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Trophozoites adhere to host epithelial cells via a specialized disk-shaped organelle called the ventral disk. [14] Cysts are oval-shaped cells slightly smaller than trophozoites. [15] They lack flagella, and are covered by a smooth, clear cyst wall. [15] Each cyst contains four nuclei and fragments of the ventral disc. [15]
Giardiasis is a parasitic disease caused by Giardia duodenalis (also known as G. lamblia and G. intestinalis). [3] Infected individuals who experience symptoms (about 10% have no symptoms) may have diarrhea, abdominal pain, and weight loss. [1] Less common symptoms include vomiting and blood in the stool. [1]
About 40 species have been described, but most of them are probably synonyms. [11] Currently, five to six morphologically distinct species are recognised. [12] Giardia duodenalis (=G. intestinalis, =G. lamblia) infect humans and other mammals, G. microti infects voles, G. muris is found in other mammals, G. ardeae and G. psittaci in birds, and G. agilis in amphibians. [4]
However, researchers found G. duodenalis to have a core set of genes that function in meiosis and that are widely present among sexual eukaryotes. [5] These results suggested that Giardia duodenalis is capable of meiosis and thus sexual reproduction.
Many phytoplasma-infected plants develop a bushy or "witches' broom" appearance due to changes in their normal growth patterns. Most plants exhibit apical dominance, but infection can trigger the proliferation of axillary (side) shoots and a reduction in internode size. [8] Such symptoms are actually useful in the commercial production of ...
Hypersensitive response (HR) is a mechanism used by plants to prevent the spread of infection by microbial pathogens.HR is characterized by the rapid death of cells in the local region surrounding an infection and it serves to restrict the growth and spread of pathogens to other parts of the plant.
Plants can play host to a wide range of pathogen types, including viruses, bacteria, fungi, nematodes, and even other plants. [35] Notable plant viruses include the papaya ringspot virus, which has caused millions of dollars of damage to farmers in Hawaii and Southeast Asia, [36] and the tobacco mosaic virus which caused scientist Martinus ...
This high-magnification image shows part of a cell with single bacteroids within their host plant. In this image, endoplasmic reticulum, dictysome, and cell wall can be seen. Rhizobacteria are root-associated bacteria that can have a detrimental (parasitic varieties), neutral or beneficial effect on plant growth.