I-axoneme iyisakhiwo esikhona ku-flagella kanye ne-cilia yamangqamuzana e-eukaryotic, abhekene nokunyakaza kwawo. I-axoneme yakhiwe ngama-microtubules we-helical, axhunywe ngamaprotheni emoto kanye namaprotheni esakhiwo. Lesi sakhiwo sibalulekile ekuhambeni kwamaselula, okuvumela amaseli ukuthi ahambe ngendlela ehlelekile nephumelelayo. Kulo mongo, ukwakheka nezici ze-axoneme kubaluleke kakhulu ekuqondeni ukusebenza kwe-flagella ye-eukaryotic ne-cilia.
Yini ukubaluleka kwe-Axoneme ekusebenzeni kwamaselula kanye ne-ciliary?
I-axoneme iyisakhiwo esiyisisekelo somsebenzi wamaselula kanye ne-ciliary. Inikeza ukusekela nokunyakaza kwe-cilia yamaseli ne-flagella. I-axoneme yakhiwe ngama-microtubules ahlelekile ashelela phezu kwamanye ukuze enze ukunyakaza.
Ngaphezu kwalokho, i-axoneme ibalulekile ukuze kuhambe izinto eziphilayo ezihlukahlukene, njengesidoda ne-protozoa. Ivumela amaseli ukuthi ahambe ngendlela ehlelekile nephumelelayo, enze imisebenzi ebalulekile ekusindeni kwalezi zinto eziphilayo.
Omunye umsebenzi obalulekile we-axoneme umbono we-stimuli yangaphandle. I-cilia ekhona kumaseli ezinzwa iyakwazi ukubona izinguquko endaweni ezungezile futhi idlulisele lolu lwazi ngaphakathi kweseli. Ngakho-ke, i-axoneme ifaka isandla ekuphenduleni kwamaselula ekushukumiseni kwangaphandle.
Kafushane, i-axoneme iyisakhiwo esibalulekile sokusebenza kwamaselula kanye ne-ciliary, edlala indima ebalulekile ekuthuthweni, ekuboneni okushukumisayo, nasekuxhumaneni kokunyakaza kwamaseli. Ukwakheka nokuhleleka kwayo kubalulekile ekuqinisekiseni ukusebenza okufanele kwamangqamuzana nokuphila kwezinto eziphilayo.
Ukubaluleka kwamaprotheni e-Axoneme ne-Myofibril ekusebenzeni kwamaselula kanye nenkontileka.
Amaprotheni e-Axoneme kanye ne-myofibril abalulekile ekusebenzeni kahle kwamaseli nokufinyela kwemisipha. I-axoneme yisakhiwo esikhona ku-cell cilia kanye ne-flagella, ebhekene nokunyakaza kwalezi zakhiwo. I-Myofibrils itholakala emisipha yamathambo nenhliziyo, futhi idlala indima ekufinyezeni kwemisipha.
Ku-axoneme, amaprotheni afana ne-tubulin ne-dynein abalulekile ekuhambeni kwe-cilia ne-flagella. I-Tubulin yakha ama-microtubules akha i-axoneme, kuyilapho i-dynein inesibopho sokushelela kwe-microtubule, ikhiqize ukunyakaza okuphawulekayo kwalezi zakhiwo. Ngaphandle kwalawa maprotheni, ingqamuzana ngeke likwazi ukwenza ukunyakaza okubalulekile emisebenzini efana nokuhamba nokubona izinto ezishukumisayo zangaphandle.
Ku-myofibrils, amaprotheni afana ne-actin ne-myosin abalulekile ekufinyezeni kwemisipha. I-Actin yakha imicu emincane, kuyilapho i-myosin yakha imicu ewugqinsi. Phakathi nokufinyela kwemisipha, la maprotheni ashibilika phezu komunye, afinyeze ubude be-myofibrils futhi abangele ukugoqa kwemisipha. Ngaphandle kokusebenza kwalawa maprotheni, imisipha ngeke ikwazi ukugoqa futhi yenza ukunyakaza.
Ngakho-ke, amaprotheni e-axoneme kanye ne-myofibril adlala indima ebalulekile ekusebenzeni kwamangqamuzana kanye nokuqina kwemisipha. Zibalulekile ekuhambeni kwamaselula kanye nokufinyela kwemisipha, futhi zibalulekile ekugcineni i-homeostasis nempilo yomzimba.
Ukwakheka kwamakhemikhali kwama-microtubules: ayini futhi akhiwa kanjani?
