Deer antler stem cell niche: An interesting perspective

In recent years,there has been considerable exploration into methods aimed at enhancing the regenerative capacity of transplanted and/or tissue-resident cells.Biomaterials,in particular,have garnered significant interest for their potential to serve as natural scaffolds for cells.In this editorial,we provide commentary on the study by Wang et al,in a recently published issue of World J Stem Cells,which investigates the use of a decellularized xenogeneic extracellular matrix(ECM)derived from antler stem cells for repairing osteochondral defects in rat knee joints.Our focus lies specifically on the crucial role of biological scaffolds as a strategy for augmenting stem cell potential and regenerative capabilities,thanks to the establishment of a favorable microenvironment(niche).Stem cell differen-tiation heavily depends on exposure to intrinsic properties of the ECM,including its chemical and protein composition,as well as the mechanical forces it can generate.Collectively,these physicochemical cues contribute to a bio-instructive signaling environment that offers tissue-specific guidance for achieving effective repair and regeneration.The interest in mechanobiology,often conceptualized as a form of“structural memory”,is steadily gaining more validation and momen-tum,especially in light of findings such as these.

Distribution and dynamics of niche and interspecific association of dominant phytoplankton species in the Feiyun River basin,Zhejiang,China

To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the downstream were chosen as the study area,for which 22 sampling sites were designated.Sampling was conducted in September 2021,January,May,and July 2022.Phytoplankton species were identified from both quantitative samples and in-vivo observations.Phytoplankton was quantified by direct counting.Results show that there were 98 species belonging to 6 phyla and 78 genera.In addition,to clarify the niches of the dominant phytoplankton species and their interspecific association,the dominance index was calculated,and a comprehensive analysis was conducted including niche width,niche overlap value,ecological response rate,overall association,chi-square test,and the stability.The phytoplankton community exhibited characteristics of a Cyanobacteria-Chlorophyta-Diatom type community,showing higher diversity in spring and lower diversity in summer.Among 11 dominants phytoplankton species from 3 phyla,both frequency and dominance degree varied seasonally,of which Microcystis sp.was the dominant species in Spring,Autumn,and Winter.The niche widths of the dominant species ranged from 0.234 to 0.933,and were categorized into three groups.The niche overlap values of the 11 dominant species ranged from 0.359 to 0.959,exhibiting significant seasonal differences-highest in winter followed by autumn,spring,and summer in turn.The overall correlation among dominant species in all four seasons revealed a non-significant negative association,resulting in an unstable community structure.A significant portion(84.2%)of species pairs displayed positive associations,suggesting a successional pattern where Diatoms dominated while other dominant species shared resources and space.Despite this pattern,stability measurements indicated that the dominant species community remained unstable.Therefore,careful monitoring is recommended for potential water environment issues arising from abnormal proliferation of dominant species in the watershed during winter.This research built a theoretical foundation with a data support to the early warning of eutrophication and provided a reference for water resources management in similar watersheds along the eastern coast of China.

Distribution,abundance,and realized niches of meroplankton by two different mesh size nets during spring 2017 in the Southern Yellow Sea,China

Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.

Post-disaster spatial reconstruction from the perspective of a rural settlement niche in the upper reaches of the Minjiang River

Post-disaster recovery and reconstruction provide an effective way to reduce the disaster vulnerability of, and promote leapfrog development in, an affected area. To date, studies that have used administrative boundaries to investigate the reconstruction of settlement space have not been able to clearly define the real boundaries of land use changes or quantify the degree of response to the ‘Build-Back-Better’ initiative, and have lacked any consideration of the fourth reconstruction stage–development period(10 years). This study constructed a mountain settlement niche and analyzed the characteristics, spatial reconstruction, and drivers of rural settlements during 2009–2019 in the upper reaches of the Minjiang River, southwest China. The results showed the following:(1) Natural factors were the basis for the formation and development of mountain settlement niches. The scale of the settlement niche and its land use structure depended on the physical geography features and the ethnic farming and grazing traditions. The settlement niche provided a realistic boundary for the spatial reconstruction.(2) The layout of residential land around cropland was the common feature of the mountain settlement niche. Of all the land use types, the roads and rural residential lands showed the most change over the 10 years;13,860 residential patches increased in size and 4,742 patches were abandoned.(3) The area of orchards, planted to reconstruct the economy in the mountains, increased by nearly 2.5 times.(4) Collapses, landslides, and debris flow disasters and the ecological red line influenced the spatial reconstruction. While the main focus of post-disaster recovery is spatial reconstruction, initiatives should include economic and spiritual recovery, and should also achieve sustainable development of the region.

