Mitogen driven differentiation of mononuclear cells is a useful model of antibody synthesis and secretion in humans. We have studied Pokeweed mitogen (PWM) induced immunoglobulin secretion in vitro in both healthy individuals and multiple sclerosis patients. Within the healthy population we have identified individuals who consistently secrete low levels of IgG in response to PWM and others who secrete very high levels. The underlying mechanisms involved in low response are not well understood. We have observed that the peripheral blood mononuclear cells (PBMC) obtained from low responders differ from those obtained from high responders in each of the following: Their T-helper cell subset contains a higher ratio of T suppressor-inducer cells over T helper-inducer cells; their PBMC contain a higher level of in vivo radiation-sensitive suppression; their PBMC generate a lower autologous mixed lymphocyte response; and their B lymphocytes secrete lower amounts of IgG when mixed with heterologous high responder T helper cells. These results suggest the response involves the interactions between T helper cell subsets, T suppressor cells and B lymphocytes and that the level of response is the sum of the contribution of each subset. PWM induced immunoglobulin secretion was measured in multiple sclerosis patients during different phases of clinical disease activity. Relapsing-remitting multiple sclerosis patients in early relapse secreted less immunoglobulin than patients with prolonged relapse, suggesting that immune function varies with clinical disease activity. Testing the level of PWM induced immunoglobulin secretion in relapsing-remitting multiple sclerosis patients during the clinically stable phase suggested that those patients who secreted high levels of IgG in response to PWM were more likely to suffer a clinical relapse within 6 months than those patients who secreted a low amount. Chronic progressive multiple sclerosis patients secreted higher amounts of immunoglobulin in this assay than healthy control individuals. This group of multiple sclerosis patients also had; (i) reduced Concanavalin A (Con A) suppressor cell activity measured both by the ability to suppress a/ Con A induced proliferation and b/ PWM induced IgG secretion in heterologous cell cultures and; (ii) reduced percentages of T cells expressing T suppressor and T suppressor-inducer markers. The treatment of chronic progressive multiple sclerosis patients in vivo with lymphoblastoid interferon resulted in a dramatic reduction in level of PWM induced immunoglobulin secretion without alteration in Concanavalin A induced suppression or in the percentages of T cells expressing subset specific markers. The PWM induced IgG secretion assay is a valuable technique for investigating the regulation of humoral immunity in both health and disease. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Despite earlier indirect evidence that an antral chalone exists, no such inhibitor has been found in antral extract. Recently, interest in the question of an antral inhibitory mechanism has been revived by studies that showed that for a given rise in serum gastrin caused by antral distension, the response of both the innervated and denervated stomach is greatly enhanced by vagal denervation of the antrum. While this study suggested a neuro-humoral character of the antral inhibitory mechanism, it gave no indication as to the source of the inhibitor. Subsequent studies, however, suggested that neither the antrum nor the CNS was the source for this inhibitor. The initial aim of this study was to investigate the fundus as a possible source of the inhibitor by studying the effect of proximal gastric vagotomy on the antral inhibitory mechanism initiated by distension. The results gave clear indication that the inhibitor was indeed released from the fundus; indeed, the antral inhibitory mechanism was in reality a fundic one. Once the fundus was shown to be the source of the inhibitor, it was necessary to establish whether this inhibitor did in fact reside in the fundic mucosa. Four dogs were prepared with a denervated fundic pouch (or Heidenhain pouch, HP), and a fistula of the main, innervated stomach (gastric fistula, GF). The acid secretory responses of both the HP and GF to graded doses of pentagastrin and histamine was studied. In addition both the secretion of acid and the response of immunoreactive gastrin in the blood in response to a standard meal of 15% liver extract was studied. All these experiments were repeated after excision of the fundic mucosa of the main stomach. The results show that excision of the fundic mucosa reduced the GF acid secretion to the stimuli by 85-100%. By contrast, the maximal HP acid secretion increased by 247% in response to pentagastrin and 200% in response to histamine. The increase in the response to submaximal doses of these exogenous stimuli was even greater. Similarly, the peak 30 minutes HP output in response to feeding increased by 418%. Fundic mucosal excision also resulted in the increase in both basal (from 36±3 to 248±37 pg/ml) and food-stimulated response (from 168±12 preoperatively to 392±49 pg/ml postoperatively). Since the intragastric pH was held constant at 5.5 during the meal tests both before and after the operation, the augmented gastrin response could not be attributed to reduced acid secretion caused by excision of the fundic mucosa. From these studies it can be concluded that: (1) antral distension releases an inhibitor from the fundus; (2) excision of the fundic mucosa results in increased response of the HP to both submaximal and maximal doses of pentagastrin and histamine indicating that both the sensitivity of the oxyntic cell and parietal cell mass has increased; (3) excision of the fundic mucosa results in increased basal and food-stimulated gastrin response independent of the pH of the meal suggesting removal of an inhibitor of gastrin release. / Surgery, Department of / Medicine, Faculty of / Graduate

