[Eating disorders - what the gastroenterologist needs to know]

Eating disorders are potentially life-threatening disorders that go along with severe psychiatric and somatic comorbidities. It is expected that the number of patients will dramatically increase in the post COVID-19 pandemic era.Four main eating disorders are mentioned in the Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) and the International Classification of Diseases 11 (ICD-11): anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED) und avoidant restrictive food intake disorder (ARFID). Many traditional assumptions in eating disorders are currently challenged due to recent research results. The gastroenterologist is usually not the first point of contact for patients with eating disorders. However, he is crucial, especially in the management of gastroenterologic complications of eating disorders.Focus of the overview will be on relevant gastroenterologic aspects and less on the psychiatric treatment. Basics of the most common eating disorders will be repeated, opportunities in diagnosing an eating disorder and the most relevant gastroenterologic complications will be described. Obesity and its management, an entity that often goes along with an eating disorder, is not in the spotlight of the review.

Home treatment as an add-on to family-based treatment for adolescents with anorexia nervosa compared with standard family-based treatment and home-based stress reduction training: study protocol for a randomized clinical trial

BACKGROUND

Family-based treatment (FBT) is currently the most effective evidence-based treatment approach for adolescents with anorexia nervosa (AN). Home treatment (HT) as an add-on to FBT (FBT-HT) has been shown to be acceptable, feasible and effective. The described three-arm randomized clinical trial (RCT) is intended to investigate whether FBT-HT demonstrates higher efficacy compared to standard outpatient FBT with supplemental mindfulness-based stress reduction training (FBT-MBSR).

METHODS

This RCT compares FBT-HT to standard outpatient FBT and FBT-MBSR as a credible home-based control group in terms of efficacy and delivery. Adolescents with AN or atypical AN disorder (n = 90) and their parent(s)/caregiver(s) are to be randomly assigned to either FBT, FBT-HT or FBT-MBSR groups. Eating disorder diagnosis and symptomatology are to be assessed by eating disorder professionals using standardized questionnaires and diagnostic instruments (Eating Disorder Examination, Eating Disorder Inventory, Body Mass Index). In addition, parents and caregivers independently provide information on eating behavior, intrafamily communication, stress experience and weight. The therapeutic process of the three treatments is to be measured and assessed among both participants and care providers. The feasibility, acceptability and appropriateness can thus also be evaluated.

DISCUSSION

We hypothesize that FBT-HT will be an acceptable, appropriate and feasible intervention and, importantly, will outperform both established FBT and FBT-MBSR in improving adolescent weight and negative eating habits. Secondary outcome measures include the reduction in the stress experienced by caregivers, as well as the regulation of perceived expressed emotions within the family, while the intrafamily relationships are hypothesized to mediate/moderate the effectiveness of FBT. The proposed study has the potential to enhance the scientific and clinical understanding of the efficacy of FBT for AN, including whether the addition of HT to FBT versus another home-based adjunct intervention improves treatment outcomes. Furthermore, the study aligns with public health priorities to optimize the outcomes of evidence-based treatments and integrate the community setting. Trial registration This study is registered at ClinicalTrials.gov (NCT05418075).

The mental distress of our youth in the context of the COVID-19 pandemic

BACKGROUND

Epidemiological evidence from population-based surveys suggest that the psychological well-being of adolescents has been severely affected by the COVID-19 pandemic itself, as well as by the safety measures implemented. The rationale of the study was to investigate the influence of the pandemic on psychiatric emergency service use, psychiatric admissions rates, emotional well-being, suicidality and self-harm behaviour in help-seeking children and adolescents.

METHODS

Retrospective cohort study of electronic patient records before and during the COVID-19 pandemic from the emergency out-patient facility of the department of child and adolescent psychiatry and psychotherapy of the Psychiatric University Hospital Zürich. The frequency of all emergency service contacts from 1 January 2019 to 31 June 2021 were described and the frequency of records compared in half-year intervals. Emotional well-being, behavioural problems, suicidality and self-harm were estimated based on the mental state examination notes of electronic patient records from the 1 March to the 30 April for the years 2019, 2020 and 2021.

RESULTS

After an initial decline in emergency contacts at the beginning of the first lockdown, the use of the centralised emergency service increased during the subsequent months and has since stabilised at a significantly higher level than before the pandemic. Comparison of emergency contacts in the first half of 2019 with the first half of 2021 shows that the number of emergency phone contacts nearly doubled, emergency outpatient assessments increased by 40%, emergency bridging interventions increased by 230%, and inpatient admissions of minors to adult psychiatric inpatient units more than doubled because of lack of service capacity in child and adolescent psychiatry. The proportion of adolescents who reported suicidal ideation increased significantly by 15%, from 69% to 84%, and the proportion of adolescents who reported self-harm behaviour increased by 17%, from 31% to 48%.

CONCLUSION

We found a significant increase in psychiatric service use, as well as in reported serious mental health symptoms such as suicidality and self-harm behaviour in help-seeking children and adolescents in the course of the pandemic. The child and adolescent psychiatric healthcare system is overburdened and down-referral of adolescents in need of ongoing therapy is becoming increasingly difficult. We recommend prioritising preventive and therapeutic measures to support the mental health of our children and adolescents alongside the somatic management of the COVID-19 pandemic.

