碳酸钙和根际作用对酸性红壤解磷微生物丰度的影响

选用玉米品种郑单958为试验材料,设置不添加碳酸钙(CK)、每千克土添加0.3g碳酸钙(Ca-0.3)和0.5g碳酸钙(Ca-0.5)3个碳酸钙处理,以相应处理未种植物土壤为非根际对照土壤,研究了碳酸钙和根际作用对酸性红壤磷酸酶活性及解磷微生物相关功能基因phoC和phoD丰度的影响。结果表明:碳酸钙添加能有效改善玉米生长,促进地上部氮、磷、钾和钙的吸收。土壤酸性磷酸酶(ACP)活性显著高于碱性磷酸酶(ALP)活性,表明酸性土壤中ACP在矿化有机磷方面占主导地位。根际土壤ACP、ALP活性和phoD基因拷贝数均显著高于非根际,而仅Ca-0.5处理ALP活性和phoD基因拷贝数显著高于CK,说明根际效应强于碳酸钙处理。phoC基因拷贝数与土壤铵态氮、硝态氮含量存在显著相关性,ALP活性和phoD基因拷贝数与土壤pH及铵态氮、硝态氮、有效磷、交换性钙含量均存在显著相关性。可见,碳酸钙和根际作用均影响酸性土壤解磷微生物功能和丰度,但根际效应更加明显,这些作用与土壤理化因子的改变密切相关。     

水稻叶片的活性氧代谢及衰老调控

介绍了水稻叶片中活性氧的代谢过程及目前延缓叶片衰老的调控手段。     

Calcium nutrition of the sugarbeet

Abstract

When sugarbeet seedlings are transferred from a complete nutrient solution to one from which Ca has been withheld, the rootlets and tops fail to develop. The same transfer at the eight‐leaf stage causes the rootlets to become stubby and swollen at the tips and blade expansion becomes modified; particularly the upper portions of the blades attaining nearly full development, which pucker and often develop a cupping or hooding effect; a unique symptom characteristic of Ca deficiency. As each new leaf develops, the blade area becomes smaller until only a black tip remains at the apex of the petiole, which is the symptom referred to as tip‐burn for this petiole and the successively . shorter petioles formed as Ca deficiency increases in severity. Strangely, these symptoms also appear during periods of rapid growth when the nutrient solution contains as much as 10 to 28 milliequivalents per liter of Ca or when soils are high in Ca. This implies that Ca absorption and possibly translocation limits the Ca supply at the growing point. Increasing Mg in the nutrient solution decreases Ca uptake and increases Ca deficiency. Potassium deficiency, unexpectedly, induces Ca deficiency apparently by decreasing the translocation of Ca to the growing point.

These phenomena suggest the hypothesis that when ion absorption takes place from the root exchange site that has the affinity for H > Ca > Mg > K > Na, then the H generated internally replaces, and the roots absorb, Na, K and Mg preferentially. Externally, Ca would be adsorbed preferentially from the nutrient solution by the exchange complex, and with the addition of Mg, it would compete for the common adsorption site of Ca and limit Ca absorption internally. Under these conditions potassium‐deficient nutrient solutions would not induce Ca deficiency by decreasing Ca absorption but rather by decreasing Ca translocation. Theoretically, Ba would replace H more readily than Ca on the exchange complex, and therefore, Ba would be adsorbed preferentially and Ca uptake would increase. This effect of Ba was verified experimentally.

Since the translocation of ⁴⁵Ca to the growing point was found to be unrestricted under Ca‐sufficient and Ca‐deficient conditions and since the formation of insoluble Ca compounds such as phosphate or oxalate did not account for the Ca deficiency at the growing point, the cause of the Ca deficiency at the growing point is most likely the higher priority of the storage root for Ca over tops when leaf blades and storage root are both expanding rapidly. However, Ca retransport from older to younger parts of the sugarbeet plant may be restricted by the formation of Ca phosphate under Ca‐deficient conditions and Ca oxalate under Ca‐sufficient conditions.

Calcium deficiency increases net photosynthesis per unit blade area initially, probably because of blade puckering, but not on a per unit chlorophyll basis.     

