Reazioni delle piante di Ricinus communis a incisioni sperimentali

Summary

The author has produced wounds in the stem of Ricinus communis, studing the regeneration and cicatrization processes.

The rapidity of the surface cicatrization is in relation with the water loss of the waunded cells.

Both in the stems woumded let free and in those in which an extra tissue has been introduced, the cicatrization processes tacke place. They only take place with different velocity. The healing process lead to the reconstruction of the cortical and the conducting tissues.

The whole reconstruction of the stele may occur, when the flow of the assimilated stuffs is slowed. Sothat it is probable that the regeneration depends more upon the tissue nutrition tham on a specifical properti of the tissues.     

Conjugation of phosphonoacetic acid to nucleobase promotes a mechanism-based inhibition

Small molecule inhibitors have a powerful blocking action on viral polymerases. The bioavailability of the inhibitor, nevertheless, often raise a significant selectivity constraint and may substantially limit the efficacy of therapy. Phosphonoacetic acid has long been known to possess a restricted potential to block DNA biosynthesis. In order to achieve a better affinity, this compound has been linked with natural nucleotide at different positions. The structural context of the resulted conjugates has been found to be crucial for the acquisition by DNA polymerases. We show that nucleobase-conjugated phosphonoacetic acid is being accepted, but this alters the processivity of DNA polymerases. The data presented here not only provide a mechanistic rationale for a switch in the mode of DNA synthesis, but also highlight the nucleobase-targeted nucleotide functionalization as a route for enhancing the specificity of small molecule inhibitors.     

On Testing Equality of Means of Correlated Variates with Incomplete Data

A statistic is proposed for testing the hypothesis of equality of the means of a bivariate normal distribution with unknown common variance and correlation coefficient when observations are missing on one of the variates. Expressions for the second and fourth central moments of the statistic are obtained. These moments are used to approximate the distribution of the statistic by a Student's t distribution under the null hypothesis. The powers of the test are computed and compared with those of the conventional paired t and the other known statistics.     

Obtaining a High Percentage of Explants with Negative Serological Reactions against viruses by Combining Potato Meristem Culture with Antiphytoviral Chemotherapy

A high percentage of plantlets, in which PVX, PVM, and PVS were no longer detectable by precipitin tests was obtained from 100% virus-infected stocks of the potato varieties Rosa and Priobskij rannija by combining meristem (tip) culture with antiphytoviral chemotherapy. When 2,4 - dioxohexahydro 1,3,5-triazinc (DHT) was added to the nutrient media, no virus was detectable serologically in 72% of the corresponding explants of the variety Rosa and in 66% of that of the variety Priobskij rannija, respectively. Contrary to this, all untreated control explants proved virusinfected. Treatment with 2-thiouracil resulted in 46.6%, with cyanoguanidine in 28.6% of plantlets, in which no virus was detectable serologically.     

Monoclonal antibodies to the hydrogenase ofThiocapsa roseopersicina

Monoclonal antibodies were produced to electrophoretically pure hydrogenase fromThiocapsa roseopersicina. Protein immunoelectroblotting was used to identify the hydrogenase-specific antibodies. Among the 18 monoclonal antibodies selected by enzyme immunoassay, three were found to react with highly immunogenic trace contaminating proteins. One cell line produced antibody that inhibitied hydrogenase activity. This was the first specific inhibitor of the hydrogenase function. The results suggest that monoclonal antibodies could provide valuable new informations about the enzyme structure as well.