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1.
Radiother Oncol ; 188: 109861, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37619659

RESUMEN

BACKGROUND: Aside from surgical resection, the only standard of care treatment modality for meningiomas is radiotherapy (RT). Despite this, few studies have focused on identifying clinical covariates associated with failure of fractionated RT following surgical resection (fRT), and the timing of fRT following surgery still remains controversial (adjuvant versus salvage fRT). We assessed the outcomes of the largest, multi-institutional cohort of surgically resected meningiomas treated with subsequent adjuvant and salvage fRT to identify factors associated with local freedom from recurrence (LFFR) over 3-10 years post-fRT and to determine the optimal timing of fRT. METHODS: Patients with intracranial meningiomas who underwent surgery and fRT between 1997 and 2018 were included. Primary endpoints were radiographic recurrence/progression and time to progression from the completion of fRT. RESULTS: 404 meningiomas were included for analysis. Of these, 167 (41.3%) recurred post-fRT. Clinical covariates independently associated with worse PFS post-fRT included receipt of previous RT to the meningioma, having a WHO grade 3 meningioma or recurrent meningioma, the meningioma having a higher MIB1-index or brain invasion on pathology, and older patient age at diagnosis. Subgroup analysis identified higher MIB1-index as a histological factor associated with poorer LFFR in WHO grade 2 meningiomas. 179 patients underwent adjuvant RT shortly after surgery whereas 225 patients had delayed, salvage fRT after recurrence/progression. Following propensity score matching, patients that underwent adjuvant fRT had improved LFFR post-fRT compared to those that received salvage fRT. CONCLUSION: There is a paucity of clinical factors that can predict a meningioma's response to fRT following surgery. Adjuvant fRT may be associated with improved PFS post-fRT compared to salvage fRT. Molecular biomarkers of RT-responsiveness are needed to better inform fRT treatment decisions.

2.
Clin Transl Radiat Oncol ; 41: 100631, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37168253

RESUMEN

Background: Surgery is the primary treatment for most meningiomas. However, primary fractionated radiotherapy (fRT) remains an option for patients with larger meningiomas in challenging anatomic locations or patients at prohibitively high surgical risk. Outcome prediction for these patients is uncertain and cannot be guided by histopathology without available tumor tissue from surgery. Therefore, we aimed to assess the clinical factors that contribute to treatment failure in a large cohort of meningiomas consecutively treated with fRT as primary therapy, with the goal of identifying predictors of response. Methods: Patients treated with primary fRT for intracranial meningiomas from 1998 to 2017 were reviewed. Those who received primary surgical resection, radiosurgery, previous fRT, or had <6 months of clinical follow-up were excluded. We applied logistic regression and Cox regression modeling to ascertain key predictors of treatment failure, progression-free survival (PFS), and adverse events (AE) following fRT. Results: Our cohort included 137 meningiomas, 21 of which progressed after fRT (median PFS 3.45 years). Progressive meningiomas had a larger median gross tumor volume (GTV) compared to those that remained stable (19.1 cm3 vs 9.6 cm3, p = 2.86 × 10-2). GTV > 11.27 cm3 was independently predictive of progression and larger GTV was associated with higher risk of significant (grades 3/4) AE following fRT. Cavernous sinus and optic nerve sheath meningiomas had overall excellent outcomes post-fRT. Conclusions: We present a large cohort of meningiomas treated with primary fRT and find GTV and anatomic location to be key predictors of outcome, adding to the complex treatment considerations for this heterogeneous disease.

3.
Horm Behav ; 156: 105444, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38344953

RESUMEN

This study examined the effect of 6 weeks of supraphysiological nandrolone decanoate (ND) administration in adult mice (7 months) on cognitive function and neuroinflammation during aging. Male C57BL/6 mice were randomized into ND (10 mg·kg-1·wk-1) or control (CTL) groups. Half of the mice were tested at a young (Y) age (ND-Y and CTL-Y), 1 week following final ND administration, while the remaining mice were tested at 16 months (O) (ND-O and CTL-O). Learning and memory were better in young mice compared to older mice, regardless of treatment. ND-O displayed decreased anxiety as compared to all other groups. TNFα and IL1ß expression were higher in older mice, regardless of treatment. ND administration in young mice appeared to attenuate the neuroinflammatory response in aging mice as evidenced by decreased COX2, IL-4 and increased IL-10 expression in ND-O compared to CTL-O. BDNF AR and ER expression increased in ND-O compared to CTL-O. Results of the study indicated that supraphysiological ND administration had no negative effect on learning and memory but may attenuate anxiety in older mice. In addition, ND administration in young adult mice may attenuate the inflammatory response during aging, which may be related to elevations in both AR and ER expression.


