Limitations of a random screen: Search for new anticancer drugs in higher plants

The inherent limitations of a random search of higher plants for novel cancer chemotherapeutic agents are reviewed—the National Cancer Institute’s (NCI) Anticancer Screening Program. A graphic summary of plant exploration for the NCI is depicted on a world map showing 58 floristic regions. It is estimated that less than one-half of the world flora is economically feasible for collection. Random screening of approximately 35,000 species has led to guidelines that precluded further screening of all species in 333 genera and another 2,905 species in 1,773 genera. These taxa are reported to represent one-half to two-thirds of the species that characterize vegetation in geographic areas most frequently explored for the NCI. It is estimated that 40,000 untested species of flowering plants are readily available and meet the NCI guidelines for antitumor screening. However, because of apparent diminishing returns from random screening of chemicals in plant genera, it is suggested that a good representation of the diversity in the world flora could be obtained in 10,000 collections, if random sampling follows the phytogeographic outline that is recommended. Modifications to the screening methodology might be geared to an expected point of diminishing returns for discovering novel chemotypes. Additionally, the NCI should continue random screening to increase the development of new anticancer drugs; past screening has generated a tremendous wealth of data. Finally, in this paper, the author proposes to utilize lists representing taxa commonly collected for the NCI to create a manual of worldwide common plants.     

神农架国家级自然保护区药用苔藓植物的研究

对神农架国家级自然保护区药用苔藓植物进行了初步研究,结果表明,共有20种药用苔藓植物,隶属于14科18属,其中苔类3种,藓类17种.     

中国与北美苔藓植物区系关系的探讨

关于中国和北美间苔藓植物区系关系的研究是在20世纪90年代开始的。研究表明中国和北美苔类和藓类的种间关系疏远,这一事实说明两个大陆在第三纪后期分离后,由于地质、地理、气候等因素的差异致使苔藓植物区系成分也产生明显分异。虽然它们在科、属方面差异较小,但两个大陆已各自形成地区特有的苔类和藓类的属。已知的中国特有及东亚特有的苔类属有5个,藓类属有22个;而已知北美地区特有的苔类属有4个、藓类属有5个。北美东部和西部形成于不同地质时期,在苔藓植物方面与中国共同分布的科、属和种存在一定差异。从神农架藓类植物研究表明,从共同分布的种来看,北美东部与中国比北美西部与中国的相似性系数高约6％。从两地区间苔类和藓类植物的雌雄同株或雌雄异株及孢子直径大小而论,这两个因素似乎并不是影响苔藓植物在两大地区间分布的主要原因,但对苔藓植物的分布仍然十分重要。本文作者认为结合中国和北美的地史、地理条件及苔藓植物自身的特点,可以认为白令海峡不是阻碍中国和北美苔藓植物交流的绝对自然屏障;中国和北美苔藓植物区系关系目前的状况,是长期多次交流融合和分异的结果。     

Tree hollows can affect epiphyte species composition

Tree hollows often harbor animals and microorganisms, thereby storing nutritive resources derived from their biological activities. The outflows from tree hollows can create unique microenvironments, which may affect communities of epiphytic organisms on trunk surfaces below the hollows. In this study, we tested whether the species richness and composition of epiphytic bryophytes (liverworts and mosses) and lichens differ above and below tree hollows of Aria japonica and Cercidiphyllum japonicum in a Japanese temperate forest. The species richness of epiphytic bryophytes and lichens did not differ above and below hollows; however, the species composition of bryophytes differed significantly above and below hollows. Indicator species analyses showed that the moss species Anomodon tristis and the liverwort species Porella vernicosa were significantly more common below than above hollows, while the liverwort species Radula japonica and four lichen species, including Leptogium cyanescens, occurred more frequently above than below hollows. Our results highlight that tree hollows can produce unique microenvironments on trunk surfaces that potentially contribute to the maintenance of epiphytic diversity on a local scale.     

