Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Cureus ; 16(3): e57092, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38681348

RESUMO

Introduction Planovalgus deformity is common in children with spastic cerebral palsy (CP), particularly spastic diplegia and spastic quadriplegia. It results from muscle imbalance over the immature foot skeleton, leading to hindfoot valgus, forefoot abduction, and joint subluxation. Surgical interventions, like calcaneal lengthening osteotomy (CLO), are frequently employed to correct this deformity, but objective guidelines for its use in CP patients are lacking. Material and methods This retrospective cohort study examined the efficacy of CLO in correcting plano valgus deformity in pediatric CP patients at the Pediatric Orthopedic Unit of Christian Medical College (CMC) in Vellore, India. Data from patient records and radiographs were collected, including demographics, pre- and postoperative angles, and surgical details. Statistical analysis was performed to assess changes in angles and associations with various factors. Results After the surgery, there was a notable enhancement in the calcaneal pitch, lateral talo-first metatarsal angle, and naviculocuboid overlap, as shown by the CLO results. However, tibiocalcaneal angles did not show significant changes. Associations were observed between age, Gross Motor Function Classification System (GMFCS) level, additional surgeries, and postoperative angle corrections. Conclusion CLO shows promise in correcting plano valgus deformity, with age, GMFCS level, and comorbidities influencing outcomes. Long-term follow-up is crucial to monitor correction durability. Specific radiographic angles provide insights into CLO's biomechanical effects, but study limitations warrant caution in interpretation. CLO effectively corrects plano valgus deformity in pediatric CP patients, with age, GMFCS level, and comorbidities influencing outcomes. Long-term follow-up and further research are needed to optimize management strategies and enhance understanding of surgical outcomes.

2.
Front Nutr ; 10: 1121508, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36742434

RESUMO

In the current scenario, it is estimated that by 2050, there will be an additional 2.5 billion people and a 70% increase in food demand. Crop yields are not increasing fast enough to support global needs, and world agriculture is facing several serious challenges. Therefore, insects can be a nutritious alternative to meet the ever-increasing food demand in the present and future. The majority of insect consumption occurs in developing countries, with approximately 1,900 insect species consumed worldwide. Food and feed derived from them are of high quality, have a high feed conversion ratio and emit a low level of greenhouse gases. Among insects silkworms are beneficial to humans, not only because of their high nutritional value, but also because of their several pharmacological properties. Silkworm eggs, larvae, and pupae contains high amount of proteins, oils, minerals, vitamins, and several other beneficial components which are nutritious as well as have positive effect on human health. Studies have shown that silkworm pupae protect the liver, enhance immunity, inhibit apoptosis, inhibit cancer, inhibit tumor growth, inhibit microbial growth, regulate blood glucose and blood lipids, and lower blood pressure. This review paper summerized the nutritional value of different life stages of silkworm, nutritional comparison of silkworm with the major human foods, and the effects of silkworm consumption on human health, thus ittargets to generate interest toward in sericulture and improve human health by using silkworm as a nutritious food and attain sustainability in food and nutritional security.

3.
Zootaxa ; 5194(2): 213-232, 2022 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-37045335

RESUMO

Four species of soft scale insect [Hemiptera: Coccidae: Fistulococcus pokfulamensis Hodgson & Martin, Kilifia deltoides De Lotto, Maacoccus piperis (Green) and Paralecanium machili Takahashi] and two species of mealybug [Hemiptera: Pseudococcidae: Antonina thaiensis Takahashi and Formicococcus simplicior (Green)] are recorded in India for the first time. Each of the six species is comprehensively diagnosed based on Indian material, and compared with earlier descriptions. Keys to the Indian species in their respective genera are provided to facilitate identification. Ecological information on host plants, associated ants and natural enemies is also given.


