In face of the everlasting battle toward COVID-19 and the rapid evolution of SARS-CoV-2,no specific and effective drugs for treating this disease have been reported until today.Angiotensin-converting enzyme 2(ACE2),a ...In face of the everlasting battle toward COVID-19 and the rapid evolution of SARS-CoV-2,no specific and effective drugs for treating this disease have been reported until today.Angiotensin-converting enzyme 2(ACE2),a receptor of SARS-CoV-2,mediates the virus infection by binding to spike protein.Although ACE2 is expressed in the lung,kidney,and intestine,its expressing levels are rather low,especially in the lung.Considering the great infectivity of COVID-19,we speculate that SARS-CoV-2 may depend on other routes to facilitate its infection.Here,we first discover an interaction between host cell receptor CD147 and SARS-CoV-2 spike protein.The loss of CD147 or blocking CD147 in Vero E6 and BEAS-2B cell lines by anti-CD147 antibody,Meplazumab,inhibits SARSCoV-2 amplification.Expression of human CD147 allows virus entry into non-susceptible BHK-21 cells,which can be neutralized by CD147 extracellular fragment.Viral loads are detectable in the lungs of human CD147(hCD147)mice infected with SARS-CoV-2,but not in those of virus-infected wild type mice.Interestingly,virions are observed in lymphocytes of lung tissue from a COVID-19 patient.Human T cells with a property of ACE2 natural deficiency can be infected with SARS-CoV-2 pseudovirus in a dosedependent manner,which is specifically inhibited by Meplazumab.Furthermore,CD147 mediates virus entering host cells by endocytosis.Together,our study reveals a novel virus entry route,CD147-spike protein,which provides an important target for developing specific and effective drug against COVID-19.展开更多
AIM To investigate whether patients with refractory epilepsy and healthy infants differ in gut microbiota(GM),and how ketogenic diet(KD) alters GM.METHODS A total of 14 epileptic and 30 healthy infants were recruited ...AIM To investigate whether patients with refractory epilepsy and healthy infants differ in gut microbiota(GM),and how ketogenic diet(KD) alters GM.METHODS A total of 14 epileptic and 30 healthy infants were recruited and seizure frequencies were recorded. Stool samples were collected for 16 S r DNA sequencing using the Illumina Miseq platform. The composition of GM in each sample was analyzed with MOTHUR,and intergroup comparison was conducted by R software.RESULTS After being on KD treatment for a week,64% of epileptic infants showed an obvious improvement,with a 50% decrease in seizure frequency. GM structure in epileptic infants(P1 group) differed dramatically from that in healthy infants(Health group). Proteobacteria,which had accumulated significantly in the P1 group,decreased dramatically after KD treatment(P2 group). Cronobacter predominated in the P1 group and remained at a low level both in the Health and P2 groups. Bacteroides increased significantly in the P2 group,in which Prevotella and Bifidobacterium also grew in numbers and kept increasing.CONCLUSION GM pattern in healthy infants differed dramatically from that of the epileptic group. KD could significantly modify symptoms of epilepsy and reshape the GM of epileptic infants.展开更多
Dear Editor,The tea tree Camellia sinensis,a member of the genus Camellia in the Theaceae family,includes two major cultivated varieties,C.sinensis var.assamica(CSA\Assam type)and C.sinensis var.sinensis(CSS;Chinese t...Dear Editor,The tea tree Camellia sinensis,a member of the genus Camellia in the Theaceae family,includes two major cultivated varieties,C.sinensis var.assamica(CSA\Assam type)and C.sinensis var.sinensis(CSS;Chinese type)(Ming and Bartholomew,2007).Due to the high economic importance of the tea tree,considerable efforts have been made to explore genetic basis of the biosynthesis of natural metabolites that determine health benefits and diverse tea flavors(Shi et al.,2011;Li et al.,2011;Li et al.,2015;Xia et aL,2017;Liu et al.,2019).展开更多
