Glucose transporters in pearl gentian grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂): Molecular cloning,characterization, tissue distribution and their expressions in response to dietary carbohydrate level

The glucose transporters (GLUTs) play vital role in mediating the glucose uptake process, the movement of glucose across plasma membranes. In this study, three GLUTs, GLUT1, GLUT2 and GLUT4 were cloned and characterized form pearl gentian grouper, a hybrid grouper, and their expressions in response to dietary carbohydrate level (8.02%, 11.89% and 16.08%) were investigated after feeding. The full‐length cDNA of GLUT1, GLUT2 and GLUT4 were 2,104, 3,759 and 2,815 bp, respectively, encoding a putative protein of 491, 508 and 505 amino acids respectively. The results of sequence and phylogenetic analysis revealed that grouper GLUTs were highly conserved and clustered together with their corresponding teleost orthologues, rather than mammals. In addition, GLUT1 was ubiquitously expressed in all detected tissues with relative high expressions in heart and brain. GLUT2 is relatively abundant in some certain tissues that release glucose, such as liver and intestine, and GLUT4 was expressed primarily in muscle and eye. The elevated dietary carbohydrate level had no significant difference on the expression of GLUT1 in grouper liver. The expression of GLUT2 in grouper liver was significantly up‐regulated with the increasing dietary carbohydrate from 8.02% to 11.89%, and therefore down‐regulated significantly. Meanwhile, the expression of GLUT4 in grouper muscle increased significantly with increasing dietary carbohydrate. Results of this study indicate that the up‐regulation of GLUTs in fish contribute to maintain glucose equilibrium to some extent when fish were fed with high carbohydrate diets.     

杂交茎瘤芥干物质积累和氮磷钾吸收特性研究

用分期取样、化验分析、模型拟合的方法对杂交茎瘤芥干物质积累和氮、磷、钾的吸收特性进行了研究。结果表明,杂交茎瘤芥干物质积累和氮、磷、钾的吸收均符合Logistic生长曲线,干物质的旺盛积累期在13～18叶龄,磷、钾的旺盛吸收期与干物质的旺盛积累期同步,氮的旺盛吸期在11～16叶龄。在旺盛生长期干物质积累量占87％,氮、磷、钾在旺盛吸收期的吸收量占大田营养生长阶段吸收总量的68．9％,70．3％,72．7％。在此基础上,讨论了杂交笨瘤芥施肥量、施肥时期和追肥次数．     

马尾松不同种源P素吸收动力学特征

通过水培试验研究田间试验下对P肥反应存在显著差异的5个马尾松种源在3种P水平(水培试验中为0、5、20μmol·L-1)下根系P素吸收总量、离子动力学参数(Imax、Km和Cmin)等特征。研究表明,随着溶液P素浓度的升高,马尾松各参试种源的苗高生长、P素吸收总量均有不同程度的增加,但其变化因种源而异。福建武平和广东信宜两种源对P素增加的反应敏感性(高生长和P素吸收增长率)远低于其他3个参试种源,与大田P肥试验结果一致。对1年生和半年生水培幼苗离子动力学参数测定结果揭示,随着培养溶液P素浓度的升高,各参试种源的Imax下降,Km和Cmin增加。比较分析发现,低P水平下广东信宜和福建武平两种源具有相对较小的Km和Cmin,相对较大的Imax,对分布于武夷山脉南端的福建武平种源尤其如此。     

缺Ca/Fe及盐分胁迫下番茄Pb吸收转运与关键基因的表达关系

选取台湾黄圣女番茄为供试材料,通过水培试验研究缺Ca/Fe及盐分胁迫三种处理对Pb在番茄中富集的影响,并测定不同处理下根部CNGC1(环核苷酸门控非选择性阳离子通道)和HMA3(P1B-ATPase酶)基因的相对表达量,进而探究CNGC1和HMA3基因的表达对番茄吸收累积Pb的影响。结果表明:与对照相比,缺钙处理显著增强了根对Pb的吸收能力并抑制了Pb往地上部转运过程,缺Fe处理对根吸收能力无显著影响而增加了往地上部转运量,盐分处理同时增强了根部吸收及往地上部转运能力;不同处理下番茄根部单位质量Pb净吸收量与CNGC1离子通道的活性水平呈现出极显著正相关(P0.01),说明番茄根部CNGC1离子通道在不同处理下Pb的吸收可能起着重要作用;番茄Pb转运系数与HMA3的表达量呈现极显著负相关(P0.01),说明番茄HMA3的高表达抑制了番茄对Pb的地上转运能力。因此,缺Ca/Fe及盐分胁迫处理对Pb在番茄中富集有不同影响,CNGC1离子通道和HMA3的表达量在一定程度上决定了Pb在番茄中的分布。     

