獐牙菜属植物花蜜腺形态及解剖学

在扫描电镜下观察了獐牙菜属Swertia L.10组30种植物花蜜腺的数目,位置,形态和附属物等特征;同时还利用光镜对各组代表种的蜜腺结构进行了解剖学观察。结果表明獐牙菜属花蜜腺外部形态多种多,但在组与组之间无明显间断,演化序列呈梯度变化;内部结构基本相同,为不具维管束的结构蜜腺,且均为淀粉型蜜腺。因此,从花蜜腺的角度不支持将獐牙菜属划分为小属的观点,同时,还结合其它证据讨论了花蜜腺特征的演化趋势。     

３种獐牙菜属植物花蜜腺的发育解剖学研究

獐牙菜属的红直獐牙菜、抱茎獐牙菜和四数獐牙菜３种植物花蜜腺都属花被蜜腺,其结构相似,均由分泌表皮和产蜜组织组成,为结构蜜腺,是花冠其部薄壁组织恢复分和能力形成的,分泌表皮无气孔器,原蜜汁由蜜腺周围的维管束提供,经产蜜组织加工后,由分泌表皮外薄的角质层泌出。四数獐牙菜花蜜腺裸露,凸起,而另２化蜜腺凹限为囊状、;红直獐牙菜为脱落蜜腺、而抱茎獐牙菜和四数獐牙菜为宿存蜜腺,其花蜜腺的性状基本印证了３种獐牙菜属植物的系统位置。     

四数獐牙菜的胚胎学及其系统学意义

四数獐牙菜花药四室,药壁发育为双子叶型;绒毡层腺质型。小孢子母细胞减数分裂为同时型, 四分体的排列方式为四面体形;成熟花粉为3-细胞。子房2心皮,2心皮连接处强烈内凸,4列胚珠。薄 珠心,单珠被,直生胚珠。胚囊发育为蓼型。胚乳发育为核型。胚胎发育为茄型酸浆I变型。反足细胞 在胚囊成熟时期宿存。果实成熟时,种子只发育至球型胚阶段。承珠盘存在。与已研究的獐牙菜种类 的胚胎特征相比较,该种存在三个显著的特点：直生胚珠,心皮连接处强烈内凸,承珠盘存在。这三个特 征目前仅在龙胆族中的花锚属中发现。经过性状分析,它们均是演征,此三个共有演征表明四数獐牙菜 与花锚属是一单系群,它们的亲缘关系最近。这与Yun &; Kupfer(1995)的分子证据部分吻合,因为分 子系统树上的花锚单系支包括花锚、四数獐牙菜和北美的密花属(广义獐牙菜属中的密花组),而后者的 胚胎学特征未有任何报道。胚胎学研究暗示四数獐牙菜的分类学等级有待重新评价,广义的獐牙菜属 有可能不是一单系发生群。     

7种獐牙菜属药用植物形态组织学研究

本文报道了水灵芝(Swertia davidii Franch)、双斑獐牙菜(S.bimaculata(S.et Z.)HK.f.Thoms)、江浙獐牙菜(S.hickinii Burk)、贵州獐牙菜(S.koui-tchensis Franch)、大籽獐牙菜(S.macrosperma C.B.Clarke)、翼梗獐牙菜(S.nervosa Wall)、紫红獐牙菜(S.punicea Hemsl.)等7种獐牙菜属药用植物的药材性状、根茎叶的显微构造和解离组织及粉末特征,为合理开发和利用这一药物资源提供了鉴别依据,也为獐牙菜属植物的形态组织学研究提供了有价值的资料。     

獐牙菜亚族植物的系统发育分析

獐牙菜亚族(subtribe Swertiinae)是龙胆科(Gentianaceae)中分类处理较困难的一个亚族。为探讨该亚族各属之间和属内的系统关系,选取了该亚族86种及变种,采用ML和BI方法对样本的叶绿体基因mat K和rbc L片段进行分析,构建了该亚族的系统发育树,用马尔科夫蒙特卡洛算法(MCMC)的分子序列贝叶斯分析推算了该亚族的关键演化时间点。结果显示:①龙胆亚族和獐牙菜亚族各自为单系,且互为姐妹类群;②獐牙菜属、假龙胆属、肋柱花属和喉毛花属均不是单系群,各属的种在系统发育树上互有交叉,特别是獐牙菜属的多个种分别聚到不同的支上,与其它属是并系关系;③獐牙菜亚族49个种在约4 Ma开始形成;④分子数据支持何廷农分类系统对于獐牙菜亚属和多枝亚属的属间划分,部分支持多枝亚属下多枝组和宽丝组的划分;⑤异型花属、獐牙菜属、假龙胆属、喉毛花和肋柱花属的属间分类以及獐牙菜属肉根亚属密花组的系统位置仍需进一步讨论。     

