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Pneumonia is a common comorbidity in patients with severe traumatic brain injury (TBI), and is associated with increased morbidity and mortality. In this study, we established a model of intratracheal Klebsiella pneumoniae administration in young adult male and female mice, at 4 days following an experimental TBI, to investigate how K. pneumoniae infection influences acute post-TBI outcomes. A dose-response curve determined the optimal dose of K. pneumoniae for inoculation (1 x 10^6 colony forming units), and administration at 4 days post-TBI resulted in transient body weight loss and sickness behaviors (hypoactivity and acute dyspnea). K. pneumoniae infection led to an increase in pro-inflammatory cytokines in serum and bronchoalveolar lavage fluid at 24 h post-infection, in both TBI and sham (uninjured) mice. By 7 days, when myeloperoxidase + neutrophil numbers had returned to baseline in all groups, lung histopathology was observed with an increase in airspace size in TBI + K. pneumoniae mice compared to TBI + vehicle mice. In the brain, increased neuroinflammatory gene expression was observed acutely in response to TBI, with an exacerbated increase in Ccl2 and Hmox1 in TBI + K. pneumoniae mice compared to either TBI or K. pneumoniae alone. However, the presence of neuroinflammatory immune cells in the injured brain, and the extent of damage to cortical and hippocampal brain tissue, was comparable between K. pneumoniae and vehicle-treated mice by 7 days. Examination of the fecal microbiome across a time course did not reveal any pronounced effects of either injury or K. pneumoniae on bacterial diversity or abundance. Together, these findings demonstrate that K. pneumoniae lung infection after TBI induces an acute and transient inflammatory response, primarily localized to the lungs with some systemic effects. However, this infection had minimal impact on secondary injury processes in the brain following TBI. Future studies are needed to evaluate the potential longer-term consequences of this dual-hit insult.
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Lesões Encefálicas Traumáticas , Modelos Animais de Doenças , Infecções por Klebsiella , Klebsiella pneumoniae , Camundongos Endogâmicos C57BL , Animais , Lesões Encefálicas Traumáticas/microbiologia , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/patologia , Camundongos , Infecções por Klebsiella/patologia , Infecções por Klebsiella/microbiologia , Feminino , Masculino , Citocinas/metabolismo , Líquido da Lavagem BroncoalveolarRESUMO
Pyrazine carbohydrazide based hydrazones were synthesized starting from 5-methylpyrazine-2-carboxylic acid. The acid was first converted to its methyl ester, which on further treatment with hydrazine hydrate transformed to carbohydrazide. The carbohydrazide was treated with differently substituted aromatic carbonyl compounds giving hydrazones. Characterization of the synthesized compounds was carried out using modern spectroscopic techniques and unambiguously confirmed through X-ray crystallographic studies of compound 3d. The purity of the compounds was verified using elemental analysis. The target molecules were evaluated for urease inhibition, antioxidant and antimicrobial activity.
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Desenho de Fármacos , Hidrazinas/síntese química , Hidrazinas/farmacologia , Hidrazonas/síntese química , Hidrazonas/farmacologia , Pirazinas/síntese química , Pirazinas/farmacologia , Anti-Infecciosos/síntese química , Anti-Infecciosos/farmacologia , Antioxidantes/síntese química , Antioxidantes/farmacologia , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Cristalografia por Raios X , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Espectrometria de Massas , Modelos Moleculares , Estrutura Molecular , Espectroscopia de Prótons por Ressonância Magnética , Espectrofotometria Infravermelho , Relação Estrutura-Atividade , Urease/antagonistas & inibidores , Urease/metabolismoRESUMO
Adipose tissue, both intricate and fundamental to physiological functions, comprises cell types, including adipocytes, pivotal in secreting bioactive peptides known as 'adipokines.' Apelin (APLN), Visfatin (VSFTN), and Irisin (IRSN) are novel adipokines involved in regulating energy, carbohydrate, protein, and lipid metabolism. APLN acts as an endogenous ligand for G-protein-coupled receptors, VSFTN is essential in nicotinamide adenine dinucleotide (NAD) biosynthesis, and IRSN is released from skeletal muscle and adipose tissues. Their influence spans various physiological domains, including insulin resistance and sensitivity, cardiovascular functions, angiogenesis, and reproductive systems. This review focuses on the potential roles of APLN, VSFTN, and IRSN in energy regulation mechanisms related to farm animal production. Despite accumulating evidence of their significance, comprehensive understanding is still emerging, with most studies based on model organisms. Thus, there's a pressing need for targeted research on farm animals. Addressing these knowledge gaps could pave the way for improved health strategies, reproductive efficiency, and productivity in farm animals. Future research should focus on understanding the multifaceted interactions of these adipokines and their implications for promoting sustainable and effective animal production.
