偷竊寄生 kleptoparasitic

最近在看一篇文獻的時候，看到一個有趣的名詞：kleptoparasitic。

kleptoparasitic翻成中文就是「偷竊寄生」，字首klept(o)-源自希臘文kleptein，意為「偷竊」（to steal）。

寄生（parasitism）大家都知道是什麼，但是偷竊寄生是一種怎樣的生活形態呢？以肖稗稈蠅屬（Desmometopa）的昆蟲為例，這一屬的蠅，會在牠的宿主（如西方蜜蜂 Apis mellifera）被掠食者攻擊的時候，趁掠食者（如蜘蛛）不注意，在旁邊偷偷搶點蜜蜂的腸子等等。

雖然鬣狗（hyena）有時也會跟在其他掠食者的旁邊偷點東西吃，但偷竊寄生的動物可是專業的在扮演「你吃肉我喝湯」的角色。尤其牠們的雌性，因為卵子的製造需要消耗大量的養分，他們可是孜孜不倦地在找機會呢。

牠們為了找機會，當然就要發展出一套偵測系統，快速而準確的偵測出附近有沒有宿主受到攻擊；由於蜜蜂在受到攻擊時會發出費洛蒙，這些蠅便發展出費洛蒙偵測系統，可以在幾秒內偵測到並展開行動。

降落傘花。圖片來源：Wiki

沒想到牠們對費洛蒙的敏感性，卻被降落傘花（parachute plant，Ceropegia sandersonii）給利用了。因為降落傘花具有花粉器（pollinaria）這種傳粉的構造，而花粉器因為重量的關係，昆蟲如果太小隻是幫不上忙的。因為這一屬的蠅夠大，所以降落傘花就發出西方蜜蜂受攻擊時產生的費洛蒙，把蠅兒給騙進來。

受騙的蠅兒，因為降落傘花的形狀的關係，一進去就被關在裡面了。不過別緊張，一天以後花謝了，蠅兒就脫困了：而植物傳宗接代的重責大任也完成了！

在被子植物裡面，根據目前的估計，有百分之四到六都是靠騙的來完成傳宗接代的任務。若以邱園2016年的報告中被子植物的總數（369,000種）乘以百分之五來計算，也就是說世界上有18,450種植物是「以騙維生」的喔！

參考文獻：

張彥華、曾喜育、曾彥學。臺灣產牛皮消屬植物花粉器形態之研究。林業研究季刊 34(4):251-262, 2012.

S. D. JohnsonT. J. Edwards.The structure and function of orchid pollinaria. Plant Systematics and Evolution March 2000, Volume 222, Issue 1, pp 243–269.

Heiduk et al., Ceropegia sandersonii Mimics Attacked Honeybees to Attract Kleptoparasitic Flies for Pollination, Current Biology (2016), http://dx.doi.org/10.1016/j.cub.2016.07.085

Royal Botanical Gardens Kew. State of the World's Plants 2016.

碳氫化合物的名稱

在製作第二課測驗解說時，
想到應該要補充一下碳氫化合物的稱呼。

為什麼？因為從一到四個碳的碳氫化合物的命名，並不遵守我們第一課說的規則喔！

先來看一下影音資料：

甲烷是methane，不是monane；（甲烷的故事）
乙烷是ethane，不是bisane或diane（要是這名字就糟了）（乙烷的故事）；
丙烷是propane；（丙烷的故事）
丁烷是butane；（丁烷的故事）
不過從五，也就是戊烷開始，就回歸到原來的命名，所以是pentane；不過戊烷有個俗稱 amyl alcohol（戊烷的故事）
己烷（你「擠完」了沒有？XD）是hexane；
庚烷是heptane；
辛烷是octane。

「遠方的聲音」-電話（Distance voice - telephone）

1892年，貝爾從紐約打電話到芝加哥
圖片來源：Wikipedia

1876年三月，貝爾（Alexander Graham Bell）獲得了電話在美國的第一個專利。不過，電話「telephone」這個字，其實也是字首與字尾拼起來的呢！
In March 1876, Alexander Graham Bell was awarded a patent for the electric telephone by the United States Patent and Trademark Office (USPTO). It was the first patent to be awarded for telephone.