基于不同DNA序列对四数獐牙菜系统位置分析

以扁蕾属植物为外类群,基于trnL-trnF序列、rpl16序列以及 ITS序列,采用最大简约法对四数獐牙菜的系统位置进行了分析.结果显示:尽管在ITS系统发育树、trnL-trnF系统发育树和rpl16系统发育树中所用的种和数量有所不同,所得到的3种系统发育树的拓扑结构也不一致,但四数獐牙菜的系统位置在3种系统发育树中的结果基本一致.在trnL-trnF系统发育树中,四数獐牙菜与花锚属的H.elliptica、H.brevicornis和H.weddelliana形成了一个单系群;而在ITS和rpl16系统发育树中,四数獐牙菜与歧散獐牙菜先聚在一起,再与花锚属的植物聚为一支支持率较高的单系支.研究表明,四数獐牙菜与Anagalidium属的歧散獐牙菜的亲缘关系最近,其次是与花锚属的植物,而与獐牙菜属植物的亲缘关系较远.本实验系统发育的结果支持将四数獐牙菜从獐牙菜属中分出而归入Anagalidium属的观点.     

獐牙菜属生药形态组织学的研究Ⅰ.

作者较系统地研究了国产獐牙菜属生药和形态组织学特征。对其进行了详细描述并给出了性状鉴别和显微鉴别的检索表、比较表以及组织特征图。首次测量了叶的栅表比、气孔指数与气孔数。研究结果为该类生药的准确鉴定、质量评价及资源的开发利用提供了详实的科学依据。本文首先报告其中的5种,即:獐牙菜Swertia bimaculata;西南獐牙菜S. cmcta;狭叶獐牙菜S. angustifolia;紫红獐牙菜S.punicea;以及显脉獐牙菜S. neruosa。     

基于ITS和matK序列的獐牙菜亚族 (龙胆科龙胆族)分子系统学

为探讨獐牙菜亚族（subtribe Swertiinae）各属之间和一些属内的系统关系,本研究选取了该亚族14属68种1变种,采用最大简约法（maximum parsimony）和贝叶斯法（Bayesian inference）对样品核基因ITS和叶绿体基因matK的两个片段进行独立和联合分析。结果显示：Bartonia位于亚族的最基部;喉毛花属（Comastoma）、肋柱花属（Lomatogonium）和假龙胆属（Gentianella）都非单系,处于同一个较为进化的分支中;獐牙菜属折皱组（Swertia sect. Rugosa）和獐牙菜组（S. sect. Swertia）亲缘关系最近,宽丝组（S. sect. Platynema）和藏獐牙菜组（S. sect. Kingdon Wardia）亲缘关系最近;口药花属（Jaeschkea）与獐牙菜属多枝组（S. sect. Ophelia）的大籽獐牙菜（Smacrosperma）亲缘关系最近。同时讨论了獐牙菜亚族形态分类与分子数据不一致的原因。     

龙胆科獐牙菜属新分类纲要

獐牙菜属是龙胆科中的一个大属,广泛分布于亚洲、北美洲、欧洲和非洲.本文报道獐牙菜属下的两个新组(sect.Montana和sect.Echinulata)和七个新系(ser.Repentes,ser.Kilimandscharicae,ser.Coombosae,ser.Japonicae,ser.Swertopsis,ser.Pumilae和ser.Abyssinicae).同时对獐牙菜属中的一些类群进行了分类修订,本分类纲要将被獐牙菜属世界专著采用.     

