Retinal pigmented epithelium does not transdifferentiate in adult goldfish

The neural retina of adult goldfish can regenerate from an intrinsic source of proliferative neuronal progenitor cells, but it is not known whether the retina can regenerate by transdifferentiation of the retinal pigmented epithelium (RPE), a phenomenon demonstrated in adult newts. In this study, we asked whether following surgical removal of the neural retina in adult goldfish the RPE was capable of autonomously transdifferentiating and generating new neural retina. The retina was prelabeled by injecting the fluorescent dye Fluoro-Gold (FG) into the eye prior to surgical removal; this procedure ensured that residual retina was labeled with FG and could therefore be distinguished from unlabeled, regenerated retina. To examine the time course of retinal regeneration, and to identify regenerated retinal neurons, the thymidine analogue bromodeoxyuridine was injected intraocularly, and retinas were examined up to 2 months later. We found that the RPE did not transdifferentiate; instead, retinas regenerated only when pieces of residual neural retina were left intact. Under these circumstances, newly regenerated cells derived from proliferating cells intrinsic to the residual neural retina. When retinas were completely removed, as was evident from a lack of FG labeling, there was no retinal regeneration. © 1995 John Wiley & Sons, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50086/1/480270402_ftp.pd

Évaluation de la validité prédictive de neuf instruments chez les agresseurs sexuels adultes

Un large éventail d’instruments s’offre aux cliniciens pour évaluer le risque que posent les délinquants sexuels. La présente étude vise à comparer la validité prédictive de huit instruments (VRAG, SORAG, RRASOR, Statique-99, Statique-2002, RM2000, MnSOST–R et SVR-20) et un outil de référence (PCL-R) selon quatre types de récidive (nuisance sexuelle, récidive sexuelle, récidive violente non sexuelle et récidive non violente et non sexuelle) et pour trois groupes d’agresseurs sexuels. Les résultats indiquent que ces outils ont une validité prédictive marginale à modeste en ce qui concerne la récidive sexuelle. Cependant, une étude plus détaillée en fonction du type d’agresseurs indique une plus grande efficacité de ces instruments pour la récidive sexuelle chez les agresseurs d’enfants et pour la récidive non sexuelle chez les agresseurs de femmes. Les outils actuariels ne permettent de prédire aucune forme de récidive chez les agresseurs mixtes.This study compares the predictive accuracy of eight commonly used risk assessment instruments (the VRAG, the SORAG, the RRASOR, the Static-99, the Static-2002, the Risk Matrix 2000, the MnSOST–R and the SVR-20) and the PCL–R. Four types of recidivism were used (nuisance, sexual, nonsexual victim-involved and nonsexual victimless) and offenders were divided into three subgroups (rapists, child molesters and mixed offenders). Results indicate that instruments showed marginal to modest predictive accuracy for sexual recidivism. However, when we take account of the subgroups, the predictive accuracy for sexual recidivism was higher with child molesters and for non-sexual recidivism with rapists. Most instruments showed predictions no better than chance for mixed offenders and for predicting non-contact sexual reoffending.En la actualidad, se dispone de una amplia gama de herramientas para evaluar el riesgo de reincidencia de los delincuentes sexuales. El presente estudio compara la validez predictiva de ocho métodos (VRAG, SORAG, RRASOR, Static-99, Static-2002, RM2000, MnSOST-R y SVR-20) y un método de referencia (PCL-R) que evalúa cuatro tipos de reincidencia (reincidencia sexual violenta, reincidencia sexual, reincidencia violenta no sexual y reincidencia no violenta y no sexual) para tres grupos de agresores sexuales. Los resultados indican que estos métodos tienen una validez predictiva que va de marginal a modesta en lo que respecta a la reincidencia sexual. Sin embargo, un estudio más detallado en función del tipo de agresores indica una mayor eficacia de estos métodos para evaluar la probabilidad de reincidencia sexual en el caso de agresores de menores y la reincidencia no sexual de los agresores de mujeres. Los instrumentos estadísticos no permiten predecir ninguna forma de reincidencia en el grupo de los agresores mixtos

Expression of rod and cone visual pigments in goldfish and zebrafish: A rhodopsin-like gene is expressed in cones

The primary purpose of the present study was to determine whether a rhodopsin-like gene, which has been postulated to represent the green cone pigment in several species, is in fact expressed in cone photoreceptors instead of rods. The expression patterns of rod opsin and blue and red cone opsins were also examined in both goldfish and zebrafish retinas using colorimetric in situ hybridization. The results demonstrate that the rhodopsin-like gene is expressed in green cones, as predicted. A subset of small cones that do not hybridize with these cRNA probes are tentatively identified as ultraviolet receptors. The results also demonstrate that opsin message in cones is restricted to the perinuclear region, whereas in rods, it is both perinuclear and adjacent to the ellipsoid.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30780/1/0000433.pd

The Imprint of Galaxy Formation on X-ray Clusters

It is widely believed that structure in the Universe evolves hierarchically, as primordial density fluctuations, amplified by gravity, collapse and merge to form progressively larger systems. The structure and evolution of X-ray clusters, however, seems at odds with this hierarchical scenario for structure formation. Poor clusters and groups, as well as most distant clusters detected to date, are substantially fainter than expected from the tight relations between luminosity, temperature and redshift predicted by these models. Here we show that these discrepancies arise because, near the centre, the entropy of the hot, diffuse intracluster medium (ICM) is higher tha$achievable through gravitational collapse, indicating substantial non-gravitational heating of the ICM. We estimate this excess entropy for the first time, and argue that it represents a relic of the energetic winds through which forming galaxies polluted the ICM with metals. Energetically, this is onl$ possible if the ICM is heated at modest redshift (z \ltsim 2) but prior to cluster collapse, indicating that the formation of galaxies precedes that of clusters and that most clusters have been assembled very recently.Comment: 5 pages, plus 2 postscript figures (one in colour), accepted for publication in Natur

Genomic and proteomic biases inform metabolic engineering strategies for anaerobic fungi.

