316 research outputs found
Animal Models of Zika Virus Sexual Transmission
ZIKV was first identified in the 1940s as a mosquito-borne virus; however, sexual transmission, which is uncommon for arboviruses, was demonstrated more than 60 years later. Tissue culture and animal models have allowed scientists to study how this transmission is possible. Immunocompromised mice infected with ZIKV had high viral loads in their testes, and infection of immunocompetent female mice was achieved following intravaginal inoculation or inoculation via mating with an infected male. These mouse studies lead researchers to investigate the individual components of the male reproductive system. In cell culture and mouse models, ZIKV can persist in Sertoli and germ cells of the testes and epithelial cells in the epididymis, which may lead to sexual transmission even after ZIKV has been cleared from other tissues. ZIKV has also been studied in nonhuman primates (NHPs), which appears to mimic the limited human epidemiological data, with low rates of symptomatic individuals and similar clinical signs. Although refinement is needed, these animal models have proven to be key in ZIKV research and continue to help uncovering the mechanisms of sexual transmission. This review will focus on the animal models used to elucidate the mechanisms of sexual transmission and persistence of flaviviruses
Spatio-temporal patterns of beaked whale echolocation signals in the North Pacific.
At least ten species of beaked whales inhabit the North Pacific, but little is known about their abundance, ecology, and behavior, as they are elusive and difficult to distinguish visually at sea. Six of these species produce known species-specific frequency modulated (FM) echolocation pulses: Baird's, Blainville's, Cuvier's, Deraniyagala's, Longman's, and Stejneger's beaked whales. Additionally, one described FM pulse (BWC) from Cross Seamount, Hawai'i, and three unknown FM pulse types (BW40, BW43, BW70) have been identified from almost 11 cumulative years of autonomous recordings at 24 sites throughout the North Pacific. Most sites had a dominant FM pulse type with other types being either absent or limited. There was not a strong seasonal influence on the occurrence of these signals at any site, but longer time series may reveal smaller, consistent fluctuations. Only the species producing BWC signals, detected throughout the Pacific Islands region, consistently showed a diel cycle with nocturnal foraging. By comparing stranding and sighting information with acoustic findings, we hypothesize that BWC signals are produced by ginkgo-toothed beaked whales. BW43 signal encounters were restricted to Southern California and may be produced by Perrin's beaked whale, known only from Californian waters. BW70 signals were detected in the southern Gulf of California, which is prime habitat for Pygmy beaked whales. Hubb's beaked whale may have produced the BW40 signals encountered off central and southern California; however, these signals were also recorded off Pearl and Hermes Reef and Wake Atoll, which are well south of their known range
Complete genome sequence of Syntrophobacter fumaroxidans strain (MPOB(T)).
Syntrophobacter fumaroxidans strain MPOB(T) is the best-studied species of the genus Syntrophobacter. The species is of interest because of its anaerobic syntrophic lifestyle, its involvement in the conversion of propionate to acetate, H2 and CO2 during the overall degradation of organic matter, and its release of products that serve as substrates for other microorganisms. The strain is able to ferment fumarate in pure culture to CO2 and succinate, and is also able to grow as a sulfate reducer with propionate as an electron donor. This is the first complete genome sequence of a member of the genus Syntrophobacter and a member genus in the family Syntrophobacteraceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,990,251 bp long genome with its 4,098 protein-coding and 81 RNA genes is a part of the Microbial Genome Program (MGP) and the Genomes to Life (GTL) Program project
Functionally specialized junctions between endothelial cells of lymphatic vessels
