PUB11-Dependent Ubiquitination of the Phospholipid Flippase ALA10 Modifies ALA10 Localization and Affects the Pool of Linolenic Phosphatidylcholine.

Biogenesis of photosynthetic membranes depends on galactolipid synthesis, which relies on several cell compartments, notably the endoplasmic reticulum (ER) and the chloroplast envelope. Galactolipid synthesis involves lipid trafficking between both membrane compartments. In Arabidopsis, ALA10, a phospholipid flippase of the P4 type-ATPase family, counteracts the limitation of monogalactosyldiacylglycerol (MGDG) production and has a positive effect on leaf development. ALA10 locates in distinct domains of the ER depending on the ALIS (ALA interacting subunit) subunit it interacts with: close to the plasma membrane with ALIS1, or next to chloroplasts with ALIS5. It interacts with FAD2 (Fatty acid desaturase 2) and prevents accumulation of linolenic (18:3) containing phosphatidylcholine (PC) stimulating an increase of MGDG synthesis. Here we report that ALA10 interacts with PUB11 (plant U-box type 11), an E3 protein ubiquitin ligase, in vitro and in vivo. ALA10 is however ubiquitinated and degraded by the 26S proteasome in a PUB11-independent process. In pub11 null mutant, the proteasome-dependent degradation of ALA10 is retained and ALA10 is still subject to ubiquitination although its ubiquitination profile appears different. In the absence of PUB11, ALA10 is constrained to the ER close to chloroplasts, which is the usual location when ALA10 is overexpressed. Additionally, in this condition, the decrease of 18:3 containing PC is no longer observed. Taken together these results suggest, that ALA10 contributes in chloroplast-distal ER interacting domains, to reduce the 18:3 desaturation of PC and that PUB11 is involved in reconditioning of ALA10 from chloroplast-proximal to chloroplast-distal ER interacting domains.

Importance of phosphatidylcholine on the chloroplast surface.

In plant cells, phosphatidylcholine (PC) is a major glycerolipid of most membranes but practically lacking from the plastid internal membranes. In chloroplasts, PC is absent from the thylakoids and the inner envelope membrane. It is however the main component of the outer envelope membrane, where it exclusively distributes in the outer monolayer. This unique distribution is likely related with operational compartmentalization of plant lipid metabolism. In this review, we summarize the different mechanisms involved in homeostasis of PC in plant cells. The specific origin of chloroplast PC is examined and the involvement of the P4-ATPase family of phospholipid flippases (ALA) is considered with a special attention to the recently reported effect of the endoplasmic reticulum-localized ALA10 on modification of chloroplast PC desaturation. The different possible roles of chloroplast PC are then discussed and analyzed in consideration of plant physiology.

New Insights on Thylakoid Biogenesis in Plant Cells.

Photosynthetic membranes, or thylakoids, are the most extensive membrane system found in the biosphere. They form flattened membrane cisternae in the cytosol of cyanobacteria and in the stroma of chloroplasts. The efficiency of light energy capture and conversion, critical for primary production in ecosystems, relies on the rapid expansion of thylakoids and their versatile reorganization in response to light changes. Thylakoid biogenesis results from the assembly of a lipid matrix combined with the incorporation of protein components. Four lipid classes are conserved from cyanobacteria to chloroplasts: mono- and digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol, and phosphatidyldiacylglycerol. This review focuses on the production and biophysical properties of galactolipids, making them determinant factors for the nonvesicular/nonlamellar biogenesis and for the three-dimensional architecture of nascent thylakoids. The regulation of MGD1, the committing enzyme of galactolipid biosynthesis in Arabidopsis, via feedback regulatory loops and control of protein binding to membranes, is also detailed.

ALA10, a Phospholipid Flippase, Controls FAD2/FAD3 Desaturation of Phosphatidylcholine in the ER and Affects Chloroplast Lipid Composition in Arabidopsis thaliana.

The biogenesis of photosynthetic membranes relies on galactoglycerolipids, which are synthesized via pathways that are dispatched over several cell compartments. This membrane biogenesis requires both trafficking of lipid intermediates and a tight homeostatic regulation. In this work, we address the role of ALA10 (for aminophospholipid ATPase), a P4-type ATPase, in a process counteracting the monogalactosyldiacylglycerol (MGDG) shortage in Arabidopsis (Arabidopsis thaliana) leaves. ALA10 can interact with protein partners, ALIS1 (for ALA-interacting subunit1) or ALIS5, leading to differential endomembrane localizations of the interacting proteins, close to the plasma membrane with ALIS1 or to chloroplasts with ALIS5. ALA10 interacts also with FATTY ACID DESATURASE2 (FAD2), and modification of ALA10 expression affects phosphatidylcholine (PC) fatty acyl desaturation by disturbing the balance between FAD2 and FAD3 activities. Modulation of ALA10 expression downstream impacts the fatty acyl composition of chloroplast PC. ALA10 expression also enhances leaf growth and improves the MGDG-PC ratio, possibly through MGDG SYNTHASE1 (MGD1) activation by phosphatidic acid. The positive effect of ALA10 on leaf development is significant in conditions such as upon treatment of plants with Galvestine-1, an inhibitor of MGDG synthases, or when plants are grown at chilling temperature.

On remembering: the notion of memory without recollection.

