The maize quadraplex tetraploids and duplex tetraploids were developed using Kato’s protocols. The phenotype ofheterosis and inbreeding depression over generations in their parents and progenies of F1, F2 and F3 were...The maize quadraplex tetraploids and duplex tetraploids were developed using Kato’s protocols. The phenotype ofheterosis and inbreeding depression over generations in their parents and progenies of F1, F2 and F3 were investigated.The results indicated that different duplex tetraploids have different genetic backgrounds, but they acquire maximumheterosis at same traits, such as the leaf length, leaf width, culm circumference and days to flowering. P.N. rises muchfaster from the F2 to F3 segment than the A.W. does for the plant height in duplex tetraploids. In comparing duplex andquadraplex over a generation the quadriplex is showing the greatest heterosis in plant height, leaf height, leaf width anddays to flowering. Most of the examples achieve the maximum heterosis at Qu F2, with the exception of culm circumference,which achieves greatest heterosis at PNAW F1. Meanwhile, this experiment shows that quadraplex tetraploids has distinctadditional favorable alleles that are not contained in duplex tetraploid, this is demonstrated by the heterosis found incrosses between the two duplex tetraploid. This finding helps explain quadraploids superiority and unique breedingbehavior, in which, the progressive heterosis and inbreeding depression in maize are due mainly to linkage disequilibrium.The severe inbreeding depression in duplex tetraploids is due mainly to the rapid loss of complementary chromosomes orgenes interactions in the first few generation of inbreeding. Correspondingly, the progressive heterosis in quadraplextetraploids is due mainly to a progressive increase in complementarities of homologous chromosomes or genes interactions.Greater complementarities of homologous chromosomes or genes interactions in tetraploids maize alse helps explainrecent molecular biology research indicating that some of traits in quadraplex tetraploids are more responsive to geneticdiversity than in duplex tetraploids. In addition, the dosage effect of polyploid in relation to the genetic basis of heterosisand inbreeding depression were discussed also.展开更多
Guard cells have been developed as a model system for dissecting hormone,ion channel and calcium signal transduction in response to physiological stimuli. Abscisic acid causes elevations in the cytosolic Ca^2+ concent...Guard cells have been developed as a model system for dissecting hormone,ion channel and calcium signal transduction in response to physiological stimuli. Abscisic acid causes elevations in the cytosolic Ca^2+ concentration in guard cells. We identified reactive oxygen species（ROS) activation of Ca^2+-permeable展开更多
The present study explores the forward mask-ing of the two-tone stimuli in sequence that evoked responses in the inferior colliculus (IC) of the echolocating bats. The results indicate that forward masking is obvious ...The present study explores the forward mask-ing of the two-tone stimuli in sequence that evoked responses in the inferior colliculus (IC) of the echolocating bats. The results indicate that forward masking is obvious in the acoustic responses of the IC neurons to the two-tone stimuli. Meanwhile the intensity sensitivity of the neurons respond-ing to the probe increases with the inter-tone interval de-creasing. The effects of forward masking are correlated with the relative intensity and the interval between the masker and probe. That is, the effects of forward masking are re-duced with the masker intensity decreasing and enhanced with the probe intensity decreasing and the inter-tone inter-val shortened. The present study suggests that there is a cor-relation between the characteristics of the response to the probe and the dynamic conditions of the postsynaptic cur-rents in the IC neurons.展开更多
Auxin response factors (ARFs) play a central role in plants as transcriptional factors in response to auxin. The Arabidopsis ARF8 gene is a light-inducible gene and ARF8 protein might control auxin homeostasis in a ne...Auxin response factors (ARFs) play a central role in plants as transcriptional factors in response to auxin. The Arabidopsis ARF8 gene is a light-inducible gene and ARF8 protein might control auxin homeostasis in a negative feed-back fashion through regulation of GH3 gene expression. In a double mutant designated infertile line including arf8-1 (a T-DNA insertion mutant of ARF8), we isolated fertility1-1 (fer1-1), a mutant of Fer1, which acts synergistically with ARF8 to control the development of the anther and filament in Arabidopsis. Genetics analysis has demonstrated that fer 1-1 is a T-DNA insertion line, indicating that Fer1 might be cloned by inverse polymerase chain reaction (PCR) or the TAIL-PCR approach. Phenotypic identification and molecular analysis of fer 1-1 and the infertile line will be helpful to characterize the function of Fer1, to further study the function of ARF8, and to reveal the molecular mechanism underlying the interaction of Fer1 and ARF8 in controlling development of the anther and filament.展开更多
By means of a particular two-tone stimulationparadigm in combination of using a pair of electrodes forsimultaneously recording from two inferior colliculus (IC)neurons, the current in vivo study is undertaken to explo...By means of a particular two-tone stimulationparadigm in combination of using a pair of electrodes forsimultaneously recording from two inferior colliculus (IC)neurons, the current in vivo study is undertaken to explorethe role of frequency band integration (FBI) in sharpening offrequency tuning in the big brown bat, Eptesicus fuscus.Three major results are found: (1) The paired neurons cor-related to FBI are located not only within the same frequencyfilter bandwidth (FFB), but also across different FFBs. Therelations of their frequency tuning curves (FTCs) are mainlyof two types: the flank-overlapped and overlaid patterns. (2)Although the sharpness of FTCs between paired neurons ismutual, the sharpening efficiency of neurons located withinthe same FFB is higher than that of neurons across FFBs,and the FTCs of neurons with the best frequencies (BF) of 20--30 kHz are most strongly sharpened. (3) The strength ofFBI is weak near the BF but gradually increased with fre-quencies away from the BF of sound stimuli. This suggeststhat the dynamical FBI of the IC neurons located within and across the FFBs might be involved in the formation of func-tional FFB structures.展开更多
基金This study was in part supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Education Ministry of Chinaa grant from the Department of Energy Biosciences,USA,to University of Columbia,JB.
