Izvestiia Akademii nauk. Seriia biologicheskaia最新文献

The influence of different factors on microspore embryogenesis in Chinese cabbage (B. rapa ssp. chinensis) was studied. A genotype dependence for embryo formation was observed. The majority of embryos and plants were obtained from microspores isolated from flower buds (2-2.9 mm in length) and cultured in the NLN liquid medium with 13% sucrose (w/v) supplemented with 24-epibrassinolide and 1% activated charcoal. Embryos cultured on the 1/2 Murashige-Skoog culture medium with 2% sucrose (w/v), 0.1 mg/L benzylaminopurine, and 3g/L Phytagel stimulated the formation of secondary embryos that resulted in development of large number of doubled haploid plants.

Species of the genus Bidens that have invaded natural communities in Europe were observed. Fourteen species have been introduced in European botanical gardens since the 18th century, but only two of them have become invasive in Russia-Bidensfrondosa and B. connata. B.frondosa demonstrates microevolutional ability in the second distribution range. Nevertheless, it has a low ability of hybridization. B. frondosa has higher competitiveness compared with that of B. connata.

The main results of studies regarding the biology of Sertoli cells under various experimental conditions are considered. Possible potential mechanisms underlying the transition of highly differentiated Sertoli cells to dedifferentiation, limited by proliferation and reproduction and not accompanied by significant phenotypic changes, are discussed.

An attempt to summarize some static morphological renderings of reversible structural alterations of nervous processes, as well as receptor and synaptic terminals, to compare them with the mechanisms of actual transformation of living neurons and to find a common kinetic characteristic for these phenomena has been made. The contractile tone and contraction of processes of living isolated neurons are reported. The dependence of the direction of retraction on the localization of the adhesion site of the isolated cell has been detected. The retraction bulb has been identified as an indicator of all contractions of motor and sensory terminals, both alive and fixed. The process of transformation of growth cones into retraction bulbs has been investigated. The presence of mechanical tension in preterminals and interneuronal contacts has been demonstrated in vitro. Similarity of the kinetics of tissue receptor sensory terminals and growth cones has been detected during in vivo experiments. The kinetics of asynaptic dendrite contraction has been compared to the well-characterized structural variability of dendritic spines. The hypothesis of a common origin of the contractile tone of all nervous elements as one of the principal nonelectrophysiological properties of a neuron has been put forward.

Material for this study was obtained from the hatchery with brood stock of Lates calcarifer that originated from a natural population living in inshore waters off Central Vietnam. Commercial interest in L. calcarifer as an object of mariculture and wildstock fishery has resulted in several publications on its early life history; nevertheless, comprehensive description of early development of L. calcarifer based on controlled incubation of embryos and larvae has remained absent. In the present paper embryonic and larval development to the stage of anlage of pelvic fins is described in detail and illustrated with original drawings of live material on the basis of thermostatically controlled incubation of embryos at 27°C and larvae at 26.8°C (26.5-28.0°C). The first cleavage furrow appeared at the age of 33.5 min. The duration of synchronous cleavage cycle was 16 min. About 80% of all embryos hatched at the age of 18 h. The length of newly hatched larva during the first hour after emergence from the egg shell was 1.63 ± 0.016 mm (1.50-1.75 mm). Chronology of development of the organs, early circulatory system, and pigmentation pattern is given. The dynamics of change in the trunk and caudal body segment number in larva from hatching to the moment of anlage of pelvic fins is shown. The total number of body segments reached the maximum value of 26-27 soon after hatching and then decreased to 20-21 segments. Newly received data are discussed in a comparative context of development of some other teleosts.

The biological activity of ethyl acetate extract of exometabolites from the marine microalgae Phaeodactylum tricornutum against a test culture of Listeria monocytogenes 4b has been investigated. It was shown that the stimulating effect of algal exometabolites on the growth of pathogenic bacteria increased maximally by 98.3% on day 6 of the cultivation, if the active substances comprising the culture liquid of P. tricornutum were separated by successive extractions with solvents in order of increasing polarity (hexane, benzene, ethyl acetate), and by 150% on day 3, if the substances from the ethyl acetate extract of exometabolites were separated by column chromatography. It is noted that the fraction of biologically active substances maximally stimulating the growth of L. monocytogenes can be used to prepare an accumulation medium for detecting these patho- genic bacteria in marine environments and hydrobionts.

The reaction of males of three forest rodent species (Myodes clethrionomys, M. rutilus, Apodemus uralensis) to young animals in comparison with their dimensional characteristics and androgenization level was studied. Demonstration of parental care was detected in males of two vole species (M. clethrionomys and M. rutilus) in case of regular contacts with them (sensitization effect). It was demonstrated that the testosterone concentration in the blood serum, as well as the testosterone content in the testicles of the M. clethrionomys males (demonstrating the parental care), was higher than in the sample of males inclined to infanticide. An increased testosterone content in the testicles and blood serum was also found in the M. rutilus males that had contact with young animas. Neither demonstration of parental care nor significant differences in the testosterone concentration in the testicles and blood serum were detected in the A. uralensis males.

Complexes of mycotoxins in fruticose lichens of 14 species belonging to five genera of the family Parmeliaceae were characterized by size, composition, and content of individual components. It was shown that species of the genus Bryoria always contain five mycotoxins (sterigmatocystin, mycophenolic acid, citrinin, emodin, and alternariol). In Evernia and Pseudevernia, this list is supplemented with zearalenone, diacetoxyscirpenol, and cyclopiazonic acid or fumonisins. It was noted that Alectoria and Usnea are distinguished by a peculiar set of toxic metabolites and occupy an intermediate position according to their number. The similarities and distinctions of the mycotoxin profile in species belonging to the same genus and in specimens from different habitats are discussed.

This paper studies morphometric parameters (body weight, weight of internal organs, body size, etc.) in 170 elk of various sex and age obtained in the Vyatka taiga area in winter. A number of physiological parameters (specific metabolism and thermal conductivity, heat loss rate, etc.) characterizing the metabolic rate and energy balance in the body were calculated for model animals (calf, male, and female). It is noted that in the transition from the first to the second half of winter the specific metabolism in model animals decreased from 20.6, 16.9, and 15.9 to 18.7, 15.4, and 14.5 kcal/(kg day), respectively. It is shown that changes in the rhythm of motor activity of elk are synchronized with the daily air temperature and the maximum flight distance depends on the amount of energy received by the body with food.

The distribution of mycotoxins anc unic acid in the thallus of epigenous fruticose lichens Alectoria ochroleuca; several species of the genera Cladonia, Cotraria, and Flavocetraria; foliose lichens Nephroma arcticum; and six species of the genus Peltigera were studied by mnzyme-linked immunosorbent assay. The mycotoxin content was lower in the top or apical parts of the thalli than in the basal parts and in dead areas. Differences in the distribution of usnic acid were insignificant in the majority of species, but in Cladonia stellaris and N. arcticum lichens the content of this metabolite in the upper and pc ripheral areas was higher than in the basal parts.