棕果蝠取食对两种榕树种子萌发行为的影响

在实验室利用聚果榕（Fieus racemosa）和对叶榕（Fieus hispida）成熟的果实饲喂笼养棕果蝠（Rousettus leschenaulti）,比较了不同处理的3组种子的萌发行为：（1）棕果蝠粪便中的种子;（2）被吐出的果渣中的种子;（3）成熟果实中的种子（对照）。棕果蝠取食行为显著影响了两种榕树种子的萌发过程,3种不同处理的种子萌发过程及最终萌发率（GP）之间都存在显著的差异。聚果榕种子经过棕果蝠消化道后GP显著降低,而对叶榕种子的GP显著提高。棕果蝠粪便中的聚果榕种子萌发开始（GS）和最短萌发时间（Tmin）均比对照种子延迟了2d,但其粪便中的对叶榕种子G5比对照种子提前了1d,Tmin提前了2d;与之相似,前者种子萌发比果实中种子提前2d达到萌发总量的50％（T50）,但后者没有改变T50。不同种榕果果渣中的种子萌发行为也有重大差异：聚果榕果渣中种子的Tmin和T50均比对照种子延迟1d,GS没发生改变;而对叶榕果渣中种子的Tmin比对照种子提前了3d,GS提前1d,T50没有改变。棕果蝠取食两种榕果后在飞行过程中排泄,进而有效的散布种子;而且通过消化明显改变了种子萌发行为,使种子萌发类型更为多样,增加了种子在不同时空条件下萌发的可能性。     

Anti‐Adhesion Activity of Tannins Isolated from the Mangrove Laguncularia racemosa

In the search of new compounds with biofilm‐inhibiting properties, mangroves with their richness of secondary metabolites can be a valuable resource. Crude methanolic leaf extracts from the mangrove Laguncularia racemosa enriched in phenolic substances cause a reduction in initial cell adhesion of Candida glabrata and Candida albicans, but not on Escherichia coli. LC/MS‐guided fractionation of the phenolic compounds resulted in 19 fractions, of which ten were analyzed for their bioactivity against cell adhesion. Effects on cell adhesion and planktonic growth of Escherichia coli, Candida glabrata and Candida albicans were measured in 96‐well microtiter plates in the presence of 0.2 mg ml^?1 of the isolated fractions. Two fractions caused a reduction of cell adhesion of Candida albicans. These fractions containing bioactive compounds were analyzed by LC/MS and NMR spectroscopy. Casuarinin and digalloyl‐hexahydroxydiphenoyl‐glucose were identified in the active fractions, in addition to three signals of ellagitannins. These results indicate a specific mode of action of hydrolysable tannins against cell adhesion of Candida albicans, which needs to be further analyzed.     

N:P stoichiometry in Ficus racemosa and its mutualistic pollinator

Aims Nitrogen (N) and phosphorus (P) are limiting nutrients to life across a variety of ecosystems. N:P stoichiometry, concerning the balance of these two elements, has recently received great attention. However, little is known about the nature of N:P stoichiometry in obligate mutualism.Methods N:P stoichiometry of Ficus racemosa and its pollinating wasp Ceratosolen fusciceps, an example of coevolving obligate mutualism, was investigated, and the N:P stoichiometric traits of male versus female wasps were compared.Important findings Nutrient concentrations in C. fusciceps were much higher than in its host. N enrichment in fig wasp was evidently stronger than phosphorus. N concentrations of male fig wasps were significantly higher than those of females, while P concentrations of female fig wasps were remarkably higher than those of male ones. Therefore, N:P ratios in male fig wasps were significantly greater than in female fig wasps. N:P ratio in fig-pollinating wasp displayed linear functions to fig N contents, suggesting that N limitation in fig wasps may dominate the nutritional relationship between fig pollinator and its host. Fig wasp population size had significant influences on N concentrations in host fig and female wasp per se. Driven by the nutritional stress of pollinating and parasite insects, fig fruit preferred increasing its diameter first but not nutrient richness. Values for N and P contents of fig pollinators showed seasonal differences with greater N:P ratios in dry season than in rainy season. The observations suggest that tropical climate change would result in more severe N limitation to fig-pollinating wasp and may further influence the stability of fig–fig wasp mutualism.     

Long‐term dynamics of the long‐lived conifer Libocedrus bidwillii after a volcanic eruption 2000 years ago

Abstract. Question: Following a volcanic eruption of ca. 232 AD, known as the Taupo eruption, the emergent conifer Libocedrus bidwillii expanded on Mt. Hauhungatahi, upwards above the current tree‐line, and downwards into the mixed montane forest. We ask: (1) if current age‐structures at different altitudes support the patterns predicted by the temporal stand replacement model, with cohort senescence and progressively depleting recruitment at ca. 600 year intervals (average cohort age) since the eruption: and (2) if the case history of the population sheds light on the persistence of mixed conifer‐hardwood forests in general. Location: Mt. Hauhungatahi, Tongariro National Park, New Zealand. Methods: The species composition and structure of seven stands covering the altitudinal range of Libocedrus bidwillii, were quantified. Libocedrus trees were cored, and regression equations used to predict ages. Cohorts were identified. Results: Libocedrus densities and basal areas, and the abundance of seedlings and saplings, peaked at different altitudes. At the species’lower limits there has been no recruitment for ca. 550 years, and the angiosperm Weinmannia racemosa has gained dominance. In the tree line and sub‐alpine forest stands, a low level of continuous regeneration has been boosted by periodic cohort recruitment following exogenous disturbances. Conclusions: In the montane zone, the Libocedrus age structure, and its replacement by Weinmannia, are consistent with a model of depleting cohorts separated by ca. 600 years since the Taupo eruption. At higher altitudes more frequent disturbances and reduced competition have allowed Libocedrus persistence. Comparison with other studies suggests long‐term relationships between gymnosperms and angiosperms are mediated by the scale and frequency of disturbance.     

