紅錐蝽卵子發生過程中胞外H+轉運動力學的研究
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卵子發生在生物體形成過程中非常重要，影響到胚胎的發育以及個體的形成，在這個過程中，H+動力學起到一個關鍵的調節作用，細胞通過H+轉運維持膜電勢和產生跨膜的化學梯度來驅動次級代謝，但是在昆蟲滋養型卵母細胞成卵過程中發生的H+流的變化和H+流引起的pH值變化所起到的調節作用卻了解很少。利用“非損傷微測技術”可實現對H+流在不同時間和空間的實時監測，從而揭示H+流在昆蟲滋養型卵母細胞生成過程中所起到的調節作用。 美國Wadsworth中心神經系統失調研究實驗室科學家Bjornsson C. S.等采用“非損傷微測技術”對紅錐蝽（Rhodnius prolixus）在相同生長部位的不同生長階段進行胞外H+流實時監測發現，卵黃生成中期卵巢管中分離相鄰卵泡囊的主莖表現出顯著的H+外流，而在卵黃生成后期H+外流減弱。H+外流的現象不僅在主莖生成之前已經產生，而且先于鄰近卵泡囊的卵黃生成起始階段。另外在生成絨毛膜的末端卵泡囊和卵泡囊排卵后也分別檢測到了H+的外流現象，這揭示了軀體的卵泡上皮細胞控制著H+的外流。 |
 上圖： 上圖是通過非損傷微測技術在卵巢管不同部位不同生長時期檢測到的H+流的變化情況。正值為外流，負值為內流。 | |||
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該研究通過非損傷微測技術檢測昆蟲成卵過程中H+流的變化，揭示了H+流在卵黃生成的起始階段、內吞、卵泡細胞骨架動力學及濾泡反饋機制調節中的重要作用，跨膜H+流可促使胞內pH值的改變。這為昆蟲成卵過程的機理研究提供了新穎的思路和方法。 | ||||
關鍵詞：H+, 離子選擇電極(ion-selective probe) , 卵子發生(oogenesis)
參考文獻：Bjornsson CS, et al. The Journal of Experimental Biology,2004, 207, 2835-2844
全文下載：http://jeb.biologists.org/cgi/content/abstract/207/16/2835
Abstract:
The spatiotemporal dynamics of transmembrane hydrogen ion (H+) fluxes during oogenesis were investigated in the telotrophic ovarioles of the insect, Rhodnius prolixus. Although Rhodnius ovarioles possess exaggerated morphological and electrical polarity between nurse cells and oocytes, little is known about H+ changes during oogenesis, despite the regulatory role played by H+ and pH in many relevant cellular processes. A number of dynamic extracellular H+ fluxes were measured along Rhodnius ovarioles, representing an oogenesis cycle, using a non-invasive, self-referencing, H+-selective probe. The interfollicular stalk separating adjacent follicles exhibited prominent H+ efflux that peaked during midvitellogenesis and declined during late vitellogenesis. H+ efflux in this region preceded stalk formation and, importantly, preceded the onset of vitellogenesis in the adjacent posterior follicle. H+ efflux was also observed over the terminal follicle, where specialized regions of the chorion were forming, and was still detected around follicle cells after ovulation, indicating that the somatic follicular epithelium produced this flux. Transmembrane H+ fluxes may drive intracellular pH changes or may stabilize pHi in response to pH-altering events. H+ fluxes may play a role in processes that coincide spatially and temporally, including the onset of vitellogenesis, endocytosis, follicle cell cytoskeletal dynamics, and regulation of interfollicular feedback mechanisms.
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