Anaerobic fungi (Neocallimastigomycota) are emerging non-model hosts for biotechnology due to their wealth of biomass-degrading enzymes, yet tools to engineer these fungi have not yet been established. Here, we show that the anaerobic gut fungi have the most GC depleted genomes among 443 sequenced organisms in the fungal kingdom, which has ramifications for heterologous expression of genes as well as for emerging CRISPR-based genome engineering approaches. Comparative genomic analyses suggest that anaerobic fungi may contain cellular machinery to aid in sexual reproduction, yet a complete mating pathway was not identified. Predicted proteomes of the anaerobic fungi also contain an unusually large fraction of proteins with homopolymeric amino acid runs consisting of five or more identical consecutive amino acids. In particular, threonine runs are especially enriched in anaerobic fungal carbohydrate active enzymes (CAZymes) and this, together with a high abundance of predicted N-glycosylation motifs, suggests that gut fungal CAZymes are heavily glycosylated, which may impact heterologous production of these biotechnologically useful enzymes. Finally, we present a codon optimization strategy to aid in the development of genetic engineering tools tailored to these early-branching anaerobic fungi

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Low-frequency cortical activity is a neuromodulatory target that tracks recovery after stroke.

Recent work has highlighted the importance of transient low-frequency oscillatory (LFO; <4 Hz) activity in the healthy primary motor cortex during skilled upper-limb tasks. These brief bouts of oscillatory activity may establish the timing or sequencing of motor actions. Here, we show that LFOs track motor recovery post-stroke and can be a physiological target for neuromodulation. In rodents, we found that reach-related LFOs, as measured in both the local field potential and the related spiking activity, were diminished after stroke and that spontaneous recovery was closely correlated with their restoration in the perilesional cortex. Sensorimotor LFOs were also diminished in a human subject with chronic disability after stroke in contrast to two non-stroke subjects who demonstrated robust LFOs. Therapeutic delivery of electrical stimulation time-locked to the expected onset of LFOs was found to significantly improve skilled reaching in stroke animals. Together, our results suggest that restoration or modulation of cortical oscillatory dynamics is important for the recovery of upper-limb function and that they may serve as a novel target for clinical neuromodulation

Transforaminal endoscopic surgery for symptomatic lumbar disc herniations: a systematic review of the literature

The study design includes a systematic literature review. The objective of the study was to evaluate the effectiveness of transforaminal endoscopic surgery and to compare this with open microdiscectomy in patients with symptomatic lumbar disc herniations. Transforaminal endoscopic techniques for patients with symptomatic lumbar disc herniations have become increasingly popular. The literature has not yet been systematically reviewed. A comprehensive systematic literature search of the MEDLINE and EMBASE databases was performed up to May 2008. Two reviewers independently checked all retrieved titles and abstracts and relevant full text articles for inclusion criteria. Included articles were assessed for quality and outcomes were extracted by the two reviewers independently. One randomized controlled trial, 7 non-randomized controlled trials and 31 observational studies were identified. Studies were heterogeneous regarding patient selection, indications, operation techniques, follow-up period and outcome measures and the methodological quality of these studies was poor. The eight trials did not find any statistically significant differences in leg pain reduction between the transforaminal endoscopic surgery group (89%) and the open microdiscectomy group (87%); overall improvement (84 vs. 78%), re-operation rate (6.8 vs. 4.7%) and complication rate (1.5 vs. 1%), respectively. In conclusion, current evidence on the effectiveness of transforaminal endoscopic surgery is poor and does not provide valid information to either support or refute using this type of surgery in patients with symptomatic lumbar disc herniations. High-quality randomized controlled trials with sufficiently large sample sizes are direly needed to evaluate if transforaminal endoscopic surgery is more effective than open microdiscectomy

The Natural History of ‘Oumuamua

International audienceThe discovery of the first interstellar object passing through the Solar System, 1I/2017 U1 (`Oumuamua), provoked intense and continuing interest from the scientific community and the general public. The faintness of `Oumuamua, together with the limited time window within which observations were possible, constrained the information available on its dynamics and physical state. Here we review our knowledge and find that in all cases, the observations are consistent with a purely natural origin for `Oumuamua. We discuss how the observed characteristics of `Oumuamua are explained by our extensive knowledge of natural minor bodies in our Solar System and our current knowledge of the evolution of planetary systems. We highlight several areas requiring further investigation

PyCogent: a toolkit for making sense from sequence

The COmparative GENomic Toolkit, a framework for probabilistic analyses of biological sequences, devising workflows and generating publication quality graphics, has been implemented in Python