Evidence of high mercury accumulation in the cell wall of the liverwort Jungermannia vulcanicola Steph. to form particles of a mercury-sulphur compound

Abstract

Transmission electron microscope and X-ray microanalyser studies were carried out on the cells of mercury accumulating aquatic liverwort Jungermannia vulcanicola from Kashiranashigawa Stream.

The mercury which is accumulated from stream water is mainly located in the cell wall in the form of electron dense particles having the size range 0.01 – 0.1 μm up to 0.2 μm. The chemical form of the mercury in the electron dense particles is a mercury-sulphur compound, probably mercuric sulphide, which is not toxic to living organisms.     

一株肠膜明串珠菌的分离鉴定及其抑菌特性

[背景] 水产病原细菌严重威胁水产动物健康且制约水产养殖业发展,细菌性鱼病的有效防治成为水产养殖领域亟待解决的问题。[目的] 筛选对水产病原细菌有抑制效果的菌株,并研究其抑菌特性及其在水产细菌病害防治中的实际效果。[方法] 通过16S rRNA基因测序、构建系统发育树和生理生化鉴定确定筛选菌株的进化地位,通过乙酸乙酯萃取获得抑菌物质粗提物,通过偶氮酪蛋白法检测菌株胞外蛋白酶活力,采用结晶紫染色法对菌株的生物膜形成能力进行测定,通过浸浴攻毒模型确定所筛菌株对维氏气单胞菌的防治作用。[结果] 从泡菜发酵物中筛选出一株乳酸菌DH,经16S rRNA基因测序、发育树分析和生理生化鉴定确定其为肠膜明串珠菌,该菌分泌的胞外抑菌物质对鼠伤寒沙门氏菌、大肠埃希氏菌、铜绿假单胞菌、杀鲑气单胞菌、希瓦氏菌和维氏气单胞菌表现出抑菌效果,其抑菌物质能被乙酸乙酯萃取并且具有热稳定性。菌株DH能够显著抑制待测菌株的蛋白酶产量和生物膜形成能力,并且对维氏气单胞菌浸浴攻毒有防治作用。[结论] 肠膜明串珠菌DH通过分泌抑菌物质抑制水产病原细菌的生长,能够为细菌性鱼病的防治提供一定的理论和应用潜力。     

一株可增强莱茵衣藻耐盐能力细菌MEZX29的分离与鉴定

【背景】水体中的藻类、细菌及这些微生物之间的相互作用对水体生态系统的功能有着重要作用。近年来,一些河流、湖泊等淡水资源的盐渍化不断加重,对水体生态系统造成严重影响。然而,高盐胁迫条件如何影响藻类与其他细菌的相互作用,以及是否存在能够促进藻类耐盐能力的有益细菌等问题尚未得到深入研究。【目的】分离和鉴定可以促进淡水藻类莱茵衣藻抗盐能力的细菌,并开展相关机制分析。【方法】通过富集培养、筛选和共接种实验,获得可以促进衣藻耐盐的细菌;基于活细胞浓度、叶绿素含量等参数评价衣藻在不同条件下的生长能力;对菌株进行16S rRNA基因序列分析和基因组分析,预测其可能的菌藻相互作用机制。【结果】获得一株在250-290 mmol/L NaCl条件下可以显著增强衣藻耐盐能力的菌株MEZX29,16S rRNA基因序列分析表明,该菌可能属于Rhodococcus qingshengii;基因组分析结果表明,该细菌含有参与糖代谢、乙烯合成、生物膜形成等途径的基因,这些基因可能在促进衣藻抗盐过程中起到重要作用。【结论】Rhodococcus qingshengiiMEZX29可以增强莱茵衣藻21gr抵抗高盐胁迫的能力,为研究藻类与其他微生物之间的有益相互作用提供了新的材料。     

Regeneration capacity of oceanic-montane liverworts: implications for community distribution and conservation

Abstract

Scotland’s mountains are home to a rare and unique liverwort community, ‘the oceanic-montane liverwort-rich heath’, but its component species are absent from regions where they could potentially thrive. Many biological characteristics of these species are unknown, making it impossible to explain the reasons for their rarity; however, they have not been observed to produce sporophytes within Britain. We use ex situ cultivation of whole liverworts and fragments, and in situ cultivation of fragments, to assess the growth rate and the potential for vegetative reproduction of several species. Most of the species grew from both fragments and as whole plants, indicating that the rarity of the liverwort heath is not due to poor powers of regeneration. We propose that growth rate and the potential to regenerate from fragments are important factors structuring the liverwort heath community, at least locally. Furthermore, this study demonstrates that there is potential for ex situ conservation of rare liverwort species, in situ enhancement of existing populations, and creation of new ones.     

