Distribution patterns of clonal plants in the subnival belt of the Hengduan Mountains,SW China

Clonal reproduction(i.e.,production of potentially independent offspring by vegetative growth)is thought to provide plants with reproductive assurance.Thus,studying the evolution of clonal reproduction in local floras is crucial for our understanding of the adaptive mechanisms plants deploy in stressful environments such as alpine regions.In this study,we characterized clonal plant species in the subnival belt of the Hengduan Mountains(a global biodiversity hotspot with extreme environmental conditions in southwest China),in order to determine the effects of sex system,growth form,and elevational distribution on clonality.We compiled clonality data of angiosperm species belonging to 41 families in the subnival belt of the Hengduan Mountains using published information.Of the 793 species recorded in the region,47.92%(380 species)are clonal species.Both sex system and growth form had significant effects on the occurrence of clonal reproduction:unisexual species(79.79%)were more likely to be clonal than bisexual species(43.63%),and herbaceous species(51.04%)were more likely to be clonal than woody species(16.67%).Compared with non-alpine-endemic species(44.60%),alpine-endemic species(58.33%)showed a significantly higher proportion of clonal reproduction.Further logistic regression analysis showed a positive association between incidence of clonality and elevational range,indicating that species distributed at high elevations are more likely to be clonal.Furthermore,the elevational gradients in clonality were contingent on sex system or growth form.This study reveals that plants in the subnival belt of the Hengduan Mountains might optimize their probability of reproduction through clonal reproduction,a finding that adds to our growing understanding of plant's adaptations to harsh alpine environments.

Cdc42 deletion yielded enamel defects by disrupting mitochondria and producing reactive oxygen species in dental epithelium

Developmental defects of enamel are common due to genetic and environmental factors before and after birth.Cdc42,a Rho family small GTPase,regulates prenatal tooth development in mice.However,its role in postnatal tooth development,especially enamel formation,remains elusive.Here,we investigated Cdc42 functions in mouse enamel development and tooth repair after birth.Cdc42 showed highly dynamic temporospatial patterns in the developing incisors,with robust expression in ameloblast and odontoblast layers.Strikingly,epithelium-specific Cdc42 deletion resulted in enamel defects in incisors.Ameloblast differentiation was inhibited,and hypomineralization of enamel was observed upon epithelial Cdc42 deletion.Proteomic analysis showed that abnormal mitochondrial components,phosphotransferase activity,and ion channel regulator activity occurred in the Cdc42 mutant dental epithelium.Reactive oxygen species accumulation was detected in the mutant mice,suggesting that abnormal oxidative stress occurred after Cdc42 depletion.Moreover,Cdc42 mutant mice showed delayed tooth repair and generated less calcified enamel.Mitochondrial dysfunction and abnormal oxygen consumption were evidenced by reduced Apool and Timm8a1 expression,increased Atp5j2 levels,and reactive oxygen species overproduction in the mutant repair epithelium.Epithelium-specific Cdc42 deletion attenuated ERK1/2 signaling in the labial cervical loop.Aberrant Sox2 expression in the mutant labial cervical loop after clipping might lead to delayed tooth repair.These findings suggested that mitochondrial dysfunction,up-regulated oxidative stress,and abnormal ion channel activity may be among multiple factors responsible for the observed enamel defects in Cdc42 mutant incisors.Overall,Cdc42 exerts multidimensional and pivotal roles in enamel development and is particularly required for ameloblast differentiation and enamel matrix formation.

3D-printed cell-free PCL-MECM scaffold with biomimetic micro-structure and micro-environment to enhance in situ meniscus regeneration

Despite intensive effort was made to regenerate injured meniscus by cell-free strategies through recruiting endogenous stem/progenitor cells,meniscus regeneration remains a great challenge in clinic.In this study,we found decellularized meniscal extracellular matrix(MECM)preserved native meniscal collagen and glycosaminoglycans which could be a good endogenous regeneration guider for stem cells.Moreover,MECM significantly promoted meniscal fibrochondrocytes viability and proliferation,increased the expression of type II collagen and proteoglycans in vitro.Meanwhile,we designed 3D-printed polycaprolactone(PCL)scaffolds which mimic the circumferential and radial collagen orientation in native meniscus.Taken these two advantages together,a micro-structure and micro-environment dually biomimetic cell-free scaffold was manipulated.This cell-free PCL-MECM scaffold displayed superior biocompatibility and yielded favorable biomechanical capacities closely to native meniscus.Strikingly,neo-menisci were regenerated within PCL-MECM scaffolds which were transplanted into knee joints underwent medial meniscectomy in rabbits and sheep models.Histological staining confirmed neo-menisci showed meniscus-like heterogeneous staining.Mankin scores showed PCL-MECM scaffold could protect articular cartilage well,and knee X-ray examination revealed same results.Knee magnetic resonance imaging(MRI)scanning also showed some neo-menisci in PCL-MECM scaffold group.In conclusion,PCL-MECM scaffold appears to optimize meniscus regeneration.This could represent a promising approach worthy of further investigation in preclinical applications.