Photosystem 2 activities of hyper-accumulator Dicranopteris dichotoma Bernh from a light rare earth elements mine

The distribution of rare earth elements (REEs) in the fern Dicranopteris dichotoma Bernh plants from a light rare earth elements mine (LRM) and a non-mining (NM) area in Longnan county of Jiangxi province, China were investigated by means of inductively coupled plasma-mass spectrometry, transmission electron microscopy, and energy-dispersive X-ray microanalysis. The photosynthetic characteristics of D. dichotoma were studied by chlorophyll (Chl) a fluorescence kinetics. Contents of REEs in the lamina and the root of D. dichotoma were higher than those in soils, and were mainly distributed in lamina. A part of them was found in the chloroplast. By comparing with D. dichotoma from NM area, the efficiency of photosystem 2 photochemistry and electron transport rate were significantly enhanced in lamina of the plant from LRM because most of REEs deposits were distributed along cell wall, in vacuole, and in chloroplast. High contents of REEs in lamina did not decrease the photosynthetic activities in LRM plants of D. dichotoma. Besides, D. dichotoma could change its β-carotene content to avoid the damaging effect of high REEs content.     

NICHE PARTITIONING AND THE COEXISTENCE OF TWO CRYPTIC DICTYOTA (DICTYOTALES,PHAEOPHYCEAE) SPECIES FROM THE CANARY ISLANDS1

Coexistence in a homogeneous environment requires species to specialize in distinct niches. Sympatry of cryptic species is of special interest to both ecologists and evolutionary biologists because the mechanisms that facilitate their persistent coexistence are obscure. In this study, we report on two sympatric Dictyota species, D. dichotoma (Huds.) J. V. Lamour. and the newly described species D. cymatophila sp. nov., from the Canary Islands. Gene sequence data (rbcL, psbA, nad1, cox1, cox3, and LSU rDNA) demonstrate that D. dichotoma and D. cymatophila do not represent sister species. Rather, D. cymatophila and D. dichotoma have converged on a nearly identical morphology, only to be distinguished with detailed morphometric observations. Both species co‐occur in eulittoral pools and the shallow subtidal in Tenerife. Even though D. cymatophila was more dominant in wave‐exposed places and D. dichotoma in less exposed areas, the spatial distribution of both species overlapped in intermediate habitats. The species display radically different phenologies. D. dichotoma reached its highest density in winter and early spring and disappeared nearly completely in autumn, while D. cymatophila dominated the study site from July until November. The timing of gamete release also differs between both species, D. dichotoma releasing gametes twice every lunar cycle, while the release of gametes in D. cymatophila occurred roughly every other day.     

SPECIES DELIMITATION,TAXONOMY, AND BIOGEOGRAPHY OF DICTYOTA IN EUROPE (DICTYOTALES,PHAEOPHYCEAE)1

Taxonomy of the brown algal genus Dictyota has a long and troubled history. Our inability to distinguish morphological plasticity from fixed diagnostic traits that separate the various species has severely confounded species delineation. From continental Europe, more than 60 species and intraspecific taxa have been described over the last two centuries. Using a molecular approach, we addressed the diversity of the genus in European waters and made necessary taxonomic changes. A densely sampled DNA data set demonstrated the presence of six evolutionarily significant units (ESUs): Dictyota dichotoma (Huds.) J. V. Lamour., D. fasciola (Roth) J. V. Lamour., D. implexa J. V. Lamour., D. mediterranea (Schiffn.) G. Furnari, D. spiralis Mont., and the newly described D. cyanoloma sp. nov., which was previously reported as D. ciliolata from the Mediterranean Sea. Species distributions, based on DNA‐confirmed occurrence records, indicate that all species are geographically confined to the NE Atlantic Ocean with the exception of D. dichotoma and D. implexa, which also occur in South Africa and Bermuda, respectively. To investigate potential hybridization between D. dichotoma and D. implexa, which were previously shown to be sexually compatible in culture, we compiled and analyzed sets of mitochondrial, plastid, and nuclear markers to detect putative hybrids or introgression in natural populations. Failure to detect natural hybrids indicates that effective pre‐ and postzygotic isolation mechanisms are at play in natural populations and supports the by‐product hypothesis of reproductive isolation.     

