In this introductory organic chemistry experiment, the students get an opportunity to analyze and identify an unknown compound as it is done in a real-laboratory setting. First, students are instructed on the proper operation of three major instruments, NMR, IR, and GC–MS, and are given a sample of an unknown compound. The students are expected to operate these three instruments on their own so as to obtain 1H NMR, 13C NMR, IR, and MS spectra of their unknown sample. They must then interpret the data from each of the four spectroscopic methods simultaneously to elucidate the chemical structure of the unknown compound. In this exercise, the instructor does not provide a list of possible unknowns so as to narrow the search for the students. All the knowledge about the nature of the compound is obtained from the spectral data.
Despite their descent from a common ancestral gene and the requirement for coordinated, tissue-specific regulation, the alpha- and beta-globin genes in many mammals are regulated in distinctly different ways. Unlike the beta-globin gene, the rabbit alpha-globin gene is transiently expressed at a high level without an added enhancer in transfected erythroid and non-erythroid cells. By examining a series of alpha/beta fusion genes, we show that internal sequences of the rabbit alpha-globin gene (within the first two exons and introns) are required along with the 5' flank for this enhancer-independent expression. Furthermore, deletion of the introns of the alpha-globin gene, or replacement by introns of the beta-globin gene, results in severely decreased expression of the transfecting genes. Hybrid constructs between segments of the alpha-globin gene and a luciferase gene confirm that internal alpha-globin sequences are needed for high level production of RNA in transfected cells. The flanking and internal sequences implicated in regulation of the rabbit alpha-globin gene coincide with a prominent CpG-rich island and may comprise an extended promoter (including both flanking and intragenic sequences) that is active in transfected cells without an enhancer.
This article describes a novel experiment focused on metal ion hydrolysis and the equilibria related to metal ions in aqueous systems. Using 27Al NMR, the students become familiar with NMR spectroscopy as a quantitative analytical tool for the determination of aluminum by preparing a standard calibration curve using standard aluminum solutions in dilute nitric acid keeping the aluminum in the hexaaquoaluminum ion form, Al(H2O)6
3+. The technique has a large linear dynamic range, and in this experiment it ranges from 10 to 1000 ppm. Once the quantitative technique is validated, the goal of the experiment is to investigate the hydrolysis of Al3+ ions in aqueous solution by determining the concentration of the Al(H2O)6
3+ ion by 27Al NMR for a series of solutions with the same total concentration of aluminum but at various pHs ranging between 1.0 to 4.5. This experiment is also suitable for an instrumental analysis or inorganic chemistry course.
Although cells of mushroom-producing fungi typically contain paired haploid nuclei (n + n), most Armillaria gallica vegetative cells are uninucleate. As vegetative nuclei are produced by fusions of paired haploid nuclei, they are thought to be diploid (2n). Here we report finding haploid vegetative nuclei in A. gallica at multiple sites in southeastern Massachusetts, USA. Sequencing multiple clones of a single-copy gene isolated from single hyphal filaments revealed nuclear heterogeneity both among and within hyphae. Cytoplasmic bridges connected hyphae in field-collected and cultured samples, and we propose nuclear migration through bridges maintains this nuclear heterogeneity. Growth studies demonstrate among- and within-hypha phenotypic variation for growth in response to gallic acid, a plant-produced antifungal compound. The existence of both genetic and phenotypic variation within vegetative hyphae suggests that fungal individuals have the potential to evolve within a single generation in response to environmental variation over time and space.
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