bluuebunny/crossref_metadata_2025_split huggingface dataset:
Costs of colour change in fish: food intake and behavioural decisions
Authors: Rodgers Gwendolen M. , Gladman Nicholas , Corless Hannah , Morrell Lesley 
Published: April 2013

SummaryMany animals, particularly reptiles, amphibians, fish and cephalopods, have the ability to change their body colour, for functions including thermoregulation, signalling and predator avoidance. Many fish plastically darken their body colouration in response to dark visual backgrounds, and this functions to reduce predation risk. Here, we test the hypotheses that 1) colour change in fish carries with it an energetic cost and 2) affects subsequent shoal and habitat choice decisions. We demonstrate that guppies (Poecilia reticulata) change colour in response to dark and light visual backgrounds, and that doing so carries an energetic cost in terms of food consumption. By increasing food intake, however, guppies are able to maintain growth rates and meet the energetic costs of changing colour. Following colour change, fish preferentially chose habitats and shoals that match their own body colouration, and maximise crypsis, thus avoiding the need for further colour change, but also potentially paying an opportunity cost associated with restriction to particular habitats and social associates. Thus, colour change to match the background is complemented by behavioural strategies, which should act to maximise fitness in variable environments.
Genetically and environmentally mediated divergence in lateral line morphology in the Trinidadian guppy (Poecilia reticulata)
Authors: Fischer Eva K. , Soares Daphne , Archer Kathryn R. , Ghalambor Cameron K. , Hoke Kim L. 
Published: April 2013

Summary
Fish and other aquatic vertebrates use their mechanosensory lateral line to detect objects and motion in their immediate environment. Differences in lateral line morphology have been extensively characterized among species, however intraspecific variation remains largely unexplored. In addition, little is known about how environmental factors modify development of lateral line morphology. Predation is one environmental factor that can act both as a selective pressure causing genetic differences between populations, and as a cue during development to induce plastic changes. Here, we test if variation in the risk of predation within and among populations of Trinidadian guppies (Poecilia reticulata) influences lateral line morphology. We compared neuromast arrangement in wild-caught guppies from distinct high- and low-predation population pairs to examine patterns associated with differences in predation pressure. To distinguish genetic and environmental influences, we compared neuromast arrangement in guppies from different source populations reared with and without exposure to predator chemical cues. We found that the distribution of neuromasts across the body varies between populations based on both genetic and environmental factors. To the best of our knowledge, this study is the first to demonstrate variation in lateral line morphology based on environmental exposure to an ecologically relevant stimulus.
Physiological adaptations to reproduction I. Experimentally increasing litter size enhances aspects of antioxidant defence but does not cause oxidative damage in mice
Authors: Garratt Michael , Pichaud Nicolas , King Edith D. Aloise , Brooks Robert C. 
Published: April 2013

SummaryLife history theory suggests that investment in reproduction can trade off against growth, longevity and both reproduction and performance later in life. One possible reason for this trade-off is that reproduction directly causes somatic damage. Oxidative stress, an overproduction of reactive oxygen species in relation to cellular defences, can correlate with reproductive investment and has been implicated as a pathway leading to senescence. This has led to the suggestion that this aspect of physiology could be an important mechanism underlying the trade-off between reproduction and lifespan. We manipulated female reproductive investment to test whether oxidative stress increases with reproduction in mice. Each female's pups were cross-fostered to produce litters of either two or eight, representing small and large levels of reproductive investment for wild mice. No differences were observed between reproductive groups at peak-lactation for several markers of oxidative stress in the heart and gastrocnemius muscle. Surprisingly, oxidative damage to proteins was lower in the livers of females with a litter size of eight than in females with two pups or non-reproductive control females. While protein oxidation decreased, activity levels of the antioxidant enzyme superoxide dismutase increased in the liver, suggesting this may be one pathway used to protect against oxidative stress. Our results highlight the need for caution when interpreting correlative relationships and suggest that oxidative stress does not increase with enhanced reproductive effort during lactation.
Glossossoma nigrior (Trichoptera: Glossosomatidae) respiration in moving fluid
Authors: Morris Mark W. L. , Hondzo Miki 
Published: April 2013