Chloroplast phylogeography of Iris dichotoma (Iridaceae), a widespread herbaceous species in East Asia

Both a complex topography and climate change have huge impacts on the distribution and genetic structure of extant species. Due to the lack of relevant molecular research, little is definitively known about the phylogeography of herbaceous plants in East Asia. Here we investigate the genetic diversity, population structure and historical population dynamics of Iris dichotoma Pallas, a widespread perennial herbaceous species in northeastern and northern China. Twenty-nine populations, totalling 297 individuals, were sampled throughout the Chinese distributional range of I. dichotoma. The combined sequences of six chloroplast DNA fragments (petA-psbE, rps18-clpp, psbJ-petA, trnD-trnT, rps16 and ndhA) were used to identify 13 haplotypes, of which six were private ones restricted in a single population. Genetic differentiation among I. dichotoma populations, enabled us to infer potential refugia during the glacial period in the Yinshan Mountains–Yanshan Mountains, where high levels of haplotype and nucleotide diversity were detected. The results of a neutral test and mismatch distribution analysis both indicated that I. dichotoma underwent a recent population expansion. In East Asia, postglacial environmental and climatic changes appear to have promoted genetic diversification not only in better-studied woody species, but also in herbaceous ones like I. dichotoma. Future studies of more herbaceous plant species are needed to obtain better insight into how modern temperate biodiversity has developed in East Asia.     

A taxonomic appraisal on the rare green algal genus Ecballocystopsis M.O.P.Iyengar (Chlorellales: Trebouxiophyceae): morphological and numerical approach

Ecballocystopsis (Oocystaceae, Chlorellales, Trebouxiophyceae) is a rare green algal genus, represented by only five taxa: E. dichotoma var. dichotoma from China and E. indica, E. desikacharyi, E. himalayensis and E. dichotoma var. minuta from India. Here we propose the novel variety E. dichotoma var. anandii from Jharkhand, synonymization of E. himalayensis with E. dichotoma and erection of E. dichotoma var. minuta to a separate species as E. minuta stat. et comb. nov. These taxonomic changes are well supported by the results of a multivariate analysis based on a numerical taxonomic approach. Cluster analysis (CA), principal component analysis (PCA) and principal coordinates analysis (PCoA) were performed to resolve the species delimitation ambiguity and supplement the morphology-based classification of the genus. Ecballocystopsis himalayensis and E. dichotoma grouped in a single cluster along with the proposed new variety, while E. indica, E. desikacharyi and E. minuta formed separate clusters. An identification key to the species of the genus Ecballocystopsis is also presented.     

Terbutryn resistance in Vaucheria dichotoma

Infestations of Vaucheria dichotoma have been reported to become resistant to the herbicide terbutryn after successful control by annual or biennial applications for 11 years. V. dichotoma was isolated from a site where terbutryn treatment gave good control and from a site where terbutryn treatment had failed. The isolate from the latter was resistant to terbutryn in laboratory toxicity tests. The resistant strain was not killed until the dose of terbutryn was increased to more than double the concentration approved for use in British waters. The shape of the resistance curve indicated that the resistance mechanism was not by modification of the protein binding site, suggesting that differential uptake, translocation and/or degradation is involved.     

Rhizoid production in excised Dictyota dichotoma

Excised segments of fronds of Dictyota dichotoma (Huds.) Lamour. show a marked basipetal increase in rhizoid production when grown in culture. Rhizoid production is inhibited by bright light and apparently enhanced by red light (λ 600–690 mμ).     

