Mutations affecting expression of the rosy locus in Drosophila melanogaster

The rosy locus in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase (XDH). Previous studies defined a "control element" near the 5' end of the gene, where variant sites affected the amount of rosy mRNA and protein produced. We have determined the DNA sequence of this region from both genomic and cDNA clones, and from the ry+10 underproducer strain. This variant strain had many sequence differences, so that the site of the regulatory change could not be fixed. A mutagenesis was also undertaken to isolate new regulatory mutations. We induced 376 new mutations with 1-ethyl-1-nitrosourea (ENU) and screened them to isolate those that reduced the amount of XDH protein produced, but did not change the properties of the enzyme. Genetic mapping was used to find mutations located near the 5' end of the gene. DNA from each of seven mutants was cloned and sequenced through the 5' region. Mutant base changes were identified in all seven; they appear to affect splicing and translation of the rosy mRNA. In a related study (T. P. Keith et al. 1987), the genomic and cDNA sequences are extended through the 3' end of the gene; the combined sequences define the processing pattern of the rosy transcript and predict the amino acid sequence of XDH.

Sequence of the structural gene for xanthine dehydrogenase (rosy locus) in Drosophila melanogaster

We determined the nucleotide sequence of a 4.6-kb EcoRI fragment containing 70% of the rosy locus. In combination with information on the 5' sequence, the gene has been sequenced in entirety. rosy cDNAs have been isolated and intron/exon boundaries have been determined. We find an open reading frame which spans four exons and would encode a protein of 1335 amino acids. The molecular weight of the encoded protein (xanthine dehydrogenase), based on the amino acid translation, is 146,898 daltons which agrees well with earlier biophysical estimates. Characteristics of the protein are discussed.

Molecular mapping of the rosy locus in Drosophila melanogaster

The DNA from the chromosomal region of the Drosophila rosy locus has been examined in 83 rosy mutant strains. Several spontaneous and radiation-induced alleles were associated with insertions and deletions, respectively. The lesions are clustered in a 4-kb region. Some of the alleles identified on the DNA map have been located on the genetic map by fine-structure recombination experiments. The genetic and molecular maps are collinear, and the alignment identifies the DNA location of the rosy control region. A rosy RNA of 4.5 kb has been identified; its 5' end lies in or near the control region.

Rhodopsin's amino terminus is a principal antigenic site

Antisera and monoclonal antibodies to rhodopsin were examined for their binding specificity to rhodopsin by using peptides from the rhodopsin sequence as competitors for antibody binding to rhodopsin in an enzyme-linked immunoassay. Monoclonal antibodies tested were raised in mice against bovine and rat rhodopsin. Antisera tested were raised in sheep against bovine rhodopsin and in rabbits against human rhodopsin. Peptides were synthesized from the bovine rhodopsin sequences 2-32, 1-12, 13-23, 24-34, 5-11, 231-252 and 331-348 for use as competitors in the immunoassay. A mixture of soluble CNBr peptides, and the purified CNBr peptide representing the sequence 2-39 were also employed. The monoclonal antibodies were all anti-amino-terminal in their binding specificity, although each recognized slightly different regions of the amino terminus. Each of the three antisera was predominantly directed against rhodopsin's amino terminus. We conclude that the amino-terminal 30 or more amino acids, and particularly the amino-terminal 15 amino acids, represent a principal antigenic region of the rhodopsin molecule.

Analysis of cell types identifiable in air-dried cell preparations of human testis

The mixed cell population of the testicular epithelium has been studied in air-dried cell preparations obtained from a testicular biopsy. Observed cell types are defined, quantified and assigned to cell stages of the spermatogenic cycle. Studies with tritiated thymidine helped to categorize the spermatogonial cell types. Variation in cell size within cell categories, variation in frequency of cells in different categories within individuals, and variation in frequency of cells within categories between individuals were subjected to quantitative analysis.

X-linked Ehlers-Danlos syndrome type V; the next generation

Two English families with the X-linked form (Type V) of the Ehlers-Danlos syndrome (EDS) who were investigated almost 20 years ago have been re-studied. In one family, the potentially heterozygous sister of 3 affected brothers had born two sons, of whom one has EDS. The 3 brothers had all procreated, producing a total of 2 sons and 3 daughters, all of whom are clinically normal. These pedigree data provide further evidence to support the syndromic identity and X-linked mode of inheritance of this form of the EDS. In the second family, two affected brothers had both procreated; one had produced three normal offspring, while the other had a son with soft extensible skin and a daughter with articular hypermobility. The syndromic status of this kindred is uncertain. Serum copper and ceruloplasmin concentrations in affected males and obligate carrier females in both families were normal. Cytogenetic investigations, including high resolution banding, yielded normal results.

