茶树对铝的吸收、积累特性及饮茶安全性评价

茶树是典型的富铝植物,茶又是深受人们喜爱的饮品,而铝是一种对人体健康有害的金属元素,饮茶是否会导致人体铝中毒引起人们高度关注。本文详细阐述了茶树对铝的吸收和积累特性,分析了茶汤中铝的溶出量、溶出形态及生物可给性,阐明了科学饮茶是健康安全的,并提出了合理有效的茶叶降铝措施。     

湖南冬闲田马铃薯氮吸收分配规律研究

试验采用“3414”设计方案，分析冬闲田马铃薯在不同肥料水平下氮肥吸收分配规律。结果表明：马铃薯地上部全氮含量在全生育期间其动态变化呈现为苗期低，块茎形成期高，而在块茎成熟期缓陧下降的趋势，且在整个生育期内，氮素浓度的变化表现为地上部〉块茎；块茎中氮的含量均在块茎形成期最高，块茎成熟期下降。     

不同马铃薯品种铜素的吸收、积累和分配

以紫花白、陇薯3号、大西洋为材料,对不同马铃薯品种的铜素吸收、积累、分配规律进行了研究。结果表明,生育期间马铃薯全株平均铜含量为11.62 mg/kg。叶片中铜素累积吸收量陇薯3号呈S型曲线变化,紫花白、大西洋呈抛物线趋势变化;茎中表现为紫花白、陇薯3号呈渐增趋势,大西洋则变化平稳;全株和块茎中的铜素累积吸收量随生育进程的推进逐渐增加。各器官铜素累积吸收量均表现为陇薯3号>紫花白>大西洋。淀粉积累期是吸铜最多、最快的时期。全生育期平均,铜在叶、茎、块茎中的分布分别为28.44%～39.23%、10.67%～18.68%、42.10%～60.89%。收获时马铃薯体内的铜素运转率为77.85%～94.61%。每生产1 000 kg鲜块茎平均吸收铜3.83 g,消耗系数平均为0.0015,生产效率平均为265.21。     

马铃薯硫素吸收规律的初步研究

通过田间试验和室内测定分析,研究了马铃薯硫素吸收规律。结果表明:马铃薯全生育期内各器官含硫量始终以叶片最高,茎秆其次,块茎最低;全株硫的累积吸收量随生育进程的推进呈二次曲线变化,在淀粉积累期硫素累积量达到最大值;块茎形成至块茎增长期是马铃薯一生中硫素吸收速率最快、吸收数量最多的时期;生育期间硫素在马铃薯各器官的分配随着生长中心的转移,发生相应的变化,块茎增长期之前叶片中分配最多,其次为茎秆,块茎中最少,之后则是块茎中最多,茎秆其次,叶片中最少;硫在叶片中的分配率随生育进程逐渐降低,块茎中硫的分配率则为直线增长,茎秆中硫的分配率变化表现为单峰曲线,峰值出现在块茎形成期。本试验产量水平下,每生产500kg块茎需要吸收硫0.13kg。     

不同施砷量对烤烟砷吸收、积累及分布的影响

采用盆栽试验研究了不同施砷量对烤烟砷吸收、积累和分布的影响,结果表明,土壤中施砷可增加烤烟对砷的吸收,提高其富集系数,导致地上部、地下部、烟灰和烟气中砷的积累,且随着土壤中施砷量的增加而提高,但施砷可降低烤烟的位移系数,即降低由地下部向地上部运输砷的能力.砷能分布在烤烟的各个部位,在烤烟各器官中的分布规律为:根>下部叶>茎>中部叶>上部叶.     

