Characterization of microsatellite DNA markers in the Emei moustache toads (<Emphasis Type="Italic">Leptobrachium boringii</Emphasis>)

We report ten microsatellite loci in the Emei moustache toads, Leptobrachium boringii. Markers were obtained by screening a genomic library enriched for microsatellite motifs. Twenty-four individuals from one breeding site were examined and ten loci were polymorphic. The number of alleles per locus ranged from 3–9 with an average of 6.3/locus. The expected heterozygosity and observed heterozygosity ranged from 0.3874 to 0.8432, and from 0.4583 to 0.9167, respectively. Cross-species amplification was tested in a closely related species L. leishanensis. These markers will be useful in future studies on characterizing the mating system of the species.     

A non-human primate model for gluten sensitivity

Background and Aims

Gluten sensitivity is widespread among humans. For example, in celiac disease patients, an inflammatory response to dietary gluten leads to enteropathy, malabsorption, circulating antibodies against gluten and transglutaminase 2, and clinical symptoms such as diarrhea. There is a growing need in fundamental and translational research for animal models that exhibit aspects of human gluten sensitivity.

Methods

Using ELISA-based antibody assays, we screened a population of captive rhesus macaques with chronic diarrhea of non-infectious origin to estimate the incidence of gluten sensitivity. A selected animal with elevated anti-gliadin antibodies and a matched control were extensively studied through alternating periods of gluten-free diet and gluten challenge. Blinded clinical and histological evaluations were conducted to seek evidence for gluten sensitivity.

Results

When fed with a gluten-containing diet, gluten-sensitive macaques showed signs and symptoms of celiac disease including chronic diarrhea, malabsorptive steatorrhea, intestinal lesions and anti-gliadin antibodies. A gluten-free diet reversed these clinical, histological and serological features, while reintroduction of dietary gluten caused rapid relapse.

Conclusions

Gluten-sensitive rhesus macaques may be an attractive resource for investigating both the pathogenesis and the treatment of celiac disease.     

Sequential cell wall transformations in response to the induction of a pedicel abscission event in Euphorbia pulcherrima (poinsettia)

Alterations in the detection of cell wall polysaccharides during an induced abscission event in the pedicel of Euphorbia pulcherrima (poinsettia) have been determined using monoclonal antibodies and Fourier transform infrared (FT-IR) microspectroscopy. Concurrent with the appearance of a morphologically distinct abscission zone (AZ) on day 5 after induction, a reduction in the detection of the LM5 (1→4)-β- d -galactan and LM6 (1→5)-α- l -arabinan epitopes in AZ cell walls was observed. Prior to AZ activation, a loss of the (1→4)-β- d -galactan and (1→5)-α- l -arabinan epitopes was detected in cell walls distal to the AZ, i.e. in the to-be-shed organ. The earliest detected change, on day 2 after induction, was a specific loss of the LM5 (1→4)-β- d -galactan epitope from epidermal cells distal to the region where the AZ would form. Such alteration in the cell walls was an early, pre-AZ activation event. An AZ-associated de-esterification of homogalacturonan (HG) was detected in the AZ and distal area on day 7 after induction. The FT-IR analysis indicated that lignin and xylan were abundant in the AZ and that lower levels of cellulose, arabinose and pectin were present. Xylan and xyloglucan epitopes were detected in the cell walls of both the AZ and also the primary cell walls of the distal region at a late stage of the abscission process, on day 7 after induction. These observations indicate that the induction of an abscission event results in a temporal sequence of cell wall modifications involving the spatially regulated loss, appearance and/or remodelling of distinct sets of cell wall polymers.     

The effect of dynamic knee-extension exercise on patellar tendon and quadriceps femoris muscle glucose uptake in humans studied by positron emission tomography.

Both tendon and peritendinous tissue show evidence of metabolic activity, but the effect of acute exercise on substrate turnover is unknown. We therefore examined the influence of acute exercise on glucose uptake in the patellar and quadriceps tendons during dynamic exercise in humans. Glucose uptake was measured in five healthy men in the patellar and quadriceps tendons and the quadriceps femoris muscle at rest and during dynamic knee-extension exercise (25 W) using positron emission tomography and [18F]-2-fluoro-2-deoxy-D-glucose ([18F]FDG). Glucose uptake index was calculated by dividing the tissue activity with blood activity of [18F]FDG. Exercise increased glucose uptake index by 77% in the patellar tendon (from 0.30 +/- 0.09 to 0.51 +/- 0.16, P = 0.03), by 106% in the quadriceps tendon (from 0.37 +/- 0.15 to 0.75 +/- 0.36, P = 0.02), and by 15-fold in the quadriceps femoris muscle (from 0.31 +/- 0.11 to 4.5 +/- 1.7, P = 0.005). The exercise-induced increase in the glucose uptake in neither tendon correlated with the increase in glucose uptake in the quadriceps muscle (r = -0.10, P = 0.87 for the patellar tendon and r = -0.30, P = 0.62 for the quadriceps tendon). These results show that tendon glucose uptake is increased during exercise. However, the increase in tendon glucose uptake is less pronounced than in muscle and the increases are uncorrelated. Thus tendon glucose uptake is likely to be regulated by mechanisms independently of those regulating skeletal muscle glucose uptake.     

