I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Methods in Enzymology.

Following scrutiny of present biofuels, algae are seriously considered as feedstocks for next-generation biofuels production. Their high productivity and the associated high lipid yields make them attractive options. In this review, we analyse a number aspects of large-scale lipid and overall algal biomass production from a biochemical and energetic standpoint. We illustrate that the maximum conversion efficiency of total solar energy into primary photosynthetic organic products falls in the region of 10%. Biomass biochemical composition further conditions this yield: 30 and 50% of the primary product mass is lost on producing cell protein and lipid. Obtained yields are one third to one tenth of the theoretical ones. Wasted energy from captured photons is a major loss term and a major challenge in maximising mass algal production. Using irradiance data and kinetic parameters derived from reported field studies, we produce a simple model of algal biomass production and its variation with latitude and lipid content. An economic analysis of algal biomass production considers a number of scenarios and the effect of changing individual parameters. Our main conclusions are that: (i) the biochemical composition of the biomass influences the economics, in particular, increased lipid content reduces other valuable compounds in the biomass; (ii) the “biofuel only” option is unlikely to be economically viable; and (iii) among the hardest problems in assessing the economics are the cost of the CO2 supply and uncertain nature of downstream processing. We conclude by considering the pressing research and development needs.

Microalgae as biodiesel & biomass feedstocks: Review & analysis of the biochemistry, energetics & economics

▪ Abstract Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that was first identified in 1978 as a quantitatively minor component of suspension-cultured sycamore cell walls. Subsequent studies have shown that RG-II is present in the primary walls of angiosperms, gymnosperms, lycophytes, and pteridophytes and that its glycosyl sequence is conserved in all vascular plants examined to date. This is remarkable because RG-II is composed of at least 12 different glycosyl residues linked together by more than 20 different glycosidic linkages. However, only a few of the genes and proteins required for RG-II biosynthesis have been identified. The demonstration that RG-II exists in primary walls as a dimer that is covalently cross-linked by a borate diester was a major advance in our understanding of the structure and function of this pectic polysaccharide. Dimer formation results in the cross-linking of the two homogalacturonan chains upon which the RG-II molecules are constructed and ...

RHAMNOGALACTURONAN II: Structure and Function of a Borate Cross-Linked Cell Wall Pectic Polysaccharide

The green lineage (Viridiplantae) comprises the green algae and their descendants the land plants, and is one of the major groups of oxygenic photosynthetic eukaryotes. Current hypotheses posit the early divergence of two discrete clades from an ancestral green flagellate. One clade, the Chlorophyta, comprises the early diverging prasinophytes, which gave rise to the core chlorophytes. The other clade, the Streptophyta, includes the charophyte green algae from which the land plants evolved. Multi-marker and genome scale phylogenetic studies have greatly improved our understanding of broad-scale relationships of the green lineage, yet many questions persist, including the branching orders of the prasinophyte lineages, the relationships among core chlorophyte clades (Chlorodendrophyceae, Ulvophyceae, Trebouxiophyceae and Chlorophyceae), and the relationships among the streptophytes. Current phylogenetic hypotheses provide an evolutionary framework for molecular evolutionary studies and comparative genomics. This review summarizes our current understanding of organelle genome evolution in the green algae, genomic insights into the ecology of oceanic picoplanktonic prasinophytes, molecular mechanisms underlying the evolution of complexity in volvocine green algae, and the evolution of genetic codes and the translational apparatus in green seaweeds. Finally, we discuss molecular evolution in the streptophyte lineage, emphasizing the genetic facilitation of land plant origins.

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Phylogeny and Molecular Evolution of the Green Algae

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

I. I n t r o d u c t o r y Review of Some Recen t Comparat ive Cytological Studies in the Green Algae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 II. A Classification of the Green Algae Based on Cytological Characterist ics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 III. Problems and Impl ica t ions of a Cytological Classification . . . . . . . . . 119 IV. The Origin of Land Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 V. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 VI. Zusammenfassung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 VII. References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Comparative cytology, evolution and classification of the green algae with some consideration of the origin of other organisms with chlorophylls A and B

Structural evolution in the flagellated cells of green algae and land plants.

SUMMARY

The results of previous research and a present survey of some of the cytological characteristics of 18 additional genera and 34 additional species are presented and discussed from the viewpoint of phylogenetic and taxonomic significance. A preliminary attempt is made to place these, algae, in 4 orders on the basis of comparative cytology, and in particular on the basis of variation in mitosis and cytokinesis and the distribution of plasmodesmata. Consideration is given to the evolution of the phragmoplast and to the hypothesis that the Chaetophorales are related to the ancestry of land plants.

Mitosis, cytokinesis, the distribution of plasmodesmata, and other cytological characteristics in the ulotrichales, ulvales, and chaetophorales: phylogenetic and taxonomic considerations1

SUMMARY

Mitosis, cytokinesis, and cellular organization during interphase are described. Interphase cells possess a single microbody-like organdie which occurs between, and is appressed to, the chloroplast and nucleus. The microbody-like organelle divides during mitosis and. the division of the chloroplast. Anaphase is unusual in that chromosome-to-spindle pole distance remains constant even though the 2 groups of chromosomes become widely separated. When anaphase is half completed, a vacuole forms in the interzonal region and appears to be involved in further separation of the chromosomes. Vacuolar development is also involved with events of early interphase. The cytology of K. flaccidum is compared to those of Ulothrix fimbriata and Stigeoclonium helveticum. The comparison, does not support the present classification of the 3 species, and indicates the value of comparative fine structural studies in the classification of ulotrichalean algae.

Cellular organization, mitosis, and cytokinesis in the ulotrichalean alga, klebsormidium1,2,3

The origin of a cell wall was an event of fundamental importance in the evolution of plants. In the green algae, cell walls apparently had independent origins in at least three lines of evolution. In this paper, the components of the cell wall were determined and compared in four filamentous green algae representing the charophycean, chlorophycean and ulvacean evolutionary lines. The walls of all four have hydroxyproline-containing proteins which separate into five or six bands upon SDS gel electrophoresis. Variation does exist, with the charophyte possessing fast moving electrophoretic bands and high hydroxyproline content, the chlorophytes having intermediate movement of bands and lower hydroxyproline content, and the ulvacean representative possessing slow moving bands and a very low, if not questionable, hydroxyproline and saccharide content. Qualitative and quantitative estimates of wall proteins and sugars have been determined and compared. A hypothetical scheme of cell wall evolution based on these data, those of previous analyses, and recent phylogenetic schemes is presented. Although sound conclusions cannot be made until more information is available, the scheme might help to emphasize the areas most in need of additional research.

Kenneth D. Stewart

Papers

Comparative cytology, evolution and classification of the green algae with some consideration of the origin of other organisms with chlorophylls A and B

Structural evolution in the flagellated cells of green algae and land plants.

Mitosis, cytokinesis, the distribution of plasmodesmata, and other cytological characteristics in the ulotrichales, ulvales, and chaetophorales: phylogenetic and taxonomic considerations1

Cellular organization, mitosis, and cytokinesis in the ulotrichalean alga, klebsormidium1,2,3

The comparative aspects of cell wall chemistry in the green algae ( chlorophyta )