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Exaggeration of type 2 immune responses promotes lung inflammation and altered lung development; however, eosinophils, despite expansion in the postnatal lung, have not been specifically assessed in the context of neonatal lung disease. Furthermore, early life factors including prematurity and respiratory infection predispose infants to chronic obstructive pulmonary disease later in life. To assess eosinophils in the developing lung and how they may contribute to chronic lung disease, we generated mice harboring eosinophil-specific deletion of the negative regulatory enzyme SH2 domain-containing inositol 5' phosphatase-1. This increased the activity and number of pulmonary eosinophils in the developing lung, which was associated with impaired lung development, expansion of activated alveolar macrophages (AMφ), multinucleated giant cell formation, enlargement of airspaces, and fibrosis. Despite regression of eosinophils following completion of lung development, AMφ-dominated inflammation persisted, alongside lung damage. Bone marrow chimera studies showed that SH2 domain-containing inositol 5' phosphatase-1-deficient eosinophils were not sufficient to drive inflammatory lung disease in adult steady-state mice but once inflammation and damage were present, it could not be resolved. Depletion of eosinophils during alveolarization alleviated pulmonary inflammation and lung pathology, demonstrating an eosinophil-intrinsic effect. These results show that the presence of activated eosinophils during alveolarization aggravates AMφs and promotes sustained inflammation and long-lasting lung pathology.
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Impairments in social and cognitive function are a common consequence of pediatric traumatic brain injury (TBI). Rehabilitation has the potential to promote optimal behavioral recovery. Here, we evaluated whether an enhanced social and/or cognitive environment could improve long-term outcomes in a preclinical model of pediatric TBI. Male C57Bl/6 J mice received a moderately-severe TBI or sham procedure at postnatal day 21. After one week, mice were randomized to different social conditions (minimal socialization, n = 2/cage; or social grouping, n = 6/cage), and housing conditions (standard cage, or environmental enrichment (EE), incorporating sensory, motor, and cognitive stimuli). After 8 weeks, neurobehavioral outcomes were assessed, followed by post-mortem neuropathology. We found that TBI mice exhibited hyperactivity, spatial memory deficits, reduced anxiety-like behavior, and reduced sensorimotor performance compared to age-matched sham controls. Pro-social and sociosexual behaviors were also reduced in TBI mice. EE increased sensorimotor performance, and the duration of sociosexual interactions. Conversely, social housing reduced hyperactivity and altered anxiety-like behavior in TBI mice, and reduced same-sex social investigation. TBI mice showed impaired spatial memory retention, except for TBI mice exposed to both EE and group housing. In the brain, while TBI led to significant regional tissue atrophy, social housing had modest neuroprotective effects on hippocampal volumes, neurogenesis, and oligodendrocyte progenitor numbers. In conclusion, manipulation of the post-injury environment has benefit for chronic behavioral outcomes, but the benefits are specific to the type of enrichment available. This study improves understanding of modifiable factors that may be harnessed to optimize long-term outcomes for survivors of early-life TBI.
