Seaweeds for animal production use

Early scientific studies conducted at the turn of the twentieth century failed to support the inclusion of seaweeds into animal rations at high inclusion rates. At that time, based on proximate analysis and energy availability studies, dried seaweeds or kelp meal largely fell out of favor as a recommended animal feed source. Nevertheless, kelp meal was still regarded by some as having properties which improved animal health and productivity which were not conveniently explained by conventional feed analysis. In the 1970s, research leads to the discovery that chelated micromineral sources were more efficient for the delivery of microelements than conventional inorganic sources. This prompted renewed interest in seaweeds as rich sources of over 60+ microelements. However, it was only in the early 2000s, when detailed analysis of the complex structure of the polysaccharides associated with seaweeds was tied to their prebiotic actions, that a clear explanation for the basis of productivity and health enhancement was attained. Further analysis indicated that other constituents in various brown seaweeds such as phlorotannins and antioxidants also contributed to the observed bioactivities. Of all of the brown seaweeds cited in studies, the one most scientifically documented is Ascophyllum nodosum, and of all of these sources, Tasco®, a sundried, high-quality macroalgal product, produced by Acadian Seaplants has been the most studied. The latest studies of Tasco® suggest prebiotic potencies at least five times that of the reference prebiotic inulin with additional performance-enhancing benefits in animal rations that rival antibiotic inclusions.     

Microbial alginate production,modification and its applications

Alginate is an important polysaccharide used widely in the food, textile, printing and pharmaceutical industries for its viscosifying, and gelling properties. All commercially produced alginates are isolated from farmed brown seaweeds. These algal alginates suffer from heterogeneity in composition and material properties. Here, we will discuss alginates produced by bacteria; the molecular mechanisms involved in their biosynthesis; and the potential to utilize these bacterially produced or modified alginates for high-value applications where defined material properties are required.     

Sustainable harvesting of wild seaweed resources

Abstract

Macroalgae have played an important role in coastal communities for centuries. In the past, they have been harvested and gathered from shorelines around the world for traditional uses such as food, animal feed and a crude fertilizer (marine manure). Today, seaweeds are used in a multitude of applications with expanding global industries based on hydrocolloids, cosmetics and food supplements, and also as a potential biofuel source. However, of the approximately 10?000 algal species reported to exist, only a small number are commercially utilized. While representing only a small fraction of total global seaweed production, harvesting and gathering ‘wild’ seaweeds has had, and continues to have, an integral role in many coastal societies, often being intrinsically linked to the cultural identity of those coastal communities. Today, 32 countries actively harvest seaweeds from wild stocks, with over 800?000 t harvested annually from natural beds. It is vitally important that seaweeds are utilized sustainably and that natural resources are effectively managed by coastal communities with vested interests around the world. As the popularity of seaweeds increases and the use of less traditional species with novel applications comes to the fore, it is critically important to make certain that the sustainability of the resource is ensured given the increased pressures of harvesting. Issues exist regarding ownership of the resource and its over-exploitation, and the implementation of environmentally damaging harvesting techniques must be avoided. Resource scientists, managers, conservationists, governments, and other stakeholders need to be proactive in the sustainable management of these vulnerable, yet valuable, resources.     

Orofacial clefting: recent insights into a complex trait

Orofacial clefts are common birth defects of multifactorial etiology. Several novel approaches have recently been applied to investigate the causes of clefts. These include examining Mendelian forms of clefting to identify genes that might also be implicated in isolated clefting, analyzing chromosomal rearrangements in which clefting is part of the resultant phenotype, studying animal models in which clefts arise either spontaneously or as a result of mutagenesis experiments, exploring how expression patterns correlate with gene function and examining the effects of gene-environment interactions. Together, these complementary strategies are providing researchers with new clues as to what mechanisms underlie orofacial clefting.     

