RESUMO
PURPOSE: Guidelines recommend endocrine treatment for estrogen receptor-positive (ER+) breast cancers for up to 10 years. Earlier data suggest that the 70-gene signature (MammaPrint) has potential to select patients that have an excellent survival without chemotherapy and limited or no tamoxifen treatment. The aim was to validate the 70-gene signature ultralow-risk classification for endocrine therapy decision making. METHODS: In the IKA trial, postmenopausal patients with non-metastatic breast cancer had been randomized between no or limited adjuvant tamoxifen treatment without receiving chemotherapy. For this secondary analysis, FFPE tumor material was obtained of ER+HER2- patients with 0-3 positive lymph nodes and tested for the 70-gene signature. Distant recurrence-free interval (DRFI) long-term follow-up data were collected. Kaplan-Meier curves were used to estimate DRFI, stratified by lymph node status, for the three predefined 70-gene signature risk groups. RESULTS: A reliable 70-gene signature could be obtained for 135 patients. Of the node-negative and node-positive patients, respectively, 20% and 13% had an ultralow-risk classification. No DRFI events were observed for node-negative patients with an ultralow-risk score in the first 10 years. The 10-year DRFI was 90% and 66% in the low-risk (but not ultralow) and high-risk classified node-negative patients, respectively. CONCLUSION: These survival analyses indicate that the postmenopausal node-negative ER+HER2- patients with an ultralow-risk 70-gene signature score have an excellent 10-year DRFI after surgery with a median of 1 year of endocrine treatment. This is in line with published results of the STO-3-randomized clinical trial and supports the concept that it is possible to reduce the duration of endocrine treatment in selected patients.
Assuntos
Neoplasias da Mama , Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Quimioterapia Adjuvante , Feminino , Humanos , Sobretratamento , Pós-Menopausa , Prognóstico , Tamoxifeno/uso terapêuticoRESUMO
BACKGROUND: Insight into the causes of colorectal cancer (CRC) in adolescent and young adult (AYA) patients is limited. Without definitive information, patients often shape their own beliefs on the cause of their illness, developing causal attributions. This study aims to examine the causal attributions of CRC in AYA patients, compare these with middle-aged and older adults CRC patient groups and explore the association between causal attributions and psychological distress. METHODS: Two cross-sectional questionnaire studies were conducted among CRC survivors diagnosed between 1998 and 2007 using the population-based PROFILES registry. Three groups were defined by age at diagnosis: AYA (18-39 years; n = 67), middle-aged (40-70 years; n = 1993) and older adult survivors (70+ years; n = 1922). Causal attributions were assessed in a single free-text item from the Brief Illness Perception Questionnaire and psychological distress measured by the Hospital Anxiety and Depression Scale. RESULTS: AYA survivors most often attributed their CRC to heredity (36.4%), lifestyle (14.5%) and chance (10.9%). AYA survivors attributed their CRC to these causes more frequently than middle-aged and older adult CRC survivors. AYA survivors who attributed their CRC to causes out of their control (chance, heredity) showed significantly lower mean scores on anxiety (4.3 vs. 5.6; p < 0.01) compared to AYAs who reported causes within their control (lifestyle, stress). No significant difference was found for depression. CONCLUSION: AYA patients with CRC may benefit from in-depth discussion about the lack of known (biological) causes and how this does not directly imply a lifestyle or stress cause.
