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  • 1
    ISSN: 1573-6857
    Keywords: Drosophila ; P-element mutagenesis ; somatic mosaics ; visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A neuroanatomical screening of a collection of P-element mutagenized flies has been carried out with the aim of finding new mutants affecting the optic lobe of the adult brain in Drosophila melanogaster. We have identified a new gene that is involved in the development of the adult axon array in the optic ganglia and in the ommatidia assembly. We have named this locus visual system disorganizer (vid). Reversional mutagenesis demonstrated that the vid mutant was the result of a P-element insertion in the Drosophila genome and allowed us to generate independent alleles, some of which resulted in semilethality, like the vid original mutant, while the others were completely lethal. A genetic somatic mosaic analysis indicated that the vid gene is required in the eye for its normal development by inductive effects. This analysis also suggests an inductive effect of the vid gene on the distal portion of the optic lobe, particularly the lamina and the first optic chiasma. Moreover, the absence of mutant phenotype in the proximal region of the optic ganglia, including the medulla, the second optic chiasma, and the lobula complex underlying mosaic eyes, is suggestive of an autonomously acting mechanism of the vid gene in the optic lobe. The complete or partial lethality generated by different mutations at the vid locus suggests that this gene's role may not be limited to the visual system, but may also affect a vital function during Drosophila development.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6857
    Keywords: Drosophila ; P-element mutagenesis ; somatic mosaics ; visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A neuroanatomical screening of a collection of P-element mutagenized flies has been carried out with the aim of finding new mutants affecting the optic lobe of the adult brain inDrosophila melanogaster. We have identified a new gene that is involved in the development of the adult axon array in the optic ganglia and in the ommatidia assembly. We have named this locusvisual system disorganizer (vid). Reversional mutagenesis demonstrated that thevid mutant was the result of a P-element insertion in theDrosophila genome and allowed us to generate independent alleles, some of which resulted in semilethality, like thevid original mutant, while the others were completely lethal. A genetic somatic mosaic analysis indicated that thevid gene is required in the eye for its normal development by inductive effects. This analysis also suggests an inductive effect of thevid gene on the distal portion of the optic lobe, particularly the lamina and the first optic chiasma. Moreover, the absence of mutant phenotype in the proximal region of the optic ganglia, including the medulla, the second optic chiasma, and the lobula complex underlying mosaic eyes, is suggestive of an autonomously acting mechanism of thevid gene in the optic lobe. The complete or partial lethality generated by different mutations at thevid locus suggests that this gene's role may not be limited to the visual system, but may also affect a vital function duringDrosophila development.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6857
    Keywords: artificial selection ; Drosophila ; genetic variation ; non-linear response ; rare alleles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Quantitative genetic theory predicts that variation due to rare alleles at many loci will generate a transient acceleration in the response to directional selection. We have tested this prediction by constructing experimental lines ofDrosophila melanogaster that carry positively selected ethanol resistance alleles at low frequencies, and then subjecting the lines to directional selection for ethanol resistance. Approximately 468,000 files were subjected to artificial selection over 30 generations. The predicted non-linear selection responses were observed in all experimental lines and replicates, on three genetic backgrounds. In contrast, un-selected controls and lines carrying random alleles at low frequencies on the same genetic backgrounds exhibited linear selection responses. These results demonstrate that non-linearities due to rare alleles are detectable and repeatable, provided that experiments are done on a sufficiently large scale. The results suggest that it may be possible to test for rare-alleles as a component of naturally occurring genetic variation by careful examination of selection response curves.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 173-184 
    ISSN: 1573-6857
    Keywords: evolution ; genetics ; neurophysiology ; philosophy ; politics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On first impression, the disciplines of genetics and political science would appear to be unrelated. And yet, commencing more than 30 years ago, the interdisciplinary field known as Biopolitics has now taken hold. This essay traces the central thrust of the biopolitical research agenda. It describes, analyzes, and assesses how political scientists have sought to show connections between our species' genetic constitution and our species' political behavior. Important bridges between the two are the neurophysiology of the human brain and the role of evolutionary theory in charting man's adaptational political profile. The parameters of the emerging biopolitical literature raise profound policy questions, some of which are also characterized.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 97-108 
    ISSN: 1573-6857