The impact of seaweed life phase and postharvest storage duration on the chemical and rheological properties of hybrid carrageenans isolated from Portuguese Mastocarpus stellatus

Variations in chemical and gelling characteristics of hybrid carrageenan extracted from Mastocarpus stellatus seaweeds are studied in order to explore potential links between the seaweeds life phase, the seaweeds postharvest storage duration and the phycocolloids properties. Chemical structures of phycocolloids were assessed by Fourier Transform Infrared spectroscopy (FTIR) and ¹H NMR spectroscopy. Rheological properties of hybrid carrageenans, such as intrinsic viscosity ([η]), gel elasticity (G₀), gel setting temperature (T_g) and gel melting temperature (T_m), were measured with a stress rheometer. Seasonal variation in the degree of sulphates of native extracts and in their corresponding gelling properties is found. The minimum in gelling properties coincides with a minimum of fructified gametophytes in populations harvested during the cold season. Alkali treated extracts also show minimum gelling properties during the cold season but no correlation with variations in the chemical characteristics could be identified. The gel setting temperature is the only significant change in the properties of hybrid carrageenans extracted from dried seaweeds stored over 39 months in opaque and sealed plastic bags. These results point to non trivial relationships between the life stages of M. stellatus seaweeds, the chemical structure and gel properties of the alkali-extracted phycocolloids, and suggest a route towards the sustainable exploitation of the natural resource.     

Experimental approaches used to quantify physical parameters at cellular and subcellular levels

From a mechanical point of view, plant and hyphal cells are more complex than their animal counterparts because the variety of structural components determining cellular architecture is broader. In addition to cytoskeletal elements and the plasma membrane, the cell wall and turgor pressure equip plant and hyphal cells with structures analogous to an exoskeleton and a hydroskeleton, respectively. To quantify the physical properties of plant and hyphal cells, researchers have developed a plethora of experimental methods. This review provides an overview of experimental approaches that have been used to measure turgor pressure and to determine the mechanical properties of the plant cell wall at the subcellular level. It is completed by a glimpse into the arsenal of techniques that has been used to characterize the physical properties of cytoskeletal elements. These have mostly been used on animal cells, but we hope they will find their way into plant cell research. Finally, assays and tests to measure the generation of forces by cells and subcellular structures are discussed.     

Seaweed protoplasts: status,biotechnological perspectives and needs

Protoplasts are living plant cells without cell walls which offer a unique uniform single cell system that facilitates several aspects of modern biotechnology, including genetic transformation and metabolic engineering. Extraction of cell wall lytic enzymes from different phycophages and microbial sources has greatly improved protoplast isolation and their yield from a number of anatomically more complex species of brown and red seaweeds which earlier remained recalcitrant. Recently, recombinant cell wall lytic enzymes were also produced and evaluated with native ones for their potential abilities in producing viable protoplasts from Laminaria. Reliable procedures are now available to isolate and culture protoplasts from diverse groups of seaweeds. To date, there are 89 species belonging to 36 genera of green, red and brown seaweeds from which successful protoplast isolation and regeneration has been reported. Of the total species studied for protoplasts, most belonged to Rhodophyta with 41 species (13 genera) followed by Chlorophyta and Phaeophyta with 24 species each belonging to 5 and 18 genera, respectively. Regeneration of protoplast-to-plant system is available for a large number of species, with extensive literature relating to their culture methods and morphogenesis. In the context of plant genetic manipulation, somatic hybridization by protoplast fusion has been accomplished in a number of economically important species with various levels of success. Protoplasts have also been used for studying foreign gene expression in Porphyra and Ulva. Isolated protoplasts are also exploited in numerous miscellaneous studies involving membrane function, cell structure, bio-chemical synthesis of cell walls etc. This article briefly reviews the status of various developments in seaweed protoplasts research and their potentials in genetic improvement of seaweeds, along with needs that must to be fulfilled for effective realization of the objectives envisaged for protoplast research.     

Visual position stabilization in the hummingbird hawk moth, Macroglossum stellatarum L. II. Electrophysiological analysis of neurons sensitive to wide-field image motion

Response properties of neurons in the cervical connectives of the hummingbird hawk moth, Macroglossum stellatarum L., were determined. All neurons described in this account respond directionally selectively to motion in large parts of the visual field of either eye. They respond maximally to bilateral stimulation, preferring either motion as induced on the eyes during translatory movements of the animal or when it turns around one of its body axes. Cells most sensitive to rotational motion either respond best to rotation of the patterns around the vertical axis of the animal or around its longitudinal body axis. Neurons most sensitive to translational pattern motion respond best to either simulated translations of the animal along its vertical or along an oblique axis. Most types of neurons respond tonically and do not habituate. The sensitivity to motion stimuli is not evenly distributed within the receptive field of any investigated neuron. Part of these neurons might play a role in visual position and course stabilization. Accepted: 13 August 1997     

