Land Surface Temperature continuous time series from SSM/I passive microwave radiometers, over northern latitudes (Latitudes > 45°N), during summer snow free period (2000-2011), with links to NetCDF files

Remote sensing instruments are key players to map land surface temperature (LST) at large temporal and spatial scales. In this paper, we present how we combine passive microwave and thermal infrared data to estimate LST during summer snow-free periods over northern high latitudes. The methodology is based on the SSM/I-SSMIS 37 GHz measurements at both vertical and horizontal polarizations on a 25 km × 25 km grid size. LST is retrieved from brightness temperatures introducing an empirical linear relationship between emissivities at both polarizations as described in Royer and Poirier (2010). This relationship is calibrated at pixel scale, using cloud-free independent LST data from MODIS instruments. The SSM/I-SSMIS and MODIS data are synchronized by fitting a diurnal cycle model built on skin temperature reanalysis provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). The resulting temperature dataset is provided at 25 km scale and at an hourly time step during the ten-year analysis period (2000-2011). This new product was locally evaluated at five experimental sites of the EU-PAGE21 project against air temperature measurements and meteorological model reanalysis, and compared to the MODIS LST product at both local and circumpolar scale. The results giving a mean RMSE of the order of 2.2 K demonstrate the usefulness of the microwave product, which is unaffected by clouds as opposed to thermal infrared products and offers a better resolution compared to model reanalysis.

Biostimulation methods associated with early weaning and reproductive rhythms in primiparous rabbit does

