City spore concentrations in the European Economic Community (EEC). VI. Poaceae (Grasses), 1982–1986

Summary Airborne grass-pollen concentrations in six cities in the EEC are compared, based on observations from five years, 1982–1986. Results show that there are quantitative differences both between the monitoring stations and between the years. Very provisionally, the average seasonal total of the European urban airborne grass-pollen concentration can be put at 4 to 5000 per m³ of air. Also qualitatively, regarding the seasonal fluctuations, there are differences between the stations, and between the years. Generally, the results confirm that June is the most typical grass-pollen month in northwestern Europe, whereas in mediterranean Europe May is the more prominent grass-pollen period. There seems to be little coherence between the starting dates of the grass-pollen season even at relatively nearby stations in northwestern Europe, suggestive for a great influence of the actual weather situation.     

Ontogeny of intruding non-periplasmodial tapetum in the wild chicory,Cichorium intybus (Compositae)

The tapetal development ofCichorium intybus L. is investigated using LM and TEM and discussed in relation to the development in other species. During the second meiotic division the tapetal cells become binucleate and lose their cell walls. They intrude the loculus at the time of microspore release from the meiotic callose walls, which means that a locular cavity is never present in this species. During pollen development they tightly junct the exine, especially near the tips of the spines. During the two-celled pollen grain stage they degenerate and most of their content turns into pollenkitt. Until anther dehiscence they keep their individuality, which means that these intruding tapetal cells never fuse to form a periplasmodium. The ultrastructural cytoplasmatic changes during this development are discussed in relation to possible functions.     

三水盆地早白垩世白鹤洞组的被子植物花粉*

系统描述了区内早白垩世白鹤洞组的被子植物花粉,11属20余种.结合前人研究成果,对一些容易混淆的属种作了区分性的讨论.据所发现的被子植物花粉的组合面貌,将白鹤洞组归人中晚阿尔必期.     

Nuclear DNA content and separation of Nicotiana sylvestris vegetative and generative nuclei at various stages of male gametogenesis

At all stages of male gametogenesis, generative and vegetative pollen nuclei of Nicotiana sylvestris can be distinguished without ambiguity after Feulgen or ethidium bromide staining. They differ by their morphology and their apparent DNA content, always lower in vegetative nuclei. These differences provide a basis for their separation by sedimentation and fluorometry. After elimination of the another somatic cells and after crushing the pollen, vegetative and generative nuclei are separated by two successive Percoll gradients (purity 80–90%). Analysis of the gradient fractions and final purification can be done with a cell sorter. DNAs of both types are isolated by a cetyltrimethylammonium method, followed by a RNase treatment. Yields are lower for vegetative than for generative nuclei, and decrease with the age of pollen. Molecular weights and digestibility by restriction enzymes are compatible with molecular analyses.     

Floristic and structural variation in the Tamaulipan thornscrub,northeastern Mexico

Abstract. A generalized research strategy is presented for identifying the ecological effects of the physical environment and management in a poorly known region of subtropical, semiarid thornscrub in northeastern Mexico. Vegetation samples were stratified across a small number of climatic subregions, substrate types and topographic situations. Classification analysis and PCo A of the species x site matrix of incidence data after application of the Information Statistic were used. The analyses suggested that the regional variation in climate, substrates and topography was responsible for the major floristic differences in the vegetation. The distributions of most plant species were related to the variation in the physical environment. PCo A of the species x site cover data after application of the Bray-Curtis dissimilarity metric revealed evidence of vegetation change due to overgrazing in each major floristic group, but not to selective cutting for timber and firewood.     

Chromosome association and pollen fertility of parental and interspecific hybrids of Lycopersicon esculentum X L. hirsutum and L. pennellii

Cytological studies were carried out on two wild species (L. hirsutum and L. pennellii) and the cultivated species (L. esculentum) of tomato and their F1 hybrids. Both parents and hybrids show a diploid chromosome number of 2n=24. The meiotic behaviour of the cultivated species showed a high degree of chromosome homology resulting in a high level of chiasmata frequency per bivalent. In contrast, the two wild species showed a slight increase in uniyalent frequency and a decrease in bivalent formation and chiasmata frequency. The meiotic behaviour of the hybrids showed a high level of univalents and low levels of bivalents as well as trivalents. Highly significant decreases in chiasmata frequency and increases in meiotic abnormalities, especially in the L. esculentum X L. pennellii hybrid, also were detected. The high meiotic irregularity and low chiasmata frequency recorded in the second hybrid indicated the disharmony and difference between its parental genomes and also served to predict its sterility. With regard to degree of pairing recorded in the hybrids, there is a possibility that sterility in such cases may refer to genetic factors in addition to the previously mentioned reasons. Pollen fertility showed no great difference between L. esculentum and L. hirsutum and their F1 hybrid, but a significant decrease was recorded in the L. esculentum X L. pennellii hybrid, which was clearly associated with high meiotic irregularity, low chiasmata frequency and chromosome association.     

