Analysis of long-term observations of NOx and CO in megacities and application to constraining emissions inventories

Long-term atmospheric NOx/CO enhancement ratios in megacities provide evaluations of emission inventories. A fuel-based emission inventory approach that diverges from conventional bottom-up inventory methods explains 1970–2015 trends in NOx/CO enhancement ratios in Los Angeles. Combining this comparison with similar measurements in other U.S. cities demonstrates that motor vehicle emissions controls were largely responsible for U.S. urban NOx/CO trends in the past half century. Differing NOx/CO enhancement ratio trends in U.S. and European cities over the past 25 years highlights alternative strategies for mitigating transportation emissions, reflecting Europe's increased use of light-duty diesel vehicles and correspondingly slower decreases in NOx emissions compared to the U.S. A global inventory widely used by global chemistry models fails to capture these long-term trends and regional differences in U.S. and Europe megacity NOx/CO enhancement ratios, possibly contributing to these models' inability to accurately reproduce observed long-term changes in tropospheric ozone

A novel superfamily of bridge-like lipid transfer proteins

Lipid transfer proteins mediate nonvesicular transport of lipids at membrane contact sites to regulate the lipid composition of organelle membranes. Recently, a new type of bridge-like lipid transfer protein has emerged; these proteins contain a long hydrophobic groove and can mediate bulk transport of lipids between organelles. Here, we review recent insights into the structure of these proteins and identify a repeating modular unit that we propose to name the repeating β-groove (RBG) domain. This new structural understanding conceptually unifies all the RBG domain-containing lipid transfer proteins as members of an RBG protein superfamily. We also examine the biological functions of these lipid transporters in normal physiology and disease and speculate on the evolutionary origins of RBG proteins in bacteria

The bridge-like lipid transfer protein (BLTP) gene group: introducing new nomenclature based on structural homology indicating shared function.

The HUGO Gene Nomenclature Committee assigns unique symbols and names to human genes. The use of approved nomenclature enables effective communication between researchers, and there are multiple examples of how the usage of unapproved alias symbols can lead to confusion. We discuss here a recent nomenclature update (May 2022) for a set of genes that encode proteins with a shared repeating β-groove domain. Some of the proteins encoded by genes in this group have already been shown to function as lipid transporters. By working with researchers in the field, we have been able to introduce a new root symbol (BLTP, which stands for "bridge-like lipid transfer protein") for this domain-based gene group. This new nomenclature not only reflects the shared domain in these proteins, but also takes into consideration the mounting evidence of a shared lipid transport function

Retinal Expression of the <i>Drosophila eyes absent</i> Gene Is Controlled by Several Cooperatively Acting Cis-regulatory Elements

<div><p>The <i>eyes absent</i> (<i>eya</i>) gene of the fruit fly, <i>Drosophila melanogaster</i>, is a member of an evolutionarily conserved gene regulatory network that controls eye formation in all seeing animals. The loss of <i>eya</i> leads to the complete elimination of the compound eye while forced expression of <i>eya</i> in non-retinal tissues is sufficient to induce ectopic eye formation. Within the developing retina <i>eya</i> is expressed in a dynamic pattern and is involved in tissue specification/determination, cell proliferation, apoptosis, and cell fate choice. In this report we explore the mechanisms by which <i>eya</i> expression is spatially and temporally governed in the developing eye. We demonstrate that multiple cis-regulatory elements function cooperatively to control <i>eya</i> transcription and that spacing between a pair of enhancer elements is important for maintaining correct gene expression. Lastly, we show that the loss of <i>eya</i> expression in <i>sine oculis</i> (<i>so</i>) mutants is the result of massive cell death and a progressive homeotic transformation of retinal progenitor cells into head epidermis.</p></div

Allocation of distinct organ fates from a precursor field requires a shift in expression and function of gene regulatory networks

<div><p>A common occurrence in metazoan development is the rise of multiple tissues/organs from a single uniform precursor field. One example is the anterior forebrain of vertebrates, which produces the eyes, hypothalamus, diencephalon, and telencephalon. Another instance is the <i>Drosophila</i> wing disc, which generates the adult wing blade, the hinge, and the thorax. Gene regulatory networks (GRNs) that are comprised of signaling pathways and batteries of transcription factors parcel the undifferentiated field into discrete territories. This simple model is challenged by two observations. First, many GRN members that are thought to control the fate of one organ are actually expressed throughout the entire precursor field at earlier points in development. Second, each GRN can simultaneously promote one of the possible fates choices while repressing the other alternatives. It is therefore unclear how GRNs function to allocate tissue fates if their members are uniformly expressed and competing with each other within the same populations of cells. We address this paradigm by studying fate specification in the <i>Drosophila</i> eye-antennal disc. The disc, which begins its development as a homogeneous precursor field, produces a number of adult structures including the compound eyes, the ocelli, the antennae, the maxillary palps, and the surrounding head epidermis. Several selector genes that control the fates of the eye and antenna, respectively, are first expressed throughout the entire eye-antennal disc. We show that during early stages, these genes are tasked with promoting the growth of the entire field. Upon segregation to distinct territories within the disc, each GRN continues to promote growth while taking on the additional roles of promoting distinct primary fates and repressing alternate fates. The timing of both expression pattern restriction and expansion of functional duties is an elemental requirement for allocating fates within a single field.</p></div

Retinal progenitors within <i>so</i>^<i>1</i> mutants progressively transform into head epidermis.

<p>(A-M) Light microscope images of developing wild type, <i>so</i>^<i>1</i>, and <i>so</i>^<i>1</i>, <i>eya composite enhancer GAL4</i>, <i>UAS-p35</i> eye-antennal discs. Green = Otd and red = Cut. Expression of both <i>otd</i> and <i>cut</i> is de-repressed within the eye field of <i>so</i>^<i>1</i> mutant discs over the course of larval eye development. Although cell death has been blocked in the eye disc of <i>so</i>^<i>1</i> mutants by the caspase inhibitor p35, expression of <i>otd</i> and <i>cut</i> is still de-repressed in retinal progenitors. AEL = after egg laying. Anterior is to the right in all disc images. At least 30 discs were examined for each genotype at each developmental time point. Scale bar, 50μm.</p