43 research outputs found
A Mighty Small Heart: The Cardiac Proteome of Adult Drosophila melanogaster
Drosophila melanogaster is emerging as a powerful model system
for the study of cardiac disease. Establishing peptide and protein maps of the
Drosophila heart is central to implementation of protein
network studies that will allow us to assess the hallmarks of
Drosophila heart pathogenesis and gauge the degree of
conservation with human disease mechanisms on a systems level. Using a
gel-LC-MS/MS approach, we identified 1228 protein clusters from 145 dissected
adult fly hearts. Contractile, cytostructural and mitochondrial proteins were
most abundant consistent with electron micrographs of the
Drosophila cardiac tube. Functional/Ontological enrichment
analysis further showed that proteins involved in glycolysis,
Ca2+-binding, redox, and G-protein signaling, among other
processes, are also over-represented. Comparison with a mouse heart proteome
revealed conservation at the level of molecular function, biological processes
and cellular components. The subsisting peptidome encompassed 5169 distinct
heart-associated peptides, of which 1293 (25%) had not been identified in
a recent Drosophila peptide compendium. PeptideClassifier
analysis was further used to map peptides to specific gene-models. 1872 peptides
provide valuable information about protein isoform groups whereas a further 3112
uniquely identify specific protein isoforms and may be used as a
heart-associated peptide resource for quantitative proteomic approaches based on
multiple-reaction monitoring. In summary, identification of
excitation-contraction protein landmarks, orthologues of proteins associated
with cardiovascular defects, and conservation of protein ontologies, provides
testimony to the heart-like character of the Drosophila cardiac
tube and to the utility of proteomics as a complement to the power of genetics
in this growing model of human heart disease
Evolution of pathogenicity and sexual reproduction in eight Candida genomes
Candida species are the most common cause of opportunistic fungal infection worldwide. Here we report the genome sequences of six Candida species and compare these and related pathogens and non-pathogens. There are significant expansions of cell wall, secreted and transporter gene families in pathogenic species, suggesting adaptations associated with virulence. Large genomic tracts are homozygous in three diploid species, possibly resulting from recent recombination events. Surprisingly, key components of the mating and meiosis pathways are missing from several species. These include major differences at the mating-type loci (MTL); Lodderomyces elongisporus lacks MTL, and components of the a1/2 cell identity determinant were lost in other species, raising questions about how mating and cell types are controlled. Analysis of the CUG leucine-to-serine genetic-code change reveals that 99% of ancestral CUG codons were erased and new ones arose elsewhere. Lastly, we revise the Candida albicans gene catalogue, identifying many new genes.publishe
Transcription Factors Mat2 and Znf2 Operate Cellular Circuits Orchestrating Opposite- and Same-Sex Mating in Cryptococcus neoformans
Cryptococcus neoformans is a human fungal pathogen that undergoes a dimorphic transition from a unicellular yeast to multicellular hyphae during opposite sex (mating) and unisexual reproduction (same-sex mating). Opposite- and same-sex mating are induced by similar environmental conditions and involve many shared components, including the conserved pheromone sensing Cpk1 MAPK signal transduction cascade that governs the dimorphic switch in C. neoformans. However, the homeodomain cell identity proteins Sxi1α/Sxi2a encoded by the mating type locus that are essential for completion of sexual reproduction following cellâcell fusion during opposite-sex mating are dispensable for same-sex mating. Therefore, identification of downstream targets of the Cpk1 MAPK pathway holds the key to understanding molecular mechanisms governing the two distinct developmental fates. Thus far, homology-based approaches failed to identify downstream transcription factors which may therefore be