Assuntos
Formigas , Hemípteros , Animais , Índia
4.
PLoS One ; 7(12): e51641, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23272127

RESUMO

Mycobacterium tuberculosis (Mtb) is known to produce wax esters (WE) when subjected to stress. However, nothing is known about the enzymes involved in biosynthesis of WE and their role in mycobacterial dormancy. We report that two putative Mtb fatty acyl-CoA reductase genes (fcr) expressed in E. coli display catalytic reduction of fatty acyl-CoA to fatty aldehyde and fatty alcohol. Both enzymes (FCR1/Rv3391) and FCR2/Rv1543) showed a requirement for NADPH as the reductant, a preference for oleoyl-CoA over saturated fatty acyl-CoA and were inhibited by thiol-directed reagents. We generated Mtb gene-knockout mutants for each reductase. Metabolic incorporation of( 14)C-oleate into fatty alcohols and WE was severely diminished in the mutants under dormancy-inducing stress conditions that are thought to be encountered by the pathogen in the host. The fatty acyl-CoA reductase activity in cell lysates of the mutants under nitric oxide stress was significantly reduced when compared with the wild type. Complementation restored the lost activity completely in the Δfcr1 mutant and partially in the Δfcr2 mutant. WE synthesis was inhibited in both Δfcr mutants. The Δfcr mutants exhibited faster growth rates, an increased uptake of (14)C-glycerol suggesting increased permeability of the cell wall, increased metabolic activity levels and impaired phenotypic antibiotic tolerance under dormancy-inducing combined multiple stress conditions. Complementation of the mutants did not restore the development of antibiotic tolerance to wild-type levels. Transcript analysis of Δfcr mutants showed upregulation of genes involved in energy generation and transcription, indicating the inability of the mutants to become dormant. Our results indicate that the fcr1 and fcr2 gene products are involved in WE synthesis under in vitro dormancy-inducing conditions and that WE play a critical role in reaching a dormant state. Drugs targeted against the Mtb reductases may inhibit its ability to go into dormancy and therefore increase susceptibility of Mtb to currently used antibiotics thereby enhancing clearance of the pathogen from patients.


Assuntos
Ésteres/química , Mycobacterium tuberculosis/metabolismo , Acil Coenzima A/química , Aldeído Redutase/genética , Aldeídos/química , Sequência de Aminoácidos , Antibacterianos/farmacologia , Clonagem Molecular , Resistência Microbiana a Medicamentos , Escherichia coli/genética , Ácidos Graxos/química , Álcoois Graxos/química , Teste de Complementação Genética , Glicerol/química , Humanos , Lipídeos/química , Modelos Químicos , Dados de Sequência Molecular , Mutação , Fases de Leitura Aberta , Homologia de Sequência de Aminoácidos
5.
Peptides ; 30(12): 2161-7, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19666067

RESUMO

The effects of various antimicrobial peptides (AMPs) on disrupting the hemagglutinating ability of cellular components of the putative oral pathogen Porphyromonas gingivalis were examined. AMP inhibition of P. gingivalis 381-induced hemagglutination using vesicles (VES) or outer membrane (OM) preparations was determined within standardized hemagglutination assays using various mammalian erythrocytes. A synthetic decapeptide (KSL-W) and its truncated peptide analogs were evaluated and compared with selected classes of AMPs derived from naturally occurring innate defense peptides. All tested AMPs were effective in disrupting P. gingivalis-induced hemagglutination among tested erythrocytes, with the exception of magainin I and the truncated KSL-W analogs. LL-37 was generally the most potent followed by histatin 5. The synthetic decapeptide (KSL-W) was found to be similar to the histatin 8 peptide in terms of inhibitory effect. In addition, co-application assays (with selected oral-related AMPs+/-KSL-W) were employed to determine if co-application procedures would improve hemagglutination abrogation above that of oral-related AMPs alone. These experiments revealed that the KSL-W peptide improved hemagglutination inhibition above that of each of the oral-related peptides (histatin 5 and 8, LL-37) alone. Among mammalian erythrocytes, significant peptide-induced hemagglutination was observed for the cathelicidin class AMPs, LL-37 and indolicidin (>or=25 and >or=100 microM respectively). In contrast, KSL-W did not induce erythrocyte agglutination throughout any concentration range tested (0.1-1000 microM). Our results suggest that several AMPs are effective in disrupting P. gingivalis 381-induced hemagglutination and that the co-application of a small, synthetically derived peptide may serve to augment the role of local host AMPs engaged in innate defense.


