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1.
Brief Bioinform ; 25(2)2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38343323

RESUMO

Veterinary systems biology is an innovative approach that integrates biological data at the molecular and cellular levels, allowing for a more extensive understanding of the interactions and functions of complex biological systems in livestock and veterinary science. It has tremendous potential to integrate multi-omics data with the support of vetinformatics resources for bridging the phenotype-genotype gap via computational modeling. To understand the dynamic behaviors of complex systems, computational models are frequently used. It facilitates a comprehensive understanding of how a host system defends itself against a pathogen attack or operates when the pathogen compromises the host's immune system. In this context, various approaches, such as systems immunology, network pharmacology, vaccinology and immunoinformatics, can be employed to effectively investigate vaccines and drugs. By utilizing this approach, we can ensure the health of livestock. This is beneficial not only for animal welfare but also for human health and environmental well-being. Therefore, the current review offers a detailed summary of systems biology advancements utilized in veterinary sciences, demonstrating the potential of the holistic approach in disease epidemiology, animal welfare and productivity.


Assuntos
Bem-Estar do Animal , Biologia de Sistemas , Animais , Biologia Computacional , Simulação por Computador , Genótipo , Fenótipo
2.
Environ Res ; 252(Pt 3): 119034, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38701888

RESUMO

Cumulative human exposure to the environmental toxin, bisphenol A (BPA), has raised important health concerns in recent decades. However, the direct genomic regulation of BPA in skeletal muscles and its clinical significance are poorly understood. Therefore, we conducted a genome-wide transcriptome analysis after daily oral administration of BPA at the lowest observed adverse-effect level (LOAEL, 50 mg/kg) in male mice for six weeks to explore the gene-expression regulations in skeletal muscle induced by BPA. The primary Gene Ontology terms linked to BPA-dependent, differentially expressed genes at LOAEL comprised adaptive-immune response, positive regulation of T cell activation, and immune system process. The gene-set enrichment analysis disclosed increased complement-associated genes [complement components 3 (C3) and 4B, complement factor D, complement receptor 2, and immunoglobulin lambda constant 2] in the group administered with BPA, with a false-discovery rate of <0.05. Subsequent validation analysis conducted in BPA-fed animal skeletal muscle tissue and in vitro experiments confirmed that BPA induced immune activation, as evidenced by increased levels of C3 and C4α proteins in mice, C2C12 myoblasts, and mouse skeletal muscle cells. In addition, BPA markedly upregulated the transcription of tumor necrosis factor-α (Tnfα) in C2C12 myoblasts and mouse skeletal muscle cells, which was substantially inhibited by 5z-7-oxozeanol and parthenolide, providing further evidence of BPA-induced inflammation in muscle cells. Our bioinformatics and subsequent animal and in vitro validations demonstrate that BPA can activate inflammation in skeletal muscle, which could be a risk factor underlying chronic muscle weakness and wastage.


Assuntos
Compostos Benzidrílicos , Perfilação da Expressão Gênica , Músculo Esquelético , Fenóis , Compostos Benzidrílicos/toxicidade , Animais , Fenóis/toxicidade , Masculino , Camundongos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Transcriptoma/efeitos dos fármacos , Camundongos Endogâmicos C57BL
3.
Anim Biotechnol ; 35(1): 2331179, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38519440

RESUMO

Despite the significant threat of heat stress to livestock animals, only a few studies have considered the potential relationship between broiler chickens and their microbiota. Therefore, this study examined microbial modifications, transcriptional changes and host-microbiome interactions using a predicted metabolome data-based approach to understand the impact of heat stress on poultry. After the analysis, the host functional enrichment analysis revealed that pathways related to lipid and protein metabolism were elevated under heat stress conditions. In contrast, pathways related to the cell cycle were suppressed under normal environmental temperatures. In line with the transcriptome analysis, the microbial analysis results indicate that taxonomic changes affect lipid degradation. Heat stress engendered statistically significant difference in the abundance of 11 microorganisms, including Bacteroides and Peptostreptococcacea. Together, integrative approach analysis suggests that microbiota-induced metabolites affect host fatty acid peroxidation metabolism, which is correlated with the gene families of Acyl-CoA dehydrogenase long chain (ACADL), Acyl-CoA Oxidase (ACOX) and Acetyl-CoA Acyltransferase (ACAA). This integrated approach provides novel insights into heat stress problems and identifies potential biomarkers associated with heat stress.


