bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plants
Authors: Shefferson Richard P. 
Published: June 2009

Summary 1. I present an evolutionary ecology interpretation of vegetative dormancy in mature herbaceous perennials. This kind of vegetative dormancy has been noted for at least 40 years, but has only recently become a topic of study. 2. Vegetative dormancy may be considered in a life‐history context. Both vegetative dormancy and mortality typically decrease with increasing size. Vegetative dormancy’s relationship to reproduction is more complex, because some species increase flowering and fruiting after dormancy while others do the opposite. 3. If vegetative dormancy is adaptive, then it is most likely a bet‐hedging trait. Dormancy‐prone plants are often long‐lived, and in such organisms, bet‐hedging traits should counter the effects of environmental stochasticity on adult survival. This adaptive context may vary by life span, because in shorter‐lived plants, fitness is most sensitive to changes in reproduction rather than survival. 4. Vegetative dormancy could evolve if the costs of sprouting ever outweigh the benefits. The benefits of sprouting include: (i) photosynthesis and (ii) the opportunity to flower and reproduce. The costs include: (i) greater chance of herbivory, (ii) greater need for limiting nutrients, and (iii) greater maintenance costs. The many losses of photosynthesis among plants suggest that these benefits may not always outweigh the costs. 5. Vegetative dormancy may be an evolutionary step towards the loss of photosynthesis. Many non‐photosynthetic plants acquire carbon from their mycorrhizal fungi. Many autotrophic, dormancy‐prone plants also acquire some carbon from their mycorrhizal fungi. Further, non‐photosynthetic plants often become dormant to an even greater extent than autotrophic, dormancy‐prone plants. 6.
Synthesis Vegetative dormancy often occurs in clades with non‐photosynthetic, myco‐heterotrophic plants, with implications for the evolution of traits involved in carbon nutrition. The links between vegetative dormancy, other life‐history traits, mycorrhizas and the loss of photosynthesis should provide exciting directions for further research in plant evolutionary ecology. Particularly needed is an assessment of the physiology of vegetative dormancy, including whether the mycorrhiza is a carbon source in all dormancy‐prone plant species. Equally important is a better understanding of the genetic relationships among photosynthesis, myco‐heterotrophy and dormancy.
Structural characterization of the active form of PerR: insights into the metal‐induced activation of PerR and Fur proteins for DNA binding
Authors: Jacquamet L. , Traoré D. A. K. , Ferrer J.‐L. , Proux O. , Testemale D. , Hazemann J.‐L. , Nazarenko E. , El Ghazouani A. , Caux‐Thang C. , Duarte V. , Latour J.‐M. 
Published: June 2009

SummaryIn Bacillus subtilis, the transcription factor PerR is an iron dependant sensor of H2O2. The sensing mechanism relies on a selective metal catalysed oxidation of two histidine residues of the regulatory site. Here we present the first crystal structure of the active PerR protein in complex with a Mn2+ ion. In addition, X‐ray absorption spectroscopy experiments were performed to characterize the corresponding iron form of the protein. Both studies reveal a penta‐coordinate arrangement of the regulatory site that involves three histidines and two aspartates. One of the histidine ligand belongs to the N‐terminal domain. Binding of this residue to the regulatory metal allows the protein to adopt a caliper‐like conformation suited to DNA binding. Since this histidine is conserved in all PerR and a vast majority of Fur proteins, it is likely that the allosteric switch induced by the regulatory metal is general for this family of metalloregulators.
Regulatory mutations in Sin recombinase support a structure‐based model of the synaptosome
Authors: Rowland Sally‐J. , Boocock Martin R. , McPherson Arlene L. , Mouw Kent W. , Rice Phoebe A. , Stark W. Marshall 
Published: June 2009