Light and Branch Formation in the Alga Vaucheria dichotoma (Xanthophyceae)

Branches of Vaucheria dichotoma (L.) Ag. were induced in two ways: by cutting, which led to a branch in the wound area and by exposure to light. Blue and red light were most active in branch formation. The light intensity dependence and the action spectrum of branch formation showed patterns similar to those of photosynthesis. Photosynthetic involvement was also indicated by the DCMU inhibition of branch formation. Elongation-branching studies at different photoperiods showed that branching was increased by the presence of more photosynthetic light than was necessary for elongation. It may be concluded that photosynthesis exerted the main control of the branch formation of V. dichotoma. However, the action spectrum of branch formation showed a higher efficiency in blue light than would be expected from the action spectrum of photosynthesis. It is therefore possible that apart from the main induction via the photosynthetic pigments, other blue light sensitive pigments may have a regulatory effect. Far-red light treatment of filaments pre-exposed to 8-h and 16-h light periods did not affect branch formation. Spectrophotometrical detection of phytochrome was not successful. This may indicate that there is no participation of phytochrome in branch formation. I am indebted to Dr. Lisbeth Fries for her interest. I also wish to thank Prof. Lars Olof Björn and his friendly staff at the Institute of Plant Physiology at the University of Lund, where some of the experiments were carried out. I am grateful to AB Tomaso Minori for revising the English test and to Miss Inga-Britt Jansson for typing it. The investigation was supported financially by a grant to Dr. Lisbeth Fries from the Swedish National Science Research Council.     

侵蚀退化地植被恢复过程中芒萁对土壤可溶性有机碳的影响

林下植被是生态系统的重要组分。通过对比分析红壤侵蚀区植被恢复过程中,林下有无芒萁覆盖地的土壤可溶性有机碳(DOC,Dissolved Organic Carbon)含量及其与地下根系生物量、地上植被淋溶液DOC含量的关系。结果表明:林下植被芒萁覆盖增加了地上叶片和地下根系生物量,土壤DOC含量及储量也显著增加(P0.05),芒萁覆盖对表层土壤(0—20cm)DOC的影响大于深层土壤(20—100cm)(P0.05);相关分析结果表明,林下芒萁覆盖地土壤DOC储量与细根生物量的垂直变化呈显著的正相关关系(P0.05),且随植被恢复年限的增加相关性显著增加,地下根系的垂直分布直接影响各土层DOC储量。不同植被恢复时期,林下芒萁覆盖地土壤DOC与鲜叶(马尾松+芒萁)和枯落物(马尾松+芒萁)淋溶液DOC均呈显著的正相关关系(P0.01),而林下裸露地土壤DOC仅与鲜叶(马尾松)淋溶液DOC呈显著的相关性(P0.01),林下芒萁覆盖地相对于裸露地枯落物淋溶液对土壤DOC储量的影响大于鲜叶。植被恢复过程中芒萁覆盖地土壤微生物生物量碳和微生物熵显著高于林下裸露地。因此,在植被恢复进程中,芒萁能够提供更多底物参与土壤物质与养分循环,对土壤DOC的贡献较大,为侵蚀区马尾松林恢复提供了重要的养分再吸收来源;同时芒萁覆盖增加了微生物活性,促进了微生物对土壤DOC的同化作用,提高了微生物碳源的利用率,对土壤有机碳的积累起着重要的作用。     

不同生境银柴胡根内生菌群落特征及其与药材主要有效成分、产量的相关性分析

【背景】银柴胡（Stellaria dichotoma var.lanceolata）具有重要的临床药用价值,其总甾醇和总黄酮含量是评价药材的关键。【目的】探究药用植物银柴胡在不同生境下根内生菌群落特征及其与药材主要成分、产量之间的关系。【方法】采用高通量测序技术和药材常规测定方法,分析了风沙土（semi-fixed aeolian sandy soil,SFA）生境、石砾质土（lithosol,LI）生境和黄绵土（loessal,LO）生境银柴胡根内生菌群落特征及其与药材性状响应关系。【结果】各生境银柴胡内生优势细菌门为放线菌门（Actinobacteriota）和变形菌门（Proteobacteria）,优势真菌门为子囊菌门（Ascomycota）和担子菌门（Basidiomycota）,而内生优势菌属因生境不同各不相同;银柴胡药材主要有效成分总甾醇和总黄酮含量在LI生境中较高,而单株干重和干鲜比在SFA生境中较高。Spearman相关性分析表明,与银柴胡药材有效成分及产量显著正相关的内生菌相对较多。综合比较,内生细菌如metagenome_g__norank_f__67-14和内生真菌如unclassified_p__Ascomycota等更为显著。【结论】与银柴胡药材关键活性成分相关的内生菌群落在种类鉴定和提取、菌种培养和次生代谢物分析等方面具有广阔的研究价值。本研究为银柴胡道地产区药材高质量产业发展提供理论参考。     