El objetivo general de esta Tesis Doctoral ha sido tratar de mejorar los parámetros reproductivos de las conejas primíparas lactantes, empleando dos métodos de manejo (destete temprano y extensificación del ritmo reproductivo), que están directamente relacionados con su balance energético. Para ello, se diseñaron 2 experimentos en este tipo de hembras. En el primero, se estudió el efecto del destete a 25 días post-parto (dpp) sobre la actividad ovárica y el metabolismo energético de las conejas una semana más tarde (32 dpp). Un total de 34 primíparas lactantes con 8 gazapos fueron distribuidas en tres grupos: 10 conejas se sacrificaron a los 25 dpp (grupo L25), 13 fueron destetadas a los 25 dpp y sacrificadas a los 32 dpp (grupo NL32), y 11 conejas no se destetaron y fueron sacrificadas a los 32 dpp (grupo L32). No se observaron diferencias significativas entre grupos en el peso corporal, el peso del ovario, ni en las concentraciones séricas de ácidos grasos no esterificados y de proteínas totales. A pesar de que el grupo NL32 presentó un bajo consumo de alimento (122 ± 23,5 g / día, p <0,001), su contenido corporal estimado de lípidos (16,9 ± 1,09%, P <0,008), proteínas (19,7 ± 0,07%, P <0,0001), y energía (1147 ± 42,7 MJ / kg, p <0,006) fueron más elevados y las concentraciones séricas de glucosa (158 ± 24,5 mg/dl, p <0,04) más bajas que en los grupos L25 (11,9 ± 1,3%, 18,5 ± 0,08%, 942 ± 51,3 MJ/kg y 212 ± 27,9 mg/dl) y L32 (13,4 ± 1,03%, 18,5 ± 0,1%, 993 ± 40,4 MJ/kg y 259 ± 29,5 mg/dl), respectivamente. En el grupo L25 se observó un menor número medio de folículos ≥ 1 mm en la superficie ovárica en comparación con los grupos NL32 y L32 (12,7 ± 1,5 vs. 18,0 ± 1,45 y 17,6 ± 1,67, p <0,05). La población folicular ovárica en las secciones histológicas y la inmunolocalización de los receptores de prolactina fueron similares en todos los grupos. En el grupo L25, tanto la maduración nuclear de oocitos, medida en términos de tasas alcanzadas de Metafase II (67,0 vs. 79,7 y 78,3%, P <0.05) y la maduración citoplasmática, medida por el porcentaje de gránulos corticales (GC) total o parcialmente migrados en los oocitos, fueron significativamente menores que en los grupos NL32 y L32 (16,0 vs 38,3 y 60,0%, P <0.05). En conclusión, a pesar de que el destete precoz a 25 dpp pareció mejorar las reservas de energía de las conejas primíparas, este hecho no se reflejó claramente a nivel ovárico a los 32 dpp y fue similar independientemente del destete, por lo que éste último podría llevarse a cabo más tarde. En el segundo experimento, se compararon dos ritmos reproductivos. Se utilizaron un total de 48 conejas primíparas lactantes con 8 gazapos que se asignaron al azar en dos grupos experimentales: a) lactantes sacrificadas a comienzos del post-parto (11 dpp) de acuerdo a un ritmo semi-intensivo (n = 24), y b) lactantes sacrificadas al final del período post-parto (25 dpp) de acuerdo con un ritmo más extensivo (n = 24). En ellas, se estudió el peso vivo, la composición corporal estimada, parámetros metabólicos y endocrinos (estradiol y progesterona) y características ováricas como la población folicular y la tasa de atresia, así como la maduración nuclear y citoplásmica de los oocitos. En este estudio, el peso vivo, el contenido de energía corporal, los depósitos grasos y los ácidos grasos no esterificados disminuyeron a lo largo del post-parto con respecto al momento del parto (P <0,05). Las concentraciones séricas de proteínas y glucosa aumentaron en el mismo periodo post-parto (P <0,05). Se observaron similares niveles de estradiol y progesterona en ambos ritmos, así como una población folicular, tasas de maduración nuclear (tasa de oocitos en metafase II) y citoplasmática (porcentaje de oocitos con gránulos corticales migrados), similares en ambos momentos del post-parto. Sin embargo, el número de folículos preovulatorios en la superficie ovárica fue menor (P <0,05) y la tasa de atresia tendió a ser mayor con un porcentaje también menor de folículos sanos (P <0,1) en los ovarios de las hembras sometidas al ritmo extensivo. En conclusión, al final del post-parto (25 días), las conejas primíparas sin destetar muestran un deterioro de sus reservas corporales, de sus parámetros metabólicos séricos y de la calidad de sus oocitos; incluso se ha observado una ligera influencia negativa en el desarrollo de sus folículos ováricos. Por esta razón, se considera que en las conejas primíparas lactantes el manejo reproductivo extensivo (25 dpp) no presenta ninguna ventaja en comparación con el semi-intensivo (11 dpp). A la vista de los resultados de estos dos experimentos, podemos decir que ni el destete temprano, ni la extensificación del ritmo reproductivo han conseguido una mejora en los parámetros reproductivos de una hembra primípara. Por ello, son