Assuntos
Anti-Infecciosos/farmacologia , Hemaglutinação/efeitos dos fármacos , Peptídeos/farmacologia , Porphyromonas gingivalis/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Anti-Infecciosos/síntese química , Anti-Infecciosos/química , Eritrócitos/microbiologia , Humanos , Dados de Sequência Molecular , Peptídeos/síntese química , Peptídeos/química , Coelhos , Ovinos
6.
PLoS One ; 4(6): e6077, 2009 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-19562030

RESUMO

BACKGROUND: Mycobacterium tuberculosis (Mtb) becomes dormant and phenotypically drug resistant when it encounters multiple stresses within the host. Inability of currently available drugs to kill latent Mtb is a major impediment to curing and possibly eradicating tuberculosis (TB). Most in vitro dormancy models, using single stress factors, fail to generate a truly dormant Mtb population. An in vitro model that generates truly dormant Mtb cells is needed to elucidate the metabolic requirements that allow Mtb to successfully go through dormancy, identify new drug targets, and to screen drug candidates to discover novel drugs that can kill dormant pathogen. METHODOLOGY/PRINCIPAL FINDINGS: We developed a novel in vitro multiple-stress dormancy model for Mtb by applying combined stresses of low oxygen (5%), high CO(2) (10%), low nutrient (10% Dubos medium) and acidic pH (5.0), conditions Mtb is thought to encounter in the host. Under this condition, Mtb stopped replicating, lost acid-fastness, accumulated triacylglycerol (TG) and wax ester (WE), and concomitantly acquired phenotypic antibiotic-resistance. Putative neutral lipid biosynthetic genes were up-regulated. These genes may serve as potential targets for new antilatency drugs. The triacylglycerol synthase1 (tgs1) deletion mutant, with impaired ability to accumulate TG, exhibited a lesser degree of antibiotic tolerance and complementation restored antibiotic tolerance. Transcriptome analysis with microarray revealed the achievement of dormant state showing repression of energy generation, transcription and translation machineries and induction of stress-responsive genes. We adapted this model for drug screening using the Alamar Blue dye to quantify the antibiotic tolerant dormant cells. CONCLUSIONS/SIGNIFICANCE: The new in vitro multiple stress dormancy model efficiently generates Mtb cells meeting all criteria of dormancy, and this method is adaptable to high-throughput screening for drugs that can kill dormant Mtb. A critical link between storage-lipid accumulation and development of phenotypic drug-resistance in Mtb was established. Storage lipid biosynthetic genes may be appropriate targets for novel drugs that can kill latent Mtb.


Assuntos
Regulação da Expressão Gênica , Lipídeos/química , Testes de Sensibilidade Microbiana/métodos , Mycobacterium tuberculosis/metabolismo , Análise por Conglomerados , Corantes/farmacologia , Regulação para Baixo , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Oxazinas/farmacologia , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica , Xantenos/farmacologia
7.
FEMS Microbiol Lett ; 267(1): 121-8, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17156119

RESUMO

The lipids located in the outer layer of Mycobacterium tuberculosis, which include sulfolipid, phthiocerol dimycocerosate (PDIM), diacyltrehalose, and polyacyltrehalose, may play a role in host-pathogen interactions. These lipids were purified using thin-layer chromatography, and their ability to induce proinflammatory cytokines in human monocytes and in a human acute monocytic leukemia cell line (THP-1) was examined. None of the lipids tested induced significant interleukin (IL)-12p40 or tumor necrosis factor (TNF)-alpha production in monocytic cells. Diacyltrehalose significantly inhibited lipopolysaccharide- and M. tuberculosis-induced IL-12p40, TNF-alpha, and IL-6 productions in human monocytes, whereas other lipids had no effect. However, diacyltrehalose was unable to inhibit peptidoglycan-induced IL-12p40 production. These results suggest that diacyltrehalose is a mycobacterial factor capable of modulating host immune responses.


Assuntos
Citocinas/biossíntese , Lipídeos/imunologia , Monócitos/imunologia , Mycobacterium tuberculosis/imunologia , Trealose/análogos & derivados , Trealose/imunologia , Linhagem Celular Tumoral , Células Cultivadas , Cromatografia em Camada Fina , Humanos , Subunidade p40 da Interleucina-12/biossíntese , Interleucina-6/biossíntese , Lipídeos/isolamento & purificação , Mycobacterium tuberculosis/química , Trealose/isolamento & purificação , Fator de Necrose Tumoral alfa/biossíntese
8.
Microbiology (Reading) ; 152(Pt 9): 2717-2725, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16946266

