Ашық рұқсат
Рұқсат берілді
Тек жазылушылар үшін
Том 84, № 3 (2023)
Articles
Glutamate and GABA receptors in non-neural animals (Placozoa): Preadaptation to neural transmission
Аннотация
Origins of neural system is one of the major transitions in planetary evolution. Many details of these transitions are still unknown. In particular, high diversity of neurotransmitters lacks convincing explanation so far. We analyze homologues of neuronal glutamate and gamma-aminobutyric acid (GABA) receptors of Placozoa – animal phyla lacking neurons but displaying motility and complex behaviour. Phylogenetic analysis and comparison of amino acids in ligand-binding pockets show that glutamate and GABA-like receptors of Placozoa are surprisingly numerous, diverse and fast-evolving. All these traits are characteristic of odorant rather than neurotransmitter receptors of higher animals. We argue that chemoreception system was an important source of diverse receptors for emerging nervous system to recruit, and that amino acid neurotransmitters (glutamate, GABA, glycine) were relevant external stimuli for early animals before the emergence of nervous system.
163-176
Larva morphology of shore flies Ephydra riparia and Paracoenia fumosa (Diptera: Ephydridae) and adaptation of Diptera to increased salinity
Аннотация
Larvae of many shore fly species (family Ephydridae) are adapted to living in water with high or extremely high salinity. Little is known about the morphological and physiological foundations of such adaptation. We described the details of the morphology of third-instar larvae of two shore flies: Ephydra riparia and Paracoenia fumosa and presented the scanning electron microscopy (SEM) images. For the first time, by silver-staining and SEM, we proved that the larvae of both studied species had anal organs (AO) – specialized structures that serve an osmoregulatory function and are responsible for the transport of ions from the environment to the larval hemolymph (but not in the opposite direction). We compared the larvae morphology of the studied species with some other shore fly species from the genera Ephydra, Paracoenia, Hydrellia, and Coenia, as well as with larvae of the model species Drosophila melanogaster (family Drosophilidae). Special attention was paid to the morphology of AO, which contribute to the adaptation of larvae to increased salinity. Extremely halophilic species either do not have AO, or they are poorly developed, while moderately halophilic shore flies have more developed features connected with the permeability of the AO cuticle and active ion transport. These features are most developed in freshwater shore flies. AO activity can vary due to the shape and area of the AO, the smoothness or wrinkling of the cuticle, and the presence of nanoscale pits on it. Described variability of AO structure is probably adaptive since, at high salinity, both the permeability of the AO cuticle and the active transport of ions from the environment to the hemolymph become less beneficial or even harmful.
177-194
The phenomenon of marine bioprospecting
Аннотация
Bioprospecting (bioexploration or biosearch), which has taken shape since the end of the 90s of the last century, is developing rapidly. In recent decades, the dynamics of scientific publications on this topic has increased many times. Marine bioprospecting, as part of the general research direction, is characterized by an extremely wide range of studies, most of which are still in the phase of accumulating information about the genetic and biochemical diversity of biological material. In order to assess the potential of bioprospecting, a review of the results of the conducted studies was carried out. Within its framework, the periodization of the biosearch was carried out, the scale, the main factors, the problems, and the economic foundation of bioprospecting development are identified. The analysis and classification of methodological concepts is carried out. The role of information is revealed and the consequences of the development of bioprospecting are considered. The significant lag of the Russian marine bioprospecting requires taking serious steps toward the development of important and promising directions such as the creation of appropriate infrastructure and new forms of research organizations, the consolidation of the scientific community, the inclusion of business and government structures in the process.
