879 research outputs found
Effects of riparian plant diversity loss on aquatic microbial decomposers become more pronounced at longer times
We examined the potential long-term impacts of riparian plant diversity loss on diversity and activity of aquatic microbial decomposers. Microbial assemblages were obtained
in a mixed-forest stream by immersion of mesh bags contain-ing three leaf species (alder, oak and eucalyptus), commonly
found in riparian corridors of Iberian streams. Simulation of
species loss was done in microcosms by including a set of all
leaf species, retrieved from the stream, and non-colonized
leaves of three, two or one leaf species. Leaves were renewed
every month throughout six months, and microbial inoculum
was ensured by a set of colonized leaves from the previous
month. Microbial diversity, leaf mass loss and fungal biomass
were assessed at the second and sixth months after plant
species loss. Molecular diversity of fungi and bacteria, as the
total number of operational taxonomic units per leaf diversity
treatment, decreased with leaf diversity loss. Fungal biomass
tended to decrease linearly with leaf species loss on oak and
eucalyptus, suggesting more pronounced effects of leaf diver-sity on lower quality leaves. Decomposition of alder and
eucalyptus leaves was affected by leaf species identity, mainly
after longer times following diversity loss. Leaf decomposi-tion of alder decreased when mixed with eucalyptus, while
decomposition of eucalyptus decreased in mixtures with oak.
Results suggest that the effects of leaf diversity on microbial
decomposers depended on leaf species number and also on
which species were lost from the system, especially after
longer times. This may have implications for the management
of riparian forests to maintain stream ecosystem functioning.FEDER-POFC-COMPETE and the Portuguese
Foundation for Science and Technology supported this study (PEst-C/
BIA/UI4050/2011, PTDC/AAC-AMB/113746/2009 and PTDC/AAC-AMB/117068/2010), S. Duarte (SFRH/BPD/47574/2008) and I.
Fernandes (SFRH/BD/42215/2007)
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Urinary incontinence related to perineal muscle strength in the first trimester of pregnancy: cross-sectional study
Objective To analyze pelvic floor muscle strength (PFMS), urinary continence and quality of life related to urinary incontinence (UI) of women in the first trimester of pregnancy. Method Cross-sectional study with a sample of 500 women who started prenatal care in a complementary healthcare facility in Guarulhos, state of São Paulo, from 2012 and 2013. Pelvic floor muscle strength was evaluated through perineometry. The pregnant women who presented UI answered the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF). Results It was found that maternal age (OR=1.06; CI95% 1.02-1.11) and prior UI (OR=15.12; 95%CI 8.19-27.92) are the variables that, in tandem, best explain the occurrence of UI at the beginning of pregnancy. The mean score on the ICIQ-SF was 8.2 (SD=3.9), considered a moderate impact on quality of life. Conclusion Older pregnant women with prior UI are more likely to have UI in the first trimester of pregnancy.
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d-β-Tocotrienol-mediated cell cycle arrest and apoptosis in human melanoma cells
Background: The rate-limiting enzyme of the mevalonate pathway, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, provides essential intermediates for the prenylation or dolichylation of growth-related proteins. d-δ-Tocotrienol, a post-transcriptional downregulator of HMG CoA reductase, suppresses the proliferation of murine B16 melanoma cells. Dietary d-δ- tocotrienol suppresses the growth of implanted B16 melanomas without toxicity to host mice. Materials and Methods: The proliferation of human A2058 and A375 melanoma cells following a 72 h incubation in 96-well plates was measured by CellTiter 96® Aqueous One Solution. Cell cycle distribution was determined by flow cytometry. Fluorescence microscopy following acridine orange and ethidium bromide dual staining and procaspase-3 cleavage were used to detect apoptosis. Western-blot was employed to measure protein expression. Results: d-δ-Tocotrienol induced dose-dependent suppression of cell proliferation with 50% inhibitory concentrations (IC50) of 37.5±1.4 (A2058) and 22.3±1.8 (A375) μmol/l, respectively (data are reported as mean±standard deviation). d-δ-Tocotrienol-mediated cell cycle arrest at the G1 phase was accompanied by reduced expression of cyclin-dependent kinase 4. Concomitantly, d- δ-tocotrienol induced caspase-3 activation and apoptosis. The impact of d-δ-tocotrienol on A2058 cell proliferation was potentiated by lovastatin (IC50=3.1±0.5 μmol/l), a competitive inhibitor of HMG CoA reductase. Conclusion: d-δ-Tocotrienol may have potential application in melanoma chemoprevention and/or therapy