necesarios más estudios sobre el estado metabólico de la coneja primípara lactante para conseguir métodos o estrategias que lo mejoren y tengan consecuencias directas sobre la actividad reproductiva y sobre su éxito productivo. The general aim of this Thesis was to study two management methods (early weaning and extensive reproductive rhythm) linked to the energy balance of the primiparous rabbit does to improve their reproductive performance. In this sense, 2 experiments were conducted using this kind of females. In the first experiment, the effect of weaning at 25 days post-partum (dpp) on ovarian activity and energetic metabolism one week later (32 dpp) was studied. A total of 34 primiparous lactating rabbit does were used and distributed among three groups: 10 does euthanized at 25 dpp (group L25), 13 does weaned at 25 dpp and euthanized at 32 dpp (group NL32), and 11 non weaned does euthanized at 32 dpp (group L32). No significant differences were observed in live body weight, ovary weight, serum non esterified fatty acids (NEFA) and total protein concentration among groups. Although NL32 does had a low feed intake (122±23.5 g/Day; P < 0.001), their estimated lipids (16.9±1.09%, P < 0.008), protein (19.7±0.07%, P < 0.0001), and energy (1147±42.7 MJ/kg, P < 0.006) body contents were higher and their serum glucose concentrations (158±24.5 mg/dl, P < 0.04) were lower compared to L25 does (11.9±1.3%, 18.5±0.08%, 942±51.3 MJ/kg and 212±27.9 mg/dl) and L32 does (13.4±1.03%, 18.5±0.1%, 993±40.4 MJ/kg and 259±29.5 mg/dl, respectively). A lower number of follicles ≥1mm was observed compared to NL32 and L32 groups (12.7±1.5 vs. 18.0±1.45 and 17.6 ±1.67; P < 0.05) in the ovarian surface of L25 does. Follicular population in the histological ovarian sections and immunolocalization of prolactin receptor were similar in all groups. In group L25, both nuclear maturation of oocytes in terms of Metaphase II rate (67.0 vs. 79.7 and 78.3%; P < 0.05) and cytoplasmic maturation measured by percentage of cortical granules (CG), totally or partially migrated in oocytes were significantly lower than in groups NL32 and L32 (16.0 vs. 38.3 and 60.0%; P < 0.05). Consequently, a higher rate of oocytes with non-migrated CGs was found in group L25 than in groups NL32 and L32 (76.0 vs. 46.8 and 33.3%; P < 0.05). In conclusion, even though early weaning at 25 dpp seemed to improve body energy stored in primiparous does, this fact was not well reflected on the ovarian status at 32 dpp, which was similar regardless of weaning time. In the second experiment, two reproductive rhythms were compared. A total of 48 primiparous Californian x New Zealand White rabbit does suckling 8 kits were randomly allocated in two experimental groups: a) lactating does euthanized at early post-partum period (11 dpp) according to a semi-intensive rhythm (n = 24), and b) lactating does euthanized on later post-partum period (25 dpp) according to a more extensive rhythm (n = 24). Live weight, estimated body composition, serum metabolic and endocrine parameters (oestradiol and progesterone concentrations) and ovarian features like follicle population and atresia rate, and oocyte maturation were studied. Live weight, body energy content, lipid depots and serum non esterified fatty acids (NEFA) concentrations diminished from parturition time to post-partum period (P < 0.05). In addition, serum protein and glucose concentrations increased along postpartum time (P < 0.05). Similar oestradiol and progesterone levels were shown in rhythms as well as similar follicle population and nuclear and cytoplasmic maturation rates measured as metaphase II and cortical granule migration, respectively in both postpartum times. However, number of preovulatory follicles on the ovarian surface was lower (P < 0.05) and atresia rate tended to be higher with also lower percentage of healthy follicles (P < 0.1) in ovaries of females of extensive group. In conclusion, primiparous non-weaned rabbits does at late post-partum time (25 days), Did no show any improvement regarding body reserves, serum metabolic parameters and oocyte quality; even a slight negative influence has been observed in the development of their ovarian follicles. Thus this reproductive management does not present any advantage compared to earlier post-partum (11 days) reproductive rhythm. In summary, according to the obtained results from these two experiments, we can say that the application of early weaning and the extensive rhythms did not achieve an improvement in the reproductive performance of primiparous does. Thus, it is necessary to conduct more studies about the metabolic status of the primiparous lactating doe to achieve strategies in order to improve it and consequently, to improve the reproductive activity and their productive success.