浙江省清凉峰自然保护区苔藓植物区系成分研究

通过对2013~2014年于清凉峰自然保护区采集的1 500余份苔藓植物标本进行鉴定和文献研究,统计分析了清凉峰自然保护区苔藓植物种类组成,区系地理成分及特点,并对该地区与相邻8个地区藓类植物的丰富度系数比较和相似性系数比较,以明确该地区苔藓植物不同的生态分布类型,揭示浙江清凉峰保护区苔藓植物多样性的变化规律。结果表明:(1)浙江省清凉峰国家自然保护区苔藓植物共有62科143属337种(包括3个变种),其中苔类植物20科29属49种,藓类植物42科114属288种。(2)藓类植物的优势科9个、优势属16个。(3)该地区苔藓植物区系成分主要以东亚成分为主(占总种数41.84%),温带成分次之(占总种数28.57%),热带成分再次之(占总种数20.74%)。(4)浙江清凉峰自然保护区苔藓植物区系与浙江省境内的金华山、大盘山、天目山和凤阳山的亲缘关系较为密切。(5)浙江清凉峰自然保护区苔藓植物生态分布类型复杂多样,以石生类型(占总标本数的47.09%)最多,其次为岩面土生(占总标本数的27.68%)和土生(占总标本数的12.85%)类型。     

木林子国家级自然保护区苔藓植物物种与区系研究

基于野外调查、采集标本和查阅文献,对木林子国家级自然保护区苔藓植物物种及区系特点进行研究。结果显示:该保护区苔藓植物共有64科121属292种,其中,苔类28科38属88种,藓类36科83属204种。该保护区共有湖北新记录科2科、新记录属9属、新记录种73种。该保护区苔藓植物区系成分多样,有11个区系类型,以温带成分为主(占30.89%)、东亚成分次之(占18.92%)。相比清凉峰、大巴山、十万大山和佛坪4个国家级自然保护区,木林子呈现出科多种少的特点,物种分化程度更高。木林子保护区与清凉峰的苔藓植物组成相似度最高,与佛坪相似度最低。该研究结果从苔藓植物多样性的角度佐证了清江流域物种分化程度较高的观点,为丰富木林子国家级自然保护区苔藓植物和湖北省苔藓植物提供了基础资料。     

New frontiers in bryology - physiology, molecular biology and functional genomics. * Wood AJ, Oliver MJ, Cove DJ, eds. 2004. Dordrecht: Kluwer Academic Publishers. {pound}63 (hardback). 203 pp.

This book is a collection of papersfrom the major researchers involved in physiological, molecularand genomic research on bryophytes, mainly, although not exclusively,using the moss Physcomitrella patens. This is a growing areaof research and the book aims to provide ‘... a synopsisof the outstanding basic research being conducted using mossesas a model multi-cellular eukaryote’. Bryophytes (mosses, liverworts and hornworts) are an importantand often neglected group     

藻苔纲Takakiopsida，一个独特的苔藓植物类群

藻苔属Takakia在建立之初被认为是原始的苔类植物。这一神秘类群的出现引起了苔藓学家的兴趣,发表了一系列相关的论文。但是随着其孢子体的发现,它的系统位置引起了争论。本文详细分析了藻苔属植物的形态性状特征,参考了大量其他学科的研究成果,认为它既不能归于类,也不能归于苔类。就其系统位置而言,应该成为一独立的纲——藻苔纲。     

Bryophytes and lichens in 16th-century herbaria

The diversity of bryophyte and lichen collections in 9 of the oldest preserved herbaria (dating from ca 1542 to 1577) was compared, including the first reports of bryophytes and lichens from the ‘En Tibi’ herbarium (possibly 1542–1544) and the herbarium of Leonhard Rauwolf (1560–1563). Bryophytes and lichens formed only a minority in each herbarium compared to the numbers of vascular plant specimens; numbers ranged from representatives of 21 genera in the herbarium of Ulisse Aldrovandi to the single genus Conocephalum in the Rauwolf herbarium. The focus was on large, handsome species of bryophytes and macrolichens, apart from small amounts of additional species collected as ‘by-catch’ in mixed collections. All herbaria together included 34 genera of bryophytes (36 species and 10 specimens identified to genus level) and 13 genera of lichens (24 species and 4 specimens identified to genus level). The diversity of mosses was higher than that of liverworts, and pleurocarpous mosses were more diverse than acrocarpous mosses. The collectors probably aimed at selecting material that was either characteristic of the vegetation in the respective areas of collecting or used for certain purposes (or both). The former hypothesis is supported by the small overlap in taxonomic diversity between the herbaria, and the latter by the fact that several moss, liverwort, and lichen genera are included whose traditional uses are well documented.     

