bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroanatomical basis for cholinergic modulation of locomotor networks by sacral relay neurons with ascending lumbar projections
Authors: Finkel Eran , Etlin Alex , Cherniak Meir , Mor Yoav , Lev‐Tov Aharon , Anglister Lili
Published: April 2014

Synaptic excitation by sacrocaudal afferent (SCA) input of sacral relay neurons projecting rostrally through the ventral white matter funiculi (VF neurons) is a potent activator of the hindlimb central pattern generators (CPGs) in rodent spinal cords lacking descending supraspinal control. Using electrophysiological recordings from the sacral and lumbar spinal segments, we show that the motor output of the lumbar segments produced by SCA stimulation is enhanced by exposing the sacral segments of the neonatal rat spinal cord to the acetylcholinesterase inhibitor edrophonium (EDR). Histochemical and immunostaining of the sacral cord reveals expression of acetylcholinesterase activity, ability to synthesize acetylcholine, and/or innervation by cholinergic synaptic inputs in significant proportions of fluorescently back‐labeled sacral VF neurons. Moreover, the majority of the VF neurons express M2 muscarinic receptors, raising the possibility that the elevated acetylcholine levels resulting from inhibition of acetylcholinesterase act on such receptors. Indeed, sacral application of atropine or the M2‐type receptor antagonist methoctramine was found to reverse the effects of EDR. We suggest that variations in the sacral level of acetylcholine modulate the SCA‐induced locomotor rhythm via muscarinic receptor‐dependent mechanisms and that the modified activity of sacral VF neurons in the presence of an acetylcholinesterase inhibitor can be partially ascribed to the cholinergic components associated with them. Thus, pharmacological manipulations of the sacral cholinergic system may be used to modulate the locomotor‐related motor output in the absence of descending supraspinal control. J. Comp. Neurol. 522:3437–3455, 2014. © 2014 Wiley Periodicals, Inc.
Cortical innervation of the hypoglossal nucleus in the non‐human primate (Macaca mulatta)
Authors: Morecraft Robert J. , Stilwell‐Morecraft Kimberly S. , Solon‐Cline Kathryn M. , Ge Jizhi , Darling Warren G.
Published: April 2014

The corticobulbar projection to the hypoglossal nucleus was studied from the frontal, parietal, cingulate, and insular cortices in the rhesus monkey by using high‐resolution anterograde tracers and stereology. The hypoglossal nucleus received bilateral input from the face/head region of the primary (M1), ventrolateral pre‐ (LPMCv), supplementary (M2), rostral cingulate (M3), and caudal cingulate (M4) motor cortices. Additional bilateral corticohypoglossal projections were found from the dorsolateral premotor cortex (LPMCd), ventrolateral proisocortical motor area (ProM), ventrolateral primary somatosensory cortex (S1), rostral insula, and pregenual region of the anterior cingulate gyrus (areas 24/32). Dense terminal projections arose from the ventral region of M1, and moderate projections from LPMCv and rostral part of M2, with considerably fewer hypoglossal projections arising from the other cortical regions. These findings demonstrate that extensive regions of the non‐human primate cerebral cortex innervate the hypoglossal nucleus. The widespread and bilateral nature of this corticobulbar connection suggests recovery of tongue movement after cortical injury that compromises a subset of these areas, may occur from spared corticohypoglossal projection areas located on the lateral, as well as medial surfaces of both hemispheres. Since functional imaging studies have shown that homologous cortical areas are activated in humans during tongue movement tasks, these corticobulbar projections may exist in the human brain. J. Comp. Neurol. 522:3456–3484, 2014. © 2014 Wiley Periodicals, Inc.
Ablation of ErbB4 from excitatory neurons leads to reduced dendritic spine density in mouse prefrontal cortex
Authors: Cooper Margaret A. , Koleske Anthony J.
Published: April 2014

Dendritic spine loss is observed in many psychiatric disorders, including schizophrenia, and likely contributes to the altered sense of reality, disruption of working memory, and attention deficits that characterize these disorders. ErbB4, a member of the EGF family of receptor tyrosine kinases, is genetically associated with schizophrenia, suggesting that alterations in ErbB4 function contribute to the disease pathology. Additionally, ErbB4 functions in synaptic plasticity, leading us to hypothesize that disruption of ErbB4 signaling may affect dendritic spine development. We show that dendritic spine density is reduced in the dorsomedial prefrontal cortex of ErbB4 conditional whole‐brain knockout mice. We find that ErbB4 localizes to dendritic spines of excitatory neurons in cortical neuronal cultures and is present in synaptic plasma membrane preparations. Finally, we demonstrate that selective ablation of ErbB4 from excitatory neurons leads to a decrease in the proportion of mature spines and an overall reduction in dendritic spine density in the prefrontal cortex of weanling (P21) mice that persists at 2 months of age. These results suggest that ErbB4 signaling in excitatory pyramidal cells is critical for the proper formation and maintenance of dendritic spines in excitatory pyramidal cells. J. Comp. Neurol. 522:3351–3362, 2014. © 2014 Wiley Periodicals, Inc.
Optimization of a merit function for the visual perception of color uniformity in spot lights
Authors: Teupner Anne , Bergenek Krister , Wirth Ralph , Miñano Juan Carlos , Benítez Pablo
Published: April 2014

The objective of the present study is the development of an optimized evaluation method which describes color uniformity in the far field of light‐emitting diode (LED) spot lights related to visual perception of color and pattern. The merit function is requested to evaluate measurements and optical simulations of spot light systems. A human factor experiment was performed as a two‐alternative forced choice (2AFC) test. During the experiment, a pairs of spot lights with various spatial color distributions were shown successively to the subject. The subjects had to select the more even spot light of the pair shown.