SummaryThe resolvase Sin regulates DNA strand exchange by assembling an elaborate interwound synaptosome containing catalytic and regulatory Sin tetramers, and an architectural DNA‐bending protein. The crystal structure of the regulatory tetramer was recently solved, providing new insights into the structural basis for regulation. Here we describe the selection and characterization of two classes of Sin mutations that, respectively, bypass or disrupt the functions of the regulatory tetramer. Activating mutations, which allow the catalytic tetramer to assemble and function independently at site I (the crossover site), were found at ∼20% of residues in the N‐terminal domain. The most strongly activating mutation (Q115R) stabilized a catalytically active synaptic tetramerin vitro. The positions of these mutations suggest that they act by destabilizing the conformation of the ground‐state site I‐bound dimers, or by stabilizing the altered conformation of the active catalytic tetramer. Mutations that block activation by the regulatory tetramer mapped to just two residues, F52 and R54, supporting a functional role for a previously reported crystallographic dimer–dimer interface. We suggest how F52/R54 contacts between regulatory and catalytic subunits might promote assembly of the active catalytic tetramer within the synaptosome.
Studies on the epidemiology and yield losses from rice black‐streaked dwarf disease in a recent epidemic in Zhejiang province, China
Authors: Wang H.‐D. , Chen J.‐P. , Wang A.‐G. , Jiang X.‐H. , Adams M. J. 
Published: June 2009

The spread of rice black‐streaked dwarf disease, which has emerged as a major problem on winter wheat and the two summer rice crops (early indica and late japonica) grown in central and southern Zhejiang province, China, is documented from 1995 to 2007. The late japonica crop suffered the most: up to 64 640 ha were affected with estimated losses of c. 120 000 t grain per year. Peak adult numbers of the small brown planthopper vector, Laodelphax striatellus, coincided with the seedling stages of both rice crops and the proportion of the insect population carrying virus increased during 1998–2005. Seedlings with three to four leaves were the most susceptible, whereas plants inoculated after the end of tillering developed few or no symptoms. Disease levels were strongly correlated with numbers of viruliferous vectors. In sowing‐date experiments with both rice crops, the earliest sowings had the most disease and suffered the greatest yield losses. With the last sowing date (25 days after the first), there were almost no losses. There were yield losses of 0·80% for every 1% increase in disease incidence in early indica rice and rather more (0·92%) in the late japonica crop. There were large differences in susceptibility between cultivars, indicating the possibility, within currently available germplasm, of using more resistant cultivars to help contain the disease. Changes in cropping practice and in recent winter weather conditions have probably contributed to the emergence of the virus as a major pathogen in eastern China.
Genetic variability of Candida albicans isolates in a university hospital in Hungary
Authors: Farkas Zoltán , Kocsubé Sándor , Tóth Mónika , Vágvölgyi Csaba , Kucsera Judit , Varga János , Pfeiffer Ilona 
Published: June 2009

SummaryThe occurrence and genetic variability of Candida albicans isolates in a Hungarian hospital were examined. Among the 103 Candida isolates, 44 (42.7%) proved to be C. albicans species. Comparing with a previous study carried out in 2002, the percentage of infections caused by C. albicans decreased in Hungary in this period with an increasing incidence of non‐albicans species, in accordance with the world‐wide trend. The genetic variability of the isolates was examined using mitochondrial DNA (mtDNA), restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) analysis and electrophoretic karyotyping. The examined C. albicans isolates could be clustered into four groups based on their mtDNA profiles. The electrophoretic karyotypes of the isolates were mostly identical to that of the reference strain 1006, with the exception of mtDNA type II isolates. RAPD analysis could be used to cluster the isolates into different groups, but this clustering was not in complete agreement with their assignment to mtDNA types. Population genetic analyses of the data indicated low amounts of recombination among these C. albicans strains. None of the isolates exhibited decreased susceptibilities to 5‐fluorocytosine.
Retinal neuroprotection by hypoxic preconditioning is independent of hypoxia‐inducible factor‐1α expression in photoreceptors
Authors: Thiersch Markus , Lange Christina , Joly Sandrine , Heynen Severin , Le Yun Zheng , Samardzija Marijana , Grimm Christian 
Published: June 2009

