副基體綱

副基體綱
	吉姆薩染液染色的陰道滴蟲活動體
科學分類
界：	古蟲界 Excavata
綱：	副基體綱 Parabasalia; Honigberg 1973
目
	Trichomonadida; Cristamonadida; Spirotrichonymphida; Trichonymphida;

副基體綱 (Parabasalia) 是古蟲界中一群具有鞭毛的原生生物，大部分的物種與動物共生，例如白蟻^[1]和某些蟑螂腸道內的物種，這些共生原生生物同時也與細菌共生，細菌會協助原生生物分解纖維素，間接幫助白蟻和蟑螂分解纖維素。副基體綱中某些物種為寄生性，某些則會導致人類疾病。

特徵

細胞前端生有一叢或多叢的鞭毛。副機體綱的特徵是基體 (basal body) 藉由副基體纖維 (parabasal fibers) 與高基氏體連接。大部分物種胞內有一束維管，從細胞前端延伸至細胞末端，有些物種還會突出胞外，此構造稱作軸柱 (axostyle)，副基體綱的軸柱構造與銳滴蟲目的軸柱不同。

副基體綱為不具線粒體的厭氧生物，不具線粒體，副基體綱擁有一種小型的造氫體 (hydrogenosome)，學者推測這些造氫體是由退化的線粒體演化而來^[2]。其他不具線粒體的鞭毛蟲也具有類似的造氫體，學者認為這些具有造氫體的鞭毛蟲和副基體綱的親緣關係接近，於是將其稱作「後滴門 (metamonad)」。副基體綱不具有食槽 (feeding groove) ，這個特徵和線粒體一樣是在演化過程中消失的。

分類

副前基體綱分類狀況凌亂，被不同的學者分類方式不同，一般分為七到十個目^[3]，現在則被分為四個目：Trichonymphida、Spirotrichonymphida、Cristamonadida，和 Trichomonadida^[4]。

毛滴蟲目 (Trichomonadida) 具有4-6根鞭毛，其中一根鞭毛附着在細胞的側面，常形成波狀膜。很多物種寄生在脊椎動物中，例如陰道滴蟲會經由人類性行為傳播。
Trichonymphida、Spirotrichonymphida、Cristamonadida 則具有較多的鞭毛，大多棲息在昆蟲的腸道內^[5]。

參考資料

^ Ohkuma M, Iida T, Ohtoko K, et al. Molecular phylogeny of parabasalids inferred from small subunit rRNA sequences, with emphasis on the Hypermastigea. Mol. Phylogenet. Evol. June 2005, 35 (3): 646–55. PMID 15878133. doi:10.1016/j.ympev.2005.02.013.
^ Bui, ET; Bradley, PJ; Johnson, PJ. A common evolutionary origin for mitochondria and hydrogenosomes. Proceedings of the National Academy of Sciences of the United States of America. Sep 3, 1996, 93 (18): 9651–6. Bibcode:1996PNAS...93.9651B. PMC 38483 . PMID 8790385. doi:10.1073/pnas.93.18.9651.
^ Yubuki, Naoji; Céza, VÍT; Cepicka, Ivan; Yabuki, Akinori; Inagaki, Yuji; Nakayama, Takeshi; Inouye, Isao; Leander, Brian S. Cryptic Diversity of Free-Living Parabasalids, Pseudotrichomonas keilini and Lacusteria cypriaca n. G., n. Sp., as Inferred from Small Subunit rDNA Sequences. Journal of Eukaryotic Microbiology. 2010, 57 (6): 554–61. PMID 20880033. doi:10.1111/j.1550-7408.2010.00509.x.
^ Adl, Sina M; et, al. The new higher level classification of eukaryotes with emphasis on the taxonomy of protists. Journal of Eukaryotic Microbiology. 2005, 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x .
^ Carpenter KJ, Keeling PJ. Morphology and phylogenetic position of Eucomonympha imla (Parabasalia: Hypermastigida). J. Eukaryot. Microbiol. 2007, 54 (4): 325–32. PMID 17669157. doi:10.1111/j.1550-7408.2007.00263.x.

[pmid15878133-1] Ohkuma M, Iida T, Ohtoko K, et al. Molecular phylogeny of parabasalids inferred from small subunit rRNA sequences, with emphasis on the Hypermastigea. Mol. Phylogenet. Evol. June 2005, 35 (3): 646–55. PMID 15878133. doi:10.1016/j.ympev.2005.02.013.

[2] Bui, ET; Bradley, PJ; Johnson, PJ. A common evolutionary origin for mitochondria and hydrogenosomes. Proceedings of the National Academy of Sciences of the United States of America. Sep 3, 1996, 93 (18): 9651–6. Bibcode:1996PNAS...93.9651B. PMC 38483 . PMID 8790385. doi:10.1073/pnas.93.18.9651.

[3] Yubuki, Naoji; Céza, VÍT; Cepicka, Ivan; Yabuki, Akinori; Inagaki, Yuji; Nakayama, Takeshi; Inouye, Isao; Leander, Brian S. Cryptic Diversity of Free-Living Parabasalids, Pseudotrichomonas keilini and Lacusteria cypriaca n. G., n. Sp., as Inferred from Small Subunit rDNA Sequences. Journal of Eukaryotic Microbiology. 2010, 57 (6): 554–61. PMID 20880033. doi:10.1111/j.1550-7408.2010.00509.x.

[4] Adl, Sina M; et, al. The new higher level classification of eukaryotes with emphasis on the taxonomy of protists. Journal of Eukaryotic Microbiology. 2005, 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x .

[pmid17669157-5] Carpenter KJ, Keeling PJ. Morphology and phylogenetic position of Eucomonympha imla (Parabasalia: Hypermastigida). J. Eukaryot. Microbiol. 2007, 54 (4): 325–32. PMID 17669157. doi:10.1111/j.1550-7408.2007.00263.x.

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