Biology Bulletin Reviews最新文献

Abstract

Based on materials on the infection of seabirds and invertebrates of the Franz Josef Land archipelago (FJL) collected during expeditions in 1991–1993, a species identification of the acanthocephalan Polymorphus phippsi and an analysis of the parasitic system it forms in the High Arctic were carried out. Acanthocephala is classified as hydrotopic parasites of the marine ecological group. The central link in its parasitic system is the main intermediate host—the amphipod Gammarus setosus, which is widespread in the coastal waters of the shelf zone of the entire Arctic basin. The maintenance of the acanthocephalan population in the FJL and in the European Arctic as a whole is carried out by one obligate definitive host—the common eider Somateria mollissima. The remaining bird species in which P. phippsi infection has been recorded (arctic tern, black guillemot, purple sandpiper, and several gulls) play the role of facultative and/or eliminative hosts. The flows of infection passing through different categories of hosts in the parasitic system of P. phippsi were calculated. The involvement of birds phylogenetically distant from eiders into the transmission of P. phippsi is facilitated by the trophic relationship of Arctic birds with amphipods of the coastal complex, including G. setosus. The phenomenon of nonspecific parasitism in the Arctic is also characteristic of a number of other species of avian helminths. In addition to the characteristics of the diet of birds in the Arctic, this may be determined by a decrease in their resistance to parasite infection when living in extreme Arctic conditions. It has been suggested that the parasitic systems of bird helminths in the Arctic model the situation that developed in marine coastal refugia of the late Pliocene–Pleistocene, where micro- and macroevolutionary events took place due to host radiation of parasites.

Abstract

On the basis of 20 years of research in Northeast Russia, issues concerning the validity, ecology, and zoogeography of N. tumidus van Cleave et Bangham, 1949 are discussed. This paper presents data on the infection of arctic chars of the genus Salvelinus by acanthocephalans in several mountain lakes of this region. Finds of N. tumidus in whitefish (Coregonidae) from lakes of other mountain regions of Southern and Western Siberia are described. Paleogeographic reconstructions of vast lake basins in Siberia are considered. These hypotheses give an idea of probable habitats of ancestral forms of salmonid fish which currently serve as obligatory definitive hosts of N. tumidus in their Asian range. Based on the available data on the ways of formation of isolated populations of arctic char and whitefish in continental mountain areas, it is suggested that the modern range of the acanthocephalan N. tumidus is related to the distribution of such fish populations in North Asia.

Keywords:

Acanthocephala, Neoechinorhynchus tumidus, arctic chars, coregonid fish, mountain lakes, Siberia, Northeast Russia.

Abstract

The phenotypic diversity of the population of Proteocephalus longicollis (Zeder 1800) cestode from Coregonus lavaretus (Linnaeus 1758) whitefish from Lake Kamennoe (Kostomukshsky Nature Reserve, North Karelia) was studied. The variability of intrapopulation groupings of P. longicollis (identified by discrete traits of the attachment and trophic–reproductive complexes) is described. The diversity, similarity, and difference of morphometric indices and the role of individual groupings in the phenotypic diversity of the population were estimated. It was demonstrated that the phenotype with a clavate scolex form the core of the P. longicollis population. Such a phenotype is well differentiated from the nucleus-like and lanceolate phenotypes by a larger size of the scolex and lower variability. It was concluded that the ecological type of the host’s behavior, which determines the niche occupied by a population, is an important factor shaping the phenotypic diversity and structure of the helminth population. The adaptive response of the P. longicollis population to a change in the host species is provided by a change in the frequencies of phenotypes that differ in the attachment traits.

Abstract

The aim of this study was to compare the parameters of the parasite species richness in common shrew Sorex araneus during the periods of its highest and lowest population abundance. The analysis was based on a comparative assessment of parasitic infracommunities and accumulation curves of helminth species richness. The significance of the observed differences was determined by analyzing the coefficients of the power regression equation modeling the dynamics of accumulation of species richness of parasitic communities. It has been shown that with an increase in the number of common shrews, there is a decrease in the average values of species richness of parasitic infracommunities, while their β-diversity increases. Differences in the accumulation curves of parasite species richness at low and high host abundance are determined by the peculiarities of the distribution of species richness in helminth infracommunities. During the period of relative depression in the number of S. araneus, the structure of parasite infracommunities was dominated by individuals with average values of species richness. During years of high shrew abundance, their population is characterized by a predominance of individuals with a poor species richness of parasites.