195-214
Bird population dynamics during the regenerative succession of mossy pine woodland in southwestern Belarus
Аннотация
Disturbed forest ecosystems are characterized by significant spatial and temporal changes. As a part of the study on bird communities, changes in bird abundance during the secondary succession of a cleared mossy pine woodland in southwestern Belarus were investigated. The purpose of the work was to determine the inter-annual dynamics of bird species abundance and to assess the variability of individual species abundance during the secondary succession of the mossy pine woodland. The material was collected in 2000–2019. Line transects were set to conduct bird counts in ecosystems at different stages of succession. For the data processing, generally accepted methods of statistical analysis were used. The species diversity of birds was found to increase from 8 to 42 species, the overall abundance from 171.7 to 587.1 birds/km2 during the succession (6 stages, from 1 to 90 years in age). The abundance of species (birds/km2) and inter-annual variability during 11 seasons were determined. The coefficient of variation (CV) was the highest (71.00–82.50%) for species whose abundance did not exceed 1.0 birds/km2. The average abundance of species varied considerably, e.g., among passerines at the 80–90-year old stage from 1.1 birds/km2 (Little Flycatcher) to 153.7 birds/km2 (Chaffinch). Bird populations with high abundance turned out to be the most stable, for example at the last two successional stages the CV of the Chaffinch is 6.02 and 7.16%. For species with average abundance the variability is found to be low or medium (varies from 11.90 to 36.20%), for species with low abundance the CV varies from 17.68 to 82.50%. All six stages of succession were dominated by nesting migratory birds, which account for 75.0% of the species in the first stage of succession to 52.4% in the fifth and sixth stages. Near and distant migrants form the basis of the bird community at all stages. Populations of sedentary species and distant migrants are more stable than those of near migrants.
215-228
Seasonal dynamics of shoots growth in Forsythia ovata Nakai plants: Rhythmicity of apical and radial growth
Аннотация
The aim of the study was to establish the type (linear or non-linear) and shape (presence of extremes and trends) of the time dependences of apical and radial growth rates for shoots of two types (branching and formation) in woody plants. The object of the study was an introduced in the Middle Urals ornamental early-flowering shrub species Forsythia ovata Nakai. Seasonal dynamics of morphometric parameters of two types of shoots, which differ in intensity of growth and origin (developing from the apical or dormant buds of the skeletal branch respectively), was examined. Also, there was made an assessment of their relationship with air temperature and precipitation values. Apical and radial growth are accompanied by oscillations of increments. The duration of individual phases of oscillations is about 7 or more days, which makes it possible to attribute this phenomenon to infradian growth rhythms. The weak relationship between the characteristics of the observed oscillations and weather conditions indicates the predominantly endogenous nature of the observed morphogenetic processes. The growth of formation shoots begins 4 weeks later than branching shoots. This delay is apparently related to the time necessary for activation of dormant bud growth. Seasonal dynamics curves of rates and accelerations of the apical and radial shoot’s growth have the shape of previously unobserved oscillations with phases fading in amplitude and changing in duration. The growth ends 1–2 months before the environmental conditions become unfavorable. The oscillations of the growth rate of shoots are apparently associated with the action of two or more differently directed factors, which determine the increase in volume of different segments of the shoot. These factors include the different contribution of cell division and elongation to the change in the geometric dimensions of the apical meristem domains. The main differences in the seasonal dynamics of the apical and radial increments for both types of shoots are: the duration of growth (6–8 and 4 weeks, respectively), the number of extremes, the amplitude and the duration of individual phases of oscillations. Higher amplitudes of the growth rate oscillations in shoots formation compared with branching shoots, cause bigger values of the formation shoots total increments. The dynamic curves of the apical growth rates have two maxima, while those of the radial growth have only one. Each type of growth, despite the delay in the onset of the formation shoots, has the same total duration. The shapes of curves of seasonal changes in speeds and accelerations of shoot growth values are also similar for different types of shoots. These similarities indicate that shoots have the same “programs” of growth regulation, ultimately determined by the genotype. The rhythmic growth of both types of shoots during the season suggests the existence of the relationship in time between the rates of division and growth of cells located in functionally different groups of cells in the apical meristem zone.
229-240