RESUMEN
Burnout and its negative sequelae are a persistent problem in gynecologic oncology, threatening the health of our physician workforce. Individual-level interventions such as stress management training, physical activity, and sleep hygiene only partially address this widespread, systemic crisis rooted in the extended work hours and stressful situations associated with gynecologic oncology practice. There is an urgent need for systematic, institution-level changes to allow gynecologic oncologists to continue the crucial work of caring for people with gynecologic cancer. We present recommendations for institution-level changes which are grounded in the framework presented by the National Plan for Health Workforce Well-Being by the National Academy of Medicine. These are aimed at facilitating gynecologic oncologists' well-being and reduction of burnout. Recommendations include efforts to create a more positive and inclusive work environment, decrease administrative barriers, promote mental health, optimize electronic medical record use, and support a diverse workforce. Implementation and regular evaluation of these interventions, with specific attention to at-risk groups, is an important next step.
Asunto(s)
Agotamiento Profesional , Ginecología , Oncología Médica , Oncólogos , Humanos , Agotamiento Profesional/prevención & control , Femenino , Ginecología/normas , Oncología Médica/normas , Neoplasias de los Genitales Femeninos/terapia , Neoplasias de los Genitales Femeninos/psicología , Sociedades Médicas/normas , Promoción de la Salud/métodosRESUMEN
BACKGROUND: Despite evidence supporting its use, many Enhanced Recovery After Surgery (ERAS) recommendations remain poorly adhered to and barriers to ERAS implementation persist. In this second updated ERAS® Society guideline, a consensus for optimal perioperative care in gynecologic oncology surgery is presented, with a specific emphasis on implementation challenges. METHODS: Based on the gaps identified by clinician stakeholder groups, nine implementation challenge topics were prioritized for review. A database search of publications using Embase and PubMed was performed (2018-2023). Studies on each topic were selected with emphasis on meta-analyses, randomized controlled trials, and large prospective cohort studies. These studies were then reviewed and graded by an international panel according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. RESULTS: All recommendations on ERAS implementation challenge topics are based on best available evidence. The level of evidence for each item is presented accordingly. CONCLUSIONS: The updated evidence base and recommendations for stakeholder derived ERAS implementation challenges in gynecologic oncology are presented by the ERAS® Society in this consensus review.
Asunto(s)
Recuperación Mejorada Después de la Cirugía , Neoplasias de los Genitales Femeninos , Femenino , Humanos , Neoplasias de los Genitales Femeninos/cirugía , Estudios Prospectivos , Atención Perioperativa , Procedimientos Quirúrgicos GinecológicosRESUMEN
OBJECTIVE: Pelvic exenteration (PE) is an extensive surgery associated with high rates of postoperative morbidity and mortality. The absence of well-defined preoperative selection criteria to identify patients eligible for PE prompted the assessment of pre-operative predictors of 30-day major surgical complications. METHODS: Demographics and surgical characteristics of patients undergoing PE for gynecologic cancer in a single institution between 01/2004-12/2016 were reviewed. Postoperative complications within 30â¯days following surgery were graded using the Accordion grading system. Logistic regression was used to analyze potential risk factors for severe postoperative complications. RESULTS: A total of 138 patients were included in the cohort. Forty-five patients underwent total PE, 52 anterior PE, and 41 posterior PE. Among the 137 patients with follow-up, a severe postoperative complication was experienced by 37 patients (27.0%) and 3 patients (2.2%) experienced death within 90â¯days. The most frequent grade 3 complications were complications of urinary reconstruction (nâ¯=â¯15), wound dehiscence (nâ¯=â¯9), and abdominal abscess requiring intervention with drain or return to the operating room (nâ¯=â¯6). On multivariable analysis, independent predictors of severe postoperative complications were anterior or total PE (adjusted odds ratio (aOR): 11.66, 95% CI 2.56-53.18), pre-operative hemoglobin ≤10â¯mg/dl (aOR 2.70, 95% CI 1.02-7.14) and presence of 3+ comorbidities (aOR: 2.76, 95% CI 1.07-7.10). CONCLUSIONS: Major complications after exenteration are common. Surgical complexity and patient selection play a considerable role in predicting complications. These data can be used to better risk stratify patients undergoing PE.
