High frequency <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated plant transformation induced by ammonium nitrate

Success in plant genetic transformation depends on the efficiency of explant regeneration and transgene integration. Whereas the former one depends on explant totipotency, the latter depends on the activity of host DNA repair and chromatin organisation factors. We analyzed whether factors that result in an increase in recombination frequency can also increase transformation efficiency. Here, we report that a threefold increase in the concentration of NH₄NO₃ in the growth medium results in more than a threefold increase in the Agrobacterium tumefaciens-mediated transformation frequency of Nicotiana tabacum plants. Regeneration of calli without selection showed that the increase in transformation frequency was primarily due to the increase in transgene integration efficiency rather than in tissue regeneration efficiency. PCR analysis of insertion sites showed a decrease in the frequency of truncations of the T-DNA right border and an increase on the left border. We hypothesize that exposure to ammonium nitrate modifies the activity of host factors leading to higher frequency of transgene integrations and possibly to the shift in the mechanism of transgene integrations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Types of Higher Nervous Activity in Pigs: Characteristics of Behavior and Effects of Technological Stress

Neurophysiology - The strength, balance, and mobility of central nervous processes, which determine behavior, were estimated in six-month-old pigs of the Large White breed. According to the...     

Characteristic Immunohematological Parameters of Migratory (Vespertilio murinus Linnaeus, 1758) and Resident (Myotis dasycneme Boie, 1825) Bat Species of the Ural Fauna

Doklady Biological Sciences - The results of the first comparative analysis of hematological parameters of bats from natural populations of the Ural region are presented: the pond bat (Myotis...     

Enzymatic indication of heavy metal toxicity to marine heterotrophic bacteria

The ecotoxicological effect of heavy metals on the dehydrogenase and catalase activities of marine heterotrophic bacteria was assessed in pure strains and in associations. The microorganisms from the surfaces of copper-containing materials had higher levels of enzyme activities and were inhibited by trace metals to a lesser degree. The data from the field and laboratory experiments suggest that catalase activity can provide an ecological indicator of the effects of heavy metals on the aquatic environment.     

Purification and characterisation of recombinant Bacteroides fragilis toxin-2

Fragilysin (BFT) is metalloprotease that is secreted by enterotoxigenic Bacteroides fragilis. Studying the mechanism of BFT interaction with intestinal epithelial cells requires a pure protein sample. In this study, we cloned DNA-fragments coding for the catalytic domain of fragilysin-2 and profragilysin-2 into an E. coli expression vector. Purification methods for the recombinant fragilysin-2 catalytic domain and profragilysin-2 were developed. In addition, we obtained mature active fragilysin-2 from recombinant proprotein by limited tryptic digestion. We tested the biological activity of the recombinant protein samples and revealed that E-cadherin was cleaved when HT-29 cells were treated with mature fragilysin-2 but not with profragilysin-2. Azocoll, azocasein and gelatin were not proteolytically cleaved by mature fragilysin-2. Proteins released in culture medium after HT-29 cells treatment with mature active BFT-2 were identified.