陕西汉中市中学生色觉障碍的调查

色觉障碍包括色盲和色弱,有后天性和先天性之分.后天患者往往伴有视力的严重损害,故较易发现.先天患者往往视力良好,对自己的色觉异常往往不自知.色觉障碍与日常生活及工作有密切的关系,故研究青少年色觉障碍的发病情况,对其职业选择、优生优育,减少色盲的发病率,采取相应的预防措施等都具有一定的实际意义.为此,我们于1988年5月至6月对汉中市八个中学的部分中学生进行了色觉障碍的详细调查与统计,现报告如下:     

关于色盲机理研究的一些新发现

色盲是一种常见的色觉异常现象。自从1794年著名的英国化学家道尔顿(他本人就是色盲患者)发表了研究报导以来,世界上许多科学家对其病理作了不懈的探索;最近美国斯坦福大学以内森斯为主的一个研究小组用遗传学方法进行的研究取得了新的突破,为揭开色盲之谜作出了重要贡献。近些年,有人通过研究人视网膜中央凹附近的视     

通过调查探讨色盲、色弱与正常色觉的遗传关系

通过对贵州省贞丰县一个满族色盲家系的调查和分析,简单探讨了色盲、色弱与正常色觉的遗传关系,提高对此类遗传病进一步的认识,以及用于生物学教学。     

问题解答

问:为什么色盲基因只用一个隐性基因b表示? 答:色盲有许多类型。课本上讲的实际上是红绿色盲。据研究,人的色觉是由于三种不同的视蛋白和维生素A复合形成红、绿、蓝三种色素,因而能分别吸收红、绿、蓝光而引起视觉。如果缺乏某种色素,不能分辨某种颜色,称为部分色盲,如红色盲、绿色盲等。如色素全部缺乏,则完全不能分辨颜色,称全色盲。最常见的红绿色盲是一种x连锁隐性遗传病,患者不能     

基于H分量旋转的色盲矫正方法

为提高色盲患者的色彩分辨力,提出一种基于H分量旋转的色盲矫正方法。在颜色的HSI空间,利用H分量的连续性和周期性特点,在保持S、I分量不变的情况下,通过旋转H分量得到矫正图像,该图像以降低低频颜色的分辨率来换取高频颜色的分辨率提高。实验表明：在色盲类型给定且图像颜色是给定色盲易混淆的情况下,对H分量旋转120度能得到色彩分辨效果很好的矫正图像。     

浅谈先天性色觉障碍

先天性色觉障碍通常称为色盲，它不能分辩自然光谱中的各种颜色或某种颜色。而对颜色的辨别能力差的则称色弱，它与色盲的界限一般不易严格区分，只不过轻重程度不同罢了。色盲又分为全色盲和部分色盲（红色盲、绿色盲、蓝黄色盲等）。色弱包括全色弱和部分色弱（红色弱、绿色弱、蓝黄色弱等）。1全色菌属于完全性视锥细胞功能障碍，与夜盲（视杆细胞功能障碍）恰好相反，患者尤喜暗、畏光，表现为昼盲。七彩世界在其眼中是一片灰暗，如同现黑白电视一般，仅有明暗之分，而无颜色差别。而且所见红色发暗、蓝色光亮，此外还有视力差、弱视、…     

人眼和微光夜视仪

人眼是一个很好的图象检测器。人眼网膜的感受器有两种:视锥细胞和视杆细胞。视锥细胞分辨本领高,有色觉,但是灵敏度低,适用于明视觉;视杆细胞灵敏度高,但分辨力差,色盲,适用于暗视觉。在正常照度下,人眼检测目标的效果主要     

基于色盲遗传学教学素材的挖掘及其在教学中应用

在遗传学课程教学中,红绿色盲是X连锁隐性遗传的典型案例。然而红绿色盲只是比较常见的色觉障碍,还有其他临床分型。不同的色盲遗传方式可能不同,致病基因也不同。近年来,关于色盲的致病基因、分子机制、基因治疗等方面取得了很大进展,相关研究成果可以作为很好的素材在遗传学教学中进行使用。本文阐述了基于色盲的遗传学教学素材的挖掘及其在本校遗传学课程中“绪论”“遗传的细胞和分子基础”“伴性遗传”“染色体畸变”“基因突变”“遗传学进展”等章节教学中的应用。通过课堂教授与问答,辅以课后文献检索与阅读,使学生在更好掌握遗传学基本内容的基础上,能拓宽遗传学学术视野,激发学习兴趣。     