RESUMO

Mycobacterium tuberculosis under stress stores triacylglycerol (TG). There are 15 genes in M. tuberculosis that belong to a novel family of TG synthase genes (tgs), but it is not known which of them is responsible for this accumulation of TG. In this paper, it is reported that M. tuberculosis H37Rv accumulated TG under acidic, static or hypoxic growth conditions, or upon treatment with NO, whereas TG accumulation was drastically reduced in the tgs1 (Rv3130c) disrupted mutant. Complementation with tgs1 restored this TG accumulation. C(26) was a major fatty acid in this TG, indicating that the TGS1 gene product uses C(26) fatty acid, which is known to be produced by the mycobacterial fatty acid synthase. TGS1 expressed in Escherichia coli preferred C(26 : 0)-CoA for TG synthesis. If TG storage is needed for the long-term survival of M. tuberculosis under dormant conditions, the tgs1 product could be a suitable target for antilatency drugs.


Assuntos
Diacilglicerol O-Aciltransferase/genética , Genes Bacterianos , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Triglicerídeos/biossíntese , Escherichia coli/genética , Concentração de Íons de Hidrogênio , Hipóxia , Mutação , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/crescimento & desenvolvimento , Óxido Nítrico/farmacologia , Triglicerídeos/genética
9.
J Biol Chem ; 281(7): 3866-75, 2006 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-16354661

RESUMO

Twenty-four putative lipase/esterase genes of Mycobacterium tuberculosis H37Rv were expressed in Escherichia coli and assayed for long-chain triacylglycerol (TG) hydrolase activity. We show here that the product of Rv3097c (LIPY) hydrolyzed long-chain TG with high specific activity. LIPY was purified after solubilization from inclusion bodies; the enzyme displayed a K(m) of 7.57 mM and V(max) of 653.3 nmol/mg/min for triolein with optimal activity between pH 8.0 and pH 9.0. LIPY was inhibited by active serine-directed reagents and was inactivated at temperatures above 37 degrees C. Detergents above their critical micellar concentrations and divalent cations inhibited the activity of LIPY. The N-terminal half of LIPY showed sequence homology with the proline glutamic acid-polymorphic GC-rich repetitive sequences protein family of M. tuberculosis. The C-terminal half of LIPY possesses amino acid domains homologous with the hormone-sensitive lipase family and the conserved active-site motif GDSAG. LIPY shows low sequence identity with the annotated lipases of M. tuberculosis and with other bacterial lipases. We demonstrate that hypoxic cultures of M. tuberculosis, which had accumulated TG, hydrolyzed the stored TG when subjected to nutrient starvation. Under such conditions, lipY was induced more than all lipases, suggesting a central role for it in the utilization of stored TG. We also show that in the lipY-deficient mutant, TG utilization was drastically decreased under nutrient-deprived condition. Thus, LIPY may be responsible for the utilization of stored TG during dormancy and reactivation of the pathogen.


Assuntos
Proteínas de Bactérias/fisiologia , Hidrolases de Éster Carboxílico/fisiologia , Lipase/fisiologia , Mycobacterium tuberculosis/metabolismo , Triglicerídeos/metabolismo , Fatores de Virulência/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/isolamento & purificação , Clonagem Molecular , Indução Enzimática , Lipase/química , Lipase/genética , Lipase/isolamento & purificação , Dados de Sequência Molecular , Fatores de Virulência/química , Fatores de Virulência/genética , Fatores de Virulência/isolamento & purificação
10.
J Bacteriol ; 186(15): 5017-30, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15262939

RESUMO

Mycobacterium tuberculosis enters the host by inhalation of an infectious aerosol and replicates in the alveolar macrophages until the host's immune defense causes bacteriostasis, which leads the pathogen to go into nonreplicative drug-resistant dormancy. The dormant pathogen can survive for decades till the host's immune system is weakened and active tuberculosis develops. Even though fatty acids are thought to be the major energy source required for the persistence phase, the source of fatty acids used is not known. We postulate that the pathogen uses triacylglycerol (TG) as a storage form of fatty acids. Little is known about the biosynthesis of TG in M. tuberculosis. We show that 15 mycobacterial genes that we identified as putative triacylglycerol synthase (tgs) when expressed in Escherichia coli showed TGS activity, and we report some basic catalytic characteristics of the most active enzymes. We show that several tgs genes are induced when the pathogen goes into the nonreplicative drug-resistant state caused by slow withdrawal of O(2) and also by NO treatment, which is known to induce dormancy-associated genes. The gene (Rv3130c) that shows the highest TGS activity when expressed in E. coli shows the highest induction by hypoxia and NO treatment. Biochemical evidence shows that TG synthesis and accumulation occur under both conditions. We conclude that TG may be a form of energy storage for use during long-term dormancy. Therefore, TG synthesis may be an appropriate target for novel antilatency drugs that can prevent the organism from surviving dormancy and thus assist in the control of tuberculosis.


