Integrin-Mediated Adhesion in the Unicellular Holozoan Capsaspora owczarzaki.

In animals, cell-matrix adhesions are essential for cell migration, tissue organization, and differentiation, which have central roles in embryonic development [1-6]. Integrins are the major cell surface adhesion receptors mediating cell-matrix adhesion in animals. They are heterodimeric transmembrane proteins that bind extracellular matrix (ECM) molecules on one side and connect to the actin cytoskeleton on the other [7]. Given the importance of integrin-mediated cell-matrix adhesion in development of multicellular animals, it is of interest to discover when and how this machinery arose during evolution. Comparative genomic analyses have shown that core components of the integrin adhesome pre-date the emergence of animals [8-11]; however, whether it mediates cell adhesion in non-metazoan taxa remains unknown. Here, we investigate cell-substrate adhesion in Capsaspora owczarzaki, the closest unicellular relative of animals with the most complete integrin adhesome [11, 12]. Previous work described that the life cycle of C. owczarzaki (hereafter, Capsaspora) includes three distinct life stages: adherent; cystic; and aggregative [13]. Using an adhesion assay, we show that, during the adherent life stage, C. owczarzaki adheres to surfaces using actin-dependent filopodia. We show that integrin β2 and its associated protein vinculin localize as distinct patches in the filopodia. We also demonstrate that substrate adhesion and integrin localization are enhanced by mammalian fibronectin. Finally, using a specific antibody for integrin β2, we inhibited cell adhesion to a fibronectin-coated surface. Our results suggest that adhesion to the substrate in C. owczarzaki is mediated by integrins. We thus propose that integrin-mediated adhesion pre-dates the emergence of animals

Comparative epigenomics in distantly related teleost species identifies conserved cis-regulatory nodes active during the vertebrate phylotypic period

The complex relationship between ontogeny and phylogeny has been the subject of attention and controversy since von Baer’s formulations in the 19th century. The classic concept that embryogenesis progresses from clade general features to species-specific characters has often been revisited. It has become accepted that embryos from a clade show maximum morphological similarity at the so-called phylotypic period (i.e., during mid-embryogenesis). According to the hourglass model, body plan conservation would depend on constrained molecular mechanisms operating at this period. More recently, comparative transcriptomic analyses have provided conclusive evidence that such molecular constraints exist. Examining cis-regulatory architecture during the phylotypic period is essential to understand the evolutionary source of body plan stability. Here we compare transcriptomes and key epigenetic marks (H3K4me3 and H3K27ac) from medaka (Oryzias latipes) and zebrafish (Danio rerio), two distantly related teleosts separated by an evolutionary distance of 115-200 Myr. We show that comparison of transcriptome profiles correlates with anatomical similarities and heterochronies observed at the phylotypic stage. Through comparative epigenomics, we uncover a pool of conserved regulatory regions (approximate to 700), which are active during the vertebrate phylotypic period in both species. Moreover, we show that their neighboring genes encode mainly transcription factors with fundamental roles in tissue specification. We postulate that these regulatory regions, active in both teleost genomes, represent key constrained nodes of the gene networks that sustain the vertebrate body plan

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Capsaspora Owczarzaki as a unicellular model to study co-option of the ancestral integrin adhesome

Trabajo presentado en el Moscow Forum PROTIST 2016, celebrado en Moscú del 6 al 10 de junio de 2016.Adhesion systems and signaling networks are both essential in multicellular organisms. Some elements of the adhesion and signaling pathways of metazoans, such as proteins from the integrin adhesome are conserved in their closest unicellular relatives. This means these proteins already existed in the unicellular ancestor of metazoans and that they were co-opted for a multicellular lifestyle. To understand how the integrin adhesome was co-opted at the onset of Metazoa, we aim to unravel its function in a close unicellular relative of animals, the filasterean Capsaspora owczarzaki. This protist is the closest unicellular relative to metazoans that contains in its genome the basic core of proteins that constitutes the integrin adhesome. The expression of these proteins is upregulated during the aggregative stage in culture conditions. In order to understand its role, we are developing some molecular and genetic tools, such as immunostaining, transfection, and CRISPR/cas9. We will discuss preliminary data on the localization of several cytoskeletal and adhesion proteins of the integrin adhesome in C. owczarzaki, obtained by overexpression and by immunostaining with antibodies raised against our proteins of interest. We will also discuss the development of CRISPR system in this organism with the aim to develop a complete model system to analyze the origin of animals.N

Integrin-Mediated Adhesion in the Unicellular Holozoan Capsaspora owczarzaki

In animals, cell-matrix adhesions are essential for cell migration, tissue organization, and differentiation, which have central roles in embryonic development [1-6]. Integrins are the major cell surface adhesion receptors mediating cell-matrix adhesion in animals. They are heterodimeric transmembrane proteins that bind extracellular matrix (ECM) molecules on one side and connect to the actin cytoskeleton on the other [7]. Given the importance of integrin-mediated cell-matrix adhesion in development of multicellular animals, it is of interest to discover when and how this machinery arose during evolution. Comparative genomic analyses have shown that core components of the integrin adhesome pre-date the emergence of animals [8-11]; however, whether it mediates cell adhesion in non-metazoan taxa remains unknown. Here, we investigate cell-substrate adhesion in Capsaspora owczarzaki, the closest unicellular relative of animals with the most complete integrin adhesome [11, 12]. Previous work described that the life cycle of C. owczarzaki (hereafter, Capsaspora) includes three distinct life stages: adherent; cystic; and aggregative [13]. Using an adhesion assay, we show that, during the adherent life stage, C. owczarzaki adheres to surfaces using actin-dependent filopodia. We show that integrin b2 and its associated protein vinculin localize as distinct patches in the filopodia. We also demonstrate that substrate adhesion and integrin localization are enhanced by mammalian fibronectin. Finally, using a specific antibody for integrin b2, we inhibited cell adhesion to a fibronectin-coated surface. Our results suggest that adhesion to the substrate in C. owczarzaki is mediated by integrins. Wethus propose that integrin-mediated adhesion pre-dates the emergence of animals