Asunto(s)
Neoplasias de los Genitales Femeninos/cirugía , Exenteración Pélvica/efectos adversos , Complicaciones Posoperatorias/etiología , Adulto , Anciano , Femenino , Humanos , Modelos Logísticos , Persona de Mediana Edad , Estudios RetrospectivosRESUMEN
The discovery of toxin-antitoxin gene pairs (also called addiction modules) on extrachromosomal elements of Escherichia coli, and particularly the discovery of homologous modules on the bacterial chromosome, suggest that a potential for programmed cell death may be inherent in bacterial cultures. We have reported on the E. coli mazEF system, a regulatable addiction module located on the bacterial chromosome. MazF is a stable toxin and MazE is a labile antitoxin. Here we show that cell death mediated by the E. coli mazEF module can be triggered by several antibiotics (rifampicin, chloramphenicol, and spectinomycin) that are general inhibitors of transcription and/or translation. These antibiotics inhibit the continuous expression of the labile antitoxin MazE, and as a result, the stable toxin MazF causes cell death. Our results have implications for the possible mode(s) of action of this group of antibiotics.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , Antitoxinas/genética , Antitoxinas/metabolismo , Apoptosis , Proteínas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Medios de Cultivo , Regulación Bacteriana de la Expresión Génica , Biosíntesis de Proteínas/efectos de los fármacos , Transcripción Genética/efectos de los fármacosRESUMEN
The E. coli RelA protein is a ribosome-dependent (p)ppGpp synthetase that is activated in response to amino acid starvation. RelA can be dissected both functionally and physically into two domains: The N-terminal domain (NTD) (amino acids [aa] 1 to 455) contains the catalytic domain of RelA, and the C-terminal domain (CTD) (aa 455 to 744) is involved in regulating RelA activity. We used mutational analysis to localize sites important for RelA activity and control in these two domains. We inserted two separate mutations into the NTD, which resulted in mutated RelA proteins that were impaired in their ability to synthesize (p)ppGpp. When we caused the CTD in relA(+) cells to be overexpressed, (p)ppGpp accumulation during amino acid starvation was negatively affected. Mutational analysis showed that Cys-612, Asp-637, and Cys-638, found in a conserved amino acid sequence (aa 612 to 638), are essential for this negative effect of the CTD. When mutations corresponding to these residues were inserted into the full-length relA gene, the mutated RelA proteins were impaired in their regulation. In attempting to clarify the mechanism through which the CTD regulates RelA activity, we found no evidence for competition for ribosomal binding between the normal RelA and the overexpressed CTD. Results from CyaA complementation experiments of the bacterial two-hybrid system fusion plasmids (G. Karimova, J. Pidoux, A. Ullmann, and D. Ladant, Proc. Natl. Acad. Sci. USA 95:5752-5756, 1998) indicated that the CTD (aa 564 to 744) is involved in RelA-RelA interactions. Our findings support a model in which RelA activation is regulated by its oligomerization state.
