Free cytosolic Ca^2＋ （[Ca^2＋]cyt） is an ubiquitous second messenger in plant cell signaling, and [Ca^2＋]cyt elevation is associated with Ca^2＋-permeable channels in the plasma membrane and endomembranes regulate...Free cytosolic Ca^2＋ （[Ca^2＋]cyt） is an ubiquitous second messenger in plant cell signaling, and [Ca^2＋]cyt elevation is associated with Ca^2＋-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca^2＋ channels and their regulation remains limited in planta. A type of voltage- dependent Ca^2＋-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba^2＋ and Ca^2＋, and their activities can be inhibited by micromolar Gd^3＋. The unitary conductance and the reversal potential of the channels depend on the Ca^2＋ or Ba^2＋ gradients across the plasma membrane. The inward whole-cell Ca^2＋ （Ba^2＋） current, as well as the unitary current amplitude and NPo of the single Ca^2＋ channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.展开更多
One of the detrimental effects of high salmity on plant cells is considered to be the result of an ion imbalance, particularly a high ratio of Na^+ to K^+ ions, in the cytoplasm. Such an imbalance is probably due to a...One of the detrimental effects of high salmity on plant cells is considered to be the result of an ion imbalance, particularly a high ratio of Na^+ to K^+ ions, in the cytoplasm. Such an imbalance is probably due to a great increase of entry of Na^+ ions into cells and a decline in absorption of K^+ ions under high-salinity conditions. Thus, plant cells展开更多
NBS-LRR (nucleotide binding sites and leucine rich repeat) protein plays a crucial role as sentries and as defense activators in plants. The structure and function of NBS-LRR proteins are closely related. Previous art...NBS-LRR (nucleotide binding sites and leucine rich repeat) protein plays a crucial role as sentries and as defense activators in plants. The structure and function of NBS-LRR proteins are closely related. Previous articles have announced that the activated ZAR1 (HopZ-Activated Resistance 1) forms a pentamer in the plasma membrane, which is a calcium permeable channel that can trigger plant immune signaling and cell death. However, the structure of galore NBS-LRRs in Arabidopsis is not yet clear. The functional sites of distinct NBS-LRR in cells may vary. In addition, identifying pathogens and activating defense regions may occur in different subcellular compartments. Therefore, dissecting the specific structure and positioning of NBS-LRRs is an indispensable step in understanding their functions. In this article, we exploit AlphaFold to predict the structure of some designed NBS-LRRs, and utilize Agroinfiltration transient expression system, combined with biochemical fractionation, to dissect the localization of these NBS-LRR receptors from Arabidopsis. Structural data indicates that the identified NBS-LRRs share analogous conformation. Membrane fractionation assay demonstrates these NBS-LRRs are mainly associated with the membrane. These data show that the Ca2+-permeable channel activity may be evolutionarily conserved in NBS-LRR of Arabidopsis, and this study provides some reference clues for analyzing the structure and localization patterns of other plant immune receptors.展开更多
OBJECTIVE： To observe the impact of Shijueming （Concha Haliotidis） on spontaneously hypertensive rats via blood pressure, serum calcium, vascular smooth muscle membrane L-type calcium channel α1 C subunit （CaL-...OBJECTIVE： To observe the impact of Shijueming （Concha Haliotidis） on spontaneously hypertensive rats via blood pressure, serum calcium, vascular smooth muscle membrane L-type calcium channel α1 C subunit （CaL-α1C）, plasma membrane calci- um-ATPase （PMCA） mRNA expression, and the L-type calcium channel in vascular smooth muscle cells. METHODS： Twelve-week-old male rats with sponta- neous hypertension were divided into three groups： a Shijueming （Concha Haliotidis） group （group 1）, a nifedipine group （group 2）, and a dis- tilled water group （group 3）. All were given a four-week treatment. Blood pressure and dissocia- tive serum calcium were examined before treat- ment. Blood pressure was taken every week during treatment. Atomic absorption spectrometry was used to examine dissociative serum calcium. Re-verse transcription-polymerase chain reaction was used to examine the expression of CaL-α1C and PM- CA1 mRNA. The patch clamp technique was used to examine the electrophysiological characteristics of the vascular smooth muscle cell calcium chan- nels. RESULTS： After treatment, blood pressure of the Shijueming （Concha Halioticlis） group lowered but not significantly （P〉0.05）. Blood pressure of the nifedipine group lowered significantly （P〈0.05）. Blood pressure of the distilled water group re- mained high. The concentration of serum calcium in the Shijueming （Concha Haliotidis） and the dis- tilled water groups lowered （P〈0.05）. Expression of CaL-α1C mRNA in the nifedipine group decreased compared with the distilled water group （P〈0.01）. There was the decreasing trend in the Shijueming （Concha Haliotidis） group, but it was not statistically significant. Shijueming （Concha Haliotidis） also had effects on the expression of PMCA1 mRNA but with- out statistical significance. However, there was a significant decreasing effect on vascular smooth muscle cell Ica-L flow. CONCLUSION： This study indicated that Shijuem- ing （Concha Haliotidis） could increase serum calci- um and decrease blood pressure. It may work by in- fluencing calcium channels, expression of PMCA1 mRNA, and regulating ion calcium channels and calcium-ATPase.展开更多
基金Supported by the National Natural Science Foundation of China (30671029)the State Key Basic Research and Development Plan of China(2006CB100100)
文摘Free cytosolic Ca^2＋ （[Ca^2＋]cyt） is an ubiquitous second messenger in plant cell signaling, and [Ca^2＋]cyt elevation is associated with Ca^2＋-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca^2＋ channels and their regulation remains limited in planta. A type of voltage- dependent Ca^2＋-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba^2＋ and Ca^2＋, and their activities can be inhibited by micromolar Gd^3＋. The unitary conductance and the reversal potential of the channels depend on the Ca^2＋ or Ba^2＋ gradients across the plasma membrane. The inward whole-cell Ca^2＋ （Ba^2＋） current, as well as the unitary current amplitude and NPo of the single Ca^2＋ channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.