文摘The maize quadraplex tetraploids and duplex tetraploids were developed using Kato’s protocols. The phenotype ofheterosis and inbreeding depression over generations in their parents and progenies of F1, F2 and F3 were investigated.The results indicated that different duplex tetraploids have different genetic backgrounds, but they acquire maximumheterosis at same traits, such as the leaf length, leaf width, culm circumference and days to flowering. P.N. rises muchfaster from the F2 to F3 segment than the A.W. does for the plant height in duplex tetraploids. In comparing duplex andquadraplex over a generation the quadriplex is showing the greatest heterosis in plant height, leaf height, leaf width anddays to flowering. Most of the examples achieve the maximum heterosis at Qu F2, with the exception of culm circumference,which achieves greatest heterosis at PNAW F1. Meanwhile, this experiment shows that quadraplex tetraploids has distinctadditional favorable alleles that are not contained in duplex tetraploid, this is demonstrated by the heterosis found incrosses between the two duplex tetraploid. This finding helps explain quadraploids superiority and unique breedingbehavior, in which, the progressive heterosis and inbreeding depression in maize are due mainly to linkage disequilibrium.The severe inbreeding depression in duplex tetraploids is due mainly to the rapid loss of complementary chromosomes orgenes interactions in the first few generation of inbreeding. Correspondingly, the progressive heterosis in quadraplextetraploids is due mainly to a progressive increase in complementarities of homologous chromosomes or genes interactions.Greater complementarities of homologous chromosomes or genes interactions in tetraploids maize alse helps explainrecent molecular biology research indicating that some of traits in quadraplex tetraploids are more responsive to geneticdiversity than in duplex tetraploids. In addition, the dosage effect of polyploid in relation to the genetic basis of heterosisand inbreeding depression were discussed also.
文摘Guard cells have been developed as a model system for dissecting hormone,ion channel and calcium signal transduction in response to physiological stimuli. Abscisic acid causes elevations in the cytosolic Ca^2+ concentration in guard cells. We identified reactive oxygen species（ROS) activation of Ca^2+-permeable
基金supported by the National Natural Science Foundation of China(Grant No.30170313)the Ph.D.Education Fund of China(Grant No.2000026905)and the NSF of USA.`
文摘The present study explores the forward mask-ing of the two-tone stimuli in sequence that evoked responses in the inferior colliculus (IC) of the echolocating bats. The results indicate that forward masking is obvious in the acoustic responses of the IC neurons to the two-tone stimuli. Meanwhile the intensity sensitivity of the neurons respond-ing to the probe increases with the inter-tone interval de-creasing. The effects of forward masking are correlated with the relative intensity and the interval between the masker and probe. That is, the effects of forward masking are re-duced with the masker intensity decreasing and enhanced with the probe intensity decreasing and the inter-tone inter-val shortened. The present study suggests that there is a cor-relation between the characteristics of the response to the probe and the dynamic conditions of the postsynaptic cur-rents in the IC neurons.
文摘Auxin response factors (ARFs) play a central role in plants as transcriptional factors in response to auxin. The Arabidopsis ARF8 gene is a light-inducible gene and ARF8 protein might control auxin homeostasis in a negative feed-back fashion through regulation of GH3 gene expression. In a double mutant designated infertile line including arf8-1 (a T-DNA insertion mutant of ARF8), we isolated fertility1-1 (fer1-1), a mutant of Fer1, which acts synergistically with ARF8 to control the development of the anther and filament in Arabidopsis. Genetics analysis has demonstrated that fer 1-1 is a T-DNA insertion line, indicating that Fer1 might be cloned by inverse polymerase chain reaction (PCR) or the TAIL-PCR approach. Phenotypic identification and molecular analysis of fer 1-1 and the infertile line will be helpful to characterize the function of Fer1, to further study the function of ARF8, and to reveal the molecular mechanism underlying the interaction of Fer1 and ARF8 in controlling development of the anther and filament.
文摘By means of a particular two-tone stimulationparadigm in combination of using a pair of electrodes forsimultaneously recording from two inferior colliculus (IC)neurons, the current in vivo study is undertaken to explorethe role of frequency band integration (FBI) in sharpening offrequency tuning in the big brown bat, Eptesicus fuscus.Three major results are found: (1) The paired neurons cor-related to FBI are located not only within the same frequencyfilter bandwidth (FFB), but also across different FFBs. Therelations of their frequency tuning curves (FTCs) are mainlyof two types: the flank-overlapped and overlaid patterns. (2)Although the sharpness of FTCs between paired neurons ismutual, the sharpening efficiency of neurons located withinthe same FFB is higher than that of neurons across FFBs,and the FTCs of neurons with the best frequencies (BF) of 20--30 kHz are most strongly sharpened. (3) The strength ofFBI is weak near the BF but gradually increased with fre-quencies away from the BF of sound stimuli. This suggeststhat the dynamical FBI of the IC neurons located within and across the FFBs might be involved in the formation of func-tional FFB structures.
