RESUMO
In recent years, significant progress has been made in the fields of nonlinear and ultrafast optics, offering exciting opportunities for terahertz (THz) science and technology. In this study, we present a novel design of a SSBCD (Solid-State-Biased Coherent Detection) device for the coherent detection of ultra-broadband THz pulses. By increasing the number of cross-fingers, we have effectively enhanced the sensitivity of the SSBCD device. The design of stepped and circular structures has successfully expanded the detectable electric field directions while reducing the dependence on the incident field direction. As a result, we have achieved ultra-broadband detection with a high dynamic range and a wide detection angle. These research findings lay a critical foundation for the integration of solid-state ultra-broadband detection into compact and miniaturized terahertz systems.
RESUMO
The transient photocurrent is one of the key parameters of the spatial radiation effect of photoelectric devices, and the energy level defect affects the transient photocurrent. In this paper, by studying the deep level transient spectrum of a self-designed Schottky diode, the defect properties of the interface region of the anode metal AlCu and Si caused by high-temperature annealing at 150 â, 200 â and 300 â for 1200 h have been quantitatively analyzed. The study shows that the defect is located at the position of + 0.41 eV on the valence band, the concentration is 2.8 [Formula: see text] 1013/cm2, and the capture cross section is [Formula: see text] = 8.5 [Formula: see text] 1017. The impurity energy level mainly comes from the diffusion of Al atom in anode metal. We found that the defect did not cause the electrical performance degradation and obvious morphology change of the device, but the transient photocurrent increased significantly. The reason is that the high temperature treatment results in a growth in the density of states at the interface between AlCu-Si. The more mismatched dislocations and recombination center increased the reverse current of the heterojunction. The above view is proved by the TCAD simulation test.
RESUMO
The coronavirus disease (COVID-19) is a novel emerging infectious disease spreading worldwide. To further understand the disease, we compared its clinical characteristics, symptoms and outcomes by gender. In an analysis of public surveillance data of Taiwan from January 21 to April 18, 2020, a total of 398 patients were diagnosed with COVID-19 by the detection of severe acute respiratory syndrome coronavirus 2 in pharynx swabs. We divided the patients into two groups: men and women. The associated data were collected, and multivariate comparisons of radiographic infiltration were conducted to analyse the gender-based differences. The mean incubation period was 5.4 ± 5 days, and the incubation period in men was 3.2 days longer than that in women (8 ± 8.1 vs. 4.8 ± 3, p = 0.05). The male patients with COVID-19 with infiltration in chest X-rays (CXR) were 12 years older than their female counterparts. The mortality rate in the male patients with COVID-19 was 6.4-fold higher than that in the female patients (3.2% vs. 0.5%, p < 0.05). The patients with comorbidities of diabetes mellitus and hypertension were vulnerable to infiltration in CXR and the patients with COVID-19 who had infiltration in CXR easily ended up with intubation, intensive care unit admission and mortality. Moreover, female patients with COVID-19 who had fever, cough and dyspnoea were susceptible to infiltration in CXR. Irrespective of whether the cases were imported female from Europe, America or Asia, indigenous male, the factors associated with death in patients with severe COVID-19 were male sex, elderly, female with fever, cough, dyspnoea and DM.
RESUMO
Gender inequality has severe consequences on public health in terms of delay in diagnosis of pulmonary tuberculosis (PTB). In order to explore gender-related differences in diagnosis delay, a cross-sectional study of 10 686 patients diagnosed with PTB in Yulin from 1 January 2009 to 31 December 2014 was conducted. Diagnosis delay was categorised into 'short delay' and 'long delay' by four commonly used cut-off points of 14, 30, 60 and 90 days. Logistic regression analysis was used to analyse gender differences in diagnostic delay. Stratified analyses by smear results, age, urban/rural were performed to examine whether the effect persisted across the strata. The median delay was 31 days (interquartile range 13-65). Diagnostic delay in females at cut-off points of 14, 30, 60 and 90 days had odds ratios (OR) of 0.99 (95% CI 0.91-1.09), 1.09 (95% CI 1.01-1.18), 1.15 (95% CI 1.05-1.26) and 1.18 (95% CI 1.06-1.31), respectively, compared with males. Stratified analysis showed that females were associated with increased risk of longer delay among those aged 30-60 years, smear positive and living in the rural areas (P < 0.05). The female-to-male OR increased along with increased delay time. Further inquiry into the underlying reasons for gender differences should be urgently addressed to improve the current situation.