The perceived rank order of spot lights was calculated afterwards. It was compared with five different mathematical functions describing several aspects of spatial color uniformity based on the CIELAB color space. These are the widely used color difference  ΔE, gradient, difference of color average, circular symmetry description, and linear smoothness. No single basic function fits the perception in a sufficient way because none of the function considers all visual aspects. For a better correlation between the visual perception and the merit function, a linear combination of four basic functions is proposed. The designed merit function for the color uniformity of spot lights USL is more effective for the prediction of the visual perception. A correlation value of 0.91 is reached. It enables a quantitative evaluation of those LED lighting systems and protects against individual subjective judgments. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 287–296, 2015
Calcium influx and postsynaptic proteins coordinate the dendritic filopodium‐spine transition
Authors: Hu Hsiao‐Tang , Hsueh Yi‐Ping
Published: April 2014

Dendritic spines are the major locations of excitatory synapses in the mammalian central nervous system. The transformation from dendritic filopodia to dendritic spines has been recognized as one type of spinogenesis. For instance, syndecan‐2 (SDC2), a synaptic heparan sulfate proteoglycan, is highly concentrated at dendritic spines and required for spinogenesis. It induces dendritic filopodia formation, followed by spine formation. However, the molecular regulation of the filopodium‐spine transition induced by SDC2 is still unclear. In this report, we show that calcium is an important signal downstream of SDC2 in regulation of filopodium‐spine transition but not filopodia formation. SDC2 interacted with the postsynaptic proteins calmodulin‐dependent serine kinase (CASK) and LIN7 and further recruited NMDAR to the tips of filopodia induced by SDC2. Calcium influx via NMDAR promoted spine maturation because addition of EGTA or AP5 to the culture medium effectively prevented morphological change from dendritic filopodia to dendritic spines. Our data also indicated that F‐actin rearrangement regulated by calcium influx is involved in the morphological change, because the knockdown of gelsolin, a calcium‐activated F‐actin severing molecule, impaired the filopodium‐spine transition induced by SDC2. In conclusion, our study demonstrates that postsynaptic proteins coordinate to trigger calcium signalling and cytoskeleton rearrangement and consequently control filopodium‐spine transition. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 1011–1029, 2014
Opposing effects of hypoxia on catecholaminergic locus coeruleus and hypocretin/orexin neurons in chick embryos
Authors: Landry Jeremy P. , Hawkins Connor , Wiebe Sabrina , Balaban Evan , Pompeiano Maria
Published: April 2014

Terrestrial vertebrate embryos face a risk of low oxygen availability (hypoxia) that is especially great during their transition to air‐breathing. To better understand how fetal brains respond to hypoxia, we examined the effects of low oxygen availability on brain activity in late‐stage chick embryos (day 18 out of a 21‐day incubation period). Using cFos protein expression as a marker for neuronal activity, we focused on two specific, immunohistochemically identified cell groups known to play an important role in regulating adult brain states (sleep and waking): the noradrenergic neurons of the Locus Coeruleus (NA‐LC), and the Hypocretin/Orexin (H/O) neurons of the hypothalamus. cFos expression was also examined in the Pallium (the avian analog of the cerebral cortex). In adult mammalian brains, cFos expression changes in a coordinated way in these areas. In chick embryos, oxygen deprivation simultaneously activated NA‐LC while deactivating H/O‐producing neurons; it also increased cFos expression in the Pallium. Activity in one pallial primary sensory area was significantly related to NA‐LC activity. These data reveal that at least some of the same neural systems involved in brain‐state control in adults may play a central role in orchestrating prenatal hypoxic responses, and that these circuits may show different patterns of coordination than seen in adults. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 1030–1037, 2014
Changes in the social environment induce neurogenic plasticity predominantly in niches residing in sensory structures of the zebrafish brain independently of cortisol levels
Authors: Lindsey Benjamin W. , Tropepe Vincent
Published: April 2014

