Análisis de una iniciativa estudiantil de investigación surgida en Criptogamia, una asignatura optativa de segundo ciclo de Biología = Analysis of a students’ research initiative originating in Cryptogamy, an elective course in the last two years of the Biology degree

Presentamos una experiencia exitosa de aprendizaje que partió de Criptogamia (asignatura optativa de segundo ciclo de Biología), que dio lugar a un proyecto de investigación gestionado por los propios alumnos. La iniciativa se consolidó estableciendo una Asociación de Estudiantes centrada en investigación y divulgación. En poco tiempo, los participantes han presentado comunicaciones científicas, y organizado actividades dirigidas a diversos públicos, dentro y fuera de la comunidad universitaria. Actualmente se plantea una colaboración multidisciplinar con otros organismos de investigación y la extensión de su ámbito de estudio. Abordamos su incidencia en el aprendizaje en varios aspectos: científico (técnicas específicas, rigor, búsqueda de información e interpretación de resultados), comunicativo (estructuración y presentación de la información obtenida, para diversos públicos), y organizativo, incluyendo el trabajo en equipo. Aunque de carácter espontáneo, esta experiencia muestra rasgos evaluables en cuanto a sus posibilidades para otras asignaturas. Analizamos las características y planteamiento de esta optativa, el perfil de sus alumnos, y el contexto universitario que la acoge. Detectamos como factores principales los aspectos participativos de la asignatura, la cohesión del grupo, el carácter voluntario de la implicación, los beneficios percibidos por los estudiantes, y la disponibilidad de recursos humanos (supervisión) y materiales (equipamiento y subvenciones).

FOXC2 controls formation and maturation of lymphatic collecting vessels through cooperation with NFATc1.

The mechanisms of blood vessel maturation into distinct parts of the blood vasculature such as arteries, veins, and capillaries have been the subject of intense investigation over recent years. In contrast, our knowledge of lymphatic vessel maturation is still fragmentary. In this study, we provide a molecular and morphological characterization of the major steps in the maturation of the primary lymphatic capillary plexus into collecting lymphatic vessels during development and show that forkhead transcription factor Foxc2 controls this process. We further identify transcription factor NFATc1 as a novel regulator of lymphatic development and describe a previously unsuspected link between NFATc1 and Foxc2 in the regulation of lymphatic maturation. We also provide a genome-wide map of FOXC2-binding sites in lymphatic endothelial cells, identify a novel consensus FOXC2 sequence, and show that NFATc1 physically interacts with FOXC2-binding enhancers. As damage to collecting vessels is a major cause of lymphatic dysfunction in humans, our results suggest that FOXC2 and NFATc1 are potential targets for therapeutic intervention.

The biology of Aedes (Ochlerotatus) albifasciatus Macquart, 1838 (Diptera: Culicidae) in Central Argentina

Aedes albifasciatus is a flood water mosquito ocurring in the southern countries of South America. It is a competent vector of the Western Equine Encephalitis (WEE) and causes important losses on milk and beef production in central Argentina. Field work was carried out from December 1990 to March 1993, on a monthly basis during the dry season and biweekly during the rainy season. Larvae were collected using the 'dipping' technique and females with CDC traps baited with CO2. Field collected larvae were used to build laboratory cohorts, from which basic population parameters were estimated. Eggs survived up to six months on dry soil, although there was a linear decrease of viability with time. At 23ºC, larval development time was around nine days, and all adults emerged within one week. The estimation of larval development in the laboratory seems to be very near the development on the field, as larvae have been collected on average eight days after a rainfall. Egg to adult survival was 83%, with the highest mortality on fourth larval instar (6%). In the laboratory studies, sex proportion among the adults was 1:1, females lived longer than males (median 13 and five days, respectively), and adult survival pattern showed a constant number of individuals dying per unit time. Field collected females layed an average of 84 eggs per batch, and completing up to five gonotrophic cycles, suggesting an estimated survival of up to 35-50 days.

Periodic accumulation of cdc15 mRNA is not necessary for septation in Schizosaccharomyces pombe.