用外翻肠囊法研究高钙条件下有机锰在肉仔鸡小肠中的吸收特点

本试验用外翻肠囊法研究高钙对肉仔鸡不同肠段(十二指肠、空肠和回肠)吸收不同形态锰的影响,以比较有机锰和无机锰在高钙条件下吸收特点的差异。采用单因子完全随机设计,培养液中添加的4种锰源分别为:硫酸锰、弱络合强度的蛋氨酸锰(Mn-MetE)、中等络合强度的氨基酸锰(Mn-AAA)和强络合强度的氨基酸锰(Mn-AAB)。为了扣除内源的影响,设置1个零添加锰水平处理。将40只31日龄AA肉公鸡随机分到以上5个组,每组8个重复,每个重复1只鸡,每只鸡的十二指肠、空肠和回肠分别作为相应肠段外翻肠囊的一个重复。结果表明:1)体外培养回肠肠囊对锰的吸收率显著高于十二指肠(P<0.01);2)回肠肠囊对强络合强度的Mn-AAB中锰的吸收率显著高于硫酸锰或中等络合强度的Mn-AAA(P<0.05)。本试验结果表明:在高钙条件下,络合形态的有机锰在体外培养的肉仔鸡肠囊中的吸收率显著高于无机形态的锰;强络合强度有机锰源中的锰能更强地抵抗小肠内的解离,比弱或中等络合强度的有机锰源更有利于锰的吸收。     

Hyaluronidase administered with xylazine–tiletamine–zolazepam into adipose tissue shortens recovery from anesthesia in pigs

Objective

To evaluate the effect of hyaluronidase on uptake, duration and speed of elimination of xylazine–tiletamine–zolazepam administered in the subcutaneous fat over the dorsal lumbar region of swine.

Optimal dietary alpha‐linolenic acid/linoleic acid ratio improved digestive and absorptive capacities and target of rapamycin gene expression of juvenile grass carp (Ctenopharyngodon idellus)

Growth performance, digestive and absorptive capacities and target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6K1) and eIF4E‐binding protein (4E‐BP) gene expression in the hepatopancreas and intestine of juvenile grass carp (Ctenopharyngodon idellus) fed graded ratios of dietary alpha‐linolenic acid/linoleic acid (ALA/LNA) (0.01, 0.34, 0.68, 1.03, 1.41, 1.76 and 2.15) for 60 days were investigated. The results showed that ALA/LNA ratio of 1.03 significantly improved (i) per cent weight gain (PWG) and feed efficiency, (ii) hepatopancreatic trypsin, chymotrypsin, lipase, amylase and intestinal creatine kinase (CK) activities, (iii) hepatopancreatic trypsinogen‐2 and chymotrypsinogen mRNA levels. Meanwhile, fish fed with ALA/LNA ratio of 0.68 significantly enhanced, (iv) Na⁺/K⁺‐ATPase and γ‐glutamyl transpeptidase activities in whole intestine, and alkaline phosphatase activities in the proximal intestine (PI) and distal intestine, (v) amylase, intestinal Na⁺/K⁺‐ATPase alpha‐subunit isoform 1, Na⁺/K⁺‐ATPase alpha‐subunit isoform 8 and CK mRNA abundances, (vi) TOR and S6K1 gene expression in the hepatopancreas and intestine of juvenile grass carp. Based on the quadratic regression analysis of PWG, cholecystokinin and leptin contents in the PI, optimal dietary ALA/LNA ratio of juvenile grass carp (8.78–72.00 g) was estimated to be 1.08, 1.19 and 1.05, respectively.     

Dietary calcium requirement in fishes

The dietary requirement of calcium (Ca) has been well established in terrestrial animals. However, investigations for dietary Ca requirement in fish are complicated and reports limited as fish can use waterborne Ca in addition to dietary Ca. Ca absorption in fishes from environmental water is species specific and depends on concentration of Ca in rearing environment and availability of dietary Ca. Ca and phosphorus are generally combined together in fish body therefore maintaining a dietary calcium: phosphorus ratio is important. Ca exists in a complex form in fish meal, which is not available to fishes; hence, although fish meal contains an appreciable amount of calcium, dietary Ca supplementation in fish meal‐based diets for some species is necessary. This review article summarizes and discusses pertinent information on absorption of Ca from water, essentiality of dietary Ca, bioavailability of Ca from different sources, optimum calcium:phosphorus ratio and dietary Ca requirement in fishes.