The effect of temperature on the life cycle of Drosophila acutilabella

This is a study of the rate of development of the fly, Drosophila acutilabelle, Stalker (1953), at three temperatures, 22°, 25°, and 28°C. It is part of a larger project testing the hypothesis that stenothermal species (those restricted to a narrow temperature range) are more sensitive than eurythermal species, such a the cosmopolitan D. melanogaster and D. hydei (those able to live over a broad temperature range) to the effects of temperature during development. It has been suggested that eurythermal species have a lower Q10 of development. The species used in this study is considered to be stenothermal because it is limited in distribution to Florida, Cuba, Hispaniola and Jamaica, which are regions of relatively warm temperature with little seasonal change

Evaluation of irrigation pumping plant efficiencies and costs in the high plains of eastern Colorado

CER68-69RLL-DLM43.Includes bibliographical references (page 18).December 1968

Genetic analysis of photosynthesis

It is now possible to select mutations of nuclear genes controlling various steps of the light reaction of photosynthesis in higher plants. Forty-nine such mutants, which were not previously available for the study of photosynthesis, have been isolated on the basis of their high level of chlorophyll fluorescence or their ability to withstand treatment of the photodynamic inhibitor, diquat. Diquat requires photosynthetic activity in order to kill plants and therefore mutants of photosynthesis survive. Full green seedling lethal photosynthesis mutants of Zea mays have been isolated which have near normal chloroplast ultrastructure. Using standard measurements of photosynthetic reactions we have characterized the first series of these mutants to the single protein involved. Among those now identified, one is missing the NADP+ reductase enzyme (hcf-1); another has lost cytochrome f(hcf-2); and one has no high potential cytochrome b[subscript 559] (hcf-3). There is also indication that hcf-4 does not have the ATP synthesis enzymes for non-cyclic photophosphorylation. These maize mutants are now being applied to basic studies of the pathway of photosynthetic electron transport and phosphorylation. Unique information gained in this way may have application to our understanding of photosynthetic control in an important food plant species.DONALD MILES, Biology Division, University of Missouri Columbia, Mo

Artificial aquifer recharge in the Colorado portion of the Ogallala Aquifer

November 1984.Bibliography: pages 24-25

Global analysis of gene expression changes during retinoic acid-induced growth arrest and differentiation of melanoma: comparison to differentially expressed genes in melanocytes vs melanoma

<p>Abstract</p> <p>Background</p> <p>The incidence of malignant melanoma has significantly increased over the last decade. Some of these malignancies are susceptible to the growth inhibitory and pro-differentiating effects of all-<it>trans</it>-retinoic acid (RA). The molecular changes responsible for the biological activity of RA in melanoma are not well understood.</p> <p>Results</p> <p>In an analysis of sequential global gene expression changes during a 4–48 h RA treatment of B16 mouse melanoma cells, we found that RA increased the expression of 757 genes and decreased the expression of 737 genes. We also compared the gene expression profile (no RA treatment) between non-malignant melan-a mouse melanocytes and B16 melanoma cells. Using the same statistical test, we found 1495 genes whose expression was significantly higher in melan-a than in B16 cells and 2054 genes whose expression was significantly lower in melan-a than in B16 cells. By intersecting these two gene sets, we discovered a common set of 233 genes whose RNA levels were significantly different between B16 and melan-a cells and whose expression was altered by RA treatment. Within this set, RA treatment altered the expression of 203 (87%) genes toward the melan-a expression level. In addition, hierarchical clustering showed that after 48 h of RA treatment expression of the 203 genes was more closely related to the melan-a gene set than any other RA treatment time point. Functional analysis of the 203 gene set indicated that RA decreased expression of mRNAs that encode proteins involved in cell division/cell cycle, DNA replication, recombination and repair, and transcription regulation. Conversely, it stimulated genes involved in cell-cell signaling, cell adhesion and cell differentiation/embryonic development. Pathway analysis of the 203 gene set revealed four major hubs of connectivity: CDC2, CHEK1, CDC45L and MCM6.</p> <p>Conclusion</p> <p>Our analysis of common genes in the 48 h RA-treatment of B16 melanoma cells and untreated B16 vs. melan-a data set show that RA "normalized" the expression of genes involved in energy metabolism, DNA replication, DNA repair and differentiation. These results are compatible with the known growth inhibitory and pro-differentiating effects of RA. Pathway analysis suggests that CDC2, CHEK1, CDC45L and MCM6 are key players in mediating the biological activity of RA in B16 melanoma cells.</p

A Tribute to James Moffett

A tribute to James Moffett, a visionary and trailblazer, who wrote about trends in education long before others even considered their possibilities