The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 ...The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.展开更多
The knowledge of the existence,distribution and fate of polycyclic aromatic hydrocarbons(PAHs)and substituted polycyclic aromatic hydrocarbons(SPAHs)in wastewater treatment plants(WWTPs)was vital for reducing their co...The knowledge of the existence,distribution and fate of polycyclic aromatic hydrocarbons(PAHs)and substituted polycyclic aromatic hydrocarbons(SPAHs)in wastewater treatment plants(WWTPs)was vital for reducing their concentrations entering the aquatic environment.The concentrations of 13 SPAHs and 16 PAHs were all determined in a WWTP with styrene butadiene rubber(SBR)in partnership with the moving bed biofilm reactor(MBBR)process.SPAHs presented a higher concentration lever than PAHs in nearly all samples.The total removal efficiencies of PAHs and SPAHs ranged from 64.0%to 71.36%and 78.4%to 79.7%,respectively.The total yearly loads of PAHs(43.0 kg)and SPAHs(73.0 kg)were mainly reduced by the primary and SBR/MBBR biological treatment stages.The tertiary treatment stage had a minor contribution to target compounds removal.According to a synthesis and improvement fate model,we found that the dominant processes changed as the chemical octanol water partition coefficient(K_(ow))increased.But the seasonal variations of experimental removal efficiencies were more obvious than that of predicted data.In the primary sedimentation tank,dissolution in the aqueous phase and sorption to sludge/particulate matter were controlling processes for the removal of PAHs and SPAHs.The sorption to sludge and biodegradation were the principal removal mechanisms during the SBR/MBBR biological treatment process.The contribution of volatilization to removal was always insignificant.Furthermore,the basic physicochemical properties and operating parameters influenced the fate of PAHs and SPAHs in the WWTP.展开更多
The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot e...The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.Residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.Furthermore,of the residual N,approximately 5.4%was taken up on average in the following season and 50.2%was lost,but 44.4%remained in the soil.Hence,the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha–1in order to achieve a balance between rice yield and high N fertilizer uptake.展开更多
Japanese British writer Kazuo Ishiguro is one of the leading writers in contemporary British literature.He has always been committed to creating works with universal significance.Responsibility and destiny are themes ...Japanese British writer Kazuo Ishiguro is one of the leading writers in contemporary British literature.He has always been committed to creating works with universal significance.Responsibility and destiny are themes that run through his works.His novel Never Let Me Go tells a story of a group of clones growing up in the Hailsham,who are given the mission to donate organs at birth.So,there is no doubt that they will inevitably end their lives in the process of donating organs to human beings again and again.The tragic life of clones is determined by the motivation of human to create them.展开更多
[Objective] The aim of this study was investigated the rice yield, nitrogen uptake and ^15-fertilizer fate at different transplanting density to provide scientific ba- sis for improving the yield of rice and applying ...[Objective] The aim of this study was investigated the rice yield, nitrogen uptake and ^15-fertilizer fate at different transplanting density to provide scientific ba- sis for improving the yield of rice and applying reasonably fertilizer. [Method] A field experiment was carried out to study the effect of different transplanting density on rice yield, nitrogen (N) absorption, sources of N uptake by rice and the N balance in the plant-soil systems by using ^15-labelled urea. [Result] There were no significant differences in rice yields and total N uptakes by rice between treatments 30 cm × 30 cm and 40 cm × 40 cm, but the yield of rice and total N absorption in the two treatments were remarkably higher than those in 50 cm × 50 cm treatment. The amounts of total N uptake by rice were in the range of 112.3-162.7 kg/hm2 in the three transplanting densities. The result showed that about 1/3 of the total N uptake by rice was supplied by application fertilizer and the other 2/3 was obtained from the soil N pool. The ^15N-labelled urea absorbed by rice, residual in soil and lost accounted for 16.3%-26.1%, 17.0%-20.9% and 53.0%-66.7% of the total fertilizer, respectively. A great deal of ^15N-labelled urea was lost during the rice growing season. [Conclusion] Considering the rice yield and environmental protection, the transplanting density of 30 cm×30 cm was recommended in the hilly area of Sichuan basin in the southwest China.展开更多