Summary
Laboratory measurements of dissolved oxygen (DO) uptake by Glossosoma nigrior (Banks) were conducted in a sealed, recirculating flume under variable fluid flow velocities. Measurements were performed in similar water temperatures, DO concentrations, and fluid flow velocities as field conditions in the stream where the larvae were obtained. Total oxygen uptake by both cased larvae and corresponding cases without larvae were quantified. An increased fluid flow velocity corresponded to an increased larval DO uptake rate. Oxygen uptake by the larval cases alone was not as sensitive to changes in the Peclet (Pe) number, the dimensionless ratio of advective to diffusive DO transport, as uptake by larvae themselves. The flux of DO to larvae and their cases was up to seven times larger in a moving fluid in comparison to non-moving fluid conditions in the proximity of larvae for 0 &lt; Pe &lt; 175. A functional relationship was developed relating fluid flow and DO uptake across a larval case. According to the proposed quantitative relationship, Pe alone describes 91% of the variation in the DO flux to the larvae under variable fluid flow conditions. In response to fluid motion, larvae depicted two characteristic behavioral responses. When the ratio of advective DO transport to diffusive transport was low (Pe &lt; 87), larvae occasionally abandoned their cases or spent more time partially extended from their cases. At Pe &gt; 87, larvae typically remained in their cases. This indicates that oxygen delivery to the larvae at low Pe is insufficient to satisfy the respiratory demands of cased larvae.
Artificial activation of mature unfertilized eggs in the malaria vector mosquito, Anopheles stephensi (Diptera, Culicidae)
Authors: Yamamoto Daisuke S. , Hatakeyama Masatsugu , Matsuoka Hiroyuki 
Published: April 2013

Summary
In the past decade, many transgenic lines of mosquitoes have been generated and analyzed, whereas the maintenance of a large number of transgenic lines requires a great deal of effort and cost. In vitro fertilization by an injection of cryopreserved sperm into eggs has been proven to be effective for the maintenance of strains in mammals. The technique of artificial egg activation is a prerequisite for the establishment of in vitro fertilization by sperm injection. We demonstrated that artificial egg activation is feasible in the malaria vector mosquito, Anopheles stephensi (Diptera, Culicidae). Nearly 100% of eggs dissected from virgin females immersed in distilled water darkened, similar to normally oviposited fertilized eggs. It was revealed by the cytological examination of chromosomes that meiotic arrest was relieved in these eggs about 20 min after incubation in water. Biochemical examinations revealed that MAPK (mitogen-activated protein kinase)/ERK (extracellular signal-regulated protein kinase) and MEK (MAPK/ERK kinase) were dephosphorylated similar to that in fertilized eggs. These results indicate that dissected unfertilized eggs were activated in distilled water and started development. Injection of distilled water into body cavity of the virgin blood-fed females also induced activation of a portion of eggs in the ovaries. The technique of artificial egg activation is expected to contribute to the success of in vitro fertilization in A. stephensi.
Environmental response and adaptation of glycoprotein glue within the droplets of viscous prey capture threads from araneoid spider orb-webs
Authors: Opell Brent D. , Karinshak Shannon E. , Sigler Mary A. 
Published: April 2013