Home treatment as an add-on to family-based treatment in adolescents with anorexia nervosa: A pilot study

Objective

This pilot study examines the feasibility and the effectiveness of add‐on home treatment (HT) to family‐based treatment (FBT) in adolescents with anorexia nervosa (AN). The HT intervention is delivered by specialised nurses and aims at supporting patients and parents to re‐establish family meals in the home environment.

Method

We performed a 3‐month study in AN patients with a waiting‐list control design comparing 45 (43 females, 2 males) adolescents receiving FBT augmented with HT compared to 22 (21 females, 1 male) participants receiving FBT alone on the waiting list for additional HT. Eating disorder diagnosis, psychopathology and severity of clinical symptoms were assessed using the Eating Disorder Examination (EDE) interview, the Eating Disorders Inventory (EDI‐2) and clinical parameters (BMI, menstrual status, level of over‐exercising) at baseline and after 3 months.

Results

After 3 months of treatment, both treatment groups showed a significant early weight gain, a reduction in the rate of AN diagnoses assessed with the EDE interview and a reduction in EDI‐2 total scores. The combined HT/FBT group showed a significantly greater increase in BMI than the FBT‐only group. In the combined HT/FBT group, none of the patients had to be admitted to hospital, while three (13.6%) of the FBT‐only group had to be referred to inpatient treatment.

Discussion

Our results suggest that HT augmented FBT might be useful compared to FBT alone in terms of early weight gain and might reduce the risk of hospital admission in adolescent AN.

Home treatment as an add‐on to family‐based treatment seems to be a well‐accepted and very effective method for the treatment of eating disorders in adolescence.

Combining family‐based treatment with home treatment thus seems to even enhance the therapy effectiveness of FBT in terms of initial weight gain as well as psychopathology

Feasibility and acceptability of home treatment as an add-on to family based therapy for adolescents with anorexia nervosa. A case series

OBJECTIVE

This study examines the feasibility, acceptability, and preliminary effect sizes on outcome measures of home treatment (HT) as an add-on to family-based therapy (FBT) in adolescents with anorexia nervosa (AN). The HT intervention is delivered by specialized nurses and aims at supporting patients and parents to re-establish family meals in the home environment.

METHOD

Forty-five (43 female, 2 male) adolescents meeting ICD 10 criteria for anorexia nervosa or atypical anorexia nervosa received FBT augmented with HT over 12 weeks. Eating disorder (ED) diagnosis, psychopathology and severity of clinical symptoms were assessed using the Eating Disorder Examination (EDE) interview, the Eating Disorders Inventory (EDI-2) at baseline (BL) and after 3-months RESULTS: All participants and parents were retained and found HT acceptable. At the end of Treatment (EOT) participants showed a significant early weight gain, a reduction in the AN psychopathology assessed with the EDE interview and a reduction in EDI-2 total scores. None of the patients had to be admitted to hospital. Treatment satisfaction was high in both patients and parents.

DISCUSSION

Findings provide preliminary evidence that HT is feasible, acceptable and produces clinically significant improvements in targeted outcome.

Home treatment for adolescents with eating disorders as an add-on to family based therapy

Introduction

Family-based therapy (FBT) has been proven effective in treating eating disorders among children and adolescents. However, many families have difficulties implementing the measures recommended in outpatient therapy.

Objectives

This study examines the effectiveness of add-on home treatment (HT) to family based therapy (FBT) in adolescents with anorexia nervosa (AN). The HT intervention is delivered by specialized nurses and aims at supporting patients and parents to re-establish family meals in the home environment.

Methods

We performed an case-control study in AN patients comparing 44 (42 female, 2 male) adolescents receiving FBT augmented with HT compared to 22 (22 female, 1 male) participants receiving FBT alone. Eating disorder diagnosis, psychopathology and severity of clinical symptoms were assessed using (EDE, EDI-2) and clinical parameters (BMI, menstrual status, level of over-exercising) at baseline and after 3-months.

Results

After 3 months both treatment groups showed a significant early weight gain, a reduction in the rate of AN diagnoses assessed with the EDE interview and a reduction in EDI-2 total scores. The combined HT/FBT group showed a significantly greater increase in BMI than the FBT-only group. In the combined HT/FBT group none of the patients had to be admitted to hospital while 13.6% of the FBT-only group had to be referred to inpatient treatment. Treatment satisfaction in the combined HT/FBT group was high in both patients and parents.

Conclusions

Our results suggest that HT augmented FBT is superior compared to FBT alone in terms of early weight gain and might reduce the risk of hospital admission in adolescent AN.

Disclosure

No significant relationships.

[Systemic Treatment of Eating Disorders]

Systemic Treatment of Eating Disorders Abstract. Eating disorders (EDs) are deleterious illnesses that are associated with significant psychiatric and medical morbidity and mortality, considerable distress and impairment, marked caregiver burden, and high treatment costs. Because EDs commonly onset in adolescence and young adulthood, and with consistent evidence that early intervention results in the most promising treatment outcomes, an increasing amount of research has been devoted to the treatment of adolescent EDs. Although still less researched in adult presentations of EDs, the historical record of research on adolescent ED treatment over the last half-century principally supports family therapy. Current published clinical guidelines recommend an ED-specific family therapy as the first-line treatment of adolescents with anorexia nervosa (AN) and as a recommended treatment of adolescents with bulimia nervosa (BN). The number of treatment trials for adolescent AN has slowly grown over the last few decades and, more recently, family interventions include protocols extending to new populations and diagnoses, including BN. This narrative review summarizes existing family-based approaches to the treatment of adolescent EDs, integrating recent research findings. This article also includes discussion of methods, both current and proposed, that expand and adapt current family-based approaches in efforts to improve the breadth and scope of ED treatment in adolescence and young adulthood.