(A) Gastric Secretion The present study was performed to investigate the canine post-pancreatic duct ligation GIP secretion in response to fat ingestion using a meat meal mixed with unhydrolyzed or hydrolyzed whipping cream, and to determine whether GIP plays a role in the production of hyperacid secretion in the pancreatic duct ligated dogs. Four mongrel female dogs were prepared with Heidenhain pouch (HP) and gastric fistula (GF), and daily acid secretion from the HP was measured before and after pancreatic duct ligation (PDL). HP acid output, serum immunoreactive gastrin (IR-Ga) and serum immunoreactive gastric inhibitory polypeptide (IR-GIP) concentrations during five hours following oral ingestion of a meat meal alone, a meat meal mixed with 125g of unhydrolyzed cream and meat meal mixed with 125g of hydrolyzed cream were measured before and after PDL. Twenty four hour HP acid outputs increased significantly in each of the four dogs after PDL. Five hour HP acid outputs in response to a meat meal alone and a meat meal plus unhydrolyzed cream were modestly increased, while those in response to a meat meal plus hydrolyzed cream were rather reduced after PDL. Serum IR-Ga responses to all stimulants were lowered after PDL and those to meat meal plus hydrolyzed cream lowered most markedly. Serum IR-GIP responses to a meat meal alone were significantly increased, while those to a meat meal plus unhydrolyzed and hydrolyzed cream were reduced. The results of the present study demonstrate serum IR-GIP in response to a meat meal is increased by PDL in dogs, suggesting augmented acid juice passing into the intestinal lumen is responsible for the increased GIP response. It is indicated that hypo-secretion of GIP is not the cause of hypersecretion of gastric acid in the PDL dogs. (B) Glucose Metabolism. Functional alteration in glucose homeostasis especially concerning the early onset of diabetes after PDL was studied in dogs. Intravenous (i.v.) and intragastric glucose tolerance tests were performed at two to ten weeks and two weeks after PDL respectively. Serum glucose, IRI, and IR-GIP in response to a meat meal with and without unhydrolyzed or hydrolyzed fat were estimated at six weeks after PDL. Significantly impaired glucose tolerance and early phase IRI secretion after i.v. glucose were shown at two to ten weeks after PDL. Intragastric glucose load revealed delayed pattern of serum glucose and IRI (no evidence of glucose intolerance or diminished IRI secretion), indicating decreased gastric motility after PDL. Serum IR-GIP response to intragastric glucose load was not attenuated by the operation but showed a similar pattern to IRI response. Serum IRI responses to meat meals with and without unhydrolyzed or hydrolyzed cream were impaired after PDL. It is indicated that dogs after PDL show early onset (two to ten weeks) of diabetes, i.e. blunted early phase insulin secretion, 2 the mechanism of GIP secretion as an insulinotropic enterohormone remains intact after PDL if sufficient stimulants are given. / Surgery, Department of / Medicine, Faculty of / Graduate

Orientadores: Everardo Magalhães Carneiro, Rosane Aparecida Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T08:39:55Z (GMT). No. of bitstreams: 1 Vettorazzi_JeanFranciesco_M.pdf: 1578894 bytes, checksum: 8f7aa3029a184083fe57d566c9524755 (MD5) Previous issue date: 2013 / Resumo: No acoplamento estímulo/secreção das células ?, os canais de K+ sensíveis ao ATP (KATP) e os canais de Ca2+ sensíveis à voltagem (Cav) contribuem para a geração e sustentação do potencial de ação. Alterações na sua expressão/atividade resultam em prejuízos na secreção de insulina. A restrição protéica e dieta hiperlipídica alteram o fluxo iônico e secreção de insulina nas células ?, e o aminoácido taurina (Tau) regula o fluxo iônico. O objetivo desse estudo foi caracterizar a expressão e o funcionamento dos KATP e Cav, assim como proteínas de extrusão dos grânulos de insulina em ilhotas pancreáticas de camundongos desnutridos alimentados com dieta hiperlipídica e suplementados com Tau. Camundongos machos C57Bl/6J receberam dieta controle (C) ou dieta lipoproteica (R) por 6 semanas. Em sequência metade desses grupos foi alimentados por 8 semanas com dieta hiperlipídica sem (CH e RH) ou com suplementação de 5% de Tau (CHT e RHT). Foi verificado que camundongos R tiveram menor crescimento e desenvolvimento dos órgãos. Camundongos RH e CH apresentaram aumento de peso corporal e estoques