Species complex
In biology, a species complex is a group of closely related species that are very similar in appearance to the point that the boundaries between them are often unclear. Terms sometimes used synonymously but with more precise meanings are: cryptic species for two or more species hidden under one species name, sibling species for two cryptic species that are each other's closest relative, and species flock for a group of closely related species living in the same habitat. As informal taxonomic ranks, species group, species aggregate, and superspecies are also in use.
Two or more taxa once considered conspecific (of the same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties), but this is not a species complex.
A species complex is in most cases a monophyletic group with a common ancestor, although there are exceptions. It may represent an early stage after speciation, but may also have been separated for a long time period without evolving morphological differences. Hybrid speciation can be a component in the evolution of a species complex.
AGG
Agg or AGG may refer to:
As an acronym:
As another abbreviation or symbol:
People with the surname Agg include:
See also
AGG01
AGG01 is the tentative name of a new peptide antibiotic discovered in the breast milk of the Tammar wallaby, reportedly one hundred times more powerful than penicillin.
This compound was found to be effective against MRSA, E. coli, Streptococci, Salmonella, Bacillus subtilis, Pseudomonas spp., Proteus vulgaris, and Staphylococcus aureus.
AGG01 is a cationic peptide, which is a polycationic protein that is rich in positive residues of the amino acids arginine and lysine, and which folds into an amphipathic structure (one which has both hydrophobic and hydrophilic areas). These features mean that it can interact with the anionic lipids in the bacterial membrane, such as phosphatidylglycerol. It inserts itself into the membrane, by competing with cross-linking proteins between each membrane layer, and then sets up trans-membrane protein channels which induce ion transport out of the cell. This causes huge leakage via osmosis through these 'pores’ and the general consensus is that the loss of these essential molecules is the mechanism by which bacteria are killed. The bacterial membrane has a different structure from the mammalian plasma membrane, so the protein can only kill pathogenic cells and not human ones.
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