Sesquiterpenes from Cupressus macrocarpa foliage

Ten sesquiterpenes, many with unusual carbon skeletons, were identified in foliage of Cupressus macrocarpa. These are (-)-10-epi-beta-acoradiene; ent-widdra-2,4(14)-diene; (E)-iso-gamma-bisabolene, i.e., (4E)-4-(1,5-dimethylhex-5-enylidene)-1-methylcyclohexene; (-)-cumacrene, i.e., (4S)-4-[(1R,2S)-2-isopropenyl-1-methylcyclobutyl]-1-methylcyclohexene; (-)-alpha-chamipinene, i.e., (1S,6S,7S)-2,2,6,8-tetramethyltricyclo[5.3.1.01,6]undec-8-ene; and five sesquiterpenes with a 3,3,4'-trimethyl-1,1'-bi(cyclohexyl) skeleton for which the trivial name macrocarpane is proposed. The possible single-enzyme biogenesis of these sesquiterpenes is discussed.     

Meteorological phenomena affecting the presence of solid particles suspended in the air during winter

Winter is not traditionally considered to be a risky season for people who suffer from pollen allergies. However, increasing numbers of people are showing symptoms in winter. This prompted our investigation into the levels of solid material in the air, and some of the meteorological phenomena that allow their accumulation. This study showed a possible relationship between the phenomenon of thermal inversion, which occurs when very low temperatures, cloudless skies and atmospheric calms coincide, and an increase in the concentration of solid material in the atmosphere. Frequently, this situation is associated with other predictable phenomena such as fog, dew and frost. This may allow a warning system to be derived for urban pollution episodes. The effect caused by parameters such as wind and rainfall was also analysed. Solid material was differentiated into non-biological material from natural and non-natural sources (e.g. soot, dust, sand, diesel exhaust particles, partially burnt residues) and biological material. The latter mainly comprises pollen grains and fungal spores. Owing to its abundance and importance as a causal agent of winter allergies, Cupressaceae pollen was considered separately. Received: 28 April 1999 / Revised: 16 November 1999 / Accepted: 17 November 1999     

水分胁迫和复水对石灰岩地区柏木幼苗根系生长的影响

利用适生植物自身的抗旱能力来进行石灰岩地区植被的恢复和重建是石灰岩生态研究中的重要问题.为了解石灰岩山地适生物种柏木对水分胁迫的适应机制,以柏木实生苗为材料,通过盆栽水分受控实验,研究了其根系生长特性及复水后的修复能力.结果表明:在水分胁迫程度不大、历时不长的情况下,水分胁迫有诱导根系下扎的趋势,复水后,根长在原有的基础上进一步伸长.随着胁迫的加剧和胁迫时间的延长,柏木幼苗的根长、根平均直径、根表面积和根体积等根系大小参数均呈降低趋势,以采取小根系来增强竞争力.复水后,除重度干旱外,其余处理组根系大小参数都能恢复到对照水平,补偿作用与胁迫程度有关.一定程度的水分胁迫对柏木幼苗的茎叶生长没有产生影响,而对根的抑制作用明显,根冠比降低,但胁迫程度加剧和历时延长后,柏木幼苗的根冠比有增大的趋势.柏木幼苗在水分胁迫较轻时把较多的碳水化合物分配到茎叶中,而胁迫严重时把较多的碳水化合物分配到根部.复水促进根、冠干物质的积累,但不同的胁迫程度和胁迫时间促进作用不同.     

Unreduced diploid nuclei in Cupressus dupreziana A. Camus pollen

Size and DNA content of pollen of Cupressus dupreziana A. Camus, a highly endangered Mediterranean conifer, were assessed by cytomorphological observations and flow cytometric analyses and then compared to C. sempervirens L. pollen. Mature C. dupreziana pollen was composed of two uninucleated types of pollen grains differing in size. Around 35% of the grains exhibited a size similar to C. sempervirens pollen, while 65% exhibited a larger diameter. However only one peak of fluorescence was detected by flow cytometry. DNA content of C. dupreziana pollen was twice the DNA content of C. sempervirens pollen. Comparison of DNA contents of mature and germinating pollen revealed that mature pollen of both species were arrested in the G2 phase. Comparison with the DNA content of somatic tissue (2C) provided evidence for the production of unreduced pollen in C. dupreziana. This unexpected feature in gymnosperms is discussed in terms of reproductive strategy of this species. Received: 11 December 1999 / Accepted: 22 December 1999     

Search strategies of fruit flies in steady and shifting winds in the absence of food odours

Abstract. Flight behaviour by females of two species of fruit flies, Drosophila funebris and Drosophila immigrans , was videorecorded in a wind tunnel in still air and in wind with a constant or shifting direction. Flies which were deprived of food overnight took flight in the absence of food odours. Both species responded to the presented winds in agreement with two models that predict the shortest distance to an odour plume. According to these models, the shortest distance to an odour plume is travelled when insects fly at right angles to the wind with a steady direction. In winds shifting over more than 60, the shortest distance to an odour plume is achieved when insects fly parallel to the time-averaged wind direction. We propose a behavioural mechanism which accomplishes the observed flight directions taken by the two species of fruit flies in response to the tested wind regimes.     

Biometrical variability of foliage and cone characters inCupressus bakeri (Cupressaceae)

Biometrical variability of foliage, cones, and seeds were analyzed in 8 native populations (throughout the range) of a relictual species,Cupressus bakeri Jeps. (Cupressaceae) from California and Oregon. The partition of variation within and among populations for this rare plant was investigated and the justification for subspecies status was reviewed. Morphological characters varied significantly, with more of the variation among populations than at the population level. Multivariate analyses indicated close affinities among populations on serpentine sites suggesting the presence of a serpentine race. However, the high degree of variation among populations did not permit their clear separation into the two subspecies described byWolf (1948). We conclude thatC. bakeri should be treated as a monotypic species.     

Flora Palinologica Italiana,Sezione Aeropalinologica —S 103:Cupressus sempervirens L

Summary This contribution to the ?Palynological Italian Flora, Aeropalynological Section? deals withCupressus sempervirens L. (Mediterranean cypress). Palynological card regards fresh and acetolyzed pollen.      

Unexpected DNA content in the endosperm of Cupressus dupreziana A. Camus seeds and its implications in the reproductive process

 Nuclear DNA content of embryo and endosperm from mature and immature Cupressus dupreziana A. Camus seeds was estimated using laser flow cytometry. Relative DNA content of endosperm nuclei corresponded to four ploidy levels: 2C, 4C, 6C and 8C. The embryo nuclei invariably exhibited a diploid pattern. In all endosperm tissue analyzed no haploid nucleus was found. This is problematic since, in gymnosperms, endosperm and female gametes originate from one functional haploid megaspore produced by meiosis. The possible origin and derivation of C. dupreziana endosperm are discussed in light of previous results concerning the two other Mediterranean cypresses, C. sempervirens and C. atlantica. Received: 15 January 1998 / Revision accepted: 27 March 1998