Molecular characterization of spontaneous mutations at the scarlet locus of Drosophila melanogaster

Six spontaneous mutations of the scarlet (st) locus of Drosophila melanogaster have been studied at the molecular level. Two of the mutants (st1 and stsp) arose in laboratory populations, while the other four (stcob, stct89, stdct and stdv) were isolated from natural populations. In five of these there is a DNA insertion within the st region and in four cases the insertion has been identified as being a transposable element; these include the retrotransposons 412 and B104/roo, and also jockey a member of the LINE family. In the other case (stdct), the insertion appears to consist of partially duplicated st sequences. In two of the mutants (st1 and stdv) the same transposable element (412) has inserted in the same orientation at exactly the same site within the st gene. The transposable element insertions are found in intron and exon regions of the st gene and also in the putative upstream regulatory region; insertions located in introns or exons result in the production of truncated st transcripts. The results show that the same types of transposable elements that cause spontaneous mutation in laboratory stocks of D. melanogaster also cause mutation in the wild.

White as a reporter gene to detect transcriptional silencers specifying position-specific gene expression during Drosophila melanogaster eye development

The white+ gene was used as a reporter to detect transcriptional silencer activity in the Drosophila genome. Changes in the spatial expression pattern of white were scored in the adult eye as nonuniform patterns of pigmentation. Thirty-six independent P[lacW] transposant lines were collected. These represent 12 distinct pigmentation patterns and probably 21 loci. The spatial pigmentation pattern is due to cis-acting suppression of white+ expression, and the suppression probably depends on cell position rather than cell type. The mechanism of suppression differs from inactivation by heterochromatin. In addition, activation of lacZ in P[lacW] occurs also in specific patterns in imaginal discs and embryos in many of the lines. The expression patterns of white+ and lacZ may reflect the activity of regulatory elements belonging to an endogenous gene near each P[lacW] insertion site. We speculate that these putative POSE (position-specific expression) genes may have a role in pattern formation of the eye as well as other imaginal structures. Three of the loci identified are optomotor-blind, engrailed and invected. teashirt is also implicated as a candidate gene. We propose that this "silencer trap"' may be an efficient way of identifying genes involved in imaginal pattern formation.

The silver gene of Drosophila melanogaster encodes multiple carboxypeptidases similar to mammalian prohormone-processing enzymes

The silver (svr) gene of Drosophila melanogaster is required for viability, and severe mutant alleles result in death prior to eclosion. Adult flies homozygous or hemizygous for weaker alleles display several visible phenotypes, including cuticular structures that are pale and silvery in color due to reduced melanization. We have identified and cloned the DNA encoding the svr gene and determined the sequence of several partially overlapping cDNAs derived from svr mRNAs. The predicted amino acid sequence of the polypeptides encoded by these cDNAs indicates that the silver proteins are members of the family of preprotein-processing carboxypeptidases that includes the human carboxypeptidases E, M, and N. One class of svr mRNAs is alternatively spliced to encode at least two polyproteins, each of which is composed of two carboxypeptidase domains.

The molecular analysis of brown eye color mutations isolated from geographically discrete populations of Drosophila melanogaster

A large proportion of spontaneous mutations in Drosophila melanogaster strains of laboratory origin are associated with insertions of mobile DNA elements. As a first step toward determining whether spontaneous laboratory mutations are predictive for mutational events occurring in the wild, recessive brown (bw) eye color mutants were isolated. By inbreeding the progeny of wild-caught Drosophila melanogaster females, bw mutations were isolated from seven separate geographic sites distributed among Japan, California. Siberia and Hungary. Among a total of 14 mutations studied, no case of transposon mutagenesis was found. At least 4 mutations are associated with small deletions in the bw gene. The remainder are inseparable from wild-type bw by Southern analysis and are presumed to be basepair changes or very small indels. Although only two spontaneous bw mutants of laboratory origin have been analyzed molecularly, one is a mobile element insertion.

