Does Physical Contact with a Dog or Person Affect Performance of a Working Memory Task?

ABSTRACT

Working memory (WM) plays a critical role in the execution of a wide variety of cognitive tasks and predicts academic success. This study was designed to compare the impact of the presence of a dog or a person, and physical contact with them, on the performance of a WM task. It also exam- ined whether the impact differed for two dogs, and whether these factors im- pacted arousal during the WM task. College students (n=31, aged 18–23 years) performed a WM task in five counterbalanced conditions; dog-touch, dog-no-touch, person-touch, person-no-touch, and alone. Participants were randomly assigned to one of two dogs; Miniature Poodle (n=16) or Border Collie (n=15). The WM task involved replicating increasingly complicated se- quences of colored lights by touching them on an iPad^®. Linear mixed model analyses revealed there was a significant interaction between collaborator and touch (p=0.05); best WM scores occurred without touch with either the per- son or the dog present, and worst WM scores occurred when the participant was touching a dog. Analyzing WM test during the dog conditions, touch (p=0.027) and dog breed (p=0.042) contributed independently to it; task completion was worse when the poodle was present and better without touch. Physiological measures [heart rate (HR) and heart rate variability] during the ex- periment indicated that the WM task was physiologically arousing (p<0.001) compared with listening, and HR was higher when touching a person than a dog during the task (p<0.046). These results are consistent with facilitation of performance by the presence of an observer. If there is a beneficial effect on cognition from a dog, physical contact with the dog might not be a necessary component. Aspects of the dog (e.g., breed) are also likely factors in WM task performance. This study highlights the importance of situational characteristics in studies evaluating the impact of companion animals.     

A nitrogen fertilization field study of carbon-13 and nitrogen-15 transfers in ectomycorrhizas of Pinus sabiniana

Ectomycorrhizal (EM) fungi form relationships with higher plants; plants transfer C to fungi, and fungi transfer nutrients to their host. While evidence indicates that this interaction is largely mutualistic, less is known about how nutrient supply and EM associates may alter C and nutrient exchanges, especially in intact plant-soil-microbe systems in the field. In a dual-labeling experiment with N fertilization, we used C and N stable isotopes to examine in situ transfers in EM pine trees in a Pinus sabiniana woodland in northern California. We added ¹⁵NH₄SO₂ and ¹³CO₂ to track ¹³C transfer from pine needles to EM roots and ¹⁵N transfer from soil to EM roots and pine needles. Transfers of ¹³C and ¹⁵N differed with EM morphotype and with N fertilization. The brown morphotype received the least C per unit of N transferred (5:1); in contrast red and gold morphotypes gained more C and transferred less N (17:1 and 25:1, respectively). N fertilization increased N retention by ectomycorrhizas (EMs) but did not increase N transfer from EMs to pine needles. Therefore N fertilization positively affected both nutrient and C gains by EMs, increasing net C flows and N retention in EMs. Our work on intact and native trees/EM associations thereby extends earlier conclusions based on pot studies with young plants and culturable EM fungi; our results support the concept that EM-host relationships depend on species-level differences as well as responses to soil resources such as N.     

Salt leaching leads to drier soils in disturbed semiarid woodlands of central Argentina

Disturbances in semiarid environments have revealed a strong connection between water, salt and vegetation dynamics highlighting how the alteration of water fluxes can drive salt redistribution process and long-term environmental degradation. Here, we explore to what extent the reciprocal effect, that of salt redistribution on water fluxes, may play a role in dictating environmental changes following disturbance in dry woodlands. We assessed salt and water dynamics comparing soil-solution electrical conductivity, chloride concentration, soil water content (SWC) and soil matric and osmotic water potential (Ψ_m, Ψ_os) between disturbed and undisturbed areas. A large pool of salts and chlorides present in undisturbed areas was absent in disturbed plots, suggesting deep leaching. Unexpectedly, this was associated with slight but consistently lower SWC in disturbed versus undisturbed situations during two growing seasons. The apparent paradox of increased leaching but diminishing SWC after disturbance can be explained by the effect of native salt lowering Ψ_os enough to prevent full soil drying. Under disturbed conditions, the onset of deep drainage and salt leaching would raise Ψ_os allowing a decline of Ψ_m and SWC. Soil water storage seems to be modulated by the presence (under natural conditions) and partial leaching (following selective shrub disturbance) of large salt pools. This counterintuitive effect of disturbances may be important in semiarid regions where deep soil salt accumulation is a common feature. Our results highlight the importance of water–salt–vegetation coupling for the understanding and management of these systems.     