Abstract

The myxosporean Myxidium rhodei Leger, 1905 is a common parasite of Palaearctic cyprinids localized primarily in the Bowman capsules of fish kidneys. In Lake Baikal, roach Rutilus rutilus has been infected with myxosporidium M. rhodei at a high prevalence (94–100%) and intensity of invasion (up to 6000 pseudocysts) in 1999–2021. In this work, we analyzed the age-related, seasonal, long-term dynamics and the spatial distribution of M. rhodei infestation of roaches in Chivirkuy Bay of Lake Baikal. The parasite begins to be registered in yearlings, then the intensity of invasion of roach M. rhodei increases, reaching a maximum in middle-aged fish, and decreases in older fish. M. rhodei has an annual development cycle in roaches. Fluctuations in the infection of M. rhodei in the studied fish over 25 years of observation correlate with long-term changes in the hydrological regime of Lake Baikal.

Abstract

Studying the proteome of helminths is of fundamental and applied importance, as it helps to find the molecular mechanisms underlying the life activity of parasitic organisms and the relationships in the parasite–host system. It also allows us to identify molecules that can be proposed as targets for creation of anthelmintic drugs. The review collects available information on the composition of proteins of parasitic worms. Based on data from genomic, transcriptomic and proteomic analysis of a small number of well-studied species, a primary description of the main groups of parasite proteins—structural proteins, carbohydrate metabolism enzymes, and proteins responsible for the body’s resistance to stress—was carried out. Comparative studies of the protein composition of some helminths at different stages of the life cycle are presented, and proteins typical for larvae and imago parasites are described. Works devoted to the study of proteins that parasites secrete into the external environment (secretomes) are discussed separately. It has been shown that the secretome proteins include various proteolytic enzymes, proteins of the detoxification system, signaling molecules, etc.

Abstract—Bipolaris sorokiniana is circumglobally widespread root and leaf pathogen of cereals and grasses. It can grow both endo- and epiphytically and also survive in the soil. The chemical mechanisms of such good persistence of the fungus are poorly studied. This study assays the biological (phytotoxic, antimicrobial, insecticidal, and cytotoxic) activity of extracts from cultures of four B. sorokiniana of distinct geographical origin produced on three different media. The composition of media and, to lesser extent, origin of the isolate affected the yield of extractive matter, spectrum, and level of biological activity of extracts. Extracts from liquid culture mycelium demonstrated relatively high insecticidal activity to wheat aphid and galleria, while extracts from solid cultures were highly cytotoxic to the Sf9 cell line. Phytotoxic activity was the most pronounced in extracts from culture liquids. No correlation was found between phytotoxic and insecticidal or cytotoxic activity of extracts indicating possible production of insecticidal metabolites by B. sorokiniana isolates. The revealed insecticidal properties of the fungal metabolites were able to explain its high competition activity for the plant substrate and broaden the biotechnological potential B. sorokiniana of as a producer of bioactive compounds.

