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Problematic pornography use (PPU) is an emerging condition associated with several negative psychological and sexual outcomes. This study aimed to systematically review treatment approaches for PPU. Potentially eligible studies were searched for in PubMed/MEDLINE, Embase, PsycINFO, and Web of Science up to April 1, 2023. The quality of the evidence was assessed with the use of the Joanna Briggs Institute's checklists, the Cochrane risk-of-bias tools, and the GRADE approach. A total of 8936 references were retrieved, and 28 studies were included in the systematic review (n = 500 participants). Included studies were case reports (k = 16), case series (k = 1), quasi-experimental investigations (k = 7), and randomized clinical trials (k = 4). The majority of included studies presented overall low quality and significant risk of bias, with all interventions receiving a low or very low rating according to the GRADE approach. Most studies investigated psychological interventions, with the predominance of second and third wave cognitive behavioral therapy interventions. Pharmacological treatments included opioid antagonists (naltrexone in most cases) and antidepressants, while one study investigated a protocol that included rTMS. Several investigations described the combination of psychological and pharmacological approaches. Most studies did not report on side effects, with online and self-help interventions presenting significant issues in terms of treatment adherence. Even though there are promising options that may have efficacy for the treatment of patients with PPU, the literature in the topic still presents significant limitations that compromise the reaching of more definitive conclusions.
Assuntos
Terapia Cognitivo-Comportamental , Literatura Erótica , Humanos , Terapia Cognitivo-Comportamental/métodosRESUMO
OBJECTIVE: Our aim was to analyze the association between criminal behavior and impulsivity in individuals with drug addiction and investigate whether impulsiveness mediates the relationship between drug use severity and legal problems. METHODS: This cross-sectional study included 773 men diagnosed with addiction (295 alcohol users and 478 users of crack/polysubstance) while undergoing addiction treatment. The BIS-11 and ASI-6 were applied to assess impulsivity, criminal behavior, and drug use. RESULTS: The prevalence of criminal behavior was 41.7% (n = 123) in alcohol users and 64.9% (n = 310) in users of crack/polysubstance. Earlier use of different substances and higher impulsivity scores were observed in individuals with criminal history. Mediation analyses revealed that impulsiveness acts as a mediator factor between substance use and criminal behavior, enhancing the severity of legal problems. CONCLUSION: Our findings can help in deciding on tailored treatment strategies, focusing not only on substance use, but also on the prevention of social problems, criminality, and impulsivity.
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Alcohol Use Disorder (AUD) is a highly prevalent condition worldwide that produces a wide range of pathophysiological consequences, with a critical impact on health and social issues. Alcohol influences gene expression through epigenetic changes mainly through DNA methylation. In this sense, levels of 5-methylcytosine (5-mC), namely Global DNA methylation (GMe), which can be influenced by environmental and hormonal effects, represent a putative biological mechanism underlying alcohol effects. Our aim was to investigate the influence of AUD diagnosis and alcohol patterns (i.e., years of addiction, use in the last 30 days, and alcohol severity) on GMe levels. The sample consisted of 256 men diagnosed with AUD and 361 men without AUD. DNA samples from peripheral blood were used to assess GMe levels, measured through the levels of 5-mC using high-performance liquid chromatography. Results from multiple linear regression analysis indicated that the presence of AUD was associated with lower GMe levels (beta=-0.155, p=0.011). Other alcohol-related outcomes were not associated with DNA methylation. Our findings are consistent with the hypothesis that the impact of chronic and heavy alcohol use in GMe could be a potential mechanism mediating the multiple organ damages related to AUD.
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Plastoglobules (PGs) contiguous with the outer leaflets of thylakoid membranes regulate lipid metabolism, plastid developmental transitions, and responses to environmental stimuli. However, the function of OsFBN7, a PG-core fibrillin gene in rice, has not been elucidated. Using molecular genetics and physiobiochemical approaches, we observed that OsFBN7 overexpression promoted PG clustering in rice chloroplasts. OsFBN7 interacted with two KAS I enzymes, namely OsKAS Ia and OsKAS Ib, in rice chloroplasts. Lipidomic analysis of chloroplast subcompartments, including PGs in the OsFBN7 overexpression lines, confirmed that levels of diacylglycerol (DAG), a chloroplast lipid precursor and monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), the main chloroplast membrane lipids, were increased in PGs and chloroplasts. Furthermore, OsFBN7 enhanced the abundances of OsKAS Ia/Ib in planta and their stability under oxidative and heat stresses. In addition, RNA sequencing and real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analyses showed that the expression of the DAG synthetase gene PAP1 and MGDG synthase gene MDG2 was upregulated by OsFBN7. In conclusion, this study proposes a new model in which OsFBN7 binds to OsKAS Ia/Ib in chloroplast and enhances their abundance and stability, thereby regulating the chloroplast and PG membrane lipids involved in the formation of PG clusters.