Assuntos
Sobreviventes de Câncer/psicologia , Neoplasias do Colo/psicologia , Neoplasias do Colo/terapia , Conhecimentos, Atitudes e Prática em Saúde , Adolescente , Adulto , Idoso , Ansiedade/psicologia , Neoplasias do Colo/etiologia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção Social , Inquéritos e Questionários , Adulto JovemRESUMO
PURPOSE: To evaluate the impact of chemotherapy on subjective cognitive functioning according to age in a large cohort of breast cancer patients. METHODS: Within the UMBRELLA cohort, 715 patients with early-stage primary invasive breast cancer (T1-3N0-1M0) were selected. Subjective cognitive function was assessed by means of the EORTC QLQ-C30 up to 24 months and compared between patients treated with and without chemotherapy, for three different age strata (355 patients < 55 years, 240 patients aged 55-65 years, and 120 patients > 65 years). Differences between chemotherapy and non-chemotherapy patients by age at different time points were assessed by linear mixed-effect models correcting for age, tumor stage, educational level, endocrine therapy, anxiety, and depression. RESULTS: In total, 979 patients from the UMBRELLA cohort were included, of which 715 (73%) responded to baseline and at least one follow-up questionnaire. Questionnaire response rates ranged between 92 and 70%. The proportion of patients treated with chemotherapy decreased with age: 64% (n = 277) in patients < 55 years, 45% (n = 107) in patients 55-65 years, and 23% (n = 27) in patients > 65 years. Chemotherapy was associated with reduced subjective cognitive functioning. The impact of chemotherapy on subjective cognitive function was most pronounced in patients < 55 years, followed by those between 55 and 65 years. In the youngest age groups, patients treated with chemotherapy had significantly lower cognitive functioning up to 24 months. In women over 65 years, subjective cognitive functioning was comparable between patients treated with and without chemotherapy. CONCLUSION: This study confirms that chemotherapy is associated with impaired subjective self-reported cognitive functioning in breast cancer patients, and the effect persists at least up to 2 years after diagnosis. The impact of chemotherapy on self-reported cognitive functioning in the first 24 months is most pronounced in younger patients, especially those under 55 years of age.
Assuntos
Fatores Etários , Neoplasias da Mama/epidemiologia , Sobreviventes de Câncer , Cognição/efeitos dos fármacos , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/complicações , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Quimioterapia Adjuvante/efeitos adversos , Cognição/fisiologia , Feminino , Humanos , Mastectomia , Mastectomia Segmentar , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Qualidade de Vida , Autorrelato , Inquéritos e QuestionáriosRESUMO
OBJECTIVE: Next-generation sequencing (NGS) is increasingly being employed in the context of personalized cancer treatment. Anticipating unsolicited findings that may arise during a NGS procedure is a key consideration; however, little is known about cancer patients' intentions, needs, and preferences concerning the return of unsolicited findings. METHODS: A qualitative design using individual semi-structured interviews with 24 cancer patients was utilized to explore patients' decisions on whether to receive unsolicited findings from NGS. These interviews were subsequently analyzed using the constant comparative method to develop codes and themes. RESULTS: We identified 4 interrelated themes that emerged in the context of the return of unsolicited findings. First, we describe how cancer patients expressed a strong need to control their lives. Second, we show the importance of family dynamics. Third, the NGS procedure regarding unsolicited findings is perceived as cognitively complex, and fourth, the procedure is also considered emotionally complex. CONCLUSIONS: The results of our study contribute to a better understanding of what cancer patients consider important and what may motivate and influence them when making decisions on the disclosure of unsolicited findings following NGS. We show how Joel Feinberg's classification of autonomy may help clinicians to better understand cancer patients' desire for autonomous decision making while also acknowledging the emotional and cognitive difficulties regarding the disclosure of unsolicited findings. These insights could be helpful for clinicians to guide patients through this complex process.
Assuntos
Família/psicologia , Genômica , Neoplasias/psicologia , Preferência do Paciente/psicologia , Adaptação Psicológica , Adulto , Tomada de Decisões , Revelação , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/genética , Pesquisa QualitativaRESUMO
BACKGROUND: With increasing survival rates of adolescents and young adults (AYAs) with breast cancer, health-related quality of life (HRQoL) becomes more important. An important aspect of HRQoL is sexual QoL. This study examined long-term sexual QoL of AYA breast cancer survivors, compared sexual QoL scores with that of other AYA cancer survivors, and identified factors associated with long-term sexual QoL of AYA breast cancer survivors. MATERIALS AND METHODS: Data of the SURVAYA study were utilized for secondary analyses. Sexual QoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life cancer survivorship core questionnaire (EORTC QLQ-SURV100). Descriptive statistics were used to describe sexual QoL of AYA cancer survivors. Linear regression models were constructed to examine the effect of cancer type on sexual QoL and to identify factors associated with sexual QoL. RESULTS: Of the 4010 AYA cancer survivors, 944 had breast cancer. Mean sexual QoL scores of AYA breast cancer survivors ranged from 34.5 to 60.0 for functional domains and from 25.2 to 41.5 for symptom-orientated domains. AYA breast cancer survivors reported significantly lower sexual QoL compared to AYA survivors of other cancer types on all domains. Age, time since diagnosis, relationship status, educational level, chemotherapy, hormonal therapy, breast surgery, body image, and coping were associated with sexual QoL of AYA breast cancer survivors. CONCLUSIONS: AYA breast cancer survivors experience decreased sexual QoL in the long term (5-20 years) after diagnosis and worse score compared to AYA survivors of other cancer types, indicating a clear need to invest in supportive care interventions for those at risk, to enhance sexual well-being.
