29 How did Dr. Windbichler and Dr. Crisanti stop A. gambiae females being created (reproduced)?
(A)They used insecticides.
(B)They eliminated malaria.
(C)They made A. gambiae males incapable of reproduction.
(D)They inserted a gene to destroy the X chromosome of A. gambiae.

       Kill the mosquito and you kill the disease. That is the usual approach to controlling Malaria瘧疾. And if done properly正確、合適, it works. The problem is that the  insecticides殺蟲劑 employed to do the killing destroy lots of other things as well. An old dream of those who seek to eliminate排除；消除 malaria is thus a way of selectively killing only what transmits播送 the parasite寄生生物: mosquitoes of the genus Anopheles瘧蚊屬 most notably格外 Anopheles gambiae. And that, more or less主要, is what is proposed建議  by Nikolai Windbichler and Andrea Crisanti of Imperial College, London, in a paper in Nature communications交流；溝通. They think they have worked out how to stop A gambiae females being created in the first place. That would break the chain of transmission播送內容, 傳遞 in two ways:  immediately, because it is only females that drink blood and so pass the parasite寄生生物 on; and in the longer term because without females a population cannot reproduce. 

       The researchers’ trick騙局；詭計、方法 is to engineer into the mosquitoes a gene for a protein蛋白質 called a homing endonuclease歸巢內切酶基因. These genes are peculiar奇怪, and are probably a type of genetic parasite寄生生物. They cut particular sequence順序, 一連串 of DNA in a way that damages the chromosome染色體 such DNA is found in. In extreme cases, that destroys the chromosome染色體. (In less extreme cases, the process of repair修理；修補 often copies the endonuclease核酸内切酶 gene into the repair site; hence the name “homing,” and also the suspicion認為可能, 懷疑，猜想 of parasitism 寄生.) 

       Dr. Windbichler and Dr. Crisanti have found a homing endonuclease歸巢內切酶基因 in a species of slime mould黴；黴菌 that, by a strange coincidence, cuts a sequence順序, 一連串 of DNA found repeatedly一再 in the X chromosome of Anopheles gambiae, destroying the chromosome染色體 completely. 

B)They eliminated malaria. 

C)They made A. gambiae males incapable of reproduction. 

D)They inserted a gene to destroy the X chromosome of A. gambiae.