越南篦齿苏铁小孢子发生及其系统学意义

运用常规石蜡切片方法,结合显微荧光技术对越南篦齿苏铁Cycas elongata 小孢子发生和花粉个体发育进行了研究。结果表明：其小孢子叶球5月中下旬开始萌动,小孢子囊着生在小孢子叶远轴面,且3-5小孢子囊以辐射状排列方式聚生成聚合囊。小孢子囊壁由6-7层细胞组成,包括表皮、中层及绒毡层。绒毡层来源于成熟造孢组织的外围细胞,其退化形式为分泌型。6月中旬,小孢子母细胞进入减数分裂I,至6月下旬形成四分体。母细胞减数分裂后胞质分裂的方式与其他苏铁类植物不同,具有连续型与同时型两种类型。7月中旬,小孢子经过2次有丝分裂后,形成3细胞的成熟花粉粒。7月下旬进入散粉状态。在花粉发育过程中,母细胞内淀粉粒的积累及其壁上胼胝质的沉积均呈现规律性变化。     

四川前胡属的花粉形态及系统学意义

通过光学显微镜和扫描电镜观察了前胡属 Peucedanum L.7种植物的花粉形态 .研究结果表明 :该属花粉为三棱长球形 ;三孔沟 ,边孔 ;外壁两层 ,层次分明 .根据花粉形态可归为 :矩形型和赤道收缩形型二个类型 ,其演化趋势为矩形型→赤道收缩形型 .研究结果支持了关于前胡属在伞形科中是一个较自然和较进化的类群的观点 .本文从孢粉学角度还初步分析了该属的属下系统 ,为该属的系统学研究提供基础资料     

末次冰期以来北海道、萨哈林岛及亚洲东北部落叶松林演变史

萨哈林岛（库叶岛）和北海道的末次冰期沉积丰富的落叶松花粉,为了搞清楚落叶松花粉百分比和实际森林密度的关系,我们系统地分析了从苔原,森林苔原以及泰加林的表土样品,根据孢粉资料恢复了两个岛屿3万年以来的植被和气候,两个岛上3万年前后 以云杉与落叶松共生的森林为主,松和冷杉现在比现代相对较冷和干的气候条件下,萨哈林在末次冰盛期的草原和泰加林主要由落叶松和松组成,和现在西伯利亚东北部的泰加林相似,在北海道末次冰盛期的草原和泰加林主要由落叶松,松以及云杉组成,气候更加干冷,在新仙女木期森林苔原分布到中萨哈林岛,而北海道的草原和泰加林以落叶松为主,气候可能比末次冰盛期还要冷,在1万年前两个岛的落叶松含量都开始下降,6000年前在北海道消失,萨哈林岛的落叶松则残存至今。     

Last glacial maximum biomes reconstructed from pollen and plant macrofossil data from northern Eurasia

Pollen and plant macrofossil data from northern Eurasia were used to reconstruct the vegetation of the last glacial maximum (LGM: 18,000 ± 2000 ¹⁴C yr bp ) using an objective quantitative method for interpreting pollen data in terms of the biomes they represent ( Prentice et al., 1996 ). The results confirm previous qualitative vegetation reconstructions at the LGM but provide a more comprehensive analysis of the data. Tundra dominated a large area of northern Eurasia (north of 57°N) to the west, south and east of the Scandinavian ice sheet at the LGM. Steppe‐like vegetation was reconstructed in the latitudinal band from western Ukraine, where temperate deciduous forests grow today, to western Siberia, where taiga and cold deciduous forests grow today. The reconstruction shows that steppe graded into tundra in Siberia, which is not the case today. Taiga grew on the northern coast of the Sea of Azov, about 1500 km south of its present limit in European Russia. In contrast, taiga was reconstructed only slightly south of its southern limit today in south‐western Siberia. Broadleaved trees were confined to small refuges, e.g. on the eastern coast of the Black Sea, where cool mixed forest was reconstructed from the LGM data. Cool conifer forests in western Georgia were reconstructed as growing more than 1000 m lower than they grow today. The few scattered sites with LGM data from the Tien‐Shan Mountains and from northern Mongolia yielded biome reconstructions of steppe and taiga, which are the biomes growing there today.     