Bile Acids Induce Glucagon-Like Peptide 2 Secretion with Limited Effects on Intestinal Adaptation in Early Weaned Pigs

Early weaning is a stressful event characterized by a transient period of intestinal atrophy that may be mediated by reduced secretion of glucagon-like peptide (GLP) 2. We tested whether enterally fed bile acids or plant sterols could increase nutrient-dependent GLP-2 secretion and improve intestinal adaptation in weanling pigs. During the first 6 d after weaning, piglets were intragastrically infused once daily with either deionized water -control-, chenodeoxycholic acid -CDC; 60mg/kg body weight-, or b-sitoesterol -BSE; 100 mg/kg body weight-. Infusing CDC increased plasma GLP-2 -P menor que 0.05- but did not affect plasma GLP-1 and feed intake. The intestinal expression of Glp2r -glucagon-like peptide 2 receptor-, Asbt -sodium-dependent bile acid transporter-, Fxr -farnesoid X receptor-, and Tgr5 -guanosine protein?coupled bile acid receptor- genes were not affected by CDC treatment. The intragastric administration of CDC did not alter the weight and length of the intestine, yet increased the activation of caspase-3 in ileal villi -P menor que 0.02- and the expression of Il6 -interleukin 6; P menor que 0.002- in the jejunum. In contrast, infusing BSE did not affect any of the variables that were measured. Our results show that the enteral administration of the bile acid CDC potentiates the nutrient-induced secretion of endogenous GLP-2 in early-weaned pigs. Bile acid?enhanced release of GLP-2, however, did not result in improved intestinal growth, morphology, or inflammation during the postweaning degenerative phase.

Flujo laminar: el cementerio de Igualada y los procesos elásticos en la arquitectura de Enric Miralles y Carme Pinós

La tesis Flujo Laminar, El cementerio de Igualada y los procesos elásticos en la arquitectura de Enric Miralles y Carme Pinós analiza la metodología que utilizan y desarrollan los arquitectos Miralles y Pinós en el proyecto del cementerio de Igualada. Enric Miralles y Carme Pinós comienzan a trabajar juntos en 1983, separándose siete años después. La producción arquitectónica que generan durante este periodo ha sido valorada y considerada por la crítica como una de las de mayor calidad en el último cuarto del siglo XX. Respecto a esta etapa de colaboración existen artículos dispersos que analizan de manera aislada algunos aspectos de sus proyectos. Sin embargo, no se han realizado estudios que analicen su metodología proyectual, sus herramientas, sus estrategias y sus diferentes conexiones y referencias. Tampoco se han analizado hasta el momento, cómo son sus procesos proyectuales, sus tiempos y sus objetivos. En este sentido, el proyecto del cementerio de Igualada será clave en la trayectoria del equipo. El tiempo extenso empleado en el proceso y la singularidad de la obra, además de otros factores del propio imaginario de Miralles y Pinós, marcarán a este proyecto como un punto de inflexión en su trabajo. La investigación plantea, en primer lugar, la descripción del contexto en el cual se comienzan a desarrollar los proyectos iniciales de Miralles y Pinós, además de los antecedentes que generarán la propuesta para el cementerio de Igualada. Seguidamente, se describen y analizan los apoyos y las referencias que los arquitectos utilizan en este proyecto, tanto las vinculadas a la cultura local como las atrapadas desde el imaginario universal. Por otro lado, el bloque central de la investigación aporta doce herramientas que construyen la metodología proyectual de Miralles y Pinós. Esta contribución se ha realizado desde el análisis y el cruce de los documentos originales del proyecto de Igualada y los escritos existentes de los arquitectos. Las herramientas aportadas son: deslizar, desplazar, repetir, enterrar, constreñir, oscilar, estirar, desenredar, desviar, rehacer, hendir y fluir. Todas ellas se describen, analizan e interpretan desde setenta y dos documentos esenciales extraídos del proceso de Igualada. Un último capítulo de conclusiones, define lo que se presenta en la investigación como una metodología propia de Enric Miralles y Carme Pinós, denominada procesos elásticos, en el que se describen sus cualidades y sus tiempos, a la vez que se presenta también una táctica empleada en el proyecto de Igualada denominada flujo laminar. ABSTRACT The thesis Laminar Flow, the Igualada cemetery and the elastic processes in the architecture of Enric Miralles and Carme Pinós analyses the methodology that the architects Miralles and Pinós used in the project for the Igualada cemetery park. Enric Miralles and Carme Pinós began to work together in 1983, and went their different ways seven years later. The architectural production they generated during that period has been valued and considered by critics to be among the greatest quality of production in the final quarter of the twentieth century. There is a scattering of articles about this period which give an independent analysis of some features of their products. However, there are no studies which analyse their project design methodology, their tools, their strategies and their different connections and references. Neither has there been analysis to date of the nature of their project design processes, nor of their times and their aims. Within this context, the Igualada cemetery project was key in the path to be trodden by the team. The great length of time used on the process and the singularity of the work, alongside other factors from Miralles and Pinós's personal imaginarium, were to mark this project as a turning point in their work. This research sets out, first of all, to describe the context in which the early projects by Miralles and Pinós began to be developed, as well as the background to the generation of their proposal for the Igualada cemetery. There follows a description and analysis of the resources and of the references that the architects used in this project, both those linked to local culture and those picked from the universal imaginarium. Furthermore, the central block of the research identifies twelve tools which make up Miralles and Pinós's project design methodology. This contribution has been performed on the basis of analysis and comparison of the original Igualada project documents and of writings extant by the architects. The tools identified are: slide, shift, repeat, bury, constrain, oscillate, stretch, untangle, divert, redo, groove and flow. They are all described, analysed and interpreted on the basis of seventy-two essential documents extracted from the Igualada process. A final chapter of conclusions defines what is presented in the research as a methodology which is specific to Enric Miralles and Carme Pinós, denominated elastic processes, describing their qualities and their times, along with the presentation of a tactic used in the Igualada project which is denominated laminar flow.

