bluuebunny/crossref_metadata_2025 huggingface dataset:
Incomplete Wood–Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring
Dehalococcoides mccartyi
Authors: Zhuang Wei-Qin , Yi Shan , Bill Markus , Brisson Vanessa L. , Feng Xueyang , Men Yujie , Conrad Mark E. , Tang Yinjie J. , Alvarez-Cohen Lisa
Published: April 2014

Significance

We have studied the functionality of an incomplete acetyl-CoA “Wood–Ljungdahl” pathway in a strictly organohalide-respiring bacterium,
Dehalococcoides mccartyi
. We found that in addition to its ability to incorporate exogenous formate, this pathway cleaves acetyl-CoA to generate methyl-tetrahydrofolate for methionine biosynthesis, serving as a unique substitute of the missing methylene-tetrahydrofolate reductase function. We also found that accumulation of carbon monoxide (CO), an obligate by-product from acetyl-CoA cleavage, inhibits
D. mccartyi
axenic cultures, but can be ameliorated by the presence of a CO-oxidizing organism, resulting in an unusual syntrophic association. The understanding of the products and biosynthetic functions of this incomplete Wood–Ljungdahl pathway improves our knowledge of alternate central metabolic strategies used by environmental microorganisms.
[2Fe-2S] cluster transfer in iron–sulfur protein biogenesis
Authors: Banci Lucia , Brancaccio Diego , Ciofi-Baffoni Simone , Del Conte Rebecca , Gadepalli Ravisekhar , Mikolajczyk Maciej , Neri Sara , Piccioli Mario , Winkelmann Julia
Published: April 2014

Significance

Biogenesis of iron–sulfur proteins is a complex process requiring a large number of accessory proteins. In eukaryotes, [2Fe-2S] clusters are synthesized in mitochondria on a scaffold protein. The cluster is then released to monothiol glutaredoxin 5 (GRX5), which was proposed to mediate the transfer of [2Fe-2S] clusters from the scaffold protein to several target proteins, but its precise molecular function remains to be clarified. By investigating the molecular recognition between human GRX5 and its partner proteins (human ISCA1 and ISCA2) and characterizing at the molecular level the cluster transfer process between them, we have shown that a switch between two conformational states of holo GRX5 drives the cluster transfer event, which occurs by a specific protein–protein recognition process.
Partner choice and fidelity stabilize coevolution in a Cretaceous-age defensive symbiosis
Authors: Kaltenpoth Martin , Roeser-Mueller Kerstin , Koehler Sabrina , Peterson Ashley , Nechitaylo Taras Y. , Stubblefield J. William , Herzner Gudrun , Seger Jon , Strohm Erhard
Published: April 2014

Significance

Symbiotic microbes are essential for the survival of many multicellular organisms, yet the factors promoting cooperative symbioses remain poorly understood. Three genera of solitary wasps cultivate antibiotic-producing
Streptomyces
bacteria for defense of their larvae against pathogens. Here we show that the wasp ancestor acquired the protective symbionts from the soil at least 68 million years ago. Although mother-to-offspring symbiont transmission dominates, exchange between unrelated individuals and uptake of opportunistic microorganisms from the environment occasionally occurs. However, experimental infections of female beewolves reveal that the wasps selectively block transmission of nonnative bacteria to their offspring. These findings suggest a previously unknown mechanism to maintain a specific symbiont over long evolutionary timescales and help to explain the persistence of bacterial mutualists in insects.
Low glucose relates to greater aggression in married couples
Authors: Bushman Brad J. , DeWall C. Nathan , Pond Richard S. , Hanus Michael D.
Published: April 2014

Significance

People are often the most aggressive against the people to whom they are closest—intimate partners. Intimate partner violence might be partly a result of poor self-control. Self-control of aggressive impulses requires energy, and much of this energy is provided by glucose derived from the food we eat. We measured glucose levels in 107 married couples over 21 days. To measure aggressive impulses, participants stuck 0–51 pins into a voodoo doll that represented their spouse each night, depending how angry they were with their spouse. To measure aggression, participants blasted their spouse with loud noise through headphones. Participants who had lower glucose levels stuck more pins into the voodoo doll and blasted their spouse with louder and longer noise blasts.
Lipopolysaccharide O antigen size distribution is determined by a chain extension complex of variable stoichiometry inEscherichia coliO9a
Authors: King Jerry D. , Berry Scott , Clarke Bradley R. , Morris Richard J. , Whitfield Chris
Published: April 2014

Significance

Lipopolysaccharides (LPSs) are unique glycolipids that are characteristic components of outer membranes in Gram negative bacteria and play important roles in pathogenesis. Many LPSs contain a long-chain polysaccharide (known as the O antigen) whose length can be an important factor in bacterial resistance to complement-mediated killing. While components involved in chain-length determination are known in many systems, the underlying regulatory mechanism is not. Here we apply a mathematical modeling approach that integrates the existing structural and biochemical data to develop a new model, variable geometry, for chain-length regulation using the prototype for O antigens whose synthesis involves the widespread ATP-binding cassette transporter-dependent pathway.
Mapping the stochastic response of nanostructures
Authors: Pattamatta Subrahmanyam , Elliott Ryan S. , Tadmor Ellad B.
Published: April 2014

