Intraspecific Variation of Floral Scent Chemistry in Magnolia kobus DC. (Magnoliaceae)

Magnolia kobus was examined at 32 sites in Japan (109 female-stage flowers from 52 plants) by GC-MS. Major chemical compounds (a total of 36 chemicals) emitted from the flowers were: linalool (and its oxides), limonene, cis- and trans-β-Ocimene, benzaldehyde, benzyl alcohol, benzyl cyanide, and 2-aminobenzaldehyde. Linalool and its oxides were the most abundant components of floral scents in 21 individuals. The rate at which chemical volatiles were emitted ranged from 0.002 to 0.929 μg/flower/hour (average 0.211). High quantitative and qualitative variation in floral scent chemistry among individuals was found throughout the range of M. kobus, especially in central Honshu. The high variability in floral scent chemistry may be due to the importance of visual cues in the reproductive biology of M. kobus which flowers in early spring, resulting in decreased selection for specific floral scent profiles. Alternatively, different scent compounds or chemical profiles may be equally effective in attracting pollinators. Received 25 June 2001/ Accepted in revised form 25 August 2001     

Antibiotics,Sugars, and Amino Acids in Nectar of Rhododendron and Piptanthus Species from Nepal

Nectars were extracted in Helambu and Langtang Nepal Himalayas from Rhododendron arboreum and Rh. barbatum (Ericaceae), and from Piptanthus nepalensis (Fabaceae), and analyzed for sugars, amino acids, and antibiotic activity. Sugar content in Rhododendron nectar varied from 17 to 65%. In most nectars, G and F were present in a 1:1 ratio. In addition, from a Rh. arboreum nectar, S could be detected. Piptanthus nectar showed a very high sugar content (up to 80%), F and G, or F, G, and S, respectively, being the main sugar constituents. In all Rhododendron nectar amino acids could be found. In Piptanthus nectar there were no traceable amino acids. Neither an evolutionary significance of amino acid contents in floral nectar nor their close correlation with bees, the main pollinators of both genera, could be confirmed from our studies. Rhododendron nectar showed antibiotic activity due to the presence of acetylandromedol. The biological significance of acetylandromedol, the main toxic principle from Rhododendron nectar, seems to be its antibiotic activity, which could possibly compensate for lower sugar contents in preventing bacterial growth.     

Tropical Bees (Trigona hockingsi) Show No Preference for Nectar with Amino Acids

We offered Australian tropical stingless bees (Trigona hockingsi) artificial nectar (30% sucrose w/v) either with or without added amino acids (3.30 mM). Bees showed no preference for nectar type, suggesting that sugars, rather than amino acids, play a greater role in nectar choice by this species.     

Intraspecific Morphological Variation Among Populations of Pratylenchus brachyurus and P. coffeae

Three populations of Pratylenchus coffeae and two of P. brachyurus, each originating from a single female, were maintained on Citrus spp. or Solanum nigrum L. for several years under greenhouse conditions. Nematodes were extracted from roots, and adult female specimens were killed, fixed, and mounted in glycerine for microscopic study. Variables measured were distance between vulva and anus and lengths of the stylet, posterior uterine sac, and tail. The mean data and coefficients of variability suggest that styler length had the least variability, and length of posterior uterine sac the most. When males and distinct spermathecae are not evident in P. coffeae populations, the species can he distinguished from P. brachyurus by a shorter mean stylet length, longer mean posterior uterine sac length, and much longer distance between the vulva and anus.     

Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited

Two samples of ammonoids belonging to the Oppeliidae, Sublunuloceras virguloidesHecticoceras (Brightii) canaliculatum, are analyzed to estimate the intraspecific variability of embryonic shell features. The study of embryonic shell characters reveals two main shapes of protoconch, flattened and round. Prosiphons may be straight or slightly curved. New parameters for area are added to the linear parameters commonly found in the literature. Prosiphon length and caecum area vary greatly whereas protoconch and ammonitella diameter vary only slightly, and the ammonitella angle is almost constant. The protoconch-to-ammonitella size ratio behaves differently in each species, suggesting different patterns of embryonic growth. We compare our results with published data and discuss their significance for species determination and ontogenetic interpretation. The main finding is that intraspecific embryonic variation is greater than was previously believed.     

江华苦茶资源的氨基酸组分含量及组成分析

以江华苦茶群体资源为实验材料,用高效液相色谱法,分析检测53个单株的18种氨基酸组分的含量,并对所得数据进行必要分析。结果表明,18种氨基酸组分的含量在不同单株间差异很大,整体变异系数较大,资源变异类型较多,在育种上的选择范围大;对茶树资源中含量较高五个组分进行相关关系分析,发现茶氨酸含量与大量氨基酸含量间存在极显著相关关系,茶氨酸含量与氨基酸总量间存在极显著相关关系,大量氨基酸含量与氨基酸总量之间存在极显著相关关系。     

615小鼠血红蛋白α链的氨基酸组成及个别肽段的氨基酸序列

用CM-Cellulose-23柱层析分离纯化了615小鼠珠蛋白α链,测定其N端氨基酸残基为缬氨酸.615小鼠珠蛋白α链含有141个氨基酸残基,其中19个亮氨酸残基,10个组氨酸残基,9个缬氨酸残基,上述氨基酸残基的数目与文献中其亲本C₅₇BL不同.用胰蛋白酶水解615小鼠珠蛋白α链,发现有不溶性的‘核心’和可溶性的酶解片段.其中一个酶解肽段从N端数第8位氨基酸残基发生了突变,由亲本的缬氨酸变为亮氨酸.     

