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RESEARCH QUESTION: Does double blastocyst vitrification and warming affect pregnancy, miscarriage or live birth rates, or birth outcomes, from embryos that have undergone preimplantation genetic testing for aneuploidies (PGT-A) testing? DESIGN: This retrospective observational analysis of embryo transfers was performed at a single centre between January 2017 and August 2022. The double-vitrification group included frozen blastocysts that were vitrified after 5-7 days of culture, warmed, biopsied (either once or twice) and re-vitrified. The single vitrification (SV) group included fresh blastocysts that were biopsied at 5-7 days and then vitrified. RESULTS: A comparison of the 84 double-vitrification blastocysts and 729 control single-vitrification blastocysts indicated that the double-vitrification embryos were frozen later in development and had expanded more than the single-vitrification embryos. Of the 813 embryo transfer procedures reported, 452 resulted in the successful delivery of healthy infants (56%). There were no significant differences between double-vitrification and single-vitrification embryos in the pregnancy, miscarriage or live birth rates achieved after single-embryo transfer (55% versus 56%). Logistic regression indicated that while reduced live birth rates were associated with increasing maternal age at oocyte collection, longer culture prior to freezing and lower embryo quality, double vitrification was not a significant predictor of live birth rate. CONCLUSIONS: Blastocyst double vitrification was not shown to impact pregnancy, miscarriage or live birth rates. Although caution is necessary due to the study size, no effects of double vitrification on miscarriage rates, birthweight or gestation period were noted. These data offer reassurance given the absence of the influence of double vitrification on all outcomes after PGT-A.
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Aborto Espontâneo , Coeficiente de Natalidade , Blastocisto , Criopreservação , Transferência Embrionária , Vitrificação , Humanos , Feminino , Gravidez , Estudos Retrospectivos , Adulto , Aborto Espontâneo/epidemiologia , Transferência Embrionária/métodos , Taxa de Gravidez , Nascido Vivo , Resultado da GravidezRESUMO
AIM: To explore self-reported dentofacial trauma and their potential endodontic sequelae in boxers using a questionnaire, followed by clinical and radiographic assessment to (1) compare the nature and number of self-reported dentofacial injuries with physical evidence of injury sequelae; and (2) investigate potential risk factors influencing dentofacial trauma and their endodontic sequelae. METHODOLOGY: A focus group validated questionnaire was completed by 176 boxers recruited from 16 London boxing clubs; 61 boxers from this cohort then attended a London dental hospital, for a clinical and radiographic assessment. Data from the questionnaire and clinical assessments were then collated and analysed using Chi-squared or t-tests. RESULTS: Questionnaire data revealed 87.5% of boxers reported a history of dentofacial trauma during boxing activity. The clinical and radiographic assessment detected evidence of dentofacial trauma in 91.8% of boxers and dental injury or endodontic-related injury sequelae in 68.9% of boxers. There was a significant association between dentofacial trauma and boxers who did not participate in weekly neck weight sessions (p < .001), and there was a significant association between trauma-related endodontic sequelae and: boxer age (p = .01); competitions per month (p = .002); and defensive skill (p = .007). CONCLUSIONS: A majority of the cohort had suffered dentofacial injuries and endodontic sequelae. The questionnaire data under-reported musculoskeletal injuries and endodontic sequelae, suggesting that some hard-tissue injuries following repetitive dentofacial trauma may have a subclinical presentation. Injury risk may be related to increased boxer age, defensive skills, frequency of participation in competitions, and frequency of neck weight sessions per week.
