Morphological and phylogenetic studies onCordyceps sinensis distributed in southwestern China

Cordyceps is one of the target genera for modern mycological studies. Among themCordyceps sinensis is the most famous but poorly defined species because the fungus is endemic in districted regions of east Eurasia. We have explored the various growing regions and habitats where the fungus grows in the wild. We also examined authentic cultures for the species. We analyzed the sequences of ITS1, 2 and 5.8 S rDNA regions ofC. sinensis materials collected from 11 localities of southwestern China. Phylogenetic analyses were performed with these sequences and with additional sequences obtained from GenBank. All sequences formed a single cluster, which comprised two subgroups. Our results strongly suggested that intraspecific variation was rather small and that some species that are morphologically similar toC. sinensis but with different names might be synonymous withC. sinensis. The difference in the pharmaceutical activity among these collectedC. sinensis from different regions will be studied in the future.     

Sequential expression of mRNA-encoded keratin sets in neonatal mouse epidermis: basal cells with properties of terminally differentiating cells

The keratin pattern of newborn mouse epidermis was investigated during terminal differentiation. In highly pure fractions of basal and suprabasal cells, obtained by Percoll density gradient centrifugation, we identified two sets of mRNA-encoded proteins: a basal set of 58.5, 52, and 47 kd subunits and a suprabasal set of 67 and 60 kd subunits. The large subunits of each set were alkaline to neutral, while the small subunits were acidic. Polyclonal antibodies against the suprabasal, acidic 60 kd protein and the basal, alkaline 58.5 kd protein selectively recognized their antigens in immunoblots of NEPHGE -resolved keratins and decorated the corresponding epidermal compartments in frozen sections. The antibody to the suprabasal 60 kd protein also recognized distinct cells in the basal cell layer. Quantification of this cell population revealed a 10% cell fraction, morphologically indistinguishable from the total cell population, that, in addition to expressing basal keratin proteins, was already synthesizing suprabasal keratin subunits.     

Effect of polynucleotides and a basic protein on the condensation of phenylalanyl adenylate

The effect of polyuridylate and of histone on the oligomerization of phenylalanyl adenylate was tested. Polyuridylate which pairs with adenine under suitable conditions showed no effect. Histone increased the rate of the polymerization whereas a neutral protein, albumin, had no effect. Simultaneous presence of nucleotides diminished the effect of histone. The implication of these results on the prebiotic polypeptide formation is discussed.     

Ultrasensitive hybridization analysis using fluorescence correlation spectroscopy.

The hybridization of fluorescently tagged 18mer deoxyribonucleotides with complementary DNA templates was analysed by fluorescence correlation spectroscopy (FCS) in a droplet under an epi-illuminated fluorescence microscope at the level of single molecules. The interaction can be monitored by the change in the translational diffusion time of the smaller (18mer) primer when binding to the bigger (7.5 kb) DNA containing the complementary sequence. The hybridization process in the presence of template M13mp18 ssDNA was monitored in a small volume (2 x 10(-16)I) at various temperatures. The Arrhenius plot of the association rate constant shows that the activation energy was 38.8 kcal/mol, but the hybridization process may involve several components. The titration experiment suggested that approximately 2 primers can be associated with one template DNA at 40 degrees C. Results of a simple homology search for the sequences complementary to the primer indicate the existence of additional sites of lower specificity.