To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was...To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was determined in an alpine meadow for two months. Two weeks after 15 N application, total recovery of 15 N from NO - 3_ 15 N was 73.5% while it was 78% from NH + 4_ 15 N. More 15 N was recovered in plants than in soil organic matter or in microbial biomass, irrespective of forms of N added. After one month, 70.6% of added NO - 3_ 15 N and 57.4% of NH + 4_ 15 N were recovered in soils and plants. 15 N recovered in soil organic matter decreased greatly while that recovered in plants varied little, irrespective of the form N. Compared with the results of two weeks after 15 N application, more NO - 3_ 15 N than NH + 4_ 15 N was recovered in microbial biomass. Total recovery was 58.4% (six weeks) and 67% (eight weeks) from NO - 3_ 15 N, and 43.1% and 49% from NH + 4_ 15 N, respectively. Both plants and soil microorganism recovered more NO - 3_ 15 N than NH + 4_ 15 N. But plants recovered more 15 N than soil microorganisms. During the whole experiment plants retained more NO - 3_N and 15 N than soil microorganisms while 15 N recovered in inorganic N pool did not exceed 1% due to lower amount of inorganic N. This indicates that plants play more important roles in the retention of deposited N although microbial biomass can be an important sink for deposited N in early days after N application.展开更多
Doris Lessing is a famous British female writer.Her short fiction to room 19 depicts the heroine Susan Rawing's tragic fate.The article makes an analysis on the feminine psychological need in the marriage from fou...Doris Lessing is a famous British female writer.Her short fiction to room 19 depicts the heroine Susan Rawing's tragic fate.The article makes an analysis on the feminine psychological need in the marriage from four aspects:Spiritual Freedom,Financially independent,interpersonal communication,mutual faith.展开更多
An accidental discharge of nitrobenzene happened in November 2005 in the Songhua River,China.The AQUATOX model was modified and adapted to simulate the time-dependent nitrobenzene distribution in this multimedia aquat...An accidental discharge of nitrobenzene happened in November 2005 in the Songhua River,China.The AQUATOX model was modified and adapted to simulate the time-dependent nitrobenzene distribution in this multimedia aquatic system and its potential ecological impacts.Nitrobenzene concentrations in flowing water,sediment,and biota were predicted.Based on the initial concentrations of nitrobenzene observed in the field during the accidental discharge,that is,0.167-1.47 mg/L at different river segments, the predic...展开更多
Reactive astrogliosis occurs after central nervous system(CNS) injuries whereby resident astrocytes form rapid responses along a graded continuum. Following CNS lesions, na?ve astrocytes are converted into reactive...Reactive astrogliosis occurs after central nervous system(CNS) injuries whereby resident astrocytes form rapid responses along a graded continuum. Following CNS lesions, na?ve astrocytes are converted into reactive astrocytes and eventually into scar-forming astrocytes that block axon regeneration and neural repair. It has been known for decades that scarring development and its related extracellular matrix molecules interfere with regeneration of injured axons after CNS injury, but the cellular and molecular mechanisms for controlling astrocytic scar formation and maintenance are not well known. Recent use of various genetic tools has made tremendous progress in better understanding genesis of reactive astrogliosis. Especially, the latest experiments demonstrate environment-dependent plasticity of reactive astrogliosis because reactive astrocytes isolated from injured spinal cord form scarring astrocytes when transplanted into injured spinal cord, but revert in retrograde to naive astrocytes when transplanted into naive spinal cord. The interactions between upregulated type I collagen and its receptor integrin β1 and the N-cadherin-mediated cell adhesion appear to play major roles for local astrogliosis around the lesion. This review centers on the environment-dependent plasticity of reactive astrogliosis after spinal cord injury and its potential as a therapeutic target.展开更多
Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming...Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming.These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineagespecific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells.Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted.展开更多
Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the  ̄(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina f...Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the  ̄(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina field plot experiment. One hundred and thirty-eight kg N/ha, 86 kg N/ha as basal dressing and 52 kgN/ha as top dressing, was applied with band application technique. The experiment was conducted in thesoutheast of China, near Yingtan City, Jianxi Province.Results from is ̄(15)N mass balance study showed that when urea was applied as basal dressing the plantrecovery was 44.0% of the applied N for Theatment T (with application of N, P, K, B and lime). Plantrecoveries were 38.0%-40.5% for Treatments -K, -B, -lime and +RS (without application of K, B or limeas well as with additional rice straw compared with Theatment T), which were not significantly differentfrom Treatment T. In contrast, plant recovery was only 5.1% for Treatment-P (without application of P),indicating that P was the factor limiting N uptake by rape. However, N remaining in 0-0.30 m soil was highup to 71.6% for Theatment -P, while the corresponding data were 33.0%-42.6% for the other treatments.The total recovery of applied N (including plant recovery and N remaining in 0-0.60 m soil) was 91.5% forTreatment T when urea was applied as basal dressing, while almost all the applied N was recovered when ureawas applied as top dressing. It was suggested that N loss was greatly controlled by using band applicationmethod in this experiment.Results from the field plot experiment showed that N supply capacity of this red soil was very low, andthe efficiency of the applied N was quite high, 7.1 kg rape seed was increased by application of one kg N forTreatmentT. Nitrogen and phosphorus were the key factors limiting rape yield, and the yield was very lowwhen neither of them was applied. The yield in TreatmentK was significantly lower than that in TYeatmentT, with the former accounting for 77% of the later.展开更多
Mesenchymal stem cells(MSCs)are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts,adipocytes,or chondrocytes in vitro,and regulatin...Mesenchymal stem cells(MSCs)are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts,adipocytes,or chondrocytes in vitro,and regulating the bone marrow microenvironment and adipose tissue remodeling in vivo.The process of fate determination is initiated by signaling molecules that drive MSCs into a specific lineage.Impairment of MSC fate determination leads to different bone and adipose tissue-related diseases,including aging,osteoporosis,and insulin resistance.Much progress has been made in recent years in discovering small molecules and their underlying mechanisms control the cell fate of MSCs both in vitro and in vivo.In this review,we summarize recent findings in applying small molecules to the trilineage commitment of MSCs,for instance,genistein,medicarpin,and icariin for the osteogenic cell fate commitment;isorhamnetin,risedronate,and arctigenin for pro-adipogenesis;and atractylenolides and dihydroartemisinin for chondrogenic fate determination.We highlight the underlying mechanisms,including direct regulation,epigenetic modification,and post-translational modification of signaling molecules in the AMPK,MAPK,Notch,PI3K/AKT,Hedgehog signaling pathways etc.and discuss the small molecules that are currently being studied in clinical trials.The target-based manipulation of lineage-specific commitment by small molecules offers substantial insights into bone marrow microenvironment regulation,adipose tissue homeostasis,and therapeutic strategies for MSC-related diseases.展开更多
Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the ...Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the development of liposomal drugs. Hence, an overview of currently used bioanalytical methods is imperative to lay the groundwork for the need of developing a bioanalytical method for liposome measurements in vivo. Currently, major analytical methods for nanoliposomes measurement in vivo include fluorescence labeling, radiolabeling, magnetic resonance imaging(MRI), mass spectrometry and computed tomography. In this review, these bioanalytical methods are summarized, and the advantages and disadvantages of each are discussed. We provide insights into the applicability and limitations of these analytical methods in the application of nanoliposomes measurement in vivo, and highlight the recent development of instrumental analysis techniques. The review is devoted to providing a comprehensive overview of the investigation of nanoliposomes design and associated fate in vivo, promoting the development of bioanalytical techniques for nanoliposomes measurement, and understanding the pharmacokinetic behavior, effectiveness and potential toxicity of nanoliposomes in vivo.展开更多