Assuntos
Neoplasias da Mama , Sobreviventes de Câncer , Humanos , Adolescente , Adulto Jovem , Feminino , Neoplasias da Mama/terapia , Qualidade de Vida , Sobreviventes , MamaRESUMO
BACKGROUND: In the absence of prognostic biomarkers, most patients with early-stage triple-negative breast cancer (eTNBC) are treated with combination chemotherapy. The identification of biomarkers to select patients for whom treatment de-escalation or escalation could be considered remains an unmet need. We evaluated the prognostic value of histopathologic traits in a unique cohort of young, (neo)adjuvant chemotherapy-naïve patients with early-stage (stage I or II), node-negative TNBC and long-term follow-up, in relation to stromal tumor-infiltrating lymphocytes (sTILs) for which the prognostic value was recently reported. MATERIALS AND METHODS: We studied all 485 patients with node-negative eTNBC from the population-based PARADIGM cohort which selected women aged <40 years diagnosed between 1989 and 2000. None of the patients had received (neo)adjuvant chemotherapy according to standard practice at the time. Associations between histopathologic traits and breast cancer-specific survival (BCSS) were analyzed with Cox proportional hazard models. RESULTS: With a median follow-up of 20.0 years, an independent prognostic value for BCSS was observed for lymphovascular invasion (LVI) [adjusted (adj.) hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.49-3.69], fibrotic focus (adj. HR 1.61, 95% CI 1.09-2.37) and sTILs (per 10% increment adj. HR 0.75, 95% CI 0.69-0.82). In the sTILs <30% subgroup, the presence of LVI resulted in a higher cumulative incidence of breast cancer death (at 20 years, 58%; 95% CI 41% to 72%) compared with when LVI was absent (at 20 years, 32%; 95% CI 26% to 39%). In the ≥75% sTILs subgroup, the presence of LVI might be associated with poor survival (HR 11.45, 95% CI 0.71-182.36, two deaths). We confirm the lack of prognostic value of androgen receptor expression and human epidermal growth factor receptor 2 -low status. CONCLUSIONS: sTILs, LVI and fibrotic focus provide independent prognostic information in young women with node-negative eTNBC. Our results are of importance for the selection of patients for de-escalation and escalation trials.
Assuntos
Neoplasias de Mama Triplo Negativas , Humanos , Feminino , Prognóstico , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/patologia , Linfócitos do Interstício Tumoral/metabolismo , Linfócitos do Interstício Tumoral/patologia , Biomarcadores Tumorais , Quimioterapia AdjuvanteRESUMO
Over the past twenty years conservation genetics has progressed from being mainly a theory-based field of population biology to a full-grown empirical discipline. Technological developments in molecular genetics have led to extensive use of neutral molecular markers such as microsatellites in conservation biology. This has allowed assessment of the impact of genetic drift on genetic variation, of the level of inbreeding within populations, and of the amount of gene flow between or within populations. Recent developments in genomic techniques, including next generation sequencing, whole genome scans and gene-expression pattern analysis, have made it possible to step up from a limited number of neutral markers to genome-wide estimates of functional genetic variation. Here, we focus on how the transition of conservation genetics to conservation genomics leads to insights into the dynamics of selectively important variation and its interaction with environmental conditions, and into the mechanisms behind this interaction.