Motivation to change, coping, and self-esteem in adolescent anorexia nervosa: a validation study of the Anorexia Nervosa Stages of Change Questionnaire (ANSOCQ)

BACKGROUND

Understanding motivation to change is a key issue in both the assessment and the treatment of eating disorders. Therefore, sound instruments assessing this construct are of great help to clinicians. Accordingly, the present study analysed the psychometric properties of the Anorexia Nervosa Stages of Change Questionnaire (ANSOCQ), including its relation to coping style and self-esteem.

METHODS

N = 92 adolescents referred to an eating disorders outpatient clinic meeting criteria for anorexia nervosa gave written informed consent to participate in this study and completed the ANSOCQ, the Eating Disorder Inventory, the Eating Attitudes Test, the Body Image Questionnaire, two questionnaires measuring Self-Related Cognitions and the Coping Across Situations Questionnaire. After a treatment period of nine months, clinical anorexia nervosa diagnosis and the body mass index were re-assessed. In addition to exploratory factor analysis, correlational analysis was used to test for the convergent validity of the ANSOCQ and logistic regression analysis was used to test its predictive validity.

RESULTS

The ANSOCQ had good psychometric properties. Factor analysis yielded two meaningful factors labelled as 'weight gain and control' and 'attitudes and feelings'. Internal consistencies of the two factors amounted to Cronbach's alpha = .87 and .76, respectively. Significant correlations with other scales measuring eating disorder psychopathology were indicative of meaningful construct validity. Higher motivation to change was related to higher self-esteem and a more active coping style. Higher (positive) ANSOCQ total scores predicted remission of anorexia nervosa after nine months of treatment. A higher score on 'attitudes and feelings' was a protective factor against drop-out from intervention.

CONCLUSIONS

The ANSOCQ is a clinically useful instrument for measuring motivation to change in adolescents with AN. Two factorial dimensions explain most of the variation. Self-esteem and coping style are relevant additional constructs for the understanding of the motivation to change in anorexia nervosa.

TRIAL REGISTRATION

NCT02828956. Retrospectively registered July 2016.

[Prevention and interventions for suicidal youth considerations for health professionionals in Switzerland]

Adolescence is associated with a dramatic surge in suicide rate. While worldwide age-adjusted suicides rate per 100’000 in under 14-year olds are relatively low around 0.6, a dramatic increase to 7.4 can be observed in 15 – 19 year olds with suicide being one of the three leading causes of mortality in most countries in this age group. From 2000 to 2013 the Swiss annual average of completed suicides in 15 – 19 year olds was 33.1 (minimum 24; maximum 47). This corresponds to an average age-specific death rate of 7.6, which is slightly above the global mean. Suicide prevention and treatment of suicidality in adolescents is a complex underpinning. Subjectively experienced feelings of insufficiency, hopelessness and the feeling of worthlessness combined with concrete suicidal ideations and the capacity to act out are important indicators for assessing suicidal risk. Suicide attempts as the strongest risk factor for suicide should always be taken seriously, even if they occur in the context of situational crisis. Narcissistic personality traits or increased impulsivity are further indicators of risk. The early detection and effective treatment of mental disorders such as depression, anxiety disorders, bipolar-affective disorders or psychotic disorders provide a great opportunity to reduce the frequency of suicide attempts and suicide. Particular caution is required when co-morbid addictions are present. The maintenance or establishment of sustainable relationships with significant others is considered a key protecting factor. Increasing withdrawal from significant others is an important warning sign and needs urgent involvement of experts. In acute suicidality, the admission to a psychiatric hospital must be considered, if necessary against the will of affected adolescent and their relatives. Personality-related recurrent suicidal behavior requires specific treatment approaches taking into account the prevention of iatrogenic worsening of suicidal patterns.

A GAL4-HP1 fusion protein targeted near heterochromatin promotes gene silencing

We have constructed a new reporter transgene, Winkelried, equipped with a synthetic binding site for the yeast GAL4 transcriptional activator. The binding site is inserted between the white and lacZ reporter genes, and is flanked by FRT sequences. These elements allow excision of the GAL4 binding site by crossing the transgenic line with an FLP recombinase producing strain. We have generated by X-ray irradiation two independent chromosomal rearrangements, Heidi and Tell, relocating Winkelried next to pericentromeric heterochromatin. These rearrangements induce variegation of both white and lacZ. Variegation of Winkelried in the rearranged transgenic lines responds to the loss and excess of doses of the dominant suppressors of position-effect variegation (PEV) Su(var)3-7 and Su(var)2-5. Winkelried therefore constitutes a unique tool to test the effect on variegation in cis of any factor fused to the GAL4 DNA binding domain. Indeed, a chimeric protein, made of the DNA binding site of GAL4 and of HP1, the modifier of PEV encoded by Su(var)2-5, is shown to enhance variegation of Heidi and Tell. Excision of the binding sites for GAL4 in the variegating rearrangements Heidi and Tell abolishes the modifier effect of the GAL4-HP1 chimera. Therefore, in the Heidi and Tell rearrangements, enhancement of position-effect variegation depends strictly both on the concentration of GAL4-HP1 and on the presence of its binding site in the vicinity of the reporter genes.

