The eyespot of the biflagellate unicellular green alga Chlamydomonas reinhardtii is a complex organelle that facilitates directional responses of the cell to environmental light stimuli. The eyespot, which assembles de novo after every cell division and retains a distinctive association with the microtubule cytoskeleton, comprises an elliptical patch of rhodopsin photoreceptors in the plasma membrane and stacks of carotenoid-rich pigment granule arrays in the chloroplast and serves as a model for understanding how organelles are formed and placed asymmetrically in the cell. This study describes the roles of several factors in the assembly and positioning of the eyespot. Two loci, EYE2 and EYE3, define factors involved in the formation and organization of the eyespot pigment granule arrays. Whereas EYE3, a serine/threonine kinase of the ABC1 family, localizes to pigment granules, EYE2 localization corresponds to an area of the chloroplast envelope in the eyespot. These proteins play interdependent roles: EYE2 and the ChR1 photoreceptor co-position in the absence of pigment granules, and the pigment granules are required to maintain the shape and integrity of the EYE2/ChR1 patch. The miniature-eyespot locus MIN2 affects eyespot size and likely regulates the amount of material available for eyespot assembly. The MLT2 locus regulates eyespot size, number, and asymmetry. A novel locus, PEY1, modulates the position of the eyespot on the anterior-posterior axis by affecting microtubule rootlet length. A working model is developed wherein rootlet microtubule-directed photoreceptor localization establishes connections in the chloroplast envelope with EYE2, which directs the site for pigment granule array assembly, and MLT2 is proposed to negatively regulate the levels of eyespot proteins.

Mitochondrion is believed to be an ubiquitous organelle which occurred about 1,5 billion years ago by a single endosymbiotic event. Mitochondria is mostly dependent on the protein import from cytosol thus the establishment of protein import machinery was essential for seizing the new endosymbiont. Possibilities of studying the evolution of protein import machineries are quite limited given that no "free living" mitochondria or amitochondriate organisms are known nowadays. One alternative is to study mitochondrial secondary reductive evolution of anaerobic parasitic protists. Giardia intestinalis is flagellated protozoan living in microaerofilic environment of the small intestine. It containes one of the most reduced mitochondrion (mitosome) described so far. Hence it serves as a great model for studying mitochondrial evolution. Although it is well understood that all mitosomal proteins are transported from cytosol, many aspects of protein import pathway remain elusive. While the main channel Tom40 is present in the outer membrane, two other main translocases (Sam50 which is required for betta-barrel assembly in the outer membrane and Tim17/22/23 which is essential for protein translocation through the inner membrane) have not been identified so far. Protein translocation through Tim17/22/23 channel...

Introdução: A doença hepática gordurosa não alcoólica (DHGNA) é uma das formas mais comuns de doença hepática, que acomete cerca de 20% a 30% da população adulta, sendo encontrada mais frequentemente em indivíduos obesos (~90%). Dentre os principais fatores etiológicos estão: resistência à insulina, disfunção mitocondrial e estresse oxidativo. Até o presente momento não há tratamento farmacológico específico para a DHGNA, por isso modificações no estilo de vida como redução do peso corporal (PC), dieta e prática regular de exercício físico são eficazes no combate a DHGNA. Entretanto ainda não está elucidado quais os principais impactos do exercício físico na DHGNA. Objetivos: Com isso, propusemos um estudo experimental que avaliou o efeito do treinamento físico sobre metabolismo oxidativo, funcionalidade mitocondrial hepática e muscular (soléo) e lipogênese hepática em modelo de DHGNA em camundongos obesos (ob/ob). Métodos: Utilizou-se 14 (ob/ob) com déficit em leptina e forma divididos em dois grupos: Sedentário (SED)=7 e treinados (TF=7) de acordo com o equilíbrio na média do PC. Estes animais foram submetidos a um protocolo de 8 semanas de treinamento físico aeróbio (TFA) a 60% da velocidade máxima obtida no teste de corrida realizado no último dia da semana de adaptação ao TFA. Na quarta semana foi realizado o reajuste da intensidade apenas nos TF e o teste de capacidade de corrida foi aplicado na oitava semana em ambos os grupos para se avaliar o desempenho dos animais nas variáveis ligadas ao TFA. Avaliou-se durante todo o protocolo: peso corporal (PC) em média, percentual, evolução do PC e consumo de água e ração. Na expressão gênica intra-hepática e muscular foram analisados: PGC-1Alfa, CPT-1Alfa e PPAR-Alfa relacionados a funcionalidade mitocondrial, em adição analisou-se no fígado: SREBP1. No metabolismo oxidativo analisou-se: biomarcadores (MDA e carbonilas), atividade enzimática de SOD, CAT e GST, sistema antioxidante não enzimático: sulfidrilas, GSH e GSH/GSSG, enzimas metabólicas (Citrato sintase e Beta-HAD). Foi realizada análise histopatológica hepática por HE, além do peso absoluto e relativo dos tecidos hepático e adiposo branco retroperitoneal, periepididimal e inguinal. Resultados: Na análise intergrupo em relação ao PC, observou-se redução significativa no grupo TF, assim como nos consumos de água e ração que foram significativamente menores após 8 semanas: Na análise de expressão gênica hepática encontramos aumento de PGC-1Alfa (p=0,002) e menor de CPT-1Alfa p=0,03) no grupo LTF após 8 semanas de TFA. No músculo Soléo encontramos maior expressão dos genes: PGC-1Alfa (p=0,002) e CPT-1Alfa (p=0,01). Em relação a MDA e carbonilas não houve diferença intergrupo, assim como em SOD, CAT e GST. Entretanto, quando analisamos o sistema antioxidante não enzimático, encontramos que os TF obtiveram maior nível de: sulfídrilas (p=0,02), GSH (p=0,001) e GSH/GSSG (p=0,02), além maior ativação das enzimas metabólicas: citrato sintase (p=0,004) e Beta-HAD (p=0,01). No peso dos órgãos, o TF demonstrou menor peso absoluto e relativo hepático e retroperitoneal. Na análise histológica, não houve diferença significante. Conclusões: Nossos dados demonstram que TFA melhorou o controle do PC, hiperfagia e peso do fígado e retroperitoneal, funcionalidade mitocondrial e metabolismo oxidativo em (ob/ob) com DHGNA. Há necessidade uma intervenção a longo prazo com TFA, para que se posso visualizar possíveis melhorias histológicas / Non-alcoholic fatty liver disease (NAFLD) is one of the most common forms of liver disease, affecting about 20% to 30% of the adult population, being found more often in obese individuals (~ 90%). Among the main etiological factors are insulin resistance, mitochondrial dysfunction and oxidative stress. To date, no specific pharmacological treatment for NAFLD, so lifestyle modifications such as: reduction in BW, diet and regular practice of physical exercise are effective, however it is not yet elucidated what the main impacts of physical exercise on NAFLD. Therefore, we proposed an experimental study that evaluated the effect of physical training on oxidative metabolism, hepatic and muscular mitochondrial function (soles) and hepatic lipogenesis in an ob / ob model of NAFLD. We used 14 (ob / ob) with leptin deficiency and divided into two groups: Sedentary (SED) = 7 and Trained (TF = 7) according to the mean BW balance. These animals were submitted to an 8-week protocol of aerobic physical training (AET) at 60% of the maximum velocity obtained in the running test performed on the last day of the week of adaptation to AET. In the fourth week the intensity adjustment was only done in the TF and the running capacity test was amplified in the eighth week in both groups to evaluate the performance of the animals in the variables linked to the AET. It was evaluated throughout the protocol: body weight (BW) on average, percentage, BW evolution and water and feed consumption. In the intrahepatic and muscular gene expression were analyzed: PGC-1Alpha, CPT-1Alpha and PPAR-Alpha related to mitochondrial functionality, in addition liver was analyzed: SREBP1. In the oxidative metabolism, we analyzed: biomarkers (MDA and carbonyls), enzymatic activity of SOD, CAT and GST, non-enzymatic anti-oxidant system: sulfhydryl, GSH and GSH / GSSG, metabolic enzymes (Citrate synthase and Beta-HAD). Hepatic histopathological analysis was performed by HE, in addition to the absolute and relative weight of the hepatic and white retroperitoneal, periepididimal and inguinal adipose tissues. In the intergroup analysis in relation to BW, a significant reduction was observed in the TF group, as well as in the water and feed intakes that were significantly lower after 8 weeks: In the analysis of hepatic gene expression we found an increase of PGC-1Alpha (p = 0.002) and CPT-1 = 0.0Alpha 3) in the TF group after 8 weeks of AET. In the soleus we found higher expression of the genes: PGC-1Alpha (p= 0.002) and CPT-1Alpha (p = 0.01). In relation to MDA and carbonyls there was no intergroup difference, as in SOD, CAT and GST. When we analyzed the non-enzymatic anti-oxidant system, we found that the TF had a higher activity of: sulfhydryls (p = 0.02), GSH (p = 0.001) and GSH / GSSG (p = 0.02) metabolic enzymes: citrate synthase (p = 0.004) and Beta-HAD (p = 0.01). In the weight of the organs the TF showed lower absolute and relative hepatic and retroperitoneal weight. In the histological analysis, there was no significant difference. Our data demonstrate that AET improved BW control, hyperphagia and liver and retroperitoneal weight, mitochondrial functionality and oxidative metabolism in (ob / ob) with NAFLD. Long-term AET intervention is needed so that we can visualize possible histological improvements. We considered the effective AET to improve aspects related to NAFLD