Significance

A challenge in nanotechnology is that nanoscale structures exhibit a rate-dependent and apparently random (stochastic) load-deflection behavior when repeated experimental measurements are compared. The variability in mechanical response is due to the extreme nonconvexity of the nanostructure’s energy versus structure function. The many minima of this function correspond to equilibrium states, accessible during loading, that create many possible pathways. Traditional atomistic simulation techniques cannot systematically address this complexity. Here, we explore a new method based on constructing an “equilibrium map” (akin to a phase diagram) that efficiently and systematically explores a nanostructure's stochastic, rate-dependent response to specified loading conditions. We demonstrate the method's capabilities and its surprisingly complex results for the case of a nanoslab of nickel under uniaxial compression.
Enhanced evolution by stochastically variable modification of epigenetic marks in the early embryo
Authors: Branciamore Sergio , Rodin Andrei S. , Riggs Arthur D. , Rodin Sergei N.
Published: April 2014

Significance

In this paper we investigate by quantitative modeling the effect on evolution of epigenetic variation during a window of opportunity in the early embryo. It is generally accepted that generation of new functions is primarily driven by gene duplication. However, pseudogenization (degradation of a new gene copy) is statistically much more likely than gaining a new function, and thus this remains a serious conceptual problem. We find that epigenetic variation, even in a constant environment, can essentially eliminate the pseudogenization problem and dramatically improve the efficacy of evolution by gene duplication.
Assessing the effects of anthropogenic aerosols on Pacific storm track using a multiscale global climate model
Authors: Wang Yuan , Wang Minghuai , Zhang Renyi , Ghan Steven J. , Lin Yun , Hu Jiaxi , Pan Bowen , Levy Misti , Jiang Jonathan H. , Molina Mario J.
Published: April 2014

Significance

Increasing levels of air pollutants in Asia have recently drawn considerable attention, but the effects of Asian pollution outflows on regional climate and global atmospheric circulation remain to be quantified. Using a multiscale global aerosol–climate model (GCM), we demonstrate long-range transport of the Asian pollution, large resulting variations in the aerosol optical depth, cloud droplet number concentration, and cloud and ice water paths; enhanced shortwave and longwave cloud radiative forcings; and increased precipitation and poleward heat transport. Our work provides, for the first time to the authors’ knowledge, a global multiscale perspective of the climatic effects of pollution outflows from Asia. The results reveal that the multiscale modeling framework is essential in simulating the aerosol invigoration effect of deep convective cloud systems by a GCM.
Rescuing US biomedical research from its systemic flaws
Authors: Alberts Bruce , Kirschner Marc W. , Tilghman Shirley , Varmus Harold
Published: April 2014

The long-held but erroneous assumption of never-ending rapid growth in biomedical science has created an unsustainable hypercompetitive system that is discouraging even the most outstanding prospective students from entering our profession—and making it difficult for seasoned investigators to produce their best work. This is a recipe for long-term decline, and the problems cannot be solved with simplistic approaches. Instead, it is time to confront the dangers at hand and rethink some fundamental features of the US biomedical research ecosystem.
Defining modulatory inputs into CNS neuronal subclasses by functional pharmacological profiling
Authors: Raghuraman Shrinivasan , Garcia Alfredo J. , Anderson Tatiana M. , Twede Vernon D. , Curtice Kigen J. , Chase Kevin , Ramirez Jan-Marino , Olivera Baldomero M. , Teichert Russell W.
Published: April 2014

Significance

We functionally profiled cells from a locus of the mouse brainstem that contains the neuronal network responsible for generating breathing patterns. By uncovering cell-specific constellations (i.e., distinctive combinations of receptors and ion channels that define each cell type), we identified specific neuronal classes and subclasses within the network. We discovered neuromodulators affecting the activity of specific neuronal subclasses within the functional network. This study provides proof-of-principle that a pharmacological strategy for altering the activity of a specific type of neuron can be developed which has potential as a parallel or complementary approach to genetic strategies for functionally perturbing a specific neuronal cell type in vivo. Additionally, unlike genetic approaches, this pharmacological approach is directly applicable to nonmodel organisms.
Glioblastoma cellular architectures are predicted through the characterization of two-cell interactions
Authors: Kravchenko-Balasha Nataly , Wang Jun , Remacle Francoise , Levine R. D. , Heath James R.
Published: April 2014

Significance

Microscopic analysis of cellular architectures within a diseased tissue often provides an independent assay relative to measurements of molecular biomarkers from that same tissue. Both methods may point to the same disease state, but the relationship between the two is often not clear. We explore a connection by investigating how growth factor-driven protein signaling depends upon the distance separating pairs of cancer cells. A thermodynamic-derived theory identifies the intercellular separation that corresponds to the steady state of the signaling. That length scale is found to be the dominant cell separation distance in bulk tissue culture. The approach is tested in one cell line and validated in another, and may provide insight into the diffusive nature of certain brain cancer phenotypes.
Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides
Authors: Fang Hui , Battaglia Corsin , Carraro Carlo , Nemsak Slavomir , Ozdol Burak , Kang Jeong Seuk , Bechtel Hans A. , Desai Sujay B. , Kronast Florian , Unal Ahmet A. , Conti Giuseppina , Conlon Catherine , Palsson Gunnar K. , Martin Michael C. , Minor Andrew M. , Fadley Charles S. , Yablonovitch Eli , Maboudian Roya , Javey Ali
Published: April 2014