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Lesões Encefálicas Traumáticas , Cognição , Comportamento Social , Animais , Masculino , Camundongos , Encéfalo/patologia , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/fisiopatologia , Lesões Encefálicas Traumáticas/reabilitação , Cognição/fisiologia , Aprendizagem em Labirinto , Distribuição Aleatória , Modelos Animais de Doenças , Comportamento Animal/fisiologiaRESUMO
Pediatric traumatic brain injury (TBI) is a major public health issue, and a risk factor for the development of post-traumatic epilepsy that may profoundly impact the quality of life for survivors. As the majority of neurotrauma research is focused on injury to the adult brain, our understanding of the developing brain's response to TBI remains incomplete. Neuroinflammation is an influential pathophysiological mechanism in TBI, and is thought to increase neuronal hyperexcitability, rendering the brain more susceptible to the onset of seizures and/or epileptogenesis. We here hypothesized that peripheral blood-derived macrophages, recruited into the injured brain via C-C motif ligand 2 (CCL2) chemokine/C-C chemokine receptor type 2 (CCR2) signaling, contributes to neuroinflammation and thus seizure susceptibility after experimental pediatric TBI. Using Ccr2 gene-deficient mice in the controlled cortical impact (CCI) model of TBI, in 3-week-old male mice we found that TBI led to an increase in susceptibility to pentylenetetrazol (PTZ)-evoked seizures, associated with considerable cortical tissue loss, a robust cellular neuroinflammatory response, and oxidative stress. Intriguingly, although Ccr2-deficiency increased CCL2 levels in serum, it did not exacerbate seizure susceptibility or the neuroinflammatory cellular response after pediatric TBI. Similarly, acute post-injury treatment with a CCR2 antagonist did not influence seizure susceptibility or the extent of tissue damage in wild-type (WT) mice. Together, our findings suggest that CCR2 is not a crucial driver of epileptogenesis or neuroinflammation after TBI in the developing brain. We propose that age may be an important factor differentiating our findings from previous studies in which targeting CCL2/CCR2 has been reported to be anti-inflammatory, neuroprotective or anti-seizure.
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Lesões Encefálicas Traumáticas , Doenças Neuroinflamatórias , Camundongos , Masculino , Animais , Qualidade de Vida , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/genética , Inflamação , Encéfalo/metabolismo , Quimiocina CCL2/genética , Receptores CCR2/genética , Receptores CCR2/metabolismo , Camundongos Endogâmicos C57BLRESUMO
ABSTRACT: In this research, a comprehensive code called KIANA is developed based on the Gaussian plume model to simulate and predict the radiological consequences received through all the possible, reasonable, probable, and standard exposure pathways for NPPs and chemical facilities. To validate the KIANA code, a case study is modeled for Bushehr Nuclear Power Plant Unit One (BNPP-1), and the KIANA code results are compared with the results of the Final Safety Analysis Report (FSAR-2017) data of BNPP-1. To assess the performance of the KIANA code, the total dose due to the airborne pathway in accident conditions including small break LOCA (SBLOCA), large break LOCA (LBLOCA), and equivalent exposure dose for the thyroid gland of a group of infants and children age 1 to 8 y at BNPP-1, are investigated. The KIANA code results show that the total effective doses do not exceed the regulatory limit of 5 mSv for external and internal exposures and the regulatory limit of 50 mSv for thyroid equivalent dose. The KIANA code results indicate good agreement with the results of FSAR-2017.
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Acidente Nuclear de Fukushima , Monitoramento de Radiação , Acidentes , Criança , Pré-Escolar , Humanos , Lactente , Centrais Nucleares , Doses de Radiação , Monitoramento de Radiação/métodos , Software , SuccinimidasRESUMO
While it is well-established that bone responds dynamically to mechanical loading, the effects of mild traumatic brain injury (mTBI) on cranial bone composition are unclear. We hypothesized that repeated mTBI (rmTBI) would change the microstructure of cranial bones, without gross skull fractures. To address this, young adult female Piebald Viral Glaxo rats received sham, 1×, 2× or 3× closed-head mTBIs delivered at 24 h intervals, using a weight-drop device custom-built for reproducible impact. Skull bones were collected at 2 or 10 weeks after the final injury/sham procedure, imaged by micro computed tomography and analyzed at predetermined regions of interest. In the interparietal bone, proximal to the injury site, modest increases in bone thickness were observed at 2 weeks, particularly following 2× and 3× mTBI. By 10 weeks, 2× mTBI induced a robust increase in the volume and thickness of the interparietal bone, alongside a corresponding decrease in the volume of marrow cavities in the diploë region. In contrast, neither parietal nor frontal skull samples were affected by rmTBI. Our findings demonstrate time- and location-dependent effects of rmTBI on cranial bone structure, highlighting a need to consider microstructural alterations to cranial bone when assessing the consequences of rmTBI.