Assuntos
Diagnóstico Tardio/estatística & dados numéricos , Tuberculose Pulmonar/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , China , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , População Rural/estatística & dados numéricos , Fatores Sexuais , Fatores de Tempo , População Urbana/estatística & dados numéricos , Adulto JovemRESUMO
PURPOSE: The purpose of our study was to investigate an underlying mechanism that hydrogen peroxide-induced mitophagy contributed to laryngeal cancer cells survivals under oxidative stress condition. METHODS: Tumor tissue and serum samples were collected from patients with laryngeal cancer. The Hep2 cell, a human laryngeal carcinoma cell, was used in in vitro experiments. The levels of lipid peroxidation were analyzed by ELISA. Knockdown of FUNDC1 was performed by RNAi. The changes of target proteins were determined by qRT-PCR and western blot. The cells were analyzed for changes in proliferation using cell counting kit-8 and mitophagy by the mitochondrial membrane potential assay and transmission electron microscopy. RESULTS: FUNDC1 in laryngeal cancer tissues were relative to the levels of lipid peroxidation in laryngeal cancer patients, which suggested that FUNDC1 was associated with the status of oxidative stress in the laryngeal cancer patients. Hydrogen peroxide significantly induced the elevation of FUNDC1, a mitophagic factor, in a time- and dose-dependent manner in laryngeal cancer cells, which was dependent on ERK signal activation. Knockdown of FUNDC1 by the siRNA attenuated the survival of laryngeal cancer cells under hydrogen peroxide stimulation. Moreover, the elevated FUNDC1 was required for the occurrence of mitophagy under hydrogen peroxide stimulation, which was identified by transmission electron microscopy, the alterations of mitochondrial permeability transition and the specific mitochondrial protein, hsp60. Inhibition of mitophagy with cyclosporine A could also effectively attenuate the laryngeal cancer cells survival under hydrogen peroxide stimulation. CONCLUSIONS: Hydrogen peroxide upregulated the expression of FUNDC1 through the activation of ERK1/2 signal to trigger a mitophagic response, giving laryngeal cancer cells a befit for survival. These findings suggested that FUNDC1 might be a potential target for the treatment of laryngeal cancer accompanied with high lipid peroxidation status.
Assuntos
Regulação Neoplásica da Expressão Gênica , Peróxido de Hidrogênio/farmacologia , Neoplasias Laríngeas/patologia , Peroxidação de Lipídeos , Proteínas de Membrana/metabolismo , Mitocôndrias/patologia , Proteínas Mitocondriais/metabolismo , Mitofagia , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Estudos de Casos e Controles , Sobrevivência Celular , Seguimentos , Humanos , Neoplasias Laríngeas/genética , Neoplasias Laríngeas/metabolismo , Proteínas de Membrana/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Oxidantes/farmacologia , Fosforilação , Prognóstico , Células Tumorais CultivadasRESUMO
The anti-PD-1 antibodies nivolumab and pembrolizumab are active in metastatic melanoma; however, there is limited data on combining anti-PD-1 antibody and radiotherapy (RT). We sought to review clinical outcomes of patients receiving RT and anti-PD-1 therapy. All patients receiving anti-PD-1 antibody and RT for metastatic melanoma were identified. RT and systemic treatment, clinical outcome, and toxicity data were collected. Fifty-three patients were included; 35 patients received extracranial RT and/or intracranial stereotactic radiosurgery (SRS) and 21 received whole brain radiotherapy (WBRT) (three of whom also received SRS/extracranial RT). Patients treated with extracranial RT or SRS received treatment either sequentially (RT then anti-PD-1, n = 11), concurrently (n = 16), or concurrent "salvage" treatment to lesions progressing on anti-PD-1 therapy (n = 15). There was no excessive anti-PD-1 or RT toxicity observed in patients receiving extracranial RT. Of six patients receiving SRS, one patient developed grade 3 radiation necrosis. In 21 patients receiving WBRT, one patient developed Stevens-Johnson syndrome, one patient developed acute neurocognitive decline, and one patient developed significant cerebral edema in the setting of disease. Response in irradiated extracranial/intracranial SRS lesions was 44% for sequential treatment and 64% for concurrent treatment (p=0.448). Likewise there was no significant difference between sequential or concurrent treatment in lesional response of non-irradiated lesions. For progressing lesions subsequently irradiated, response rate was 45%. RT and anti-PD-1 antibodies can be safely combined, with no detectable excess toxicity in extracranial sites. WBRT and anti-PD-1 therapy is well tolerated, although there are rare toxicities and the role of either anti-PD-1 or WBRT in the etiology of these is uncertain.
