海南岛土壤磷吸持性及其在分类中的意义

本文根据海南岛不同土壤类型的65个剖面310个土层的土壤磷(P)吸持性的测定结果,讨论土壤P吸持性与土壤类型、母岩(母质)种类、及土壤黏粒、铁铝氧化物含量之间的关系,并阐明土壤P吸持性在该地区土壤分类中的意义, 供为选用土壤分类指标参考。     

Molecular Aspect of Al Tolerance in Crop Plants: Novel Al-Activated Malate Transporter Gene in Wheat Roots

Aluminum (Al) is a major element in the soil; 30–40% of arable land is acidic. Solubilized Al ion in acid soils inhibits root elongation. Intensive research on the Al tolerance mechanism has been conducted in the past few decades. Mechanism of Al tolerance can be classified into Al exclusion mechanism and intracellular tolerance mechanism. Efflux of organic acids from roots upon receiving the Al signal is the major Al exclusion mechanism. Efflux of organic acids through the channel in the plasma membrane was confirmed, and the gene specifically encoding malate transporter in Al-tolerant wheat was discovered recently. The regulatory mechanism in the efflux of organic acids upon protein phosphorylation may be operative. The production of reactive oxygen species (ROS) and their scavenging system are thought to be important in the intracellular tolerance mechanism.     

家畜精子超弱化学发光的研究

利用液体闪烁计数仪测定绵羊精子的超弱化学发光,以研究它的机理和畜牧中的应用价值。结果表明,精子的发光与活力、呼吸、果糖分解、~(32)Pi摄入量和磷酸肌酸呈正相关(r=0.9806,P<0.01;0.9684,p<0.01;0.9882,p<0.01;0.9793,p<0.01;0.9962,p<0.01)说明了精子的发光与代谢存在有内在的联系,反映了精子的能量转化过程和精子细胞物理化学反应的信息,是评定精子质量很有价值的一个指标。     

Acceleration of N mineralization by release of enzymes and substrates from soil mineral particles with phosphates

A study was conducted to develop an improved method for measuring organic N (net) mineralization in which chemical extraction takes place in combination with suspension incubation in ammonia-absorbing membrane bottles. To obtain direct evidence of the extent to which extracted organic N is mineralizable, the extraction suspension was further incubated immediately after the extraction procedure with mild and selective extractants. In this ‘extraction incubation’ method, extraction continues during the incubation but only relatively easily mineralizable organic matter is released. Standard incubation is usually carried out in sealed N₂-flushed bottles. However, when phosphate or pyrophosphate soil suspensions are incubated, mineralization is much higher than in soil water suspensions. Further, accumulation of ammonia+(ammonium) and other gases, i.e. CO_2, can affect the reaction rate and final reaction equilibrium in the sealed incubation flask. It was to avoid these effects that the membrane method was developed. With this procedure, the flask is closed with an ammonia-absorbing membrane permeable to other gases. Water, phosphate and pyrophosphate suspensions were incubated at 37 °C in sealed bottles (SB), in sealed N₂ gas-flushed bottles (SBN₂), and in bottles with ammonia-trapping filters (MB). The maximum amount of released during 10 days' incubation was 133.0 mg kg⁻¹ in the water, 208.0 mg kg⁻¹ in the phosphate and 454.1 mg kg⁻¹ in the pyrophosphate suspension (soil total C content 6.2% and N 0.25%). During incubation in phosphate and pyrophosphate suspensions, the mobilization was nearly linear in membrane bottles. The variation between replicates was also smallest in these bottles. It was concluded that membrane bottles were best suited to incubation when mobilization reactions were accelerated with phosphate or pyrophosphate extractants. The method was easy to perform and gave results with good replicability.     