7种獐牙菜属植物花粉形态的研究

本文应用光学显微镜和扫描电子显微镜,对龙胆科(Gentianaceae)獐牙菜属(Swertia L.)7种植物(獐牙菜Swertia bimaculata(S.et z.)HK.f.Thoms.、水灵芝S.davidii Franch.、江浙獐牙菜S.hickinii Burkill.、贵州獐牙菜S.kouitchensisFranch.、大籽獐牙菜S.macrosperma C.B.Clarke.、翼梗獐牙菜S.nervosa Wall.、紫红獐牙菜S.punicea Hemsl.)的花粉形态作了比较观察,找出了它们的鉴别特征,阐明了獐牙菜属植物花粉的外壁外层表面纹饰的三种类型为条纹—网状、网状和瘤状雕纹。     

Never too late? Consequences of late birthdate for mass and survival of bighorn lambs

In strongly seasonal environments, the timing of birth can have important fitness consequences. We investigated which factors affect parturition date and how birthdate interacts with sex, maternal characteristics and environmental variables to affect the growth and survival of bighorn sheep (Ovis canadensis) lambs in a marked population in Alberta. Over 14 years, the estimated birthdate of 216 lambs ranged from 21 May to 18 July. Parturition date was heritable and genetically correlated with maternal mass the previous fall. Weaning a lamb delayed parturition the following year by about 7 days. Birthdate did not affect summer growth rate, but late-born lambs were lighter in mid September (the approximate time of weaning) than early-born ones. Birthdate did not affect survival to weaning, but late birth decreased survival to 1 year for male lambs. Forage quality, measured by fecal crude protein, did not affect survival to 1 year. Once we accounted for lamb mass in mid September, birthdate no longer affected the probability of survival, suggesting that late birth decreased survival by shortening a lamb's growing season. Because there was no compensatory summer growth, late-born lambs were smaller than early-born ones at the onset of winter. Our data highlight the importance of birthdate on life history traits and suggest that resource scarcity had more severe consequences for juvenile males than for females.     

Serum-induced hypha formation in the dimorphic yeast Yarrowia lipolytica

The dimorphic yeast Yarrowia lipolytica forms true hyphae in a medium containing N-acetylglucosamine. We made a new finding that serum is a very effective inducer of hypha formation of Y. lipolytica: serum induced its hyphal growth very quickly compared to N-acetylglucosamine (4 h vs. 10 h). Osmotic and oxidative stresses (0.2 M NaCl and 20 mM H2O2) inhibited the hypha formation induced by N-acetylglucosamine, but did not suppress the hypha formation triggered by serum. Serum-specific morphological mutants, which formed hyphae in the N-acetylglucosamine medium but not in serum medium, could be isolated. These results suggest that the signal triggered by serum may be transduced through a different pathway, at least in part, from that used for the N-acetylglucosamine signal in Y. lipolytica.     

Localisation of translocated 14C in roots and root exudates of field-grown maize

The roots of a mature, field-grown maize plant are dimorphic: the primary root and those from the oldest nodes are bare with a heavily lignified cortex arid sloughed epidermis; those from younger nodes, except for a bare elongation zone, have an intact epidermis surrounded by a persistent soil sheath. Sheathed roots consistently have more layers of cortical cells, but the ratio of volumes of cortex to stele (ca 4) and the cross-sectional area of phloem (ca³× 10⁻² mm²) are similar in each type. Assimilated carbon (from ¹⁴ C applied to a small area of one leaf) was translocated to all roots and actively metabolized in cortex and stele of both types. After 1 to 2 days the proportion of ¹⁴C exuded from a given length of mature root into its soil sheath, or into the adjacent unattached soil in the case of bare roots, was the same (5%) in both root types when compared with the ethanol-soluble ¹⁴C in the tissues of this length. Up to 75% of the ethanol-soluble label in the roots was in a cationic fraction (amino acids and unidentified compounds), ca 1% was in an anionic fraction and the remainder was in a neutral fraction (sugars). Approximately equal amounts of soluble ¹⁴C were found in the stele, cortex and laterals.     

Dispersal of chasmogamous and cleistogamous seeds inViola hondoensis W. Backer et H. Boiss

To test generality of the near-and-far dispersal model proposed by Schoen and Lloyd (1984), we compared dispersal distances of cleistgamous and chasmogamous seeds ofViola hondoensis. Dispersal distance was not significantly different between cleistogamous and chasmogamous seeds, implying that the near-and-far dispersal model cannot apply toV. hondoensis. Alternatively, little pollinator availability in summer and autumn seems to be a major factor favoring facultative cleistogamy in this species.     

