Abstract
蜜蜂是生物界中沈積鐵最旺盛的生物之一，是目前唯一被證實可在細胞內沈積鐵礦物的真核生物，是研究細胞內鐵沈積的最佳系統之一。再者，蜜蜂也是生物行為被研究最清楚的生物之一，也是研究磁場導航的最佳系統之一。雖然，蜜蜂的築巢及飛行舞蹈的方式會受地球磁場的影響而本身又擁有天然磁量及含鐵顆粒，然而，鐵顆粒的序列沈積過程及是否確有磁鐵沈積則未被證實，本論文以電子顯微鏡，定量分析的技術研究蜜蜂的鐵沈積以及闡明蜜蜂沈積磁鐵及磁場感應的機制。研究蜜蜂鐵沈積的生物礦化作用過程發現：(1) 蜜蜂的鐵沈積作用開始於工蜂羽化後的第二天；(2)鐵沈積作用發生在營養細胞的鐵沈積囊胞內，其內的固形鐵顆粒由直徑7.5 nm的微細粒子聚集而成；(3) 在鐵沈積囊胞膜的內方有一層霧狀區域，可能是生物礦化作用進行的地方； (4) 固形鐵顆粒體積之增大除了靠同一鐵沈積囊胞內微小鐵顆粒的繼續聚集外，也藉囊胞彼此癒合而增大；(5) 工蜂與雄蜂的鐵顆粒是均勻分散在細胞質內，而蜂王的鐵顆粒則是集中在細胞的角落；(6) 每隻成熟工蜂的鐵顆粒總含鐵量為0.13±0.01μg，佔其體內總鐵量的1％及約佔蜂期所增加鐵量的３％。研究固形鐵顆粒是否含磁鐵及蜜蜂磁場導航的機制發現：(1) 部份固形鐵顆粒的內部有一些約10nm大小的超順磁的磁鐵；(2) 神經末梢分布至鐵沈積細胞群神經突觸也與營養細胞緊密結合；(3) 一些細胞骨架與鐵沈積囊胞的膜鍵結在一起，鍵結點是一種粗短的柱狀構造。研究群居性蜂類與獨居性蜂類在鐵沈積上的差異發現：(1) 在群居性蜂類的成員中除過去已知的蜜蜂和熊蜂(~BI2;Bombus~I; sp.)外，虎頭蜂(~BI2;Vespa affinis ~I; Linnaeus)和長腳蜂(~BI2;Polistes rothneyi~I; Cameron) 的營養細胞內有鐵顆粒的沈積；(2) 獨居性蜂類的成員中，木匠蜂 (~BI2;Xylocpa~I;~BI2;tranquebarorum~I; Swederus) 和細腰蜂 (~BI2; Secliphron~I; ~BI2;madraspatanum~I; Fabricius)的營養細胞內有鐵顆粒的沈積，但黃面蜂(~BI2;Anterhynchium ~I; ~BI2;flavomarginatum~I; Linnaius)和螺嬴(~BI2; Eumenes arcuata~I; Kirsch)則無鐵的沈積。本文分五章：第一章前言；第二章蜜蜂鐵顆粒的發育過程及超微構造；第三章蜜蜂的磁鐵及磁場感應；第四章群居蜂與單獨蜂在鐵沈積上的差異；第五章結論。Honeybees are one of the organisms which are able to depositiron minerals and are the only eukaryotic organism which hasbeen identified to deposit iron intracellularly. Therefore,honeybees are an ideal system to study intracellular ironbiomineralization. Furthermore, the behavior of honeybees hasbeen clearly studied and proven to use magnetoreception. Themagnetoreception of honeybees has been previously demonstratedthrough activities such as comb-building and homing orien-tation that are affected by the geomagnetic field and thefinding of magnetic remanence and iron granules. However, thedetailed events of iron biomineralization and magnetite havenot yet been found in honeybees. Experiments reported in thisthesis were designed for studying the cellular and biochemicalevents in iron biomineralization as well as elucidating on themechanism of magnetite biomineralization and magnetoreceptionin the honeybees. A variety of techniques in electronmicroscopy and quantitative analysis were employed This thesisis divided into five chapters: chapter I general introduction;chapter II the ultrastructure and formation of iron granules inthe honeybee (~BI2;Apis mellifera~I;); chapter IIImagnetoreception in honeybee (~BI2;Apis mellifera~I;); chapterVI iron biomineralization in social bees and solitary bees;chapter V general discussion.