Grebe chondrodysplasia and brachydactyly in a family

A family is reported in which various skeletal abnormalities have been segregating over three generations. The Great-grandfather (11) of the consultand had features consistent with Grebe chondrodysplasia. The other members of the family have brachydactyly, radiologically characterised by short first metacarpals and short middle phalanges of the index and little fingers. The possibility of association of familial brachydactyly and Grebe chondrodysplasia is discussed. An attempt has been made to deal with the genetic counselling problem in this particular family.

Chromosome banding: specification of structural features of dyes giving rise to G-banding

Metaphase chromosomes were stained in a routine G-banding procedure with 39 basic dyes of varied structures substituted for the Giemsa stain. Staining outcomes were categorized as: overstained, differentially stained, trivially or unstained. Certain structural features of the dyes were described numerically, namely, largest conjugated fragment (LCF), conjugated bond number (CBN) and cationic weight. The staining outcomes were compared to these numerical structural parameters, and structure--staining correlations sought. Dyes with large conjugated systems (and high LCF values) were seen to be overstained; dyes with low LCF values were often non-staining. At intermediate LCF values, the more hydrophobic dyes (with high Hansch pi values) stained differentially; the more hydrophilic dyes failed to stain. Expressed numerically, 89% of the dyes with the following characteristics stained differentially: 30 greater than or equal to LCF greater than or equal to 10; Hansch pi greater than -5.0. It was concluded that contributions to dye-chromosome affinity included coulombic forces and van der Waals attractions and that the selectivity of G-banding was largely due to hydrophobic bonding. Induction of bands could be due to the loss of hydrophilic histones, amplifying underlying variations in the hydrophobic-hydrophilic character of the chromosome structure. Relatively hydrophobic sites include AT-rich DNA and disulphide-rich proteins. The effects on Romanowsky G-banding of chemically modifying chromosomes were in keeping with this model. Overstaining resulted from formation of either hydrophobic or conjugated derivatives or both, whereas trivial or non-staining arose from the formation of hydrophilic derivatives. Intriguingly, the efficacy of the dyes used for Q-banding also correlated positively with their hydrophobic character.

Cytogenetic and histological studies in a series of subfertile males

Cytogenetic and histological studies were carried out on a series of 68 men during investigations for subfertility. Somatic chromosome analysis identified 4 cases with abnormal karyotypes. Meiotic chromosome analysis identified 4 cases with abnormal meiosis. Analysis of cell stages of the spermatogenic cycle in cytogenetic preparations identified 12 cases with missing cell cycle stages. Histological analysis of tissue samples identified defects of the spermatogenic cycle in 23 cases. A kinetic model of spermatogenesis is used in order to relate the different types of abnormality to the spermatogenic cycle.

Through the looking glass: history-taking revisited

Traditional teaching of history-taking stops short of assisting the learner to evaluate the doctor-patient relationship, and incorporate this into clinical decision making. The evolution of specific programs in interviewing skills is reviewed, emphasizing the content and process of the medical interview and newer teaching methods being used in these programs. Improved methods of evaluating the effectiveness of these programs, including increased patient and physician satisfaction, will form part of the future direction of residency programs in family medicine. (Can Fam Physician 1981; 27:827-830).

Methyldopa-induced pancreatitis

An acute febrile illness associated with gastrointestinal upset developed in a patient within one week after starting treatment with methyldopa. The illness was characterized by prompt subsidence of symptoms when the patient withdrew therapy secondary to gastrointestinal upset, and recrudescence of symptoms when methyldopa therapy was reinitiated. This was associated with hyperamylasemia, hyperlipasemia, hyperpyrexia, and epigastric pain, both on admission to the hospital and upon rechallenge with methyldopa. Although gastrointestinal upset has been reported as an untoward side effect of methyldopa, this is the first report to our knowledge of documented methyldopa-induced hyperamylasemia and hyperlipasemia secondary to pancreatitis.