RESUMO
Arsenic is a notorious environmental toxicant known as both a carcinogen and an atherogen in human beings, but the pathogenic mechanisms are not completely understood. In cell culture studies, trivalent arsenic enhanced oxidative stress in a variety of mammalian cells, and this association may be closely associated with the development of arsenic-related diseases. To investigate the effect of arsenic exposure on oxidative stress in humans, we conducted a population study to determine the relationships of blood arsenic to reactive oxidants and antioxidant capacity at the individual level. We recruited 64 study subjects ages 42-75 years from residents of the Lanyang Basin on the northeast coast of Taiwan, where arsenic content in well water varies from 0 to > or = 3,000 microg/L. We used a chemiluminescence method, with lucigenin as an amplifier for measuring superoxide, to measure the plasma level of reactive oxidants. We used the azino-diethyl-benzthiazoline sulphate method to determine the antioxidant capacity level in plasma of each study subject. We determined arsenic concentration in whole blood by hydride formation with an atomic absorption spectrophotometer. The average arsenic concentration in whole blood of study subjects was 9.60 +/- 9.96 microg/L (+/- SD) with a range from 0 to 46.50 microg/L. The level of arsenic concentration in whole blood of study subjects showed a positive association with the level of reactive oxidants in plasma (r = +0.41, p = 0.001) and an inverse relationship with the level of plasma antioxidant capacity (r = -0.30, p = 0.014). However, we found no significant association (p = 0.266) between levels of plasma reactive oxidants and antioxidant capacity. Our results also show that the lower the primary arsenic methylation capability, the lower the level of plasma antioxidant capacity (p = 0.029). These results suggest that ingestion of arsenic-contaminated well water may cause deleterious effects by increasing the level of reactive oxidants and decreasing the level of antioxidant capacity in plasma of individuals. Persistent oxidative stress in peripheral blood may be a mechanism underlying the carcinogenesis and atherosclerosis induced by long-term arsenic exposure.
Assuntos
Antioxidantes/farmacologia , Arsênio/efeitos adversos , Arsênio/sangue , Poluentes Ambientais/efeitos adversos , Poluentes Ambientais/sangue , Estresse Oxidativo , Espécies Reativas de Oxigênio/sangue , Adulto , Idoso , Arteriosclerose/fisiopatologia , Feminino , Humanos , Masculino , Metilação , Pessoa de Meia-Idade , Neoplasias/fisiopatologia , TaiwanRESUMO
Full-length cDNA clones encoding deoxyhypusine synthase (DHS) and eucaryotic initiation factor 5A (eIF-5A) have been isolated from a cDNA expression library prepared from tomato leaves (Lycopersicon esculentum, cv. Match) exposed to environmental stress. DHS mediates the first of two enzymatic reactions that activate eIF-5A by converting a conserved lysine to the unusual amino acid, deoxyhypusine. Recombinant protein obtained by expressing tomato DHS cDNA in Escherichia coli proved capable of carrying out the deoxyhypusine synthase reaction in vitro in the presence of eIF-5A. Of particular interest is the finding that DHS mRNA and eIF-5A mRNA show a parallel increase in abundance in senescing tomato flowers, senescing tomato fruit, and environmentally stressed tomato leaves exhibiting programmed cell death. Western blot analyses indicated that DHS protein also increases at the onset of senescence. It is apparent from previous studies with yeast and mammalian cells that hypusine-modified eIF-5A facilitates the translation of a subset of mRNAs mediating cell division. The present study provides evidence for senescence-induced DHS and eIF-5A in tomato tissues that may facilitate the translation of mRNA species required for programmed cell death.