Asunto(s)
Anabolizantes , Nandrolona , Masculino , Ratones , Animales , Nandrolona Decanoato , Nandrolona/farmacología , Anabolizantes/farmacología , Factores de Crecimiento Nervioso , Ratones Endogámicos C57BL
5.
Med Pharm Rep ; 95(1): 59-64, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35720244

RESUMEN

Background: Anal fistula is often considered to be a dilemma because of the need to maintain a fine balance between postoperative incontinence and recurrence. We tried to find whether apprehension of causing incontinence should stop us from performing fistulectomy. The aim of this study was to determine whether fistulectomy was associated with increased rate of fecal incontinence and recurrence, compared to other procedures used for the treatment of anal fistula. Methods: It was a prospective, single center, observational study. All patients with anal fistula operated at a tertiary care teaching institute over a period of two years were included in the study. Recurrence rates and fecal incontinence were compared between patients subjected to fistulectomy and other procedures for treatment of fistula in ano. Results: A total of 124 patients with anal fistula were included. 92.8% patients were ≤ 60 years of age with high male preponderance (89.5%). Perineal discharge was the commonest complaint (95.96%). Intersphincteric (47.58%) followed by transphincteric fistulas (45.16%) accounted for the majority of fistulas. Fistulectomy was the most common procedure, performed in 90 (72.58%) patients. Incontinence occurred in 8/90 (8.88%) from the fistulectomy group and 2/34 (5.9%) patients in other surgery group, p=0.726. Recurrence occurred in 8/90 (8.88%) from the fistulectomy group and 8/34 (23.5%) patients from other surgery group, p=0.038. Overall rates of incontinence and recurrence were 8.1% and 12.9% respectively. Conclusion: Fistulectomy, as compared to other procedures, results in less chances of recurrence without compromising continence.

6.
Global Spine J ; 11(1_suppl): 23S-29S, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33890805

RESUMEN

STUDY DESIGN: Narrative review. OBJECTIVES: We aim to describe current progress in the application of artificial intelligence and machine learning technology to provide automated analysis of imaging in patients with spinal disorders. METHODS: A literature search utilizing the PubMed database was performed. Relevant studies from all the evidence levels have been included. RESULTS: Within spine surgery, artificial intelligence and machine learning technologies have achieved near-human performance in narrow image classification tasks on specific datasets in spinal degenerative disease, spinal deformity, spine trauma, and spine oncology. CONCLUSION: Although substantial challenges remain to be overcome it is clear that artificial intelligence and machine learning technology will influence the practice of spine surgery in the future.

7.
Artículo en Inglés | MEDLINE | ID: mdl-26245616

RESUMEN

BACKGROUND: Epilepsy is a common disorder in South Africa and the literature indicates that many patients do not access treatment. The reasons are complex and include a poor knowledge about causes, symptoms, diagnosis and treatment (medical knowledge). This study aimed to assess the medical knowledge of isiZulu-speaking people with epilepsy (PWE) who attend a combination regional and district hospital in the eThekwini district in KwaZulu-Natal Province. METHOD: This was a prospective, cross-sectional, descriptive study. Data were collected using a validated data collection tool for assessing the medical knowledge of PWE and analysed descriptively. RESULTS: The questionnaires were completed by 199 PWE, with the general level of schooling being low and half being unemployed. Knowledge around causes, symptoms, diagnosis and treatments was good, but there were significant gaps in knowledge that may affect morbidity and mortality. DISCUSSION: The findings will serve as a useful guide to develop both preventive and educational interventions to enhance knowledge around the causes and treatment of epilepsy in this population. It is important that such interventions also consider family and healthcare providers. CONCLUSION: There were considerable gaps in the medical knowledge of isiZulu-speaking PWE's, indicating the need for an educational intervention to improve their understanding of epilepsy. Further research is needed-using a range of tools to ensure that the data is reliable and valid-if the results are to be generalisable to the rest of the province and South Africa.


