909 research outputs found
Eastern Black Nightshade
The nightshade species of North America consist of black nightshade (Solanum nigrum L.), American black nightshade (Solanum americanum Mill.), hairy nightshade (Solanum surrachoides Sendt.) and eastern black nightshade (Solanum ptycanthum Dun.). Eastern black nightshade is a problem weed in many soybean producing areas and is the predominant problem nightshade in Kentucky. In addition to field crops, the nightshades are also problem weeds in canning peas (Pisum sativum L.), field beans (Phaseolus vulgaris L.), potatoes (Solanum tuberosum L.) and tomatoes (Lycopersicon esculentum Mill.). Previously, most nightshades in Kentucky have been referred to as black nightshade. It is now known that black nightshade occurs in the U.S. only in the western states, while eastern black. nightshade is commonly found in many states east of the Rocky Mountains. These species are similar in their gross morphology and are easily confused with each other. When grown under different environmental conditions, the nightshades may vary considerably in many taxonomic characteristics frequently used for identification and make identification more difficult (Ogg, A.G., B.p. Rogers and E.S. Schilling, 1981)
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Vector Finite Element Modeling of the Full-Wave Maxwell Equations to Evaluate Power Loss in Bent Optical Fibers
We measure the loss of power incurred by the bending of a single mode step-indexed optical fiber using vector finite element modeling of the full-wave Maxwell equations in the optical regime. We demonstrate fewer grid elements can be used to model light transmission in longer fiber lengths by using high-order basis functions in conjunction with a high order energy conserving time integration method. The power in the core is measured at several points to determine the percentage loss. We also demonstrate the effect of bending on the light polarization
Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products
We developed a low-cost, high-throughput microbiome profiling method that
uses combinatorial sequence tags attached to PCR primers that amplify the rRNA
V6 region. Amplified PCR products are sequenced using an Illumina paired-end
protocol to generate millions of overlapping reads. Combinatorial sequence
tagging can be used to examine hundreds of samples with far fewer primers than
is required when sequence tags are incorporated at only a single end. The
number of reads generated permitted saturating or near-saturating analysis of
samples of the vaginal microbiome. The large number of reads al- lowed an
in-depth analysis of errors, and we found that PCR-induced errors composed the
vast majority of non-organism derived species variants, an ob- servation that
has significant implications for sequence clustering of similar high-throughput
data. We show that the short reads are sufficient to assign organisms to the
genus or species level in most cases. We suggest that this method will be
useful for the deep sequencing of any short nucleotide region that is
taxonomically informative; these include the V3, V5 regions of the bac- terial
16S rRNA genes and the eukaryotic V9 region that is gaining popularity for
sampling protist diversity.Comment: 28 pages, 13 figure
Cytotoxic polyfunctionality maturation of cytomegalovirus-pp65-specific CD4 + and CD8 + T-cell responses in older adults positively correlates with response size
Cytomegalovirus (CMV) infection is one of the most common persistent viral infections in humans worldwide and is epidemiologically associated with many adverse health consequences during aging. Previous studies yielded conflicting results regarding whether large, CMV-specific T-cell expansions maintain their function during human aging. In the current study, we examined the in vitro CMV-pp65-reactive T-cell response by comprehensively studying five effector functions (i.e., interleukin-2, tumor necrosis factor-Ξ±, interferon-Ξ³, perforin, and CD107a expression) in 76 seropositive individuals aged 70 years or older. Two data-driven, polyfunctionality panels (IL-2-associated and cytotoxicity-associated) derived from effector function co-expression patterns were used to analyze the results. We found that, CMV-pp65-reactive CD8β+βand CD4β+βT cells contained similar polyfunctional subsets, and the level of polyfunctionality was related to the size of antigen-specific response. In both CD8β+βand CD4β+βcells, polyfunctional cells with high cytotoxic potential accounted for a larger proportion of the total response as the total response size increased. Notably, a higher serum CMV-IgG level was positively associated with a larger T-cell response size and a higher level of cytotoxic polyfunctionality. These findings indicate that CMV-pp65-specific CD4β+βand CD8β+βT cell undergo simultaneous cytotoxic polyfunctionality maturation during aging
Genetic influences on externalizing psychopathology overlap with cognitive functioning and show developmental variation
Background: Questions remain regarding whether genetic influences on early life psychopathology overlap with cognition and show developmental variation.