Summary
Viscous threads that form the prey capture spiral of araneoid orb-web retain insects that strike the web, giving a spider more time to locate and subdue them. The viscoelastic glycoprotein glue responsible for this adhesion forms the core of regularly spaced aqueous droplets, which are supported by protein axial fibers. Glycoprotein extensibility both facilitates the recruitment of adhesion from multiple droplets and dissipates the energy generated by insects struggling to free themselves from the web. Compounds in the aqueous material make droplets hygroscopic, causing both an increase in droplet volume and extensibility as humidity (RH) rises. We characterized these humidity-mediated responses at 20%, 37%, 55%, 72%, and 90% RH in two large orb-weavers, Argiope aurantia, which is found in exposed habitats, and Neoscona crucifera, which occupies forests and forest edges. The volume-specific extension of A. aurantia glycoprotein reached a maximum value at 55% RH and then declined, whereas that of N. crucifera increased exponentially through the RH range. As RH increased, the relative stress on droplet filaments at maximum extension, as gauged by axial line deflection, decreased in a linear fashion in A. aurantia, but in N. crucifer increased logarithmically, indicating that N. crucifera threads are better equipped to dissipate energy through droplet elongation. The greater hygroscopicity of A. aurantia threads equips them to function in lower RH environments and during the afternoon when RH drops, but their performance is diminished during the high RH of the morning hours. In contrast, the lower hygroscopicity of N. crucifera threads optimizes their performance for intermediate and high RH environments and during the nigh and morning. These interspecific differences support the hypothesis that viscous capture threads are adapted to the humidity regime of an orb-weaver's habitat.
Visual search in hunting archerfish shares all hallmarks of human performance
Authors: Rischawy Ingo , Schuster Stefan 
Published: April 2013

Summary
Archerfish are renowned for shooting down aerial prey with water jets, but nothing is known about the ways they spot prey items in their richly structured mangrove habitats. We trained archerfish to stably assign the categories 'target' and 'background' to objects solely on the basis of non-motion cues. Unlike many other hunters archerfish are able to discriminate a target from its background in the complete absence of either self-motion or relative motion parallax cues and without using stored information about the structure of the background. This allowed us to perform matched tests to compare the ways fish and humans scan stationary visual scenes. In humans, visual search is seen as a doorway to cortical mechanisms of how attention is allocated. Fish lack a cortex and we therefore wondered if archerfish would differ from humans in their ways they scan a stationary visual scene. Our matched tests failed to disclose any differences in the dependence of response time distributions, a most sensitive indicator of the search mechanism, on number and complexity of background objects. Median and range of response times depended linearly on the number of background objects and the corresponding effective processing time per item increased similarly - about fourfold - in both humans and fish when the task was harder. Archerfish, like humans, also systematically scanned the scenery, starting with the closest object. Taken together, benchmark visual search tasks failed to disclose any difference between archerfish - who lack a cortex - and humans.
Redetermination of the structure of 3-methyl-1,5-diphenyl-4,5-dihydro- 1H-pyrazole, C16H16N2
Authors: Samshuddin Seranthimata , Narayana Badiadka , Yathirajan Hemmige S. , Gerber Thomas , Hosten Eric , Betz Richard 
Published: April 2013

Abstract C16H16N2, triclinic, P1̅ (no. 2), a = 6.2920(1) Å, b = 8.2151(2) Å, c = 12.4139(2) Å, α = 88.547(1)°, β = 81.649(1)°, γ = 89.546(1)°, V = 634.7 Å3, Z = 2, Rgt(F) = 0.0398, wRref(F2) = 0.1101, T = 200 K.
Predicting Growth and Decay of Hydraulic-Fracture Width in Porous Media Subjected to Isothermal and Nonisothermal Flow
Authors: Tran David , Settari A. (Tony) , Nghiem Long 
Published: April 2013

SummaryOn the basis of the continuum thermo-poroelastic theory, a new analytical formula of fracture width is developed to quickly predict its transient growth or decay. The effects of the poroelastic stress (also called back stress) and thermal stress are taken into account. The counterbalance between the effects of back stress and thermal stress (in case of injection of cold fluid) is shown to be a function of flow and thermal properties and can be easily demonstrated by the formula developed. The analytical formula of fracture width is not complicated and does not require complex calculations. Different phenomena affecting the magnitude of fracture width are easily examined, such as the presence or absence of leakoff, isothermal or nonisothermal fracturing, and initial effective stress in the formation. Results show that the fracture width continuously decays with time because of the effect of pore pressure when there is leakoff. On the other hand, the fracture width will grow with time by the influence of thermal stress when cold fluid is injected. Unlike cold fluid, when hot fluid is used, the crack may close completely and the speed of the process will depend on the temperature of the injected fluid. Formulae for penetration depths for pressure and temperature are also developed and applied to the crack-width equation so that time-dependent maximum width and crack profiles can be computed. The analytical solution has also been validated by the finite-element (FE) numerical method.
The Associated Effects of the Soybean Aphid Resistance Gene Rag2 from PI 200538 on Agronomic Traits in Soybean
Authors: Kim Ki‐Seung , Diers Brian W. 
Published: April 2013