吊瓜籽中氨基酸质量分数的测定

样品吊瓜籽经酸水解处理,应用氨基酸分析仪进行分析,结果表明,吊瓜籽含所有常规17种氨基酸,质量分数高达23.28%,其中谷氨酸(G lu)和精氨酸(Agr)质量分数达4.39%和3.88%。     

氨基酸分析法快速测定梭曼中毒后大鼠脑组织中兴奋性氨基酸的含量

建立一种快速、准确、可靠的脑内兴奋性氨基酸定量检测方法 ,并观察梭曼惊厥后大鼠脑组织中兴奋性氨基酸(EAAs)含量变化。采用 6 30 0黄金系统氨基酸分析仪 ,在锂柱 130min程序生理体液分析方法基础上 ,根据兴奋性氨基酸(EAAs)的特性 ,建立了EAAs的快速测定方法 ,并用此方法对梭曼惊厥后不同时相大鼠的新鲜脑组织进行定位检测。梭曼诱发惊厥后大脑皮质和海马内谷氨酸和天冬门氨酸水平显著下降。惊厥 30min时谷氨酸下降最明显 ,分别是正常组的 5 3.2 %和 5 2 .8%。天门冬氨酸更易受梭曼中毒的影响 ,惊厥后 5、30、90min 3个时相点测定值均显著下降。此方法完成谷氨酸和天门冬氨酸分析的时间是 2 0min ,比原方法缩短了 110min ;且有较好的重现性 (GluCV :日内 1.86 % ,日间 2 .32 % ;AspCV :日内 1.42 ,日间 2 .48% )和回收率 (Glu 97.7% ;Asp97.3% )。兴奋性氨基酸参与了梭曼中毒性惊厥的病理生理过程。本方法定量检测兴奋性氨基酸快速、准确 ,并利于大批量样品的快速测定     

氨基酸转运载体研究进展

氨基酸转运载体是介导氨基酸跨膜转运的膜蛋白,在氨基酸营养机体细胞和神经调节过程中起着重要作用;而且,其功能异常会导致严重的氨基酸吸收和代谢障碍性疾病,也具有重要的病理学意义。本文就近年来关于中性氨基酸、酸性氨基酸和碱性氨基酸转运载体家族成员及其组织分布、分子生物学特征、生理功能和病理学意义等研究进展进行了综述。     

人胃癌组织及胃正常组织氨基酸差异研究

对 2 2例胃癌组织及其癌边组织、胃正常组织氨基酸进行了测定。发现胃癌组织氨基酸总量低于癌边组织氨基酸总量 ,癌边组织氨基酸总量又低于胃正常组织氨基酸总量。癌中组织与癌边组织相比有 8种氨基酸明显降低 ,P <0 .0 1 ;其中三种为人体必需氨基酸 ,三种为生糖氨基酸。胃癌组织与胃正常组织相比 3种生糖氨基酸明显降低 ,P<0 .0 5。结果表明 :胃癌组织存在明显的氨基酸代谢异常     

利用串联质谱鉴定氨基酸突变的生物信息学算法

氨基酸突变能够改变蛋白的结构和功能,影响生物体的生命过程.基于串联质谱的鸟枪法蛋白质组学是目前大规模研究蛋白质组学的主要方法,但是现有的质谱数据鉴定流程为了提高鉴定结果的灵敏度往往会有意压缩数据库中的氨基酸突变信息.因此,如何挖掘数据中的氨基酸突变信息成为当前质谱数据鉴定的一个重要部分.当前应用于氨基酸突变鉴定的串联质谱鉴定方法大致可以分为3大类:基于序列数据库搜索的方法、基于序列标签搜索的算法以及基于图谱库搜索的算法.本文首先详细介绍了这3种氨基酸突变鉴定算法,并分析了各种方法的特点和不足,然后介绍了氨基酸突变鉴定的研究现状和发展方向.随着基于串联质谱的蛋白质组学的不断发展,蛋白序列中的氨基酸突变信息将被更好地解析出来,从而得以深入探讨由氨基酸突变引起的蛋白结构和功能改变,为揭示氨基酸突变的生物学意义奠定基础.     