Assuntos
Regulação da Expressão Gênica de Plantas , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Fatores de Iniciação de Peptídeos/genética , Proteínas de Ligação a RNA , Solanum lycopersicum/enzimologia , Solanum lycopersicum/genética , Envelhecimento , Sequência de Aminoácidos , Archaea/genética , Sequência de Bases , Sequência Conservada , DNA Complementar , Fungos/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Biblioteca Gênica , Humanos , Solanum lycopersicum/crescimento & desenvolvimento , Lisina , Dados de Sequência Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Fatores de Iniciação de Peptídeos/metabolismo , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Plantas/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Fator de Iniciação de Tradução Eucariótico 5ARESUMO
A chiral gas chromatographic method with FID was developed for the determination of S- and R-mephenytoin in human urine. The assay is linear from 25 to 800 ng/mL for each enantiomer and the limit of detection and limit of quantitation were 12 and 25ng/mL for each enantiomer, respectively. The method affords average recoveries of 74.41 +/- 3.93% and 73.78 +/- 3.02% for S- and R-mephenytoin, respectively. The method allows the phenotype study of CYP2C19 in Chinese subjects. The phenotype pattern of 90 Chinese volunteers was determined, in which 26 volunteers received phenotyping and genotyping tests. The results of phenotype analysis showed that the interindividual variation was marked. The mephenytoin S/R enantiomeric ratios in urine of 11 volunteers were > or = 0.95 and identified as poor metabolizers. The frequency of poor metabolizers was 12.2% in the Chinese subjects tested. A good relationship between phenotype and genotype analysis of CYP2C19 was observed.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Povo Asiático/genética , Cromatografia Gasosa/métodos , Sistema Enzimático do Citocromo P-450/genética , Mefenitoína/urina , Oxigenases de Função Mista/genética , Calibragem , China , Citocromo P-450 CYP2C19 , Genótipo , Humanos , Mefenitoína/química , Fenótipo , Polimorfismo Genético , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , EstereoisomerismoRESUMO
The Erh-Ren River is one of the most polluted rivers in Taiwan. Although its flow rate is relatively low, the rate is still beyond the capacity of any traditional water treatment facility. A pilot-scale constructed wetland (CW) is the attempt used to purify the highly polluted river water and to collect data for the construction and operation of a full-scale system in the future. This article reports the results from this initial stage of our research work. During the study, the most efficient nutrient removal occurred between April and October. The monthly average removal rates of chemical oxygen demand (COD) ranged from 13-51% of ammonia-N (AN) from 78-100%, and of orthophosphate (OP) from 52-85%. After November, input COD levels increased, and the monthly average removal rates of ammonia-N dropped to 16% and of orthophosphate to 13%. The dramatic changes in removal efficiency suggest that the macrophytes in the CW had a direct influence on the water treatment and that the change of seasons and the quality of the river water inhibited the growth of the macrophytes.
Assuntos
Poluentes Químicos da Água/metabolismo , Amônia/metabolismo , Biodegradação Ambiental , Ecossistema , Água Doce , Organofosfatos/metabolismo , Consumo de Oxigênio , Projetos Piloto , TaiwanRESUMO
A cDNA clone encoding a lipase (lipolytic acyl hydrolase) expressed at the onset of petal senescence has been isolated by screening a cDNA expression library prepared from carnation flowers (Dianthus caryophyllus). The cDNA contains the lipase consensus sequence, ITFAGHSLGA, and encodes a 447-amino acid polypeptide with a calculated molecular mass of 50.2 kDa that appears to be a cytosolic protein. Over-expression of the clone in Escherichia coli yielded a protein of the expected molecular weight that proved capable of deesterifying fatty acids from p-nitrophenylpalmitate, tri-linolein, soybean phospholipid, and Tween in both in vitro and in situ assays of enzyme activity. The abundance of the lipase mRNA increases just as carnation flowers begin to senesce, and expression of the gene is also induced by treatment with ethylene. Southern blot analyses of carnation genomic DNA have indicated that the lipase is a single copy gene. The lipase gene is also expressed in carnation leaves and is up-regulated when the leaves are treated with ethylene. Deesterification of membrane lipids and ensuing loss of membrane structural integrity are well established early events of plant senescence, and the expression pattern of this lipase gene together with the lipolytic activity of its cognate protein indicate that it plays a fundamentally central role in mediating the onset of senescence.
Assuntos
Etilenos/farmacologia , Lipase/genética , Reguladores de Crescimento de Plantas/farmacologia , Plantas/enzimologia , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA de Plantas , Expressão Gênica , Dados de Sequência Molecular , Desenvolvimento Vegetal , Plantas/efeitos dos fármacosRESUMO
BACKGROUND: Streptococcus pneumoniae is the cause of significant preventable morbidity and mortality each year, especially among the elderly. This study evaluated the effectiveness of a three-step strategy to improve pneumococcal vaccination rates in patients ages 65 and older. METHODS: We obtained a baseline vaccination rate by chart review of a randomized list of patients ages 65 and older. Interventions that included physician education, a system of office prompts, and patient education were instituted for 1 year. We performed a second chart review to determine the success of the intervention. RESULTS: Vaccination rates increased significantly from 56.7% to 75.8%. No significant difference in initial vaccination rates between men and women was found. Although rates improved for both men and women, only the increase in vaccination for men was significant. CONCLUSIONS: This study shows that an easy and inexpensive intervention can substantially impact pneumococcal vaccination rates. Specifically, a three-step approach that combines provider education, office prompts, and patient education has proven effective.