Exosome isolation from hemolymph of Korean rhinoceros beetle,Allomyrina dichotoma (Coleoptera: Scarabaeidae)

Exosomes are 30–150 nm vesicles that are secreted from a range of cells. Recently, exosomes have been the subject of considerable research because there is mounting awareness of their diverse functions, including a role in cell–cell communication and presenting pathogens for immune responses. Exosomes contain diverse nucleic acid and protein cargos, derived not only from the organism but also from pathogens, making them suitable for use in disease diagnosis. The Korean rhinoceros beetle, Allomyrina dichotoma (Coleoptera: Scarabaeidae), is commercially reared in Korea for the pet trade and is used in traditional medicine for liver‐related diseases. However, several insect diseases caused by bacteria, fungi and viruses have been reported in A. dichotoma mass‐rearing facilities. Identifying these diseases with accuracy and in a timely manner is of paramount importance. Such diagnosis can be accomplished by identifying the nucleic acid or amino acid fragments from these disease‐causing pathogens in the exosome of A. dichotoma. We isolated exosomes from the hemolymph of A. dichotoma and used them to analyze exosome RNA and proteins. We confirmed the isolation of exosomes through RNA profiling, protein analysis and Western blotting. Our research established a solid foundation for using insect exosome protein and RNA analyses for the accurate diagnosis of insect diseases. To our knowledge, this is the first report of exosome isolation from insect hemolymph.     

Establishment of a loop‐mediated isothermal amplification system for on‐site diagnosis of Oryctes rhinoceros nudivirus in Allomyrina dichotoma (Coleoptera: Scarabaeidae)

The Korean insect industry is rapidly developing, with the Korean horn beetle Allomyrina dichotoma as one of the most popular insects kept as pets. Korean horn beetles reared in local farms are suffering from Oryctes rhinoceros nudivirus (OrNV). In a nationwide investigation on the early death of young larvae due to this virus, 70 to 77% mortality was found. It was also confirmed that several larvae collected from some wild horn beetle habitats were infected with the virus. Thus, it was concluded that the virus could be transmitted vertically from an infected adult to the offspring and that the OrNV disease is a very serious threat to the wild horn beetle in Korea. With local farmers expecting that an early detection technique would be helpful for the quick removal of infected larvae, an on‐site diagnosis method for the viral disease using loop‐mediated isothermal amplification (LAMP) assay was thus tested. To avoid the DNA extraction process, the LAMP assay used a 50‐fold diluted hemolymph was set for diagnosis standardization and convenient on‐site application to infected larvae from local farms. A. dichotoma larvae were assayed for the OrNV infectivity with LAMP primers targeting the OrNV_gp102 gene. To evaluate the LAMP specificity, two bacterial pathogens, Bacillus thuringiensis and Serratia marcescens, causing disease in A. dichotoma were tested along with OrNV. The positive results were detected only from the OrNV‐infected larvae.     

The plastome of a brown alga,Dictyota dichotoma

Summary Plastids of the brown algaDictyota dichotoma contain a single homogeneous DNA species which bands at a buoyant density of 1.693 g/cm³ in neutral CsCl equilibrium density gradients. The corresponding nuclear DNA has a density of 1.715 g/cm³. The molecular size of the plastid DNA is 123 kbp as calculated by both electron microscopy of spread intact circular molecules and gel electrophoresis following single and double digestions with various restriction enzymes. A restriction map has been constructed using the endonucleases Sal I, Bam HI, and Bgl II which cleave theDictyota plastome into 6, 12, and 17 fragments, respectively. No large repeated regions, as found in chlorophycean andEuglena plastid DNAs, were detected.Dictyota dichotoma is the first member from the chlorophyll c-line of the algal pedigree for which a physical map of plastid DNA has been established. Dedicated to Professor Dr. W. Stubbe on the occasion of his 65th birthday.     