Assuntos
Oryza , Oryza/genética , Oryza/metabolismo , Cloroplastos/metabolismo , Galactolipídeos/metabolismo , Tilacoides/metabolismo , Lipídeos de Membrana/metabolismo , Resposta ao Choque TérmicoRESUMO
Plant tissues can be enriched in phytonutrients not only by stimulating their biosynthesis but also by providing appropriate sink structures for their sequestering and storage. In the case of carotenoids, they accumulate at high levels in chromoplasts naturally found in flowers and fruit. Chromoplasts can also be artificially differentiated from leaf chloroplasts by boosting carotenoid production with the bacterial protein crtB. Here we used electron and confocal microscopy together with subplastidial fractionation and transcript, protein and metabolite analyses to analyze the structural and biochemical changes occurring in crtB-induced artificial chromoplasts and their impact on the accumulation of health-related isoprenoids. We show that leaf chromoplasts develop plastoglobules (PG) harboring high levels of carotenoids (mainly phytoene and pro-vitamin A ß-carotene) but also other nutritionally relevant isoprenoids, such as tocopherols (vitamin E) and phylloquinone (vitamin K1). Further promoting PG proliferation by exposure to intense (high) light resulted in a higher accumulation of these health-related metabolites but also an acceleration of the chloroplast-to-chromoplast conversion. We further show that the production of reactive oxygen species (ROS) stimulates chromoplastogenesis. Our data suggest that carotenoid accumulation and ROS production are not just consequences but promoters of the chromoplast differentiation process.
Assuntos
Carotenoides , Plastídeos , Espécies Reativas de Oxigênio/metabolismo , Plastídeos/metabolismo , Carotenoides/metabolismo , Cloroplastos/metabolismo , beta Caroteno/metabolismoRESUMO
The current study addresses the need to empirically develop effective mental health interventions for youth from ethnic/racial minority and low-income neighborhoods. Using Stage Model evaluation methods supported by the National Institutes of Health in the US to address underutilization of mental healthcare among racial/ethnic minority youth, this feasibility study demonstrates empirical adaptation of an innovative sport-specific psychological intervention for use in youth from ethnic/racial minority and low-income neighborhoods. An international group of professionals familiar with sport performance and mental health intervention serving the target population experientially examined the adapted intervention protocols in workshops and provided feedback. Survey results indicated the professionals found the intervention components were easy to administer and likely to be safe, enjoyable, engaging and efficacious for youth mental health and sport performance. The protocols were revised based on feedback from these professionals and the intervention was examined in a case trial involving an Asian American youth who evidenced Social Anxiety Disorder. Case study results indicated the intervention could be implemented with integrity, and severity of psychiatric symptoms and factors interfering with sport performance decreased after intervention implementation. The participant's relationships with family, coaches and teammates were also improved.
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Etnicidade , Saúde Mental , Adolescente , Atletas , Minorias Étnicas e Raciais , Estudos de Viabilidade , Humanos , Grupos Minoritários/psicologia , National Institutes of Health (U.S.) , Estados UnidosRESUMO
Malate dehydrogenases (MDHs) convert malate to oxaloacetate using NAD(H) or NADP(H) as a cofactor. Arabidopsis thaliana mutants lacking plastidial NAD-dependent MDH (pdnad-mdh) are embryo-lethal, and constitutive silencing (miR-mdh-1) causes a pale, dwarfed phenotype. The reason for these severe phenotypes is unknown. Here, we rescued the embryo lethality of pdnad-mdh via embryo-specific expression of pdNAD-MDH. Rescued seedlings developed white leaves with aberrant chloroplasts and failed to reproduce. Inducible silencing of pdNAD-MDH at the rosette stage also resulted in white newly emerging leaves. These data suggest that pdNAD-MDH is important for early plastid development, which is consistent with the reductions in major plastidial galactolipid, carotenoid, and protochlorophyllide levels in miR-mdh-1 seedlings. Surprisingly, the targeting of other NAD-dependent MDH isoforms to the plastid did not complement the embryo lethality of pdnad-mdh, while expression of enzymatically inactive pdNAD-MDH did. These complemented plants grew indistinguishably from the wild type. Both active and inactive forms of pdNAD-MDH interact with a heteromeric AAA-ATPase complex at the inner membrane of the chloroplast envelope. Silencing the expression of FtsH12, a key member of this complex, resulted in a phenotype that strongly resembles miR-mdh-1. We propose that pdNAD-MDH is essential for chloroplast development due to its moonlighting role in stabilizing FtsH12, distinct from its enzymatic function.