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In porcine in vitro production (IVP) systems, the use of oocytes derived from prepubertal gilts, whilst being commercially attractive, remains challenging due to their poor developmental competence following in vitro maturation (IVM). Follicular fluid contains important growth factors and plays a key role during oocyte maturation; therefore, it is a common supplementation for porcine IVM medium. However, follicular fluid contains many poorly characterized components, is batch variable, and its use raises biosecurity concerns. In an effort to design a defined IVM system, growth factors such as cytokines have been previously tested. These include leukaemia inhibitory factor (LIF), fibroblast growth factor 2 (FGF2), and insulin-like growth factor 1 (IGF1), the combination of which is termed 'FLI'. Here, using abattoir-derived oocytes in a well established porcine IVP system, we compared follicular fluid and FLI supplementation during both IVM and embryo culture to test the hypothesis that FLI can substitute for follicular fluid without compromising oocyte nuclear and cytoplasmic maturation. We demonstrate that in oocytes derived from prepubertal gilts, FLI supplementation enhances oocyte meiotic maturation and has a positive effect on the quality and developmental competence of embryos. Moreover, for the first time, we studied the effects of follicular fluid and FLI combined showing no synergistic effects.
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Fator 2 de Crescimento de Fibroblastos , Fator de Crescimento Insulin-Like I , Suínos , Animais , Feminino , Fator 2 de Crescimento de Fibroblastos/farmacologia , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fator Inibidor de Leucemia/farmacologia , Fator Inibidor de Leucemia/metabolismo , Fator de Crescimento Insulin-Like I/farmacologia , Oócitos , Sus scrofa , Suplementos Nutricionais , Técnicas de Maturação in Vitro de Oócitos , Fertilização in vitroRESUMO
BACKGROUND: The nematode Caenorhabditis elegans has been extensively used to explore the relationships between complex traits, genotypes, and environments. Complex traits can vary across different genotypes of a species, and the genetic regulators of trait variation can be mapped on the genome using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) derived from genetically and phenotypically divergent parents. Most RILs have been derived from crossing two parents from globally distant locations. However, the genetic diversity between local C. elegans populations can be as diverse as between global populations and could thus provide means of identifying genetic variation associated with complex traits relevant on a broader scale. RESULTS: To investigate the effect of local genetic variation on heritable traits, we developed a new RIL population derived from 4 parental wild isolates collected from 2 closely located sites in France: Orsay and Santeuil. We crossed these 4 genetically diverse parental isolates to generate a population of 200 multi-parental RILs and used RNA-seq to obtain sequence polymorphisms identifying almost 9000 SNPs variable between the 4 genotypes with an average spacing of 11 kb, doubling the mapping resolution relative to currently available RIL panels for many loci. The SNPs were used to construct a genetic map to facilitate QTL analysis. We measured life history traits such as lifespan, stress resistance, developmental speed, and population growth in different environments, and found substantial variation for most traits. We detected multiple QTLs for most traits, including novel QTLs not found in previous QTL analysis, including those for lifespan and pathogen responses. This shows that recombining genetic variation across C. elegans populations that are in geographical close proximity provides ample variation for QTL mapping. CONCLUSION: Taken together, we show that using more parents than the classical two parental genotypes to construct a RIL population facilitates the detection of QTLs and that the use of wild isolates facilitates the detection of QTLs. The use of multi-parent RIL populations can further enhance our understanding of local adaptation and life history trade-offs.
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Caenorhabditis elegans/genética , Características de História de Vida , Locos de Características Quantitativas , Animais , Mapeamento Cromossômico , Ligação Genética , Genótipo , Organismos Geneticamente ModificadosRESUMO
BACKGROUND: Accumulation of protein aggregates are a major hallmark of progressive neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. Transgenic Caenorhabditis elegans nematodes expressing the human synaptic protein α-synuclein in body wall muscle show inclusions of aggregated protein, which affects similar genetic pathways as in humans. It is not however known how the effects of α-synuclein expression in C. elegans differs among genetic backgrounds. Here, we compared gene expression patterns and investigated the phenotypic consequences of transgenic α-synuclein expression in five different C. elegans genetic backgrounds. RESULTS: Transcriptome analysis indicates that α-synuclein expression effects pathways associated with nutrient storage, lipid transportation and ion exchange and that effects vary depending on the genetic background. These gene expression changes predict that a range of phenotypes will be affected by α-synuclein expression. We confirm this, showing that α-synuclein expression delayed development, reduced lifespan, increased rate of matricidal hatching, and slows pharyngeal pumping. Critically, these phenotypic effects depend on the genetic background and coincide with the core changes in gene expression. CONCLUSIONS: Together, our results show genotype-specific effects and core alterations in both gene expression and in phenotype in response to α-synuclein expression. We conclude that the effects of α-synuclein expression are substantially modified by the genetic background, illustrating that genetic background needs to be considered in C. elegans models of neurodegenerative disease.