Airborne pollen in Padua (NE-Italy): A comparison between two pollen samplers

During recent years a gradual decrease inallergenic airborne pollen concentration hasbeen observed in the monitoring station ofPadua (Italy). Because technical checks of thesampler were not able to explain this trend,the results obtained from two twinpollen-samplers (Lanzoni VPPS 2000), placed twometres apart, were compared.An eight-week sampling was carried out duringthe year 2000 from July to September.Subsequent analysis revealed no statisticallysignificant difference between the dataobtained with the two instruments. On the otherhand, both samplers captured high levels offungal spores. We conclude that the observednegative trend in pollen count is real and notrelated to technical biases.     

长梗苦草花粉粒的电镜观察

通过扫描电镜和透射电镜首次对沉水植物梗苦草（Vallisneria longipedunculata)的花粉粒进行了观察,其花粉粒的细胞壁非常薄,无萌发孔,但有2－3个具有较质丝的凹穴。花粉粒细胞壁的覆盖层十分不明显。具散生的颗粒;外壁内层较为厚实,但柱状结构分化不明显,整体呈海绵状;花粉内壁较厚。在花粉粒内部,有大量的单粒和复粒的淀粉粒,但未见到半复粒。     

Calcium in the micropylar secretion and receptivity of explanted Crocus ovules to intra- and interspecific pollen

The micropylar secrete of the ovules of Crocus vernus ssp. vernus was analyzed for the Ca⁺² content by atomic absorption, and its capacity to germinate and attract pollen was tested by pollinating explanted ovules, and incubating in absence of culture medium. The results display a Ca⁺² concentration of 28.9 mM in the micropylar secrete. On this secrete both compatible- and incompatible pollen germinates with a mean percentage of 53.7%, and their pollen tubes enter the micropylar canal with percentages of 32.3% to 21.0%. In situ the ovules fail to attract tubes of incompatible pollen. The results are discussed in relation to the ovule receptivity and the guided growth of pollen tubes, substantiating the model of the tropic growth towards increasing calcium concentrations.     

Isolation of Allium pollen protoplasts

Studies on protoplasts isolation were carried out with mature pollen grains of 29 samples of species of Allium aflatunense, A. cepa, A. fistulosum, A. karataviense, A. longicuspis, A. nutans, A. odorum, A. sativum and A. schoenoprasum. Surface sterilized pollen grains drifted from crushed anthers were incubated in an enzyme solution containing 1% (w/v) cellulase Onozuka R-10, 1% (w/v) Macerozyme R-10, 0,5 mol l^-1 sucrose and the basal salts of Nitsch medium. Protoplasts were released within 3 to 120 min, either from the pollen grain, through a slightly disturbed germination pore (narrow aperture), or through a wider aperture, when the exine surrounding the germination pore was disturbed. For the first time, protoplasts were obtained from 13 genotypes of 6 Allium species, at a rate of 1 to 30% of the digested intact pollen grains, depending on the genotype.     

湖北秭归盆地中侏罗世陈家湾组孢粉组合的发现及其意义

本文首次报道了湖北秭归盆地陈家湾组孢粉组合,该组合可归入Cyathidites minor-Classopollis Callialasporites为代表的组合,时代属中侏罗世。陈家湾组孢粉组合的特征反映了秭归盆地中侏罗世泄滩组、陈家湾组和沙溪庙组三个组的孢粉组合的面貌基本一致,仅早期组合与中、晚期组合略有差别。建议以Gyathidites minor-classopollis-callialasportes组合代表湖北西部——重庆地区中侏罗世孢粉组合,早期为Lunzisporites pallidus亚组合,中晚期为Converrrcosisporites venitus亚组合。根据孢粉植物群在本区侏罗纪垂直分布情况,提出早侏罗世时期属亚热带一热带炎热潮湿气候环境,植物生长茂盛;早侏罗世之后,潮湿的气候仍占主导地位,但出现了干旱的先兆;中侏罗世早期进入了半干旱阶段,随后即为炎热干旱的气候所笼罩;至晚侏罗世达到非常干旱的程度,植物种类十份单调,唯有掌鳞杉科植物占据着统治地位。     

山楂蜂花粉中脂肪酸的GC-MS分析

用乙醇-氯仿作溶剂,提取出山楂蜂花粉粗脂肪,然后进行甲酯化处理,用气相色谱/质谱联用技术进行分离鉴定,共鉴定出10种脂肪酸,并测定相对含量,多不饱和脂肪酸含量较高,其中亚油酸相对含量为47.84%,亚麻酸相对含量为19.30%.