Assuntos
Aves Domésticas , Transcriptoma , Animais , Aves Domésticas/genética , Aves Domésticas/metabolismo , Peroxidação de Lipídeos/genética , Jejuno/metabolismo , Galinhas/genética , Galinhas/metabolismo , Perfilação da Expressão Gênica , Resposta ao Choque Térmico/genética , Lipídeos , Aminoácidos/genética , Aminoácidos/metabolismo
4.
BMC Vet Res ; 18(1): 337, 2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36071517

RESUMO

BACKGROUND: Milk provides energy as well as the basic nutrients required by the body. In particular, milk is beneficial for bone growth and development in children. Based on scientific evidence, cattle milk is an excellent and highly nutritious dietary component that is abundant in vitamins, calcium, potassium, and protein, among other minerals. However, the commercial productivity of cattle milk is markedly affected by mastitis. Mastitis is an economically important disease that is characterized by inflammation of the mammary gland. This disease is frequently caused by microorganisms and is detected as abnormalities in the udder and milk. Streptococcus agalactiae is a prominent cause of mastitis. Antibiotics are rarely used to treat this infection, and other available treatments take a long time to exhibit a therapeutic effect. Vaccination is recommended to protect cattle from mastitis. Accordingly, the present study sought to design a multi-epitope vaccine using immunoinformatics. RESULTS: The vaccine was designed to be antigenic, immunogenic, non-toxic, and non-allergic, and had a binding affinity with Toll-like receptor 2 (TLR2) and TLR4 based on structural modeling, docking, and molecular dynamics simulation studies. Besides, the designed vaccine was successfully expressed in E. coli. expression vector (pET28a) depicts its easy purification for production on a larger scale, which was determined through in silico cloning. Further, immune simulation analysis revealed the effectiveness of the vaccine with an increase in the population of B and T cells in response to vaccination. CONCLUSION: This multi-epitope vaccine is expected to be effective at generating an immune response, thereby paving the way for further experimental studies to combat mastitis.


Assuntos
Vacinas Bacterianas , Doenças dos Bovinos , Mastite Bovina , Animais , Vacinas Bacterianas/imunologia , Bovinos , Doenças dos Bovinos/microbiologia , Doenças dos Bovinos/prevenção & controle , Biologia Computacional , Epitopos , Escherichia coli , Feminino , Mastite Bovina/prevenção & controle , Proteínas de Membrana , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Streptococcus agalactiae , Vacinas de Subunidades Antigênicas/imunologia
5.
Soft Matter ; 17(47): 10703-10715, 2021 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-34783328

RESUMO

We present the general structural and dynamical characteristics of flexible ring polymers in narrowly confined two-dimensional (2D) melt systems using atomistic molecular dynamics simulations. The results are further analyzed via direct comparison with the 2D linear analogue as well as the three-dimensional (3D) ring and linear melt systems. It is observed that dimensional restriction in 2D confined systems results in an increase in the intrinsic chain stiffness of the ring polymer. Fundamentally, this arises from an entropic penalty on polymer chains along with a reduction in the available chain configuration states in phase space and spatial choices for individual segmental walks. This feature in combination with the intermolecular interactions between neighboring ring chains leads to an overall extended interpenetrated chain configuration for the 2D ring melt. In contrast to the generally large differences in structural and dynamical properties between ring and linear polymers in 3D melt systems, relatively similar local-to-global chain structures and dynamics are observed for the 2D ring and linear melts. This is attributed to the general structural similarity (i.e., extended double-stranded chain conformations), the less effective role of the chain ends, and the absence of complex topological constraints between chains (i.e., interchain entanglement and mutual ring threading) in the 2D confined systems compared with the corresponding 3D bulk systems.