Significance

A new class of heterostructures consisting of layered transition metal dichalcogenide components can be designed and built by van der Waals (vdW) stacking of individual monolayers into functional multilayer structures. Nonetheless, the optoelectronic properties of this new type of vdW heterostructure are unknown. Here, we investigate artificial semiconductor heterostructures built from single-layer WSe
2
and MoS
2
. We observe spatially direct absorption but spatially indirect emission in this heterostructure, with strong interlayer coupling of charge carriers. The coupling at the hetero-interface can be readily tuned by inserting hexagonal BN dielectric layers into the vdW gap. The generic nature of this interlayer coupling is expected to yield a new family of semiconductor heterostructures having tunable optoelectronic properties through customized composite layers.
Thalamocortical rhythms during a vibrotactile detection task
Authors: Haegens Saskia , Vázquez Yuriria , Zainos Antonio , Alvarez Manuel , Jensen Ole , Romo Ranulfo
Published: April 2014

Significance

When a near-threshold sensory stimulus is presented, a sensory percept may or may not be produced. The exact process by which neural activity elicits subjective perception is a long-standing open question. Here, we ask what role brain oscillations in early sensory regions play in this cognitive process, as oscillations are thought to reflect population dynamics, indicative of the state of a brain network. We found task-related modulations in oscillatory activity in both the somatosensory thalamus and primary sensory cortex, which were correlated with the perceptual decision process and subsequent behavioral response. We conclude that these early sensory regions, in addition to their primary sensory functions, may be actively involved in perceptual decision making.
Correlative markers in EU-parliamentary French debate
Authors: Svensson Maria
Published: April 2014

The purpose of this paper is to describe the function of non seulement… mais (‘not only… but’) and et même (‘and even’) in the organization of argumentation in EU-parliamentary debate. They both reinforce the argumentation for a conclusion, but they behave differently on a textual-discursive level. Et même marks a difference in argumentative force between arguments, whereas non seulement… mais can also be used as a purely additive marker without implication on the scalarity between the arguments. This study is based on C-ParlEur. Corpus de discours du PARLement EURopéen consisting of 919 speeches during the debates delivered by the 78 French MEPs during the April 2006–March 2008 period.
Abstracting phonological generalizations
Authors: Gierut Judith A. , Morrisette Michele L. , Younger Caitlin J.
Published: April 2014

The purpose was to document the trials to induce first generalization in children with phonological disorders enrolled in treatment. Archival data from 65 preschoolers were examined, with three kinds of generalization documented: treated, within- and across-class gains in production accuracy. Overall, an average of 185 trials was sufficient to induce first generalization, but this varied based on the kind of generalization that occurred. Across-class generalization required the fewest trials and generalization to the treated sound, the most trials. Results bear on applied issues associated with lexical diffusion in clinical treatment and theoretical issues associated with error-driven learning algorithms and abstraction of phonological generalizations from the input.
Rapid phonological coding and working memory dynamics in children with cochlear implants
Authors: Pisoni David B.
Published: April 2014

Past research on cochlear implants in deaf children has been narrowly focused on speech and language outcomes and efficacy of cochlear implantation as a medical treatment for profound hearing loss. Little, if any, basic or clinical research has investigated the underlying neurobiological and cognitive factors that are responsible for the enormous individual differences and variability in the effectiveness of cochlear implants in this unique clinical population. Our research over the last twenty years has demonstrated that a small number of core elementary cognitive processes such as rapid phonological coding, working memory dynamics, processing speed, inhibition and sequence learning are strongly associated with traditional “endpoint” clinical speech and language outcome measures. These foundational cognitive processes reflect the global coordination, integration and functional connectivity of multiple underlying brain systems used in speech perception, production and spoken language processing. Our findings on the underlying sources of variability in spoken language processing provide a new theoretical framework that can help to understand and explain the enormous individual differences in speech and language outcomes following cochlear implantation. The results of our research have direct clinical implications for improving the diagnosis, treatment and early identification of young profoundly deaf children who may be at high risk for poor speech and language outcomes following cochlear implantation.
Effects of Streamflow Diversion on a Fish Population: Combining Empirical Data and Individual-Based Models in a Site-Specific Evaluation
Authors: Harvey Bret C. , White Jason L. , Nakamoto Rodney J. , Railsback Steven F.
Published: April 2014

