RESUMO
Legumes play an important role in the soil nitrogen availability via symbiotic nitrogen fixation (SNF). Phosphate (Pi) deficiency severely impacts SNF because of the high Pi requirement of symbiosis. Whereas PHT1 transporters are involved in Pi uptake into nodules, it is unknown how Pi is transferred from the plant infected cells to nitrogen-fixing bacteroids. We hypothesized that Medicago truncatula genes homologous to Arabidopsis PHO1, encoding a vascular apoplastic Pi exporter, are involved in Pi transfer to bacteroids. Among the seven MtPHO1 genes present in M. truncatula, we found that two genes, namely MtPHO1.1 and MtPHO1.2, were broadly expressed across the various nodule zones in addition to the root vascular system. Expressions of MtPHO1.1 and MtPHO1.2 in Nicotiana benthamiana mediated specific Pi export. Plants with nodule-specific downregulation of both MtPHO1.1 and MtPHO1.2 were generated by RNA interference (RNAi) to examine their roles in nodule Pi homeostasis. Nodules of RNAi plants had lower Pi content and a three-fold reduction in SNF, resulting in reduced shoot growth. Whereas the rate of 33Pi uptake into nodules of RNAi plants was similar to control, transfer of 33Pi from nodule cells into bacteroids was reduced and bacteroids activated their Pi-deficiency response. Our results implicate plant MtPHO1 genes in bacteroid Pi homeostasis and SNF via the transfer of Pi from nodule infected cells to bacteroids.
Assuntos
Medicago truncatula/genética , Fixação de Nitrogênio/fisiologia , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/fisiologia , Nódulos Radiculares de Plantas/fisiologia , Sinorhizobium meliloti/fisiologia , Simbiose/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Fixação de Nitrogênio/genética , Nódulos Radiculares de Plantas/genética , Simbiose/genéticaRESUMO
Hereditary haemochromatosis, one of the most common genetic disorders in the United States, can produce systemic iron deposition leading to end-organ failure and death if untreated. The diagnosis of this condition can be challenging as elevated serum ferritin may be seen in a variety of conditions, including acute and chronic liver disease, a range of systemic inflammatory states, and both primary and secondary iron overload syndromes. Appropriate and timely diagnosis of haemochromatosis is paramount as simple interventions, such as phlebotomy, can prevent or reverse organ damage from iron overload. The recognition of other aetiologies of elevated ferritin is also vital to ensure that appropriate intervention is provided and phlebotomy only utilized in patients who require it. In this review, we summarize the existing data on the work up and management of hereditary haemochromatosis and present a practical algorithm for the diagnosis and management of this disease.
Assuntos
Hemocromatose/diagnóstico , Hemocromatose/terapia , Humanos , Programas de Rastreamento , Flebotomia/métodosRESUMO
Fat malabsorption associated with Roux-en-Y gastric bypass (RYGB) may contribute to elevated postprandial glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) after the procedure, leading to sustained weight loss and appetite reduction. This study investigated whether fat malabsorption via orlistat increases GLP-1 and PYY and if these increases would be proportional to changes in hunger and satiety. Five healthy participants received standardized meals with 120 mg orlistat or placebo in a randomized, double-blinded, crossover design for 3 days. On the final day, glucose, insulin, GLP-1, PYY3-36 and visual analogue scores for hunger and satiety were measured over a 14-hour period that included three meals. Fasting, 14-hour area under the curve (AUC) and meal-related AUC for glucose and insulin were similar, although postprandial increases in peak insulin and glucose were greater with orlistat. PYY3-36 , GLP-1, hunger and satiety were not different. In conclusion, short-term orlistat administration does not enhance postprandial GLP-1 or PYY3-36 or affect hunger or satiety in normal-weight individuals. Furthermore, fat malabsorption from RYGB is unlikely to mediate subsequent postprandial increases in GLP-1 and PYY.