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Caenorhabditis elegans/genética , Fenótipo , Transcrição Gênica , alfa-Sinucleína/genética , Animais , Caenorhabditis elegans/efeitos dos fármacos , Expressão Gênica , Perfilação da Expressão Gênica , alfa-Sinucleína/toxicidadeRESUMO
BACKGROUND: Neurodegenerative diseases (NGDs) such as Alzheimer's and Parkinson's are debilitating and largely untreatable conditions strongly linked to age. The clinical, neuropathological, and genetic components of NGDs indicate that neurodegeneration is a complex trait determined by multiple genes and by the environment. MAIN BODY: The symptoms of NGDs differ among individuals due to their genetic background, and this variation affects the onset and progression of NGD and NGD-like states. Such genetic variation affects the molecular and cellular processes underlying NGDs, leading to differential clinical phenotypes. So far, we have a limited understanding of the mechanisms of individual background variation. Here, we consider how variation between genetic backgrounds affects the mechanisms of aging and proteostasis in NGD phenotypes. We discuss how the nematode Caenorhabditis elegans can be used to identify the role of variation between genetic backgrounds. Additionally, we review advances in C. elegans methods that can facilitate the identification of NGD regulators and/or networks. CONCLUSION: Genetic variation both in disease genes and in regulatory factors that modulate onset and progression of NGDs are incompletely understood. The nematode C. elegans represents a valuable system in which to address such questions.
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Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Modelos Animais de Doenças , Variação Genética , Doenças Neurodegenerativas/genética , Animais , Caenorhabditis elegans/metabolismo , Humanos , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , FenótipoRESUMO
Developmental decisions are important in organismal fitness. For the nematode Caenorhabditis elegans, which is naturally found in the ephemeral food patches formed by rotting plant material, correctly committing to dauer or non-dauer larval development is key to genotype survival. To investigate the link between reproductive traits, which will determine how populations grow, and dauer larvae formation, we have analysed these traits in mutation accumulation lines of C. elegans. We find that reproductive traits of individual worms-the total number of progeny and the timing of progeny production-are highly correlated with the population size observed in growing populations. In contrast, we find no relationship between reproduction traits and the number of dauer larvae observed in growing populations. We also do not observe a mutational bias in dauer larvae formation. These results indicate that the control of dauer larvae formation is distinct from the control of reproduction and that differences in dauer larvae formation can evolve rapidly.
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Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/genética , Adaptação Biológica , Animais , Caenorhabditis elegans/fisiologia , Meio Ambiente , Larva/crescimento & desenvolvimento , Acúmulo de MutaçõesRESUMO
The placebo effect is widely recognized but important questions remain, for example whether the capacity to respond to a placebo is an evolved, and potentially ubiquitous trait, or an unpredictable side effect of another evolved process. Understanding this will determine the degree to which the physiology underlying placebo effects might be manipulated or harnessed to optimize medical treatments. We argue that placebo effects are cases of phenotypic plasticity where once predictable cues are now unpredictable. Importantly, this explains why placebo-like effects are observed in less complex organisms such as worms and flies. Further, this indicates that such species present significant opportunities to test hypotheses that would be ethically or pragmatically impossible in humans. This paradigm also suggests that data informative of human placebo effects pre-exist in studies of model organisms.