基金Project supported by the National Natural Science Foundation of China.
文摘One of the detrimental effects of high salmity on plant cells is considered to be the result of an ion imbalance, particularly a high ratio of Na^+ to K^+ ions, in the cytoplasm. Such an imbalance is probably due to a great increase of entry of Na^+ ions into cells and a decline in absorption of K^+ ions under high-salinity conditions. Thus, plant cells
文摘NBS-LRR (nucleotide binding sites and leucine rich repeat) protein plays a crucial role as sentries and as defense activators in plants. The structure and function of NBS-LRR proteins are closely related. Previous articles have announced that the activated ZAR1 (HopZ-Activated Resistance 1) forms a pentamer in the plasma membrane, which is a calcium permeable channel that can trigger plant immune signaling and cell death. However, the structure of galore NBS-LRRs in Arabidopsis is not yet clear. The functional sites of distinct NBS-LRR in cells may vary. In addition, identifying pathogens and activating defense regions may occur in different subcellular compartments. Therefore, dissecting the specific structure and positioning of NBS-LRRs is an indispensable step in understanding their functions. In this article, we exploit AlphaFold to predict the structure of some designed NBS-LRRs, and utilize Agroinfiltration transient expression system, combined with biochemical fractionation, to dissect the localization of these NBS-LRR receptors from Arabidopsis. Structural data indicates that the identified NBS-LRRs share analogous conformation. Membrane fractionation assay demonstrates these NBS-LRRs are mainly associated with the membrane. These data show that the Ca2+-permeable channel activity may be evolutionarily conserved in NBS-LRR of Arabidopsis, and this study provides some reference clues for analyzing the structure and localization patterns of other plant immune receptors.
文摘OBJECTIVE： To observe the impact of Shijueming （Concha Haliotidis） on spontaneously hypertensive rats via blood pressure, serum calcium, vascular smooth muscle membrane L-type calcium channel α1 C subunit （CaL-α1C）, plasma membrane calci- um-ATPase （PMCA） mRNA expression, and the L-type calcium channel in vascular smooth muscle cells. METHODS： Twelve-week-old male rats with sponta- neous hypertension were divided into three groups： a Shijueming （Concha Haliotidis） group （group 1）, a nifedipine group （group 2）, and a dis- tilled water group （group 3）. All were given a four-week treatment. Blood pressure and dissocia- tive serum calcium were examined before treat- ment. Blood pressure was taken every week during treatment. Atomic absorption spectrometry was used to examine dissociative serum calcium. Re-verse transcription-polymerase chain reaction was used to examine the expression of CaL-α1C and PM- CA1 mRNA. The patch clamp technique was used to examine the electrophysiological characteristics of the vascular smooth muscle cell calcium chan- nels. RESULTS： After treatment, blood pressure of the Shijueming （Concha Halioticlis） group lowered but not significantly （P〉0.05）. Blood pressure of the nifedipine group lowered significantly （P〈0.05）. Blood pressure of the distilled water group re- mained high. The concentration of serum calcium in the Shijueming （Concha Haliotidis） and the dis- tilled water groups lowered （P〈0.05）. Expression of CaL-α1C mRNA in the nifedipine group decreased compared with the distilled water group （P〈0.01）. There was the decreasing trend in the Shijueming （Concha Haliotidis） group, but it was not statistically significant. Shijueming （Concha Haliotidis） also had effects on the expression of PMCA1 mRNA but with- out statistical significance. However, there was a significant decreasing effect on vascular smooth muscle cell Ica-L flow. CONCLUSION： This study indicated that Shijuem- ing （Concha Haliotidis） could increase serum calci- um and decrease blood pressure. It may work by in- fluencing calcium channels, expression of PMCA1 mRNA, and regulating ion calcium channels and calcium-ATPase.
