Phosphorus limitation on CO_(2)fertilization effect in tropical forests informed by a coupled biogeochemical model

Tropical forests store more than half of the world's terrestrial carbon(C)pool and account for one-third of global net primary productivity(NPP).Many terrestrial biosphere models(TBMs)estimate increased productivity in tropical forests throughout the 21st century due to CO_(2)fertilization.However,phosphorus(P)liaitations on vegetation photosynthesis and productivity could significantly reduce the CO_(2)fertilization effect.Here,we used a carbon-nitrogen-phosphorus coupled model(Dynamic Land Ecosystem Model;DLEM-CNP)with heterogeneous maximum carboxylation rates to examine how P limitation has affected C fluxes in tropical forests during1860-2018.Our model results showed that the inclusion of the P processes enhanced model performance in simulating ecosystem productivity.We further compared the simulations from DLEM-CNP,DLEM-CN,and DLEMC and the results showed that the inclusion of P processes reduced the CO_(2)fertilization effect on gross primary production(GPP)by 25%and 45%,and net ecosystem production(NEP)by 28%and 41%,respectively,relative to CN-only and C-on ly models.From the 1860s to the 2010s,the DLEM-CNP estimated that in tropical forests GPP increased by 17%,plant respiration(Ra)increased by 18%,ecosystem respiration(Rh)increased by 13%,NEP increased by 121%per unit area,respectively.Additionally,factorial experiments with DLEM-CNP showed that the enhanced NPP benefiting from the CO_(2) fertilization effect had been offset by 135%due to deforestation from the 1860s to the 2010s.Our study highlights the importance of P limitation on the C cycle and the weakened CO_(2)fertilization effect resulting from P limitation in tropical forests.

Comparison of stem taper models for the four tropical tree species in Mount Makiling, Philippines

This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica(Magabuyo),Diplodiscus paniculatus(Balobo), Parashorea malaanonan(Bagtikan), and Swietenia macrophylla(Mahogany) in Mount Makiling Forest Reserve(MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate(SEE),coefficient of determination(R^2), mean bias( E),and absolute mean difference(AMD). For the lack-offit statistics, SEE, E and AMD were determined in different relative height classes. The results indicated that the Kozak02 stem taper model offered the best fit for the four tropical species in most statistics. The Kozak02 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, E and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height,merchantable stem volumes and total stem volumes of standing trees belonging to the four species of thetropical forest in MMFR.

Angiogenesis in a 3D model containing adipose tissue stem cells and endothelial cells is mediated by canonical Wnt signaling

Adipose-derived stromal cells （ASCs） have gained great attention in regenerative medicine. Progress in our understanding of adult neovascularization further suggests the potential of ASCs in promoting vascular regeneration, although the specific cues that stimulate their angiogenic behavior remain controversial In this study, we established a three-dimensional （3D） angiogenesis model by co-culturing ASCs and endothelial cells （ECs） in collagen gel and found that ASC-EC-instructed angiogenesis was regulated by the canonical Wnt pathway. Furthermore, the angiogenesis that occurred in implants collected after injections of our collagen gel- based 3D angiogenesis model into nude mice was confirmed to be functional and also regulated by the canonical Wnt pathway. Wnt regulation of angiogenesis involving changes in vessel length, vessel density, vessel sprout, and connection numbers occurred in our system. Wnt signaling was then shown to regulate ASC- mediated paracrine signaling during angiogenesis through the nuclear translocation of β-catenin after its cytoplasmic accumulation in both ASCs and ECs. This translocation enhanced the expression of nuclear cofactor Lef-1 and cyclin D1 and activated the angiogenic transcription of vascular endothelial growth factor A （VEGFA）, basic fibroblast growth factor （bFGF）, and insulin-like growth factor 1 （IGF-1）. The angiogenesis process in the 3D collagen model appeared to follow canonical Wnt signaling, and this model can help us understand the importance of the canonical Wnt pathway in the use of ASCs in vascular regeneration.

Human induced pluripotent stem cell based in vitro models of the blood-brain barrier： the future standard？

There is an urgent and tremendous need for human dis- ease models in drug development in order to improve pre- clinical predictability. In the case of brain disorders drugs have to cross the blood-brain barrier （BBB） to enter the central nervous system （CNS）. It was estimated that more than 95% of the drugs cannot cross the BBB.

