Articles de revista
http://hdl.handle.net/2117/23869
2024-03-28T23:32:59ZHuman CASPR2 antibodies reversibly alter memory and the CASPR2 protein complex
http://hdl.handle.net/2117/363805
Human CASPR2 antibodies reversibly alter memory and the CASPR2 protein complex
Joubert, Bastien; Petit-Pedrol, Mar; Planagumà, Jesús; Mannara, Francesco; Radosevic, Marija; Marsal, Maria; Maudes, Estibaliz; García-Serra, Anna; Aguilar, Esther; Andrés-Bilbé, Alba; Gasull, Xavier; Loza-Alvarez, Pablo; Sabater, Lidia; Rosenfeld, Myrna R.; Dalmau, Josep
Objective
The encephalitis associated with antibodies against contactin-associated protein-like 2 (CASPR2) is presumably antibody-mediated but the antibody effects and whether they cause behavioral alterations are not well-known. Here, we used a mouse model of patients’ IgG transfer and super-resolution microscopy to demonstrate the antibody pathogenicity.
Methods
IgG from patients with anti-CASPR2 encephalitis or healthy controls were infused into the cerebroventricular system of mice. The levels and colocalization of CASPR2 with transient axonal glycoprotein-1 (TAG1) were determined with Stimulated Emission Depletion (STED) microscopy (40-70μm lateral resolution). Hippocampal clusters of Kv1.1 voltage-gated potassium channels (VGKC) and GluA1-containing AMPA receptors were quantified with confocal microscopy. Behavioral alterations were assessed with standard behavioral paradigms. Cultured neurons were used to determine the levels of intracellular CASPR2 and TAG1 after exposure to patients’ IgG.
Results
Infusion of patients’ IgG, but not control IgG, caused memory impairment along with hippocampal reduction of surface CASPR2 clusters and decreased CASPR2/TAG1 colocalization. In cultured neurons, patients’ IgG led to an increase of intracellular CASPR2 without affecting TAG1, suggesting selective CASPR2 internalization. Additionally, mice infused with patients’ IgG showed decreased levels of Kv1.1 and GluA1 (two CASPR2 regulated proteins). All these alterations and the memory deficit reverted to normal after removing patients’ IgG.
Interpretation
IgG from patients with anti-CASPR2 encephalitis cause reversible memory impairment, inhibit the interaction of CASPR2/TAG1, and decrease the levels of CASPR2 and related proteins (VGKC, AMPAR). These findings fulfill the postulates of antibody-mediated disease and provide a biological basis for antibody-removing treatment approaches.
2022-03-10T10:09:22ZJoubert, BastienPetit-Pedrol, MarPlanagumà, JesúsMannara, FrancescoRadosevic, MarijaMarsal, MariaMaudes, EstibalizGarcía-Serra, AnnaAguilar, EstherAndrés-Bilbé, AlbaGasull, XavierLoza-Alvarez, PabloSabater, LidiaRosenfeld, Myrna R.Dalmau, JosepObjective
The encephalitis associated with antibodies against contactin-associated protein-like 2 (CASPR2) is presumably antibody-mediated but the antibody effects and whether they cause behavioral alterations are not well-known. Here, we used a mouse model of patients’ IgG transfer and super-resolution microscopy to demonstrate the antibody pathogenicity.
Methods
IgG from patients with anti-CASPR2 encephalitis or healthy controls were infused into the cerebroventricular system of mice. The levels and colocalization of CASPR2 with transient axonal glycoprotein-1 (TAG1) were determined with Stimulated Emission Depletion (STED) microscopy (40-70μm lateral resolution). Hippocampal clusters of Kv1.1 voltage-gated potassium channels (VGKC) and GluA1-containing AMPA receptors were quantified with confocal microscopy. Behavioral alterations were assessed with standard behavioral paradigms. Cultured neurons were used to determine the levels of intracellular CASPR2 and TAG1 after exposure to patients’ IgG.