高钾血症模型的建立及抢救措施机理的分析

高钾血症是临床上多种疾病所并发的一种常见病理生理过程。血钾升高的最大危害是心肌毒性,它可引起机体心律失常甚至心脏停搏危及生命。因此,预防高钾血症的发生和采取有效的处理方法,一直是病理生理学研究的热点问题之一。了解高血钾对心肌细胞的毒性作用及寻找抢救方法。制备高血钾家兔模型,并分别用葡萄糖酸钙、NaHCO3进行抢救。高钾血症时,心电图可见家兔心律失常,并且T波高耸,Q—T间期缩短,同时,还会使机体的呼吸系统发生变化;用葡萄糖酸钙、NaHCO3后,抢救成功。高血钾对心脏有毒性作用,浓度升高速度越快,毒性作用越大。静脉推注高葡萄糖溶液、NaHCO3溶液都对缓解高血钾症有一定的作用;心电图可作为诊断高血钾,判定其程度和观察疗效的重要指标。     

Effect of dietary moisture and sodium content on urine composition and calcium oxalate relative supersaturation in healthy miniature schnauzers and labrador retrievers

The aim of this series of studies was to evaluate two possible feeding strategies as methods for reducing the risk of calcium oxalate (CaOx) formation in two breeds of healthy dog. The studies compared the effect of dietary moisture (Study 1) and dietary sodium (Na), (Study 2) on urine composition of labrador retrievers (LR) and miniature schnauzers (MS). A nutritionally complete dry dog food was fed to 16 dogs (eight LR, eight MS; Study 1) and 15 dogs (seven LR, eight MS; Study 2) for 24 days (Study 1), or 36 days (Study 2). The dogs were fed the diet alone (7% moisture, 0.06 g Na/100 kcal), or supplemented with deionised water to 73% moisture (Study 1), or dietary Na, to deliver 0.20 or 0.30 g Na per 100 kcal (Study 2). Urine pH, volume, specific gravity, and concentrations of 12 analytes were measured for each dog. Urinary relative supersaturations (RSS) with CaOx were calculated from these values. The effects of supplemental Na or water were established using t tests (Study 1) or analysis of variance, and multiple range tests (least significant difference) (Study 2); P<0.05 was considered significant. Increasing dietary moisture significantly increased total moisture intake (P=0.001), and reduced urine specific gravity (P=0.003), urinary oxalate concentration (P=0.04), and CaOx relative supersaturation (P=0.04) in the MS. Urinary parameters remained unchanged in the LR, indicating that feeding a high moisture diet may reduce the risk of CaOx formation in high-risk breeds. Increasing dietary Na led to production of urine with a significantly lower CaOx RSS in both breeds, indicating that sodium supplementation to dry diet formats may reduce the risk of CaOx formation. These feeding strategies should be considered when evaluating methods for preventing CaOx formation within high-risk groups.     

Effect of soil water stress on the development of stone cells in pear (Pyrus pyrifolia cv. ‘Niitaka’) flesh

This study was carried out to investigate the cause of stone cell formation in pear (Pyrus pyrifolia cv. ‘Niitaka’) flesh. Potted plants grown in a glass house were subjected to water stress conditions without irrigation for 30 days from 30 days before full bloom (BFB treatment), full bloom (FB treatment) and 30 days after full bloom (AFB treatment). Control plants were drip-irrigated daily maintaining a soil matrix potential around −40 ± 5 kPa. The formation of stone cells in pear flesh increased in the FB treatment and AFB treatment plants and this tendency was sustained until the harvest season. Root activity was investigated 60 days after full bloom (DAFB) and the triphenyltetrazolium chloride (TTC) reduction potential, the formazan content and leaf water potential were investigated 30, 45, and 60 DAFB. Root activity decreased progressively due to the effect of water stress. Also, the Ca content in leaf and flesh was lower. The peroxidase activity was high in the flesh at the early stages of fruit growth and decreased at the late stages of fruit growth, and then a higher increase of peroxidase activity was observed in water-stressed fruit. The reduction in calcium content of leaf and fruit in plants under water stress may be related to the reduction of root activity and leaf water potential. The increase in peroxidase activity under water stress may be due to limited calcium absorption. Higher peroxidase activity may induce the accumulation of lignin in the cell wall and promote the formation of stone cells in pear flesh. We conclude that water stress condition during the early stages of fruit growth is one of several factors that determine the formation of stone cells in pear flesh.     