Suppression of distinct ovo phenotypes in the Drosophila female germline by maleless- and Sex-lethal

Mutations in ovo result in several different phenotypes, which we show are due to the regulation of distinct developmental pathways. Two X (female) germ cells require ovo+ activity for viability, but 1X (male) germ cells do not. In our study, we observed suppression of the ovo germline-lethality phenotype in loss-of-function maleless (mle) females indicating that ovo+ and mle+ have opposing effects in female germ cells; or that they are hierarchically related. Gain-of-function Sex-lethal (Sxl) alleles and male specific lethal-2 alleles did not suppress the ovo germline death phenotype. Many of the surviving germ cells in females mutant for both ovo and mle showed ovarian tumors. In contrast to the germline viability phenotype, we did observe suppression of the tumor phenotype in females heterozygous for gain-of-function alleles of Sxl. Further, females mutant for some hypomorphic ovo alleles were rendered fertile by Sxl gain-of-function alleles. Thus, ovo+ is required for at least two distinct functions, one involving mle+, and one mediated by Sxl+ gene products. The existence of ovo+ functions independent of mle+ and Sxl+ is likely.

OVO transcription factors function antagonistically in the Drosophila female germline

OVO controls germline and epidermis differentiation in flies and mice. In the Drosophila germline, alternative OVO-B and OVO-A isoforms have a common DNA-binding domain, but different N-termini. We show that these isoforms are transcription factors with opposite regulatory activities. Using yeast one-hybrid assays, we identified a strong activation domain within a common region and a counteracting repression domain within the OVO-A-specific region. In flies, OVO-B positively regulated the ovarian tumor promoter, while OVO-A was a negative regulator of the ovarian tumor and ovo promoters. OVO-B isoforms supplied ovo(+) function in the female germline and epidermis, while OVO-A isoforms had dominant-negative activity in both tissues. Moreover, elevated expression of OVO-A resulted in maternal-effect lethality while the absence of OVO-A resulted in maternal-effect sterility. Our data indicate that tight regulation of antagonistic OVO-B and OVO-A isoforms is critical for germline formation and differentiation.

The Drosophila gene stand still encodes a germline chromatin-associated protein that controls the transcription of the ovarian tumor gene

The Drosophila gene stand still (stil) encodes a novel protein required for survival, sexual identity and differentiation of female germ cells. Using specific antibodies, we show that the Stil protein accumulates in the nucleus of all female germ cells throughout development, and is transiently expressed during early stages of male germline differentiation. Changes of Stil subnuclear localization during oogenesis suggest an association with chromatin. Several mutant alleles, which are point mutations in the Stil N-terminal domain, encode proteins that no longer co-localized with chromatin. We find that Stil binds to many sites on polytene chromosomes with strong preference for decondensed chromatin. This localization is very similar to that of RNA polymerase II. We show that Stil is required for high levels of transcription of the ovarian tumor gene in germ cells. Expression of ovarian tumor in somatic cells can be induced by ectopic expression of Stil. Finally, we find that transient ubiquitous somatic expression of Stil results in lethality of the fly at all stages of development.

The Drosophila Sin3 gene encodes a widely distributed transcription factor essential for embryonic viability

Expression of many mammalian genes is activated by the binding of heterodimers of the Myc and Max proteins to specific DNA sequences called the E-boxes. Transcription of the same genes is repressed upon binding to the same sequences of complexes composed of Max, Mad/Mxi1, the co-repressors Sin3 and N-CoR, and the histone deacetylase Rpd3. Max-Mad/Mxi1 heterodimers, which bind to E-boxes in absence of co-repressors, do not inhibit gene expression simply by competition with Myc-Max heterodimers, but require Sin3 and Rpd3 for efficient repression of transcription. We have cloned a Drosophila homolog of Sin3 (dSin3) and found it to be ubiquitously expressed during embryonic development. Yeast, mouse and Drosophila proteins share six blocks of strong homologies, including four potential paired amphipathic helix domains. In addition, the domain of binding to the histone deacetylase Rpd3 is strongly conserved. Null mutations cause recessive embryonic lethality.

Drosophila OVO zinc-finger protein regulates ovo and ovarian tumor target promoters

The ovo+ and ovarian tumor+ genes function in the germline sex determination pathway in Drosophila, but the hierarchical relationship between them is unknown. We found that increased ovo+ copy number resulted in increased ovarian tumor expression in the female germline and increased ovo expression in the male germline. The ovo locus encodes C2H2 zinc-finger proteins. Bacterially expressed OVO zinc-finger domain bound to multiple sites at or near the ovo and ovarian tumor promoters strongly suggesting that OVO is directly autoregulatory and that ovarian tumor is a direct downstream target of ovo in the germline sex determination hierarchy. Both positive and negative regulation by OVO proteins appears likely, depending on promoter context and on the sex of the fly. Our observation that two strong OVO-binding sites are at the initiator of the TATA-less ovo-B and ovarian tumor promoters raises the possibility that OVO proteins influence the nucleation of transcriptional pre-initiation complexes.