AbstractHypoxic preconditioning stabilizes hypoxia‐inducible factor (HIF) 1α in the retina and protects photoreceptors against light‐induced cell death. HIF‐1α is one of the major transcription factors responding to low oxygen tension and can differentially regulate a large number of target genes. To analyse whether photoreceptor‐specific expression of HIF‐1α is essential to protect photoreceptors by hypoxic preconditioning, we knocked down expression of HIF‐1α specifically in photoreceptor cells, using the cyclization recombinase (Cre)–lox system. The Cre‐mediated knockdown caused a 20‐fold reduced expression of Hif‐1α in the photoreceptor cell layer. In the total retina, RNA expression was reduced by 65%, and hypoxic preconditioning led to only a small increase in HIF‐1α protein levels. Accordingly, HIF‐1 target gene expression after hypoxia was significantly diminished. Retinas of Hif‐1α knockdown animals did not show any pathological alterations, and tolerated hypoxic exposure in a comparable way to wild‐type retinas. Importantly, the strong neuroprotective effect of hypoxic preconditioning against light‐induced photoreceptor degeneration persisted in knockdown mice, suggesting that hypoxia‐mediated survival of light exposure does not depend on an autocrine action of HIF‐1α in photoreceptor cells. Hypoxia‐mediated stabilization of HIF‐2α and phosphorylation of signal transducer and activator of transcription 3 (STAT 3) were not affected in the retinas of Hif‐1α knockdown mice. Thus, these factors are candidates for regulating the resistance of photoreceptors to light damage after hypoxic preconditioning, along with several potentially neuroprotective genes that were similarly induced in hypoxic knockdown and control mice.
Comparison of the structure and composition of bacterial communities from temperate and tropical freshwater ecosystems
Authors: Humbert Jean‐F. , Dorigo Ursula , Cecchi Philippe , Le Berre Brigitte , Debroas Didier , Bouvy Marc 
Published: June 2009

SummaryWe used a partial 16S rRNA sequencing approach to compare the structure and composition of the bacterial communities in three large, deep subalpine lakes in France with those of communities in six shallow tropical reservoirs in Burkina Faso. Despite the very different characteristics of these ecosystems, we found that their bacterial communities share the same composition in regard to the relative proportions of the different phyla, suggesting that freshwater environmental conditions lead to convergence in this composition. In the same way, we found no significant difference in the richness and diversity of the bacterial communities in France and Burkina Faso. We defined core and satellite operational taxonomic units (OTUs) (sequences sharing at least 98% identity) on the basis of their abundance and their geographical distribution. The core OTUs were found either ubiquitously or only in temperate or tropical and subtropical areas, and they contained more than 70% of all the sequences retrieved in this study. In contrast, satellite OTUs were characterized by having a more restricted geographical distribution and by lower abundance. Finally, the bacterial community composition of these freshwater ecosystems in France and Burkina Faso was markedly different, showing that the history of these ecosystems and regional environmental parameters have a greater impact on the relative abundances of the different OTUs in each bacterial community than the local environmental conditions.
Europe, the bull and the Minotaur: the biological legacy of a Neolithic love story
Authors: Brüssow Harald 
Published: June 2009

SummaryThe European cattle was domesticated 10 000 years ago in eastern Turkey, 1000 years later pottery‐associated milk fats identify cattle‐based dairy activity in western Turkey. Subsequently, the Indo‐European language, domesticated animals and plants travel as a Neolithic package along two major routes across Europe. A striking south‐east to north‐west gradient of a mutation in the current European population (lactase persistence into adulthood) documents the expansion of a Neolithic dairy culture into a Mesolithic hunter society. Using oral tradition (myths), archaeological and written historical evidence and biological data, it is asked whether highly transmissible viral diseases like measles and smallpox entered during the Neolithic from domesticated animals into the human population. The bovine origin of paramyxovirus infections is likely; smallpox comes from camels or from rodents via cattle while mycobacteria and Helicobacter infected humans already before the Neolithic. Microbes adapt constantly and quickly to changing ecological situations. The current global environmental changes will lead to another highly dynamic phase of viral transmissions into the human population.
Transcriptome analysis of nitrogen‐efficient rice over‐expressing alanine aminotransferase
Authors: Beatty Perrin H. , Shrawat Ashok K. , Carroll Rebecka T. , Zhu Tong , Good Allen G. 
Published: June 2009

