Objective To investigate whether chronic constriction injury(CCI)of the sciatic nerve of rats could produce alterations in the phosphorylation of cyclic AMP response element binding(CREB)protein in dorsal root ganglia...Objective To investigate whether chronic constriction injury(CCI)of the sciatic nerve of rats could produce alterations in the phosphorylation of cyclic AMP response element binding(CREB)protein in dorsal root ganglia(DRG)and superficial dorsal horn neurons of the spinal cord.Methods Chronic constriction injury(CCI)of the sciatic nerve was employed as a model of neuropathic pain.Thirty-two Sprague-Dawley rats were randomly divided into Na⒍ve,Sham,CCI2w(received CCI for2weeks)and CCI4w(received CCI for4weeks)groups.Hind pawwithdrawal threshold to mechanical stimuli and withdrawal latency to thermal stimuli were used to determine the mechanical and thermal hyperalgesia.Then all the rats were deeply anesthetized and perfused intracardially with paraformaldehyde.The fixed L 4-5 spinal cord and the L 5 DRG ipsilateral to CCI were harvested for fixation.The pCREB-immunoreactive(pCREB-IR)cells in both DRG and superficial dorsal horn neurons were quantified for analysis using immunohistochemistry methods.Results On the14th day after sciatic nerve injury,all the rats exhibited significant mechanical and thermal hyperalgesia.The mechanical withdrawal thresholds to von Frey filament from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01);Thermal withdwal latencies from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01).Some rats from Sham group also showed mechanical hyperalgesia compared to both baseline values and those of Na⒍ve group(P<0.01).28days after CCI,both mechanical and thermal hypersensitivity were significantly alleviated,with no statistical significance compared to those of Sham group.On the14th day after CCI,the number of pCREB-IR cells significantly increased in ipsilateral L 5 DRGs and superficial dorsal horns(P<0.01)compared to Sham group.The number of phosphorylated CREB-IR cells in the ipsilateral DRGs from Sham group also increased compared to that of Naive rats(P<0.05).There were no significant statistical differences of numbers of CREB-IR neuron between Sham group and CCI4wgroup.Conclusion CCI increases CREB phosphorylation both in DRG and superficial dorsal horn neurons of the lumbar spinal cord,and may be one of the key molecular mechanisms of central and peripheral sensitization following peripheral nerve injury.展开更多
Ever increasing pressures on tropical forests worldwide due to anthropogenic disturbances have greatly affected both above-and belowground functioning of these forests.While fine roots play major ecological roles in f...Ever increasing pressures on tropical forests worldwide due to anthropogenic disturbances have greatly affected both above-and belowground functioning of these forests.While fine roots play major ecological roles in forests through assisting in nutrient and water uptake and returning elements to the soil environment,coarse roots play an important role in C sequestration.We studied changes in fine and coarse root biomass,production,turnover and carbon and nitrogen return to the soil in two regenerating forest stands(RFs)following stonemining that were 5 years(RF-5)and 15 years(RF-15)post-disturbance compared with a natural forest stand(NF)in Mizoram,North-east India.Fine(<2mm)and coarse root(2-10 mm)biomass differed significantly among the forest stands and ranged from239(RF-5)to 415(NF)and 230(RF-5)to 436(NF)g m 2,respectively.Total root(fine+coarse)biomass increased during stand development but the proportion of very fine root(<0.5 mm)to total root production decreased.Fine root biomass decreased with increasing soil depth.Fine and total root biomass showed strong seasonal correlations with soil moisture,more so than for rainfall and temperature,whereas these relationships were less clear for the coarse root biomass.The amount of N(25-55 kg ha-1)and C(1.9-3.6t ha-1)stored in root biomass increased with stand age with a corresponding increase in production and turnover of C and N to the soil.Disturbance to these tropical forests negatively affected root dynamics,influenced their spatiotemporal patterns,and reduced the production,amount and availability of nutrients returned to the soil along with a strong reduction in the root biomass carbon pool and sequestration in carbon residence time.We observed that root growth,especially fine roots,is dependent on abiotic variables,and plays a significant role in early stages of secondary succession by adding organic matter and nutrients through high turnover rates in these forests.展开更多
Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize （Zea mays L., cv. Zhengdan 958） were grown in hydroponics with the...Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize （Zea mays L., cv. Zhengdan 958） were grown in hydroponics with the control （4 mmol L-1） or low-nitrogen （40 μmol L-1） for 12 d, supplied as nitrate. Low nitrogen enhanced root elongation rate by 4.1-fold, accompanied by increases in cell production rate by 2.2-fold, maximal elemental elongation rate （by 2.5-fold）, the length of elongation zone （by 1.5-fold）, and ifnal cell length by 1.8-fold. On low nitrogen, the higher cell production rate resulted from a higher cell division rate and in fact the number of dividing cells was reduced. Consequently, the residence time of a cell in the division zone tended to be shorter under low nitrogen. In addition, low nitrogen increased root diameter, an increase that occurred speciifcally in the cortex and was accompanied by an increase in cell number. It is concluded that roots elongates in response to low-nitrogen stress by accelerating cell production and expansion.展开更多
[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine...[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials, to determine the root diameter （D）, root length （L）, specific root length （SRL） and contents of major nutrient elements N, P, K, Ca, Mg and C of fine roots （level 1 -5）, study the morphological characteristics and major nutrient element content and investigate the correlation. [ Result] The results showed that morphological differences of fine roots （ level 1 - 5 ） of Eucalyptus grandis plantation were great with the increase of root order, to be specific, D and L increased and SRL decreased with the increasing root order; SRL, L and D of 3-year-old Eucalyptus grauclis plantation were greater than those of 2-year-old Euca/yptus grand/s plantation. Contents of N, Ca, Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order： N and Mg contents were reduced, while Ca and C contents were enhanced; P and K contents varied with different forest ages; both 2-year-old and 3-year- old Eucalyptus grandis showed an order of C 〉 K 〉 Ca （Mg） 〉 N. Major nutrient element content and morphological characteristics of Eucalyptus grand/s fine roots （level 1 -5 ） were extremely significantly correlated （P 〈0.01 ）, SRL, L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grand/s. Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age, and the nutrient cycling and energy flow patterns also changed; major nutrient dements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order, therefore N fertilizer could be applied to improve the growth of fine roots. [ Condusion] This study laid the foundation for understanding the fine root morphology and nutrient variation pattern of Eucalyptus grandis plantation and enriching the response and adaptation mechanism theory of roots to environment, pos- sessing important reference significance for the sustainable development of Eucalyptus grand/s plantation.展开更多
文摘Objective To investigate whether chronic constriction injury(CCI)of the sciatic nerve of rats could produce alterations in the phosphorylation of cyclic AMP response element binding(CREB)protein in dorsal root ganglia(DRG)and superficial dorsal horn neurons of the spinal cord.Methods Chronic constriction injury(CCI)of the sciatic nerve was employed as a model of neuropathic pain.Thirty-two Sprague-Dawley rats were randomly divided into Na⒍ve,Sham,CCI2w(received CCI for2weeks)and CCI4w(received CCI for4weeks)groups.Hind pawwithdrawal threshold to mechanical stimuli and withdrawal latency to thermal stimuli were used to determine the mechanical and thermal hyperalgesia.Then all the rats were deeply anesthetized and perfused intracardially with paraformaldehyde.The fixed L 4-5 spinal cord and the L 5 DRG ipsilateral to CCI were harvested for fixation.The pCREB-immunoreactive(pCREB-IR)cells in both DRG and superficial dorsal horn neurons were quantified for analysis using immunohistochemistry methods.Results On the14th day after sciatic nerve injury,all the rats exhibited significant mechanical and thermal hyperalgesia.The mechanical withdrawal thresholds to von Frey filament from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01);Thermal withdwal latencies from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01).Some rats from Sham group also showed mechanical hyperalgesia compared to both baseline values and those of Na⒍ve group(P<0.01).28days after CCI,both mechanical and thermal hypersensitivity were significantly alleviated,with no statistical significance compared to those of Sham group.On the14th day after CCI,the number of pCREB-IR cells significantly increased in ipsilateral L 5 DRGs and superficial dorsal horns(P<0.01)compared to Sham group.The number of phosphorylated CREB-IR cells in the ipsilateral DRGs from Sham group also increased compared to that of Naive rats(P<0.05).There were no significant statistical differences of numbers of CREB-IR neuron between Sham group and CCI4wgroup.Conclusion CCI increases CREB phosphorylation both in DRG and superficial dorsal horn neurons of the lumbar spinal cord,and may be one of the key molecular mechanisms of central and peripheral sensitization following peripheral nerve injury.