Multiple developmental requirements of noisette, the Drosophila homolog of the U2 snRNP-associated polypeptide SP3a60

We report the cloning of the noisette gene (noi), which encodes the Drosophila melanogaster ortholog of a U2 snRNP-associated splicing factor, SF3a60 (SAP61) in humans and PRP9p in Saccharomyces cerevisiae. Antibodies raised against human SF3a60 recognized NOI in flies, showing a nuclear localization in all the stages examined, including the embryo, the dividing cells of imaginal discs, and the larval polyploid nuclei. NOI is expressed in somatic and germinal cells of both male and female gonads. By mobilization of P transposons, we have generated a large number of noi mutations. Complete loss of function resulted in lethality at the end of embryogenesis, without obvious morphological defects. Hypomorphic alleles revealed multiple roles of noi for the survival and differentiation of male germ cells, the differentiation of female germ cells, and the development of several adult structures.

stand still, a Drosophila gene involved in the female germline for proper survival, sex determination and differentiation

We identified a new gene, stand still (stil), required in the female germline for proper survival, sex determination and differentiation. Three strong loss-of-function alleles were isolated. The strongest phenotype exhibited by ovaries dissected from adult females is the complete absence of germ cells. In other ovaries, the few surviving germ cells frequently show a morphology typical of primary spermatocytes. stil is not required either for fly viability or for male germline development. The gene was cloned and found to encode a novel protein. stil is strongly expressed in the female germ cells. Using P[stil+] transgenes, we show that stil and a closely localized gene are involved in the modification of the ovarian phenotypes of the dominant alleles of ovo caused by heterozygosity of region 49 A-D. The similarity of the mutant phenotypes of stil to that of otu and ovo suggests that the three genes function in a common or in parallel pathways necessary in the female germline for its survival, sex determination and differentiation.

The histone deacetylase RPD3 counteracts genomic silencing in Drosophila and yeast

Both position-effect variegation (PEV) in Drosophila and telomeric position-effect in yeast (TPE) result from the mosaic inactivation of genes relocated next to a block of centromeric heterochromatin or next to telomeres. In many aspects, these phenomena are analogous to other epigenetic silencing mechanisms, such as the control of homeotic gene clusters, X-chromosome inactivation and imprinting in mammals, and mating-type control in yeast. Dominant mutations that suppress or enhance PEV are thought to encode either chromatin proteins or factors that directly affect chromatin structure. We have identified an insertional mutation in Drosophila that enhances PEV and reduces transcription of the gene in the eye-antenna imaginal disc. The gene corresponds to that encoding the transcriptional regulator RPD3 in yeast, and to a human histone deacetylase. In yeast, RRD3-deletion strains show enhanced TPE, suggesting a conserved role of the histone deacetylase RPD3 in counteracting genomic silencing. This function of RPD3, which is in contrast to the general correlation between histone acetylation and increased transcription, might be due to a specialized chromatin structure at silenced loci.

The dose of a putative ubiquitin-specific protease affects position-effect variegation in Drosophila melanogaster

A dominant insertional P-element mutation enhances position-effect variegation in Drosophila melanogaster. The mutation is homozygous, viable, and fertile and maps at 64E on the third chromosome. The corresponding gene was cloned by transposon tagging. Insertion of the transposon upstream of the open reading frame correlates with a strong reduction of transcript level. A transgene was constructed with the cDNA and found to have the effect opposite from that of the mutation, namely, to suppress variegation. Sequencing of the cDNA reveals a large open reading frame encoding a putative ubiquitin-specific protease (Ubp). Ubiquitin marks various proteins, frequently for proteasome-dependent degradation. Ubps can cleave the ubiquitin part from these proteins. We discuss the link established here between a deubiquitinating enzyme and epigenetic silencing processes.

Position-effect variegation in Drosophila depends on dose of the gene encoding the E2F transcriptional activator and cell cycle regulator

A dominant mutation due to the insertion of a P-element at 93E on the third chromosome of Drosophila melanogaster enhances position-effect variegation. The corresponding gene was cloned by transposon tagging and the sequence of the transcript revealed that it corresponds to the gene encoding the transcriptional activator and cell cycle regulator dE2F. The transposon-tagged allele is homozygous viable, and the insertion of the transposon in an intron correlates with a strong reduction in the amount of transcript. A homozygous lethal null allele was found to behave as a strong enhancer when heterozygous. Overexpression of the gene in transgenic flies has the opposite effect of suppressing variegation. A link is established here, and discussed, between the dose of a transcriptional activator, which controls the cell cycle, and epigenetic silencing of chromosomal domains in Drosophila.

Identification of regions interacting with ovoD mutations: potential new genes involved in germline sex determination or differentiation in Drosophila melanogaster

Only a few Drosophila melanogaster germline sex determination genes are known, and there have been no systematic screens to identify new genes involved in this important biological process. The ovarian phenotypes produced by females mutant for dominant alleles of the ovo gene are modified in flies with altered doses of other loci involved in germline sex determination in Drosophila (Sex-lethal+, sans fille+ and ovarian tumor+). This observation constitutes the basis for a screen to identify additional genes required for proper establishment of germline sexual identity. We tested 300 deletions, which together cover approximately 58% of the euchromatic portion of the genome, for genetic interactions with ovoD. Hemizygosity for more than a dozen small regions show interactions that either partially suppress or enhance the ovarian phenotypes of females mutant for one or more of the three dominant ovo mutations. These regions probably contain genes whose products act in developmental hierarchies that include ovo+ protein.

