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Regeneration Ability (regeneration + ability)
Selected AbstractsDistribution of aquatic vascular plants in lowland rivers: separating the effects of local environmental conditions, longitudinal connectivity and river basin isolationFRESHWATER BIOLOGY, Issue 3 2005BENOÎT O. L. DEMARS Summary 1. Changes in species distributions along rivers have rarely been observed independently of changes in environmental conditions and meaningful comparison between different catchments is made difficult by the limited geographical distribution of species. This study presents a new approach to quantify the effect of the spatial structure of lowland river networks on aquatic plant distribution and to explore the potential underlying processes using species life-history characteristics. 2. Twenty-five species of aquatic vascular plants recorded in 62 sites across five calcareous river basins were used to investigate (i) the temporal turnover of plant species, (ii) the habitat utilisation of species, (iii) the trade-offs between different plant life-history characteristics and (iv) the relationship between species life-history characteristics and habitat utilisation. 3. The annual plant turnover within a 3-year period was, although significant, extremely low. It suggests that results from spatial surveys conducted over 3 years should not be undermined by temporal changes. 4. Spatial connectivity along and between rivers was more important than in-channel physical characteristics in shaping species assemblages. Neither chemical factors (ammonium, phosphate) nor extrinsic biotic competitors (filamentous green algae) significantly influenced plant distribution. 5. The most common combinations of life-history characteristics were neither related to environmental conditions nor to spatial isolation. Instead, they could reflect natural selection processes associated with larger scales than those considered in this study. 6. Plant distribution was most strongly related to the dispersal and regeneration abilities of the plants, supporting the hypotheses relating to longitudinal connectivity. The hypothesis that different growth forms would be associated with different in-channel physical features was not verified. As expected, there were no substantial differences in plant life-history characteristics between river basins. [source] Migration of mesenchymal cell fated to blastema is necessary for fish fin regenerationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2008Yuki Nakatani Urodeles and fish have higher regeneration ability in a variety of tissues and organs than do other vertebrate species including mammals. Though many studies have aimed at identifying the cellular and molecular basis for regeneration, relatively little is known about the detailed cellular behaviors and involved molecular basis. In the present study, a small molecule inhibitor was used to analyzed the role of phosphoinositide 3-kinase (PI3K) signaling during regeneration. We showed that the inhibitor disrupted the formation of blastema including the expression of characteristic genes. The failure of blastema formation was due to the impaired migration of mesenchymal cells to the distal prospective blastema region, although it had a little affect on cell cycle activation in mesenchymal cells. Moreover, we found that the epidermal remodeling including cell proliferation, distal cell migration and Akt phosphorylation was also affected by the inhibitor, implying a possible involvement of epidermis for proper formation of blastema. From these data, we propose a model in which distinct signals that direct the cell cycle activation, mesenchymal cell migration and epidermal remodeling coordinate together to accomplish the correct blastema formation and regeneration. [source] Effects of activation of hedgehog signaling on patterning, growth, and differentiation in Xenopus froglet limb regenerationDEVELOPMENTAL DYNAMICS, Issue 8 2009Nayuta Yakushiji Abstract Regenerating limbs of urodele amphibians and Xenopus tadpole are reconstructed along proximal,distal, anterior,posterior (AP), and dorsal,ventral axes. In contrast, a regenerated limb of the Xenopus froglet does not have digits, and only a simple cartilaginous structure referred to as a "spike" is formed. This suggests that repatterning along the AP axis is absent in the froglet blastema. Previous studies have shown that Shh and its target genes are not expressed in the froglet blastema. In this study, we activated Hedgehog signaling in the froglet blastema and found that target genes of Shh were inducible in the mesenchyme of limb blastema. Furthermore, we found that activation of the signaling had effects on blastema cell proliferation and chondrogenesis and resulted in the formation of multiple cartilaginous structures. These findings indicate that activation of signaling that is absent in the froglet blastema is effective for improvement of limb regeneration ability in the Xenopus froglet. Developmental Dynamics, 2009. © 2009 Wiley-Liss, Inc. [source] Optimization of culture conditions for plant regeneration of Panicum spp. through somatic embryogenesisGRASSLAND SCIENCE, Issue 1 2010Mi-Suk Seo Abstract We developed a rapid and efficient shoot regeneration system for Panicum spp. by adjusting the regeneration medium and studying the responses of different genotypes and the influence of explant types (mature seed, immature embryo and shoot apex). We used Panicum meyerianum (Nees) and Panicum longijubatum (Stapf) which were shown to perform well, to select the optimal medium for shoot regeneration. The highest frequency of shoot regeneration was obtained on Murashige and Skoog medium supplemented with 30 g L,1 maltose and 1 mg L,1 N-phenyl-N,-[(1,2,3-thidiazol-5-yl) urea]. The callus formed green spots after 1 week of culture and showed primary green shoots after 2 weeks. In this system, the calli derived from mature seed of nine Panicum genotypes showed large variation in shoot regeneration ability: from 0 to 69.9% in the frequency of shoot formation and from 0 to 8.4 in the number of shoots per callus. Guineagrass (Panicum maximum Jacq.) showed no ability and switchgrass (Panicum virgatum L.) showed low ability to regenerate from mature seed-derived calli; however, both were able to be regenerated from immature embryos and calli derived from shoot apices. We developed an efficient protocol for high shoot regeneration of various Panicum genotypes which provides a foundation for efficient tissue culture and genetic improvement of Panicum. [source] Fire and species range in Mediterranean landscapes: an experimental comparison of seed and seedling performance among Centaurea taxaJOURNAL OF BIOGEOGRAPHY, Issue 1 2002Miquel Riba Aim