字首tele-是「遠方」的意思；而字尾-phone是「聲音」的意思。兩個字合起來就是「遠方的聲音」的意思！
The prefix tele- means "distant" and the suffix -phone means "sound, voice". The actual meaning for "telephone" is "distant voice".

不過，電話並不是第一個使用telephone這個詞的器具。在1844年，約翰‧泰勒船長（John Taylor）發明了用四個空氣喇叭讓船隻在大霧中還可以互相聯絡的方法，而telephone這個詞就是他發明的。而1860年約翰‧菲力普‧雷斯（Johann Philipp Reis）發明了原形電話，可以將聲音轉成電波。
However, the word "telephone" was not invented by Bell. Caption John Taylor invented this word on his invention for using for air horns to communicate with vessels in foggy weather. Johann Philipp Reis invented Reis Telephone in 1860, which was the first instrument that can convert voice into electrical impulses.

參考文獻 References：

Wikipedia. telephone

口臭 halitosis

圖片來源：Wikipedia

halitosis這個自來自於拉丁文的halitus，這個字第一次出現是在1874年，意思是呼吸，不過比較強調呼氣的部分（breath, exhalation, steam, vapor）；它與拉丁文的 halare （意為呼吸，一樣是著重在呼氣的部分： to breathe, emit vapor）。而字尾 -osis 在第二十三課（一）學過，是與疾病有關的字尾。一樣跟呼吸有關有個字尾 -pnea，它是由希臘文的 pnoia來的，意思也是呼吸（breath)，在第二十五課（二）有學到。

The word "halitosis" was first appeared in 1874. Halitosis means "bad breath". The word is originated from Latin halitus, meaning breath, exhalation, steam, vapor. It is related to halare (to breath, emit vapor). There is a suffix "-pnea" also meaning breath and it is originated from Greek pnoia (breath). We learn that in Lesson 25-2.

根據維基百科的資料，口臭是看牙醫的第三名的理由；第一名是蛀牙、第二名是牙齦問題；世界上大約有兩成的人有口臭的問題，使得任何可以消除口臭的東西（口香糖、breath mint）都大行其道。

According to Wikipedia, halitosis is the third most frequent reason for people to seek dental care, following tooth decay and gum disease. Because about 20% of the general population are reported to suffer from it to some degree, anything that claim to be able to reduce halitosis (chewing gum, breath mint) are quite popular.

並非所有自認為有口臭的人都有口臭的問題：大約有5-72％因口臭而求診的病患，在專業檢查時並沒有真正的口臭。真的有口臭的人，往往是在齦或舌頭背面的細菌造成的。其他10％是由鼻腔、鼻竇、咽喉、肺、食道、胃或其它地方疾病造成。

Not all who think they have halitosis really have it. Significant percentages (5–72%) of people who suspect that they have halitosis have been reported not to have genuine halitosis when examined by professionals. Most of the occasion of halitosis (about 90%) is caused by bacteria present below the gumline and on the back of the tongue. The remaining 10% could be resulted from disorders in the nasal cavity, sinuses, throat, lungs, esophagus, stomach or elsewhere.

參考文獻 References：

Wikipedia. Halitosis.
Merriam-Webster Dictionary.
Online Etymology : halitosis.

What's the relationship between oxygen and sour?

In Lesson 17-1, we learned the prefix of oxygen. They are:

ox-, oxy-

We also learned that the prefixes for sour or sharp taste are the same. How come?

Antoine Lavoisier. Source: Wikipedia

The reason why oxygen and sour/sharp taste use the same prefixes has a lot to do with Antoine Lavoisier.

Although other scientists like Joseph Priestley and Carl Wilhelm Scheele complained that Lavoisier was not the first one who found oxygen, he was the first person to conduct the first adequate quantitative experiments on oxidation and give the first correct explanation of how combustion works.

He discredited the 'phlogisticated air' theory, noting that after he burned elements like phosphorus, mercury and sulfur, the overall weight did not change at all. When he heated red calx (mercury oxide, HgO), this substance is being released back into the air.

Because the compound generated from burning phosphorus, mercury or mercury are acidic, he named this 'vital air' to 'oxygen', mistakenly thought oxygen is the constituent of all acids. Chemists in 19th century proved that hydrogen is the component of all acid, but by then the name is too well established.