Resource managers commonly face the need to evaluate the ecological consequences of specific water diversions of small streams. We addressed this need by conducting 4 years of biophysical monitoring of stream reaches above and below a diversion and applying two individual-based models of salmonid fish that simulated different levels of behavioral complexity. The diversion of interest captured about 24% of streamflow between June and October but had little or no effect over the remainder of the year. The change in biomass of Rainbow Trout Oncorhynchus mykiss and steelhead (anadromous Rainbow Trout) over the dry season (June–October) favored the upstream control over the downstream diversion reach over 4 years (2008–2011). Dry-season growth did not differ consistently between the two reaches but did exhibit substantial annual variation. Longer-term observations revealed that in both reaches most fish growth occurred outside the period of dry-season diversion. After calibration to the upstream control reach, both individual-based models predicted the observed difference in fish biomass between control and diversion reaches at the ends of the dry seasons. Both models suggested the difference was attributable in part to differences in habitat structure unrelated to streamflow that favored the upstream reach. The two models both also reproduced the large seasonal differences in growth, small differences between reaches in individual growth, and natural distributions of growth among individuals. Both the empirical data and simulation modeling suggested that the current level of diversion does not threaten the persistence of the salmonid population. In multiyear simulations using the two models, the model incorporating greater flexibility in fish behavior exhibited weaker population-level responses to more extreme reductions in dry-season streamflow. We believe the application of individual-based models in this case has placed resource managers in a relatively strong position to forecast the consequences of future environmental alterations at the study site.

Received March 22, 2013; accepted October 17, 2013
Measuring the Economic Value of Increased Precision in Scientific Estimates of Marine Mammal Abundance and Bycatch: Harbor Porpoise Phocoena phocoena in the Northeast U.S. Gill-Net Fishery
Authors: Bisack Kathryn D. , Magnusson Gisele
Published: April 2014

Marine mammal stock assessments provide information that is valuable to public sector management and the private fishing sector; however, data are costly to collect. The precautionary approach, which is widely used in fishery and marine mammal management, advocates a conservative management decision with priority to the resource when there is uncertainty regarding the impact on the resource from human activity. The potential biological removal (PBR) control rule of the U.S. Marine Mammal Protection Act explicitly incorporates uncertainty in input variables into the determination of allowable levels of human-induced mortality for a stock. Less uncertainty results in higher PBR values for a given stock level. Variations in government funding levels can disrupt the scientific data collection that is necessary for PBR calculation. We present an economic net benefit framework that examines the indirect value of information from marine mammal stock assessments to the commercial fishing industry. Using the harbor porpoise Phocoena phocoena and the U.S. Atlantic sink gill-net fishery as a case study, we estimated the difference between total public sector data collection costs and total private sector benefits from increased profits. Net benefits represent a measure of the value of information to society, while the difference in profits measures the value of the information to the private sector. Several results are forthcoming. First, the optimal allocation of funding showed that abundance surveys are a more cost-effective means to reduce uncertainty in PBR input variables than increasing observer coverage of the fishing industry. Second, for all levels of PBR in this empirical example, total benefits to the private sector for a higher PBR exceeded the costs of collecting additional scientific data to increase the precision of input variables and thus increase PBR. Since net benefits are positive, the private sector may consider funding of scientific data collection for marine mammals as a way to reduce uncertainty, thereby allowing a higher PBR value.

Received March 19, 2013; accepted November 14, 2013
Evaluation of Calcein for Estimating Abundance of Lake Trout Alevins on a Spawning Reef
Authors: Marsden J. Ellen , Kelsey Kevin P. , Riley Jacob W. , Hatt Joanna
Published: April 2014

Reproduction by stocked Lake Trout Salvelinus namaycush is generally estimated as the relative abundance of fry, that is, catch per unit effort in emergent fry traps and in beam trawls, but these estimates have high variance due to spatially heterogeneous distributions of fry. We used calcein, which produces a fluorescent mark in calcified structures, to batch-mark fry and generate a mark–recapture estimate of fry abundance on a small, shallow spawning reef. Eggs collected from feral Lake Trout in Lake Champlain, Vermont were reared at ambient lake temperatures, and fry were marked 7 d after hatching. Fry were immersed in a salt solution for osmotic induction and then placed for 4 min in a calcein solution. After marking, 18,000 fry were released on a spawning reef, and 2,000 fry were maintained in the hatchery. Wild-caught fry and hatchery fry were checked for marks every 2–9 d. Mark clarity was highest in the mandible and tail rays. Marks may have faded, but they did not disappear: marks were visible in the mandible in 100% of hatchery fry after 68 d. An average of 37% of wild-caught fry had marks, yielding a Chapman population estimate (±SD) of 47,486±2,301. The mark–recapture estimate was within the range of fry abundance estimated over 6 years based on egg density data and estimates of hatching success but was substantially higher than estimated for the same year-class. This work supports prior estimates of fry abundance and provides a potential method for assessing fry abundance on deep reefs and the success of fry stocking.