Recirculation of fluid and cells through lymphatic vessels plays a key role in normal tissue homeostasis, inflammatory diseases, and cancer. Despite recent advances in understanding lymphatic function (Alitalo, K., T. Tammela, and T.V. Petrova. 2005. Nature. 438:946–953), the cellular features responsible for entry of fluid and cells into lymphatics are incompletely understood. We report the presence of novel junctions between endothelial cells of initial lymphatics at likely sites of fluid entry. Overlapping flaps at borders of oak leaf–shaped endothelial cells of initial lymphatics lacked junctions at the tip but were anchored on the sides by discontinuous button-like junctions (buttons) that differed from conventional, continuous, zipper-like junctions (zippers) in collecting lymphatics and blood vessels. However, both buttons and zippers were composed of vascular endothelial cadherin (VE-cadherin) and tight junction–associated proteins, including occludin, claudin-5, zonula occludens–1, junctional adhesion molecule–A, and endothelial cell–selective adhesion molecule. In C57BL/6 mice, VE-cadherin was required for maintenance of junctional integrity, but platelet/endothelial cell adhesion molecule–1 was not. Growing tips of lymphatic sprouts had zippers, not buttons, suggesting that buttons are specialized junctions rather than immature ones. Our findings suggest that fluid enters throughout initial lymphatics via openings between buttons, which open and close without disrupting junctional integrity, but most leukocytes enter the proximal half of initial lymphatics
Low-Intrusion Techniques and Sensitive Information Management for Warhead Counting and Verification: FY2012 Annual Report
Progress in the second year of this project is described by the series of technical reports and manuscripts that make up the content of this report. These documents summarize successes in our goals to develop our robust image-hash templating and material-discrimination techniques and apply them to test image data
Evolutionary Dynamics of Human Rotaviruses: Balancing Reassortment with Preferred Genome Constellations
Group A human rotaviruses (RVs) are a major cause of severe gastroenteritis in infants and young children. Yet, aside from the genes encoding serotype antigens (VP7; G-type and VP4; P-type), little is known about the genetic make-up of emerging and endemic human RV strains. To gain insight into the diversity and evolution of RVs circulating at a single location over a period of time, we sequenced the eleven-segmented, double-stranded RNA genomes of fifty-one G3P[8] strains collected from 1974 to 1991 at Children's Hospital National Medical Center, Washington, D. C. During this period, G1P[8] strains typically dominated, comprising on average 56% of RV infections each year in hospitalized children. A notable exception was in the 1976 and 1991 winter seasons when the incidence of G1P[8] infections decreased dramatically, a trend that correlated with a significant increase in G3P[8] infections. Our sequence analysis indicates that the 1976 season was characterized by the presence of several genetically distinct, co-circulating clades of G3P[8] viruses, which contained minor but significant differences in their encoded proteins. These 1976 lineages did not readily exchange gene segments with each other, but instead remained stable over the course of the season. In contrast, the 1991 season contained a single major clade, whose genome constellation was similar to one of the 1976 clades. The 1991 clade may have gained a fitness advantage after reassorting with as of yet unidentified RV strain(s). This study reveals for the first time that genetically distinct RV clades of the same G/P-type can co-circulate and cause disease. The findings from this study also suggest that, although gene segment exchange occurs, most reassortant strains are replaced over time by lineages with preferred genome constellations. Elucidation of the selective pressures that favor maintenance of RVs with certain sets of genes may be necessary to anticipate future vaccine needs
Genetic and seasonal determinants of vitamin D status in Confederated Salish and Kootenai Tribes (CSKT) participants
Background: Vitamin D is a hormone produced in the skin upon ultraviolet B (UVB) radiation. Vitamin D is a crucial regulator of calcium and phosphate levels for bone mineralization and other physiological roles. Vitamin D levels vary globally in human populations due to genetics, geography, and other demographic factors. It is estimated that 20-85 % of the variability in vitamin D levels is driven by genetic variation. To improve our understanding of contributors to vitamin D levels, we conducted a candidate-gene study in partnership with the Confederated Salish and Kootenai Tribes (CSKT).
Methods: We recruited 472 CSKT study participants on the Flathead Reservation in Montana. Demographic factors included age, BMI, and gender (185 male and 287 female; ≥ 18 years old). Genomic DNA and plasma were isolated from whole blood. We sequenced 14 vitamin D regulatory candidate genes: CASR, CUBN, CYP2R1, CYP3A4,CYP24A1, CYP27B1, DHCR7, GC, RXRA, RXRB, RXRG, SULT2A1, UGT1A4, and VDR. We also measured plasma levels of vitamin D and vitamin D metabolites by liquid chromatography/mass-spectrometry (LC/MS), including the clinical marker of vitamin D status, 25-hydroxyvitamin D3 [25(OH)D3]. We tested demographic factors as well as common and rare genetic variants for statistical associations with vitamin D levels using bioinformatics software and R statistical programming language code.