Lovoisier was killed in the French Revolution. According to a (probably apocryphal) story, the appeal to spare his life so that he could continue his experiments was cut short by the judge: "La République n'a pas besoin de savants ni de chimistes; le cours de la justice ne peut être suspendu." ("The Republic has no need of scientists or chemists; the course of justice cannot be delayed.")

中文版

What is the relationship between halogens and salts?

In Lesson 17-4, we learned that functional groups containing chlorine (Cl) are using the prefix hal(o)-. As a matter of fact, fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) are called the halogens or halogen elements collectively.

However, we learned that the suffix hal(o)- meaning sea or salt in Lesson 18-2. Are they using the same prefix? Why is that?

The reason why elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) are called the halogens is because when they react with metals they produce a wide range of salts, including calcium fluoride, sodium chloride (common salt), silver bromide and potassium iodide. Therefore, they are name halogens, meaning 'salt-producing'. The suffix -gen means 'produce', which we learned in Lesson 16-5.

Jöns Jakob Berzelius. Source: Wikipedia

This name was suggested by Swiss chemist Jöns Jakob Berzelius in 1842. However, the term halogen was created by Johann Salomo Christoph Schweigger at 1811. It was suggested for naming chlorine at the time, but it was not used. Later, the term was used by calling all of the element of  group 17 -- including chlorine.

中文版

Why cyanide and blue share the same prefix?

After learning Lesson 17-4, you may become curious why cyanide and the color blue share the same prefix. It is:

cyan(o)-

The reason why they share the same prefix is because it is being firstly obtained by the heating of the pigment known as Prussian blue.

Prussian blue. Source: Wikipedia

Prussian blue is a dark blue pigment with the idealized chemical formula Fe ₇(CN) ₁₈. To better understand the binding situation in this complex compound the formula can also be written as Fe ₄[Fe(CN) ₆] ₃ · xH ₂O. It is the first synthetic dye. It also called Berlin Blue or Persian/Paris Blue. It is the traditional "blue" in blueprints.

Prussian blue can be use to treat thallium poisoning. It was synthesized by the paint maker Johann Jacob Diesbach in 1706.

Because cyanide was obtained from Prussian blue at first, it was named cyanide as a reference of blue. The Greek for dark blue is kyanos.

中文版

Reference:

Wikipedia. Cyanide - Nomenclature and Etymology.

This suffix is making me dizzy: -oate

In Lesson 17-4, there is a suffix -oate can be used in :

dissociated type of carboxylic acid (COO^-), and also in ester (R-O-R).

We get confused with acid because the suffix of acid is -ate.

I found that even Google translate has a hard time to differentiate. Last time I was reading an article regarding to 3-methylbutyl pentanoate, 3-methylbutyl 3-methylbutyrate,  3-methylbutyl 2-methylbutyrate, butyl pentanoate and propyl hexanoate. When I checked these five compounds in Google translate, it translated them as acid or ester. Fortunately, they are referred as esters in that article.

Those compounds are the five esters that can be detected in dead and decomposed human cadavers.

Source: Wikipedia

However, -oate is not the worst one. The worst chemical suffix is -ane!

Reference:

E. Cuypers et. al., 2015. The Search for a Volatile Human Specific Marker in the Decomposition Process. PLOS One. DOI: 10.1371/journal.pone.0137341

中文版

Why chlorine and color green use the same prefix chlor(o)- ?

After finished learning Lesson 17-2, I am sure all of you noticing that chlorine (Cl) and color green share that same prefix. It is

chlor(o)-

Why do both of them share the same prefix? There's a story.

The element chlorine was firstly discovered by Carl Wilhelm Scheele in 1774. When he treated the pyrolusite with hydrochloric acid over a warm sand bath, a yellow-green gas with a strong odor was produced. The reaction is indicated as below:


4 HCl + MnO₂ → MnCl₂ + 2 H₂O + Cl₂

However, he did not realize what he got is an element. He thought it is an oxide (also a lot of people at that time), although he did notice this yellow-green gas can make the litmus paper turning blue. He also noticed that this gas can kill bugs.

Humphry Davy. Source: Wikipedia

Humphry Davy repeated his experiment in 1810 and he reckoned it is an element. He named it chlorine because its color. In Greek, chlōros means yellow-green color. Although Johann Salomo Christoph Schweigger suggested that it should be named as halogen, but it is named chlorine. The term "halogen" was later being used to name all of the elements that have similar characteristics as chlorine -- they can all form sea salt-like compound with metals.

