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Dictyostelium Macrocephalum
''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as a normal and often abundant component of the soil microflora, and play an important role in the maintenance of balanced bacterial populations in soils. The genus ''Dictyostelium'' is in the order Dictyosteliida, the so-called cellular slime molds or social amoebae. In turn the order is in the infraphylum Mycetozoa. Members of the order are Protista of great theoretical interest in biology because they have aspects of both unicellularity and multicellularity. The individual cells in their independent phase are common on organic detritus or in damp soils and caves. In this phase they are amoebae. Typically, the amoebal cells grow separately and wander independently, feeding mainly on bacteria. However, they interact to form multi-cellular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyostelium
''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as a normal and often abundant component of the soil microflora, and play an important role in the maintenance of balanced bacterial populations in soils. The genus ''Dictyostelium'' is in the order Dictyosteliida, the so-called cellular slime molds or social amoebae. In turn the order is in the infraphylum Mycetozoa. Members of the order are Protista of great theoretical interest in biology because they have aspects of both unicellularity and multicellularity. The individual cells in their independent phase are common on organic detritus or in damp soils and caves. In this phase they are amoebae. Typically, the amoebal cells grow separately and wander independently, feeding mainly on bacteria. However, they interact to form multi-cellula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicellularity
A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus ''Dictyostelium''. Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells. Colonial organisms are the result of many identical individuals joining together to form a colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular". There are also multinucleate though technically unicellular organisms that are macroscopic, such as the xenophyophorea that can reach 20 cm. Evolutionary history Occurrence Multicellularity has evolved in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocyst
A macrocyst is an aggregate of cells of Dictyostelids formed during sexual reproduction enclosed in a cellulose wall. If two amoebae of different mating types are present in a dark and wet environment, they can fuse during aggregation to form a giant cell. The giant cell will then engulf the other cells in the aggregate and encase the whole aggregate in a thick, cellulose wall to protect it. This is known as a macrocyst. Inside the macrocyst, the giant cell divides first through meiosis, then through mitosis to produce many haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ... amoebae that will be released to feed as normal amoebae would. See also * Life cycle and reproduction of Dictyostelium discoideum References Mycetozoa {{amoebozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amoeba
An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopodia, pseudopods. Amoebae do not form a single Taxonomy (biology), taxonomic group; instead, they are found in every major Lineage (evolution), lineage of eukaryote, eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals. Microbiologists often use the terms "amoeboid" and "amoeba" interchangeably for any organism that exhibits amoeboid movement. In older classification systems, most amoebae were placed in the Class (biology), class or subphylum Sarcodina, a grouping of Unicellular organism, single-celled organisms that possess pseudopods or move by protoplasmic flow. However, molecular phylogenetic studies have shown that Sarcodina is not a monophyletic group whose memb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyostelium Mucoroides
''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as a normal and often abundant component of the soil microflora, and play an important role in the maintenance of balanced bacterial populations in soils. The genus ''Dictyostelium'' is in the order Dictyosteliida, the so-called cellular slime molds or social amoebae. In turn the order is in the infraphylum Mycetozoa. Members of the order are Protista of great theoretical interest in biology because they have aspects of both unicellularity and multicellularity. The individual cells in their independent phase are common on organic detritus or in damp soils and caves. In this phase they are amoebae. Typically, the amoebal cells grow separately and wander independently, feeding mainly on bacteria. However, they interact to form multi-cellular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homothallism
Homothallic refers to the possession, within a single organism, of the resources to reproduce sexually; i.e., having male and female reproductive structures on the same thallus. The opposite sexual functions are performed by different cells of a single mycelium. It can be contrasted to heterothallic. It is often used to categorize fungi. In yeast, heterothallic cells have mating types a and α. An experienced mother cell (one that has divided at least once) will switch mating type every cell division cycle because of the ''HO'' allele. Sexual reproduction commonly occurs in two fundamentally different ways in fungi. These are outcrossing (in heterothallic fungi) in which two different individuals contribute nuclei to form a zygote, and self-fertilization or selfing (in homothallic fungi) in which both nuclei are derived from the same individual. Homothallism in fungi can be defined as the capability of an individual spore to produce a sexually reproducing colony when propagated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploid is often used to describe cells with three or more chromosome sets. Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle. Half ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterothallism
Heterothallic species have sexes that reside in different individuals. The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of sexual reproduction from a single organism. In heterothallic fungi, two different individuals contribute nuclei to form a zygote. Examples of heterothallism are included for ''Saccharomyces cerevisiae, Aspergillus fumigatus, Aspergillus flavus'', ''Penicillium marneffei'' and ''Neurospora crassa''. The heterothallic life cycle of ''N. crassa'' is given in some detail, since similar life cycles are present in other heterothallic fungi. Life cycle of ''Saccharomyces cerevisiae'' The yeast ''Saccharomyces cerevisiae'' is heterothallic. This means that each yeast cell is of a certain mating type and can only mate with a cell of the other mating type. During vegetative growth that ordinarily occurs when nutrients are abundant, ''S. cer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyostelium Discoideum
''Dictyostelium discoideum'' is a species of soil-dwelling amoeba belonging to the phylum Amoebozoa, infraphylum Mycetozoa. Commonly referred to as slime mold, ''D. discoideum'' is a eukaryote that transitions from a collection of unicellular amoebae into a multicellular slug and then into a fruiting body within its lifetime. Its unique asexual lifecycle consists of four stages: vegetative, aggregation, migration, and culmination. The lifecycle of ''D. discoideum'' is relatively short, which allows for timely viewing of all stages. The cells involved in the lifecycle undergo movement, chemical signaling, and development, which are applicable to human cancer research. The simplicity of its lifecycle makes ''D. discoideum'' a valuable model organism to study genetic, cellular, and biochemical processes in other organisms. Natural habitat and diet In the wild, ''D. discoideum'' can be found in soil and moist leaf litter. Its primary diet consists of bacteria, such as ''Escherichia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metazoans
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemotaxis
Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food (e.g., glucose) by swimming toward the highest concentration of food molecules, or to flee from poisons (e.g., phenol). In multicellular organisms, chemotaxis is critical to early development (e.g., movement of sperm towards the egg during fertilization) and development (e.g., migration of neurons or lymphocytes) as well as in normal function and health (e.g., migration of leukocytes during injury or infection). In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. The aberrant chemotaxis of leukocytes and lymphocytes also contribute to inflammatory diseases such as atherosclerosis, asthma, and arthr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipeptide
A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiologically important, and some are both physiologically and commercially significant. A well known dipeptide is aspartame, an artificial sweetener. Dipeptides are white solids. Many are far more water-soluble than the parent amino acids. For example, the dipeptide Ala-Gln has the solubility of 586 g/L more than 10x the solubility of Gln (35 g/L). Dipeptides also can exhibit different stabilities, e.g. with respect to hydrolysis. Gln does not withstand sterilization procedures, whereas this dipeptide does. Because dipeptides are prone to hydrolysis, the high solubility is exploited in infusions, i.e. to provide nutrition. Examples Commercial value About six dipeptides are of commercial interest. *Aspartame (''N''-L-α-aspartyl-L-phenyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