Received June 4, 2013; accepted November 20, 2013
Population Structure and Run Timing of Sockeye Salmon in the Skeena River, British Columbia
Authors: Beacham Terry D. , Cox-Rogers Steven , MacConnachie Cathy , McIntosh Brenda , Wallace Colin G.
Published: April 2014

Determination of run timing is an important component of salmonid fisheries management and was the major focus of the current study. Population structure of Sockeye Salmon Oncorhynchus nerka was examined in the Skeena River, northern British Columbia. Variation at 14 microsatellites was surveyed for 27 populations in the drainage. There were 9,473 individuals sampled in a lower river test fishery during 2000–2011 in order to provide information on relative abundance and time of arrival of specific populations or stocks near the mouth of the river. Within-lake or within-river tributary structuring of populations was the general pattern observed, with 10 populations from Babine Lake clustering together in 91% of dendrograms evaluated, and two populations from Lakelse Lake clustering together in 100% of dendrograms evaluated. The 27 populations sampled were arranged in 12 reporting groups for genetic stock identification applications. The estimated stock composition of known-origin mixtures was within 2% of the correct estimate for all 12 reporting groups present in the mixtures. Sockeye Salmon typically began arriving at the test fishery on the lower Skeena River by June 10, peaking in daily abundance in late July or early August, and finished migrating past the test fishery by mid-September. Relative timing of the 12 reporting groups, from earliest to latest, was as follows: Lakelse Lake, Alastair Lake, Zymoetz River, Morice Lake, Kispiox River, Sustut Lake, Babine Lake, Slamgeesh Lake, Motase Lake, Bear Lake, Kitsumkalum Lake, and Kitwanga Lake. Genetic mixed-stock analysis, coupled with a test fishery in the lower river, can assist managers in regulating fisheries directed at Skeena River Sockeye Salmon.

Received February 12, 2013; accepted December 4, 2013
Impacts of External and Surgery-Based Tagging Techniques on Small Northern Pike Under Field Conditions
Authors: Hühn Daniel , Klefoth Thomas , Pagel Thilo , Zajicek Petr , Arlinghaus Robert
Published: April 2014

In Northern Pike Esox lucius negligible effects of external tags on growth and survival have commonly been reported, but no studies exist for age-0 fish. We tested the impacts of fin clipping, PIT tags, and three external tags (T-bar anchor, opercular, and streamer tags) on age-0 Northern Pike in a pond. We also examined the impacts of surgically implanted transmitters on small adult Northern Pike in a natural lake. The loss of PIT tags was lowest among all tags and close to 0%. Of the external tags, T-bar anchor tags performed best. Loss of these tags was initially low (on average 5.7% after 195 d) increasing to about 20.0% by 520 d posttagging. Tagging-induced mortality of a few percent was present in all tags tested within the first 195 d posttagging in the pond environment but not present afterwards. The PIT tags, fin clips, and external tags did not affect the growth or condition of surviving fish. Surgically implanted transmitters reduced the growth of small adult Northern Pike with total lengths <480 mm, but no effects were found for larger individuals. We conclude that PIT tagging is the most suitable marking technique for age-0 Northern Pike. If external visibility is required, T-bar anchor tags are also useful, as long as tagging-induced mortality and tag loss rates are accounted for at the analysis stage. Our study raises a cautionary note about surgically implanted transmitters in small adult Northern Pike, as they may negatively affect behavior and fitness.

Received March 27, 2013; accepted November 26, 2013
Risk-Based Management of Viral Hemorrhagic Septicemia Virus in Minnesota
Authors: Phelps Nicholas B. D. , Craft Meggan E. , Travis Dominic , Pelican Katharine , Goyal Sagar M.
Published: April 2014

Viral hemorrhagic septicemia virus (VHSV; strain VHSV-IVb) is an emergent and serious disease of fish in the Great Lakes region of North America. In addition to the numerous large-scale mortality events in wild fish, the emergence of VHSV has resulted in a major regulatory response to protect both farm-raised and wild fish populations. However, characterizing and mitigating risk factors for the continued transmission of VHSV is a difficult task. A semiquantitative risk assessment model was used to focus VHSV management efforts in Minnesota. The risk of VHSV introduction into major watersheds in Minnesota was directly correlated to their proximity to Lake Superior, the only VHSV-positive body of water in the state. Although the current regulations are uniform across Minnesota, the risk varied for specific locations within the watersheds. For example, the introduction of game fish for stock enhancement (a common fisheries management practice) is a significant factor in determining the risk of VHSV introduction into public waters, as is the movement of baitfish. In this analysis, aquaculture facilities with strict biosecurity programs and frequent health inspections received the lowest risk scores and were largely considered as protective or at low risk for VHSV introduction. These results suggest that the current management strategy, based on political boundaries, should be reevaluated. We recommend the creation of a risk-based management strategy based upon the identification of higher-risk watersheds and specific bodies of water, thus allowing managers to efficiently target surveillance and response activities in Minnesota.

