34 research outputs found
Daam1a mediates asymmetric habenular morphogenesis by regulating dendritic and axonal outgrowth
Although progress has been made in resolving the genetic pathways that specify neuronal asymmetries in the brain, little is known about genes that mediate the development of structural asymmetries between neurons on left and right. In this study, we identify daam1a as an asymmetric component of the signalling pathways leading to asymmetric morphogenesis of the habenulae in zebrafish. Daam1a is a member of the Formin family of actin-binding proteins and the extent of Daam1a expression in habenular neuron dendrites mirrors the asymmetric growth of habenular neuropil between left and right. Local loss and gain of Daam1a function affects neither cell number nor subtype organisation but leads to a decrease or increase of neuropil, respectively. Daam1a therefore plays a key role in the asymmetric growth of habenular neuropil downstream of the pathways that specify asymmetric cellular domains in the habenulae. In addition, Daam1a mediates the development of habenular efferent connectivity as local loss and gain of Daam1a function impairs or enhances, respectively, the growth of habenular neuron terminals in the interpeduncular nucleus. Abrogation of Daam1a disrupts the growth of both dendritic and axonal processes and results in disorganised filamentous actin and α-tubulin. Our results indicate that Daam1a plays a key role in asymmetric habenular morphogenesis mediating the growth of dendritic and axonal processes in dorsal habenular neurons
Adapting forest health assessments to changing perspectives on threats – a case example from Sweden
A revised Swedish forest health assessment
system is presented. The assessment system
is composed of several interacting components
which target information needs for strategic
and operational decision making and accommodate
a continuously expanding knowledge base.
The main motivation for separating information
for strategic and operational decision making is
that major damage outbreaks are often scattered
throughout the landscape. Generally, large-scale
inventories (such as national forest inventories)
cannot provide adequate information for mitigation
measures. In addition to broad monitoring
programs that provide time-series information on
known damaging agents and their effects, there
is also a need for local and regional inventories
adapted to specific damage events. While information
for decision making is the major focus of
the health assessment system, the system also contributes
to expanding the knowledge base of forest
conditions. For example, the integrated monitoring
programs provide a better understanding of
ecological processes linked to forest health. The
new health assessment system should be able to
respond to the need for quick and reliable information
and thus will be an important part of the
future monitoring of Swedish forests
Identification of erythroferrone as an erythroid regulator of iron metabolism
Recovery from blood loss requires a greatly enhanced supply of iron to support expanded erythropoiesis. After hemorrhage, suppression of the iron-regulatory hormone hepcidin allows increased iron absorption and mobilization from stores. We identified a new hormone, erythroferrone (ERFE), which mediates hepcidin suppression during stress erythropoiesis. ERFE is produced by erythroblasts in response to erythropoietin. ERFE-deficient mice fail to suppress hepcidin rapidly after hemorrhage and exhibit a delay in recovery from blood loss. ERFE expression is greatly increased in murine Hbb(Th3/+) thalassemia intermedia where it contributes to the suppression of hepcidin and systemic iron overload characteristic of this disease