354 research outputs found
Stable populations in unstable habitats: temporal genetic structure of the introduced ascidian Styela plicata in North Carolina
14 páginas, 3 tablas, 4 figuras.The analysis of temporal genetic variability is
an essential yet largely neglected tool to unveil and predict
the dynamics of introduced species. We here describe
the temporal genetic structure and diversity over time of
an introduced population of the ascidian Styela plicata
(Lesueur, 1823) in Wilmington (North Carolina, USA,
34°08′24″N, 77°51′44″W). This population suffers important
salinity and temperature changes, and in June every
year we observed massive die-offs, leaving free substratum
that was recolonized within a month. We sampled 12–14
individuals of S. plicata every 2 months from 2007 to 2009 (N = 196) and analyzed a mitochondrial marker (the gene
cytochrome oxidase subunit I, COI) and seven nuclear
microsatellites. Population genetic analyses showed similar
results for both types of markers and revealed that most
of the genetic variation was found within time periods.
However, analyses conducted with microsatellite loci also
showed weak but significant differences among time periods.
Specifically, in the samplings after die-off episodes
(August–November 2007 and 2008) the genetic diversity
increased, the inbreeding coefficient showed prominent
drops, and there was a net gain of alleles in the microsatellite
loci. Taken together, our results suggest that recruits
arriving from neighboring populations quickly occupied
the newly available space, bringing new alleles with them.
However, other shifts in genetic diversity and allele loss
and gain episodes were observed in December–January and
February–March 2008, respectively, and were apparently
independent of die-off events. Overall, our results indicate
that the investigated population is stable over time and
relies on a periodic arrival of larvae from other populations,
maintaining high genetic diversity and a complex interplay
of allele gains and losses.This research was supported
by a grant from the United States–Israel Binational Science Foundation
(BSF), Jerusalem, Israel (number 2014025), the Spanish Government
project CTM2013—48163—and the Catalan Government Grant
2014SGR-336 for Consolidated Research Groups.Peer reviewe
Simulation of static and random errors on Grover's search algorithm implemented in a Ising nuclear spin chain quantum computer with few qubits
We consider Grover's search algorithm on a model quantum computer implemented
on a chain of four or five nuclear spins with first and second neighbour Ising
interactions. Noise is introduced into the system in terms of random
fluctuations of the external fields. By averaging over many repetitions of the
algorithm, the output state becomes effectively a mixed state. We study its
overlap with the nominal output state of the algorithm, which is called
fidelity. We find either an exponential or a Gaussian decay for the fidelity as
a function of the strength of the noise, depending on the type of noise (static
or random) and whether error supression is applied (the 2pi k-method) or not.Comment: 18 pages, 8 figures, extensive revision with new figure
An observational study of the 7 September 2005 Barcelona tornado outbreak
This paper presents an observational study of the tornado outbreak that took place on the 7 September 2005 in the Llobregat delta river, affecting a densely populated and urbanised area and the Barcelona International airport (NE Spain). The site survey confirmed at least five short-lived tornadoes. Four of them were weak (F0, F1) and the other one was significant (F2 on the Fujita scale). They started mostly as waterspouts and moved later inland causing extensive damage estimated in 9 million Euros, three injured people but fortunately no fatalities. Large scale forcing was provided by upper level diffluence and low level warm air advection. Satellite and weather radar images revealed the development of the cells that spawned the waterspouts along a mesoscale convergence line in a highly sheared and relatively low buoyant environment. Further analysis indicated characteristics that could be attributed indistinctively to non-supercell or to mini-supercell thunderstorms
An observational study of the 7 September 2005 Barcelona tornado outbreak
This paper presents an observational study of the tornado outbreak that took place on the 7 September 2005 in the Llobregat delta river, affecting a densely populated and urbanised area and the Barcelona International airport (NE Spain). The site survey confirmed at least five short-lived tornadoes. Four of them were weak (F0, F1) and the other one was significant (F2 on the Fujita scale). They started mostly as waterspouts and moved later inland causing extensive damage estimated in 9 million Euros, three injured people but fortunately no fatalities. Large scale forcing was provided by upper level diffluence and low level warm air advection. Satellite and weather radar images revealed the development of the cells that spawned the waterspouts along a mesoscale convergence line in a highly sheared and relatively low buoyant environment. Further analysis indicated characteristics that could be attributed indistinctively to non-supercell or to mini-supercell thunderstorms
Phosphorus restriction does not prevent the increase in fibroblast growth factor 23 elicited by high fat diet
This
study
was
designed
to evaluate
the
influence
of phosphorus
(P)
restriction
on
the
dele-
terious
effects
of high
fat
diets
on
mineral
metabolism.
Twenty-four
rats
were
allotted
to 3
groups
(n = 8 each)
that
were
fed
different
diets
for
7 months.