Effects of crop‐straw biochar on crop growth and soil fertility over a wheat‐millet rotation in soils of China

We conducted a pot experiment using a wheat‐millet rotation to examine the effects of two successive rice‐straw biochar applications on crop growth and soil properties in acidic oxisols and alkaline cambosols from China. Biochar was incorporated into soil at rates of 0, 2.25 or 22.5 Mg/ha at the beginning of each crop season with identical applications of NPK fertilizer. In the oxisols, the largest biochar treatment enhanced soil pH and cation exchange capacity, decreased soil bulk density, improved soil P, K, Ca and Mg availability and enhanced their uptake, and increased wheat and millet yields by 157 and 150% for wheat grain and straw, respectively, and 72.6% for millet straw. In the cambosols, biochar treatment decreased soil bulk density, improved P and K availability, increased N, P and K uptake by crops and increased wheat and millet straw yields by 19.6 and 60.6%, respectively. Total soil organic carbon increased in response to successive biochar applications over the rotation. No difference in water‐soluble organic carbon was recorded between biochar‐treated and control soils. Converting straw to biochar and treating soils with successive applications may be a viable option for improving soil quality, sequestering carbon and utilizing straw resources in China.     

Short rotation forestry – Earthworm interactions: A field based mesocosm experiment

Short rotation forestry (SRF) which consists of planting rapidly growing native and non-native tree species has been introduced to the UK to increase woody biomass production. A largely unknown aspect of SRF species is their interaction with soil fauna, of which the earthworm community is a major component. Earthworms have a pronounced impact on litter decomposition, nutrient cycling and tree growth. Conversely, tree litter and root chemistry can impact on the associated earthworm community development. The aim of this study was to determine direct interactions between SRF species and earthworms. A field-based mesocosm experiment was conducted using Betula pendula (birch) and Eucalyptus nitens (eucalyptus) with two earthworm species Lumbricus terrestris and Allolobophora chlorotica. The one year experiment revealed that native birch and non-native eucalyptus had a similar influence on L. terrestris population development. However, birch had a positive impact on A. chlorotica population establishment compared with eucalyptus. In the presence of earthworms, total tree biomass and leaf nitrogen concentration of eucalyptus were increased respectively by 25% and 27% compared with an earthworm-free control. In the presence of earthworms, surface litter incorporation was greater for both tree species (almost 5 times for birch and 3 times for eucalyptus) compared with controls. This work showed direct SRF-earthworm interactions which differed for tree species.     

Enhanced root uptake of acibenzolar-S-methyl (ASM) by tomato plants inoculated with selected Bacillus plant growth-promoting rhizobacteria (PGPR)

The combination of plant growth-promoting rhizobacteria (PGPR) and plant resistance inducers is an alternative crop protection approach in modern agricultural systems. Despite the numerous reports regarding the improved suppression of plant pathogens by their combined application, little is known about the interactions among these components. In the present study, the persistence behavior of the plant activator acibenzolar-S-methyl (ASM) in the rhizosphere of tomato plants and its root uptake as well as systemic translocation ability in aboveground parts after combined use with certain Bacillus PGPR strains (B. amyloliquefaciens IN937a, B. pumilus SE34, B. subtilis FZB24 and GB03) were investigated. Additionally, the population dynamics of the PGPR strain B. subtilis GB03 at the tomato root system and rhizosphere soil applied with or without the pesticide were studied. The results showed that the addition of PGPR inocula did not affect the dissipation rate of ASM in rhizosphere soil. Also, the formation of its major metabolite CGA 210007 in soil was rapid, since it was detected one hour after root drench and it was maintained at high levels during the sampling period without considerable variations among the bacterial treatments compared to the control. The uptake and systemic translocation of ASM and its metabolite CGA 210007 from root to shoot was rapid and maximum concentrations were observed at 48–96 h after its application. It was revealed that in plants treated with the PGPR strains B. subtilis GB03 and B. pumilus SE34 the uptake and systemic translocation of ASM and CGA 210007 in the aerial parts of the tomato plants was significantly higher compared to the control receiving no bacterial treatment. Also, the populations of the strain B. subtilis GB03 showed high colonizing ability in the root system and the rhizosphere soil. PGPR strains that lead to enhanced pesticide uptake by plants should be further evaluated as components in integrated management systems.     

