海洋觀察🌊🐡
【從牙齒到喙】
亞歷山德拉·羅斯（Alexandra Rose）
(河豚=以下稱為：雞泡魚)
我們對河豚(俗稱: 雞泡魚)的認識大多為刺身美食及毒性無比。
而原來雞泡魚的牙齒亦很有魅力。
【雞泡魚一生都在長牙齒 而且堅硬無比】
常有人把雞泡魚的嘴巴形容為「老虎鉗子」，如果你將一根鐵絲伸到雞泡魚嘴裡的話，它能一節一節地把它咬斷，據說一斤重的雞泡魚就可以咬斷6號鐵絲（直徑4.88毫米），所以千萬不要拿手指頭去試雞泡魚嘴巴的咬合力，不然你的手指頭很可能會被切掉一截。
雞泡魚的嘴巴之所以如此厲害，不單是因為它的牙齒非常堅硬，也是因為其牙齒部位有著特殊的構造，看上去和鳥的嘴巴結構很像，而且上頜和下頜的牙齒看上去各自是兩片，實際是連在一起的，雞泡魚的嘴巴部位肌肉發達，可以給予牙齒以極強的切削功能，因此雞泡魚就連鐵絲也能咬斷了。
雞泡魚是地球上一種最具魅力但最有毒的脊椎動物，而牠最突出和可識別的特徵之一是牠們的大牙齒，或更準確地說是「喙」。而有沒有想過雞泡魚也可以教給我們有關牙科的知識？
河豚= 雞泡魚屬於拉丁語「四齒龍科」
（Tetraodontidae），「四齒」之所以得名，是由於四個部分融合的板狀齒而形成了堅韌的喙，而不是大多數其他硬骨魚擁有的輪廓齒。 牠們使用這種堅硬的喙將食物粉碎和磨碎，這些食物主要包括貝類、棘皮動物、甲殼類動物以及所有其他形式的鈣質無脊椎動物。
而進食這類的海洋生物，往往會令牙齒帶來極大的磨損，所以，雞泡魚的牙齒一直在生長。
這種不段長牙的特技，正正受到科學家的關注。我們只有兩套需要持續一生的牙齒。 到十二歲時，大多數人的所有乳牙（或乳齒）都被一整套較大的永久性牙齒所取代，這些牙齒必須再保持多八到九十年的功能。當人類的壽命比較短時，一套「成年牙齒」就足夠了，但是由於科學的進步和先進的醫療保健，大多數人的壽命已超過牙齒的耐用性。 為了給我們人類提供一種再生牙科，目前正在進行研究，以尋找一種方法來確定魚類如何能夠連續生長牙齒並將其應用於人類。
據謝菲爾德大學動植物科學系的進化生物學家Gareth Fraser博士說，我們可以將雞泡魚的喙作為簡化牙齒替換系統的模型。 Gareth博士說：「科學對了解牙齒的置換過程，了解控制牙齒持續供應的基因以及牙齒幹細胞維持機制的興趣極大。」在雞泡魚長出典型的喙之前，其初始牙列與大多數其他骨魚相似。 這些主要的牙齒最終掉出，四顆不斷替換的牙齒取代了它們，形成了喙的結構。 每隻「牙齒」都由水平生長的幾層骨頭狀物質（稱為牙本質）組成，不斷產生這種物質是為了替代因吃堅硬食物而磨損的舊層。
弗雷澤（Fraser）博士及其團隊最近鑑定出了負責這種持續再生的所謂「牙仙子」細胞。 進一步的研究旨在發現造成這種情況的確切遺傳和分子機制，希望我們可能能夠刺激人類中的相似細胞，從而使我們在需要時能夠長出更多的牙齒。 弗雷澤（Fraser）認為，人類甚至有進化的可能性，望有一天人類的牙齒可能會演變成雞泡魚般的喙。 與牙齒不同，喙不易受到崩裂，腐爛或掉落的危害。 當然，這種進化變化至少需要花費數百萬年的時間，因此與此同時，我們最好繼續拜訪牙醫，並妥善保管我們的一組非再生牙齒。
未來預告：
1.河豚(雞泡魚)的簡化牙齒替換系統是人類的參考模型指標。
2.刺激人類中類似的細胞，使我們能夠在需要時生長出更多的牙齒。
原文內容：
《Ocean Geographic》:Facebook & IG
Ocean Watch
“From Teeth to Beaks”
By Alexandra Rose
Breakout lines
- HUMAN CAN USE THE PUFFERFISH beak as a model for a simplified tooth replacement system.
- Stimulate similar cells in humans, allowing us to GROW EXTRA SETS OF TEETH WHEN NEEDED.
Puffer fish, some of the most charismatic yet poisonous vertebrates on the planet, could have important evolutionary lessons to teach us about dentistry. One of the most prominent and recognizable features of puffer fish is their large teeth, or more accurately beaks, for which they are named. Puffers belong to the family Tetraodontidae, Latin for “four teeth”, and are thus named due to the presence of four partially fused plate-like teeth that form a tough beak instead of the delineated teeth possessed by most other teleosts. They use this hard beak to crush and grind up their food, which consists primarily of shellfish, echinoderms, crustaceans, and all other manner of calcareous invertebrates. This type of abrasive diet puts an extreme amount of wear and tear on their teeth, which conveniently have the ability to grow continuously throughout the fish’s lifetime.
This process of vertebrate tooth replacement, referred to as odontogenesis, is of particular interest in the field of dentistry because as humans, we only get two sets of teeth that need to last us our entire lives. By the time we reach age twelve, most humans have all their primary teeth (or “baby teeth”) replaced by a full set of larger, permanent teeth which must then remain functional for another eight or nine decades. One set of “adult teeth” was sufficient when human lifespans were much shorter, but due to scientific advancements and sophisticated medical care, most people outlive the durability of their teeth. In an effort to provide our species with a form of regenerative dentistry, research is currently underway, to find a means to determine how fish are able to grow teeth continuously and apply it to humans.
According to Dr. Gareth Fraser, an evolutionary biologist in the University of Sheffield´s Department of Animal and Plant Sciences, we can use the puffer fish beak as a model for a simplified tooth replacement system. “It is of great interest for science to understand the process of tooth replacement, to understand the genes that govern the continued supply of teeth and mechanisms of dental stem cell maintenance,” Dr Gareth says. Before puffers grow their characteristic beak, their initial dentition is similar to that of most other bony fishes. These primary teeth eventually fall out and four continually replacing teeth take their place to form the structure of the beak. Each “tooth” is comprised of several horizontally growing layers of a bone-like substance called dentine that is constantly being produced in an effort to replace older layers worn out by eating tough foods.
Dr. Fraser and his team have recently identified the so-called “tooth fairy” cells responsible for this constant regeneration. Further research aims to discover the precise genetic and molecular mechanisms responsible for this, with hopes that we may be able to stimulate similar cells in humans, allowing us to grow extra sets of teeth when needed. Fraser feels that there may even be an evolutionary possibility that human teeth could someday evolve into puffer-like beaks. Unlike teeth, a beak would not be susceptible to the demises of chipping, rotting, or falling out. This kind of evolutionary change would of course take at least several million years, so in the meantime, we had all best continue going to our dentists and taking good care of our single set of non-regenerative teeth.