Asunto(s)
Escherichia coli/enzimología , Ligasas/metabolismo , Toxina de Adenilato Ciclasa , Aminoácidos/deficiencia , Proteínas Bacterianas/genética , Análisis Mutacional de ADN , Activación Enzimática , Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Prueba de Complementación Genética , Guanosina Pentafosfato/metabolismo , Guanosina Tetrafosfato/metabolismo , Ligasas/genética , Modelos Biológicos , Conformación Proteica , Precursores de Proteínas/genética , Estructura Terciaria de Proteína , Ribosomas/metabolismo , Técnicas del Sistema de Dos HíbridosRESUMEN
The Escherichia coli mazEF system is a chromosomal "addiction module" that, under starvation conditions in which guanosine-3',5'-bispyrophosphate (ppGpp) is produced, is responsible for programmed cell death. This module specifies for the toxic stable protein MazF and the labile antitoxic protein MazE. Upstream from the mazEF module are two promoters, P(2) and P(3) that are strongly negatively autoregulated by MazE and MazF. We show that the expression of this module is positively regulated by the factor for inversion stimulation. What seems to be responsible for the negative autoregulation of mazEF is an unusual DNA structure, which we have called an "alternating palindrome." The middle part, "a," of this structure may complement either the downstream fragment, "b," or the upstream fragment, "c". When the MazE.MazF complex binds either of these arms of the alternating palindrome, strong negative autoregulation results. We suggest that the combined presence of the two promoters, the alternating palindrome structure and the factor for inversion stimulation-binding site, all permit the expression of the mazEF module to be sensitively regulated under various growth conditions.
Asunto(s)
Apoptosis/genética , Proteínas de Unión al ADN/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Regiones Promotoras Genéticas , Antitoxinas , Secuencia de Bases , Proteínas Portadoras/metabolismo , Endorribonucleasas , Genes Bacterianos , Factores de Integración del Huésped , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Unión ProteicaRESUMEN
In bacteria, programmed cell death is mediated through "addiction modules" consisting of two genes. The product of the second gene is a stable toxin, whereas the product of the first is a labile antitoxin. Here we extensively review what is known about those modules that are borne by one of a number of Escherichia coli extrachromosomal elements and are responsible for the postsegregational killing effect. We focus on a recently discovered chromosomally borne regulatable addiction module in E. coli that responds to nutritional stress and also on an antideath gene of the E. coli bacteriophage lambda. We consider the relation of these two to programmed cell death and antideath in bacterial cultures. Finally, we discuss the similarities between basic features of programmed cell death and antideath in both prokaryotes and eukaryotes and the possibility that they share a common evolutionary origin.
Asunto(s)
Apoptosis , Bacteriófago lambda/genética , Escherichia coli/citología , Genes Bacterianos , Plásmidos/genética , Apoptosis/genética , Apoptosis/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/fisiología , Escherichia coli/crecimiento & desarrollo , Escherichia coli/virología , Genes Virales , Proteínas Virales/genética , Proteínas Virales/fisiologíaRESUMEN
In Escherichia coli, programmed cell death is mediated through "addiction modules" consisting of two genes; the product of one gene is long-lived and toxic, whereas the product of the other is short-lived and antagonizes the toxic effect. Here we show that the product of lambdarexB, one of the few genes expressed in the lysogenic state of bacteriophage lambda, prevents cell death directed by each of two addiction modules, phd-doc of plasmid prophage P1 and the rel mazEF of E. coli, which is induced by the signal molecule guanosine 3',5'-bispyrophosphate (ppGpp) and thus by amino acid starvation. lambdaRexB inhibits the degradation of the antitoxic labile components Phd and MazE of these systems, which are substrates of ClpP proteases. We present a model for this anti-cell death effect of lambdaRexB through its action on the ClpP proteolytic subunit. We also propose that the lambdarex operon has an additional function to the well known phenomenon of exclusion of other phages; it can prevent the death of lysogenized cells under conditions of nutrient starvation. Thus, the rex operon may be considered as the "survival operon" of phage lambda.