In multicellular organisms, biological activities are regulated by cell signaling. The various signal transduction path- ways regulate cell fate, proliferation, migration, and polarity. Miscoordination of the communic...In multicellular organisms, biological activities are regulated by cell signaling. The various signal transduction path- ways regulate cell fate, proliferation, migration, and polarity. Miscoordination of the communicative signals will lead to disasters like cancer and other fatal diseases. The JAK/STAT signal transduction pathway is one of the pathways, which was first identified in vertebrates and is highly conserved throughout evolution. Studying the JAK/STAT signal transduc- tion pathway in Drosophila provides an excellent opportunity to understand the molecular mechanism of the cell regu- lation during development and tumor formation. In this review, we discuss the general overview of JAK/STAT signaling in Drosophila with respect to its functions in the eye development and stem cell fate determination.展开更多
The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this stu...The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this study,the recovery of a single application of 15N-labeled fertilizer or residues in rice-wheat cropping system was determined,in order to provide theoretical foundation for the nitrogen management in sustainable agricultural production.A continuous trace experiment was conducted for 15N microplots by using randomized block design with four treatments and four replications(T1 = 15N-labeled fertilizer with crop residue incorporation,T2 = 15N-labeled residues,T3 = 14N fertilizer to generate unlabeled crop residue,and T4 = 15Nlabeled fertilizer without crop residue incorporation).Our results showed that,on average,17.17 and 12.01% of crop N was derived from N fertilizer and 15N-labeled residues,respectively during the first growing season,suggesting that approximately 82.83 or 87.99% of crop N was derived directly from soil N pool.There was a larger difference in the 15N recovery pattern in crop when N was applied as fertilizer or residues,i.e.,most of crop N derived from N fertilizer was absorbed in the first growing season(92.04%),and the relevant value was 38.03% when 15N-labeled residues were applied.This implied that most of N fertilizer was recovered in the present cropping season,while a longer residue effect will be found for 15N-labeled residues.Thus,the average recovery of N fertilizer and N residue in the soil after the first growing season was 33.46 and 85.64%,respectively.The recovery of applied N in soil when N was applied as residues was significantly higher than that when N was applied as fertilizer.There was a larger difference in the total 15N recovery in plant and soil when N was applied as fertilizer or residues.By the end of the fifth or sixth cropping season,the total 15N recovery in plant and soil when N was applied as fertilizer or residues were estimated at 64.38 and 79.11%,respectively.On the contrary,there was little difference between the practices of residue incorporation and residue removal following the N fertilizer application.N fertilizer appeared to be more readily available to crops than residue-N,and residue-N replenished soil N pool,especially N in soil organic matter,much more than N fertilizer after six growing seasons.Therefore,residue-N is a better source for sustaining N content of soil organic matter.Thus,one possible management practice is to use both organic and inorganic N sources simultaneously to improve the use efficiency of N while protecting the sustainability of soil.展开更多
Two dominant species of Willow( Salix triandra )and Reed (Phragmites australis) along the Schelde Estuary(in Belgium)were selected in this research. The pigments of higher plant was used as biomarkers, the deco...Two dominant species of Willow( Salix triandra )and Reed (Phragmites australis) along the Schelde Estuary(in Belgium)were selected in this research. The pigments of higher plant was used as biomarkers, the decomposition process of the two species were studied after they fall into the Schelde Estuary. After statistical analysis(Spearman rank order correlation, P <0 05), the results has shown the decomposition dynamics pattern of the pigments, and the willow showed different pattern in comparing with the reed, e.g. Chlorophyll a decomposition dynamics for willow is: y 1=12196 x 2 - 175895 x +1E+06+ k , R 2=0 5706 while for reed is: y 2=-37878 x 2+229782 x +734282+ k , R 2=0 9065 The precise time of the leaf litter spent in the water was also calculated as were less than 24 days, 24-37 days, longer than 37 days(willow)and less than 24 days, longer than 24 days(reed), the leaf litter fate of the two dominant species in the Schelde Estuary was also compared.展开更多
基金supported by the National Key Research and Development Project of China,Nos.2017YFA0104100(to JL),2017YFA0701304(to HX)National Natural Science Foundation of China Nos.81970820(to HX),31930068(to JL)。
文摘The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.
