莼菜根不同发育区细胞中高尔基体的发育与结构变化

在莼菜根分生区细胞中,部分粗糙内质网片断转化成单个潴泡,游离于细胞基质中的单个潴泡相互叠加后形成具6—8个潴泡组成的高尔基体。高尔基体在伸长区进入分泌高峰期,由于其成熟面的潴泡溢出大量分泌泡后消失或潴泡游离出去,使高尔基体潴泡数目减少,部分高尔基体形成面有内质网溢出的小泡互相融合后形成新的潴泡补充,另一些高尔基体由于得不到潴泡补充而逐渐消失;这可能是成熟区细胞内高尔基体数目减少的重要原因之一。     

穗花杉的胚珠结构与雌、雄配子体的发育

穗花杉胚珠结构最显著的特点之一是,珠心顶部有一比较发达的贮粉室。珠孔道的闭塞主要是由珠被中层区细胞形成的;珠被维管束8—14个。假种皮中具14—17个粘液分泌道。小孢子囊远轴着生,起源于皮下细胞。在小孢子母细胞分裂前后,绒毡层出现局部异常膨大现象。成熟花粉由两个细胞组成。雌配子体游离核经8次分裂产生256个核后形成胞壁。颈卵器单个,顶生。从胚珠结构和雌雄配子体发育来看,穗花杉属在红豆杉科中可能居于最原始的位置;而且它与三尖杉属有许多共同之处。     

长江华溪蟹纳精囊超微结构的研究

利用电镜技术,对长江华溪蟹的纳精囊进行了研究。结果表明:在纳精囊上皮的顶分泌型腺细胞中,充满大量高尔基体和粗面内质网的潴泡和囊泡。泡中含有絮状或颗粒状分泌物。潴泡和囊泡先是单独存在,最后聚集在一起,形成大的分泌颗粒后排出囊腔。核糖体比比皆是。线粒体数量较大,作为一种载体参与了分泌物的形成。细胞化学显示,分泌物中含有蛋白质、脂肪和少量糖类。结论:纳精囊上皮的顶分泌型腺细胞具有积极的分泌活动。       

小白鼠体内器官上皮细胞中高尔基氏器的形态与分泌机能的关系

1.本实验用古典的Aoyama氏法显示小白鼠副睾上皮、胰腺外分泌上皮、肾近曲小管上皮及肠腺上皮细胞中的高尔基氏器;小白鼠分三组,第一组正常作对照用,第二组于杀死取材前半至1小时内,用1毫克硝酸匹罗卡品从皮下注射入动物体内,第三组在杀死取材前半至1小时内用0.2毫克硫酸阿托品从皮下注入动物体内。 2.比较三组小白鼠四种器宫的高尔基氏器后,发现有显著的区别:①正常小白鼠副睾上皮细胞和胰腺外分泌上皮细胞中的高尔基氏器呈网状或略呈网织状。肾近曲小管上皮细胞中高尔基氏器呈小滴状或由小滴速成短杆。肠腺上皮细胞内的高尔基氏器是小块状;②用硝酸匹罗卡品注射小白鼠后,器官或腺体上皮细胞中的高尔基氏器因颗粒浓集而膨胀很大。同时形成分泌滴排出于腔中;③用硫酸阿托品注射小白鼠后,器官或腺体上皮细胞中的高尔基氏器显现紧缩,很少或不形成分泌颗粒。 3.细胞内高尔基氏器的膨胀紧缩及颗粒的涨落与分泌的生理和药理机能有关,而颗粒的集散又影响高尔基氏器的改变。故我们同意Nassonov与Bowen(1924a)的主张,认为高尔基氏器可能是细胞中有分泌机能的主要机构。     

篦子三尖杉的胚胎学研究及其系统位置的探讨

篦子三尖杉Cephalotaxus oliveri的成熟花粉包含两个细胞,花粉管在精原细胞产生后 经历了一年的休眠期; 精原细胞分裂产生两个体积不等的精子; 雌配子体游离核经12次分裂后形成细胞壁; 窄长的颈卵器单个顶生; 卵细胞中含有大量类核仁状体; 受精时,雌雄核在分裂中期完全融合; 原胚游离核在16核时产生细胞壁; 原胚具冠细胞; 无裂生多胚现象; 成熟胚 二枚子叶。总之,蓖子三尖杉与本属其它种相比,存在明显的差异。如精原细胞分裂前细胞中心细 胞质浓缩成星状放射区域; 苗端早在胚成熟前分化形成明显的突起,以及成熟胚的子叶极为发达等等。因此,作者赞同将蓖子三尖杉在本属中另立一组的观点。     