Results
Infusion of patients’ IgG, but not control IgG, caused memory impairment along with hippocampal reduction of surface CASPR2 clusters and decreased CASPR2/TAG1 colocalization. In cultured neurons, patients’ IgG led to an increase of intracellular CASPR2 without affecting TAG1, suggesting selective CASPR2 internalization. Additionally, mice infused with patients’ IgG showed decreased levels of Kv1.1 and GluA1 (two CASPR2 regulated proteins). All these alterations and the memory deficit reverted to normal after removing patients’ IgG.
Interpretation
IgG from patients with anti-CASPR2 encephalitis cause reversible memory impairment, inhibit the interaction of CASPR2/TAG1, and decrease the levels of CASPR2 and related proteins (VGKC, AMPAR). These findings fulfill the postulates of antibody-mediated disease and provide a biological basis for antibody-removing treatment approaches.The nucleus measures shape changes for cellular proprioception to control dynamic cell behavior
http://hdl.handle.net/2117/331106
The nucleus measures shape changes for cellular proprioception to control dynamic cell behavior
Venturini, Valeria; Pezzano, Fabio; Català Castro, Frederic; Häkkinen, Hanna-Maria; Jiménez-Delgado, Senda; Colomer Rosell, Mariona; Marro, Monica; Tolosa-Ramon, Queralt; Paz-López, Sonia; Valverde, Miguel A.; Weghuber, Julian; Loza- Alvarez, Pablo; Krieg, Michael; Wieser, Stefan; Ruprecht, Verena
Single cells continuously experience and react to mechanical challenges in three-dimensional tissues. Spatial constraints in dense tissues, physical activity, and injury all impose changes in cell shape. How cells can measure shape deformations to ensure correct tissue development and homeostasis remains largely unknown (see the Perspective by Shen and Niethammer). Working independently, Venturini et al. and Lomakin et al. now show that the nucleus can act as an intracellular ruler to measure cellular shape variations. The nuclear envelope provides a gauge of cell deformation and activates a mechanotransduction pathway that controls actomyosin contractility and migration plasticity. The cell nucleus thereby allows cells to adapt their behavior to the local tissue microenvironment.
2020-11-02T10:54:46ZVenturini, ValeriaPezzano, FabioCatalà Castro, FredericHäkkinen, Hanna-MariaJiménez-Delgado, SendaColomer Rosell, MarionaMarro, MonicaTolosa-Ramon, QueraltPaz-López, SoniaValverde, Miguel A.Weghuber, JulianLoza- Alvarez, PabloKrieg, MichaelWieser, StefanRuprecht, VerenaSingle cells continuously experience and react to mechanical challenges in three-dimensional tissues. Spatial constraints in dense tissues, physical activity, and injury all impose changes in cell shape. How cells can measure shape deformations to ensure correct tissue development and homeostasis remains largely unknown (see the Perspective by Shen and Niethammer). Working independently, Venturini et al. and Lomakin et al. now show that the nucleus can act as an intracellular ruler to measure cellular shape variations. The nuclear envelope provides a gauge of cell deformation and activates a mechanotransduction pathway that controls actomyosin contractility and migration plasticity. The cell nucleus thereby allows cells to adapt their behavior to the local tissue microenvironment.Unravelling the Metabolic Progression of Breast Cancer Cells to Bone Metastasis by Coupling Raman Spectroscopy and a Novel Use of Mcr-Als Algorithm
http://hdl.handle.net/2117/117522
Unravelling the Metabolic Progression of Breast Cancer Cells to Bone Metastasis by Coupling Raman Spectroscopy and a Novel Use of Mcr-Als Algorithm
Marro, Monica; Nieva, Claudia; Juan, Anna de; Sierra, Angels
Raman spectroscopy (RS) has shown promise as a tool to reveal biochemical changes that occur in cancer processes at the cellular level. However, when analyzing clinical samples, RS requires improvements to be able to resolve biological components from the spectra. We compared the strengths of Multivariate Curve Resolution (MCR) versus Principal Component Analysis (PCA) to deconvolve meaningful biological components formed by distinct mixtures of biological molecules from a set of mixed spectra. We exploited the flexibility of the MCR algorithm to easily accommodate different initial estimates and constraints. We demonstrate the ability of MCR to resolve undesired background signals from the RS that can be subtracted to obtain clearer cancer cell spectra. We used two triple negative breast cancer cell lines, MDA-MB 231 and MDA-MB 435, to illustrate the insights obtained by RS that infer the metabolic changes required for metastasis progression. Our results show that increased levels of amino acids and lower levels of mitochondrial signals are attributes of bone metastatic cells, whereas lung metastasis tropism is characterized by high lipid and mitochondria levels. Therefore, we propose a method based on the MCR algorithm to achieve unique biochemical insights into the molecular progression of cancer cells using RS.
