Tetrahymena thermophila and Candida albicans Group I intron-derived ribozymes can catalyze the trans-excision-splicing reaction

Group I intron-derived ribozymes can catalyze a variety of non-native reactions. For the trans-excision-splicing (TES) reaction, an intron-derived ribozyme from the opportunistic pathogen Pneumocystis carinii catalyzes the excision of a predefined region from within an RNA substrate with subsequent ligation of the flanking regions. To establish TES as a general ribozyme-mediated reaction, intron-derived ribozymes from Tetrahymena thermophila and Candida albicans, which are similar to but not the same as that from Pneumocystis, were investigated for their propensity to catalyze the TES reaction. We now report that the Tetrahymena and Candida ribozymes can catalyze the excision of a single nucleotide from within their ribozyme-specific substrates. Under the conditions studied, the Tetrahymena and Candida ribozymes, however, catalyze the TES reaction with lower yields and rates [Tetrahymena (kobs) = 0.14/min and Candida (kobs) = 0.34/min] than the Pneumocystis ribozyme (kobs = 3.2/min). The lower yields are likely partially due to the fact that the Tetrahymena and Candida catalyze additional reactions, separate from TES. The differences in rates are likely partially due to the individual ribozymes ability to effectively bind their 3′ terminal guanosines as intramolecular nucleophiles. Nevertheless, our results demonstrate that group I intron-derived ribozymes are inherently able to catalyze the TES reaction

Temperature-sensitive anthocyanin production in flowers of Plantago lanceolata

Flower color in the weedy perennial Plantago lanceolata is phenotypically plastic. Darker flowers are produced at cooler ambient temperatures, and circumstantial evidence suggests that this is adaptive. The goal of this project was to investigate the chemical basis for the color plasticity. To test the hypothesis that increased anthocyanin production at low temperatures underlies the plasticity, extracts of P. lanceolata flowers produced at warm and cool temperatures were analyzed using UV/visible spectrophotometry coupled with mass spectrometry. Mass spectrometry allowed us to compare relative abundances of individual anthocyanins. Seventeen anthocyanins, derived from both cyanidin and delphinidin branches of the anthocyanin biosynthetic pathway, were detected. Most of these significantly increased in abundance under cool conditions. Genotypes differed significantly in anthocyanin levels and in their sensitivity to temperature change. Genotypes that showed greater floral color plasticity tended to show also greater temperature sensitivity with respect to anthocyanin production. Data suggest that the temperature regulation of the anthocyanin biosynthetic pathway occurs both upstream and downstream of the divergence of the cyanidin and delphinidin branches. The degree of temperature sensitivity, i.e. phenotypic plasticity, appears to be controlled downstream, whereas the overall temperature effect appears to be controlled upstream

Behavioural Salinity Preferences of Juvenile Green Sturgeon \u3ci\u3eAcipenser medirostris\u3c/i\u3e Acclimated to Fresh Water and Full-Strength Salt Water

To quantify the salinity preference of juvenile green sturgeon Acipenser medirostris, two groups of A. medirostris [140 days post hatch (dph); total length (LT) 38.0–52.5 cm] were acclimated to either near fresh water (mean ± S.E. salinity = 3.2 ± 0.6) or full-strength salt water (34.1 ± 1.2) over 8 weeks. Following acclimation, the two groups were divided into experimental and control groups, where experimental A. medirostris from both freshwater and saltwater acclimations were individually introduced (200–220 dph) into a rectangular salinity-preference flume (maximum salinity gradient: 5–33). Control A. medirostris were presented with only their acclimation water (fresh water or salt water) on both sides of the flume. It was demonstrated that A. medirostris acclimated to both salt water and fresh water spent a significantly greater amount of time on the side of the testing area with the highest salinity concentration (P \u3c 0.05 and P \u3c 0.001, respectively) while control A. medirostris spent an equal amount of time on each side of the flume. These findings indicate that juvenile A. medirostris are not only capable of detecting salt water within the first year of their lives but perhaps are actively seeking out saline environments as they move through a watershed. Establishing A. medirostris salinity preferences provides a better understanding of the early life history of this threatened species, shedding light on possible outmigration timing