de gordura, hipercolesterolemia, intolerância à glicose e resistência à insulina. A suplementação com Tau preveniu o acúmulo de gordura e prejuízos na homeostase da glicose apenas no grupo CHT. Ilhotas isoladas de camundongos R secretaram menos insulina em resposta a 2,8 mM ou 11,1mM de glicose em associação com 30 mM de K+ ou 100 ?M de tolbutamida (Tolb). O influxo de Ca2+ em resposta à Tolb não diferiu entre ilhotas R e C. Ainda, ilhotas R tiveram redução do conteúdo total de insulina, da expressão protéica da SNAP-25, e aumento da subunidade Kir6.2 dos KATP e da sua atividade em resposta à glicose. Ilhotas CH secretaram mais insulina frente a 11,1 mM de glicose e agentes despolarizantes, associada à maior inibição dos KATP e ativação dos Cav em resposta à glicose. O grupo RH apresentou menor secreção de insulina frente a 2,8 mM de glicose e 30 mM de K+, e secreção similar ao grupo C frente a 11,1 mM de glicose e agentes despolarizantes, com aumento na expressão da SNAP-25 e inibição dos KATP em resposta à glicose. No grupo CHT houve normalização da liberação de insulina e aumento na expressão das subunidades ?1.2 e ?2 do Cav, SNAP-25 e sintaxina. Nas ilhotas RHT houve aumento na secreção de insulina frente à glicose e agentes despolarizantes, maior expressão da sintaxina e da subunidade Kir6.2 do KATP, bem como de sua inibição em resposta à glicose. Prejuízos na secreção de insulina no grupo R estão associados à menor expressão de proteínas envolvidas no processo exocitótico e aumento da expressão e atividade dos KATP. O grupo RH, com resistência à insulina similar ao grupo CH, não apresenta a mesma adaptação funcional das células ?, sem hipersecreção nesse grupo. A melhora na capacidade secretória do grupo RHT pode decorrer da ação da Tau sobre os KATP contribuindo para o adequado acoplamento estímulo/secreção e a extrusão dos grânulos de insulina via sintaxina / Abstract: In ? cells stimulus/secretion coupling, ATP-sensitive K+ channels (KATP) and voltage-sensitive Ca2+ channel (Cav) contribute to generating and sustaining the potential action. Changes in the expression or activity of these channels lead to insulin secretion impairment. Protein restriction as well as high-fat diet alters ?-cells ionic handling modifying insulin secretory profile. Taurine (Tau) regulates ion flux and improves ?-cell function. The aim of this study was to characterize the expression and function of KATP and Cav channels, as well as exocitotic proteins in isolated islets from malnourished mice submitted to high-fat diet and supplemented with Tau. Male C57Bl/6J mice received control (14% protein-C) or low-protein diet (6% protein-R) for 6 weeks. After, half of these groups were submitted to high-fat diet for 8 weeks without (CH and RH) or combined with 5% of Tau (CHT and RHT). Protein restricted mice showed lower growth and organs development. Both, CH and RH mice presented higher body weight, fat stores, hypercholesterolemia, glucose intolerance and insulin resistance. Tau supplementation prevented fat accumulation and glucose intolerance only in CHT group. Isolated islets from malnourished mice secreted less insulin in response to 2.8 mM glucose in combination with 30 mM K + or 100 ?M tolbutamide (Tolb). However, Ca2+ influx in these conditions did not differ. R group also released less insulin in response to 11.1 mM glucose in combination or not with depolarizing agents. In addition, R islets showed lower insulin and SNAP-25 protein content, whereas an increased protein expression of the Kir6.2 subunit of the KATP channel, as well as its activation during glucose stimulus. However, CH islets presented increased hormone release in the presence of 11.1 mM glucose in combination or not with depolaring agents, effect associated with enhanced KATP inhibition and Cav activation in response to glucose. RH group showed a lower insulin secretion in response to 2.8 mM glucose plus K+, and a similar secretion to C group upon 11.1 mM glucose together or not with depolarizing agents. Also, RH islets showed increased SNAP-25 protein levels. In CHT islets, Tau supplementation normalized insulin release and increased protein amount of ?1.2 and ?2 subunits of the Cav without modify its activity, and enhanced islet SNAP-25 and syntaxin protein levels. But, in RHT islets, enhanced insulin secretion in response to glucose and depolarizing agents, and increased syntaxin and Kir6.2 protein expression. In addition, RHT islets showed improved KATP inhibition and Cav activation in the presence of the sugar. In conclusion, insulin secretory dysfunction in R islets was associated with the lower expression of the exocytotic proteins and altered protein expression and activity of the KATP . Whereas, despite RH mice showed insulin resistance in a similar extent of that observed in CH mice, they did not present ?-cells functional adaptations to this condition, since RH islets did not hypersecret insulin. In addition, RHT islets presented a better secretory capacity probably due to the higher content of KATP and it inhibition induced by Tau which contributes to enhance the insulin exocytosis via syntaxin protein / Mestrado / Fisiologia / Mestre em Biologia Funcional e Molecular

No description available.