The social environment is known to modulate adult neurogenesis. Studies in mammals and birds have shown a strong correlation between social isolation and decreases in neurogenesis, whereas time spent in an enriched environment has been shown to restore these deficits and enhance neurogenesis. These data suggest that there exists a common adaptive response among neurogenic niches to each extreme of the social environment. We sought to further test this hypothesis in zebrafish, a social species with distinct neurogenic niches within primary sensory structures and telencephalic nuclei of the brain. By examining stages of adult neurogenesis, including the proliferating stem/progenitor population, their surviving cohort, and the resulting newly differentiated neuronal population, we show that niches residing in sensory structures are most sensitive to changes in the social context, and that social isolation or novelty are both capable of decreasing the number of proliferating cells while increasing the number of newborn neurons within a single niche. Contrary to observations in rodents, we demonstrate that social novelty, a form of enrichment, does not consistently rescue deficits in cell proliferation following social isolation, and that cortisol levels do not negatively regulate changes in adult neurogenesis, but are correlated with the social context. We propose that enhancement or suppression of adult neurogenesis in the zebrafish brain under different social contexts depends largely on the type of niche (sensory or telencephalic), experience from the preceding social environment, and occurs independently of changes in cortisol levels. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 1053–1077, 2014
An NAD+ biosynthetic pathway enzyme functions cell non‐autonomously in C. elegans development
Authors: Crook Matt , Mcreynolds Melanie R. , Wang Wenqing , Hanna‐Rose Wendy
Published: April 2014

Background: Disruption of cellular metabolite levels can adversely impact development. Specifically, loss‐of‐function of the C. elegans NAD+ salvage biosynthesis gene PNC‐1 results in an array of developmental phenotypes. Intriguingly, PNC‐1 and its functional equivalent in vertebrates are secreted, but the contributions of the extracellular enzymes are poorly understood. We sought to study the tissue‐specific requirements for PNC‐1 expression and to examine the role of the secreted isoform. Results: A thorough analysis of PNC‐1 expression did not detect expression in tissues that require PNC‐1 function. Limited expression of both the secreted and intracellular PNC‐1 isoforms provided function at a distance from the tissues with phenotypes. We also find that the secreted isoform contributes to in vivo PNC‐1 activity. Furthermore, uv1 cell survival has the most stringent requirements in terms of PNC‐1 expression pattern or level. Conclusions: Using careful promoter analysis and a restricted expression approach, we have shown that both the secreted and the intracellular PNC‐1 isoforms function cell non‐autonomously, and that the PNC‐1a isoform is functionally relevant in vivo. Our work suggests a model where PNC‐1 function is provided cell non‐autonomously by a mix of intra and extracellular activity, most likely requiring NAD+ salvage metabolite transport between tissues. Developmental Dynamics 243:965–976, 2014. © 2014 Wiley Periodicals, Inc.
The drosophila Chmp1 protein determines wing cell fate through regulation of epidermal growth factor receptor signaling
Authors: Valentine Meagan , Hogan Justin , Collier Simon
Published: April 2014

BACKGROUND:Receptor down‐regulation by the multivesicular body (MVB) pathway is critical for many cellular signaling events. MVB generation is mediated by the highly conserved ESCRT (0, I, II, and III) protein complexes. Chmp1 is an ESCRT‐III component and a putative tumor suppressor in humans. However, published data on Chmp1 activity are conflicting and its role during tissue development is not well defined.RESULTS:We investigated the function of DrosophilaChmp1and found that it is an essential gene. In the wing, loss of Chmp1 activity causes a cell fate change from intervein to vein, and interactions between Chmp1 and Drosophila Epidermal Growth Factor Receptor (DER) regulators suggest that Chmp1 negatively regulates DER signaling.Chmp1knockdown also decreases Blistered expression, which is repressed by DER signaling. We find that Chmp1 protein localizes to the late endosome in Drosophila embryos, which is consistent with its effects on DER signaling resulting from its function in the ESCRT‐III complex.CONCLUSIONS:Drosophila Chmp1 negatively regulates DER signaling, likely through its role in MVB formation. Loss of Chmp1 activity in the Drosophila wing induces a cell fate change from intervein to vein that should provide a useful tool for future studies of ESCRT protein activity.Developmental Dynamics 243:977–987, 2014. © 2014 Wiley Periodicals, Inc.
AP‐2α is required after lens vesicle formation to maintain lens integrity
Authors: Kerr Christine L. , Zaveri Mizna A. , Robinson Michael L. , Williams Trevor , West‐Mays Judith A.
Published: April 2014

Background: Transcription factors are critical in regulating lens development. The AP‐2 family of transcription factors functions in differentiation, cell growth and apoptosis, and in lens and eye development. AP‐2α, in particular, is important in early lens development, and when conditionally deleted at the placode stage defective separation of the lens vesicle from the surface ectoderm results. AP‐2α's role during later stages of lens development is unknown. To address this, the MLR10‐Cre transgene was used to delete AP‐2α from the lens epithelium beginning at embryonic day (E) 10.5. Results: The loss of AP‐2α after lens vesicle separation resulted in morphological defects beginning at E18.5. By P4, a small highly vacuolated lens with a multilayered epithelium was evident in the MLR10‐AP‐2α mutants. Epithelial cells appeared elongated and expressed fiber cell specific βB1 and γ‐crystallins. Epithelial cell polarity and lens cell adhesion was disrupted and accompanied by the misexpression of ZO‐1, N‐Cadherin, and β‐catenin. Cell death was observed in the mutant lens epithelium between postnatal day (P) 14 and P30, and correlated with altered arrangements of cells within the epithelium. Conclusions: Our findings demonstrate that AP‐2α continues to be required after lens vesicle separation to maintain a normal lens epithelial cell phenotype and overall lens integrity and to ensure correct fiber cell differentiation. Developmental Dynamics 243:1298–1309, 2014. © 2014 Wiley Periodicals, Inc.
Follow your gut: Relaying information from the site of left–right symmetry breaking in the mouse
Authors: Saijoh Yukio , Viotti Manuel , Hadjantonakis Anna‐Katerina
Published: April 2014

