Lipid allocation in late-stage barnacle larvae from subtropical and temperate waters

The transition of planktonic late-stage barnacle larvae to a benthic life requires enough energy to power settlement and metamorphosis, and may be compromised by food limitation during early ontogeny. We carried out a comparative study to better understand the larval physiology of space-monopolizing barnacles exposed to contrasting regimes of primary productivity: Chthamalus bisinuatus under a meso-oligotrophic regime on the southeastern coast of Brazil, and C. montagui under a highly productive regime on the southwestern coast of the British Isles. We used an index based on lipid composition—the triacylglycerol (TAG) to phospholipid (PL) ratio—to characterize lipid allocation (energy/structure) in the tissues of cyprid larvae and anticipated depleted TAG reserves in cyprids from less productive waters. Despite the considerably different levels of primary productivity between subtropical (1.31 ± 0.4 mg chl a m-3) and temperate waters (3.09 ± 1.2 mg chl a m-3), TAG/PL ratio and settlement success were comparable for C. bisinuatus and C. montagui. Lipid allocation of daily cohorts was also comparable for both chthamalids, with cyprids equally storing TAG reserves (≥50% of total lipid content). This points to an energetic threshold below which nauplii cannot develop to a cyprid and/or selection for lipid accumulation under poor trophic conditions. We highlight the challenges of directly relating estimates of primary productivity with food supply and larval physiological status, as lower chl a concentrations do not necessarily indicate food limitation for barnacle nauplii. We propose a conceptual model to clarify the process of lipid allocation (energetic to structural lipids) in the tissues of cyprid larvae

Resident and Facility Factors Associated with Rehospitalization from Skilled Nursing Facilities

ABSTRACT Older adults often require short-term nursing home care after an acute hospital stay to receive skilled nursing or rehabilitation services. Rehospitalization after a skilled nursing facility (SNF) admission is a potential indicator of poor nursing home quality that is associated with substantial risks of complications and increased costs of care. This study examined resident and facility factors associated with 30-day rehospitalizations during a one-year study period from SNFs in New Mexico. The Minimum Data Set 3.0 was used to explore resident factors and Nursing Home Compare data was used for facility factors. Among residents admitted to the SNF from an acute care hospital for 30-days or fewer (n = 2,370), 317 (13.4%) were rehospitalized. In bivariate analyses, several resident characteristics during their SNF stay were associated with significantly increased probability of rehospitalization, including an unhealed pressure ulcer, delirium, shortness of breath, and oxygen use. In multivariable models, the relative odds of rehospitalization were increased in those who identified as American Indian or Alaska Native, residents who rejected care, those with symptoms of delirium, and those who required greater mobility assistance with activities of daily living. The relative odds of rehospitalization were decreased in women and in residents with dementia. However, overall, none of the models improved prediction of rehospitalization. The Nursing Home Compare 5-star rating showed a decline in nurse staff ratings from 2015 to 2016. Policy implications include value-based penalties linked to high SNF rehospitalization rates and policies focused on reducing Medicare costs, while improving nursing home quality

The Canada-UK Deep Submillimetre Survey: The Survey of the 14-hour field

We have used SCUBA to survey an area of 50 square arcmin, detecting 19 sources down to a 3sigma sensitivity limit of 3.5 mJy at 850 microns. We have used Monte-Carlo simulations to assess the effect of source confusion and noise on the SCUBA fluxes and positions, finding that the fluxes of sources in the SCUBA surveys are significantly biased upwards and that the fraction of the 850 micron background that has been resolved by SCUBA has been overestimated. The radio/submillmetre flux ratios imply that the dust in these galaxies is being heated by young stars rather than AGN. We have used simple evolution models based on our parallel SCUBA survey of the local universe to address the major questions about the SCUBA sources: (1) what fraction of the star formation at high redshift is hidden by dust? (2) Does the submillimetre luminosity density reach a maximum at some redshift? (3) If the SCUBA sources are proto-ellipticals, when exactly did ellipticals form? However, we show that the observations are not yet good enough for definitive answers to these questions. There are, for example, acceptable models in which 10 times as much high-redshift star formation is hidden by dust as is seen at optical wavelengths, but also acceptable ones in which the amount of hidden star formation is less than that seen optically. There are acceptable models in which very little star formation occurred before a redshift of three (as might be expected in models of hierarchical galaxy formation), but also ones in which 30% of the stars have formed by this redshift. The key to answering these questions are measurements of the dust temperatures and redshifts of the SCUBA sources.Comment: 41 pages (latex), 17 postscript figures, to appear in the November issue of the Astronomical Journa

Comparison of Pittsburgh compound B and florbetapir in cross-sectional and longitudinal studies.