基金This work was supported by the National Natural Science Foundation of China(No.51979255).
文摘The knowledge of the existence,distribution and fate of polycyclic aromatic hydrocarbons(PAHs)and substituted polycyclic aromatic hydrocarbons(SPAHs)in wastewater treatment plants(WWTPs)was vital for reducing their concentrations entering the aquatic environment.The concentrations of 13 SPAHs and 16 PAHs were all determined in a WWTP with styrene butadiene rubber(SBR)in partnership with the moving bed biofilm reactor(MBBR)process.SPAHs presented a higher concentration lever than PAHs in nearly all samples.The total removal efficiencies of PAHs and SPAHs ranged from 64.0%to 71.36%and 78.4%to 79.7%,respectively.The total yearly loads of PAHs(43.0 kg)and SPAHs(73.0 kg)were mainly reduced by the primary and SBR/MBBR biological treatment stages.The tertiary treatment stage had a minor contribution to target compounds removal.According to a synthesis and improvement fate model,we found that the dominant processes changed as the chemical octanol water partition coefficient(K_(ow))increased.But the seasonal variations of experimental removal efficiencies were more obvious than that of predicted data.In the primary sedimentation tank,dissolution in the aqueous phase and sorption to sludge/particulate matter were controlling processes for the removal of PAHs and SPAHs.The sorption to sludge and biodegradation were the principal removal mechanisms during the SBR/MBBR biological treatment process.The contribution of volatilization to removal was always insignificant.Furthermore,the basic physicochemical properties and operating parameters influenced the fate of PAHs and SPAHs in the WWTP.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA28100302)the earmarked fund for China Agriculture Research System (CARS-01-29)+2 种基金the National Key Research and Development Program of China(2017YFD0200104)the Fifth (2019) of ‘Young Talents’ Project of Northeast Agricultural University,Chinathe Open Program of Key Laboratory of Germplasm Enhancement,Physiology and Ecology of Food Crops in Cold Region,Ministry of Education,Northeast Agricultural University (CXSTOP2021009)。
文摘The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.Residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.Furthermore,of the residual N,approximately 5.4%was taken up on average in the following season and 50.2%was lost,but 44.4%remained in the soil.Hence,the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha–1in order to achieve a balance between rice yield and high N fertilizer uptake.
文摘Japanese British writer Kazuo Ishiguro is one of the leading writers in contemporary British literature.He has always been committed to creating works with universal significance.Responsibility and destiny are themes that run through his works.His novel Never Let Me Go tells a story of a group of clones growing up in the Hailsham,who are given the mission to donate organs at birth.So,there is no doubt that they will inevitably end their lives in the process of donating organs to human beings again and again.The tragic life of clones is determined by the motivation of human to create them.
基金Supported by the Financial Breeding Fund for Young Scholars in Sichuan Province(2008QNJJ-016)Financial Fund for Excellent Gene Engineering Papers in Sichuan Province (2010LWJJ-008)~~
文摘[Objective] The aim of this study was investigated the rice yield, nitrogen uptake and ^15-fertilizer fate at different transplanting density to provide scientific ba- sis for improving the yield of rice and applying reasonably fertilizer. [Method] A field experiment was carried out to study the effect of different transplanting density on rice yield, nitrogen (N) absorption, sources of N uptake by rice and the N balance in the plant-soil systems by using ^15-labelled urea. [Result] There were no significant differences in rice yields and total N uptakes by rice between treatments 30 cm × 30 cm and 40 cm × 40 cm, but the yield of rice and total N absorption in the two treatments were remarkably higher than those in 50 cm × 50 cm treatment. The amounts of total N uptake by rice were in the range of 112.3-162.7 kg/hm2 in the three transplanting densities. The result showed that about 1/3 of the total N uptake by rice was supplied by application fertilizer and the other 2/3 was obtained from the soil N pool. The ^15N-labelled urea absorbed by rice, residual in soil and lost accounted for 16.3%-26.1%, 17.0%-20.9% and 53.0%-66.7% of the total fertilizer, respectively. A great deal of ^15N-labelled urea was lost during the rice growing season. [Conclusion] Considering the rice yield and environmental protection, the transplanting density of 30 cm×30 cm was recommended in the hilly area of Sichuan basin in the southwest China.