Assuntos
Conservação dos Recursos Naturais , Genômica , Animais , Meio Ambiente , Genética Populacional , Plantas/genéticaRESUMO
PURPOSE: Our purpose was to assess the prevalence of patient-reported symptoms of local late toxicity in patients with irradiated breast cancer and determine the association between late toxicity and quality of life. METHODS: Within the prospective Utrecht cohort for Multiple BReast cancer intErvention studies and Long-term evaluation cohort, a survey on self-reported late toxicity was sent to all patients with breast cancer with ≥12 months interval since radiation therapy treated with curative intent. Patients were treated with hypofractionated radiation therapy of 40 Gy/15 fractions or 42.5 Gy/16 fractions, with or without a simultaneous integrated boost. Symptoms of late toxicity were evaluated on a 4-point Likert scale. Late toxicity was defined as moderate-severe breast or chest wall pain combined with at least 1 other mild-severe late toxicity symptom, that is, breast or arm/hand lymphedema, firmness of the breast, or impaired arm movement. Physical, role, and social functioning were measured before, during, and after the late toxicity survey using the European Organization for Research and Treatment of Cancer Quality of Life Core questionnaire-C30 and compared with a Dutch normative population. RESULTS: In the study, 1613/2248 patients (72%) were included. Of those, 16% (n = 265) reported late toxicity. The median time interval between radiation therapy and survey was 38 months (interquartile range, 21-55). Moderate/severe firmness of the breast, chest wall pain, and breast pain were reported by, respectively, 18% (n = 295), 14% (n = 225), and 10% (n = 140) of all patients. Physical, role, and social functioning were below the clinical threshold (ie, clinically relevant impairment) in 13% to 52% of patients with late toxicity and 2% to 26% of patients without late toxicity. Patients with late toxicity significantly more often received analgesics, physiotherapy, and lymphedema therapy compared with patients without late toxicity. CONCLUSIONS: This study provided insight into the prevalence of patient-reported late toxicity after hypofractionated radiation therapy and the influence of late toxicity on quality of life after breast cancer. These results may help health care professionals to inform their patients about long-term effects of breast cancer treatment including hypofractionated radiation therapy.
Assuntos
Neoplasias da Mama , Linfedema , Humanos , Feminino , Neoplasias da Mama/radioterapia , Estudos Prospectivos , Qualidade de Vida , Dor , Medidas de Resultados Relatados pelo PacienteRESUMO
Here we report evidence of a mitochondrial-Wolbachia sweep in North American populations of the parasitoid wasp Nasonia vitripennis, a cosmopolitan species and emerging model organism for evolutionary and genetic studies. Analysis of the genetic variation of 89 N. vitripennis specimens from Europe and North America was performed using four types of genetic markers: a portion of the mitochondrial cytochrome oxidase I gene, nine polymorphic nuclear microsatellites, sequences from 11 single-copy nuclear markers and six Wolbachia genes. The results show that the European populations have a sevenfold higher mitochondrial sequence variation than North American populations, but similar levels of microsatellite and nuclear gene sequence variation. Variation in the North American mitochondria is extremely low (pi=0.31%), despite a highly elevated mutation rate (approximately 35-40 times higher than the nuclear genes) in the mitochondria of Nasonia. The data are indicative of a mitochondrial sweep in the North American population, possibly due to Wolbachia infections that are maternally co-inherited with the mitochondria. Owing to similar levels of nuclear variation, the data could not resolve whether N. vitripennis originated in the New or the Old World.
Assuntos
Mitocôndrias/genética , Filogenia , Vespas/classificação , Wolbachia/genética , Animais , Proteínas de Bactérias/genética , Evolução Molecular , Variação Genética , Proteínas de Insetos/genética , Repetições de Microssatélites , Mitocôndrias/microbiologia , Modelos Genéticos , Dados de Sequência Molecular , Mutação , América do Norte , Vespas/genética , Vespas/microbiologia , Wolbachia/fisiologiaRESUMO
Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. Inverse terminal velocity (Vt(-1)) of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to different metrics of landscape connectivity, at two spatial scales: in a detailed analysis of eight landscapes in Spain and along a latitudinal gradient using 29 landscapes across three European regions. In the highly patchy Spanish landscapes, seed Vt(-1)increased significantly with increasing connectivity. A common garden experiment suggested that differences in Vt(-1) may be in part genetically based. The Vt(-1) was also found to increase with landscape occupancy, a coarser measure of connectivity, on a much broader (European) scale. Finally, Vt(-1)was found to increase along a south-north latitudinal gradient. Our results for M. muralis are consistent with 'Darwin's wind dispersal hypothesis' that high cost of dispersal may select for lower dispersal ability in fragmented landscapes, as well as with the 'leading edge hypothesis' that most recently colonized populations harbour more dispersive phenotypes.