Seaweed extract stimuli in plant science and agriculture

Both micro- and macroalgae have long been used to augment plant productivity and food production in various regions of the world through their beneficial effects when applied to soils. Interactions of algae with the soil community undoubtedly are complex and benefits are dependent on the crop and the local environmental conditions. This has resulted in much speculation as to mechanisms involved as well as the validity of the results reported. It is now 60 years since the first commercial seaweed extract was manufactured for agricultural use. These aqueous extracts allowed for the first time the direct application of soluble seaweed constituents to specific plant organs such as leaves and roots. The earlier concept that benefits of seaweeds and their extracts were due mainly to their manurial value or to their micronutrient suites is no longer tenable. Seaweeds likewise have been used for millennia as fodder supplements to improve animal nutrition and productivity. Recent research is focusing on their mode of action, specific health benefits, and the mechanisms of action in animals. Improved analytical techniques and instrumentation coupled with the use of molecular genetic tools are establishing that seaweed extracts can modify plant and animal responses at a fundamental level. It therefore seems appropriate to review key developments over the years and to remark on novel findings. A new and exciting vista has opened for seaweed extracts in both plant and animal applications.     

144 Use of Fourier Transform Infrared (FT IR) Diffuse Reflectance Spectroscopy and Hamming Distances to Study the Phycocolloid Chemosystematics of the Red Algae (Rhodophta)

Coalescence in seaweeds is known to occur in the laboratory among young and older sporelings and in the field between neighboring conspecific clumps. However, because spores and germlings are difficult to study in the field, it is as yet unknown at which stage of population development coalescence is most important. Since many seaweeds disperse aggregated propagules, often with a sticky mucilagous envelope around the spores, aggregated recruitment and coalescence might be more important at early stages of population establishment than among fully grown, well established clumps. Using recruitment plates maintained during several experimental times in the field, we are evaluating the above idea with mid-intertidal populations of Mazzaella laminarioides. During high fertility seasons, close to 45% of the spores settling within or at close (<1 m) distances of the bed exhibited aggregated recruitment, forming groups of 2 to 150+spores. The probability of aggregated recruitments is a function of dispersal distance and spore density. The number of sporelings produced is a function of spore density and coalescence. Highest after-recruitment mortality (first 15 days) occurs among solitary recruits, followed by sporelings conformed by small number of spores (2–4). Approximately 50% of the spores recruited, isolated or in group, coalesce within these 15 days, gradually forming massive sporelings with increasingly larger basal areas. Thus, after recruitment, sporelings may disappear (die), survive or coalesce. These three alternatives are integrated in a new demographic model for coalescing seaweeds (supported by grant FONDECYT 1020855).     

143 Coalescense During Early Recruitment of Mazzaella Laminarioides

Coalescence in seaweeds is known to occur in the laboratory among young and older sporelings and in the field between neighboring conspecific clumps. However, because spores and germlings are difficult to study in the field, it is as yet unknown at which stage of population development coalescence is most important. Since many seaweeds disperse aggregated propagules, often with a sticky mucilagous envelope around the spores, aggregated recruitment and coalescence might be more important at early stages of population establishment than among fully grown, well established clumps. Using recruitment plates maintained during several experimental times in the field, we are evaluating the above idea with mid‐intertidal populations of Mazzaella laminarioides. During high fertility seasons, close to 45% of the spores settling within or at close (<1 m) distances of the bed exhibited aggregated recruitment, forming groups of 2 to 150+spores. The probability of aggregated recruitments is a function of dispersal distance and spore density. The number of sporelings produced is a function of spore density and coalescence. Highest after‐recruitment mortality (first 15 days) occurs among solitary recruits, followed by sporelings conformed by small number of spores (2–4). Approximately 50% of the spores recruited, isolated or in group, coalesce within these 15 days, gradually forming massive sporelings with increasingly larger basal areas. Thus, after recruitment, sporelings may disappear (die), survive or coalesce. These three alternatives are integrated in a new demographic model for coalescing seaweeds (supported by grant FONDECYT 1020855).     

