamines were increased by exposure to TDZ associated with the induction of regeneration. The auxin-transport
inhibitor 2,3,5-triiodobenzoic acid and auxin action inhibitor, p-chlorophenoxyisobutyric acid decreased the TDZ-induced regeneration but increased concentrations of endogenous serotonin
and melatonin. As well, inhibitors of calcium and sodium transport significantly reduced TDZ-induced morphogenesis while increasing
endogenous indoleamine content. These data indicate that TDZ-induced regeneration is the manifestation of a metabolic cascade
that includes an initial signaling event, accumulation, and transport of endogenous plant signals such as auxin and melatonin,
a system of secondary messengers, and a concurrent stress response. 相似文献
102.
Torque teno virus(TTV)is a nonenveloped virus containing a single-stranded,circular DNA genome of approximately 3.8kb.We completely synthesized the 3808 nucleotides of the TTV(SANBAN isolate)genome,which contains a hairpin structure and a GC-rich region.More than 100 overlapping oligonucleotides were chemically synthesized and assembled by polymerise chain assembly reaction(PCA),and the synthesis was completed with splicing by overlap extension(SOEing).This study establishes the methodological basis of the chemical synthesis of a viral genome for use as a live attenuated vaccine or gene therapy vector. 相似文献
103.
104.
Involvement of Matrix Metalloproteinases on the Inhibition of Cells Invasion and Migration by Emodin in Human Neuroblastoma SH-SY5Y Cells 总被引:1,自引:0,他引:1
Hsu-Feng Lu Kuang-Chi Lai Shu-Chun Hsu Hui-Ju Lin Chao-Lin Kuo Ching-Lung Liao Jai-Sing Yang Jing-Gung Chung 《Neurochemical research》2009,34(9):1575-1583
Emodin (1,3,8-trihydroxy-6-methylanthaquinone), an active component present in the root and rhizome of Rheum palmatum L. (Polygonaceae) has anti-bacterial, anti-tumor, diuretic and vasorelaxant effects. However, its mechanism of action on
the cell migration and invasion of human neuroblastoma cancer SH-SY5Y cells is not fully understood. In this study, firstly,
the effects of emodin on the percentage of viable cells were examined by using MTT assay and it was found that emodin induced
dose-and time-dependent inhibition in human neuroblastoma SH-SY5Y cells. Second, the effects of emodin on the migration and
invasion of SH-SY5Y cells were examined by using wound assay and matrigel counting and the results showed that emodin suppressed
the migration and invasion of SH-SY5Y cells. Third, we examined the effect of emodin on the levels of associated proteins
by using Western blotting and the results indicated that emodin inhibited the levels of GRB2, RhoA, HIF-1α, VEGF, FAK, iNOS,
COX2, p-p38, p-c-jun, MMP2, MMP9 and MMP7 but promoted the levels of PKC, PI3K, MEKK3 and NF-κB p65 that led to the inhibition
of migration and invasion of SH-SY5Y cells in vitro. 相似文献
105.
106.
107.
Ninety-one lakes distributed along the Tatra Mountains (most of lakes > 1 ha and 65% of lakes > 0.01 ha) were sampled and analysed for ionic and nutrient composition in September 2004 (15 years after reduction in acid deposition). Eighty-one lakes were in alpine zone and ten lakes in Norway spruce forest. The results were compared to similar lake surveys from 1994 (the beginning of water recovery from acidification) and 1984 (maximum acidification). Atmospheric deposition of SO 4 2? and inorganic N decreased 57% and 35%, respectively, in this region from the late 1980s to 2000. Lake water concentrations of SO 4 2? and NO 3 ? have decreased both by ~50% on average (to 23 and 19 μmol L?1, respectively, in 2004) since 1984. While the decrease in SO 4 2? concentrations was stable throughout 1984–2004, most of the NO 3 ? decrease occurred from 1994 to 2004. The declines in SO 4 2? and NO 3 ? concentrations depended on catchment coverage with vegetation, being most rapid for SO 4 2? in forest lakes and for NO 3 ? in rocky lakes. Concentrations of the sum of base cations (dominated by Ca2+) significantly decreased between 1984 and 2004, with the highest change in rocky lakes. Most of this decline occurred between 1994 and 2004. Acid neutralising capacity (ANC) did not change in the 1984–1994 period, but increased on average by 29 μmol L?1 between 1994 and 2004, with the highest change in rocky lakes. Over the last decade, the proportion of lakes with ANC > 150 μmol L?1 increased from 15% to 21% and that of ANC < 20 μmol L?1 decreased from 37% to 20%. The highest decline in H+ and Al concentrations occurred in the most acid lakes. On a regional basis, no significant change was observed for total phosphorus, total organic nitrogen, and dissolved organic carbon (DOC) in the 1994–2004 period. However, these parameters increased in forest lakes, which exhibited an increasing trend in DOC concentrations, inversely related (P < 0.001) to their decreasing ionic strength (30% on average in 1994–2004). 相似文献
108.
