252 research outputs found
Prionochelys matutina Zangerl, 1953 (Testudines: Pan-Cheloniidae) from the Late Cretaceous of the United States and the evolution of epithecal ossifications in marine turtles
Background Many neritic to nearshore species of marine adapted turtle from the Late Cretaceous of North America are thought to represent the stem lineage of Cheloniidae but due to fragmentary holotypes, low total specimen counts, and resultantly incomplete morphological character suites, are routinely placed either within or outside of crown group Chelonioidea leaving their precise cladistic affinities uncertain. Despite this systematic ambiguity, the referral of these species to either the stem of Cheloniidae or Chelonioidea belies the critical importance of these taxa in any investigation into the origins of extant marine turtles. The adequate incorporation of these species into phylogenetic studies requires the formal description of relatively complete specimens, particularly those possessing associated cranial and post-cranial material. Methods Remarkably complete fossil specimens of several adult and juvenile marine turtles from the Mooreville Chalk and Eutaw Formations (Alabama, USA) are formally described and assigned to Prionochelys matutina. This material provides new information into the anatomy, ontogeny, and cladistic affinities of the species. A phylogenetic hypothesis for Late Cretaceous marine turtles is then generated through the consilience of stratigraphic, morphological, and molecular data. Results Phylogenetic analysis places Prionochelys matutina on the stem of Cheloniidae as a member of a monophyletic clade with other putative pan-cheloniids, including Ctenochelys stenoporus, Ctenochelys acris, Peritresius martini, and Peritresius ornatus. The members of this clade possess incipient secondary palates, pronounced carapacial and plastral fontanelles at all stages of development, and are characterized by the presence of superficial ossifications at the apices of the neural keel elevations along the dorsal midline of the carapace. Discussion The epithecal osteoderms dorsal to the neural series (epineurals) found in Ctenochelyidae are unique among turtles. The presence of epineurals in ctenochelyid turtles shows that epithecal ossifications arose independently in both leatherback (Dermochelyidae) and hard-shelled (Cheloniidae) marine turtles. Whether or not the epineurals of Ctenochelyidae are homologous with the dermal ossicles comprising the carapace of Dermochelys coriacea remains untested however, histological thin sectioning of dermochelyid and ctenochelyd epithecal elements may reveal meaningful information in future studies
Investigation of International Space Station Major Constituent Analyzer Anomalous ORU 02 Performance
The Major Constituent Analyzer (MCA) is a mass spectrometer based system that measures the major atmospheric constituents on the International Space Station. In 2011, two MCA ORU 02 analyzer assemblies experienced premature on-orbit failures. These failures were determined to be the result of off-nominal ion source filament performance. Recent product improvements to ORU 02 designed to improve the lifetime of the ion pump also constrained the allowable tuning criteria for the ion source filaments. This presentation describes the filament failures as well as the corrective actions implemented to preclude such failures in the future
An International Quiet Ocean Experiment
Author Posting. © Oceanography Society, 2011. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 24, no. 2 (2011): 174–181, doi:10.5670/oceanog.2011.37.The effect of noise on marine life is one of the big unknowns of current marine science. Considerable evidence exists that the human contribution to ocean noise has increased during the past few decades: human noise has become the dominant component of marine noise in some regions, and noise is directly correlated with the increasing industrialization of the ocean. Sound is an important factor in the lives of many marine organisms, and theory and increasing observations suggest that human noise could be approaching levels at which negative effects on marine life may be occurring. Certain species already show symptoms of the effects of sound. Although some of these effects are acute and rare, chronic sublethal effects may be more prevalent, but are difficult to measure. We need to identify the thresholds of such effects for different species and be in a position to predict how increasing anthropogenic sound will add to the effects. To achieve such predictive capabilities, the Scientific Committee on Oceanic Research (SCOR) and the Partnership for Observation of the Global Oceans (POGO) are developing an International Quiet Ocean Experiment (IQOE), with the objective of coordinating the international research community to both quantify the ocean soundscape and examine the functional relationship between sound and the viability of key marine organisms. SCOR and POGO will convene an open science meeting to gather community input on the important research, observations, and modeling activities that should be included in IQOE
Protein phosphatase 2A plays a crucial role in Giardia lamblia differentiation
Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Molecular and Biochemical Parasitology 152 (2007): 80-89, doi:10.1016/j.molbiopara.2006.12.001.The ability of Giardia lamblia to undergo two distinct differentiations in
response to physiologic stimuli is central to its pathogenesis. The giardial
cytoskeleton changes drastically during encystation and excystation. However, the
signal transduction pathways mediating these transformations are poorly
understood. We tested the hypothesis that PP2A, a highly conserved
serine/threonine protein phosphatase, might be important in giardial differentiation.