Methods: Using data from 9,421 individuals aged 8-21 from the Philadelphia Neurodevelopmental Cohort, factors of psychopathology were generated using a bifactor model of item-level data from a psychiatric interview. Five orthogonal factors were generated: anxious-misery (mood and anxiety), externalizing (attention deficit hyperactivity and conduct disorder), fear (phobias), psychosis-spectrum, and a general factor. Genetic analyses were conducted on a subsample of 4,662 individuals of European American ancestry. A genetic relatedness matrix was used to estimate heritability of these factors, and genetic correlations with executive function, episodic memory, complex reasoning, social cognition, motor speed, and general cognitive ability. Gene Γ Age analyses determined whether genetic influences on these factors show developmental variation.
Results: Externalizing was heritable (h2 = 0.46, p = 1 Γ 10-6), but not anxious-misery (h2 = 0.09, p = 0.183), fear (h2 = 0.04, p = 0.337), psychosis-spectrum (h2 = 0.00, p = 0.494), or general psychopathology (h2 = 0.21, p = 0.040). Externalizing showed genetic overlap with face memory (Οg = -0.412, p = 0.004), verbal reasoning (Οg = -0.485, p = 0.001), spatial reasoning (Οg = -0.426, p = 0.010), motor speed (Οg = 0.659, p = 1x10-4), verbal knowledge (Οg = -0.314, p = 0.002), and general cognitive ability (g)(Οg = -0.394, p = 0.002). Gene Γ Age analyses revealed decreasing genetic variance (Ξ³g = -0.146, p = 0.004) and increasing environmental variance (Ξ³e = 0.059, p = 0.009) on externalizing.
Conclusions: Cognitive impairment may be a useful endophenotype of externalizing psychopathology and, therefore, help elucidate its pathophysiological underpinnings. Decreasing genetic variance suggests that gene discovery efforts may be more fruitful in children than adolescents or young adults
Selective Constraints on Amino Acids Estimated by a Mechanistic Codon Substitution Model with Multiple Nucleotide Changes
Empirical substitution matrices represent the average tendencies of
substitutions over various protein families by sacrificing gene-level
resolution. We develop a codon-based model, in which mutational tendencies of
codon, a genetic code, and the strength of selective constraints against amino
acid replacements can be tailored to a given gene. First, selective constraints
averaged over proteins are estimated by maximizing the likelihood of each 1-PAM
matrix of empirical amino acid (JTT, WAG, and LG) and codon (KHG) substitution
matrices. Then, selective constraints specific to given proteins are
approximated as a linear function of those estimated from the empirical
substitution matrices.
Akaike information criterion (AIC) values indicate that a model allowing
multiple nucleotide changes fits the empirical substitution matrices
significantly better. Also, the ML estimates of transition-transversion bias
obtained from these empirical matrices are not so large as previously
estimated. The selective constraints are characteristic of proteins rather than
species. However, their relative strengths among amino acid pairs can be
approximated not to depend very much on protein families but amino acid pairs,
because the present model, in which selective constraints are approximated to
be a linear function of those estimated from the JTT/WAG/LG/KHG matrices, can
provide a good fit to other empirical substitution matrices including cpREV for
chloroplast proteins and mtREV for vertebrate mitochondrial proteins.
The present codon-based model with the ML estimates of selective constraints
and with adjustable mutation rates of nucleotide would be useful as a simple
substitution model in ML and Bayesian inferences of molecular phylogenetic
trees, and enables us to obtain biologically meaningful information at both
nucleotide and amino acid levels from codon and protein sequences.Comment: Table 9 in this article includes corrections for errata in the Table
9 published in 10.1371/journal.pone.0017244. Supporting information is
attached at the end of the article, and a computer-readable dataset of the ML
estimates of selective constraints is available from
10.1371/journal.pone.001724
Effects of 192 IgG-saporin on acetylcholinesterase histochemistry in male and female rats
Sex hormones may exert neuroprotective effects in various models of brain lesions. Male and female Long-Evans rats were subjected to intracerebroventricular injections of 2 microg 192 IgG-saporin or vehicle. Starting 2 days before surgery, half the male rats were treated with estradiol for 7 days. Three weeks after surgery, they were sacrificed for histochemical staining of acetylcholinesterase (AChE) and densitometric evaluations. The lesion induced a substantial to dramatic decrease of the AChE-positive fiber density in the cingulate, somatosensory, piriform, retrosplenial and perirhinal cortices, and in the hippocampus. Weak effects were found in the striatum. There was no significant decrease in the dorsal thalamus. Sex had no significant effect on AChE-positive staining in any brain area. In males, estradiol treatment did not alter the effects of 192 IgG-saporin. These results show that sex or estradiol treatment in male rats does not interfere with the immunotoxic effects of intracerebroventricular injections of 192 IgG-saporin on cholinergic projections from the basal forebrain