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Cloroplastos/metabolismo , Malato Desidrogenase/metabolismo , Carotenoides/metabolismo , Cloroplastos/genética , Galactolipídeos/metabolismo , Inativação Gênica/fisiologia , Malato Desidrogenase/genética , Protoclorifilida/metabolismoRESUMO
Objective: To evaluate aggressiveness in individuals receiving treatment for alcohol and crack cocaine use, both alone and in combination with one another, in order to compare them to control subjects with no history of drug problems, using the State-Trait Anger Expression Inventory. Method: The sample consisted of 67 men aged 18-65 years, divided into four groups: alcohol (n = 13); crack cocaine (n = 25); crack cocaine + alcohol (n = 16) and controls (n = 13). Participants completed the following instruments: socioeconomic questionnaire, the Wechsler Abbreviated Scale of Intelligence and the State-Trait Anger Expression Inventory. Results: Individuals with alcohol dependence alone, or comorbid with crack cocaine dependence, showed elevated levels of aggression and anger, though these varied according to the drug of abuse. Concurrent users of alcohol and crack cocaine had the highest levels of aggression, followed by isolated alcohol users, suggesting an association between alcohol consumption and aggression. Conclusion: The present findings suggest that alcohol and aggression levels may be associated with violent behavior. Concurrent use of alcohol and crack cocaine was related to higher levels of aggression, which may be associated with more severe alterations in behavior and impulse control.
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Alcoolismo , Transtornos Relacionados ao Uso de Cocaína , Cocaína Crack , Agressão , Ira , Transtornos Relacionados ao Uso de Cocaína/epidemiologia , Humanos , MasculinoRESUMO
There is evidence that dopamine receptors D2 (DRD2) and D4 (DRD4) polymorphisms may influence substance use disorders (SUD) susceptibility both individually and through their influence in the formation of DRD2-DRD4 heteromers. The dopaminergic role on the vulnerability to addiction appears to be influenced by sex. A cross-sectional study with 307 crack cocaine addicts and 770 controls was conducted. The influence of DRD2 rs2283265 and DRD4 48 bp VNTR in exon 3 variants, as well as their interaction on crack cocaine addiction susceptibility and severity were evaluated in women and men separately. An association between the DRD2 T allele and crack cocaine addiction was found in women. In this same group, interaction analysis demonstrated that the presence of DRD2-T allele and concomitant absence of DRD4-7R allele were associated with risk for crack cocaine addiction. No influence of DRD2 and DRD4 variants was observed in men regarding addiction severity. This study reinforces the role of dopaminergic genes in externalizing behaviors, especially the influence of DRD2-DRD4 interaction on SUD. This is the fourth sample that independently associated the DRD2-DRD4 interaction with SUD itself or related disorders. In addition, our findings point out to a potential difference of dopaminergic neurotransmission across sex influencing addiction susceptibility.