水稻硅吸收动力学参数固定方法的研究

本文采用常规耗竭法和改进耗竭法研究了水稻苗期硅的吸收动力学参数,着重对测定方法、数据处理方式及参数的量纲表示等进行了初步探讨。结果表明,不同的试验方法、数据处理方式及不同的量纲表示得到的水稻苗期硅吸收动力学参数值的大小不同。为使试验结果真实可靠,应该用不同的数据处理方式对数据进行处理并用相关系数的大小对数据作出评价。在本试验中,根据相关系数的大小得出,改进耗竭法优于常规耗竭法;不同的数据处理方式中,作图法得到的数据准确性最高;Vmax用mg/(g.h),DW作量纲时得到的硅吸收动力参数值较为合理。     

Phosphorus fertilizer effects on the competition between wheat and several weed species

Information on phosphorus (P) fertilizer affecting crop–weed competitive interactions might aid in developing improved weed management systems. A controlled environment study was conducted to examine the effect of three P doses on the competitive ability of four weed species that were grown with wheat. Two grass and two broad-leaved weed species were chosen to represent the species that varied in their growth responsiveness to P: wild oat (medium), Persian darnel (low), round-leaved mallow (high), and kochia (low). Wheat and each weed species were grown in a replacement series design at P doses of 5, 15, and 45 mg P kg⁻¹ soil. The competitive ability of the low P-responsive species, Persian darnel and kochia, decreased as the P dose increased, supporting our hypothesis that the competitiveness of species responding minimally to P would remain unchanged or decrease at higher P levels. As expected, the competitiveness of the high P-responsive species, round-leaved mallow, progressively improved as the P dose increased. However, wild oat's competitive ability with wheat was not affected by the P fertilizer. The results suggest that fertilizer management strategies that favor crops over weeds might deserve greater attention when weed infestations consist of species known to be highly responsive to higher soil P levels. The information gained in this study could be used to advise farmers of the importance of strategic fertilizer management in terms of both weed management and crop yield.     

Hypolipemic and hypoglycemic effects of total triterpenoids from Psidium guajava leaves on type 2 diabetic rats

AIM: To investigate the effects of total triterpenoids from Psidium guajava leaves (TTPGL) on blood glucose and lipids in type 2 diabetic rats. METHODS: The diabetic rats were induced by intraperitoneal injection of streptozotocin at dose of 35 mg/kg and feeding with high-fat diet. The animals were divided into 5 groups: diabetic model control group (model), TTPGL treatment groups (with the doses of 60, 120 and 240 mg/kg, respectively) and rosiglitazone treatment group (3 mg/kg). Another 12 normal SD rats were used as the normal controls. The rats received daily treatment for 6 weeks, and then the levels of fasting blood glucose (FBG), fasting insulin (FINS), triglyceride (TG), total cholesterol (TCH), free fatty acid (FFA), glycosylated hemoglobin (GHb) and glycosylated serum proteins (GSP) were measured. The protein expression of peroxisome proliferator-activated receptor γ (PPARγ) in adipose tissues was detected by Western blotting. RESULTS: Compared with normal control group, the levels of FBG, GHb and blood lipids were increased in type 2 diabetic rats. The FINS, insulin sensitivity index, and the protein expression of PPARγ in adipose tissues were decreased. Compared with model group, the levels of FBG and GSP were decreased,and the FINS, insulin sensitivity index, and the protein expression of PPARγ in adipose tissues significantly increased in TTPGL treatment groups (with the doses of 120 and 240 mg/kg). The levels of serum TG,TCH and FFA were significantly lower in TTPGL treatment groups (P<0.01 or P<0.05) as compared with the model controls. CONCLUSION: TTPGL decreases the levels of blood glucose and lipids in diabetic rats. TTPGL also increases serum insulin level and improves insulin sensitivity. The action mechanism of TTPGL may be related to the increase in the protein expression of PPARγ.