Nitrogen (N) leaching in vegetable fields from December 2002 to May 2003 with equal dressings of total N for asequential rotation of Chinese flat cabbage (Brassica chinensis L. var. rosularis) and lettuce (Lactuca sat...Nitrogen (N) leaching in vegetable fields from December 2002 to May 2003 with equal dressings of total N for asequential rotation of Chinese flat cabbage (Brassica chinensis L. var. rosularis) and lettuce (Lactuca sativa L.) in asuburban major vegetable production base of Shanghai were examined using the lysimeter method to provide a scientificbasis for rational utilization of nitrogen fertilizers so as to prevent nitrogen pollution of water resources. Results showedthat leached N consisted mainly of nitrate N, which accounted for up to more than 90% of the total N loss and couldcontribute to groundwater pollution. Data also showed that by partly substituting chemical N (30%) in a basal dressingwith equivalent N of refined organic fertilizer in the Chinese flat cabbage field, 64.5% of the leached nitrate N was reduced,while in the lettuce (Lactuca sativa L.) field, substituting 1/2 of the chemical N in a basal dressing and 1/3 of the chemicalN in a top dressing with equivalent N of refined organic fertilizers reduced 46.6% of the leached nitrate N. In the two-year sequential rotation system of Chinese flat cabbage and lettuce, nitrate-N leaching in the treatment with the highestamount of chemical fertilizer was up to 46.55 kg ha-1, while treatment plots with the highest amount of organic fertilizerhad only 17.58 kg ha-1. Thus, partly substituting refined organic fertilizer for chemical nitrogen in the first two seasonshas a great advantage of reducing nitrate-N leaching.展开更多
INTRODUCTIONIn China ,the incidence and mortality of gastric cancer rank the second among all cancers. Recent development of cancer [1-20].The aim of this study was investigat the insight of apoptosis and bcl-2, p53 a...INTRODUCTIONIn China ,the incidence and mortality of gastric cancer rank the second among all cancers. Recent development of cancer [1-20].The aim of this study was investigat the insight of apoptosis and bcl-2, p53 and C-myc protein expression in the development of gastric cancer .展开更多
The rubber tree,Hevea brasiliensis,produces natural rubber that serves as an essential industrial raw material.Here,we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-...The rubber tree,Hevea brasiliensis,produces natural rubber that serves as an essential industrial raw material.Here,we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-time sequencing(SMRT)and Hi-C technologies to anchor the～1.47-Gb genome assembly into 18 pseudochromosomes.The chromosome-based genome analysis enabled us to establish a model of spurge chromosome evolution,since the common paleopolyploid event occurred before the split of Hevea and Manihot.We show recent and rapid bursts of the three Hevea-specific LTR-retrotransposon families during the last 10 million years,leading to the massive expansion by～65.88%(～970 Mbp)of the whole rubber tree genome since the divergence from Manihot.We identify large-scale expansion of genes associated with whole rubber biosynthesis processes,such as basal metabolic processes,ethylene biosynthesis,and the activation of polysaccharide and glycoprotein lectin,which are important properties for latex production.A map of genomic variation between the cultivated and wild rubber trees was obtained,which contains～15.7 million high-quality single-nucleotide polymorphisms.We identified hundreds of candidate domestication genes with drastically lowered genomic diversity in the cultivated but not wild rubber trees despite a relatively short domestication history of rubber tree,some of which are involved in rubber biosynthesis.This genome assembly represents key resources for future rubber tree research and breeding,providing novel targets for improving plant biotic and abiotic tolerance and rubber production.展开更多
Background:The current World Health Organization(WHO) classification of nasopharyngeal carcinoma(NPC) con?veys little prognostic information.This study aimed to propose an NPC histopathologic classification that can p...Background:The current World Health Organization(WHO) classification of nasopharyngeal carcinoma(NPC) con?veys little prognostic information.This study aimed to propose an NPC histopathologic classification that can poten?tially be used to predict prognosis and treatment response.Methods:We initially developed a histopathologic classification based on the morphologic traits and cell differentia?tion of tumors of 2716 NPC patients who were identified at Sun Yat?sen University Cancer Center(SYSUCC)(training cohort).Then,the proposed classification was applied to 1702 patients(retrospective validation