真江蓠对氨氮去除效率与吸收动力学研究

以真江蓠(Gracilaria asiatica)为实验材料,在实验室水平上测定了真江蓠培养密度对NH4-N去除效率和吸收速率的影响,比较了真江蓠在氮半饥饿和氮饱和状态下的氨氮吸收动力学特征以及不同起始浓度NH4-N对其吸收速率的影响.结果表明:真江蓠密度为2～24 g·L-1时,5 h内随着藻体密度增大和实验时间延长,真江蓠去氨氮能力也增强.当藻体密度为24g·L-1时,真江蓠在5 h内去除氨氮效率最高,达到99.77%.各种藻体密度在起始阶段保持较高吸收速率(30～41 μmol·g-1·h-1),随后藻体密度与吸收速率呈反比关系,其最低藻体密度组(2 g·L-1)在3 h和5 h吸收速率最大,分别为28.33 μmol·g-1·h-1和18.85μmol·g-1·h-1.在起始浓度梯度实验中,氮半饥饿和氮饱和真江蓠吸收氨氮的最大吸收速率和半饱和常数在1 h均达到最高值,分别为116.47、159.40μmol·g-1·h-1和439.70、913.61 μmol·g-1·h-1.之后随着培养时间的延长而降低.氮半饥饿和氮饱和真江蓠对NH4-N的吸收差别不显著;当氨氮浓度为300～500μmol·L-1时,氮半饥饿的真江蓠在起始1 h内有一个快速吸收阶段(40.7～102.1μmol·g-1·h-1),吸收速率与NH4-N浓度几乎成正比,此时不符合米氏动力学饱和方程,而在低N浓度下(100～200μmol·L-1),藻体对NH4-N的吸收则没有出现这种现象;随着培养时间延长,直到NH4-N浓度达到一定限度时,吸收速率可达到一极大值而符合米氏动力学饱和方程.该研究结果为大规模栽培真江蓠净化水体和生态修复提供了理论依据.     

Resistance breeding and biocontrol of Striga asiatica (L.) Kuntze in maize: a review

Purpose: The aims of this article are to highlight pre-breeding procedures for identifying primary sources of Striga-resistance genes and to summarize complimentary breeding techniques that enhance partial resistance of maize varieties against Striga species.

Materials and methods: The paper presented a comprehensive account of Striga screening and controlling techniques and highlighted the potential of integrating partial resistance with FOS to boost maize production and productivity in SSA.

Results: Striga infestation is a major constraint to maize production and productivity in Sub-Saharan Africa (SSA). A lack of Striga-resistant maize varieties and the limited adoption of other control methods hinder effective and integrated control of the parasitic weed in maize and related cereal crops globally. Genetic resistance of maize should be complemented with the use of Fusarium oxysporum f.sp. strigea (FOS), a biocontrol agent known to suppress Striga.

Conclusions: A combined use of genetic resistance and FOS has remained largely unutilized in controlling Striga in Africa. A combination of conventional and molecular Striga-resistance breeding tools as well as the use of FOS are promising methods to effectively control Striga in SSA.     

江西道地药材车前中氮磷钾的积累转运规律研究

分别用凯氏定氮法、钒钼黄比色法和火焰分光光度法测定车前不同生育期及各器官中N、P、K的含量。结果表明:车前植株中N、P、K含量为K>N>P;整个生育期间,根系吸收的氮首先在叶片中积累,然后逐渐转移到穗和种子中;而钾首先送往叶柄,当穗尚未形成时,在根系中积累,而后再转移至其它器官;P在种子形成前转移率不高,随着种子的形成而大量积累。说明不同生育期车前植株各器官中N、P、K的转移规律不同。     

车前草多糖的结构和性质初探

从车前草中提取、分离纯化得到多糖组分PPII-a,并对其组成结构和性质进行分析。车前草经热水提取、DEAE-Sepharose F.F柱层析、Superdex-200柱层析得到车前草多糖PPII-a,经HPLC、UV、IR、比色、β-消去等方法对其组成结构及理化性质进行测定。结果表明:PPII-a为均一组分,相对分子质量为4.6×105Da,其总糖含量、蛋白含量、糖醛酸含量分别为90.5%、9.7%、20.9%,单糖组成及摩尔比为阿拉伯糖∶甘露糖∶葡萄糖∶半乳糖=7.6∶1∶1.8∶1.9;呈现多糖特征吸收峰,含有β-吡喃糖苷键。β-消去实验结果表明,糖链与结合蛋白之间是通过O-型糖肽键相连。因此,PPII-a是一种均一的具有O-糖肽键的酸性杂多糖。     

Effects of dietary Centella asiatica (L.) Urban on growth performance,nutrient digestibility,blood composition in piglets vaccinated with Mycoplasma hyopneumoniae