A central unresolved question in the molecular cascade that drives establishment of left–right (LR) asymmetry in vertebrates are the mechanisms deployed to relay information between the midline site of symmetry‐breaking and the tissues which will execute a program of asymmetric morphogenesis. The cells located between these two distant locations must provide the medium for signal relay. Of these, the gut endoderm is an attractive candidate tissue for signal transmission since it comprises the epithelium that lies between the node, where asymmetry originates, and the lateral plate, where asymmetry can first be detected. Here, focusing on the mouse as a model, we review our current understanding and entertain open questions concerning the relay of LR information from its origin. genesis 52:503–514, 2014. © 2014 Wiley Periodicals, Inc.
Fitness dynamics within a poplar hybrid zone: II. Impact of exotic sex on native poplars in an urban jungle
Authors: Roe Amanda D. , MacQuarrie Chris J.K. , Gros‐Louis Marie‐Claude , Simpson J. Dale , Lamarche Josyanne , Beardmore Tannis , Thompson Stacey L. , Tanguay Philippe , Isabel Nathalie
Published: April 2014

Trees bearing novel or exotic gene components are poised to contribute to the bioeconomy for a variety of purposes such as bioenergy production, phytoremediation, and carbon sequestration within the forestry sector, but sustainable release of trees with novel traits in large‐scale plantations requires the quantification of risks posed to native tree populations. Over the last century, exotic hybrid poplars produced through artificial crosses were planted throughout eastern Canada as ornamentals or windbreaks and these exotics provide a proxy by which to examine the fitness of exotic poplar traits within the natural environment to assess risk of exotic gene escape, establishment, and spread into native gene pools. We assessed postzygotic fitness traits of native and exotic poplars within a naturally regenerated stand in eastern Canada (Quebec City, QC). Pure natives (P. balsamifera and P. deltoides spp. deltoides), native hybrids (P. deltoides × P. balsamifera), and exotic hybrids (trees bearing Populus nigra and P. maximowiczii genetic components) were screened for reproductive biomass, yield, seed germination, and fungal disease susceptibility. Exotic hybrids expressed fitness traits intermediate to pure species and were not significantly different from native hybrids. They formed fully viable seed and backcrossed predominantly with P. balsamifera. These data show that exotic hybrids were not unfit and were capable of establishing and competing within the native stand. Future research will seek to examine the impact of exotic gene regions on associated biotic communities to fully quantify the risk exotic poplars pose to native poplar forests.
Spatial genetic structure in Beta vulgaris subsp. maritima and Beta macrocarpa reveals the effect of contrasting mating system, influence of marine currents, and footprints of postglacial recolonization routes
Authors: Leys Marie , Petit Eric J. , El‐Bahloul Yasmina , Liso Camille , Fournet Sylvain , Arnaud Jean‐François
Published: April 2014

Understanding the factors that contribute to population genetic divergence across a species' range is a long‐standing goal in evolutionary biology and ecological genetics. We examined the relative importance of historical and ecological features in shaping the present‐day spatial patterns of genetic structure in two related plant species, Beta vulgaris subsp. maritima and Beta macrocarpa. Using nuclear and mitochondrial markers, we surveyed 93 populations from Brittany (France) to Morocco – the southern limit of their species' range distribution. Whereas B. macrocarpa showed a genotypic structure and a high level of genetic differentiation indicative of selfing, the population genetic structure of B. vulgaris subsp. maritima was consistent with an outcrossing mating system. We further showed (1) a strong geographic clustering in coastal B. vulgaris subsp. maritima populations that highlighted the influence of marine currents in shaping different lineages and (2) a peculiar genetic structure of inland B. vulgaris subsp. maritima populations that could indicate the admixture of distinct evolutionary lineages and recent expansions associated with anthropogenic disturbances. Spatial patterns of nuclear diversity and differentiation also supported a stepwise recolonization of Europe from Atlantic‐Mediterranean refugia after the last glacial period, with leading‐edge expansions. However, cytoplasmic diversity was not impacted by postglacial recolonization: stochastic long‐distance seed dispersal mediated by major oceanic currents may mitigate the common patterns of reduced cytoplasmic diversity observed for edge populations. Overall, the patterns we documented here challenge the general view of reduced genetic diversity at the edge of a species' range distribution and provide clues for understanding how life‐history and major geographic features interact to shape the distribution of genetic diversity.
Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents, Pinus tabuliformis and Pinus yunnanensis
Authors: Xing Fangqian , Mao Jian‐Feng , Meng Jingxiang , Dai Jianfeng , Zhao Wei , Liu Hao , Xing Zhen , Zhang Hua , Wang Xiao‐Ru , Li Yue
Published: April 2014