蕨配子体发育及卵发生的显微结构观察

运用显微观察技术对蕨(Pteridium aquilinum var. latiusculum)配子体发育和卵发生进行了研究。结果表明：(1)蕨孢子黄褐色,四面体形,具三裂缝,接种后3～7 d萌发,经丝状体和片状体阶段发育成原叶体,成熟原叶体雌雄异株或同株。(2)蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层和下层细胞发育为颈卵器壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞,分别为卵细胞、腹沟细胞和颈沟细胞;刚产生时,此3个细胞紧贴颈卵器壁,细胞质内液泡较多,随着发育,卵细胞和腹沟细胞之间产生了分离腔,但二者通过孔区相连,在卵细胞上表面可观察到卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,颈卵器壁细胞内具有黑色颗粒物质。连续切片观察发现,成熟卵细胞上表面中央具有受精孔。卵发生的细节尚需超微结构的研究。     

青阳参小孢子发生和雄配子体发育

利用常规石蜡制片技术、荧光显微技术、光镜细胞化学技术、电子显微镜技术对青阳参小孢子发生和雄配子体发育进行了详细观察。结果显示,小孢子孢原细胞起源于皮下组织并在两个地方分化;孢原细胞平周分裂形成初生壁层和初生造孢层,初生壁层细胞再经过平周分裂形成2层细胞,其中最内一层即为绒毡层,绒毡层为分泌型绒毡层,既为小孢子发育提供营养来源,又分泌分泌物形成包围花粉粒的膜;初生造孢层细胞直接行使小孢子母细胞的功能;成熟花粉粒中含有大量淀粉粒、蛋白质、内质网、叶绿体、脂体和大液泡;包围花粉粒的膜和花粉粒之间的膜含有蛋白质成分和脂类成分;小孢子细胞核分裂形成营养细胞和生殖细胞,营养细胞和生殖细胞间没有细胞板形成,生殖细胞呈透镜型、比营养细胞小。     

峨眉凤丫蕨配子体发育及卵发生的研究

用显微观察及透射电镜技术对峨眉凤丫蕨的配子体发育及卵发生过程进行了观察研究,以探讨其卵发生细胞学机制及蕨类植物演化关系。结果表明:(1)峨眉凤丫蕨孢子接种7～9d萌发,经丝状体和片状体阶段发育为心形原叶体,成熟原叶体雌雄同株,在原叶体基部产生精子器,在原叶体生长点下方产生颈卵器。(2)卵发生研究表明,峨眉凤丫蕨颈卵器产生于生长点下方的表面细胞,该细胞经2次分裂形成3层细胞,中间者为初生细胞,它经2次不等分裂产生卵细胞、腹沟细胞和颈沟细胞;新产生的卵与腹沟细胞间连接紧密,有发达的胞间连丝,随着发育,卵细胞与腹沟细胞之间产生分离腔,而腹沟细胞与卵细胞始终通过孔区相连;发育中期,卵核形成大量核外突;发育后期,在卵细胞外侧形成卵膜,孔区演变为受精孔,核外突数量减少。     

甘蔗茎尖原生分生组织区域化

甘蔗茎尖原生分生组织是甘蔗地上部分一切形态组织的发源中心,通过对6个不同茎径甘蔗品种4个不同营养发育时期的茎尖原生分生组织显微和超微结构观察研究发现:甘蔗茎尖原生分生组织呈半卵型结构,明显分为原套原始细胞区、原体原始细胞区、周缘分生细胞区、髓分生区,其区域化符合原套-原体学说。原套原始细胞区为最外一层细胞,原套细胞之间胞间连丝丰富,而原套与原体细胞之间胞间连丝极少,细胞以垂周分裂为主,扩大原生分生组织表面积;原体位于原套下的分生组织的中央区域,细胞可以进行各个方向的分裂,不断增加体积,原体原始细胞区呈一个球体;周缘分生区位于原套、原体下方两侧,细胞活跃产生叶原基和原形成层细胞;髓分生区细胞位于原体下方周缘分生区内侧,细胞横向分裂纵向排列,使甘蔗茎伸长。     