Analysis of Schizosaccharomyces pombe mutants that are defective in septum formation and cytokinesis has identified the product of the cdc15 gene as a key element in formation of a division septum. S. pombe cells lacking cdc15p function cannot assemble a functional medial ring, and do not make a division septum. cdc15 mRNA accumulates periodically during the cell cycle, peaking after entry into mitosis, and increased expression of the gene in G2-arrested cells can promote F-actin ring formation. Here, we have investigated the effects of mutations that block cell division upon the expression of cdc15 in synchronised cell populations, and analysed the expression of cdc15 when septum formation is induced by ectopic activation of the septation signalling network. We concluded the following: (i) the septation signalling network genes are not required for periodic accumulation of cdc15 mRNA; (ii) induction of septum formation in G2-arrested cells by activation of the septation signalling network does not result in accumulation of cdc15 mRNA, which is therefore not a prerequisite for septum formation; (iii) failure to turn off septum formation at the end of mitosis results in continued expression of cdc15; and (iv) periodic accumulation of cdc15 mRNA is mediated by a 97 bp region 5' to the mRNA start site.

Human biology: cibernética y biología humana en el nuevo discurso expositivo de la década de 1970

En este trabajo se explica cuáles fueron las estrategias utilizadas y los resultados obtenidos en la primera exposición del nuevo esquema museográfico del Museo de Historia Natural de Londres, concebido por Roger Miles, Jefe del Departamento de Servicios Públicos de esa prestigiada institución. Esta iniciativa pretendía atraer a un mayor número de visitantes a partir de exposiciones basadas en modelos y módulos interactivos que relegaban a los objetos de las colecciones a un segundo plano. La exposición se tituló Human Biology y fue inaugurada el 24 de mayo de 1977. El tema de la exposición fue la biología humana, pero como se argumenta en este trabajo, Human Biology sirvió también como medio para legitimar el discurso modernizador de la biología humana, en tanto disciplina más rigurosa por las herramientas y técnicas más precisas que las utilizadas por la antropología física tradicional. Se buscaba también generar una audiencia para reforzar el campo interdisciplinario de la ciencia cognitiva y en particular la inteligencia artificial. El equipo de asesores científicos de la exposición contó entre sus miembros con personalidades que jugaron un papel protagónico en el desarrollo de esas disciplinas, y necesitaban demostrar su validez y utilidad ante los no especialistas y el público en general.

Fifteen years of molecular lymphangiogenesis - an interview with Kari Alitalo by Tatiana Petrova.

Kari Alitalo is one of the leaders in the field of lymphangiogenesis. Research from his laboratory has contributed to the transformation of a largely descriptive field into a dynamic discipline, which now holds promise for the treatment of cancer, inflammation and vascular dysfunction. The interview intends to provide historical insights into these changes and hopefully inspiration to the young generation of vascular biologists.

Synaptobrevin N-terminally bound to syntaxin-SNAP-25 defines the primed vesicle state in regulated exocytosis.

Rapid neurotransmitter release depends on the ability to arrest the SNAP receptor (SNARE)-dependent exocytosis pathway at an intermediate "cocked" state, from which fusion can be triggered by Ca(2+). It is not clear whether this state includes assembly of synaptobrevin (the vesicle membrane SNARE) to the syntaxin-SNAP-25 (target membrane SNAREs) acceptor complex or whether the reaction is arrested upstream of that step. In this study, by a combination of in vitro biophysical measurements and time-resolved exocytosis measurements in adrenal chromaffin cells, we find that mutations of the N-terminal interaction layers of the SNARE bundle inhibit assembly in vitro and vesicle priming in vivo without detectable changes in triggering speed or fusion pore properties. In contrast, mutations in the last C-terminal layer decrease triggering speed and fusion pore duration. Between the two domains, we identify a region exquisitely sensitive to mutation, possibly constituting a switch. Our data are consistent with a model in which the N terminus of the SNARE complex assembles during vesicle priming, followed by Ca(2+)-triggered C-terminal assembly and membrane fusion.

The biology of malarial parasite in the mosquito: a review

The purpose of this review is to summarize the biology of Plasmodium in the mosquito including recent data to contribute to better understanding of the developmental interaction between mosquito and malarial parasite. The entire sporogonic cycle is discussed taking into consideration different parasite/vector interactions and factors affecting parasite development to the mosquito.