Genetic analyses indicate that Pinus densata is a natural homoploid hybrid originating from Pinus tabuliformis and Pinus yunnanensis. Needle morphological and anatomical features show relative species stability and can be used to identify coniferous species. Comparative analyses of these needle characteristics and phenotypic differences between the artificial hybrids, P. densata, and parental species can be used to determine the genetic and phenotypic evolutionary consequences of natural hybridization. Twelve artificial hybrid families, the two parental species, and P. densata were seeded in a high‐altitude habitat in Linzhi, Tibet. The needles of artificial hybrids and the three pine species were collected, and 24 needle morphological and anatomical traits were analyzed. Based on these results, variations in 10 needle traits among artificial hybrid families and 22 traits among species and artificial hybrids were predicted and found to be under moderate genetic control. Nineteen needle traits in artificial hybrids were similar to those in P. densata and between the two parental species, P. tabuliformis and P. yunnanensis. The ratio of plants with three needle clusters in artificial hybrids was 22.92%, which was very similar to P. densata. The eight needle traits (needle length, the mean number of stomata in sections 2 mm in length of the convex and flat sides of the needle, mean stomatal density, mesophyll/vascular bundle area ratio, mesophyll/resin canal area ratio, mesophyll/(resin canals and vascular bundles) area ratio, vascular bundle/resin canal area ratio) relative to physiological adaptability were similar to the artificial hybrids and P. densata. The similar needle features between the artificial hybrids and P. densata could be used to verify the homoploid hybrid origin of P. densata and helps to better understand of the hybridization roles in adaptation and speciation in plants.
A hidden Markov model to identify and adjust for selection bias: an example involving mixed migration strategies
Authors: Fieberg John R. , Conn Paul B.
Published: April 2014

An important assumption in observational studies is that sampled individuals are representative of some larger study population. Yet, this assumption is often unrealistic. Notable examples include online public‐opinion polls, publication biases associated with statistically significant results, and in ecology, telemetry studies with significant habitat‐induced probabilities of missed locations. This problem can be overcome by modeling selection probabilities simultaneously with other predictor–response relationships or by weighting observations by inverse selection probabilities. We illustrate the problem and a solution when modeling mixed migration strategies of northern white‐tailed deer (Odocoileus virginianus). Captures occur on winter yards where deer migrate in response to changing environmental conditions. Yet, not all deer migrate in all years, and captures during mild years are more likely to target deer that migrate every year (i.e., obligate migrators). Characterizing deer as conditional or obligate migrators is also challenging unless deer are observed for many years and under a variety of winter conditions. We developed a hidden Markov model where the probability of capture depends on each individual's migration strategy (conditional versus obligate migrator), a partially latent variable that depends on winter severity in the year of capture. In a 15‐year study, involving 168 white‐tailed deer, the estimated probability of migrating for conditional migrators increased nonlinearly with an index of winter severity. We estimated a higher proportion of obligates in the study cohort than in the population, except during a span of 3 years surrounding back‐to‐back severe winters. These results support the hypothesis that selection biases occur as a result of capturing deer on winter yards, with the magnitude of bias depending on the severity of winter weather. Hidden Markov models offer an attractive framework for addressing selection biases due to their ability to incorporate latent variables and model direct and indirect links between state variables and capture probabilities.
Geographic variation in seed traits within and among forty‐two species of Rhododendron (Ericaceae) on the Tibetan plateau: relationships with altitude, habitat, plant height, and phylogeny
Authors: Wang Yongji , Wang Jianjian , Lai Liming , Jiang Lianhe , Zhuang Ping , Zhang Lehua , Zheng Yuanrun , Baskin Jerry M. , Baskin Carol C.
Published: April 2014

Seed mass and morphology are plant life history traits that influence seed dispersal ability, seeding establishment success, and population distribution pattern. Southeastern Tibet is a diversity center for Rhododendron species, which are distributed from a few hundred meters to 5500 m above sea level. We examined intra‐ and interspecific variation in seed mass and morphology in relation to altitude, habitat, plant height, and phylogeny. Seed mass decreased significantly with the increasing altitude and increased significantly with increasing plant height among populations of the same species. Seed mass differed significantly among species and subsections, but not among sections and subgenera. Seed length, width, surface area, and wing length were significantly negative correlated with altitude and significantly positive correlated with plant height. Further, these traits differed significantly among habitats and varied among species and subsection, but not among sections and subgenera. Species at low elevation had larger seeds with larger wings, and seeds became smaller and the wings of seeds tended to be smaller with the increasing altitude. Morphology of the seed varied from flat round to long cylindrical with increasing altitude. We suggest that seed mass and morphology have evolved as a result of both long‐term adaptation and constraints of the taxonomic group over their long evolutionary history.
A multiscale analysis of gene flow for the New England cottontail, an imperiled habitat specialist in a fragmented landscape
Authors: Fenderson Lindsey E. , Kovach Adrienne I. , Litvaitis John A. , O'Brien Kathleen M. , Boland Kelly M. , Jakubas Walter J.
Published: April 2014

