Cephalodella edax. sp. nov. A rotifer parasitic in the motile colonial alga Uroglena volvox Ehrenberg

A monogonont rotifer found parasitizing colonies of the motile alga Uroglena volvox Ehrenberg in two north English lakes is described as a new species. Diagnostic taxonomic details are given together with remarks on other rotifers known to occur in motile colonies of algae.     

Application of autonomous underwater vehicle and image analysis for detecting the three-dimensional distribution of freshwater red tide Uroglena americana (Chrysophyceae)

The spatial structure of Uroglena americana was detected usingan autonomous underwater vehicle equipped with a submersiblemicroscope, video recording system and water quality monitoringsensors. Uroglena americana colonies were enumerated via imageanalysis and pattern recognition methods. This quantitativetechnique is useful for understanding plankton assemblages,distributions and their potential to become nuisance algal blooms.     

Experimental Lake Fertilization in the Kuokkel Area,Northern Sweden. Phytoplankton Biomass and Algal Composition in Natural and Fertilized Subarctic Lakes

Based on 500 quantitative algal analyses from 1971–1980 the seasonal variations of phytoplankton biomass and species diversity have been evaluated in one natural and three fertilized subarctic lakes. Enrichment with P alone did not cause any biomass increase and inhibited dinoflagellates and Dinobryon. Enrichment with N alone stimulated Uroglena and Gymnodinium and the biomass increased. No species were inhibited. Enrichment with both N and P made the biomass increase 50–60 times and the stimulated genera were: Chlorella, Choricystis, Chromulina, Chrysochromulina, Gymnodinium, Monoraphidium, Ochromonas, Spiniferomonas, Rhodomonas and Uroglena. In all fertilized lakes monocultures of chlorococcal green algae finally developed.     

Differential sensitivity to natural ultraviolet radiation among phytoplankton species in Arctic lakes (Spitsbergen,Norway)

Incubation experiments demonstrated a differential sensitivity to natural UV-radiation among the dominant phytoplankton species from three Arctic lakes, situated near Ny-Ålesund, Spitsbergen (79° N). The growth of small chlorophytes, diatoms and picocyanobacteria from two oligotrophic lakes was inhibited primarily by the shorter wavelength UV components, while the growth of the larger colony-forming species (cyanobacteria, Planktothrix sp., Woronichinia sp. and the chrysophyte, Uroglena americana Calkins) apparently was stimulated. These colonies (not easily eaten by daphnids) dominated at the end of the experiment in those treatments where the short wavelength UV components were not excluded. For the two oligotrophic localities, 70 and 61%, respectively, of total phytoplankton biovolume were edible in the treatments excluding short wavelength UV, compared to only 13 and 19%, respectively, in the treatments including such radiation. For the third, more productive and less transparent lake, the percentage of edible species in the treatments with and without short wavelength UV radiation did not differ (ca. 75% for both treatments).     

Elucidating the evolution and diversity of Uroglena-like colonial flagellates (Chrysophyceae): polyphyletic origin of the morphotype

ABSTRACT

The Uroglena-like morphotype represents a prototype of a colonial naked chrysophyte, comprising plastid-bearing cells that are arranged as the surface monolayer of the spherical colony. So far, insufficient molecular characterization appears to be the most significant brake on the modern taxonomic revision of this ecologically and morphologically coherent group of organisms. The general aim of this work was to conduct a modern taxonomic revision of Uroglena-like flagellates by using combined molecular, morphological and ultrastructural methodology, complemented by exploring type localities of Uroglena volvox and Uroglenopsis americana in Europe and North America, respectively. On the basis of phylogenetic analysis of concatenated nuclear SSU rDNA and plastid rbcL sequences we show that Uroglena-like colonial flagellates form three genetically and morphologically distinct lineages within the Ochromonadales (Chrysophyceae), distinguished here as Uroglena, Uroglenopsis and Urostipulosphaera gen. nov. The taxonomic status of the other chrysophyte genera with spherical colonies is discussed in light of our findings.     

