Target morphology and cell memory:a model of regenerative pattern formation

Despite the growing body of work on molecular components required for regenerative repair,we still lack a deep understanding of the ability of some animal species to regenerate their appropriate complex anatomical structure following damage.A key question is how regenerating systems know when to stop growth and remodeling-what mechanisms implement recognition of correct morphology that signals a stop condition？In this work,we review two conceptual models of pattern regeneration that implement a kind of pattern memory.In the first one,all cells communicate with each other and keep the value of the total signal received from the other cells.If a part of the pattern is amputated,the signal distribution changes.The difference fromthe original signal distribution stimulates cell proliferation and leads to pattern regeneration,in effect implementing an error minimization process that uses signaling memory to achieve pattern correction.In the second model,we consider a more complex pattern organization with different cell types.Each tissue contains a central（coordinator）cell that controls the tissue and communicates with the other central cells.Each of them keeps memory about the signals received from other central cells.The values of these signals depend on the mutual cell location,and the memory allows regeneration of the structure when it is modified.The purpose of these models is to suggest possible mechanisms of pattern regeneration operating on the basis of cell memory which are compatible with diverse molecular implementation mechanisms within specific organisms.

Impact of different regeneration patterns of old-growth Chinese fir on quantity and quality of soil organic carbon

Chinese fir is one of the largest distributions of commercial forest plantation in South China. In this study, we chose the different regeneration patterns of Chinese fir for our researches, the results showed different regeneration patterns affected both the quantity and quality of soil organic carbon. clear cutting followed by different regeneration in old-growth Chinese fir decreased the quantity of soil organic carbon both in artificial regeneration forest and natural regeneration forest, and both of them were significantly different with the old-growth Chinese fir forest （p〈0.05）. The concentrations of soil organic carbon（SOC） and particulate organic carbon（POC） in natural regeneration forest were higher than those in artificial regeneration forest, and the difference was significant in the 0-5 cm layer （p〈0.05）. Different regeneration patterns decreased forest SOC storage. Compared with the old-growth Chinese fir, SOC storage in 0-100 cm layer decreased by 7.09% and 13.27% in natural regeneration forest and artificial regeneration forest respectively, and the differences were both significant （p〈0.05）. In addition, SOC storage in 0-100 cm layer of natural regeneration forest was 7.13% higher than that in artificial regeneration forest.

Control of In Vitro Regeneration of Individual Reproductive and Vegetative Organs in Dracaena fragrans cv. massangeana Hort. Regularities of the Direct Regenerationof Individual Organs In Vitro

Various individual organs (tepal, flower bud, inflorescence branch, inflorescence, adult vegetative bud and juvenile vegetative bud) were directly regenerated respectively by callus in Dracaena fragrans cv. massangeana Hort. During the regeneration of these individual organs some regularity phenomena were observed. Firstly, the kind range of the individual organs, which are directly regenerated in vitro, is in close relationship to the differentiated stages of the organs used for explant excision during plant ontogeny. The explants excised from the epigeous organ that is differentiated at some stage (stage A) during plant ontogeny must be able to separately regenerate all of those individual epigeous organs: ones differentiated slightly later than the stage A, ones differentiated at the stage A and all ones differentiated earlier than the stage A. Secondly, within this range which kind of organ is regenerated depends on the exogenous auxin concentrations in medium. With the gradual increase of 2,4-D concentration from 0.005 mg/L to 0.5 mg/L, the kinds of regenerated organs will change by the order as follows: vegetative bud, inflorescence, inflorescence branch, flower bud, tepal. These regularities will be able to be used for inducing the direct regeneration of a given epigeous organ in angiosperms.

Decoding brain responses to pixelized images in the primary visual cortex: implications for visual cortical prostheses

Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex（the implant area） is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine（LSVM） as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.

The present status and future prospects of forest vegetation in part of Nanda Devi Biosphere Reserve(a World Heritage Site),India

We studied forest vegetation at Lata-Tolma- Phagti, a protected area and part of Nanda Devi Biosphere Reserve in the western Himalaya. We analyzed community composition, population structure, regeneration patterns, and projected development of future compositional patterns. We sampled ten 10 x 10 m quadrat for tree species in each of 30 forest stands. We sampled shrubs in ten 5 x 5 m quadrat, and herbs in twenty 1 x 1 m quadrat within each forest stand. We recorded 248 plant species from 8 forest communities. Broadly the demographic profiles at study sites exhibited progressive structures suggesting long term persistence of the communities/species. Density--diameter distribution revealed greater proportions of seedlings and a significant decline （P 〈 0.05） in the proportion of trees in older age/size classes. Of the 23 recorded tree species, 13.0 % showed good, 52.2 % fair, 26.1% poor and 8.7 % no regeneration. Differences in regeneration by species are indicative of future foreststructure and dynamics. Assessment of changes in structure of forest types provides baseline data for development of priorities for conservation of other representative land- scapes in the reserve as well as in the Himalaya.

Effect of exclosure on woody species diversity and population structure in comparison with adjacent open grazing land: the case of Jabi Tehnan district north western Ethiopia

Land rehabilitation by area exclosure was the fastest and moderate approach of recovering degraded sites.However,the effect of exclosure on woody species parameters in Jabitehnan district,north-western Ethiopia has not been investigated.Therefore,the current study was conducted(i)to assess and compare diversity,composition and density of woody species in exclosure and adjacent open lands,and(ii)to analyze population structure as well as regeneration status of woody species.A random sampling method was employed to select a total of 40 sample plots(50m*50m).A total of 8 parallel transect lines were used inside and outside the exclosure land in each site for consecutive(50m interval)plot establishment.Species diversity was 1.7 and 3.03 for WG,1.1 and 2.94 for GW open and exclosures,respectively.Population structure of woody species in exclosures of both sites exhibited an inverted J shape which indicates good regeneration status,while in adjacent open grazing land it exhibited partial bell shape.Generally,exclosure provides various biophysical benefits better than adjacent open grazing lands.It is recommended to protect degraded lands by exclosure via integrating appropriate species and convert their diversity into use so as to develop their potential benefits on land restoration.