The colonial rock-forming microfossils of the Bohemian Upper Proterozoic (Czechoslovakia), “Bohemipora Pragensis’ n.g., n.sp.

Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe). They resemble those described by Cayeux (1894) from the Upper Proterozoic (Brioverian) of Bretagne (France). It is shown, unlike the views of Cayeux and his followers (Deflandre, 1955, and Graindor 1957), that the observed structures did not belong to individuals but to colonies of filamentous prokaryotic organisms, most probably blue-green algae (Cyanophyta). These produced specific crystal-like mineral aggregation round each filament. Scanning microscope examination has revealed that the individual facets of these mineral crystals were perforated by the openings through which the thread-like bodies of these primitive organisms protruded. It is shown that these microorganisms were attached to the cells of other, bigger microorganisms and enveloped them. Some of these substrate organisms might have been eukaryotic algae. The thecae gradually accumulated around the cells of these carrier organisms and after death the colonies disintegrated to constitute the main component of the sediment. The microfossils described are just a major component of a complicated fossil assemblage comprising coccoid and filamentous blue-green algae and bacteria. There are indications that several eukaryotic species might also have been present.The following new taxa are described:Thecophytales, new order,Cayeuxidae (Graindor) family emend.,Bohemipora n. gen.,B. pragensis, n. sp.     

Inhibition of lysosomal fusion with symbiont-containing vacuoles in Paramecium bursaria

Paramecium bursaria harbors several hundred intracellular Chlorella symbionts which remain undigested at the same time that the host cell phagocytizes and digests other organisms. Using electron microscopy and thorotrast labelling, we have shown that secondary lysosomes fuse with food vacuoles, but do not fuse with vacuoles containing symbiotic algae. From these and other data we suggest that the symbiotic algae alter the membrane of the vacuole which surrounds them, thus inhibiting fusion with secondary lysosomes.     

RNA Isolation method for polysaccharide rich algae: agar producing <Emphasis Type="Italic">Gracilaria tenuistipitata</Emphasis> (Rhodophyta)

RNA isolation is essential to study gene expression at the molecular level. However, RNA isolation is difficult in organisms (plants and algae) that contain large amounts of polysaccharides, which co-precipitate with RNA. Currently, there is no commercial kit available, specifically for the isolation of high-quality RNA from these organisms. Furthermore, because of the large amounts of polysaccharides, the common protocols for RNA isolation usually result in poor yields when applied to algae. Here we describe a simple method for RNA isolation from the marine red macroalga Gracilaria tenuistipitata var. liui Zhang et Xia (Rhodophyta), which can be applied to other plants and algae.     

Algal nitrogen fixation in the tropics

Summary a)Nitrogen fixation in rice fields. Nitrogen-fixing blue-green algae grow abundantly in tropical regions and are particularly common in paddy fields. Their possible role in the nitrogen accumulation of soil has been studied. The most vigorous nitrogen-fixing blue-green algae have been assessed for use as green manure in rice fields and favorable effects have been reported in India and other countries. b)Nitrogen fixation by algae in water. The planktonic blue-green algae occur abundantly at certain time of the year in sea water and lake water, and some of them are known to be nitrogen fixers. Certain Japanese species of blue-green algae can withstand high temperatures including ten nitrogen-fixing species from hot-spring waters. c)Nitrogen fixation by symbiotic blue-green algae. Certain species of blue-green algae form associations with other organisms such as fungi, liverworts, ferns and seed plants. The relationship between these two organisms is on one occasion commensal and on others symbiotic. Certain symbiotic blue-green algae are provided with the ability to fix the atmospheric nitrogen.     

Biologically active oxylipins from seaweeds

Our previous research has shown that many red algae metabolize polyunsaturated fatty acids to oxidized products resembling the eicosanoid hormones from mammals. We have extended these studies to members of the Phaeophyceae and Chlorophyta and find they also possess similar biosynthetic pathways. From several we have identified novel prostaglandin-like substances. Studies of the molecular mechanisms by which some of these marine oxylipins are formed have revealed that novel oxidative reactions are utilized. Understanding of these biosynthetic pathways in detail has allowed their utilization to produce research biochemicals of high value, such as 12S-hydroperoxyeicosatetraenoic acid (12S-HPETE). Because of their biological properties, seaweed-derived oxylipins have potential utility as pharmaceuticals and research biochemicals.     

Variations in morphology and PSII photosynthetic capabilities during the early development of tetraspores of <Emphasis Type="Italic">Gracilaria vermiculophylla </Emphasis>(Ohmi) Papenfuss (Gracilariales,Rhodophyta)

Background  

Red algae are primitive photosynthetic eukaryotes, whose spores are ideal subjects for studies of photosynthesis and development. Although the development of red alga spores has received considerable research attention, few studies have focused on the detailed morphological and photosynthetic changes that occur during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi) Papenfuss (Gracilariales, Rhodophyta). Herein, we documented these changes in this species of red algae.     