叶面喷施硼酸对苹果果实硼和钙含量的影响

 以‘富士’苹果为试材，通过幼果期、果实膨大期和果实成熟期叶面喷施硼酸，研究硼对果实硼和钙含量的影响。结果表明：从叶面喷硼对果实吸收硼的短期效果来看，果实发育的不同时期叶面喷施硼酸均促进果实对硼、钙的吸收，并且处理的效果顺序是：幼果期>果实膨大期>果实成熟期；在果实采收时硼含量为：果实膨大期>果实成熟期>幼果期。不同时期叶面喷施硼酸均提高了果肉细胞中水溶态硼、半束缚态硼和束缚态硼的绝对含量，从3种形态硼所占的比例来看，随着果实不断发育，水溶态硼和半束缚态硼比例升高，而束缚态硼比例下降。     

Mitogen-activated protein kinase is involved in the changes of intracellular free calcium concentration induced by wound exudate in cultured rat epidermal stem cells

AIM: To observe the effects of harvested wound exudate on intracellular free Ca²⁺ in epidermal stem cells (ESCs) in vitro, and to investigate the relationship between mitogen-activated protein kinases (MAPKs) signal pathways and Ca²⁺ mobilization in this condition.METHODS: Wound exudate was harvested from the 80 full-thickness wounds produced on both sides of the back in 40 adult Wistar rats. ESCs were isolated, purified from neonatal Wistar rats by referring to the formerly records and binding our ideas. When the cultured cells showed up clone growing, they were divided into five groups as follows: group A: control group (no-treatment); group B: only treatment with wound exudate; group C: treatment with wound exudate and PD98059; group D: treatment with wound exudate and SB203580; group E: treatment with wound exudate, PD 98059 and SB203580. Then, the cells were incubated with fluorescence Ca²⁺ dye fluo-3/AM at 37 ℃ for 30 min, and measured by using laser scanning confocal microscope.RESULTS: The results showed that the fluorescent intensity of group B was higher than that in group A. A phenomenon of calcium oscillation was found in group C and group D. Furthermore, a rapid decrease of fluorescent intensity was observed in the cells that were preincubated with PD98059 and SB203580 at the same time. CONCLUSION: Based on above results, we propose that wound exudate can directly induce an increase in intracellular free Ca²⁺concentrations of ESCs. MAPKs signaling pathway has an important function of feedback regulation for free Ca²⁺ mobilization of ESCs in this condition, and also is capable of affecting the biological behaviour of epidermal stem cells.     

钙在橄榄树器官中的定量研究

本研究用原子吸收光谱法分析了果园土壤及橄榄树体各器官中钙量和不同组分钙的含量。结果表明：0～30cm土层中钙含量最高为0．65mg／g。橄榄器官中叶的钙含量最高为4．523mg／g，其次为根、果、结果枝。地上部器官钙含量由主干一主枝一结果枝一叶片逐渐增加。在各器官中钙主要以醋酸溶钙和盐酸溶钙的形式存在。     

单性结实与自花结实柑橘果实发育中钙钾动态的研究

 对单性结实的‘国庆1 号’温州蜜柑和自花结实的‘华农本地早’橘从开花前子房发育至果实成熟采收期整个子房或幼果及果实的不同部位(果皮和果肉) 的钙与钾含量变化进行了测定。结果表明:1) ‘国庆1 号’花前及花期子房钙含量较高, 花后趋降; 而其钾含量在花前及花期相对较低, 花后上升;2) ‘华农本地早’花前子房钙含量相对较低, 花后有一上升过程; 而对应钾在花前及花期就已很高, 花后下降; 3) 两品种果肉的钙含量自花后65 d 后均呈下降趋势, 而‘国庆1 号’果皮的钙含量在花后80 d 有一显著上升, 对应的‘华农本地早’在花后125 d 才急剧增加, 之后直至果实成熟二者均维持在较高水平;4) 两品种果皮、果肉的钾含量在果实发育过程中均呈类似的下降趋势。