2018-05-25T11:54:03ZMarro, MonicaNieva, ClaudiaJuan, Anna deSierra, AngelsRaman spectroscopy (RS) has shown promise as a tool to reveal biochemical changes that occur in cancer processes at the cellular level. However, when analyzing clinical samples, RS requires improvements to be able to resolve biological components from the spectra. We compared the strengths of Multivariate Curve Resolution (MCR) versus Principal Component Analysis (PCA) to deconvolve meaningful biological components formed by distinct mixtures of biological molecules from a set of mixed spectra. We exploited the flexibility of the MCR algorithm to easily accommodate different initial estimates and constraints. We demonstrate the ability of MCR to resolve undesired background signals from the RS that can be subtracted to obtain clearer cancer cell spectra. We used two triple negative breast cancer cell lines, MDA-MB 231 and MDA-MB 435, to illustrate the insights obtained by RS that infer the metabolic changes required for metastasis progression. Our results show that increased levels of amino acids and lower levels of mitochondrial signals are attributes of bone metastatic cells, whereas lung metastasis tropism is characterized by high lipid and mitochondria levels. Therefore, we propose a method based on the MCR algorithm to achieve unique biochemical insights into the molecular progression of cancer cells using RS.Light-sheet microscopy: a tutorial
http://hdl.handle.net/2117/114544
Light-sheet microscopy: a tutorial
Olarte, Omar E.; Andilla, Jordi; Gualda, Emilio J.; Loza-Alvarez, Pablo
This paper is intended to give a comprehensive review of light-sheet (LS) microscopy from an optics perspective. As such, emphasis is placed on the advantages that LS microscope configurations present, given the degree of freedom gained by uncoupling the excitation and detection arms. The new imaging properties are first highlighted in terms of optical parameters and how these have enabled several biomedical applications. Then, the basics are presented for understanding how a LS microscope works. This is followed by a presentation of a tutorial for LS microscope designs, each working at different resolutions and for different applications. Then, based on a numerical Fourier analysis and given the multiple possibilities for generating the LS in the microscope (using Gaussian, Bessel, and Airy beams in the linear and nonlinear regimes), a systematic comparison of their optical performance is presented. Finally, based on advances in optics and photonics, the novel optical implementations possible in a LS microscope are highlighted.
2018-02-27T13:01:35ZOlarte, Omar E.Andilla, JordiGualda, Emilio J.Loza-Alvarez, PabloThis paper is intended to give a comprehensive review of light-sheet (LS) microscopy from an optics perspective. As such, emphasis is placed on the advantages that LS microscope configurations present, given the degree of freedom gained by uncoupling the excitation and detection arms. The new imaging properties are first highlighted in terms of optical parameters and how these have enabled several biomedical applications. Then, the basics are presented for understanding how a LS microscope works. This is followed by a presentation of a tutorial for LS microscope designs, each working at different resolutions and for different applications. Then, based on a numerical Fourier analysis and given the multiple possibilities for generating the LS in the microscope (using Gaussian, Bessel, and Airy beams in the linear and nonlinear regimes), a systematic comparison of their optical performance is presented. Finally, based on advances in optics and photonics, the novel optical implementations possible in a LS microscope are highlighted.Interference with Clp protease impairs carotenoid accumulation during tomato fruit ripening
http://hdl.handle.net/2117/114194
Interference with Clp protease impairs carotenoid accumulation during tomato fruit ripening
Andrea, Lucio D’; Simon-Moya, Miguel; Llorente, Briardo; Llamas, Ernesto; Loza-Alvarez, Pablo; Li, Li; Rodriguez-Concepcion, Manuel
Profound metabolic and structural changes are required for fleshy green fruits to ripen and become colorful and tasty.
