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Selected AbstractsErasure of the paternal transcription program during spermiogenesis: The first step in the reprogramming of sperm chromatin for zygotic developmentDEVELOPMENTAL DYNAMICS, Issue 5 2008Junke Zheng Abstract Male germ cells possess a unique epigenetic program and express a male-specific transcription profile. However, when its chromatin is passed onto the zygote, it expresses an transcription/epigenetic program characteristic of the zygote. The mechanism underlying this reprogramming process is not understood at present. In this study, we show that an extensive range of chromatin factors (CFs), including essential transcription factors and regulators, remodeling factors, histone deacetylases, heterochromatin-binding proteins, and topoisomerases, were removed from chromatin during spermiogenesis. This process will erase the paternal epigenetic program to generate a relatively naive chromatin, which is likely to be essential for installation of the zygotic developmental program after fertilization. We have also showed that transcription termination in male germ cells was temporally correlated with CF dissociation. A genome-wide CF dissociation will inevitably disassemble the transcription apparatus and regulatory mechanism and lead to transcription silence. Based on data presented in this and previous studies (Sun et al., Cell Research [2007] 17:117,134), we propose that paternal-zygotic transcription reprogramming begins with a genome-wide CF dissociation to erase the existing transcription program in later stages of spermatogenesis. This will be followed by assembling of the zygotic equivalent after fertilization. The transcription/epigenetic program of the male germ cell is transformed into a zygotic one using an erase-and-rebuild strategy similar to that used in the maternal-zygotic transition. It is also noted that transcription is terminated long after meiosis is completed and before chromatin becomes highly condensed during spermatogenesis. The temporal order of these events suggests that transcription silence does not have to be coupled to meiosis or chromatin condensation. Developmental Dynamics 237:1463-1476, 2008. © 2008 Wiley-Liss, Inc. [source] Purification and characterization of heparan sulfate from human primary osteoblastsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2009Sadasivam Murali Abstract Heparan sulfate (HS) is a linear, highly variable, highly sulfated glycosaminoglycan sugar whose biological activity largely depends on internal sulfated domains that mediate specific binding to an extensive range of proteins. In this study we employed anion exchange chromatography, molecular sieving and enzymatic cleavage on HS fractions purified from three compartments of cultured osteoblasts,soluble conditioned media, cell surface, and extracellular matrix (ECM). We demonstrate that the composition of HS chains purified from the different compartments is structurally non-identical by a number of parameters, and that these differences have significant ramifications for their ligand-binding properties. The HS chains purified of conditioned medium had twice the binding affinity for FGF2 when compared with either cell surface or ECM HS. In contrast, similar binding of BMP2 to the three types of HS was observed. These results suggest that different biological compartments of cultured cells have structurally and functionally distinct HS species that help to modulate the flow of HS-dependent factors between the ECM and the cell surface. J. Cell. Biochem. 108: 1132,1142, 2009. © 2009 Wiley-Liss, Inc. [source] Undertreatment of congestive heart failure in an Australian settingJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 1 2004P. J. Boyles BPharm (Hons) Summary Aim:, Guidelines for the management of patients with chronic heart failure have undergone change in recent years, with , -blockers and spironolactone shown to reduce mortality when added to angiotensin converting enzyme (ACE) inhibitors, diuretics and digoxin. The aim of this study was to examine the therapeutic management of heart failure in patients admitted to Tasmania's three major public hospitals, with an assessment of the appropriateness of the therapy according to contemporary published guidelines. Methods:, An extensive range of clinical and demographic data was retrospectively extracted from the medical records of consecutive adult patients admitted to the medical wards of the hospitals with heart failure, either as a primary diagnosis or as a comorbidity, during a 6-month period in late 1999,early 2001. Results:, The 450 patients (57% females) had a mean age of 77·8 ± 10·2 years, and were being treated with a median of seven drugs on hospital admission. The percentages of patients being treated with the major drugs of interest were: ACE inhibitors (50%), , -blockers (22%), spironolactone (15%), digoxin (24%), loop diuretics (65%) and angiotensin-II receptor antagonists (8%). Almost 10% were taking a non-steroidal anti-inflammatory agent. Less than one-half the patients who were receiving an ACE inhibitor were taking a target dose for heart failure. There were no significant differences in the pattern of drug use between the three hospitals. Underuse of heart failure medications was most pronounced in women and elderly patients. Conclusions:, The data suggest that current guidelines for the treatment of heart failure are still not being reflected in clinical practice. The relatively low use of drugs shown to improve survival in heart failure is of concern and warrants educational intervention. [source] Linkages of plant traits to soil properties and the functioning of temperate grasslandJOURNAL OF ECOLOGY, Issue 5 2010Kate H. Orwin Summary 1.,Global change is likely to alter plant community structure, with consequences for the structure and functioning of the below-ground community and potential feedbacks to climate change. Understanding the mechanisms behind these plant,soil interactions and feedbacks to the Earth-system is therefore crucial. One approach to understanding such mechanisms is to use plant traits as predictors of functioning. 2.,We used a field-based monoculture experiment involving nine grassland species that had been growing on the same base soil for 7 years to test whether leaf, litter and root traits associated with different plant growth strategies can be linked to an extensive range of soil properties relevant to carbon, nitrogen and phosphorus cycling. Soil properties included the biomass and structure of the soil microbial community, soil nutrients, soil microclimate and soil process rates. 