芸苔属脱外壁花粉的分离与人工萌发

芸苔属青菜（Ｂｒａｓｓｉｃａ ｃｈｉｎｅｎｓｉｓ）与紫菜苔（Ｂ． ｃａｍ ｐｅｓｔｒｉｓｖａｒ． ｐｕｒｐｕｒｅａ）的花粉经低温水合、热激、渗激三步程序,分离出大量具萌发能力的脱外壁花粉,脱外壁率可高达６０％ 以上。在含有碳源与氮源及Ｒｏｂｅｒｔｓ培养基盐成分的碱性ＰＥＧ 培养基中,首次使芸苔属脱外壁花粉萌发,萌发率可达３３％ ～４１％ 。在扫描电镜下观察了花粉脱外壁与萌发的过程。讨论了不同植物花粉脱外壁的方法与花粉壁生物学特点的对应关系,以及外壁对花粉萌发的可能作用     

Structures and contribution to the antigenicity of oligosaccharides of Japanese cedar (Cryptomeria japonica) pollen allergenCry j I: relationship between the structures and antigenic epitopes of plantN-linked complex-type glycans

The oligosaccharide structures ofCry j I, a major allergenic glycoprotein ofCryptomeria japonica (Japanese cedar, sugi), were analysed by 400 MHz¹H-NMR and two-dimensional sugar mapping analyses. The four major fractions comprised a series of biantennary complex type N-linked oligosaccharides that share a fucose/xylose-containing core and glucosamine branches including a novel structure with a nongalactosylated fucosylglucosamine branch.Rabbit polyclonal anti-Cry j I IgG antibodies cross-reacted with three different plant glycoproteins having the same or shorter N-linked oligosaccharides asCry j I. ELISA and ELISA inhibition studies with intact glycoproteins, glycopeptides and peptides indicated that both anti-Cry j I IgGs and anti-Sophora japonica bark lectin II (B-SJA-II) IgGs included oligosaccharide-specific antibodies with different specificities, and that the epitopic structures against anti-Cry j I IgGs include a branch containing 1–6 linked fucose and a core containing fucose/xylose, while those against anti-B-SJA-II IgGs include nonreducing terminal mannose residues. The cross-reactivities of human allergic sera to miraculin andClerodendron Trichotomum lectin (CTA) were low, and inhibition studies suggested that the oligosaccharides onCry j I contribute little or only conformationally to the reactivity of specific IgE antibodies.Abbreviations Cry j I a major allergenic glycoprotein ofCryptomeria japonica - B-SJA-II Sophora japonica bark lectin II - CTA Clerodendron trichotomum lectin - TFMS trifluoromethanesulfonic acid - HRP horseradish peroxidase     

Accumulated effect of elevated ultraviolet-B radiation over multiple generations of the arid-environment annual Dimorphotheca sinuata DC. (Asteraceae)

Two D. sinuata populations, established from the same seed batch, were cultured concurrently under ambient (2.5–8.9 kj m^?2 d^?1) and enhanced (4.7–11.4 kj m^?2 d^?1) ultraviolet-B radiation for two consecutive generations. The two populations, designated low- and high-UV-B cultivars, were each grown for an additional generation under both UV-B fluences at different alignments. Differences in plant performance were examined between UV-B treatments (immediate UV-B effects), cultivars (accumulated UV-B effects), alignments and their interactions. Accumulated UV-B had a greater effect on plant performance than immediate UV-B. The former induced earlier reproductive effort, substantial (up to 35%) reductions in dry mass (stems, leaves and reproductive organs), decreased stem and inflorescence production, and diminished steady-state fluorescence yields, chlorophyll a concentrations, pollen tube growth and germination of seeds set. The latter caused only diminished non-photochemical quenching, reduced chlorophyll a, soluble sugar and starch concentrations, decreased pollen germination, and increased carotenoid contents. Interactions between UV-B fluence level and alignment occurred for all measured dry mass parameters, leaf area, photosynthetic pigment and soluble sugar concentrations, and germination success of seeds set. These results indicate altered DNA integrity rather than an indirect UV-B effect of photomorphogenic origin.