The author begins by attempting to evaluate the notions of memory and remembering, taking into account their evolution in Freud's work and the current debates on their relative importance in conducting an analytic treatment. This leads the author to develop an extension of the theory which none the less remains Freudian, by introducing a series of notions (the main ones being the work of figurability, regredience, state of session, negative of trauma, and memory without recollection), and arguing in favour of a principle of convergence-coherence governing mental life. His thesis is the following: analytic practice contains a dimension of an archaeological order, as Freud described it, as well as - thanks to the contribution of contemporary practice denouncing its insufficiency - the complementary need for the analyst to work in a particular way in the session - that is to say, one that involves what he calls a regredience of his or her thought processes, allowing him or her to gain access to early psychic zones beyond the zone of represented memories. This is what he calls transformational psychoanalysis, complementary to archeological psychoanalysis. The author's theoretical and practical developments are backed up by a personal schema of mental functioning, an extension of Freud's schema in 1900, and the detailed description of an analytic treatment, in particular, the central session which played a crucial role in the success of this analysis.

A obra de Green e a evolução do pensamento analítico / La obra de Green y la evolución del pensamiento analítico / Green’s work and the evolution in analytic thinking

A obra de André Green representa, para o autor, o melhor exemplo do que ele concebe como paradigma evolutivo: como as ciências duras, a psicanálise também possuiria a potencialidade de organizar um saber evolutivo; mas, diferentemente delas, evoluiria sem mudança de paradigma, mais por ampliação do paradigma fundador, que abre a psicanálise para novos campos da vida psíquica. Ela seria governada por um paradigma cujo caráter evolutivo resultaria do produto de um trabalho coletivo inconsciente de autores sucessivos.

André Green’s work represents, for the author, the best example of what he conceives as the evolutionary paradigm: just as hard sciences, psychoanalysis also possesses the potential of organizing an evolutionary knowledge; nevertheless, different from them, evolves with no paradigm change, but expanding the founding paradigm, which opens psychoanalysis to new fields of psychic life. It is governed by an evolutionary paradigm where the evolutionary characteristic is the product of an unconscious collective work of successive authors.

La obra de André Green representa, para el autor, el mejor ejemplo de lo que concibe como paradigma evolutivo: como las ciencias duras, el psicoanálisis también tendría la potencialidad de organizar un saber evolutivo; pero, a diferencia de ellas, evolucionaría sin cambio de paradigma, más por ampliación del paradigma fundador que abre el psicoanálisis hacia nuevos campos de la vida psíquica. Esta sería gobernada por un paradigma cuyo carácter evolutivo resultaría del producto de un trabajo colectivo inconsciente de autores sucesivos.

Místico, conhecimento e trauma / Místico, conocimiento y trauma / Mystic, knowledge and trauma

A última parte da obra de Bion se orienta, parece-nos, para preocupações mais místicas. Mas não se trata nem de um retorno ao passado nem de uma regressão. Muito ao contrário, estes trabalhos estão no nível dos trabalhos mais instigantes e desconcertantes de Freud, como “O futuro de uma ilusão” e “Moisés e o monoteísmo”. Bion vai submeter ao crivo da psicanálise esta necessidade essencial do homem, isto é, a necessidade de dar um sentido ao seu mundo.(AU)

La última parte de la obra de Bion se orienta, nos parece, para preocupaciones más místicas. Pero no se trata ni de un retorno al pasado ni de una regresión. Muy al contrario, estos trabajos están al nivel de los trabajos más instigantes y desconcertantes de Freud, como “El futuro de uma ilusión” y “El hombre Moisés”. Bion va a someter al cribo del psicoanálisis esta necesidad esencial del hombre, o sea la necesidad de dar sentido a su mundo.(AU)

It seems to us that the last part of Bion’s work is orientated towards mystical concerns. But it is not a return to the past or a regression. These works, on the contrary, are on the same level of Freud’s most instigating and disconcerting works, like “The Future of an Illusion” and “Moses the Man”. This essential need of man, that is, the need to give meaning to his world will be submitted by Bion to psychoanalysis’s scrutiny.(AU)

Místico, conhecimento e trauma / Místico, conocimiento y trauma / Mystic, knowledge and trauma

A última parte da obra de Bion se orienta, parece-nos, para preocupações mais místicas. Mas não se trata nem de um retorno ao passado nem de uma regressão. Muito ao contrário, estes trabalhos estão no nível dos trabalhos mais instigantes e desconcertantes de Freud, como “O futuro de uma ilusão” e “Moisés e o monoteísmo”. Bion vai submeter ao crivo da psicanálise esta necessidade essencial do homem, isto é, a necessidade de dar um sentido ao seu mundo.

La última parte de la obra de Bion se orienta, nos parece, para preocupaciones más místicas. Pero no se trata ni de un retorno al pasado ni de una regresión. Muy al contrario, estos trabajos están al nivel de los trabajos más instigantes y desconcertantes de Freud, como “El futuro de uma ilusión” y “El hombre Moisés”. Bion va a someter al cribo del psicoanálisis esta necesidad esencial del hombre, o sea la necesidad de dar sentido a su mundo.

It seems to us that the last part of Bion’s work is orientated towards mystical concerns. But it is not a return to the past or a regression. These works, on the contrary, are on the same level of Freud’s most instigating and disconcerting works, like “The Future of an Illusion” and “Moses the Man”. This essential need of man, that is, the need to give meaning to his world will be submitted by Bion to psychoanalysis’s scrutiny.

Trauma e rememoração, realidade e/ou convicção / Trauma and remembrance, reality and/or certainty

Uma nova concepção de trauma se impôs na psicanálise contemporânea. O autor defende a noção de trauma em negativo e descreve a necessidade de encontrar uma nova forma interpretativa que possa revelar esse negativo, que não constitui um traço mnésico, mas o que ele chama de 'memória sem lembranças'. Novos conceitos por ele apresentados mostram-se necessários para permitir pensar a prática e a teoria desta nova face da vida psíquica (AU)