Evaluación bioecológica y ambiental de áreas arrecifales del Caribe colombiano

IP 2105-09-120-97ARTICULO(S) EN REVISTA: Maps for Colombian reefs / Juan M.Diaz.'-- en: Reef Encounter. -- No. 25 (July;1999); p. 13. -- ISSN 02552787. -- Isla Arena, una formacion coralina saludable en el area de influencia de la;pluma del rio Magdalena, plataforma continental del Caribecolombiano / Jorge H. Pinzon, Adriana M. Perdomo y;Juan M. Diaz. -- En: Revista de investigaciones marinas ycosteras. -- Vol. 27 (1998); p. 21-37. -- ISSN;01229761. -- Patterns of octocoral and black coral distributionin the oceaniz barrier reef-complex of;Providencia Island, Southwstern Caribbean / Juan A. Sanchez, Sven Zea, Juan M. Diaz. -- En: Caribbean journal;of science. -- Vol. 34, no. 3-4 (Dec. 1998); p. 250-264. -'- isSN86452-- Arrecifes coralinos : ñun tesoro;camino a la extincion? / Jaime Garzon Ferreira. -- En: Colombia: cienciay tecnologia. -- Vol. 15, no. 1;(mar. 1997); p. 11-19. -- ISSN 01205595. -- Peces registradosenlos complejos arrecifales de los cayos;Courtdown, Albuquerque y los bancos Serrana y Roncador, Caribeoccidental,Colombia / Luz Stella Mejia ...;[et.al.]. -- En: Boletin ecotropica. -- No. 32 (1998); p.413892.-- ISSN 01223313. -- Gorgonian communities in;two contrasting enviroments on oceanic atolls of the southwestern caribbean / Juan A. Sanchez, Juan M. Diaz,;spread of diseases in Caribbean coral reefs / Thomas J. Goreau... [et.al.]. -- En: Revista de biologia;tropical -- Vol. 46, sup. 5 (1998); p. 157-171. -- ISSN 00347744. -- A newspecies of Antupatharian Coral;(Cnidaria: Anthozoa) from the caribbean coast of Colombia/ Dennis M. Opresko, Juan A. Sanchez. -- En:;Caribbean journal of science. -- Vol. 33, no. 1-2 (1997);p. 7-581. -- ISSN 00086452. -- PONENCIA(S) EN;CONGRESO: Habitat maps as a tool for assessment and managementof oral reef areas in Colombia /Juan Manuel;Diaz. -- En: Reunion Cientifica Bienal de la IMIA (1 : 1999 nov.9-11 : Panama) -- Mapping reefs and;associated habitats in the SW caribbean / Juan Manuel Diaz. --En: ReunionCientifica Bienal de la IMIA (1 :;1999 nov. 9-11 : Panama) -- Evaluacion de las principalescondiciones de deterioro en algunas formaciones;coralinas de la plataforma continental del Caribe colombiano /Lina M. Barrios Suarez, Jaime Garzon Ferreira,;Sven Zea. -- En: Reunion Asociacion de Laboratorios Marinos delCaribe (ALMC) (29 : 1999 jul. 18-24 : Cumana,;Venezuela) -- Geomorfologia y distribucion de las formacionesarrecifalesde Bajo Tortugas y Bajo Salmedina,;plataforma continental del Caribe Colombiano / Fernando J.ParraVelandia,Juan M. Diaz, Gloria H. Ospina. --;En: Reunion Asociacion de Laboratorios Marinos del Caribe(ALMC)(29 : 1999 jul. 18-24 : Cumana, Venezuela) --;Zonacion y estructura de los fondos coralinos del archipielagode san Bernardo, Caribe colombiano / Mateo;Lopez Victoria, Juan M. Diaz. -- En: Reunion Asociacion deLaboratorios Marinos del Caribe (ALMC) (29 : 1999;jul. 18-24 : Cumana, Venezuela) -- Caracterizacion de lasareascoralinasdel Caribe colombiano : rasgos;morfologicos y ecologicos / Juan Manuel Diaz. -- En: Reunion Asociacion deLaboratorios Marinos del Caribe;(ALMC) (29 : 1999 jul. 18-24 : Cumana, Venezuela) -- Coralhealth assessment in four southwestern caribbean;atolls / J. Garzon Ferreira, S. Zea, J.M. Diaz. -- En: Atlanticand Gulf Assessment (AGRA) workshop (1998 Jun.;2-6 : Miami);Sven Zea. -- En: Bulletin of marine science. -- Vol. 61, no. 2(1997); p.453-465. -- ISSN 00074977. -- Rapi