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Sinais (Psicologia) , Efeito Placebo , Animais , Variação Biológica da População , Humanos , Modelos AnimaisRESUMO
BACKGROUND: Convulsive status epilepticus (CSE) is the most common life-threatening childhood neurological emergency. Despite this, there is a lack of high quality evidence supporting medication use after first line benzodiazepines, with current treatment protocols based solely on non-experimental evidence and expert opinion. The current standard of care, phenytoin, is only 60% effective, and associated with considerable adverse effects. A newer anti-convulsant, levetiracetam, can be given faster, is potentially more efficacious, with a more tolerable side effect profile. The primary aim of the study presented in this protocol is to determine whether intravenous (IV) levetiracetam or IV phenytoin is the better second line treatment for the emergency management of CSE in children. METHODS/DESIGN: 200 children aged between 3 months and 16 years presenting to 13 emergency departments in Australia and New Zealand with CSE, that has failed to stop with first line benzodiazepines, will be enrolled into this multicentre open randomised controlled trial. Participants will be randomised to 40 mg/kg IV levetiracetam infusion over 5 min or 20 mg/kg IV phenytoin infusion over 20 min. The primary outcome for the study is clinical cessation of seizure activity five minutes following the completion of the infusion of the study medication. Blinded confirmation of the primary outcome will occur with the primary outcome assessment being video recorded and assessed by a primary outcome assessment team blinded to treatment allocation. Secondary outcomes include: Clinical cessation of seizure activity at two hours; Time to clinical seizure cessation; Need for rapid sequence induction; Intensive care unit (ICU) admission; Serious adverse events; Length of Hospital/ICU stay; Health care costs; Seizure status/death at one-month post discharge. DISCUSSION: This paper presents the background, rationale, and design for a randomised controlled trial comparing levetiracetam to phenytoin in children presenting with CSE in whom benzodiazepines have failed. This study will provide the first high quality evidence for management of paediatric CSE post first-line benzodiazepines. TRIAL REGISTRATION: Prospectively registered with the Australian and New Zealand Clinical Trial Registry (ANZCTR): ACTRN12615000129583 (11/2/2015). UTN U1111-1144-5272. ConSEPT protocol version 4 (12/12/2014).
Assuntos
Anticonvulsivantes/uso terapêutico , Fenitoína/uso terapêutico , Piracetam/análogos & derivados , Estado Epiléptico/tratamento farmacológico , Adolescente , Criança , Pré-Escolar , Protocolos Clínicos , Emergências , Serviço Hospitalar de Emergência , Feminino , Seguimentos , Humanos , Lactente , Infusões Intravenosas , Levetiracetam , Masculino , Piracetam/uso terapêutico , Estudos Prospectivos , Método Simples-Cego , Resultado do TratamentoRESUMO
BACKGROUND: Signalling pathways underlie development, behaviour and pathology. To understand patterns in the evolution of signalling pathways, we undertook a comprehensive investigation of the pathways that control the switch between growth and developmentally quiescent dauer in 24 species of nematodes spanning the phylum. RESULTS: Our analysis of 47 genes across these species indicates that the pathways and their interactions are not conserved throughout the Nematoda. For example, the TGF-ß pathway was co-opted into dauer control relatively late in a lineage that led to the model species Caenorhabditis elegans. We show molecular adaptations described in C. elegans that are restricted to its genus or even just to the species. Similarly, our analyses both identify species where particular genes have been lost and situations where apparently incorrect orthologues have been identified. CONCLUSIONS: Our analysis also highlights the difficulties of working with genome sequences from non-model species as reliance on the published gene models would have significantly restricted our understanding of how signalling pathways evolve. Our approach therefore offers a robust standard operating procedure for genomic comparisons.