Assuntos
Vacinas Bacterianas/administração & dosagem , Programas de Imunização/métodos , Infecções Pneumocócicas/prevenção & controle , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Programas de Imunização/normas , Masculino , Pessoa de Meia-Idade , Guias de Prática Clínica como AssuntoRESUMO
A cDNA clone encoding a lipase that is up-regulated in senescing leaves and flower petals has been isolated by screening an expression library. The abundance of the lipase mRNA increases as flowers and leaves begin to senesce, and expression of the gene is also induced by treatment with ethylene. Transgenic Arabidopsis plants in which levels of the senescence-induced lipase protein have been reduced show delayed leaf senescence.
Assuntos
Arabidopsis/enzimologia , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lipase/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Clonagem Molecular , DNA Complementar , Regulação da Expressão Gênica no Desenvolvimento , Biblioteca Gênica , Lipase/metabolismo , Folhas de Planta/fisiologia , Caules de Planta/fisiologia , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , RNA Mensageiro/genéticaRESUMO
The aim of this study was to investigate the distribution of a calcium-inhibitable adenylyl cyclase type VI (type VI AC) in the central nervous system using an antiserum directed against the N-terminus of type VI AC. Our results indicate that type VI AC immunoreactivity is generally expressed in many brain regions with different levels of intensity. Most interestingly, the majority of the detected type VI AC immunoreactivity is present in cells of neuronal phenotype. Double immunostaining of type VI AC and markers of various neurotransmitter systems suggest that type VI AC might participate in regulation of the classical neurotransmitter systems and therefore appeared to play a very important role in the central nervous system.
Assuntos
Adenilil Ciclases/metabolismo , Sistema Nervoso Central/enzimologia , Neurônios/enzimologia , Neurotransmissores/metabolismo , Adenilil Ciclases/genética , Adenilil Ciclases/imunologia , Animais , Encéfalo/enzimologia , Cálcio/metabolismo , Cálcio/farmacologia , Soros Imunes , Imuno-Histoquímica/métodos , Proteínas Associadas aos Microtúbulos/metabolismo , Reação em Cadeia da Polimerase , Coelhos , Ratos , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/metabolismo , Transcrição Gênica , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Exercise has become a vital part of many women's lives. However, theoretic concerns have been raised about the safety of some forms of exercise during pregnancy. Because of the physiologic changes associated with pregnancy, as well as the hemodynamic response to exercise, some precautions should be observed. The physician should screen for any contraindications to exercise and encourage patients to avoid overly vigorous activity, especially in the third trimester, when most pregnant women have a decreased tolerance for weight-bearing exercise. Adequate hydration and appropriate ventilation are important in preventing the possible teratogenic effects of overheating. Pregnant women should avoid exercise that involves the risk of abdominal trauma, falls or excessive joint stress, as in contact sports and vigorous racquet sports. In the absence of any obstetric or medical complications, most women can maintain a regular exercise regimen during pregnancy. Some studies have found a greater sense of well-being, shorter labor and fewer obstetric interventions in physically well-conditioned women as compared with other women.
Assuntos
Exercício Físico , Gravidez , Feminino , Humanos , Educação de Pacientes como Assunto , Gravidez/fisiologia , Materiais de EnsinoRESUMO
Osteochondritis dissecans (OCD) should be considered in young, active patients who have generalized or anterior knee pain. A careful physical exam includes a Wilson test, thigh girth measurements, diagnostic tunnel view radiographs, and other imaging studies as needed for grading and prognosis. Two case reports demonstrate the signs and symptoms of OCD. Treatment by primary care physicians with sports medicine training may be conservative if lesions are medial and in situ and if patients are not skeletally mature; otherwise, referral is advised. Prompt surgical treatment is generally successful.
RESUMO
This article provides the practicing physician with an account of the commonly used ergogenic substances. Specific agents discussed include the following: stimulants, narcotic analgesics, anabolic-androgenic steroids, beta-blockers, diuretics, growth hormone, other peptide hormones, blood doping, and erythropoietin.
