沙生短命植物角茴香群落特征及生物学特性

采用抽样调查的方法对古尔班通古特沙漠南缘的8个角茴香自然群落的群落特征和生物生态学特性进行调查,对其群落特征和花部特征进行初步探究,为进一步对其传粉适应性以及繁育系统特征的研究奠定基础。结果表明:(1)角茴香群落中包含30种植物,隶属于15科28属,单种科、单种属较多。(2)根据群落组成和重要值可将8个角茴香自然群落划分为3个群丛,分别是角茴香+草地早熟禾+白茎绢蒿群丛、角茴香+艾比湖沙拐枣+白茎绢蒿群丛和角茴香+白茎绢蒿+蛇麻黄群丛。(3)角茴香种群、单株、花序和单花的花期分别历时37~40d、14~16d、13~15d和1~2d,单株结籽量700~900粒,种子千粒重(0.291 0±0.002 7)g,单花具有特殊的中裂片结构,具有雄蕊拟态和花粉二次呈现的功能。     

Do pollinators determine hybridization patterns in sympatricSatyrium (Orchidaceae) species?

The breakdown of species integrity was studied in three sympatricSatyrium (Orchidaceae) species at a site in the Western Cape province of South Africa. Hybrids with intermediate morphology were identified using multivariate analysis.Satyrium erectum ×S. bicorne andS. erectum ×S. coriifolium hybrids were common, while only oneS. bicorne ×S. coriifolium hybrid was found (a new record). Reciprocal artificial crossing experiments confirmed that genetic compatibility exists between all three species. However, the species have different pollinators: moths inS. bicorne, bees inS. erectum and sunbirds inS. coriifolium. Pollinators, rather than genetic factors, therefore, appear to be responsible for reproductive isolation between these species. Breakdown in pollinator specificity results in interspecific pollen transfer and the formation of hybrids. Overlap in floral signals, including nocturnal scent in bothS. erectum andS. bicorne, and bright coloration in bothS. erectum andS. coriifolium, facilitates the formation of hybrids between these species pairs. The brown, scented flowers ofS. bicorne, on the other hand, share no obvious floral signals with the bright orange, unscented flowers ofS. coriifolium, accounting for the rarity of hybrids between this species pair. Differences in floral morphology also result in mechanical isolation between these two species. Since the three species are sympatric in a very small part of their geographic ranges, it is unlikely that avoidance of hybridization has been an important selective factor in the evolution of specialized pollination systems.     

Factors affecting the initiation of mini-rhizomes from Trillium erectum and T. grandiflorum tissues in vitro

Leaf and stem explants of Trillium grandiflorum and T. erectum produced mini-rhizomes (MRs) in vitro which gave rise to shoots and roots. The apical portion of the stem and the basal portion of the leaves were the most effective explants from these tissues, while stem tissue was more responsive than leaf tissue. The best response with both species was observed on half-strength MS basal medium supplemented with cytokinin and auxin. T. erectum was more responsive than T. grandiflorum overall, and in some cases produced MRs in the absence of growth regulators. Culture at 21°C appeared to stimulate growth from T. grandiflorum tissues, compared with controls at 27°C, whereas the outgrowth of shoots from MRs was inhibited in both species at 21°C. In vitro production of MRs could provide a more rapid, alternative propagation method for these species than traditional methods.     

The allopolyploid origin ofSedum rupestre subsp.rupestre (Crassulaceae)

InSedum rupestre L. a polyploid series (x = 16) occurs in which aneuploid chromosome numbers and odd levels of ploidy prevail. The most common and widely distributed cytotype,S. rupestre subsp.rupestre, is 2n = 112. Plants resemblingS. rupestre subsp.rupestre can be obtained by hybridizing the tetraploid cytotypes ofS. forsterianum Sm. (2n = 48) andS. rupestre subsp.erectum 't Hart (2n = 64). Comparison of these artificial hybrids with their parents and a large number of plants ofS. rupestre subsp.rupestre (2n = 112) from nature showed thatS. rupestre subsp.rupestre and the artificial hybrids are morphologically indistinguishable, and intermediate betweenS. forsterianum andS. rupestre subsp.erectum. MorphologicallyS. rupestre subsp.rupestre is closer to subsp.erectum than toS. forsterianum. Chloroplast DNA restriction patterns ofS. rupestre subsp.rupestre, however, resembleS. forsterianum more closely. The combined results of the hybridization experiments, the analysis of the cpDNA restriction patterns, and the morphological variation indicate the allopolyploid origin ofS. rupestre subsp.rupestre. Natural hybrids inSedum (Crassulaceae) 4.     

