The dynamics of pre-mRNAs and poly(A)+ RNA at speckles in living cells revealed by iFRAP studies

Speckles are subnuclear domains where pre-mRNA splicing factors accumulate in the interchromatin space. To investigate the dynamics of mRNAs at speckles, fluorescently labeled Drosophila Fushitarazu (ftz) pre-mRNAs were microinjected into the nuclei of Cos7 cells and the dissociation kinetics of pre-mRNAs from speckles was analyzed using photobleaching techniques. The microinjected ftz pre-mRNAs accumulated in speckles in an intron-dependent manner and were spliced and exported to the cytoplasm with a half-time of about 10 min. Dissociation of the accumulated pre-mRNAs in speckles exhibited rapid diffusion and slow-dissociation of about 100 s. The slow-dissociation required metabolic energy of ATP. Two types of splice-defective mutated mRNAs dissociated from the speckle with a time constant similar to that of wild-type mRNA, indicating that slow-dissociation was not coupled to the splicing reaction. Furthermore, some pre-mRNAs shuttled between speckles and nucleoplasm, suggesting that pre-mRNAs repeatedly associated with and dissociated from speckles until introns were removed. Next, endogenous poly(A)+ RNA was visualized by injecting Cy3-labeled 2'O-methyl oligo(U)22 probes. Some poly(A)+ RNA distributed diffusely within the nucleus, but some of them accumulated in speckles and dissociated at time constant of about 100 s.     

Growth rate of fungi in bathrooms Experimental survey

Factors promoting fungal contamination of the cement jointing between bathroom tiles were studied in the laboratory. Under continuous wet conditions, the growth of the yeastRhodotolura andCandida on cement was detected from the fourth day of the experiment. Following the rapid growth and decline of the yeast, growth of the moldPaecilomyces was detected on the 12th day. The application of soap or malt extract to the cement promoted the growth ofPaecilomyces. Prolongation of dry conditions delayed the growth of both yeast and mold; under these conditions,Cladosporium, one of the most common molds in household bathrooms, was detected instead ofPaecilomyces. Colonies ofCladosporium were observed along cracks in the cement. On all cement examined, a succession of mycological flora from yeast to mold was found, although fungal genera varied with culture conditions.     

Stabilization of mast cells by heme oxygenase-1: an anti-inflammatory role

This study examined the role of bilirubin in heme oxygenase (HO)-1-mediated amelioration of mast cell (MC)-elicited inflammatory responses. Pretreatment of rats with an intraperitoneal injection of hemin, an inducer of HO-1, evolved a marked induction of the enzyme in MCs. Intravital videomicroscopy revealed that hemin pretreatment attenuated compound 48/80-elicited degranulation of MCs and resultant leukocyte adhesion in venules. Superfusion with biliverdin or bilirubin, but not with carbon monoxide (CO), another product of the HO reaction, mimicked suppressive actions of the HO-1 induction on both the cell degranulation and leukocyte adhesion elicited by the stimulus, suggesting a requirement of the enzyme reaction to generate bilirubin in the inhibitory mechanisms. Such MC-desensitizing actions of bilirubin were observed in primary-cultured MCs and reproduced irrespective of the choice of stimuli, such as compound 48/80, calcium ionophore, and anti-IgE serum. Furthermore, MC-stabilizing effects of HO-1 were reproduced by the gene transfection of the enzyme into mastocytoma cell line RBL2H3. These results suggest that bilirubin generated through HO-1 serves as an anti-inflammatory substance that desensitizes MCs and ameliorates leukocyte recruitment.     

A set of near-isogenic lines of Indica-type rice variety CO 39 as differential varieties for blast resistance

Twenty-seven near-isogenic lines (NILs) with the genetic background of a blast-susceptible variety, CO 39, were developed by repeated backcrossing as a first set of a large number of differential varieties (DVs) with Indica-type genetic background. The NILs included 14 resistance genes—Pish, Pib, Piz-5, Piz-t, Pi5(t), Pik-s, Pik, Pik-h, Pik-m, Pik-p, Pi1, Pi7(t), Pita, and Pita-2—derived from 26 donor varieties. The reaction patterns of NILs against 20 standard isolates from the Philippines were similar to those of blast monogenic lines with the same resistance gene, except for those against two isolates that are avirulent to Pia in the genetic background of CO 39. A genome-wide DNA marker survey revealed that chromosome segments were introgressed in the regions where each resistance gene was previously mapped and most of the other chromosome regions in each NIL were CO 39 type. Segregation analysis of resistance and co-segregation analysis between resistance and DNA markers using F3 populations derived from the crosses between each NIL and the recurrent parent, CO 39, revealed a single-gene control of resistance and association between resistance and target introgressed segments. The morphological characters of each NIL were almost the same as those of the recurrent parent except for some lines, suggesting that these NILs can be used even under tropical conditions where Japonica-type DVs are not suitable for cropping. Thus, these NILs are useful not only as genetic tools for blast resistance study but also as sources of genes for breeding of Indica-type rice varieties.     

Bilirubin exhibits a novel anti-cancer effect on human adenocarcinoma

Anti-oxidants are essential for intracellular free radical scavenging, as free radicals are one of the causes for tumorigenesis. Our objective was to use bilirubin and investigate its action on human carcinoma cell lines. Bilirubin manifested as a prooxidant showing its cytopathic effect on TMK-1, showing growth inhibition close to 50%. Cell cycle analysis showed an arrest at G0/G1. Flow cytometry investigations with Red CC-1 showed an increase by more than 2 times suggesting a prooxidative role of bilirubin. To check the effect of radicals on DNA, a Comet Assay displayed a typical comet's tail with bilirubin treated slides, only. Further, staining with DAPI showed apoptotic action of bilirubin. Decreased mitochondrial function by bilirubin was observed with Mitotracker Green FM staining. These unexpected data have led us to conclude that bilirubin has anti-cancer activity as a prooxidant and may have a more vital role in the human body than realized.