镉离子污染条件下微生物群落中细菌与藻类的相互作用

【背景】水体微生物有着丰富的多样性,不同种类的微生物之间的相互作用对水体生态系统的组成结构与功能具有重要影响。水体内的藻类与某些微生物可以发生多种相互作用,然而人们对逆境条件下的菌藻有益相互作用尚缺乏深入研究。【目的】为了研究镉对水体微生物群落的影响以及镉胁迫下菌藻之间可能的相互作用。【方法】本研究运用了基于16S rRNA基因的高通量测序技术,分析在不同Cd~(2+)条件下微生物群落结构的变化,利用微生物相互作用网络分析菌藻之间可能发生的相互作用。【结果】通过分离培养筛选出了与集胞藻PCC6803互作抗Cd~(2+)的关键细菌Y9菌株。【结论】研究结果表明Y9菌株属于Phyllobacteriaceae科,与微生物群落组成和微生物互作网络的分析结果相符。本研究为探索水体环境中微生物种间相互作用、菌藻互作抗Cd~(2+)的生态效应提供参考依据。     

Occurrence of antibiotic activity in Conocephalum conicum,Mnium undulatum and Leptodictyum riparium (Bryophytes)

Abstract

In the present work the results on antibiotic activity of the extracts from the liverwort Conocephalum conicum and the mosses Minium undulatum and Leptodictyum riparium, tested against 8 bacterial strains pathogenic to man, are referred to. The extracts have been obtained, according the method suggested by McCleary et al. (1960), in either organic solvents or in water solution. The extracts have been proved active on both bacteria Gram + ve (G +) and Gram—ve (G—), in addition the extracts from Conocephalum conicum and Leptodictyum riparium (extracts in organic solvents in particular) were the most effective in the tests. The acetone extracts from Leptodictyum riparium showed the highest value of inhibition against Pseudomonas aeruginosa (bacterium responsible for serious opportunist infections). Our results on antibiotic activity of Bryophytes only partly agree with literature for either species showing activity or for the intensity of such activity. Among the three bryophytes employed Leptodictyum riparium showed the best inhibitory power against all bacteria tested. This result seems particularly interesting in relation to the possible competition between species occurring in the water where this moss preferentially grows. The phenomenon of antibiosis in the bryophytes is discussed also in relation to symbiotic or commensal relationships existing with soil bacteria and/or fungi.     

锑矿废水影响下水库沉积物中细菌群落结构特征研究

【背景】水库沉积物中的微生物是水生态系统的重要组成部分,在沉积物物质循环中起重要作用。【目的】揭示含锑废水影响下水库表层沉积物中细菌群落结构特征及影响因子。【方法】基于Illumina高通量测序技术,对冷水沟水库表层沉积物细菌群落结构进行研究并分析其与沉积物理化性质的相关性;基于FAPROTAX软件对细菌功能进行预测分析。基于重金属污染负荷指数法评价水库重金属污染情况。【结果】高通量测序结果表明冷水沟水库的细菌群落较为丰富,主要由变形菌门(Proteobacteria,40.32%-20.19%)、拟杆菌门(Bacteroidetes,25.89%-4.44%)、脱硫杆菌(Desulfobacter,9.43%-2.02%)等81个门570个属组成。相关性分析表明,不同提取形态的锑及水溶态锑与多个不同分类水平下的细菌群落有显著的相关性。FAPROTAX软件对细菌功能进行预测,结果表明,化能异养功能细菌占优势(占总细菌的14.59%-23.58%),包括化能异养(Chemoheterotrophy)和需氧化能异养(Aerobic Chemoheterotrophy);此外,与碳、氮、硫元...     

Aerial and underground biomasses of three Sphagnum-dwelling liverworts

Abstract

The few studies that have investigated levels of genetic variation in liverworts have found very little polymorphism. Our electrophoretic data show, however, that the leafy liverwort Porella platyphylla maintains high levels of genetic variation in at least some natural populations from the southeastern United States. Within a single population from southwestern North Carolina, we detected 26 distinct multilocus genotypes and more than 80% of the enzyme loci we surveyed were polymorphic. It seems likely that earlier studies of mostly thalloid species from glaciated regions of Europe have presented a biased picture of levels of variation in liverwort populations.     