39 Phylogeny of aulacoseira (bacillariophyta)

Ochromonas sensu lato is the largest genus in the Chrysophyceae, containing over 100 names. Ochromonas species are biflagellate, naked, plastid-bearing single cells, distinguished from loricate, scaled, colonial and colorless genera. Most, if not all, species of Ochromonas are mixotrophic, i.e., they photosynthesize but they also engulf bacteria and other small prey. Preliminary evidence from SSU rRNA sequences show that Ochromonas is a polyphyletic genus. Ochromonas tuberculata is the most distinct from all other Ochromonas species. The other Ochromonas species (examined thus far) are scattered in three clades. For example, O. danica and O. sphaerocystis are sister to Poterioochromonas stipitata and P. malhamensis . Four additional species (identified by light microscopy as O. elegans Doflein, O. globosa Skuja, O. ovalis Dolfein, O. sociabilis Pringheim ) have SSU rRNA sequences identical to P. malhamensis . Of these, only O. sociabilis has been transferred to Poterioochromonas . Thus, at least some species may be synonymous with others. Two clades of marine species are also known, one containing coastal species and the other containing open ocean species. A number of genera (some also polyphyletic) are interspersed amongst the Ochromonas species (e.g., Chrysolepidomonas, Chrysonephele, Chrysoxys, Cyclonexis, Dinobryon, Epipyxis, Uroglena, Uroglenopsis ). The goal of this research (just beginning) is to establish a monophyletic Ochromonas , probably by assigning some species to other genera (existing or new). One major problem is that the type species, O. triangulata Vysotskii , hasn't been observed in over 100 years, and it is unclear which of several clades of Ochromonas contains the type. Results will be discussed.     

Long-term variations of epilimnetic phytoplankton in an artificial reservoir during a 10-year survey

Vieux-Pré is an artificial reservoir in the north-east part of France (61 Mm³), created in 1986 for hydraulic management. The phytoplankton and several environmental parameters in the upper part of the lake were monitored at a mid-lake station, from 1988 to 1997. The specific composition of the community changed during this period, from a predominantly pennate-diatom phytoplankton (Asterionella formosa, Fragilaria crotonensis), the lake passed to dominance by a sparse, motile nanoplankton (Mallomonas akrokomos, M. caudata, Cryptomonas erosa, Chroomonas/Rhodomonas, a.o.) and then by large colonies of small-celled species (Uroglena americana, Dinobryon spp., Radiocystis geminata, Aphanothece clathrata, Coelosphaerium kuetzingianum a.o.). This paper describes the algal successions involved and shows the decisive effects of the decrease of trophic level from an eutrophic stage to an oligo-mesotrophic condition. In the beginning, externally imposed disturbances (flooding and dewatering) were frequent, while now the lake has stabilised as a deep, stratified pelagic system. Under these conditions, autogenic phytoplankton appear to dominate.     

38 The sysytematics of ochromonas (chrysophyceae)

Ochromonas sensu lato is the largest genus in the Chrysophyceae, containing over 100 names. Ochromonas species are biflagellate, naked, plastid‐bearing single cells, distinguished from loricate, scaled, colonial and colorless genera. Most, if not all, species of Ochromonas are mixotrophic, i.e., they photosynthesize but they also engulf bacteria and other small prey. Preliminary evidence from SSU rRNA sequences show that Ochromonas is a polyphyletic genus. Ochromonas tuberculata is the most distinct from all other Ochromonas species. The other Ochromonas species (examined thus far) are scattered in three clades. For example, O. danica and O. sphaerocystis are sister to Poterioochromonas stipitata and P. malhamensis. Four additional species (identified by light microscopy as O. elegans Doflein, O. globosa Skuja, O. ovalis Dolfein, O. sociabilis Pringheim) have SSU rRNA sequences identical to P. malhamensis. Of these, only O. sociabilis has been transferred to Poterioochromonas. Thus, at least some species may be synonymous with others. Two clades of marine species are also known, one containing coastal species and the other containing open ocean species. A number of genera (some also polyphyletic) are interspersed amongst the Ochromonas species (e.g., Chrysolepidomonas, Chrysonephele, Chrysoxys, Cyclonexis, Dinobryon, Epipyxis, Uroglena, Uroglenopsis). The goal of this research (just beginning) is to establish a monophyletic Ochromonas, probably by assigning some species to other genera (existing or new). One major problem is that the type species, O. triangulata Vysotskii, hasn't been observed in over 100 years, and it is unclear which of several clades of Ochromonas contains the type. Results will be discussed.     