Chlorine gas in an glass container. Source: Wikipedia

中文版

Hydrogen and water

You may find it interesting that hydrogen and water use the same prefix. It is:

hydr(o)-

Actually it is related to how hydrogen was discovered.

Hydrogen was discovered by Henry Cavendish. He collected the air bubbles from metal-acid reaction and found this air to be inflammable. He named it "inflammable air", which later was given the name hydrogen by Antoine Lavoisier. Lavoisier name it hydrogen because he obtained water after burning hydrogen. The word "hydrogen" means "substance that produces water" (please refer to Lesson 16-5 for the suffix -gen).

 Cavendish's apparatus for making and collecting hydrogen. Source : Wikipedia

Henry Cavendish was a notoriously shy man, some even postulated that he suffered from autism. However, he achieved a lot.

Henry Cavendish. Source: Wikipedia

Although Cavendish was not the first person to discovered the air bubbles from metal-acid reaction, he was the first person who collected the air and characterized them. Therefore, he was recognized as the person who discovered hydrogen. He also discovered carbon dioxide by dissolving alkali in acids.

中文版

dendroprovenance and dendrochronology

Pueblo Bonito. Source: Wikipedia

Anasazi Indians, who mysteriously "vanish" from the present-day Four Corners region of the United States, comprising southeastern Utah, northeastern Arizona, northwestern New Mexico, and southwestern Colorado in 12 and 13th centuries, left many huge architectural structures in the desert. The biggest one, Pueblo Bonito, is a five-floored building with 500 rooms.

All of those buildings were made by wood. How did Anasazi Indians find so many logs in that region?

Actually, they gathered logs from mountains that are far away. In order to determine where they obtained their building materials, research team checked the strontium (Sr) content in those logs.

Strontium is a decayed product from rubidium (Rb). After rubidium is decayed and strontium is produced, because it is similar to calcium (Ca), it will be absorbed into plant just like calcium. The Rb content in the soil is different in different areas, so scientists can deduce the origin of plant from the Sr content.

From the Sr data, research team determined these logs were from Chuska and San Mateo Mountains. However, dendroprovenance results said otherwise.

Dendroprovenence is a new method developed from dendrochronology. The prefix dendr(o)-, meaning tree, is taught in Lesson 19-1. The middle part of the word, chron(o)-, meaning time, is taught in Lesson 24-2. The last part, the suffix -logy, meas study, science.

Putting them together, dendrochronology means to study the time of the tree.

Source: Ms. Lin

Dendrochronology is used by scientists to study the amount of precipitation in the past. When we chop down a tree (tree A), the outmost ring of tree A represent the amount of precipitation of this very year. Then we can count the rings of the tree. The number of rings tell us how old this tree is. If it has 100 rings, then this tree is 100 years old.

Say we find a log (tree B) also from the same area as tree A. Because precipitation varies year by year, the patterns of thick-and-thin rings in trees that grow in the same area around the same time will be similar because the climate is the same. So if we find one section of tree B is almost identical to one section of tree A, then we can take a good guess about how old tree B is. We can even figure out how long ago tree B was chopped down! This method is called dendrochronology.

As of dendroprovenance, it looks for much smaller details. We knew that precipitation varies year by year and the patterns of tree rings growing in the mountain ranges that surround the same area are similar because the climate is the same. However, each mountain range has its own microclimate. So, if we look more closely to these growth rings, we will find that growth patterns of trees from one mountain range are not identical to those of trees in nearby ranges.

The word provenance means origin or source. Because this method can help scientists find the where are those trees from, it is named dendroprovenance.

In this report, scientists found that some of the trees Anasazi Indians used were obtained from Zuni mountains. However, they switched to Chuska Mountains after 1020 A.D.

Dendroprovenance can be very useful for illegal logging. If we can establish the "fingerprints" of trees in every area, then we can catch those illegal loggers with indisputable evidences!

Reference:

Jared Diamond. 2006. Collapse.(大崩壞)。p.186-7（廖月娟譯）

2015/12/7. Unexpected wood source for Chaco Canyon great houses. Science Daily.

