Spatial and temporal patterns of seed bank dynamics in relation to gaps in an old growth tropical montane rainforest of Hainan Island, South China, were studied over two consecutive years. From June 2001 to June 2003,...Spatial and temporal patterns of seed bank dynamics in relation to gaps in an old growth tropical montane rainforest of Hainan Island, South China, were studied over two consecutive years. From June 2001 to June 2003, soil seed bank sampling blocks were taken near each of the four sides of each seed trap and immediately put into a nursery for observation of seedling emergence dynamics in four seasons （each experiment in each season）. The abundances of seedlings that emerged from seed banks showed the trend of vine functional group （VFG） 〉 shrub functional group （SFG） 〉 tree functional group （TFG） 〉 herb functional group （HFG）, but the trend in species richness of seedlings that emerged from the soil seed banks was TFG 〉 VFG 〉 SFG 〉 HFG. The abundances of seedlings that emerged from seed banks in the three gap zones showed no significant differences, but significant differences did exist for the species richness. The time of sampling or seasons of experiments had significant influences on both the species richness and seedling abundances. The seedling emergence processes of each experiment all revealed the unimodal patterns. Few emergences occurred 1 year after each experiment. Compared with those under closed canopies, the recruitment rates from seed to seedlings and from seedlings to saplings In gaps were higher, but the mortality rates from saplings to big trees were also higher in the gaps.展开更多
Cirrhosis is characterized as the progress of regenerative nodules surrounded by fibrous bands in response to chronic hepatic injury and causes portal hypertension and end-stage hepatic disease.Following liver injury,...Cirrhosis is characterized as the progress of regenerative nodules surrounded by fibrous bands in response to chronic hepatic injury and causes portal hypertension and end-stage hepatic disease.Following liver injury,liver progenitor cells(LPCs)can be activated and differentiate into hepatocytes in order to awaken liver regeneration and reach homeosta-sis.Recent research has uncovered some new sources of LPCs.Here,we update the mecha-nisms of LPCs-mediated liver regeneration in cirrhosis by introducing the origin of LPCs and LPCs’niche with a discussion of the influence of LPC-related cells.This article analyzes the mechanism of regeneration and activation of LPCs in cirrhosis in recent years aiming to provide help for clinical application.展开更多
The adult lung,a workhorse for gas exchange,is continually subjected to a barrage of assaults from the inhaled particles and pathogens.Hence,homeostatic maintenance is of paramount importance.Epithelial stem cells int...The adult lung,a workhorse for gas exchange,is continually subjected to a barrage of assaults from the inhaled particles and pathogens.Hence,homeostatic maintenance is of paramount importance.Epithelial stem cells interact with their particular niche in the adult lung to orchestrate both natural tissue rejuvenation and robust post-injury regeneration.Advances in single-cell sequencing,lineage tracing,and living tissue imaging have deepened our understanding about stem cell heterogeneities,transition states,and specific cell lineage markers.In this review,we provided an overview of the known stem/progenitor cells and their subpopulations in different regions of the adult lung,and explored the regulatory networks in stem cells and their respective niche which collectively coordinated stem cell quiescence and regeneration states.We finally discussed relationships between dysregulated stem cell function and lung disease.展开更多
Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest.It was thus essential to assess regeneration before designing optimizing st...Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest.It was thus essential to assess regeneration before designing optimizing strategies.To this end,we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots(20×25 m)on the southern aspects where the Zawita natural forest is still present.In total,1540 regenerating P.brutia were recorded,854 seedlings,597 saplings,and 89 trees.Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees.Regeneration requirements differed between seedlings and saplings.The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction.The density of saplings only showed a positive significant correlation with increasing slope.The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m.Overall,the study highlighted the requirements for seedling regeneration as a relatively open canopy cover,a light understory litter layer,and noncompacted soils.These results are a step towards designing effective management and restoration programs.展开更多
Among somatic stem cells, those residing in the intestine represent a fascinating and poorly explored research field. Particularly, somatic stem cells reside in the small intestine at the level of the crypt base, in a...Among somatic stem cells, those residing in the intestine represent a fascinating and poorly explored research field. Particularly, somatic stem cells reside in the small intestine at the level of the crypt base, in a constant balance between self-renewal and differentiation. Aim of the present review is to delve into the mechanisms that regulate the delicate equilibrium through which intestinal stem cells orchestrate intestinal architecture. To this aim, special focus will be addressed to identify the integrating signals from the surrounding niche, supporting a model whereby distinct cell populations facilitate homeostatic vs injury-induced regeneration.展开更多