Assuntos
Asteraceae/fisiologia , Ecossistema , Modelos Biológicos , Sementes/fisiologia , Vento , Característica Quantitativa Herdável , EspanhaRESUMO
Parasitoid Nasonia wasps adjust their progeny sex ratio to the presence of conspecifics to optimize their fitness. Another trait under female control is the induction of offspring diapause. We analysed progeny sex ratios and the proportion of diapausing offspring of individual Nasonia females in host patches parasitized by two species, Nasonia vitripennis and Nasonia giraulti, in North American field populations using microsatellite fingerprinting. Both Nasonia species produced similar sex ratios on hosts that were co-parasitized by their own species as by the other species, indicating that females do not distinguish between con- and heterospecific clutches. The sex ratios of the diapause and adult fractions of mixed broods from single females were not correlated. We found further indications that N. vitripennis females take the emergence time of the offspring into account in their sex allocation. The reproductive strategies of Nasonia under multiparasitism are largely adaptive, but also partially constrained by information.
Assuntos
Vespas/fisiologia , Animais , Dípteros/parasitologia , Feminino , Masculino , Densidade Demográfica , Pupa/parasitologia , Reprodução/fisiologia , Razão de MasculinidadeRESUMO
BACKGROUND: The study of inbreeding depression has major relevance for many disciplines, including conservation genetics and evolutionary biology. Still, the molecular genetic basis of this phenomenon remains poorly characterised, as knowledge on the mechanistic causes of inbreeding depression and the molecular properties of genes that give rise to or modulate its deleterious effects is lacking. These questions warrant the detailed study of genetic loci giving rise to inbreeding depression. However, the complex and polygenic nature of general inbreeding depression makes this a daunting task. Study of inbreeding effects in specific traits, such as age-specific mortality and life span, provide a good starting point, as a limited set of genes is expected to be involved. RESULTS: Here we report on a QTL mapping study on inbreeding related and temperature sensitive lethality in male Drosophila melanogaster. The inbreeding effect was expressed at moderately high temperature, and manifested itself as severe premature mortality in males, but not in females. We used a North Carolina crossing design 3 to estimate average dominance ratio and heritability. We found the genetic basis of the lethal effect to be relatively simple, being due mainly to a single recessive QTL on the left arm of chromosome 2. This locus colocalised with a QTL that conditioned variation in female life span, acting as an overdominant locus for this trait. Male life span was additionally affected by variation at the X-chromosome. CONCLUSION: This demonstrates that analysis of large conditional lethal effects is a viable strategy for delineating genes which are sensitive to inbreeding depression.
Assuntos
Drosophila melanogaster/fisiologia , Endogamia , Locos de Características Quantitativas , Animais , Drosophila melanogaster/genética , Feminino , Expectativa de Vida , Escore Lod , Longevidade , Masculino , Especificidade da Espécie , TemperaturaRESUMO
The parasitic wasp Nasonia vitripennis has been used extensively in sex allocation research. Although laboratory experiments have largely confirmed predictions of local mate competition (LMC) theory, the underlying assumptions of LMC models have hardly been explored in nature. We genotyped over 3500 individuals from two distant locations (in the Netherlands and Germany) at four polymorphic microsatellite loci to validate key assumptions of LMC theory, in terms of both the original models and more recent extensions to them. We estimated the number of females contributing eggs to patches of hosts and the clutch sizes as well as sex ratios produced by individual foundresses. In addition, we evaluated the level of inbreeding and population differentiation. Foundress numbers ranged from 1 to 7 (average 3.0 +/- 0.46 SE). Foundresses were randomly distributed across the patches and across hosts within patches, with few parasitizing more than one patch. Of the hosts, 40% were parasitized by more than one foundress. Clutch sizes of individual foundresses (average 9.99 +/- 0.51 SE) varied considerably between hosts. The time period during which offspring continued to emerge from a patch or host correlated strongly with foundress number, indicating that sequential rather than simultaneous parasitism is the more common. Genetic differentiation at the regional level between Germany and the Netherlands, as estimated by Slatkin's private allele method (0.11) and Hedrick's corrected G'(LT) (0.23), indicates significant substructuring between regions. The level of population inbreeding for the two localities (F(IL) = 0.168) fitted the expectation based on the average foundress number per patch.
