21 research outputs found
The transcriptional repressor complex FRS7-FRS12 regulates flowering time and growth in Arabidopsis
Most living organisms developed systems to efficiently time environmental changes. The plant-clock acts in coordination with external signals to generate output responses determining seasonal growth and flowering time. Here, we show that two Arabidopsis thaliana transcription factors, FAR1 RELATED SEQUENCE 7 (FRS7) and FRS12, act as negative regulators of these processes. These proteins accumulate particularly in short-day conditions and interact to form a complex. Loss-of-function of FRS7 and FRS12 results in early flowering plants with overly elongated hypocotyls mainly in short days. We demonstrate by molecular analysis that FRS7 and FRS12 affect these developmental processes in part by binding to the promoters and repressing the expression of GIGANTEA and PHYTOCHROME INTERACTING FACTOR 4 as well as several of their downstream signalling targets. Our data reveal a molecular machinery that controls the photoperiodic regulation of flowering and growth and offer insight into how plants adapt to seasonal changes
How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunesand implications for η⊕
One of the most significant advances by NASA's Mission was
the discovery of an abundant new population of highly irradiated planets with
sizes between the Earth and Neptune. Subsequent analysis showed that at ~1.5
Earth radii there is a transition from a population of predominantly rocky
super-Earths to non-rocky sub-Neptunes, which must have substantial volatile
envelopes. Determining the origin of these highly irradiated rocky planets will
be critical to our understanding of low-mass planet formation and the frequency
of potentially habitable Earth-like planets. These short-period rocky
super-Earths could simply be the stripped cores of sub-Neptunes, which have
lost their envelopes due to atmospheric photo-evaporation or other processes,
or they might instead be a separate population of inherently rocky planets,
which never had significant envelopes. Using models of atmospheric
photo-evaporation, we show that if most bare rocky planets are the evaporated
cores of sub-Neptunes then the transition radius should decrease as surveys
push to longer orbital periods, since on wider orbits only planets with smaller
less massive cores can be stripped. On the other hand, if most rocky planets
formed after their disks dissipate then these planets will have formed without
initial gaseous envelopes. In this case, we use N-body simulations of planet
formation to show that the transition radius should increase with orbital
period, due to the increasing solid mass available in their disks. Moreover, we
show that distinguishing between these two scenarios should be possible in
coming years with radial velocity follow-up of planets found by TESS. Finally,
we discuss the broader implications of this work for current efforts to measure
, which may yield significant overestimates if most
rocky planets form as evaporated cores.Comment: 8 pages, 4 figures, accepted for publication in the Monthly Notices
of the Royal Astronomical Societ
The JAK-STAT Pathway Controls Plasmodium vivax Load in Early Stages of Anopheles aquasalis Infection
Malaria affects 300 million people worldwide every year and 450,000 in Brazil. In coastal areas of Brazil, the main malaria vector is Anopheles aquasalis, and Plasmodium vivax is responsible for the majority of malaria cases in the Americas. Insects possess a powerful immune system to combat infections. Three pathways control the insect immune response: Toll, IMD, and JAK-STAT. Here we analyze the immune role of the A. aquasalis JAK-STAT pathway after P. vivax infection. Three genes, the transcription factor Signal Transducers and Activators of Transcription (STAT), the regulatory Protein Inhibitors of Activated STAT (PIAS) and the Nitric Oxide Synthase enzyme (NOS) were characterized. Expression of STAT and PIAS was higher in males than females and in eggs and first instar larvae when compared to larvae and pupae. RNA levels for STAT and PIAS increased 24 and 36 hours (h) after P. vivax challenge. NOS transcription increased 36 h post infection (hpi) while this protein was already detected in some midgut epithelial cells 24 hpi. Imunocytochemistry experiments using specific antibodies showed that in non-infected insects STAT and PIAS were found mostly in the fat body, while in infected mosquitoes the proteins were found in other body tissues. The knockdown of STAT by RNAi increased the number of oocysts in the midgut of A. aquasalis. This is the first clear evidence for the involvement of a specific immune pathway in the interaction of the Brazilian malaria vector A. aquasalis with P. vivax, delineating a potential target for the future development of disease controlling strategies
Advanced Technology Large-Aperture Space Telescope (ATLAST): A Technology Roadmap for the Next Decade
The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a set of
mission concepts for the next generation of UVOIR space observatory with a
primary aperture diameter in the 8-m to 16-m range that will allow us to
perform some of the most challenging observations to answer some of our most
compelling questions, including "Is there life elsewhere in the Galaxy?" We
have identified two different telescope architectures, but with similar optical
designs, that span the range in viable technologies. The architectures are a
telescope with a monolithic primary mirror and two variations of a telescope
with a large segmented primary mirror. This approach provides us with several
pathways to realizing the mission, which will be narrowed to one as our
technology development progresses. The concepts invoke heritage from HST and
JWST design, but also take significant departures from these designs to
minimize complexity, mass, or both.
Our report provides details on the mission concepts, shows the extraordinary
scientific progress they would enable, and describes the most important
technology development items. These are the mirrors, the detectors, and the
high-contrast imaging technologies, whether internal to the observatory, or
using an external occulter. Experience with JWST has shown that determined
competitors, motivated by the development contracts and flight opportunities of
the new observatory, are capable of achieving huge advances in technical and
operational performance while keeping construction costs on the same scale as
prior great observatories.Comment: 22 pages, RFI submitted to Astro2010 Decadal Committe