Orientation disruptor (ord): a recombination-defective and disjunction-defective meiotic mutant in Drosophila melanogaster

The effects of a semidominant autosomal meiotic mutant, orientation disruptor (symbol: ord), located at 2-103.5 on the genetic map and in region 59B-D of the salivary map, have been examined genetically and cytologically. The results are as follows. (1) Crossing over in homozygous females is reduced to about seven percent of controls on all chromosomes, with the reduction greatest in distal regions. (2) Crossing over on different chromosomes is independent. (3) Reductional nondisjunction of any given chromosome is increased to about thirty percent of gametes from homozygous females. The probability of such nondisjunction is the same among exchange and nonexchange tetrads with the exception that a very proximal exchange tends to regularize segregation. (4) Equational nondisjunction of each chromosome is increased to about ten percent of gametes in homozygous females; this nondisjunction is independent of exchange. (5) The distributive pairing system is operative in homozygous females. (6) In homozygous males, reductional nondisjunction of each chromosome is increased to about ten percent, and equational nondisjunction to about twenty percent, of all gametes. (7) Cytologically, two distinct meiotic divisions occur in spermatocytes of homozygous males. The first division looks normal although occasional univalents are present at prophase I and a few lagging chromosomes are seen at anaphase I. However, sister chromatids of most chromosomes have precociously separated by metaphase II. Possible functions of the ord(+) gene are considered.     

Abnormal eye development associated with Cat4a, a dominant mouse cataract mutation on chromosome 8

PURPOSE: Cat4a, one of four mutant alleles at the mouse Cat4 locus, causes central corneal opacity and anterior polar cataract in heterozygotes and microphthalmia in homozygotes. The Cat4 locus has been mapped to chromosome 8, 31 cM from the centromere. In this study ocular development of Cat4a mutant mice was investigated to characterize the defects in eye morphogenesis. METHODS: Serial sections from eyes of wild-type, heterozygous, and homozygous littermates were examined by means of light microscopy at selected intervals from embryonic day 11 to postnatal day 1. Eyes of adult heterozygous and homozygous mice also were evaluated histologically. RESULTS: Failure of separation of the lens vesicle from the surface ectoderm was the earliest structural defect observed. In heterozygous embryos, the abnormality was limited to persistent connection of the anterior pole of the lens to the cornea. Adult heterozygotes had defects in the central corneal stroma and endothelium and anterior polar cataracts with or without keratolenticular adhesion. In homozygous embryos, the persistent connection of lens to surface ectoderm was associated with aborted lens development, failure of closure of the optic fissure, and impairment of growth of the eyecup. Microphthalmic eyes of adult homozygous mice had a poorly developed cornea, and the anterior chamber and vitreous compartment were absent. An extensively folded retina and remnants of a degenerated lens filled the interior of the globe. CONCLUSIONS: A developmental defect inhibits separation of the lens vesicle from surface ectoderm in mice heterozygous or homozygous for the Cat4a mutation. In homozygotes subsequent lens and eye morphogenesis are also severely affected. Cat4a shows phenotypical similarity to several other independent mouse mutations including Small eye, a mutation of the Pax6 gene. Cat4 may be one of several genes involved in a common developmental path and may be part of the Pax6-regulated gene cascade governing eye morphogenesis.     

Paternal loss (pal): a meiotic mutant in Drosophila melanogaster causing loss of paternal chromosomes

The effects of a male-specific meiotic mutant, paternal los (pal), in D. melanogaster have been examined genetically. The results indicate the following: (1) When homozygous in males, pal can cause loss, but not nondisjunction, of any chromosome pair. The pal-induced chromosome loss produces exceptional progeny that apparently failed to receive one, or more, paternal chromosomes and, in addition, mosaic progeny during whose early mitotic divisions one or more paternal chromosomes were lost. (2) Only paternally derived chromosomes are lost. (3) Mitotic chromosome loss can occur in homozygous pal+progeny of pal males. (4) Chromosomes differ in their susceptibility to pal-induced loss. The site responsible for the insensitivity vs. sensitivity of the X chromosome to pal mapped to the basal region of the X chromosome at, or near, the centromere. From these results, it is suggested that pal+acts in male gonia to specify a product that is a component of, or interacts with, the centromeric region of chromosomes and is necessary for the normal segregation of paternal chromosomes. In the presence of pal, defective chromosomes are produced and these chromosomes tend to get lost during the early cleavage divisions of the zygote. (5) The loss of heterologous chromosome pairs is not independent; there are more cases of simultaneous loss of two chromosomes than expected from independence. Moreover, an examination of cases of simultaneous somatic loss of two heterologs reveals an asymmetry in the early mitotic divisions of the zygote such that when two heterologs are lost at a somatic cleavage division, almost invariably one daughter nucleus fails to get either, and the other daughter nucleus receives its normal chromosome complement. It is suggested that this asymmetry is not a property of pal but is rather a normal process that is being revealed by the mutant. (6) The somatic loss of chromosomes in the progeny of pal males allows the construction of fate maps of the blastoderm. Similar fate maps are obtained using data from gynandromorphs and from marked Y chromosome (nonsexually dimorphic) mosaics.     

