Characterization of regioisomeric diterpenoid tails in bacteriochlorophylls produced by geranylgeranyl reductase from Halorhodospira halochloris and Blastochloris viridis

Photosynthesis Research - Geranylgeranyl reductase (GGR) encoded by the bchP gene catalyzes the reductions of three unsaturated C?=?C double bonds (C6?=?C7,...     

Markov process of maintained impulse activity in central single neurons

To clarify the stochast properties of the maintained impulse activity of the central nervous system, we proposed a measure of statistical dependency on the basis of Shannon's entropy. This measure could provide the Markov properties of the neural impulse sequences, representing the necessary and sufficient condition for the statistical dependence. The order of Markov process of the sequence is determined by the conditional entropy which is derived from the joint entropy. Here the joint entropy in the case of Gaussian process is directly related with the covariance matrix which is substituted for the matrix of the serial correlation coefficients. Therefore the condition to determine the order of Markov process is obtained by the equation of the matrices of the serial correlation coefficients. The order of Markov process of the neural impulse sequences recorded from the mesencephalic reticular formation (MRF), red nucleus (RN), and lateral geniculate nucleus (LGN) neurons has been estimated. The maintained impulse activity of the MRF and RN neurons had from the 2-nd to 4-th order Markov property, while that of the LGN had no Markov property, in the consecutive impulse sequences.     

Novel chondrogenic and chondroprotective effects of the natural compound harmine

A significant number of natural compounds have been shown to regulate the behavior of the cells, in collaboration with cellular proteins. CCN2/connective tissue growth factor (CTGF) has been reported to have essential roles in cartilage development, chondrocyte proliferation and differentiation as well as regulation of the extracellular matrix metabolism. Previous studies demonstrated the capability of CCN2 to regenerate surgical defects in articular cartilage of rat knee. Also, transgenic mice over-expressing cartilage-specific CCN2 were shown to be more resistant to aging-related cartilage degradation. We hypothesized that small molecules that induce CCN2 in chondrocytes could be novel candidates to increase the resistance to aging-related cartilage degradation, or even to correct cartilage degenerative changes incurred in OA. Therefore, this study screened a compound library and identified the β-carboline alkaloid harmine as a novel inducer of CCN2 in human chondrocytic HCS-2/8 cells and osteoarthritic articular chondrocytes. Harmine increased the expression of the cartilage markers aggrecan and COL2α1, as well as that of the master regulator of chondrogenesis, SOX-9. Moreover, harmine notably induced chondrogenesis of prechondrocytic ATDC5 cells in micromass cultures. The chondroprotective effect of harmine was investigated under inflammatory condition by stimulation with TNFα, and harmine was shown to ameliorate TNFα-induced decrease in expression of CCN2 and cartilage markers. These findings uncover novel chondrogenic effects of harmine and indicate harmine as a potential drug for prevention and/or repair of cartilage degradation.     

Production of chimeric calves by aggregation of in vitro-fertilized bovine embryos without zonae pellucidae

Bovine embryos produced by in vitro maturation (IVM), fertilization (IVF) and culture (IVC) were used to produce aggregation chimeras. An aggregated chimera was produced by combining bovine IVF embryos (Holstein × Japanese Black and Japanese Brown × Limousin breeds) which were cultured in vitro without the zonae pellucidae. Forty-eight hours after IVF, embryos at the 8 cell-stage were used to produce aggregation chimeras. In Experiment I, the zonae pellucidae was removed by a microsurgical method using a microblade or by treatment with 0.25% pronase. Holstein × Japanese Black embryos were aggregated with Japanese Brown × Limousin embryos after zonae removal by hand manipulation in culture medium. In Experiment II, the viability of the aggregated embryos developing into blastocysts was examined by measuring the extent of development. The number of aggregated embryos and embryos developed into blastocysts was 34 (91.9%) and 24 (70.6%), respectively, when the zonae pellucidae was removed by the microsurgical method; and 12 (92.3%) and 6 (50.0%), respectively, when the zonae pellucidae was removed using the 0.25% pronase treatment. The size of the aggregated embryos was significantly different from that of the normal embryos when cultured in vitro until Day 10, but not different thereafter. Five aggregated embryos were transferred nonsurgically to the recipients, resulting in 1 pregnancy and the birth of 2 chimeric calves. Skin color was used as evidence of chimerism.     

Concanavalin A Modifies Allo-specific Sperm-Egg Interactions in the Ascidian, Ciona intestinalis

In the self sterile ascidian, Ciona intestinalis , the spermatozoa rarely bind to the vitelline coat of autologous eggs and never penetrate it. We report here that concanavalin A (ConA), a lectin recognizing mannose or glucose residues of carbohydrates, can modify these self- and nonself-specific sperm-egg interactions. When eggs were pretreated with 0.1–0.5 mg/ml of ConA, about two thousand spermatozoa became attached to the autologous vitelline coat within five minutes of insemination. The effect of ConA was not modified by the addition of D-mannose or pretreatment of spermatozoa with ConA, showing that ConA does not function merely as a ligand bridging the sperm and vitelline coat. In contrast to the marked enhancement of sperm-egg binding, ConA did not facilitate the penetration of spermatozoa through the autologous vitelline coat. Even in non-autologous insemination, it blocked the sperm penetration and, consequently, fertilization did not occur, as shown by Rosati et al. (1978). D-Mannose, when mixed with ConA in advance, completely abolished this inhibitory effect of ConA. Lotus agglutinin, a fucose-binding lectin, was less effective and wheat germ agglutinin and soy bean agglutinin had no effect on sperm entry in the perivitelline space. The results of this study are discussed in relation to the possible involvement of mannosyl and/or glucosyl glycoconjugates in allo-specific sperm-egg interactions.