In tomato (Solanum lycopersicum), fruit ripening involves the differentiation of chromoplasts, specialized plastids that
accumulate carotenoid pigments such as β-carotene (pro-vitamin A) and lycopene. Here, we explored the role of the
plastidial Clp protease in chromoplast development and carotenoid accumulation. Ripening-specific silencing of one
of the subunits of the Clp proteolytic complex resulted in β-carotene-enriched fruits that appeared orange instead
of red when ripe. Clp-defective fruit displayed aberrant chromoplasts and up-regulated expression of nuclear genes
encoding the tomato homologs of Orange (OR) and ClpB3 chaperones, most probably to deal with misfolded and
aggregated proteins that could not be degraded by the Clp protease. ClpB3 and OR chaperones protect the carotenoid
biosynthetic enzymes deoxyxylulose 5-phosphate synthase and phytoene synthase, respectively, from degradation,
whereas OR chaperones additionally promote chromoplast differentiation by preventing the degradation of
carotenoids such as β-carotene. We conclude that the Clp protease contributes to the differentiation of chloroplasts
into chromoplasts during tomato fruit ripening, acting in co-ordination with specific chaperones that alleviate protein
folding stress, promote enzyme stability and accumulation, and prevent carotenoid degradation
2018-02-16T12:29:52ZAndrea, Lucio D’Simon-Moya, MiguelLlorente, BriardoLlamas, ErnestoLoza-Alvarez, PabloLi, LiRodriguez-Concepcion, ManuelProfound metabolic and structural changes are required for fleshy green fruits to ripen and become colorful and tasty.
In tomato (Solanum lycopersicum), fruit ripening involves the differentiation of chromoplasts, specialized plastids that
accumulate carotenoid pigments such as β-carotene (pro-vitamin A) and lycopene. Here, we explored the role of the
plastidial Clp protease in chromoplast development and carotenoid accumulation. Ripening-specific silencing of one
of the subunits of the Clp proteolytic complex resulted in β-carotene-enriched fruits that appeared orange instead
of red when ripe. Clp-defective fruit displayed aberrant chromoplasts and up-regulated expression of nuclear genes
encoding the tomato homologs of Orange (OR) and ClpB3 chaperones, most probably to deal with misfolded and
aggregated proteins that could not be degraded by the Clp protease. ClpB3 and OR chaperones protect the carotenoid
biosynthetic enzymes deoxyxylulose 5-phosphate synthase and phytoene synthase, respectively, from degradation,
whereas OR chaperones additionally promote chromoplast differentiation by preventing the degradation of
carotenoids such as β-carotene. We conclude that the Clp protease contributes to the differentiation of chloroplasts
into chromoplasts during tomato fruit ripening, acting in co-ordination with specific chaperones that alleviate protein
folding stress, promote enzyme stability and accumulation, and prevent carotenoid degradationTranscriptome analysis in tissue sectors with contrasting crocins accumulation provides novel insights into apocarotenoid biosynthesis and regulation during chromoplast biogenesis
http://hdl.handle.net/2117/114062
Transcriptome analysis in tissue sectors with contrasting crocins accumulation provides novel insights into apocarotenoid biosynthesis and regulation during chromoplast biogenesis
Ahrazem, O.; Argandoña, J.; Fiore, A.; Aguado, C.; Luján, R.; Rubio-Moraga, A.; Marro, M.; Araujo-Andrade, C.; Loza-Alvarez, P.; Diretto, G.; Gómez-Gómez, L.
