No abstract

No abstract

, 544 biology faculty from 2-and 4-year colleges and universities, along with researchers, administrators, students, and other educational stakeholders from around the country, met in Washington, DC, to help create a blueprint for the future of undergraduate biology education (Summers, 2009). Hosted by the American Association for the Advancement of Science (AAAS), with support from the National Science Foundation (NSF), the meeting set out to mobilize the nation's undergraduate biology educators to ensure that the biology they teach in their classrooms reflects the biology they practice in the lab and field, and that all students-majors and nonmajors alike-gain a better understanding of the nature of science and the natural world (Mervis, 2009). The charge for the meeting (Transforming Undergraduate Education in Biology: Mobilizing the Community for Change) noted that the need for change reflects the radical changes in the science itself as well as the knowledge we are gaining about how people learn and the best ways to ensure that learning takes place. The meeting concentrated on how people have effected change, the results when they did so, and how the attendees and their colleagues could most effectively incorporate this knowledge and understanding into their own approaches to undergraduate education in biology. Videos, slides, and other materials from the meeting are posted at the conference website (AAAS, 2009a). A culminating summary publication is anticipated in spring 2010.The conference's theme and format were developed through a year-long series of Vision and Change conversations held at sites across the country with biologists from a variety of backgrounds. Seven of the conversations were between faculty members and administrators, one was with professional society representatives, and 13 were with undergraduate students (AAAS, 2009b). Conference activities included small group discussions to draw up the blueprint for the future; a panel discussion to explore mechanisms for institutional change; plenary talks from Bruce Alberts 1 and James Collins; 2 additional talks and a panel discussion by other leaders in the field; a presentation by potential funders on resources available to support change efforts; and poster sessions where attendees shared examples of creative curricula, effective assessments, and new approaches that can serve as models for others (AAAS, 2009c).The small group discussions built on eight themes arising from the prior conversations and the experiences of the conferees (AAAS, 2009d). These themes were as follows: 1) overarching and unifying key concepts and competencies; 2) student-centered learning (engaging students in discourse); 3) assessing student learning; 4) innovations in integrating scientific research experiences across the curriculum; 5) toolkits to support the change; 6) preparing faculty (developing teaching skills and interests of future and current faculty); 7) implementing innovations and assessing their impact; and 8) changing institutional approaches. Participa...

No abstract

Etiolated mung bean seedlings were examined for chorismate mutase activity. Evidence for the occurrence of two forms of the enzyme (designated CM-1 and CM-2) was obtained by ammonium sulfate fractionation, anion exchange cellulose chromatography, and isoelectric focusing. The two forms showed distinctly different properties, as CM-1 was inhibited by phenylalanine and tyrosine and activated by tryptophan, but inhibition by phenylalanine and tyrosine was reversed by tryptophan. The other form, CM-2, was unaffected by any of the three aromatic amino acids. Isoelectric points of the two forms were CM-1, pH 4.6, and CM-2, pH 5.6. The molecular weights estimated by molecular sieving on Sephadex G-200 were CM-1, 50,000, and CM-2, 36,000.Chorismic acid has been established as an important intermediate in the biosynthesis of the aromatic amino acids phenylalanine, tyrosine, and tryptophan in microorganisms (5-7). By action of chorismate mutase, chorismate is converted to prephenate, the precursor of phenylalanine and tyrosine. Chorismate serves as a substrate for anthranilate synthetase, the first reaction in a branch pathway leading to the synthesis of tryptophan. Control of chorismate mutase activity would therefore be of prime importance in the regulation of phenylalanine and tyrosine biosynthesis. Multiple forms of chorismate mutase have been found in fungi, bacteria, and blue green algae. Certain of these forms appear to have regulatory properties, and their roles in regulating production of the two amino acids have been investigated in these microorganisms (2, 3, 8-14, 16, 17 MATERIALS AND METHODSPlant Material. Etiolated mung bean seedlings (Phaseolus aureus) were purchased from a local retail grocer. Such seedlings germinated in the laboratory and harvested 2 to 3 days after planting gave the same results as those obtained commercially.Preparation of Acetone Powders. Whole seedlings were added to a Waring Blendor and ground for 1 min with acetone precooled to -10 C. The resulting suspension was put on a Biichner funnel and washed with cold acetone until the filtrate was colorless. The acetone powder was air-dried and then stored in a desiccator at 4 C under nitrogen. Powders stored for 2 weeks retained at least 80% of chorismate mutase activity that was present at the time the powders were prepared. Those stored for 1 month possessed only one-half of their original activity.Preparation of Pulverized Frozen Material. Etiolated mung bean seedlings were frozen in liquid nitrogen and, while frozen, homogenized to a fine powder in a Waring Blendor. At least 60 sec at full speed were required to pulverize completely the frozen material. The powder was stored at -10 C until used for enzyme extraction. Powders stored at -10 C for 1 month retained at least 95% of their original chorismate mutase activity.Enzyme Preparation. Frozen powder was mixed with 20% by weight Polyclar AT and 50 mm potassium phosphate buffer. pH 6.8, 5 g fresh weight of powder per ml of buffer. The powder was allowed to thaw and then left ...