濒危乔木红豆杉不同更新阶段的生境特征比较

以福建梅花山自然保护区濒危乔木红豆杉(Taxus chinensis(Pilger)Rehd.)为对象,对红豆杉的种子排放、幼苗更新、幼树更新3个更新阶段的生境特征进行研究,并比较生态位的变化,以此评价红豆杉不同更新阶段的生境需求。结果显示:随着个体发育生长,红豆杉更新生境发生了明显转变,种子排放地与幼苗生境空间一致性较高,而它们与幼树生境存在明显的空间不一致性。从生态位角度来看,种子排放地和幼苗生境重叠指数≤0.5的仅有海拔和坡度2个因子,这说明幼苗的空间格局受到鸟类传播的强烈影响,鸟类传播所排放的种子能萌发并生长成幼苗。幼苗和幼树生境重叠指数≤0.5的因子有海拔、坡向、植被类型,说明在大尺度景观因子和庇护植被层面上,植物的更新需求出现了明显的不一致。研究结果表明红豆杉的更新生境存在明显的阶段变化,可能造成植物更新出现建成限制,使幼树阶段成为更新的瓶颈阶段。     

One step more towards taxane production through enhanced Taxus propagation

We have developed a high-yielding procedure for the in vitro propagation of juvenile material of Taxus baccata involving a combination of seed handling and culture on WP culture medium supplemented with sucrose (2%), activated charcoal (0.5%) and BAP (22.19 mM) for 30 days, followed by 40 days on hormone-free medium. Shoot apical ends should be decapitated to obtain propagation rates up to 12- to 18-fold per subculture period (70 days). In this way the high genetic variability of the juvenile material can be used in the most productive way. In addition to producing large numbers of yew plants (difficult to get by traditional methods), this procedure allows the fast screening of individuals for their taxane content. A negative correlation between growth and secondary metabolite content was found for paclitaxel. The positive correlation with 10-deacetyl baccatin III accumulation reflects once more the commercial viability of using 10-deacetyl baccatin III extraction as an alternative to taxane production, but this time opening up the possibility of selecting genotypes with both characteristics: fast growth and high productivity. Received: 12 July 1999 / Revision received: 22 November 1999 / Accepted: 22 November 1999     

Chemical Studies on Taxus canadensis

A series of new taxanes, 1 – 93 , have been isolated, together with 37 known taxoids including Taxol^® (paclitaxel) and cephalomannine, from the Canadian yew, Taxus canadensis (Taxaceae) in the past 30 years. These new taxoids possess various skeletons containing 5/7/6, 6/10/6, 6/5/5/6, 6/8/6, and 6/12 ring systems and six new taxanes with four novel skeletons, i.e., a taxane with a 6/6/8/6 ring system, a taxane with a [3.3.3] propellane skeleton, three taxanes with [3.3.3] [3.4.5] dipropellane sytems, as well as a novel taxane with a unique 5/5/4/6/6/6 hexacyclic skeleton, containing a unique [3.3.2] propellane, were isolated for the first time from natural sources. It should be emphasized that 13‐acetyl‐9‐dihydrobaccatin III, a very useful starting material for the semisynthesis of Taxol^® and Taxotere^®, represents the most abundant taxane in the needles of this yew tree. These findings establish the above mentioned yew tree as significantly different from the remaining species. On the other hand, some chemical modifications on the taxanes isolated from this plant were carried out.     

Effects of <i>Piriformospora indica</i> on the Respiration of <i>Taxus chinensis</i> var. <i>mairei</i> under Water Stress

Seedlings of Taxus chinensis var. mairei were used as experimental materials to study the adaptation of Piriformospora indica to this plant under water stress. The materials were divided into two groups, namely, with or without inoculation with P. indica. Each group was subjected to four different levels of water stress. Vitality and physiological and biochemical indexes of the roots of T. chinensis var. mairei were regularly measured. Under water stress, T. chinensis var. mairei had significantly decreased root vitality; root vitality was higher in inoculated roots than in uninoculated roots. Under intense water stress, the inoculated roots had a higher soluble sugar content than the uninoculated roots. Under water stress, T. chinensis var. mairei experienced decreased activity of aerobic respiratory metabolic enzymes. The activity of anaerobic respiratory metabolic enzymes and alcohol dehydrogenase initially increased and then decreased, whereas that of lactate dehydrogenase increased. The inoculated roots had a higher activity of respiratory metabolic enzymes than the uninoculated roots. As water stress was further intensified, the roots had significantly decreased activity of aerobic respiratory metabolic enzymes and significantly increased activity of anaerobic respiratory metabolic enzymes. The activity of respiratory metabolic enzymes decreased faster in the uninoculated roots than in the inoculated roots. This study demonstrated that Piriformospora indica plays a positive role in enhancing the antihypoxic ability of T. chinensis var. mairei, thereby alleviating plant damage due to water stress.     