地钱颈卵器发育和卵发生的显微观察及细胞化学研究

对地钱（Marchantia polymorpha）颈卵器发育和卵发生过程进行了显微观察和细胞化学的研究,颈卵器起始于原始细胞,该细胞呈乳突状,经横分裂产生基细胞和顶细胞,顶细胞经3次纵斜向分裂和1次横分裂产生初生细胞,初生细胞是颈卵器内的第一个细胞,经横分裂产生中央细胞和颈沟母细胞,前者产生1个腹沟细胞和1个卵细胞,后者最终产生4个颈沟细胞。颈卵器的成熟表现为颈部显著伸长和腹部膨大,卵细胞成熟时具有不规则的核,细胞质内含有丰富的囊泡和颗粒物,卵细胞周围充满粘性物质,细胞化学研究表明,该粘性物质为多糖,卵细胞质中深染色的颗粒可能为脂类物质,腹沟细胞自产生后就逐渐退化,颈沟细胞的退化迟于腹沟细胞,其数量通常为4个,偶尔可见5个颈沟细胞或具有双核的现象。     

Mapping the suturing of a continental biota

The present-day spatial distribution of interspecific contact zones and intraspecific phylogeographical breaks provides a window into the past ecological and evolutionary processes that underlie speciation and species ranges. The clustering of contact zones and/or phylogeographical breaks in space indicates the suturing of diverged biotas. The presence of such suture zones indicates that similar ecological and historical factors have influenced the past and present distributions of populations and their divergence. Thus, suture zones are ideal natural laboratories for studying divergence, secondary contact and speciation across many different taxa. The concept of suture zones was formalized decades ago by Remington (1968), but only a few detailed and quantitative investigations of suture zones exist (Swenson & Howard 2004, 2005; Whinnett et al. 2005; Moritz et al. 2009). This limited number of investigations is largely because of a lack of detailed geographical data and sophisticated analytical tools. In this issue of Molecular Ecology, Rissler & Smith (2010) have accomplished a detailed investigation into the suturing of amphibian lineages in the United States which uses both detailed geographical data and sophisticated analytical methods. The work greatly enhances our knowledge of suture zones by extending previous work that has focused less on amphibians and by explicitly considering the relationship between species richness and suture zones.     

西藏农作物病原真菌的区域分化初探*

在西藏农作物病原真菌调查基础上,综合分析西藏自然环境条件和社会经济条件对病原真菌分布的影响,将西藏病原真菌分布划分为5个区:(1) 喜马拉雅南侧暖热湿润区; (2)藏东温暖半湿润区; (3)藏南温暖半干旱区; (4) 西喜马拉雅温凉干旱区; (5) 藏北羌塘高寒区;     

Molecular patterns of introgression in a classic hybrid zone between the Australian tree frogs,Litoria ewingii and L. paraewingi: evidence of a tension zone

Hybrid zones provide a rare opportunity to explore the processes involved in reproductive isolation and speciation. The southern hybrid zone between the southeastern Australian tree frogs Litoria ewingii and L. paraewingi has been comprehensively studied over the last 40 years, primarily using reproductive compatibility experiments and male advertisement calls. We used mitochondrial DNA (mtDNA) and eight nuclear microsatellite markers to characterize this hybrid zone along a historically studied transect and to test various dispersal‐dependent and dispersal‐independent hybrid zone models. The species are genetically distinct and the level of hybridization within the contact zone is low, with the majority of admixed individuals representing later‐generation hybrids. Based on previous experimental genetic compatibility studies, we predicted that hybrids with L. paraewingi mtDNA would be more frequent than hybrids with L. ewingii mtDNA. Surprisingly, a greater proportion of the identified hybrids had L. ewingii mtDNA. Geographical cline analyses showed a sharp transition in allele frequencies across the transect, and both the mtDNA and microsatellite data showed concordant cline centres, but were best supported by a model that allowed width to vary. Overall, the L. ewingii–L. paraewingi hybrid zone is best characterized as a tension zone, due to the narrow cline width, concordant genetic clines and low levels of hybridization.     

Tension versus ecological zones in a two-locus system

Previous theories show that tension and ecological zones are indistinguishable in terms of gene frequency clines. Here I analytically show that these two types of zones can be distinguished in terms of genetic statistics other than gene frequency. A two-locus cline model is examined with the assumptions of random mating, weak selection, no drift, no mutation, and multiplicative viabilities. The genetic statistics for distinguishing the two types of zones are the deviations of one- or two-locus genotypic frequencies from Hardy-Weinberg equilibrium (HWE) or from random association of gametes (RAG), and the deviations of additive and dominance variances from the values at HWE. These deviations have a discontinuous distribution in space and different extents of interruptions in the ecological zone with a sharp boundary, but exhibit a continuous distribution in the tension zone. Linkage disequilibrium enhances the difference between the deviations from HWE and from RAG for any two-locus genotypic frequency.     

