Peter A. Smirnov

@rambler.ru

Department of invertebrate zoology SPbU, Laboratory of parasitic worms and protists, ZIN RAS
SPbU, ZIN RAS

Peter A. Smirnov


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https://researchid.co/san_petri

RESEARCH INTERESTS

invertebrate zoology
10

Scopus Publications

Scopus Publications

  • Why has the ‘miracidium’ of Notocotylidae (Trematoda: Digenea) lost all stage-specific traits?
    Peter A. Smirnov, Anna Gonchar
    Parasitology Research, 2025
    Digeneans of the family Notocotylidae differ from other digeneans in their peculiar eggs. The eggs feature a pair of long filaments extending from their poles, and their contents differ significantly from what we expect to observe in the eggs of digeneans. Instead of a ciliated miracidium larva, the notocotylid egg contains a tiny few-celled mother sporocyst. This sporocyst infects a snail host following accidental ingestion of the egg. Previous transmission electron microscope studies elucidated the structure of the sporocyst and proposed a mechanism of the injection relying on the structure called the opercular cord, but the data were insufficient to describe certain details. Here, we present ultrastructural data on the egg of Paramonostomum, clarifying the nature of the injection apparatus and providing the missing details of the in-egg mother sporocyst structure. We found the opercular cord to be part of the eggshell associated with the vitelline membrane. We also elucidated the intertwining connection between the germ cells and the sporocyst's tegument and explored 'nuage' granules present in the cytoplasm of the germ cells, providing evidence for identification of these cells as the germ ones. We discuss our findings in the context of transition of miracidia to a passive strategy of snail infection.
  • Erratum to: Reconstruction of Derogenes varicus Miracidium (Digenea: Derogenidae): First Ultrastructural Description of Spines on the Surface of Hemiurata Larvae (Doklady Biochemistry and Biophysics, (2024), 518, 1, (346-354), 10.1134/S1607672924701059)
    P. A. Smirnov, D. Yu. Krupenko
    Doklady Biochemistry and Biophysics, 2024
    An Erratum to this paper has been published: https://doi.org/10.1134/S1607672924550015
  • Reconstruction of Derogenes varicus Miracidium (Digenea: Derogenidae): First Ultrastructural Description of Spines on the Surface of Hemiurata Larvae
    P. A. Smirnov, D. Yu. Krupenko
    Doklady Biochemistry and Biophysics, 2024
    We performed a detailed ultrastructural reconstruction of the "passive" miracidium of Derogenes varicus Muller, 1784 , a species from the Hemiurata group. The miracidium is highly miniaturized and simplified in comparison with the "active" miracidia. For the first time we elucidated the nature of the spines on the surface of the hemiuroid larva: they are derivatives of the epithelial plates. The anterior end of the larva is equipped with three epithelial plates that bear both spines and cilia. The major part of the miracidial surface is formed by the tegument. The nervous and excretory systems of the D. varicus miracidium are extremely reduced. Single undifferentiated cell comprises the germinal material of the miracidium. We discuss the trends of evolution of hemiuroid miracidia that are associated with the transition to passive strategy of infection.
  • The structure of the Cryptocotyle lingua miracidium (Digenea: Opisthorchiidae)
    Peter A. Smirnov, Anna Gonchar
    Zoologischer Anzeiger, 2024
  • High prevalence of Trypanosoma theileri-like trypanosomes and scarcity of monoxenous trypanosomatids in tabanids of Northwestern Russia
    Anna I. Ganyukova, Daria Drachko, Marina N. Malysheva, Alexander O. Frolov, V. V. Agasoi, et al.
    Protistology, 2024
    The hematophagous flies of the family Tabanidae are worldwide-distributed nuisance pests and at the same time vectors of various diseases for humans and livestock, including trypanosomiases.No large-scale studies dedicated to trypanosomatid infections in tabanids have been performed so far in Russia and this work intended to close this gap.Using light microscopy and molecular analyses, we screened 1180 individuals (26 species, 6 genera) of female tabanids collected in Northwestern Federal District.Our results demonstrated a high prevalence of trypanosomes (43%) belonging to the two major lineages of the Trypanosoma theileri species complex (TthI and TthII) and only a few cases of monoxenous trypanosomatids' presence.We performed statistical assessment of the obtained data and revealed differential prevalence of the two trypanosome lineages in different tabanid taxa.We also described the temporal dynamics of infections in tabanid populations: early start of trypanosome acquisition with the steady growth of overall prevalence during the season, but distinct trajectories for the prevalence of the two trypanosome haplotypes.We provided a detailed explanation of the observed results based on the available data on the biology of tabanids and proposed hypotheses concerning the reasons for distribution of trypanosomes in the peripheral blood of the ruminant hosts and trypanosome specificity.
