Until about five years ago, the very idea that peptide hormones might be made anywhere in the brain besides the hypothalamus was astounding- Peptide hormones, scientists thought, were made by endocrine glands and the hypothalamus was thought to be the brains’ only endocrine gland. What is more, because peptide hormones cannot cross the blood-brain barrier; researchers believed that they never got to any part of the brain other than the hypothalamus, where they were simply produced and then released into the bloodstream.But these beliefs about peptide hormones were questioned as laboratory after laboratory found that antiserums to peptide hormones, when injected into the brain, bind in places other than the hypothalamus, indicating that either the hormones or substances that cross-react with the antiserums are present. The immunological method of detecting peptide hormones by means of antiserums, however, is imprecise. Cross-reactions are possible, and this method cannot determine whether the substances detected by the antiserums really are the hormones, or merely close relatives. Furthermore this method cannot be used to determine the location in the body where the detected substances are actually produced.New techniques of molecular biology, however, provide a way to answer these questions. It is possible to make specific complementary DNA’s (CDNA’s) that can serve as molecular probes to seek out the messenger RNA’s (mRNA’s) of the peptide hormones. If brain cells are making the hormones, the cells will contain these mRNA’s. If the products the brain cells make resemble the hormones but are not identical to them, then the cDNA’s should still bind to these mRNA’s, but should not bind as tightly as they would to mRNA’s for the true hormones. The cells containing these mRNA’s can then be isolated and their mRNA’s decoded to determine just what their protein products are and how closely the products resemble the true peptide hormones.The molecular approach to detecting peptide hormones using cDNA probes should also be much faster than the immunological method because it can take years of tedious purifications to isolate peptide hormones and then develop antiserums to them. Roberts, expressing the sentiment of many researchers, states: “I was trained as an endocrinologist. But it became clear to me that the field of endocrinology needed molecular biology input. The process of grinding out protein purifications is just too slow.”If, as the initial tests with cDNA probes suggest, peptide hormones really are made in the brain in areas other than the hypothalamus, a theory must be developed that explains their function in the brain. Some have suggested that the hormones are all growth regulators, but Rosen’s work on rat brains indicates that this cannot be true. A number of other researchers propose that they might be used for intercellular communication in the brain.1.Which of the following titles best summarizes the passage?2.The passage suggests that a substance detected in brain by use of antiserums to peptide hormones may（ ）. 3.The passage implies that, in doing research on rat brains, Rosen discovered that （ ）.4.Which of the following is a way in which the immunological method of detecting peptide hormones differs from the molecular method?
A.Is Molecular Biology the Key to Understanding Intercellular Communication in the Brain? B.Molecular Biology: Can Researchers Exploit Its Techniques to Synthesize Peptide Hormones? C.The Advantages and Disadvantages of the Immunological Approach to Detecting Peptide Hormones. D.Peptide Hormones: How Scientists Are Attempting to Solve Problems of Their Detection.
问题2：
A.have been stored in the brain for a long period of time and to Understand Their Function B.play no role in the functioning of the brain C.have been produced in some part of the body other than the brain D.play an important role in the functioning of hypothalamus
问题3：
A.peptide hormones are used for intercellular communication B.complementary DNA’s do not bind to cells producing peptide hormones C.products clo
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We all know that the normal human daily cycle of activity is of some 7 to 8 hours’ sleep alternation with some 16 to 17 hour’s wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified.The question is no mere academic one. The case, for example, with which people can change from working in the day to working at night is a question of growing importance in industry where automation calls for round-the-clock working of machines. It normally, takes from five days to one week for a person to adapt to a reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12 midnight to 8 a.m. one week, 8 a.m. to 4 p.m. the next, and 4 p.m. to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently.The only real solution appears to be to hand over the night shift to a number of permanent night workers. An interesting study of the domestic life and health of night-shift workers was carried out by Brown in 1957. She found a high incidence of disturbed sleep and other disorders among those on alternating day and night shifts, but no abnormal occurrence of these phenomena among those on permanent night work.This latter system then appears to be the best long-term policy, but meanwhile something may be done to relieve the strains of alternate day and night work by selecting those people who can adapt most quickly to the changes of routine. One way of knowing when a person has adapted is by measuring his body temperature. People engaged in normal daytime work will have a high temperature during the hours of wakefulness and a low one at night; when they change to night work the pattern will only gradually go back to match the new routine and the speed with which it does so parallels, broadly speaking, the adaptation of the body as a whole, particularly in terms of performance. Therefore, by taking body temperature at intervals of two hours throughout the period of wakefulness it can be seen how quickly a person can adapt to a reversed routine, and this could be used as a basis for selection. So far, however, such a form of selection does not seem to have been applied in practice.1.Why is the question of “how easily people can get used to working at night” not a mere academic question?2.The main problem of the round-the-clock working system lies in （ ）.3.The best solution for implementing the 24-liour working system seems to be （ ）.4.It is possible to find out if a person has adapted to the changes of routine by measuring his body temperature because （ ）.5.Which of the following statements is NOT TRUE?
A.Because few people like to reverse the cycle of sleep and wakefulness. B.Because sleep normally coincides with the hours of darkness. C.Because people are required to work at night in some fields of industry. D.Because shift work in industry requires people to change their sleeping.
问题2：
A.the inconveniences brought about to the workers by the introduction of automation B.the disturbance of the daily life cycle of workers who have to change shifts too frequent C.the fact that people working at night are often less effective D.the fact that it is difficult to find a number of good night workers
问题3：
A.to change shifts at longer intervals B.to have longer shift C.to arrange for some people to work on night shifts only D.to create better living conditions for night workers
问题4：
A.body temperature changes when the cycle of sleep and wakefulness alternates B.body temperature changes when he changes to night shift or back C.the temperature reverses when the routine is changed D.people have higher temperatures when they are working efficiently
问题5：
A.Body temperature may serve as an indication of a worker's performance. B.The selection of
The machine looked like a large,（ ） , old-fashioned typewriter.
A.forceful B.clumsy C.intense D.tricky