Orientadores: Everardo Magalhães Carneiro, Rosane Aparecida Ribeiro / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T15:27:40Z (GMT). No. of bitstreams: 1 Santos-Silva_JuniaCarolinaRebelo_D.pdf: 1918048 bytes, checksum: 70dc34ec9c47cef2caa60225a914173e (MD5) Previous issue date: 2014 / Resumo: A obesidade é um importante fator que predispõe ao desenvolvimento do diabetes mellitus tipo 2 (T2DM). A transição da obesidade para o T2DM é precedida pela resistência à insulina que pode se manifestar em resposta a influências ambientais, como a ingestão de dietas ricas em gorduras, ou por fatores genéticos, como a deficiência na produção do hormônio leptina. Camundongos obesos ob/ob são caracterizados pela ausência da produção do hormônio leptina e apresentam obesidade por hiperfagia. A taurina (Tau) é um aminoácido sulfatado não essencial e dentre suas várias ações biológicas destaca-se seu envolvimento na regulação da homeostase glicêmica e metabolismo energético. Nosso objetivo foi avaliar o efeito da suplementação com Tau sobre o desenvolvimento da obesidade, homeostase da glicose, estrutura e função do pâncreas endócrino em camundongos ob/ob. Foram utilizados camundongos C57 e ob/ob que beberam água (C e ob) ou 5% de Tau (CT e obT) dos 30 aos 90 dias de vida. Camundongos ob apresentaram massivo acúmulo de gordura corporal, intolerância à glicose e resistência à insulina. Essas alterações na homeostase à glicose foram acompanhadas por alterações morfológicas e funcionais adaptativas na ilhota pancreática dos camundongos ob, sendo evidenciada hipersecreção de insulina em resposta à glicose associada ao maior influxo de Ca 2+ e redução da ação da somatostina sobre a célula ?. Essa maior resposta secretória também pode estar associada à maior ação do sistema nervoso parassimpático, visto que ilhotas ob secretaram mais insulina em resposta ao agonista colinérgico, carbacol (Cch), e quando as proteínas kinases (PK)-A e C foram ativadas. Contudo, ilhotas de fêmeas ob não apresentaram redução da secreção de insulina em resposta à fenilefrina, o que sugere menor sensibilidade simpática nesse grupo. A suplementação com Tau não preveniu o desenvolvimento da obesidade, mas melhorou a tolerância à glicose, reduziu a produção hepática de glicose e aumentou a sensibilidade à insulina. Ilhotas de camundongos obT apresentaram atenuação da hipersecreção de insulina em resposta à glicose. Tal efeito pode estar associado à melhora na sensibilidade da ilhota obT à somatostatina e ao menor influxo de Ca 2+ em resposta a glicose, bem como redução da amplificação da secreção em resposta à ação da via colinérgica/PKC e a maior sensibilidade simpática na ilhota de fêmeas obT. Ainda, foi observada maior secreção de glucagon em ilhotas de camundongos ob. Essa alteração pode ser devida a alterações na excitação da célula ?, pois o grupo ob apresentou aumento da frequência de oscilações de Ca 2+ em resposta a concentrações basais e estimulatórias de glicose. Todas as alterações fisiológicas da ilhota pancreática foram acompanhadas por aumento da massa de ilhotas, células ? e ? no pâncreas de camundongos ob. A Tau reduziu a massa de ilhotas e células ?, contudo no pâncreas do grupo obT houve maior massa de células ? e ?. As modificações morfofuncionais da ilhota ob foram acompanhadas por redução da expressão gênica do glucagon, somatostatina, do GLUT-2, TRPM5, do SSTR2, e MafB, porém aumento do conteúdo de mRNA de insulina, PAX6, PDX-1 e Ngn3. A Tau normalizou a expressão dos genes do glucagon, Glut-2 e TRPM5 e aumentou a expressão de MafA, Ngn3 e NeuroD. Nossos resultados, pela primeira vez, demonstraram que a suplementação com Tau melhorou a homeostase glicêmica regulando a morfo-fisiologia das células ?, ? e ? em camundongos geneticamente obesos, indicando um possível papel do aminoácido na preservação da função pancreática endócrina e também da interação parácrina de seus hormônios na obesidade e T2DM / Abstract: Obesity is an important factor that predisposes to the development of type 2 diabetes mellitus (T2DM). The transition from obesity to T2DM is preceded by insulin resistance which can manifest in response to environmental influences such as the intake of high-fat diets or genetic factors, such as deficiency in the production of leptin. Obese (ob/ob) mice are characterized by the absence of production of leptin and become obese due to severe hyperfagia. Taurine (Tau) is a non-essential amino acid and among its various biological