Asunto(s)
Epilepsia , Conocimientos, Actitudes y Práctica en Salud , Grupos de Población/psicología , Adolescente , Adulto , Anciano , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sudáfrica , Encuestas y Cuestionarios , Adulto Joven
8.
Artículo en Inglés | AIM (África) | ID: biblio-1257799

RESUMEN

Background: Epilepsy is a common disorder in South Africa and the literature indicates that many patients do not access treatment. The reasons are complex and include a poor knowledge about causes; symptoms; diagnosis and treatment (medical knowledge). This study aimed to assess the medical knowledge of isiZulu-speaking people with epilepsy (PWE) who attend a combination regional and district hospital in the eThekwini district in KwaZulu-Natal Province.Method: This was a prospective; cross-sectional; descriptive study. Data were collected using a validated data collection tool for assessing the medical knowledge of PWE and analysed descriptively.Results: The questionnaires were completed by 199 PWE; with the general level of schooling being low and half being unemployed. Knowledge around causes; symptoms; diagnosis and treatments was good; but there were significant gaps in knowledge that may affect morbidity and mortality.Discussion: The findings will serve as a useful guide to develop both preventive and educational interventions to enhance knowledge around the causes and treatment of epilepsy in this population. It is important that such interventions also consider family and healthcare providers.Conclusion: There were considerable gaps in the medical knowledge of isiZulu-speaking PWE's; indicating the need for an educational intervention to improve their understanding of epilepsy. Further research is needed-using a range of tools to ensure that the data is reliable and valid-if the results are to be generalisable to the rest of the province and South Africa


Asunto(s)
Epilepsia/diagnóstico , Epilepsia/terapia , Hospitales Comunitarios , Conocimiento , Sudáfrica
9.
Int J Legal Med ; 116(3): 184-6, 2002 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12111325

RESUMEN

DNA typing of nine short tandem repeat (STR) loci was carried out on unrelated Israeli Jewish and Arab individuals. All loci were highly polymorphic and the distribution of the obtained genotypes did not deviate from Hardy-Weinberg equilibrium. A comparison between Jewish and Arab population data revealed statistically significant differences in allele frequency distributions for some of the loci. The results presented in this study enable the use of these nine STR loci for forensic, identification and paternity cases in the Jewish and the Arab populations of Israel.


Asunto(s)
Árabes/genética , Frecuencia de los Genes , Judíos/genética , Secuencias Repetidas en Tándem/genética , Simulación por Computador , Dermatoglifia del ADN , Medicina Legal/métodos , Humanos , Israel
10.
Planta ; 210(6): 947-55, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10872227

RESUMEN

Like higher plants, unicellular green algae of the genus Dunaliella respond to light stress by enhanced de-epoxidation of violaxanthin and accumulation of Cbr, a protein homologous to early light-inducible proteins (Elips) in plants. Earlier studies indicated that Cbr was associated with the light-harvesting complex of photosystem II (LHCII) and suggested it acted as a zeaxanthin-binding protein and fulfilled a photo-protective function (Levy et al. 1993, J. Biol. Chem. 268: 20892-20896). To characterize the protein-pigment subcomplexes containing Cbr in greater detail than attained so far, thylakoid membranes from Dunaliella salina grown in high light or normal light were solubilized with dodecyl maltoside and fractionated by isoelectric-focusing. Analysis of the resolved LHCII subcomplexes indicated preferred associations among the four LHCIIb polypeptides and between them and Cbr: subcomplexes including Cbr contained one or two of the more acidic of the four LHCIIb polypeptides as well as large amounts of lutein and zeaxanthin relative to chlorophyll a/b. After sucrose gradient centrifugation, Cbr free of LHCIIb polypeptides was detected together with released pigments; this Cbr possibly originated in subcomplexes dissociated in the course of the analysis. These results agree with the conclusion that Cbr is part of the network of LHCIIb protein-pigment complexes and suggest that the role played by Cbr involves the organization and/or stabilization of assemblies highly enriched in zeaxanthin and lutein. Such assemblies may function to protect PSII from photodamage due to overexcitation.