文摘To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was determined in an alpine meadow for two months. Two weeks after 15 N application, total recovery of 15 N from NO - 3_ 15 N was 73.5% while it was 78% from NH + 4_ 15 N. More 15 N was recovered in plants than in soil organic matter or in microbial biomass, irrespective of forms of N added. After one month, 70.6% of added NO - 3_ 15 N and 57.4% of NH + 4_ 15 N were recovered in soils and plants. 15 N recovered in soil organic matter decreased greatly while that recovered in plants varied little, irrespective of the form N. Compared with the results of two weeks after 15 N application, more NO - 3_ 15 N than NH + 4_ 15 N was recovered in microbial biomass. Total recovery was 58.4% (six weeks) and 67% (eight weeks) from NO - 3_ 15 N, and 43.1% and 49% from NH + 4_ 15 N, respectively. Both plants and soil microorganism recovered more NO - 3_ 15 N than NH + 4_ 15 N. But plants recovered more 15 N than soil microorganisms. During the whole experiment plants retained more NO - 3_N and 15 N than soil microorganisms while 15 N recovered in inorganic N pool did not exceed 1% due to lower amount of inorganic N. This indicates that plants play more important roles in the retention of deposited N although microbial biomass can be an important sink for deposited N in early days after N application.
文摘Doris Lessing is a famous British female writer.Her short fiction to room 19 depicts the heroine Susan Rawing's tragic fate.The article makes an analysis on the feminine psychological need in the marriage from four aspects:Spiritual Freedom,Financially independent,interpersonal communication,mutual faith.
文摘An accidental discharge of nitrobenzene happened in November 2005 in the Songhua River,China.The AQUATOX model was modified and adapted to simulate the time-dependent nitrobenzene distribution in this multimedia aquatic system and its potential ecological impacts.Nitrobenzene concentrations in flowing water,sediment,and biota were predicted.Based on the initial concentrations of nitrobenzene observed in the field during the accidental discharge,that is,0.167-1.47 mg/L at different river segments, the predic...
基金supported by research grants to SL from NIH(1R01NS079432 and 1R01EY024575)Shriners Research Foundation(SHC-86300-PHI,SHC-86200-PHI-16 and SHC-85100)
文摘Reactive astrogliosis occurs after central nervous system(CNS) injuries whereby resident astrocytes form rapid responses along a graded continuum. Following CNS lesions, na?ve astrocytes are converted into reactive astrocytes and eventually into scar-forming astrocytes that block axon regeneration and neural repair. It has been known for decades that scarring development and its related extracellular matrix molecules interfere with regeneration of injured axons after CNS injury, but the cellular and molecular mechanisms for controlling astrocytic scar formation and maintenance are not well known. Recent use of various genetic tools has made tremendous progress in better understanding genesis of reactive astrogliosis. Especially, the latest experiments demonstrate environment-dependent plasticity of reactive astrogliosis because reactive astrocytes isolated from injured spinal cord form scarring astrocytes when transplanted into injured spinal cord, but revert in retrograde to naive astrocytes when transplanted into naive spinal cord. The interactions between upregulated type I collagen and its receptor integrin β1 and the N-cadherin-mediated cell adhesion appear to play major roles for local astrogliosis around the lesion. This review centers on the environment-dependent plasticity of reactive astrogliosis after spinal cord injury and its potential as a therapeutic target.