Assuntos
Aciltransferases/biossíntese , Regulação Bacteriana da Expressão Gênica , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/crescimento & desenvolvimento , Triglicerídeos/biossíntese , Aciltransferases/genética , Anaerobiose , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Meios de Cultura , Diacilglicerol O-Aciltransferase , Indução Enzimática , Escherichia coli/enzimologia , Escherichia coli/genética , Mycobacterium tuberculosis/fisiologia , Óxido Nítrico/farmacologia
11.
J Biosci ; 28(5): 637-46, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14517367

RESUMO

Terpenoids are known to have many important biological and physiological functions. Some of them are also known for their pharmaceutical significance. In the late nineties after the discovery of a novel non-mevalonate (non-MVA) pathway, the whole concept of terpenoid biosynthesis has changed. In higher plants, the conventional acetate-mevalonate (Ac-MVA) pathway operates mainly in the cytoplasm and mitochondria and synthesizes sterols, sesquiterpenes and ubiquinones predominantly. The plastidic non-MVA pathway however synthesizes hemi-, mono-, sesqui- and di-terpenes, along with carotenoids and phytol chain of chlorophyll. In this paper, recent developments on terpenoids biosynthesis are reviewed with respect to the non-MVA pathway.


Assuntos
Ácido Mevalônico/metabolismo , Plantas/metabolismo , Terpenos/metabolismo , Acetatos/metabolismo , Eritritol/química , Eritritol/metabolismo , Plantas/genética , Terpenos/química
12.
Microbiology (Reading) ; 149(Pt 7): 1837-1847, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12855735

RESUMO

The cell envelope of pathogenic mycobacteria is highly distinctive in that it contains a large number of structurally related very long multiple methyl-branched fatty acids. These complex molecules are thought to play important roles in cell envelope organization and virulence. The genetic and enzymic characterization of the polyketide synthase Mas, which is responsible for the synthesis of one such family of fatty acids (the mycocerosic acids), paved the way towards the identification of other enzymes involved in the synthesis of methyl-branched fatty acids in M. tuberculosis. In an effort to elucidate the origin of these complex fatty acids and their possible involvement in pathogenesis, the two mas-like polyketide genes pks5 and pks7 were disrupted in M. tuberculosis and the effects of their inactivation on fatty acid composition and virulence were analysed. While the disruption of pks7 resulted in a mutant deficient in the production of phthiocerol dimycocerosates, the cell envelope composition of the pks5 mutant was found to be identical to that of the wild-type parental strain M. tuberculosis H37Rv. Interestingly, both the pks5 and pks7 mutants displayed severe growth defects in mice.


Assuntos
Complexos Multienzimáticos/genética , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/patogenicidade , Animais , Sequência de Bases , Células Cultivadas , DNA Bacteriano/genética , Ácidos Graxos/biossíntese , Ácidos Graxos/química , Feminino , Regulação Bacteriana da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Genes Bacterianos , Macrófagos/microbiologia , Lipídeos de Membrana/química , Camundongos , Camundongos Endogâmicos BALB C , Complexos Multienzimáticos/metabolismo , Mutação , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/crescimento & desenvolvimento , Virulência/genética
13.
J Bacteriol ; 185(15): 4620-5, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12867474

RESUMO

We show that the disruption of one of the mycocerosic acid synthase (mas)-like genes, msl5 (pks8 plus pks17) in Mycobacterium tuberculosis H37Rv generates a mutant incapable of producing monomethyl branched unsaturated C(16) to C(20) fatty acids that are minor constituents of acyltrehaloses and sulfolipids. The msl5 mutation did not cause any significant change in the acyl lipid composition and also did not affect growth in culture, in mouse alveolar macrophage cell line MH-S, or in the murine lung.


