花粉高尔基囊泡与牛脑微管的体外结合

把从榛木（Ｃｏｒｙｌｕｓａｖｅｌｌａｎａ Ｌ．）花粉中分离得到的高尔基囊泡与经高度纯化并聚合好的牛脑微管进行体外组合,然后于１．５ ｍ ｏｌ／Ｌ的蔗糖层上进行超离心,对其沉淀物进行ＳＤＳ－聚丙烯酰胺凝胶电泳和电镜负染。结果表明,花粉高尔基囊泡可以结合到牛脑微管上,证明植物花粉的高尔基囊泡与动物细胞的某些细胞器一样,也与细胞骨架的主要组成之一——微管具有结构上的紧密联系。花粉高尔基囊泡与牛脑微管的体外结合能力,受１０ ｍ ｍ ｏｌ／ＬＡＴＰ和０．５ ｍ ｏｌ／ＬＫＣｌ的影响,但不受５ ｍ ｍ ｏｌ／Ｌ ＡＭＰ－ＰＮＰ的影响,说明两者结合可能是通过高尔基囊泡表面与ＡＴＰ有关的某种外周膜蛋白来完成的。     

中国蓼属植物花粉形态的研究

本文用光学显微镜和扫描电镜对国产44种2变种蓼属植物的花粉形态进行了观察。除了前人报道的31种外,其中15种为首次报道。本属花粉形态多类型,有球形、近球形、近扁球形、近长球形及长球形;从萌发孔来看,有三沟型、三孔沟型、散沟型及散孔形：外壁纹饰有颗粒-穿孔、微刺-穿孔、微刺-凹穴、细网状、皱块状及粗网状。根据这些特征将花粉划分为10种类型,其中西伯利亚蓼型(Sibir-icum-type)为本文首次提出。文中对本属的分类问题进行了探讨,不支持Steward(1930)将本属划分为8个组的意见,而认为应将本属划分为11个组。     

Easy determination of ploidy level in Arabidopsis thaliana plants by means of pollen size measurement

Summary Cytogenetic examination of transgenic Arabidopsis thaliana (L.) Heynh. plants obtained by Agrobacterium-mediated gene transfer to cotyledon- and root-explants or by direct gene transfer into protoplasts revealed a high percentage of tetraploid or aneuploid transformants. Depending on the transformation procedure used, 13% (root explant transformation), 33% (cotyledon explant transformation), or 38% (direct gene transfer) of the transformants showed aberrant ploidy levels. A good correlation between the ploidy level of a plant and the size of its pollen grains was observed. This allows quick and simple testing of the ploidy level of transgenic Arabidopsis plants.Abbreviations AM Arabidopsis medium - ANOVA analysis of variance - DAPI 4,6-Diamidino-2-phenylindole - PEG polyethyleneglycol     

Pollination success in a population of dioecious rain forest trees

Pollination success in female trees was determined for a population of Neolitsea dealbata (R. Br.) Merr., a locally abundant dioecious tree pollinated by small, unspecialized insects in northern Queensland rain forest, Australia. The population consisted of a clustered group of trees with a mean male-to-female distance of 4.5 m and more isolated individuals, including females more than 90 m away from the nearest pollen source. A map of all reproductive trees was produced to determine accurate male-to-female distances. The size of the pollen source available to females was defined as a function of the distance to the nearest ten male trees and their sizes (male neighbourhood index). The rate of pollen movement to females was measured by counting pollen tubes (and the number of tubes per style) in female trees 6 days after the commencement of population flowering. The pollination rate decreased steeply to less than half when the nearest male was only 6.5 m away. Although pollen reached a female 330 m away from the nearest pollen source, only 10% of receptive flowers had been pollinated. The short flowering period (2–3 weeks) combined with the the slow rate of pollen movement means that a large proportion of flowers in isolated trees are unpollinated, confirming an earlier finding that isolated females set fewer fruits than gregarious females. The reliability of pollen transfer to females was determined by quantifying insects and their pollen loads trapped at female trees with a range of male neighbourhood indices. Quantities of insects and pollen were significantly correlated with the size of the male neighbourhood index, indicating a strong density-dependent response by vectors to flowering. Pollen was also collected from insect visitors to non-flowering trees. Females with large male neighbourhood indices received more pollen than non-flowering trees with equivalent male neighbourhood indices. However, when the male neighbourhood indices were small for both female and non-flowering trees, the changces of pollinators encountering female and non-flowering trees were similar, suggesting random movements of pollinators in sparse-flowering sub-populations. The dioecious breeding system, brief, synchronous flowering period, clustered population structure and random, opportunistic foraging behaviour of vectors interacted in a way that reduced reproduction in relatively isolated trees. These results demonstrate a mechanism for differential breeding success between trees in natural populations and emphasize the possible impact of logging regimes on pollen flow between trees. Large interconspecific distances in species-rich environments may have been a factor in the selection for synchronous flowering between trees in outcrossing tree species with generalist insect pollinators.     

