Recovery of retinal function from suppression caused by flashes of light. Electroretinogram measurements in totally color-blind eyes.
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Adaptation, Ocular↗
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Physical and physiological correlates of behavioral inhibition.
Previous investigations have suggested that the temperamental quality of inhibition is related to the threshold of reactivity to unfamiliar events within certain limbic structures. In earlier work, children in three independent samples who had been selected to be inhibited were more likely to have blue than brown eyes, whereas uninhibited children were more likely to have brown eyes. The present study, which selected two-year-old children on the basis of eye color (blue or brown) rather than behavior, found a significant association between blue eyes and behavioral inhibition, and between brown eyes and an uninhibited style. Although the inhibited children were more likely to have a high and stable heart rate than were the uninhibited children, there was no relation between eye color and these cardiac measures. Several interpretations of the association between these temperamental categories and iris pigmentation are proposed.
Arousal↗
A genetic analysis of the Suppressor 2 of zeste complex of Drosophila melanogaster.
The zeste1 (z1) mutation of Drosophila melanogaster produces a mutant yellow eye color instead of the wild-type red. Genetic and molecular data suggest that z1 achieves this change by altering expression of the wild-type white gene in a manner that exhibits transvection effects. There exist suppressor and enhancer mutations that modify the z1 eye color, and this paper summarizes our studies of those belonging to the Suppressor 2 of zeste complex [Su(z)2-C]. The Su(z)2-C consists of at least three subregions called Psc (Posterior sex combs), Su(z)2 and Su(z)2D (Distal). The products of these subregions are proposed to act at the level of chromatin. Complementation analyses predict that the products are functionally similar and interacting. The alleles of Psc define two overlapping phenotypic classes, the hopeful and hapless. The distinctions between these two classes and the intragenic complementation seen among some of the Psc alleles are consistent with a multidomain structure for the product of Psc. Psc is a member of the homeotic Polycomb group of genes. A general discussion of the Polycomb and trithorax group of genes, position-effect variegation, transvection, chromosome pairing and chromatin structure is presented.
ATP-Binding Cassette Transporters↗
Shyness and little boy blue: iris pigmentation, gender, and social wariness in preschoolers.
In recent years, researchers have uncovered a link between iris pigmentation and inhibition/social wariness among young children (e.g., Rosenberg & Kagan, 1987, 1989; Rubin & Both, 1989). In the present study, 152 Caucasian preschool-aged (Mage = 54.09 months, SD = 5.84) children (77 males) with either blue (n = 84) or brown (n = 68) eyes, were compared in terms of parental and teacher ratings of social wariness, social play, and aggression. A significant Eye Color x Gender Interaction was found in terms of indices of social wariness; blue-eyed males were rated as more socially wary than brown-eyed males, while blue- and brown-eyed females did not differ in this regard. These results supported the notion that eye color is a marker variable for social wariness in young children.
Aggression↗
Structure of the Drosophila mutable allele, white-crimson, and its white-ivory and wild-type derivatives.
The white locus in Drosophila is required for a normal brick-red eye color; deletions of this locus result in a bleached-white eye color. The white-crimson (wc) allele of white was isolated as a partial revertant of another mutant white allele, white-ivory (wi), a mutation due to duplication of sequences within the white locus. The wc allele reverts at high frequencies to wild-type and wi phenotypes and generates white-eyed derivatives, including deletions with one endpoint at the white locus. We analyzed the structure of the wc allele by molecular cloning and by Southern blot analysis of genomic DNA and found that the wc phenotype results from the insertion of a 10 kilobase DNA sequence into the wi duplication. Five independent phenotypic revertants of wc to wi were examined, and in each case reversion was accompanied by apparently precise excision of the insertion. Reversion of wc to a wild-type phenotype in each of the six cases examined was mediated by excision of both the insertion and one copy of the wi duplication, restoring gene structure to wild-type.
Alleles↗
Some non-auditory correlates of the hearing threshold levels of an aviation noise-exposed population.
In a retrospective analysis of data collected during the 1963 followup of the NAMRL Thousand Aviator Study, two hearing level groups were identified, normal and impaired, and compared along 33 non-auditory dimensions. It was discovered that these two equally noise-exposed groups could be differentiated according to their smoking history and eye color. That is, the impaired hearing group reported smoking more cigarettes for a greater period of time than did the members of the normal hearing group. Furthermore, blue-eye individuals were over-represented in the impaired hearing group and under-represented in the normal hearing group, whereas the reverse was true for brown-eyed aviators. This latter finding is consistent with reports linking temporary hearing loss and eye color. There was 31 other physical, psychological, and sociological measures which failed to appear differentially in the two groups.
