The systematic or long-distance signal transmission plays crucial roles inanimal lives. Compared with animals, however, much less is known about the roles of long-distancesignal communication in plant lives. Using the...The systematic or long-distance signal transmission plays crucial roles inanimal lives. Compared with animals, however, much less is known about the roles of long-distancesignal communication in plant lives. Using the model plant Commelina communisL, we have probed theroot to shoot communication mediated by heat-shock signals. The results showed that a heat shock of5 min at 40°C in partial roots, i.e. half or even 1/4 root system, could lead to a significantdecrease in stomatal conductance. The regulation capability depends on both heat shock temperatureand the amount of root system, i.e. with higher temperature and more roots stressed, the leafconductance would decrease more significantly. Interestingly, the stomatal regulation by heat shocksignal is in a manner of oscillation: when stomata conductance decreased to the lowest level withinabout 30 min, it would increase rapidly and sometimes even exceed the initial level, and afterseveral cycles the stomata conductance would be finallystabilized at a lower level. Feeding xylemsap collected from heat-shocked plants could lead to a decrease in stomata conductance, suggestingthat the heat shock-initiated signal is basically a positive signal. Further studies showed thatheat shock wasnot able to affect ABA content in xylem sap, and also, not able to lead to a decreasein leaf water status, which suggested that the stomatal regulation was neither mediated by ABA norby a hydraulic signal. Heat shock could lead to an increase in xylemsap H_2O_2 content, andmoreover, the removal of H_2O_2 by catalase could partially recover the stomatal inhibition by xylemsap collected from heat-shocked plants, suggesting that H_2O_2 might be able to act as one of theroot signals to control the stomatal movement. Due to the fact that heat-shock and drought areusually two concomitant stresses, the stomatal regulation by heat-shock signal should be ofsignificance for plant response to stresses. The observation for the stomatal regulation in anoscillation manner by presently identified new 展开更多
Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, m...Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.展开更多
基金supported by the National Basic Research Program of China(Grant No.2003CB114300)National Natural Science Foundation of China(Grant Nos.30270135&30470160).
文摘The systematic or long-distance signal transmission plays crucial roles inanimal lives. Compared with animals, however, much less is known about the roles of long-distancesignal communication in plant lives. Using the model plant Commelina communisL, we have probed theroot to shoot communication mediated by heat-shock signals. The results showed that a heat shock of5 min at 40°C in partial roots, i.e. half or even 1/4 root system, could lead to a significantdecrease in stomatal conductance. The regulation capability depends on both heat shock temperatureand the amount of root system, i.e. with higher temperature and more roots stressed, the leafconductance would decrease more significantly. Interestingly, the stomatal regulation by heat shocksignal is in a manner of oscillation: when stomata conductance decreased to the lowest level withinabout 30 min, it would increase rapidly and sometimes even exceed the initial level, and afterseveral cycles the stomata conductance would be finallystabilized at a lower level. Feeding xylemsap collected from heat-shocked plants could lead to a decrease in stomata conductance, suggestingthat the heat shock-initiated signal is basically a positive signal. Further studies showed thatheat shock wasnot able to affect ABA content in xylem sap, and also, not able to lead to a decreasein leaf water status, which suggested that the stomatal regulation was neither mediated by ABA norby a hydraulic signal. Heat shock could lead to an increase in xylemsap H_2O_2 content, andmoreover, the removal of H_2O_2 by catalase could partially recover the stomatal inhibition by xylemsap collected from heat-shocked plants, suggesting that H_2O_2 might be able to act as one of theroot signals to control the stomatal movement. Due to the fact that heat-shock and drought areusually two concomitant stresses, the stomatal regulation by heat-shock signal should be ofsignificance for plant response to stresses. The observation for the stomatal regulation in anoscillation manner by presently identified new
文摘Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.