A Single-Cell Landscape of Human Liver Transplantation Reveals a Pathogenic Immune Niche Associated with Early Allograft Dysfunction

Liver transplantation(LT)is the standard therapy for individuals afflicted with end-stage liver disease.Despite notable advancements in LT technology,the incidence of early allograft dysfunction(EAD)remains a critical concern,exacerbating the current organ shortage and detrimentally affecting the prognosis of recipients.Unfortunately,the perplexing hepatic heterogeneity has impeded characterization of the cellular traits and molecular events that contribute to EAD.Herein,we constructed a pioneering single-cell transcriptomic landscape of human transplanted livers derived from non-EAD and EAD patients,with 12 liver samples collected from 7 donors during the cold perfusion and portal reperfusion stages.Comparison of the 75231 cells of non-EAD and EAD patients revealed an EAD-associated immune niche comprising mucosal-associated invariant T cells,granzyme B^(+)(GZMB^(+))granzyme K^(+)(GZMK^(+))natural killer cells,and S100 calcium binding protein A12^(+)(S100A12^(+))neutrophils.Moreover,we verified this immune niche and its association with EAD occurrence in two independent cohorts.Our findings elucidate the cellular characteristics of transplanted livers and the EAD-associated pathogenic immune niche at the single-cell level,thus,offering valuable insights into EAD onset.

A Reference Vector-Assisted Many-Objective Optimization Algorithm with Adaptive Niche Dominance Relation

It is still a huge challenge for traditional Pareto-dominatedmany-objective optimization algorithms to solve manyobjective optimization problems because these algorithms hardly maintain the balance between convergence and diversity and can only find a group of solutions focused on a small area on the Pareto front,resulting in poor performance of those algorithms.For this reason,we propose a reference vector-assisted algorithmwith an adaptive niche dominance relation,for short MaOEA-AR.The new dominance relation forms a niche based on the angle between candidate solutions.By comparing these solutions,the solutionwith the best convergence is found to be the non-dominated solution to improve the selection pressure.In reproduction,a mutation strategy of k-bit crossover and hybrid mutation is used to generate high-quality offspring.On 23 test problems with up to 15-objective,we compared the proposed algorithm with five state-of-the-art algorithms.The experimental results verified that the proposed algorithm is competitive.

Cellular and molecular characteristics of the premetastatic niches

The premetastatic niches(PMN)formed by primary tumor-derived molecules regulate distant organs and tissues to further favor tumor colonization.Targeted PMN therapy may prevent tumor metastasis in the early stages,which is becoming increasingly important.At present,there is a lack of in-depth understanding of the cellular and molecular characteristics of the PMN.Here,we summarize current research advances on the cellular and molecular characteristics of the PMN.We emphasize that PMN intervention is a potential therapeutic strategy for early prevention of tumor metastasis,which provides a promising basis for future research and clinical application.

Injectable hydrogel made from antler mesenchyme matrix for regenerative wound healing via creating a fetal-like niche

BACKGROUND Scar formation and loss of cutaneous appendages are the greatest challenges in cutaneous wound healing.Previous studies have indicated that antler reserve mesenchyme(RM)cells and their conditioned medium improved regenerative wound healing with partial recovery of cutaneous appendages.AIM To develop hydrogels from the antler RM matrix(HARM)and evaluate the effect on wound healing.METHODS We prepared the hydrogels from the HARM via enzymatic solubilization with pepsin.Then we investigated the therapeutic effects of HARM on a full-thickness cutaneous wound healing rat model using both local injections surrounding the wound and topical wound application.RESULTS The results showed that HARM accelerated wound healing rate and reduced scar formation.Also,HARM stimulated the regeneration of cutaneous appendages and blood vessels,and reduced collagen fiber aggregation.Further study showed that these functions might be achieved via creating a fetal-like niche at the wound site.The levels of fetal wound healing-related genes,including Collagen III and TGFβ3 treated with HARM were all increased,while the expression levels of Collagen I,TGFβ1,and Engrailed 1 were decreased in the healing.Moreover,the number of stem cells was increased in the fetal-like niche created by HARM,which may contribute to the regeneration of cutaneous appendages.CONCLUSION Overall,we successfully developed an injectable hydrogel made from antler RM matrix for the regenerative repair of full-thickness cutaneous wounds.We uncovered the molecular mechanism of the hydrogels in promoting regenerative wound healing,and thus pave the way for HARM to be developed for the clinic use.

