January 08, 2013
Most people might see cockroaches as good-for-nothing pests, but this germ-ridden insect could be an indirect source of new antibiotics for humans.
Cockroaches host the larvae of a parasitic type of wasp, which spend their formative days eating the bacteria-laden body of the cockroach from the inside out.
Researchers have discovered the wasp larva secretes chemicals that sanitize the decidedly unsanitary guts of the cockroach.
These germ-killing chemicals could eventually be developed for human uses.
For the developing larvae, “the cockroach is the only food source and the cradle,” says biologist Gudrun Herzner at the University of Regensburg in Germany.
It’s a cradle that needs a good cleaning, because cockroaches spend time in some very unsanitary places, from trash heaps to public toilets, where you’ll find a cornucopia of bacteria, fungi and viruses that can make you, and the emerald wasp larva, sick.
While the young wasp’s hygiene challenges may seem extreme, Herzner says they are basically the same problems we all face. “The larva has to protect, first, its food from degradation by microbes, and then it has to protect itself from foodborne illnesses that these microbes might cause.”
As the wasp larva munches its way through the microbe-laden body of the cockroach, it produces generous amounts of a clear liquid.
Herzner and her colleagues found this liquid to contain a blend of antimicrobial substances, according to their study published in the Proceedings of the National Academy of Sciences.
"The larvae seem to disperse this secretion thoroughly inside the cockroach, and in this way sanitize their cockroach hosts,” Herzner says.
One of the chemicals fights the germs that cause tuberculosis; another has a broad range of activity against bacteria, fungi, and viruses such as hepatitis C.
Herzner says it is the first time researchers have found insects using this chemical against microbes.
But it’s probably not the last insect antimicrobial discovery.
Most antibiotics that doctors use have been discovered among microbes living in the soil, but if researchers turn to the insect world, microbiologist Julian Davies, at the University of British Columbia, says, “You can have a potentially new source of antibiotics. People have been looking at this. Nothing’s come out of it yet, but they’re certainly looking at it.”
Antimicrobials have been discovered everywhere from frog skin to panda blood, but none of them have made it to the medicine cabinet yet.
Davies says it can be hard to isolate useful quantities of the active chemicals in these sources, and they may be difficult chemicals to produce in the lab.
Plus, Davies says, “It’s fine to find an antibiotic, but half of them are toxic.”
Scientists are working to overcome these hurdles.
Davies says these chemicals may be more than just microbe killers. He points to the emerging field of research on microbe-to-microbe chemical communication.
“And you can ask the question, ‘Are they killing each other, or are they talking to each other?’”
But, with antibiotic-resistant infections a growing threat worldwide, killing the microbes is scientists' current priority.
good-for-nothing (a) 一無是處的
larva (n) 幼蟲，幼體
parasitic (a) 寄生的 XXXXX parasite (n) 寄生蟲
secrete (v) 分泌
secretion 是名詞。 這個字跟“secret” (秘密)長很像，但尾巴多一個”e”。發音時，重音在第二 音節，很容易唸錯，需注意！
蟑螂可作為一種寄生性黃蜂的幼蟲宿主(host the larvae of a parasitic type of wasp)。幼蟲在成形時期 (formative days)，會把蟑螂充滿細菌的 (bacteria-laden)身體，從內到外地啃食(from the inside out)。研究人員發現，黃峰幼蟲會分泌化學物質 (secretes chemicals)來替蟑螂那非常骯髒的內臟消毒 (decidedly unsanitary guts)。
cradle (n) 搖籃
unsanitary (a) 不衛生的
sanitary (a) 衛生的。文中還有名詞 “sanitizer”，「消毒殺菌劑」。
degradation (n) 腐蝕
microbe (n) 微生物
文中 antimicrobial 是 anti- 加上 microbial 而來，意思是「抗菌的」。
對於黃峰幼蟲來說，蟑螂的身體是食物來源 (food source)，也是成長的搖籃 (cradle)。研究人員說，由於蟑螂長期出沒與生長的環境都很骯髒，身上帶有數不盡的細菌，黴菌和病毒 (a cornucopia of bacteria, fungi and viruses)，這都會可讓我們還有黃蜂的幼蟲生病。
寄生在蟑螂體內的黃峰幼蟲所面對的衛生挑戰 (hygiene challenges) 看似超高難度，但其實與人類面對的是同樣的問題：幼蟲必須要保護它的食物不因微生物而腐壞 (degradation by mibrobes)，同時也要讓自己不染上微生物所引起的，以食物為途徑的傳染病 (foodborne illnesses)。
dispenser (n) 分配者
dispense是動詞，「分配，分送」的意思，用法是 dispense something to someone。但片語 dispense with something 是「免除，不再需要」之意。同樣一個字，用法、意思差很多，要特別注意！
munch (v) 咯吱咯吱地咀嚼
cabinet (n) 櫥，櫃
hurdle (n) 障礙，困難
emerging (a) 新興的
priority (n) 優先考慮的事
當黃蜂幼蟲在蟑螂體內大快朵頤(munches)的時候 ，會分泌出大量的透明液體 (generous amounts of a clear liquid)。研究人員發現，這個液體含有抗微生物物質的混合物 (a blend of antimicrobial substances)。黃蜂幼蟲在蟑螂體內徹底地散布 (disperse) 這樣的分泌物 (secretion)，借此替宿主消毒。
抗微生物劑 (antimicrobials) 在各處都能被發現，青蛙的皮膚，貓熊血液中都可發現，但還沒有一樣能進入我們藥櫃中 (medicine cabinet)。研究人員說，要把這些來源的活性 (active)物質分離出有用的量 (useful quantities)並不容易，要在研究室裡製造也有困難。此外，找到一種新的抗生素 (antibiotic)雖然是件好事，但半數是有毒性的 (toxic)。
這些化學物質也許不能單單只被視為是滅菌劑 (microbe killers)。研究人員指出一個新興的領域 (emerging field)，專門研究微生物間的化學溝通 (microbe-to-microbe chemical communication)。但由於全球正面臨抗藥性傳染病 (antibiotic-resistant infections)的威脅，找到殺菌方法仍是科學家們的當務之急 (current priority)。
本文出現很多個複合形容詞。複合形容詞用一個字就可以表達一個子句或是一個介係詞詞片語的意思。妥善利用的話，可以省去多餘文字，讓文章讀起來更精簡，不囉嗦。舉例來說，本文第一句有兩個複合形容詞，如果用子句表達的話，可改寫成 “Most people might see cockroaches as pests that are good for nothing, but this insect that is ridden with germs could be an indirect source of new antibiotics for humans.” 讀起來不只囉嗦，且容易造成閱讀時的斷句困難，導致語意不清。改成複合形容詞寫法來修飾名詞，good-for-nothing pests 和 germ-ridden insect，是不是更簡潔易讀呢？
Check your vocabulary!
Fill in the blanks with a word or phrase from the list above. Make necessary changes. After you finish, select the text below to reveal the hidden answers.
1. There are lots of bureaucratic hurdles to deal with when adopting a child.
2. The customer is high on our list of priorities.
3. The baby rested peacefully in his cradle.
4. Jamie came out of the store munching a bag of potato chips.
5. The eggs sit all winter, but don't turn to larvae until there's a rain.
6. The toad's skin secretes a deadly poison.
7. Parasitic beetles often make their homes in the nests of ants.