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Control Establishment (control + establishment)
Selected AbstractsEpigenetic control of translation regulation: Alterations in histone H3 lysine 9 post-translation modifications are correlated with the expression of the translation initiation factor 2B (Eif2b5) during thermal control establishmentDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2010Tatiana Kisliouk Abstract Thermal control set point is regulated by thermosensitive neurons of the preoptic anterior hypothalamus (PO/AH) and completes its development during postnatal critical sensory period. External stimuli, like increase in environmental temperature, influence the neuronal protein repertoire and, ultimately, cell properties via activation or silencing of gene transcription, both of which are regulated by the "histone code."" Here, we demonstrated an increase in global histone H3 lysine 9 (H3K9) acetylation as well as H3K9 dimethylation in chick PO/AH during heat conditioning at the critical period of sensory development. In contrast to the global profile of H3K9 modifications, acetylation and dimethylation patterns of H3K9 at the promoter of the catalytic subunit of eukaryotic translation initiation factor 2B (Eif2b5) were opposite to each other. During heat conditioning, there was an increase in H3K9 acetylation at the Eif2b5 promoter, simultaneously with decrease in H3K9 dimethylation. These alterations coincided with Eif2b5 mRNA induction. Moreover, exposure to excessive heat during the critical period resulted in long-term effect on both H3K9 tagging at the Eif2b5 promoter and Eif2b5 mRNA expression. These data suggest a role for dynamic H3K9 post-translational modifications in global translation regulation during the thermal control establishment. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2010 [source] A role for eukaryotic translation initiation factor 2B (eIF2B) in taste memory consolidation and in thermal control establishment during the critical period for sensory developmentDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2007Sharon Tirosh Abstract All species exhibit critical periods for sensory development, yet very little is known about the molecules involved in the changes in the network wiring that underlies this process. Here the role of transcription regulation of the translation machinery was determined by evaluating the expression of eIF2B,, an essential component of translation initiation, in both taste-preference development and thermal control establishment in chicks. Analysis of the expression pattern of this gene after passive-avoidance training revealed clear induction of eIF2B, in both the mesopallium intermediomediale (IMM) and in the striatum mediale (StM). In addition, a correlation was found between the concentration of methylanthranilate (MeA), which was the malaise substrate in the passive-avoidance training procedure, the duration of memory, and the expression level of eIF2B,. Training chicks on a low concentration of MeA induced short-term memory and low expression level of eIF2B,, whereas a high concentration of MeA induced long-term memory and a high expression level of eIF2B, in both the IMM and StM. Furthermore, eIF2B, -antisense "knock-down" not only reduced the amount of eIF2B, but also attenuated taste memory formation. In order to determine whether induction of eIF2B, is a general feature of neuronal plasticity, we checked whether it was induced in other forms of neuronal plasticity, with particular attention to its role in temperature control establishment, which represents hypothalamic-related plasticity. It was established that eIF2B, -mRNA was induced in the preopotic anterior hypothalamus during heat conditioning. Taken together, these results correlate eIF2B, with sensory development. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] Rooting depth and soil moisture control Mediterranean woody seedling survival during droughtFUNCTIONAL ECOLOGY, Issue 3 2007F. M. PADILLA Summary 1Seedling survival is one of the most critical stages in a plant's life history, and is often reduced by drought and soil desiccation. It has been hypothesized that root systems accessing moist soil layers are critical for establishment, but very little is known about seedling root growth and traits in the field. 2We related seedling mortality to the presence of deep roots in a field experiment in which we monitored soil moisture, root growth and seedling survival in five Mediterranean woody species from the beginning of the growing season until the end of the drought season. 3We found strong positive relationships between survival and maximum rooting depth, as well as between survival and soil moisture. Species with roots in moist soil layers withstood prolonged drought better, whereas species with shallow roots died more frequently. In contrast, biomass allocation to roots was not related to establishment success. 4Access to moist soil horizons accounted for species-specific survival rates, whereas large root : shoot (R:S) ratios did not. The existence of soil moisture thresholds that control establishment provides insights into plant population dynamics in dry environments. [source] Why do some species in arid lands increase under grazing?AUSTRAL ECOLOGY, Issue 5 2009Mechanisms that favour increased abundance of Maireana pyramidata in overgrazed chenopod shrublands of South Australia Abstract While the abundance of some plant species decreases under high grazing intensity, others become more abundant. Release from competition by decreaser species contributes to this pattern in mesic systems, but this may not be the case in xeric systems where competition may be less intense. Here we examine three mechanisms that may be involved: (i) increased recruitment and growth because of soil changes produced by grazing, for example, increased soil nutrient availability through dung accumulation; (ii) increased recruitment favoured by the breaking up of the lichen crust; and (iii) reduced competition because of the decline of decreaser species. We used field and glasshouse experiments to determine the possible contribution of these mechanisms to the increase of the chenopod Maireana pyramidata around a watering point in a chenopod shrubland of South Australia. There was no evidence of nutrient accumulation close to the watering point, and while seedlings of M. pyramidata responded to nutrient addition, their growth was the same in soil collected from areas with different grazing intensity. While a broken lichen crust increased the emergence of both M. pyramidata and the decreaser Atriplex vesicaria, the effect was larger for the former. We found no competition between seedlings of the two species or between juveniles of A. vesicaria and seedlings of M. pyramidata in glasshouse experiments. Adult plants of both A. vesicaria and M. pyramidata produced similar growth reduction in seedlings of M. pyramidata. Furthermore, a field removal experiment failed to detect any competitive effect of A. vesicaria on M. pyramidata. Our data indicate that the disintegration of the soil crust by grazer activities can be a major factor controlling floristic changes in overgrazed rangelands. These results imply that factors that control establishment may be more important than competition in shaping shrub population dynamics in these systems. Ground surface itself can affect establishment opportunities, and this should be taken into account in management and restoration efforts in arid lands. [source] | ||||||||||