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Evolução Biológica , Regulação da Expressão Gênica , Nematoides/genética , Nematoides/metabolismo , Animais , Biomarcadores , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Análise por Conglomerados , Perfilação da Expressão Gênica , Ligantes , Nematoides/classificação , Filogenia , Ligação Proteica , Transdução de SinaisRESUMO
Sarcopenia, a gradual decrease in skeletal muscle mass and strength, is a major component of frailty in the elderly, with age, (lack of) exercise and diet found to be the major risk factors. The nematode Caenorhabditis elegans is an important model of sarcopenia. Although many studies describe loss of muscle function in ageing C. elegans, surprisingly few report on the loss of muscle mass. Here, in order to quantify loss of muscle mass under various dietary restriction (DR) conditions, we used an internal GFP standard to determine levels of the major body wall muscle myosin (UNC-54) in transgenic unc-54::gfp worms over their lifespan. Myosin density linearly increased during the first week of adulthood and there was no significant effect of DR. In contrast, an exponential decrease in myosin density was seen during the second week of adulthood, with reduced rates of myosin loss for mild and medium DR compared to control. UNC-54 turnover rates, previously determined using pulse-labelling methods, correspond well with the t1/2 value found here for UNC-54-GFP using fluorescence (control t1/2 = 12.0 days), independently validating our approach. These data indicate that sarcopenia is delayed in worms under mild and medium DR due to a reduced rate of myosin UNC-54 degradation, thereby maintaining protein homeostasis.
Assuntos
Proteínas de Caenorhabditis elegans , Sarcopenia , Animais , Humanos , Adulto , Idoso , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Miosinas/metabolismo , Animais Geneticamente Modificados/metabolismoRESUMO
The study of pig preimplantation embryo development has several potential uses: from agriculture to the production of medically relevant genetically modified organisms and from rare breed conservation to acting as a physiologically relevant model for progressing human and other (e.g., endangered) species' in vitro fertilisation technology. Despite this, barriers to the widespread adoption of pig embryo in vitro production include lipid-laden cells that are hard to visualise, slow adoption of contemporary technologies such as the use of time-lapse incubators or artificial intelligence, poor blastulation and high polyspermy rates. Here, we employ a commercially available time-lapse incubator to provide a comprehensive overview of the morphokinetics of pig preimplantation development for the first time. We tested the hypotheses that (a) there are differences in developmental timings between blastulating and non-blastulating embryos and (b) embryo developmental morphokinetic features can be used to predict the likelihood of blastulation. The abattoir-derived oocytes fertilised by commercial extended semen produced presumptive zygotes were split into two groups: cavitating/blastulating 144 h post gamete co-incubation and those that were not. The blastulating group reached the 2-cell and morula stages significantly earlier, and the time taken to reach the 2-cell stage was identified to be a predictive marker for blastocyst formation. Reverse cleavage was also associated with poor blastulation. These data demonstrate the potential of morphokinetic analysis in automating and upscaling pig in vitro production through effective embryo selection.
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Cryopreservation of both gametes and embryos, both for storage and for the preservation of their developmental capacity is a critical aspect of assisted reproductive technology. The survival of reproductive material following cryopreservation protocols is not only vital to clinical applications in the human in vitro fertilisation clinic, but is also important in the in vitro production of livestock embryos. The ability to routinely cryopreserve oocytes and embryos of livestock species has the potential to improve animal welfare, reduce environmental impact, and reduce the associated costs for breeding companies through the reduction of live animal transportation. Unfortunately, frozen oocytes and embryos are regularly documented to contain a higher proportion of apoptotic cells compared to their non-frozen counterparts, with freezing procedures thought to trigger apoptotic pathways of cell death. Comparisons between frozen and non-frozen samples also show changes in the gene expression of apoptotic factors such as Bcl-2 and Bax in response to cryopreservation. Apoptotic inhibition has the potential to improve cryosurvival, and how to achieve this is subject to debate. Here, we review how exposure to low temperatures during cryopreservation may be responsible for the abnormal activation of apoptotic pathways in mammalian oocytes and embryos, and discuss the ways in which they can be influenced to improve cryopreservation protocols, particularly in agriculturally important species.