海南岛苔藓植物研究历史、现状与展望

综述了海南岛苔藓植物的研究历史和现状。目前海南岛已记录的苔藓植物共有87科227属806种,其中苔类33科71属366种,藓类51科152属436种,角苔类3科4属4种;苔藓植物的区系组成以热带亚洲成分为主,与香港、台湾地区的种属相似性高;对海南岛苔藓植物的研究集中在尖峰岭、霸王岭、吊罗山3个国家级自然保护区;叶附生苔是海南热带雨林主要的苔藓生态分布类型之一,共有7科23属123种;初步统计濒危苔藓植物有15种。今后应继续开展广泛和持续的物种多样性调查,从生态学、植物化学、分子生物学等领域进行研究,促进合理的开发利用和推动保护工作。     

江西九岭山国家自然保护区苔藓植物区系研究北大核心CSCD

九岭山国家级自然保护区南连罗霄山脉,东、北、西三面与武夷山脉、大别山脉、武陵山脉隔水相望。笔者于2020年9至12月间,对九岭山国家级自然保护区苔藓植物进行了野外调查及标本采集,共采集标本562号,对保护区苔藓植物标本进行鉴定及统计,分析研究区苔藓植物区系地理特征,并与江西7个地区苔藓植物的相似性和热带性质/温带性质(R/T)值进行了比较。结果表明:(1)九岭山国家级自然保护区共有苔藓植物58科100属179种(变种、亚种和变型),其中藓类植物34科64属113种,苔类植物23科34属64种,角苔类植物1科2属2种。(2)九岭山苔藓植物区系成分复杂,区系成分以东亚分布最高;温带成分略高于热带成分,该区表现出明显的过渡性。(3)九岭山苔藓植物与大部分地区科、属的相似性都较高;九岭山与阳际峰种的相似性最高,而与鄱阳湖湿地种的相似性最低。(4)九连山自然保护区苔藓植物R/T值最高为1.32,鄱阳湖湿地R/T值最低为0.50;九岭山国家级自然保护区与铜钹山自然保护区的R/T值最接近,且都是温带性质略高于热带性质,具有明显过渡性。总体来看,江西从南到北热带成分逐步减少,温带成分不断增加,中部呈现出明显的过渡性。     

浙江乌岩岭国家级自然保护区叶附生苔类及附主植物多样性

叶附生苔类植物是一类主要生长在热带雨林和亚热带常绿阔叶林维管植物叶片表面的苔类植物, 具有重要的生态价值, 是苔藓植物中最需要关注和保护的一个类群。但由于其个体细小、分类困难等原因, 此前针对我国叶附生苔类植物的采样可能存在低估其多样性的情况。为了解采样方式可能对叶附生苔类植物多样性的影响, 本研究在乌岩岭国家级自然保护区对叶附生苔开展了系统的采样及比较研究。根据叶附生苔附主植物的叶片特性、分布位置等因素, 对保护区内的叶附生苔类植物及附主植物开展沿海拔梯度的系统调查和取样, 分析了叶附生苔类植物和附主植物的多样性及物种组成情况。结果显示, 该保护区共有叶附生苔类植物5科14属49种, 叶附生苔附主植物57科84属119种。与历史数据相比, 本研究区新增叶附生苔2科5属35种, 其中浙江省新记录苔类4种。叶附生苔物种丰富度表现出随海拔升高呈单峰型分布的模式, 在500-900 m海拔段的种数最多。基于叶片数的物种累积曲线及随机抽样分析表明, 该保护区叶附生苔在不同生境及同一附主植物不同叶片间表现出较大的种类组成差异。鉴于本研究采集方法获得的较高叶附生苔物种多样性, 建议在我国叶附生苔多样性其他分布中心开展类似的研究, 以进一步摸清我国叶附生苔类植物物种多样性。     