Behavior and single gene substitution in Drosophila melanogaster. I. Mating and courtship differences with w, cn, and bw loci

The effect of single allele substitutions into an isogenic background in Oregon-R inbred lines of Drosophila melanogaster on courtship and mating patterns has been studied. A comparison has been made between the white locus w, wco, we, the wild type w+, cn, bw, and cn bw to test the effect of eye pigmentation in influencing courtship and mating patterns. It was found that w, we, wco, cn, and bw females were more successful in mating than were wild-type and cn bw females, cn bw females being less successful than wild-type females. Also, w and cn bw males were equally successful in mating but less successful than wild-type males during the 20-min test period. The mutant males performed as well as the wild-type after courtship was initiated. The behavioral parameters measured were (1) courtship latency, the time from exposure of male to female until orientation; (2) mating speed, the time from beginning of orientation of male to female until successful copulation, and (3) copulation time.     

Erythroid Krüppel-like transcription factor (Eklf) maps to a region of mouse chromosome 8 syntenic with human chromosome 19

The effects of fatty acids, including oleate, on the interaction between furosemide and valproic acid in sera at respective serum therapeutic concentration levels were investigated using an ultrafiltration technique. The free fraction of furosemide was significantly increased in the presence of valproic acid. Mutual displacement experiments indicated that furosemide and valproic acid share a common high affinity binding site on human serum albumin (HSA). The serum free fraction of furosemide was increased by the presence of six or more fatty acid molecules per HSA molecule. This fatty acid-induced increase in the unbound fraction of furosemide was further increased by the binding of valproic acid. However, the inhibition of furosemide binding to serum for a fatty acid-valproic acid-furosemide system is nearly the same as the additive effect of fatty acid and valproic acid on the furosemide to serum. Thus, the mechanism for the displacement of HSA-bound furosemide by valproic acid was concluded to be different from that for fatty acid-catalyzed displacement.     

The molybdoenzyme system of Drosophila melanogaster. I. Sulfite oxidase: identification and properties. Expression of the enzyme in maroon-like (mal), low-xanthine dehydrogenase (lxd), and cinnamon (cin) flies

Sulfite oxidase (sulfite: ferricytochrome c oxidoreductase; EC 1.8.2.1) has been detected in Drosophila melanogaster and some of its properties have been studied. In most respects this enzyme resembles the mammalian sulfite oxidases except for its molecular weight (148,000), which is somewhat higher than that of rat sulfite oxidase (116,000). Cytochrome c, potassium-ferricyanide, and oxygen can serve as electron acceptors in the oxidation of sulfite by the enzyme. Although definite evidence can be obtained only through the analysis of the pure enzyme, experiments involving tungstate feeding suggest that Drosophila sulfite oxidase is most probably a molybdoenzyme. Extracts of mal flies show normal levels of sulfite oxidase, whereas lxd flies have only 5-10% of the activity of wild type, and in cin flies the enzyme is apparently absent. While it is possible that the lxd and cin mutations are at some level responsible for the defective synthesis of a molybdenum-containing cofactor (supposed to be present in most molybdoenzymes), the evidence accumulated so far by several authors and the results of the present investigation argue against the involvement of a Mo cofactor in the multiple enzyme deficiencies observed in mal flies.     

