Assessment of predation by the West Coast rock lobster (Jasus lalandii) : relationships among growth rate, diet and benthic community composition, with implications for the survival of juvenile abalone (Haliotis midae)

Bibliography: leaves 195-213.This thesis focused on two aspects of predation by the West Coast rock lobster (Jasus lalandii). These were (1) the problem of slow growth currently observed in adult male rock lobsters and the putative link between growth rate and food availability, and (2) the influence of rock-lobster predation on the benthos, but more specifically on sea urchins and juvenile abalone

Symmetries, Currents and Conservation Laws of Self-Dual Gravity

We describe an infinite-dimensional algebra of hidden symmetries for the self-dual gravity equations. Besides the known diffeomorphism-type symmetries (affine extension of w(infinity) algebra), this algebra contains new hidden symmetries, which are an affine extension of the Lorentz rotations. The full symmetry algebra has both Kac-Moody and Virasoro-like generators, whose exponentiation maps solutions of the field equations to other solutions. Relations to problems of string theories are briefly discussed.Comment: 14 pages, LaTeX, the paper was reformatte

Separation Options for Phosphorylated Osteopontin from Transgenic Microalgae Chlamydomonas reinhardtii.

Correct folding and post-translational modifications are vital for therapeutic proteins to elicit their biological functions. Osteopontin (OPN), a bone regenerative protein present in a range of mammalian cells, is an acidic phosphoprotein with multiple potential phosphorylation sites. In this study, the ability of unicellular microalgae, Chlamydomonas reinhardtii, to produce phosphorylated recombinant OPN in its chloroplast is investigated. This study further explores the impact of phosphorylation and expression from a "plant-like" algae on separation of OPN. Chromatography resins ceramic hydroxyapatite (CHT) and Gallium-immobilized metal affinity chromatography (Ga-IMAC) were assessed for their binding specificity to phosphoproteins. Non-phosphorylated recombinant OPN expressed in E. coli was used to compare the specificity of interaction of the resins to phosphorylated OPN. We observed that CHT binds OPN by multimodal interactions and was better able to distinguish phosphorylated proteins in the presence of 250 mM NaCl. Ga-IMAC interaction with OPN was not selective to phosphorylation, irrespective of salt, as the resin bound OPN from both algal and bacterial sources. Anion exchange chromatography proved an efficient capture method to partially separate major phosphorylated host cell protein impurities such as Rubisco from OPN

Predicting biological variation using a simple morphometric marker in the sedentary marine invertebrate Haliotis rubra

Copyright © Inter-Research 2008Many sedentary marine invertebrates have a fine-scale (100s m) population structure that complicates their conservation and management. This is a consequence of the limited information on the boundaries between component populations and the biological variability among them. Blacklip abalone Haliotis rubra form discrete populations, many of which are ‘stunted’ with individuals reaching a maximum length less than those in adjacent areas. In the present study, we obtained information on the growth, size at maturity and fecundity of H. rubra from stunted and ‘non-stunted’ populations spread across broad (10s km) and fine (100s m) spatial scales. Relationships between each of these key population parameters and a simple ‘morphometric marker’ based on the relationship between shell length and shell height were also examined. Variation in broad-scale growth and size at maturity could primarily be attributed to differences between stunted and non-stunted sites. Within the stunted site, growth and size at maturity were substantially different over distances >150 m. However, within the non-stunted site these parameters tended to be similar across 1000 m. While the lowest fecundities tended to be in the stunted sites, there was significant overlap among all sites. These spatial patterns in biology were highly correlated with the spatial variability observed in a simple morphometric marker. These results suggest that this morphometric marker can be used as a tool for the spatial management of abalone fisheries by cheaply inferring key biological parameters for individual populations and identifing the boundaries among these based on these differences.T. Saunders and S. Mayfiel

Optimization of culture conditions for the production and activity of recombinant xylanase from microalgal platform

Xylanases are enzymes responsible for the hydrolysis of the heteropolymer xylan. They have wide applications ranging from the bakery, animal husbandry, and textile to pulp and paper industry and biofuel productions. Recombinant xylanase production has been previously reported from different hosts such as bacteria and yeast. Microalgae offer a safe and cost-effective photosynthetic platform for producing recombinant proteins, including therapeutics and industrial enzymes. In this study, we optimized the production of recombinant xylanase expressed and secreted from the green alga, Chlamydomonas reinhardtii. The growth of the culture was optimized using response surface methodology (RSM) based on central composite design (CCD), with two numeric (culture incubation time and agitation rate) and one categoric (light intensity) factors. The optimum biomass concentration was obtained as 0.71 mg/mL from the CCD values. In addition, bubble column photobioreactors were set and compared for the culture growth, the protein concentration, and the enzyme activity under different light intensities and air flows. Increasing the aeration rate from 1 vvm to 2 vvm resulted in improved enzyme activity from 5330.5 U/g to 6277.7 U/g under 3500 lux illumination on the 3rd day of the culture. This study may lead to the further large-scale production of xylanase with high enzyme activity and reveal the advantage of the microalgae as a sustainable platform. © 2023 Elsevier B.V

Development of a cell surface display system in Chlamydomonas reinhardtii

Cell-surface display systems are biotechnological techniques used to express heterologous proteins on the cell surface. Their application depends directly on the cell system used, as well as on the anchoring point for the surface displayed protein. To meet most application demands an inexpensive, safe, and scalable production platform, that reduces the economic barriers for large scale use is needed. Toward this goal, we screened three possible cell surface anchoring points in the green algae Chlamydomonas by fusing mVenus to prospective anchors moieties. The vectors harboring mVenus:anchor were screened for mVenus fluorescence and tested for cellular localization by confocal laser scanning microscopy. This strategy allowed the identification of two functional anchors, one for the cytoplasmic membrane using the MAW8 GPI-anchor signal, and one for the cell wall using the GP1 protein. We also exploited GP1 chemical and biological traits to release the fused proteins efficiently during cell wall shedding. Our work provides a foundation for surface engineering of C reinhardtii supporting both cell biology studies and biotechnology applications