Asunto(s)
Bacteriófago lambda/genética , Escherichia coli/genética , Proteínas Virales/genética , Proteínas Virales/metabolismo , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , Clonación Molecular , Endopeptidasa Clp , Escherichia coli/crecimiento & desarrollo , Escherichia coli/virología , Genotipo , Guanilil Imidodifosfato/metabolismo , Ligasas/genética , Ligasas/metabolismo , Lisogenia , Mutagénesis Insercional , Plásmidos , Proteínas Recombinantes/metabolismo , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismoRESUMEN
The immediate early BRLF1 and BZLF1 promoters of Epstein-Barr virus are crucial for triggering the replicative cycle of the virus. To better understand the cell type dependence of the lytic cycle we conducted an analysis of the BRLF1-promoter in the epithelial cell line HeLa and the lymphoid cell line IM9. To analyze promoter activities, transient transfections with 5'-deletions of the BRLF1-promoter in front of luciferase as reporter gene were conducted. Besides the already known cis-acting elements of the promoter close to the TATA-box, more distal elements were located and functionally tested. A nuclear factor 1 consensus site was found to act positively in HeLa cells, but did not in lymphoid IM9 cells. The NF1 site was shown to bind protein by electrophoretic mobility shift assays, antibody-supershifts and in vitro footprinting. Thus, a protein belonging to the nuclear factor 1 family of proteins was identified as additional cellular trans-acting factor for the BRLF1-promoter besides the already described factors Sp1, Zta and Zif268.
Asunto(s)
Proteínas Potenciadoras de Unión a CCAAT , Proteínas de Unión al ADN/metabolismo , Genes Inmediatos-Precoces , Herpesvirus Humano 4/genética , Regiones Promotoras Genéticas , Factores de Transcripción/metabolismo , Sitios de Unión , Células HeLa , Humanos , Factores de Transcripción NFI , Proteínas Nucleares , Proteína 1 de Unión a la Caja YAsunto(s)
Citometría de Flujo/métodos , Proteínas Luminiscentes/genética , Plásmidos/análisis , Replicación del ADN/genética , Electroporación , Genes Reporteros/genética , Proteínas Fluorescentes Verdes , Herpesvirus Humano 4/genética , Humanos , Plásmidos/genética , Transfección/genética , Células Tumorales CultivadasRESUMEN
"Addiction modules" consist of two genes. In most of them the product of one is long lived and toxic while the product of the second is short lived and antagonizes the toxic effect; so far, they have been described mainly in a number of prokaryotic extrachromosomal elements responsible for the postsegregational killing effect. Here we show that the chromosomal genes mazE and mazF, located in the Escherichia coli rel operon, have all of the properties required for an addiction module. Furthermore, the expression of mazEF is regulated by the cellular level of guanosine [corrected] 3',5'-bispyrophosphate, the product of the RelA protein under amino acid starvation. These properties suggest that the mazEF system may be responsible for programmed cell death in E. coli and thus may have a role in the physiology of starvation.
Asunto(s)
Cromosomas Bacterianos , Proteínas de Escherichia coli , Escherichia coli/genética , Guanosina Tetrafosfato/farmacología , Proteínas Bacterianas/genética , Secuencia de Bases , ADN Bacteriano , Proteínas de Unión al ADN , Endorribonucleasas , Escherichia coli/citología , Eliminación de Gen , Datos de Secuencia Molecular , Mutación , Regiones Promotoras GenéticasRESUMEN
Most bacterial RNA consists of stable RNA which is composed of rRNA and tRNA. We have followed by primer extension analysis the level of ribosomal RNA synthesis along the growth phases of a cell culture. A sharp drop in rRNA synthesis was observed upon the transition from the exponential to the stationary phase of growth. Our results demonstrate that an effective shut-off of rRNA synthesis occurs also in the absence of ppGpp. Mutations in the host factors Fis and H-NS, which are known to regulate rrn P1 promoters, did not affect the shut-off process of ribosomal RNA promoters. We also tested the effect of RpoS, the sigma factor known to induce a number of genes in the stationary phase. It was shown that the host factors Fis, H-NS and RpoS do not play a major role in the regulation of the shut-off process of rRNA synthesis. The results presented demonstrate that the rate of rRNA synthesis provides a sensitive measure of the growth phase of the bacterial culture.
