粘性红圆酵母XJU-1产β-胡萝卜素的研究

目的:从粘性红圆酵母Rhodotorula mucilaginosaXJU-1中提取β-胡萝卜素并对其特性加以研究。方法:采用酸热法对发酵产物破壁,用丙酮∶石油醚(1∶1)萃取β-胡萝卜素,采用GB/T 5009.83-2003的HPLC方法测定β-胡萝卜素含量,以448nm波长的紫外分光光度吸收值计算出色素损失率来探讨β-胡萝卜素的稳定性。结果:该菌株在液体发酵培养基中生长72hβ-胡萝卜素含量高达389.2μg/g干重,经实验确定,葡萄糖是最有利于β-胡萝卜素生成的碳源;蛋白胨是生产β-胡萝卜素的最佳氮源。提取的β-胡萝卜素耐热性较好,需置于暗处保存。结论:该菌种β-胡萝卜素产率明显高于国内外已报道的,有很好的开发前景。     

高效液相色谱法测定蔬菜中β-胡萝卜素的不确定度评定

建立高效液相色谱法测定蔬菜中β-胡萝卜素（β-carotene）的不确定度评定数学模型,计算β-胡萝卜素测量结果的不确定度。胡萝卜和菠菜中β-胡萝卜素的扩展不确定分别为0.684和0.444 mg/100g,k=2,P=95%。影响β-胡萝卜素HPLC法测定的不确定度来源主要是样品均匀性、前处理过程及HPLC仪器定量重复性,不确定度评定有利于完善测定结果的准确性。     

丝状真菌SC－2产β－胡萝卜素的研究

利用改良的ＳＭＡ培养基富集培养从植物的落花上分离筛选出的产β─胡萝卜素的菌株ＳＣ—２。该菌株在以棉籽饼粉为主要原料的培养基上生长良好。最高生物量达５４ｍｇ干菌体／ｍｌ培养液。胡萝卜素含量１．８５ｍｇ／ｇ干菌体。ＨＰＬＣ测定β─胡萝卜素占总胡萝卜素的９０．５％。     

HPLC法测定南瓜中β-胡萝卜素

目的：建立高效液相色谱法（HPLC）测定南瓜中β-胡萝卜素含量的方法,并对12份南瓜样品中β-胡萝卜素含量进行测定。方法：色谱柱：Eclipse XDB-C18柱（4.6mm×250mm,5μm）;流动相：水（A）+丙酮（B）;检测波长：450nm。结果：南瓜中β-胡萝卜素在35 min内得到较好分离,重复性好（RSD=5.11%）,精密度高（RSD=0.70%）,稳定性好（RSD=2.73%）,加标回收结果准确可靠（RSD=2.06%）。12份南瓜样品中β-胡萝卜素含量差异较大（8.9～94.4 μg/g）,印度南瓜16296-1中β-胡萝卜素含量最高,其次为中国南瓜9132、印度南瓜16291-2和16167-8,这3种南瓜中β-胡萝卜素含量较接近（均≥76 μg/g）,含量最低的为印度南瓜16185-6。结论：建立了一种快速测定南瓜中β-胡萝卜素的高效液相色谱方法,该方法准确、可靠;12份南瓜样品中β-胡萝卜素含量差异较大。     

发酵法生产β-胡萝卜素菌丝体中氨基酸含量的分析

采用日立８３５－５０型氨基酸分析仪,测定了发醇法生产的β－胡萝卜素菌丝体及提取β－胡萝卜素后剩余的菌渣中氨基酸含量,结果表明：在氨基酸总含量中,必需氨基酸含量较高;在β－胡萝卜素菌丝体、菌渣中,赖氨酸含量较高,谷氨酸含量最高。     

光合细菌H3菌株色素分析

H3菌株系由盐田微生物层中分离获得的光合细菌株。具有丰富的天然色素。经活细胞色素光谱吸收峰值测定,色素经有机溶剂提取、硅胶薄板层析、SDS－PAGE电泳等,结果表明H3菌株的主要色素包括细菌叶绿素a、细菌脱镁叶绿素（Bacteriophaeophytin）和三种类胡萝卜素。总胡萝卜素含量占细胞于重的0．6％,胡萝卜素蛋白复合体的分子量约11,000.培养条件的差异对色素形成及相对含量有不同程度的影响。     

丝状真菌SC—2产β—胡萝卜素的研究

利用改良的ＳＭＡ培养基富集培养从植物的落花上分离筛选出的产β－胡萝卜素的菌株ＳＣ－２。该菌株在以棉籽饼粉为主要原料的培养基上生长良好。最高生物量达５４ｍｇ干菌体／ｍｌ培养液。胡萝卜素含量１．８５ｍｇ／ｇ干菌体。ＨＰＬＣ测定β－胡萝卜素占总胡萝卜素的９０．５％。     

丝状真菌SC－2产β－胡萝卜素的研究

利用改良的ＳＭＡ培养基富集培养从植物的落花上分离筛选出的产β─胡萝卜素的菌株ＳＣ—２。该菌株在以棉籽饼粉为主要原料的培养基上生长良好。最高生物量达５４ｍｇ干菌体／ｍｌ培养液。胡萝卜素含量１．８５ｍｇ／ｇ干菌体。ＨＰＬＣ测定β─胡萝卜素占总胡萝卜素的９０．５％。     

紫草提取物的体外抗氧化活性研究

为研究紫草色素(LEP)的体外抗氧化活性,采用常规回流方法提取LEP,测定了LEP对超氧自由基(O2)和1,1-二苯基-2-苦苯肼自由基(DPPH.)的清除能力,及其对β-胡萝卜素/亚油酸自氧化体系的抑制作用。结果表明,LEP对DPPH.和O2均有较强的清除能力,并且对β-胡萝卜素/亚油酸自氧化体系有明显的抑制作用,说明紫草的药理作用可能与LEP较强的抗氧化能力有关。     

湛江常见野菜安全可食性探讨

对湛江野菜所含的硝酸盐、维生素C、胡萝卜素及氨基酸进行了测定和分析。结果表明,刺苋和野当归富含维生素C和胡萝卜素,硝酸盐含量较低,实为品质上乘野蔬。东风菜和枸杞虽然胡萝卜素含量很高,但前者维生素C和氨基酸含量较低,后者硝酸盐含量已超过三级蔬菜标准。不宜大量食用。其余几种野菜营养成分比传统蔬菜高,属于安全食用性野菜。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).