Summary Successful fundamental or basic research, while being stimulated by applied studies, provides the development of new technologies
for the benefit of mankind. Photoautotrophic micropropagation or micropropagation using sugar-free medium is no exception
from this generalization. The concept of photoautotrophic micropropagation is derived from research that revealed the relatively
high photosynthetic abilities of chlorophyllous cultures such as leafy explants and plantlets in vitro. To meet the ever-increasing demand for quality transplants, the scaling-up of photoautotrophic micropropagation systems,
for commercialization, has become necessary. This article reviews the recent advancement in the development and utilization
of large culture vessels for photoautotrophic micropropagation with special emphasis on the feasibility of the system for
the commercial-scale propagation. The review also includes choices for supporting material, ventilation type, planting density,
vessel volume, and vessel sterilization procedure, and problems and solutions to achieve uniform growth in a large culture
vessel. A case study of the commercial application of a photoautotrophic micropropagation system using large culture vessles,
which recently has been established in Kunming, China, is also presented in this article. 相似文献
Many inhibitory rhythmic networks produce activity in a range of frequencies. The relative phase of activity between neurons in these networks is often a determinant of the network output. This relative phase is determined by the interaction between synaptic inputs to the neurons and their intrinsic properties. We show, in a simplified network consisting of an oscillator inhibiting a follower neuron, how the interaction between synaptic depression and a transient potassium current in the follower neuron determines the activity phase of this neuron. We derive a mathematical expression to determine at what phase of the oscillation the follower neuron becomes active. This expression can be used to understand which parameters determine the phase of activity of the follower as the frequency of the oscillator is changed. We show that in the presence of synaptic depression, there can be three distinct frequency intervals, in which the phase of the follower neuron is determined by different sets of parameters. Alternatively, when the synapse is not depressing, only one set of parameters determines the phase of activity at all frequencies. 相似文献
Two interlinked quorum sensing circuits, las and rhl, which control pathogenesis of Pseudomonas aeruginosa are further modulated by numerous regulators, including VqsR (virulence and quorum sensing regulator). High-density oligonucleotide microarrays were used to compare the global expression profile of a wild-type and VqsR mutant in ABC minimal medium. The expression of a large group of metabolic genes, ECF sigma factors as well as of many quorum-sensing genes previously not assigned to VqsR-regulon was found to be affected by the disruption of vqsR. 相似文献
Like other tested wild-type strains (DTXII and IL-125-2B), exponential glucose- and/or fructose-grown cells of Saccharomyces cerevisiae BY4742 exhibit the previously described high activity of Pdr5p and Snq2p pumps (measured as export of the potentiometric fluorescent probe diS-C3(3)). Upon saccharide depletion from the medium the pump activity in these cells, which differ from other strains in having a lower membrane potential, sharply drops to a very low level similar to that found in cells grown on ethanol or glycerol. This negligible pump activity in respiring cells thus appears to have a universal character.
Addition of glucose or fructose to respiring BY4742 cells grown to low culture densities restores multidrug resistance pump activity due partly to pump synthesis in pre-existing cells and partly to the high pump activity of newly grown cells; no such pump activity boost occurs when the sugar is added to high-density cultures of ethanol-grown or post-diauxic glucose-grown cells, even if these cultures are diluted to low density by their original growth-depleted medium. A strong sugar-induced increase in pump activity is found solely if respiring cells from high-density cultures are resuspended in fresh YPD or YPE medium before sugar addition. Its absence in respiring cells suspended in growth-depleted medium reflects an as yet unidentified effect of the composition of the growth-exhausted medium (depletion of some components and/or accumulation of extracellular metabolites during yeast growth) on sugar-induced pump activity rise. 相似文献