species-specific. Here, we applied insertional mutagenesis via Agrobacterium-mediated transformation and transcription analysis using whole genome microarrays to identify factors involved in C. neoformans differentiation. Two transcription factors, Mat2 and Znf2, were identified as key regulators of hyphal growth during same- and opposite-sex mating. Mat2 is an HMG domain factor, and Znf2 is a zinc finger protein; neither is encoded by the mating type locus. Genetic, phenotypic, and transcriptional analyses of Mat2 and Znf2 provide evidence that Mat2 is a downstream transcription factor of the Cpk1 MAPK pathway whereas Znf2 functions as a more terminal hyphal morphogenesis determinant. Although the components of the MAPK pathway including Mat2 are not required for virulence in animal models, Znf2, as a hyphal morphology determinant, is a negative regulator of virulence. Further characterization of these elements and their target circuits will reveal genes controlling biological processes central to fungal development and virulence
Childrenâs and adolescentsâ rising animal-source food intakes in 1990â2018 were impacted by age, region, parental education and urbanicity
Animal-source foods (ASF) provide nutrition for children and adolescentsâ physical and cognitive development. Here, we use data from the Global Dietary Database and Bayesian hierarchical models to quantify global, regional and national ASF intakes between 1990 and 2018 by age group across 185 countries, representing 93% of the worldâs child population. Mean ASF intake was 1.9 servings per day, representing 16% of children consuming at least three daily servings. Intake was similar between boys and girls, but higher among urban children with educated parents. Consumption varied by age from 0.6 at <1 year to 2.5 servings per day at 15â19 years. Between 1990 and 2018, mean ASF intake increased by 0.5 servings per week, with increases in all regions except sub-Saharan Africa. In 2018, total ASF consumption was highest in Russia, Brazil, Mexico and Turkey, and lowest in Uganda, India, Kenya and Bangladesh. These findings can inform policy to address malnutrition through targeted ASF consumption programmes.publishedVersio
Incident type 2 diabetes attributable to suboptimal diet in 184 countries
The global burden of diet-attributable type 2 diabetes (T2D) is not well established. This risk assessment model estimated T2D incidence among adults attributable to direct and body weight-mediated effects of 11 dietary factors in 184 countries in 1990 and 2018. In 2018, suboptimal intake of these dietary factors was estimated to be attributable to 14.1 million (95% uncertainty interval (UI), 13.8â14.4 million) incident T2D cases, representing 70.3% (68.8â71.8%) of new cases globally. Largest T2D burdens were attributable to insufficient whole-grain intake (26.1% (25.0â27.1%)), excess refined rice and wheat intake (24.6% (22.3â27.2%)) and excess processed meat intake (20.3% (18.3â23.5%)). Across regions, highest proportional burdens were in central and eastern Europe and central Asia (85.6% (83.4â87.7%)) and Latin America and the Caribbean (81.8% (80.1â83.4%)); and lowest proportional burdens were in South Asia (55.4% (52.1â60.7%)). Proportions of diet-attributable T2D were generally larger in men than in women and were inversely correlated with age. Diet-attributable T2D was generally larger among urban versus rural residents and higher versus lower educated individuals, except in high-income countries, central and eastern Europe and central Asia, where burdens were larger in rural residents and in lower educated individuals. Compared with 1990, global diet-attributable T2D increased by 2.6 absolute percentage points (8.6 million more cases) in 2018, with variation in these trends by world region and dietary factor. These findings inform nutritional priorities and clinical and public health planning to improve dietary quality and reduce T2D globally.publishedVersio
Kepler K2 Campaign 9: II. First space-based discovery of an exoplanet using microlensing
We report on the discovery of a bound exoplanetary microlensing event from a
blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9).