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Concussão Encefálica , Lesões Encefálicas Traumáticas , Animais , Concussão Encefálica/diagnóstico por imagem , Modelos Animais de Doenças , Feminino , Ratos , Crânio/diagnóstico por imagem , Tempo , Microtomografia por Raio-XRESUMO
The current investigation presents a comprehensive program called KIANA to assess and analyze the environmental effects due to the release of radioactive materials from the stack of nuclear installations. Bushehr Nuclear Power Plant Unit One (BNPP-1) is modeled using the KIANA software and the release of radioactive materials from the BNPP-1 stack on the members of the public through the airborne pathway is evaluated during normal operation as well as in the accident conditions including Design Basis Accidents (DBA) and Beyond Design Basis Accidents (BDBA). To verify and validate the KIANA software, the results of the KIANA are compared with the results of DOZA_M, ESTE, PC-CREAM 98, RECASS Express, and the values of the total effective dose monitored by the local detectors of BNPP-1. The KIANA is developed based on the Gaussian diffusion model written using C# programming language. In the current research, the total effective dose received by a member of the public due to the radioactive plume passage through the airborne pathway is calculated in the normal condition of BNPP-1. Moreover, the total effective dose in the case of the primary-to-secondary leakage inside the steam generators, the total effective dose in the case of Large Break Loss of Coolant Accident (LBLOCA) and Small Break Loss of Coolant Accident (SBLOCA), and the equivalent dose of the thyroid gland tissue for an infant group (1-8 years old) in the case of LBLOCA in DBA conditions are evaluated. Finally, the absorbed dose of the whole body of adults at the initial stage after a BDBA, absorbed dose of the thyroid gland tissue for an infant group (1-8 years old) at the initial stage after a BDBA, and the total effective dose in the first year after the accident in the case of a BDBA are assessed. The results of the KIANA software indicate a good agreement with the results of the DOZA_M, ESTE, PC-CREAM 98, RECASS Express computer programs, and the values of the total effective dose monitored by the local detectors of BNPP-1. The developed software has the potential of calculations of concentration and radionuclide dose received through all the exposure pathways such as airborne, foodstuff, marine, soil, animals, and vegetation without any restriction in normal and accident conditions, simultaneously.
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In this paper, a novel domestic code called KIANA was developed for the assessment of radiological impacts on the population in normal and accident conditions including design basis accident (DBA) and beyond DBA (BDBA) for the nuclear power plants. The validation process of the KIANA code was performed using the results of the DOZA_M radiological code, whose results are presented in the Final Safety Analysis Report (FSAR) of the Bushehr Nuclear Power Plant Unit One (BNPP-1). The calculations of KIANA are performed based on the Gaussian diffusion model. The developed KIANA code has the potential of calculating the concentration and radionuclide doses due to the pathways such as airborne, foodstuff, marine (both one and two boxes models), soils, animals, vegetation (with and without tritium) and other pathways without any restriction. In the current research, the individual dose from a cloud to the member of the public in the region of BNPP-1 in normal condition was calculated. Moreover, the total effective dose to the member of the public from the primary to the secondary leakage inside steam generators, large break loss-of-coolant accident (LBLOCA) and small break loss-of-coolant accident was calculated. Thyroid gland equivalent dose for the infant (1-8 years) in the case of LBLOCA at the BNPP in DBA conditions was also evaluated. Finally, the prevented dose at the initial stage for the whole body of adults after BDBA, prevented dose at the initial stage for the thyroid gland of children after BDBA and the effective dose during the first year after the accident (external body irradiation from presence in the area) in the case of BDBA are assessed. The KIANA simulation results showed a good agreement with the FSAR data of BNPP.