Pollen morphology in Asiatic species ofTrillium

Pollen grains of five species and two interspecific hybrids ofTrillium from eastern Asia have been examined with scanning electron and transmission electron microscopy. All species from eastern Asia, excludingT. govanianum, are characterized by inaperturate pollen and an unstratified and granulated exine structure. Pollen of the Himalayan species,T. govanianum, is, however, monocolpate and intectate. The palynological evidence suggests that the Asiatic species, excludingT. govanianum, are closely related to each other and toT. erectum in North America, andT. govanianum is independent of the other species in the genus.     

耐碳青霉烯类肺炎克雷伯菌对C57BL/6小鼠肺部菌群的扰动

【背景】肺部菌群与宿主健康和呼吸道疾病密切相关,耐碳青霉烯类肺炎克雷伯菌(carbapenem-resistantKlebsiella pneumonia,CRKP)是临床常见的条件致病菌,感染后对肺部菌群的影响尚不清楚。【目的】探究耐碳青霉烯类肺炎克雷伯杆菌CRKP2对C57BL/6小鼠肺部菌群的扰动。【方法】将C57BL/6小鼠随机分为3组,分别用CRKP2、碳青霉烯类敏感肺炎克雷伯菌KP2044和无菌PBS溶液滴鼻,利用16S rRNA基因的高通量测序技术分析肺部菌群结构。【结果】与健康小鼠相比,菌株KP2044和CRKP2感染后小鼠肺部菌群α多样性和β多样性均显著改变,变形菌门相对丰度显著增加,乳酸杆菌属相对丰度明显下降。与KP2044相比,CRKP2生物膜形成能力较弱,感染后小鼠死亡率较低,对肺部菌群的扰动较小。【结论】虽然肺炎克雷伯菌是条件致病菌,但高剂量耐碳青霉烯类肺炎克雷伯菌CRKP2仍对健康小鼠肺部菌群造成显著影响;尽管菌株CRKP2具有多重耐药性,但与菌株KP2044相比对肺部菌群的扰动较小,因此推测KP菌株感染对肺部菌群的扰动程度可能与菌株毒力有关。     

A karyomorphological study of the genusHypericum (Hypericaceae) in Japan

Chromosome numbers were determined in 226 collections ofHypericum of Japan, representing nine species and one interspecific hybrid. These included the first cytological records forH. erectum var.caespitosum, H. samaniense, H. hakonense, H. sikokumontanum, H. kamtschaticum var.kamtschaticum, H. kamtschaticum var.hondoense, H. pseudopetiolatum, H. yojiroanum andH. tosaense. Counts of 2n=16 were made throughout for collections of six species, and those of 2n=18 forH. ascyron. Intraspecific polyploidy was found inH. samaniense (2x and 3x, x=8) andH. pseudopetiolatum (2x and 4x, x=8). Results of the karyotype analysis showed that three different karyotypes could be recognized, and they were parallel to the subdivision ofHypericum by Kimura (1951). The chromosomes were very small and mostly median centromeric. It was suggested that the role of polyploidy in the evolutionary differentiation ofHypericum in Japan might have been rather limited.     

Puccinia kraussiana (Uredinales) onHeterosmilax gaudichaudiana,A new record of rust in Eastern Asia

Puccinia kraussiana, a rust fungus of Africa, was found in Taiwan for the first time in eastern Asia. It was parasiting on leaves ofHeterosmilax gaudichaudiana, on which all four stages were characteristically found. The host species,H. gaudichaudiana, newly added to the host range ofP. kraussiana, constitutes also a new entry to the phanerogamic flora of Taiwan.     