6.
Genomics ; 112(2): 1988-1999, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31759120

RESUMO

We analyzed the whole genomes of cecum microbiomes of Ethiopian indigenous chickens from two distinct geographical zones: Afar (AF) district (Dulecha, 730 m above sea level) and Amhara (AM) district (Menz Gera Midir, 3300 m). Through metagenomic analysis we found that microbial populations were mainly dominated by Bacteroidetes and Firmicutes. We identified 2210 common genes in the two groups. LEfSe showed that the distribution of Coprobacter, Geobacter, Cronobacter, Alloprevotella, and Dysgonomonas were more abundant in AF than AM. Analyses using KEGG, eggNOG, and CAZy databases indicated that the pathways of metabolism, genetic information processing, environmental information processing, and cellular process were significantly enriched. Functional abundance was found to be associated with the nutrient absorption and microbial localization of indigenous chickens. We also investigated antibiotic resistant genes and found antibiotics like LSM, cephalosporin, and tetracycline were significantly more abundant in AF than AM.


Assuntos
Galinhas/microbiologia , Farmacorresistência Bacteriana , Microbioma Gastrointestinal , Metagenoma , Animais , Bacteroidetes/genética , Bacteroidetes/patogenicidade , Ceco/microbiologia , Etiópia , Firmicutes/genética , Firmicutes/patogenicidade , Metagenômica/métodos , Sequenciamento Completo do Genoma/métodos
7.
Int J Mol Sci ; 22(2)2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33451076

RESUMO

Porcine heart xenotransplantation is a potential treatment for patients with end-stage heart failure. To understand molecular mechanisms of graft rejection after heart transplantation, we transplanted a 31-day-old alpha-1,3-galactosyltransferase knockout (GTKO) porcine heart to a five-year-old cynomolgus monkey. Histological and transcriptome analyses were conducted on xenografted cardiac tissue at rejection (nine days after transplantation). The recipient monkey's blood parameters were analyzed on days -7, -3, 1, 4, and 7. Validation was conducted by quantitative real-time PCR (qPCR) with selected genes. A non-transplanted GTKO porcine heart from an age-matched litter was used as a control. The recipient monkey showed systemic inflammatory responses, and the rejected cardiac graft indicated myocardial infarction and cardiac fibrosis. The transplanted heart exhibited a total of 3748 differentially expressed genes compared to the non-transplanted heart transcriptome, with 2443 upregulated and 1305 downregulated genes. Key biological pathways involved at the terminal stage of graft rejection were cardiomyopathies, extracellular interactions, and ion channel activities. The results of qPCR evaluation were in agreement with the transcriptome data. Transcriptome analysis of porcine cardiac tissue at graft rejection reveals dysregulation of the key molecules and signaling pathways, which play relevant roles on structural and functional integrities of the heart.


Assuntos
Rejeição de Enxerto , Transplante de Coração , Transplante Heterólogo , Animais , Biomarcadores , Biologia Computacional/métodos , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Ontologia Genética , Rejeição de Enxerto/genética , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/prevenção & controle , Haplorrinos , Transplante de Coração/efeitos adversos , Imunossupressores/farmacologia , Masculino , Anotação de Sequência Molecular , Suínos , Transcriptoma , Transplante Heterólogo/efeitos adversos
8.
Funct Integr Genomics ; 20(1): 117-131, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31396752