Received July 22, 2013; accepted November 27, 2013
Limit Reference Points for Pacific Salmon Fisheries
Authors: Portley Nicole , Geiger Harold J.
Published: April 2014

“Limit reference points” define a state at which fishery management has reached overfishing, overfished stock status, or some other regulatory or conservation point of concern. In many Pacific salmon Oncorhynchus spp. fishery jurisdictions, management only uses “target reference points”—the specific numerical management objective intended to bring about some fishery benefit. There are several reasons to adopt limit reference points, and jurisdictions without previously defined limit reference points could adopt them in order to align better with the Magnuson–Stevens Act (American fisheries) or, more importantly, to facilitate cross-jurisdiction sustainability assessments, which are increasingly needed for certifications of sustainability. In actual practice, the stock size of 0.5 times a target reference point has been used as a limit reference point for some Pacific salmon fisheries, or at least as a proxy for a limit reference point. We term this point the “minimum stock size threshold,” following a convention already in use, and we note that limit reference points defined this way are increasingly being accepted as a standard either because of justification based on simulation and fishery principles or for purely pragmatic reasons.

Received July 2, 2013; accepted January 6, 2014
Coded Wire Tag and Passive Integrated Transponder Tag Implantations in Juvenile Burbot
Authors: Ashton Neil K. , Anders Paul J. , Young Shawn P. , Cain Kenneth D.
Published: April 2014

Regional stakeholders in various nations are investigating the restoration of imperiled and extirpated Burbot Lota lota populations via the stocking of hatchery-produced fish. Although stocking programs routinely tag fish for monitoring and evaluation projects, there is currently only limited information available regarding effective tagging techniques for use with juvenile Burbot. We identified two anatomical locations (dorsal muscle and peritoneum) that were suitable for PIT tag implantation and six body sites (snout, periocular region, nape, pectoral fin base, dorsal fin base, and ventral [anal fin base]) that were suitable for coded wire tag batch marking of age-0 Burbot (88–144 mm TL). Our evaluation of these implantation methods generally revealed a high rate of tag retention (>95%) and no significant tagging effects on fish survival or growth. A follow-up study also demonstrated satisfactory mass-marking rates for both tag types. Coded wire tags and PIT tags should provide harmless, affordable, long-term identification of hatchery Burbot juveniles.

Received August 27, 2013; accepted December 27, 2013
Effects of Structural and Spatiotemporal Factors on Fish Use of Artificial Habitat in a Texas Reservoir
Authors: Daugherty Daniel J. , Driscoll M. Todd , Ashe Daniel E. , Schlechte J. Warren
Published: April 2014

We evaluated fish use of artificial habitat in relation to structure size and shape and the spatiotemporal factors of season, diel period, and reservoir region in Striker Reservoir, Texas. Recycled Christmas trees were used to construct three sizes of cluster- and linear-shaped structures; fish at each were sampled seasonally during the day and night with electrofishing. Largemouth Bass Micropterus salmoides and Bluegill Lepomis macrochirus comprised 57% of the fish collected; other centrarchids comprised an additional 33%. Overall fish assemblages at the habitat structures were not related to the factors we examined. However, species-specific analyses indicated that the percentage of structures occupied, catch per unit effort (CPUE), and mean size of Largemouth Bass and Bluegills were influenced by the factors we examined. Largemouth Bass exhibited a greater percent occupancy of the largest structures and a higher CPUE in small structures; the mean size (TL) of Largemouth Bass was lower in cluster-shaped structures at night. Bluegill percent occupancy and CPUE were significantly greater in cluster-shaped structures than in linear-shaped ones; however, larger individuals were more often found in linear-shaped structures. Spatiotemporal differences in percent occupancy, CPUE, and mean TL were apparent, with greater abundance of both species during summer and fall and larger mean TL of Largemouth Bass during spring. The percentage of structures occupied by Largemouth Bass was significantly higher in the lower reservoir; however, mean TL was higher among structures in the upper reservoir. The percentage of structures occupied by Bluegills, as well as CPUE, was greater in the lower reservoir. Our results suggest that both the size and shape of artificial habitats, as well as spatiotemporal factors, should be considered when planning habitat enhancement efforts.

Received September 4, 2013; accepted December 19, 2013
Effects of Dietary Protein and Fish Density on Performance and Production Economics of Golden Shiners in Pools
Authors: Lochmann R T , Phillips H , Weldon D , Stone N , Engle C
Published: April 2014

We conducted an outdoor feeding trial with Golden Shiners Notemigonus crysoleucas using diets with 22% or 28% protein from different sources. The 28% protein diet with soybean (SOY) meal was the control, and the three other diets contained 22% protein mainly from SOY, corn gluten feed (CGF), or corn distillers dried grains with solubles (DDGS). The 22% protein SOY diet was also offered as a meal or pellet in separate treatments. Each of the five diets was fed to fish at two densities: 250,000 fish/ha (low density) or 750,000 fish/ha (high density). Fish with an initial weight of 0.25 ± 0.003 g (mean ± SE) were stocked into four 4.1-m3 pools per treatment and fed daily to apparent satiation for 9 weeks. Diet effects were assessed by measuring growth, survival, feed conversion, condition index, and body composition. An enterprise budget analysis was conducted to determine the economic effects of different treatments. Fish weight gain was higher at the low density regardless of diet. Weight gain was also higher in fish fed the diet with 28% protein than in those fed other diets at either density. Relative weight (Wr) was higher at the high density and in fish fed the SOY diets compared with those fed the CGF or DDGS diets. Survival was higher at the high density, and no diet effects were apparent. Gross yield was higher at the high density and in the 28% protein SOY control. Feed conversion ratio was better at the low density. Whole-body lipid was higher in fish at the low density. The most economically beneficial diet was the 28% protein SOY diet, but producers must consider feed choice in the context of their overall business model. The 22% protein diets were inadequate for rapid growth, but did not compromise survival, indicating a possible use for maintenance feeding when fish reach market size.
Effect of Stocking Density on Growth and Survival of the Prawn Macrobrachium tenellum Cultured in a Cage-Pond System
Authors: López-Uriostegui Fermín , Ponce-Palafox Jesús T , Arredondo-Figueroa José L , Benítez-Mandujano Mario A , Gómez Manuel García-Ulloa , Vargasmachuca Sergio Castillo , Esparza-Leal Héctor M
Published: April 2014