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Criopreservação , Embrião de Mamíferos , Animais , Apoptose , Criopreservação/veterinária , Fertilização in vitro/veterinária , OócitosRESUMO
The aim of this paper is to provide guidelines on how to report a small volume cone beam computed tomography (CBCT) scan.
Assuntos
Tomografia Computadorizada de Feixe Cônico Espiral , Tomografia Computadorizada de Feixe CônicoRESUMO
Eukaryotic cells respond to hypothermic stress through a series of regulatory mechanisms that preserve energy resources and prolong cell survival. These mechanisms include alterations in gene expression, attenuated global protein synthesis and changes in the lipid composition of the phospholipid bilayer. Cellular responses to hyperthermia, hypoxia, nutrient deprivation and oxidative stress have been comprehensively investigated, but studies of the cellular response to cold stress are more limited. Responses to cold stress are however of great importance both in the wild, where exposure to low and fluctuating environmental temperatures is common, and in medical and biotechnology settings where cells and tissues are frequently exposed to hypothermic stress and cryopreservation. This means that it is vitally important to understand how cells are impacted by low temperatures and by the decreases and subsequent increases in temperature associated with cold stress. Here, we review the ways in which eukaryotic cells respond to hypothermic stress and how these compare to the well-described and highly integrated stress response systems that govern the cellular response to other types of stress.
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Eucariotos/fisiologia , Hipotermia/fisiopatologia , Estresse Fisiológico , Animais , Membrana Celular/metabolismo , Humanos , Hipóxia/fisiopatologia , Estresse OxidativoRESUMO
Different genetic backgrounds can modify the effect of mutated genes. Human α-synuclein (SNCA) gene encodes α-synuclein, and its oligomeric complexes accumulate with age and mediate the disruption of cellular homeostasis, resulting in the neuronal death that is characteristic of Parkinson's Disease. Polymorphic variants modulate this complex pathologic mechanism. Previously, we constructed five transgenic introgression lines of a Caenorhabditis elegans model of α-synuclein using genetic backgrounds that are genetically diverse from the canonical wild-type Bristol N2. A gene expression analysis revealed that the α-synuclein transgene differentially affects genome-wide transcription due to background modifiers. To further investigate how complex traits are affected in these transgenic lines, we measured the α-synuclein transgene expression, the overall accumulation of the fusion protein of α-synuclein and yellow fluorescent protein (YFP), the lysosome-related organelles, and the body size. By using quantitative PCR (qPCR), we demonstrated stable and similar expression levels of the α-synuclein transgene in different genetic backgrounds. Strikingly, we observed that the levels of the a-synuclein:YFP fusion protein vary in different genetic backgrounds by using the COPAS™ biosorter. The quantification of the Nile Red staining assay demonstrates that α-synuclein also affects lysosome-related organelles and body size. Our results show that the same α-synuclein introgression in different C. elegans backgrounds can produces differing effects on complex traits due to background modifiers.