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Transtornos Relacionados ao Uso de Cocaína/genética , Cocaína Crack , Predisposição Genética para Doença/genética , Receptores de Dopamina D2/genética , Receptores de Dopamina D4/genética , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Repetições Minissatélites , Polimorfismo Genético , Fatores Sexuais , Adulto JovemRESUMO
BACKGROUND: NBOMes are a new class of potent hallucinogens widely present in illicit drugs. Little is known about this class of drugs, regarding its detection and clinical manifestations of intoxication. OBJECTIVE: This study aims to enhance care involving NBOMes by reviewing the literature on their clinical manifestations and laboratorydetection. METHODS: A systematic review was performed on the clinical manifestations and laboratory tests of NBOMEs ingestion. Embase, Pubmed, PsycINFO, and Cochrane databases were employed in this analysis. RESULTS: Forty-five articles met the inclusion criteria out of the 2814 nonduplicated studies on the theme. Seventy case reports of intoxication were found in the analyzed articles (64.3% were men and 11.4% were women, mean age of 22.5). The technique most employed for NBOMes identification was chromatography of blood, urine, and oral fluids. Moreover, the studies identified 13 chemical structures differentfrom the NBOMes on their toxicological analyses.According to these studies, most of these drugs were ingested orally-nasal use was the second preferred administration route, followed by intravenous administration. CONCLUSION: Better identification of the clinicalmanifestations and laboratory profile of NBOMes is crucial to the recognition of intoxication as well as to its effective treatment.
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Alucinógenos/intoxicação , Fenetilaminas/intoxicação , Acidose/induzido quimicamente , Injúria Renal Aguda/induzido quimicamente , Drogas Desenhadas , Febre/induzido quimicamente , Alucinógenos/sangue , Parada Cardíaca/induzido quimicamente , Humanos , Fenetilaminas/sangue , Rabdomiólise/induzido quimicamente , Convulsões/induzido quimicamente , Tentativa de Suicídio , Taquicardia/induzido quimicamente , Distúrbios do Paladar/induzido quimicamenteRESUMO
The biogenesis and maintenance of cell organelles such as mitochondria and chloroplasts require the import of many proteins from the cytosol, a process that is controlled by phosphorylation. In the case of chloroplasts, the import of hundreds of different proteins depends on translocons at the outer and inner chloroplast membrane (TOC and TIC, respectively) complexes. The essential protein TOC159 functions thereby as an import receptor. It has an N-terminal acidic (A-) domain that extends into the cytosol, controls receptor specificity, and is highly phosphorylated in vivo However, kinases that phosphorylate the TOC159 A-domain to enable protein import have remained elusive. Here, using co-purification with TOC159 from Arabidopsis, we discovered a novel component of the chloroplast import machinery, the regulatory kinase at the outer chloroplast membrane 1 (KOC1). We found that KOC1 is an integral membrane protein facing the cytosol and stably associates with TOC. Moreover, KOC1 phosphorylated the A-domain of TOC159 in vitro, and in mutant koc1 chloroplasts, preprotein import efficiency was diminished. koc1 Arabidopsis seedlings had reduced survival rates after transfer from the dark to the light in which protein import into plastids is required to rapidly complete chloroplast biogenesis. In summary, our data indicate that KOC1 is a functional component of the TOC machinery that phosphorylates import receptors, supports preprotein import, and contributes to efficient chloroplast biogenesis.
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Proteínas de Arabidopsis/metabolismo , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Proteínas de Arabidopsis/fisiologia , Proteínas de Cloroplastos/fisiologia , Cromatografia de Afinidade , Citosol/metabolismo , Escherichia coli/metabolismo , Espectrometria de Massas , Mutação , Fosforilação , Domínios Proteicos , Transporte Proteico , Proteínas Recombinantes/metabolismoRESUMO
Crack cocaine users frequently report difficulties regarding having healthy and rewarding relationships. Factors other than the use of crack cocaine itself may be at play when it comes to being able to develop healthier connections with partners, adult relatives and close friends. To verify which factors, including demographics, substance abuse related factors and psychiatric comorbidities could be markers for a higher severity of problems in interpersonal relationships of crack cocaine users seeking for treatment. This was a cross-sectional study, conducted between April 2011 and November 2012. Participants were 407 crack cocaine users seeking treatment in specialized public facilities of six Brazilian capitals. The relationship of severity of problems in the family/social area and the prevalence of psychiatric disorders, exposure to stressful events, substance use related factors and practice of illicit activities were explored through multivariate analyses. Number of days using crack cocaine in the last 30 days, age of first time using alcohol and feeling its effects, a diagnosis of alcohol abuse, posttraumatic stress disorder, antisocial personality disorder and attention-deficit/hyperactivity disorder were significantly associated with a higher severity of problems in interpersonal relationships with partners, adult relatives and friends. Problems in interpersonal relationships are strongly related to specific psychiatric comorbidities and the frequency of crack cocaine use. Factors identified by this study can make the paths to recovery more challenging. These results support psychosocial interventions that focus in the improvement of interpersonal relationships of crack cocaine users.
