Catálogo de publicaciones - revistas

<jats:p>During differentiation, thousands of genes are repositioned toward or away from the nuclear envelope. These movements correlate with changes in transcription and replication timing. Using synthetic (TALE) transcription factors, we found that transcriptional activation of endogenous genes by a viral trans-activator is sufficient to induce gene repositioning toward the nuclear interior in embryonic stem cells. However, gene relocation was also induced by recruitment of an acidic peptide that decondenses chromatin without affecting transcription, indicating that nuclear reorganization is driven by chromatin remodeling rather than transcription. We identified an epigenetic inheritance of chromatin decondensation that maintained central nuclear positioning through mitosis even after the TALE transcription factor was lost. Our results also demonstrate that transcriptional activation, but not chromatin decondensation, is sufficient to change replication timing.</jats:p>

<jats:p>Serial femtosecond crystallography using ultrashort pulses from x-ray free electron lasers (XFELs) enables studies of the light-triggered dynamics of biomolecules. We used microcrystals of photoactive yellow protein (a bacterial blue light photoreceptor) as a model system and obtained high-resolution, time-resolved difference electron density maps of excellent quality with strong features; these allowed the determination of structures of reaction intermediates to a resolution of 1.6 angstroms. Our results open the way to the study of reversible and nonreversible biological reactions on time scales as short as femtoseconds under conditions that maximize the extent of reaction initiation throughout the crystal.</jats:p>

<jats:p>Certain antibody therapies have demonstrated the potential for directing a patient's own immune system against tumors. Further advances in this area will depend upon a detailed understanding of the tumor microenvironment and characterization of the location and status of immune cells and their interaction with tumor cells. This will require methods that provide phenotyping of immune and cancer cells combined with information about their spatial relationship in tumor regions. Additionally, a deeper understanding of the signaling cascades active in immune recognition of cancers is crucial. During this webinar, we will discuss the bringing together of multiplexed fluorescent immunohistochemistry, advanced microscopy techniques, and bioinformatics, and how these are now enabling new insights into cancer biology and immunology.</jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>

<jats:p>Malnutrition is a complex topic that affects different communities and different populations in a variety of ways. Given its many faces, adequate data to address this serious condition is essential if solutions are to be found. Defining exactly what malnutrition is (or isn't) has also been a challenge. However, there is agreement that malnutrition is an issue of critical importance around the globe. This publication brings together important research articles previously published in Science with original articles, all from top researchers and thought leaders in the field. It is intended to be a call to action for the scientific, academic, governmental, and medical communities to assess and address the economic and clinical burden that malnutrition (in all of its forms) exerts on the global economy and to find a means to provide both short- and long-term solutions for those suffering from malnutrition and its consequences.</jats:p> <jats:p> This booklet brought to you by the <jats:italic>Science</jats:italic> /AAAS Custom Publishing Office. </jats:p>

<jats:p>Malnutrition is a complex topic that affects different communities and different populations in a variety of ways. Given its many faces, adequate data to address this serious condition is essential if solutions are to be found. Defining exactly what malnutrition is (or isn't) has also been a challenge. However, there is agreement that malnutrition is an issue of critical importance around the globe. This publication brings together important research articles previously published in Science with original articles, all from top researchers and thought leaders in the field. It is intended to be a call to action for the scientific, academic, governmental, and medical communities to assess and address the economic and clinical burden that malnutrition (in all of its forms) exerts on the global economy and to find a means to provide both short- and long-term solutions for those suffering from malnutrition and its consequences.</jats:p> <jats:p> This booklet brought to you by the <jats:italic>Science</jats:italic> /AAAS Custom Publishing Office. </jats:p>

<jats:p>On this week's show: When eels attack and a news roundup.</jats:p>

<jats:p>Edentulism, the absence of teeth, has evolved convergently among vertebrates, including birds, turtles, and several lineages of mammals. Instead of teeth, modern birds (Neornithes) use a horny beak (rhamphotheca) and a muscular gizzard to acquire and process food. We performed comparative genomic analyses representing lineages of nearly all extant bird orders and recovered shared, inactivating mutations within genes expressed in both the enamel and dentin of teeth of other vertebrate species, indicating that the common ancestor of modern birds lacked mineralized teeth. We estimate that tooth loss, or at least the loss of enamel caps that provide the outer layer of mineralized teeth, occurred about 116 million years ago.</jats:p>

<jats:p>Recent discoveries of spectacular dinosaur fossils overwhelmingly support the hypothesis that birds are descended from maniraptoran theropod dinosaurs, and furthermore, demonstrate that distinctive bird characteristics such as feathers, flight, endothermic physiology, unique strategies for reproduction and growth, and a novel pulmonary system originated among Mesozoic terrestrial dinosaurs. The transition from ground-living to flight-capable theropod dinosaurs now probably represents one of the best-documented major evolutionary transitions in life history. Recent studies in developmental biology and other disciplines provide additional insights into how bird characteristics originated and evolved. The iconic features of extant birds for the most part evolved in a gradual and stepwise fashion throughout archosaur evolution. However, new data also highlight occasional bursts of morphological novelty at certain stages particularly close to the origin of birds and an unavoidable complex, mosaic evolutionary distribution of major bird characteristics on the theropod tree. Research into bird origins provides a premier example of how paleontological and neontological data can interact to reveal the complexity of major innovations, to answer key evolutionary questions, and to lead to new research directions. A better understanding of bird origins requires multifaceted and integrative approaches, yet fossils necessarily provide the final test of any evolutionary model.</jats:p>