Asunto(s)
Chlorophyta/metabolismo , Proteínas Nucleares/metabolismo , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Tilacoides/metabolismo , Centrifugación por Gradiente de Densidad , Chlorophyta/química , Focalización Isoeléctrica , Complejos de Proteína Captadores de Luz , Luteína/metabolismo , Proteínas Nucleares/química , Proteínas del Complejo del Centro de Reacción Fotosintética/química , Complejo de Proteína del Fotosistema II , Unión Proteica , Tilacoides/química , Xantófilas , Zeaxantinas , beta Caroteno/análogos & derivados , beta Caroteno/metabolismo
11.
J Forensic Sci ; 45(3): 687-8, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10855979

RESUMEN

An exhibit that is often received for examination in cases of robbery or terrorist activity is adhesive tape. This type of exhibit can often, but not always, be successfully processed for fingerprints. The question arises whether or not it is possible to extract and type DNA after the tape has been sequentially processed for fingerprints. In this work, various donors left fingerprints on the adhesive side of tapes. The tapes were then sequentially processed for fingerprints using an alternate light source, cyanoacrylate fuming, and staining with BY-40 and then crystal violet. DNA was subsequently successfully extracted, amplified and typed for six STR loci.


Asunto(s)
ADN/aislamiento & purificación , Dermatoglifia , Repeticiones de Microsatélite/genética , Adhesivos , ADN/análisis , Medicina Legal/métodos , Humanos , Reacción en Cadena de la Polimerasa , Manejo de Especímenes , Violencia
12.
J Forensic Sci ; 45(2): 445-6, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10782971

RESUMEN

Two cases of threatening letters with their accompanying envelopes were received to the Division of Forensic Identification unit of the Israel Police. The envelopes, including the stamps, and the letters were initially examined for latent fingerprints by the DFO reagent, known to cause degradation of DNA. Although no latent fingerprints could be visualized on any of the items, the biology laboratory using organic DNA extraction, was successful in defining genetic profiles from all the items employing six STR loci, even after treatment with DFO. In a controlled experiment, a known donor attached a stamp, by licking, to an envelope. This item was treated with DFO and then profiled using STR loci. The results showed that previous DFO treatment on the control stamp before DNA analysis had no negative effects on obtaining the DNA profile of the known donor using STR loci.


Asunto(s)
Compuestos Aza/farmacología , Dermatoglifia del ADN/normas , Dermatoglifia , Medicina Legal/métodos , Secuencias Repetidas en Tándem/genética , Crimen , Humanos , Reacción en Cadena de la Polimerasa , Reproducibilidad de los Resultados , Manejo de Especímenes
13.
J Forensic Sci ; 45(1): 158-60, 2000 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-10641930

RESUMEN

DNA extracted from fingernail clippings of victims in forensic cases is a possible source of DNA from the perpetrator in cases where victims struggled or defended themselves. The source of this DNA on a victim's fingernails could possibly originate from contact with the suspect's blood, saliva, semen or scratched skin. In this technical note we evaluate the relevance of routine DNA typing of fingernail clippings in the forensic biology laboratory when, in real casework, normally only small quantities of nail material is sent. This was carried out by extracting DNA from fingernail clippings from a number of volunteers, before and after aggressively scratching other volunteers. No blood was drawn from the scratching, but skin flakes were observed under the nails before cutting and subsequent DNA typing. The DNA extracted was then typed using the STR systems: HUMTHO1, HUMTPOX and HUMCSF1PO (CTT triplex) and the system of D1S80. These profiles were compared with profiles achieved by similar typing of buccal swabs as a reference from each volunteer. In this study, the profile detected from each volunteer's clippings was the same before and after scratching, and matched the profile of the corresponding volunteer as defined by typing each volunteer's reference buccal swab. Fingernail clippings that are sent to our lab in actual casework are usually so small that additional treatment by swabbing or removing debris from below the clipping is not possible. For this reason, in this simulation the entire clippings were used for DNA extraction, to maximize the possibility of finding an additional profile. In conclusion, the findings from this study show that although the profiles obtained when typing fingernail clippings are those of the donors themselves, we suggest that typing of fingernail clippings should be carried out in forensic cases only when relevant. We would suggest that fingernail clippings not be routinely sent to the biology laboratory as items of evidence to be tested.


