Inhibition of Tobacco Mosaic Virus Reproduction in Isolated Tobacco Protoplasts by Means of Pancreatic Ribonuclease

Treatment of protoplasts with RNase solutions (1 — 100 μg/ml) sharply reduced their ability to support TMV reproduction. Treatment of protoplasts with RNase both prior to and after inoculation with the virus, and also treatments of varying duration, had approximately the same effect on inhibiting TMV reproduction; however, the effect became sharply intensified with higher RNase concentrations. The authors assume that the RNase inhibitive effect in protoplasts is ensured by the specific structure of this relatively small positively-charged macromolecule, not by its enzymic properties. The RNase molecules apparently have a damaging effect on the plasmalemma and possibly on other cell membranes with which the initial stages of TMV reproduction are associated. The development of the RNase damaging effect can be prevented by bivalent metal ions in the incubation medium, especially by calcium and manganese. The protective effect of cations is presumably caused not only by the charge, but by their steric configuration since K⁺ and Mg⁺⁺ are ineffective in protecting the protoplasts.     

Use of RAPD-PCR-analysis of cellular DNA for the evaluation of genetic polymorphism and subspecies diagnostics of the Far Eastern leopard Panthera pardus orientalis]

Genetic polymorphism in the Far-Eastern leopard subspecies Panthera pardus orientalis was examined by RAPD-PCR analysis of total cellular DNA. Primers diagnostic for the leopard subspecies were detected. These primers can be used for differentiating wild-living animals from those kept in captivity and distinguishing different breeding lines. Genetic diversity was shown to be lower in animals from the zoo (D = 0.058) and higher in a natural population (D = 0.137). Two lines of the Persian subspecies were genetically closest (D = 0.042), and the Persian and Far-Eastern subspecies represented by wild animals, genetically most remote (D = 0.274). The level of genetic divergence of the Persian subspecies and Far-Eastern subspecies (zoo animals) was lower (D = 0.108) than between representatives of the Persian subspecies from the captive and natural population (D = 0.220). On the basis of analysis of relatedness, performed using NTSYS and PHYLIP software packages, the possibility cannot be excluded that some P. p. orientalis animals from the zoo have a hybrid origin and may be assigned to another Far-Eastern subspecies.     

Plastid DNA variation in highly fragmented populations of <Emphasis Type="Italic">Microbiota decussata</Emphasis> Kom. (Cupressaceae), an endemic to Sikhote Alin Mountains

Microbiota decussata Kom. (Cupressaceae) is a subalpine species endemic to the Sikhote Alin Mountains with populations scattered throughout the range. We used sequence data for four noncoding regions of chloroplast DNA to characterize the genetic diversity in populations sampled from different parts of M. decussata natural range. No variation was observed in the trnT–trnF region, whereas the trnH–psbA, trnS–trnfM, and trnS–trnG regions showed polymorphisms. At the species level, we found a low nucleotide diversity (π = 0.0009) and high haplotype diversity (h = 0.981) as well as high differentiation (Φ_ST = 0.420). N _ST and G _ST values suggested the existence of a phylogeographic structure in M. decussata. The observed patterns of diversity could be explained in part by ecological features of the species and its long-term persistence throughout the range with population expansion, successive fragmentation and isolation.