Crocins, the red soluble apocarotenoids of saffron, accumulate in the flowers of Crocus species in a developmental and tissue-specific manner. In Crocus sieberi, crocins accumulate in stigmas but also in a distinct yellow tepal sector, which we demonstrate contains chromoplast converted from amyloplasts. Secondary metabolites were analysed by LC-DAD-HRMS, revealing the progressive accumulation of crocetin and crocins in the yellow sector, which were also localized in situ by Raman microspectroscopy. To understand the underlying mechanisms of crocin biosynthesis, we sequenced the C. sieberi tepal transcriptome of two differentially pigmented sectors (yellow and white) at two developmental stages (6 and 8) by Illumina sequencing. A total of 154 million high-quality reads were generated and assembled into 248,099 transcripts. Differentially expressed gene analysis resulted in the identification of several potential candidate genes involved in crocin metabolism and regulation. The results provide a first profile of the molecular events related to the dynamics of crocetin and crocin accumulation during tepal development, and present new information concerning apocarotenoid biosynthesis regulators and their accumulation in Crocus. Further, reveals genes that were previously unknown to affect crocin formation, which could be used to improve crocin accumulation in Crocus plants and the commercial quality of saffron spice.
2018-02-12T15:43:52ZAhrazem, O.Argandoña, J.Fiore, A.Aguado, C.Luján, R.Rubio-Moraga, A.Marro, M.Araujo-Andrade, C.Loza-Alvarez, P.Diretto, G.Gómez-Gómez, L.Crocins, the red soluble apocarotenoids of saffron, accumulate in the flowers of Crocus species in a developmental and tissue-specific manner. In Crocus sieberi, crocins accumulate in stigmas but also in a distinct yellow tepal sector, which we demonstrate contains chromoplast converted from amyloplasts. Secondary metabolites were analysed by LC-DAD-HRMS, revealing the progressive accumulation of crocetin and crocins in the yellow sector, which were also localized in situ by Raman microspectroscopy. To understand the underlying mechanisms of crocin biosynthesis, we sequenced the C. sieberi tepal transcriptome of two differentially pigmented sectors (yellow and white) at two developmental stages (6 and 8) by Illumina sequencing. A total of 154 million high-quality reads were generated and assembled into 248,099 transcripts. Differentially expressed gene analysis resulted in the identification of several potential candidate genes involved in crocin metabolism and regulation. The results provide a first profile of the molecular events related to the dynamics of crocetin and crocin accumulation during tepal development, and present new information concerning apocarotenoid biosynthesis regulators and their accumulation in Crocus. Further, reveals genes that were previously unknown to affect crocin formation, which could be used to improve crocin accumulation in Crocus plants and the commercial quality of saffron spice.Synaptic phosphorylated a-synuclein in dementia with Lewy bodies
http://hdl.handle.net/2117/111726
Synaptic phosphorylated a-synuclein in dementia with Lewy bodies
Colom-Cadena, Martí; Pegueroles, Jordi; Herrmann, Abigail G.; Henstridge, Christopher M.; Muñoz, Laia; Querol-Vilaseca, Marta; San Martin, Carla; Luque-Cabecerans, Joan; Clarimon, Jordi; Belbin, Olivia; Nuñez-Llaves, Raúl; Blesa, Rafael; Smith, Colin; McKenzie, Chris-Anne; Frosch, Matthew P.; Roe, Allyson; Fortea, Juan; Andilla, Jordi; Loza-Alvarez, Pablo; Gelpi, Ellen; Hyman, Bradley T.; Spires-Jone, Tara L.; Lleó, Alberto
Dementia with Lewy bodies is characterized by the accumulation of Lewy bodies and Lewy neurites in the CNS, both of which are
composed mainly of aggregated a-synuclein phosphorylated at Ser129. Although phosphorylated a-synuclein is believed to exert
toxic effects at the synapse in dementia with Lewy bodies and other a-synucleinopathies, direct evidence for the precise synaptic
localization has been difficult to achieve due to the lack of adequate optical microscopic resolution to study human synapses. In the
present study we applied array tomography, a microscopy technique that combines ultrathin sectioning of tissue with immunofluorescence
allowing precise identification of small structures, to quantitatively investigate the synaptic phosphorylated a-synuclein
pathology in dementia with Lewy bodies. We performed array tomography on human brain samples from five patients with
