Ostrya virginiana （Betulaceae）的胚珠和胚囊发育及其系统学 …

首次报道了铁木属Ｏｓｔｒｙａ的胚珠和胚囊发育过程。研究结果表明：Ｏ．ｖｉｒｇｉｎｉａｎａ的多数子房内有２个胚珠,胚珠倒生,单珠被,厚珠心,具１至数上孢原细胞;孢原细胞平周分裂形成一个周缘细胞和一个造孢细胞,造孢细胞直接发育成大孢子母细胞,四分体大孢子呈线形排列,它们均可成为功能大孢子;绝大多数胚珠中具有２￣６个胚囊,胚囊蓼型。最后,对珠被层数和多孢原、多胚囊等问题进行了讨论,并对桦木科各属的胚胎学     

小草蔻胚珠及雌配子体发育的研究

小草蔻（Alpinia henryi K.Schum）胚胎倒生,厚珠心,双珠被。内珠被独自成珠孔。造孢细胞,大孢子母细胞和四体时期,周缘细胞仅1层。四分体线形,少数三分体。合点在孢子具功能。成熟胚珠具有珠心冠原和承珠盘结构。胚囊发育属蓼型。成熟胚整,合点端狭长,形成盲囊。反足核不能构成细胞,是短命的。膜质假种皮的原基从外珠被和珠柄发生。     

濒危物种灰叶胡杨的大孢子发生和雌配子体发育

用石蜡切片法对濒危物种灰叶胡杨的大孢子发生和雌配子体发育过程进行观察研究.结果显示,灰叶胡杨雌蕊由三心皮构成,侧膜胎座,胚珠为倒生型,有18～21列;发育早期的胚珠为双珠被,厚珠心;当外珠被发育至与内珠被处于同一水平时,内珠被便开始退化,故成熟胚珠为单珠被;孢原细胞1个,并且自表皮下2层处分化;大孢子母细胞由孢原细胞分裂后形成的造孢细胞直接发育而来;大孢子四分体直线形排列,合点端的大孢子为功能大孢子,蓼型胚囊;在胚囊发育过程中珠孔端的珠心组织退化.根据开花物候不同阶段花的形态特征,可以初步判断灰叶胡杨大孢子发生和雌配子体的发育进程.     

Ostrya virginiana (Betulaceae)的胚珠和胚囊发育及其系统学意义

首次报道了铁木属Ostrya的胚珠和胚囊发育过程。研究结果表明: O. virginiana的多数子房 内有2个胚珠,胚珠倒生,单珠被,厚珠心,具1至数个孢原细胞;孢原细胞子周分裂形成一个周缘细胞 和一个造孢细胞,造孢细胞直接发育成大孢子母细胞,四分体大孢子呈线形排列,它们均可成为功能大 孢子;绝大多数胚珠中具2～6个胚囊,胚囊蓼型。最后,对珠被层数和多孢原、多胚囊等问题进行了讨 论,并对桦木科各属的胚胎学性状作了比较,发现桦木科各属的胚胎学特征具有较高的一致性,如多孢 原、多胚囊,较长的传粉和受精间隔期等。同时,比较和讨论了某些胚胎学性状,如胚珠类型和珠被层数,在高等金缕梅类各科间的异同及系统学意义。     

北柴胡大小孢子发生和雌雄配子体发育的研究

用石蜡切片法对北柴胡的大、小孢子发生和雌、雄配子体发育过程进行观察研究.结果显示,北柴胡的胚珠为倒生型,单珠被,薄珠心.孢原细胞不经分裂直接发育成大孢子母细胞;四分体线性,多数情况下合点端的大孢子为功能大孢子,少数情况下亚合点端的大孢子也可发育为功能大孢子,蓼型胚囊;八核胚囊时期,珠心基部和两侧的一些珠心细胞保持自己的细胞质和形状,留存较久,成为珠心座细胞,珠被内表皮细胞发育为珠被绒毡层;花药壁发育类型为基本型,绒毡层为腺质绒毡层.小孢子母细胞减数分裂的胞质分裂为同时型,产生正四面体型四分体.成熟花粉为3细胞型.     

车桑子大孢子发生与雌配子体发育

采用常规石蜡切片法,对车桑子大孢子的发生和雌配子体的发育进行观察,探讨车桑子自然结籽率低的原因和明确其胚胎发育特征。结果表明:(1)车桑子花柱有花柱道,子房3室,中轴胎座,横生胚珠,每心室两枚胚珠,双珠被,厚珠心,无承珠盘。(2)位于珠心表皮细胞下的孢原细胞经平周分裂产生造孢细胞,造孢细胞发育为大孢子母细胞,大孢子母细胞经减数分裂形成线性四分体,靠近珠孔端3个大孢子退化消失,靠合点端大孢子发育为功能大孢子,大孢子发生类型为单孢子发生型。(3)单核胚囊经3次有丝分裂形成7细胞8核的成熟胚囊,胚囊发育类型为蓼型。(4)花器官形态的变化和大孢子发育过程有一定联系,可根据雌花形态特征大致判断大孢子发育时期。研究认为,车桑子雌配子体发育过程中出现的胚囊不中空、游离核不进一步细胞化等异常现象,可能是导致车桑子自然结籽率低的原因之一。     