Adult↗
Structure and expression of wild-type and suppressible alleles of the Drosophila purple gene.
Viable mutant alleles of purple (pr), such as prbw, exhibit mutant eye colors. This reflects low 6-pyruvoyl tetrahydropterin (PTP) synthase activity required for pigment synthesis. PTP synthase is also required for synthesis of the enzyme cofactor biopterin; presumably this is why some pr alleles are lethal. The prbw eye color phenotype is suppressed by suppressor of sable [su(s)] mutations. The pr gene was cloned to explore the mechanism of this suppression. pr produces two PTP synthase mRNAs: one constitutively from a distal promoter and one in late pupae and young adult heads from a proximal promoter. The latter presumably supports eye pigment synthesis. The prbw allele has a 412 retrotransposon in an intron spliced from both mRNAs. However, the head-specific mRNA is reduced > 10-fold in prbw and is restored by a su(s) mutation, while the constitutive transcript is barely affected. The Su(s) protein probably alters processing of RNA containing 412. Because the intron containing 412 is the first in the head-specific mRNA and the second in the constitutive mRNA, binding of splicing machinery to nascent transcripts before the 412 insertion is transcribed may preclude the effects of Su(s) protein.
Alcohol Oxidoreductases↗
Inbreeding studies in Brasilian schoolchildren.
We present results of comparisons between consanguineous and control couples and their children in Southern Brasil. Multiple regression, t-test and chi 2 analyses were applied to the data. The following variables were investigated; Parents: structure of first cousin marriages, latitude and longitude of birthplaces, cohabitation time, rurality, marriage age, occupation, number of liveborn children, and frequency of twinning. Schoolchildren: clinical data as classified into 24 discontinuous traits, each one subdivided into two categories (number and severity), and seven continuous traits (weight, height, pulse rate, respiratory rate, systolic pressure, diastolic pressure, and temperature); nutrition indices and biotype; family names; intelligence tests and school performance; birth order, age, hair color, hair type, eye color, and skin color; twinning in the sibship, and infant mortality among sibs of the propositi. Our study showed a) nonrandomness of consanguineous marriages as detected on structural, racial, geographical, and temporal levels; b) a heavy mutational load of about 1.5 lethons acting on infant mortality; c) no inbreeding effect on morbidity in general (with a possible exception of "ear morbidity", including hearing deficit); d) a modest inbreeding depression on height (a decrease of 2 cm with an increase of 10% of inbreeding); 3) a suggestion of inbreeding depression on "intelligence".
Brazil↗
Halothane resistance in Drosophila melanogaster: development of a model and gene localization techniques.
Studying genetically altered animals that are resistant to inhaled anesthetics may ultimately lead to an understanding of anesthetics' mechanism(s) of action. We studied the genetics of halothane resistance in a strain of Drosophila melanogaster that showed substantially increased resistance to halothane anesthesia. We developed a test method that allowed us to repeatedly observe several samples of flies exposed to the same concentration of halothane, and we measured halothane resistance. The 50% effective dose (ED50) of 91R flies (our resistant population) was greater than the ED50 of Canton-S (our control strain) by 69% in females and by 48% in males. By assessing the contributions of the three major chromosomes of Drosophila to resistance, this study found that the X and third chromosomes of 91R have no effect on resistance, while the second chromosome has a major impact. Resistance within the second chromosome was further localized by testing marked recombinant chromosomes. The central region of 91R's second chromosome, bounded by the genes for black thoracic color and cinnabar eye color, determined most if not all of the increase in resistance. We were not able to further localize resistance within this segment of the second chromosome (containing about 8% of the total genetic map distance). An autosomal dominant gene for halothane resistance in 91R was localized to a small region of the second chromosome.
Anesthetics, Inhalation↗
[The color of the eyes: past "theories" and current "knowledge"].
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Eye Color↗
Frequency and characteristics of familial aggregation of Paget's disease of bone.