An intragenic tandem duplication of genomic DNA is responsible for the f3N mutation of Drosophila melanogaster

Among the numerous X chromosome-linked forked bristle (f) mutations described in Drosophila melanogaster, one designated f3N exhibits the unusual property of reverting spontaneously to wild type at an inordinate frequency, a frequency that can be increased with x-ray irradiation. In contrast to the f mutants described thus far, all of which are associated with the insertion of mobile DNA elements, f3N is associated with an intragenic duplication of 2.8 kb of genomic DNA that resolves to the normal sequence when reversions occur. Consideration is given to intrachromosomal recombination as the mechanism of reversion and truncation of the forked protein as a cause for the mutant phenotype.

Abdominal gestation

Abdominal pregnancy is such an unusual form of ectopic gestation that the diagnosis is often missed or delayed. We report three cases, each with a different clinical presentation. A careful history and evaluation in the Emergency Department (ED), along with liberal and timely use of ultrasonography, are critical for prompt diagnosis and treatment. Features such as abdominal pain inconsistent with a previous presumptive diagnosis, or repeated ED visits, in a patient with a positive beta-HCG test, are suggestive of this diagnosis.

Undiagnosed post-traumatic stress disorder following motor vehicle accidents

OBJECTIVES

To determine the pattern of emergence of post-traumatic stress disorder (PTSD) among motor vehicle accident victims and to examine the influence of PTSD on subsequent levels of disability.

DESIGN

A longitudinal study of motor vehicle accident victims one month and 18 months after the accident.

SUBJECTS

Twenty-four motor vehicle accident victims admitted by the trauma team at the Royal Adelaide Hospital. A 52% response rate was achieved.

MAIN OUTCOME MEASURES

Post-traumatic stress disorder as diagnosed by the Diagnostic Interview Schedule and disability as measured with the Sickness Impact Profile.

RESULTS

Eighteen months after their accidents, six of the 24 subjects had clinically significant PTSD and one was considered borderline. None had been previously diagnosed or treated. The group with PTSD had higher scores on all measures of psychological distress one month after the accident and were more likely to use immature psychological defences. There was no association between physical outcome (measured with the modified Glasgow Outcome Scale) at six months and subsequent diagnosis of PTSD. However, the group with PTSD had higher levels of disability on assessment with the Sickness Impact Profile, particularly in the domain of social functioning. The results suggest PTSD was associated with work-related dysfunction equal to that associated with severe physical handicap.

CONCLUSION

The data from this pilot study suggest that PTSD after motor vehicle accidents is an important cause of disability, which may also become the focus for damages in litigation. Thus, there is a need for further investigation of the early patterns of distress and to design preventive programs for victims of road accidents.

Genetics and linkage mapping of Drosophila buzzatii

Of 51 visible mutants isolated from natural or laboratory populations of Drosophila buzzatii, or X-ray induced, 42 have been assigned to chromosomes, and linkage maps have been constructed. About half of the autosomal mutants map to chromosome 2, with only two on chromosome 3 and none on chromosome 4. For the whole repleta group, chromosome 2 also exhibits much greater inversion variability than other chromosomes, which suggests variation among chromosomes in apparent mutability. The chromosomes of D. buzzatii are homologized to those of D. melanogaster and to the standard chromosomal elements of Drosophila. Sequence comparisons for six X chromosome mutant genes, whose homology is reasonably certain, in 13 Drosophila species confirm linkage group conservation but great variation among species in gene order. The linkage group conservation of single-copy genes stands in contrast to observed transpositions between elements for tandem repeat genes.