红花胚珠和雌配子体发育

用石蜡切片法研究了红花的大孢子发生和雌配子体发育过程,得到以下结果：（１）胚珠发育为薄珠心类型,倒生胚珠,具单珠被。（２）胚囊发育蓼型。（３）有珠被绒毛层,珠被绒毡层起始于大孢子母细胞时期,单核胚囊阶段高度发育,受精后从合点端逐渐退化。珠孔塞细胞呈毛状。     

八角枫大孢子发生和雌配子体发育

八角枫为顶生胎座、倒生胚珠、单珠被。孢原细胞处于珠心表皮之下,直接起大孢子母细胞的功能。珠心表皮细胞平周分裂产生多层珠心周缘细胞,为厚珠心。四分体线行排列,合点端的大孢子发育为蓼型胚囊。开花前,两极核事例成次生核,或不融合仍保留极核状态。反足细胞退化较晚,胚囊合点端具承珠盘。     

籽银桂雌雄配子体的发育研究

利用石蜡切片和扫描电子显微镜技术。研究了南京地区银桂品种群的‘籽银桂’雌雄配子体的发育过程。雄蕊的孢原细胞在8月中旬出现。花药壁的发育为基本型,分泌型绒毡层。小孢子母细胞减数分裂为同时型。形成的4个小孢子四分体呈典型的四面体型。成熟花粉粒即雄配子体为二核花粉粒。籽银桂为倒生胚珠。单珠被,薄珠心。珠被内层细胞特化为珠被绒毡层。在胚珠合点端。有承珠盘结构。在9月中旬,雌蕊的孢原细胞开始分化出来。孢原细胞直接发育成大孢子母细胞,然后大孢子母细胞减数分裂形成大孢子。‘籽银桂’的胚囊发育类型为蓼型。成熟胚囊即雌配子体由2个助细胞、1个卵细胞、1个中央细胞(2个核)和3个反足细胞组成。     

大叶杨配囊及胚珠的形成和发育

本文应用细胞化学方法研究了大叶杨胚珠、胚囊的形成和发育过程中核酸、蛋白质及不溶性多糖的分布和消长。大孢子母细胞、大孢子四分体及功能大孢子中含较少不溶性多糖,但却含丰富的RNA和蛋白质。功能大孢子经分裂发育成八核的蓼型胚囊。四核胚囊开始积累细胞质多糖,成熟胚囊中除反足细胞外充满淀粉粒。反足细胞形成后不久即退化。助细胞具多糖性质的丝状器,受精前两个助细胞退化。卵细胞核对Feulgen反应呈负反应。二极核受精前由胚囊中部移向卵器,与卵器接触后融合形成次生核。发育早期的胚珠为厚珠心,双珠被。晚期,内珠被退化,故成熟胚珠为单珠被。四核胚囊时期,珠孔端珠心组织退化,胚囊伸向珠孔形成胚囊喙。合点端珠心组织含丰富的蛋白质和核酸,这一性质与绒毡层性质相似,可能涉及胚囊的营养运输。胚囊的营养来源于子房和胎座细胞内贮存的淀粉粒。     

The Experimental Control of Inflorescence Development in Carex

In an attempt to elucidate the factors controlling the developmentof the inflorescence of Carex various substances were appliedto plants of several species during and after the transitionto the flowering phase. The main effects of the treatments onthe inflorescence were that indole-3–acetic acid and i-naphtha-leneaceticacid caused the induction of female spikelets on the sites ofpotential male flowers, 2, 3, 5-triiodobenzoic acid caused suppressionof branching and kinetin an increase in branching. All threesubstances resulted in a decrease in the flowering response,as expressed by the number of inflorescences produced. On thebasis of these results it is suggested that normal developmentof the inflorescence can be explained on a hypothesis involvingtwo substances, one probably an auxin and the other replaceablein experiments by kinetin. The possibility is considered thatthis second substance may be a kinetin-like factor producedby the roots.     

Naturalists and Natural History Institutions of the American West: A Preview

SYNOPSIS. The nineteenth century was a time of active explorationof the American West. This symposium details the individualsand institutions that initiated the natural history studiesassociated with the accumulation of the geographic informationand relates the natural history studies to the growth and developmentof science and the scientific community.     