Three New Butenolides from the Green Alga Caulerpa racemosa var. turbinata

Three new butenolides, caulerpalide A and a pair of enantiomers, (+)‐caulerpalide B and (?)‐caulerpalide B, together with seven known compounds, have been isolated from the green alga Caulerpa racemosa var. turbinata. All these structures were determined by spectroscopic techniques. The absolute configurations of caulerpalide A, (+)‐caulerpalide B and (?)‐caulerpalide B were elucidated by the method of ECD calculation. This is the first separation of butenolides from the algae of genus Caulerpa. Additionally, the antibacterial activities of the nine isolated compounds were also evaluated.     

Phytochemical fingerprinting to thwart black cohosh adulteration: a 15 Actaea species analysis

Introduction – The popular use of black cohosh products (Actaea racemosa L., syn. Cimicifuga racemosa L.) is growing as the demand for alternatives to estrogen therapy has increased. Critical to safe use is the assurance of unadulterated, high‐quality products. Questions have been raised about the safety of black cohosh due to cases of liver toxicity in patients who reported taking it; subsequent evaluation found some products to be adulterated with other related herbal species. Correct plant species identification is a key first step for good manufacturing practices of safe black cohosh products. Objectives – To develop analytical methods which distinguish black cohosh from other species (American and Asian) of Actaea increasingly found as adulterants in commercially available black cohosh products. Material and methods – Fifteen species of Actaea were collected from North America and Asia, and the phytochemical fingerprints of these samples were established using HPLC‐PDA and LC‐MS techniques. Results – The HPLC and LC‐MS fingerprints for polyphenols and triterpene glycosides revealed distinct patterns that make black cohosh clearly distinguishable from most other species of Actaea. Two marker compounds, cimifugin and cimiracemoside F, were found to be important to distinguish black cohosh from most Asian species of Actaea. Formononetin was not found from either Asian or American species of Actaea. Conclusions – Phytochemical fingerprinting is a practical, reliable method for authenticating black cohosh and distinguishing it from other species of Actaea increasingly found as adulterants in commercially available black cohosh products. This should facilitate the continued development of high‐quality, unadulterated black cohosh products. Copyright © 2011 John Wiley & Sons, Ltd.     

Genetic evidence for the identity of Caulerpa racemosa (Forsskål) J. Agardh (Caulerpales,Chlorophyta) in the Adriatic Sea

Three taxa of Caulerpa racemosa that differ morphologically and genetically have been reported in the Mediterranean Sea. The ‘invasive variety’ was recorded for the first time in the early 1990s in Libya. In less than 10 years, it was found in almost all parts of the Mediterranean. The first record of C. racemosa in the Croatian part of the Adriatic Sea was in 2000 and as many as 35 different localities were established by the end of 2004. In terms of morphology, the specimens from the Adriatic Sea resemble the ‘invasive variety’. To confirm this, we analysed populations from two different localities (the island of Mljet and the peninsula of Pelje?ac) using the ITS1-5.8S-ITS2 region of 18S-5.8S-26S rDNA unit as a molecular marker. The ITS1-5.8S-ITS2 region from nine individual plants was amplified by PCR, cloned in a pCR 2.1 vector and sequenced. Phylogenetic comparison of sequences from specimens found in the Adriatic Sea with specimens of the same and similar taxa, found both inside and outside the Mediterranean, provided genetic evidence that C. racemosa populating the Adriatic Sea corresponds to the Mediterranean C. racemosa var. cylindracea (Sonder) Verlaque, Huisman?&?Boudouresque, i.e. to the ‘invasive variety’.     

The confounding effects of logging on tree seedling growth and herbivory in Central Amazon

Light availability is an important modulator of seedling growth and plant–herbivore dynamics. Logging increases light levels in forests, potentially altering herbivore–plant interactions that drive seedling establishment. We conducted a transplant experiment to evaluate how logging and herbivory affect seedling growth and survival in three shade‐tolerant tree species, at paired canopy gap and understory sites in logged forest and an adjacent unlogged area in central Amazonia (Brazil). Seedlings were either left exposed to naturally occurring insect herbivores or protected from insects by a fine netting structure. We measured the herbivore damage and growth rate of seedlings after 18 mo. In general, logged areas received more light than unlogged sites. Growth and herbivory rates were positively influenced by light, and herbivory was also influenced positively by logging. In gaps, increased growth mitigated foliar damage. Logging resulted in a loss of foliar tissue due to increased herbivory. Herbivory rates were higher in the understory of logged sites than in that of unlogged understory sites, but growth was similar in these areas. Thus, the understory of logged areas provided the least favorable sites for shade‐tolerant tree regeneration, due to higher herbivory rates. The effect of logging on biotic interactions can extend beyond the gaps it creates into untouched understory sites. To our knowledge, this is the first time such a pattern has been observed, highlighting the importance of evaluating the impact of logging on biotic interactions.     

香港地区红树植物资源研究(Ⅱ)——红树植物Lumnitzera racemosa(榄李)抑制植物真菌有效成分的分离与鉴定

本文对红树植物榄李(Lumnitzera racemosa)茎的95％乙醇提取物进行了抑制植物真菌(Fusarium oxysporum,Helminthosporium.sp,Stemphyllium.)效能的研究,并对其抑菌有效成份进行了分离与鉴定,研究结果表明,丹宁(tanning)(来自水相提取物)是抑菌的主要活性组份,其它还有黄酮类似物,脂肪酸等(来自于氯仿提取物)也有一些抑菌能力。