Single-cell RNA sequencing in cornea research:Insights into limbal stem cells and their niche regulation

The corneal epithelium is composed of stratified squamous epithelial cells on the outer surface of the eye,which acts as a protective barrier and is critical for clear and stable vision.Its continuous renewal or wound healing depends on the proliferation and differentiation of limbal stem cells(LSCs),a cell population that resides at the limbus in a highly regulated niche.Dysfunction of LSCs or their niche can cause limbal stem cell deficiency,a disease that is manifested by failed epithelial wound healing or even blindness.Nevertheless,compared to stem cells in other tissues,little is known about the LSCs and their niche.With the advent of single-cell RNA sequencing,our understanding of LSC characteristics and their microenvironment has grown considerably.In this review,we summarized the current findings from single-cell studies in the field of cornea research and focused on important advancements driven by this technology,including the heterogeneity of the LSC population,novel LSC markers and regulation of the LSC niche,which will provide a reference for clinical issues such as corneal epithelial wound healing,ocular surface reconstruction and interventions for related diseases.

Ecological Niche Modelling Reveals the Peculiarities of Ecological Disjunction Between Two Sympatric Racerunners in Kazakhstan:Eremias lineolata(Nikolsky,1897)and Eremias scripta(Strauch,1867)

The ecological-niche models for two sympatric species,Eremias lineolata(Nikolsky,1897)and Eremias scripta(Strauch,1867),reveal evidence of spatial and temporal disjunction in the actual niches of both species.Eremias lineolata demonstrates a wide range of adaptations and,at the same time,has a greater need for winter precipitation and minimal temperature than E.scripta.Possible explanations for the thermal diversity of both species are provided.Thermal variables(monthly temperatures,monthly solar radiation,etc.)are traditionally important for ectotherm animals.Interestingly,as many as half of the key variables in both species are related to different aspects of environmental water balance(precipitation,air humidity,vapor pressure).There are several ways in which moisture may impact the lizard’s life cycle.Soil humidity is related to soil temperature and may be important during winter hibernation.In summer,soil humidity may support successful embryogenesis.Precipitation during the warm months is a key factor in maintaining the moisture content of the soil.In winter,snow cover provides a better thermal balance of the soil’s top layers where winter shelters are housed.Ecological niche modeling(ENM)is an interdisciplinary approach combining the geographical,climatic,ecological,and biological aspects of the wellbeing of species.This interdisciplinary approach lifts biological studies onto a new,integrative level,providing a comprehensive view on species biology and answering the questions that might not be answered if the traditional methods for studying animals were used alone.

Niche differentiation shapes the bacterial diversity and composition of apple

Microorganisms play an important role in plant growth,health and ecological function.It is necessary to explore the microbial community because of the significant ecological and economic value of apples(Malus x domestica).However,the related bacterial communities in different ecological habitats are not clear in the unique scion/rootstock combinations of apples.In this study,the Illumina Miseq platform was used to analyze the bacterial communities in different niches(bulk soil,rhizosphere soil and roots)of two scion/rootstock combinations[Fuji/Malus xiaojinensis Cheng et Jiang(Mx)and Fuji/Malus baccata(L.)Borkh.(Mb)].The relationship between the microbial community,soil properties,and plant characters was explored.The results showed that the diversity of the bacterial community decreased from bulk soil to rhizosphere soil and then to roots.In addition,at the phylum level,Proteobacteria,Actinobacteria and Acitinobacteria were dominant and had notable divergence in different ecological niches.Distinct niches had remarkable effects on the diversity and composition of the bacterial community according to PCoA.The rootstock genotype had an effect on the bacterial composition but no effect on the diversity.pH,soil organic matter(SOM),alkaline hydrolyzable nitrogen(AN)were the main factor affecting the structure of bacterial community in rhizosphere soil,as shown by Pearson analysis.Bacteria taxa in the roots were affected by starch,fructose,sucrose and sorbitol.This study showed the microbial community structure in different ecological niches of different scion/rootstock combinations and provided some evidence for understanding the microbial-plant interaction of apple rootstocks.