Ukwakheka kwamakhemikhali kwama-microtubules kubalulekile ekuqondeni ukwakheka nokusebenza kwalezi zakhiwo ezibalulekile zamangqamuzana. Ama-microtubules akhiwa yi-tubulin, iphrotheni eyakhiwe izinhlobo ezimbili eziyinhloko zama-subunits: i-alpha ne-beta. Lawa ma-subunits ahlelwe abe ama-dimers abopha ukuze akhe ama-protofilaments, wona ahlotshaniswa eceleni ukuze akhe ama-microtubules.
Ama-Microtubules adlala indima ebalulekile ezinqubweni zamaselula njengokuhlukana kwamaseli, ukuthuthwa kwe-intracellular, kanye nokunyakaza kwamaseli. Ukwakheka kwawo kwamakhemikhali okuhlukile kuzivumela ukuba zishintshe kakhulu futhi zizihlele kabusha ngokushesha njengoba kudingwa iseli.
I-Axoneme: izici kanye nokwakheka
I-axoneme iyisakhiwo esikhethekile esitholakala ku-cilia ne-flagella yamangqamuzana e-eukaryotic. Iqukethe ukuhlelwa kwesici sama-microtubules ahlelwe ngephethini ethi "9+2", lapho amapheya ayisishiyagalolunye wama-microtubules azungeza ama-microtubule amabili amaphakathi.
Ngokungeziwe kuma-microtubules, i-axoneme iqukethe namaprotheni asesekeli afana nama-dyneins nama-nexins, adlala indima ebalulekile ekuhambeni kwe-cilia ne-flagella. Lawa maprotheni ezimoto avumela i-axoneme ukuthi ifinyeze futhi ikhiqize ukunyakaza, okubalulekile emisebenzini efana nokuhamba kwamaseli kanye nokususwa kwezinhlayiya endaweni ezungezile.
Imisebenzi ebalulekile yama-microtubules ku-cytoplasm: funda mayelana neziyinhloko.
Ama-Microtubules ayizakhiwo ezibalulekile ku-cytoplasm yamaseli futhi enza imisebenzi eminingana ebalulekile. Akhiwe ngama-tubulin dimers, enza ama-filaments angenalutho ahlinzeka ngokusekela kwesakhiwo, enze lula ukuthuthwa kwe-intracellular, kanye nokusiza ekuhlukaniseni amaseli.
Enye yezindima ezibalulekile zama-microtubules ukusebenza njengamathrekhi okuthutha ama-organelles nama-vesicles ngaphakathi kweseli. Amaprotheni ezimoto, afana ne-dynein ne-kinesin, ahamba ngama-microtubules, okwenza kube lula ukuhamba kwempahla ebalulekile emisebenzini ehlukahlukene yamaselula.
Ngaphezu kwalokho, ama-microtubules abalulekile ekwakhekeni kwe-mitotic spindle ngesikhathi sokuhlukaniswa kwamaseli, okuqinisekisa ukusatshalaliswa okufanele kwama-chromosome kumaseli endodakazi. Baphinde babambe iqhaza ekugcineni ukuma kweseli kanye nokunyakaza kwezakhiwo zamaselula ezifana ne-cilia ne-flagella.
I-Axoneme: izici nokwakheka
I-axoneme iyisakhiwo esitholakala ku-cilia ne-flagella, esakhiwe ngama-microtubules ahlelwe ngendlela ethile. Iqukethe ama-microtubule ayisishiyagalolunye azungeze ipheya emaphakathi, okukunikeza isici esithi "9+2".
Ama-microtubules e-axoneme akhiwe nge-tubulin, iphrotheni ebalulekile ekwakhekeni nasekusebenzeni kwayo. Ukuhlelwa kwama-microtubules ku-axoneme kuvumela ukunyakaza kwe-cilia ne-flagella, okuhlinzeka ngokunyakaza kwamaseli aphethe.
I-Axoneme: izici nokwakheka
O axoneme iyisakhiwo sangaphakathi se-cytoskeletal se-cilia ne-flagella esekelwe kuma-microtubules abanika ukunyakaza. Isakhiwo sayo siqukethe ulwelwesi lwe-plasma oluzungeza ipheya lama-microtubules amaphakathi namapheya ayisishiyagalolunye ama-peripheral microtubules.
I-axoneme itholakala ngaphandle kweseli futhi ibambelele ngaphakathi kweseli ngomzimba we-basal. Inobubanzi obungu-0,2 μm futhi ingahluka ngobude ukusuka ku-5 ukuya ku-10 μm ku-cilia kuya kumamilimitha amaningana ku-flagella yezinhlobo ezithile zezilwane, nakuba ngokuvamile ikala u-50 kuya ku-150 μm.
Isakhiwo se-axonal se-cilia ne-flagella silondoloza kakhulu kuzo zonke izinto eziphilayo ze-eukaryotic, kusukela I-Chlamydomonas i-microalgae ku-flagellum yesidoda somuntu.
