Elasticidad de membrana plasmática de levaduras mediante estudios de retracción de Nanotubo

27 h. figuras; tabls.; ilus. Abstract en español e inglés. Contiene Referencia Bibliográfica.Las membranas biológicas constituyen la estructura celular más común en la materia viva, pudiendo ser consideradas como un ejemplo de alta tecnología natural de microencapsulación. Las membranas se comportan como barreras mecánicas semipermeables, regulando el tránsito y la señalización de los compartimentos celulares con el exterior. A su vez, son extremadamente dinámicas tanto de manera global como a pequeña escala espacial. Las interacciones de los lípidos entre sí y con otras moléculas presentes en las membranas (principalmente proteínas) son determinantes para muchas funciones, como la señalización, los procesos de fusión y fisión o la adhesión celular. La forma física de una estructura membranosa está determinada básicamente por su grado de curvatura intrínseca. De igual manera, esta propiedad evidencia la tendencia que tienen los lípidos a formar fases no lamelares. La disposición de los lípidos en la bicapa está directamente relacionada con su forma intrínseca o geométrica, que también condiciona el modo en que estas moléculas se empaquetan e interaccionan entre sí. En este trabajo de tesina se puso foco en la capacidad que tiene la membrana plasmática de cambiar localmente su curvatura. Para realizar estos estudios, deformamos la membrana plasmática localmente, generando tubos de membrana de diámetro nanométrico mediante el empleo de pinzas ópticas. El trabajo se realizó sobre membranas de levaduras Saccharomyces cerevisiae de la cepa BY4741. Estudios previos han demostrado que cuando una bicapa lipídica es sometida a un cambio local de curvatura presenta un comportamiento elástico, mientras que las membranas celulares de mamíferos son marcadamente viscoelásticas. Por otro lado, no se han reportado estudios de deformaciones locales de curvatura en membranas de organismos de otros reinos, que no contienen colesterol sino otros esteroles u hopanoides. Mediante estos experimentos se pretendió poner a punto la metodología a fin de estudiar cómo es la energética de deformación fuera del plano de membrana plasmática de levaduras S. cerevisiae cepa BY4741, la cual contiene un alto porcentaje del esterol ergosterol, en comparación con el comportamiento ya conocido de membrana plasmática de células de mamífero. En este trabajo se encontró que la relajación de nanotubos de membranas plasmáticas de levaduras S. cerevisiae cepa BY4741 ocurre con tiempos característicos en el intervalo 0,02-0,5 s, y si promediamos todos los valores encontrados, obtenemos un valor promedio de 0,2 s ± 0,1 s. Este valor es similar a lo informado para eritrocitos, así como para células tumorales cerebrales en humanos y células de ovario de hámster chino. Hasta donde sabemos, no hay estudios de este tipo reportados en microorganismos eucariotas.Fil: Bischof, Andrea Alejandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Bischof, Andrea Alejandra. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Biológica; Argentina.Fil: Bischof, Andrea Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentina

Late Quaternary vegetation history of central North Island, New Zealand

23 sites in the central North Island of Otiran and Aranuian age (Last Glaciation and post-glacial) were pollen analysed. Three regions were examined in detail: Taranaki, Taupo-Tongariro and Bay of Plenty. For most of the Otiran period (c. 70 000 BP-14 000 BP) the central North Island was covered with scrub-grassland communities. Forest was scarce and scattered. Within this period two major interstadials are recognized. During an early Otiran interstadial, which reached its maximum at about an estimated 60 000 BP, both podocarp-hardwood forest and Nothofagus forest were abundant. Although perhaps 2°C cooler than present, the climate seems to have been mild and moist during this period. A second interstadial lasted from about 45 000 BP to 25 000 BP. It was a time of diverse vegetation and climates. Although scrub was the dominant vegetation over most of the region, there were substantial areas of podocarp-hardwood forest, Nothofagus forest and also some grassland. In some localities it appears that all these vegetation types co-existed. Forest was most abundant from 32 - 27 000 BP. The climate was considerably cooler than that of today with mean annual temperatures up to 4°C lower. Rainfall was lower than at present, but still adequate for podocarp forest growth in some regions. From after 25 000 BP until 14 000 BP grassland/scrubland associations were almost totally dominant. Some forest survived throughout this period, but mainly in hilly and mountainous regions. The grassland/scrubland associations appear to have been very uniform throughout, and there is no evidence for better developed vegetation in the northern regions. The climate was much cooler than today, perhaps 5°C cooler but, more importantly, appears to have been harsh and variable. Rainfall was much lower than at present, especially in the east. In Taranaki, forest dominated by podocarpus spicatus replaced grassland between 13 000 and 12 000 BP. At about 10 000 BP Dacrydium cupressinum and Ascarina lucida became abundant and remained so until about 5000 BP. After this date Ascarina declined while Knightia excels and Dacrydium colensoi spread. After 3000 BP D. colensoi became scarce and today is no longer found in the region. In Hawkes Bay Podocarpus spicatus/totara forest replaced the previous grass and scrub communities by 10 000 BP, but probably not much earlier. These forests remained dominant with only minor changes until the Polynesian burnings of the last millenium. The early Aranuian (14 000 - 10 000 BP) was drier than present, but rainfall was adequate to support podocarp forest in most places, except the drier east coast districts. Increase in rainfall, rather than the well-attested Aranuian warming, was the main reason for the spread of forest. The period from 10 000 BP to 5000 BP was the mildest and wettest of the last 70 000 years. Since 5000 BP there has been a drift to a cooler, droughtier climate

Influence of Angiopoietin Treatment with Hypoxia and Normoxia on Human Intervertebral Disc Progenitor Cell’s Proliferation, Metabolic Activity, and Phenotype

Increasing evidence implicates intervertebral disc (IVD) degeneration as a major contributor to low back pain. In addition to a series of pathogenic processes, degenerated IVDs become vascularized in contrast to healthy IVDs. In this context, angiopoietin (Ang) plays a crucial role and is involved in cytokine recruitment, and anabolic and catabolic reactions within the extracellular matrix (ECM). Over the last decade, a progenitor cell population has been described in the nucleus pulposus (NP) of the IVD to be positive for the Tie2 marker (also known as Ang-1 receptor). In this study, we investigated the influence of Ang-1 and Ang-2 on human NP cell (Tie2+, Tie2- or mixed) populations isolated from trauma patients during 7 days in normoxia (21% O2) or hypoxia (≤ 5% O2). At the end of the process, the proliferation and metabolic activity of the NP cells were analyzed. Additionally, the relative gene expression of NP-related markers was evaluated. NP cells showed a higher proliferation depending on the Ang treatment. Moreover, the study revealed higher NP cell metabolism when cultured in hypoxia. Additionally, the relative gene expression followed, with an increase linked to the oxygen level and Ang concentration. Our study comparing different NP cell populations may be the start of new approaches for the treatment of IVD degeneration

Cellular Senescence: Defining a Path Forward.

Cellular senescence is a cell state implicated in various physiological processes and a wide spectrum of age-related diseases. Recently, interest in therapeutically targeting senescence to improve healthy aging and age-related disease, otherwise known as senotherapy, has been growing rapidly. Thus, the accurate detection of senescent cells, especially in vivo, is essential. Here, we present a consensus from the International Cell Senescence Association (ICSA), defining and discussing key cellular and molecular features of senescence and offering recommendations on how to use them as biomarkers. We also present a resource tool to facilitate the identification of genes linked with senescence, SeneQuest (available at http://Senequest.net). Lastly, we propose an algorithm to accurately assess and quantify senescence, both in cultured cells and in vivo

Meeting Report: Aging Research and Drug Discovery

Aging is the single largest risk factor for most chronic diseases, and thus possesses large socioeconomic interest to continuously aging societies. Consequently, the field of aging research is expanding alongside a growing focus from the industry and investors in aging research. This year's 8th Annual Aging Research and Drug Discovery ARDD) meeting was organized as a hybrid meeting from August 30th to September 3rd 2021 with more than 130 attendees participating on-site at the Ceremonial Hall at University of Copenhagen, Denmark, and 1800 engaging online. The conference comprised of presentations from 75 speakers focusing on new research in topics including mechanisms of aging and how these can be modulated as well as the use of AI and new standards of practices within aging research. This year, a longevity workshop was included to build stronger connections with the clinical community