dementia with Lewy bodies, five patients with Alzheimer’s disease and five healthy control subjects to analyse the presence of
phosphorylated a-synuclein immunoreactivity at the synapse and their relationship with synapse size. Main analyses were performed
in blocks from cingulate cortex and confirmed in blocks from the striatum of cases with dementia with Lewy bodies. A
total of 1 318 700 single pre- or post-synaptic terminals were analysed. We found that phosphorylated a-synuclein is present
exclusively in dementia with Lewy bodies cases, where it can be identified in the form of Lewy bodies, Lewy neurites and
small aggregates (50.16 mm3). Between 19% and 25% of phosphorylated a-synuclein deposits were found in presynaptic terminals
mainly in the form of small aggregates. Synaptic terminals that co-localized with small aggregates of phosphorylated a-synuclein
were significantly larger than those that did not. Finally, a gradient of phosphorylated a-synuclein aggregation in synapses
(pre4pre + post4post-synaptic) was observed. These results indicate that phosphorylated a-synuclein is found at the presynaptic
terminals of dementia with Lewy bodies cases mainly in the form of small phosphorylated a-synuclein aggregates that are
associated with changes in synaptic morphology. Overall, our data support the notion that pathological phosphorylated a-synuclein
may disrupt the structure and function of the synapse in dementia with Lewy bodies.
2017-12-11T16:49:11ZColom-Cadena, MartíPegueroles, JordiHerrmann, Abigail G.Henstridge, Christopher M.Muñoz, LaiaQuerol-Vilaseca, MartaSan Martin, CarlaLuque-Cabecerans, JoanClarimon, JordiBelbin, OliviaNuñez-Llaves, RaúlBlesa, RafaelSmith, ColinMcKenzie, Chris-AnneFrosch, Matthew P.Roe, AllysonFortea, JuanAndilla, JordiLoza-Alvarez, PabloGelpi, EllenHyman, Bradley T.Spires-Jone, Tara L.Lleó, AlbertoDementia with Lewy bodies is characterized by the accumulation of Lewy bodies and Lewy neurites in the CNS, both of which are
composed mainly of aggregated a-synuclein phosphorylated at Ser129. Although phosphorylated a-synuclein is believed to exert
toxic effects at the synapse in dementia with Lewy bodies and other a-synucleinopathies, direct evidence for the precise synaptic
localization has been difficult to achieve due to the lack of adequate optical microscopic resolution to study human synapses. In the
present study we applied array tomography, a microscopy technique that combines ultrathin sectioning of tissue with immunofluorescence
allowing precise identification of small structures, to quantitatively investigate the synaptic phosphorylated a-synuclein
pathology in dementia with Lewy bodies. We performed array tomography on human brain samples from five patients with
dementia with Lewy bodies, five patients with Alzheimer’s disease and five healthy control subjects to analyse the presence of
phosphorylated a-synuclein immunoreactivity at the synapse and their relationship with synapse size. Main analyses were performed
in blocks from cingulate cortex and confirmed in blocks from the striatum of cases with dementia with Lewy bodies. A
total of 1 318 700 single pre- or post-synaptic terminals were analysed. We found that phosphorylated a-synuclein is present
exclusively in dementia with Lewy bodies cases, where it can be identified in the form of Lewy bodies, Lewy neurites and
small aggregates (50.16 mm3). Between 19% and 25% of phosphorylated a-synuclein deposits were found in presynaptic terminals
mainly in the form of small aggregates. Synaptic terminals that co-localized with small aggregates of phosphorylated a-synuclein
were significantly larger than those that did not. Finally, a gradient of phosphorylated a-synuclein aggregation in synapses
(pre4pre + post4post-synaptic) was observed. These results indicate that phosphorylated a-synuclein is found at the presynaptic
terminals of dementia with Lewy bodies cases mainly in the form of small phosphorylated a-synuclein aggregates that are
associated with changes in synaptic morphology. Overall, our data support the notion that pathological phosphorylated a-synuclein
may disrupt the structure and function of the synapse in dementia with Lewy bodies.High-Resolution Morphological Approach to Analyse Elastic Laminae Injuries of the Ascending Aorta in a Murine Model of Marfan Syndrome
http://hdl.handle.net/2117/104182
High-Resolution Morphological Approach to Analyse Elastic Laminae Injuries of the Ascending Aorta in a Murine Model of Marfan Syndrome
López-Guimet, Júlia; Andilla, Jordi; Loza-Álvarez, Pablo; Egea, Gustavo