The occurrence of axillary antheridia in dioecious mosses

Abstract

Antheridia that are undoubtedly axillary occur in species of Bryum, Mnium and Aulacomnium. It is suggested that this is a primitive feature and that the typical moss antheridial head, with all the antheridia apparently terminal, has been derived from species with axillary antheridia, either by restriction of the antheridia to the axils of the uppermost bracts, as in the liverwort Haplomitrium blumei, or by the suppression of the upper bracts.     

Influence of Temperature on the Effects of Artificially Enhanced UV-B Radiation on Aquatic Bryophytes Under Laboratory Conditions

We examined, under laboratory conditions, the influence of temperature (2 °C vs. 10 °C) on the physiological responses of two aquatic bryophytes from a mountain stream to artificially enhanced UV-B radiation for 82 d. These organisms may be exposed naturally to relatively low temperatures and high levels of UV-B radiation, and this combination is believed to increase the adverse effects of UV-B radiation. In the moss Fontinalis antipyretica, UV-B-treated samples showed severe physiological damages, including significant decreases in chlorophyll (Chl) and carotenoid (Car) contents, Chl a/b and Chl/phaeopigment ratios, Chl a fluorescence parameters F_v/F_m and _PS2, electron transport rate (ETR_max), and growth. In the liverwort Jungermannia cordifolia, UV-B radiation hardly caused any physiological change except for growth reduction. Thus, this liverwort seemed to be more tolerant to UV-B radiation than the moss under the specific experimental conditions used, maybe partly due to the accumulation of UV-B absorbing compounds. The influence of temperature on the effects of UV-B radiation depended on the species: the higher the UV-B tolerance, the lower the influence of temperature. Also, different physiological variables showed varied responses to this influence. Particularly, the lower temperature used in our study enhanced the adverse effects of UV-B radiation on important physiological variables such as F_v/F_m, growth, and Chl/phaeopigment ratios in the UV-B-sensitive F. antipyretica, but not in the more UV-B-tolerant J. cordifolia. Thus, the adverse effects of cold and UV-B radiation were apparently additive in the moss, but this additiveness was lacking in the liverwort. The Principal Components Analyses (PCA) conducted for both species with the physiological data obtained after 36 and 82 d of culture confirmed the above results. Under natural conditions, the relatively high water temperatures in summer might facilitate the acclimation of aquatic bryophytes from mountain streams to high levels of UV-B radiation. This may be relevant to predict the consequences of concomitant global warming and increasing UV-B radiation.     

Mnioloma fuscum (Marchantiopsida: Calypogeiaceae), an unexpected addition to the indigenous flora of New Zealand

Abstract

Mnioloma fuscum, a liverwort species known to date primarily from tropical-montane regions, is reported for New Zealand for the first time. Its occurrence in New Zealand is unexpected as the next nearest known site is believed to be the Solomon Islands, some 3500 km distant. The occurrence of Mnioloma fuscum in New Zealand highlights the contribution tropical regions have made to the composition of New Zealand's hepatic flora.     

Culture studies on Radula flaccida Lindenb. & Gottsche

Abstract

Radula flaccida has been grown on defined inorganic media. Its growth varies with the type and concentration of the media, lower concentrations proving better than higher ones. Basile's medium supported a better growth of the liverwort than that of Diller et al., Müller's medium being least effective. The liverwort was successfully established on leaves and bark of some higher plants, thus proving that it is not ‘host’ specific with respect to leaf types and that it is not exclusively epiphyllous. Its less frequent occurrence on bark may be due to other habitat factors.     

Stabilizing Effect of Lipopolysaccharide on the l-Glycerol 3-Phosphate Acyltransferase of Escherichia coli Membrane

A gene, frxC, which is unique to the chloroplast genome of the liverwort Marchantia polymorpha, has sequence similarity to nifH, the product of which is an iron protein of a nitrogenase. Although frxC is expressed to produce a protein in liverwort chloroplasts, its function is not known. Using a probe of liverwort chloroplast DNA, a 10.1-kb region containing a gene cluster consisting of open reading frames (ORF278-frxC-ORF469–0RF248) was isolated from the cyanobacterium Synechocystis PCC6803. In this region, frxC and ORF469 showed sequence similarities to liverwort chloroplast frxC (83%) and immediately downstream ORF465 (74%), respectively. Synechocystis frxC showed 31% amino acid sequence identity with nifHl from Clostridium pasteurianum. Additionally, Synechocystis ORF469 showed a sequence similarity (19% identity) to C. pasteurianum nifK product, which is the β subunit of a molybdenum-iron protein of a nitrogenase complex. Conservation of the gene arrangement between liverwort and Synechocystis suggests that the liverwort chloroplast frxC-ORF465 cluster may have evolved from an ancestor common to Synechocystis, and that these two genes may have been transferred to the nuclear genome in tobacco and rice during evolution.     