异常三色觉者的色觉异常检查和相对光谱亮度测定的相关研究

利用滤光片型测异仪,对220名(男146,女74)受试者进行了比配黄光所需的红光和绿光的相对量及其变动范围的测定。220例中,207例色觉正常,对他们R/G比值的统计学特性加以分析,假设其分布是正态的。其余13例,占总检查人数的6％,包括甲型色盲3人,乙型色盲3人,甲型异常三色觉者1人,乙型异常三色觉者2人和极端乙型异常三色觉者4人。7名异常三色觉者中的6名的相对光谱亮度曲线曾群加测定。此外,我们还测定了5名正常人,2名甲型色盲和2名乙型色盲的相对光谱亮度曲线,以资此较。同时,所有的受试者还阅读了假等色图谱(Ishihara 15版),作为一种衡量其色分辨能力的定性检查。从我们实验结果的相关考虑,同时根据Rushton对圆锥细胞色素从正常人的分布过渡到二色觉者的分布的建议,对异常三色觉的形成原因进行了探讨。为了解释异常三色觉者的某些视功能表现,除了由一个系统一部分细胞的视色素轉变到另一个系统的视色素而产生的异常三色觉之外,另外一些例子可能是由于形成某些异常的色素而引起的,这种异常的色素既不存在于正常“红”系统中,也不存在于正常“绿”系统中,可能是P_(54)和(2P_(54)+3P_(59))两色素轉变过程中停留在中间状态的一种色素。这个假设也可以解释为什么在简单异常三色觉羣里,R/G比值容易处于某些数值。对平均R/G比值与正常人相差很小但此配范围又较大的异常三色觉者,可能的解释是他们的“红”系统和“绿”系统的色素在某种程度上相互轉变,两个系统的吸收光谱相互接近。此外,还有一些更复杂的例子,须要一个以上的形成原因来解释他们的视觉现象。     

考核与练习 每期10题

1.人类的褐色眼睛B对蓝色眼睛b为显性,今有一对褐色眼睛、正常色觉的夫妇,生了一个蓝色眼睛而色盲的儿子,那么这对夫妇的基因型是: A.BBx~Bx~b×Bbx~BY B.Bbx~Bx~b×Bbx~BY C.Bbx~Bx~b×BBx~BY D.BBx~bx~b×Bbx~BY 2.有一种植物,只有在显性基因A和B同时存在时才开紫色花,否则都开白花。已知一株开紫色花的植物和一株开白花的植物进行杂交,产生开紫花植株17棵,开白花植株15棵。问这两种亲本杂交,     

Color-Vision Mechanisms in the Peripheral Retinas of Normal and Dichromatic Observers

It is possible that so-called normal trichromatic vision occurs only between the central blue-blind fixation area and about 30° peripherally. Beyond about 30° vision has been alleged to become dichromatic (red-green blind), and beyond about 60°, monochromatic. Hence every form of color blindness may characterize various zones of the normal retina. We have studied mechanisms of peripheral color vision, mainly by measuring the spectral sensitivities of the blue-, green-, and red-sensitive systems, isolated by differential color adaptation. In normal observers the sensitivity of the blue-mechanism falls off about 2 log units by 80° out. The green- and red-sensitive systems decline only about 0.7 log unit over the same range. Protanopes, deuteranopes, and tritanopes exhibit comparable changes. We have not found any color mechanism present centrally to be wholly lost peripherally. Nor, for dichromats, have we found any mechanism missing centrally to be present peripherally. Whatever evidences of peripheral color blindness have been observed appear to involve other mechanisms than failure of receptors, probably including some fusion of neural pathways from receptors to centers.     

Statistical and molecular analyses of evolutionary significance of red-green color vision and color blindness in vertebrates

Red-green color vision is strongly suspected to enhance the survival of its possessors. Despite being red-green color blind, however, many species have successfully competed in nature, which brings into question the evolutionary advantage of achieving red-green color vision. Here, we propose a new method of identifying positive selection at individual amino acid sites with the premise that if positive Darwinian selection has driven the evolution of the protein under consideration, then it should be found mostly at the branches in the phylogenetic tree where its function had changed. The statistical and molecular methods have been applied to 29 visual pigments with the wavelengths of maximal absorption at approximately 510-540 nm (green- or middle wavelength-sensitive [MWS] pigments) and at approximately 560 nm (red- or long wavelength-sensitive [LWS] pigments), which are sampled from a diverse range of vertebrate species. The results show that the MWS pigments are positively selected through amino acid replacements S180A, Y277F, and T285A and that the LWS pigments have been subjected to strong evolutionary conservation. The fact that these positively selected M/LWS pigments are found not only in animals with red-green color vision but also in those with red-green color blindness strongly suggests that both red-green color vision and color blindness have undergone adaptive evolution independently in different species.     

