The fruit fly Drosophila melanogaster displays an ovarian diapause that is regulated by photoperiod.Newly eclosed female flies (Canton-S wild type) exposed to short days (<14 hr of light per day) at 12'C (or 100C) enter a fairly shallow reproductive diapause. Females exposed to long days (16 hr of light per day) at the same low temperature undergo ovarian maturation. The short day induced diapause continues for 6-7 weeks under a 10:14 light/dark cycle at 120C but is terminated rapidly after a transfer to higher temperature (18 or 250C) or to long days (18:6 light/dark cycle).Females from three strains homozygous for alleles of the period (per) locus, reportedly arrhythmic for behavioral circadian rhythms, and females that possessed two overlapping deletions of per were also capable of discriminating between long and short days, although, when compared with the wild-type flies, the critical day length was shifted to shorter values by -2 hr. It is concluded that the period locus is not causally involved in photoperiod time measurement.The majority of insects inhabiting the temperate zones develop and reproduce during the summer months but become dormant as winter approaches. Although ecological distinctions are becoming blurred, this dormancy may be a direct response to unfavorable conditions (i.e., cold torpor or quiescence), or it involves programmed responses to seasonal changes in day length (or photoperiod), which results in interruptions or alterations in endocrine regulation (i.e., diapause). Photoperiodic regulation of diapause has been documented for a large number of species representing -13 insect orders (1).A central problem in the study of photoperiodism is the nature of the "clock" used by organisms to discriminate long days from short days (or short nights from long nights) as the seasons change. The mechanism of this time measurement remains obscure, but a favored model suggests that night length is measured by a clock based on the system of circadian oscillations, which also regulate overt daily rhythms (2-4). In the 50 years since its formulation, this proposition has become known as "Hunning's hypothesis." D. melanogaster occupies an almost unique position in biological research because of its amenability for molecular and genetic analysis. Therefore, the nature of its overwintering strategy, whether diapause or quiescence, is also of considerable interest. To our knowledge, no published observations on this aspect of its biology have appeared, although it would be surprising if some attention had not been given to the problem, especially since the circadian system is known to underlie photoperiodic time meaurement [at least in D. auraria (13)], and the clock or period (per) locus is being subjected to intensive molecular and genetic analysis (14-17).This paper describes experiments with D. melanogaster in which newly eclosed adults were exposed to a range of photoperiods at temperatures somewhat lower than those normally used in routine laboratory maintenance and experimentation in an a...

The molting process in arthropods is regulated by steroid hormones acting via nuclear receptor proteins. The most common molting hormone is the ecdysteroid, 20‐hydroxyecdysone. The receptors of 20‐hydroxyecdysone have also been identified in many arthropod species, and the amino acid sequences determined. The functional molting hormone receptors consist of two members of the nuclear receptor superfamily, namely the ecdysone receptor and the ultraspiracle, although the ecdysone receptor may be functional, in some instances, without the ultraspiracle. Generally, the ecdysone receptor/ultraspiracle heterodimer binds to a number of ecdysone response elements, sequence motifs that reside in the promoter of various ecdysteroid‐responsive genes. In the ensuing transcriptional induction, the ecdysone receptor/ultraspiracle complex binds to 20‐hydroxyecdysone or to a cognate ligand that, in turn, leads to the release of a corepressor and the recruitment of coactivators. 3D structures of the ligand‐binding domains of the ecdysone receptor and the ultraspiracle have been solved for a few insect species. Ecdysone agonists bind to ecdysone receptors specifically, and ligand–ecdysone receptor binding is enhanced in the presence of the ultraspiracle in insects. The basic mode of ecdysteroid receptor action is highly conserved, but substantial functional differences exist among the receptors of individual species. Even though the transcriptional effects are apparently similar for ecdysteroids and nonsteroidal compounds such as diacylhydrazines, the binding shapes are different between them. The compounds having the strongest binding affinity to receptors ordinarily have strong molting hormone activity. The ability of the ecdysone receptor/ultraspiracle complex to manifest the effects of small lipophilic agonists has led to their use as gene switches for medical and agricultural applications.

The in vitro production of juvenile hormone (JH) was investigated by using isolated ring glands from third instar Drosophila melanogaster. A JH-like molecule is secreted that comigrates with a synthetic sample of methyl 6,7;10,11-bisepoxy-3,7,11-trimethyl-(2E)-dodecenoate (JHB3) during TLC, liquid chromatography, and GC analysis. Purified product from farnesoic acid-stimulated ring glands was analyzed by electron impact GC/MS and gave a mass spectrum identical to synthetic JHB3. Additional structure confirmation was obtained following conversion of product from unstimulated biosynthesis to a derivative that comigrated on liquid chromatography with the derivative prepared from synthetic JHB3. Physiological studies revealed that JHB3 is produced solely by the corpus allatum portion of the ring gland in vitro. Isolated ring glands from other cyclorrhaphous dipteran larvae also produce JHB3 almost exclusively in vitro. Corpora allata from mosquito larvae, however, produce only JH III, indicating that JHB3 production may be restricted to the higher Diptera. Topically applied synthetic JHB3 caused developmental responses in newly formed D. melanogaster white puparia similar to those obtained with JH III. The data suggest that JHB3 is a fly juvenile hormone.