Asunto(s)
Escherichia coli/genética , Regiones Promotoras Genéticas/genética , ARN Ribosómico/genética , Proteínas Bacterianas/genética , Técnicas Bacteriológicas , Secuencia de Bases , División Celular/genética , Cartilla de ADN/genética , ADN Bacteriano/genética , Proteínas de Unión al ADN/genética , Escherichia coli/crecimiento & desarrollo , Regulación Bacteriana de la Expresión Génica/genética , Guanosina Tetrafosfato/farmacología , Datos de Secuencia Molecular , ARN Bacteriano/genética , Factor sigma/genética , Transcripción Genética/genéticaRESUMEN
The segmentation gene hunchback (hb) plays a central role in determining the anterior-posterior pattern in the Drosophila embryo. We have cloned the homologue of hb from the flour beetle Tribolium and show that, on the basis of its expression pattern, most of its functions seem to be conserved between these two species. Like Drosophila, Tribolium has a maternal hb expression that appears to be under translational control by a factor at the posterior pole of the embryo. The maternal expression is followed by a zygotic expression in the region of the developing head and thoracic segments. During germ band extension, a posterior expression domain appears that is likely to be homologous to the posterior blastoderm expression of hb in Drosophila. These observations suggest that hb may have the same functions in early Drosophila and Tribolium development, despite the different types of embryogenesis in these two species (long versus short germ development). One differing aspect of hb expression in Tribolium concerns a structure that is not present in Drosophila, namely the serosa. An hb expression domain at the anterior pole precisely demarcates the border between the extraembryonic serosa and the embryonic field in the Tribolium embryo at an early stage, and hb protein remains expressed in the serosa cells until the end of embryogenesis.
Asunto(s)
Secuencia Conservada , Proteínas de Unión al ADN , Proteínas de Drosophila , Genes de Insecto , Hormonas Juveniles/genética , Factores de Transcripción , Tribolium/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cartilla de ADN/genética , Drosophila/genética , Exones , Datos de Secuencia Molecular , Morfogénesis/genética , Tribolium/embriologíaRESUMEN
Understanding protein-DNA interactions in vivo at origins of DNA replication throughout the cell cycle may shed further insight on the mechanisms of initiation and replication control. The Burkitt's lymphoma cell line Raji harbors multiple copies of latent Epstein-Barr virus. Once per cell cycle the origin of plasmid replication of Epstein-Barr virus provides replication function in cis for the viral DNA. Here we examined in vivo nucleoprotein complexes on the initiator element of the origin before and after DNA synthesis. For this purpose Raji cells were synchronously growth arrested in G1 phase by mimosine and in mitosis by colchicine, respectively. The association of the initiator element with proteins was visualized by footprinting with dimethyl sulfate and ligation mediated polymerase chain reaction. Methylation patterns indicated a novel binding activity within each element of a nonamer repeated three times at the initiator element. This activity was strongly diminished in mitotic cells. Furthermore, 5'-ends of Epstein-Barr virus DNA were mapped to the nonamers by ligation mediated polymerase chain reaction, suggesting potential initiation sites for replication from DS.
Asunto(s)
Ciclo Celular/genética , Replicación del ADN , ADN Viral/genética , Herpesvirus Humano 4/genética , Nucleoproteínas/análisis , Antígenos Virales/metabolismo , Secuencia de Bases , Linfoma de Burkitt , Ciclo Celular/efectos de los fármacos , Colchicina/farmacología , ADN/efectos de los fármacos , Proteínas de Unión al ADN/metabolismo , Antígenos Nucleares del Virus de Epstein-Barr , Fase G1/genética , Humanos , Mimosina/farmacología , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Unión Proteica , Origen de Réplica , Fase S/genética , Ésteres del Ácido Sulfúrico/farmacología , Células Tumorales Cultivadas , Latencia del VirusRESUMEN
ppGpp serves as an alarmon in prokaryotes, distributing and coordinating different cellular processes according to the nutritional potential of the growth medium. This work is interpreted as favoring the view that, in addition to its previously documented role in regulating the rate of ribosome synthesis, ppGpp participates in coordinating DNA replication and cell division. We studied the effects of ppGpp on the cell division cycle, using cells containing plasmid pSM11 that codes for the 55-kDa truncated RelA protein under the inducible Ptac promoter. In this system it was found that the rate of initiation of new rounds of DNA replication is inversely correlated with the intracellular level of ppGpp. Furthermore, ppGpp levels similar to those found during the activation of stringent control inhibited replication initiation, in a manner comparable to that resulting from inhibition of protein synthesis by amino acid starvation or by chloramphenicol addition. However, in contrast to chloramphenicol treatment, elevated ppGpp levels did not block septum formation, and, in fact, there is some evidence for enhanced septation. As a result, the residual cell division following elevation in ppGpp levels was higher than after chloramphenicol treatment, resulting in cells with a size similar to that of stationary phase cells.