Izici
Ama-axoneme eningi le-cilia ne-flagella anokumiswa okwaziwa ngokuthi “9 + 2”, okungukuthi, amapheya ayisishiyagalolunye ama-peripheral microtubules azungeze ipheya emaphakathi.
Ama-microtubules kubhangqa ngalinye ahlukile ngosayizi nokubunjwa, ngaphandle kwepheya elimaphakathi, elinama-microtubules afanayo. Lawa ma-tubules ayizakhiwo ezinzile, ezikwazi ukumelana nokuqhekeka.
Ama-Microtubules ane-polarity futhi wonke anohlelo olufanayo, isiphetho esithi "+" sibheke phezulu kanye nesiphetho esithi "-" esisekelweni.
Isakhiwo kanye nokwakheka
Njengoba sesiphawulile, isakhiwo se-axoneme siwuhlelo lwe-9 + 2. Ama-Microtubules amade, ama-cylindrical structures akha ama-protofilaments. Ama-protofilaments wona aqukethe ama-protein subunits abizwa ngokuthi i-alpha tubulin ne-beta tubulin.
I-protofilament ngayinye ineyunithi ye-alpha tubulin ekugcineni, kuyilapho enye ineyunithi ye-beta tubulin. Isiphetho esinetheminali ye-beta tubulin sibizwa ngokuthi "+" isiphetho, esinye isiphetho kungaba isiphetho sika-"-". Wonke ama-protofilaments we-microtubule efanayo aqondiswe nge-polarity efanayo.
Ama-Microtubules aqukethe, ngaphezu kwama-tubulins, amaprotheni abizwa ngokuthi amaprotheni ahlobene ne-microtubule (MAPs). Kupheya ngayinye yama-microtubules aseduze, encane (microtubule A) yakhiwe ngama-protofilaments angu-13.
I-Microtubule B inama-protofilament angu-10 kuphela, kodwa inkulu kune-microtubule A. Ipheya emaphakathi yama-microtubules inosayizi ofanayo futhi ngayinye yakhiwe ngama-protofilament angu-13.
Leli pheya elimaphakathi lama-microtubules linqunywa i-central sheath, iphrotheni exhuma kuma-microtubules we-peripheral A ngokusebenzisa izikhulumi ze-radial. Ama-microtubules A no-B epheya ngalinye ahlanganiswa iphrotheni ebizwa ngokuthi i-nexin.
Ama-microtubules ahlanganisa nezingalo ezimbili ezakhiwe iphrotheni ebizwa ngokuthi i-dynein. Le phrotheni inesibopho sokusebenzisa amandla atholakala ku-ATP ukushayela ukunyakaza kwe-cilia ne-flagella.
Ngaphandle, i-axoneme imbozwe i-ciliary noma i-flagellar membrane enesakhiwo nokwakheka okufanayo nolwelwesi lwe-plasma lweseli.
Okuhlukile kumodeli ye-axoneme ethi “9 + 2”
Nakuba ukwakheka kwe-“9 + 2” ye-axoneme ilondolozwe kakhulu kumaseli e-eukaryotic amaningi a-ciliated kanye/noma ahlabayo, kukhona okuhlukile kule modeli.
Esidodeni sezinye izinhlobo zezilwane, i-microtubules emaphakathi ayikho, okuholela ekucushweni kwe-"9+0". Ukunyakaza kwe-Flagellar kulawa ma-sperm akubonakali kuhluka kakhulu kulokho okubonwa kuma-axonemes ngokucushwa okuvamile, ngakho-ke kukholakala ukuthi lawa ma-microtubules awadlali indima enkulu ekunyakazeni.
Le modeli ye-axoneme iye yabonwa esidodeni sezinhlobo ezinjengezinhlanzi I-Lycondontis kanye nama-annelids ohlobo I-Myzostomum .
Okunye ukumisa okubonwa kuma-axoneme ukucushwa kwe-"9 + 1". Kulokhu, i-microtubule eyodwa ephakathi ikhona, kunokuba i-pair. Kulezi zimo, i-microtubule ephakathi iguqulwa kakhulu, iveza izindonga eziningana ezigxilile.
Le phethini ye-axoneme iye yabonwa kuma-gametes wesilisa wezinhlobo ezithile ze-flatworm. Nokho, kulezi zinhlobo zezilwane, le phethini ye-axoneme ayiphindaphindeki kwamanye amangqamuzana ayi-ciliated noma izinto eziphilayo ezifuywayo.