Terremoto 2010 en Chile y vivienda social: resultados y aprendizajes para recomendación de políticas públicas

El territorio chileno esta propenso, desde antes que se constituyera como nación, al impacto del comportamiento de la naturaleza que le es inherente y que también le produce daños. Está representado en los seísmos, los más dañinos. Todavía, la sociedad chilena no termina de comprender que esos daños, son parte de un desequilibrio de una convivencia armoniosa entre ella y esa naturaleza, puesto que el ser humano que vive y habita sobre ella, también lo es. Así entonces, cada vez que el territorio y su espacio son remecidos por los seísmos, la naturaleza, manifestada en la sociedad, adquiere nuevos aprendizajes para mejorar la respuesta al próximo evento. El terremoto 2010 de 8.8° Richter, fue el segundo de mayor magnitud después del otro que hasta ahora, es el más grande del planeta, y que pudo ser medido. Aquel, fue el terremoto de Valdivia de 9,5° Richter, ocurrido el 22 de mayo de 1960. Las sociedades no son estáticas, cambian, son dinámicas. Esta vez el seísmo del 2010, ocurrió en una sociedad que hace ya 35 años, adoptó un modelo de economía de libre mercado. La pobreza que tenía a 1990, era de aproximadamente, un 40%. La del 2010, de un 14%. Durante la dictadura militar hubo otro seísmo de 7,8° Richter, recién instalándose el modelo aludido. El del 2010, permite sacar conclusiones en el contexto de este modelo económico. Los resultados aparentemente son interesantes en cuanto a que hubo pocas víctimas pero por otra parte, hubo un gran daño económico. La tesis profundiza en el impacto del seísmo en la dimensión del parque habitacional construido y de la vivienda social y en los habitantes más pobres y vulnerables. Es la primera investigación sobre seísmos y vivienda social en Chile. Se asume la hipótesis que ciertas variables por una parte, y una cultura antisísmica por otra, están presentes y han penetrado en los sectores populares durante los últimos 50 años y que ello, podría estar en la base de los resultados obtenidos. Se plantea una suerte de “matrimonio bien avenido” entre el habitante y políticas públicas en vivienda. De ello, se derivan recomendaciones para mejorar los avances en el problema investigado que se contextualizan en referencia al marco teórico elaborado. Sin embargo, y no obstante lo investigado, lo ya avanzado no garantiza buenos resultados en el próximo evento, Por ello, los aprendizajes nutren a otros, nuevos, que acompañarán a la sociedad chilena en su esencia e identidad como nación. ABSTRACT Long before its establishment as an independent nation, the Chilean territory has been prone to the impact of nature, which is an inherent and damaging feature of this land. Such an impact is represented by earthquakes, which are regarded as the most damaging natural disasters. Today, the Chilean society is still unable to understand that these impacts are part of an unbalanced coexistence between individuals and nature since human beings, who live and inhabit this space, are also an element of nature. Therefore, each time this territory is hit by earthquakes, nature —represented by society— learns new lessons in order to provide a better response to future events. The 2010 earthquake, which rated 8.8 on the Richter scale, was the second largest earthquake after the most powerful earthquake ever recorded. Such an event was the Valdivia earthquake of May 22, 1960, which rated 9.5 on the Richter scale. Societies are not static as they are changing