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Phycotoxin
Phycotoxins (from Greek, ''phykos'', "seaweed"; and ''toxikon'', "toxin") are complex allelopathic chemicals produced by eukaryotic and prokaryotic algal secondary metabolic pathways. More simply, these are toxic chemicals synthesized by photosynthetic organisms. These metabolites are (in most cases) not harmful to the producer but may be toxic to either one or many members of the marine food web. This page focuses on phycotoxins produced by marine microalgae; however, freshwater algae and macroalgae are known phycotoxin producers and may exhibit analogous ecological dynamics. In the pelagic marine food web, phytoplankton are subjected to grazing by macro- and micro-zooplankton as well as competition for nutrients with other phytoplankton species. Marine bacteria try to obtain a share of organic carbon by maintaining symbiotic, parasitic, commensal, or predatory interactions with phytoplankton. Other bacteria will degrade dead phytoplankton or consume organic carbon released by viral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allelopathic
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see black walnut (' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Competition (biology)
Competition is an interaction between organisms or species in which both require a resource that is in limited supply (such as food, water, or territory). Competition lowers the fitness of both organisms involved since the presence of one of the organisms always reduces the amount of the resource available to the other. In the study of community ecology, competition within and between members of a species is an important biological interaction. Competition is one of many interacting biotic and abiotic factors that affect community structure, species diversity, and population dynamics (shifts in a population over time). There are three major mechanisms of competition: interference, exploitation, and apparent competition (in order from most direct to least direct). Interference and exploitation competition can be classed as "real" forms of competition, while apparent competition is not, as organisms do not share a resource, but instead share a predator. Competition among membe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, catalytic activity of their own (usually as a cofactor to an enzyme), defense, and interactions with other organisms (e.g. pigments, odorants, and pheromones). A primary metabolite is directly involved in normal "growth", development, and reproduction. Ethylene exemplifies a primary metabolite produced large-scale by industrial microbiology. A secondary metabolite is not directly involved in those processes, but usually has an important ecological function. Examples include antibiotics and pigments such as resins and terpenes etc. Some antibiotics use primary metabolites as precursors, such as actinomycin, which is created from the primary metabolite tryptophan. Some sugars are metabolites, such as fructose or glucose, which are both p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algal Blooms
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. ''Algal bloom'' commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest. Algal blooms are the result of a nutrient, like nitrogen or phosphorus from various sources (for example fertilizer runoff or other forms of nutrient pollution), entering the aquatic system and causing excessive growth of algae. An algal bloom affects the whole ecosystem. Consequences range from the benign feeding of higher trophic levels to more harmful effects like blocking sunlight from reaching other or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioaccumulation
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. Bioaccumulation, for example in fish, can be predicted by models. Hypothesis for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data. Biotransformation can strongly modify bioaccumulation of chemicals in an organism. Toxicity induced by metals is associated with bioaccumulation and biomagnification. Storage or uptake of metals faster than the rate at which an organism metabolizes and excretes lead to the accumulation of that metal. The presence of various chemicals and harmful substances in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphidophyte
The raphidophytes, formally known as Raphidomonadea or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes are unicellular, with large cells (50 to 100 μm), but no cell walls. Raphidophytes possess a pair of flagella, organised such that both originate from the same invagination (or gullet). One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoid chloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle (or eyespot) typical of this group. In terms of ecology, raphidophytes occur as photosynthetic autotrophs across a range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prymnesiophytes
The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for ''Prymnesium''), are a clade of algae. The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at the class rank rather than as a division. Although the phylogenetics of this group has become much better understood in recent years, there remains some dispute over which rank is most appropriate. Characteristics The chloroplasts are pigmented similarly to those of the heterokonts, but the structure of the rest of the cell is different, so it may be that they are a separate line whose chloroplasts are derived from similar red algal endosymbionts. The cells typically have two slightly unequal flagella, both of which are smooth, and a unique organelle called a ''haptonema'', which is superficially similar to a flagellum but differs in the arrangement of microtubules and in its use. The name comes from the Greek ''hapsis'', touch, and ''n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria. Cyanobacteria use photosynthetic pigments, such as carotenoids, phycobilins, and various forms of chlorophyll, which absorb energy from light. Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed. Phototrophic eukaryotes such as green plants perform photosynthesis in plast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diatoms
A diatom (New Latin, Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's Biomass (ecology), biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion metric tons of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The Protist shell, shells of dead diatoms can reach as much as a half-mile (800 m) deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Dep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy and myzocytosis). In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, ''Oodinium'' and ''Pfiesteria''). Some dinoflagellates pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, the term "flagellate" is included in other terms (such as "dinoflagellate" and "choanoflagellata") which are more formally characterized. Form and behavior Flagella in eukaryotes are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella often support hairs, called mastigonemes, or contain rods. Their ultrastructure plays an important role in classifying eukaryotes. Among protoctists and microscopic anima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physiological
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical and physical functions in a living system. According to the classes of organisms, the field can be divided into medical physiology, animal physiology, plant physiology, cell physiology, and comparative physiology. Central to physiological functioning are biophysical and biochemical processes, homeostatic control mechanisms, and communication between cells. ''Physiological state'' is the condition of normal function. In contrast, ''pathological state'' refers to abnormal conditions, including human diseases. The Nobel Prize in Physiology or Medicine is awarded by the Royal Swedish Academy of Sciences for exceptional scientific achievements in physiology related to the field of medicine. Foundations Cells Although there are differe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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