ABSTRACTThe soybean aphid (SA) (Aphis glycines Matsumura) has become a major insect pest of soybean [Glycine max (L.) Merr.] in North America. Three SA biotypes and several genes conferring resistance to this pest have been discovered. The major SA resistance gene Rag2 was identified and mapped from the maturity group VIII PI 200538 and the gene has been introgressed into Midwest‐adapted germplasm. The objective of this study was to test whether Rag2 has unintended effects on seed yield and other agronomic traits in elite midwestern U.S. adapted soybean backgrounds. Homozygous resistant (Rag2) and susceptible (rag2) backcross lines from two backgrounds were tested in multiple environments under conditions with nondetectable SA infestations. Across environments, the Rag2 locus had no significant (P = 0.05) associated effects on seed yield, maturity, plant height, and lodging score in the first background. In the second background, a significant effect was observed across environments for yield, with those lines homozygous for the Rag2 resistance allele averaging 256 kg ha–1 less yield than lines homozygous for the susceptible allele. The inconsistency of effects observed in the two populations may be the result of differences in the size of the introgressed region in the two populations or the result of background effects. These results show the importance of considering the associated effects of Rag2 when this gene is bred into elite genetic backgrounds.
Partitioning Soil Respiration during Pasture Regrowth
Authors: Skinner R. Howard 
Published: April 2013

ABSTRACTUnderstanding the regulation of net ecosystem exchange and soil C sequestration within pasture systems requires knowledge of its component fluxes, including photosynthetic uptake and respiratory loss. However, little information is available on the partitioning of soil respiration (RS) between its heterotrophic respiration (RH) and rhizosphere respiration (RR) components for perennial cool‐season pasture species. The purpose of this study was to use stable C isotopes to examine the effects of regrowth after defoliation on the components of soil respiration for grassland plots planted as an orchardgrass (Dactylis glomerata L.)–white clover (Trifolium repens L.) mixture but dominated by orchardgrass (90 to 100% of harvested biomass). Respiration components were quantified during the first 3 wk following defoliation at the beginning of July in 2010 and 2011. In 2010, RS, RH, and RR were all lowest 1 d after cutting (DAC). Both RS and RH significantly increased by 8 DAC but no further increase occurred over the next 2 wk. In contrast, RR continued to increase throughout the regrowth period. In 2011, RS did not differ among harvests and averaged across dates was less than in 2010. During the 2011 regrowth period RH increased slightly whereas RR did not change significantly. The rhizosphere contribution (RC) to RS averaged 0.49, increasing from 0.35 to 0.56 during regrowth in 2010 but decreasing from 0.62 to 0.43 in 2011. Differences among years in respiration responses during regrowth were possibly due to a combination of factors including resource limitations, soil moisture stress, and differences in soil temperature.
Analysis of Quantitative Traits in Two Long‐Term Randomly Mated Soybean Populations: I. Genetic Variances
Authors: Recker Jill R. , Burton Joseph W. , Cardinal Andrea , Miranda Lilian 
Published: April 2013