Sex determination in dioecious Silene latifolia. Effects of the Y chromosome and the parasitic smut fungus (Ustilago violacea) on gene expression during flower development

We have embarked on a molecular cloning approach to the investigation of sex determination in Silene latifolia Poiret, a dioecious plant species with morphologically distinguishable sex chromosomes. One of our key objectives was to define a range of genes that are up-regulated in male plants in response to Y chromosome sex-determination genes. Here we present the characterization of eight male-specific cDNA sequences and classify these according to their expression dynamics to provide a range of molecular markers for dioecious male flower development. Genetically female S. latifolia plants undergo a partial sex reversal in response to infection by the parasitic smut fungus Ustilago violacea. This phenomenon has been exploited in these studies; male-specific cDNAs have been further categorized as inducible or noninducible in female plants by smut fungus infection. Analysis of the organ-specific expression of male-specific probes in male and female flowers has also identified a gene that is regulated in a sex-specific manner in nonreproductive floral tissues common to both male and female plants. This observation provides, to our knowledge, the first molecular marker for dominant effect of the Y chromosome in nonreproductive floral organs.     

High-frequency retrotransposition of a marked I factor in Drosophila melanogaster correlates with a dynamic expression pattern of the ORF1 protein in the cytoplasm of oocytes

To study the expression of the I factor, a non-long-terminal-repeat retrotransposon responsible for I-R hybrid dysgenesis in Drosophila melanogaster, we have tagged the ORF1 protein (ORF1p) by inserting the HA epitope in its N-terminal region. In transgenic flies, this modification is compatible with a high rate of autonomous transposition and allows direct estimation of the transposition frequency. I factor transposes in the germline of females (SF) that are daughters from crosses between I strain males (which contain active copies of the I factor) and R strain females (which do not). We analyzed the expression pattern of ORF1p by indirect immunofluorescence. Its expression correlates with retrotransposition. During oogenesis ORF1p appears unexpectedly as a cytoplasmic product, which accumulates with a specific pattern into the oocyte. A comparison of the expression patterns under conditions that modify the transposing activity of the element clarifies some aspects of I-factor functioning in the transposition process.     

Su(UR)ES: a gene suppressing DNA underreplication in intercalary and pericentric heterochromatin of Drosophila melanogaster polytene chromosomes

A genetic locus suppressing DNA underreplication in intercalary heterochromatin (IH) and pericentric heterochromatin (PH) of the polytene chromosomes of Drosophila melanogaster salivary glands, has been described. Found in the In(1)scV2 strain, the mutation, designated as Su(UR)ES, was located on chromosome 3L at position 34. 8 and cytologically mapped to region 68A3-B4. A cytological phenotype was observed in the salivary gland chromosomes of larvae homozygous and hemizygous for Su(UR)ES: (i) in the IH regions, that normally are incompletely polytenized and so they often break to form "weak points," underreplication is suppressed, breaks and ectopic contacts disappear; (ii) the degree of polytenization in PH grows higher. That is why the regions in chromosome arm basements, normally beta-heterochromatic, acquire a distinct banding pattern, i. e., become euchromatic by morphological criteria; (iii) an additional bulk of polytenized material arises between the arms of chromosome 3 to form a fragment with a typical banding pattern. Chromosome 2 PH reveals additional alpha-heterochromatin. Su(UR)ES does not affect the viability, fertility, or morphological characters of the imago, and has semidominant expression in the heterozygote and distinct maternal effect. The results obtained provide evidence that the processes leading to DNA underreplication in IH and PH are affected by the same genetic mechanism.     

Computer-assisted training in genetically-induced neuropsychological deficits. A case report of a patient with de Grouchy syndrome I (chromosome 18 p syndrome)

The present case study is a report on computer-based training approach in a male patient suffering from the de-Grouchy syndrome I (with a characteristic chromosomal deletion pattern), who along with psychotic symptoms displayed neuropsychological deficits. Participating in a well-established intervention programme aimed at a broad spectrum of psychological functions, the patient went through 36 training sessions. With regard to outcome assessments one focus was on improved performance in the training tasks, while the other one referred to transfer effects, as indexed by a neuropsychological test battery which was given before and after the entire programme. In both areas substantial gains from training emerged according to the collected data. In view of these results neuropsychological training approaches appear to have a perspective even in behavioural deficits with a genetic basis.     

Survey of malathion resistance and avermectin susceptibility in field populations of Drosophila melanogaster (Diptera: Drosophilidae) and D. simulans

Populations of Drosophila melanogaster (Meigen) and Drosophila simulans (Sturtevant) from various geographic locations in North America and elsewhere were sampled to assess the distribution of malathion resistance and avermectin tolerance. Comparisons are made to previous reports of a differential response to malathion selection in these species. Results indicate that for malathion, resistance is widespread in D. simulans but varies considerably in D. melanogaster. For avermectins, although the pattern of tolerance is similar in both species, there exists a significant amount of variation in these levels between geographic regions. We consider how these different geographic patterns of resistance distribution may shed insight on the relative roles of population structure and exposure history in affecting the spread of resistance. In addition, we consider further the use of D. melanogaster and D. simulans as a model for examining the effects of insecticide exposure on sympatric populations.     