RESUMO

The estrous cycle is a complex process regulated by several hormones. To understand the dynamic changes in gene expression that takes place in the swine endometrium during the estrous cycle relative to the day of estrus onset, we performed RNA-sequencing analysis on days 0, 3, 6, 9, 12, 15, and 18, resulting in the identification of 4495 differentially expressed genes (DEGs; Q ≤ 0.05 and |log2FC| ≥ 1) at various phases in the estrous cycle. These DEGs were integrated into multiple gene co-expression networks based on different fold changes and correlation coefficient (R2) thresholds and a suitable network, which included 899 genes (|log2FC| ≥ 2 and R2 ≥ 0.99), was identified for downstream analyses based on the biological relevance of the Gene Ontology (GO) terms enriched. The genes in this network were partitioned into 6 clusters based on the expression pattern. Several GO terms including cell cycle, apoptosis, hormone signaling, and lipid biosynthetic process were found to be enriched. Furthermore, we found 15 significant KEGG pathways, including cell adhesion molecules, cytokine-cytokine receptor signaling, steroid biosynthesis, and estrogen signaling pathways. We identified several genes and GO terms to be stage-specific. Moreover, the identified genes and pathways extend our understanding of porcine endometrial regulation during estrous cycle and will serve as a good resource for future studies.


Assuntos
Endométrio/metabolismo , Ciclo Estral/genética , Sus scrofa/genética , Animais , Apoptose/genética , Feminino , Ontologia Genética , Redes Reguladoras de Genes , RNA-Seq , Sus scrofa/metabolismo
9.
Vet Res ; 51(1): 128, 2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33050948

RESUMO

Porcine reproductive and respiratory syndrome virus (PRRSV) infection is the most important viral disease causing severe economic losses in the swine industry. However, mechanisms underlying gene expression control in immunity-responsible tissues at different time points during PRRSV infection are poorly understood. We constructed an integrated gene co-expression network and identified tissue- and time-dependent biological mechanisms of PRRSV infection through bioinformatics analysis using three tissues (lungs, bronchial lymph nodes [BLNs], and tonsils) via RNA-Seq. Three groups with specific expression patterns (i.e., the 3-dpi, lung, and BLN groups) were discovered. The 3 dpi-specific group showed antiviral and innate-immune signalling similar to the case for influenza A infection. Moreover, we observed adaptive immune responses in the lung-specific group based on various cytokines, while the BLN-specific group showed down-regulated AMPK signalling related to viral replication. Our study may provide comprehensive insights into PRRSV infection, as well as useful information for vaccine development.


Assuntos
Imunidade Adaptativa/genética , Imunidade Inata/genética , Síndrome Respiratória e Reprodutiva Suína/imunologia , Vírus da Síndrome Respiratória e Reprodutiva Suína/fisiologia , Transcriptoma/imunologia , Animais , Síndrome Respiratória e Reprodutiva Suína/genética , Síndrome Respiratória e Reprodutiva Suína/virologia , Sus scrofa , Suínos
10.
Gynecol Endocrinol ; 36(7): 599-604, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32321334

RESUMO

To verify the different expression of G protein-coupled estrogen receptor 1 (GPER1) among normal uterine, leiomyoma, and adenomyosis tissues. Normal uterine, leiomyoma, and adenomyosis tissue samples were obtained from women aged 35-52 years from a tertiary university hospital. The tissue samples were subjected to immunohistochemical, Western blot, and reverse-transcription polymerase chain reaction (RT-PCR) analyses of GPER1. GPER1 protein expression was confirmed in the tissues by immunohistochemical and Western blot analyses and compared with GPER1 mRNA levels using RT-PCR. GPER1 was detected in the tissue samples of leiomyoma and adenomyosis, which are estrogen-dependent diseases. GPER1 expression was similar between normal uterine and leiomyoma tissues but was reduced in adenomyosis tissue. The level of phosphorylated extracellular signal-regulated kinases 1/2 was lower and higher in leiomyoma and adenomyosis tissues, respectively, than in normal tissue, but the differences among the groups were not statistically significant. Our immunohistochemical, Western blot, and RT-PCR results suggest that GPER1 expression is involved in cell proliferation in leiomyoma and in cell invasion and migration in adenomyosis. Functional studies of GPER1 involving larger sample sizes should be performed to confirm the adenomyosis and leiomyoma disease mechanisms and eventually to develop new therapeutic interventions for these diseases.