中文版

parthenogenesis: female reproduction without male

What is parthenogenesis?

This word can be split into two part.

The prefix partheno- is from Greek word parthenos, meaning virgin; and the suffix -genesis means production. Put them together, parthenogenesis means sexual reproduction with development of a gamete without fertilization.

Parthenogenesis can be found in some plants and invertebrates, especially arthropods. For vertebrates it was only observed under captivity.

However, in a study done by Stony Brook University, they found that about 3% of the smalltooth sawfish (Pristis pectinata) underwent parthenogenesis.

Smalltooth sawfish. Source: Science Daily

Smalltooth sawfish is one of the large fish living in Florida. It was listed as endangered in 2003 because the population decreased to 1-5% (about 200 individuals left) of 1900.

Concerning about inbreeding, the scientists started to do their DNA fingerprinting. Surprisingly, they found some of the females were reproducing without mating.

There were five of them that are extremely close to each other, according to the DNA fingerprinting result.

In the past, parthenogenesis only happened for sharks in captivity, not to mention those sharks weren't healthy at all.

Perhaps it is a way to preserve the population when the population size is so low. Although parthenogenesis does not help with genetic diversity, it will help to maintain the population size.

Reference:

Andrew T. Fields, Kevin A. Feldheim, Gregg R. Poulakis, Demian D. Chapman. 2015. Facultative parthenogenesis in a critically endangered wild vertebrate. Curr. Biol. 25（11）：R446-R447

中文版

What is hypercapnia?

In November 22, 2015, a woman felt uncomfortable while she was driving through Highway No.3 in Nantou, Taiwan. Because her daughter was fainted in the same vehicle, she called the police.

When the police arrived, they found that she did not turn on the air-conditioning. She switched to circulation, which did not allow fresh air to come in.

I often found it curious why our car has a setting "circulation". Although it can prevent bad smell coming from outside to enter our car, but it also prevent fresh air from coming in. If we drive for a long time and leave the setting on "circulation" (like this woman did), you may suffer from hypercapnia.

What is hypercapnia?

The prefix hyper-, we is from Lesson 6-1, meaning above.

The prefix capn- is introduced in Lesson 17-1, meaning carbon dioxide. It can also be written as capno-, depending on what letter connecting to it.

The suffix -ia is introduced in Lesson 16-4, meaning condition.

Putting them together, hypercapnia is a condition of abnormally elevated carbon dioxide (CO₂) levels in the blood.

According to Wikipedia, hypercapnia normally triggers a reflex which increases breathing and access to oxygen, such as arousal and turning the head during sleep. A failure of this reflex can be fatal, for example as a contributory factor in sudden infant death syndrome.

Symptoms and signs of early hypercapnia include flushed skin, full pulse, tachypnea (abnormally rapid breathing), dyspnea (difficult in breathing), extrasystoles (a heartbeat outside the normal rhythm), muscle twitches, hand flaps, reduced neural activity, and possibly a raised blood pressure. According to other sources, symptoms of mild hypercapnia might include headache, confusion and lethargy. Hypercapnia can induce increased cardiac output, an elevation in arterial blood pressure, and a propensity toward arrhythmias.

Recently, a research paper suggested if the carbon dioxide in the ocean keeps rising, the fish will also suffered from hypercapnia too!

Source: Wikipedia

Hypercapnia is also called carbon dioxide toxicity. It will happen within 30 minutes when the concentration of carbon dioxide reach 6%.

Next time when you are going for a long ride with your family, please remember to check the air-conditioner's setting!

Reference :

民視新聞。2015/11/22。國道驚魂!車內只開循環 女副駕缺氧昏厥。

Wikipedia. Hypercapnia.

Ben I. McNeil & Tristan P. Sasse. 2016. Future ocean hypercapnia driven by anthropogenic amplification of the natural CO2 cycle. Nature. 529, 383–386

Archaefructus : not the oldest angiosperm anymore

In 2015, an ancient plant fossil named Montsechia vidalii has claimed the throne of the oldest angiosperm. Before its discovery, Archaefructus liaoningensis was believed to be the oldest angiosperm in the world.

Archaefructus liaoningensis Source: wikipedia

The flowers for both of them do not have petal nor sepal. For Archaeofructus, the scientists found its fruit and female flowers. There was no male flower to be found. Both of them seem to produce unisexual flowers.