The unicellular freshwater cyanobacterium Synechococcus and mixotrophic flagellates: evidence for a functional association in an oligotrophic, subalpine lake

1. We applied Reynolds's approach to the study of phytoplankton ecology through functional associations of species to identify possible algal species, which associate with the freshwater cyanobacterium Synechococcus. Previously an association among Synechococcus spp. and small‐celled chlorophytes (association Z) has been recognised by evaluating phytoplankton associations according to functional criteria. 2. Biomass data for phytoplankton and picocyanobacteria from Lago Maggiore spanning more years were organised in a matrix and a cluster analysis was performed. The results showed four groups separated at a linkage distance of 0.20. Mixotrophic species which clustered with Synechococcus spp. were Ceratium hirundinella, Chrysochromulina parva, Cryptomonas erosa, Cryptomonas ovata, Dinobryon bavaricum, Dinobryon sociale, Rhodomonas minuta and Uroglena americana. The redundancy analysis (RDA) consolidated the association of Synechococcus with C. hirundinella and R. minuta showing greater probability of occurrence than random aggregates of species. 3. The association Synechococcus spp. –C. hirundinella also appeared from temporal variation of their biomass. In early summer both these species increased at the same time; later, the peak of C. hirundinella (potential predator) coincided with a minimum of Synechococcus spp. suggesting a possible predator‐prey interaction. This implied that phytoplankton assemblages which form a functional group cannot only have similar adaptations and requirements but can also exhibit trophic interactions. 4. We propose to enlarge the association Z and create an association Z_MX (where _MX stands for mixotrophs) which would include Synechococcus spp. and C. hirundinella as the most representative of the mixotrophic species found in the oligotrophic Lago Maggiore.     

中国弯颈霉新种及产环孢菌素的研究

对云南省迪庆藏族自治州产的冬虫夏草 Cordyceps sinensis(Berk.)Sacc.进行分离获一纯种,经培养鉴定确为弯颈霉属 Tolypocladium w.Gams 一新种,命名为中国弯颈霉 To-lypocladium sinense c.L.Li sp.nov.。它在几种琼脂培养基上生长形成瓶梗及瓶梗孢于,瓶梗基部呈球形或椭圆形膨大,瓶颈细长而弯曲,瓶梗孢子球形至卵形。其形态特征及生活习性与弯颈霉属其它种类显然不同,故定为一新种。它在蛋白胨葡萄糖培养液中,温度26℃,pH5.2,摇瓶振荡培养12天。发酵液用乙酸乙酯萃取,减压蒸馏,从每升发酵液中获50—80mg 环孢菌素粗品。对几种半知真菌显示了明显的拮抗作用。     

黄芪属与雀儿豆属(豆科)的定界问题——以米林黄芪为例谈谈对二属的认识

本文讨论了黄芪属与雀儿豆属的定界问题。作者以米林黄芪为例,分析了不同作者将其处理为不同属成员的原因。在研究了大量标本的基础上,进一步确认米林黄芪绝非雀儿豆属植物。同时,提出区别二属的关键特征。     

Biosystematic study of hexaploids Elymus tschimganicus and E. glaucissimus. II. Interspecific hybridization and genomic relationship.

To investigate genomic relationships of Elymus tschimganicus (Drobov) Tzvelev (2n = 6x = 42, S1S2Y genomes) and E. glaucissimus (M. Pop.) Tzvelev (2n = 6x = 42, S1S2Y genomes), interspecific hybridizations of the two target species were carried out with 27 other Elymus species containing the SH, SY, SYH, SYP, SYW, and SH1H2 genomes, respectively, collected from different geographic regions. Chromosome pairing behavior was analyzed at metaphase I in 27 hybrids representing 23 hybrid combinations, and overall genomic relationships of the two target species with the other Elymus taxa were estimated. The study concluded that (i) interspecific hybridization was principally easy to perform between the Elymus species, but no general pattern of crossability was obtained, and all hybrids were completely sterile, (ii) the two species have a similar meiotic pattern in their hybrids with the other Elymus species, and (iii) species containing the SY, SYP, and SYH genomes have a generally higher level of genomic homology to the target species than those possessing the SH genomes, and the South American hexaploid with the SH1H2 genomes has the lowest level of genomic homology to the two target taxa.     