actions stands out its involvement in the regulation of glucose homeostasis and energy metabolism. Our aim was to evaluate the effect of Tau supplementation upon the development of obesity, glucose homeostasis, structure and function of the endocrine pancreas in ob/ob mice. We used C57 and ob/ob who drank water (C and ob) or 5% of Tau (CT and obT) from 30 to 90 days of age. Ob mice showed massive accumulation of body fat, glucose intolerance and insulin resistance. These changes in glucose homeostasis were followed by adaptive morphological and functional changes in the pancreatic islet from ob mice with hypersecretion of insulin in response to glucose associated with increased Ca 2+ influx and a reduction in somatostatin action on the ? cell. This increased secretory response was also associated with increased activity of the parasympathetic nervous system, as ob islets secrete more insulin in response to the cholinergic agonist carbachol (Cch), and when protein kinases (PK) -A and C pahtways were activated. However, female ob islets showed no reduction in insulin secretion in response to phenylephrine, suggesting diminished sympathetic sensitivity in this group. Tau supplementation did not prevent the development of obesity, but improved glucose tolerance, reduced hepatic glucose production and increased insulin sensitivity. Islets from obT mice showed attenuation of hypersecretion of insulin in response to glucose. This effect may be associated with improved sensitivity of obT islet to somatostatin and lower Ca 2+ influx in response to glucose and reduced the amplification of insulin secretion in response to cholinergic/PKC pathway and increased sympathetic sensitivity in islets from female obT mice. Moreover, we observed higher glucagon secretion in islets from ob mouse and this change may be due to changes in the excitement of ? cell because the ob group increased frequency of Ca 2+ oscillations in response to basal and stimulatory concentrations of glucose. All physiological changes were accompanied by an increase in islet, ? and ? cells masses in the pancreas from ob mice. Tau reduced the mass of islets and ? cells, however there was a higher content of ? and ? cells masses in obT. Morphological and functional modifications in islets from ob mice were accompanied by reduced gene expression of glucagon, somatostatin, GLUT-2, TRPM5, SSTR2, and MafB, but increased mRNA content of insulin, PAX6, PDX-1 and Ngn3. Tau normalized gene expression of glucagon, TRPM5 and GLUT-2 and increased the expression of MafA, Ngn3 and NeuroD. Our results indicate, for the first time, that supplementation with Tau improves glucose homeostasis by regulating the morphology and physiology of ?, ? and ? cells in ob mice, indicating a possible therapeutic role for preservation of pancreatic endocrine function in obesity and T2DM / Doutorado / Fisiologia / Doutora em Biologia Funcional e Molecular

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22665号 / 農博第2420号 / 新制||農||1080(附属図書館) / 学位論文||R2||N5296(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 栗原 達夫, 教授 小川 順, 教授 阪井 康能 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Orientador: Silvia Rodrigues Machado / Resumo: O gênero Jacaranda Juss. (Bignoniaceae), um representante da tribo Jacarandeae, é constituído por 47 espécies, das quais 39 são endêmicas para o Brasil. Este gênero se destaca dos demais gêneros de Bignoniaceae principalmente por apresentar estaminódio alongado glandular e forte potencial etnobotânico e fitoquímico em várias espécies ocorrentes no Brasil. Estruturas secretoras são sítios de produção de substâncias bioativas, estudos sobre distribuição, morfologia e organização anatômica e sua composição química podem contribuir para conhecimento de Jacaranda no âmbito biológico, químico e farmacológico. Neste contexto, o objetivo deste estudo foi realizar uma descrição anatômica foliar de 24 espécies de Jacaranda ressaltando características capazes de agrupar espécies e comparar com ambientes de ocorrência e evidenciar características diagnósticas para as espécies. Dentre elas, também foi objetivo desse estudo, realizar uma prospecção das estruturas secretoras foliares e florais em seis espécies associando o morfotipo das glândulas com sua localização, organização anatômica e as principais classes de compostos produzidos. Para isso, usamos técnicas rotineiras para o processamento de material herborizado e material coletado fresco para estudos anatômicos, micromorfológicos de superfície, histoquímicos e analises de agrupamento. Características morfológicas e anatômicas foliares, tais como, o tamanho, forma, tipo da margem e textura dos foliólulos, assim como a estrutura da ala... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The genus Jacaranda Juss. (Bignoniaceae), a representative of the Jacarandeae tribe, consists of 47 species, 39 of which are endemic to Brazil. This genus stands out from the other genera of Bignoniaceae mainly for presenting elongated glandular staminode and strong ethnobotanical and phytochemical potential in several species occurring in Brazil. Secretory structures are sites of production of bioactive substances, studies on distribution, morphology and anatomical organization and their chemical composition can contribute to Jacaranda knowledge in the biological, chemical and pharmacological fields. In this context, the objective of this study was to perform a leaf anatomical description of 24 species of Jacaranda highlighting characteristics capable of grouping species and comparing with occurrence environments and highlighting diagnostic characteristics for the species. Among them, it was also the aim of this study, to prospect for leaf and floral secretory structures in six species associating the gland morphotype with its location, anatomical organization and the main classes of compounds produced. For this, we use routine techniques for the processing of herborized material and fresh collected material for anatomical, surface micromorphological, histochemical and cluster analysis studies. Leaf morphological and anatomical characteristics, such as the size, shape, type of margin and texture of the leaflets, as well as the structure of the wing and edge, as well as the t... (Complete abstract click electronic access below) / Doutor

Rab GTPases are small signaling molecules that play an important role in vesicle trafficking in eukaryotic cells. Correct signaling through small GTPases allows orchestration of vesicle transport among cellular organelles and also to the cell wall providing cell wall material for cell growth and elongation. Engagement of Rab GTPases in the regulation of endomembrane trafficking is one of the evolutionary conserved aspects of secretion regulation. The network of Rab GTPases interaction includes also various downstream effectors. One of them is the exocyst complex involved in vesicle docking at the plasma membrane. It is a complex composed of eight different subunits (Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70 and Exo84). Exocyst was discovered as Sec4p Rab GTPase effector in yeast and also data from animal models describe the Sec15 exocyst subunit as the Rab-interacting partner, but data from plants are missing. On the other hand, numerous studies identified exocyst role in tip growth of pollen tube and root hairs, seed coat formation, cell plate and cell wall formation, hypocotyl elongation, and importantly also PIN auxin efflux carriers recycling and polar auxin transport. There are two paralogues of SEC15 in the Arabidopsis genome, SEC15a and SEC15b, the previous one already shown to be...

Plants have an artillery to defend themselves. The plant surface is protected by water- resistant cuticle and mechanically strong cell wall. Then each plant cell has tools to recognize and to answer to a pathogen threat. In an extreme case, the answer is programmed cell death. Plant immunity is a complex process integrating these passive and active mechanisms in an effort to overstay a pathogen attack. When the plant cell is attacked by a pathogen, the metabolic resources are redirected towards immunity reaction which results in growth restriction. Both the immunity reaction and the growth are dependent on the efficient polarized secretion of various cargoes. Exocyst complex mediates tethering of a secretory vesicle with a target membrane and SNARE complex orchestrates the subsequent steps of vesicle docking and fusion. Exocyst and SNAREs are regulated by various proteins. In my work, I focused on identifying the exocyst interaction partners in plant immunity. In cooperation with my colleagues, we found the direct association between Qa-SNARE SYP121 involved in plant penetration resistance and EXO70B2 exocyst subunit. Moreover, we confirmed the relevance of their interaction for the formation of epidermal defensive structures, papillae and haustorial encasements in plant defence against non-adapted...