cohort) from hospitals outside SYSUCC and 1613 patients(prospective validation cohort) from SYSUCC.The efficacy of radiochemotherapy and radiotherapy modalities was compared between the proposed subtypes.We used Cox proportional hazards models to estimate hazard ratios(HRs) with 95% confidence intervals(CI) for overall survival(OS).Results:The 5?year OS rates for all NPC patients who were diagnosed with epithelial carcinoma(EC;3708 patients),mixed sarcomatoid?epithelial carcinoma(MSEC;1247 patients),sarcomatoid carcinoma(SC;823 patients),and squamous cell carcinoma(SCC;253 patients) were 79.4%,70.5%,59.6%,and 42.6%,respectively(P < 0.001).In mul?tivariate models,patients with MSEC had a shorter OS than patients with EC(HR = 1.44,95% CI = 1.27–1.62),SC(HR = 2.00,95% CI = 1.76–2.28),or SCC(HR = 4.23,95% CI = 3.34–5.38).Radiochemotherapy significantly improved survival compared with radiotherapy alone for patients with EC(HR 49–0.75),and possibly for those with SCC(HR = 0.67,95% CI = 0.56–0.80),MSEC(HR = 0.58,95% CI = 0..74–1.28).= 0.63;95% CI = 0.40–0.98),but not for patients with SC(HR = 0.97,95% CI = 0Conclusions:The proposed classification offers more information for the prediction of NPC prognosis compared with the WHO classification and might be a valuable tool to guide treatment decisions for subtypes that are associ?ated with a poor prognosis.展开更多
In 2010, Chinese maize yields increased from 961.5 kg ha-1 in 1949 to 5 453.8 kg ha-L This increase is the result of genetic improvements, an increase in nitrogen application, and refinement of planting densities. The...In 2010, Chinese maize yields increased from 961.5 kg ha-1 in 1949 to 5 453.8 kg ha-L This increase is the result of genetic improvements, an increase in nitrogen application, and refinement of planting densities. The objective of this study was to provide a theoretical basis for maize production research by analyzing the maize yield gain characteristics. Six varieties of maize were selected for the study; each selection is representative of a typical or commonly used maize variety from a specific decade, beginning from the 1950s and continuing through each decade into the 2000s. The selections and their corresponding decade were as follows： Baihe, 1950s; Jidan 101, 1960s; Zhongdan 2, 1970s; Yedan 13, 1980s; Zhengdan 958, 1990s; and Xianyu 335, 2000s. Each variety was planted under four different densities （37 500, 52 500, 67 500, and 82 500 plants ha-0 and four different nitrogen applications （0, 150, 225, and 300 kg ha-1 to study the effects on yield gain characteristics. The obtained results demonstrated that there was a maize yield increase of 123.19% between the 1950s variety and the 2000s variety. Modern Chinese maize varieties had a higher yield advantage. They also displayed the additional potential to acquire higher yield under increased planting densities and nitrogen applications. At the present cultivation levels （planting at 67 500 plants ha-~ with 225 kg ha-1 nitrogen application）, the contribution types and corresponding yield increase percentages were as follows： genetic improvement, 45.37%; agronomic-management improvement, 30.94%; and genotype× agronomicmanagement interaction, 23.69%. At high-yielding cultivation levels （planting at 82 500 plants ha-1 with 300 kg ha-1 nitrogen application）, the contribution types and corresponding yield increase percentages were as follows： genetic improvement, 31.30%; agronomic-management improvement, 36.23%; and genotype × agronomic-management interaction, 32.47%. The contribution of agronomic-management and genotype ×agronomic-management 展开更多
The effects of rapid cold hardening （RCH） on the cold tolerance of the last instar larvae of Chilo suppressalis （Walker） were evaluated for the first time. The discriminating temperature, induction, detection, dur...The effects of rapid cold hardening （RCH） on the cold tolerance of the last instar larvae of Chilo suppressalis （Walker） were evaluated for the first time. The discriminating temperature, induction, detection, duration and extent of RCH of the larvae in the laboratory were tested, and the supercooling points （SCPs） and the contents of water and lipid of the larvae after RCH treatment were determined, respectively. The results showed that the discriminating temperature of the larvae was about -21℃. Mean survival rates of the larvae which exposed to either 0 or 5℃ for 2 and 4 h before exposure to the discriminating temperature for 2 h were significantly higher than those of the control groups （P 〈 0.05）. Moreover, the highest survival rate appeared in the larvae after 0℃ for 4 h treatment. The protection against low temperature gained by RCH at 0℃ for 4 h was rapidly lost on return to 28℃. Mean survival rates of RCH larvae were significantly higher than those of non-acclimated （NACC） larvae and acclimation （ACC） larvae when they were exposed to the discriminating temperature for 2 or 4 h （P〈 0.05）. Moreover, the rates of NACC, ACC, RCH and ACC ＋ RCH larvae from 2 to 6 h to the discriminating temperature resulted in a significant decline. The values of SCPs and the contents of lipid of the larvae which exposed to either 0 or 5℃ for 2 and 4 h showed no significant difference at 0.05 level compared to those of the control groups. But the contents of water in the larvae were obviously decreased. Therefore, it could be concluded that RCH could enhance cold tolerance and affect partly physiological and biochemical components of the larvae of C. suppressalis, but the underlying mechanisms needs to be further explored.展开更多
Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and tot...Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and total nitrogen （TN） in black soil beach （BSB）. We measured SOC and TN in severely degraded and non-degraded grasslands to calculate differences in carbon and nitrogen storage, and field survey results were extrapolated to the entire headwaters area of the Qinghai-Tibetan Plateau （36.3xlos krn~） to determine SOC and TN losses from these grasslands. We also evaluated changes in SOC and TN in severely degraded grasslands that were artificially re-vegetated five, seven and nine years ago. Totally 92.43 Tg C and 7.08 Tg N were lost from the BSB in the headwater area, which was approximately 50% of the original C and N soil pools. Re-vegetation of the degraded grasslands in the headwater area would result in a gain of 32.71 Tg C in the soil after five years, a loss of 5.5a Tg C after seven years and an increase of 44.15 Tg C after nine years. The TN increased by 53.09% and 59.98% after five and nine years, respectively, while it decreased by 4.92% after seven years of re-vegetation. The results indicate that C and N stocks followed a ＂V＂ shaped pattern with re- vegetation time. Understanding plant-soil interactions during succession of artificially planting grassland ecosystems is essential for developing scientifically sound management strategies for the effectively re-vegetated BSB.展开更多
基金supported by the National Science and Technology Major Project of China(2019ZX09732-001)the Key R&D Plan Projects in Shaanxi Province(2020ZDXM2-SF-01)Young Talent fund of the University Association for Science and Technology in Shaanxi,China(20200304).
文摘In face of the everlasting battle toward COVID-19 and the rapid evolution of SARS-CoV-2,no specific and effective drugs for treating this disease have been reported until today.Angiotensin-converting enzyme 2(ACE2),a receptor of SARS-CoV-2,mediates the virus infection by binding to spike protein.Although ACE2 is expressed in the lung,kidney,and intestine,its expressing levels are rather low,especially in the lung.Considering the great infectivity of COVID-19,we speculate that SARS-CoV-2 may depend on other routes to facilitate its infection.Here,we first discover an interaction between host cell receptor CD147 and SARS-CoV-2 spike protein.The loss of CD147 or blocking CD147 in Vero E6 and BEAS-2B cell lines by anti-CD147 antibody,Meplazumab,inhibits SARSCoV-2 amplification.Expression of human CD147 allows virus entry into non-susceptible BHK-21 cells,which can be neutralized by CD147 extracellular fragment.Viral loads are detectable in the lungs of human CD147(hCD147)mice infected with SARS-CoV-2,but not in those of virus-infected wild type mice.Interestingly,virions are observed in lymphocytes of lung tissue from a COVID-19 patient.Human T cells with a property of ACE2 natural deficiency can be infected with SARS-CoV-2 pseudovirus in a dosedependent manner,which is specifically inhibited by Meplazumab.Furthermore,CD147 mediates virus entering host cells by endocytosis.Together,our study reveals a novel virus entry route,CD147-spike protein,which provides an important target for developing specific and effective drug against COVID-19.