Mosaicism for a small supernumerary ring X chromosome in a dysmorphic, growth-retarded male: mos47,XXY/48,XXY, +r(X)

Supernumerary ring X [r(X)] chromosomes are often found in patients with Turner syndrome. The phenotypic effects of the r(X) chromosome are variable, and largely depend on the presence or absence of the X inactivation (XIST) locus. Ring(X) chromosomes in males are rare and have been previously reported in only four cases, with 47,XY, + r(X) or mos47,XY, +r(X)/46,XY karyotypes. These patients all had developmental delay and dysmorphic features. We describe a 2.5-year-old male patient with facial dysmorphia, growth retardation, microcephaly, global developmental delay, and microphallus. Cytogenetic analysis from peripheral blood lymphocytes and fibroblasts identified mosaicism for two cell lines: mos48,XXY, + r(?X)/47,XXY. Fluorescence in situ hybridization (FISH) with an X chromosome paint showed the ring chromosome to be X chromosome derived. This is the first case of an r(X) chromosome described in a 47,XXY patient. FISH analysis of the r(X) chromosome with an XIST probe showed that the XIST locus was absent. Functional disomy of genes in the r(X) chromosome most likely accounts for the abnormal phenotype in the proband.     

Evolution of nerve development in frogs. I. The development of the peripheral nervous system in Discoglossus pictus (Discoglossidae)

The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle development which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shift during evolution of PNS development in frogs.     

Executive functions in young males with fragile X syndrome in comparison to mental age-matched controls: Baseline findings from a longitudinal study.

The performance of 54 boys with fragile X syndrome (FXS), ages 7 to 13 years, was compared to that of a group of typically developing boys who were matched on mental age (MA) and ethnicity across multiple measures of executive function (EF). Boys with FXS varied in their ability to complete EF measures, with only 25.9% being able to complete a set-shifting task and 94.4% being able to complete a memory for word span task. When compared to the control group, and controlling for MA and maternal education, boys with FXS showed significant deficits in inhibition, working memory, cognitive flexibility/set-shifting, and planning. No group differences were observed in processing speed. Mental age significantly impacted performance on working memory, set-shifting, planning, and processing speed tasks for both groups. In boys with FXS, MA significantly predicted performance on working memory and set-shifting tasks. Our findings suggest that deficits in EF in boys with FXS are not solely attributable to developmental delays but, rather, present as a true array of neurocognitive deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

small wing encodes a phospholipase C-(gamma) that acts as a negative regulator of R7 development in Drosophila

Phospholipase C-(gamma) (PLC-(gamma)) is activated in many cell types following growth factor stimulation. Our understanding of the role of PLC-(gamma) in cell growth and differentiation has been severely limited by the dearth of mutations in any organism. In this study, we show that the Drosophila gene small wing (sl), identified by Bridges in 1915, encodes a PLC-(gamma). Mutations of sl result in extra R7 photoreceptors in the compound eye, consistent with overactivation of the receptor tyrosine kinase pathways that control R7 development. The data presented here provide the first genetic evidence that PLC-(gamma) is involved in Ras-mediated signaling and indicate that PLC-(gamma) acts as a negative regulator in such pathways in Drosophila.     

Sex role attitudes and mathematical ability in 4th-, 8th-, and 11th-grade students from a high socioeconomic area.

Examined gender differences in mathematical ability, relationship of sex-role attitudes to mathematical ability, and age-related changes in attitude toward math. 317 4th, 8th, and 11th graders of high SES were given a sex-role standards attitude scale and either the Stanford Mathematics Achievement Test or the Stanford Diagnostic Mathematics Test. Overall, no significant differences by sex were found in math ability. Sex-role attitudes related to higher math scores at the 4th- and 8th-grade levels. Females tended to express positive attitudes toward mathematics at all grade levels—significantly more so than males at the 11th-grade level. Implications are discussed in terms of culturally influenced sex-role attitudes and characteristics of this SES. Girls of this SES may receive more parental encouragement and have different role models than average children. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)