Function of Drosophila ovo+ in germ-line sex determination depends on X-chromosome number

Germ-line sex determination in Drosophila melanogaster requires an assessment of the number of X chromosomes as measured against autosomal standards (XX = female, X = male) and signaling from the soma. Both of these sex determination cues are required for female-specific Sex-lethal+ function in germ cells. The ovo+ locus encodes zinc finger protein(s) required for female-specific splicing of Sex-lethal+ pre-mRNA, making ovo+ a candidate function acting between the two principal cues and Sex-lethal+. We have made ovo reporter genes and find that they show high activity in the germ line of females and low activity in the germ line of males. XY flies transformed into somatic females do not show high levels of reporter activity, while XX flies transformed into somatic males do. This shows that high level ovo+ expression depends on the number of X chromosomes, not the somatic sexual signals. The requirement for ovo+ function is restricted to XX flies. Mutations in ovo have no effect on XY males, X0 males or XY females, but have pronounced effects on germ cell viability in XX females, XX females with sex transformed germ lines, and XX males indicating that ovo+ gene products are required for events occurring only in flies with two X chromosomes.

Evidence for sex transformation of germline cells in ovarian tumor mutants of Drosophila

Mutations at a few genetic loci in Drosophila cause ovarian tumors with hundreds of poorly differentiated germ cells. We examined several of these mutants to test the hypothesis that such ovarian tumors contain sex-transformed cells. By testing for expression of male germline traits, we determined that partial germline sex transformation occurs in otu, snf, Sxlfs, and bam ovarian tumors. Thus these genes are likely to be required for proper establishment of germline sexual identity.

The role of the ovarian tumor locus in Drosophila melanogaster germ line sex determination

The locus ovarian tumor (otu) is involved in several aspects of oogenesis in Drosophila melanogaster. The possible role of otu in the determination of the sexual identity of germ cells has not been extensively explored. Some otu alleles produce a phenotype known as ovarian tumors: ovarioles are filled with numerous poorly differentiated germ cells. We show that these mutant germ cells have a morphology similar to primary spermatocytes and that they express male germ line-specific reporter genes. This indicates that they are engaged along the male pathway of germ line differentiation. Consistent with this conclusion, we found that the splicing of Sex-lethal (Sxl) pre-mRNAs occurs in the male-specific mode in otu-transformed germ cells. The position of the otu locus in the regulatory cascade of germ line sex determination has been studied by using mutations that constitutively express the feminizing activity of the Sxl gene. The sexual transformation of the germ cells observed with several combinations of otu alleles can be reversed by constitutive expression of Sxl. This shows that otu acts upstream of Sxl in the process of germ line sex determination. Other phenotypes of otu mutations were not rescued by constitutive expression of Sxl, suggesting that several functions of otu are likely to be independent of sex determination. Finally, we show that the gene dosage of otu modifies the phenotype of ovaries heterozygous for the dominant alleles of ovo, another gene involved in germ line sex determination. One dose of otu+ enhances the ovoD ovarian phenotypes, while three doses partially suppress these phenotypes. Synergistic interaction between ovoD1 and otu alleles leads to the occasional transformation of chromosomally female germ cells into early spermatocytes. These interactions are similar to those observed between ovoD and one allele of the sans fille (snf) locus. Altogether, our results imply that the otu locus acts, along with ovo, snf, and Sxl, in a pathway (or parallel pathways) required for proper sex determination of the female germ line.

Analysis of the resistance to heat and hydrogen peroxide stresses in COS cells transiently expressing wild type or deletion mutants of the Drosophila 27-kDa heat-shock protein

The Drosophila melanogaster small heat-shock protein, hsp27 (Dhsp27) belongs to a family of polypeptides which shares a sequence related to alpha-crystallin and which protect cell against heat shock. Dhsp27 accumulates following heat shock and, in absence of stress, in the central nervous system, imaginal discs and the gonads of the developing fly. Two internal and adjacent deletion mutants in the conserved alpha-crystallin domain of Dhsp27 were constructed. Expression vectors containing either the coding sequence of Dhsp27 or that of the two deletion mutants linked to the Simian-Virus-40 late promoter were used to transfect monkey COS cells. The transient expression of Dhsp27 was found to decrease the sensitivity of COS cells to heat and hydrogen-peroxide stresses as judged by Trypan-blue staining and indirect immunofluorescence analysis. Using this rapid test, we observed that a deletion of 62 amino acids, which lies at the 5' end of the conserved alpha-crystallin domain and covers the first 41 amino acids of this region had only a weak effect on the protective activity of Dhsp27. This suggests that the N-terminal half of the conserved alpha-crystallin domain may not be essential for the protective activity of the small hsp. In contrast, Dhsp27 was no more active when the last 42 amino acids of the alpha-crystallin domain were deleted. Biochemical fractionation and indirect immunofluorescence analysis indicated that the protective function of Dhsp27 was localized at the level of the nucleus.

Transcriptional regulation in Drosophila during heat shock: a nuclear run-on analysis

We used a nuclear run-on assay as a novel approach to study the changes in transcriptional activity that take place in Drosophila melanogaster during heat shock. In response to a rapid temperature upshift, total transcriptional activity in cultured KC161 cells decreased proportionally to the severity of the shock. After extended stress at 37 degrees C (15 min or more), transcription was severely reduced, and at 39 degrees C most transcription was instantaneously arrested. However, strikingly different responses were observed for individual genes. Transcription of histone H1 genes was severely inhibited even under mild heat shock conditions. Transcription of the actin 5C gene decreased progressively with increasing temperature, while transcription of the core histone genes or of the heat shock cognate genes was repressed only under severe heat shock conditions. Transcriptional activation of the D. melanogaster heat shock genes was also investigated. In unshocked cells, hsp84 was moderately transcribed, while transcriptional activity at the other protein-coding heat shock genes was undetectable (less than 0.2 polymerases per gene). Engaged but paused RNA polymerase molecules were found at the hsp70 and hsp26 genes, but not at the other heat shock genes. The rates of transcription increased with increasing temperature with a peak of expression at around 35 degrees C. At 37 degrees C, induction was less efficient, and no induction was achieved after a rapid shift to 39 degrees C. Increased transcription of the heat shock genes was observed within 1-2 min of heat shock, and maximal rates were reached within 2-5 min. Despite very similar profiles of response, different heat shock genes were transcribed at strikingly different rates, which varied over a 20-fold range. The noncoding heat shock locus 93D was transcribed at a very high rate under non-heat shock conditions, and showed a transcriptional response to elevated temperatures different from that of protein-coding heat shock genes. An estimation of the absolute rates of transcription at different temperatures was obtained.