西方蜜蜂工蜂肠道菌群定殖起始点和定殖稳态点的结构比较分析

【目的】目前,针对昆虫肠道细菌定殖规律的研究还未见报道。探索西方蜜蜂(Apis mellifera)肠道菌群定殖过程两个重要时间节点(起始0日龄和稳态7日龄)间肠道细菌群落(菌群)结构组成的差异,加深对蜜蜂及昆虫肠道菌群定殖规律的认识。【方法】分别采集两个化蛹后工蜂发育阶段的个体各5只,分别解剖并提取其肠道菌群DNA。使用Illumina技术对肠道菌群16S rD NA高变区进行高通量测序。通过生物信息学的分析方法对肠道菌群进行多样性分析,并对两个时间点相对丰度最高的肠道菌群进行统计分析,比较肠道菌群相对丰度和组成的差异。【结果】共获得515156条高质量序列,长度为227904953bp,平均长度为442bp。基于OTUs的分类表明,工蜂肠道细菌分别隶属于34个门82个纲221个目405个科799个属。此外,工蜂肠道菌群定殖起点和终点间的Alpha多样性指数存在显著差异(ACE,P=0.0014;Chao,P=0.0013;Shannon,P=0.0003;Simpson,P=0.0028,Student’s t检验)。此外,相较0日龄工蜂,7日龄工蜂肠道中的乳酸杆菌Lactobacillus、Gilliamella、双歧杆菌Bifidobacterium、Snodgrassella4个属的相对丰度显著增加;相反,不动杆菌Acinetobacter、大肠杆菌志贺氏菌Escherichia-Shigella、鞘脂单胞菌Sphingomonas、类杆菌Bacteroides、涅斯捷连科氏菌Nesterenkonia、栖热菌Thermus6个属的细菌相对丰度显著降低(P0.05)。【结论】出房(0日龄)成年工蜂的肠道菌群多样性显著高于菌群定殖完成(7日龄)工蜂的肠道菌群多样性,且成年工蜂肠道菌群定殖完成前后部分类群的相对丰度显著改变。本研究的结果不仅可增加我们对蜜蜂肠道菌群定殖规律的认识,也能够为研究其他昆虫肠道菌群的定殖规律提供重要的参考信息。     

Biological control of an exotic scale, Orthezia insignis Browne (Homoptera: Ortheziidae), saves the endemic gumwood tree, Commidendrum robustum (Roxb.) DC. (Asteraceae) on the island of St. Helena

St. Helena is a small South Atlantic island with a highly degraded, but internationally significant, terrestrial flora. The 2500 remaining gumwoods, Commidendrum robustum, are an important part of this remnant flora. In 1991, a South American scale insect, Orthezia insignis, was identified attacking the gumwood trees. By 1993, severe infestations had killed over 100 trees. If the number of dead trees had continued to increase exponentially, all 2500 trees would have died by 1995. This outcome was likely given abundant alternative host plants, and lack of natural enemies of O. insignis. Host range tests showed that the other members of the endemic genus Commidendrum were also at risk. The coccinellid predator, Hyperaspis pantherina, was released on St. Helena in 1993. H. pantherina numbers increased from 1994, coinciding with a 30× decrease in scale numbers. Scale outbreaks have not been reported on St Helena since 1995, and culturing of H. pantherina was discontinued because insufficient O. insignis prey could be found in the field. Extensive blackening from sooty molds on the surviving trees in 1995 suggested that the predator was effective just in time to prevent death of most trees. H. pantherina appears to have saved the field population of a rare endemic plant from extinction.     

广东南雄丹霞梧桐自然保护区蕨类植物区系研究

该研究在野外调查、搜集文献和整理植物数据库的基础上,对广东南雄丹霞梧桐自然保护区蕨类植物区系组成和分布区类型进行统计分析,并比较与周边相邻3个研究区蕨类植物区系的相似性,为研究区植物资源的合理开发利用提供依据。结果表明:(1)广东南雄丹霞梧桐自然保护区共统计到蕨类植物28科51属84种,科属结构单一,分化水平不高,以寡种科属居多,但区系起源古老,进化关系连贯。(2)该区蕨类区系地理联系广泛,在科、属水平上与热带亲缘程度较高,以泛热带分布、亚热带分布为主,在种水平上以热带亚洲分布和东亚分布为主,区系地理成分呈热带向温带过渡渗透性质。(3)在与邻近区亲缘关系上,与观音岽联系最为紧密,其次是冠豸山,与丹霞山的关系较疏远。该研究区与观音岽的属、种相似性系数均在0.83以上,区系同质性明显,与两者现代自然条件相似的事实相吻合。该研究结果为探讨丹霞地貌地带蕨类植物的起源和发育提供了重要依据。     

The association between the phytoplankton, Rhopalosolen species (Chlorophyta; Chlorophyceae), and Anopheles gambiae sensu lato (Diptera: Culicidae) larval abundance in western Kenya

