438 research outputs found
Interaction Between Visual and Phonotactic Orientation During Flight in \u3ci\u3eMagicicada Cassini\u3c/i\u3e (Homoptera: Cicadidae)
Visual and phonotactic orientation often occur simultaneously in diurnal cicadas. and these animals generally have their largest sensory elaboration in eyes and hearing organs. Phonotactic orientation occurs principally during flight. Males and females of Magicicada cassini commonly perform low- altitude « 5 m) and short-distance « 15 m) flights in their natural habitat at flight speeds of 3 to 6 m/s. During flight, the long body axis is tilted 10° to Q , head upward. Wing beat frequencies of tethered animals at 24° to 26°C averaged 28.8 Hz. Body temperature in the field for flying individuals aver- aged 4.6°C above ambient.
Compound eyes of females possess about 7% more facets than males, and the binocular field of view for both is especially expanded dorsa-frontally, frontally, and fronto-ventrally. The role of vision for phonoresponses, and in flight and landing behavior. was studied in nature by comparing controls with cicadas with eyes partly to completely covered with aluminum paint. Cicadas with their three ocelli covered behaved like controls and exhibited low-altitude and short-distance flights with landings on neighboring shrubs, as did cicadas with only both caudal halves or both dorsal halves of the compound eyes covered. Those with both compound eyes covered completely (with or without additionally covering the three ocelli) flew to higher altitudes and for longer distances. Higher and longer flight courses were also seen in cicadas (A) with only one compound eye covered. which in addition circled during walking and flight toward the side of unrestricted vision, (B) with both frontal or both ventral halves of their compound eyes covered. and (C) with either the binocular or monocular fields of the eyes covered. Thus, the paired fronta-antero-ventral regions of the compound eyes provide visual information for habitat-dependent low-altitude flights and landings.
Females with intact compound eyes and ocelli responded to playbacks of just the frequency/intensity sweep at the end of the buzz in calling songs of a male by flying within 1.2 m above the ground and landing on a nylon screen- covered small bush directly above the loudspeaker from distances of 2 to 8 m. mostly from lower vegetation. Males that were blinded, or blinded and deafened, sang less and flew less than normal males. However. they performed all of those behaviors, and all also walked and fed.
Periodical cicadas (Magicicada, Tibicininae) are known for synchronized adult emergence and noisy aggregations of millions of individuals of three intermingled species in each brood population (Alexander and Moore 1962). Broods are isolated geographically and chronologically, such that in some years no periodical cicada adults emerge, and most areas of the eastern United States have only one brood population appearing as adults at intervals of either 13 or 17 years. In all Magicicada species, daily flights affect spacing and aggregation of both sexes during feeding, chorusing, mating, and ovipositing. Flights are mediated by both acoustical and visual cues. Each species in these aggregations establishes mating leks. These aggregations continue to mix, every day and unpredictably, during the emergence period. Toward the end of the reproductive season, males die sooner than females, leading to little or no chorusing, and then females disperse progressively further from the lek sites. The cohesive effect of the acoustical cues of chorusing males on these cicada populations is obvious.
Both sexes of all six species of periodical cicadas live and feed on shrubs and trees of different species, sizes, and shapes, and females lay eggs in their living twigs. Their niches overlap almost completely, the three species of 13 year or 17-year cicadas being separated principally by diurnal acoustic behavior leading to aggregation sites that change every day and are seldom exclusive to a single Magicicada species. Adults frequently change location in these complex visual environments by short-distance and low-altitude flights. which we call bush-hopping. These flights are associated with sound communication and reproductive activities and are most commonly observed during bright sunlight and at ambient temperatures above 25°C with little wind (Alexander and Moore 1958,1962; Dunning et al. 1979). Otte (1990) and Toms (1992) discuss the common correlation between hearing and flying in orthopteroid insects, interactions basically similar to those found in cicadas. The present paper describes the interaction of vision (compound eyes and ocelli) and phonoresponses of males and females of Magicicada cassini (Fisher) in walking, but especially in flight and landing behavior, within a natural habitat
Dry soils can intensify mesoscale convective systems