    Keywords: heritability estimates ; IQ ; model tests ; Spearman'sg ; twin research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One reason for the astonishing persistence of the IQ myth in the face of overwhelming prior and posterior odds against it may be the unbroken chain of excessive heritability claims for ‘intelligence’, which IQ tests are supposed to ‘measure’. However, if, as some critics insist, ‘intelligence’ is undefined, and Spearman's g is beset with numerous problems, not the least of which is universal rejection of Spearman's model by the data, then how can the heritability of ‘intelligence’ exceed that of milk production of cows and egg production of hens? The thesis of the present review paper is that the answer to this riddle has two parts: (a) the technical basis of heritability claims for human behavior is just as shaky as that of Spearman's g. For example, a once widely used ‘heritability estimate’ turns out to be mathematically invalid, while another such estimate, though mathematically valid, never fits any data; and (b) valid technical criticisms of flawed heritability claims typically are met with stubborn editorial resistance in the main stream journals, which tends to calcify such misinformation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 109-112 
    ISSN: 1573-6857
    Keywords: heritability ; intelligence testing ; observational studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper begins with a brief summary of the history of the development of ideas in the field of quantitative genetics. Next there is discussion of the controversy surrounding the contention that IQ tests validly estimate some highly heritable general intelligence factor. The validity of the reasoning supporting this contention is questioned. The theory of correlation between relatives has been of vast importance in plant and animal breeding because it is possible to design and carry out experiments to estimate variance components in expressions for covariances between relatives. However, data on humans is observational and individuals are not randomly assigned to environments, so that estimation of heritability from such data is not on the same firm foundation as it is in plant and animal breeding contexts.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6857
    Keywords: eugenics ; genetic determinism ; immigration restriction ; Nazi science ; sterilization laws
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eugenics, the attempt to improve the genetic quality of the human species by ‘better breeding’, developed as a worldwide movement between 1900 and 1940. It was particularly prominent in the United States, Britain and Germany, and in those countries was based on the then-new science of Mendelian genetics. Eugenicists developed research programs to determine the degree to which traits such as Huntington's chorea, blindness, deafness, mental retardation (feeblemindedness), intelligence, alcoholism, szhiophrenia, manic depression, rebelliousness, nomadism, prostitution and feeble-inhibition were genetically determined. Eugenicists were also active in the political arena, lobbying in the United States for immigration restriction and compulsory sterilization laws for those deemed genetically unfit; in Britain they lobbied for incarceration of genetically unfit and in Germany for sterilization and eventually euthanasia. In all these countries one of the major arguments was that of efficiency: that it was inefficient to allow genetic defects to be multiplied and then have to try and deal with the consequences of state care for the offspring. National Socialists called genetically defective individuals ‘useless eaters’ and argued for sterilization or euthanasia on economic grounds. Similar arguments appeared in the United States and Britain as well. At the present time (1997) much research and publicity is being given to claims about a genetic basis for all the same behaviors (alcoholism, manic depression, etc), again in an economic context – care for people with such diseases is costing too much. There is an important lesson to learn from the past: genetic arguments are put forward to mask the true – social and economic – causes of human behavioral defects.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 75-76 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 75-76 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 99 (1997), S. 97-108 
    ISSN: 1573-6857
    Keywords: heritability estimates ; IQ ; model tests ; Spearman's g ; twin research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One reason for the astonishing persistence of the IQ myth in the face of overwhelming prior and posterior odds against it may be the unbroken chain of excessive heritability claims for ‘intelligence’, which IQ tests are supposed to ‘measure’. However, if, as some critics insist, ‘intelligence’ is undefined, and Spearman's g is beset with numerous problems, not the least of which is universal rejection of Spearman's model by the data, then how can the heritability of ‘intelligence’ exceed that of milk production of cows and egg production of hens? The thesis of the present review paper is that the answer to this riddle has two parts: (a) the technical basis of heritability claims for human behavior is just as shaky as that of Spearman's g. For example, a once widely used ‘heritability estimate’ turns out to be mathematically invalid, while another such estimate, though mathematically valid, never fits any data; and (b) valid technical criticisms of flawed heritability claims typically are met with stubborn editorial resistance in the main stream journals, which tends to calcify such misinformation.
    Type of Medium: Electronic Resource
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