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Alcoolismo/psicologia , Transtorno da Personalidade Antissocial/psicologia , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Transtornos Relacionados ao Uso de Cocaína/psicologia , Cocaína Crack , Relações Interpessoais , Transtornos de Estresse Pós-Traumáticos/psicologia , População Urbana/estatística & dados numéricos , Adolescente , Adulto , Alcoolismo/epidemiologia , Transtorno da Personalidade Antissocial/epidemiologia , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Brasil/epidemiologia , Transtornos Relacionados ao Uso de Cocaína/epidemiologia , Comorbidade , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Adulto JovemRESUMO
In a changing environment, plants need to cope with the impact of rising temperatures together with high light intensity. Here, we used lipidomics in the tomato model system to identify lipophilic molecules that enhance tolerance to combined high-temperature and high-light stress. Among several hundred metabolites, the two most strongly up-regulated compounds were α-tocopherol and plastoquinone/plastoquinol. Both are well-known lipid antioxidants and contribute to the protection of photosystem II (PSII) against photodamage under environmental stress. To address the protective function of tocopherol, an RNAi line (vte5) with decreased expression of VTE5 and reduced levels of α-tocopherol was selected. VTE5 encodes phytol kinase, which acts in the biosynthetic pathway of tocopherols. vte5 suffered strong photoinhibition and photobleaching when exposed to combined high-light and high-temperature stress, but neither stress alone produced a visible phenotype. As vte5 had plastoquinone levels similar to those of the wild type under combined stress, the strong phenotype could be attributed to the lack of α-tocopherol. These findings suggest that VTE5 protects against combined high-light and high-temperature stress and does so by supporting α-tocopherol production.
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Luz/efeitos adversos , Proteínas de Plantas/genética , Solanum lycopersicum/fisiologia , Temperatura , Solanum lycopersicum/genética , Fosfotransferases/metabolismo , Fitol/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Tocoferóis/metabolismoRESUMO
BACKGROUND: This study aims to compare allele and genotype frequencies of a 30-bp variable number of tandem repeats (VNTR) polymorphism of the DAT1 gene, located at intron 8, between adult crack cocaine users and nonaddicted individuals. Due to its involvement in drug addiction, this gene is a good candidate for molecular studies. METHODS: A cross-sectional sample of 239 current adult crack abusers or dependents from in- and outpatient clinics and 211 control individuals was collected in Brazil. They were evaluated using ASRS, ASI-6, WAIS-III, and MINI assessments. DNA samples extracted from whole blood were genotyped for the intron 8 VNTR in DAT1. RESULTS: Logistic regression analysis was performed and controlled for gender, age, ethnicity, educational level, and comorbidities of clinical interest (generalized anxiety disorder, suicide risk, major depressive episode, and attention deficit/hyperactivity disorder). This analysis showed that the 6R6R genotype was associated with crack cocaine addiction (OR = 1.844; CI = 1.101-3.089; p = 0.020). CONCLUSIONS: Our results are consistent with the role of DAT1 in the neurobiology of drug addiction. Nevertheless, the study of other genes, environmental factors, and their interactions is also important to gain a broader understanding of this condition.
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Transtornos Relacionados ao Uso de Cocaína/genética , Cocaína Crack , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Adulto , Transtornos Relacionados ao Uso de Cocaína/complicações , Estudos Transversais , Feminino , Frequência do Gene , Genótipo , Humanos , Íntrons , Masculino , Repetições Minissatélites , Polimorfismo GenéticoRESUMO
In recent years, several studies have been focused on the comorbidity of psychiatric disorders with alcohol and other substance dependence. In this context, the Brazilian Association of Studies on Alcohol and Other Drugs initiated a project to establish Brazilian Guidelines. The aim of this study was to review diagnostic and therapeutic criteria for the most prevalent psychiatric comorbidities. Randomized clinical trials, epidemiological studies, animal testing and other forms of research are reviewed herein. The main psychiatric comorbidities are investigated and data published in the literature are reviewed, based on guidelines adopted by other countries. Epidemiological aspects, diagnostic criteria, integrated treatment and the organization of specialized service, as well as details regarding psychotherapy and pharmacological treatment are discussed. The guidelines of the Brazilian Association of Studies on Alcohol and Other Drugs reinforce the importance of adequate diagnosis and treatment regarding alcoholic and drug dependent patients suffering of comorbid psychiatric disorders.