The MAT A locus of the dimorphic yeast Yarrowia lipolytica consists of two divergently oriented genes

The MAT A locus of Yarrowia lipolytica, which was on the basis of its ability to induce sporulation in a diploid B/B strain, represses the mating capacity of this strain. The gene functions required for induction of sporulation and repression of conjugation could be separated by subcloning. Sequence analysis revealed two ORFs in the MAT A locus. One of them (MAT A1) codes for a protein of 119 amino acids which is required to induce sporulation. The other (MAT A2) codes for a protein of 291 amino acids that is able to repress conjugation. Both genes are oriented divergently from a central promoter region, which possesses putative TATA and CAAT boxes for both genes. The product of MAT A1 shows no homology to any known protein and seems to represent a new class of mating-type genes. MAT A2 contains a HMG box with homology to other mating-type genes. Both MAT A1 and MAT A2 are mating-type specific. In cells of both mating types, the regions flanking the MAT A locus contain sequences with homology to either S. cerevisiae SLA2 and ORF YBB9, respectively. From hybridization and subcloning data we estimate that the MAT A region is approximately 2 kb long and is present only once in the genome. Received: 25 January 1999 / Accepted: 16 April 1999     

Traits of fatty acid accumulation in dimorphic seeds of the euhalophyte Suaeda salsa in saline conditions

The mechanism on of how salinity affects seed fatty acids accumulation remains unclear in halophytes. The present results revealed that the content of total unsaturated fatty acids in black seeds was higher than in brown seeds in the euhalophyte Suaeda salsa under controlled saline conditions. Salinity (200?mM NaCl) significantly increased the total oil content, unsaturated acid/saturated acid ratio, and content of α-linolenic acid (C18:3) (ALA), especially in brown seeds. The most abundant fatty acid in dimorphic seeds is linoleic acid (C18:2) (>70%). It appears that more ALA accumulated in brown seeds compared to black seeds. The enzyme activity of omega-3 fatty acid desaturase (ω-3 FAD) in brown seeds was much higher than that in black seeds, but salinity had no significant effect on the activity of ω-3 FAD in both brown and black seeds. The relative expression of SsFAD7 was increased by salinity, and the value in brown seeds was much higher than that in black seeds. This means salinity can, salinity can improve the quantity of fatty acids in dimorphic seeds of S. salsa, and the enzyme of ω-3 FAD and SsFAD7 may involve in the accumulation of ALA in dimorphic seeds under salinity.     

Impact of embryo technologies on secondary sex ratio in rabbit

Increasing evidence indicates that assisted reproductive technologies (ARTs) disturb skewed sex-ratio and induce sex-dimorphic postnatal effects. Undoubtedly, the combination of multiple ovulation and embryo transfer (MOET) together with the use of vitrification technique (MOVET) is currently being used in breeding programs. However, since the first case of sex skewing reported in 1991, the accumulative and long-term transmission of skewed sex-ratio to future generations has not been thoroughly evaluated. Here we test as MOVET program induce a skewed sex ratio, and we consider skewed sex ratio transmission to future generations. To this end, we first evaluated the F1 generation, demonstrating that a MOVET program causes a severe imbalance skewed secondary sex ratio (SSR) towards male by 12%. This imbalanced persist after a second MOVET program (F2 generation), with an accumulative skewed SSR towards male by 25%. Finally, using a crossbred generation derived from crossing F1 males derived from a MOVET program with naturally-conceived (NC) females, we show that the imbalance skewed SRR persist. Bodyweight comparison between MOVET animals and NC counterparts revealed significant changes at birth, weaning and adulthood. However, there was a significant interaction between F2 MOVET animals and sex, demonstrating an apparent accumulative sex-dimorphic effect. At adulthood, MOVET derived males presented a lower body weight. In conclusion, we show that the MOVET program causes a direct, accumulative and long-term transmission of skewed SSR.     

A molecular toolbox for manipulating Eremothecium coryli

The genus Eremothecium contains dimorphic and filamentous fungal species, most notably Eremothecium sinecaudum (Holleya sinecauda), a dimorphic plant pathogen, which was isolated from mustard seeds, and Eremothecium gossypii (Ashbya gossypii), a filamentous fungus, which is well known for its ability to produce riboflavin. In this study, we present the initial molecular characterization of another Eremothecium species classified as Eremothecium coryli. E.coryli is a dimorphic fungus. We have developed, based on previously described reagents, a transformation system for E. coryli using kanMX and NATMX3 as dominant selectable marker genes on freely replicating plasmids conferring resistance to the antibiotics G418 and nourseothricin, respectively. As reporter genes we could introduce lacZ and GFP, which were controlled either by the AgTEF1 promoter or by regulatable MET promoters derived from the A. gossypii and Saccharomyces cerevisiae MET3 genes. These newly established tools will allow a detailed comparison of different growth modes in filamentous or dimorphic species within the genus Eremothecium.