Heat shock response in Drosophila

Major alterations in genetic activity have been observed in every organism after exposure to abnormally high temperatures. This phenomenon, called the heat shock response, was discovered in the fruit fly Drosophila. Studies with this organism led to the discovery of the heat shock proteins, whose genes were among the first eukaryotic genes to be cloned. Several of the most important aspects of the regulation of the heat shock response and of the functions of the heat shock proteins have been unraveled in Drosophila.

Tissue-specific expression of the heat shock protein HSP27 during Drosophila melanogaster development

The alpha-crystallin-related heat shock (stress) protein hsp27 is expressed in absence of heat shock during Drosophila melanogaster development. Here, we describe the tissue distribution of this protein using an immunoaffinity-purified antibody. In embryos, hsp27 translated from maternal RNA is uniformly distributed, except in the yolk. During the first, second, and early third larval stages, hsp27 expression is restricted to the brain and the gonads. These tissues are characterized by a high level of proliferating cells. In late third instar larvae and early pupae, in addition to the central nervous system and the gonads, all the imaginal discs synthesize hsp27. The disc expression seems restricted to the beginning of their differentiation since it disappears during the second half of the pupal stage: no more hsp27 is observed in the disc-derived adult organs. In adults, hsp27 is still present in some regions of the central nervous system, and is also expressed in the male and female germ lines where it accumulates in mature sperm and oocytes. The transcript and the protein accumulate in oocytes since the onset of vitellogenesis with a uniform distribution similar to that found in embryos. The adult germ lines transcribe hsp27 gene while no transcript is detected in the late pupal and adult brain. These results suggest multiple roles of hsp27 during Drosophila development which may be related to both the proliferative and differentiated states of the tissues.

Germ-line sex determination in Drosophila melanogaster

In Drosophila melanogaster, the mechanism of sex determination is substantially different in the germ line and in the soma. In the germ line, the process is not completely cell-autonomous, but requires some signals from the soma. Only some of the genes involved in somatic sex determination are also needed for germ cell development. Recent genetic studies have identified loci required for germ-line sex determination.

Genetic evidence that the ovo locus is involved in Drosophila germ line sex determination

Zygotically contributed ovo gene product is required for the survival of female germ cells in Drosophila melanogaster. Trans-allelic combinations of weak and dominant ovo mutations (ovoD) result in viable germ cells that appear to be partially transformed from female to male sexual identity. The ovoD2 mutation is partially suppressed by many Sex-lethal alleles that affect the soma, while those that affect only the germ line fail to interact with ovoD2. One of two loss-of-function ovo alleles is suppressed by a loss-of-function Sex-lethal allele. Because ovo mutations are germ line dependent, it is likely that ovo is suppressed by way of communication between the somatic and germ lines. A loss-of-function allele of ovo is epistatic to germ line dependent mutations in Sex-lethal. The germ line dependent sex determination mutation, sans fille, and ovoD mutations show a dominant synergistic interaction resulting in partial transformation of germ line sexual identity. The ovo locus appears to be involved in germ line sex determination and is linked in some manner to sex determination in the soma.

Expression of the small heat shock genes during Drosophila development: comparison of the accumulation of hsp23 and hsp27 mRNAs and polypeptides

Seven heat shock genes are clustered within 15 kilobases of DNA at the Drosophila melanogaster chromosomal site 67B. They show a complex pattern of expression in the absence of external stress during normal development of this organism. In this paper, we quantitatively compare the abundance of the messenger RNAs for these seven genes at all major stages of Drosophila development and then focus on hsp23 and hsp27 for which available antibodies allow the comparison between the accumulation of the mRNAs and that of their corresponding polypeptides. Transcripts for both genes are maximally abundant in white prepupae. We observe that the amount of hsp23 message decreases more rapidly than that of hsp27 mRNA throughout the pupal period. The maximal abundance of the proteins occurs at the middle of the pupal stage, when their corresponding RNAs have almost completely disappeared. The peaks of expression of the proteins are also broader than those of their transcripts, indicating that the half-lives of the polypeptides are longer. These observations suggest that complex mechanisms regulate the expression of the small heat shock genes during Drosophila development.