SummaryCrop plants require nitrogen for key macromolecules, such as DNA, proteins and metabolites, yet they are generally inefficient at acquiring nitrogen from the soil. Crop producers compensate for this low nitrogen utilization efficiency by applying nitrogen fertilizers. However, much of this nitrogen is unavailable to the plants as a result of microbial uptake and environmental loss of nitrogen, causing air, water and soil pollution. We engineered rice over‐expressing alanine aminotransferase (AlaAT) under the control of a tissue‐specific promoter that showed a strong nitrogen use efficiency phenotype. In this study, we examined the transcriptome response in roots and shoots to the over‐expression of AlaAT to provide insights into the nitrogen‐use‐efficient phenotype of these plants. Transgenic and control rice plants were grown hydroponically and the root and shoot gene expression profiles were analysed using Affymetrix Rice GeneChip microarrays. Transcriptome analysis revealed that there was little impact on the transgenic transcriptome compared with controls, with 0.11% and 0.07% differentially regulated genes in roots and shoots, respectively. The most up‐regulated transcripts, a glycine‐rich cell wall (GRP) gene and a gene encoding a hypothetical protein (Os8823), were expressed in roots. Another transgenic root‐specific up‐regulated gene was leucine rich repeat (LRR). Genes induced in the transgenic shoots included GRP, LRR, acireductone dioxygenase (OsARD), SNF2 ATP‐translocase and a putative leucine zipper transcription factor. This study provides a genome‐wide view of the response to AlaAT over‐expression, and elucidates some of the genes that may play a role in the nitrogen‐use‐efficient phenotype.
Intuitions about gravity and solidity in great apes: the tubes task
Authors: Cacchione Trix , Call Josep 
Published: June 2009

AbstractWe investigated whether great apes, like human infants, monkeys and dogs, are subject to a strong gravity bias when tested with the tubes task, and – in case of mastery – what the source of competence on the tubes task is. We presented 22 apes with three versions of the tubes task, in which an object is dropped down a tube connected to one of three potential hiding places and the subject is required to locate the object. In two versions, apes were confronted with a causal tube that varied in the amount of perceptual information it provided (i.e. presence or absence of acoustic cues). The third version was a non‐causal adaptation of the task in which a painted line ‘connected’ dropping and hiding places. Results indicate that apes neither have a reliable gravity bias when tested with the tubes, nor understand the causal function of the tube. Even though there is evidence that they can integrate tube‐related causal information to localize the object, they seem to depend mainly on non‐causal inferences when searching for an invisibly displaced object.
NEUROIMAGING IN PSYCHIATRY: EVALUATING THE ETHICAL CONSEQUENCES FOR PATIENT CARE
Authors: BOYCE ALISON C. 
Published: June 2009

ABSTRACTAccording to many researchers, it is inevitable and obvious that psychiatric illnesses are biological in nature, and that this is the rationale behind the numerous neuroimaging studies of individuals diagnosed with mental disorders. Scholars looking at the history of psychiatry have pointed out that in the past, the origins and motivations behind the search for biological causes, correlates, and cures for mental disorders are thoroughly social and historically rooted, particularly when the diagnostic category in question is the subject of controversy within psychiatry. This is obscured by neuroimaging studies that drive researchers to proclaim ‘revolutions’ in psychiatry, namely in the DSM. Providing neuroimaging evidence to support the contention that a condition is ‘real’ is likely to be extremely influential, as has been extensively discussed in the neuroethics literature. This type of evidence will also reinforce the pre‐existing beliefs of those researchers or clinicians who are already expecting a biological description. The uncritical credence given to neuroimaging research is an ethical issue, not in its potential for contributing to misdiagnosis per se but because of the motivations that often drive this research. My claim is that this research should proceed with an awareness of presumptions and motivations underlying the field as a whole, in addition to an explicit focus on the past and potential future consequences of classification and diagnosis on the groups of individuals under study.
OUR BRAINS ARE NOT US
Authors: GLANNON WALTER 
Published: June 2009