Soil moisture can feed back on rainfall through the impact of surface fluxes on the environment in which convection develops. The vast majority of previous research has focused on the initiation of convection, but in many regions of the world, the majority of rain comes from remotely triggered mesoscale convective systems (MCSs). Here we conduct a systematic observational analysis of soil moisture feedbacks on propagating MCSs anywhere in the world and show a strong positive impact of drier soils on convection within mature MCSs. From thousands of storms captured in satellite imagery over the Sahel, we find that convective cores within MCSs are favored on the downstream side of dry patches ≥200 km across. The effect is particularly strong during the afternoon–evening transition when convection reaches its diurnal peak in intensity and frequency, with dry soils accounting for an additional one in five convective cores. Dry soil patterns intensify MCSs through a combination of convergence, increased instability, and wind shear, all factors that strengthen organized convection. These favorable conditions tend to occur in the vicinity of a surface-induced anomalous displacement of the Sahelian dry line/intertropical discontinuity, suggesting a strong link between dry line dynamics and soil moisture state. Our results have important implications for nowcasting of severe weather in the Sahel and potentially in other MCS hotspot regions of the world
The extracellular matrix of hematopoietic stem cell niches
Hematopoietic stem cells (HSCs) are the life-long source of all types of blood cells. Their function is controlled by their direct microenvironment, the HSC niche in the bone marrow. Although the importance of the extracellular matrix (ECM) in the niche by orchestrating niche architecture and cellular function is widely acknowledged, it is still underexplored. In this review, we provide a comprehensive overview of the ECM in HSC niches. For this purpose, we first briefly outline HSC niche biology and then review the role of the different classes of ECM molecules in the niche one by one and how they are perceived by cells. Matrix remodeling and the emerging importance of biophysics in HSC niche function are discussed. Finally, the application of the current knowledge of ECM in the niche in form of artificial HSC niches for HSC expansion or targeted differentiation as well as drug testing is reviewed. © 2021 The Author(s
Bürgerbeteiligung in der Lokalpolitik
Die vorliegende Arbeit zeigt die Entstehung einer Bürgerbeteiligung in Form der Lokalen Agenda 21. Zum besseren Verständnis zeigt sie nicht nur die bestehenden gesetzlichen Grundlagen der indirekten und direkten Demokratie in Österreich und die Möglichkeiten der Bürgerbeteiligung auf, sondern gibt weiter theoretisches Basiswissen in Form von Begriffsklärungen wie der Partizipation, der Bürgerbeteiligung und der Nachhaltigkeit. Die Tätigkeit der Lokalen Agenda 21 basiert auf einem Handlungsprogramm der UNO, welches 1992 in Rio de Janeiro beschlossen wurde. Das große erklärte Ziel ist die Steigerung der Nachhaltigkeit in jedem Lebensbereich und Verankerung dessen in den Köpfen der Bevölkerung, d.h. dass theoretisch ebendiese für die Veränderung notwendig ist. Im 28.Kapitel der Agenda 21 wurde beschlossen, dass jede Kommune in einen Dialog mit seiner Bevölkerung treten soll. In diesem neuen und geschützten Rahmen werden die Grenzen zwischen den teilnehmenden BürgerInnen, Verwaltung und PolitikerInnen neu erprobt. Außerdem können neue Formen des Politikmachens erprobt und Machtverhältnisse kritisch hinterfragt werden. Die Lokale Agenda 21 wird zu einem Lernprozess für alle Beteiligten. Für Wien gilt, dass Bürgermeister Häupl die Aalborg Charta unterschrieb und die Stadt Wien somit verpflichtete sich an dem Prozessen zu beteiligen. Nach einem Pilotprojekt 1998 wurde vom Wiener Gemeinderat ein Organisationsmodell beschlossen – mit der Grundlage des Vereins Lokale Agenda 21 Wien zur Förderung von Bürgerbeteiligungsprozessen - , dass im März 2004 zum Start der Lokalen Agenda 21 in Wien Liesing führte. Schon im ein halbes Jahr später konnte der Prozess mit einer umfangreichen Aktivierungs- und Informationsphase sowie den ersten Arbeitsgruppen starten. Ende des Jahres 2004 wurden sie in Liesing als erste Agendagruppen anerkannt
Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon
West Africa is a hot spot region for land–atmosphere coupling where atmospheric conditions and convective rainfall can strongly depend on surface characteristics. To investigate the effect of natural interannual vegetation changes on the West African monsoon precipitation, we implement satellite-derived dynamical datasets for vegetation fraction (VF), albedo and leaf area index into the Weather Research and Forecasting model. Two sets of 4-member ensembles with dynamic and static land surface description are used to extract vegetation-related changes in the interannual difference between August–September 2009 and 2010. The observed vegetation patterns retain a significant long-term memory of preceding rainfall patterns of at least 2 months. The interannual vegetation changes exhibit the strongest effect on latent heat fluxes and associated surface temperatures. We find a decrease (increase) of rainy hours over regions with higher (lower) VF during the day and the opposite during the night. The probability that maximum precipitation is shifted to nighttime (daytime) over higher (lower) VF is 12 % higher than by chance. We attribute this behaviour to horizontal circulations driven by differential heating. Over more vegetated regions, the divergence of moist air together with lower sensible heat fluxes hinders the initiation of deep convection during the day. During the night, mature convective systems cause an increase in the number of rainy hours over these regions. We identify this feedback in both water- and energy-limited regions of West Africa. The inclusion of observed dynamical surface information improved the spatial distribution of modelled rainfall in the Sahel with respect to observations, illustrating the potential of satellite data as a boundary constraint for atmospheric models
The role of ZC3H32 in Trypanosoma brucei
In
the
protozoan
parasite
Trypanosoma
brucei
gene
expression
is
mostly
regulated
on
the
post-‐transcriptional
level.