  • Miracidium of Steringophorus furciger (Digenea:Fellodistomidae) and other passive Bucephalata larvae
    Peter A. Smirnov, Anna Gonchar
    Zoomorphology, 2023
  • Fine structure of a tiny gymnophalloid miracidium (Digenea)
    Peter A. Smirnov, Andrey A. Dobrovolskij
    Journal of Morphology, 2021
    We elucidate the morphology of the miracidia with passive strategy of infection. In contrast to the well‐studied “active” free‐swimming larvae (e.g., those of Schistosoma, Fasciola, Echinostoma), “passive” miracidia do not search for their hosts in the external environment. The infection occurs only after the mollusk ingests the eggs with the larvae. The miracidia of this type are extremely miniaturized organisms whose somatic elements are reduced compared to the “active” forms. The details of the structure are unknown for the majority of taxa with “passive” larvae. Here, we provide the first description of a gymnophalloid miracidium based on ultrastructural data. The larva of Parvatrema affinis Jameson & Nicoll, 1913 consists of 21 cells. Its nervous and excretory systems are reduced to the extreme level. Its penetration apparatus includes two crystalloid gland‐cells, unique among digeneans. The “true” epithelium of its body wall is a novelty never described for any other miracidium. We compare the structure of gymnophalloid and bucephaloid miracidia trying to determine possible ancestral features of the larvae in this digenean lineage and trends of their evolution.
  • Ultrastructure and functional morphology of dermal glands in the freshwater mite Limnochares aquatica (L., 1758) (Acariformes, Limnocharidae)
    Andrey B. Shatrov, Elena V. Soldatenko, Vitaliy A. Stolbov, Petr A. Smirnov, Olga A. Petukhova
    Arthropod Structure and Development, 2019
  • What is hidden under an eggshell? Ultrastructural evidence on morphology of “passive” prosorhynchus squamatus miracidium (digenea: Bucephalidae)
    P. A. Smirnov, A. A. Dobrovolskij
    Invertebrate Zoology, 2019
    Miracidium is the larva of digeneans that serves to infect mollusks (first intermediate hosts). Many digeneans possess miracidia that use active strategy of infection. These larvae swim by ciliary action to the specific mollusks and penetrate into them. Miracidia of other digeneans follow an essentially different, passive way of infection: they rest in the eggshells and the mollusks become infected only after they ingest the eggs with larvae inside. The differences in strategies of infection are reflected in contrasting morphologies of the two types of miracidia. “Passive” ones are always smaller and “simplified”. However, very little is known about details behind this reduction. This is due to the evident lack of ulstrastructural data on “passive” forms. Here we present the TEMreconstruction of P. squamatus “passive” miracidium and compare it with the well-known structure of “active” forms. How to cite this article: Smirnov P.A., Dobrovolskij A.A. 2019. What is hidden under an eggshell? Ultrastructural evidence on morphology of “passive” Prosorhynchus squamatus miracidium (Digenea: Bucephalidae) // Invert. Zool. Vol.16. No.4. P.361–376. doi: 10.15298/invertzool.16.4.04
  • Crithidia dobrovolskii sp. n. (Kinetoplastida: Trypanosomatidae) from parasitoid fly Lypha dubia (Diptera: Tachinidae): morphology and phylogenetic position
    Anna I. Ganyukova, , Marina N. Malysheva, Petr A. Smirnov, Alexander O. Frolov, and
    Protistology, 2019
    The article provides characteristics of a new parasite, Crithidia dobrovolskii sp.n., which was isolated from the tachinid fly captured in the Leningrad Region of Russia. The presented description of Crithidia dobrovolskii sp.n. is based upon light microscopic, ultrastructural, and molecular phylogenetic data. Molecular phylogenetic analyses of SSU rRNA gene and GAPDH gene sequences have demonstrated that the new species is most closely related to Crithidia fasciculata.