3.,Plant species with a high relative growth rate (RGR) were associated with high leaf and litter quality (e.g. low toughness, high nitrogen concentrations), an elevated biomass of bacteria relative to fungi in soil, high rates of soil nitrogen mineralization and concentrations of extractable inorganic nitrogen, and to some extent higher available phosphorus pools. 4.,In contrast to current theory, species with a high RGR and litter quality were associated with soils with a lower rate of soil respiration and slow decomposition rates. This indicates that predicting processes that influence carbon cycling from plant traits may be more complex than predicting processes that influence nitrogen and phosphorus cycling. 5.,Root traits did not show strong relationships to RGR, leaf or litter traits, but were strongly correlated with several soil properties, particularly the biomass of bacteria relative to fungi in soil and measures relating to soil carbon cycling. 6.,Synthesis. Our results indicate that plant species from a single habitat can result in significant divergence in soil properties and functioning when grown in monoculture, and that many of these changes are strongly and predictably linked to variation in plant traits associated with different growth strategies. Traits therefore have the potential to be a powerful tool for understanding the mechanisms behind plant,soil interactions and ecosystem functioning, and for predicting how changes in plant species composition associated with global change will feedback to the Earth-system. [source] Co-evolutionary Dynamics Within and Between Firms: From Evolution to Co-evolutionJOURNAL OF MANAGEMENT STUDIES, Issue 8 2003Henk W. Volberda abstract The extensive selection,adaptation literature spans diverse theoretical perspectives, but is inconclusive on the role of managerial intentionality in organizational adaptation. Indeed this voluminous literature has more to say about selection and sources and causes of structural inertia than about self-renewing organizations that might counteract such inertia. In this introductory essay, we identify four co-evolutionary generative mechanisms (engines) , naïve selection, managed selection, hierarchical renewal and holistic renewal , which illustrate the extensive range of evolutionary paths that can take place in a population of organizations. In particular, the managed selection engine provides the foundations of the underlying principles of co-evolving self-renewing organizations: managing internal rates of change, optimizing self-organization, and balancing concurrent exploration and exploitation. However, it is altogether clear that empirical co-evolution research represents the next frontier for empirically resolving the adaptation selection debate. The essay concludes with a discussion of requirements for co-evolutionary empirical research and introduces the empirical papers in this Special Research Symposium. [source] The dark arts of good people: How popular culture negotiates ,spin' in NBC's The West Wing1JOURNAL OF SOCIOLINGUISTICS, Issue 1 2006Kay Richardson This paper argues that the popular American TV series The West Wing provides, within popular culture, a sympathetic and realistic view of the work of the political ,spin doctor'. This enterprise is sociolinguistically interesting because of the extensive range of metalinguistic and metacommunicative reflection which it involves. The West Wing centres its storytelling within the world of the spin doctor, thus making such characters central to the narrative: further, it constructs them as likeable, virtuous characters who are also clever. Their cleverness is a matter of sociolinguistic performance expressed in dialogue which displays their professional writing craft skills and their spontaneous witty badinage. [source] The evolution of intelligence: adaptive specializations versus general processBIOLOGICAL REVIEWS, Issue 3 2001EUAN M. MAGPHAIL ABSTRACT Darwin argued that between-species differences in intelligence were differences of degree, not of kind. The contemporary ecological approach to animal cognition argues that animals have evolved species-specific and problem-specific processes to solve problems associated with their particular ecological niches: thus different species use different processes, and within a species, different processes are used to tackle problems involving different inputs. This approach contrasts both with Darwin's view and with the general process view, according to which the same central processes of learning and memory are used across an extensive range of problems involving very different inputs. We review evidence relevant to the claim that the learning and memory performance of non-human animals varies according to the nature of the stimuli involved. We first discuss the resource distribution hypothesis, olfactory learning-set formation, and the ,biological constraints' literature, but find no convincing support from these topics for the ecological account of cognition. We then discuss the claim that the performance of birds in spatial tasks of learning and memory is superior in species that depend heavily upon stored food compared to species that either show less dependence upon stored food or do not store food. If it could be shown that storing species enjoy a superiority specifically in spatial (and not non-spatial) tasks, this would argue that spatial tasks are indeed solved using different processes from those used in non-spatial tasks. Our review of this literature does not find a consistent superiority of storing over non-storing birds in spatial tasks, and, in particular, no evidence of enhanced superiority of storing species when the task demands are increased, by, for example, increasing the number of items to be recalled or the duration of the retention period. We discuss also the observation that the hippocampus of storing birds is larger than that of non-storing birds, and find evidence contrary to the view that hippocampal enlargement is associated with enhanced spatial memory; we are, however, unable to suggest a convincing alternative explanation for hippocampal enlargement. The failure to find solid support for the ecological view supports the view that there are no qualitative differences in cognition between animal species in the processes of learning and memory. We also argue that our review supports our contention that speculation about the phylogenetic development and function of behavioural processes does not provide a solid basis for gaining insight into the nature of those processes. We end by confessing to a belief in one major qualitative difference in cognition in animals: we believe that humans alone are capable of acquiring language, and that it is this capacity that divides our intelligence so sharply from non-human intelligence. [source] | ||||||||||