基金Supported by the Innovation Fund of Science and Technology Commission of Shenzhen Municipality,China,No.JCYJ-2015-0403100317071
文摘AIM To investigate whether patients with refractory epilepsy and healthy infants differ in gut microbiota(GM),and how ketogenic diet(KD) alters GM.METHODS A total of 14 epileptic and 30 healthy infants were recruited and seizure frequencies were recorded. Stool samples were collected for 16 S r DNA sequencing using the Illumina Miseq platform. The composition of GM in each sample was analyzed with MOTHUR,and intergroup comparison was conducted by R software.RESULTS After being on KD treatment for a week,64% of epileptic infants showed an obvious improvement,with a 50% decrease in seizure frequency. GM structure in epileptic infants(P1 group) differed dramatically from that in healthy infants(Health group). Proteobacteria,which had accumulated significantly in the P1 group,decreased dramatically after KD treatment(P2 group). Cronobacter predominated in the P1 group and remained at a low level both in the Health and P2 groups. Bacteroides increased significantly in the P2 group,in which Prevotella and Bifidobacterium also grew in numbers and kept increasing.CONCLUSION GM pattern in healthy infants differed dramatically from that of the epileptic group. KD could significantly modify symptoms of epilepsy and reshape the GM of epileptic infants.
基金This study was supported by a startup grant from the South China Agricultural University and Yunnan Innovation Team Project(to L.-Z.G.).E.E.E.is an investigator of the Howard Hughes Medical Institute.
文摘Dear Editor,The tea tree Camellia sinensis,a member of the genus Camellia in the Theaceae family,includes two major cultivated varieties,C.sinensis var.assamica(CSA\Assam type)and C.sinensis var.sinensis(CSS;Chinese type)(Ming and Bartholomew,2007).Due to the high economic importance of the tea tree,considerable efforts have been made to explore genetic basis of the biosynthesis of natural metabolites that determine health benefits and diverse tea flavors(Shi et al.,2011;Li et al.,2011;Li et al.,2015;Xia et aL,2017;Liu et al.,2019).
基金the National Natural Science Foundation of China (No. 20337010).
文摘Nitrogen (N) leaching in vegetable fields from December 2002 to May 2003 with equal dressings of total N for asequential rotation of Chinese flat cabbage (Brassica chinensis L. var. rosularis) and lettuce (Lactuca sativa L.) in asuburban major vegetable production base of Shanghai were examined using the lysimeter method to provide a scientificbasis for rational utilization of nitrogen fertilizers so as to prevent nitrogen pollution of water resources. Results showedthat leached N consisted mainly of nitrate N, which accounted for up to more than 90% of the total N loss and couldcontribute to groundwater pollution. Data also showed that by partly substituting chemical N (30%) in a basal dressingwith equivalent N of refined organic fertilizer in the Chinese flat cabbage field, 64.5% of the leached nitrate N was reduced,while in the lettuce (Lactuca sativa L.) field, substituting 1/2 of the chemical N in a basal dressing and 1/3 of the chemicalN in a top dressing with equivalent N of refined organic fertilizers reduced 46.6% of the leached nitrate N. In the two-year sequential rotation system of Chinese flat cabbage and lettuce, nitrate-N leaching in the treatment with the highestamount of chemical fertilizer was up to 46.55 kg ha-1, while treatment plots with the highest amount of organic fertilizerhad only 17.58 kg ha-1. Thus, partly substituting refined organic fertilizer for chemical nitrogen in the first two seasonshas a great advantage of reducing nitrate-N leaching.
文摘INTRODUCTIONIn China ,the incidence and mortality of gastric cancer rank the second among all cancers. Recent development of cancer [1-20].The aim of this study was investigat the insight of apoptosis and bcl-2, p53 and C-myc protein expression in the development of gastric cancer .
基金supported by Yunnan Innovation Team Project and the start-up grant from South China Agricultural University(to L.G.).
