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Long-term Regulation (long-term + regulation)
Selected AbstractsLong-term regulation in calretinin staining in the rat inferior colliculus after unilateral auditory cortical ablationTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 20 2010Cheryl Clarkson Abstract In this study we analyzed the effects in the inferior colliculus of a unilateral ablation of the auditory cortex in rats. Variations in both calretinin immunoreactivity and protein levels determined by Western blot suggest that such lesions induce changes in the regulation of this calcium-binding protein. Stereological counts of calretinin-immunoreactive neurons in the inferior colliculus 15, 90, and 180 days after the lesion showed a progressive increase in the number of immunoreactive neurons, with a parallel increase in the intensity of staining. Two hundred forty days after the cortical lesion, both the number of immunoreactive neurons and the staining intensity had returned to control values. The effects of the cortical lesion on calretinin regulation are more intense in those inferior colliculus subdivisions more densely innervated by the corticocollicular projection. This finding, along with the time course of calretinin regulation suggests that degeneration of the descending projection is linked to calretinin regulation in the inferior colliculus. We hypothesize, based on the role of calretinin, that the observed increase in immunoreactivity levels seen in the inferior colliculus after lesioning of the auditory cortex may be related to altered excitability in deafferented neurons. Our finding, may reflect adaptive mechanisms to changes in calcium influx and excitability in inferior colliculus neurons induced by lesions of the descending projection from the cortex to the inferior colliculus. J. Comp. Neurol. 518:4261,4276, 2010. © 2010 Wiley-Liss, Inc. [source] Modelling the efficacy of entomopathogenic nematodes in the regulation of invertebrate pests in glasshouse cropsJOURNAL OF APPLIED ECOLOGY, Issue 2 2000A. Fenton Summary 1. ,Entomopathogenic nematodes belonging to the families Heterorhabditidae and Steinernematidae are lethal obligate parasites of a wide range of invertebrate species. These nematodes exhibit many characteristics that make them ideal candidates as biological control agents of insect pests (rapid host death, high reproductive rates, easily mass-reared in vitro, easy application techniques). 2. ,However, at present, the number of pest species to which these nematodes are applied successfully is small. Clearly, there is a need to develop existing knowledge of the nematode into a more complete understanding of the nematode,pest system as a whole. 3. ,To consider the potential of entomopathogenic nematodes as biological control agents, we adopted a generalized analytical modelling approach and, using realistic parameter estimates, determined the conditions under which these nematodes can regulate a pest population. 4. ,Stability analyses suggested that entomopathogenic nematodes may not be capable of regulating a host population to a stable equilibrium. Long-term persistence of the host and nematode population is unlikely, due to the highly destabilizing effects of the parasite,host relationship. As such, these nematodes may be better suited to short-term control through inundative application techniques rather than long-term regulation. 5. ,This preliminary generalized model highlights areas where further work is needed. This includes estimation of the probability of nematode infection in the field, the effect of host size on the transmission cycle and the influence of spatial heterogeneity on stability. [source] Reversal of the silencing of tetracycline-controlled genes requires the coordinate action of distinctly acting transcription factorsTHE JOURNAL OF GENE MEDICINE, Issue 1 2005Renata Pankiewicz Abstract Background Regulation of genes transferred to eukaryotic organisms is often limited by the lack of consistent expression levels in all transduced cells, which may result in part from epigenetic gene silencing effects. This reduces the efficacy of ligand-controlled gene switches designed for somatic gene transfers such as gene therapy. Methods A doxycycline-controlled transgene was stably introduced in human cells, and clones were screened for epigenetic silencing of the transgene. Various regulatory proteins were targeted to the silent transgene, to identify those that would mediate regulation by doxycycline. Results A doxycycline-controlled minimal promoter was found to be prone to gene silencing, which prevents activation by a fusion of the bacterial TetR DNA-binding domain with the VP16 activator. DNA modification studies indicated that the silenced transgene adopts a poorly accessible chromatin structure. Several cellular transcriptional activators were found to restore an accessible DNA structure when targeted to the silent transgene, and they cooperated with Tet-VP16 to mediate regulation by doxycycline. Conclusions Reversal of the silencing of a tetracycline-regulated minimal promoter requires a chromatin-remodeling activity for subsequent promoter activation by the Tet-VP16 fusion protein. Thus, distinct regulatory elements may be combined to obtain long-term regulation and persistent expression of exogenous genes in eukaryotic cells. Copyright © 2004 John Wiley & Sons, Ltd. [source] Neutropenia dynamics in a case of T-LGL lymphoproliferation illustrate rapid turnover of granulocyte progenitorsCELL PROLIFERATION, Issue 3 2010C. M. Wolfrom Objectives:, To elucidate the natural history of T-cell large granular lymphocyte (T-LGL) lymphoproliferation, we followed changes in associated fluctuating neutropenia for 3 years in an untreated patient presenting with the disease. Materials and methods:, We report a nonlinear mathematical analysis of irregular neutrophil fluctuation, using iterative data maps, to detect long-term regulation of the neutrophil population. Results:, This geometric analysis indicated that variations of this sequence of neutrophil counts followed bounded deterministic dynamics around a fixed low level equilibrium, a situation similar to that previously observed for cultured mouse early bone marrow progenitor cells. Conclusion:, These findings illustrate how the deleterious effect of T-LGL on neutrophils is balanced, over periods of years, by pulses of compensatory neutrophil production, potentially accounting for the commonly observed prolonged indolent course of the disease. [source] | ||||||||||