Evolution of Protein Molecules

Amongst the diverse and potent biological activities of free fatty acids (FFAs) is the ability to kill or inhibit the growth of bacteria. The antibacterial properties of FFAs are used by many organisms to defend against parasitic or pathogenic bacteria. Whilst their antibacterial mode of action is still poorly understood, the prime target of FFA action is the cell membrane, where FFAs disrupt the electron transport chain and oxidative phosphorylation. Besides interfering with cellular energy production, FFA action may also result from the inhibition of enzyme activity, impairment of nutrient uptake, generation of peroxidation and auto-oxidation degradation products or direct lysis of bacterial cells. Their broad spectrum of activity, non-specific mode of action and safety makes them attractive as antibacterial agents for various applications in medicine, agriculture and food preservation, especially where the use of conventional antibiotics is undesirable or prohibited. Moreover, the evolution of inducible FFA-resistant phenotypes is less problematic than with conventional antibiotics. The potential for commercial or biomedical exploitation of antibacterial FFAs, especially for those from natural sources, is discussed.

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Antibacterial free fatty acids: activities, mechanisms of action and biotechnological potential

Multiple interacting physical, chemical, and biotic factors, in proper combination, lead to the development and persistence of nuisance algal blooms. Upon examining combinations of environmental conditions most likely to elicit nuisance blooms, commonalities and analog situations become more apparent among coastal marine (dinoflagellate-dominated), estuarine (dinoflagellate- and cyanobacteria-dominated), and freshwater (cyanobacteria-dominated) ecosystems. A combination of the following hydrological, chemical, and biotic factors will most likely lead to bloom-sensitive waters: a horizontally distinct water mass; a vertically stratified water column; warm weather conditions, as typified by dry monsoon tropical climates and summer seasons in temperate zones; high incident photosynthetically active radiation (PAR); enhanced allochthonous organic matter loading (both as DOC and POC); enhanced allochthonous inorganic nutrient loading (nitrogen and/or phosphorus); adequate availability of essential metals, supplied by terrigenous inputs or upwelling; underlying sediments physically and nutritionally suitable as “seed beds” for resting cysts and akinetes; algal-bacterial synergism, which exhibits positive impacts on phycosphere nutrient cycling; algal-micrograzer (protists and rotifers) synergism, which also enhances nutrient cycling without consumption of filamentous and colonial nuisance taxa; and selective (for non-nuisance taxa) activities of macrograzers (crustacean zooplankton, larval fish).

Nuisance bloom taxa share numerous additional physiological and ecological characteristics, including limited heterotrophic capabilities, high degrees of motility, and toxicity. Given such a set of commonalities, it would appear useful and timely to identify and address generally applicable criteria for deeming a water body “bloom sensitive” and to incorporate such criteria into the design of water quality management strategies applicable to both coastal marine and freshwater habitats.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1988.33.4part2.0823

Nuisance phytoplankton blooms in coastal, estuarine, and inland waters1

Over the past two decades, molecular phylogenetic data have allowed evaluations of hypotheses on the evolution of green algae based on vegetative morphological and ultrastructural characters. Higher taxa are now generally recognized on the basis of ultrastructural characters. Molecular analyses have mostly employed primarily nuclear small subunit rDNA (18S) and plastid rbcL data, as well as data on intron gain, complete genome sequencing, and mitochondrial sequences. Molecular-based revisions of classification at nearly all levels have occurred, from dismemberment of long-established genera and families into multiple classes, to the circumscription of two major lineages within the green algae. One lineage, the chlorophyte algae or Chlorophyta sensu stricto, comprises most of what are commonly called green algae and includes most members of the grade of putatively ancestral scaly flagellates in Prasinophyceae plus members of Ulvophyceae, Trebouxiophyceae, and Chlorophyceae. The other lineage (charophyte algae and embryophyte land plants), comprises at least five monophyletic groups of green algae, plus embryophytes. A recent multigene analysis corroborates a close relationship between Mesostigma (formerly in the Prasinophyceae) and the charophyte algae, although sequence data of the Mesostigma mitochondrial genome analysis places the genus as sister to charophyte and chlorophyte algae. These studies also support Charales as sister to land plants. The reorganization of taxa stimulated by molecular analyses is expected to continue as more data accumulate and new taxa and habitats are sampled. Twenty years ago, a relatively slim volume with chapters by leading chlorophycologists celebrated the systematics of green algae (Irvine and John, 1984), a field that was undergoing rapid and fascinating changes, both in content and theory. ‘‘The present period may be termed the ‘Age of Ultrastructure’ in green algal systematics,’’ wrote Frank Round (1984, p. 7) in the introductory chapter, which summarized the history and state of the art. Round (1984) argued that light microscopy had laid the foundation in the preceding two centuries, but that the foundation was largely descriptive—alpha taxonomy in the most restricted sense. Ultrastructure, he asserted, had enlarged and presumably would continue to expand our horizons to unify systematics of green algae and overcome the fragmented alpha taxonomy that had dominated the field. Little did Round know that this golden age of green algal systematics was about to go platinum. Molecular systematics, in concert with a rigorous theoretical approach to data analysis and hypothesis testing (Theriot, 1992; Swofford et al., 1996), would at first complement and then transform the age of ultrastructure and usher in the ‘‘Age of Molecules.’’ In this article, we review the major advances in green algal systematics in the past 20 years, with a focus on well-supported, monophyletic taxa and the larger picture of phylogeny and evolution of green algae. We will review the types of data that have fueled these advances. As will become obvious, this perspective entails discussion of some embryophytes as well as their closest green algal relatives. In addition, we will point

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Green algae and the origin of land plants

Oxidative stress generation by microcystins in aquatic animals: why and how.