Results: We identified 7,370 total genetic variants with 8% (n = 585) of them being novel. We identified 60 genetic variants that may be of clinical significance (disease associated or predicted to influence medication response). Vitamin D levels were below sufficiency [25(OH)D3 + 25(OH)D2 levels \u3c 20 ng/mL] in 56 % of CSKT participants across the year. We observed seasonal vitamin D and metabolite level fluctuations in a seasonal, sinusoidal statistical model with peak concentrations in June – August and trough concentrations in December – February. In linear regression analysis, we found that age, BMI, season, and 5 variants in CUBN and CYP3A4 were significantly associated with 25(OH)D3 concentration (p-value\u3c 0.05). In logistic regression, we found that 4 variants in CUBN, CYP3A4, and UGT1A4 were associated with 25(OH)D sufficiency status [25(OH)D3 + 25(OH)D2 levels of 20 ng/mL] (p-value\u3c 0.05). Multivariate linear regression analysis revealed that genetic variation alone explained ~13% of the variability in 25(OH)D3 concentration in CSKT participants. Genetic variation and environmental factors together explained ~23 % of the variability in 25(OH)D3 concentration in CSKT participants. It is likely that genetic variation in additional genes and other environmental factors (e.g., dietary vitamin D intake) that were not included in this study explain the remaining variability in 25(OH)D3 concentration.
Conclusion: This research addresses the need for increased inclusion of American Indian and Alaska Natives in precision medicine health research. We are the first to describe the contribution of season and genetics to vitamin D levels in an American Indian population. Our next steps will be to use these findings to perform mechanistic studies and develop interventional strategies for the CSKT people
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.Comment: 49 pages, 16 figures, accepted by A
The SDSS-III Baryon Oscillation Spectroscopic Survey: Quasar Target Selection for Data Release Nine
The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-year
spectroscopic survey of 10,000 deg^2, achieved first light in late 2009. One of
the key goals of BOSS is to measure the signature of baryon acoustic
oscillations in the distribution of Ly-alpha absorption from the spectra of a
sample of ~150,000 z>2.2 quasars. Along with measuring the angular diameter
distance at z\approx2.5, BOSS will provide the first direct measurement of the
expansion rate of the Universe at z > 2. One of the biggest challenges in
achieving this goal is an efficient target selection algorithm for quasars over
2.2 < z < 3.5, where their colors overlap those of stars. During the first year
of the BOSS survey, quasar target selection methods were developed and tested
to meet the requirement of delivering at least 15 quasars deg^-2 in this
redshift range, out of 40 targets deg^-2. To achieve these surface densities,
the magnitude limit of the quasar targets was set at g <= 22.0 or r<=21.85.
While detection of the BAO signature in the Ly-alpha absorption in quasar
spectra does not require a uniform target selection, many other astrophysical
studies do. We therefore defined a uniformly-selected subsample of 20 targets
deg^-2, for which the selection efficiency is just over 50%. This "CORE"
subsample will be fixed for Years Two through Five of the survey. In this paper
we describe the evolution and implementation of the BOSS quasar target
selection algorithms during the first two years of BOSS operations. We analyze
the spectra obtained during the first year. 11,263 new z>2.2 quasars were
spectroscopically confirmed by BOSS. Our current algorithms select an average
of 15 z > 2.2 quasars deg^-2 from 40 targets deg^-2 using single-epoch SDSS
imaging. Multi-epoch optical data and data at other wavelengths can further
improve the efficiency and completeness of BOSS quasar target selection.
[Abridged]Comment: 33 pages, 26 figures, 12 tables and a whole bunch of quasars.
Submitted to Ap
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