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Transtornos Relacionados ao Uso de Álcool , Transtornos Mentais , Guias de Prática Clínica como Assunto , Sociedades Científicas/normas , Transtornos Relacionados ao Uso de Substâncias , Transtornos Relacionados ao Uso de Álcool/diagnóstico , Transtornos Relacionados ao Uso de Álcool/epidemiologia , Transtornos Relacionados ao Uso de Álcool/terapia , Brasil , Comorbidade , Humanos , Transtornos Mentais/diagnóstico , Transtornos Mentais/epidemiologia , Transtornos Mentais/terapia , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Transtornos Relacionados ao Uso de Substâncias/terapiaRESUMO
Female crack users who sought treatment are a hard to find part of the population. We studied sociodemographic and behavioral characteristics of crack users undergoing treatment in psychosocial care centers for alcohol and other drugs in six Brazilian cities. We carried out a cross-sectional study of 816 crack users and collected data with the Addiction Severity Index. Women were more likely to be in vulnerable situations: had worst levels of education, were not receiving money enough to their basic needs; more likely to be HIV positive (10.1%), to report sexual abuse (34%), and to be separated from their children (20%).
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Transtornos Relacionados ao Uso de Cocaína/reabilitação , Cocaína Crack/efeitos adversos , Populações Vulneráveis , Adulto , Brasil/epidemiologia , Transtornos Relacionados ao Uso de Cocaína/epidemiologia , Transtornos Relacionados ao Uso de Cocaína/psicologia , Estudos Transversais , Feminino , Infecções por HIV/epidemiologia , Pessoas Mal Alojadas/psicologia , Humanos , Violência por Parceiro Íntimo/psicologia , Masculino , Pessoa de Meia-Idade , Prevalência , Estupro/psicologia , Assunção de Riscos , Fatores Socioeconômicos , Adulto JovemRESUMO
Photosynthesis is the key bioenergetic process taking place in the chloroplast. The components of the photosynthetic machinery are embedded in a highly dynamic matrix, the thylakoid membrane. This membrane has the capacity to adapt during developmental transitions and under stress conditions. The galactolipids are the major polar lipid components of the thylakoid membrane conferring bilayer properties, while neutral thylakoid lipids such as the prenyllipids and carotenoids contribute to essential functions such as electron transport and photoprotection. Despite a large number of studies, the intriguing processes of thylakoid membrane biogenesis and dynamics remain unsolved. Plastoglobules, thylakoid-associated lipid droplets, appear to actively participate in thylakoid function from biogenesis to senescence. Recruitment of specific proteins enables the plastoglobules to act in metabolite synthesis, repair and disposal under changing environmental conditions and developmental stages. In this review, we describe plastoglobules as thylakoid membrane microdomains and discuss their involvement in lipid remodeling during stress and in the conversion from one plastid type to another. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Desenvolvimento Vegetal , Plastídeos/fisiologia , Tilacoides/fisiologia , Cádmio/toxicidade , Senescência Celular , Cloroplastos , Luz , Microdomínios da Membrana/fisiologiaRESUMO
We report on the characterization of Tic56, a unique component of the recently identified 1-MD translocon at the inner envelope membrane of chloroplasts (TIC) in Arabidopsis (Arabidopsis thaliana) comprising Tic20, Tic100, and Tic214. We isolated Tic56 by copurification with Tandem Affinity Purification-tagged Toc159 in the absence of precursor protein, indicating spontaneous and translocation-independent formation of the translocon at the outer envelope membrane of chloroplasts (TOC) and TIC supercomplexes. Tic56 mutant plants have an albino phenotype and are unable to grow without an external carbon source. Using specific enrichment of protein amino termini, we analyzed the tic56-1 and plastid protein import2 (toc159) mutants to assess the in vivo import capacity of plastids in mutants of an outer and inner envelope component of the anticipated TOC-TIC supercomplex. Inboth mutants, we observed processing of several import substrates belonging to various pathways. Our results suggest that despite the severe developmental defects, protein import into Tic56-deficient plastids is functional to a considerable degree, indicating the existence of alternative translocases at the inner envelope membrane.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cloroplastos/ultraestrutura , Membranas Intracelulares/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Arabidopsis/química , Western Blotting , Cloroplastos/metabolismo , Marcação por Isótopo , Proteínas de Membrana Transportadoras/química , Peso Molecular , Mutação/genética , Peptídeos/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Transporte Proteico , Especificidade por SubstratoRESUMO