粤东亚热带森林群落树种组成对苔藓植物分布的影响

为探究森林群落树种组成对苔藓植物分布的影响,利用多元统计方法研究粤东亚热带地区苔藓植物的组成和分布对林分类型的响应。根据森林乔木层的树种组成划分为翻白叶树(Pterospermum heterophyllum)、木荷(Schima superba)+米锥(Castanopsis carlesii)和米锥3种森林类型。结果表明,3种森林类型中苔类(liverworts)和藓类(mosses)植物群落组成特征总体上存在显著差异;双齿裂萼苔(Chiloscyphus latifolius)和细指苔(Kurzia gonyotricha)在3种类型林分中的重要值变化指示了苔类植物群落的差异。3种类型林分中,均以东亚拟鳞叶藓(Pseudotaxiphyllum pohliaecarpum)为优势种。不同林分中藓类植物种类组成主要表现为亚优种分布的不同。这表明森林群落树种组成作为重要的生物因子,对林内苔藓植物的分布和种类组成有重要影响。     

Responses of bryophytes to wood-ash recycling are related to their phylogeny and pH ecology

Ash generated by the combustion of solid biofuels is increasingly being returned to the fuel's place of origin (mostly forests). In this way, nutrient depletion and acidification caused by biofuel harvest is counteracted and a waste problem is solved. Concerns about the potential negative effects of ash spreading on forest biodiversity (in particular mosses) have been raised, but little is known. I studied the effects of the application of two types of ash (the most used self-hardened crushed ash including fine particles and a less reactive type, pellets without fine particles) on 28 moss species and 17 liverwort species. In two field experiments, one on transplants of ground-living species and one on wood-inhabiting species in situ, I measured the response during the first two months after ash application. Visible damage (discoloration from green to brown) was assessed for all species and the growth response was measured for 24 ground-living species. The responses to crushed ash were clearly related to the species’ pH ecology and phylogenetic position. The growth of bryophytes associated with acidic conditions (pooled data from 10 species) or considered as being indifferent to pH (4 species) was negatively affected, whereas there was no effect on the growth of bryophytes of non-acidic habitats (10 species). The connection to phylogeny was even clearer. Most taxa responded negatively, but transplants from the moss order Bryales (4 species) and the family Brachytheciaceae (2 species; order Hypnales) grew better when treated with ash. The genera with the clearest negative responses were Sphagnum mosses (5 species), Tetraphis mosses (1 species), Dicranum mosses (6 species), and Barbilophozia liverworts (2 species). The four red-listed wood-inhabiting liverworts studied were not significantly damaged. Concerning ash type, pellets caused smaller effects than crushed ash, both on the positive and negative side. The results show that responses to ash recycling of the bryophyte species included in this study are predictable from their phylogenetic position and/or pH ecology. Further studies are needed to determine the generality of these results and to sort out if phylogeny or current relationship to pH is the primary determinant of the response.     

New national and regional bryophyte records, 37

Abstract

We analyzed the form of the UV-absorption spectra and calculated the bulk UV-absorption capacity of the methanolic extracts (BUVACME) in 15 bryophytes (five liverworts and 10 mosses) from unshaded aquatic habitats of Tierra del Fuego (Argentina). BUVACME was obtained as the area under the absorbance curve (AUC) in several ranges of the UV band to allow comparison with the literature data. Both the spectra form and the AUC values depended on the species considered. The spectra showed either no, one or two defined peaks. The peaks were probably due to phenolic derivatives, which could act as both screening compounds and antioxidants. The different AUCs calculated were highly and significantly correlated, and thus it may be unimportant which of these is used. The AUC values of most liverworts were higher than those of most mosses and in particular, the liverworts Noteroclada confluens and Triandrophyllum subtrifidum showed much higher BUVACMEs than those analyzed in any other bryophyte. Thus, the accumulation of UV-absorbing compounds might often increase protection against UV radiation in liverworts, but rarely in mosses. This is in line with the evolutionary differences between these two groups of bryophytes. Except for the two abovementioned liverwort species, BUVACME of aquatic bryophytes from Tierra del Fuego is not particularly different to that found in bryophytes from other zones of the planet.     