Cloning and direct sequencing from lambda cDNA libraries using the polymerase chain reaction: suppressin and the vasopressin receptor as models

A strategy using the polymerase chain reaction (PCR) to screen a lambda gt11 pituitary cDNA library for cDNAs encoding suppressin, a putative anti-proliferative protein, and a putative vasopressin receptor is described. The use of this technique will facilitate the demonstration of e.g. the presence of "neuropeptide receptors" on cells of the lymphoid system, confirming the concept of "shared ligands and receptors" by the neuroendocrine and the immune system. Neither of the genes encoding the proteins of the present study have previously been cloned. The PCR-screening procedure requires sequence information from the gene of interest which permits the generation of complementary primers. These primers are then used in combination with lambda phage primers complementary to regions flanking the cloning site in a PCR to amplify cDNAs derived from the gene of interest. This novel screening procedure yields cDNA related to the gene of interest, including the largest clone present in the library. To confirm the utility of this technique for cDNA libraries, the library was also screened using traditional cDNA hybridization techniques. The largest clone obtained by screening the cDNA library with PCR was the same as that obtained by the conventional technique. Thus, the results of these studies show that the PCR method can be used instead of more conventional means to screen cDNA libraries. Lastly, we describe a protocol for directly sequencing PCR-amplified DNA using the same primers that are used for amplification. The combined use of these two strategies permits cloning and sequencing of cDNAs from lambda cDNA libraries in a fraction of the time required using traditional screening techniques, but with identical results.

Mutations in the su(s) gene affect RNA processing in Drosophila melanogaster

We have studied the effect of mutations in the suppressor of sable [su(s)] gene on P element-induced yellow alleles. Two independent mutations tested, y76d28 and y1#7, contain a 1.1-kilobase (kb) P element inserted in the 5' transcribed untranslated portion of the yellow gene. Sequences responsible for the y1#7 mutation are inserted in the same transcriptional orientation as yellow and cannot be processed by splicing, and this mutation is not suppressed by su(s) mutations. P element sequences are located in a transcriptional orientation opposite to that of the yellow gene in y76d28; these sequences can be spliced from a composite P element-yellow mRNA, resulting in low accumulation of a functional 1.9-kb yellow transcript. The levels of both the putative precursor P element-yellow RNA and the 1.9-kb yellow transcript increase in y76d28 su(s) flies, suggesting that mutations in su(s) do not affect the efficiency of splicing of the P element sequences. Analysis of y76d28 cDNAs isolated from flies carrying a wild-type or mutant su(s) gene demonstrates that the choice of splice junctions to process P element sequences is unchanged in these different backgrounds, suggesting that mutations in su(s) do not affect the selection of donor and acceptor splice sites. We propose that the su(s) protein functions to control the stability of unprocessed RNA during the splicing reaction.

Structural studies on alkylisocyanate polymers by thermal degradation tandem mass spectrometry

Homopolymers and copolymers of alkylisocyanates having n-hexyl, 2,6-dimethylheptyl, 3,7-dimethyloctyl, and (2,2-dimethyl-1,3-dioxolan-4-yl)methyl substituents underwent thermal degradation in the course of desorption electron ionization to yield trimers and monomers that were characterized in situ by tandem mass spectrometry. The trimers were trisubstituted cyanuric acids, the protonated molecules displaying a characteristic series of alkene eliminations on collision-induced dissociation to yield protonated cyanuric acid, m/ z 130. Confirmation of the identity of the pyrolysates was obtained by using two types of MS3 experiments: the reaction intermediate scan and the two-dimensional familial scan. The ion chemistry of the trimers and of the protonated monomer, the alkylisocyanate, was elucidated. Among the many interesting fragmentation processes undergone by the ionized trimers were a and 3 C-C bond cleavages and charge-remote fragmentations, which provided information on branching in the alkyl substituent. The dioxolane-containing substituent showed unique ion chemistry. The monomer distribution in the copolymers was deduced from the abundances of the various protonated trimers. The distribution was found to be random in all copolymers except that containing the dioxolane substituent.

Acute pelvic inflammatory disease after surgical sterilization

STUDY OBJECTIVE

Physicians are very cognizant of the possibility of pregnancy after surgical sterilization, but the potential for acute pelvic inflammatory disease (PID) is thought to be rare. This study was undertaken to determine if upper tract PID occurred more frequently than previously reported in patients remote from surgical sterilization.