基金supported by a South Korea Science and Engineering Foundation grant funded by the South Korea government(MEST)(2011-0019243,2011-0019254)a grant from the South Korea Health 21 R and D Project,Ministry of Health and Welfare,South Korea(A120478)a grant from the Korea Health 21 R and D Project,Ministry of Health and Welfare,South Korea(A085136)
文摘Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming.These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineagespecific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells.Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted.
文摘Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the  ̄(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina field plot experiment. One hundred and thirty-eight kg N/ha, 86 kg N/ha as basal dressing and 52 kgN/ha as top dressing, was applied with band application technique. The experiment was conducted in thesoutheast of China, near Yingtan City, Jianxi Province.Results from is ̄(15)N mass balance study showed that when urea was applied as basal dressing the plantrecovery was 44.0% of the applied N for Theatment T (with application of N, P, K, B and lime). Plantrecoveries were 38.0%-40.5% for Treatments -K, -B, -lime and +RS (without application of K, B or limeas well as with additional rice straw compared with Theatment T), which were not significantly differentfrom Treatment T. In contrast, plant recovery was only 5.1% for Treatment-P (without application of P),indicating that P was the factor limiting N uptake by rape. However, N remaining in 0-0.30 m soil was highup to 71.6% for Theatment -P, while the corresponding data were 33.0%-42.6% for the other treatments.The total recovery of applied N (including plant recovery and N remaining in 0-0.60 m soil) was 91.5% forTreatment T when urea was applied as basal dressing, while almost all the applied N was recovered when ureawas applied as top dressing. It was suggested that N loss was greatly controlled by using band applicationmethod in this experiment.Results from the field plot experiment showed that N supply capacity of this red soil was very low, andthe efficiency of the applied N was quite high, 7.1 kg rape seed was increased by application of one kg N forTreatmentT. Nitrogen and phosphorus were the key factors limiting rape yield, and the yield was very lowwhen neither of them was applied. The yield in TreatmentK was significantly lower than that in TYeatmentT, with the former accounting for 77% of the later.
基金Supported by the National Natural Science Foundation of China,No.81573992
文摘Mesenchymal stem cells(MSCs)are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts,adipocytes,or chondrocytes in vitro,and regulating the bone marrow microenvironment and adipose tissue remodeling in vivo.The process of fate determination is initiated by signaling molecules that drive MSCs into a specific lineage.Impairment of MSC fate determination leads to different bone and adipose tissue-related diseases,including aging,osteoporosis,and insulin resistance.Much progress has been made in recent years in discovering small molecules and their underlying mechanisms control the cell fate of MSCs both in vitro and in vivo.In this review,we summarize recent findings in applying small molecules to the trilineage commitment of MSCs,for instance,genistein,medicarpin,and icariin for the osteogenic cell fate commitment;isorhamnetin,risedronate,and arctigenin for pro-adipogenesis;and atractylenolides and dihydroartemisinin for chondrogenic fate determination.We highlight the underlying mechanisms,including direct regulation,epigenetic modification,and post-translational modification of signaling molecules in the AMPK,MAPK,Notch,PI3K/AKT,Hedgehog signaling pathways etc.and discuss the small molecules that are currently being studied in clinical trials.The target-based manipulation of lineage-specific commitment by small molecules offers substantial insights into bone marrow microenvironment regulation,adipose tissue homeostasis,and therapeutic strategies for MSC-related diseases.
基金supported by the National Natural Science Foundation of China (Grant No. 81430087, 81673396, 81603182)
文摘Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the development of liposomal drugs. Hence, an overview of currently used bioanalytical methods is imperative to lay the groundwork for the need of developing a bioanalytical method for liposome measurements in vivo. Currently, major analytical methods for nanoliposomes measurement in vivo include fluorescence labeling, radiolabeling, magnetic resonance imaging(MRI), mass spectrometry and computed tomography. In this review, these bioanalytical methods are summarized, and the advantages and disadvantages of each are discussed. We provide insights into the applicability and limitations of these analytical methods in the application of nanoliposomes measurement in vivo, and highlight the recent development of instrumental analysis techniques. The review is devoted to providing a comprehensive overview of the investigation of nanoliposomes design and associated fate in vivo, promoting the development of bioanalytical techniques for nanoliposomes measurement, and understanding the pharmacokinetic behavior, effectiveness and potential toxicity of nanoliposomes in vivo.
