Determination of iron absorption by rat bioassay. Evaluation of methods of dosing59Fe on radioiron absorption from plant diets

We studied the potential of an animal model to predict nonheme iron absorption in humans and tested a feasible and easy technique of dosing⁵⁹Fe to evaluate bioavailability of dietary nonheme iron. Plant diets containing about 20 ppm or 75 ppm iron were the nonheme iron sources with ferrous sulfate (75 ppm) as a reference. Radioiron was administered by (a) gavaging in water, 1 h after a meal; (b) mixing with the meal; and (c) making a slurry with the meal and gavaging. No significant differences were found (P0.05) in⁵⁹Fe absorption among the three methods of administering radioiron. Absorption of⁵⁹Fe was similar to apparent iron absorption for all diets tested, whether the animals consumed the same diet as that of the test meal or a different diet. A high correlation (r=0.88) obtained between the apparent iron absorption and⁵⁹Fe iron absorption for different dosing techniques, indicates that extrinsic iron tag administered by any of these methods is valid to measure nonheme iron absorption. Apparent iron absorption values determined by rats fed 20 ppm or 75 ppm dietary iron from plant sources were similar to reported values for humans. It is concluded that the normal adult rat is an appropriate model to study iron bioavailability of human foods when iron status, maturity, iron intake relative to requirement, and method of measurement are similar to the human situation.     

Effect of addition of bovine milk and vegetable milks on thein vitro availability of iron from cereal meals

Studies were carried out on thein vitro availability of iron from a standard cereal meal with and without the addition of bovine milk (BM), groundnut milk (GM) and soybean milk (SM). Further, availability of iron from these milks per se was also investigated. Estimation of the total iron content from BM, GM, and SM revealed that it was highest in case of SM followed by GM and BM. This trend was reversed for percent available iron which was highest for BM followed by GM and SM. Thein vitro availability of iron from the cereal meal was low (3.7%). Addition of BM and GM enhanced the availability of iron from the standard meal whereas SM had no particular enhancing quality. The practical implications of the findings for iron nutrition in humans are discussed.     

喷施KH2PO4对孕穗期低温胁迫下小麦叶片抗氧化特性与幼穗冻害的影响

为探讨低温胁迫发生前叶面喷施磷酸二氢钾(KH2PO4)对小麦小穗发育及旗叶生理特性的调节作用,以烟农19(冬性,低温不敏感型)和新麦26(半冬性,低温敏感型)为材料,利用盆栽试验,在小麦孕穗期于人工气候模拟箱内进行低温(2℃和-2℃)胁迫,并在低温处理前叶面喷施0.2％KH2PO4溶液,低温结束后分析了小麦幼穗冻害发生...     

皂化麦麸对重金属Cd~(2+)的吸附作用及吸附机理研究

为扩大纤维素类生物吸附剂的开发利用资源,采用五因子二次回归正交旋转组合设计方法对影响皂化麦麸吸附Cd2+的因子进行优化,得出在吸附时间为1h、加入量为0.20g、pH=6、温度20℃、浓度2.00mg·L-1时,皂化麦麸有最大吸附率(YMax=99.19%)。对比试验表明,皂化麦麸对Cd2+的吸附优于活性炭,纤维素在吸附中起主要作用。扫描电镜下皂化麦麸表面显示粗糙和多褶皱的物理吸附特征,红外光谱显示皂化麦麸中-OH、-CH3、C≡C、C=C、C=O、C-O基团可能参与吸附作用。吸附等温线和吸附动力学模型显示,皂化麦麸对Cd2+吸附符合Freundlich等温式和二级动力学模型。皂化麦麸经过解吸附可以反复使用。     

玉米C_4光合酶基因导入对拟南芥光合特性及抗旱性的影响

为了解玉米C_4型光合酶基因对C3植物拟南芥光合特性的影响及其对干旱胁迫的响应,分别以过表达ZmPEPC(磷酸烯醇式丙酮酸羧化酶)、ZmPPDK(丙酮酸磷酸二激酶)和ZmNADP-ME(依赖于NADP的苹果酸酶)单个酶基因的拟南芥株系(分别简写为PC、PK、ME),以及过表达PEPC+PPDK和PPDK+NADP-ME两个酶基因的拟南芥株系(分别简写为PCK、PKM)为供试材料,在开花期停止浇水,并分别于干旱胁迫处理前1天、第5天、第10天和结束干旱胁迫复水处理5d时测定转基因拟南芥中目标基因的表达量、光合速率、水分利用效率和酶活性。结果表明,在正常生长条件下,PCK类型株系的PEPC酶活性、PPDK酶活性、净光合速率(Pn)以及水分利用效率(WUE)较野生型拟南芥分别高52%、20%、24%和55%,除PPDK酶活性外,PCK类型株系各指标测定值的增幅均高于其他转基因类型株系,综合表现最优。不同类型株系的上述测定指标总体表现为PCKPCPK、PKMME。干旱胁迫处理5d时,各类型株系中目标基因的表达量、光合酶活性、Pn和WUE均有所上升。干旱胁迫处理10d时,拟南芥受到严重损伤,上述指标的测定值均下降。复水5d时上述指标得到不同程度的恢复,不同类型转基因株系的各项测定指标在不同干旱胁迫处理中总体仍表现为PCK最优,PC次之。各转基因株系均优于受体非转基因拟南芥。     

肥料增效剂对夏玉米植物学性状、产量构成及土壤中NH4+-N和NO3--N的动态影响

2014、2015年夏季,试验采用单因素随机区组设计,以先玉335为材料,设置两种肥料增效剂、7种施肥方式,研究大喇叭口期和抽雄期植物学性状、施肥后0、14、28、42 d时0~30 cm和31~60 cm土壤中NH_4~+-N和NO_3~--N含量以及收获时玉米穗部性状和产量差异。结果表明,分期施肥比全部氮肥作底肥更能促进夏玉米茎粗、叶面积、气生根数量、穗长、穗行数和行粒数等增加。与对照和不施用肥料增效剂相比,0~30 cm和31~60 cm土层中施用两种肥料增效剂的NH_4~+-N含量较高,NO_3~--N含量较低,控制了NH_4~+/NO_3~-比例。两种肥料增效剂相比,Entrench效果明显优于NMAX。