DESIGN

Retrospective review of hospitalized patients with the primary discharge diagnosis of PID.

SETTING

Urban, university hospital.

PARTICIPANTS

Three hundred sixty-four hospitalized patients with the primary discharge diagnosis of PID over a six-year study period.

MEASUREMENTS AND MAIN RESULTS

Patients' age; gynecologic histories and diagnoses; and laboratory, clinical, and surgical findings were noted. Twenty-three cases of acute PID were identified in 21 patients previously sterilized (6%). Nine of the 23 cases had systemic toxicity warranting surgical evaluation; 18 of the 23 cases were admitted from the emergency department. Mean statistical characteristics of the study group were age, 27.3 +/- 0.8 (SE) years; time interval from sterilization, 49.8 +/- 7.4 months; WBC 15,000 +/- 1,200; and temperature, 38.0 +/- 0.2 C.

CONCLUSION

We conclude that acute PID may occur more frequently than previously reported in patients with prior surgical sterilization. An increased awareness of this entity is warranted.

Immunomodulatory characteristics of a novel antiproliferative protein, suppressin

We investigated the immunoregulatory properties of a recently described inhibitor of lymphocyte proliferation, suppressin (SPN). It was determined that preincubation of murine leukocytes with SPN enhances natural killer cell (NK) activity. In addition, SPN potentiates interferon-gamma (IFN-gamma) augmentation of NK activity. Furthermore, preincubation of murine leukocytes with SPN induces the production of IFN-alpha/beta. The IFN-alpha/beta produced is active in NK assays as well as vesicular stomatitis virus neutralization assays. In vivo, SPN increases the time of survival of C57BL/6 mice injected with EL-4 lymphoma cells. Interestingly, SPN inhibits immunoglobulin (IgA, IgG, and IgM) production in response to the mitogen, concanavalin A in a dose-dependent manner. Collectively, the above data indicate SPN may have numerous applications in clinical science including tumor surveillance and autoimmune diseases such as arthritis.

Tissue-specific transcriptional enhancers may act in trans on the gene located in the homologous chromosome: the molecular basis of transvection in Drosophila

The y2 mutation resulted from the insertion of the gypsy element into the X-linked yellow locus of Drosophila melanogaster. As a consequence of this insertion, transcriptional enhancers that control the expression of the yellow gene in the wings and body cuticle of adult flies are unable to act on the yellow promoter, resulting in a tissue-specific phenotype characterized by mutant coloration in these structures. Some yellow null alleles (yn) are able to complement the y2 phenotype giving rise to near wild type y2/yn females. The molecular structure of the yellow locus in complementing and noncomplementing mutations was determined by cloning and sequencing the various alleles examined. From the information obtained in these studies, we propose a model suggesting that the complementing wild type phenotype of y2/yn flies might be due to the ability of functional wing and body cuticle transcriptional enhancers located in the yn locus to act in trans on the promoter of the yellow gene found in the y2-containing chromosome. Furthermore, this transactivation is abolished by the presence of an intact promoter in cis, suggesting that promoter competition between the yellow genes located on each homolog precludes the activation in trans by transcriptional enhancers in favour of cis effects on their own promoter.

Infrared tympanic thermography in the emergency department

The failure to diagnose hypothermic and hyperthermic states can have profound clinical implications. Thus, accurately determining body temperature is an integral component of the evaluation of all emergency department (ED) patients. Oral measurements are most commonly obtained but may not reflect core temperatures. Rectal temperatures are considered more reliable but may not reflect fluctuating core temperatures, and are dependent on site placement. The objective of this study was to determine the practicality and comparative accuracy of tympanic thermographic measurements in the ED. Oral, rectal and tympanic readings were compared in 411 patients. There were significant differences when comparing tympanic to oral (R2 = 0.599, P = 0.0001) and rectal to oral (R2 = 0.554, P = 0.0001) temperatures. In contrast, the correlation between tympanic and rectal measurements was R2 = 0.805, with no significant difference between the two, (P = 0.7077). No complications associated with the use of the tympanic probe were detected. Infrared tympanic thermography is an efficient and noninvasive technique for accurately measuring the temperature of ED patients.