Indlela yokunyakaza ye-Axoneme
Ucwaningo lokunyakaza kwe-flagellar luye lwabonisa ukuthi ukuguquguquka kwe-flagellar kwenzeka ngaphandle kokufinyela noma ukufinyezwa kwama-axoneme microtubules. Ngenxa yalesi sizathu, isazi se-cytologist u-Peter Satir uhlongoze imodeli yokunyakaza kwe-flagellar ngokusekelwe ekuthuthweni kwe-microtubule.
Ngokwale modeli, ukunyakaza kufinyelelwa ngokugudluzwa kwe-microtubule eyodwa isuka kubhangqwana ngalinye iye kumlingani wayo. Lo modeli ufana nokushelela kwamaketanga e-myosin ku-actin ngesikhathi sokufinyela kwemisipha. Ukunyakaza kwenzeka phambi kwe-ATP.
Izingalo ze-dynein zigxile ku-A microtubule yepheya ngayinye, iziphetho zazo ziqondiswe ku-B microtubule. Ekuqaleni kokunyakaza, izingalo ze-dynein zinamathela endaweni yokuhlangana ku-B microtubule. Khona-ke, kwenzeka ushintsho ekucushweni kwe-dynein okudonsa i-microtubule ye-B phansi.
I-Nexin ibamba ama-microtubules amabili eduze. Kamuva, izingalo ze-dynein zihlukana ne-B microtubule. Bese bephinda bajoyina ukuze baphinde inqubo. Lokhu kushelela kwenzeka ngokushintshana phakathi kolunye uhlangothi lwe-axoneme nolunye.
Lokhu kugudluzwa kwe-axoneme ukusuka kolunye uhlangothi kuya kolunye kubangela ukuba i-cilium, noma i-flagellum, igobe kuqala iye kolunye uhlangothi bese iye kolunye uhlangothi. Inzuzo yemodeli ye-Satir yokunyakaza kwe-flagellar ukuthi izochaza ukunyakaza kwe-appendage kungakhathaliseki ukuthi ukumiswa kwe-axoneme kwama-axoneme microtubules.
Izifo ezihlobene ne-Axoneme
Ukuguqulwa kofuzo okuningana kungabangela ukukhula okungavamile kwe-axoneme. Lokhu okungavamile kungase kuhlanganise, phakathi kokunye, ukuntuleka kwengalo eyodwa ye-dynein, ngaphakathi noma ngaphandle, kwama-microtubules amaphakathi, noma izikhulumi ze-radial.
Kulezi zimo, i-syndrome ebizwa ngokuthi i-Kartagener syndrome iqala, lapho abantu abaphethwe yiyo beyinyumba ngoba isidoda asikwazi ukunyakaza.
Lezi ziguli zibuye zithuthukise i-viscera endaweni ehlanekezelwe uma kuqhathaniswa nesimo sazo esivamile; isibonelo, inhliziyo itholakala kwesokudla somzimba futhi isibindi kwesokunxele. Lesi simo saziwa ngokuthi i-situs inversus.
Labo abaphethwe i-Kartagener syndrome bavame ukungenwa izifo zokuphefumula kanye ne-sinus.
Esinye isifo esihlobene nokuthuthukiswa okungavamile kwe-axoneme isifo sezinso ze-polycystic. Kulesi simo, ama-cysts amaningi akhula ezinso, ekugcineni abhubhise izinso. Lesi sifo sibangelwa ukuguqulwa kwezakhi zofuzo ezihlanganisa amaprotheni okuthiwa ama-polycystins.
Izinkomba
- M. Porter noW. Sale (2000). I-axoneme engu-9 + 2 ihlanganisa ama-dynein amaningana angalo angaphakathi kanye nenethiwekhi yama-kinases nama-phosphatase alawula ukuhambahamba. Ijenali ye-Cell Biology.
- I-Axoneme Ku-Wikipedia Retrieved from en.wikipedia.org.
- G. Karp (2008). Ibhayoloji yamaselula namangqamuzana. Imiqondo kanye nokuhlola. 5 th Uhlelo. John Wiley & Sons, Inc. Izinkampani
- S. L. Wolfe (1977). I-Cellular Biology, i-Omega Publishing, Inc.
- T. Ishikawa (2017). Isakhiwo se-Axoneme se-Motile Cilia. I-Cold Spring Harbor Perspectives ku-Biology.
- U-RW Linck, H. Chemes no-D. F. Albertini (2016). I-axoneme: amandla aqhuba isidoda ne-cilia kanye nama-ciliopathies ahlobene aholela ekungazali. Ijenali Yokusizwa Ukuzala kanye Nezakhi Zofuzo.
- S. Resino (2013). I-cytoskeleton: i-microtubules, i-cilia, ne-flagella. Kubuyiswe ku-epidemiologiamolecular.com