Assuntos
Acil Coenzima A/metabolismo , Aciltransferases/metabolismo , Ácidos Graxos Insaturados/biossíntese , Mycobacterium tuberculosis/patogenicidade , Tuberculose Pulmonar/microbiologia , Aciltransferases/genética , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Linhagem Celular , Ácidos Graxos Insaturados/química , Pulmão/microbiologia , Macrófagos Alveolares/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Virulência
14.
J Biosci ; 28(4): 479-87, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12799494

RESUMO

Palmarosa inflorescence with partially opened spikelets is biogenetically active to incorporate [U-14C]sucrose into essential oil. The percent distribution of 14C-radioactivity incorporated into geranyl acetate was relatively higher as compared to that in geraniol, the major essential oil constituent of palmarosa. At the partially opened spikelet stage, more of the geraniol synthesized was acetylated to form geranyl acetate, suggesting that majority of the newly synthesized geraniol undergoes acetylation, thus producing more geranyl acetate. In vitro development of palmarosa inflorescence, fed with [U-14C]sucrose, resulted in a substantial reduction in percent label from geranyl acetate with a corresponding increase in free geraniol, thereby suggesting the role of an esterase in the production of geraniol from geranyl acetate. At time course measurement of 14CO2 incorporation into geraniol and geranyl acetate substantiated this observation. Soluble acid invertase was the major enzyme involved in the sucrose breakdown throughout the inflorescence development. The activities of cell wall bound acid invertase, alkaline invertase and sucrose synthase were relatively lower as compared to the soluble acid invertase. Sucrose to reducing sugars ratio decreased till fully opened spikelets stage, concomitant with increased acid invertase activity and higher metabolic activity. The phenomenon of essential oil biosynthesis has been discussed in relation to changes in these physiological parameters.


Assuntos
Cymbopogon/metabolismo , Sacarose/metabolismo , Terpenos/metabolismo , Monoterpenos Acíclicos , Fenômenos Bioquímicos , Bioquímica , Metabolismo dos Carboidratos , Esterases/metabolismo , Hidrólise , Fenômenos Fisiológicos Vegetais , Fatores de Tempo
15.
Infect Immun ; 71(7): 3794-801, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12819062

RESUMO

The cell wall lipids in Mycobacterium tuberculosis are probably involved in pathogenesis. The largest open reading frame in the genome of M. tuberculosis H37Rv, pks12, is unique in that it encodes two sets of domains needed to produce fatty acids. A pks12-disrupted mutant was produced, and disruption was confirmed by both PCR analysis and Southern blotting. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that a 430-kDa protein band present in the wild type was missing in the mutant. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MS) and liquid chromatography (LC)-MS analysis of tryptic peptides showed that 54 peptides distributed throughout this protein matched the pks12-encoded sequence. Biochemical analysis using [1-(14)C]propionate as the radiotracer showed that the pks12 mutant was deficient in the synthesis of dimycocerosyl phthiocerol (DIM). SDS-PAGE, immunoblot analysis of proteins, and analysis of fatty acids showed that the mutant can produce mycocerosic acids. Thus, the pks12 gene is probably involved in the synthesis of phthiocerol, the diol required for DIM synthesis. Growth of the pks12 mutant was attenuated in mouse alveolar macrophage cell line MH-S, and the virulence of the mutant in vivo was highly attenuated in a murine model. Thus, pks12 probably participates in DIM production and its expression is involved in pathogenesis.


Assuntos
Genoma Bacteriano , Lipídeos/biossíntese , Mycobacterium tuberculosis/genética , Fases de Leitura Aberta , Animais , Linhagem Celular , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidade , Propionatos/metabolismo , Recombinação Genética , Virulência
16.
Phytochemistry ; 63(3): 257-64, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12737976

RESUMO

Total incorporation of exogenously administered [2-14C]acetate into essential oil of palmarosa (Cymbopogon martinii) was found to be relatively higher than that of either [U-14C]sucrose or [U-14C]glucose during inflorescence development. Among the major essential oil constituents, biogenesis of geranyl acetate was much higher than that of geraniol. Alkaline hydrolysis of [14C]labeled geranyl acetate revealed that the majority of the label incorporated into geranyl acetate was present in the geraniol moiety, indicating that only newly synthesized geraniol gets acetylated to form geranyl acetate. Geranyl acetate cleaving esterase (GAE) activity followed a similar pattern during both in vivo and in vitro inflorescence development, with maximum activity at immature inflorescence stages, suggesting the involvement of GAE in geraniol production during inflorescence development. Five esterase isozymes (Est-A to E) were detected in the enzymic fraction of palmarosa inflorescence and all showed GAE activity, with Est-B being significantly increased during inflorescence development. The role of GAE in geraniol production and improving the palmarosa oil quality is discussed.