In Marfan syndrome, the tunica media is disrupted, which leads to the formation of ascending aortic
aneurysms. Marfan aortic samples are histologically characterized by the fragmentation of elastic
laminae. However, conventional histological techniques using transverse sections provide limited
information about the precise location, progression and 3D extension of the microstructural changes
that occur in each lamina. We implemented a method using multiphoton excitation fluorescence
microscopy and computational image processing, which provides high-resolution en-face images
of segmented individual laminae from unstained whole aortic samples. We showed that internal
elastic laminae and successive 2nd laminae are injured to a different extent in murine Marfan aortae;
in particular, the density and size of fenestrae changed. Moreover, microstructural injuries were
concentrated in the aortic proximal and convex anatomical regions. Other parameters such as the
waviness and thickness of each lamina remained unaltered. In conclusion, the method reported here is
a useful, unique tool for en-face laminae microstructure assessment that can obtain quantitative threedimensional
information about vascular tissue. The application of this method to murine Marfan aortae
clearly shows that the microstructural damage in elastic laminae is not equal throughout the thickness
of the tunica media and in the different anatomical regions of the ascending aorta.
2017-05-08T11:04:27ZLópez-Guimet, JúliaAndilla, JordiLoza-Álvarez, PabloEgea, GustavoIn Marfan syndrome, the tunica media is disrupted, which leads to the formation of ascending aortic
aneurysms. Marfan aortic samples are histologically characterized by the fragmentation of elastic
laminae. However, conventional histological techniques using transverse sections provide limited
information about the precise location, progression and 3D extension of the microstructural changes
that occur in each lamina. We implemented a method using multiphoton excitation fluorescence
microscopy and computational image processing, which provides high-resolution en-face images
of segmented individual laminae from unstained whole aortic samples. We showed that internal
elastic laminae and successive 2nd laminae are injured to a different extent in murine Marfan aortae;
in particular, the density and size of fenestrae changed. Moreover, microstructural injuries were
concentrated in the aortic proximal and convex anatomical regions. Other parameters such as the
waviness and thickness of each lamina remained unaltered. In conclusion, the method reported here is
a useful, unique tool for en-face laminae microstructure assessment that can obtain quantitative threedimensional
information about vascular tissue. The application of this method to murine Marfan aortae
clearly shows that the microstructural damage in elastic laminae is not equal throughout the thickness
of the tunica media and in the different anatomical regions of the ascending aorta.STED imaging performance estimation by means of Fourier transform analysis
http://hdl.handle.net/2117/103681
STED imaging performance estimation by means of Fourier transform analysis
Merino, David; Mallabiabarrena, Arrate; Andilla, Jordi; Artigas García, David; Zimmermann, Timo; Loza Álvarez, Pablo
Due to relatively high powers used in STED, biological samples may be affected
by the illumination in the process of image acquisition. Similarly, the performance of the
system may be limited by the sample itself. Optimization of the STED parameters taking into
account the sample itself is therefore a complex task as there is no clear methodology that can
determine the image improvement in an objective and quantitative manner. In this work, a
method based on Fourier transform formalism is presented to analyze the performance of a
STED system. The spatial frequency distribution of pairs of confocal and STED images are
compared to obtain an objective parameter, the Azimuth Averaged Spectral Content Spread
(AASCS), that is related to the performance of the system in which the sample is also
considered. The method has been first tested on samples of beads, and then applied to cell
samples labeled with multiple fluorescent dyes. The results show that a single parameter, the
AASCS, can be used to determine the optimal settings for STED image acquisition in an
objective way, only by using the information provided by the images from the sample
themselves. The AASCS also helps minimize the depletion power, for better preservation of
the samples.