Assuntos
Dopagem Esportivo , Antagonistas Adrenérgicos beta/efeitos adversos , Antagonistas Adrenérgicos beta/farmacologia , Anabolizantes/efeitos adversos , Anabolizantes/farmacologia , Analgésicos Opioides/efeitos adversos , Analgésicos Opioides/farmacologia , Animais , Estimulantes do Sistema Nervoso Central/efeitos adversos , Estimulantes do Sistema Nervoso Central/farmacologia , Diuréticos/efeitos adversos , Diuréticos/farmacologia , Dopagem Esportivo/classificação , Dopagem Esportivo/legislação & jurisprudência , Dopagem Esportivo/prevenção & controle , Prescrições de Medicamentos , Eritropoetina/efeitos adversos , Eritropoetina/farmacologia , Hormônio do Crescimento/efeitos adversos , Hormônio do Crescimento/farmacologia , Humanos , Esportes/legislação & jurisprudência , Medicina Esportiva/legislação & jurisprudência , Medicina Esportiva/métodosRESUMO
mRNAs encoding putative oleosins have been detected in the tapetum of developing anthers in Brassica and Arabidopsis, but the authentic proteins have not been previously documented. Antibodies against a synthetic 15-residue polypeptide that represents a portion of the putative tapetum oleosins encoded by two cloned Brassica napus genes were raised. Using these antibodies for immunoblotting after SDS-PAGE of the sporophytic extracts of B. napus developing anthers, two oleosins of approximately 48 and 45 kDa were detected. These two oleosins were judged to be the putative oleosins encoded by cloned Brassica genes because of their identical N-terminal sequences. The two oleosins were present in the anthers only during the developmental stage when the tapetum cells were packed with organelles. A fraction of lowdensity organelles was isolated from the developing anthers by flotation centrifugation. The fraction contained plastoglobule-filled plastids and lipid-containing particles. The structures of these two isolated organelles were similar to those in situ in the tapetum cells. Of subcellular fractions of the anther homogenate, the two oleosins were present exclusively in the low-density organelle fraction. They were absent in the surface fractions of the developing microspores and the mature pollen, although fragmented oleosin molecules were earlier reported to be present on the pollen. By immunocytochemistry, immunogold particles were found largely on the periphery of the plastoglobuli inside the plastids in the tapetum cells. The antibodies also detected oleosins on the surface of storage oil bodies inside the maturing microspores. Apparently, the gametophytic microspore oil-body oleosins share common epitopes at the generally non-conserved C-terminal domain with the sporophytic tapetum oleosins.
Assuntos
Brassica/metabolismo , Regulação da Expressão Gênica de Plantas , Organelas/metabolismo , Proteínas de Plantas/biossíntese , Sequência de Aminoácidos , Brassica/crescimento & desenvolvimento , Fracionamento Celular , Clonagem Molecular , Eletroforese em Gel de Poliacrilamida , Regulação da Expressão Gênica no Desenvolvimento , Genes de Plantas , Microscopia Eletrônica , Dados de Sequência Molecular , Peso Molecular , Organelas/ultraestrutura , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , RNA Mensageiro/biossíntese , Proteínas Recombinantes/biossíntese , Transcrição GênicaRESUMO
The monolayer tapetum cells of the maturing flowers of Brassica napus contain abundant subcellular globuli-filled plastids and special lipid particles, both enriched with lipids that are supposed to be discharged and deposited onto the surface of adjacent maturing pollen. We separated the two organelles by flotation density gradient centrifugation and identified them by electron microscopy. The globuli-filled plastids had a morphology similar to those described in other plant species and tissues. They had an equilibrium density of 1.02 g/cm(3) and contained neutral esters and unique polypeptides. The lipid particles contained patches of osmiophilic materials situated among densely packed vesicles and did not have an enclosing membrane. They exhibited osmotic properties, presumably exerted by the individual vesicles. They had an equilibrium density of 1.05 g/cm(3) and possessed triacylglycerols and unique polypeptides. Several of these polypeptides were identified, by their N-terminal sequences or antibody cross-reactivity, as oleosins, proteins known to be associated with seed storage oil bodies. The morphological and biochemical characteristics of the lipid particles indicate that they are novel organelles in eukaryotes that have not been previously isolated and studied. After lysis of the tapetum cells at a late stage of floral development, only the major plastid neutral ester was recovered, whereas the other abundant lipids and proteins of the two tapetum organelles were present in fragmented forms or absent on the pollen surface.