东北红豆杉—无花果复合种植对两种植物生长和土壤酶活性影响

设计了室内控制条件下的东北红豆杉和无花果的复合种植实验，并与单一种植东北红豆杉和单一种植无花果的模式进行了比较。分别考察了上述3种模式下，东北红豆杉和无花果的生长指标、光合作用以及土壤酶活性差异。结果表明：①在生长量方面，复合种植3个月的东北红豆杉的株高增长率为152.6%，是单一种植的东北红豆杉株高增长率的1.56倍；复合种植3个月的无花果，其当年生枝的生长量为68.4 cm³，比单一种植的无花果高36.3%。②在光合作用指标方面，在800 μmol·m^-2·s^-1光照强度下，复合种植3个月的东北红豆杉和无花果净光合速率与相应的单一种植相比，分别提高了19.0%和5.3%。③在土壤酶活性方面，在7月份，复合种植模式下的土壤蔗糖酶、脲酶和酸性磷酸酶活性比单一种植东北红豆杉土壤相应酶活性分别提高51.6%、58.5%和50.8%，比单一种植物无花果土壤相应酶活性分别提高85.5%、47.5%和71.9%；土壤多酚氧化酶活性在不同种植模式之间无显著差异（P>0.01）。综上，东北红豆杉-无花果复合种植可以提高土壤蔗糖酶、脲酶和酸性磷酸酶活性，对两种植物生长均具有促进作用。上述结果可为在生产实践上进行东北红豆杉-无花果复合经营提供参考。     

Deciphering the Antimicrobial Potential of Taxus wallichiana Zucc: Identification and Characterization Using Bioassay-Guided Fractionation

Taxus wallichiana Zucc. is a high valued medicinal plant and has been mainly studied for its anti-cancer properties. However, research on its other important biological activities, such as its antimicrobial potential, still needs attention. The focus of the present study is to investigate the antimicrobial activity of secondary metabolites of T. wallichiana needles against 3 different groups of microorganisms, i. e., bacteria, actinobacteria, and fungi. Bioactive compounds from T. wallichiana needles were separated through column chromatography, and, TLC-bioautography. Mobile phases were optimized using Snyder's selectivity triangle. Antimicrobial spots were fractionated and compounds were identified by gas chromatography-mass spectroscopy (GC/MS) and liquid chromatography-mass spectrometry (LC/MS). Functional groups were characterized using Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (NMR) was used to identify the molecular structures. GC/MS and LC/MS data analysis confirm the presence of fatty acids (arachidic acid, behenic acid, palmitic acid, and stearic acid), vitamins (nicotinamide), and alkaloids (cinchonine, timolol), aminobenzamides (procainamide), carbocyclic sugar (myoinositol), and alkane hydrocarbon (hexadecane), having antimicrobial activity in the needles of T. wallichiana. To the best of our knowledge, this is the first report on the isolation and characterization of antimicrobial compounds from the needles of Taxus wallichiana (Himalayan yew). The data obtained from the present study will be supportive to the new drug discoveries in modern medicine with various combinations of medicinal plant's active constituents that can be used for curing many diseases.     

Inhibitory effect of 13 taxane diterpenoids from Chinese yew (Taxus chinensis var. mairei) on the proliferation of HeLa cervical cancer cells

The inhibitory effect of 13 taxanes isolated from the Chinese yew (Taxus chinensis var. mairei) on the proliferation of human cervical cancer HeLa cells were examined using an MTT assay. Four compounds having a hydrophobic cinnamate side chain showed antiproliferative activity, which may be due to increased cell permeability.     

Branch wood from the lake shore settlements of Horgen Scheller, Switzerland: Evidence for economic specialization in the late Neolithic period

596 waterlogged, uncarbonized branch wood specimens from four cultural layers of the late Neolithic lake shore site of Horgen Scheller (between 3080 and 3030 B.C.) on Lake Zilrich, Switzerland, were examined. The following parameters were analysed: taxonomy, diameter and age of the twigs, cutting season, and distribution of the branches over the area as well as their distribution in the different cultural layers. The twigs were divided into the following three groups, based on differences observed in these analyses: conifers, deciduous trees with catkins, and deciduous trees without catkins. Branch diameter examinations revealed that branches of deciduous trees were thicker on average than those of conifers. While branches from deciduous trees without catkins were gathered at the age of seven years on average, those of conifers and deciduous trees with catkins were older. Waney edge analyses showed that the majority of the twigs were cut within the winter months. Among the deciduous trees without catkins there is, however, a markedly higher proportion of branches cut in summer than in the other two groups. The taxonomic examinations demonstrated that 70% of the specimens consisted of twigs of eitherCorylus avellana L. (hazel),Taxus baccata L. (yew), orAbies alba Mill. (silver fir), thus implying the great economic importance of these species in the settlements of Horgen Scheller. To our knowledge this is the first report that a remarkably high proportion of yew twigs (26.8%) has been found in an analysis of subfossil twigs. The possibility is discussed that the inhabitants had specialized in obtaining yew from the region. Concentrations of wood finds, possible remains of buildings, became evident from the analyses of the distribution of the branch wood over the excavated area. A very similar spatial distribution pattern of the taxa was found through the different cultural layers. Therefore it seems likely that existing structures were reused when a new settlement was built. The data also show that the building outlines slowly moved towards land over time. A rising lake water level could have led to gradual dislocation of the settlements.