Algae are important food resources of the larvae of the African malaria vectors, Anopheles gambiae Giles and Anopheles arabiensis Patton (Anopheles gambiae sensu lato), and other zooplankton, but empirical evidence remains meager about the agal flora in ephemeral water bodies. The animals present in natural aquatic habitats in western Kenya were sampled from July to November 2002 to study abiotic and biotic environmental factors determining A. gambiae sl larval abundance. The five highest concentrations of third and fourth instars and pupae (hereafter referred to as old-stage larvae) were sampled in conjunction with the unicellular epizoic green algae, Rhopalosolen species (Chlorophyta; Chlorophyceae). Canonical correspondence analysis revealed that the presence of Rhopalosolen species was the most important determinant of the animal assemblage. The density of old-stage A. gambiae sl larvae was positively correlated with the presence of Rhopalosolen species, but the density of first and second instars of A. gambiae sl was not. The water bodies with Rhopalosolen sp. yielded larger mosquitoes in spite of the higher density of larvae. We demonstrated that the productivity of water bodies in terms of the larvae of malaria vectors can differ in magnitude depending on the agal flora. We discuss phytoplankton as a regulator of mosquito larval populations.     

Flavonoids in the leaves ofTrillium undulatum willdenow

Three flavonol glycosides were identified in the leaves ofTrillium undulatum. The main glycoside was kaempferol 3-O-α-rhamnosyl-(1→2)-O-[α-rhamnosyl-(1→6)]-β-glucoside; the glycosidic sugars and their linkage pattern were quite different from those of the leaf flavonoids ofT. tschonoskii, T. apetalon, T. Kamtschaticum, T. erectum andT. grandiflorum. Two minor compounds were kaempferol/quercetin 3-O-rutinoside. Part 2 in the series “Studies of the flavonoids of genusTrillium”. For Part 1, see Yoshitamaet al., (1992) Bot. Mag. Tokyo105: 555.     

饲料类型对茶尺蠖幼虫肠道细菌多样性及幼虫存活率的影响

【目的】茶尺蠖是茶园中的重要害虫。研究茶尺蠖寄主食物-肠道菌群-茶尺蠖生长发育三者之间的关系对于茶尺蠖的防治具有重要的理论指导价值。【方法】分析不添加茶叶因子的纯人工饲料和茶树鲜叶对茶尺蠖幼虫的存活影响;用高通量测序技术分析不同饲料饲喂的茶尺蠖幼虫的肠道菌群异同。【结果】取食人工饲料的幼虫死亡率远远高于取食茶树鲜叶的幼虫;取食人工饲料的幼虫肠道细菌多样性和丰富度高于取食茶树鲜叶的幼虫;茶尺蠖幼虫肠道中存在很多促进宿主生长的细菌。【结论】饲料类型影响茶尺蠖幼虫的存活;饲料类型影响茶尺蠖幼虫肠道菌群结构。     

Quantifying the potential for flow to remove the emergent aquatic macrophyte Sparganium erectum from the margins of low-energy rivers

The emergent macrophyte species Sparganium erectum occurs commonly at the margins of low- to medium- energy river systems across the northern temperate zone. It is considered as an invasive species along low-energy water courses in many parts of the US and Australia. The life-cycle and biomechanical properties of this species make it very well adapted to such environments, allowing rapid growth and sediment trapping, such that encroachment into the channel occurs as the growing season progresses. The widespread growth of species such as S. erectum is therefore of particular concern, when considering the flood risk potential of many rivers. As such, the conditions required for survival or uprooting and scouring of this plant are of interest, as are the times of the year and processes by which these plants spread to increase the size of current stands, and to form new stands. It is known that S. erectum reproduces by several vegetative methods including rhizome growth, dispersal of detached rhizomes, and relocation of entire plants. However, the mechanisms and flow conditions necessary for uprooting or scouring of entire plants, and the separation of fragments of this species, at different times of the year, are largely unknown. The aim of this paper is to model the uprooting resistance of S. erectum plants as reported by Liffen et al. (in press), and to investigate the manner by which this species is adapted to proliferate in low-energy, low-gradient streams. The results presented here show that Monte Carlo simulations using the RipRoot root-reinforcement model can be used to accurately model plant pullout forces, rhizome interconnectivity and length changes for S. erectum plants throughout the growing season. Analysis presented here also suggests that plant uprooting forces are several orders of magnitude larger than potential drag forces that could act on the S. erectum plants at the River Blackwater site modeled, and even at sites with much higher channel slopes. This result suggests that the ability of these plants to thrive in low-energy rivers, but not in higher-energy river environments, is less related to driving forces causing drag on the plants, and more related to the energy conditions controlling erosion and deposition of the fine substrate materials these plants thrive in. The critical shear stress of the fine within-vegetation material was shown here to only be exceeded by the average boundary shear stress within the vegetation, during winter months when above-ground biomass and thus Manning's n values were at their lowest. For example, during March and April average boundary shear stress was predicted to exceed critical boundary shear stress for 6% of the time. Erodibility measurements from jet-tests conducted at the River Blackwater fieldsite suggested that this excess in boundary shear stress could result in potential vertical scour of up to 0.09 m in both March and April. During the majority of the growing season sediment trapping rather than erosion dominated, with enough deposition occurring over the summer to protect all but the shallowest, weakest and least interconnected rhizomes and plants from being scoured in the winter months. The balance between erosion and deposition within stands of S. erectum in these low-energy environments therefore allows for the maintenance of established stands of vegetation, whilst still allowing for scouring of weaker S. erectum plants that can establish previously un-colonized channel margins further downstream.     