GENOMIC INSIGHTS INTO EVOLUTIONARY RELATIONSHIPS AMONG HETEROKONT LINEAGES EMPHASIZING THE PHAEOPHYCEAE1

Heterokonts comprise a large and diverse group of organisms unified by the heterokont biflagellate condition. Monophyly of many of these lineages is well established, but evolutionary relationships among the various lineages remain elusive. Among these lineages, the brown algae (Phaeophyceae) are a monophyletic, taxonomically diverse, and ecologically critical group common to marine environments. Despite their biological and scientific importance, consensus regarding brown algal phylogeny and taxonomic relationships is missing. Our long‐term research goal is to produce a well‐resolved taxon‐rich phylogeny of the class to assess evolutionary patterns and taxonomic relationships among brown algal lineages and their relationship to other closely related heterokont groups. To accomplish this goal and augment existing loci for phaeophycean‐wide systematic studies, we generated expressed sequence tags (ESTs) from several major brown algal lineages and from the heterokont lineage representing the closest sister group to brown algae. To date, we have successfully constructed cDNA libraries for two lineages (Choristocarpus tenellus Zanardini and Schizocladia ischiensis E. C. Henry, Okuda et H. Kawai) and in the library test phase obtained up to 1,600 ESTs per organism. Annotation results showed a gene discovery rate of 45%–50% for each library revealing 500–700 unique genes from each organism. We have identified several potential genes for phylogenetic inference and used these loci for preliminary molecular clock analyses. Our molecular clock analysis suggests that the basal divergence in brown algae occurred around the time of the pennate‐centric diatom divergence. Here we report this analysis and other uses of ESTs in brown algal phylogenomics and the utility of these data for resolving the phylogeny of this group.     

Nitrogenase Activity in Relation to Intracellular Organisms in Sphagnum Mosses

Electron microscopic studies of Sphagnum lindbergii (Schimp.) and S. riparium (Ångstr.) have revealed the presence of intracellular organisms such as blue-green algae, green algae, bacteria and fungi. Nitrogenase activities of these Sphagnum mosses were found to be related mainly to the presence of intracellular Nostoc filaments. The appearance of nitrogen-fixing blue-green algae within bryophytes is thus not restricted to liverworts. The association is likely to be of ecological importance as it seems to occur in very acid habitats generally lacking blue-green algae. Possible interrelations between the moss, the blue-green algae and different types of bacteria are discussed.     

Ediacaran developmental biology

Rocks of the Ediacaran System (635–541 Ma) preserve fossil evidence of some of the earliest complex macroscopic organisms, many of which have been interpreted as animals. However, the unusual morphologies of some of these organisms have made it difficult to resolve their biological relationships to modern metazoan groups. Alternative competing phylogenetic interpretations have been proposed for Ediacaran taxa, including algae, fungi, lichens, rhizoid protists, and even an extinct higher‐order group (Vendobionta). If a metazoan affinity can be demonstrated for these organisms, as advocated by many researchers, they could prove informative in debates concerning the evolution of the metazoan body axis, the making and breaking of axial symmetries, and the appearance of a metameric body plan. Attempts to decipher members of the enigmatic Ediacaran macrobiota have largely involved study of morphology: comparative analysis of their developmental phases has received little attention. Here we present what is known of ontogeny across the three iconic Ediacaran taxa Charnia masoni, Dickinsonia costata and Pteridinium simplex, together with new ontogenetic data and insights. We use these data and interpretations to re‐evaluate the phylogenetic position of the broader Ediacaran morphogroups to which these taxa are considered to belong (rangeomorphs, dickinsoniomorphs and erniettomorphs). We conclude, based on the available evidence, that the affinities of the rangeomorphs and the dickinsoniomorphs lie within Metazoa.     

Algal Visual Proteins: An Evolutionary Point of View

Light is a major environmental signal controlling most life processes; hence, light perception is absolutely necessary for organisms that rely on light. In order to detect light, organisms evolved photoreceptors, which are found throughout all the kingdoms with enormous structural variations. Yet, the nature of the photoreceptor pigment is highly conserved, probably for the stringent conditions it has to satisfy. In prokaryotes such as the archaebacteria Halobacterium halobium and Natronobacterium pharaonis, the cell membrane provides an extensive surface on which membrane-spanning light-sensitive proteins are spread with a fixed bidimensional orientation for maximal effectiveness in photon capturing. In unicellular algae, a similar pigment-containing patch probably exists in the Chlorophyta, whereas more complex photoreceptors, such as three-dimensional crystals of membrane-spanning proteins, for example, may occur in the Euglenophyta and Chrysophyta. The superfamily of the seven membrane-spanning domains proteins is responsible for reception roles (chemoreception, mechanoreception, photoreception), and one of these proteins (i.e., rhodopsin) is responsible for photoreception and vision. Therefore, we could reasonably expect it or its homologues to be found in any group of living organisms that manifests photobehavior. Indications of the presence of rhodopsin in all the domains are emerging; therefore, we consider experimental evidence that bears out this theory on organisms other than algae and then provide a more exhaustive examination of the visual pigments present in algal phyla.     