C3H
zinc
fingers
have
shown
to
play
an
important
role
in
this
process.
So
far,
all
described
C3H
zinc
finger
in
Trypanosoma
brucei
have
shown
to
stabilize
their
targets.
This
work
focuses
on
the
zinc
finger
protein
ZC3H32.
A
large-‐scale
isolation
of
free
and
membrane-‐bound
polyribosomes
from
proyclic
and
bloodstream
trypanosomes,
which
is
also
described
in
this
thesis,
suggested
that
this
protein
associates
with
polyribosomes.
However,
small-‐scale
polyribosome
isolations
followed
by
Western
blotting
revealed
that
only
a
minor
fraction
of
it
is
actually
associated
with
polyribosomes.
Immunofluorescence
showed
that
ZC3H32
localizes
to
the
cytoplasm.
A
yeast-‐two-‐
hybrid
screen
identified
it
as
a
putative
binding
partner
of
MKT1.
This
interaction
was
confirmed
by
co-‐immunoprecipitation.
RNAi,
as
well
as
knock-‐out
studies,
showed
that
ZC3H32
is
essential
in
the
bloodstream
form.
Northern
blotting,
as
well
as
a
SILAC
screen
by
Urbaniak
et
al.
indicate
that
it
is
also
enriched
in
this
life-‐cycle
stage
as
compared
to
procyclics.
Artificial
tethering
of
ZC3H32
to
a
reporter
RNA
lead
to
the
RNA’s
degradation,
suggesting
that
this
protein
has
a
destabilizing
effect.
Tethering
of
ZC3H32
fragments
revealed
that
both
its
N-‐terminal,
as
well
as
its
C-‐terminal
region
are
able
to
generate
this
destabilization
effect,
while
the
middle
region,
containing
the
zinc
finger
domains,
can’t.
RNA
isolation
from
polyribosomal
fractions
showed
that
tethering
of
ZC3H32
also
decreases
the
translation
of
the
reporter
RNA.
High-‐throughput
sequencing
of
poly-‐A+
RNA
from
a
ZC3H32-‐RNAi
cell
line
revealed
20
RNAs
that
were
up-‐regulated
upon
ZC3H32
knock-‐down
and
thus
might
be
putative
targets.
The
upregulation
was
confirmed
for
three
of
these
candidate
RNAs.
The
majority
of
the
putative
ZC3H32
targets
play
a
role
in
the
trypanosome’s
energy
metabolism
and
15
of
them
are
up-‐regulated
in
procyclics.
These
results
suggest
that
ZC3H32
might
be
involved
in
the
stage-‐specific
regulation
of
these
RNAs
in
the
bloodstream
form
Dry-to-Wet Soil Gradients Enhance Convection and Rainfall over Subtropical South America
Soil moisture-precipitation (SM-PPT) feedbacks at the mesoscale represent a
major challenge for numerical weather prediction, especially for subtropical
regions that exhibit large variability in surface SM. How does surface
heterogeneity, specifically mesoscale gradients in SM and land surface
temperature (LST), affect convective initiation (CI) over South America? Using
satellite data, we track nascent, daytime convective clouds and quantify the
underlying antecedent (morning) surface heterogeneity. We find that convection
initiates preferentially on the dry side of strong SM/LST boundaries with
spatial scales of tens of kilometers. The strongest alongwind gradients in LST
anomalies at 30 km length scale underlying the CI location occur during weak
background low-level wind (<2.5m/s), high convective available potential energy
(>1500J/kg) and low convective inhibition (<250J/kg) over sparse vegetation. At
100 km scale, strong gradients occur at the CI location during convectively
unfavorable conditions and strong background flow. The location of PPT is
strongly sensitive to the strength of the background flow. The wind profile
during weak background flow inhibits propagation of convection away from the
dry regions leading to negative SM-PPT feedback whereas strong background flow
is related to longer lifecycle and rainfall hundreds of kilometers away from
the CI location. Thus, the sign of the SM-PPT feedback is dependent on the
background flow. This work presents the first observational evidence that CI
over subtropical South America is associated with dry soil patches on the order
of tens of kilometers. Convection-permitting numerical weather prediction
models need to be examined for accurately capturing the effect of SM
heterogeneity in initiating convection over such semi-arid regions.Comment: 42 pages, 14 figures, 3 tables. Manuscript under peer-revie
B Cell–specific Transgenic Expression of Bcl2 Rescues Early B Lymphopoiesis but Not B Cell Responses in BOB.1/OBF.1-deficient Mice