Assuntos
Adenomiose/genética , Leiomioma/genética , Miométrio/metabolismo , Receptores de Estrogênio/genética , Receptores Acoplados a Proteínas G/genética , Neoplasias Uterinas/genética , Adenomiose/metabolismo , Adenomiose/patologia , Adulto , Estudos de Casos e Controles , Feminino , Expressão Gênica , Humanos , Imuno-Histoquímica , Leiomioma/metabolismo , Leiomioma/patologia , Pessoa de Meia-Idade , Miométrio/patologia , Receptores de Estrogênio/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Neoplasias Uterinas/metabolismo , Neoplasias Uterinas/patologia , Útero/metabolismo , Útero/patologia
11.
Am J Physiol Regul Integr Comp Physiol ; 314(3): R334-R341, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29092859

RESUMO

The renal outer medullary potassium channel (ROMK; Kir1.1) plays an important role in Na+ and K+ homeostasis. ROMK knockout (KO) mice show a similar phenotype to Bartter's syndrome of salt wasting and dehydration due to reduced Na-2Cl-K-cotransporter activity but not in ROMK1 KO mice. ROMK KO mice also show hydronephrosis; however, the mechanism of this phenotype has not been understood. We have previously demonstrated a gender-sex difference in hydronephrosis and PGE2 production in ROMK KO mice. In this study we compared the gender-sex difference in bladder hypertrophy and hydronephrosis in ROMK KO mice. The bladder weight, bladder capacity, and the thickness of urothelium in male ROMK KO showed average increased two to approximately fourfold greater than wild-type (WT) mice, but there was no difference in either female or ROMK1 KO mice. The thickness of the urothelium was 648.8 ± 33.2 µm vs. 302.7 ± 16.5 µm ( P < 0.001) and the detrusor muscle 1,940.7 ± 98.9 µm vs. 1,308.2 ± 102.1 µm ( P = 0.013), respectively, in 12-mo male ROMK KO mice compared with the same age WT mice. Western blotting detected ROMK expression at 45~48 kDa, and both ROMK1 and ROMK2 mRNA were detected by quantitative PCR in the bladder. Immunofluorescence staining showed ROMK stained in the bladder, ureter, and urethra in WT but not in KO. In addition, there was a correlation between the severity of hydronephrosis and the bladder weight in male but not in female ROMK KO mice. In conclusion, ROMK expressed in the urinary tract at both protein and mRNA levels; significant enlargement and hypertrophy of the bladder may contribute to hydronephrosis in male ROMK KO mice.


Assuntos
Síndrome de Bartter/metabolismo , Hidronefrose/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Bexiga Urinária/metabolismo , Animais , Síndrome de Bartter/genética , Síndrome de Bartter/patologia , Modelos Animais de Doenças , Feminino , Predisposição Genética para Doença , Hidronefrose/genética , Hidronefrose/patologia , Hipertrofia , Masculino , Camundongos Knockout , Músculo Liso/metabolismo , Músculo Liso/patologia , Tamanho do Órgão , Fenótipo , Canais de Potássio Corretores do Fluxo de Internalização/deficiência , Canais de Potássio Corretores do Fluxo de Internalização/genética , Fatores Sexuais , Ureter/metabolismo , Ureter/patologia , Uretra/metabolismo , Uretra/patologia , Bexiga Urinária/patologia , Urotélio/metabolismo , Urotélio/patologia
12.
Soft Matter ; 14(3): 470, 2018 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-29265163

RESUMO

Correction for 'Effect of short-chain branching on interfacial polymer structure and dynamics under shear flow' by Sohdam Jeong et al., Soft Matter, 2017, 13, 8644-8650.