The word Archaefructus is also a combination of prefix and suffix. Try to figure it out before you see the rest of this article.

The prefix, archae(o)-, is the same as arche(o)-. We have learned it from Lesson 16-2. Both of them are originated from Greek word archaios, meaning ancient, old.

The other part of Archaefructus, -fructus, is also having a Greek origin. It is originated from fructus, meaning fruit.

Putting them together, Archaefructus, meaning "ancient fruit".

Archaeofructus was dated back 125 million years and Montsechia was dated back 130 million years. Therefore, Archaeofructus is no longer the oldest angiosperm anymore.

However, both of them are water-borne plants. The research team for Montsechia also suggested that its pollens are probably carried by water.

Although only 5% of angiosperm live in water, the discovery of Montsechia suggested a possibility that the primitive angiosperms could be all water-borne.

As a final note, the second part of Archaefructus' name, liaoningensis, is a memoir of the place it was discovered. It was found in the Province of Liaoning, China.

中文課程請點：Archaefructus 遼寧古果

Oophila : an interesting unicellular algae.

In Lesson 16-1, we introduced many suffixes related to attraction. They are :

-phil, -phile, -philia, -philic, -tropin, -tropism.

There's a unicellular algae named Oophila amblystomatis, which live symbiotically with spotted salamander (Amblystoma maculatum) and hence its name "amblystomatis".

spotted salamander. Source: wiki

How about its genus "Oophila"? Well, it is a combination of one prefix and one suffix.

The former part oo is originated from the prefix  oo- , which comes from Greek ōon, meaning egg.

The later part -phila is originated from the suffix -philia, which is written as philein in Greek. It means "like, loving".

Putting them together, Oophila meaning egg-loving.

Is this algae egg-loving? Apparently so. It is living with the embryo of spotted salamander symbiotically. As a result, the embryo of spotted salamander looks greenish. The special thing with this relationship is the algae is actually living INSIDE the cell. This is the first time scientists discovered such a thing. Usually, the adaptive immune system of vertebrates will attack the foreign tissues (in this case, the algae). However, it seems that the algae has made peace with the salamander's immune system.

Scientists discovered that the salamander cells have arranged their mitochondria alongside with the algae, so their mitochondria can use as much oxygen from the algae as possible; and the salamander algae (Oophila's nickname) can use the metabolic waste (CO₂) from salamander's mitochondria.

Scientists also found that spotted salamander can pass the algae through generations. Isn't it cool?

References:

Anna Petherick. 2010/7/30. A solar salamander-Photosynthetic algae have been found inside the cells of a vertebrate for the first time. Nature News.

Ryan Kerney, Eunsoo Kim, Roger P. Hangarter, Aaron A. Heiss, Cory D. Bishop, and Brian K. Hall. 2011. Intracellular invasion of green algae in a salamander host. Proc. Natl. Acad. Sci. USA. 108（16）：6497–6502, doi: 10.1073/pnas.1018259108

Achilles tendon

In Lesson 15-1 we learned the prefixes for tendon: tend(o)-, tendin(o)-, ten(o)- and tenont(o)-.

In this article I want to tell a story about Achilles tendon.

Achilles tendon. Source: wiki

Which one is Achilles tendon? Achilles tendon is the one that labelled as tendo calcaneus. It is the thickest tendon of human body.

Well, why is this tendon called Achilles tendon? In Homer's Iliad, it was told during the Trojan War, Achilles was struck on his unprotected heel (right on this tendon!) by a poisoned arrow shot by Paris, that killed him.

The story also told that in the same war, after killing Hector (the Prince of Troy), Achilles is said to have cut behind Hector's Achilles tendons, and threaded leather thongs through the incisions in order to drag him behind a chariot.

Achilles drag Hector's body behind a chariot outside Troy after killing him.
Source: wiki

It was said that Hector predicted Achilles death while he was dying. In Greek mythology, Achilles' mother, the goddess Thetis, received a prophecy of her son's death. Hearing this, she dipped him into the River Styx to protect his body from harm. However, she kept hold of his heel, meaning that the water did not touch this part of his body and it was therefore vulnerable.

After Hector's death, his brother Paris shot Achilles right on the only vulnerable spot.