ABSTRACTMany neuroscientists have claimed that our minds are just a function of and thus reducible to our brains. I challenge neuroreductionism by arguing that the mind emerges from and is shaped by interaction among the brain, body, and environment. The mind is not located in the brain but is distributed among these three entities. I then explore the implications of the distributed mind for neuroethics.
Maturation of Corporate Governance Research, 1993–2007: An Assessment
Authors: Durisin Boris , Puzone Fulvio 
Published: June 2009

ABSTRACTManuscript Type: ReviewResearch Question/Issue: This study seeks to investigate whether governance research in fact is a discipline or whether it is rather the subject of multi‐disciplinary research. We map the intellectual structure of corporate governance research and its evolution from 1993–2007.Research Findings/Results: Based on the analysis of more than 1,000 publications and 48,000 citations in Corporate Goverance: An International Review (CGIR) and other academic journals, our study identifies the most influential works, the dominant subfields, and their evolution. Our study assesses the maturation of corporate governance research as a discipline; it finds increasing sophistication, depth and rigor, and consistency in its intellectual structure.Theoretical Implications: There is a large body of accumulated corporate governance research in the US, yet there is an empirical gap on cross‐national studies in the literature. Furthermore, hardly any of the top cited works undertake their study in a cross‐national setting. Thus, corporate governance research and CGIR in its quest to contribute to a global theory of corporate governance might benefit if articles have a cross‐national methodological approach and empirical grounding in their research design and if articles explicitly aim at stating the theoretical underpinnings they draw on.Practical Implications: Globalists find in CGIR an outlet addressing economics and finance (e.g., whether and how compensation or dismissal of CEOs is related to board characteristics), management (e.g., whether and how best practice codes adoption is related to board characteristics and performance), and accounting (e.g., whether and how earnings manipulations is related to board characteristics) issues globally.
Women Directors on Corporate Boards: A Review and Research Agenda
Authors: Terjesen Siri , Sealy Ruth , Singh Val 
Published: June 2009

ABSTRACTManuscript Type: ReviewResearch Question/Issue: This review examines how gender diversity on corporate boards influences corporate governance outcomes that in turn impact performance. We describe extant research on theoretical perspectives, characteristics, and impact of women on corporate boards (WOCB) at micro, meso, and macro levels: individual, board, firm, and industry/environment.Research Finding/Results: To the best of our knowledge, this is the first comprehensive review of WOCBs, incorporating and integrating research from over 400 publications in psychology, sociology, leadership, gender, finance, management, law, corporate governance, and entrepreneurship domains. In addition, we organized our findings to provide a new lens enabling the field to be readily examined by level and by theoretical perspective. The review indicates that WOCB research is about improving corporate governance through better use of the whole talent pool's capital, as well as about building more inclusive and fairer business institutions that better reflect their present generation of stakeholders.Theoretical Implications: With only one in 10 papers addressing theoretical development, the predominant perspectives are human and social capital theories and gender schema at the individual level; social identity, token, and social networks theories at board level; resource dependency, institution, and agency theories at the firm level; and institutional, critical, and political theories at the environmental level. We provide a short synopsis of findings at each level, and conclude with an outline of fruitful directions for future research.Practical Implications: There are increasing pressures for WOCBs from diverse stakeholders, such as the European Commission, national governments, politicians, employer lobby groups, shareholders, Fortune and FTSE rankings, best places for women to work lists, as well as expectations from highly qualified women who are likely to leave if they see no women board members. Rationales generally draw on the business case; however, the moral justice case is also used by those who seek a fairer gender balance in all aspects of society. From our review, the “Impact” section charts the effect of WOCB at all four levels of analysis.