Heterosigma akashiwo and its related algae were re-examined by light and electron microscopes using cultured materials including type cultures of bothH. akashiwo andH. inlandica as well as specimens referred to asOlisthodiscus luteus maintained in CCAP and UTEX. All the strains examined were similar to one another in appearance and ultrastructural features. They can be accommodated in a single species,H. akashiwo, which has been invalidly published.

Morphology, ultrastructure and taxonomy of the raphidophycean alga Heterosigma akashiwo

An allelopathic fatty acid from the brown alga Cladosiphon okamuranus

Nine taxa of Nitella (Charales, Charophyceae) from Japan, including five Japanese or east Asian endemics, were examined to improve understanding of their taxonomic status. The approaches used were light and scanning electron microscopy (SEM) of the oospores and sequencing of the gene (rbcL) encoding the large subunit of Rubisco. The species delineated were N. pulchella (= N. dualis f. pulchella), N. furcala, N. inversa (= N. furcata f. inversa), N. gracilens (= N. furcata f. gracilens), N. pseudoflabellata, N. hyalina, N. spieiformis (= N. gracilis f. spiciformis), N. moriokae (= N. rigida f. moriokae) and N. axillaris (= N. translucens var. axillaris). SEM observations showed that the oospore morphology of four taxa – N. inversa, N. gracilens, N. spiciformis and N. axillaris – was distinctly different from that of the species (N. furcata, N. furcata, N. gracilis and N. translucens, respectively) to which R.D. Wood assigned them as infraspecific taxa. Furthermore, the rbcL data showed that N. gra...

Taxonomic re-examination of Nitella (Charales, Charophyceae) from Japan, based on microscopical studies of oospore wall ornamentation and rbcL gene sequences

Abstract Six taxa of Nitella (Charales, Charophyceae), collected from Asia, were investigated using light and scanning electron microscopy (SEM) for the oospores, and sequencing of the gene encoding the large subunit of Rubisco (rbcL), in order to improve our understanding of their taxonomic status. Our SEM observations demonstrated that the oospore morphology of four taxa belonging to the subgenus Tieffa1lenia [N. megaspora (J. Groves) Sakayama, comb. nov. (= N. pseudoflabellata f. megaspora), N. tumulosa (= N. furcata f. tumulosa), N. gracillima (= N. gracilis f. gracillima) and N. axilliformis (= N. translucens f. axilliformis)] is distinctly different from that of the species N. pseudoflabellata, N. furcata, N. gracilis and N. translucens, respectively, to which R.D. Wood assigned them as infraspecific taxa. Our rbcL sequence data showed that N. megaspora is separated phylogenetically from N. pseudoflabellata, N. tumulosa from N. furcata and N. axilliformis from N. translucens. In addition, to re-examine the taxonomic system of Nitella proposed by R.D. Wood, who treated oospore wall ornamentations as diagnostic at the infraspecific level, we carried out molecular phylogenetic analyses using the combined sequence data set for the gene encoding the beta subunit of ATP synthase (atpB) and the rbcL gene of these six species, as well as eleven species of Nitella studied previously. The combined sequence data resolved fiverobust clades within the subgenus Tieffallenia that were characterized by differences in oospore wall ornamentation. However, the species and sectional diagnoses of R.D. Wood, such as the form and cell number of dactyls in vegetative thalli, were variable within the clades. Therefore, R.D. Wood's taxonomic system appears unnatural, at least within the subgenus Tieffallenia.

Taxonomic re-examination of six species of Nitella (Charales, Charophyceae)

A flattened discoid flagellate collected from the Seto Inland Sea, Japan, has been examined by light and electron microscopy. This alga agrees well withClisthodiscus luteus Carter. It has two heterodynamic flagella emerging from a furrow on the upward side of the cell that contains six to 13 yellow-green parietal chloroplasts. It does not rotate but smoothly glide while swimming. The cell has a thin periplast lying between the plasmalemma and chloroplasts. Neither lipid bodies nor mucocysts are seen in the periplast. The pyrenoid matrix being free from thylakoids is penetrated by several cytoplasmic canals from various directions. There are no vesicles of periplastidal network in the narrow space between chloroplast envelope and chloroplast ER.

Yoshiaki Hara

Papers

Morphology, ultrastructure and taxonomy of the raphidophycean alga Heterosigma akashiwo

An allelopathic fatty acid from the brown alga Cladosiphon okamuranus

Taxonomic re-examination of Nitella (Charales, Charophyceae) from Japan, based on microscopical studies of oospore wall ornamentation and rbcL gene sequences

Taxonomic re-examination of six species of Nitella (Charales, Charophyceae)

Morphology and Ultrastructure of Olisthodiscus luteus(Raphidophyceae)with Special Reference to the Taxonomy