文摘The rubber tree,Hevea brasiliensis,produces natural rubber that serves as an essential industrial raw material.Here,we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-time sequencing(SMRT)and Hi-C technologies to anchor the～1.47-Gb genome assembly into 18 pseudochromosomes.The chromosome-based genome analysis enabled us to establish a model of spurge chromosome evolution,since the common paleopolyploid event occurred before the split of Hevea and Manihot.We show recent and rapid bursts of the three Hevea-specific LTR-retrotransposon families during the last 10 million years,leading to the massive expansion by～65.88%(～970 Mbp)of the whole rubber tree genome since the divergence from Manihot.We identify large-scale expansion of genes associated with whole rubber biosynthesis processes,such as basal metabolic processes,ethylene biosynthesis,and the activation of polysaccharide and glycoprotein lectin,which are important properties for latex production.A map of genomic variation between the cultivated and wild rubber trees was obtained,which contains～15.7 million high-quality single-nucleotide polymorphisms.We identified hundreds of candidate domestication genes with drastically lowered genomic diversity in the cultivated but not wild rubber trees despite a relatively short domestication history of rubber tree,some of which are involved in rubber biosynthesis.This genome assembly represents key resources for future rubber tree research and breeding,providing novel targets for improving plant biotic and abiotic tolerance and rubber production.
基金supported by grants from the National High Technology Research and Development Program of China(863 Program)(No.2012AA02A501)the Chinese State Key Basic Research Project(No.2011CB504805)the National Natural Science Foundation of China(No.81272952 and No.81472522)
文摘Background:The current World Health Organization(WHO) classification of nasopharyngeal carcinoma(NPC) con?veys little prognostic information.This study aimed to propose an NPC histopathologic classification that can poten?tially be used to predict prognosis and treatment response.Methods:We initially developed a histopathologic classification based on the morphologic traits and cell differentia?tion of tumors of 2716 NPC patients who were identified at Sun Yat?sen University Cancer Center(SYSUCC)(training cohort).Then,the proposed classification was applied to 1702 patients(retrospective validation cohort) from hospitals outside SYSUCC and 1613 patients(prospective validation cohort) from SYSUCC.The efficacy of radiochemotherapy and radiotherapy modalities was compared between the proposed subtypes.We used Cox proportional hazards models to estimate hazard ratios(HRs) with 95% confidence intervals(CI) for overall survival(OS).Results:The 5?year OS rates for all NPC patients who were diagnosed with epithelial carcinoma(EC;3708 patients),mixed sarcomatoid?epithelial carcinoma(MSEC;1247 patients),sarcomatoid carcinoma(SC;823 patients),and squamous cell carcinoma(SCC;253 patients) were 79.4%,70.5%,59.6%,and 42.6%,respectively(P < 0.001).In mul?tivariate models,patients with MSEC had a shorter OS than patients with EC(HR = 1.44,95% CI = 1.27–1.62),SC(HR = 2.00,95% CI = 1.76–2.28),or SCC(HR = 4.23,95% CI = 3.34–5.38).Radiochemotherapy significantly improved survival compared with radiotherapy alone for patients with EC(HR 49–0.75),and possibly for those with SCC(HR = 0.67,95% CI = 0.56–0.80),MSEC(HR = 0.58,95% CI = 0..74–1.28).= 0.63;95% CI = 0.40–0.98),but not for patients with SC(HR = 0.97,95% CI = 0Conclusions:The proposed classification offers more information for the prediction of NPC prognosis compared with the WHO classification and might be a valuable tool to guide treatment decisions for subtypes that are associ?ated with a poor prognosis.