Morphometric and molecular variation in concert: taxonomy and genetics of the reticulate Pyrenean and Iberian alpine spiny fescues (Festuca eskia complex,Poaceae)

The Iberian mountain spiny fescues are a reticulate group of five diploid grass taxa consisting of three parental species and two putative hybrids: F. × souliei (F. eskia × F. quadriflora) and F. × picoeuropeana (F. eskia × F. gautieri). Phenotypic and molecular studies were conducted with the aim of determining the taxonomic boundaries and genetic relationships of the five taxa and disentangling the origins of the two hybrids. Statistical analyses of 31 selected phenotypic traits were conducted on individuals from 159 populations and on nine type specimens. Molecular analyses of random amplified polymorphic DNA (RAPD) markers were performed on 29 populations. The phenotypic analyses detected significant differences between the five taxa and demonstrated the overall intermediacy of the F. × picoeuropeana and F. × souliei between their respective parents. The RAPD analysis corroborated the genetic differentiation of F. eskia, F. gautieri and F. quadriflora and the intermediate nature of the two hybrids; however, they also detected genetic variation within F. × picoeuropeana. These results suggest distinct origins for F. × picoeuropeana in the Cantabrian and Pyrenean mountains, with the sporadic Pyrenean populations having potentially resulted from recent hybridizations and the stabilized Cantabrian ones from older events followed by potential displacements of the parents. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 676–706.     

Human Dietary Exposure to Uranium in Catalonia, Spain

The purpose of this study was to determine the daily dietary intake of uranium (U) by the general population of Catalonia, Spain. Uranium concentrations were measured in foods widely consumed by the population living in that autonomous community. Food samples were randomly acquired in 12 representative cities of Catalonia. The dietary intake of U was estimated for various age–gender groups: children, adolescents, adults, and seniors. Fish and seafood was the food group showing the highest U concentrations (0.090 μg/g of fresh weight (fw)), followed by dairy products (0.044 μg/g fw). In contrast, the lowest U levels were found in oils and fats (0.003 μg/g fw), while in tubers and milk, U was not detected in any sample. The estimated dietary intake of U for a standard male adult of 70 kg body weight living in Catalonia was 15.48 μg/day. According to the age/gender of the population, the highest dietary intake of U corresponded to children (20.32 μg/day), while senior females was the subgroup with the lowest U intake (10.04 μg/day). Based on the tolerable daily intake established for U, the current dietary intake of this metal by the general population of Catalonia should not mean health risks for any of the different age/gender groups of consumers.     

Culex pipiens affected by joint infection of a mosquito iridescent virus and Strelkovimermis spiculatus

Dual infections with a mosquito iridescent virus (MIV) and the mermithid nematode, Strelkovimermis spiculatus were recorded in natural Culex pipiens populations around La Plata city, Argentina. S. spiculatus was detected in 82% of samples that were positive for MIV infection. Dissected larvae of Cx. pipiens with patent MIV infection presented 42% infection with S. spiculatus. Larvae of Cx. pipiens exposed to MIV and S. spiculatus under laboratory conditions produced a high joint infection rate (82.5%) while no infection was recorded on larvae exposed to virus suspension only. Field and laboratory results suggest a strong association between S. spiculatus and MIV in natural populations of Cx. pipiens, in which S. spiculatus could be a mode of entry for the virus into the mosquito hemocele.     

Synthesis and acetylcholinesterase inhibitory activity of polyhydroxylated sulfated steroids: Structure/activity studies

Disulfated and trisulfated steroids have been synthesized from cholesterol and their acetylcholinesterase inhibitory activity has been evaluated. In our studies we have found that the activity was not only dependent on the location of the sulfate groups but on their configurations. 2β,3α,6α-trihydroxy-5α-cholestan-6-one trisulfate (18) was the most active steroid with an IC₅₀ value of 15.48 μM comparable to that of 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (1). Both compounds were found to be less active than the reference compound eserine. The butyrylcholinesterase activity of 1 and 18 was one magnitude lower than that against acetylcholinesterase revealing a selective inhibitor profile.     

Structural and biochemical characterization of Rv2140c,a phosphatidylethanolamine-binding protein from Mycobacterium tuberculosis

Rv2140c is one of many conserved Mycobacterium tuberculosis proteins for which no molecular function has been identified. We have determined a high-resolution crystal structure of the Rv2140c gene product, which reveals a dimeric complex that shares strong structural homology with the phosphatidylethanolamine-binding family of proteins. Rv2140c forms low-millimolar interactions with a selection of soluble phosphatidylethanolamine analogs, indicating that it has a role in lipid metabolism. Furthermore, the small molecule locostatin binds to the Rv2140c ligand-binding site and also inhibits the growth of the model organism Mycobacterium smegmatis.     

LOV‐domain photoreceptor,encoded in a genomic island,attenuates the virulence of Pseudomonas syringae in light‐exposed Arabidopsis leaves

In Arabidopsis thaliana, light signals modulate the defences against bacteria. Here we show that light perceived by the LOV domain‐regulated two‐component system (Pst–Lov) of Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) modulates virulence against A. thaliana. Bioinformatic analysis and the existence of an episomal circular intermediate indicate that the locus encoding Pst–Lov is present in an active genomic island acquired by horizontal transfer. Strains mutated at Pst–Lov showed enhanced growth on minimal medium and in leaves of A. thaliana exposed to light, but not in leaves incubated in darkness or buried in the soil. Pst–Lov repressed the expression of principal and alternative sigma factor genes and their downstream targets linked to bacterial growth, virulence and quorum sensing, in a strictly light‐dependent manner. We propose that the function of Pst–Lov is to distinguish between soil (dark) and leaf (light) environments, attenuating the damage caused to host tissues while releasing growth out of the host. Therefore, in addition to its direct actions via photosynthesis and plant sensory receptors, light may affect plants indirectly via the sensory receptors of bacterial pathogens.