and dynamic. The 2010 earthquake took place within a context in which society operated under a free market economy model that had been running for 35 years. As of 1990, 40 per cent of the population lived in poverty; in 2010, such a figure was reduced to 14 per cent. Likewise, a magnitude 7.8 quake struck the country during the military regime period in the early days of the above model. The 2010 earthquake allows us to draw some conclusions within the context of this economic model. Results are interesting since there were few fatalities but significant economic loss. This thesis provides insights into the impact of the 2010 earthquake on the housing stock, social housing and those living in poverty and vulnerability. This is the first research on earthquakes and social housing conducted in Chile. The hypothesis is that certain variables and anti-seismic culture have permeated popular segments of the population over the last 50 years. The latter may be at the basis of the results obtained during this research. Likewise, this study proposes a certain “happy marriage” between the inhabitant and public policies on housing. The above offers some recommendations intended to further explore this issue; these suggestions are contextualized according to the theoretical framework developed in this research. However, current progress on this matter does not ensure positive results in the event of an earthquake. This is why these lessons will serve as models for future events, which are intrinsically tied to local society and Chilean identity.

Feto-placental development in the rabbit is altered by maternal food restriction from early pregnancy

Feto-placental development in the rabbit is altered by maternal food restriction from early pregnancy Maternal under-nutrition can induce Intrauterine Growth Restriction by placental insufficiency. To determine the consequences in the rabbit feto-placental unit, 32 pregnant rabbits were allocated in three feeding groups: ad libitum diet (Group C; n=9); restricted to 50% of their ad libitum intake during the pre-implantational period (Day 0 to Day 7) (Group PR; n=11) or restricted from Day 0 to Day 28 (Group TR; n=12).

Modulation of an early step in the secretory machinery in hippocampal nerve terminals

In hippocampal neurons, neurotransmitter release can be regulated by protein kinase A (PKA) through a direct action on the secretory machinery. To identify the site of PKA modulation, we have taken advantage of the ability of the neurotoxin Botulinum A to cleave the synaptic protein SNAP-25. Cleavage of this protein decreases the Ca2+ responsiveness of the secretory machinery by partially uncoupling Ca2+-sensing from fusion per se. This is expressed as a shift toward higher Ca2+ levels of the Ca2+ to neurotransmitter release relationship and as a perturbation of synaptic delay under conditions where secretion induced by the Ca2+-independent secretagogue ruthenium red is unimpaired. We find that SNAP-25 cleavage also perturbs PKA-dependent modulation of secretion; facilitation of ruthenium red-evoked neurotransmitter release by the adenylyl cyclase activator forskolin is blocked completely after Botulinum toxin A action. Together with our observation that forskolin modifies the Ca2+ to neurotransmitter release relationship, our results suggest that SNAP-25 acts as a functional linker between Ca2+ detection and fusion and that PKA modulates an early step in the secretory machinery related to calcium sensing to facilitate synaptic transmission.