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Acidente Nuclear de Fukushima , Monitoramento de Radiação , Adulto , Animais , Benchmarking , Criança , Humanos , Lactente , Centrais Nucleares , Doses de Radiação , Radiografia , SoftwareRESUMO
Attenuating the Taxol yield of Aspergillus terreus with the subculturing and storage were the technical challenges that prevent this fungus to be a novel platform for industrial Taxol production. Thus, the objective of this study was to unravel the metabolic machineries of A. terreus associated with attenuation of Taxol productivity, and their restoring potency upon cocultivation with the Podocarpus gracilior microbiome. The Taxol yield of A. terreus was drastically reduced with the fungal subculturing. At the 10th subculture, the yield of Taxol was reduced by four folds (78.2 µg/l) comparing to the original culture (268 µg/l), as authenticated from silencing of molecular expression of the Taxol-rate limiting enzymes (GGPPS, TDS, DBAT and BAPT) by qPCR analyses. The visual fading of A. terreus conidial pigmentation with the subculturing, revealing the biosynthetic correlation of melanin and Taxol. The level of intracellular acetyl-CoA influx was reduced sequentially with the fungal subculturing, rationalizing the decreasing on Taxol and melanin yields. Fascinatingly, the Taxol biosynthetic machinery and cellular acetyl-CoA of A. terreus have been completely restored upon addition of 3% surface sterilized leaves of P. gracilior, suggesting the implantation of plant microbiome on re-triggering the molecular machinery of Taxol biosynthesis, their transcriptional factors, and/or increasing the influx of Acetyl-CoA. The expression of the proteins of 74.4, 68.2, 37.1 kDa were exponentially suppressed with A. terreus subculturing, and strongly restored upon addition of P. gracilior leaves, ensuring their profoundly correlation with the molecular expression of Taxol biosynthetic genes. From the proteomic analysis, the restored proteins 74.4 kDa of A. terreus upon addition of P. gracilior leaves were annotated as ribosome biogenesis proteins YTM and microtubule-assembly proteins that belong to WD40 superfamily. Thus, further ongoing studies for molecular cloning and expression of these genes with strong promotors in A. terreus, have been initiated, to construct a novel platform of metabolically stable A. terreus for sustainable Taxol production. Attenuating the Taxol yield of A. terreus with the multiple-culturing and storage might be due to the reduction on main influx of acetyl-CoA, or downregulation of ribosome biogenesis proteins that belong to WD40 protein superfamily.
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Microbiota/genética , Paclitaxel/biossíntese , Pinales/genética , Proteômica , Aspergillus/genética , Vias Biossintéticas/genética , Clonagem Molecular , Pinales/microbiologia , Ribossomos/genética , Esporos Fúngicos/genética , Esporos Fúngicos/patogenicidadeRESUMO
Acute spinal cord injury (SCI) is one of the most common causes of severe disability and mortality after trauma. Magnetic resonance imaging (MRI) can identify different levels of SCI, but sometimes unable to detect the associated soft tissue injuries. The role of MRI with contrast in patients with SCI has not been studied. This is the first study in human to compare the efficacy of MRI with and without contrast in diagnosis and prognosis evaluation of SCIs.In this cross-sectional diagnostic study, MRI with and without contrast was performed on 40 patients with acute spinal injury. In these patients, 3 different types of MRI signal patterns were detected and compared.The most common cases of spinal injuries were accident (72.5%) and the after fall (27.5%). The prevalence of lesions detected includes spine fracture (70%), spinal stenosis (32.5%), soft tissue injuries (30%), and tearing of the spinal cord (2.5%). A classification was developed using 3 patterns of SCIs. Type I, seen in 2 (5.0%) of the patients, demonstrated a decreased signal intensity consistent with acute intraspinal hemorrhage. Type II, seen in 8 (20.0%) of the patients, demonstrated a bright signal intensity consistent with acute cord edema. Type III, seen in 1 (2.5%) of the patients, demonstrated a mixed signal of hypointensity centrally and hyperintensity peripherally consistent with contusion. In the diagnosis of all injuries, MRI with contrast efficacy comparable to noncontrast MRI, except in the diagnosis of soft tissue, which was significantly higher sensitivity (Pâ<â0.05).So given that is not significant differences between noncontrast and contrast-enhanced MRI in the diagnosis of major injuries (hematoma, edema, etc.) and contrast-enhanced MRI just better in soft tissues. We recommend to the MRI with contrast only used in cases of suspected severe soft tissue injury, which have been ignored by detection MRI without contrast.