基金supported by the National Basic Research Program of China (2009CB118605)
文摘In 2010, Chinese maize yields increased from 961.5 kg ha-1 in 1949 to 5 453.8 kg ha-L This increase is the result of genetic improvements, an increase in nitrogen application, and refinement of planting densities. The objective of this study was to provide a theoretical basis for maize production research by analyzing the maize yield gain characteristics. Six varieties of maize were selected for the study; each selection is representative of a typical or commonly used maize variety from a specific decade, beginning from the 1950s and continuing through each decade into the 2000s. The selections and their corresponding decade were as follows： Baihe, 1950s; Jidan 101, 1960s; Zhongdan 2, 1970s; Yedan 13, 1980s; Zhengdan 958, 1990s; and Xianyu 335, 2000s. Each variety was planted under four different densities （37 500, 52 500, 67 500, and 82 500 plants ha-0 and four different nitrogen applications （0, 150, 225, and 300 kg ha-1 to study the effects on yield gain characteristics. The obtained results demonstrated that there was a maize yield increase of 123.19% between the 1950s variety and the 2000s variety. Modern Chinese maize varieties had a higher yield advantage. They also displayed the additional potential to acquire higher yield under increased planting densities and nitrogen applications. At the present cultivation levels （planting at 67 500 plants ha-~ with 225 kg ha-1 nitrogen application）, the contribution types and corresponding yield increase percentages were as follows： genetic improvement, 45.37%; agronomic-management improvement, 30.94%; and genotype× agronomicmanagement interaction, 23.69%. At high-yielding cultivation levels （planting at 82 500 plants ha-1 with 300 kg ha-1 nitrogen application）, the contribution types and corresponding yield increase percentages were as follows： genetic improvement, 31.30%; agronomic-management improvement, 36.23%; and genotype × agronomic-management interaction, 32.47%. The contribution of agronomic-management and genotype ×agronomic-management
文摘The effects of rapid cold hardening （RCH） on the cold tolerance of the last instar larvae of Chilo suppressalis （Walker） were evaluated for the first time. The discriminating temperature, induction, detection, duration and extent of RCH of the larvae in the laboratory were tested, and the supercooling points （SCPs） and the contents of water and lipid of the larvae after RCH treatment were determined, respectively. The results showed that the discriminating temperature of the larvae was about -21℃. Mean survival rates of the larvae which exposed to either 0 or 5℃ for 2 and 4 h before exposure to the discriminating temperature for 2 h were significantly higher than those of the control groups （P 〈 0.05）. Moreover, the highest survival rate appeared in the larvae after 0℃ for 4 h treatment. The protection against low temperature gained by RCH at 0℃ for 4 h was rapidly lost on return to 28℃. Mean survival rates of RCH larvae were significantly higher than those of non-acclimated （NACC） larvae and acclimation （ACC） larvae when they were exposed to the discriminating temperature for 2 or 4 h （P〈 0.05）. Moreover, the rates of NACC, ACC, RCH and ACC ＋ RCH larvae from 2 to 6 h to the discriminating temperature resulted in a significant decline. The values of SCPs and the contents of lipid of the larvae which exposed to either 0 or 5℃ for 2 and 4 h showed no significant difference at 0.05 level compared to those of the control groups. But the contents of water in the larvae were obviously decreased. Therefore, it could be concluded that RCH could enhance cold tolerance and affect partly physiological and biochemical components of the larvae of C. suppressalis, but the underlying mechanisms needs to be further explored.
基金financially supported by the grants from the Ministry of Science and Technology,China (Grant No. 2012BAC01B02)the Ministry of Environmental Protection,China (Grant No. 201209033)
文摘Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and total nitrogen （TN） in black soil beach （BSB）. We measured SOC and TN in severely degraded and non-degraded grasslands to calculate differences in carbon and nitrogen storage, and field survey results were extrapolated to the entire headwaters area of the Qinghai-Tibetan Plateau （36.3xlos krn~） to determine SOC and TN losses from these grasslands. We also evaluated changes in SOC and TN in severely degraded grasslands that were artificially re-vegetated five, seven and nine years ago. Totally 92.43 Tg C and 7.08 Tg N were lost from the BSB in the headwater area, which was approximately 50% of the original C and N soil pools. Re-vegetation of the degraded grasslands in the headwater area would result in a gain of 32.71 Tg C in the soil after five years, a loss of 5.5a Tg C after seven years and an increase of 44.15 Tg C after nine years. The TN increased by 53.09% and 59.98% after five and nine years, respectively, while it decreased by 4.92% after seven years of re-vegetation. The results indicate that C and N stocks followed a ＂V＂ shaped pattern with re- vegetation time. Understanding plant-soil interactions during succession of artificially planting grassland ecosystems is essential for developing scientifically sound management strategies for the effectively re-vegetated BSB.