We found that in vegetatively growing trophozoites, gPP2A-C protein localizes to
basal bodies/centrosomes, and to cytoskeletal structures unique to Giardia: the
ventral disk, and the dense rods of the anterior, posterior-lateral, and caudal
flagella. During encystation, gPP2A-C protein disappears from only the anterior
flagellar dense rods. During excystation, gPP2A-C localizes to the cyst wall in
excysting cysts but is not found in the wall of cysts with emerging excyzoites.
Transcriptome and immunoblot analyses indicated that gPP2A-C mRNA and
protein are upregulated in mature cysts and during the early stage of excystation
that models passage through the host stomach. Stable expression of gPP2A-C
antisense RNA did not affect vegetative growth, but strongly inhibited the
formation of encystation secretory vesicles (ESV) and water-resistant cysts.
Moreover, the few cysts that formed were highly defective in excystation.
Thus, gPP2A-C localizes to universal cytoskeletal structures and to
structures unique to Giardia. It is also important for encystation and excystation,
crucial giardial transformations that entail entry into and exit from dormancy.This work was funded
by NIH grants GM61896, AI51687, AI42488, and DK35108. Dr. A.G. McArthur was
supported by NIH grant AI51089 and the Marine Biological Laboratory’s Program
in Global Infectious Diseases, funded by the Ellison Medical Foundation
Robust Tests for Additive Gene-Environment Interaction in Case-Control Studies Using Gene-Environment Independence
There have been recent proposals advocating the use of additive gene-environment interaction instead of the widely used multiplicative scale, as a more relevant public health measure. Using gene-environment independence enhances statistical power for testing multiplicative interaction in case-control studies. However, under departure from this assumption, substantial bias in the estimates and inflated type I error in the corresponding tests can occur. In this paper, we extend the empirical Bayes (EB) approach previously developed for multiplicative interaction, which trades off between bias and efficiency in a data-adaptive way, to the additive scale. An EB estimator of the relative excess risk due to interaction is derived, and the corresponding Wald test is proposed with a general regression setting under a retrospective likelihood framework. We study the impact of gene-environment association on the resultant test with case-control data. Our simulation studies suggest that the EB approach uses the gene-environment independence assumption in a data-adaptive way and provides a gain in power compared with the standard logistic regression analysis and better control of type I error when compared with the analysis assuming gene-environment independence. We illustrate the methods with data from the Ovarian Cancer Association Consortium.Multiple funders listed on paper
Temporal allocation of foraging effort in female Australian fur seals (Arctocephalus pusillus doriferus)
Across an individual\u27s life, foraging decisions will be affected by multiple intrinsic and extrinsic drivers that act at differing timescales. This study aimed to assess how female Australian fur seals allocated foraging effort and the behavioural changes used to achieve this at three temporal scales: within a day, across a foraging trip and across the final six months of the lactation period. Foraging effort peaked during daylight hours (57% of time diving) with lulls in activity just prior to and after daylight. Dive duration reduced across the day (196 s to 168 s) but this was compensated for by an increase in the vertical travel rate (1500–1600 m•h−1) and a reduction in postdive duration (111–90 s). This suggests physiological constraints (digestive costs) or prey availability may be limiting mean dive durations as a day progresses. During short trips (<2.9 d), effort remained steady at 55% of time diving, whereas, on long trips (>2.9 d) effort increased up to 2–3 d and then decreased. Dive duration decreased at the same rate in short and long trips, respectively, before stabilising (long trips) between 4–5 d. Suggesting that the same processes (digestive costs or prey availability) working at the daily scale may also be present across a trip. Across the lactation period, foraging effort, dive duration and vertical travel rate increased until August, before beginning to decrease. This suggests that as the nutritional demands of the suckling pup and developing foetus increase, female effort increases to accommodate this, providing insight into the potential constraints of maternal investment in this specie
Thromboxane biosynthesis in cancer patients and its inhibition by aspirin: a sub-study of the Add-Aspirin trial