宁夏地衣一新记录属——金黄衣属及其新记录种

报道了宁夏地衣的1个新记录属——金黄衣属及其新记录种——戈壁微孢衣。利用形态学和分子生物学的手段对该种进行了分类学鉴定,并对该种的形态、化学及生态分布等方面进行了详细记述。调查发现该种对人类的干扰活动非常敏感。     

Evolution of the Australian flora through the Tertiary

The evolution of the Australian flora through the Tertiary has not been reviewed by a megafossil palaeobotanist for almost a century. Based on material available and published studies, the Australian Tertiary can be considered in three units: Eocene, Oligo-Miocene, and Pliocene. Key taxa in the Eocene includeCasuarinaceae, Proteaceae, Fagaceae, Podocarpaceae, andLauraceae. Many known Eocene deposits are interpreted as warm, humid rainforests.Oligo-Miocene floras reflect a climatic deterioration, with greater occurrence of sclerophylly and xerophylly. A reduction of tropical taxa is seen with an increase ofMyrtaceae and earliest records ofMimosaceae, Chenopodiaceae, andPoaceae. These trends continue into the Pliocene, which is not well represented in Australia.Problems needing to be addressed include the discrepancy between the pollen and megafossil records ofNothofagus, the origins of Australia's wet tropical taxa, and the role of fire in the early evolution of the Australian flora.     

Oral yeast flora and its ITS sequence diversity among a large cohort of medical students in Hainan,China

The most prevalent fungal infection of humans is candidiasis which is caused by species of Candida that are typical members of the commensal microbial flora of the oral mucosa and other body surfaces. Since species of Candida differ in virulence properties and susceptibilities to anti-fungal drugs, understanding the human commensal yeast flora will have a significant impact on designing treatment and prevention strategies against yeast infections. However, although there is a global interest in Candida species, the global distributions of Candida species remain largely unknown, especially among healthy hosts. Here we report the oral yeast flora from the surveys of over 1,000 medical students in China. Our results showed that this population had a yeast carriage rate (4.5%) much lower than other population samples reported previously from Mainland China (40–70%). In addition, C. albicans was isolated at a much higher frequency than those from other Chinese samples, with a frequency (80.9%) more similar to those in developed regions such as North America. The oral yeast carriage rates and yeast species compositions were similar between male and female students and between the hosts borne and raised on Hainan Island and those borne and raised on Mainland China. Furthermore, the sequence variation at the internal transcribed spacer (ITS) regions of the nuclear ribosomal RNA gene cluster was analyzed for strains of the dominant species, C. albicans. Our analysis identified 14 ITS types among the 41 Hainan isolates of C. albicans. However, only four of the 14 ITS types were identical to those in reference strains from Europe and North America. Taken together, our analyses suggest that the oral yeast flora among host populations in China is highly heterogeneous and that there is a high ITS sequence diversity in the Hainan population of C. albicans.     

越南马兜铃属植物分布新记录——凹脉马兜铃

凹脉马兜铃(Aristolochia impressinervis C.F.Liang)曾被认为是中国广西的特有种.该文首次报道了越南植物区系中凹脉马兜铃的分布新纪录,并讨论了凹脉马兜铃的分类及其与A.pierrei L.的区别特征.