Aging and Endothelial Progenitor Cell Telomere Length in Healthy Men

BACKGROUND: Telomere length declines with age in mature endothelial cells and is thought to contribute to endothelial dysfunction and atherogenesis. Bone marrow-derived circulating endothelial progenitor cells (EPCs) are critical to vascular health as they contribute to both reendothelialization and neovascularization. We tested the hypothesis that EPC telomere length decreases with age in healthy adult humans. METHODS: Peripheral blood samples were collected from 40 healthy, non-obese, sedentary men: 12 young (age 21-34 years), 12 middle-aged (43-55 years) and 16 older (57-68 years). Putative EPCs were isolated from peripheral blood mononuclear cells and telomere length was determined using genomic DNA preparation and Southern hybridization techniques. RESULTS: EPC telomere length (base pairs) was approximately 20% (p=0.01) lower in the older (8492+523 bp) compared to the middle-aged (10,565+572 bp) and young (10,205+501 bp) men. Of note, there was no difference in EPC telomere length between the middle-aged and young men. CONCLUSIONS: These results demonstrate that EPC telomere length declines with age in healthy, sedentary men. Interestingly, telomere length was well preserved in the middle-aged compared to young men, suggesting that EPC telomere shortening occurs after the age of 55 years

Tsunami-Related Data: A Review of Available Repositories Used in Scientific Literature

Various organizations and institutions store large volumes of tsunami-related data, whose availability and quality should benefit society, as it improves decision making before the tsunami occurrence, during the tsunami impact, and when coping with the aftermath. However, the existing digital ecosystem surrounding tsunami research prevents us from extracting the maximum benefit from our research investments. The main objective of this study is to explore the field of data repositories providing secondary data associated with tsunami research and analyze the current situation. We analyze the mutual interconnections of references in scientific studies published in the Web of Science database, governmental bodies, commercial organizations, and research agencies. A set of criteria was used to evaluate content and searchability. We identified 60 data repositories with records used in tsunami research. The heterogeneity of data formats, deactivated or nonfunctional web pages, the generality of data repositories, or poor dataset arrangement represent the most significant weak points. We outline the potential contribution of ontology engineering as an example of computer science methods that enable improvements in tsunami-related data management

The instability of Alexander-McTague crystals and its implication for nucleation

We show that the argument of Alexander and McTague, that the bcc crystalline structure is favored in those crystallization processes where the first order character is not too pronounced, is not correct. We find that any solution that satisfies the Alexander-McTague condition is not stable. We investigate the implication of this result for nucleation near the pseudo- spinodal in near-meanfield systems.Comment: 20 pages, 0 figures, submitted to Physical Review

Health Effects of Naturally Radioactive Water Ingestion: The Need for Enhanced Studies

Background: Radiological pollution is a potentially important aspect of water quality. However, relatively few studies have been conducted to document its possible health effects

A modified BlÄzka–type respirometer for the study of swimming metabolism in fishes having deep, laterally compressed bodies or unusual locomotor modes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73888/1/j.1095-8649.2000.tb00890.x.pd

Simultaneous Quantitation of Amino Acid Mixtures using Clustering Agents

A method that uses the abundances of large clusters formed in electrospray ionization to determine the solution-phase molar fractions of amino acids in multi-component mixtures is demonstrated. For solutions containing either four or 10 amino acids, the relative abundances of protonated molecules differed from their solution-phase molar fractions by up to 30-fold and 100-fold, respectively. For the four-component mixtures, the molar fractions determined from the abundances of larger clusters consisting of 19 or more molecules were within 25% of the solution-phase molar fractions, indicating that the abundances and compositions of these clusters reflect the relative concentrations of these amino acids in solution, and that ionization and detection biases are significantly reduced. Lower accuracy was obtained for the 10-component mixtures where values determined from the cluster abundances were typically within a factor of three of their solution molar fractions. The lower accuracy of this method with the more complex mixtures may be due to specific clustering effects owing to the heterogeneity as a result of significantly different physical properties of the components, or it may be the result of lower S/N for the more heterogeneous clusters and not including the low-abundance more highly heterogeneous clusters in this analysis. Although not as accurate as using traditional standards, this clustering method may find applications when suitable standards are not readily available