Regulation of gametangial formation in bryophytes

Under in vitro conditions gametangial formation in bryophytes can be regulated by a variety of physical and chemical factors. Liverworts are relatively more sensitive to photoperiod than are mosses. With the exception ofRiccia crystallina all species of liverworts thus far investigated are either long-day or short-day plants. Among mosses, all butSphagnum plumulosum appear to be independent of photoperiod for the onset of the reproductive phase. The photoperiodic response in liverworts increases with increasing light intensity. Mosses, on the other hand, exhibit differential behavior.Leptobryum pyriforme andBartramidula bartramioides exhibit a linear relationship with light intensity for this response, whereasBryum argenteum, B. coronatum andBarbula gregaria have a specific light intensity requirement for optimal response. The photoperiodic effect in bryophytes is operative within certain temperature limits. Most bryophytes do not require a low temperature pretreatment for gametangial induction. Some become fertile in a broad temperature range, whereas others require a specific temperature. Among chemical factors, carbohydrates in general enhance gametangial formation.Riccia crystallina andBartramidula bartramioides develop gametangia in the presence of a carbohydrate, butBryum spp. (B. argenteum andB. coronatum) andBarbula gregaria respond even in its absence. High carbohydrate-nitrogen ratio seems more favorable for the onset of reproductive phase. Bryophytes respond differentially to various forms of nitrogen. Depletion of inorganic nitrogen (nitrate or ammonium) significantly favors gametangial induction. On the other hand, organic nitrogen (such as amino acids, peptone and urea) has differential effects on the enhancement of antheridial and archegonial formation in liverworts. Growth hormones have variable effects on gametangial induction. Indole-3-acetic acid increases archegonial formation inRiccia crystallina, but it is more favorable for antheridial production in mosses likeBryum coronatum, B. argenteum andBarbula gregaria. Gibberellins enhance antheridial formation in all the investigated bryophytes. Cytokinins stimulate induction of archegonia and inhibit antheridial formation inRiccia crystallina andBryum argenteum. Auxins, gibberellins and cytokinins also interact in eliciting the response. Iron and copper chelating agents such as EDTA and EDDHA favor vegetative growth and gametangial formation. InRiccia these chelates enhance archegonial production more than antheridial formation, but inBryum argenteum their effect is just the reverse. Salicylic acid, known to chelate iron and copper in certain animal systems, inhibits gametangial formation in most bryophytes, except inBartramidula in which it enhances vegetative growth as well as gametangial formation. InBryum argenteum the effect of these chelates is accompanied with marked changes in the endogenous levels of iron and copper. Iron appears to favor the onset of reproductive phase, whereas copper is inhibitory. Cyclic AMP, a well known mediator of hormone action in animal systems, enhances gametangial formation inBryum argenteum. The response is specific and is mimicked by phosphodiesterase inhibitors. Cyclic AMP also increases antheridial production inBryum coronatum andBarbula gregaria. InBryum argenteum it overcomes the inhibitory effect of ammonium ions and high concentrations of sucrose on gametangial formation. In addition to the above factors, pH and nutritional status of the medium also affect the onset of reproductive phase. Bryophytes exhibit maximum response in a definite pH range. Moreover, a specific change in pH of the medium is observed during gametangial initiation. Nutritional status, as affected by the concentration of nutrients in the medium, has varied effects on gametangial formation. In most instances dilution of the medium is more favorable for the response. Certain other factors, such as yeast extract and animal sex hormones, also enhance the formation of antheridia and archegonia. The onset of the reproductive phase involves metabolic changes in the differentiating tissues. Archegonial initiation is accomplished by intense metabolic activities, and in certain liverworts there is an increase in the content of carbohydrates, auxins, RNA and proteins, whereas the level of total nitrogen drops. Besides this a number of enzymes and phenolic compounds also exhibit marked qualitative and quantitative changes. Once gametangia are induced under in vitro conditions, fertilization can be accomplished by flooding the cultures bearing mature gametangia with sterile, distilled water. Development of sporophytes is markedly affected by temperature and nutritional status of the medium.     