Tocopherol, a compound with vitamin E (VTE) activity, is a conserved constituent of the plastidial antioxidant network in photosynthetic organisms. The synthesis of tocopherol involves the condensation of an aromatic head group with an isoprenoid prenyl side chain. The latter, phytyl diphosphate, can be derived from chlorophyll phytol tail recycling, which depends on phytol kinase (VTE5) activity. How plants co-ordinate isoprenoid precursor distribution for supplying biosynthesis of tocopherol and other prenyllipids in different organs is poorly understood. Here, Solanum lycopersicum plants impaired in the expression of two VTE5-like genes identified by phylogenetic analyses, named SlVTE5 and SlFOLK, were characterized. Our data show that while SlFOLK does not affect tocopherol content, the production of this metabolite is >80% dependent on SlVTE5 in tomato, in both leaves and fruits. VTE5 deficiency greatly impacted lipid metabolism, including prenylquinones, carotenoids, and fatty acid phytyl esters. However, the prenyllipid profile greatly differed between source and sink organs, revealing organ-specific metabolic adjustments in tomato. Additionally, VTE5-deficient plants displayed starch accumulation and lower CO2 assimilation in leaves associated with mild yield penalty. Taken together, our results provide valuable insights into the distinct regulation of isoprenoid metabolism in leaves and fruits and also expose the interaction between lipid and carbon metabolism, which results in carbohydrate export blockage in the VTE5-deficient plants, affecting tomato fruit quality.
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Vias Biossintéticas , Regulação para Baixo , Metabolismo dos Lipídeos , Especificidade de Órgãos , Proteínas de Plantas/metabolismo , Solanum lycopersicum/enzimologia , Tocoferóis/metabolismo , Vias Biossintéticas/genética , Metabolismo dos Carboidratos/genética , Clorofila/metabolismo , Regulação para Baixo/genética , Ésteres/metabolismo , Frutas/metabolismo , Gases/metabolismo , Regulação da Expressão Gênica de Plantas , Técnicas de Silenciamento de Genes , Genes de Plantas , Metabolismo dos Lipídeos/genética , Solanum lycopersicum/genética , Mutação/genética , Fotossíntese/genética , Complexo de Proteína do Fotossistema II/metabolismo , Fitol/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Prenilação , Interferência de RNA , Solubilidade , Amido/metabolismoRESUMO
Arabidopsis proton gradient regulation (pgr) mutants have high chlorophyll fluorescence and reduced non-photochemical quenching (NPQ) caused by defects in photosynthetic electron transport. Here, we identify PGR6 as the chloroplast lipid droplet (plastoglobule, PG) kinase ABC1K1 (activity of bc1 complex kinase 1). The members of the ABC1/ADCK/UbiB family of atypical kinases regulate ubiquinone synthesis in bacteria and mitochondria, and impact various metabolic pathways in plant chloroplasts. Here, we demonstrate that abc1k1 has a unique photosynthetic and metabolic phenotype that is distinct from that of the abc1k3 homolog. The abc1k1/pgr6 single mutant is specifically deficient in the electron carrier plastoquinone, as well as in ß-carotene and the xanthophyll lutein, and is defective in membrane antioxidant tocopherol metabolism. After 2 days of continuous high light stress, abc1k1/pgr6 plants suffer extensive photosynthetic and metabolic perturbations, strongly affecting carbohydrate metabolism. Remarkably, however, the mutant acclimates to high light after 7 days together with a recovery of carotenoid levels and a drastic alteration in the starch-to-sucrose ratio. Moreover, ABC1K1 behaves as an active kinase and phosphorylates VTE1, a key enzyme of tocopherol (vitamin E) metabolism in vitro. Our results indicate that the ABC1K1 kinase constitutes a new type of regulatory link between photosynthetic activity and chloroplast metabolism.