Asunto(s)
Medicina Legal/métodos , Uñas/patología , Análisis de Secuencia de ADN , Humanos
14.
Plant Physiol Biochem ; 37(11): 875-879, 1999 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-10580288

RESUMEN

Unicellular green algae of the genus Dunaliella, similar to higher plants, respond to light stress by enhanced de-epoxidation of violaxanthin and accumulation of Cbr, a protein homologous to early light inducible proteins (Elips) in plants. These proteins belong to the superfamily of chlorophyll a/b binding proteins. Two Dunaliella strains, D. bardawil and D. salina, were compared for these two responses under light in the UVA, blue, green and red spectral ranges. In D. bardawil, the two stress responses were similarly induced under UVA, blue or red light and to a lesser extent under green light. In D. salina, a similar spectral range dependence was exhibited for violaxanthin de-epoxidation. However, Cbr accumulated only under UVA or blue light but not under green or red light. A strong synergistic effect of a low dose of blue light superimposed on red light resulted in Cbr accumulation. These results reveal strain-specific differences in spectral range requirements of the two light-stress responses. In the two strains, violaxanthin de-epoxidation is triggered under photosynthetically-active spectral ranges but at least in D. salina, Cbr accumulation appears to require a specific light signal additionally to a signal(s) generated by light stress.

16.
J Clin Gastroenterol ; 27(1): 85-9, 1998 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-9706780

RESUMEN

Immunoproliferative small intestinal disease (IPSID) is a rare lympho-proliferative disorder of the upper small intestine. It is considered a special form of MALT lymphoma with propensity to malignant transformation. This disorder is rare in pediatric literature. We report a case of IPSID in a 16-year-old boy with low-grade malignant transformation, presenting as severe malnutrition and a possible association with Helicobacter pylori. The patient responded well to an extended treatment with tetracycline and eradication of H. pylori.


Asunto(s)
Enfermedad Inmunoproliferativa del Intestino Delgado/diagnóstico , Síndromes de Malabsorción/etiología , Adolescente , Helicobacter pylori/aislamiento & purificación , Humanos , Enfermedad Inmunoproliferativa del Intestino Delgado/complicaciones , Enfermedad Inmunoproliferativa del Intestino Delgado/microbiología , Enfermedad Inmunoproliferativa del Intestino Delgado/patología , Intestino Delgado/patología , Masculino , Estómago/microbiología
17.
J Biol Chem ; 273(28): 17553-8, 1998 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-9651348

RESUMEN

A 150-kDa transferrin-like protein (Ttf) is associated with the plasma membrane of the halotolerant unicellular alga Dunaliella salina (Fisher, M., Gokhman, I., Pick, U., and Zamir, A. (1997) J. Biol. Chem. 272, 1565-1570). The Ttf level rises with medium salinity or upon iron depletion. Evidence that Ttf is involved in iron uptake by Dunaliella is presented here. Algal iron uptake exhibits characteristics resembling those of animal transferrins: high specificity and affinity for Fe3+ ions, strict dependence on carbonate/bicarbonate ions, and very low activity in acidic pH. Reducing the level of Ttf by mild proteolysis of whole cells is accompanied by lowered uptake activity. Conversely, accumulation of high levels of Ttf is correlated with an enhancement of iron uptake. Kinetically, iron uptake consists of two steps: an energy-independent binding of iron to the cell surface and an energy-dependent internalization. Salinities as high as 3.5 M NaCl do not inhibit iron uptake or decrease the apparent affinity for Fe3+ ions, implying that Ttf activity is not affected by high salt. These results indicate that transferrins, hitherto identified only in animals, are present and function in iron transport also in plant systems.


Asunto(s)
Chlorophyta/metabolismo , Compuestos Férricos/farmacocinética , Transferrina/metabolismo , Membrana Celular/metabolismo , Unión Proteica , Cloruro de Sodio
18.
J Biol Chem ; 272(3): 1565-70, 1997 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-8999829

RESUMEN

The alga Dunaliella salina is outstanding is its ability to withstand extremely high salinities. To uncover mechanisms underlying salt tolerance, a search was carried out for salt-induced proteins. The level of a plasma membrane 150-kDa protein, p150, was found to increase with rising external salinity (Sadka, A., Himmelhoch, S., and Zamir, A. (1991) Plant Physiol. 95, 822-831). Based on its cDNA-deduced sequence, p150 belongs to the transferrin family of proteins so far identified only in animals. This, to our best knowledge, is the first demonstration of a transferrin-like protein in a photosynthetic organism. Unlike animal transferrins, p150 contains three, rather than two, internal repeats and a COOH-terminal extension including an acidic amino acid cluster. In intact cells p150 is degraded by Pronase, indicating that the protein is extracellularly exposed. The relationship of p150 to iron uptake is supported by the induction of the protein in iron-deficient media and by its radioactive labeling in cells grown with 59Fe. Accumulation of p150 is transcriptionally regulated. It is proposed that p150 acts in iron uptake other than by receptor-mediated endocytosis and that its induction permits the cells to overcome a possible limitation in iron availability under high salinities.