2017-04-24T15:38:29ZMerino, DavidMallabiabarrena, ArrateAndilla, JordiArtigas García, DavidZimmermann, TimoLoza Álvarez, PabloDue to relatively high powers used in STED, biological samples may be affected
by the illumination in the process of image acquisition. Similarly, the performance of the
system may be limited by the sample itself. Optimization of the STED parameters taking into
account the sample itself is therefore a complex task as there is no clear methodology that can
determine the image improvement in an objective and quantitative manner. In this work, a
method based on Fourier transform formalism is presented to analyze the performance of a
STED system. The spatial frequency distribution of pairs of confocal and STED images are
compared to obtain an objective parameter, the Azimuth Averaged Spectral Content Spread
(AASCS), that is related to the performance of the system in which the sample is also
considered. The method has been first tested on samples of beads, and then applied to cell
samples labeled with multiple fluorescent dyes. The results show that a single parameter, the
AASCS, can be used to determine the optimal settings for STED image acquisition in an
objective way, only by using the information provided by the images from the sample
themselves. The AASCS also helps minimize the depletion power, for better preservation of
the samples.Polarized cortical tension drives zebrafish epiboly movements
http://hdl.handle.net/2117/103032
Polarized cortical tension drives zebrafish epiboly movements
Hernández-Vega, Amayra; Marsal, María; Pouille, Philippe-Alexandre; Tosi, Sebastien; Colombelli, Julien; Luque, Tomás; Navajas, Daniel; Pagonabarraga, Ignacio; Martín-Blanco, Enrique
The principles underlying the biomechanics of morphogenesis are
largely unknown. Epiboly is an essential embryonic event in which
three tissues coordinate to direct the expansion of the blastoderm.
How and where forces are generated during epiboly, and how
these are globally coupled remains elusive. Here we developed a
method, hydrodynamic regression (HR), to infer 3D pressure fields,
mechanical power, and cortical surface tension profiles. HR is
based on velocity measurements retrieved from 2D+T microscopy
and their hydrodynamic modeling. We applied HR to identify
biomechanically active structures and changes in cortex local
tension during epiboly in zebrafish. Based on our results, we
propose a novel physical description for epiboly, where tissue
movements are directed by a polarized gradient of cortical tension.
We found that this gradient relies on local contractile forces at the
cortex, differences in elastic properties between cortex components
and the passive transmission of forces within the yolk cell.
All in all, our work identifies a novel way to physically regulate
concerted cellular movements that might be instrumental for the
mechanical control of many morphogenetic processes.
2017-03-29T11:00:58ZHernández-Vega, AmayraMarsal, MaríaPouille, Philippe-AlexandreTosi, SebastienColombelli, JulienLuque, TomásNavajas, DanielPagonabarraga, IgnacioMartín-Blanco, EnriqueThe principles underlying the biomechanics of morphogenesis are
largely unknown. Epiboly is an essential embryonic event in which
three tissues coordinate to direct the expansion of the blastoderm.
How and where forces are generated during epiboly, and how
these are globally coupled remains elusive. Here we developed a
method, hydrodynamic regression (HR), to infer 3D pressure fields,
mechanical power, and cortical surface tension profiles. HR is
based on velocity measurements retrieved from 2D+T microscopy
and their hydrodynamic modeling. We applied HR to identify
biomechanically active structures and changes in cortex local
tension during epiboly in zebrafish. Based on our results, we
propose a novel physical description for epiboly, where tissue
movements are directed by a polarized gradient of cortical tension.
We found that this gradient relies on local contractile forces at the
cortex, differences in elastic properties between cortex components
and the passive transmission of forces within the yolk cell.
All in all, our work identifies a novel way to physically regulate
concerted cellular movements that might be instrumental for the
mechanical control of many morphogenetic processes.