Assuntos
Acetilesterase/metabolismo , Poaceae/metabolismo , Terpenos/metabolismo , Acetatos/metabolismo , Acetilesterase/isolamento & purificação , Monoterpenos Acíclicos , Radioisótopos de Carbono , Concentração de Íons de Hidrogênio , Hidrólise , Isoenzimas/isolamento & purificação , Isoenzimas/metabolismo , Óleos Voláteis/metabolismo , Poaceae/crescimento & desenvolvimento
17.
J Bacteriol ; 185(10): 2999-3008, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12730158

RESUMO

Tuberculosis is one of the leading preventable causes of death. Emergence of drug-resistant tuberculosis makes the discovery of new targets for antimycobacterial drugs critical. The unique mycobacterial cell wall lipids are known to play an important role in pathogenesis, and therefore the genes responsible for their biosynthesis offer potential new targets. To assess the possible role of some of the genes potentially involved in cell wall lipid synthesis, we disrupted a mas-like gene, msl7, and a chalcone synthase-like gene, pks10, with phage-mediated delivery of the disruption construct, in which the target gene was disrupted by replacement of an internal segment with the hygromycin resistance gene (hyg). Gene disruption by allelic exchange in the case of each disruptant was confirmed by PCR and Southern blot analyses. Neither msl7 nor pks10 mutants could produce dimycocerosyl phthiocerol, although both could produce mycocerosic acids. Thus, it is concluded that these gene products are involved in the biosynthesis of phthiocerol. Both mutants were found to be attenuated in a murine model, supporting the hypothesis that dimycocerosyl phthiocerol is a virulence factor and thus the many steps involved in its biosynthesis offer potential novel targets for antimycobacterial therapy.


Assuntos
Aciltransferases/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Lipídeos/biossíntese , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/patogenicidade , Virulência/genética , Aciltransferases/metabolismo , Animais , Antígenos de Bactérias/biossíntese , Radioisótopos de Carbono , Células Cultivadas , Feminino , Engenharia Genética/métodos , Lipídeos/análise , Lipídeos/química , Macrófagos Alveolares/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium tuberculosis/metabolismo , Propionatos/metabolismo , Recombinação Genética , Tuberculose/microbiologia
18.
Mol Microbiol ; 45(5): 1451-9, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12207710

RESUMO

Cell wall lipids of Mycobacterium tuberculosis containing multiple methylbranched fatty acids play critical roles in pathogenesis and thus offer targets for new antimycobacterial drugs. Mycocerosicacid synthase gene (mas) encodes the enzyme that produces one class of such acids. Seven mas-like genes (msls) were identified in the genome. One of them, msl3, originally annotated as two separate genes, pks 3 and pks 4, is now shown to constitute a single open reading frame, which encodes a 220.3 kDa protein. Msl3 was disrupted using a phage mediated delivery system and the gene replacement in the mutant was confirmed by polymerase chain reaction analysis of the flanking regions of the introduced disrupted gene and by Southern analysis. Biochemical analysis showed that the msl3 mutant does not produce mycolipanoic acids and mycolipenic(phthienoic) acids, the major constituents of polyacyl trehaloses and thus lacks this cell wall lipid, but synthesizes all of the other classes of lipids. The absence of the major acyl chains that anchor the surface-exposed acyltrehaloses causes a novel growth morphology; the cells stick to each other, most probably via the intercellular interaction between the exposed hydrophobic cell surfaces, manifesting a bead-like growth morphology without affecting the overall growth rate.


Assuntos
Aciltransferases/genética , Aciltransferases/metabolismo , Ácidos Graxos/biossíntese , Genes Bacterianos , Glicolipídeos/biossíntese , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Aderência Bacteriana , Sequência de Bases , Parede Celular/metabolismo , DNA Bacteriano/genética , Lipídeos de Membrana/biossíntese , Modelos Biológicos , Mutagênese , Mutação , Mycobacterium tuberculosis/citologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...