Isolation of a cDNA encoding functional Drosophila alcohol dehydrogenase in Escherichia coli and purification of the bacterially produced enzyme

Because of the severe limitations on growing large quantities of Drosophila affinidisjuncta in the laboratory, direct purification of alcohol dehydrogenase (ADH) from this species has proven impossible. As an alternative source of this enzyme, a cDNA encoding functional ADH was isolated from a newly constructed cDNA library made from larval poly(A)-containing RNA. The cDNA was recovered by virtue of its hybridization to a previously isolated genomic ADH gene. Nucleotide sequence analysis confirmed the identity of the newly isolated cDNA. When the cDNA was inserted in the proper orientation downstream of the lac promoter on the vector pUC8, the cDNA directed the synthesis of functional ADH by the bacterial host. The bacterially produced enzyme was purified to homogeneity and used to elicit polyclonal antibodies in rabbits. The purified ADH has identical apparent subunit molecular weight to that of authentic ADH in larval fly extracts as determined by immunoblotting. Further, comparisons of the kinetic parameters of the bacterially produced enzyme and ADH activity in larval fly extracts indicate similar substrate preferences, pH dependencies, and Km values for 2-propanol and NAD. These results show that expression of a cDNA in Escherichia coli is a valid strategy for isolation of an ADH that would otherwise be difficult or impossible to purify.

Mutant gene phenotypes mediated by a Drosophila melanogaster retrotransposon require sequences homologous to mammalian enhancers

We have analyzed the molecular structure of phenotypic revertants of gypsy-induced mutations to understand the molecular mechanisms by which this retrotransposon causes mutant phenotypes in Drosophila melanogaster. The independent partial revertants analyzed are caused by the insertion of different transposons into the same region of gypsy. One partial revertant of the yellow allele y2 arose as a consequence of the insertion of the jockey mobile element into gypsy sequences, whereas a second incomplete revertant is due to the insertion of the hobo transposon. In addition, a previously isolated partial revertant of the Hairy-wing allele Hw1 resulted from the integration of the BS transposable element into the same gypsy sequences. The region affected by the insertion of the three transposons contains 12 copies of a repeated motif that shows striking homology to mammalian transcriptional enhancers. Our results suggest that these sequences, which might be involved in the transcriptional control of the gypsy element, are also responsible for the induction of mutant phenotypes by this retrotransposon.

Genetic instability in Drosophila melanogaster: P-element mutagenesis by gene conversion

We report the molecular characterization of several P element-induced mutations and their revertants at the yellow (y) locus of Drosophila melanogaster. One of the mutants analyzed, y76d28, results from the insertion of a P element into the 5'-transcribed, untranslated portion of the y gene. Sequence analysis of several revertants of y76d28 shows that P excision occurs imprecisely. These events result in insertion of additional ATG codons in the y locus mRNA but are without phenotypic effect. In addition, we describe the molecular structure of P-associated mutations induced in a near wild-type revertant of y76d28 that carries an internally deleted 0.4-kilobase P element in the 5' noncoding region. Sequence analysis of two of these mutants demonstrates that they arose as a result of the integration of a larger P element at the exact location as in the parental stock without the 8-base-pair additional duplication associated with P insertions. The phenotype of these y alleles is dependent on the size and orientation of the integrated P element. We infer that P-element replacement in these mutants has occurred by a recombination/gene conversion mechanism.