Relative influence of shredders and fungi on leaf litter decomposition along a river altitudinal gradient
We compared autumn decomposition rates of European alder leaves at four sites along the Lasset–Hers River system, southern France, to test whether changes in litter decomposition rates from upstream (1,300 m elevation) to downstream (690 m) could be attributed to temperature-driven differences in microbial growth, shredder activity, or composition of the shredder community. Alder leaves lost 75–87% of original mass in 57 days, of which 46–67% could be attributed to microbial metabolism and 8–29% to shredder activity, with no trend along the river. Mass loss rates in both fine-mesh (excluding shredders) and coarse-mesh (including shredders) bags were faster at warm, downstream sites (mean daily temperature 7–8°C) than upstream (mean 1–2°C), but the differ- ence disappeared when rates were expressed in heat units to remove the temperature effect. Mycelial biomass did not correlate with mass loss rates. Faster mass loss rates upstream, after temperature correction, evidently arise from more efficient shredding by Nemourid stoneflies than by the Leuctra-dominated assemblage downstream. The influence of water temperature on decomposition rate is therefore expressed both directly, through microbial metabolism, and indirectly, through the structure of shredder commu- nities. These influences are evident even in cold water where temperature variation is small
Predictors of physical activity and barriers to exercise in nursing and medical students
Aims
To investigate physical activity levels of nursing and medicine students; examine predictors of physical activity level; and examine the most influential benefits and barriers to exercise.
Background
Healthcare professionals have low levels of physical activity, which increases their health risk and may influence their health promotion practices with patients.
Design
We surveyed 361 nursing (n=193) and medicine (n=168) students studying at a UK medical school.
Methods
Questionnaire survey, active over 12 months in 2014-2015. Measures included physical activity level, benefits and barriers to exercise, social support, perceived stress and self-efficacy for exercise.
Results
Many nursing and medicine students did not achieve recommended levels of physical activity (nursing: 48%; medicine: 38%). Perceived benefits of exercise were health-related, with medicine students identifying additional benefits for stress-relief. Most notable barriers to exercise were: lack of time, facilities having inconvenient schedules and exercise not fitting around study or placement schedules. Nursing students were less active than medicine students; they perceived fewer benefits and more barriers to exercise and reported lower social support for exercise. Physical activity of nursing and medicine students was best predicted by self-efficacy and social support, explaining 35% of the variance.
Conclusion
Physical activity should be promoted in nursing and medicine students. Interventions should aim to build self-efficacy for exercise and increase social support. Interventions should be developed that are targeted specifically to shift-working frontline care staff, to reduce schedule-related barriers to exercise and increase accessibility to workplace health and wellbeing initiatives
Intraspecific traits change biodiversity effects on ecosystem functioning under metal stress
The online version of this article (doi:10.1007/s00442-011-1930-3) contains supplementary material, which is available to authorized users.Studies investigating the impacts of biodiversity loss on ecosystem processes have often reached different conclusions, probably because insufficient attention has been paid to some aspects including (1) which biodiversity measure (e.g., species number, species identity or trait) better explains ecosystem functioning, (2) the mechanisms underpinning biodiversity effects, and (3) how can environmental context modulates biodiversity effects. Here, we investigated how species number (one to three species) and traits of aquatic fungal decomposers (by replacement of a functional type from an unpolluted site by another from a metal-polluted site) affect fungal production (biomass acumulation) and plant litter decomposition in the presence and absence of metal stress. To examine the putative mechanisms that explain biodiversity effects, we determined the contribution of each fungal species to the total biomass produced in multicultures by real-time PCR. In the absence of metal, positive diversity effects were observed for fungal production and leaf decomposition as a result of species complementarity. Metal stress decreased diversity effects on leaf decomposition in assemblages containing the functional type from the unpolluted site, probably due to competitive interactions between fungi. However, dominance effect maintained positive diversity effects under metal stress in assemblages containing the functional type from the metal-polluted site. These findings emphasize the importance of intraspecific diversity in modulating diversity effects under metal stress, providing evidence that trait-based diversity measures should be incorporated when examining biodiversity effects.The Portuguese Foundation for Science and