Landscape features of anthropogenic or natural origin can influence organisms' dispersal patterns and the connectivity of populations. Understanding these relationships is of broad interest in ecology and evolutionary biology and provides key insights for habitat conservation planning at the landscape scale. This knowledge is germane to restoration efforts for the New England cottontail (Sylvilagus transitionalis), an early successional habitat specialist of conservation concern. We evaluated local population structure and measures of genetic diversity of a geographically isolated population of cottontails in the northeastern United States. We also conducted a multiscale landscape genetic analysis, in which we assessed genetic discontinuities relative to the landscape and developed several resistance models to test hypotheses about landscape features that promote or inhibit cottontail dispersal within and across the local populations. Bayesian clustering identified four genetically distinct populations, with very little migration among them, and additional substructure within one of those populations. These populations had private alleles, low genetic diversity, critically low effective population sizes (3.2–36.7), and evidence of recent genetic bottlenecks. Major highways and a river were found to limit cottontail dispersal and to separate populations. The habitat along roadsides, railroad beds, and utility corridors, on the other hand, was found to facilitate cottontail movement among patches. The relative importance of dispersal barriers and facilitators on gene flow varied among populations in relation to landscape composition, demonstrating the complexity and context dependency of factors influencing gene flow and highlighting the importance of replication and scale in landscape genetic studies. Our findings provide information for the design of restoration landscapes for the New England cottontail and also highlight the dual influence of roads, as both barriers and facilitators of dispersal for an early successional habitat specialist in a fragmented landscape.
The causal pie model: an epidemiological method applied to evolutionary biology and ecology
Authors: Wensink Maarten , Westendorp Rudi G. J. , Baudisch Annette
Published: April 2014

A general concept for thinking about causality facilitates swift comprehension of results, and the vocabulary that belongs to the concept is instrumental in cross‐disciplinary communication. The causal pie model has fulfilled this role in epidemiology and could be of similar value in evolutionary biology and ecology. In the causal pie model, outcomes result from sufficient causes. Each sufficient cause is made up of a “causal pie” of “component causes”. Several different causal pies may exist for the same outcome. If and only if all component causes of a sufficient cause are present, that is, a causal pie is complete, does the outcome occur. The effect of a component cause hence depends on the presence of the other component causes that constitute some causal pie. Because all component causes are equally and fully causative for the outcome, the sum of causes for some outcome exceeds 100%. The causal pie model provides a way of thinking that maps into a number of recurrent themes in evolutionary biology and ecology: It charts when component causes have an effect and are subject to natural selection, and how component causes affect selection on other component causes; which partitions of outcomes with respect to causes are feasible and useful; and how to view the composition of a(n apparently homogeneous) population. The diversity of specific results that is directly understood from the causal pie model is a test for both the validity and the applicability of the model. The causal pie model provides a common language in which results across disciplines can be communicated and serves as a template along which future causal analyses can be made.
Untangling the relationships among regional occupancy, species traits, and niche characteristics in stream invertebrates
Authors: Heino Jani , Grönroos Mira
Published: April 2014

The regional occupancy and local abundance of species are affected by various species traits, but their relative effects are poorly understood. We studied the relationships between species traits and occupancy (i.e., proportion of sites occupied) or abundance (i.e., mean local abundance at occupied sites) of stream invertebrates using small‐grained data (i.e., local stream sites) across a large spatial extent (i.e., three drainage basins). We found a significant, yet rather weak, linear relationship between occupancy and abundance. However, occupancy was strongly related to niche position (NP), but it showed a weaker relationship with niche breadth (NB). Abundance was at best weakly related to these explanatory niche‐based variables. Biological traits, including feeding modes, habit traits, dispersal modes and body size classes, were generally less important in accounting for variation in occupancy and abundance. Our findings showed that the regional occupancy of stream invertebrate species is mostly related to niche characteristics, in particular, NP. However, the effects of NB on occupancy were affected by the measure itself. We conclude that niche characteristics determine the regional occupancy of species at relatively large spatial extents, suggesting that species distributions are determined by environmental variation among sites.
NK cells gain higher IFN‐γ competence during terminal differentiation
Authors: Luetke‐Eversloh Merlin , Cicek Basak B. , Siracusa Francesco , Thom Jenny T. , Hamann Alf , Frischbutter Stefan , Baumgrass Ria , Chang Hyun‐Dong , Thiel Andreas , Dong Jun , Romagnani Chiara
Published: April 2014

NK cells are the main cells of the innate immune system that produce IFN‐γ, and they express this cytokine at early stages of maturation in response to cytokine stimulation. Conversely, acquisition of IFN‐γ‐competence in CD4+ T helper cells requires a differentiation process from naïve toward type 1 (Th1) cells, which is associated with epigenetic remodeling at the IFNG locus. In the present study, we show that the ability of NK cells to produce IFN‐γ in response to activating receptor (actR) engagement is gradually acquired during terminal differentiation and is accompanied by progressively higher NF‐κB activation in response to actR triggering. Moreover, during the differentiation process NK cells gradually display increasing expression of IFNG and TBX21 (encoding T‐bet) transcripts and demethylation at the IFNG promoter. This study provides new insights in the molecular mechanisms underlying NK‐cell ability to express IFN‐γ upon actR engagement. Thus, we propose that in order to efficiently produce IFN‐γ in response to infected or transformed cells, NK cells gain Th1‐like features, such as higher IFN‐γ competence and epigenetic remodeling of the IFNG promoter, during their terminal differentiation.
Transferrin‘ activation: Bonding with transferrin receptors tunes KLRG1 function
Authors: Steinle Alexander
Published: April 2014