Bioreactor design for propagation of somatic embryos

Six identical bioreactors were constructed and built at the Agricultural University of Norway to provide optimal conditions for plant cell regeneration from cells into somatic embryos (clonal or somatic seeds). This was made possible through cooperation in COST87 by a European network in a working group on regeneration from plant cell cultures. The bioreactor design provides gentle stirring through a slow-speed stirrer that regularly changes direction of rotation to prevent quiet zones in the suspension in which cells can settle and grow. In addition, the oxygen is provided, bubble-free, through thin silicone tubing loops that are hanging loose, moving with the liquid to prevent cell growth on these tubes. We used off-the-shelf components whenever possible, to reduce the costs to a minimum, which was another aim of the construction. The result was a suite of relatively inexpensive computer-controlled bioreactors that could control temperature, oxygen, pH, stirrer speed and stirrer direction. In addition, we have provided different light spectral qualities by simple means of filtering the light. Using the present software, the parameters can be set up to alter every hour during the 24-h day/night cycle. All our cultures have improved growth in the bioreactors compared to identical cultures in Erlenmeyer flasks. The cultures used are: embryogenic cultures of carrot (Daucus carota), Norway spruce (Picea abies), birch (Betula pendula), cyclamen (Cyclamen persicum) and shoot cultures of Christmas begonia (Begonia x cheimantha). The paper also discusses recommendations for improvements of the current system for future revisions.     

Adult spawners: A critical period for subarctic Chinook salmon in a changing climate

Concurrent, distribution-wide abundance declines of some Pacific salmon species, including Chinook salmon (Oncorhynchus tshawytscha), highlights the need to understand how vulnerability at different life stages to climate stressors affects population dynamics and fisheries sustainability. Yukon River Chinook salmon stocks are among the largest subarctic populations, near the northernmost extent of the species range. Existing research suggests that Yukon River Chinook salmon population dynamics are largely driven by factors occurring between the adult spawner life stage and their offspring's first summer at sea (second year post-hatching). However, specific mechanisms sustaining chronic poor productivity are unknown, and there is a tremendous sense of urgency to understand causes, as declines of these stocks have taken a serious toll on commercial, recreational, and indigenous subsistence fisheries. Therefore, we leveraged multiple existing datasets spanning parent and juvenile stages of life history in freshwater and marine habitats. We analyzed environmental data in association with the production of offspring that survive to the marine juvenile stage (juveniles per spawner). These analyses suggest more than 45% of the variability in the production of juvenile Chinook salmon is associated with river temperatures or water discharge levels during the parent spawning migration. Over the past two decades, parents that experienced warmer water temperatures and lower discharge in the mainstem Yukon River produced fewer juveniles per spawning adult. We propose the adult spawner life stage as a critical period regulating population dynamics. We also propose a conceptual model that can explain associations between population dynamics and climate stressors using independent data focused on marine nutrition and freshwater heat stress. It is sobering to consider that some of the northernmost Pacific salmon habitats may already be unfavorable to these cold-water species. Our findings have immediate implications, given the common assumption that northern ranges of Pacific salmon offer refugia from climate stressors.     

Antibacterial Activity of Ronidazole

Ronidazole, a nitroimidazole that has in vivo antiparasitic and antimycoplasmal activity, also has some in vivo antibacterial activity.     

Sensitivity Analysis of the APEX Model for Assessing Sustainability of Switchgrass Grown for Biofuel Production in Central Texas

Crop simulation models are increasingly being used to understand the feasibility of large-scale cellulosic biofuel production along with the multi-dimensional impacts on environmental sustainability. However, how the uncertainty in model parameters impacts model performance for sustainability is unclear. In this case study, sensitivity analyses were conducted for three switchgrass sustainability metrics: total biomass production, nitrogen loss, and soil carbon change using the APEX (Agricultural Policy/Environmental eXtender) model. Fifteen out of the 45 parameters (25 crop growth (CROP) parameters and 20 additional model parameters (PARM)) were identified as influential for the three sustainability metrics for three lowland genotypes (WBC, AP13, and KAN) across two locations (Temple, TX, and Austin, TX). Our sensitivity results showed that parameter importance was not dependent on the genotypes but depended on the variables of interest, and differed only slightly between locations. Influential belowground-related CROP and PARM parameters were identified for each sustainability metric, indicating that belowground-related parameters are just as important as commonly measured aboveground CROP parameters. Further investigation of the linear or non-linear relationships and the two-way interactions between each of the individual influential parameters with the three sustainability metrics reflected the functions and characteristics within the APEX model and the interrelations among different processes. Strong interactions between the most influential parameters for total biomass, nitrogen loss, and soil carbon change also highlighted the importance of accurately setting these parameters. Identification of influential model parameters for switchgrass sustainability may help guide field measurements and provide further understanding of the interrelated processes in the APEX model. Furthermore, future field experiments can be designed to measure these influential parameters and understand the non-linear relationships identified between influential parameters and response variables. More accurate model parameterization will help improve APEX model performance and our understanding of the possible underlying physiological mechanisms.