Assuntos
Peptídeo 1 Semelhante ao Glucagon , Peptídeo YY , Humanos , Fome , Lipase , Período Pós-PrandialAssuntos
Microangiopatias Trombóticas , Adulto , Biópsia , Eritrócitos Anormais/metabolismo , Eritrócitos Anormais/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Microangiopatias Trombóticas/sangue , Microangiopatias Trombóticas/diagnóstico , Microangiopatias Trombóticas/patologiaRESUMO
Intussusception secondary to Meckel's diverticulum is a rare entity in adults and hence, can be a challenging to accurately diagnose preoperatively. This case illustrates the clinical, imaging, operative, and histologic manifestations of a Meckel's diverticulum leading to a long segment ileo-ileal intussusception in an adult female patient presenting with symptoms of small bowel obstruction.
RESUMO
The ß5 subunit of the proteasome has been shown in worms and in human cell lines to be regulatory. In these models, ß5 overexpression results in upregulation of the entire proteasome complex which is sufficient to increase proteotoxic stress resistance, improve metabolic parameters, and increase longevity. However, fundamental questions remain unanswered, including the temporal requirements for ß5 overexpression and whether ß5 overexpression can extend lifespan in other species. To determine if adult-only overexpression of the ß5 subunit can increase proteasome activity in a different model, we characterized phenotypes associated with ß5 overexpression in Drosophila melanogaster adults. We find that adult-only overexpression of the ß5 subunit does not result in transcriptional upregulation of the other subunits of the proteasome as they do in nematodes and human cell culture. Despite this lack of a regulatory role, boosting ß5 expression increases the chymotrypsin-like activity associated with the proteasome, reduces both the size and number of ubiquitinated protein aggregates in aged flies, and increases longevity. Surprisingly, these phenotypes were not associated with increased resistance to acute proteotoxic insults or improved metabolic parameters.
Assuntos
Envelhecimento/genética , Proteínas de Drosophila/genética , Complexo de Endopeptidases do Proteassoma/genética , Proteostase/genética , Envelhecimento/patologia , Animais , Linhagem Celular , Citoplasma/genética , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos , Longevidade/genética , Longevidade/fisiologia , Estresse Oxidativo/genética , Proteostase/fisiologiaRESUMO
Multigenic families of Plant Defensin type 1 (PDF1) have been described in several species, including the model plant Arabidopsis thaliana as well as zinc tolerant and hyperaccumulator A. halleri. In A. thaliana, PDF1 transcripts (AtPDF1) accumulate in response to pathogen attack following synergic activation of ethylene/jasmonate pathways. However, in A. halleri, PDF1 transcripts (AhPDF1) are constitutively highly accumulated. Through an evolutionary approach, we investigated the possibility of A. halleri or A. thaliana species specialization in different PDF1s in conveying zinc tolerance and/or the response to pathogen attack via activation of the jasmonate (JA) signaling pathway. The accumulation of each PDF1 from both A. halleri and A. thaliana was thus compared in response to zinc excess and MeJA application. In both species, PDF1 paralogues were barely or not at all responsive to zinc. However, regarding the PDF1 response to JA signaling activation, A. thaliana had a higher number of PDF1s responding to JA signaling activation. Remarkably, in A. thaliana, a slight but significant increase in zinc tolerance was correlated with activation of the JA signaling pathway. In addition, A. halleri was found to be more tolerant to the necrotrophic pathogen Botrytis cinerea than A. thaliana. Since PDF1s are known to be promiscuous antifungal proteins able to convey zinc tolerance, we propose, on the basis of the findings of this study, that high constitutive PDF1 transcript accumulation in A. halleri is a potential way to skip the JA signaling activation step required to increase the PDF1 transcript level in the A. thaliana model species. This could ultimately represent an adaptive evolutionary process that would promote a PDF1 joint effect on both zinc tolerance and the response to pathogens in the A. halleri extremophile species.