The inhibitory C‐type lectin‐like immunoreceptor KLRG1 enables mature NK cells and differentiated T cells to sense cadherin‐expressing cells by ligating “classical” cadherins. Upon engagement of the KLRG1 ectodomain, an inhibitory signal emanates from the cytoplasmic immunoreceptor‐tyrosine‐based inhibition motif (ITIM), dampening functional responses of these lymphocytes. Malignancy‐associated loss of cadherins has been proposed to relieve KLRG1‐mediated inhibition of cytotoxic lymphocytes and thereby to contribute to tumor surveillance by an alternate mode of “missing self‐recognition”. In this issue of the European Journal of Immunology, Schweier et al. [Eur. J. Immunol. 2014. 44: 1851–1856] propose another intriguing mechanism that may relieve KLRG1‐mediated inhibition in the course of lymphocyte activation. Subsequent to identification of the transferrin receptor (TfR) as a component of a high molecular mass KLRG1 complex, they demonstrate that a fraction of mouse KLRG1 molecules undergoes disulfide‐bonding with TfRs and colocalises with the latter at the cell surface. In functional terms, high levels of TfRs such as those found on activated lymphocytes were found to be associated with decreased KLRG1 inhibitory function, indicating that TfRs may sequester KLRG1 from interacting with cadherins. Hence, this unexpected liaison between KLRG1 and TfR may represent a regulatory link between metabolic activation and responses of lymphocytes.
Effect of cooking conditions on cholesterol oxidation and astaxanthin in dried salted shrimp
Authors: Hernández‐Becerra Josafat A. , Ochoa‐Flores Angélica A. , Soto‐Rodriguez Ida , Rodriguez‐Estrada Maria T. , García Hugo S.
Published: April 2014

Dried salted shrimp is a product made from raw shrimps, which are usually cooked and dried under direct sunlight. Brine cooking is an important step during the production of dried salted shrimp as it promotes changes that affect the product's end quality. The aim of this study was to evaluate the effect of brine concentration and boiling time on cholesterol oxidation products (COPs) formation and the concomitant changes in astaxanthin content and fatty acid profile in shrimp during cooking, sun drying, and storage. Boiling conditions did not affect COPs formation in shrimp after cooking. However, increased brine concentration and boiling time promoted high astaxanthin retention in cooked shrimp. During the first 24 h of sun drying, COPs formation in dried salted shrimp was influenced by the interaction between brine concentration and boiling time; in fact, the lowest COPs levels were observed in samples boiled at low brine concentration and short cooking times, as well as those boiled in brine with high salt concentration and long cooking times. Most astaxanthin (ca. 78%) present in cooked shrimp was degraded during solar drying. During storage, PUFA decreased, and a concomitant astaxanthin degradation and COPs formation in dried salted shrimp were observed. Neither boiling time nor storage at dark of dried salted shrimp prevented these changes.

Practical applications: The content of oxysterols in cooked dried shrimps can be minimized by optimizing the processing conditions to minimize the oxidation. This is useful for processors and consumers to reduce the intake of these toxic forms of cholesterol.

COPs and astaxanthin in dried shrimp were analysed during cooking, solar drying and storage. The COPs content in dried shrimp showed a dramatic increase after solar drying. During the ﬁrst 24 h of sun drying, COPs formation in dried salted shrimp was inﬂuenced by the brine concentration and boiling time.
Mitigating pesticide pollution in China requires law enforcement, farmer training, and technological innovation
Authors: Li Huizhen , Zeng Eddy Y. , You Jing
Published: April 2014

To feed an ever-growing population, it is necessary to take all measures to increase crop yields, including the use of pesticides. It has long been a difficult task to boost agricultural production and simultaneously minimize the impact of pesticide application on the environment, particularly in China, a developing country with more than 1.3 billion people. China has recently become the world's leading producer and consumer of pesticides, with production and consumption reaching 265 tons and 179 tons, respectively, in 2011, and a national average pesticide application dosage of more than 14 kg/ha. The large quantities of pesticides applied in agricultural fields have resulted in serious environmental deterioration. Organochlorine pesticides, such as dichloro-diphenyl-trichloroethane and hexachlorohexane, have become ubiquitous in the environment of China, with spatial distributions in soils and aquatic systems similar to their historic application patterns in different geographic regions: southeast > central > northwest. Pollution by current-use pesticides, for example, organophosphates and pyrethroids, has also been of great concern. To mitigate pesticide pollution in China, a significant reduction in pesticide inputs into the environment is mandatory. This can be accomplished only with joint efforts by the government, professionals, and citizens in combination with rigorous enforcement of laws and regulations, training of farmers in pesticide knowledge and environmental awareness, and technological innovation for producing low-risk pesticides and developing efficient application approaches. Restoring contaminated sites is also an urgent task. Finally, food security and environmental pollution are not problems for a sole country, and international cooperation and communication are necessary. Environ Toxicol Chem 2014;33:963–971. © 2014 SETAC
Lanthanum ions intervened in enzymatic production and elimination of reactive oxygen species in leaves of rice seedlings under cadmium stress
Authors: Wang Cheng-Run , Wang Qin-Ying , Tian Yuan , Zhang Ji-Feng , Li Zhi-Xiao , Cao Peng , Zhu Mei , Li Ting-Ting
Published: April 2014