Functional growth hormone (GH) receptors and GH are expressed by preimplantation mouse embryos: A role for GH in early embryogenesis?

The results of this study challenge the widely held view that growth hormone (GH) acts only during the postnatal period. RNA phenotyping shows transcripts for the GH receptor and GH-binding protein in mouse preimplantation embryos of all stages from fertilized eggs (day 1) to blastocysts (day 4). An antibody specific to the cytoplasmic region of the GH receptor revealed receptor protein expression, first in two-cell embryos, the stage of activation of the embryonic genome (day 2), and in all subsequent stages. In cleavage-stage embryos this immunoreactivity was localized mainly to the nucleus, but clear evidence of membrane labeling was apparent in blastocysts. GH receptor immunoreactivity was also observed in cumulus cells associated with unfertilized oocytes but not in the unfertilized oocytes. The blastocyst receptor was demonstrated to be functional, exhibiting the classic bell-shaped dose–response curves for GH stimulation of both 3-O-methyl glucose transport and protein synthesis. Maximal stimulation of 40–50% was seen for both responses at less than 1 ng/ml recombinant GH, suggesting a role for maternal GH. However mRNA transcripts for GH were also detected from the morula stage (day 3) by using reverse transcription–PCR, and GH immunoreactivity was seen in blastocysts. These observations raise the possibility of a paracrine/autocrine GH loop regulating embryonic development in its earliest stages.

Transient cardiac expression of constitutively active Gαq leads to hypertrophy and dilated cardiomyopathy by calcineurin-dependent and independent pathways

Cardiac hypertrophy and dilatation can result from stimulation of signal transduction pathways mediated by heterotrimeric G proteins, especially Gq, whose α subunit activates phospholipase Cβ (PLCβ). We now report that transient, modest expression of a hemagglutinin (HA) epitope-tagged, constitutively active mutant of the Gq α subunit (HAα*q) in hearts of transgenic mice is sufficient to induce cardiac hypertrophy and dilatation that continue to progress after the initiating stimulus becomes undetectable. At 2 weeks, HAα*q protein is expressed at less than 50% of endogenous αq/11, and the transgenic hearts are essentially normal morphologically. Although HAα*q protein declines at 4 weeks and is undetectable by 10 weeks, the animals develop cardiac hypertrophy and dilatation and die between 8 and 30 weeks in heart failure. As the pathology develops, endogenous αq/11 rises (2.9-fold in atria; 1.8-fold in ventricles). At 2 weeks, basal PLC activity is increased 9- to 10-fold in atria but not ventricles. By 10 weeks, it is elevated in both, presumably because of the rise in endogenous αq/11. We conclude that the pathological changes initiated by early, transient HAα*q expression are maintained in part by compensatory changes in signal transduction and other pathways. Cyclosporin A (CsA) prevents hypertrophy caused by activation of calcineurin [Molkentin, J. D., Lu, J.-R., Antos, C. L., Markham, B., Richardson, J., Robbins, J., Grant, S. R. & Olson, E. N. (1998) Cell 93, 215–228]. Because HAα*q acts upstream of calcineurin, we hypothesized that HAα*q might initiate additional pathways leading to hypertrophy and dilatation. Treating HAα*q mice with CsA diminished some, but not all, aspects of the hypertrophic phenotype, suggesting that multiple pathways are involved.