Inflammatory cytokines up-regulate FAT/CD36 expression in renal cells loaded by fatty acids

AIM: To investigate the effects of inflammatory cytokines on the expression of fatty acid transporter (FAT/CD36) in renal cells loaded by fatty acids. METHODS: Human mesangial cells (HMCs) and renal tubular epithelial HK-2 cells were treated with palmitate at concentrations of 0 mmol/L, 0.02 mmol/L, 0.04 mmol/L, 0.08 mmol/L, 0.16 mmol/L and 0.32 mmol/L for 24 h. The expression of FAT/CD36 at mRNA and protein levels was detected by real-time PCR and Western blotting,respectively. The renal cells were treated with palmitate at concentration of 0.04 mmol/L combined with TNF-α (25 μg/L) or IL-6 (20 μg/L) for 24 h. The effect of inflammatory cytokines on the mRNA and protein levels of FAT/CD36 in the renal cells was also investigated. Oil red O staining was used to determine the intracellular lipid droplet formation. The intracellular triglyceride (TG) and free fatty acid (FFA) were measured by enzymic assay and ELISA, respectively. RESULTS: Palmitate loading dose-dependently increased the expression of FAT/CD36 at mRNA and protein levels in both HMCs and HK-2 cells. The inflammatory cytokines further increased the expression of FAT/CD36 at mRNA and protein levels in both cells loaded by palmitate. Oil red O staining, TG detection and FFA assay showed that the inflammatory cytokines increased intracellular lipid levels in both HMCs and HK-2 cells. CONCLUSION: Inflammatory cytokines up-regulate the expression of FAT/CD36 in renal cells loaded by fatty acids and exacerbate the intracellular lipid accumulation.     

Angiotensin-(1-7) increases expression of ABCA1 and decreases content of cholesterol in THP-1-derived foam cells via AC-cAMP pathway

AIM: To establish the THP-1-derived foam cell formation and to evaluate the effects of angiotensin-(1-7) and MDL (an inhibitor of adenylate cyclase) on the expression of ATP-binding cassete transporter A1(ABCA1) and the content of cholesterol. METHODS: THP-1-derived macrophages were treated with oxidized low-density lipoprotein(ox-LDL) to develop into foam cells. The foam cells were divided into 4 groups: control group, MDL group, Ang-(1-7) group and MDL+Ang-(1-7) group. At 24 h after treatment, the content of cAMP was measured by ELISA. The mRNA and protein levels of ABCA1 were determined by real-time RT-PCR and Western blotting, respectively. The content of cholesterol was detected by high performance liquid chromatography. RESULTS: The cAMP, the mRNA and protein levels of ABCA1 in Ang-(1-7) group were significantly higher, and the content of cholesterol was significantly lower than those in control group (P<0.05). On the contrary, the cAMP, the mRNA and protein levels of ABCA1 in MDL group were significantly lower and the content of cholesterol was significantly higher than those in control group (P<0.05). The results in MDL+Ang-(1-7) group were between Ang-(1-7) group and control group. CONCLUSION: Ang-(1-7) inhibits the formation of foam cells by promoting the expression of ABCA1 and decreasing the content of cholesterol. MDL partly antagonizes the effect of Ang-(1-7) by inhibiting the adenylate cyclase and decreasing the content of cAMP.     

植物SWEET蛋白的结构与分类及功能研究进展

植物SWEET蛋白是一类重要的转运蛋白,研究其生理生化功能,有助于分子辅助育种,缩短育种年限。本文基于文献资料,梳理归纳了近年来国内外的植物SWEET蛋白的结构、分类、转运底物和功能方面的相关研究进展,阐述表明SWEET蛋白是植物中广泛存在的一类糖转运体,既能转运单糖又能转运蔗糖,属于Mt N3家族。不同植物间的SWEET蛋白具有一定的保守性,根据亲缘关系SWEET家族可以分为四类。植物SWEET蛋白是位于膜系统上,参与糖分的跨膜转运,在植物生长发育及逆境胁迫中均有不同程度的调控作用,如调控花蜜的分泌、花粉的营养、灌浆期种子的发育、果实发育、植物抗逆性和抗病性等。然而不同植物的SWEET蛋白转运底物和调控功能不同,目前仅在拟南芥等少数植物中研究较为深入。