Rare earth elements at proper concentrations were observed to alleviate heavy metal stress. However, the potential mechanisms of alleviation are not clear. Thus, the present study focused on the mechanisms of lanthanum (La) ions on the generation and elimination of reactive oxygen species (ROS) production in leaves of rice seedlings hydroponically cultivated in 30 µM cadmium chloride (CdCl2) for 2 d. Results showed that the decline of superoxide (O2 · −) or hydrogen peroxide (H2O2) was attributed not only to the decreased expressions of nicotinamide adenine dinucleotide phosphate oxidases-related gene, protein synthesis, and isozymes, but also to the decrease of xanthine oxidase, diamine oxidase, and guaiacol peroxidases isozymes and activities. Genes and isozymes related to superoxide dismutase, catalase, and ascorbate peroxidase were also differentially upregulated to control ROS accumulation when proper concentrations of La were combined with 30 µM Cd. Based on the results, one may conclude that La at proper concentrations not only limited the generation of O2 · − and H2O2 from the enzymatic sources but also promoted the elimination of O2 · − and H2O2 via the upregulating expressions of antioxidant enzyme–related genes and activities in the rice seedling's leaves under Cd stress. Environ Toxicol Chem 2014;33:1656–1664. © 2014 SETAC
Rapid settling of nanoparticles due to heteroaggregation with suspended sediment
Authors: Velzeboer Ilona , Quik Joris T.K. , van de Meent Dik , Koelmans Albert A.
Published: April 2014

Sedimentation of engineered nanoparticles (ENPs) has been studied mainly in artificial media and stagnant systems mimicking natural waters. This neglects the role of turbulence and heteroaggregation with sediment. The authors studied the apparent sedimentation rates of selected ENPs (cerium dioxide [CeO2], polyvinylpyrrolidone-capped silver [PVP-Ag], and silica-coated silver [SiO2-Ag]) in agitated sediment–water systems resembling fresh, estuarine, and marine waters. Experiments were designed to mimic low energy and periodically resuspended sediment water systems (14 d), followed by a long-term aging, resuspension, and settling phase (6 months), as would occur in receiving shallow lakes. The ENPs in systems with periodical resuspension of sediment were removed with sedimentation rates between 0.14 m/d and 0.50 m/d. The sedimentation rates did not vary much among ENP type, salinity, and aging time, which is attributed to the capture of ENPs in sediment flocks. The sedimentation rates were 1 to 2 orders of magnitude higher than those reported for aggregation–sedimentation in stagnant systems without suspended sediment. Heteroaggregation rates were estimated and ranged between 0.151 L/mg/d and 0.547 L/mg/d, which is up to 29 times higher than those reported for natural colloids under quiescent settling conditions. The authors conclude that rapid scavenging and sedimentation drives removal of ENPs from the water column. Environ Toxicol Chem 2014;33:1766–1773. © 2014 SETAC
An Investigation of the Impact of Misrouting Under Two‐Stage Multistage Testing: A Simulation Study
Authors: Kim Sooyeon , Moses Tim
Published: April 2014

The purpose of this study was to investigate the potential impact of misrouting under a 2‐stage multistage test (MST) design, which includes 1 routing and 3 second‐stage modules. Simulations were used to create a situation in which a large group of examinees took each of the 3 possible MST paths (high, middle, and low). We compared differences in examinees' scores associated with different paths under 2 MST assembly conditions: a small‐difference condition in which 3 modules at Stage 2 overlap in difficulty, and a large‐difference condition in which the 3 modules at Stage 2 are distinct in difficulty. We also compared examinees' score differences associated with the target MST path with the ones obtained when the second‐stage module was 1 level of difficulty above or below the target module. When the second‐stage modules overlapped in difficulty, the score differences (i.e., bias) associated with different MST paths were negligible for practical purposes. Similar trends appeared even when the second‐stage modules were significantly distinct in difficulty. The impact of misrouting was generally minimal under the MST design used in this study.
Creating Vocabulary Item Types That Measure Students' Depth of Semantic Knowledge
Authors: Deane Paul , Lawless René R. , Li Chen , Sabatini John , Bejar Isaac I. , O'Reilly Tenaha
Published: April 2014

We expect that word knowledge accumulates gradually. This article draws on earlier approaches to assessing depth, but focuses on one dimension: richness of semantic knowledge. We present results from a study in which three distinct item types were developed at three levels of depth: knowledge of common usage patterns, knowledge of broad topical associations, and knowledge of specific conceptual relationships. We attempted to avoid common sources of variance across items (such as attractive distracters) and hypothesized that the item types that required greater depth of semantic knowledge would tend to show greater difficulty and discrimination after other sources of variance were accounted for. Our results, while still exploratory, support the conclusion that the item types measure different aspects of lexical knowledge, consistent with the hypothesis of increasing semantic depth.