IntroductionQuantitative in vivo measurement of brain amyloid burden is important for both research and clinical purposes. However, the existence of multiple imaging tracers presents challenges to the interpretation of such measurements. This study presents a direct comparison of Pittsburgh compound B-based and florbetapir-based amyloid imaging in the same participants from two independent cohorts using a crossover design.MethodsPittsburgh compound B and florbetapir amyloid PET imaging data from three different cohorts were analyzed using previously established pipelines to obtain global amyloid burden measurements. These measurements were converted to the Centiloid scale to allow fair comparison between the two tracers. The mean and inter-individual variability of the two tracers were compared using multivariate linear models both cross-sectionally and longitudinally.ResultsGlobal amyloid burden measured using the two tracers were strongly correlated in both cohorts. However, higher variability was observed when florbetapir was used as the imaging tracer. The variability may be partially caused by white matter signal as partial volume correction reduces the variability and improves the correlations between the two tracers. Amyloid burden measured using both tracers was found to be in association with clinical and psychometric measurements. Longitudinal comparison of the two tracers was also performed in similar but separate cohorts whose baseline amyloid load was considered elevated (i.e., amyloid positive). No significant difference was detected in the average annualized rate of change measurements made with these two tracers.DiscussionAlthough the amyloid burden measurements were quite similar using these two tracers as expected, difference was observable even after conversion into the Centiloid scale. Further investigation is warranted to identify optimal strategies to harmonize amyloid imaging data acquired using different tracers

ISO Observations of the 53W002 Group at 6.7 microns: In Search of the Oldest Stellar Populations at z=2.4

We present a deep ISO observation at 6.7 microns of the 53W002 group of galaxies and AGN at z=2.4. This approximately samples the emitted K band. The faint, blue star-forming objects are not detected, as expected from their very blue color across the emitted optical and UV. However, 53W002 itself is detected at the 3-sigma level, with an emitted V-K color appropriate for a population formed starting at z=3.6-7.0 with most likely value z=4.7. This fits with shorter-wavelength data suggesting that the more massive members of this group, which may all host AGN, began star formation earlier in deeper potential wells than the compact Lyman-alpha emission objects. Two foreground galaxies are detected, as well as several stars. One additional 6.7-micron source closely coincides with an optically faint galaxy, potentially at z=2-3. The overall source counts are consistent with other ISO deep fields.Comment: In press, PASP (August 2004

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (\u3ci\u3eCrotalus scutulatus\u3c/i\u3e)

Snake venoms represent an enriched system for investigating the evolutionary processes that lead to complex and dynamic trophic adaptations. It has long been hypothesized that natural selection may drive geographic variation in venom composition, yet previous studies have lacked the population genetic context to examine these patterns. We leverage range-wide sampling of Mojave Rattlesnakes (Crotalus scutulatus) and use a combination of venom, morphological, phylogenetic, population genetic, and environmental data to characterize the striking dichotomy of neurotoxic (Type A) and hemorrhagic (Type B) venoms throughout the range of this species. We find that three of the four previously identified major lineages within C. scutulatus possess a combination of Type A, Type B, and a ‘mixed’ Type A + B venom phenotypes, and that fixation of the two main venom phenotypes occurs on a more fine geographic scale than previously appreciated. We also find that Type A + B individuals occur in regions of inferred introgression, and that this mixed phenotype is comparatively rare. Our results support strong directional local selection leading to fixation of alternative venom phenotypes on a fine geographic scale, and are inconsistent with balancing selection to maintain both phenotypes within a single population. Our comparisons to biotic and abiotic factors further indicate that venom phenotype correlates with fang morphology and climatic variables. We hypothesize that links to fang morphology may be indicative of co-evolution of venom and other trophic adaptations, and that climatic variables may be linked to prey distributions and/or physiology, which in turn impose selection pressures on snake venoms

From cacti to carnivores: Improved phylotranscriptomic sampling and hierarchical homology inference provide further insight into the evolution of Caryophyllales

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143660/1/ajb21069.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143660/2/ajb21069_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143660/3/ajb21069-sup-0002-AppendixS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143660/4/ajb21069-sup-0005-AppendixS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143660/5/ajb21069-sup-0001-AppendixS1.pd

Transcriptome Remodeling Contributes to Epidemic Disease Caused by the Human Pathogen Streptococcus pyogenes

For over a century, a fundamental objective in infection biology research has been to understand the molecular processes contributing to the origin and perpetuation of epidemics. Divergent hypotheses have emerged concerning the extent to which environmental events or pathogen evolution dominates in these processes. Remarkably few studies bear on this important issue. Based on population pathogenomic analysis of 1,200 Streptococcus pyogenes type emm89 infection isolates, we report that a series of horizontal gene transfer events produced a new pathogenic genotype with increased ability to cause infection, leading to an epidemic wave of disease on at least two continents. In the aggregate, these and other genetic changes substantially remodeled the transcriptomes of the evolved progeny, causing extensive differential expression of virulence genes and altered pathogen-host interaction, including enhanced immune evasion. Our findings delineate the precise molecular genetic changes that occurred and enhance our understanding of the evolutionary processes that contribute to the emergence and persistence of epidemically successful pathogen clones. The data have significant implications for understanding bacterial epidemics and for translational research efforts to blunt their detrimental effects. IMPORTANCE The confluence of studies of molecular events underlying pathogen strain emergence, evolutionary genetic processes mediating altered virulence, and epidemics is in its infancy. Although understanding these events is necessary to develop new or improved strategies to protect health, surprisingly few studies have addressed this issue, in particular, at the comprehensive population genomic level. Herein we establish that substantial remodeling of the transcriptome of the human-specific pathogen Streptococcus pyogenes by horizontal gene flow and other evolutionary genetic changes is a central factor in precipitating and perpetuating epidemic disease. The data unambiguously show that the key outcome of these molecular events is evolution of a new, more virulent pathogenic genotype. Our findings provide new understanding of epidemic disease.Peer reviewe