Interrelationship between Abscisic Acid and Ethylene in the Control of Senescence Processes in Carnation Flowers

The involvement of abscisic acid (ABA) in senescence of carnationflowers, in the presence of silver ions (which inhibit ethyleneaction), and aminoethoxyvinylglycine (AVG) (an inhibitor ofethylene synthesis) was studied. ABA stimulated senescence asseen by advancement of ethylene surge, and time to the developmentof in-rolling of petal margins. ABA also increased the sensitivityof the flowers to ethylene. Silver ions did not affect the timeor extent of the ethylene surge, but prevented the appearanceof visual senescence symptoms, and lowered the sensitivity toethylene. AVG delayed the ethylene surge and lowered the maximumrate of ethylene production. Also, AVG delayed the developmentof visible senscence. In the presence of silver ions, ABA advanced the ethylene surgebut senescence symptoms did not develop. The effect of ABA onthe parameters measured was prevented by AVG. Thus it is suggestedthat ABA exerts its effect on senescence via ethylene. The possibleinvolvement of an ABA-ethylene sequence as a mediator of waterstress-promoted senescence is discussed.     

Temperature-dependent development in marine copepods: a comparative analysis of models

A comparative analysis was carried out on the several equationsmost commonly used to describe the dependence of the developmentof organisms on temperature. Goodness of fit, number of parameters,ease of fitting data and biological significance were compared.     

Microsporogenesis in Taxus baccata L.: The Development of the archaesporium

An ultrastructural and cytochemical investigation of the developmentof the mierosporangium of Taxus baccata reveals many resemblancesto comparable events in other land plants, but also severaldistinctive features. During early development the archaesporiumcontains groups of degenerate cells which ultimately disappear,presumably by resorption. Scattered elsewhere in the cells ofthe archaesporium are highly ordered bodies, possibly crystal-likeformations of tubulin. The tapetum differentiates from the outerlayer of the archaesporium. Mitoses coincidentally cease tobe detectable within the sporangium and the sporogenous cellsbecome recognizable about three weeks before their nuclei entermeiosis. Although, as in other gymnosperms investigated, theearly development of the archaesporial cells is not synchronized,there is a tendency for synchrony to be acquired by the sporogenouscells and diad formation takes place more or less simultaneouslythroughout the sporangium. Measurements by microfluorometry of RNA levels during developmentof the archaesporium show a progressive rise in the RNA contentof the cells up to the beginning of meiosis. Microsporogenesis, Taxus baccata, archesporium     

Some Observations on the Behavioral and Morphological Development of Coyote Pups

The morphological and behavioral development of three litters(1 male; two females; two males and two females) of coyotesreared in confinement is presented. The data include: patternsof behavior and associated morphological changes in ingestive,eliminative, contactual, and care-seeking processes; interactionsamong sibs and between adults and neonates; and the developmentof agonistic behavior in coyote pups.     

Experimental and Analytical Studies of Pteridophytes: XXIX. The Effect of Progressive Starvation on the Growth and Organization of the Shoot Apex of Dryopteris aristata Druce

Observations on shoot apices of Dryopteris aristata maintainedunder conditions of progressive starvation for periods of upto a year are recorded. Changes in the size of the shoot apexand leaf primordia, in the rates of inception and developmentof leaf primordia, and in phyllotaxis, are described and discussed.     

Mechanisms of Developmental Integration of Aster novae-angliae L. and Hieracium murorum L.

This paper is an inquiry into the regulatory features of developmentof Aster novae-angliae and Hieracium murorum. Computer-generatedplant models are compared with real plants to analyze branching,conver sion from vegetative to flowering development, stem elongation,and flowering.     

Fine Structure of Phialide and Conidiospore Development in Aspergillus giganteus 'Wehmer'

The conidiophore vesicle is composed of a peripheral regionwhich contains many nuclei and mitochondria and a central regionwhich is densely packed with glycogen granules but containsvery few organelles. The phialides, which arise as sphericalprotuberances from the surface of the vesicle, are bounded bya much thinner wall than that of the vesicle. Nuclei migrateinto the phialides at a comparatively early stage in their development.Septa are present at the proximal ends of mature phialides andalthough pores are present in these septa it is suggested thatthey are too small to permit the ingress of such organellesas nuclei and mitochondria from the vesicle. The developmentof adjacent phialides is well synchronized but the developmentof the vesicle as a whole is not precisely co-ordinated. Eachmature phialide contains a single nucleus, as do the conidiosporeswhich they produce. The first conidiospore produced by a phialidearises as a spherical protrusion from the tapered, thickenedapex of the phialide. The conidiospores are delimited from thephialide by the formation of a cross wall in a manner reminiscentof the process of septation in hyphae. When first formed theconidiospores have a cylindrical shape and they only assumetheir characteristic spherical shape at a later stage in development.     

A mass spectrometric method for measuring flavour concentration/time profiles in human breath

Psychophysical work on flavour perception led to the developmentof a mass spectrometric method to monitor continuously the releaseof flavour components at the nose, breath-by-breath. The keyfeature of the measuring set-up is a special membrane interfacingwith a mass spectrometer. The method enables establishment ofthe effect of the matrix (oil or water) on flavour release rateand retention, and assignation of quantitative parameters. Amathematical model to evaluate the experimental curves was alsodeveloped.