Asunto(s)
Replicación del ADN/fisiología , Escherichia coli/metabolismo , Guanosina Tetrafosfato/metabolismo , División Celular/efectos de los fármacos , División Celular/fisiología , Cloranfenicol/farmacología , Replicación del ADN/efectos de los fármacos , Escherichia coli/citología , Escherichia coli/genética , Genes Bacterianos/efectos de los fármacos , Isopropil Tiogalactósido/farmacología , Ligasas/genética , Plásmidos/genéticaRESUMEN
Transcriptional control of the himA and the himD/hip genes coding for the two subunits of the integration host factor (IHF) was investigated. The promoters for the two genes were identified by the use of primer extension and S1 analysis. Expression from both promoters was found to increase as the cells enter stationary phase. Mutation in rpoS, known to be induced upon entry to stationary phase, dramatically reduced the growth-phase response of the himA P4 promoter but had only a small effect on the induction of the himD/hip promoter. The increased activity of both promoters required the presence of the relA and spoT genes, suggesting that ppGpp plays a major role in the response to stationary phase. An artificial increase in ppGpp in exponentially growing cells induced a rapid increase in himA P4 and himD/hip mRNA levels. Experiments with a mutant defective in rpoS showed that the response of the himA P4 promoter to high ppGpp levels was greatly reduced while that of himD/hip was only slightly affected. Therefore, it seems that different mechanisms involving RpoS and ppGpp regulate the growth-phase response of the two promoters. We propose that the effect of ppGpp on himA P4 is mediated via RpoS whereas the himD/hip promoter is affected by ppGpp independently of RpoS. Expression of the himD/hip and himA genes was found to be subject to negative autoregulation. IHF-binding sites, implicated in autoregulation, were found to overlap both the himD/hip and himA P4 promoters. An additional IHF-binding site was found upstream of the himD/hip promoter. All three sites show low binding affinity to IHF suggesting that autoregulation can take place only after sufficiently high levels of IHF accumulate in the cell.
Asunto(s)
Proteínas Bacterianas/genética , Escherichia coli/genética , Genes Bacterianos , Proteínas Bacterianas/metabolismo , Secuencia de Bases , Sitios de Unión , Clonación Molecular , Cartilla de ADN/genética , ADN Bacteriano/genética , Escherichia coli/crecimiento & desarrollo , Escherichia coli/metabolismo , Regulación Bacteriana de la Expresión Génica , Guanosina Tetrafosfato/metabolismo , Homeostasis , Factores de Integración del Huésped , Datos de Secuencia Molecular , Regiones Promotoras Genéticas , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factor sigma/metabolismoRESUMEN
Ribosomal RNA synthesis in Escherichia coli is under stringent control. The seven rRNA operons are highly conserved and are each transcribed from two tandem promoters, P1 and P2, which are located about 120 base-pairs apart. In exponentially growing cells the majority of the transcripts are initiated at the P1 promoters. The P1 promoters are highly regulated, and are under stringent as well as growth rate controls. Here we demonstrate that transcription from the rrnA P1 promoter diminishes P2 expression. In the absence of P1, the P2 promoter acts as a rather strong promoter. Insertion of a transcription terminator between P1 and P2 eliminates the inhibition of P2 by P1, suggesting that the physical movement of RNA polymerase originating at P1 and progressing along the P2 promoter is necessary for the interference process to take place. Similarly to P1, the solitary P2 promoter is subject to stringent control.