Assuntos
Razão de Masculinidade , Vespas/genética , Animais , Comportamento Competitivo/fisiologia , Feminino , Genética Populacional , Genótipo , Alemanha , Masculino , Repetições de Microssatélites/genética , Países Baixos , Comportamento Sexual Animal/fisiologia , Vespas/fisiologiaRESUMO
Inbreeding depression is a central theme within genetics, and is of specific interest for researchers within evolutionary and conservation genetics and animal and plant breeding. Inbreeding effects are thought to be caused by the joint expression of conditional and unconditional deleterious alleles. Whenever the expression of deleterious alleles is conditional, this can result in extreme environmental sensitivity in certain inbred lineages. Analysis of conditional lethal effects can reveal some of the loci that are sensitive to inbreeding. We performed a QTL (quantitative trait locus) mapping study of inbreeding-related and conditionally expressed lethality in Drosophila melanogaster. The lethal effect was triggered by exposure to a cold shock. We used a North Carolina crossing Design 3 to establish the mapping population, as well as to estimate the average dominance ratio and heritability. We found two QTL on the major autosomes carrying recessive lethals that caused male mortality, one of which also affected female mortality. More detailed study of these loci will provide information on the mechanistic basis and environmental sensitivity of inbreeding depression.
Assuntos
Aclimatação , Temperatura Baixa , Drosophila melanogaster/genética , Endogamia , Locos de Características Quantitativas , Análise de Variância , Animais , Mapeamento Cromossômico , Cruzamentos Genéticos , Feminino , Genes Dominantes , Genes de Insetos , Genética Populacional , Longevidade , Masculino , Repetições de Microssatélites , Modelos Genéticos , FenótipoRESUMO
Uncertainty analysis for large-scale model studies is a challenging activity that requires a different approach to uncertainty analysis at a smaller scale. However, in river basin studies, the practice of uncertainty analysis at a large scale is mostly derived from practice at a small scale. The limitations and inherent subjectivity of some current practices and assumptions are identified, based on the results of a quantitative uncertainty analysis exploring the effects of input data and parameter uncertainty on surface water nutrient concentration. We show that: (i) although the results from small- scale sensitivity analysis are often applied at larger scales, this is not always valid; (ii) the current restriction of the uncertainty assessment to uncertainty types with a strong evidence base gives structurally conservative estimates; (iii) uncertainty due to bias is usually not assessed, but it may easily outweigh the effects of variability; (iv) the uncertainty bandwidth may increase for higher aggregation levels, although the opposite is the standard assumption.
Assuntos
Água Doce/análise , Modelos Teóricos , Medição de Risco/métodos , Medição de Risco/estatística & dados numéricos , Rios , Incerteza , Poluição da Água/análiseRESUMO
Among various other mechanisms, genetic differences in the production of reactive oxygen species are thought to underlie genetic variation for longevity. Here we report on possible changes in ROS production related processes in response to selection for divergent virgin lifespan in Drosophila. The selection lines were observed to differ significantly in dopamine levels and melanin pigmentation, which is associated with dopamine levels at eclosion. These findings confirm that variation in dopamine levels is associated with genetic variation for longevity. Dopamine has previously been implied in ROS production and in the occurrence of age-related neurodegenerative diseases. In addition, we propose a possible proximate mechanism by which dopamine levels affect longevity in Drosophila: We tested if increased dopamine levels were associated with a "rate-of-living" syndrome of increased activity and respiration levels, thus aggravating the level of oxidative stress. Findings on locomotor activity and oxygen consumption of short-lived flies were in line with expectations. However, the relation is not straightforward, as flies of the long-lived lines did not show any consistent differences in pigmentation or dopamine levels with respect to the control lines. Moreover, long-lived flies also had increased locomotor activity, but showed no consistent differences in respiration rate. This strongly suggests that the response for increased and decreased lifespan may be obtained by different mechanisms.