The purpose of this study was to assess primary care physicians' awareness, experience, opinions and preparedness to answer patients' questions regarding direct-to-consumer (DTC) genetic testing. An anonymous survey was mailed to 2,402 family and internal medicine providers in North Carolina. Of the 382 respondents, 38.7% (n = 148) were aware of and 15% (n = 59) felt prepared to answer questions about DTC genetic tests. Respondents aged 50 or older were more likely to be aware of DTC genetic testing than those less than 40 years old (OR = 2.42). Male providers were more likely to feel prepared to answer questions than female providers (OR = 2.65). Among respondents who reportedly were aware, family practitioners were more likely than internists (OR = 3.30) to think DTC testing was clinically useful, and 18.9% had patients ask questions or bring in test results. The small percent of physicians who were aware of DTC genetic testing or felt prepared to answer questions about it suggests that education of providers will be necessary if testing becomes more widespread.

Abstract:This study describes the prevalence and characteristics of noise-induced hearing loss (NIHL) in student musicians (N = 329) aged 18-25 years. Students completed a questionnaire regarding exposures before a hearing assessment. NIHL was defined by the presence of a notch 15 dB in depth at 4000 or 6000 Hz relative to the best preceding threshold. Overall prevalence of NIHL was 45%, with 78% of notches occurring at 6000 Hz. The proportion of the total population with bilateral notching at any frequency was 11.5%, mostly occurring at 6000 Hz. There was a significant increase in the frequency of notching in students who reported more than two hours per day of personal practice. There were no significant associations for instrument group or other noise exposures. The data suggest that susceptibility to NIHL among students of music is not uniform and cannot be ascribed solely to the instrument played and other exposures. Students with bilateral losses tend to have deeper notches and may represent a group that has an inherent predisposition to NIHL. SumarioEste estudio describe la prevalencia y las características de la hipoacusia inducida por ruido (NIHL) en estudiantes de música (N = 329) con edades entre 18 y 25 años. Los estudiantes completaron un cuestionario sobre exposición a ruido antes de la evaluación auditiva. Se definió NIHL como la presencia de una muesca de 15dB en 4000 o 6000Hz con relación al mejor umbral precedente. La prevalencia general de NIHL fue de 44%, con 78% de las muescas en 6,000 Hz. La proporción de la población total con muescas bilaterales en cualquier frecuencia fue de 11.5%, en su mayoría a 6,000 Hz. Hubo un incremento significativo en la frecuencia de la muescas en los estudiantes que reportaban más de dos horas al día de práctica profesional. No hubo una asociación significativa con grupos de instrumentos u otra exposición a ruido. Los datos sugieren que la susceptibilidad a NIHL entre los estudiantes de música no es uniforme y no puede atribuirse solamente al instrumento tocado o a otras exposiciones. Los estudiantes con pérdida bilateral tienden a tener muescas más profundas y pueden representar un grupo que tenga una predisposición inherente a la NIHL.Keywords: Noise-induced hearing loss, Music-related hearing loss, Prevalence of hearing loss, Predisposition Article:Noise-induced hearing loss (NIHL) is the most prevalent sensorineural hearing loss after presbycusis. Prevalence of NIHL increases with continued exposure and advancing age. The prevention of NIHL will require a better understanding of its prevalence in the population and contributing exposure factors.NIHL can be caused by a single traumatic impulse sound but is more typically caused by repeated exposures to high intensity sound. According to NIOSH recommendations for the prevention of NIHL, high intensity sound exposure involves a time-intensity trade-off that begins with an allowable eight-hour exposure at 85 dBA, decreasing the time exposed by half for every three dB increase in intensity. Sound exposure measur...

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Steroid signaling underlies developmental processes in animals. Mutations that impair steroidogenesis in the fruit fly Drosophila melanogasterprovide tools to dissect steroid hormone action genetically. The widely used temperature-sensitive mutation ecdysoneless1(ecd1) disrupts production of the steroid hormone ecdysone, and causes developmental and reproductive defects. These defects cannot be satisfactorily interpreted without analysis of the ecdgene. Here, we show that ecd encodes an as yet functionally undescribed protein that is conserved throughout eukaryotes. The ecd1 conditional allele contains an amino acid substitution, whereas three non-conditional larval lethal mutations result in truncated Ecd proteins. Consistent with its role in steroid synthesis, Ecd is expressed in the ecdysone-producing larval ring gland. However, development of ecd-null early larval lethal mutants cannot be advanced by Ecd expression targeted to the ring gland or by hormone feeding. Cell-autonomous ecd function, suggested by these experiments, is evidenced by the inability of ecd– clones to survive within developing imaginal discs. Ecd is also expressed in the ovary, and is required in both the follicle cells and the germline for oocyte development. These defects, induced by the loss of ecd, provide the first direct evidence for a cell-autonomous function of this evolutionarily conserved protein.

The larval salivary gland of Drosophila melanogaster synthesizes and secretes glue glycoproteins that cement developing animals to a solid surface during metamorphosis. The steroid hormone 20-hydroxyecdysone (20E) is an essential signaling molecule that modulates most of the physiological functions of the larval gland. At the end of larval development, it is known that 20E—signaling through a nuclear receptor heterodimer consisting of EcR and USP—induces the early and late puffing cascade of the polytene chromosomes and causes the exocytosis of stored glue granules into the lumen of the gland. It has also been reported that an earlier pulse of hormone induces the temporally and spatially specific transcriptional activation of the glue genes; however, the receptor responsible for triggering this response has not been characterized. Here we show that the coordinated expression of the glue genes midway through the third instar is mediated by 20E acting to induce genes of the Broad Complex (BRC) through a receptor that is not an EcR/USP heterodimer. This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component.