基金University Grants Commission, New Delhi for financial support
文摘Ever increasing pressures on tropical forests worldwide due to anthropogenic disturbances have greatly affected both above-and belowground functioning of these forests.While fine roots play major ecological roles in forests through assisting in nutrient and water uptake and returning elements to the soil environment,coarse roots play an important role in C sequestration.We studied changes in fine and coarse root biomass,production,turnover and carbon and nitrogen return to the soil in two regenerating forest stands(RFs)following stonemining that were 5 years(RF-5)and 15 years(RF-15)post-disturbance compared with a natural forest stand(NF)in Mizoram,North-east India.Fine(<2mm)and coarse root(2-10 mm)biomass differed significantly among the forest stands and ranged from239(RF-5)to 415(NF)and 230(RF-5)to 436(NF)g m 2,respectively.Total root(fine+coarse)biomass increased during stand development but the proportion of very fine root(<0.5 mm)to total root production decreased.Fine root biomass decreased with increasing soil depth.Fine and total root biomass showed strong seasonal correlations with soil moisture,more so than for rainfall and temperature,whereas these relationships were less clear for the coarse root biomass.The amount of N(25-55 kg ha-1)and C(1.9-3.6t ha-1)stored in root biomass increased with stand age with a corresponding increase in production and turnover of C and N to the soil.Disturbance to these tropical forests negatively affected root dynamics,influenced their spatiotemporal patterns,and reduced the production,amount and availability of nutrients returned to the soil along with a strong reduction in the root biomass carbon pool and sequestration in carbon residence time.We observed that root growth,especially fine roots,is dependent on abiotic variables,and plays a significant role in early stages of secondary succession by adding organic matter and nutrients through high turnover rates in these forests.
基金financially supported by the National Natural Science Foundation of China (31071852 and 31121062)
文摘Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize （Zea mays L., cv. Zhengdan 958） were grown in hydroponics with the control （4 mmol L-1） or low-nitrogen （40 μmol L-1） for 12 d, supplied as nitrate. Low nitrogen enhanced root elongation rate by 4.1-fold, accompanied by increases in cell production rate by 2.2-fold, maximal elemental elongation rate （by 2.5-fold）, the length of elongation zone （by 1.5-fold）, and ifnal cell length by 1.8-fold. On low nitrogen, the higher cell production rate resulted from a higher cell division rate and in fact the number of dividing cells was reduced. Consequently, the residence time of a cell in the division zone tended to be shorter under low nitrogen. In addition, low nitrogen increased root diameter, an increase that occurred speciifcally in the cortex and was accompanied by an increase in cell number. It is concluded that roots elongates in response to low-nitrogen stress by accelerating cell production and expansion.
基金Supported by Key Project of the Education Department of Sichuan Province(09ZA079)College-level Fund of Sichuan Agricultural University(64070113)+3 种基金National Science and Technology Support Program of China(2011BAC09B05)Science and Technology Support Program of Sichuan Province(2010NZ0049)National Natural Science Foundation of China(30771717)Fund for Forest Tree Germplasm Resources in the Upper Reaches of the Yangtze River and Breeding Technology Innovation Team(00370503)
文摘[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials, to determine the root diameter （D）, root length （L）, specific root length （SRL） and contents of major nutrient elements N, P, K, Ca, Mg and C of fine roots （level 1 -5）, study the morphological characteristics and major nutrient element content and investigate the correlation. [ Result] The results showed that morphological differences of fine roots （ level 1 - 5 ） of Eucalyptus grandis plantation were great with the increase of root order, to be specific, D and L increased and SRL decreased with the increasing root order; SRL, L and D of 3-year-old Eucalyptus grauclis plantation were greater than those of 2-year-old Euca/yptus grand/s plantation. Contents of N, Ca, Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order： N and Mg contents were reduced, while Ca and C contents were enhanced; P and K contents varied with different forest ages; both 2-year-old and 3-year- old Eucalyptus grandis showed an order of C 〉 K 〉 Ca （Mg） 〉 N. Major nutrient element content and morphological characteristics of Eucalyptus grand/s fine roots （level 1 -5 ） were extremely significantly correlated （P 〈0.01 ）, SRL, L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grand/s. Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age, and the nutrient cycling and energy flow patterns also changed; major nutrient dements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order, therefore N fertilizer could be applied to improve the growth of fine roots. [ Condusion] This study laid the foundation for understanding the fine root morphology and nutrient variation pattern of Eucalyptus grandis plantation and enriching the response and adaptation mechanism theory of roots to environment, pos- sessing important reference significance for the sustainable development of Eucalyptus grand/s plantation.