Ettinger-Epstein P Tapiolas DM Motti CA Wright AD Battershill CN de Nys R 《Marine biotechnology (New York, N.Y.)》2008,10(1):64-74
The Great Barrier Reef sponge Luffariella variabilis (Poléjaeff 1884) produces a range of potent anti-inflammatory compounds as its major metabolites. These major metabolites—manoalide
monoacetate, manoalide, luffariellin A and seco-manoalide—were monitored temporally and spatially to quantify the potential
yield from wild harvest or aquaculture. Production of the major metabolites was hardwired at the population level with little
variation in space and time over meters to tens of kilometers in the Palm Islands, Queensland, Australia. Manoalide monoacetate
(35 to 70 mg g−1 dry weight of sponge) was consistently the most abundant compound followed by manoalide (15 to 20 mg g−1 dry weight). Luffariellin A and seco-manoalide were 10 to 70 times less abundant and varied between 0 and 3 mg g−1 dry weight. On a larger spatial scale, L. variabilis from Davies Reef and Magnetic Island contained the same rank order and yields of compounds as the Palm Islands, indicating
a generality of pattern over at least 100 km. The “hardwiring” of metabolite production at the population level by L. variabilis was also reflected in the lack of any inductive effect on metabolite production. In addition, individually monitored sponges
produced fixed ratios of the major metabolites over time (years). However, these ratios varied between individuals, with some
individuals consistently producing high levels of manoalide and manoalide monoacetate, providing the potential for selection
of high-yielding stocks. 相似文献
109.
Yoshiaki Tsuda Madoka Kimura Shuri Kato Toshio Katsuki Yuzuru Mukai Yoshihiko Tsumura 《Journal of plant research》2009,122(4):367-375
The genetic resources of a particular species of flowering cherry, Cerasus jamasakura, have high conservation priority because of its cultural, ecological and economic value in Japan. Therefore, the genetic
structures of 12 natural populations of C. jamasakura were assessed using ten nuclear SSR loci. The population differentiation was relatively low (F
ST, 0.043), reflecting long-distance dispersal of seeds by animals and historical human activities. However, a neighbor-joining
tree derived from the acquired data, spatial analysis of molecular variance and STRUCTURE analysis revealed that the populations
could be divided into two groups: one located on Kyusyu Island and one on Honshu Island. Genetic diversity parameters such
as allelic richness and gene diversity were significantly lower in the Kyushu group than the Honshu group. Furthermore, STRUCTURE
analysis revealed that the two lineages were admixed in the western part of Honshu Island. Thus, although the phylogeographical
structure of the species and hybridization dynamics among related species need to be evaluated in detail using several marker
systems, the Kyusyu Island and Honshu Island populations should be considered as different conservation units, and the islands
should be regarded as distinct seed transfer zones for C. jamasakura, especially when rapid assessments are required. 相似文献
110.
Nadiah Pardede Kristensen Jacob Johansson Niclas Jonzén Henrik G. Smith 《Evolutionary ecology》2018,32(5):509-528
It is generally expected that, in environments with pronounced seasonal resource peaks, birds’ reproductive success will be maximised when nestlings’ peak food demand coincides with the timing of high food availability. However in certain birds that stay resident over winter, earlier breeding leads juveniles to join the winter flock earlier, which by the prior residence effect increases their success in breeding territory competition. This trade-off between reproduction and competition may explain why, in certain species, breeding phenology is earlier and asynchronous with the resource. This study extends a previous model of the evolution of breeding phenology in a single habitat type to a landscape with two habitat types: ‘early’ and ‘late’ resource phenology. The offspring’s natal habitat type has a carryover effect upon their competitive ability regardless of which habitat type they settle in to potentially breed. We find that, when the difference in resource phenology between habitats is small (weak carryover effect), breeding phenology in the late habitat evolves to occur earlier and more asynchronously than in the early habitat, to compensate for the competitive disadvantage to juveniles raised there. However if the difference is large (strong carryover effect), then the reproductive cost of earlier breeding outweighs the benefit of the compensation, so instead breeding phenology in the late habitat evolves to become more synchronous with the resource. Recruitment is generally asymmetric, from early to late habitat type. However if the early habitat is less frequent in the landscape or produces fewer offspring, then the asymmetry is reduced, and if there is some natal habitat-type fidelity, then recruitment can have an insular pattern, i.e. most recruits to each habitat type come from that same habitat type. We detail the different scenarios in which the different recruitment patterns are predicted, and we propose that they have implications for local adaptation. 相似文献