An update on carotenoid biosynthesis in algae: phylogenetic evidence for the existence of two classes of phytoene synthase

Carotenoids play crucial roles in structure and function of the photosynthetic apparatus of bacteria, algae, and higher plants. The entry-step reaction to carotenoid biosynthesis is catalyzed by the phytoene synthase (PSY), which is structurally and functionally related in all organisms. A comparative genomic analysis regarding the PSY revealed that the green algae Ostreococcus and Micromonas possess two orthologous copies of the PSY genes, indicating an ancient gene duplication event that produced two classes of PSY in algae. However, some other green algae (Chlamydomonas reinhardtii, Chlorella vulgaris, and Volvox carteri), red algae (Cyanidioschyzon merolae), diatoms (Thalassiosira pseudonana and Phaeodactylum tricornutum), and higher plants retained only one class of the PSY gene whereas the other gene copy was lost in these species. Further, similar to the situation in higher plants recent gene duplications of PSY have occurred for example in the green alga Dunaliella salina/bardawil. As members of the PSY gene families in some higher plants are differentially regulated during development or stress, the discovery of two classes of PSY gene families in some algae suggests that carotenoid biosynthesis in these algae is differentially regulated in response to development and environmental stress as well.     

Salt-Regulated Mannitol Metabolism in Algae

Mannitol, one of the most widely occurring sugar alcohol compounds, is found in bacteria, fungi, algae, and plants. In these organisms the compound acts as a compatible solute and has multiple functions, including osmoregulation, storage, and regeneration of reducing power, and scavenging of active oxygen species. Because of the diverse functions of mannitol, introducing the ability to accumulate it has been a hallmark of attempts to generate highly salt-tolerant transgenic plants. However, transgenic plants have not yet improved significantly in their salt tolerance. Recently, we purified and characterized 2 enzymes that biosynthesize mannitol, mannitol-1-phosphate dehydrogenase (M1PDH) and mannitol-1-phosphate-specific phosphatase, from the marine red alga Caloglossa continua, which grows in estuarine areas where tide levels fluctuate frequently. The activation of Caloglossa M1PDH is unique in that it is regulated by salt concentration at enzyme level. In this review we focus on the metabolism of mannitol, mainly in marine photosynthetic organisms, and suggest how this might be applied to producing salt-tolerant transgenic plants.     

Effects of light, dissolved organic carbon, and inorganic nutrients [2pt] on the relationship between algae and heterotrophic bacteria in stream periphyton

Depending on the chemical and physical environment, algae and heterotrophic bacteria in stream periphyton communities likely engage in both positive and negative interactions. We tested the hypothesis that bacteria are more closely associated with algae when allochthonous sources of labile DOC are low and algae are not light limited. Secondly, we tested the hypothesis that, under extremely oligotrophic conditions, bacteria will out-compete algae for inorganic nutrients if their carbon requirements are met by allochthonous sources. Experiments were carried out using in situ light manipulations and nutrient diffusing substrates (releasing inorganic nutrients and /or glucose) in Harts Run, an oligotrophic stream located in north central Kentucky. Although we found that both algal and bacterial biomass were higher under ambient light, bacteria did not respond to glucose in the dark. This may indicate that bacteria were associated with algae not as a carbon source, but as a substrate for colonization. In the nutrient × glucose manipulation, we found that bacteria were co-limited by inorganic nutrients. There was no evidence of algae being negatively affected by competition with bacteria for nitrogen and phosphorus. Although low temperatures might have played a role in preventing inorganic nutrient competition between these two groups of organisms, the results of both experiments may indicate that the quantitative link between periphytic bacteria and algae is stronger under oligotrophic conditions.     

Localization and evolution of septins in algae

Septins are a group of GTP‐binding proteins that are multi‐functional, with a well‐known role in cytokinesis in animals and fungi. Although the functions of septins have been thoroughly studied in opisthokonts (fungi and animals), the function and evolution of plant/algal septins are not as well characterized. Here we describe septin localization and expression in the green algae Nannochloris bacillaris and Marvania geminata. The present data suggest that septins localize at the division site when cytokinesis occurs. In addition, we show that septin homologs may be found only in green algae, but not in other major plant lineages, such as land plants, red algae and glaucophytes. We also found other septin homolog‐possessing organisms among the diatoms, Rhizaria and cryptomonad/haptophyte lineages. Our study reveals the potential role of algal septins in cytokinesis and/or cell elongation, and confirms that septin genes appear to have been lost in the Plantae lineage, except in some green algae.     