文摘In multicellular organisms, biological activities are regulated by cell signaling. The various signal transduction path- ways regulate cell fate, proliferation, migration, and polarity. Miscoordination of the communicative signals will lead to disasters like cancer and other fatal diseases. The JAK/STAT signal transduction pathway is one of the pathways, which was first identified in vertebrates and is highly conserved throughout evolution. Studying the JAK/STAT signal transduc- tion pathway in Drosophila provides an excellent opportunity to understand the molecular mechanism of the cell regu- lation during development and tumor formation. In this review, we discuss the general overview of JAK/STAT signaling in Drosophila with respect to its functions in the eye development and stem cell fate determination.
文摘The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this study,the recovery of a single application of 15N-labeled fertilizer or residues in rice-wheat cropping system was determined,in order to provide theoretical foundation for the nitrogen management in sustainable agricultural production.A continuous trace experiment was conducted for 15N microplots by using randomized block design with four treatments and four replications(T1 = 15N-labeled fertilizer with crop residue incorporation,T2 = 15N-labeled residues,T3 = 14N fertilizer to generate unlabeled crop residue,and T4 = 15Nlabeled fertilizer without crop residue incorporation).Our results showed that,on average,17.17 and 12.01% of crop N was derived from N fertilizer and 15N-labeled residues,respectively during the first growing season,suggesting that approximately 82.83 or 87.99% of crop N was derived directly from soil N pool.There was a larger difference in the 15N recovery pattern in crop when N was applied as fertilizer or residues,i.e.,most of crop N derived from N fertilizer was absorbed in the first growing season(92.04%),and the relevant value was 38.03% when 15N-labeled residues were applied.This implied that most of N fertilizer was recovered in the present cropping season,while a longer residue effect will be found for 15N-labeled residues.Thus,the average recovery of N fertilizer and N residue in the soil after the first growing season was 33.46 and 85.64%,respectively.The recovery of applied N in soil when N was applied as residues was significantly higher than that when N was applied as fertilizer.There was a larger difference in the total 15N recovery in plant and soil when N was applied as fertilizer or residues.By the end of the fifth or sixth cropping season,the total 15N recovery in plant and soil when N was applied as fertilizer or residues were estimated at 64.38 and 79.11%,respectively.On the contrary,there was little difference between the practices of residue incorporation and residue removal following the N fertilizer application.N fertilizer appeared to be more readily available to crops than residue-N,and residue-N replenished soil N pool,especially N in soil organic matter,much more than N fertilizer after six growing seasons.Therefore,residue-N is a better source for sustaining N content of soil organic matter.Thus,one possible management practice is to use both organic and inorganic N sources simultaneously to improve the use efficiency of N while protecting the sustainability of soil.
文摘Two dominant species of Willow( Salix triandra )and Reed (Phragmites australis) along the Schelde Estuary(in Belgium)were selected in this research. The pigments of higher plant was used as biomarkers, the decomposition process of the two species were studied after they fall into the Schelde Estuary. After statistical analysis(Spearman rank order correlation, P <0 05), the results has shown the decomposition dynamics pattern of the pigments, and the willow showed different pattern in comparing with the reed, e.g. Chlorophyll a decomposition dynamics for willow is: y 1=12196 x 2 - 175895 x +1E+06+ k , R 2=0 5706 while for reed is: y 2=-37878 x 2+229782 x +734282+ k , R 2=0 9065 The precise time of the leaf litter spent in the water was also calculated as were less than 24 days, 24-37 days, longer than 37 days(willow)and less than 24 days, longer than 24 days(reed), the leaf litter fate of the two dominant species in the Schelde Estuary was also compared.