Endocytotic uptake of fluorescent dextrans by pollen tubes grown in vitro

Summary Pollen tubes grow by tip growth, with high levels of exocytosis at the apex. The commercial availability of FITC labelled -linked dextrans provides a source of biologically inert tracers for endocytotic activity in pollen tubes. Growing tubes ofNicotiana andTradescantia were transferred to media containing 1% FD-4 for varying period of time before washing in control media and observation in a fluorescence microscope. Fluorescent material appeared to enter the pollen tubes only at the tip region, and to accumulate in vacuoles, starting with smaller vacuoles near the tip and spreading to the main vacuolated part of the tube. Mature tubes, with callose plugs, were only labelled up to the first complete plug from the tip, younger tubes without plugs were labelled into the pollen grain vacuole. The fluorescent material within the pollen tubes was shown to represent uptake of intact high molecular weight dextran by the following criteria: (i) free FITC and low molecular weight dextrans could not be detected in any of the media or pollen tubes using thin layer chromatography and (ii) pollen tube growth rates were unaffected by the fluorescent dextran, but were severely inhibited by low levels of free FITC. It was concluded that the dextrans entered the tubes by endocytosis, possibly in the tip region, and were then transferred to the vacuole system of the pollen tube.Abbreviations FITC fluorescein isothiocyanate - FD fluorescent dextran     

25000年以来渤海湾西岸古环境探讨

 本文依据孢粉、微体古生物、放射性碳测年、因子分析等资料,表明25000a,BP 以来渤海湾西岸的古植被,古地理环境演变既受气候冷暖变化的影响,又受海平面变化的制约。25000—23000a,BP 为高海平面时期,古植被为森林草甸植被,23000—12000a,BP,气候冷干,为低海平面时期,以草原植被为主,前期和后期为沼泽草甸植被。12000—5000a,BP 气候温凉或温暖湿润为海平面上升时期,为阔叶林草甸或沼泽草甸植被,5000a,BP 以来,气候变凉变干,为海退时期,古植被由沼泽草甸演变为盐生草甸。     

Responses of alfalfa pollen and callus to filtrates from two isolates of Fusarium oxysporum

Summary For 25 Medicago sativa plants, measurements were made of in vitro pollen germination and growth and callus growth on mediums containing culture filtrate from two isolates of Fusarium oxysporum f. sp. medicaginis. In vivo resistance was determined by field inoculation with one isolate. There was no correlation between any in vitro measurement and in vivo resistance, and none of the in vitro measurements on control mediums were correlated. The only significant correlation for the same measurement between the two isolates was for pollen-tube length (r = 0.65). Percent of pollen germination was negatively correlated with callus growth for both isolates. Earlier work showed that callus growth in the presence of culture filtrate was linked to plant resistance, thus it appeared that percent pollen germination on culture filtrate had decreased for the more resistant plants. The haploid pollen may be used as a progeny test for identifying heterotic loci conferring resistance to Fusarium, but if the pollen of this plant species is used in direct selection by exposure to culture filtrate, the level of resistance to Fusarium may decrease.     

The effects of grazing on the pollen production of grasses

Samples from moss polsters taken over three consecutive years during a controlled grazing experiment in a nature reserve in the Netherlands were analysed for their pollen content, particularly grass pollen. Samples were also taken in the year following the experiment, with grazing pressure strongly diminished. This yielded data regarding the effect of grazing on the pollen production of grasses in open habitats, plantations, and unproductive and productive woods under different grazing pressures.     

Palynological and palaeobotanical investigations in the area of the post-medieval Helsinki Old Town

Pollen, phytolith, and plant macrofossil analyses were carried out on the cultural layers of Helsinki Old Town excavated by the Helsinki City Museum and dated to the 15–17th centuries. Cultural mineral soil layers, a former ditch, a well, one waste pit, one waste heap and three house areas were investigated. The results show that-within certain limits-pollen in the mineral soil reflects the cultural changes of the local settlement from rural to urban. Among the main anthropogenic indicators, the high NAP (non-arboreal pollen) frequencies, the low pollen concentration values, and especially the high frequencies of Cichoriaceae (Liguliflorae) pollen should be emphasized. The macrofossil data were used to determine the species list of the herb pollen and to make a more detailed reconstruction of the local vegetation at Helsinki Old Town.