Phytoremediation of petroleum hydrocarbon-contaminated saline-alkali soil by wild ornamental Iridaceae species

As a green remediation technology, phytoremediation is becoming one of the most promising methods for treating petroleum hydrocarbons (PHCs)-contaminated soil. Pot culture experiments were conducted in this study to investigate phytoremediation potential of two representative Iridaceae species (Iris dichotoma Pall. and Iris lactea Pall.) in remediation of petroleum hydrocarbon-contaminated saline-alkali soil from the Dagang Oilfield in Tianjin, China. The results showed that I. lactea was more endurable to extremely high concentration of PHCs (about 40,000 mg/kg), with a relatively high degradation rate of 20.68%.The degradation rate of total petroleum hydrocarbons (TPHs) in soils contaminated with 10,000 and 20,000 mg/kg of PHCs was 30.79% and 19.36% by I. dichotoma, and 25.02% and 19.35% by I. lactea, respectively, which improved by 10–60% than the unplanted controls. The presence of I. dichotoma and I. lactea promoted degradation of PHCs fractions, among which saturates were more biodegradable than aromatics. Adaptive specialization was observed within the bacterial community. In conclusion, phytoremediation by I. dichotoma should be limited to soils contaminated with ≤20,000 mg/kg of PHCs, while I. lactea could be effectively applied to phytoremediation of contaminated soils by PHCs with at least 40,000 mg/kg.     

Effect of solar ultraviolet radiation on growth in the marine macroalga Dictyota dichotoma (Phaeophyceae) at Helgoland and its ecological consequences

At Helgoland, in the North Sea, growth of the high sublittoral brown macroalga Dictyota dichotoma (Hudson) Lamoroux was examined in October (the time of tetraspore release) in an outdoor tank by exposing 2-day-old germlings to four solar radiation treatments achieved with different filter materials or an additional artificial light source: photosynthetically active radiation (PAR; 395–700 nm), PAR plus ultraviolet (UV)-A (320–700 nm), full solar spectrum, or solar spectrum plus artificial UV radiation (UVR). Based on length measurements over a period of 3 weeks, the growth rate in germlings strongly decreased in conditions with UVR compared to PAR: by 14% under PAR+UV-A, by 31% under the full solar spectrum and by 65% with additional UVR. Although growth rates of germlings under UVR were reduced mainly in the first week, the plants did not regain the size of the untreated plants even after 9 weeks. Regardless of the exposure, no defects in morphology or anatomy including the exposed apical meristem were detected, except for a reduction in cell division rates perhaps due to additional cost for photoprotective or repair mechanisms. Depending on the actual position of D. dichotoma plants in the natural habitat, individuals in high positions receive substantial amounts of the more harmful UV-B while those lower down might only receive UV-A during part of the day, thus the effect of UV-B on the growth of D. dichotoma will depend on its position in the field. The effects of tidal variation of the light climate and the implications of our results for the zonation of D. dichotoma are discussed. Received in revised form: 6 July 2000 Electronic Publication     

蕨类植物碳氮磷化学计量特征及其与土壤养分的关系

为探讨蕨类植物碳氮磷化学计量特征与土壤养分的关系,对福建省亚热带森林林下芒萁和乌毛蕨地上部分和地下部分的碳、氮、磷(C、N、P)含量和0~10 cm和10~20 cm两个土层的养分含量进行了测定。结果表明,无论是芒萁还是乌毛蕨,地上部分的N、P含量均高于地下部分,而C含量则无显著差异,导致地上部分的C∶N和C∶P均低于地下部分。与乌毛蕨相比,芒萁地上部分的N、P含量更低,地上和地下部分的C含量、C∶N和C∶P以及N、P含量的变异系数和表型可塑性指数则更高,表明芒萁采取了较高的养分利用效率和"表现最大化"的策略,而乌毛蕨则选择了较低的养分利用效率和"表现维持"的方式。两种蕨类植物地上和地下部分的N含量与土壤N含量(0~20 cm)均无显著相关。芒萁两个部位的P含量则均与土壤P含量(0~10 cm和10~20 cm)呈显著正相关,乌毛蕨P含量总体上与土壤P含量的相关性不显著(除地下部分的P含量与10~20 cm土层的P含量呈弱的正相关外)。这表明芒萁具有作为亚热带森林土壤P库指示植物的潜力。     