Mice deficient for the transcriptional coactivator BOB.1/OBF.1 show several defects in B cell differentiation. Numbers of immature transitional B cells in the bone marrow are reduced and fewer B cells reach the periphery. Furthermore, germinal center B cells are absent and marginal zone (MZ) B lymphocytes are markedly reduced. Increased levels of B cell apoptosis in these mice prompted us to analyze expression and function of antiapoptotic proteins. Bcl2 expression is strongly reduced in BOB.1/OBF.1-deficient pre–B cells. When BOB.1/OBF.1-deficient mice were crossed with Bcl2-transgenic mice, B cell development in the bone marrow and numbers of B cells in peripheral lymphoid organs were normalized. However, neither germinal center B cells nor MZ B cells were rescued. Additionally, Bcl2 did not rescue the defects in signaling and affinity maturation found in BOB.1/OBF.1-deficient mice. Interestingly, Bcl2-transgenic mice by themselves show an MZ B cell defect. Virtually no functional MZ B cells were detected in these mice. In contrast, mice deficient for Bcl2 show a relative increase in MZ B cell numbers, indicating a previously undetected function of Bcl2 for this B cell compartment
West African Summer Monsoon Precipitation Variability as Represented by Reanalysis Datasets
Focusing on West Africa, a region riddled with in situ data scarcity, we evaluate the summer monsoon monthly rainfall characteristics of five global reanalysis datasets: ERA5, ERA-Interim, JRA-55, MERRA2, and NCEP-R2. Their performance in reproducing the West African monsoon (WAM) climatology, interannual variability, and long-term trends for the main monsoon months are compared to gauge-only and satellite products. We further examine their ability to reproduce teleconnections between sea surface temperatures and monsoon rainfall. All reanalyses are able to represent the average rainfall patterns and seasonal cycle; however, regional biases can be marked. ERA5, ERA-Interim, and NCEP-R2 underestimate rainfall over areas of peak rainfall, with ERA5 showing the strongest underestimation, particularly over the Guinea Highlands. The meridional northward extent of the monsoon rainband is well captured by JRA-55 and MERRA2 but is too narrow in ERA-Interim, for which rainfall stays close to the Guinea Coast. Differences in rainband displacement become particularly evident when comparing strong El Niño Southern Oscillation (ENSO) years, where all reanalyses except ERA-Interim reproduce wetter Sahelian conditions for La Niña, while overestimating dry conditions at the coast except for NCEP-R2. Precipitation trends are not coherent across reanalyses and magnitudes are generally overestimated compared to observations, with only JRA-55 and NCEP-R2 displaying the expected positive trend in the Sahel. ERA5 generally outperforms ERA-Interim, highlighting clear improvements over its predecessor. Ultimately, we find the strengths of reanalyses to strongly vary across the region
Reduced spiral ganglion neuronal loss by adjunctive neurotrophin-3 in experimental pneumococcal meningitis
<p>Abstract</p> <p>Background</p> <p>Hearing loss is a frequent long-term complication of pneumococcal meningitis (PM). Its main pathological correlate is damage to the organ of Corti and loss of spiral ganglion neurons. The only current treatment option is cochlear implants which require surviving neurons. Here, we investigated the impact of systemically applied neurotrophin-3 (NT-3) on long-term hearing loss and the survival of neurons.</p> <p>Methods</p> <p>Eighteen hours after infection with <it>S. pneumoniae</it>, C57BL/6 mice were treated with a combination of ceftriaxone with NT-3 or dexamethasone or placebo. Hearing, cochlear damage, and brain damage were assessed by audiometry and histology.</p> <p>Results</p> <p>The main findings from immunohistochemical visualization of neurotrophins (NT-3, BDNF) and their receptors (TrkB, TrkC, and p75) in the cochlea were (i) enhanced staining for the cell survival-promoting receptor TrkB and (ii) increased NT-3 staining in NT-3 treated mice, showing that systemically applied NT-3 reaches the cochlea. The major effects of adjunctive NT-3 treatment were (i) a reduction of meningitis-induced hearing impairment and (ii) a reduction of spiral ganglion neuronal loss. The efficacy of NT-3 therapy was comparable to that of dexamethasone.</p> <p>Conclusion</p> <p>Systemically applied NT-3 might be an interesting candidate to improve hearing outcome after pneumococcal meningitis.</p
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