Genomic architectural variation of plant mitochondria—A review of multichromosomal structuring

Since the endosymbiont origin from α-Proteobacteria, mitochondrial genomes have undergone extremely divergent evolutionary trajectories among eukaryotic lineages. Compared with the relatively compact and conserved animal mitochondrial genomes, plant mitochondrial genomes have many unique features, especially their large and complex genomic arrangements. The sizes of fully sequenced plant mitochondrial genomes span over a 100-fold range from 66 kb in Viscum scurruloideum to 11 000 kb in Silene conica. In addition to the typical circular structure, some species of plants also possess linear, and even multichromosomal, architectures. In contrast with the thousands of fully sequenced animal mitochondrial genomes and plant plastid genomes, only around 200 fully sequenced land plant mitochondrial genomes have been published, with many being only draft assemblies. In this review, we summarize some of the known novel characteristics found in plant mitochondrial genomes, with special emphasis on multichromosomal structures described in recent publications. Finally, we discuss the future prospects for studying the inheritance patterns of multichromosomal plant mitochondria and examining architectural variation at different levels of taxonomic organization—including at the population level.     

Biological activities and potential cosmeceutical applications of bioactive components from brown seaweeds: a review

Seaweeds are the primary producers of all aquatic ecosystems. Chemical constituents isolated from diverse classes of seaweeds exert a wide range of nutritional, functional and biological activities. Unique metabolites of seaweeds possess specific biological properties that make them potential ingredients of many industrial applications such as functional foods, pharmaceuticals and cosmeceuticals. Cosmeceuticals of natural origin are becoming more popular than synthetic cosmetics. Hence, the investigation of new seaweeds derived functional components, a different source of natural products, has proven to be a promising area of cosmeceutical studies. Brown seaweeds also produce a range of active components including unique secondary metabolites such as phlorotannins and many of which have specific biological activities that give possibilities for their economic utilization. Brown seaweeds derived active compounds have been shown various functional properties including, antioxidant, antiwrinkling, whitening, antiinflammatory and antiallergy. It is well-known that these kind of biological effects are closely associated with cosmeceutical preparations. This communication reviews the current knowledge on brown seaweeds derived metabolites with various biological activities and the potential use as cosmeceutical ingredients. It is hoped that the reviewed literature on multifunctional properties of brown seaweeds will improve access to the seaweed based natural products specially the ability to incorporate these functional properties in cosmeceutical applications.     

A conceptual framework for studying the strength of plant–animal mutualistic interactions

The strength of species interactions influences strongly the structure and dynamics of ecological systems. Thus, quantifying such strength is crucial to understand how species interactions shape communities and ecosystems. Although the concepts and measurement of interaction strength in food webs have received much attention, there has been comparatively little progress in the context of mutualism. We propose a conceptual scheme for studying the strength of plant–animal mutualistic interactions. We first review the interaction strength concepts developed for food webs, and explore how these concepts have been applied to mutualistic interactions. We then outline and explain a conceptual framework for defining ecological effects in plant–animal mutualisms. We give recommendations for measuring interaction strength from data collected in field studies based on a proposed approach for the assessment of interaction strength in plant–animal mutualisms. This approach is conceptually integrative and methodologically feasible, as it focuses on two key variables usually measured in field studies: the frequency of interactions and the fitness components influenced by the interactions.     

The interspecific biomass–density relationship for terrestrial plants: where do clonal red seaweeds stand and why?

For crowded stands of terrestrial plants, ranging from mosses to trees, plant (or ramet, for clonal plants) density is negatively related to stand biomass. Stand biomass and ramet density were determined for Mazzaella cornucopiae and for Pterocladiella capillacea , two morphologically distinct intertidal clonal red seaweeds, to compare them with terrestrial plants. For these seaweeds, ramet densities were similar to the highest values reported for terrestrial plants (mosses, specifically). Stand biomass was higher than average values expected from the terrestrial interspecific biomass–density relationship, but lower than the limits expected from the terrestrial ultimate biomass–density line. These seaweeds show unexpectedly low ramet slenderness and high biomass packing per unit of volume, compared with the trend observed for terrestrial plants. Possible explanations for these differences are related to the particular physiology and habitat of intertidal clonal seaweeds.     

VARIATION IN ANATOMICAL AND MATERIAL PROPERTIES EXPLAINS DIFFERENCES IN HYDRODYNAMIC PERFORMANCES OF FOLIOSE RED MACROALGAE (RHODOPHYTA)1