13.
Soft Matter ; 13(45): 8644-8650, 2017 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-29115348

RESUMO

We present a detailed analysis on the effect of short-chain branches on the structure and dynamics of interfacial chains using atomistic nonequilibrium molecular dynamics simulations of confined polyethylene melts in a wide range of shear rates. The intrinsically fast random motions of the short branches constantly disturb the overall chain conformation, leading to a more compact and less deformed chain structure of the short-chain branched (SCB) polymer against the imposed flow field in comparison with the corresponding linear polymer. Moreover, such highly mobile short branches along the backbone of the SCB polymer lead to relatively weaker out-of-plane wagging dynamics of interfacial chains, with highly curvy backbone structures in the intermediate flow regime. In conjunction with the contribution of short branches (as opposed to that of the backbone) to the total interfacial friction between the chains and the wall, the SCB polymer shows a nearly constant behavior in the degree of slip (ds) with respect to shear rate in the weak-to-intermediate flow regimes. On the contrary, in the strong flow regime where irregular chain rotation and tumbling dynamics occur via intensive dynamical collisions between interfacial chains and the wall, an enhancement effect on the chain detachment from the wall, caused by short branches, leads to a steeper increase in ds for the SCB polymer than for the linear polymer. Remarkably, the SCB chains at the interface exhibit two distinct types of rolling mechanisms along the backbone, with a half-dumbbell mesoscopic structure at strong flow fields, in addition to the typical hairpin-like tumbling behavior displayed by the linear chains.

14.
J Chem Phys ; 147(23): 234901, 2017 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-29272944

RESUMO

Stress overshoot is one of the most important nonlinear rheological phenomena exhibited by polymeric liquids undergoing start-up shear at sufficient flow strengths. Despite considerable previous research, the fundamental molecular characteristics underlying stress overshoot remain unknown. Here, we analyze the intrinsic molecular mechanisms behind the overshoot phenomenon using atomistic nonequilibrium molecular dynamics simulations of entangled linear polyethylene melts under shear flow. Through a detailed analysis of the transient rotational chain dynamics, we identify an intermolecular collision angular regime in the vicinity of the chain orientation angle θ ≈ 20° with respect to the flow direction. The shear stress overshoot occurs via strong intermolecular collisions between chains in the collision regime at θ = 15°-25°, corresponding to a peak strain of 2-4, which is an experimentally well-known value. The normal stress overshoot appears at approximately θ = 10°, at a corresponding peak strain roughly equivalent to twice that for the shear stress. We provide plausible answers to several basic questions regarding the stress overshoot, which may further help understand other nonlinear phenomena of polymeric systems.

15.
Urol Int ; 98(2): 228-235, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28161708

RESUMO

OBJECTIVE: We evaluated the changes in the migration inhibitory factor (MIF) expression with time in the bladder and spinal cord of a Sprague-Dawley rat cystitis model. METHODS: The bladder created by injecting lipopolysaccharide (LPS) and the lumbosacral spinal cord were removed at 4, 24, and 48 h, and 7 days after the induction of chronic cystitis, and 24 h after the induction of acute cystitis. The MIF expression was estimated using immunohistochemical staining, and the MIF mRNA was quantitatively analyzed using real-time polymerase chain reaction. RESULTS: The MIF expression in the urothelial cell was lowest at 24 h after LPS injection. As the degree of inflammation decreased, the MIF expression in the urothelial cell gradually increased 48 h and 7 days. The quantitative analysis of the MIF mRNA showed that the MIF expression was highest in both the bladder and the lumbosacral spinal cord 24 h after the cystitis became most severe. In chronic cystitis, the MIF mRNA expressions in the bladder and the lumbosacral spinal cord were 2.8 and 2.1 times significantly higher than in the normal control. CONCLUSION: MIF is involved in urinary symptoms and pain in cystitis, and in the mechanism that prolongs the symptoms of chronic cystitis by involving bladder tissue, and the nervous system.