Human endometrium is a unique adult tissue that undergoes cyclical shedding,repair,and regeneration during a woman’s reproductive life.Over the past 2 decades,tremendous progress has been made towards the identificat...Human endometrium is a unique adult tissue that undergoes cyclical shedding,repair,and regeneration during a woman’s reproductive life.Over the past 2 decades,tremendous progress has been made towards the identification and characterization of endometrial stromal stem/progenitor cells.The substantial regeneration of vascularized stroma in the endometrium during the proliferative stages of each menstrual cycle is likely to be mediated by endometrial mesenchymal stromal/stem cells.This review focuses on the perivascular niche for CD140b^(+)CD146^(+)pericytes and SUSD2^(+)perivascular cells.The identity,characteristics,and underlying mechanisms of uterine regeneration are also discussed.展开更多
Background:A challenge in current forestry is adaptation of managed forests to climate change,which is likely to alter the main processes of forest dynamics,i.e.natural regeneration.Scots pine will probably lose some ...Background:A challenge in current forestry is adaptation of managed forests to climate change,which is likely to alter the main processes of forest dynamics,i.e.natural regeneration.Scots pine will probably lose some parts of its distribution area in Europe.However,two native oaks,pedunculate and sessile may maintain or expand the area of their occurrence in central Europe.The utilization of spontaneous(not initialized by foresters)oak regeneration in Scots pine stands for the creation of next generation stands is one of the adaptation methods to climate change.Many factors influencing pedunculate oak regeneration are well known,but there is a lack of knowledge on the relation between soil enzyme activity and the establishment and development of the species.The aim of the study was to identify the relationships among stand characteristics,herb species composition,soil enzyme activity and the establishment or recruitment of oak regeneration in Scots pine-dominated stands.Results:The one of the most influential factors shaping the oak seedling count was dehydrogenase activity in the humus horizon.We found that plots without litter and fern cover had higher seedling density.The raspberry ground cover and birch crown projection area had a positive influence on oak seedling number.The factor indicating good conditions for high density of oak saplings was phosphatase activity in the organic horizon.The same enzyme activity but in humus horizon described conditions in which more numerous recruits were observed.Conclusions:The activity of soil enzymes can be used as the predictor of the establishment and advancement of oak regeneration but also could be seen as a new dimension of oak regeneration.The general density of spontaneous oak regeneration was not sufficient for the creation of new generation forest stands dominated by oak,but it is possible to use them as admixtures in new generation stands.展开更多
A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period ...A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.展开更多
基金the National Natural Science Foundation of China (30430570,30070602, and 30270244).
文摘Spatial and temporal patterns of seed bank dynamics in relation to gaps in an old growth tropical montane rainforest of Hainan Island, South China, were studied over two consecutive years. From June 2001 to June 2003, soil seed bank sampling blocks were taken near each of the four sides of each seed trap and immediately put into a nursery for observation of seedling emergence dynamics in four seasons （each experiment in each season）. The abundances of seedlings that emerged from seed banks showed the trend of vine functional group （VFG） 〉 shrub functional group （SFG） 〉 tree functional group （TFG） 〉 herb functional group （HFG）, but the trend in species richness of seedlings that emerged from the soil seed banks was TFG 〉 VFG 〉 SFG 〉 HFG. The abundances of seedlings that emerged from seed banks in the three gap zones showed no significant differences, but significant differences did exist for the species richness. The time of sampling or seasons of experiments had significant influences on both the species richness and seedling abundances. The seedling emergence processes of each experiment all revealed the unimodal patterns. Few emergences occurred 1 year after each experiment. Compared with those under closed canopies, the recruitment rates from seed to seedlings and from seedlings to saplings In gaps were higher, but the mortality rates from saplings to big trees were also higher in the gaps.
基金This project is supported by the Project of Shanghai Munic-ipal Health Commission[grant number 20204Y0012]National Key R&D Program of China[grant number 2017YFC0908100]+1 种基金Corhort Study of HCC and Liver Diseases,Double First-Class Fundation,Shanghai Jiao Tong University[grant number W410170015]Overall Leverage Clinical Medicine Center,NHFPC Fundation[grant number 2017ZZ01018].
文摘Cirrhosis is characterized as the progress of regenerative nodules surrounded by fibrous bands in response to chronic hepatic injury and causes portal hypertension and end-stage hepatic disease.Following liver injury,liver progenitor cells(LPCs)can be activated and differentiate into hepatocytes in order to awaken liver regeneration and reach homeosta-sis.Recent research has uncovered some new sources of LPCs.Here,we update the mecha-nisms of LPCs-mediated liver regeneration in cirrhosis by introducing the origin of LPCs and LPCs’niche with a discussion of the influence of LPC-related cells.This article analyzes the mechanism of regeneration and activation of LPCs in cirrhosis in recent years aiming to provide help for clinical application.