ABSTRACTThe genetic effects of long‐term random mating and natural selection aided by genetic male sterility were evaluated in two soybean [Glycine max (L.) Merr.] populations: RSII and RSIII. Population means, variances, and heritabilities were estimated to determine the effects of 26 generations of random mating. The 10% highest yielding lines from each population were selected. Data was collected on flowering date, maturity date, plant height, lodging score, seed yield, seed weight, protein concentration (PC), and oil concentration (OC). RSII had a mean seed yield, PC, and OC of 2163 kg ha−1, 416 g kg−1, and 193 g kg−1, respectively. Entry‐mean heritability for seed yield, PC, and OC was estimated at 36, 68, and 57%, respectively. Theoretical response to selection was 183 kg ha−1 and, after selection, the realized gain was 161 kg ha−1. RSIII had a mean seed yield, PC, and OC of 2300 kg ha−1, 416 g kg−1, and 190 g kg−1, respectively. The entry‐mean heritability estimates for seed yield, PC, and OC were 57, 87, and 91%, respectively. Theoretical response to selection was 300 kg ha−1 and, after selection, realized gain was an increase of 139 kg ha−1. Despite not reaching their theoretical yield potential, the best lines from both populations compared well to check cultivars. The significant genetic variances and heritabilities observed demonstrate that the breakage of linkage blocks by long‐term random mating and natural selection were effective in producing competitive lines.
Nitrate Leaching from Two Kentucky Bluegrass Cultivars as Affected by Nitrate Uptake Capacity and Subsurface Soil Compaction
Authors: Zhang Chenxi , Miller Grady L. , Rufty Thomas W. , Bowman Daniel C. 
Published: April 2013

ABSTRACTThere are a number of strategies to minimize NO3– leaching from turfgrass, including planting turfgrass cultivars with higher NO3– absorption abilities. This column lysimeter study was conducted to examine NO3– leaching from two Kentucky bluegrass (Poa pratensis L.) cultivars differing in NO3– uptake capacity. Subsurface soil compaction was included as a second factor. Tillers of Julia and Midnight Kentucky bluegrass, previously identified as having high and low NO3– uptake capacity, respectively, were grown in column lysimeters. Each column was filled with Wagram loamy sand with or without a subsurface compaction layer 8.5 cm below the surface. The two cultivars were established and then treated to impose moderate N deficiency. Potassium nitrate was applied in solution at 49 kg N ha–1 followed by daily heavy irrigation. Leachate was collected and analyzed for NO3–‐N. Cumulative N leaching loss of applied N ranged from 2.6 to 19% and 2.8 to 21% for Julia and Midnight, respectively. In two out of three trials, both cultivars absorbed NO3– very efficiently in noncompacted soil, with only trace amounts of NO3– leaching. While NO3–‐N loss averaged 4.7% of applied N in noncompacted soil across all trials, subsurface soil compaction increased that to 8.9%. Results indicated that despite being identified as more efficient for NO3– uptake, NO3– leaching from Julia was generally similar to that from Midnight. Soil conditions and differences in root morphology and/or architecture may played a more important role than root uptake capacity in determining NO3– leaching from these Kentucky bluegrass genotypes.
An Introgressed Nicotiana rustica Genomic Region Confers Resistance to Phytophthora nicotianae in Cultivated Tobacco
Authors: Drake Katherine , Lewis Ramsey S. 
Published: April 2013

ABSTRACTBlack shank, caused by the pathogen Phytophthora nicotianae, is an important disease affecting tobacco (Nicotiana tabacum L.) production in many parts of the world. Host resistance offers an efficient means of reducing economic loss due to this pathogen. Previous observations suggested that a genomic region introgressed from Nicotiana rustica L. may affect resistance to black shank. The effect of this genomic region, designated as Wz, on resistance to multiple races of P. nicotianae had not previously been investigated in a systematic way, however. We used growth chamber and field experiments to evaluate resistance of a doubled haploid (DH) mapping population segregating for the Wz region. We also genotyped the population with amplified fragment length polymorphism (AFLP) markers found to be polymorphic between the parental lines. In addition, we determined resistance and marker genotypes for individuals of a larger BC1F1 population segregating for Wz. A set of 29 AFLP markers determined to be of N. rustica origin were found to cosegregate with each other and were associated with resistance to both race 0 and race 1 of P. nicotianae in the DH population. A selected subset of these markers was also found to cosegregate with resistance in the BC1F1 population. Consistent with other introgressed alien genomic regions in N. tabacum, no recombination was observed between these selected markers. The N. rustica‐derived genetic variation and associated DNA markers will be of value for breeding for black shank resistance in tobacco.