Taxonomy and biology of Culex (Culex) maxi Dyar (Diptera: Culicidae) in South America

Culex (Culex) maxi Dyar is described in the adult, pupal and larval stages, and the male genitalia and parts of the fourth-instar larva are illustrated. The larva is described for the first time. The paper includes a summary of available information on the taxonomy, bionomics and distribution of the species. The taxonomy and identification of the species are reviewed in light of current knowledge of the subgenus Culex in the New World.

Winter biology of Culex pipiens quinquefasciatus say, (Diptera: Culicidae) from Córdoba, Argentina

Adult cohorts and immature stages were kept under field conditions during the autumn and winter of three consecutive years. Survival, oviposition and development time from egg to adult were considered. The adult cohorts were studied under three experimental conditions: unfed cohorts, cohorts fed with sugar solution ansd cohorts fed with both sugar solution and blood (chicken). Female longevity showed significant differences among the three treatments. Females of unfed cohorts lived up to three weeks; females fed with sugar solution survived until six weeks, while those fed both with sugar and blood lived at most fourteen weeks; after the blood intake eggs were laid. In the immature stages, the highest relative mortality rates occurred during the egg and larval stages. Total pre-adult mortality varied between 59.09 and 89.71%. The developmental duration from egg to adult was between 43-62 days; there were no differences among results obtained for the three years.

High altitude, a natural research laboratory for the study of cardiovascular physiology and pathophysiology.

High altitude constitutes an exciting natural laboratory for medical research. Although initially, the aim of high-altitude research was to understand the adaption of the organism to hypoxia and find treatments for altitude-related diseases, during the past decade or so, the scope of this research has broadened considerably. Two important observations led the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema represents a unique model that allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Second, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we will review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.

Desenvolupament de problemes virtuals i interactius per a l’aprenentatge de la Microbiologia

La finalitat del projecte ha estat desenvolupar un espai virtual teòric-pràctic per a l’aprenentatge de la Microbiologia. Aquest espai virtual, basat en l'aprenentatge a través de problemes, s’ha anomenat “Microbiologia Interactiva” i proposa a l’alumne les següents àrees temàtiques: Introducció a les tècniques de la Microbiologia; Estructura i funció de la cèl.lula microbiana; Creixement i control microbià; Microbiologia molecular; Fisiologia i metabolisme microbians; Virologia; Ecologia Microbiana; Diversitat microbiana. Per a cada temàtica s’han definit unes competències a assolir a través de la resolució de problemes teòrics o pràctics. En aquest darrer cas, se li proposa a l’alumne que entri en el laboratori virtual per a la resolució dels casos pràctics plantejats. A més, per a la resolució dels problemes, l’alumne disposa d’un seguit de recursos per a cada temàtica. Finalment, també s’inclouen activitats de relació i d’ampliació per tal d’estimular la discussió, l’esperit crìtic, el treball en grup i la recerca bibliogràfica. A més, per tal de facilitar el seu ús, el web disposa també d'un tutorial. El web “Microbiologia Interactiva” es va introduir de forma pilat en l’ensenyament de l'assignatura de Microbiologia de la Llicenciatura de Biologia i de la de Microbiologia I de la llicenciatura de Biotecnologia de la Universitat Autònoma de Barcelona (UAB) durant el curs 2007-08. Al llarg d'aquest curs es va valorar la seva utilitat i acceptació per part dels alumnes mitjançant enquestes. Els bons resultats obtinguts van aconsellar que aquesta eina fora ja utilitzada en totes les assignatures generals de Microbiologia de les llicenciatures de Biologia, Biotecnologia, Bioquímica, Química, Enginyeria Química, Ciències Ambientals i Ciència i Tecnologia dels Aliments de la UAB. Actualment el web s’està també utilitzant amb molt bons resultats a les assignatures de Microbiologia dels nous graus que ofereix la Facultat de Biociències de la UAB. Així doncs, en aquest projecte s’han assolit amb escreix els objectius previstos. Es pot consultar el web desenvolupat a l’adreça http://microbiologia.uab.cat//Microbiologia_Interactiva_Web/.