Asunto(s)
Proteínas Algáceas , Chlorophyta/metabolismo , Proteínas de Unión a Hierro , Proteínas de la Membrana/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Membrana Celular/metabolismo , ADN Complementario , Hierro/metabolismo , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Concentración Osmolar , Pronasa/metabolismo , Unión Proteica , Homología de Secuencia de Aminoácido , Cloruro de Sodio , Transcripción Genética , Transferrina/genética
19.
J Biol Chem ; 271(30): 17718-23, 1996 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-8663366

RESUMEN

The mechanisms allowing proliferation of the unicellular green alga Dunaliella salina in up to saturating NaCl concentrations are only partially understood at present. Previously, the level of a plasma membrane Mr 60,000 protein, p60, was found to increase with rising external salinities. Based on cDNA cloning and enzymatic assays, it is now shown that p60 is an internally duplicated carbonic anhydrase, with each repeat homologous to animal and Chlamydomonas reinhardtii carbonic anhydrases, but exceptional in the excess of acidic over basic residues. Increasing salinities, alkaline shift, or removal of bicarbonate induced in D. salina parallel increases in the levels of p60, its mRNA, and external carbonic anhydrase activity. Moreover, purified p60 exhibited carbonic anhydrase activity comparable to other carbonic anhydrases. A p60-enriched soluble preparation showed maximal carbonic anhydrase activity at approximately 1.0 M NaCl and retained considerable activity at higher salt concentrations. In contrast, a similar preparation from C. reinhardtii was approximately 90% inhibited in 0.6 M NaCl. These results identified p60 as a structurally novel carbonic anhydrase transcriptionally regulated by CO2 availability and exhibiting halophilic-like characteristics. This enzyme is potentially suited to optimize CO2 uptake by cells growing in hypersaline media.


Asunto(s)
Anhidrasas Carbónicas/genética , Membrana Celular/enzimología , Chlorophyta/genética , Cloruro de Sodio/farmacología , Álcalis/farmacología , Secuencia de Aminoácidos , Aminoácidos/análisis , Animales , Secuencia de Bases , Bicarbonatos/farmacología , Anhidrasas Carbónicas/metabolismo , Chlamydomonas reinhardtii/enzimología , Chlorophyta/efectos de los fármacos , Chlorophyta/enzimología , Clonación Molecular , ADN Complementario/genética , Inducción Enzimática/efectos de los fármacos , Datos de Secuencia Molecular , ARN Mensajero/análisis , Secuencias Repetitivas de Ácidos Nucleicos , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Especificidad de la Especie
20.
Plant Physiol ; 110(4): 1405-1411, 1996 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12226269

RESUMEN

The unicellular green alga Dunaliella bardawil exhibits typical responses to excessive light when starved for sulfate under normal light (60 [mu]E m-2 s-1) but not under low light (14 [mu]E m-2 s-1). Algae were analyzed during several days of sulfate starvation for nonphotochemical quenching of chlorophyll fluorescence in the absence or presence of the uncouplers SF-6847 (SF) or carbonyl cyanide p- trifluoromethoxyphenyl hydrazone. Parallel analyses followed two light-stress responses: (a) violaxanthin conversion to zeaxanthin and (b) accumulation of Cbr, a protein analogous to plant early-light-induced proteins and implicated in zeaxanthin binding. In cells starved under normal light SF inhibited nonphotochemical quenching during the first 24 h, but not from 40 h onward. In cells starved under low light SF inhibited nonphotochemical quenching throughout the starvation period. Under normal light accumulation of zeaxanthin was nearly maximal by 24 h, but Cbr was fully induced only by 40h. Under low light zeaxanthin accumulated slowly but no Cbr was evident. These results suggest that during exposure to excessive light, the initial pH gradient-dependent, Cbr-independent mode of nonphotochemical quenching is modified to become less dependent on pH gradient and requires Cbr.

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