Impact of pre-culture on short- and long-term in vitro recovery of the biosynthetic potential and enzymatic and non-enzymatic antioxidant defense of Hypericum rumeliacum Boiss. after cryostorage

Due to its high hypericin and pseudohypericin in vitro biosynthetic capacity, the Balkan endemic Hypericum rumeliacum was selected as a prospective candidate for long-term preservation of valuable medicinal plant germplasm. Initial cryopreservation experiments were previously conducted based on the successful protocol established and reported for the widely studied H. perforatum. This is the first report on the impact of pre-culture duration on the short- and long-term in vitro recovery of the biosynthetic potential and antioxidant defense system of H. rumeliacum cryopreserved by vitrification. Cryopreservation did not impair the phenolics and flavonoids production of the regenerated plants. Moreover, hypericin and pseudohypericin levels even increased substantially in one of the regenerated lines, reaching yields from 0.107 and 0.752?mg?g^?1?DW in the control up to 0.277 and 1.112?mg?g^?1?DW for hypericin and pseudohypericin, respectively. However, the physical injury stress of the pre-culture treatment manipulations affected the physiological status of regenerants in a time dependent manner. Within 6?months after thawing, regenerants with the highest oxidative stress after pre-culture, were characterized with an augmentation of antioxidant metabolites such as phenolics, flavonoids, glutathione and ascorbic acid as well as increased antioxidant enzymatic activities in comparison with both the non-frozen control and the regenerants with the lowest pre-culture oxidative stress. Then, after 18?months of recovery, the same first H. rumeliacum group displayed a marked drop of enzymatic antioxidant activity as compared with the other groups of plants. Further research is needed to target oxidative stress alleviation to optimize H. rumeliacum cryopreservation protocol.     

Mechanism of action of N-acetylglucosaminyl-N-acetylmuramylalanyl-D-isoglutamine on the nonspecific anti-infection resistance of mice

The stimulating influence of glucose-containing muramyldipeptide (GMDP) on the nonspecific resistance of mice was shown to depend on the features of the pathogenesis of the infection. Thus, the intraperitoneal injection of GMDP increased the survival rate of mice infected with Escherichia coli, but had no stimulating effect on the resistance of the animals to Salmonella typhimurium natural infection in whose pathogenesis macrophages played an essential role. Experiments demonstrated that GMDP was capable of enhancing the ingestive function of macrophages, but did not increase their bactericidal activity with respect to this infection.     

Taxonomic identification of gram-negative nonfermenting microorganisms in environmental research

The scheme for the identification of Gram-negative nonfermenting microorganisms is proposed. The scheme comprises the most important key signs, such as the cytochrome oxidase reaction determined by the method of Gaby and Hadley, the oxidation/fermentation test, maltose oxidation and motility, as well as additional key signs, among them gelatinase activity, the oxidation of 10% lactose, nitratase activity with the liberation of free nitrogen, the utilization of the sources of carbon and energy (glucose and sodium acetate) in limited media containing ammonium salts and nitrates as the sources of nitrogen. Additional tests for the identification of nonfermenting microorganisms similar in their main key signs are also recommended.     

Alcohol dehydrogenase in the blood and liver of rats with different alcoholic motivation

Alcohol dehydrogenase (ADH) activity was determined by a highly sensitive method. The enzyme activity in the blood serum was similar in alcohol and water preferring rats, while ADH activity in the liver of alcohol preferring rats was higher than in water preferring rats. In rats, chronically intoxicated with ethanol, ADH activity in the liver decreased, while in the serum it was twice higher than the normal level. It is suggested that high level of blood ADH is not connected with the rate of enzyme synthesis in the liver.     

Implantation of embryonic brain tissue into regenerating peripheral nerve

Dynamics of development of the cerebral cortex tissue anlage in 17-day-old embryos of Wistar rats, implanted into the sciatic nerve of mature rats with the aim to establish new relay and trophic centers in the regenerating nerve have been studied. By means of certain morphological methods (silver nitrate impregnation after Bielschowsky-Gros, Sudan black, hematoxylin-eosin, toluidine blue after Nissl stainings) it has been stated that the implanted nerve cells not only preserve their viability, but also differentiate from neuroblasts up to young and mature neurons during 2 months. Already in 14 days after the operation there are blood vessels in the implants; by the 2d month massive myelinization of axons begins in the implant. A part of the regenerating myelin fibers of the nerve gets into the implant and branches. In similar cases connections between the implanted neurons and the host peripheral nervous fibers are supposed to be established.     

Modulation of alkaline phosphatase activity in alveolar type II like cells

Summary Alveolar type II like cells (ALT II) represent a small subpopulation of alveolar type II cells, which is able to proliferate, can be passaged and possess many characteristics of differentiated adult type II cells. A correlation was found between the growth and development of ALT II cells in culture and their alkaline phosphatase activity. Unlike alveolar type II cells, which lose the activity in culture, ALT II cells regain the activity and maintain it for a long culture period. Quantitative histochemical analysis of the stained cells indicate that 80% of the cells at days 15–20 in culture are alkaline phosphatase positive. Inhibition studies indicate that alkaline phosphatase from ALT II cells and freshly isolated type II cells were similar. The inhibition of ALT II alkaline phosphatase byl-levamisole and its heat stability are similar to that of the bone enzyme and differ from the intestinal enzyme. Alkaline phosphatase expression is considered part of the differentiated phenotype of these cells. Therefore, the presence of this enzyme in ALT II cells adds support to the notion that these cells maintain many aspects of mature alveolar type II cells.