Evolution of Sickness and Healing

Evolution of Sickness and Healing. Horacio Fábrega Jr. Berkeley: University of California Press, 1997 (cloth), xv. 364pp.     

New mode of Dunaliella biotechnology: two-phase growth for β-carotene production

Attempts to adapt the laboratory experience of bi-phasic growth and carotenogenesis in Dunaliella to large-scale conditions were highly successful. Algae were initially cultivated in stage one for optimizing biomass production of cells containing a low β-carotene to chlorophyll ratio. The culture was then transferred to stage two, diluted to about one third and induced for carotenogenesis. The bi-phase cultivation increased β- carotene productivity to 450 mg m^-2 d^-1 in stage one and to 300 mg m^-2 d^-1 in stage two, compared to the relatively low productivity of below 200 mg β- carotene m^-2 d^-1, in the conventional one phase type of cultivation. The results indicate that a selected algal product can be promoted specifically by growth manipulation of the alga and its environment.     

Procedure for the efficient acquisition of progeny seeds from crossed potato plants grafted onto tomato

Potato, Solanum tuberosum L. is an important crop. However, it is difficult to breed potato cultivars by applying conventional crossing methods because potato has a tetraploid genome and is vegetatively propagated. Flower formation and tuber development occur simultaneously. Many potato cultivars hardly produce any fruits after crossing and fail to produce seeds. We report an improved procedure for obtaining progeny seeds by grafting potatoes onto tomatoes. The rate of fruit formation was more than 19% when the grafted potatoes were used for the crossing experiments, whereas crossing using the ungrafted plants showed a rate of 1.1%. This result suggests that our procedure results in the easy acquisition of null-segregant progenies by crossing mutant lines. It is also expected to improve conventional potato breeding.     

Response of microbial populations to environmental disturbance

Taxonomic and genetic diversities of microbial communities disturbed by chemical pollutants were lower than in undisturbed reference communities. The dominant populations within the disturbed communities had enhanced physiological tolerances and substrate utilization capabilities, indicating that generalized physiological versatility is an adaptive characteristic of populations that successfully compete within disturbed communities.     

Production of carotene stereoisomers by Phycomyces blakesleeanus

Summary -Carotene steroisomers, mainly all-trans and to a small extent 9-cis, may be produced by the fungus Phycomyces blakesleeanus under normal fermentation conditions. The amount of the 9-cis--carotene may comprise up to 15% of the total -carotene. Similarly, cis-lycopene or-phytoene stereoisomers may be obtained when the fungus is fermented in the presence of specific -carotene inhibitors such as nicotine or diphenylamine respectively. This is the first report on the occurrence of cis-stereoisomers of carotenes in mycelial fungi.     

Expression of insulin‐like growth factor‐1 receptor in metastatic uveal melanoma and implications for potential autocrine and paracrine tumor cell growth

We investigated the importance of the insulin‐like growth factor‐1 receptor (IGF‐1R) in hepatic metastases of uveal melanoma. The expression pattern of IGF‐1R in archival tissue samples of hepatic metastasis from 24 patients was analyzed by immunohistochemistry. All the samples of hepatic metastases stained positive for IGF‐1R. To investigate the biological role of IGF‐1R on the growth of metastatic uveal melanoma, a long‐term cell line obtained from a hepatic metastasis (TJU‐UM001) was evaluated. TJU‐UM001 expressed cell surface IGF‐1R (>90%) and proliferated in response to exogenous and endogenous insulin‐like growth factor‐1 (IGF‐1). Correlatively, anti‐IGF‐1R antibody completely blocked IGF‐1‐induced growth of TJU‐UM001 cells. IGF‐1 preferentially induced phosphorylation of Akt (S473) in quiescent TJU‐UM001 cells, and this was blocked by anti‐IGF‐1R antibody. This study suggests that autocrine and paracrine mechanisms underlie IGF‐1‐induced growth of metastatic uveal melanoma and underscore the potential benefit of IGF‐1 or IGF‐1R antagonism in treatment for metastatic uveal melanoma.     

A forward chemical genetic screen reveals an inhibitor of the Mre11-Rad50-Nbs1 complex

The MRN (Mre11-Rad50-Nbs1)-ATM (ataxia-telangiectasia mutated) pathway is essential for sensing and signaling from DNA double-strand breaks. The MRN complex acts as a DNA damage sensor, maintains genome stability during DNA replication, promotes homology-dependent DNA repair and activates ATM. MRN is essential for cell viability, which has limited functional studies of the complex. Small-molecule inhibitors of MRN could circumvent this experimental limitation and could also be used as cellular radio- and chemosensitization compounds. Using cell-free systems that recapitulate faithfully the MRN-ATM signaling pathway, we designed a forward chemical genetic screen to identify inhibitors of the pathway, and we isolated 6-(4-hydroxyphenyl)-2-thioxo-2,3-dihydro-4(1H)-pyrimidinone (mirin, 1) as an inhibitor of MRN. Mirin prevents MRN-dependent activation of ATM without affecting ATM protein kinase activity, and it inhibits Mre11-associated exonuclease activity. Consistent with its ability to target the MRN complex, mirin abolishes the G2/M checkpoint and homology-dependent repair in mammalian cells.     

Molecular characterization of ENU mouse mutagenesis and archives

The large-scale mouse mutagenesis with ENU has provided forward-genetic resources for functional genomics. The frozen sperm archive of ENU-mutagenized generation-1 (G1) mice could also provide a "mutant mouse library" that allows us to conduct reverse genetics in any particular target genes. We have archived frozen sperm as well as genomic DNA from 9224 G1 mice. By genome-wide screening of 63 target loci covering a sum of 197 Mbp of the mouse genome, a total of 148 ENU-induced mutations have been directly identified. The sites of mutations were primarily identified by temperature gradient capillary electrophoresis method followed by direct sequencing. The molecular characterization revealed that all the identified mutations were point mutations and mostly independent events except a few cases of redundant mutations. The base-substitution spectra in this study were different from those of the phenotype-based mutagenesis. The ENU-based gene-driven mutagenesis in the mouse now becomes feasible and practical.