Because Achilles has only this only weak spot and hitting this spot cause his death, the phrase "Achilles heel" becoming a phrase referring to the vulnerable spot for anyone.

The oldest written record for Achilles tendon is in 1693, written by Philip Verheyen, the French/Dutch anatomist.

Reference:

Achilles tendon. Wikipedia.

New way of protein modification: stearoylation

We learned the prefixes for lipid in Lesson 14-3. They are:

adip(o)-, lip(o)-, pi(o)-, pimel(o)-, stear(o)-, steat(o)-

One of the prefixes, stear(o)- is used in stearic acid. There is a paper on Nature that is related to stearic acid in 2015.

In this paper, the research team discovered that the activity of human transferrin receptor 1 (TFR1) can be affected by stearoylation. The stearoylated TFR1 cannot activate JNK protein so mitochondria will not become fragmented.

Because fragmented mitochondria is poorly functional, stearoylation is actually a good thing in this aspect.

What is stearic acid? Stearic acid is a long-chain fatty acid, with 18 carbons with no double bond. We usually express fatty acid as "C18:0", meaning this fatty acid has 18 carbons with no double bond. The structure of stearic acid can be seen in the picture below:

Stearic acid. Source: wikipedia

Stearoylation is a whole new way of protein modification. We knew phosphorylation, ubiquitination and glycosylation can affect protein activity. But stearoylation is the first time.

To make this story more interesting, the whole discovery was started on a mistake. So making mistakes isn't so bad sometimes, huh?

Reference:

Teleman A.A. et. al., 2015. Regulation of mitochondrial morphology and function by stearoylation of TFR1. Nature. doi:10.1038/nature14601

小扁豆（lentils）與水晶體（lens）

在第十四課（一）裡面我們學到水晶體（lens）。用來形容水晶體的字首是lent(i)-。

不過，小扁豆的英文名稱是lentils。或許讀者會覺得，為什麼要提到小扁豆呢？

長在田裡的小扁豆。圖片來源：wiki

這就要看小扁豆的學名了。小扁豆的學名是：Lens culinaris。注意到屬名了嗎？跟水晶體一模一樣呢！為什麼小扁豆會使用水晶體作為學名呢？

原來是因為小扁豆的種子的形狀（如下圖）。

小扁豆的種子。圖片來源：wiki

看到了嗎？小扁豆的種子的形狀，跟水晶體以及透鏡都很像！所以就借了lens這個詞來給小扁豆啦！學到現在同學不知道有沒有發現，語言，不論是英文或中文，借詞借字是很常見的事情。只是因為英文不是我們的母語，我們認得的字沒有那麼多，所以就不那麼清楚了。

lentil and lens : are they related?

In Lesson 14-1 we learned a tissue in our eye called lens. The prefix for describing lens is lent(i)-.

However, there is also a plant, a legume which is named lentils. If we check the scientific name for lentil, you will find is very interesting. The scientific name for lentil is Lens culinaris.

How come a genus of a plant use the tissue of our eyes as its name?

Well, it's very simple. The seeds of lentils look very similar to the lens in our eye and also the lens we use for observing objects.

lentils. Source: wikipedia

Therefore, it is named lentils. It is very common to borrow words here and there to describe new things.

How come iris can be related to both eyes and plants?

We have learned iris in Lesson 14-1. The prefix for iris, irid(o)- is derived from rainbow (please referred to Lesson 5-3).

However, iris also meaning a plant.

Iris. Source: wikipedia

Iris plant is a monocot with beautiful flowers. The artist Van Gogh drew a famous painting for it. How come tissue in the eye become a plant?

Well, as we mention in this article first, the tissue in our eyes get the name iris because different people has different color of iris. Therefore, the Greek word for rainbow, iridos, is borrowed for describing the tissue in our eyes.

How about the plant iris? Isn't all iris blue?

Actually not. Because that famous painting from Van Gogh, we thought all iris are blue. Actually there are many different shades of colors for iris.

Different colors of iris. Source: wikipedia gallery

Source: Wikipedia Gallery

Source: wiki

Because iris has so many shades of colors, Greek named it iris. That's why the word iris can be used for the tissue in our eyes and also a plant!

Reference.

Wikipedia Iris (anatomy)_Etymology, Iris (plant)