Assuntos
Dopamina/metabolismo , Longevidade/genética , Atividade Motora/genética , Seleção Genética , Animais , Dopamina/genética , Drosophila melanogaster , Melaninas/genética , Melaninas/metabolismo , Consumo de Oxigênio/genética , Pigmentação/genética , Espécies Reativas de Oxigênio/metabolismo , Especificidade da EspécieRESUMO
Investigations into the genetic basis of longevity variation have shown life span to be positively correlated with starvation resistance and negatively with female fecundity, both of which rely on lipid content. To assess the firmness of this relation, we assayed correlated responses in age-specific relative fat content (RFC) and starvation resistance in lines successfully selected for divergent virgin life span. We have previously demonstrated that genetic differentiation in female fecundity between our selection lines had disappeared during relaxation of selection. Therefore, we also expected genetic differences in lipid content and starvation resistance to have disappeared. However, RFC and starvation resistance were still significantly lower in short-lived flies than in control flies. Surprisingly, also in long-lived flies RFC and starvation resistance were mostly, but not invariably, found to be significantly lower than in control flies. These results indicate that the genetic correlation of RFC and starvation resistance with reproduction has broken down. Furthermore, the relationship between life span and starvation resistance appears to be more complex than previously anticipated. Also, we could demonstrate that differences in RFC were not brought about by differences in lipid accumulation during adult life, but were already present at eclosion. These findings suggest that pre-adult developmental pathways already impact on the rate of ageing of the adult fly.
Assuntos
Drosophila melanogaster/fisiologia , Privação de Alimentos , Lipídeos/análise , Seleção Genética , Animais , Peso Corporal , Drosophila melanogaster/química , Feminino , Longevidade , Masculino , ReproduçãoRESUMO
The relative fitnesses of the different Adh genotypes under normal laboratory conditions and in the absence of alcohol stress were estimated in Drosophila melanogaster according to Prout's method. The larval component (viability) did not reveal fitness differences between the genotypes but for the adult component significant differences were observed. The female adult component (fecundity) showed an overdominant pattern: both homozygous genotypes showed a relative fitness significantly lower than the heterozygous genotype. For the male adult component (virility) also differences were observed. The homozygous SS genotype showed a lower relative fitness than the other two genotypes. Predictions for gene frequency changes based on the estimated fitness values do show a reasonably good correspondence with frequency changes actually observed in a number of experimental cage populations and indicate a globally stable equilibrium around a frequency of the F allele of 0.40-0.70. The relevance of these fitness estimates, obtained under conditions with no alcohol stress, for the explanation of the Adh polymorphisms observed in nature is discussed.
Assuntos
Álcool Desidrogenase/genética , Drosophila melanogaster/genética , Polimorfismo Genético , Animais , Cruzamentos Genéticos , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Etanol/farmacologia , Feminino , Frequência do Gene , Técnicas Genéticas , Genótipo , Larva , Masculino , Matemática , Reprodução , Seleção GenéticaRESUMO
The specific genetic basis of inbreeding depression is poorly understood. To address this question, two conditionally expressed lethal effects that were found to cause line-specific life span reductions in two separate inbred lines of Drosophila melanogaster were characterized phenotypically and genetically in terms of whether the accelerated mortality effects are dominant or recessive. The mortality effect in one line (I4) is potentially a temperature-sensitive semilethal that expresses in adult males only and is partially dominant. The other line (I10) responds as one would expect for a recessive lethal. It requires a cold shock for expression and is cold sensitive. Flies exhibiting this lethal condition responded as pupae and freshly eclosed imagoes. The effect is recessive in both males and females. The expression of the lethal effects in both lines is highly dependent upon environmental conditions. These results will serve as a basis for more detailed and mechanistic genetic research on inbreeding depression and are relevant to sex- and environment-specific effects on life span observed in quantitative trait loci studies using inbred lines.
Assuntos
Drosophila melanogaster/fisiologia , Endogamia , Longevidade/genética , Mutação/genética , Temperatura , Animais , Drosophila melanogaster/genética , Feminino , Regulação da Expressão Gênica , Padrões de Herança/genética , Masculino , Fatores SexuaisRESUMO
For the degradation of DDT and other chlorohydrocarbon insecticides energy in the form of NADPH is needed which for the greater part is supplied by the pentose phosphate shunt. Therefore the influence of DDT on the polymorphism at the G6pd and Pgd loci in Drosophila melanogaster was investigated by studying its effect on egg to adult survival and adult survival. The results show the existence of significant differences in fitness between the different genotypes of the two loci for both components. It is found that the effect of DDT supplementation differs significantly from the effect of sodium octanoate addition. DDT treatment also increases the activity of the pentose phosphate shunt as measured by the activity of G6PD and 6PGD. In larvae a 50% increase in activity is found and in adults a 100% increase. As there is little doubt that the activities of G6PD and 6PGD are somehow correlated with the fitness of flies, the data are discussed in relation to the in vitro and in vivo differences in activity between the different allozymes of both G6PD and 6PGD.