L'aprenentatge basat en problemes en models híbrids de docència-aprenentatge

La Facultat de Ciències de la Salut i de la Vida ha utilitzat des de 2004 la metodologia d'aprenentatge basat en problemes (en endavant ABP) com a mètode docent en els seus estudis de Biologia. En aquest període hem après algunes de les claus de l'aplicació del mètode en els nostres estudis. En primer lloc, cal disposar d'elements formatius que afavoreixin la formació dels tutors que participin en el projecte. Per assolir aquest objectiu hem dissenyat un portal on els nostres professors poden disposar de materials útils per a la seva activitat, així com de documents que permetin entendre millor el que suposa l'ABP. En segon lloc, el projecte tenia l'objectiu de dissenyar i avaluar activitats que permetessin integrar les pràctiques de laboratori en la lògica de la resolució de problemes pròpia de l'ABP. En aquest sentit vam dissenyar dues activitats en el tercer curs de la llicenciatura que anomenaren aprenentatge basat en el laboratori (ABL). Per aquest motiu es van dissenyar problemes que tinguessin una primera part de resolució a l'aula en grup de tutoria i una segona que obligués els estudiants a realitzar experiments de laboratori dirigits a entendre i resoldre les qüestions plantejades al grup de tutoria. L'ABL-1 fou un projecte de biologia cel·lular i destinat a aprofundir en els mecanismes implicats en els fenòmens de diferenciació dels miòcits. L'ABL-2 era un projecte conjunt dels professors de Fisiologia vegetal, Bioestadística i Microbiologia. En aquest cas es desitjava que els estudiants plantegessin la resolució a un problema que suposava la manipulació genètica de cèl·lules vegetals per fer possible que produïssin una substància específica, l'escopolamina. Finalment els estudiants havien d'escriure un article original com a projecte final de cada ABL. Els resultats dels dos anys d'experimentació han esta altament satisfactoris, d'acord amb les enquestes completades per alumnes i professors.

Adult human adipose tissue contains several types of multipotent cells.

Multipotent mesenchymal stromal cells (MSCs) are a type of adult stem cells that can be easily isolated from various tissues and expanded in vitro. Many reports on their pluripotency and possible clinical applications have raised hopes and interest in MSCs. In an attempt to unify the terminology and the criteria to label a cell as MSC, in 2006 the International Society for Cellular Therapy (ISCT) proposed a standard set of rules to define the identity of these cells. However, MSCs are still extracted from different tissues, by diverse isolation protocols, are cultured and expanded in different media and conditions. All these variables may have profound effects on the selection of cell types and the composition of heterogeneous subpopulations, on the selective expansion of specific cell populations with totally different potentials and ergo, on the long-term fate of the cells upon in vitro culture. Therefore, specific molecular and cellular markers that identify MSCs subsets as well as standardization of expansion protocols for these cells are urgently needed. Here, we briefly discuss new useful markers and recent data supporting the rapidly emerging concept that many different types of progenitor cells are found in close association with blood vessels. This knowledge may promote the necessary technical improvements required to reduce variability and promote higher efficacy and safety when isolating and expanding these cells for therapeutic use. In the light of the discussed data, particularly the identification of new markers, and advances in the understanding of fundamental MSC biology, we also suggest a revision of the 2006 ISCT criteria.

Cytochemical and immunocytochemical characterization of nuclear bodies during hibernation.

Brown adipose tissue and liver of hibernating, arousing and euthermic individuals of the dormouse Muscardinus avellanarius were studies using ultrastructural cytochemistry and immunocytochemistry with the aim to investigate possible fine structural modifications of the cell nucleus during the seasonal cycle. The general morphology of brown adipocyte and hepatocyte nuclei was similar in the three experimental groups. However, three nuclear structural constituents were identified only in hibernating individuals: coiled bodies (CBs) and amorphous bodies (ABs) were observed in hepatocytes and, together with bundles of nucleoplasmic fibrils (NF), were present in brown adipocytes of hibernating dormice. In arousing animals only some structural constituents suggestive of poorly structured CBs were found. The latter showed the same immunocytochemical features as CBs of hibernating individuals, suggesting that they are disappearing CBs. A possible involvement of CBs in storing and/or processing RNA which must be rapidly and abundantly released upon arousal is discussed. ABs similarly to CBs contain RNA and nucleoplasmic ribonucleoproteins (RNPs) and could also be involved in mRNA pathways. NF do not contain nucleic acids or RNPs and seem to be composed of protein-aceous material; their functional role in the nuclear metabolism of hibernating brown adipocytes remains unclear.