The cause of Paget's disease of bone (PDB) is unknown. In an attempt to ascertain the proportion of familial cases and evaluate the influence of genetic factors on the occurrence of the disease, a study was undertaken based on 35 PDB patients from our Unit. Their families were investigated, with the participation of a total of 128 first-degree relatives. Fourteen (40%) of these 35 index cases had at least one other first-degree relative affected with PDB and were defined as "familial." The remaining 21 (60%) were considered "sporadic." The frequency of males in the familial cases (79%) was significantly higher than among the sporadics (29%; p < or = 0.01). Mean age at diagnosis (63.1 +/- 12.6 vs. 71.3 +/- 8.7; p < or = 0.02), proportion of polyostotic cases (85.7% vs. 52.4%, p < or = 0.05), and mean number of involved bones per patient (4.36 +/- 2.50 vs. 2.33 +/- 1.93, p < or = 0.01) differ significantly in the familial and sporadic groups. The disease appears to be transmitted via both paternal and maternal sides, and pedigree analysis suggested an autosomal dominant inheritance or multifactorial mechanism. Apart from green-and-blue eye color, which was clearly associated with familial grouping (OR 6.25, 95% CI 1.15-37.16, p < or = 0.01), crude analysis on several genetically based traits and environmental variables revealed no other significant differences between the groups. The adjusted odds ratio estimated for green-and-blue eye color was 2.92 (95% CI 0.38-22.74).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Photoreactivation rescue and hypermutability of ultraviolet-irradiated excisionless Drosophila melanogaster larvae.
There is accumulating evidence suggesting that expression of genes for repair of UV damage to DNA in mammals and fish is regulated developmentally. Therefore, the activity of excision repair and photoreactivation in vivo in young larvae of Drosophila melanogaster was examined in a strain carrying the mutation mus201 that was unable to carry out excision repair. The photoreactivation activity in first-instar larvae was so high that UV-induced lethality in excision-less larvae was almost completely rescued by posttreatment with fluorescent light. Excision repair activity in first-instar repair-proficient larvae was so high that UV irradiation was scarcely able to produce somatic eye-color mutations. In contrast, excisionless larvae showed a high incidence of somatic eye-color mutation after UV-irradiation, and this incidence was reduced to the spontaneous level by posttreatment with fluorescent light. Incorporation of a postreplication repair-defective mutation into the excisionless strain decreased the incidence of UV-induced somatic mutations by a factor of 3. The analogous repair dependence of UV mutagenesis in Drosophila and Escherichia coli is discussed. It is proposed that UV-induced somatic mutations in excisionless Drosophila larvae are caused primarily by pyrimidine dimers and that a constitutive, error-prone pathway for filling daughter-strand gaps opposite dimers is, at least partly, responsible for the fixation of mutations.
Age Factors↗
New mutants and their chromosome assignment in the fly Megaselia scalaris.
We describe six new mutants, spontaneous or EMS-induced, and a previously isolated radiation-induced mutant of Megaselia scalaris Loew (Diptera, Phoridae). Five are eye-color mutants, one affects the segmentation of the abdomen, and one disturbs the regular form and arrangement of ommatidia in the compound eye. A complementation test exposed two pairs of alleles among the five eye-color mutants, leaving three different loci that affect eye pigmentation. Two of them influence the amount of xanthommatin synthesized, and one blocks the ommochrome pathway at the kynurenine step. We established chromosome assignment of the mutants by crossbreeding them with Y chromosome-autosome translocation strains.
Animals↗
Mobilization of two retroelements, ZAM and Idefix, in a novel unstable line of Drosophila melanogaster.
We describe a novel transposition system in a line of Drosophila melanogaster called RevI in which two retroelements are mobilized. These elements are the retroelement ZAM, recently described in the literature, and a novel element designated Idefix. Like ZAM, Idefix displays the structural features of a vertebrate retrovirus. Its three open reading frames encode predicted products resembling the products of the gag, pol, and env genes of retroviruses. In situ hybridization and Southern analyses performed on the RevI genome revealed the presence of some 20 copies of ZAM and Idefix, whereas ZAM is absent and Idefix is present in only four copies on the chromosomal arms of the original parental line. From RevI, a series of mutations affecting eye coloration has been recovered. The genetic and molecular analyses of these mutations have shown that most of them affected the white locus through three rounds of mutational events. The first mutational event was previously shown to be caused by a ZAM insertion 3 kb upstream of the transcription start site of white. It confers a red-brick phenotype to the orange eye coloration of the parental line. The second event results from the insertion of an Idefix copy 1.7 kb upstream of the transcription start site of the white gene, which modifies the red-brick phenotype to orange. This second mutational event was recovered as a recurrent specific mutation in 11 independent individuals. The third event results from an additional Idefix located 1.7 kb upstream of white that is responsible for the full reversion of the orange phenotype to red-brick. The fact that such mutations due to recurrent appearances of both ZAM and Idefix at the white locus result in such a variety of phenotypes brings to light a new molecular system in which the interference of mobile elements with the correct expression of the host gene can be tested.
Alleles↗
Transformation of white locus DNA in drosophila: dosage compensation, zeste interaction, and position effects.