Asunto(s)
Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , ARN Bacteriano/genética , ARN Ribosómico/biosíntesis , Operón de ARNr/genética , Secuencia de Bases , Datos de Secuencia Molecular , ARN Bacteriano/biosíntesis , ARN Ribosómico/genética , Transcripción GenéticaRESUMEN
hunchback (hb) is a key regulatory gene in the early segmentation gene hierarchy of Drosophila. It codes for a transcription factor of the Cys2-His2 zinc finger type and shows two separate zinc finger domains in its coding region. hb forms a morphogenetic gradient in the middle of the embryo that is required for setting the spatial boundaries of several target genes. We have analyzed the molecular lesions found in the different hb alleles and have studied the differential effects of these alleles on a number of such target genes. We find that in mutants in which the HB protein lacks a functional second finger domain, the regulation of the target genes Krüppel (Kr) and knirps (kni) is differentially affected. While this domain is required for the correct regulation of Kr, it is not necessary for the repression of kni. Furthermore, mutations affecting this domain lead to a decreased protein stability. The integration of the expression pattern of target genes was found to be distorted in a second class of mutants between the two finger domains which lead to gain of function or neomorphic phenotypes. The effects of these mutations were studied in detail and it was found that they fall into two classes, the first one interfering with the function of the maternal hb product, the second leading to a delayed segmentation. The function of the latter class appears to be linked to the secondary expression of hb in the parasegment 4 (PS4) stripe at blastoderm stage.
Asunto(s)
Proteínas de Unión al ADN , Proteínas de Drosophila , Drosophila/embriología , Drosophila/genética , Genes de Insecto , Alelos , Secuencia de Aminoácidos , Animales , Secuencia de Bases , ADN/genética , Análisis Mutacional de ADN , Drosophila/metabolismo , Femenino , Regulación del Desarrollo de la Expresión Génica , Hormonas Juveniles/genética , Hormonas Juveniles/metabolismo , Masculino , Datos de Secuencia Molecular , Mutación , Fenotipo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Dedos de Zinc/genéticaRESUMEN
The histidine analog 3-amino-1,2,4-triazole (AT) was used for the selection of spontaneous AT-resistant revertants of a relA mutant of Bacillus subtilis. One of these revertants, L3, showed a unique phenotype; it did not respond to amino acid starvation, like the relA mutant, but it did respond to glucose starvation by the accumulation of (p)ppGpp, unlike its parent. Genetic analysis revealed that this suppressor mutant (relA(S)) allele mapped to the relA locus at 239 degrees on the B. subtilis chromosome.
Asunto(s)
Bacillus subtilis/genética , Carbono/metabolismo , Genes Supresores , Ligasas/genética , Mutación , Alelos , Bacillus subtilis/metabolismo , Cromosomas Bacterianos , Ligasas/metabolismo , FenotipoRESUMEN
The segmentation gene hunchback (hb) is involved in setting up the anterior-posterior axis of the Drosophila embryo. It is expressed maternally and zygotically and it plays a key role in integrating the effects of the anterior and posterior maternal systems. The hb gene from D. virilis has previously been cloned and was shown to be well conserved in its coding region, but less so in its upstream region which shows a more patchy pattern of conserved and diverged sequences. This work deals with the functional conservation of hb between the two species. We have mapped two additional regulatory elements for the expression of hb in the early embryo, namely the enhancer for the maternal expression and the enhancer region for the late blastoderm expression. Fragments containing these two elements, the previously identified bicoid dependent element for the early blastoderm expression of hb and the coding region were taken from D. virilis and tested in the D. melanogaster background. We find that all enhancer elements as well as the coding region are functionally conserved between the two species. Comparison of the upstream sequences that include the enhancer region for the late blastoderm expression reveal seven highly conserved blocks. Some of these contain consensus binding sites for transregulatory factors that are likely to control the respective expression domains.