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Meios de Contraste , Imageamento por Ressonância Magnética/métodos , Meglumina , Compostos Organometálicos , Traumatismos da Medula Espinal/diagnóstico , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Silicon (Si) is as an important fertilizer element, which has been found effective in enhancing plant tolerance to variety of biotic and a-biotic stresses. This study investigates the Si potential to alleviate zinc (Zn) toxicity stress in cotton (Gossypium hirsutum L.). Cotton plants were grown in hydroponics and exposed to different Zn concentration, 0, 25, and 50 µM, alone and/or in combination with 1 mM Si. Incremental Zn concentration in growth media instigated the cellular oxidative damage that was evident from elevated levels of hydrogen peroxide (H2O2), electrolyte leakage, and malondialdehyde (MDA) and consequently inhibited cotton growth, biomass, chlorophyll pigments, and photosynthetic process. Application of Si significantly suppressed Zn accumulation in various plant parts, i.e., roots, stems, and leaves and thus promoted biomass, photosynthetic, growth parameters, and antioxidant enzymes activity of Zn-stressed as well unstressed plants. In addition, Si reduced the MDA and H2O2 production and electrolyte leakage suggesting its role in protecting cotton plants from Zn toxicity-induced oxidative damage. Thus, the study indicated that exogenous Si application could improve growth and development of cotton crop experiencing Zn toxicity stress by limiting Zn bioavailability and oxidative damage.
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Gossypium/crescimento & desenvolvimento , Estresse Oxidativo/efeitos dos fármacos , Silicatos/farmacologia , Poluentes do Solo/toxicidade , Zinco/toxicidade , Biomassa , Clorofila/metabolismo , Gossypium/efeitos dos fármacos , Gossypium/metabolismo , Peróxido de Hidrogênio/análise , Hidroponia , Malondialdeído , Oxirredução , Fotossíntese/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Poluentes do Solo/farmacocinética , Zinco/farmacocinéticaRESUMO
In this study, the data and pedigree records of the native fowls collected by Fars Native Fowls Breeding Center during 1990-2004 were analyzed. A pedigree file collected on 30855 hens and roosters was used to calculate the inbreeding coefficients and its trend and its effect on production and reproduction traits. The average of inbreeding coefficient for all birds was 0.002% ranging from 0 to 14.8%. In this population, 14% of the birds were inbred with an average inbreeding coefficient of 0.019%. The Inbreeding coefficient was considered as covariate to estimate its effect on economic traits including body weight in 12 weeks (BW12), egg number during 12 weeks (EN), mean egg weight between 28 to 32 weeks (MEW) and Age of Sexual Maturity (ASM). Results showed that inbreeding does not have a significant effect on the traits under study (p > 0.05). Moreover, heritability, genetic and phenotypic correlations between traits was estimated through a multiple traits animal model procedure by restricted maximum likelihood using ASREML software. The estimated heritabilities were 0.53, 0.47, 0.57 and 0.22 for body weight in 12 weeks (BW12), Age of Sexual Maturity (ASM), mean Egg Weight (EW) and Egg Number (EN), respectively. Because of relatively high heritabilities of productive and reproductive traits, it is possible to achieve more genetic gains in these traits using appropriate genetic selection.
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Aves/genética , Endogamia , Característica Quantitativa Herdável , Reprodução/genética , Animais , Peso Corporal/genética , Feminino , Genótipo , Irã (Geográfico) , Masculino , Modelos Genéticos , Oviparidade/genética , Linhagem , Fenótipo , Maturidade Sexual/genéticaRESUMO
This paper presents the proof of concept of a low power, low cost, wearable activity monitor. The functionality of the system is based on accurate stride detection from signals generated by two force sensing resistors integrated within a normal shoe. A novel algorithm is proposed that is able to differentiate between walking and non-walking activities with high accuracy. The performance of the proof of concept system was validated in five subjects who underwent five repetitions of three different speed walking tests, and five repetitions of five non-walking artefact generating tests. The system achieved a total sensitivity of 96% with 98% specificity and an overall accuracy of 94%.