Studies in Ancient Bryology,I. Introduction and Liverworts to 1500 A.D.

Abstract

The processes leading to changes in the meanings of bryological names in the nearly two millenia from their earliest appearance to 1500 A.D. are described and exemplified, with a more detailed account of the histories of the liverwort words: Lichen, (H)epatica, Pulmonaria, Jecoraria, Fegatella.     

Studies on the genus Mastigolejeunea (Marchantiophyta: Lejeuneaceae): Mastigolejeunea gradsteinii Sukkharak sp. nov.

Abstract

The liverwort Mastigolejeunea gradsteinii Sukkharak sp. nov. (Lejeuneaceae) is described from Malaysia. The new species is characterised by (1) rigid stem with epidermal cells as large as medullary cells, (2) apiculate leaf apex, (3) curved lobules without teeth, and (4) perianths with 7–8 keels.     

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.     

锡林河流域潜在不产氧光合细菌陆向分异特征及影响因素

【目的】为探明锡林河流域潜在不产氧光合细菌（anoxygenic photosynthetic bacteria,AnPB）的陆向分异特征及影响因素。【方法】本研究沿着陆向梯度依次采集水生湍流带、缓流带、滞流带、水偏湿生样带、湿偏旱生样带、旱生样带土壤样品。基于文献建立AnPB在科水平的数据库,运用16S rRNA基因高通量测序筛选科水平潜在AnPB类群及其组成丰度的陆向分异,运用皮尔逊相关性及冗余分析等研究土壤理化因子对潜在AnPB陆向分异的影响。【结果】紫色硫细菌（外硫红螺菌科）和紫色非硫细菌（红杆菌科、红环菌科、醋酸杆菌科、丛毛单胞菌科、全噬菌科）主要分布在水生及水偏湿生生境,其相对丰度与湿度呈显著（P<0.05）或极显著（P<0.01）正相关关系;紫色非硫细菌（红螺菌科、慢生根瘤菌科、生丝微菌科、红菌科）、芽单胞菌科、酸杆菌科、绿色非硫细菌（蔷薇菌科）等主要分布在湿偏旱生和旱生环境中,其相对丰度与盐度和全氮含量呈显著（P<0.05）或极显著（P<0.01）正相关关系;多元回归树分析显示,盐度、湿度、全氮对潜在AnPB陆向分异的总解释度分别为62.39%、...     

Athalamia hyalina (Sommerf.) S.Hatt. in Scotland,new to the British Isles

Abstract

The liverwort Athalamia hyalina (Sommerf.) S.Hatt. and the family Cleveaceae are reported as new to the British Isles from the eastern Scottish Highlands. The Scottish plants are described and illustrated and the significance of the discovery is assessed. In Scotland, Athalamia hyalina occurs on thin soil on eroding limestone ledges in a montane habitat with a continental climate. It is in active growth in the winter months, producing spores in spring. Its range is restricted but it occurs within a protected area and is not threatened at present. The species is widespread in the northern hemisphere.     

The Habitat of Zygodon forsteri (Brid) Mitt. in the New Forest,Hants

Abstract

Seven species are reported here for the first time for South Georgia. Two of these were already known from Tierra del Fuego, Acrolophozia fuegiana Schust. and Marsupella sprucei (Limpr.) H. Bern., but Acrolophozia sulcata Hässel, Marsupella austrogeorgica Hässel, and Marsupella minutula Hässel are described as new. The additional two species which are described, Austrolembidium crassum Hässel and Greeneothallus gemmiparus Hässel, also required the creation of two new genera. The total number of liverwort species now known to be present on South Georgia is sixty-six.     

Expression of the Bacillus thuringiensis Mosquitocidal Toxin Cry11Aa in the Aquatic Bacterium Asticcacaulis excentricus

A mosquitocidal aquatic bacterium has been developed by introducing an operon containing the cry11Aa, and p20 genes from Bacillus thuringiensis subsp. israelensis (Bti) into the gram-negative aquatic bacterium Asticcacaulis excentricus. After transformation, the cry11Aa gene was successfully expressed in recombinant A. excentricus under the tac promoter, at the level of 0.04 pg/cell. The recombinant bacteria were toxic to Aedes aegypti larvae with an LC₅₀ of 6.83 × 10⁵ cells/mL. We believe that these bacteria may have potential as genetically engineered microorganisms for the control of mosquito larvae.