Rats
in group
1 were
fed
nor-
mal
fat-normal
P (0.6%)
diet
(NF-NP),
rats
in group
2 were
fed
high
fat-
normal
P diet
(HF-
NP)
and
rats
in group
3 were
fed
high
fat-low
P (0.2%)
diet
(HF-LP).
Blood,
urine
and
tissues
were
collected
at the
end
of the
experiments.
When
compared
with
the
control
group
(NF-
NP),
rats
fed
HF
diets
showed
increases
in body
weight,
and
in plasma
concentrations
of tri-
glycerides
and
leptin,
and
decreased
plasma
calcitriol
concentrations.
In rats
fed
HF-NP
plasma
fibroblast
growth
factor
23
(FGF23)
was
higher
(279.6
±
39.4
pg/ml
vs
160.6
±
25.0
pg/ml,
p = 0.018)
and
renal
klotho
(ratio
klotho/GAPDH)
was
lower
(0.75
±
0.06
vs
1.06
±
0.08,
p
<
0.01)
than
in rats
fed
NF-NP.
Phosphorus
restriction
did
not
normalize
plasma
FGF23
or
renal
klotho;
in fact,
rats
fed
HF-LP,
that
only
ingested
an
average
of 22.9
mg/day
of P,
had
higher
FGF23
(214.7
±
32.4
pg/ml)
concentratio
ns
than
rats
fed
NF-NP
(160.6
±
25.
0 pg/ml),
that
ingested
and
average
of 74.4
mg/day
of P over
a 7 month
period.
In conclusion,
our
results
demonstrate
that
severe
P restriction
over
a prolonged
period
of time
(7 months)
does
not
normalize
the
increase
in circulating
FGF23
induced
by
HF
diets.
These
data
indi-
cate
that
the
deleterious
effects
of high
fat
diet
on
the
FGF23/klotho
axis
are
not
eliminated
by
reduced
P intake
Nueva información para la avifauna del estado de Querétaro, México
We present new information about 24 species, including 12 noteworthy records for the avifauna of the Mexican state of Queretaro. These data were gathered during fieldwork performed between 1993 to 2007, mainly in the Eje Neovolcánico province. Five species are considered protected under Mexican law NOM-059-SEMARNAT-2001: Buteogallus anthracinus, Buteo albonotatus, Trogon collaris, Turdus infuscatus and Vermivora crissalis. The checklist of birds present in Queretaro is now at least 347 species.Presentamos información nueva de 24 especies, incluyendo 12 nuevos registros de aves para el estado de Querétaro, México. Estos datos fueron obtenidos en diversos estudios de campo de 1993 a 2007, principalmente en la provincia del Eje Neovolcánico. Cinco especies están bajo alguna categoría de riesgo según la NOM-059-SEMARNAT-2001: Buteogallus anthracinus, Buteo albonotatus, Trogon collaris, Turdus infuscatus y Vermivora crissalis. Con estas adiciones el listado de aves de Querétaro se incrementa al menos a 347 especie
Relationship Between Bird Diversity and Habitat along a Pine- Oak Successional Forest in Southern Mexico
Few studies have related bird species richness and abundance with vegetation structure at different successional stages in pine-oak forests of Mexico. We studied changes in the bird community across three successional stages of pine-oak forest: early, intermediate, and mature. Also, we related bird community attributes—including generalist and specialist birds—with vegetation variables. We analyzed the vegetation and estimated bird abundances in 10-min-count periods in 10 circular plots per successional stage. We recorded a total of 71 bird species: 21 were specialists and 50 were generalists. The completeness of species richness was between 79 and 88% in the sampled habitats. Diversity profiles were consistently larger in the intermediate stage, except for its species richness that was not different between this and the early stage. We found a more richness and a higher number of individuals of generalist in the early and intermediate stages. The abundance of specialists was higher in the mature forest. An ordination analysis showed that generalists were associated to different variables. This suggests that these species can adapt to different forest conditions. Some specialist birds were more abundant in sites with high dominance of trees. Our results confirm the importance of maintaining not only mature forests but also young successional stages in order to conserve the species typical of secondary pine-oak forest bird species
Oral Acid Load Down-Regulates Fibroblast Growth Factor 23
Increased dietary acid load has a negative impact on health, particularly when renal function is compromised. Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that is elevated during renal failure. The relationship between metabolic acidosis and FGF23 remains unclear. To investigate the effect of dietary acid load on circulating levels of FGF23, rats with normal renal function and with a graded reduction in renal mass (1/2 Nx and 5/6 Nx) received oral NH4Cl for 1 month. Acid intake resulted in a consistent decrease of plasma FGF23 concentrations in all study groups when compared with their non-acidotic control: 239.3 ± 13.5 vs. 295.0 ± 15.8 pg/mL (intact), 346.4 ± 19.7 vs. 522.6 ± 29.3 pg/mL (1/2 Nx) and 988.0 ± 125.5 vs. 2549.4 ± 469.7 pg/mL (5/6 Nx). Acidosis also decreased plasma PTH in all groups, 96.5 ± 22.3 vs. 107.3 ± 19.1 pg/mL, 113.1 ± 17.3 vs. 185.8 ± 22.2 pg/mL and 504.9 ± 75.7 vs. 1255.4 ± 181.1 pg/mL. FGF23 showed a strong positive correlation with PTH (r = 0.877, p < 0.0001) and further studies demonstrated that acidosis did not influence plasma FGF23 concentrations in parathyroidectomized rats, 190.0 ± 31.6 vs. 215 ± 25.6 pg/mL. In conclusion, plasma concentrations of FGF23 are consistently decreased in rats with metabolic acidosis secondary to increased acid intake, both in animals with intact renal function and with decreased renal function. The in vivo effect of metabolic acidosis on FGF23 appears to be related to the simultaneous decrease in PTH
