Biotic interactions in Antarctic terrestrial ecosystems: Are they a factor?

Antarctic terrestrial ecosystems are noted for their relative simplicity and limited trophic structure. In this context, knowledge of biotic interactions in structuring terrestrial soil communities would seem beneficial from a theoretical perspective as well as from a conservation perspective. Unfortunately, although biotic interactions are generally seen as being insignificant in these unique ecosystems, this view is based upon few explicit studies and very little is known of the role that biotic interactions may play. Accordingly, we review our current understanding of these interactions, including analogues from other appropriate ecosystems. On the basis of this review, we conclude that: (1) Antarctic terrestrial systems are predominantly abiotically-driven systems; and (2) a network of manipulative field and laboratory experiments are needed for establishing any role for biotic interactions in structuring Antarctic soil environments.     

How milk does the world good: vernacular sustainability and alternative food systems in post-socialist Europe

Scholarly debates on sustainable consumption have generally overlooked alternative agro-food networks in the economies outside of Western Europe and North America. Building on practice-based theories, this article focuses on informal raw milk markets in post-socialist Lithuania to examine how such alternative systems emerge and operate in the changing political, social, and economic contexts. It makes two contributions to the scholarship on sustainable consumption. In considering semi-subsistence practices and poverty-driven consumption, this article argues for a richer, more critical, and inclusive theory of sustainability that takes into consideration vernacular forms of exchange and approaches poor consumers as subjects of global history. Second, it revisits practice theories and infrastructures of consumption approaches to consider ruptures, discontinuities, and historical change in infrastructures as a way to account for inequalities and experiences of marginalization.     

Toward metrological traceability for DNA fragment ratios in GM quantification. 3. Suitability of DNA calibrants studied with a MON 810 corn model

The quantification of GMOs by real-time PCR relies on an external calibrant. In this paper the suitability of two DNA calibrants, genomic DNA from plant leaves and plasmidic DNA, was investigated. The PCR efficiencies, the correlation coefficients of the calibration curves, and the ratios between PCR efficiencies of transgenic and endogenous sequences were compared for both calibrants using 59 data sets produced by 43 laboratories. There were no significant differences between plasmidic and genomic DNA except for the PCR efficiencies of the calibration curves for the transgene of the construct-specific real-time PCR method. In the GM system investigated, PCR efficiencies of plasmidic calibrants were slightly closer to the PCR efficiencies observed for the unknowns than those of the genomic DNA calibrant. Therefore, plasmidic DNA was the more suitable calibrant for the PCR measurements on genomic DNA extracted from MON 810 seeds. It is shown that plasmidic DNA is an appropriate choice for the calibration of measurements of MON 810 corn with respect to the DNA copy number ratio.     

Stereospecific analysis of phospholipid classes in skeletal muscle from rats fed different fat sources

The fatty acid (FA) and dimethylacetal profiles of the sn-1 and sn-2 positions of different phospholipid (PL) classes from skeletal muscle of rats as affected by dietary FA profiles were studied. Rats were fed either a control diet, an olive oil-enriched diet, or a sunflower oil-enriched diet. The FA composition of both positions of the studied PL classes was affected by diet to different extents. The FA composition of the sn-2 position of phosphatidylserine was the most influenced by diet, while phosphatidylinositol was less affected by dietary modification. The FA profile of phosphatidylcholine reflected consumed FA better than any other studied PL. Thus, olive oil rats showed higher oleic acid (C18:1 n-9) contents in both positions of phosphatidylcholine, and sunflower oil rats had higher proportions of arachidonic acid (C20:4 n-6) in the sn-1 position of this PL class. Dimethylacetals were scarcely affected by diet, and only the dimethylacetal composition of phosphatidylethanolamine showed significant modifications.     

Effects of graded doses of propofol for anesthesia induction on cardiovascular parameters and intraocular pressures in normal dogs

ObjectiveTo determine the effects of graded doses of propofol on cardiovascular parameters and intraocular pressures (IOP) in normal dogs.Study designProspective, randomized, modified Latin square, cross-over experimental study.AnimalsEleven adult random-source dogs weighing 20.2 ± 5.7 kg.MethodsThere were three treatment groups: propofol 8 mg kg^?1 intravenous (IV) until loss of jaw tone (Group P), propofol until loss of jaw tone +20% (Group P20), and propofol until loss of jaw tone +50% (Group P50). Atracurium 0.1 mg kg^?1 IV was administered in all treatments immediately after the propofol. All dogs received the three treatments in a randomized order, with at least a one week interval between treatments. Direct arterial blood pressure and IOP by applanation tonometry were obtained at baseline, after 5 minutes of pre-oxygenation (before induction), before, and after intubation. Blood gas samples were obtained at baseline, after pre-oxygenation, and before intubation.ResultsThere was no significant difference in IOP readings at any time point among groups. The IOP was significantly higher before intubation versus before induction in all three groups. There was a significantly smaller change in systolic, mean (MAP), and diastolic (DAP) arterial pressures in the P50 group compared with the P group after intubation. There was a significantly smaller change in MAP and DAP in the P50 group compared with the P20 group after intubation. The increase in CO₂ from before induction to before intubation was significantly greater in the P50 group than in the P or P20 groups.Conclusions and clinical relevanceGraded doses of propofol did not affect the increase in IOP observed with propofol induction in normal dogs. Higher doses of propofol are of no apparent additional benefit in animals who cannot tolerate an abrupt increase in IOP but may be of benefit in dogs who cannot tolerate an abrupt increase in blood pressure accompanying orotracheal intubation.     

Dyscalculia: from brain to education

Recent research in cognitive and developmental neuroscience is providing a new approach to the understanding of dyscalculia that emphasizes a core deficit in understanding sets and their numerosities, which is fundamental to all aspects of elementary school mathematics. The neural bases of numerosity processing have been investigated in structural and functional neuroimaging studies of adults and children, and neural markers of its impairment in dyscalculia have been identified. New interventions to strengthen numerosity processing, including adaptive software, promise effective evidence-based education for dyscalculic learners.     

An aneuploid mouse strain carrying human chromosome 21 with Down syndrome phenotypes

Aneuploidies are common chromosomal defects that result in growth and developmental deficits and high levels of lethality in humans. To gain insight into the biology of aneuploidies, we manipulated mouse embryonic stem cells and generated a trans-species aneuploid mouse line that stably transmits a freely segregating, almost complete human chromosome 21 (Hsa21). This "transchromosomic" mouse line, Tc1, is a model of trisomy 21, which manifests as Down syndrome (DS) in humans, and has phenotypic alterations in behavior, synaptic plasticity, cerebellar neuronal number, heart development, and mandible size that relate to human DS. Transchromosomic mouse lines such as Tc1 may represent useful genetic tools for dissecting other human aneuploidies.     

Preliminary studies on the salt tolerance and sodium relations of common ornamental plants

The salinity tolerance of local varieties of five ornamental species Begonia, Chlorophytum, Coleus, Geranium, and Mesembryanthemum was assessed in a medium term pot experiment. The pot grown plants were watered for 50 days with water salinised at 5 dS/m and 15 dS/m and a tap water control. Based on growth parameters and on survival, Begonia was classified as salt sensitive, Coleus, Geranium, and Chlorophtytum as moderately tolerant, and Mesembry‐ anthemum as salt tolerant. Shoot sodium (Na) content was measured at the end of the experiment. It appears that the restriction of Na entry to the shoot is linked to salinity tolerance. Mesembryanthemum seems to be able to control Na entry to the shoot at water salinities above 5 ds/m.