A type of cell that floats freely in the amniotic fluid of pregnant women has been found to have many of the same traits as embryonic stem cells, including an ability to grow into brain, muscle and other tissues that could be used to treat a variety of diseases, scientists reported yesterday.
The cells, shed by the developing fetus and easily retrieved during routine prenatal testing, are easier to maintain in laboratory dishes than embryonic stem cells-the highly versatile cells that come from destroyed human embryos and are at the center of a heated congressional debate that will resume this week.
Moreover, because the cells are a genetic match to the developing fetus, tissues grown from them in the laboratory will not be rejected if they are used to treat birth defects in that newborn, researchers said. Alternatively, the cells could be frozen, providing a personalized tissue bank for use later in life.
The new cells are adding credence to an emerging consensus among experts that the popular distinction between embryonic and “adult” stem cells-those isolated from adult bone marrow and other organs-is artificial.
Increasingly, it appears there is a continuum of stem cell types, ranging from the embryonic ones that can morph into virtually any kind of tissue but are difficult to tame, up to adult ones that can turn into a limited number of tissues but are relatively easy to control.
The newly analyzed fetal stem cells, scientists said, have many of the advantages of both.
“They grow fast, as fast as embryonic stem cells, and they show great pluripotentiality,” meaning they can become many kinds of tissues, said study leader Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine in Winston-Salem, N.C. “But they remain stable for years without forming tumors,” he added, something that embryonic cells are not very good at.
Atala and other scientists emphasized that they don’t believe the cells will make embryonic stem cells irrelevant.
“There’s not going to be one shoe that fits all,” said Robert Lanza, scientific director at Advanced Cell Technology in Worcester, Mass. “We’re going to have to see which ones are most useful for which clinical conditions.”
George Daley, a Harvard stem cell researcher, echoed that sentiment. “They are not a replacement for embryonic stem cells,” he said.
But in the past, even hints that non-embryonic cells might have medical potential similar to embryonic ones have complicated the political push to expand federal funding for the controversial field. And accordingly, opponents quickly pounced on the new results.
65.（ ）is not a trait of embryonic stem cells.
66. The cells that are shed by the developing fetus are（ ）.
67. Tissues grown from these cells in the laboratory will not be rejected as they are（ ）.
68. Embryonic stem cells can（ ）.
69. Robert Lanza said “There’s not going to be one shoe that fits all.” He meant（ ）.
70. The word “retrieved” in the second paragraph can be best replaced by（ ）.
问题1选项
A.Growing into brain tissues
B.Using embryonic stem cells to treat a variety of diseases
C.Causing a variety of diseases
D.Growing into muscle tissues
问题2选项
A.at the center of a heated congressional debate
B.more difficult to maintain in laboratory dishes than embryonic stem cells
C.difficult to retrieve during routine prenatal testing
D.easily retrieved during routine prenatal testing
问题3选项
A.free of birth defects
B.easier to cultivate
C.a genetic match to the donor
D.can be frozen for use by anyone in need