Technology supported I. Fernandes (SFRH/BD/42215/2007
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Gut microbiota modulation accounts for the neuroprotective properties of anthocyanins
High-fat (HF) diets are thought to disrupt the profile of the gut microbiota in a manner that may contribute to the neuroinflammation and neurobehavioral changes observed in obesity. Accordingly, we hypothesize that by preventing HF-diet induced dysbiosis it is possible to prevent neuroinflammation and the consequent neurological disorders. Anthocyanins are flavonoids found in berries that exhibit anti-neuroinflammatory properties in the context of obesity. Here, we demonstrate that the blackberry anthocyanin-rich extract (BE) can modulate gut microbiota composition and counteract some of the features of HF-diet induced dysbiosis. In addition, we show that the modifications in gut microbial environment are partially linked with the anti-neuroinflammatory properties of BE. Through fecal metabolome analysis, we unravel the mechanism by which BE participates in the bilateral communication between the gut and the brain. BE alters host tryptophan metabolism, increasing the production of the neuroprotective metabolite kynurenic acid. These findings strongly suggest that dietary manipulation of the gut microbiota with anthocyanins can attenuate the neurologic complications of obesity, thus expanding the classification of psychobiotics to anthocyanins
Maternal gene expression in Atlantic halibut (Hippoglossus hippoglossus L.) and its relation to egg quality
<p>Abstract</p> <p>Background</p> <p>The commercial production of Atlantic halibut (<it>Hippoglossus hippoglossus </it>L.) suffers from a major bottleneck due to the low success of producing juveniles for on-growing. Atlantic halibut females are routinely hand-stripped and incorrect timing of stripping can result in low quality eggs due to post-ovulatory aging. Post-ovulatory aging leads to compositional changes in eggs that include maternally provided proteins and RNAs. There have been few studies of the maternally provided mRNA transcripts that control early development in commercially important fish species. The present study aimed to study maternal gene expression in Atlantic halibut and its relation to egg quality parameters including blastomere symmetry and hatching success.</p> <p>Results</p> <p>A maternal EST library containing 2341 sequences was constructed by suppressive subtractive hybridisation. Thirty genes were selected for expression studies; 23 novel genes and 7 genes with documented roles in early development. The expressions of twenty-one selected genes were measured by qPCR from fertilization to the 10-somite stage. Three genes were identified as strictly maternal genes that were expressed until the start of gastrulation; <it>askopos </it>(<it>kop</it>), <it>si:dkey-30j22.9 </it>(Tudor family member), and <it>Tudor 5 protein </it>(<it>Tdrd5</it>). The expressions of 18 genes at the 8-cell stage were correlated with egg quality parameters. The majority of genes showed either no or very minor correlations with egg quality parameter. However, two genes correlated positively with hatching success (<it>r</it>> 0.50, HHC00353: <it>r </it>= 0.58, <it>p </it>< 0.01; HHC01517: <it>r </it>= 0.56, <it>p </it>< 0.01) and one gene (HHC00255) was negatively correlated with the percentage of normal blastomeres (<it>r </it>= -0.62, <it>p </it>< 0.05).</p> <p>Conclusions</p> <p>During this study we have related maternal levels of gene expression to hatching success in fish. Poor hatching success was not correlated with a general decrease in transcript abundance but with low transcript levels of some specific genes. Thus, the molecular mechanisms leading to low Atlantic halibut egg quality cannot be entirely explained by post-ovulatory aging.</p
Six-membered ring systems: with O and/or S atoms
A large variety of publications have emerged in 2012 involving O- and S-6-
membered ring systems. The increasing number of reviews and other communica-
tions dedicated to natural and synthetic derivatives and their biological significance
highlights the importance of these heterocycles.