A role of mulberry leaves in improving resistance to virus‐mediated disease in Allomyrina dichotoma

The purpose of this study was to develop a safe and effective method for preventing Allomyrina dichotoma nudivirus (AdNV) infection in the Korean horned beetle, Allomyrina dichotoma, found on the farms in the Republic of Korea. Mulberry leaf powder was added to fermented oak sawdust to minimize mortality in AdNV‐infected A. dichotoma. Mulberry leaves were found to contain 1‐deoxynojirimycin, which has anti‐inflammatory, antiviral, and anti‐tumor effects. Based on the proposed antiviral effects of mulberry leaves, a feed of fermented sawdust combined with 1% or 5% mulberry leaf powder was fed to AdNV‐infected second or third stage A. dichotoma larvae. The larval mortality rate was recorded over 10 weeks. The second and third instar larvae that were fed with the sawdust mixture with 5% mulberry leaf powder had mortality rates of 60% and 30%, respectively. In contrast, the control group that was fed with the sawdust without mulberry leaf powder had a mortality rate of 100%. Also, we confirmed that AdNV was not detected in the experimental group that was subjected to an outdoor application test for 8 months with mulberry leaf powder treatment. A reduced mortality rate after treatment with 1% mulberry leaf powder was observed in the field application. In addition, a comparison of the control colony and mulberry leaf treated group showed a statistical difference in growth of larvae at various states, and demonstrated the efficiency of mulberry leaf powder combined with fermented sawdust for treatment of AdNV‐ infected A. dichotoma.     

OVERWINTERING OF DICTYOTA DICHOTOMA (PHAEOPHYCEAE) NEAR ITS NORTHERN DISTRIBUTION LIMIT ON THE EAST COAST OF NORTH AMERICA1

The mechanism of yearly repopulation of Dictyota dichotoma (Hudson) Lamouroux in the inshore waters of North Carolina was studied in the field and in laboratory experiments. It was demonstrated that D. dichotoma is maintained throughout the year at this location and does not require yearly immigrations. A young germling stage was shown to function as the overwintering structure. Although release of aplanospores was unaffected by temperature and photoperiod, subsequent germination and establishment required warm conditions. If germlings were allowed to grow to the 7–9 cell stage under summer conditions, they could survive 21 wk of winter conditions. Transfer of 21 wk old winterized germlings to summer conditions resulted in the rapid production of erect blades. It therefore appears that D. dichotoma maintains its populations near its northern distribution limit on the East Coast of North America by undergoing dormancy after germling establishment.     

Effects of solvent fractions of Allomyrina dichotoma larvae through the inhibition of in vitro BACE1 and β‐amyloid(25–35)‐induced toxicity in rat pheochromocytoma PC12 cells

Amyloid‐β peptide (Aβ) generation initiated by β‐site amyloid precursor protein cleaving enzyme 1 BACE1 is a critical cause of Alzheimer's disease. In the course of our ongoing investigation of natural anti‐dementia resources, the ethyl acetate (EtOAc) fraction exerted strong BACE1‐specific inhibition with the half maximal inhibitory concentration (IC₅₀) value of 9.2 × 10^?5 μg/mL. Furthermore, Aβ(25–35)‐induced cell death was predominantly prevented by the EtOAc fraction of Allomyrina dichotoma larvae through diminishing of cellular oxidative stress and attenuating apoptosis by inhibiting caspase‐3 activity. Taken together, the present study demonstrated that A. dichotoma larvae possess novel neuroprotective properties not only via the selective and specific inhibition of BACE1 activity but also through the alleviation of Aβ(25–35)‐induced toxicity, which may raise the possibility of therapeutic application of A. dichotoma larvae for preventing and/or treating dementia.