Host niche, genotype, and field location shape the diversity and composition of the soybean microbiome

Plant-associated microbes represent a key determinant of plant fitness through acquiring nutrients,promoting growth,and resisting to abiotic and biotic stresses.However,an extensive characterization of the bacterial and fungal microbiomes present in different plant compartments of soybean in field conditions has remained elusive.In this study,we investigated the effects of four niches(roots,stems,leaves,and pods),four genotypes(Andou 203,Hedou 12,Sanning 16,and Zhonghuang 13),and three field locations(Jining,Suzhou,and Xuzhou)on the diversity and composition of bacterial and fungal communities in soybean using 16S and internal transcribed spacer rRNA amplicon sequencing,respectively.The soybean microbiome significantly differed across organs.Host genotypes explained more variation in stem bacterial community composition and leaf fungal community composition.Field location significantly affected the composition of bacterial communities in all compartments and the effects were stronger in the root and stem than in the leaf and pod,whereas field location explained more variation in stem and leaf fungal community composition than in the root and pod.The relative abundances of potential soybean fungal pathogens also differed among host organs and genotypes,reflecting the niches of these microbes in the host and probably their compatibility to the host genotypes.Systematic profiling of the microbiome composition and diversity will aid the development of plant protection technologies to benefit soybean health.

Allopolyploid origin and niche expansion of Rhodiola integrifolia(Crassulaceae)

Polyploidy after hybridization between species can lead to immediate post-zygotic isolation,causing saltatory origin of new species.Although the incidence of polyploidization in plants is high,it is thought that a new polyploid lineage can succeed only if it establishes a new ecological niche divergent from its progenitor lineages.We tested the hypothesis that Rhodiola integrifolia from North America is an allopolyploid produced by R. rhodantha and R.rosea and determined whether its survival can be explained by the niche divergence hypothesis.To this end,we sequenced two low-copy nuclear genes(ncpGS and rpb2) in a phylogenetic analysis of 42 Rhodiola species and tested for niche equivalency and similarity using Schoener’s D as the index of niche overlap.Our phylogeny-based approach showed that R integrifolia possesses alleles from both R. rhodantha and rosea Dating analysis showed that the hybridization event that led to R.integrifolia occurred ca.1.67 Mya and niche modeling analysis showed that at this time,both R.rosea and R.rhodantha may have been present in Beringia,providing the opportunity for the hybridization event.We also found that the niche of R.integrifolia differs from that of its progenitors in both niche breadth and optimum.Taken together,these results confirm the hybrid origin of R.integrifolia and support the niche divergence hypothesis for this tetraploid species.Our results underscore the fact that lineages with no current overlapping distribution could produce hybrid descendants in the past,when climate oscillations made their distributions overlap.

Spatial niche segregation between bird species in the Białowieża primeval forest(NE Poland)

Drivers of bird niche separation in temperate primeval forests have not yet been determined,due to the low number of intact forest sites.Here,we analyzed the general patterns of niche usage on trees by birds’assemblages.We tested how tree species affect the sharing of space in an assemblage of birds and their level of specialization.We conducted our study in the Białowieża primeval forest(NE Poland).During two breeding seasons,we observed bird positions on trees,divided into three vertical and six horizontal zones in 768 observation points.Based on the interaction networks framework we calculated the Kullback-Leibler distance d′as a metric of species specialization and the resource range RR index,which estimates the species’specificity based on the fraction of space utilized with a non-zero performance.The d′index was the highest in the lower understory for all parts of the tree on the basis of the position from the trunk.The RR index was the highest in the lower understory for all parts based on the position from the trunk.Regarding the tree species,the lowest d′index was observed in all tree species together,and hornbeam,whereas the highest in oak.At the tree species level,the RR index was the lowest for hornbeam.We show tree species importance in forest space sharing in the case of bird assemblages.Hornbeam,alder,and spruce are universal species that were used by birds almost entirely.In contrast,oak,lime,and maple were only partially used.Tree species with less complex structures could shape bird assemblages,as they could offer birds much fewer niches to realize.Therefore,we showed that high specialization and niche separation are drivers of high bird diversity.Consequently maintaining a diverse stand structure is crucial for biodiversity conservation.

