Algal Biology Research Articles

Printed Identification Key or Web-Based Identification Guide: An Effective Tool for Species Identification?

Species identification is often done with the aid of traditional dichotomous keys. This printed material is based on one’s decision between two alternatives, which is followed by another pair of alternatives until the final species name is reached. With the advent of internet technology, the use of an online database offers an updatable and accumulative approach to species identification. It can also be accessed anytime, and this is very useful for fast-changing groups of organisms. In this paper, we report the preference of sophomore Bachelor of Science (B.Sc.) in Microbiology students to two identification guides as a tool in taxonomy. We wish to test our hypothesis that today’s students will prefer to use web-based ID guides over printed dichotomous keys. We also describe how these printed dichotomous key and web-based ID guides were used by the students as one of their laboratory activities in the course Biology of Algae and Fungi.

High-efficiency homologous recombination in the oil-producing alga Nannochloropsis sp.

Algae have reemerged as potential next-generation feedstocks for biofuels, but strain improvement and progress in algal biology research have been limited by the lack of advanced molecular tools for most eukaryotic microalgae. Here we describe the development of an efficient transformation method for Nannochloropsis sp., a fast-growing, unicellular alga capable of accumulating large amounts of oil. Moreover, we provide additional evidence that Nannochloropsis is haploid, and we demonstrate that insertion of transformation constructs into the nuclear genome can occur by high-efficiency homologous recombination. As examples, we generated knockouts of the genes encoding nitrate reductase and nitrite reductase, resulting in strains that were unable to grow on nitrate and nitrate/nitrite, respectively. The application of homologous recombination in this industrially relevant alga has the potential to rapidly advance algal functional genomics and biotechnology.

RNA-mediated silencing in Algae: biological roles and tools for analysis of gene function.

Algae are a large group of aquatic, typically photosynthetic, eukaryotes that include species from very diverse phylogenetic lineages, from those similar to land plants to those related to protist parasites. The recent sequencing of several algal genomes has provided insights into the great complexity of these organisms. Genomic information has also emphasized our lack of knowledge of the functions of many predicted genes, as well as the gene regulatory mechanisms in algae. Core components of the machinery for RNA-mediated silencing show widespread distribution among algal lineages, but they also seem to have been lost entirely from several species with relatively small nuclear genomes. Complex sets of endogenous small RNAs, including candidate microRNAs and small interfering RNAs, have now been identified by high-throughput sequencing in green, red, and brown algae. However, the natural roles of RNA-mediated silencing in algal biology remain poorly understood. Limited evidence suggests that small RNAs may function, in different algae, in defense mechanisms against transposon mobilization, in responses to nutrient deprivation and, possibly, in the regulation of recently evolved developmental processes. From a practical perspective, RNA interference (RNAi) is becoming a promising tool for assessing gene function by sequence-specific knockdown. Transient gene silencing, triggered with exogenously synthesized nucleic acids, and/or stable gene repression, involving genome-integrated transgenes, have been achieved in green algae, diatoms, yellow-green algae, and euglenoids. The development of RNAi technology in conjunction with system level "omics" approaches may provide the tools needed to advance our understanding of algal physiological and metabolic processes.

The Ectocarpus genome sequence: insights into brown algal biology and the evolutionary diversity of the eukaryotes.

The Ectocarpus genome sequence: insights into brown algal biology and the evolutionary diversity of the eukaryotes.

The Ectocarpus genome and the independent evolution of multicellularity in brown algae.

Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae, closely related to the kelps (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic approaches to explore these and other aspects of brown algal biology further.

Algal cell biology and genomics

No abstract available

Pond Scum Genomics: The Genomes of Chlamydomonas and Ostreococcus

New insights into algal biology have recently emerged from the sequencing of the genomes of three unicellular green algae. Although green algae and plants share many of the same core metabolic pathways, analysis of the Chlamydomonas reinhardtii genome suggests retention of many genes from its

Inorganic carbon concentrating mechanisms in relation to the biology of algae.

Significant advances have recently been made in our understanding of the mechanism of inorganic carbon transport in algae and, especially, cyanobacteria with inorganic carbon concentrating mechanisms (CCMs). Furthermore, the role of CCMs in increasing the rate of photosynthesis in air-equilibrated solutions is also quite well understood. However, less often considered is how the presence (or absence) of a CCM relates to the biology of algae. This mini-review relates the occurrence of algal CCMs to phylogeny, life form, life history, and interactions with other organisms. While some patterns can be seen, the occurrence of CCMs in relation to the overall biology of the algae needs more investigation.

Intraclonal Variation in Macroalgae: Causes and Evolutionary Consequences

Recent studies documenting the presence of intraclonal variation in macroalgae indicate that there is considerable potential for selection in algae at levels other that among genets. As in other modular organisms, genetic changes that occur in algal somatic tissues may contribute to variation among sexual or asexual progeny. Several unusual aspects of algal reproduction and genetics increase the likelihood of intraclonal variation in contrast to the more familiar organisms that have strongly influenced much evolutionary theory. Somatic mutation, mitotic recombination, ploidy changes and rapid changes in genotype have all been documented in clonal lineages of macroalgae. The rarity of sexual processes in many algal populations suggests that this intraclonal genetic variation may contribute substantially to levels of genetic variation. Mechanisms that buffer the effects of somatic mutation in higher plants (e.g. stochastic meristems, diploidy) are often absent in algae, and thus intraclonal genetic variation has a high probability of being inherited and expressed in the phenotype of algal offspring. The presence of intraclonal variation, and some additional unusual aspects of algal biology, affect our concepts of the individual in biology.

Remote Sensing of Algal Bloom Dynamics

mhe last decade has seen rapid advances in two technologybased approaches to the study of algal biology: the use of remote sensing, which quantitatively measures light reflected from the surface of the earth, as a tool to study regional-scale aquatic ecosystem dynamics, and the refinement of techniques to identify and quantify algal pigments. Although research in remote sensing has been driven by the ongoing development of new sensors, advances in pigment analysis have essentially evolved from continual research in algal population dynamics, ecology, and physiology. Recent innovative results in both

REVIEWS

Book reviewed in this article Plant‐atmosphere Relationships. By J. Grace. Micromolecular Evolution, Systematics and Ecology. Ed by O. R. Gottlibb. Algal Biology: a Physiological Approach. By W. Marshall Darley.

Vertical zonation on rocky shores in the Severn estuary

Zonation of algae and invertebrates was examined on rocky shores in the Severn estuary from 1975 to 1978. These shores were characterised by an absence of macro-algae from MLWS and below. Some littoral algae showed reductions in abundance during the study. In particular, Ascophyllum nodosum and Fucus serratus almost disappeared from the mid shore at one site after 1976, and no significant recolonization had occurred by 1979. Animal species in general showed predictable and constant zonation patterns, but Littorina rudis, Patella vulgata and Elminius modestus all exhibited decreased upper vertical limits in the upper reaches of the estuary. Three approaches were taken to interpret the zonation patterns and their changes. (i) Exposure to wave action was estimated. Decreasing exposure levels may account for the decline in upper vertical limits of species in the upper estuary. (ii) A survey of silt, salinity and temperature was carried out over complete tidal cycles. High silt concentrations may partially explain the absence of macro-algae below MLWS. (iii) Preliminary experiments compared the effects of grazers in the estuary with those in fully marine conditions. These experiments point to some of the factors which are responsible for the lack of algal recolonization on the shore from which the dominant fucoids disappeared after 1976, but the situation is complex and involves algal reproductive biology as well as grazer activity.

The Biology of Algae and Other Verses

The Biology of Algae and Other Verses