Abstract—

The soil mycobiota of the Apatity city was first characterized. Significant differences in the quantitative and qualitative parameters of urban soil microfungal complexes in the Arctic zone in comparison with zonal soils were revealed. It was shown that the fungal biomass in the soil of the recreational zones of Someriumbric Leptic Entic Podzol (Arenic) was 0.18–0.20 mg/g; in the background forest soil Leptic Albic Podzol (Arenic, Folic), 0.31 mg/g. The lowest values (0.04–0.08 mg/g) was typical of zones with no vegetation and a densely compacted surface (playground – Leptic Entic Podzol (Arenic, Technic), unpaved pedestrian walkway – Someriubric Leptic Albic Podzol (Arenic). In the recreational and forest zones, soil fungi were mainly in the mycelium form (66–70% of the total biomass), while in the residential and agricultural zones soils in the form of spores. Spores were mainly represented by small forms up to 3 µm. The number of large spores was insignificant, but they were mainly detected in the soil of the residential zone. The number of ITS rRNA gene copies of fungi in soils of different functional zones varied from 4.0 × 10⁹ to 1.14 × 10¹⁰ copies/g of soil, with the highest values in the natural forest Podzol and Podzol of the unpaved pedestrian walkway. The number of microfungi CFU in topsoil ranged from 1 × 10³ to 9 × 10⁴ CFU/g of soil, reaching maximum values in the Someriumbric Leptic Entic Podzol (Arenic, Technic) soil of the recreational zone. The features of the cultivable microfungi distribution on the soil profile in different functional zones were revealed: in the residential zone Podzol, the maximum accumulation of fungi was noted in the subsoil, while in the recreational, agricultural and forest zones, their maximum number was noted in the topsoil. However, the first two differed from the background one in the absence of a second maximum accumulation of microfungi in the subsoil illuvial spodic horizon (Bs). In general, urban soils were characterized by a low species diversity of saccharolytic microfungi and a specific structure significantly different from the background soils. The genus Penicillium was characterized by maximum species diversity. Trichocladium griseum and Penicillium dierckxii dominated in the microfungi communities in the residential zone soil; P. melinii - in the recreational zone and in playground soils; microfungi of the genus Fusarium - in the agricultural zone soil Umbric Entic Podzol (Arenic); and P. decumbens - in the background forest soil.

Abstract

Currently, special attention is being paid to research on the use of residual biomass of Aspergillus fungi as a substrate for the production of food and feed ingredients. The most promising method is biocatalytic conversion of mycelial biomass polymers, which increases the availability of biologically valuable cell components. The objective of the present study to develop conditions for the enzymatic destruction of cell wall polysaccharides and protein substances of fungal biomass and secondary raw materials of enzyme production, to obtain peptide-amino acid ingredients. It has been established that the use of the enzymatic system, including intracellular proteinases and peptidases and a complex of exogenous β-glucanases, as well as regulation of the duration of their exposure, provide for the production of fermentolysates with a given structural fractional composition. Molecular mass (MM) distribution studies of peptide fractions in the fungal biomass of fermentolysates showed that over 6 h of hydrolysis, the proportion of peptides with MM over 29.0 kDa decreased by 2.8 times, and over 12 h, by 4.7 times. The content of low molecular weight peptides with MM less than 1.6 kDa increased 1.4 times, which accounted for 47.9% of the total. Comparative analysis of the spectra of peptides with MM less than 1000 Da in enzyme isolates of fungal biomass after 6 and 12 h of hydrolysis showed significant differences in their compositions. The contents of peptides with MM less than 500 Da and of free amino acids increase with an increase in hydrolysis duration by 1.6 times. The results confirm the promise of creating functional ingredients and dietary supplements enriched in a peptide–amino acid component with a predominant content of free amino acids and short bioactive peptides resulting from enzymatic treatment of fungal biomass.

Abstract—A halo is a concentric zone (5–50 µm) of the altered surface of the leaf epidermis of wheat around the penetration site of the causative agent of powdery mildew Blumeria graminis. Halo variability was studied in a control and after treatment with metabolic inhibitors (3-amino-1,2,4-triazole, bisindole-maleimide hydrochloride, diphenyleniodionium chloride, 3-isobutyl-1-methylxanthine, catalase, lanthanum nitrate). After amido black was staining, the epidermis fragments were observed as monochromatic circular blue, or bicolor red and blue structures, or as a system of several purple-red, blue, or slightly colored rings. All treatments contributed to a significant reduction in the rate successful penetration of the pathogen into plant cells with the formation of haustoria, the marker of susceptibility at the tissue level in this pathosystem. Halo sizes were increased by treating with 3-amino-1,2,4-triazole, a peroxidase and catalase inhibitor, and also by treating catalase, an enzyme that degrades hydrogen peroxide. Treatment with lanthanum nitrate, which blocks calcium channels, led to a significant decrease in the halo diameter. Halo associated with haustoria, were 1.5 times smaller compared with those observed in the absence of successful development of the pathogen. The correlation between the sizes of such halos and the occurrence frequency of haustoria is shown for the first time. The average sizes of paired large and small halos for each variant, as well as the average distances between them, reliably correlated with each other and weakly correlated with the number of haustoria. The data indicate the possibility of using some halo parameters in diagnosing the local viability of individual infectious units of B. graminis, as well as in tests for the wheat plant resistance to powdery mildew.