Necines of alkaloids in Heliotropium species from Mexico and the U.S.A.

The qualitative and quantitative compositions of necines in plants of 20 Heliotropium species collected in Mexico and the U.S.A. and one species from Spain are reported. Trachelanthamidine, supinidine and retronecine were found in all species after hydrolysis of their alkaloids; lindelofidine was detected in most species, whereas heliotridine only in four. Trachelanthamidine, lindelofidine, and supinidine were dominant in four, two and one species, respectively; retronecine was dominant in 15 species, whereas heliotridine only in one. The dominant necine in H. ternatum was either retronecine or lindelofidine depending on the collection locality. Qualitative as well as quantitative differences depending on the collection locality were found in H. curassavicum. Plants from Oaxaca, Mexico, contained lindelofidine and a pyrrolizidine-diol as major necines, trachelanthamidine as minor, and traces of retronecine. Plants originating from two other localities contained trachelanthamidine (dominant), retronecine, and supinidine. The necine patterns found in the examined species differ significantly from those previously reported for 21 species mainly collected in Asia, the Middle East and Australia.     

Studies in African Cyperaceae 35. Kyllinga carinalaevis sp. nov. from west tropical Africa

A minute new species of Kyllinga, i.e. K. carinalaevis Lye & Mesterházy, from Benin in west tropical Africa is described. It is one of three or four annual species of the genus, and the characters separating it from two other annual species are given. The species is ephemeral and occurs in a vegetation type which belongs to a Nanocyperion association. The species is probably critically endangered as it was found in a single locality out of the numerous sites that have been investigated in Benin in recent years.     

Amphibian metallothionein. Induction in the frogs Rana japonica, R. nigromaculata and Rhacophorus schlegelii

Cadmium (Cd) was injected intramuscularly into three species of frogs to examine the number of isoforms in the induced metallothionein (MT). The induced MT was shown to consist of a single isoform in the three species of frogs Rana japonica, R. nigromaculata and Rhacophorus schlegelii. Native MT in the livers of R. japonica and R. nigromaculata was copper (Cu)-MT and the induced MT in the three species was Cd, Cu-MT, the Cd/Cu ratio in the induced MT being different from species to species. The effect of Cd injections on the concentrations of 10 elements in the livers and kidneys of the Rana species was not significant except for Cu.     

Bacteroides pectinophilus sp. nov. and Bacteroides galacturonicus sp. nov.: two pectinolytic bacteria from the human intestinal tract.

Studies on the physiological characteristics of two obligately anaerobic, rod-shaped bacteria from the human intestinal tract indicated that the organisms represented two previously undescribed species of Bacteroides, for which we propose the names Bacteroides pectinophilus (type strain, N3) and Bacteroides galacturonicus (type strain, N6). Both strains were pectinophilic; that is, they utilized as fermentable substrates for growth only pectin and a few related compounds. The two species differed significantly from each other in guanine plus cytosine content of the DNA, in substrate utilization patterns, and in other phenotypic characteristics. Both species deesterified pectin by means of an extracellular pectinesterase (EC 3.1.1.11) activity. Polygalacturonate (the main component of deesterified pectin) was depolymerized extracellularly with formation of unsaturated products by both species. The depolymerizing activity required Ca2+, functioned at a higher rate when polygalacturonate was the substrate as compared with pectin, and had an alkaline pH optimum. These data, as well as viscosity decrease studies and identification of products formed from polygalacturonate, indicated that the extracellular depolymerizing activity of either species was characteristic of an exopectate (exopolygalacturonate) lyase. The exopectate lyase activity had an unusual action pattern that resulted in terminal cleavage of unsaturated trigalacturonic acid units from polygalacturonate. An unsaturated trimer was the major product that accumulated in cell-free reaction mixtures, where it was not cleaved further. Growing cells of both Bacteroides species released the exopectate lyase into the external environment by processes that did not involve cell lysis to any significant extent.(ABSTRACT TRUNCATED AT 250 WORDS)