PYROLYSIS-GAS-LIQUID CHROMATOGRAPHIC ANALYSIS OF CHLOROPHYCEAN AND RHODOPHYCEAN ALGAE1

Eight chlorococcalean algae and 5 rhodophycean algae have been grown in axenic cultures. These organisms have been “fingerprinted” using a pyrolysis-gas-liquid chromatographic analysis. Each alga has a distinctive pyrogram which characterizes it both quantitatively and qualitatively. The pyrograms are given and the significance for possible future uses of this technique in developmental, evolutionary, and systematic studies with algae is discussed.     

PROPOSAL OF ECTOCARPUS SILICULOSUS (ECTOCARPALES,PHAEOPHYCEAE) AS A MODEL ORGANISM FOR BROWN ALGAL GENETICS AND GENOMICS1,2

The emergence of model organisms that permit the application of a powerful combination of genomic and genetic approaches has been a major factor underlying the advances that have been made in the past decade in dissecting the molecular basis of a wide range of biological processes. However, the phylogenetic distance separating marine macroalgae from these model organisms, which are mostly from the animal, fungi, and higher plant lineages, limits the latters' applicability to problems specific to macroalgal biology. There is therefore a pressing need to develop similar models for the macroalgae. Here we describe a survey of potential model brown algae in which particular attention was paid to characteristics associated with a strong potential for genomic and genetic analysis, such as a small nuclear genome size, sexuality, and a short life cycle. Flow cytometry of nuclei isolated from zoids showed that species from the Ectocarpales possess smaller haploid genomes (127–290 Mbp) than current models among the Laminariales (580–720 Mbp) and Fucales (1095–1271 Mbp). Species of the Ectocarpales may complete their life histories in as little as 6 weeks in laboratory culture and are amenable to genetic analyses. Based on this study, we propose Ectocarpus siliculosus (Dillwyn) Lyngbye as an optimal choice for a general model organism for the molecular genetics of the brown algae.     

Microorganism lipid droplets and biofuel development

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from CO2 via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech ‘factories’ to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development. [BMB Reports 2013; 46(12): 575-581]     

Chlorella variabilis and Micractinium reisseri sp. nov. (Chlorellaceae,Trebouxiophyceae): Redescription of the endosymbiotic green algae of Paramecium bursaria (Peniculia,Oligohymenophorea) in the 120th year

Symbiotic algae of the ciliate Paramecium bursaria (Ehrenberg) Focker are key species in the fields of virology and molecular evolutionary biology as well as in the biology of symbiotic relationships. These symbiotic algae were once identified as Zoochlorella conductrix Brandt by the Dutch microbiologist, Beijerinck 120 years ago. However, after many twists and turns, the algae are today treated as nameless organisms. Recent molecular analyses have revealed several different algal partners depending on P. bursaria strains, but nearly all P. bursaria contains a symbiont belonging to either the so‐called ‘American’ or ‘European’ group. The absence of proper names for these algae is beginning to provoke ill effects in the above‐mentioned study areas. In the present study, we confirmed the genetic autonomy of the ‘American’ and ‘European’ groups and described the symbionts as Chlorella variabilis Shihira et Krauss and Micractinium reisseri Hoshina, Iwataki et Imamura sp. nov., respectively (Chlorellaceae, Trebouxiophyceae).     

Occurrence and phylogenetic significance of cytokinesis-related callose in green algae, bryophytes, ferns and seed plants

 In order to investigate the occurrence of callose in dividing cells, we cultivated a selection of 30 organisms (the prokaryotic cyanobacterium Anabaena and eukaryotic green algae, bryophytes, ferns and seed plants) under defined conditions in the laboratory. Samples from these photoautotrophs, which are members of the evolutionary 'green lineage' leading from freshwater algae to land plants, were analysed by fluorescence microscopy. The β-1,3-glucan callose was identified by its staining properties with aniline blue and sirofluor. With the exception of the prokaryotic cyanobacterium, all of the eukaryotic organisms studied were capable of producing wound-induced callose. No callose was detected during cytokinesis of dividing cells of unicellular green algae (and Anabaena). However, in all of the multicellular green algae and land plants (embryophytes) investigated, callose was identified in newly made septae by an intense yellow fluorescence. The formation of wound callose was never detected in cells with callose in the newly formed septae. Additional experiments verified that no fixation-induced artefacts occurred. Our results show that callose is a regular component of developing septae in juvenile cells during cytokinesis in multicellular green algae and embryophytes. The implications of our results with respect to the evolutionary relationships between extant charophytes and land plants are discussed. Received: 15 September 2000 / Revision received: 23 October 2000 / Accepted: 23 October 2000