Assuntos
Cistite/metabolismo , Cistite/fisiopatologia , Oxirredutases Intramoleculares/metabolismo , Fatores Inibidores da Migração de Macrófagos/metabolismo , Sistema Nervoso/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Imuno-Histoquímica , Inflamação , Ketamina/metabolismo , Lipopolissacarídeos/química , Dor Pélvica , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Medula Espinal/metabolismo , Bexiga Urinária/metabolismo , Urotélio/metabolismo
16.
Soft Matter ; 12(16): 3770-86, 2016 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-26997526

RESUMO

We present detailed results on the effect of chain branching on the topological properties of entangled polymer melts via an advanced connectivity-altering Monte Carlo (MC) algorithm. Eleven representative model linear, short-chain branched (SCB), and long-chain branched (LCB) polyethylene (PE) melts were employed, based on the total chain length and/or the longest linear chain dimension. Directly analyzing the entanglement [or the primitive path (PP)] network of the system via the Z-code, we quantified several important topological measures: (a) the PP contour length Lpp, (b) the number of entanglements Zes per chain, (c) the end-to-end length of an entanglement strand des, (d) the number of carbon atoms per entanglement strand Nes, and (e) the probability distribution for each of these quantities. The results show that the SCB polymer melts have significantly more compact overall chain conformations compared to the linear polymers, exhibiting, relative to the corresponding linear analogues, (a) ∼20% smaller values of 〈Lpp〉 (the statistical average of Lpp), (b) ∼30% smaller values of 〈Zes〉, (c) ∼20% larger values of 〈des〉, and (d) ∼50% larger values of 〈Nes〉. In contrast, despite the intrinsically smaller overall chain dimensions than those of the linear analogues, the LCB (H-shaped and A3AA3 multiarm) PE melts exhibit relatively (a) 7-8% larger values of 〈Lpp〉, (b) 6-11% larger values of 〈Zes〉 for the H-shaped melt and ∼2% smaller values of 〈Zes〉 for the A3AA3 multiarm, (c) 2-5% smaller values of 〈des〉, and (d) 7-11% smaller values of 〈Nes〉. Several interesting features were also found in the results of the probability distribution functions P for each topological measure.

17.
J Chem Phys ; 144(8): 081101, 2016 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-26931673

RESUMO

A comprehensive understanding of chain-branching effects, essential for establishing general knowledge of the structure-property-phenomenon relationship in polymer science, has not yet been found, due to a critical lack of knowledge on the role of short-chain branches, the effects of which have mostly been neglected in favor of the standard entropic-based concepts of long polymers. Here, we show a significant effect of short-chain branching on the structural and dynamical properties of polymeric materials, and reveal the molecular origins behind the fundamental role of short branches, via atomistic nonequilibrium molecular dynamics and mesoscopic Brownian dynamics by systematically varying the strength of the mobility of short branches. We demonstrate that the fast random Brownian kinetics inherent to short branches plays a key role in governing the overall structure and dynamics of polymers, leading to a compact molecular structure and, under external fields, to a lesser degree of structural deformation of polymer, to a reduced shear-thinning behavior, and to a smaller elastic stress, compared with their linear analogues. Their fast dynamical nature being unaffected by practical flow fields owing to their very short characteristic time scale, short branches would substantially influence (i.e., facilitate) the overall relaxation behavior of polymeric materials under various flowing conditions.

20.
Asian-Australas J Anim Sci ; 28(2): 151-7, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25557809

RESUMO

Fatness qualities in pigs measured by the amount of fat deposition and composition of fatty acids (FAs) in pork have considerable effect on current breeding goals. The stearoyl-CoA desaturase (SCD) gene plays a crucial role in the conversion of saturated FAs into monounsaturated FAs (MUFAs), and hence, is among the candidate genes responsible for pig fatness traits. Here, we identified a single nucleotide polymorphism (SNP, c.*2041T>C) in the 3' untranslated region by direct sequencing focused on coding and regulatory regions of porcine SCD. According to the association analysis using a hundred of Berkshire pigs, the SNP was significantly associated with FA composition (MUFAs and polyunsaturated FAs [PUFAs]), polyunsaturated to saturated (P:S) FA ratio, n-6:n-3 FA ratio, and extent of fat deposition such as intramuscular fat and marbling (p<0.05). In addition, the SNP showed a significant effect on the SCD mRNA expression levels (p = 0.041). Based on our results, we suggest that the SCD c.*2041T>C SNP plays a role in the gene regulation and affects the fatness qualities in Berkshire pigs.

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