外源性MMS对小鼠脑组织游离氨基酸含量的影响

研究表时,小鼠皮下注射ＭＭＳ（中分子物质）,可使脑组织游离丝氨酸、脯氨酸、酪氨酸含量降低,丙氨酸含量增高。注射氨丙嗪能抑制此种效应,但对丙氨酸升高效应不能抑制,丙氨酸升高应属应激反应机制所引起。此研究对解释中分子物质（ＭＭＳ）对神经系统的毒性和精神分裂症的关系［１］,提供了氨基酸变化的数据。     

诺丽果与热带水果中氨基酸含量及组成对比分析

以诺丽果和16种海南常见热带水果为材料,对比分析了氨基酸含量及组成。结果表明:诺丽果含有18种氨基酸,种类齐全。其氨基酸总量、人体必需氨基酸含量和儿童必需氨基酸含量均居第1位。诺丽果的E/T值为37.13%,E/N值为0.59,符合理想蛋白质的要求。诺丽果中各种人体必需氨基酸,Val、Ile、Leu、Phe+Tyr、M et+Cys、Thr的含量占氨基酸总量的比例,与1973年FAO/WHO修订的人体必需氨基酸含量模式谱基本一致,仅Lys中度缺乏。诺丽果中鲜味类、芳香族、甜味类氨基酸含量居第1位。     

Nectar yeasts in Delphinium nuttallianum (Ranunculaceae) and their effects on nectar quality

Microorganisms colonize the nectar of many angiosperms. Variable diversity and spatio-temporal dynamics of nectar-inhabiting microorganisms (e.g., yeasts) may drive variation in nectar sugar composition and subsequent plant–pollinator interactions. We assessed yeast frequency of occurrence and density in the nectar of the perennial herb, Delphinium nuttallianum, across multiple spatio-temporal scales, including flower lifetime and sex-phase transition, flowering season, populations, and years. We tested the hypothesis that pollinators vector yeasts by comparing densities between virgin flowers and those open to visitation. Finally, we identified yeasts using molecular methods and tested for an association between yeast density and nectar composition using ultra-performance liquid chromatography. Yeasts were frequent colonists of Delphinium nectar, occurring in all populations and years sampled. Yeast frequency of occurrence and density varied across most spatio-temporal scales examined. Pollinators were vectors of yeast: virgin flowers remained yeast-free, while those open to visitation became inoculated. Nectar samples were species-poor, with a majority colonized by Metschnikowia reukaufii. Finally, increasing yeast density was correlated with a decrease in sucrose and an increase in monosaccharides. Our results document that yeasts form species-poor communities in populations of this hermaphroditic perennial, in addition to highlighting their spatio-temporal dynamics and effects on nectar quality. Spatio-temporal variation in frequency of occurrence, density, and changes in nectar may have important implications for the nature and strength of interactions between Delphinium and its pollinators.     

华南主要野生蔬菜氨基酸含量及营养价值评价

通过分析华南地区八种主要野生蔬菜的氨基酸含量,对其氨基酸营养进行评价,并和菜心进行对比,发现八种野生蔬菜除不含胱氨酸外,其它氨基酸含量均很丰富,是有利用人体氨基酸营养平衡的天然绿色食品。     

刺五加、短梗五加的花蜜分泌节律、花蜜成分及访花者多样性的比较研究

野外定位观测刺五加（Eleutherococcus senticosus）、短梗五加（E.sessiliflorus）的花蜜分泌节律、访花者的多样性,室内分析其花蜜的主要成分。结果表明,刺五加雄株的花杂在开花1－3（4)d分泌花蜜,雌株在开花5－7,6－8或7－9d分泌花蜜;短梗五加以及刺五加两性株的部分花杂,在开花后有两次分泌花蜜的过程：第1次与花药开裂散粉时间一致,第2次与柱头具可授性的时间一致。而且,刺五加和短梗五加都由动物帮助传粉,花蜜分泌的时间与多数访花者的访花时间一致,在一天之中,散出花粉的花朵分泌花蜜的时间早于接受花粉的花杂,这种时间差异应该是植物控制该 花者流向并导致传粉成功的关键。短梗五加与刺五加之间以及刺五加不同性别的植株之间,花蜜的成分及相对含量各有特点,但都以果糖和葡萄糖为主。在刺五加、短梗五加花朵上记录到的访花昆明分别为50余种和40余种,多数隶属于膜翅目、鳞翅目、鞘翅目和半翅目。其中膜翅目的胡蜂、马蜂、熊蜂,双翅目的食蚜蝇、寄蝇等是刺五加、短梗五加的常见访花者。     

三种哺乳动物初乳乳汁氨基酸含量的比较

采用高效液相色谱法分析了人、牛、猪3种哺乳动物的初乳乳汁中氨基酸含量,结果表明:谷氨酸的含量在3种哺乳动物的初乳乳汁中是最高的,而蛋氨酸的含量最低;从3种动物比较来看,猪乳与牛乳的氨基酸含量比较接近,而人乳与其他两种动物有较大的差异.