Freshwater prawns, Macrobrachium tenellum, were reared at four stocking densities (6, 12, 18, and 24 prawns/m3), with three replicates each, in 12 bottom cages of 3 m3 capacity that were placed in a 1,422-m2 earthen pond. The growth, weight gain, production, specific growth rate (SGR), feed conversion ratio (FCR), and survival of the prawns were determined. We stocked 540 juveniles that had an average weight of 1.57 ± 0.09 g (mean ± SE) for 180 d and fed them twice a day with commercial shrimp pellets containing 35% crude protein. Water quality variables were measured during the study. All of the growth and production parameters were affected by stocking density (P < 0.05). The mean weight and SGR increased at low densities. The lowest mean weight (17.2 ± 2.0 g) was observed at the higher density (24 prawns/m3), although production increased at high densities and varied from 1,307.2 kg/ha at a density of 6 prawns/m3 to 2,013.3 kg/ha at a density of 24 prawns/m3. Survival varied from 79 ± 1% at a density of 6 prawns/m3 to 47.5 ± 0.6% at a density of 24 prawns/m3. The overall results suggested that stocking density affected the growth and survival of M. tenellum cultured in the cage-pond system. The initial stocking density represents a very important culture variable in terms of marketing for this freshwater prawn because at all tested densities the prawns reached their individual market size.
Methods and Accuracy of Sexing Sockeye Salmon Using Ultrasound for Captive Broodstock Management
Authors: Frost Deborah A , McAuley W Carlin , Kluver Bryon , Wastel Mike , Maynard Desmond , Flagg Thomas A
Published: April 2014

Ultrasound has been widely used to noninvasively examine the internal anatomy and reproductive status of many fish species. Since 2003, ultrasonography has been an integral part of broodstock management for Endangered Species Act–listed endangered Redfish Lake Sockeye Salmon Oncorhynchus nerka. Initial ultrasound screenings for each year's broodstock were conducted 3 to 4 months prior to anticipated maturation, before external signs of maturation developed. In keeping with the natural life history of these fish, this permitted the separation of nonmaturing fish from maturing fish so the immature fish could maintain feeding and growth. It also permitted maturing seawater-reared fish to be transferred to freshwater for final maturation. Designing a spawning matrix to maintain genetic diversity requires knowledge of the sex of each fish before spawning. Approximately 1 month prior to spawning, a second ultrasound was performed to verify sex identification and thus ensure the accuracy of the spawning matrix. Over a 9-year period, 2,662 fish were examined. The accuracy of sexing age-3 adult Sockeye Salmon ranged from 94.0% to 100%, with an average of 97.7%, while the accuracy of sexing age-4 adult fish ranged from 92.0% to 100%, with an average of 94.4%. The average accuracy was similar for fish examined in seawater or freshwater (98.1% versus 97.3%, respectively). Ultrasound was shown to be an accurate and effective tool for managing the husbandry of our captive broodstock life history.
The brain in micro‐ and hypergravity: The effects of changing gravity on the brain electrocortical activity
Authors: Marušič Uroš , Meeusen Romain , Pišot Rado , Kavcic Voyko
Published: April 2014

Understanding the effects of increased and decreased gravity on central nervous system is essential for developing proper physical and cognitive countermeasures to assure safe and effective space missions and human survival in space. This short review covers the available literature on the brain electrocortical activity effects of decreased and increased gravitational force comparing to the 1g Earth conditions. Among all neuroimaging methods such as functional magnetic resonance imaging (fMRI), positron‐emission tomography (PET), diffusion tensor imaging (DTI), the electroencephalography (EEG) was found to be suitable method to monitor brain electrocortical activity in the extreme environments. Due to complexity and high cost of space flight missions, ground‐based models have been employed to simulate microgravity effects on human body. Surprisingly, there is very limited number of publications reporting gravity‐dependent EEG spectral changes. With increased gravity there are initially increased EEG activity in higher frequencies and at around 4g appears loss of consciousness with accompanying slowing of EEG due to hypoxia. In microgravity, the most prevalent changes in EEG are faster frequencies such as alpha and beta. The results from simulated microgravity (bed rest) are pointing to changes in theta and alpha, representing signs of cortical inhibition. The changes in EEG activity in space flight are attributed to a decreased sensorimotor input while in parabolic flights short and fast transitions from hyper to microgravity presumably reflect lower arousal levels and emotional processes in microgravity. Thus, based on limited research about gravity‐related changes in EEG from different environments it is difficult to draw any unequivocal conclusions. Additional systematic studies about electrocortical activity in space and parabolic flights, as well as longer bed rest studies are needed in order to advance knowledge about brain functioning in extreme conditions such as space flights.
Targeting CXCR7/ACKR3 as a therapeutic strategy to promote remyelination in the adult central nervous system
Authors: Williams Jessica L. , Patel Jigisha R. , Daniels Brian P. , Klein Robyn S.
Published: April 2014