Dinámica de uso y cobertura del suelo en un parque nacional mexicano
To understand the dynamics of land cover at the Parque Nacional Cofre de Perote, the rates of change in land use were compared at two
different scales during the period 1995-2004. At the meso scale, these patterns were studied throughout the entire Parque Nacional Cofre
de Perote, which is one of the 60 priority mountains of Mexico, and an important natural protected area of the country located in the
state of Veracruz. At a micro scale, the work was focused in ejido El Conejo, located within the boundaries of this national park. Federal
government digital orthophotos were used to determine changes in nine categories of land use. In both, the meso- and micro-scale, it was
found that the predominant land cover categories are agriculture and forest. The probabilities of land cover change at both scales are
low and essentially the same for most land use categories, reflecting both small gains in forest cover park-wide as well as the effectiveness
of the ejido in managing natural resources within the park. The authors consider that the findings of the study may be applicable to the
broader situation of national parks in Mexico and, finally, the importance of integrating local stakeholders in the management of natural
protected areas is discussedPara entender la dinámica de la cobertura del suelo en el Parque Nacional Cofre de Perote, se hizo una comparación de las tasas de cambio de uso a dos escalas durante el periodo 1995-2004. A escala meso, se estudiaron estos patrones en toda la superficie del Parque Nacional Cofre de Perote, que es una de las 60 montañas prioritarias de México y también una importante área natural protegida del país ubicada en el estado de Veracruz. A escala micro el estudio se enfocó en el ejido El Conejo que se encuentra dentro de los límites de este parque nacional. Se utilizaron ortofotos digitales del gobierno federal para determinar el cambio en nueve categorías de uso del suelo. En ambas, meso y microescalas, se encontró que las categorías predominantes de cobertura son la agricultura y el bosque. Las probabilidades de cambio de cobertura del suelo en ambas escalas son bajas y tienen valores esencialmente iguales para la mayoría de las categorías de uso, reflejando tanto pequeñas ganancias en cobertura forestal en todo el parque como la efectividad del ejido en el manejo de recursos naturales dentro del parque. Se considera que los hallazgos de este estudio pueden ser aplicables a la situación prevaleciente en los restantes parques nacionales de México; al final se discute la importancia de integrar a los actores locales en el manejo de áreas naturales protegidasS
Energy-dense diets increase FGF23, lead to phosphorus retention and promote vascular calcifications in rats
Rats with normal renal function (Experiment 1, n = 12) and uninephrectomized (1/2Nx) rats
(Experiment 2, n = 12) were fed diets with normal P (NP) and either normal (NF) or high fat (HF).
Rats with intact renal function (Experiment 3, n = 12) were also fed NF or HF diets with high P (HP).
Additionally, uremic (5/6Nx) rats (n = 16) were fed HP diets with NF or HF. Feeding the HF diets resulted
in significant elevation of plasma FGF23 vs rats fed NF diets: Experiment 1, 593 ± 126 vs 157 ± 28 pg/
ml (p < 0.01); Experiment 2, 538 ± 105 vs 250 ± 18 pg/ml (p < 0.05); Experiment 3, 971 ± 118 vs
534 ± 40 pg/ml (p < 0.01). Rats fed HF diets showed P retention and decreased renal klotho (ratio
klotho/actin) vs rats fed NF diets: Experiment 1, 0.75 ± 0.06 vs 0.97 ± 0.02 (p < 0.01); Experiment 2,
0.69 ± 0.07 vs 1.12 ± 0.08 (p < 0.01); Experiment 3, 0.57 ± 0.19 vs 1.16 ± 0.15 (p < 0.05). Uremic rats
fed HF diet showed more severe vascular calcification (VC) than rats fed NF diet (aortic Ca = 6.3 ± 1.4
vs 1.4 ± 0.1 mg/g tissue, p < 0.001). In conclusion, energy-rich diets increased plasma levels of
FGF23, a known risk factor of cardiovascular morbidity and mortality. Even though FGF23 has major
phosphaturic actions, feeding HF diets resulted in P retention, likely secondary to decreased renal
klotho, and aggravated uremic V
- …