Latitudinal diversity gradients in bryophytes and woody plants: Roles of temperature and water availability

It remains unclear whether the latitudinal diversity gradients of micro- and macro-organisms are driven by the same macro-environmental variables. We used the newly completed species catalog and distribution information of bryophytes in China to explore their spatial species richness patterns, and to investigate the underlying roles of energy availability, climatic seasonality, and environmental heterogeneity in shaping these patterns. We then compared these patterns to those found for woody plants. We found that, unlike woody plants, mosses and liverworts showed only weakly negative latitudinal trends in species richness. The spatial patterns of liverwort richness and moss richness were overwhelmingly explained by contemporary environmental variables, although explained variation was lower than that for woody plants. Similar to woody plants, energy and climatic seasonality hypotheses dominate as explanatory variables but show high redundancy in shaping the distribution of bryophytes. Water variables, that is, the annual availability, intra-annual variability and spatial heterogeneity in precipitation, played a predominant role in explaining spatial variation of species richness of bryophytes, especially for liverworts, whereas woody plant richness was affected most by temperature variables. We suggest that further research on spatial patterns of bryophytes should incorporate the knowledge on their ecophysiology and evolution.     

Impact of management intensity on non-vascular epiphyte diversity in cacao plantations in western Ecuador

A first study on the biodiversity of non-vascular epiphytes in cacao (Theobroma cacao L.) plantations in western Ecuador yielded 112 species (51 bryophytes, 61 lichens). Epiphyte assemblages of cacao plantations resembled those of tropical rain forests but species richness was usually lower and individual species were found at lower heights on the trunks. The vast majority of the species are widespread neotropical or pantropical species; one species, Spruceanthus theobromae (Spruce) Gradst., is endemic to cacao plantations of western Ecuador. Differences in management intensity, by manual removal of epiphytes from tree trunks (limpia), had a significant impact on epiphyte species diversity. Total species richness was significantly reduced in plantations with high management intensity, due mainly to the decreased diversity of lichens and liverworts; moss diversity was not affected by management regime. Total percentage cover of bryophytes was highest in plantations with low management intensity, while lichen cover was greatest in plantations with high management intensity. Crustose lichens and smooth mats growing closely appressed to the substrate were little affected by the limpia and their growth may have been promoted when larger-sized species were removed, by reducing competition. Cacao plantations with low and moderate management intensity serve as an important substitute habitat for ecological specialists (sun epiphytes, shade epiphytes) of the rain forest and are of considerable significance for their conservation.     

中国首批濒危苔藓植物红色名录简报

初步报道了2004年上海中国苔藓植物多样性保护国际研讨会上通过的中国首批濒危苔藓植物红色名录。名录共计82种,其中藓类植物28科、47属、50种,苔类植物12科、26属、31种和角苔类植物1科、1属、1种。根据修订的IUCN/IAB标准, 82种苔藓植物中,36种划为极危（CR）,29种划为濒危（EN）,17种划为易危（VU）。对中国首批濒危苔藓植物的地理分布特点、濒危原因及今后的保护行动也进行了初步讨论。     

广西藓类植物新记录的报道

通过对广西西南部邻近中越边境山地的多次野外采集获得1 952份藓类标本,经鉴定和查阅以往广西的相关文献资料,报道了广西藓类植物新记录47种,隶属25科36属。文中列出了新记录种及其标本信息,结合文献对每个种的分布进行了更新。该研究结果不仅丰富了广西苔藓植物的物种多样性,同时也为广西乃至中国苔藓植物的区系研究和资源开发提供了新的数据资料。