BACKGROUND: Pre-clinical models demonstrate that platelet activation is involved in the spread of malignancy. Ongoing clinical trials are assessing whether aspirin, which inhibits platelet activation, can prevent or delay metastases. METHODS: Urinary 11-dehydro-thromboxane B2 (U-TXM), a biomarker of in vivo platelet activation, was measured after radical cancer therapy and correlated with patient demographics, tumour type, recent treatment, and aspirin use (100 mg, 300 mg or placebo daily) using multivariable linear regression models with log-transformed values. RESULTS: In total, 716 patients (breast 260, colorectal 192, gastro-oesophageal 53, prostate 211) median age 61 years, 50% male were studied. Baseline median U-TXM were breast 782; colorectal 1060; gastro-oesophageal 1675 and prostate 826 pg/mg creatinine; higher than healthy individuals (~500 pg/mg creatinine). Higher levels were associated with raised body mass index, inflammatory markers, and in the colorectal and gastro-oesophageal participants compared to breast participants (P < 0.001) independent of other baseline characteristics. Aspirin 100 mg daily decreased U-TXM similarly across all tumour types (median reductions: 77-82%). Aspirin 300 mg daily provided no additional suppression of U-TXM compared with 100 mg. CONCLUSIONS: Persistently increased thromboxane biosynthesis was detected after radical cancer therapy, particularly in colorectal and gastro-oesophageal patients. Thromboxane biosynthesis should be explored further as a biomarker of active malignancy and may identify patients likely to benefit from aspirin
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Global chemical effects of the microbiome include new bile-acid conjugations
A mosaic of cross-phylum chemical interactions occurs between all metazoans and their microbiomes. A number of molecular families that are known to be produced by the microbiome have a marked effect on the balance between health and disease. Considering the diversity of the human microbiome (which numbers over 40,000 operational taxonomic units), the effect of the microbiome on the chemistry of an entire animal remains underexplored. Here we use mass spectrometry informatics and data visualization approaches to provide an assessment of the effects of the microbiome on the chemistry of an entire mammal by comparing metabolomics data from germ-free and specific-pathogen-free mice. We found that the microbiota affects the chemistry of all organs. This included the amino acid conjugations of host bile acids that were used to produce phenylalanocholic acid, tyrosocholic acid and leucocholic acid, which have not previously been characterized despite extensive research on bile-acid chemistry. These bile-acid conjugates were also found in humans, and were enriched in patients with inflammatory bowel disease or cystic fibrosis. These compounds agonized the farnesoid X receptor in vitro, and mice gavaged with the compounds showed reduced expression of bile-acid synthesis genes in vivo. Further studies are required to confirm whether these compounds have a physiological role in the host, and whether they contribute to gut diseases that are associated with microbiome dysbiosis
Estrogen Receptor Beta rs1271572 Polymorphism and Invasive Ovarian Carcinoma Risk: Pooled Analysis within the Ovarian Cancer Association Consortium
The association of ovarian carcinoma risk with the polymorphism rs1271572 in the estrogen receptor beta (ESR2) gene was examined in 4946 women with primary invasive ovarian carcinoma and 6582 controls in a pooled analysis of ten case-control studies within the Ovarian Cancer Association Consortium (OCAC). All participants were non-Hispanic white women. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression adjusted for site and age. Women with the TT genotype were at increased risk of ovarian carcinoma compared to carriers of the G allele (OR = 1.10; 95%; CI: 1.01–1.21; p = 0.04); the OR was 1.09 (CI: 0.99–1.20; p = 0.07) after excluding data from the center (Hawaii) that nominated this SNP for OCAC genotyping A stronger association of rs1271572 TT versus GT/GG with risk was observed among women aged ≤50 years versus older women (OR = 1.35; CI: 1.12–1.62; p = 0.002; p for interaction = 0.02) that remained statistically significant after excluding Hawaii data (OR = 1.34; CI: 1.11–1.61; p = 0.009). No heterogeneity of the association was observed by study, menopausal status, gravidity, parity, use of contraceptive or menopausal hormones, tumor histological type, or stage at diagnosis. This pooled analysis suggests that rs1271572 might influence the risk of ovarian cancer, in particular among younger women
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