Preliminary delivery efficiency prediction of nanotherapeutics into crucial cell populations in bone marrow niche

Several crucial stromal cell populations regulate hematopoiesis and malignant diseases in bone marrow niches.Precise regulation of these cell types can remodel niches and develop new therapeutics.Multiple nanocarriers have been developed to transport drugs into the bone marrow selectively.However,the delivery efficiency of these nanotherapeutics into crucial niche cells is still unknown,and there is no method available for predicting delivery efficiency in these cell types.Here,we constructed a three-dimensional bone marrow niche composed of three crucial cell populations:endothelial cells(ECs),mesenchymal stromal cells(MSCs),and osteoblasts(OBs).Mimetic niches were used to detect the cellular uptake of three typical drug nanocarriers into ECs/MSCs/OBs in vitro.Less than 5%of nanocarriers were taken up by three stromal cell types,and most of themwere located in the extracellular matrix.Delivery efficiency in sinusoidal ECs,arteriole ECs,MSCs,and OBs in vivo was analyzed.The correlation analysis showed that the cellular uptake of three nanocarriers in crucial cell types in vitro is positively linear correlated with its delivery efficiency in vivo.The delivery efficiency into MSCs was remarkably higher than that into ECs and OBs,no matterwhat kind of nanocarrier.The overall efficiency into sinusoidal ECswas greatly lower than that into arteriole ECs.All nanocarriers were hard to be delivered into OBs(<1%).Our findings revealed that cell tropisms of nanocarriers with different compositions and ligand attachments in vivo could be predicted via detecting their cellular uptake in bone marrow niches in vitro.This study provided the methodology for niche-directed nanotherapeutics development.

Advancing Pediatric Hemodialysis Care through the Novel Intervention in Children’s Healthcare (NICH) Program

Racial, ethnic, and socioeconomic disparities present daunting hurdles that prevent equitable health outcomes for patients with end-stage kidney disease (ESKD) on hemodialysis. Additional resources, such as the Novel Intervention in Children’s Health (NICH) at Lucille Packard Children’s Hospital Stanford, provide individualized support to best assist families by assessing barriers to care with the goal of improving health outcomes. In this retrospective cohort study, we reviewed patients with ESKD on hemodialysis involved in NICH to explore if NICH serves as a liaison between the patients and multidisciplinary medical team and to explore if NICH helps patients better manage the challenges of end-stage kidney disease. Through the electronic medical record system, EPIC, we reviewed the patients’ surveys to identify barriers to care, which included school and life engagement difficulty, lack of mental health resources, food and transportation insecurity, and cultural/language barriers. We also tracked the number of hospitalizations and ED visits before and during the patients’ enrollment in NICH. We discovered that through NICH, the aforementioned barriers to care were eliminated, the number of hospitalizations and emergency department visits was reduced, and all patients transitioned from inactive to active on the transplant list. NICH successfully improved the health outcomes of these patients and empowered patients to be more engaged in their care.

干细胞niche与肿瘤干细胞产生和发展的关系

肿瘤干细胞学说认为大部分肿瘤来源于肿瘤干细胞。肿瘤干细胞与正常干细胞一样具有自我更新能力,能够产生肿瘤组织团块中的各种增殖和分化的细胞。肿瘤干细胞可能来源于正常干细胞或分化细胞。干细胞niche是干细胞生存的微环境,通过提供抑制细胞增殖和生长的信号来维持干细胞于静止状态。干细胞niche功能异常会导致niche的数量增加,以及干细胞功能异常和数量增加。肿瘤干细胞可能在异常的niche中存活,打破这种异常的niche就会削弱肿瘤干细胞的自我更新,从而抑制肿瘤的生长。靶向肿瘤干细胞异常微环境的治疗策略可能是癌症治疗的一个方向。