K2-2016-BLG-0005Lb is a densely sampled, binary caustic-crossing microlensing
event with caustic entry and exit points that are resolved in the K2C9 data,
enabling the lens-source relative proper motion to be measured. We have fitted
a binary microlens model to the K2 dataset, and to simultaneous observations
from the Optical Gravitational Lensing Experiment (OGLE-IV),
Canada-France-Hawaii Telescope (CFHT), Microlensing Observations in
Astrophysics (MOA-2), the Korean Microlensing Telescope Network (KMTNet), and
the United Kingdom InfraRed Telescope (UKIRT). Whilst the ground-based data
only sparsely sample the binary caustic, they provide a clear detection of
parallax that allows us to break completely the microlensing
mass-position-velocity degeneracy and measure the planet's mass directly. We
find a host mass of and a planetary mass of . The system lies at a distance of kpc from
Earth towards the Galactic bulge. The projected physical separation of the
planet from its host is found to be au which, for circular
orbits, corresponds to au and period yr, making K2-2016-BLG-0005Lb a close Jupiter analogue. Though
previous exoplanet microlensing events have included space-based data, this
event is the first bound microlensing exoplanet to be discovered from
space-based data. Even through a space telescope not designed for microlensing
studies, this result highlights the advantages for exoplanet microlensing
discovery that come from continuous, high-cadence temporal sampling that is
possible from space. (Abridged).Comment: 17 pages. Submitted to MNRA
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<i>Kepler K2</i> Campaign 9: II. First space-based discovery of an exoplanet using microlensing
We present K2-2016-BLG-0005Lb, a densely sampled, planetary binary caustic-crossing microlensing event found from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is the first bound microlensing exoplanet discovered from space-based data. The event has caustic entry and exit points that are resolved in the K2C9 data, enabling the lensâsource relative proper motion to be measured. We have fitted a binary microlens model to the Kepler data, and to simultaneous observations from multiple ground-based surveys. Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing massâpositionâvelocity degeneracy and measure the planetâs mass directly. We find a host mass of 0.58 ± 0.04Mâ and a planetary mass of 1.1 ± 0.1MJ. The system lies at a distance of 5.2 ± 0.2 kpc from Earth towards the Galactic bulge, more than twice the distance of the previous most distant planet found by Kepler. The sky-projected separation of the planet from its host is found to be 4.2 ± 0.3 au which, for circular orbits, deprojects to a host separation au and orbital period yr. This makes K2-2016-BLG-0005MLb a close Jupiter analogue orbiting a low-mass host star. According to current planet formation models, this system is very close to the host mass threshold below which Jupiters are not expected to form. Upcoming space-based exoplanet microlensing surveys by NASAâs Nancy Grace Roman Space Telescope and, possibly, ESAâs Euclid mission, will provide demanding tests of current planet formation models
Cryptococcus neoformans Virulence Gene Discovery through Insertional Mutagenesis
Insertional mutagenesis was applied to Cryptococcus neoformans to identify genes associated with virulence attributes. Using biolistic transformation, we generated 4,300 nourseothricin (NAT)-resistant strains, of which 590 exhibited stable resistance. We focused on mutants with defects in established virulence factors and identified two with reduced growth at 37°C, four with reduced production of the antioxidant pigment melanin, and two with an increased sensitivity to nitric oxide (NO). The NAT insertion and mutant phenotypes were genetically linked in five of eight mutants, and the DNA flanking the insertions was characterized. For the strains with altered growth at 37°C and altered melanin production, mutations were in previously uncharacterized genes, while the two NO-sensitive strains bore insertions in the flavohemoglobin gene FHB1, whose product counters NO stress. Because of the frequent instability of nourseothricin resistance associated with biolistic transformation, Agrobacterium-mediated transformation was tested. This transkingdom DNA delivery approach produced 100% stable nourseothricin-resistant transformants, and three melanin-defective strains were identified from 576 transformants, of which 2 were linked to NAT in segregation analysis. One of these mutants contained a T-DNA insertion in the promoter of the LAC1 (laccase) gene, which encodes a key enzyme required for melanin production, while the second contained an insertion in the promoter of the CLC1 gene, encoding a voltage-gated chloride channel. Clc1 and its homologs are required for ion homeostasis, and in their absence Cu(+) transport into the secretory pathway is compromised, depriving laccase and other Cu(+)-dependent proteins of their essential cofactor. The NAT resistance cassette was optimized for cryptococcal codon usage and GC content and was then used to disrupt a mitogen-activated protein kinase gene, a predicted gene, and two putative chloride channel genes to analyze their contributions to fungal physiology. Our findings demonstrate that both insertional mutagenesis methods can be applied to gene identification, but Agrobacterium-mediated transformation is more efficient and generates exclusively stable insertion mutations