问题4选项
A.turn into a limited number of tissues and are difficult to tame
B.turn into a limited number of tissues but are relatively easy to control
C.can morph into virtually any kind of tissue and are relatively easy to control
D.can morph into virtually any kind of tissue but are difficult to tame
问题5选项
A.he does not believe these cells will make embryonic stem cells irrelevant
B.he knows people have different size feet
C.he will still need to see which ones are most useful for which clinical condition
D.even hints that non-embryonic cells might have medical potential has complicated things
问题6选项
A.taken out for testing
B.collected for other uses
C.sampled for testing
D.used for testing
第1题:C
第2题:D
第3题:C
第4题:D
第5题:A
第6题:A
65.【试题答案】C
【试题解析】细节事实题。根据文章第一段第一、二句A type of cell that floats freely in the amniotic fluid of pregnant women has been found to have many of the same traits as embryonic stem cells, including an ability to grow into brain, muscle and other tissues that could be used to treat a variety of diseases.（一种可以在孕妇羊水中自由漂浮的细胞被发现与胚胎干细胞有许多相同的特征，包括能够生长成大脑、肌肉和其他组织，用于治疗各种疾病），选项C“引起各种疾病”，文章没有提到此内容，C选项正确。A选项“在脑组织中生长”，文章提到，这种细胞可以生长大脑，A选项可排除。B“利用胚胎干细胞治疗多种疾病”，文章提到，这种细胞可以治疗各种疾病，B选项可排除。D选项“长成肌肉组织”，文章提到，这种细胞，可以长成肌肉组织，D选项可排除。因此C选项正确。
66.【试题答案】D
【试题解析】细节事实题。根据第二段第一句The cells, shed by the developing fetus and easily retrieved during routine prenatal testing（这些细胞由发育中的胎儿脱落，在常规的产前检查中很容易得到），D选项“在常规产前检查中很容易找回”，符合文章内容，D选项正确。A选项“处于激烈的国会辩论的中心”，文章没有提到此内容，可排除。B选项“比胚胎干细胞更难在实验室培养皿中保存”，文章没有提到这些细胞更难在实验室培养皿中保存，B选项可排除。C选项“很难在常规产前检查中恢复”，文章没有提到此内容，可排除。因此D选项正确。
67.【试题答案】C
【试题解析】细节事实题。根据第三段第一句because the cells are a genetic match to the developing fetus, tissues grown from them in the laboratory will not be rejected（因为这些细胞在基因上与发育中的胎儿相匹配，所以在实验室中从它们生长出来的组织不会被排斥），可推测，这些细胞在基因上与发育的胎儿相匹配，C选项“和捐赠者的基因匹配”正确。其余选项，A选项“无出生缺陷”，B选项“更容易培养”和D选项“可以冷冻起来供有需要的人使用”，不符合文章内容，可排除。因此C选项正确。
68.【试题答案】D
【试题解析】细节事实题。根据第五段第三句the embryonic ones that can morph into virtually any kind of tissue but are difficult to tame（胚胎细胞几乎可以变成任何一种组织，但很难驯服），可以推断出D选项“可以转化成几乎任何一种组织，但很难驯服”正确。A选项“变成数量有限的组织，很难驯服”，文章没有提到会变成数量有限的组织，A选项可排除。B选项“转化成数量有限的组织，但相对容易控制”，说法错误，可排除。C选项“可以转化成几乎任何一种组织并且相对容易控制”，文章中没有提到细胞容易控制，C选项可排除。因此D选项正确。
69.【试题答案】A
【试题解析】细节事实题。根据Atala and other scientists emphasized that they don’t believe the cells will make embryonic stem cells irrelevant.（Atala和其他科学家强调，他们不相信这些细胞会使胚胎干细胞变得无关紧要）和“There’s not going to be one shoe that fits all,” said Robert Lanza（罗伯特•兰扎(Robert Lanza)表示：“没有一双鞋是适合所有人的”），可知Robert Lanza，Atala and other scientists的观点是一致的，他不认为这种新型细胞是万能的，会代替胚胎干细胞的所有功能，使之变得不相干。所以题干中的这句话实际上是在支撑前面的科学家的那句话they don’t believe the cells will make embryonic stem cells irrelevant.（他们不相信这些细胞会使胚胎干细胞变得无关紧要），A选项“他不相信这些细胞会使胚胎干细胞变得无关紧要”，符合文章内容，A选项正确；B选项“他知道每个人的脚大小都不一样”并不是Robert Lanza所暗示的含义；根据原文“There’s not going to be one shoe that fits all,” said Robert Lanza, scientific director at Advanced Cell Technology in Worcester, Mass. “We’re going to have to see which ones are most useful for which clinical conditions.”（“没有一只鞋适合所有人”，Robert Lanza说，他是麻省Worcester先进细胞技术的科学总监“我们将不得不确定哪些药物对哪些临床情况最为有用”）可知C选项“他还需要看看哪些药物对哪些临床情况最有用”在文章中有提及，但这句话是补充说明前文，表达他不认为这种新型细胞是万能的，而是要对症下药；D选项“即使暗示非胚胎细胞可能具有医疗潜力，也会使事情变得复杂”并不是Robert Lanza的观点。因此A选项正确。
70.【试题答案】A
【试题解析】词义辨析题。根据题干可以定位到第二段第一句The cells, shed by the developing fetus and easily retrieved during routine prenatal testing（这些细胞由发育中的胎儿脱落，在常规的产前检查中很容易得到）。这句话表达的是“在常规产前检查中容易取出这种细胞做检查”。A选项“拿出来测试”，符合文章内容。B选项“收集作其他用途”，不符合文章内容，可排除。C选项“取样测试”，文章没有提到取样，可排除C选项。D选项“用于测试”，文章没有提到这种细胞用于测试，可排除。因此A选项正确。