Reversion of a gypsy-induced mutation at the yellow (y) locus of Drosophila melanogaster is associated with the insertion of a newly defined transposable element

To understand the molecular basis of the phenotype of gypsy-induced mutations, we have analyzed the structure of phenotypic revertants of the y2 allele, which is caused by the insertion of the gypsy element into the 5' region of the yellow (y) locus. Seven spontaneous revertants examined fall into two different classes. Three of these revertants arose by homologous recombination between the two gypsy long terminal repeats (LTRs), leaving behind a solo LTR. Four additional revertants contain an intact 3' LTR and half of the 5' LTR, but the central portion of gypsy has been replaced by a different 6.5-kilobase transposable element that contains a poly(A) tail. These results suggest that the mutagenic effect of the gypsy element is not due to its insertion into sequences necessary for transcription or to the distancing between the yellow promoter and remote regulatory sequences but is a consequence of idiosyncratic properties of the element itself.

Partial revertants of the transposable element-associated suppressible allele white-apricot in Drosophila melanogaster: structures and responsiveness to genetic modifiers

The eye color phenotype of white-apricot (wa), a mutant allele of the white locus caused by the insertion of the transposable element copia into a small intron, is suppressed by the extragenic suppressor suppressor-of-white-apricot (su(wa] and enhanced by the extragenic enhancers suppressor-of-forked su(f] and Enhancer-of-white-apricot (E(wa]. Derivatives of wa have been analyzed molecularly and genetically in order to correlate the structure of these derivatives with their response to modifiers. Derivatives in which the copia element is replaced precisely by a solo long terminal repeat (sLTR) were generated in vitro and returned to the germline by P-element mediated transformation; flies carrying this allele within a P transposon show a nearly wild-type phenotype and no response to either su(f) or su(wa). In addition, eleven partial phenotypic revertants of wa were analyzed. Of these, one appears to be a duplication of a large region which includes wa, three are new alleles of su(wa), two are sLTR derivatives whose properties confirm results obtained using transformation, and five are secondary insertions into the copia element within wa. One of these, waR84h, differs from wa by the insertion of the most 3' 83 nucleotides of the I factor. The five insertion derivatives show a variety of phenotypes and modes of interaction with su[f) and su(wa). The eye pigmentation of waR84h is affected by su(f) and E(wa), but not su(wa). These results demonstrate that copia (as opposed to the interruption of white sequences) is essential for the wa phenotype and its response to genetic modifiers, and that there are multiple mechanisms for the alteration of the wa phenotype by modifiers.

The spontaneous mutation rate in Drosophila simulans

The purpose of this investigation was to determine whether there exists a correlation in Drosophila between the spontaneous mutation rate and the amount of dispersed middle repetitive (mobile) DNA sequences. The amount of these sequences is 7 times less in Drosophila simulans as compared to Drosophila melanogaster. Therefore, if a correlation exists, the spontaneous mutation rate in Drosophila simulans should be 7 times lower than that in Drosophila melanogaster. We isolated an X-chromosome inversion after X-irradiation of wild-type Drosophila simulans males, that reduced crossing-over between white and forked, two X-linked visible markers, to less than 1%. This inversion was subsequently used to determine the sex-linked recessive lethal mutation rate in Drosophila simulans males of a laboratory strain marked with white. The frequency of these lethal mutations found is not different from that observed in Drosophila melanogaster males of laboratory strains.

Genetic instability in Drosophila melanogaster: cytogenetic analysis of MR-induced X-chromosome deficiencies

We present data that demonstrate that three MR elements isolated from wild populations of Drosophila melanogaster on two continents can cause large deletions of the X chromosome in males. The deleted chromosomes, termed mini-X chromosomes, are induced at a frequency of approximately 1:4000 in chromosomes that are initially free of P elements. In situ hybridizations using a cloned P sequence as a probe fail to reveal any sequences homologous to the nomadic P family at the deletion breakpoints. Genetic analysis of 12 such mini-X chromosomes also reveals that there are no "hotspots" of chromosome breakage and that there must have been a minimum of three distinct distal breakpoints and five different proximal breakpoints in the formation of these deleted chromosomes. In fact all 12 proximal and 12 distal breakpoints may well be unique. Our data show that MR elements generate essentially random breaks along the X chromosome. We emphasize that we find no involvement of P sequences in the chromosome breakage process, consonant with the notion that MR elements exert their influence on processes involved in mitotic crossing-over.