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以分子與細胞的角度建立探討腎形紋葉珊瑚有性生殖機制的工具和技術

為了解決pg soft - medusa的問題，作者邱顗陵 這樣論述：

數十年來，石珊瑚的有性生殖引起了許多研究者和大眾的注意，在珊瑚生態學的研究中已有許多珊瑚有性生殖的資料，但珊瑚有性生殖的內在機制仍然不清楚，只有少數的研究指出珊瑚配子生成過程和產卵相關的基因和激素/類激素物質。本研究為以分子與細胞的角度建立探討珊瑚有性生殖機制的工具和技術。以腎形紋葉珊瑚Fimbriaphyllia ancora為實驗物種，建立F. ancora生殖腺轉錄體資料庫，當作研究珊瑚配子生成過程中分子和細胞機制的基礎，瞭解性別和階段特異性基因的表現情況和找到與卵母細胞發育/成熟、精子發生和精子運動/獲能相關的基因(第2章)。接著建立F. ancora生殖腺細胞分離及分散F. anc

ora的精巢組織的技術，利用內生性的綠色螢光蛋白(GFP)作為精巢體細胞的標記蛋白，分離出精巢體細胞和生殖細胞(第3章)。為了未來的功能性試驗，建立F. ancora建立卵巢的體外培養系統，篩選出適當的培養條件並培養卵巢，其可以在體外存活且維持卵巢結構6天(第4章)。這些工具和技術都是在珊瑚研究中首次被建立的，這些數據、工具及技術提供了研究珊瑚有性生殖內在機制的基礎。

藤壺幼體游泳機制學

為了解決pg soft - medusa的問題，作者王敬湧 這樣論述：

Adult barnacles display fascinating morphological variations and are adapted to a wide range of habitats, in some cases little morphological similarities are left in extremely modified taxa. Larval characters, such as the presence of frontal horns on nauplius larvae and the presence of an additiona

l distinct cypris larva in life cycle, have served to define the monophyly of this diverse group. However, the functional significance of these taxonomically important larval characters remains little understood. Barnacle nauplii swim to disperse, feed, and avoid predators. While the limbs are clear

ly involved in propelling their body through water and drawing food particle laden water towards their feeding apparatus, there has been few mechanistic studies showing empirical evidence of flow manipulation. By analyzing small scale hydrodynamics around swimming barnacle larvae, this thesis aimed

at resolving fundamental questions on how barnacle larvae interact with surrounding water to swim and feed, and to examine the morphology-flow relationships with emphasis on the consequences of having frontal horns and transition into a distinct cypris larva. A comparative analysis of naupliar body

forms from 102 species of barnacles with geometric morphometrics shows that major variations are in aspect ratio and relative frontal horns length, which are significantly explained by larval size and trophic modes, respectively. Specifically, nauplii adopted a lecithotrophic trophic mode (non-feedi

ng) have relatively shorter frontal horns than planktotrophic (feeding) nauplii, suggesting a possible feeding-related function. Observation of swimming planktotrophic nauplii by particle image velocimetry technique shows that nauplii depended on feeding current generated during recovery stroke to d

raw particles towards body. This observation confirms the long proposed ‘hypothetical’ feeding flow as feasible mechanism for nauplius to swim and feed simultaneously. Compared to lecithotrophic nauplii with shorter frontal horns, planktotrophic nauplii had less backward movement during recovery str

oke, which in turn help align the feeding chamber with suction current. However, the accurate feeding aided by ‘anchoring effect’ from having a high drag morphology with long frontal horns and tail spine was achieved at the cost of having slower swimming and higher predation risk than lecithotrophic

nauplii due to pronounced fluid signal produced. To confirm the ‘anchoring effect’ of frontal horns, nauplii’s frontal horns were experimentally ablated. Nauplii with frontal horns ablated swam with relatively higher backward movement during recovery stroke than intact nauplii, after accounting for

individual variability in swimming speed. Flow paths of suction current produced by the ablated group also appeared to be straight, as oppose to the curved flow paths laterally converging to nauplius’ body observed in the intact group. Analysis of flow field component perpendicular to nauplius’ bod

y axis confirmed the intact group did indeed draw water from a significantly wider area than the ablated group, which increase water clearance for food particles. Zooplankton morphology with long projecting spines that is sub-optimal for swimming performance has long perplexed biologists. These find

ings support the hypothesis that such morphological traits confer feeding advantage but at the cost of swimming. The swimming-feeding tradeoffs has the potential to affect morphological evolution of larval form not only between taxa, but also through larval development as relative importance between

swimming and feeding shift. Barnacles end larval period with a distinct non-feeding larval phase that specialized in settling onto substrate to complete their transition into sessile adults, which requires better swimming capability. Comparison of swimming between nauplii and cyprids shows that cyp

rids were better swimmer capable of moving more body length per beat cycle through maximizing relative duration of power stroke and asymmetry in appendages’ configuration between power and recovery stroke. Given the streamlined fusiform shape and swimming kinematics, cyprids generated fluid field di

stinctive from that of the nauplii, and in particular with little return flow during recovery stroke. This shift to become better swimmers compromise cyprids ability to feed, highlighted the change in ecological role and requirement during development could shape larval morphology and kinematics. No

tably, this change of swimming performance between nauplius and cyprid does not involve an increase in size, indicating that morphological change alone is sufficient to result in performance shift, without the switch from viscosity-dominated to inertia-dominated fluid regimes through coupled change

in size and shape commonly seen during larval development of other marine invertebrates. In summary, this thesis shows that biomechanical constraints are important in shaping evolution of taxonomically important larval characters in the model system of barnacle larvae.