Serrano (Sano) Functions with the Planar Cell Polarity Genes to Control Tracheal Tube Length

Epithelial tubes are the functional units of many organs, and proper tube geometry is crucial for organ function. Here, we characterize serrano (sano), a novel cytoplasmic protein that is apically enriched in several tube-forming epithelia in Drosophila, including the tracheal system. Loss of sano results in elongated tracheae, whereas Sano overexpression causes shortened tracheae with reduced apical boundaries. Sano overexpression during larval and pupal stages causes planar cell polarity (PCP) defects in several adult tissues. In Sano-overexpressing pupal wing cells, core PCP proteins are mislocalized and prehairs are misoriented; sano loss or overexpression in the eye disrupts ommatidial polarity and rotation. Importantly, Sano binds the PCP regulator Dishevelled (Dsh), and loss or ectopic expression of many known PCP proteins in the trachea gives rise to similar defects observed with loss or gain of sano, revealing a previously unrecognized role for PCP pathway components in tube size control

Evolving paradigms of aspen ecology and management: Impacts of stand condition and fire severity on vegetation dynamics

Quaking aspen (Populus tremuloides Michx.) comprises only a small fraction of western USA forests, yet contributes significant biological diversity and is considered by many to be the most important deciduous forest type in western North America. There is currently a high level of concern in the western United States as many seral aspen populations are declining in vigor due to drought, ungulate browsing, and lack of disturbance. It is also highly uncertain if aspen will successfully accommodate future climate warming via migration through seedling establishment, which has been assumed to be extremely rare. In recent years, fundamental assumptions concerning aspen clonal age, regeneration, and genetic diversity have been challenged, and these findings have important implications for management and persistence of aspen in western USA forests. In this study, we compared regeneration dynamics of aspen revitalization strategies (conifer removal and prescribed fire) to unplanned wildfires of low, moderate, and high severity in the Sierra Nevada, and related multiple components of pre-fire stand composition to post-fire aspen regeneration. To better understand the viability of aspen migration to accommodate future climate warming, we examined recent events of aspen seedling establishment. We found substantial evidence that greater disturbance severity yields increased aspen sprout density and growth rates, and that live conifer and/or dead aspen basal area in a stand before a fire reduces post fire sprout density. Additionally, we found evidence that aspen seedling establishment is more common than has been assumed, and represents a viable means for aspen migration. Future climate changes will present both challenges and opportunities for aspen. Increased temperatures and drought will stress existing populations, but increased high severity fire in forested areas, may provide opportunity for successful aspen migration and genet establishment. In addition to revitalizing existing aspen stands, future management goals should include the establishment of new stands in more suitable habitat

Evolving paradigms of aspen ecology and management: Impacts of stand condition and fire severity on vegetation dynamics

Quaking aspen (Populus tremuloides Michx.) comprises only a small fraction of western USA forests, yet contributes significant biological diversity and is considered by many to be the most important deciduous forest type in western North America. There is currently a high level of concern in the western United States as many seral aspen populations are declining in vigor due to drought, ungulate browsing, and lack of disturbance. It is also highly uncertain if aspen will successfully accommodate future climate warming via migration through seedling establishment, which has been assumed to be extremely rare. In recent years, fundamental assumptions concerning aspen clonal age, regeneration, and genetic diversity have been challenged, and these findings have important implications for management and persistence of aspen in western USA forests. In this study, we compared regeneration dynamics of aspen revitalization strategies (conifer removal and prescribed fire) to unplanned wildfires of low, moderate, and high severity in the Sierra Nevada, and related multiple components of pre-fire stand composition to post-fire aspen regeneration. To better understand the viability of aspen migration to accommodate future climate warming, we examined recent events of aspen seedling establishment. We found substantial evidence that greater disturbance severity yields increased aspen sprout density and growth rates, and that live conifer and/or dead aspen basal area in a stand before a fire reduces post fire sprout density. Additionally, we found evidence that aspen seedling establishment is more common than has been assumed, and represents a viable means for aspen migration. Future climate changes will present both challenges and opportunities for aspen. Increased temperatures and drought will stress existing populations, but increased high severity fire in forested areas, may provide opportunity for successful aspen migration and genet establishment. In addition to revitalizing existing aspen stands, future management goals should include the establishment of new stands in more suitable habitat

Quaking Aspen Regeneration Following Presribed Fire In Lassen Volcanic National Park, California, USA

Prescribed fire is commonly used for restoration, but the effects of reintroducing fire following a century of fire exclusion are unknown in many ecosystems. We assessed the effects of three prescribed fires, native ungulate browsing, and conifer competition on quaking aspen (Populus tremuloides Michx.) regeneration in four small groves (0.5 ha to 3.0 ha) in Lassen Volcanic National Park, California, USA, over an 11 yr period. The effects of fire on aspen regeneration density and height were variable within and among sites. Post-fire aspen regeneration density generally decreased with greater conifer basal area (rs = −0.73), but there was a wide range of aspen regeneration densities (4000 to 36 667 stems ha-1) at transects with no live conifers post-fire. The height of aspen regeneration increased as a function of increasing years-since-fire (1 yr to 11 yr), but heavy browsing by mule deer (Odocoileus hemionus Rafinesque) may alter future growth trajectories. Median percent of aspen regeneration browsed was high in burned (91%) and unburned (81%) transects. Only 7% (282 stems ha-1 to 333 stems ha-1) of post-fire aspen regeneration in 11- year old burns exceeded the height necessary to escape mule deer browsing (150 cm). Browsing may also be altering aspen growth form, such that multi-stemmed aspen regeneration was positively associated with proportion of aspen regeneration browsed. These four case studies indicate that the effects of prescribed fires on quaking aspen in the southern Cascade Range of northern California were highly variable and, when coupled with biotic factors (such as deer browsing and competing vegetation) and varying fire severity, fire may either benefit or hasten the decline of small aspen groves

Galanin-like peptide: neural regulator of energy homeostasis and reproduction.

Galanin-like peptide (GALP) was discovered in 1999 in the porcine hypothalamus and was found to be a 60 amino-acid neuropeptide. GALP shares sequence homology to galanin (1-13) in position 9-21 and can bind to and activate the three galanin receptor subtypes (GalR1-3). GALP-expressing cells are limited, and are mainly found in the arcuate nucleus of the hypothalamus (ARC) and the posterior pituitary. GALP-positive neurons in the ARC, project to several brain regions where they appear to make contact with several neuromodulators that are involved in the regulation of energy homeostasis and reproduction, anatomical evidence that suggests a role for GALP in these physiological functions. In support of this idea, GALP gene expression is regulated by several factors that reflect metabolic state including the metabolic hormones leptin and insulin, thyroid hormones, and blood glucose. Considerable evidence now exists to support the hypothesis that GALP has a role in the regulation of energy homeostasis and reproduction; and, that that GALP's role may be independent of the known galanin receptors. In this chapter we (1) provide an overview of the distribution of GALP, and discuss the potential relationship between GALP and other neuromodulators of energy homeostasis and reproduction, (2) discuss the metabolic factors that regulate GALP expression, (3) review the evidence for the role of GALP in energy homeostasis and reproduction, (4) discuss the potential downstream mediators and mechanisms underlying GALP's effects, and (5) discuss the possibility that GALP may mediate it's effects via an as yet unidentified GALP-specific receptor