Current treatment modalities for the neurodegenerative disease multiple sclerosis (MS) use disease-modifying immunosuppressive compounds but do not promote repair. Although several potential targets that may induce myelin production have been identified, there has yet to be an approved therapy that promotes remyelination in the damaged central nervous system (CNS). Remyelination of damaged axons requires the generation of new oligodendrocytes from oligodendrocyte progenitor cells (OPCs). Although OPCs are detected in MS lesions, repair of myelin is limited, contributing to progressive clinical deterioration. In the CNS, the chemokine CXCL12 promotes remyelination via CXCR4 activation on OPCs, resulting in their differentiation into myelinating oligodendrocytes. Although the CXCL12 scavenging receptor CXCR7/ACKR3 (CXCR7) is also expressed by OPCs, its role in myelin repair in the adult CNS is unknown. We show that during cuprizone-induced demyelination, in vivo CXCR7 antagonism augmented OPC proliferation, leading to increased numbers of mature oligodendrocytes within demyelinated lesions. CXCR7-mediated effects on remyelination required CXCR4 activation, as assessed via both phospho-S339-CXCR4–specific antibodies and administration of CXCR4 antagonists. These findings identify a role for CXCR7 in OPC maturation during remyelination and are the first to use a small molecule to therapeutically enhance myelin repair in the demyelinated adult CNS.
B-RAF kinase drives developmental axon growth and promotes axon regeneration in the injured mature CNS
Authors: O’Donovan Kevin J. , Ma Kaijie , Guo Hengchang , Wang Chen , Sun Fang , Han Seung Baek , Kim Hyukmin , Wong Jamie K. , Charron Jean , Zou Hongyan , Son Young-Jin , He Zhigang , Zhong Jian
Published: April 2014

Activation of intrinsic growth programs that promote developmental axon growth may also facilitate axon regeneration in injured adult neurons. Here, we demonstrate that conditional activation of B-RAF kinase alone in mouse embryonic neurons is sufficient to drive the growth of long-range peripheral sensory axon projections in vivo in the absence of upstream neurotrophin signaling. We further show that activated B-RAF signaling enables robust regenerative growth of sensory axons into the spinal cord after a dorsal root crush as well as substantial axon regrowth in the crush-lesioned optic nerve. Finally, the combination of B-RAF gain-of-function and PTEN loss-of-function promotes optic nerve axon extension beyond what would be predicted for a simple additive effect. We conclude that cell-intrinsic RAF signaling is a crucial pathway promoting developmental and regenerative axon growth in the peripheral and central nervous systems.
State-dependent and site-directed photodynamic transformation of HCN2 channel by singlet oxygen
Authors: Gao Weihua , Su Zhuocheng , Liu Qinglian , Zhou Lei
Published: April 2014

Singlet oxygen (1O2), which is generated through metabolic reactions and oxidizes numerous biological molecules, has been a useful tool in basic research and clinical practice. However, its role as a signaling factor, as well as a mechanistic understanding of the oxidation process, remains poorly understood. Here, we show that hyperpolarization-activated, cAMP-gated (HCN) channels–which conduct the hyperpolarization-activated current (Ih) and the voltage-insensitive instantaneous current (Iinst), and contribute to diverse physiological functions including learning and memory, cardiac pacemaking, and the sensation of pain–are subject to modification by 1O2. To increase the site specificity of 1O2 generation, we used fluorescein-conjugated cAMP, which specifically binds to HCN channels, or a chimeric channel in which an in-frame 1O2 generator (SOG) protein was fused to the HCN C terminus. Millisecond laser pulses reduced Ih current amplitude, slowed channel deactivation, and enhanced Iinst current. The modification of HCN channel function is a photodynamic process that involves 1O2, as supported by the dependence on dissolved oxygen in solutions, the inhibitory effect by a 1O2 scavenger, and the results with the HCN2-SOG fusion protein. Intriguingly, 1O2 modification of the HCN2 channel is state dependent: laser pulses applied to open channels mainly slow down deactivation and increase Iinst, whereas for the closed channels, 1O2 modification mainly reduced Ih amplitude. We identified a histidine residue (H434 in S6) near the activation gate in the pore critical for 1O2 modulation of HCN function. Alanine replacement of H434 abolished the delay in channel deactivation and the generation of Iinst induced by photodynamic modification. Our study provides new insights into the instantaneous current conducted by HCN channels, showing that modifications to the region close to the intracellular gate underlie the expression of Iinst, and establishes a well-defined model for studying 1O2 modifications at the molecular level.