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Lisossomos/genética , Doença de Parkinson/genética , Transcrição Gênica , alfa-Sinucleína/genética , Animais , Animais Geneticamente Modificados/genética , Proteínas de Bactérias/genética , Tamanho Corporal/genética , Caenorhabditis elegans/genética , Modelos Animais de Doenças , Regulação da Expressão Gênica , Variação Genética/genética , Genoma/genética , Humanos , Proteínas Luminescentes/genética , Lisossomos/metabolismo , Herança Multifatorial/genética , Doença de Parkinson/patologiaRESUMO
BACKGROUND: The free-living nematode Caenorhabditis elegans makes a developmental decision based on environmental conditions: larvae either arrest as dauer larva, or continue development into reproductive adults. There is natural variation among C. elegans lines in the sensitivity of this decision to environmental conditions; that is, there is variation in the phenotypic plasticity of dauer larva development. We hypothesised that these differences may be transcriptionally controlled in early stage larvae. We investigated this by microarray analysis of different C. elegans lines under different environmental conditions, specifically the presence and absence of dauer larva-inducing pheromone. RESULTS: There were substantial transcriptional differences between four C. elegans lines under the same environmental conditions. The expression of approximately 2,000 genes differed between genetically different lines, with each line showing a largely line-specific transcriptional profile. The expression of genes that are markers of larval moulting suggested that the lines may be developing at different rates. The expression of a total of 89 genes was putatively affected by dauer larva or non-dauer larva-inducing conditions. Among the upstream regions of these genes there was an over-representation of DAF-16-binding motifs. CONCLUSION: Under the same environmental conditions genetically different lines of C. elegans had substantial transcriptional differences. This variation may be due to differences in the developmental rates of the lines. Different environmental conditions had a rather smaller effect on transcription. The preponderance of DAF-16-binding motifs upstream of these genes was consistent with these genes playing a key role in the decision between development into dauer or into non-dauer larvae. There was little overlap between the genes whose expression was affected by environmental conditions and previously identified loci involved in the plasticity of dauer larva development.
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Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/genética , Regulação da Expressão Gênica no Desenvolvimento , Expressão Gênica , Animais , Sequência de Bases , Sítios de Ligação , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Fatores de Transcrição Forkhead , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Species that exploit transient food patches must both effectively utilize such food sources and colonize new patches. The timing and rate of dispersal from existing patches and adaptations that aid dispersal are therefore crucial. Currently, no system exists in which dispersal has been investigated at both the ecological and genetic levels. The extensively studied model nematode Caenorhabditis elegans is potentially such a system. Dispersal between food patches in C. elegans has been found to be related to polymorphism in the npr-1 gene, which regulates the tendency of worms to aggregate on food. Here I show that this non-dauer larval dispersal is affected by various environmental variables and that variation is not fully explained by differences in aggregation behavior. Quantitative trait loci mapping identifies candidate genomic regions, separate to npr-1, which affect variation in dispersal between two isolates. These data suggest that the ecology of C. elegans is more complex than previously thought, but indicate that it is experimentally tractable.
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Caenorhabditis elegans/fisiologia , Comportamento Alimentar/fisiologia , Larva/fisiologia , Polimorfismo Genético , Animais , Proteínas de Caenorhabditis elegans/genética , Meio Ambiente , Comportamento Alimentar/efeitos dos fármacos , Feromônios/farmacologia , Locos de Características Quantitativas , Receptores de Neuropeptídeo Y/genéticaRESUMO
Total synaptonemal complex (SC) lengths were estimated from Oreochromis aureus Steindachner (which has a WZ/ZZ sex determination system), O. mossambicus Peters and O. niloticus L. (both of which have XX/XY sex determination systems). The total SC length in oocytes was greater than that in spermatocytes in all three species (194 +/- 30 microm and 134 +/- 13 microm, 187 +/- 22 microm and 127 +/- 17 microm, 193 +/- 37 microm and 144 +/- 19 microm, respectively). These sex-specific differences did not appear to be influenced by the type of sex determination system (the female/male total SC length ratio was 1.45 in O. aureus, 1.47 in O. mossambicus and 1.34 in O. niloticus) and do not correlate with the lack of any overall sex-specific length differences in the current Oreochromis linkage map. Although based on data from relatively few species, there appears to be no consistent relationship between sex-specific SC lengths and linkage map lengths in fish. Neomale (hormonally masculinized genetic female) O. aureus and O. mossambicus had total SC lengths of 138 +/- 13 microm and 146 +/- 13 microm respectively, more similar to normal males than to normal females. These findings agree with data from other vertebrate species that suggest that phenotypic sex, rather than genotype, determines traits such as total SC length, chiasmata position and recombination pattern, at least for the autosomes.