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Técnicas Biossensoriais , Sapatos , Algoritmos , Marcha , Humanos , CaminhadaRESUMO
Global analyses of splicing of precursor messenger RNAs (pre-mRNAs) have revealed that alternative splicing (AS) is highly pervasive in plants. Despite the widespread occurrence of AS in plants, the mechanisms that control splicing and the roles of splice variants generated from a gene are poorly understood. Studies on plant serine/arginine-rich (SR) proteins, a family of highly conserved proteins, suggest their role in both constitutive splicing and AS of pre-mRNAs. SR proteins have a characteristic domain structure consisting of one or two RNA recognition motifs at the N-terminus and a C-terminal RS domain rich in arginine/serine dipeptides. Plants have many more SR proteins compared to animals including several plant-specific subfamilies. Pre-mRNAs of plant SR proteins are extensively alternatively spliced to increase the transcript complexity by about six-fold. Some of this AS is controlled in a tissue- and development-specific manner. Furthermore, AS of SR pre-mRNAs is altered by various stresses, raising the possibility of rapid reprogramming of the whole transcriptome by external signals through regulation of the splicing of these master regulators of splicing. Most SR splice variants contain a premature termination codon and are degraded by up-frameshift 3 (UPF3)-mediated nonsense-mediated decay (NMD), suggesting a link between NMD and regulation of expression of the functional transcripts of SR proteins. Limited functional studies with plant SRs suggest key roles in growth and development and plant responses to the environment. Here, we discuss the current status of research on plant SRs and some promising approaches to address many unanswered questions about plant SRs.
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Proteínas de Arabidopsis/metabolismo , Proteínas Nucleares/metabolismo , Precursores de RNA/metabolismo , Splicing de RNA/fisiologia , RNA de Plantas/metabolismo , Proteínas de Ligação a RNA/metabolismo , Processamento Alternativo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Modelos Biológicos , Proteínas Nucleares/genética , Precursores de RNA/genética , RNA de Plantas/genética , Proteínas de Ligação a RNA/genética , Fatores de Processamento de Serina-Arginina , Estresse FisiológicoRESUMO
Recently we reported that CRLK1, a novel calcium/calmodulin-regulated receptor-like kinase plays an important role in regulating plant cold tolerance. Calcium/calmodulin binds to CRLK1 and upregulates its activity. Gene knockout and complementation studies revealed that CRLK1 is a positive regulator of plant response to chilling and freezing temperatures. Here we show that MEKK1, a member of MAP kinase kinase kinase family, interacts with CRLK1 both in vitro and in planta. The cold triggered MAP kinase activation in wild-type plants was abolished in crlk1 knockout mutants. Similarly, the cold induced expression levels of genes involved in MAP kinase signaling are also altered in crlk1 mutants. These results suggest that calcium/calmodulin-regulated CRLK1 modulates cold acclimation through MAP kinase cascade in plants.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Temperatura Baixa , MAP Quinase Quinase Quinase 1/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Transdução de SinaisRESUMO
BACKGROUND: In plants, calcium (Ca2+) has emerged as an important messenger mediating the action of many hormonal and environmental signals, including biotic and abiotic stresses. Many different signals raise cytosolic calcium concentration ([Ca2+]cyt), which in turn is thought to regulate cellular and developmental processes via Ca2+-binding proteins. Three out of the four classes of Ca2+-binding proteins in plants contain Ca2+-binding EF-hand motif(s). This motif is a conserved helix-loop-helix structure that can bind a single Ca2+ ion. To identify all EF-hand-containing proteins in Arabidopsis, we analyzed its completed genome sequence for genes encoding EF-hand-containing proteins. RESULTS: A maximum of 250 proteins possibly having EF-hands were identified. Diverse proteins, including enzymes, proteins involved in transcription and translation, protein- and nucleic-acid-binding proteins and a large number of unknown proteins, have one or more putative EF-hands. Phylogenetic analysis identified six major groups that contain some families of proteins. CONCLUSIONS: The presence of EF-hand motif(s) in a diversity of proteins is consistent with the involvement of Ca2+ in regulating many cellular and developmental processes. Thus far, only 47 of the possible 250 EF-hand proteins have been reported in the literature. Various domains that we identified in many of the uncharacterized EF-hand-containing proteins should help in elucidating their cellular role(s). Our analyses suggest that the Ca2+ messenger system is widely used in plants and that EF-hand-containing proteins are likely to be the key transducers mediating Ca2+ action.