An unusual split Drosophila heat shock gene expressed during embryogenesis, pupation and in testis

Gene 2, one of the seven heat shock genes from locus 67B of Drosophila melanogaster, is transcribed into two polyadenylated RNAs having different developmental profiles of expression. The smaller transcript, of about 560 nucleotides, is expressed from mid-embryogenesis to the first two larval stages and again at the beginning of pupation. The larger transcript, 780 nucleotides, contains an additional 5' exon, accounting for its larger size. It is detected in pupae and adults, is male-specific and is localized in the testes. Heat shock does not affect the abundance of these two transcripts but induces the accumulation of a third RNA species of about 2000 nucleotides. This heat-shock RNA has the same cap site as the embryonic transcript, while its 3' portion entirely includes the neighbouring hsp22 gene. It appears, therefore, that in this case, heat shock alters the normal transcription termination process. By contrast to most heat shock genes, gene 2 contains several micro introns. One long open reading frame common to the three transcripts encodes a putative polypeptide of 111 amino acid residues. No homology was found with the other small heat shock genes of locus 67B.

Characterization of HSP27 and three immunologically related polypeptides during Drosophila development

The low-molecular-weight heat-shock protein HSP27 is made in the absence of heat shock during Drosophila melanogaster development. An analysis of the accumulation of HSP27 during specific stages of development is presented using an antiserum recognizing this protein. Whereas HSP27 is abundant during embryogenesis, the level of this protein begins to decrease in the 20-h old embryo and is no longer detectable in second instar larvae. A high level of HSP27 is again observed in third instar larvae and reaches a maximal level in late pupae. While still abundant in young adult flies of both sexes, a greater amount of HSP27 is found in females with the protein being highly concentrated within the ovaries. Following lysis of whole pupae, about 60% of HSP27 is found in the soluble lysate fraction in a form which sediments between 5 and 20 S. Anti-HSP27 serum also recognizes three other developmentally regulated polypeptides with apparent MW of 33, 85 and 120 kDa. The 33 kDa protein accumulates in pupae while those of 85 and 120 kDa are more abundant in third instar larvae. Unlike HSP27, these proteins are not detected in embryos or ovaries. Immunoblot analysis of V8 proteolytic fragments suggests that HSP 27 and 33 kDa are related polypeptides. Exposure of the developing insect to heat-shock treatment results in increased level of HSP27. In larvae, a small amount of the 33 kDa protein accumulates following heat shock, while in pupae and adult flies a decrease in the concentration of this protein is observed after heat shock. Finally, different cellular localizations and distributions within the pupal body have been found for these developmentally regulated polypeptides.

A Drosophila heat shock gene from locus 67B is expressed during embryogenesis and pupation

We present a detailed characterization of the structure and expression of gene 3 from the 67B locus of Drosophila melanogaster. Northern blot analysis reveals a major poly(A)+ transcript during two stages of development: mid-embryogenesis and beginning of pupation. After heat shock, the abundance of this mRNA is increased and small amounts of larger RNAs representing alternate terminations of the major transcript appear. In Schneider 3 tissue culture cells, beside the major transcript, we also observe small amounts of the larger RNAs after a heat shock. The sequencing of cDNA and genomic clones shows an intronless transcription unit with one long open reading frame. The deduced polypeptide has 169 amino acids. It shares a strong homology with the four small heat shock proteins in the region also conserved in the mammalian alpha-crystalline B2 chain. In gene 3, this homology is restricted to the first 50 residues along the conserved 83 amino acid stretch. Two heat shock regulatory elements are localized upstream from the gene.

Several hundred base pairs upstream of Drosophila hsp23 and 26 genes are required for their heat induction in transformed flies

We have used the P-element-mediated transformation of Drosophila germ line to study the 5' DNA sequences involved in the thermal inducibility of the genes for heat shock proteins hsp23 and 26. The results are strikingly different from those previously obtained in heterologous systems. For hsp23, each successive shortening of the promoter region from 618 to 402, 321 and 263 bp clearly decreased the expression. A construct with only 149 bp was not inducible at all. For hsp26, all the regulatory elements appear to be clustered in the first 350 bp upstream from the cap site. Clones with 171 bp showed a 4- to 10-fold decrease in induction depending on the transformed line, and those with only 52 bp were not expressed. The results suggest that at least three Pelham consensus sequences are required for the full expression of these two genes. The direct involvement of one of these consensus sequences has been assessed: a 6-bp deletion within the proximal element of the hsp26 gene strongly reduced its inducibility. Our results also indicate that X-linked hsp genes exhibit either partial dosage compensation or none at all.

Early changes in lymphocyte traffic between distant lymph nodes following regional antigenic stimulation

Regional labeling of mice by injection of cytidine-3H ([3H]CR) into the footpad of the left hind leg was used to evaluate lymphocyte traffic from the left regional nodes to the right popliteal lymph node (PLN) within a 24-h period, with or without concomitant primary or secondary stimulation of the right PLN with fluid tetanus toxoid. Results indicate that 1) in the case of primary antigen injection the relative contribution of lymphocytes from the left regional nodes to the small lymphocyte population present in the stimulated right PLN 24 h after labeling was slightly, but not significantly, greater than in non-stimulated controls; 2) a booster injection of antigen into the right hind leg footpad resulted in a significantly smaller relative contribution of lymphocytes from the previously primed left regional nodes to the small lymphocyte population in the right PLN, 24 h after injection of [3H]CR and secondary stimulation, as compared with controls or animals given a primary stimulation to the receiver node; and 3) in contrast to controls and mice subjected to primary stimulation only, the right PLN 24 h after booster contained a significant number of large lymphoid cells which, or whose precursors, had migrated to this site from contralateral nodes within a day, possibly also in the form of small lymphocytes. These findings are discussed in relation to the problem of lymphocyte recruitment and divergent behavior of non-committed lymphocytes as compared with memory cells in the initial phase after primary or secondary antigenic stimulation.