P-element-mediated DNA transformation was used to generate transformants carrying segments of DNA from the white locus of D. melanogaster. The vast majority of transduced copies of an 11.7 or a 14.3 kb segment of DNA from white successfully rescued the white- eye-color phenotype when inserted in many different chromosomal locations. However, two transformants with abnormal eye pigmentation--apparently a consequence of the genomic positions of the transduced white gene--were also recovered. In all seven cases tested, autosomal insertions of white, which is dosage-compensated in its normal location on the X chromosome, retained the property of dosage compensation. In contrast to the relative insensitivity of eye-color pigmentation and dosage compensation to genomic position, the transduced white DNA segments differed widely in their interactions with the zeste mutation, ranging from greater than normal repression by zeste to insensitivity to the presence of zeste.
Animals↗
Unusual properties of regulatory DNA from the Drosophila engrailed gene: three "pairing-sensitive" sites within a 1.6-kb region.
We have previously shown that a 2-kb fragment of engrailed DNA can suppress expression of a linked marker gene, white, in the P element vector CaSpeR. This suppression is dependent on the presence of two copies of engrailed DNA-containing P elements (P[en]) in proximity in the Drosophila genome (either in cis or in trans). In this study, the 2-kb fragment was dissected and found to contain three fragments of DNA which could mediate white suppression [called "pairing-sensitive sites" (PS)]. A PS site was also identified in regulatory DNA from the Drosophila escargot gene. The eye colors of six different P[en] insertions in the escargot gene suggest an interaction between P[en]-encoded and genome-encoded PS sites. I hypothesize that white gene expression from P[en] is repressed by the formation of a protein complex which is initiated at the engrailed PS sites and also requires interactions with flanking genomic DNA. Genes were sought which influence the function of PS sites. Mutations in some Polycomb and trithorax group genes were found to affect the eye color from some P[en] insertion sites. However, different mutations affected expression from different P[en] insertion sites and no one mutation was found to affect expression from all P[en] insertion sites examined. These results suggest that white expression from P[en] is not directly regulated by members of the Polycomb and trithorax group genes, but in some cases can be influenced by them. I propose that engrailed PS sites normally act to promote interactions between distantly located engrailed regulatory sites and the engrailed promoter.
Animals↗
Effects of stimulus size, intensity, color, and eye strain on autokinetic movement: an error signal and noise analysis.
In two experiments, with a total of 116 male and female undergraduate S s, predictions were tested from the following hypothesized explanation of autokinetic movement (AKM): undetected eye drifts lead to movement of the AKM target across the retina; this movement or error signal leads to the initiation of a cancelling response, and the AKM is directly due to CNS monitoring of the efferent responses or signals sent to the eye muscles with subsequent detection of these signals against a background of efferent noise. The error signal variables studied were stimulus color (yellow or blue-green), stimulus intensity (dim or bright), and stimulus size (1.0 or .1 deg visual angle). Small, dim lights foveally viewed and yellow as opposed to blue-green lights led to significantly more error signals and hence more AKM as measured by mean number of perceived direction changes. Also, increasing retinal displacement by changing viewing angle (from zero to 60 deg) or increasing displacement by increasing diopter strength of prisms (from zero to 30) decreased AKM as measured by number of direction changes, and this effect is due at least in part to the increase in efferent noise caused by the increases in eye muscle tension involved. It was concluded that retinal displacement affects both error signal and noise variables in the AKM and, presumably, in the perception of real movement as well.
Color Perception↗
Genetics of an unstable white mutant in Drosophila simulans: reversion, suppression and somatic instability.
A spontaneous white mutation, white-milky (wmky) of Drosophila simulans is moderately unstable and is associated with a 16-kb long DNA insertion into the white gene. wmky, which is an unstable mutation found in D. simulans, has been genetically analyzed. Among nine spontaneous, partial reversions toward wild type, five were white locus mutations. They are phenotypically different from each other and three show eye color sexual dimorphism indicating a failure of the dosage compensation mechanism. Two w locus mutations whose eye color appeared identical between males and females were also isolated. Of the other back-mutants, three were associated with a recessive suppressor of wmky and one was a semidominant suppressor. These suppressor loci are located on the third chromosome at map positions about 90 and 120, respectively. The suppressor mutations demonstrate specific effects on w locus mutations derived from wmky which lack in the gene dosage compensation. Somatic instability was detected at the frequency of 5.6 X 10(-4) in wmky flies heterozygous for the recessive suppressor and the frequency was increased 10-fold when the suppressor mutation was placed in a different genetic background.
Alleles↗