To investigate the effects of Centella asiatica (L.) on growth performance, nutrient digestibility and blood composition in piglets, 32 nursery pigs were fed 0.0, 0.5, 1.0 and 2.0% dietary C. asiatica (L.) from 15 to 90 kg BW. At 30 kg BW, nutrient digestibility was measured and at 35 kg BW piglets were vaccinated with Mycoplasma hyopneumoniae. Hematological parameters were checked at 40 and 80 kg BW. Compared with the control, growth performance was not affected. The ether extract, ash and calcium digestibility were lower at 0.5%, and dry matter, crude protein, crude fat, phosphorus and energy digestibility were lower at 1.0% (P < 0.05). On hematological values, at 40 kg hematocrit, total white blood cells, neutrophils, eosinophils, basophils, monocytes and lymphocytes were higher at the 2.0% level (P < 0.05). Most of these values except basophils and monocytes continued until at 80 kg, at which total white blood cells, neutrophils, eosinophils and lymphocytes were higher even at 1.0% (P < 0.05); neutrophil‐to‐lymphocyte ratio tended to be higher at 2.0% (P < 0.03). Cholesterol, triglycerides and antibody levels against M. hyopneumoniae did not differ except that at 40 kg the cholesterol of 0.5% was lower (P < 0.05) and M. hyopneumoniae‐specific antibodies tended to be higher with increasing levels of C. asiatica (L.) (P < 0.07). The result that C. asiatica (L.) could not improve growth performance but increased values of serum hematocrit and white blood cells, and mycoplasma immunity to M. hyopneumoniae might suggest that C. asiatica (L.) has no function to elevate body weight but has the potential to enhance innate immunity.     

月鳢食性的初步研究

通过对２４尾鳢食性的研究表明,体长在９．２￣２０．０ｍｍ的仔鱼,主要以枝角类１桡足类和摇蚊幼虫为食,体长在２１ｍｍ以上的幼鱼及成鱼主要以小型鱼类、虾为食、属动物性食性和摄食率和饱满指数随季节变化而变化,以夏季最高,冬季最低。     

中药材飞龙掌血研究进展

综述了飞龙掌血中香豆素、生物碱、挥发油、甾醇、树脂和三萜类化合物共六大类化学成分的研究成果,并介绍了近20年来发现的飞龙掌血抗肿瘤、升压、抗凝血、抗炎镇痛、扩血管、抑制流感病毒复制、解痉挛和利尿等药理活性,为我国丰富飞龙掌血资源的开发利用提供了新的思路。     

东亚唐棣组织培养体系1）

以东亚唐棣带芽茎段为外植体,研究了不同消毒方法对于无菌体系建立的影响、不同类型的芽对于诱导萌发的影响、不同基本培养基以及激素组合对于增殖与生根的影响。结果表明：较为适合东亚唐棣消毒的方法为75％酒精消毒30 s,0．1％HgCl2消毒8 min,萌发率为16．7％;带有一侧芽的顶芽为较为合适的外植体,萌发率可达87．6％;最适增殖培养基为MS＋6－BA 3．0 mg· L－1＋NAA 0．1 mg· L－1,增殖系数可达4．8;最适生根培养基为1／4MS＋NAA 0．1 mg· L－1。     

不同营养盐浓度对3种大型红藻氮、磷吸收及其生长的影响

在实验室条件下,以3种大型红藻真江蓠(Gracilaria asiatica)、脆江蓠(Gracilaria chouae)和蜈蚣藻(Grateloupiafilicina)为实验材料,研究不同营养盐浓度下这3种海藻对氮、磷的吸收和生长情况。结果表明,3种大型海藻对水体中硝酸盐和磷酸盐的吸收效果明显,并符合一级动力学方程。比较前24 h对氮的平均吸收速率,真江蓠和脆江蓠在50μmol/L组出现最大值,分别为0.739μmol/(g.h)和0.648μmol/(g.h),蜈蚣藻在20μmol/L组出现最大值0.614μmol/(g.h);比较前24 h对磷的吸收速率,真江蓠和脆江蓠在1.0μmol/L组出现最大值,分别为0.015μmol/(g.h)和0.018μmol/(g.h),蜈蚣藻在0.7μmol/L组出现最大值0.016μmol/(g.h)。结合去除速率常数来看,脆江蓠对硝酸盐和磷酸盐有更好的去除效果。营养盐的起始浓度对脆江蓠、真江蓠和蜈蚣藻的生长具有明显的影响。在所有的实验浓度下,8 d后的湿重均为脆江蓠增加最大,蜈蚣藻增加最小;并且改变硝酸盐的浓度比改变磷酸盐的浓度更能刺激蜈蚣藻的生长。     

基因枪作用下的外源GUS基因在四种红藻组织块中的瞬间表达

建立合适的外源基因转移系统是大型海藻基因工程的一个重要研究内容。外源基因在大型海藻组织中的瞬间表达可以确定外源基因是否导入海藻组织及研究影响导入的各种因素,以此来建立合适的ＤＮＡ导入系统。迄今,秦松等［１９９４］对海带的遗传转化进行了研究,用基因枪将...