Fire is a major disturbance event in Mediterranean landscapes. In this paper, we experimentally assess the effects of fire and post-fire conditions on seed germination and establishment of twenty Centaurea taxa to test whether differences among taxa are associated with range size. Methods The taxa (species and subspecies) considered were classified as rare and widespread according to their `area of occupancy' in the Mediterranean coast of Spain and France. In a first experiment, we analyse the effects of heat-shock (particularly, room temperature, 70 and 110 °C) on percentage germination and speed of germination (T50). In a second experiment, we analyse the effects of post-fire conditions (shading and soil type: burned/unburned) on seed germination and establishment ability. Results Temperatures over 120 °C resulted in 100% mortality, while temperatures in the range of those expected to be found in the first centimetres down the soil profile during a wildfire (70,110 °C) had no effect on seed germination. Differences in germination percentage and T50 among taxa were not related to rarity. In the post-fire conditions experiment, decreased radiation (shading) increased percentage germination and T50 in most taxa, while burned soil decreased germination in some of them. The effects of post-fire conditions on seedling growth (number of leaves and leaf size) were also different among taxa, but such differences were not related to rarity. However, rarity was associated with low establishment ability, as rare taxa tended to show smaller seedling size and higher mortality rates under the whole range of conditions tested. Main conclusions The results obtained indicate that fire has a negative effect upon the survival of populations in all the taxa considered, and that rare-common differences in germination and seedling establishment are not directly related to disturbance by fire. As far as interspecific differences in range size are concerned, other factors, either alone or in combination with a low regeneration ability after fire, need to be explored further. [source] Effect of parental genotypes and colchicine treatment on the androgenic response of wheat F1 hybridsPLANT BREEDING, Issue 4 2003I. Zamani Abstract The effect of the parental genotypes and colchicine treatment on the androgenic response of wheat (Triticum aestivum L.) F1 hybrids was studied. For this, anthers from three F1 hybrids and their parents were cultured on W14 initiation medium and W14 supplemented with 0.03% colchicine. The number of responding anthers, microspore-derived structures/100 anthers, green plants/embryos cultured, green plants/100 anthers and albino plants/100 anthers were recorded. It was observed that embryo formation and plant regeneration ability were genetically controlled and genotype dependent. In both treatments the variety Kavkaz had a significantly higher percentage of responding anthers, microspore-derived structures and green plants/100 anthers than the other genotypes. On the other hand, the variety Myconos also demonstrated high microspore-derived structure production and green plant regeneration when treated with colchicine. The good response observed in these two varieties indicates the importance of colchicine treatment only for certain genotypes. Green plant production capacity of the hybrids was intermediate to that of the parental varieties. As one parent with a high or even an intermediate response to anther culture could lead to the production of sufficient (for breeding purposes) green plants from the F1 hybrids, it was concluded that screening the inbred lines for the response to anther culture with and without colchicine treatment could contribute to utilization of breeding material with a low response to anther culture via the proper hybrid combinations. [source] Regeneration of fertile doubled haploid plants from colchicine-supplemented media in wheat anther culturePLANT BREEDING, Issue 6 2000I. Zamani Abstract The effect of colchicine added to induction medium for the production of fertile doubled haploid plants after in-vitro anther culture was studied in wheat, Triticum aestivum L. For this, one winter and two spring wheat varieties were used. Anther cultures of the three genotypes were treated with 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine had no significant effect on anther response and embryoid production of the genotypes examined. However, in the winter wheat genotype ,Mv Szigma', colchicine caused a significant reduction in microspore-derived structures. A significant decrease was also observed in plant regeneration ability of two genotypes (,Vergina' and ,Acheloos') after colchicine treatment. In addition, a significant reduction of the albinos produced was observed in all genotypes after olchicine treatment. In contrast, the regenerants obtained from the colchicine-supplemented induction media produced significantly higher percentages of fertile plants in all genotypes. However, the level of fertility, was significantly different among the fertile plants obtained. This, together with the observation that in the case of the winter wheat variety the colchicine treatment resulted in 100% completely fertile plants with a high seed-setting ability indicate that there is space for further improvement of the method when it is applied to spring cultivars. Finally, the increased number of seeds per 100 plated anthers obtained from all three genotypes after colchicine treatment, clearly demonstrates that the addition of colchicine to induction medium was superior to the conventional anther culture method and it could therefore be introduced into wheat breeding programmes. [source] Influence of antibiotic cefotaxime on somatic embryogenesis and plant regeneration in indica riceBIOTECHNOLOGY JOURNAL, Issue 10 2006Deepinder Grewal Dr. Abstract An antibiotic, cefotaxime (OmnataxÔ) has been found to promote somatic embryogenesis and subsequent plant regeneration in vitro in indica-type basmati rice cultures. Response was highly genotype specific. The number, mass and morphology of the calli formed on the scutellar tissues were dependent on the growth medium (with or without cefotaxime). The embryogenic nature of nodular calli was confirmed through histological analysis and their plant regeneration ability. The calli of variety Pusa basmati 1 grown on medium supplemented with cefotaxime (100 mg/L) exhibited up to 70.5% plant regeneration as compared to control (51.51%). Plants regenerated from emryogenic calli were phenotypically normal and identical to seed-derived plants and exhibited normal fertility. A limited humidity and an optimal aeration of the culture tubes further enhanced the frequency of somatic embryogenesis and plant regeneration. [source] | ||||||||||