Early Endosomes Are Required for Major Histocompatiblity Complex Class II Transport to Peptide-loading Compartments

Antigen presentation to CD4+ T lymphocytes requires transport of newly synthesized major histocompatibility complex (MHC) class II molecules to the endocytic pathway, where peptide loading occurs. This step is mediated by a signal located in the cytoplasmic tail of the MHC class II-associated Ii chain, which directs the MHC class II-Ii complexes from the trans-Golgi network (TGN) to endosomes. The subcellular machinery responsible for the specific targeting of MHC class II molecules to the endocytic pathway, as well as the first compartments these molecules enter after exit from the TGN, remain unclear. We have designed an original experimental approach to selectively analyze this step of MHC class II transport. Newly synthesized MHC class II molecules were caused to accumulate in the Golgi apparatus and TGN by incubating the cells at 19°C, and early endosomes were functionally inactivated by in vivo cross-linking of transferrin (Tf) receptor–containing endosomes using Tf-HRP complexes and the HRP-insoluble substrate diaminobenzidine. Inactivation of Tf-containing endosomes caused a marked delay in Ii chain degradation, peptide loading, and MHC class II transport to the cell surface. Thus, early endosomes appear to be required for delivery of MHC class II molecules to the endocytic pathway. Under cross-linking conditions, most αβIi complexes accumulated in tubules and vesicles devoid of γ-adaptin and/or mannose-6-phosphate receptor, suggesting an AP1-independent pathway for the delivery of newly synthesized MHC class II molecules from the TGN to endosomes.

A mouse CD8 T cell-mediated acute autoimmune diabetes independent of the perforin and Fas cytotoxic pathways: Possible role of membrane TNF

Double transgenic mice [rat insulin promoter (RIP)-tumor necrosis factor (TNF) and RIP-CD80] whose pancreatic β cells release TNF and bear CD80 all develop an acute early (6 wk) and lethal diabetes mediated by CD8 T cells. The first ultrastructural changes observed in β cells, so far unreported, are focal lesions of endoplasmic reticulum swelling at the points of contact with islet-infiltrating lymphoblasts, followed by cytoplasmic, but not nuclear, apoptosis. Such double transgenic mice were made defective in either the perforin, Fas, or TNF pathways. Remarkably, diabetes was found to be totally independent of perforin and Fas. Mice lacking TNF receptor (TNFR) II had no or late diabetes, but only a minority had severe insulitis. Mice lacking the TNF-lymphotoxin (LTα) locus (whose sole source of TNF are the β cells) all had insulitis comparable to that of nondefective mice, but no diabetes or a retarded and milder form, with lesions suggesting different mechanisms of injury. Because both TNFR II and TNF-LTα mutations have complex effects on the immune system, these data do not formally incriminate membrane TNF as the major T cell mediator of this acute autoimmune diabetes; nevertheless, in the absence of involvement of the perforin or Fas cytotoxic pathways, membrane TNF appears to be the likeliest candidate.

Multiple independent origins of Shigella clones of Escherichia coli and convergent evolution of many of their characteristics

The evolutionary relationships of 46 Shigella strains representing each of the serotypes belonging to the four traditional Shigella species (subgroups), Dysenteriae, Flexneri, Boydii, and Sonnei, were determined by sequencing of eight housekeeping genes in four regions of the chromosome. Analysis revealed a very similar evolutionary pattern for each region. Three clusters of strains were identified, each including strains from different subgroups. Cluster 1 contains the majority of Boydii and Dysenteriae strains (B1–4, B6, B8, B10, B14, and B18; and D3–7, D9, and D11–13) plus Flexneri 6 and 6A. Cluster 2 contains seven Boydii strains (B5, B7, B9, B11, B15, B16, and B17) and Dysenteriae 2. Cluster 3 contains one Boydii strain (B12) and the Flexneri serotypes 1–5 strains. Sonnei and three Dysenteriae strains (D1, D8, and D10) are outside of the three main clusters but, nonetheless, are clearly within Escherichia coli. Boydii 13 was found to be distantly related to E. coli. Shigella strains, like the other pathogenic forms of E. coli, do not have a single evolutionary origin, indicating convergent evolution of Shigella phenotypic properties. We estimate the three main Shigella clusters to have evolved within the last 35,000 to 270,000 years, suggesting that shigellosis was one of the early infectious diseases of humans.