益气补肾方调控胃癌干细胞niche及Notch信号通路抗转移分子机制研究

[目的]探讨益气补肾方调控胃癌肿瘤干细胞(cancer stem cells,CSC)niche及Notch信号通路抗胃癌增殖转移的分子机制,为临床应用提供实验依据。[方法]采用人胃癌细胞株NCI-N87建立胃癌CSC富集裸鼠荷瘤模型。裸鼠随机分为阴性对照组、模型对照组、氟尿嘧啶组(5-Fu组)、益气补肾方组(益气补肾组)及益气补肾方+氟尿嘧啶组(协同组)。每组药物干预6周,观察裸鼠体质量变化及瘤体生长情况,比较各组肿瘤增殖及远处转移情况;采用ELISA法检测瘤体血管内皮生长因子受体-1(vascular endothelial growth factor receptor-1,VEGFR-1)、骨桥蛋白(osteopontin,OPN)、缺氧诱导因子-1α(hypoxia-inducible factor-1α,HIF-1α)、CXC趋化因子受体4(CXC chemokine receptor 4,CXCR4)表达;采用免疫组化法检测肿瘤组织中CD24、CD44、上皮细胞粘附分子(epithelial cell adhesion molecule,Ep CAM)的表达;采用Western blot检测肿瘤组织Notch1、Jagged1蛋白表达。[结果]给药6周后,益气补肾组、协同组及阴性对照组裸鼠体质量均明显重于模型对照组、5-Fu组,差异均有统计学意义(P<0.01);模型对照组与阴性对照组裸鼠的瘤体均重于5-Fu组、益气补肾组及协同组,差异有统计学意义(P<0.01)。5-Fu组、益气补肾组及协同组裸鼠的肝脏、腹壁、淋巴结及肺的总转移率明显少于模型对照组,差异有统计学意义(P<0.05)。与模型对照组比,5-Fu组、益气补肾组及协同组瘤体内VEGFR-1、OPN、HIF-1α、CXCR4的表达下调,差异有统计学意义(P<0.05,P<0.01)。益气补肾组与协同组CD24、CD44的表达均低于模型对照组及5-Fu组,差异有统计学意义(P<0.05)。益气补肾组Ep CAM的表达低于模型对照组及5-Fu组,差异有统计学意义(P<0.05)。益气补肾组及协同组瘤体组织中Notch1、Jagged1蛋白表达均低于模型对照组,差异有统计学意义(P<0.05)。[结论]益气补肾方具有显著的抗胃癌细胞增殖转移的作用,其机制可能是通过调控CSC niche及Notch信号通路,进而下调胃癌CSC表面标志物CD24、CD44、Ep CAM的表达,诱导胃癌CSC良性分化,从而降低瘤体内CSC比例。

Population Dynamics and Breeding Space Niche of Four Heron Species in Tanghai Wetlands

The population dynamics and breeding behaviors of Black-crowned Night Herons （ Nycticorax nycticorax ）, Egrets （Egtetta garzetta）, Chinese Pond Herons （Ardeola bacchus） and Great Egrets （Casmerodius albus） were observed in Tanghai Wetlands, Hebei Province from August 2004 to July 2005. Further, we studied the relationship of nest space distribution and directly calculated the nest density of vertical and horizontal levels, the niche overlapping index and the niche breadth. The results showed that there were two breeding areas, named Area Ⅰ and Area Ⅱ . The maximum population occurred in the period from April to September and was approximately 5800 individuals. Area Ⅰ was occupied earlier than Area Ⅱ by approximately half a month. In the breeding period, Black-crowned Night Herons were dominant in numbers and most occupied the upper nests of the core areas. Great Egrets also took the upper nests but they have the smallest population. Most Egrets took the middle nests of the edges of the area. Chinese Pond Herons, with a smaller population than the Egret, mostly nested in the edges, but some of them also took the lower nests of the core area. On the whole, the vertical niche of Egrets is the widest, the horizontal niche of Black-crowned Night Herons is the widest and the niche breadth of Chinese Pond Herons is the largest. The nest distribution pattern is the most similar between Chinese Pond Herons and Black-crowned Night Herons, and the niche overlapping index of Chinese Pond Herons and Egrets is the largest. Black-crowned Night Herons and Great Egrets control Egrets and Chinese Pond Herons in competition. Rich food and the optimal ecological environments lead to plenty of herons in the wetlands. In addition, it is a distinguishing feature of the four species that nests are built in poplar trees over 22 m tall.

成体干细胞Niche与肺脏修复

肺脏是个开放的复杂器官,覆盖其表面的上皮细胞持续暴露在病原微生物和大气污染物中,最易受到损伤,因而关于它的结构和功能修复问题一直是研究的热点。成体干细胞具有多向分化潜能,在不同niche的作用下可以分化成不同的细胞。肺脏的不同区域含有不同的干细胞,而且这些上皮干细胞在某些特定的条件下可以产生增殖和转分化,因而这些不同水平的干细胞可以通过不同的修复方式来实施肺脏结构和功能的维持和修复,但这些干细胞的来源及其在肺脏修复中的作用和机制并不十分清楚。因此对肺脏成体干细胞的研究进展进行综述以期对肺脏的修复有一个新的认识。