Reviews on natural products involve biosynthesis and isolation of enantiomeric
derivatives h12AGE4802i, biosynthesis, isolation, synthesis, and biological studies
on the pederin family h12NPR980i and xanthones obtained from fungi, lichens,
and bacteria h12CR3717i and on the potential chemotherapeutic value of phyto-
chemical products and plant extracts as antidiabetic h12NPR580i, antimicrobial,
and resistance-modifying agents h12NPR1007i. A more specific review covers a
structure–activity relationship of endoperoxides from marine origin and their antitry-
panosomal activity h12OBC7197i.
New synthetic routes to naturally occurring, biologically active pyran derivatives
have been the object of several papers. Different approaches have been discussed for
the total synthesis of tetrahydropyran-containing natural products (")-zampanolide
h12CEJ16868, 12EJO4130, 12OL3408i, (")-aspergillides A and B h12H(85)587,
12H(85)1255, 12TA252i, (þ)-neopeltolide h12JOC2225, 12JOC9840, 12H(85)
1255i, or their macrolactone core h12OBC3689, 12OL2346i. The total synthesis
of bistramide A h12CEJ7452i and (þ)-kalihinol A h12CC901i and the stereoselec-
tive synthesis of a fragment of bryostatin h12S3077, 12TL6163i have also been sur-
veyed. Other papers relate the total synthesis of naturally occurring carbocyclic and
heterocyclic-fused pyran compounds, such as (")-dysiherbaine h12CC6295i, penos-
tatin B h12OL244i, Greek tobacco lactonic products, and analogues h12TL4293i
and on the structurally intriguing limonoids andhraxylocarpins A–E h12CEJ14342i.
The stereocontrolled synthesis of fused tetrahydropyrans was used in the preparation
of blepharocalyxin D h12AGE3901i.
Polyphenolic heterocyclic compounds have also received great attention in 2012.
The biological activities and the chemistry of prenylated caged xanthones
h12PCB78i, the occurrence of sesquiterpene coumarins h12PR77i, and the medicinal properties of the xanthone mangiferin h12MRME412i have been reviewed.
An overview on the asymmetric syntheses of flavanones and chromanones
h12EJO449i, on the synthesis and reactivity of flavones h12T8523i and xanthones
h12COC2818i, on the synthesis and biosynthesis of biocoumarins h12T2553i, and on
the synthesis and applications of flavylium compounds h12CSR869i has been discussed.
The most recent developments in the synthesis and applications of sultones, a
very important class of sulfur compounds, were reported h12CR5339i.
A review on xanthene-based fluorescent probes for sensing cations, anions, bio-
logical species, and enzyme activity has described the spiro-ring-opening approach
with a focus on the major mechanisms controlling their luminescence behavior
h12CR1910i. The design and synthesis of other derivatives to be used as sensors of
gold species h12CC11229i and other specific metal cations h12PC823i have also
been described. Recent advances related to coumarin-derived fluorescent chemosen-
sors for metal ions h12COC2690i and to monitoring in vitro analysis and cellular
imaging of monoamine oxidase activity h12CC6833i have been discussed.
The study of various organic chromophores allowed the synthesis of novel dica-
tionic phloroglucinol-type bisflavylium pigments h12SL2053i, and the optical and
spectroscopic properties of several synthetic 6-aryldibenzo[b,d]pyrylium salts were
explored h12TL6433i.
Discussion of specific reactions leading to O- and S-membered heterocyclic
compounds covers intramolecular radical cyclization h12S2475i and asymmetric
enamine and dienamine catalysis h12EJO865i, oxa-Michael h12CSR988i and dom-
ino Knoevenagel–hetero-Diels–Alder (hDA) reactions h12T5693i, and the versatility
in cycloadditions as well as nucleophilic reactions using o-quinones h12CSR1050i.
The use of specific reagents relevant to this chapter includes molecular iodine
h12CEJ5460, 12COS561i, samarium diiodide–water for selective reductive transfor-
mations h12CC330i, o-quinone methides as versatile intermediates h12CEJ9160i,
InCl3 as catalyst h12T8683i, and gold and platinum p-acid mediated insertion of
alkynes into carbon–heteroatom s-bonds h12S3401i.
The remainder of this chapter discusses the most studied transformations on
O- and S-6-membered heterocycles
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