An altitudinal transect study of the vegetation on Mount Kinabalu,Borneo

A quantitative transect analysis of altitudinal sequences of forest canopy species from 600 to 3400 m asl on Mt. Kinabalu (4101 m), Borneo, resulted in four discrete altitudinal vegetation zones. These were made up of mutually exclusive species groups for lowland (<1200 m asl), lower montane (1200 to 2000–2350 m asl), upper montane (2000–2350 to 2800 m asl), and subalpine (2800 to the forest line, 3400 m asl) zones. Zonal soil types were correlated with the vegetation zones. In upslope sequence, these were: lowland Oxisols, montane Histosol/Spodosol complex, and subalpine Inceptisols. The highest contents of organic carbon, extractable phosphorus, and exchangeable magnesium and potassium were recorded in the lower and upper montane zones. The upper boundaries of the lowland, upper montane and subalpine zones coincided with thermal thresholds of latitudinal bioclimatic zones: 18°C TMIN (Köppen's tropical), WI 85 (Kira's warm temperate), and WI 45 (Kira's cool temperate), respectively. The upper limit of the lower montane zone was correlated with an abrupt increase of water surplus estimated from the annual rainfall minus annual potential evaporation. These climatic characteristics appear to define ecological altitudinal turnover points, so called critical altitudes, where groups of associated species are displaced by other groups.Abbreviations asl = above sea level - DBH = diameter at breast height - PHQ = Park headquarters - TMAX = Mean daily maximum air temperature - TMIN = Mean daily minimum air temperature - TWINSPAN = Two-way indicator species analysis - WI = Warmth index     

长江东流河道整治对长江江豚种群数量的影响

长江江豚是生活在长江中下游的濒危水生哺乳动物,通常活动在江心洲和浅水缓滩附近。航道整治改变了鱼类栖息活动的水文环境,也给豚类生存带来负面影响。本文根据长江东流河道整治施工前和施工后各3 次野外考察资料,分析了3 种流态中江豚的数量与群结构。结果表明,该工程实施前江豚主要栖息活动在边滩的分离区,其次在洲头的分流区。工程实施后,整治江段的江豚种群数量年下降率达8. 9% 。江豚在分流区活动已消失,在分离区集群规模较小,且在流态之间移动增大。本文研究结果也提示长江江豚就地保护难度越来越大,从长江干流中把长江江豚迁入故道中是一件刻不容缓的工作。     

Temporal deposition of incremental and discontinuous zones in the otoliths of Oreochromis niloticus (L.)

Ultrathin sections of otoliths were prepared and studied with the transmission electron microscope. The discontinuous zone starts to grow at night, 3 h before light-on, and is completed a few hours after light-on. The growth of the incremental zone follows immediately afterwards and continues approximately until light-off. There is little material deposited onto the otolith at night before the start of discontinuous zone deposition.     

Strictly parapatric distribution of flightless leaf beetles of the Chrysolina angusticollis species complex (Coleoptera, Chrysomelidae) in the vicinity of Sapporo, northern Japan

In the southwestern suburbs of Sapporo, northern Japan, the flightless leaf beetle Chrysolina angusticollis species complex is represented by three phenotypically distinct forms which are distributed in a strictly parapatric manner. Boundaries between the forms usually coincided with narrow topographic barriers such as streams and cliffs, and areas with low density of host plants. In only four out of 237 sites was more than one form discovered in sympatry. In these exceptional sites, putative hybrid individuals were also found. This stricdy parapatric distribution and coincidence of boundaries with topographic barriers suggest that the boundaries are tension zones, i.e. hybrid zones maintained by dispersal of native individuals from outside of the zones and selection against hybrids in the zones.     

Distribution and habitat use of water frog hybrid complexes in France

Hybrid zones are either distributed along clines or in a mosaic of patches. This distribution may depend upon variation in taxon habitat use. Habitat use and distribution of diverse taxa of water frogs (Rana ridibunda, R. lessonae, R. perezi, R. kl. grafi and R. kl. esculenta) in France are analysed to determine whether water frog complexes conform to the mosaic or clinal model. Biogeographical scenarios may be invoked in order to explain the distribution of water frogs. However, the distribution of R. perezi and R. kl. grafi, being restricted to regions characterized by Mediterranean or Oceanic climatic conditions, suggests that these frogs do not endure cold winters. R. ridibunda is widespread in Southern France and its distribution suggests multiple introductions. It is concluded that water frogs conform to the mosaic zone model rather than to the tension zone model because: (i) taxa exhibited differences in habitat use, (ii) pure parental species were documented and (iii) hybrids are not unfit relative to parental species.