4,646 research outputs found
Age-related shifts in bacterial diversity in a reef coral
This study investigated the relationship between microbial communities in differently sized colonies of the massive coral Coelastrea aspera at Phuket, Thailand where colony size could be used as a proxy for age. Results indicated significant differences between the bacterial diversity (ANOSIM, R = 0.76, p = 0.001) of differently sized colonies from the same intertidal reef habitat. Juvenile and small colonies (28 cm mean diam). Bacterial diversity increased in a step-wise pattern from juvenilessmallmedium colonies, which was then followed by a slight decrease in the two largest size classes. These changes appear to resemble a successional process which occurs over time, similar to that observed in the ageing human gut. Furthermore, the dominant bacterial ribotypes present in the tissues of medium and large sized colonies of C. aspera, (such as Halomicronema, an Oscillospira and an unidentified cyanobacterium) were also the dominant ribotypes found within the endolithic algal band of the coral skeleton; a result providing some support for the hypothesis that the endolithic algae of corals may directly influence the bacterial community present in coral tissues.Barbara Brown recieved funding from the Leverhulme Trust [www.leverhulme.ac.uk]; Grant number: EM-2013-058. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Studies on the chemical preservation of water samples
During the storage of water samples collected from the sea, rivers or lakes, increased bacterial activity causes changes in the organic, oxygen, carbon dioxide, ammonia, nitrate or phosphate content or the H-ion concentration of the water (Waksman and Carey, 1935 ; ZoBell and Anderson, 1936)...
Methods for preparing dry, partially articulated skeletons of osteichthyans, with notes on making ridewood dissections of the cranial skeleton
Journal ArticleWe describe methods for preparing dry skeletons of virtually any osteichthyan species with a well-ossified skeleton, including very large specimens (e.g., > 1 m Megalops atlanticus). Our approach differs from those conventionally used to prepare skeletons of tetrapods in that (1) fairly complete dissection of the specimen is required at the outset of processing; and (2) we use an alcohol dehydration step to rapidly dry the specimen. Similar techniques can be used to prepare well-calcified chondrichthyan skeletons. We also outline the steps for making Ridewood dissections of the skull. Dry, partially articulated skeletons prepared by these methods can be stored indefinitely in acid-free containers in an environmentally controlled space (21 ± 6 3 ±; Rh = 40% ± 5%) in pest-proof specimen cases. Although a truism of anatomical research is that you cannot learn everything from studying one specimen or one type of preparation, partially articulated dry skeletons are useful for research ranging from phylogenetic investigations to age and growth analyses to functional morphology, making them of great and lasting value to any collection
Liver transplantation for type IV glycogen storage disease
TYPE IV glycogen storage disease is a rare autosomal recessive disorder (also called Andersen's disease1 or amylopectinosis) in which the activity of branching enzyme alpha-1, 4-glucan: alpha-1, 4-glucan 6-glucosyltransferase is deficient in the liver as well as in cultured skin fibroblasts and other tissues.2,3 This branching enzyme is responsible for creating branch points in the normal glycogen molecule. In the relative or absolute absence of this enzyme, an insoluble and irritating form of glycogen, an amylopectin-like polysaccharide that resembles plant starch, accumulates in the cells. The amylopectin-like form is less soluble than normal glycogen, with longer outer and inner chains. © 1991, Massachusetts Medical Society. All rights reserved
Discovery of an ultramassive pulsating white dwarf
We announce the discovery of the most massive pulsating hydrogen-atmosphere
(DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the
optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) =
9.08 +/- 0.06, which corresponds to a mass of 1.20 +/- 0.03 Msun. Stellar
evolution models indicate that the progenitor of such a high-mass WD endured a
stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of
pulsations in GD 518 thus offers the first opportunity to probe the interior of
a WD with a possible oxygen-neon core. Such a massive WD should also be
significantly crystallized at this temperature. The star exhibits
multi-periodic luminosity variations at timescales ranging from roughly 425-595
s and amplitudes up to 0.7%, consistent in period and amplitude with the
observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode
pulsations driven by a hydrogen partial ionization zone. Successfully
unraveling both the total mass and core composition of GD 518 provides a unique
opportunity to investigate intermediate-mass stellar evolution, and can
possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in
turn constrains SNe Ia progenitor systems.Comment: 5 pages, 3 figures, Astrophysical Journal Letters, 771, L2 (2013
The Equal Rights Amendment: A Constitutional Basis for Equal Rights for Women
In the present legal structure, some laws exclude women from legalrights, opportunities, or responsibilities. Some are framed as legislationconferring special benefits, or protection, on women. Others create orperpetuate a separate legal status without indicating on their facewhether the position of women ranks below, or above, the positionof men. Many of the efforts to create a separate legal status for womenstem from a good faith attempt to advance the interests of women.Nevertheless, the preponderant effect has been to buttress the socialand economic subordination of women
Maternal plasma DHA levels increase prior to 29 days post-LH surge in women undergoing frozen embryo transfer: a prospective, observational study of human pregnancy
Context:
Docosahexaenoic acid (DHA) is an important fatty acid required for neurological development but its importance during early fetal neurological organogenesis is unknown.
Objective:
To assess plasma fatty acid changes in early pregnancy in women undergoing natural cycle-frozen embryo transfer as a means of achieving accurately-timed periconceptual sampling.
Design:
Women undergoing frozen embryo transfer were recruited and serial fasting blood samples were taken pre-luteinising hormone (LH) surge, and at days 18, 29 and 45 post-LH surge and fatty acids were analysed using gas chromatography.
Setting:
Assisted Conception Unit, Glasgow Royal Infirmary, Scotland
Main outcome measures:
Plasma fatty acid concentrations, influence of twin pregnancies on DHA plasma concentration.
Results:
In pregnant women, there was a rapid, early increase in the maternal rate of change of plasma DHA concentration observed by 29 days post-LH surge (mean±SD, from 0.1±1.3 to 1.6±2.9 nmol DHA per mL plasma per day). This early pressure to increase plasma DHA concentration was further emphasised in twin pregnancies where the increase in DHA concentration over 45 days was two-fold higher than in singleton pregnancies (mean±SD increase, 74±39 nmol/mL versus 36±40 nmol/mL). An index of delta-6 desaturase activity increased 30% and positively correlated with the rate of change of DHA concentration between day 18 and 29-post LH surge (R-squared adjusted = 41%, P=0.0002). DHA was the only fatty acid with a continual accelerated increase in plasma concentration and a positive incremental area under the curve (mean±SD, 632±911 nmol/mL x day) over the first 45 days of gestation.
Conclusions:
An increase in maternal plasma DHA concentration is initiated in human pregnancy prior to neural tube closure which occurs at 28 days' gestation
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