Behavioral evidence of color vision deficiency in a protanomalia chimpanzee (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

Although color vision deficiency is very rare among Old World monkeys and apes, one male chimpanzee (Lucky) was identified as protanomalous by genetic and physiological analyses. This study assessed behavioral phenotypes of Lucky and four chimpanzees with normal color vision by discrimination task using the modified Ishihara pseudo-isochromatic plates. Lucky could not discriminate the stimuli that the other chimpanzees could. This is the first behavioral evidence of color vision deficiency in chimpanzees. Electronic Publication     

The molecular genetics of color vision and color blindness

Recent reports from several laboratories have changed our thinking about the molecular genetics of normal color vision and color blindness. The impact of these new findings can be best appreciated by examining them in the context of the historical development of color vision theory.     

The Causes and Consequences of Color Vision

The ability to see colors is not universal in the animal kingdom. Those animals that can detect differences in the wavelengths of the electromagnetic spectrum glean valuable sensory information about their environment. They use color vision to forage, avoid predators, and find high-quality mates. In the past, the colors that humans could see clouded scientists’ study of animals’ color perception. Leaving that bias behind has led to new insights about how and why the color vision of animals evolved. This paper provides a brief introduction to color vision, the genetics of color vision in humans, what colors other animals see, and how scientists study color vision. We examine the consequences of having color vision, including speciation, loss of olfactory capabilities, and sexual selection.     

Characterization of a Drosophila melanogaster orthologue of muskelin

Visual systems of vertebrates exhibit a striking level of diversity, reflecting their adaptive responses to various color environments. The photosensitive molecules, visual pigments, can be synthesized in vitro and their absorption spectra can be determined. Comparing the amino acid sequences and absorption spectra of various visual pigments, we can identify amino acid changes that have modified the absorption spectra of visual pigments. These hypotheses can then be tested using the in vitro assay. This approach has been a powerful tool in elucidating not only the molecular bases of color vision, but the processes of adaptive evolution at the molecular level.     

Color blindness among Aymara in Chile

Nine color blind subjects were discovered in a survey of 140 Aymaras of Arica, Chile, using as screening test a portable Anomaloscope, Ishihara tables and Hardy-Rand-Ritter plates. Pseudosisochromatic test failed on detecting four anomalous trichromates. Seven color blind subjects revealed foreign ancestors. Also a different prevalence of defectives among subsamples was observed. Thus color blindness variability within the sample could be explained by gene flow. It is proposed to use anomaloscopes as a screening device in order to survey with accuracy color vision genes in human populations.     

Anomalous color vision in three Mexican populations

Color vision was tested as part of a study of micro-evolution in three historically-related populations in Mexico. The frequencies of color vision anomalies fall within the range observed for contemporary Latin American populations. The present findings do not support the previously proposed hypothesis concerning the relaxation of selective forces in agricultural and urban populations.     

Vision screening of adolescents and their use of glasses.

Vision screening was performed in over 11 000 16-year-olds who were taking part in the National Child Development Study. For distance vision 75% had normal acuity, 9% a minor defect, and 16% a more severe unilateral or bilateral defect. For near vision 85% had normal vision, 8% a minor defect, and 7% a unilateral or bilateral defect. Few children (62) with normal distant vision had defects in near vision, though many more (607) had both poor distant vision and poor near vision. Vision defects were more common in girls than in boys and occurred more often in adolescents from non-manual than manual families. Athough 18% of children had been prescribed glasses for current use, a third did not have their glasses available at the examination: 27% of the children prescribed glasses had normal unaided distant visual acuity or only a minor defect, and they constituted 42% of those who were not wearing their glasses. Further investigation is needed into the criteria on which glasses are prescribed for children and into the reasons for which they are not worn.     

多能干细胞分化来源视网膜色素上皮细胞移植治疗视网膜变性研究进展

视网膜色素上皮（RPE）对视觉功能的维持起着至关重要的作用。视网膜变性是全球不可治愈性致盲疾病的重要原因,它由视网膜色素上皮功能失常所引起。因此,视网膜色素上皮移植是视网膜变性患者恢复视力的一种最有前景的手段之一。随着干细胞技术的快速发展,从多能干细胞（PSC）到有功能的视网膜色素上皮细胞的体外分化诱导技术已经成熟,其中包括胚胎干细胞（ESCs）和诱导多能干细胞（iPSCs）等。此外,从患者特异性iPSCs分化而来的RPE更能用于阐明发病机理并有针对性地个体治疗。更值得一提的是,经诱导得到RPE的移植不论在动物模型中,还是在临床试验里都已经得到了可喜的治疗效果。本文回顾PSC来源RPE干预治疗视网膜变性的最新研究进展。