Over the last two decades, many studies on functional morphology have suggested that material properties of seaweed tissues may influence their fitness. Because hydrodynamic forces are likely the largest source of mortality for seaweeds in high wave energy environments, tissues with material properties that behave favorably in these environments are likely to be selected for. However, it is very difficult to disentangle the effects of materials properties on seaweed performance because size, shape, and habitat also influence mechanical and hydrodynamic performance. In this study, anatomical and material properties of 16 species of foliose red macroalgae were determined, and their effects on hydrodynamic performance were measured in laboratory experiments holding size and shape constant. We determined that increased blade thickness (primarily caused by the addition of medullary tissue) results in higher flexural stiffness (EI), which inhibits the seaweed’s ability to reconfigure in flowing water and thereby increases drag. However, this increase is concurrent with an increase in the force required to break tissue, possibly offsetting any risk of failure. Additionally, while increased nonpigmented medullary cells may pose a higher metabolic cost to the seaweed, decreased reconfiguration causes thicker tissues to expose more photosynthetic surface area incident to ambient light in flowing water, potentially ameliorating the metabolic cost of producing these cells. Material properties can result in differential performance of morphologically similar species. Future studies on ecomechanics of seaweeds in wave‐swept coastal habitats should consider the interaction of multiple trade‐offs.     

Plasma membrane transport systems in higher plants: From black boxes to molecular physiology

Considerable progress in identifying transport systems of the plant plasma membrane has been made recently. The putative systems cloned to date comprise H⁺-ATPases, potassium, chloride and water channels, and carriers involved in the transport of glucose, sucrose, amino acids, peptides, potassium, nitrate, ammonium, phosphate, sulfate, iron and copper. Most of these systems were identified first in Arabidopsis thaliana . Successful cloning strategies have involved the following variety of techniques: complementation of yeast mutants, screening of Arabidopsis mutants, immunoscreening of a cDNA expression library expressed in mammalian cells, screening of genomic and cDNA libraries with probes (or degenerate oligonucleotides) derived from yeast and/or animal genes, or database screening for sequence similarity to eukaryotic counterparts. Many related transport systems have subsequently been identified either by screening libraries directly, or by systematic cDNA sequencing programs. Surprisingly large gene families have been revealed. Heterologous expression systems, such as yeast, Xenopus oocytes or insect cells, provide tools for studying the transport activities, biochemical properties and structure-function relationships of these systems. Their expression and functions in planta are investigated using northern blot analysis, in situ hybridization, and transgenic approaches. Individual systems encoded by the same gene family can differ in their transport properties and have distinct tissue expression patterns. Such diversity might be central to the integration of solute transport at the whole plant level, allowing the differential expression of sets of transport systems specifically tailored to the requirements of each tissue.     

Can tropical seaweeds reduce herbivory by growing at night? Diel patterns of growth,nitrogen content,herbivory, and chemical versus morphological defenses

Summary Tropical seaweeds in the genus Halimeda reduce losses to grazing by capitalizing on diel patterns of herbivore activity. These seaweeds produce new, more herbivoresusceptible growth at night when herbivorous reef fishes are inactive. Plant portions more than 48 h old are low in food value, well defended morphologically (calcified and high in ash content), and relatively resistant to herbivory. Younger plant portions represent 3–4.5 times the food value (nitrogen or organic content) of older portions but are only moderately more susceptible to herbivores due to their high concentrations of the terpenoid feeding deterrents halimedatrial and halimedatetraacetate. Halimedatrial significantly deters grazing by both parrotfishes (Scaridae) and surgeonfishes (Acanthuridae) and occurs in high concentrations (2–4.5% of plant ash-free dry mass) in plant portions that are 4–12 h old, intermediate concentrations (0.3–2.3%) in portions that are 16–26 h old, and low concentrations (0.3%) in older plant portions. The related compound halimedatetraacetate is absent from the youngest plant portions, shows a rapid increase in concentration (from 0 to 1%) in plant material that is approximately 16 h old, and then rapidly declines to low levels (0.1 to 0.2%) in older plant portions. Thus, newly produced tissues are nutritionally valuable but contain high concentrations of defensive chemicals. As these tissues age, morphological defenses increase, the tissue becomes less valuable as a food for herbivores, and chemical defenses decrease. Additionally, new growth of Halimeda remains unpigmented until just before sunrise. Thus, the valuable, nitrogen-containing molecules associated with photosynthesis are not placed in the new, and more herbivore susceptible, growth until lights is available and they can start producing income for the plant.Experiments in a coral-reef microcosm, where diel patterns of light and water chemistry could be altered, indicated that Halimeda's growth pattern is cued by the timing of light-dark cycles rather than by co-occurring diel changes in water chemistry. Although the growth patterns of Halimeda seem unusual, similar patterns appear to occur in numerous other seaweeds and in microalgae such as diatoms and dinoflagellates.