Effects of MDL 73005 on water-maze performances and locomotor activity in scopolamine-treated rats
The stimulation of 5-HT1A receptors in the raphe or their blockade in the hippocampus can reduce cognitive deficits induced by blockade of muscarinic receptors in the hippocampus. We investigated the effects of MDL 73005 (8-[2-(2,3-dihydro-1,4-benzodioxin-2-ylmethylamino) ethyl]-8-azaspiro[4,5] decane-7,9-dione methyl sulphonate), an agonist at 5-HT1A somatodendritic autoreceptors and an antagonist at postsynaptic 5-HT1A receptors in rats treated systemically with scopolamine. Spatial memory was assessed in a water maze using protocols testing reference and working memory. Home cage locomotor activity was also determined. Working memory and locomotor activity were evaluated before and after para-chlorophenylalanine (pCPA) treatment. Scopolamine produced a weak impairment of reference memory at 0.5 mg/kg, and a more pronounced impairment of working memory at 0.25 and 0.5 mg/kg. MDL 73005 alone (2 mg/kg, i.p.) had no effect, but prevented the memory impairments induced by 0.25 mg/kg of scopolamine. Scopolamine induced hyperlocomotion. MDL 73005 alone did not affect locomotor activity, but exacerbated the hyperlocomotion induced by 0.5 mg/kg of scopolamine. pCPA did not abolish the effects of MDL 73005, suggesting that these effects were not due to an action at presynaptic receptors, or even that they involved receptors other than serotonergic ones (e.g., D2). In conclusion, MDL 73005 is able to antagonise moderate spatial memory dysfunctions induced by systemic muscarinic blockade
Age-related changes in global motion coherence: conflicting haemodynamic and perceptual responses
Our aim was to use both behavioural and neuroimaging data to identify indicators of perceptual decline in motion processing. We employed a global motion coherence task and functional Near Infrared Spectroscopy (fNIRS). Healthy adults (nβ=β72, 18-85) were recruited into the following groups: young (nβ=β28, mean ageβ=β28), middle-aged (nβ=β22, mean ageβ=β50), and older adults (nβ=β23, mean ageβ=β70). Participants were assessed on their motion coherence thresholds at 3 different speeds using a psychophysical design. As expected, we report age group differences in motion processing as demonstrated by higher motion coherence thresholds in older adults. Crucially, we add correlational data showing that global motion perception declines linearly as a function of age. The associated fNIRS recordings provide a clear physiological correlate of global motion perception. The crux of this study lies in the robust linear correlation between age and haemodynamic response for both measures of oxygenation. We hypothesise that there is an increase in neural recruitment, necessitating an increase in metabolic need and blood flow, which presents as a higher oxygenated haemoglobin response. We report age-related changes in motion perception with poorer behavioural performance (high motion coherence thresholds) associated with an increased haemodynamic response
Intraseptal injection of the 5-HT1A/5-HT7 agonist 8-OH-DPAT and working memory in rats
RATIONALE:
In rats, 5-HT(1A) receptors are present in the septal region, e.g. on cholinergic neurons of the medial septum, where they might be a substrate for cognitively relevant interactions between cholinergic and serotonergic systems.
OBJECTIVE:
The present experiment assessed the effects of the stimulation of septal 5-HT(1A) receptors on spatial working memory.
METHODS:
Stimulation of septal 5-HT(1A) receptors was carried out by infusions targetting the medial septum of the 5-HT(1A)/5-HT(7) receptor agonist 8-hydroxy-2-(di-n-propyl-amino)-tetralin (8-OH-DPAT; 0.5 or 4 microg). Spatial memory was assessed in a water maze using a protocol placing emphasis on spatial working memory. The location of the hidden platform was changed every day and performance was assessed on two consecutive trials each day.
RESULTS:
In comparison to vehicle injections, the intraseptal infusion of 4 microg 8-OH-DPAT impaired performance significantly: rats treated with 8-OH-DPAT exhibited increased distances to reach the hidden platform on both trials 1 and 2. Rats infused with 0.5 microg showed similar changes that failed to be significant. Such effects were not observed when the platform was visible.
CONCLUSIONS:
These results extend those of a previous experiment which showed that intraseptal injections of 8-OH-DPAT impaired spatial reference memory. Based on the characteristics of the observed deficits, it is suggested that the 8-OH-DPAT-induced impairment, rather than being only the result of a true alteration of working memory, might reflect a more global cognitive deficiency in which alteration of general memory capacities may be biased by disrupted search strategies/exploration and/or dysfunctions of attention
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