Evaluation of Some Stem Taper Models for Camellia japonica in Mount Halla, Korea

This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were used in this study were standard error of estimate(SEE), mean bias( E), absolute mean difference(AMD), coefficient of determination(R2), and root mean square error(RMSE). Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics(SEE: 3.4708, E : 0.0040 cm, AMD : 0.9060 cm, R2 : 0.9870, and RMSE : 1.2545). On the other hand, Max and Burkhart stem taper model had the poorest performance in each statistical criterion(SEE: 4.2121, E : 0.2520 cm, AMD : 1.1300 cm, R2 : 0.9805, and RMSE: 1.5317). For the lack-of-fit statistics, the Kozak model 02 also provided the best performance having the best AMD in most of the relative height classes for diameter outside bark prediction and in most of the DBH classes for total volume prediction while Max and Burkhart had the poorest performance. These stem taper equations could help forest managers to better estimate the diameter outside bark at any given height, merchantable stem volumes and total stem volumes of the standing trees of Camellia japonica in the forests of Jeju Island, Korea.

The Effects of Flexible Vegetation on Forces with a Keulegan- Carpenter Number in Relation to Structures Due to Long Waves

Extreme coastal events require careful prediction of wave forces. Recent tsunamis have resulted in extensive damage of coastal structures. Such scenarios are the result of the action of long waves on structures. In this paper, the efficiency of vegetation as a buffer system in attenuating the incident ocean waves was studied through a well controlled experimental program. The study focused on the measurement of forces resulting from cnoidal waves on a model building mounted over a slope in the presence and absence of vegetation. The vegetative parameters, along with the width of the green belt, its position from the reference line, the diameter of the individual stems as well as the spacing between them, and their rigidity are varied so as to obtain a holistic view of the wave-vegetation interaction problem. The effect of vegetation on variations of dimensional forces with a Keulegan-Carpenter number （KC） was discussed in this paper. It has been shown that when vegetal patches are present in front of structure, the forces could be limited to within F＊≤I, by a percentile of 92%, 90%, 55%, and 96%, respectively for gap ratios of 0.0, 0.5, 1.0, and 1.5. The force is at its maximum for the gap ratio of 1.0 and beyond which the forces start to diminish.

Presenilin mutations and their impact on neuronal differentiation in Alzheimer’s disease

The presenilin genes(PSEN1 and PSEN2)are mainly responsible for causing early-onset familial Alzheimer’s disease,harboring~300 causative mutations,and representing~90%of all mutations associated with a very aggressive disease form.Presenilin 1 is the catalytic core of theγ-secretase complex that conducts the intramembranous proteolytic excision of multiple transmembrane proteins like the amyloid precursor protein,Notch-1,N-and E-cadherin,LRP,Syndecan,Delta,Jagged,CD44,ErbB4,and Nectin1a.Presenilin 1 plays an essential role in neural progenitor maintenance,neurogenesis,neurite outgrowth,synaptic function,neuronal function,myelination,and plasticity.Therefore,an imbalance caused by mutations in presenilin 1/γ-secretase might cause aberrant signaling,synaptic dysfunction,memory impairment,and increased Aβ42/Aβ40 ratio,contributing to neurodegeneration during the initial stages of Alzheimer’s disease pathogenesis.This review focuses on the neuronal differentiation dysregulation mediated by PSEN1 mutations in Alzheimer’s disease.Furthermore,we emphasize the importance of Alzheimer’s disease-induced pluripotent stem cells models in analyzing PSEN1 mutations implication over the early stages of the Alzheimer’s disease pathogenesis throughout neuronal differentiation impairment.

Pluripotent Stem Cells Models for Huntington's Disease:Prospects and Challenges

Pluripotent cellular models have shown great promise in the study of a number of neurological disorders. Several advantages of using a stem cell model include the potential for cells to derive disease relevant neuronal cell types, providing a system for researchers to monitor disease progression during neurogenesis, along with serving as a platform for drug discovery. A number of stem cell derived models have been employed to establish in ~,itro research models of Huntington＇s disease that can be used to investigate cellular pathology and screen lk^r drug and cell-based therapies. Although some progress has been made, there are a number of challenges and limitations that must be overcome before the true potential of this research strategy is achieved. In this article we review current stem cell models that have been reported, as well as discuss the issues that impair these studies. We also highlight the prospective application of Huntington＇s disease stem cell models in the development of novel therapeutic strategies and advancement of personalized medicine.

Human embryos in a dish - modeling early embryonic development with pluripotent stem cells

Stem cell-based embryo models present new opportunities to study early embryonic development.In a recent study,Kagawa et al.identified an approach to create human pluripotent stem cell-based blastoids that resemble the human blastocysts.These blastoids efficiently generated analogs of the EPI,TE,PrE lineages with transcriptomes highly similar to those found in vivo.Furthermore,the formation of these lineages followed the same sequence and pace of blas-tocyst development,and was also dependent on the same pathways required for lineage specification.Finally,the blastoids were capable of attaching to stimulated endometrial cells to mimic the process of implantation.While more comprehensive analysis is needed to confirm its validity and usefulness,this new blastoid system presents the latest development in the attempt to model early human embryogenesis in vitro.