文摘The adult lung,a workhorse for gas exchange,is continually subjected to a barrage of assaults from the inhaled particles and pathogens.Hence,homeostatic maintenance is of paramount importance.Epithelial stem cells interact with their particular niche in the adult lung to orchestrate both natural tissue rejuvenation and robust post-injury regeneration.Advances in single-cell sequencing,lineage tracing,and living tissue imaging have deepened our understanding about stem cell heterogeneities,transition states,and specific cell lineage markers.In this review,we provided an overview of the known stem/progenitor cells and their subpopulations in different regions of the adult lung,and explored the regulatory networks in stem cells and their respective niche which collectively coordinated stem cell quiescence and regeneration states.We finally discussed relationships between dysregulated stem cell function and lung disease.
基金supported by the Agriculture College of Duhok University
文摘Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest.It was thus essential to assess regeneration before designing optimizing strategies.To this end,we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots(20×25 m)on the southern aspects where the Zawita natural forest is still present.In total,1540 regenerating P.brutia were recorded,854 seedlings,597 saplings,and 89 trees.Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees.Regeneration requirements differed between seedlings and saplings.The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction.The density of saplings only showed a positive significant correlation with increasing slope.The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m.Overall,the study highlighted the requirements for seedling regeneration as a relatively open canopy cover,a light understory litter layer,and noncompacted soils.These results are a step towards designing effective management and restoration programs.
文摘Among somatic stem cells, those residing in the intestine represent a fascinating and poorly explored research field. Particularly, somatic stem cells reside in the small intestine at the level of the crypt base, in a constant balance between self-renewal and differentiation. Aim of the present review is to delve into the mechanisms that regulate the delicate equilibrium through which intestinal stem cells orchestrate intestinal architecture. To this aim, special focus will be addressed to identify the integrating signals from the surrounding niche, supporting a model whereby distinct cell populations facilitate homeostatic vs injury-induced regeneration.
基金The Hong Kong University Shenzhen Hospital Scientific Research Training Plan(HKUSZH20192003)National Natural Science Foundation of China/Research Grants Council Joint Research Scheme(N_HKU 732/20)
文摘Human endometrium is a unique adult tissue that undergoes cyclical shedding,repair,and regeneration during a woman’s reproductive life.Over the past 2 decades,tremendous progress has been made towards the identification and characterization of endometrial stromal stem/progenitor cells.The substantial regeneration of vascularized stroma in the endometrium during the proliferative stages of each menstrual cycle is likely to be mediated by endometrial mesenchymal stromal/stem cells.This review focuses on the perivascular niche for CD140b^(+)CD146^(+)pericytes and SUSD2^(+)perivascular cells.The identity,characteristics,and underlying mechanisms of uterine regeneration are also discussed.
基金performed under the research project entitled“The ability of used oak natural regeneration in Scots pine stand conversion–the role of birds in forest regeneration process”,which was financially supported by the the Ministry of Science and Higher Education(Grant No.240–110).
文摘Background:A challenge in current forestry is adaptation of managed forests to climate change,which is likely to alter the main processes of forest dynamics,i.e.natural regeneration.Scots pine will probably lose some parts of its distribution area in Europe.However,two native oaks,pedunculate and sessile may maintain or expand the area of their occurrence in central Europe.The utilization of spontaneous(not initialized by foresters)oak regeneration in Scots pine stands for the creation of next generation stands is one of the adaptation methods to climate change.Many factors influencing pedunculate oak regeneration are well known,but there is a lack of knowledge on the relation between soil enzyme activity and the establishment and development of the species.The aim of the study was to identify the relationships among stand characteristics,herb species composition,soil enzyme activity and the establishment or recruitment of oak regeneration in Scots pine-dominated stands.Results:The one of the most influential factors shaping the oak seedling count was dehydrogenase activity in the humus horizon.We found that plots without litter and fern cover had higher seedling density.The raspberry ground cover and birch crown projection area had a positive influence on oak seedling number.The factor indicating good conditions for high density of oak saplings was phosphatase activity in the organic horizon.The same enzyme activity but in humus horizon described conditions in which more numerous recruits were observed.Conclusions:The activity of soil enzymes can be used as the predictor of the establishment and advancement of oak regeneration but also could be seen as a new dimension of oak regeneration.The general density of spontaneous oak regeneration was not sufficient for the creation of new generation forest stands dominated by oak,but it is possible to use them as admixtures in new generation stands.
基金supported by the Swedish International Development Agency (Sida)
文摘A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.
