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Alexander V. Kalachev
Laboratory of Embryology, A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, 690041 Vladivostok, Russia

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Journal article
Published: 23 June 2021 in International Journal of Molecular Sciences
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Exogenous application of double-stranded RNAs (dsRNAs) and small-interfering RNAs (siRNAs) to plant surfaces has emerged as a promising method for regulation of essential genes in plant pathogens and for plant disease protection. Yet, regulation of plant endogenous genes via external RNA treatments has not been sufficiently investigated. In this study, we targeted the genes of chalcone synthase (CHS), the key enzyme in the flavonoid/anthocyanin biosynthesis pathway, and two transcriptional factors, MYBL2 and ANAC032, negatively regulating anthocyanin biosynthesis in Arabidopsis. Direct foliar application of AtCHS-specific dsRNAs and siRNAs resulted in an efficient downregulation of the AtCHS gene and suppressed anthocyanin accumulation in A. thaliana under anthocyanin biosynthesis-modulating conditions. Targeting the AtMYBL2 and AtANAC032 genes by foliar dsRNA treatments markedly reduced their mRNA levels and led to a pronounced upregulation of the AtCHS gene. The content of anthocyanins was increased after treatment with AtMYBL2-dsRNA. Laser scanning microscopy showed a passage of Cy3-labeled AtCHS-dsRNA into the A. thaliana leaf vessels, leaf parenchyma cells, and stomata, indicating the dsRNA uptake and spreading into leaf tissues and plant individual cells. Together, these data show that exogenous dsRNAs were capable of downregulating Arabidopsis genes and induced relevant biochemical changes, which may have applications in plant biotechnology and gene functional studies.

ACS Style

Konstantin Kiselev; Andrey Suprun; Olga Aleynova; Zlata Ogneva; Alexander Kalachev; Alexandra Dubrovina. External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana. International Journal of Molecular Sciences 2021, 22, 6749 .

AMA Style

Konstantin Kiselev, Andrey Suprun, Olga Aleynova, Zlata Ogneva, Alexander Kalachev, Alexandra Dubrovina. External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana. International Journal of Molecular Sciences. 2021; 22 (13):6749.

Chicago/Turabian Style

Konstantin Kiselev; Andrey Suprun; Olga Aleynova; Zlata Ogneva; Alexander Kalachev; Alexandra Dubrovina. 2021. "External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana." International Journal of Molecular Sciences 22, no. 13: 6749.

Research article
Published: 26 October 2020 in Journal of Morphology
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The process of spermatogenesis and spermatozoon morphology was characterized from a deep‐sea bivalve, Calyptogena pacifica (Vesicomyidae, Pliocardiinae), a member of the superfamily Glossoidea, using light and electron microscopy. Spermatogenesis in C. pacifica is generally similar to that in shallow‐water bivalves but, the development of spermatogenic cells in this species has also some distinguishing features. First proacrosomal vesicles are observed in early spermatocytes I. Although, early appearance of proacrosomal vesicles is well known for bivalves, in C. pacifica, these vesicles are associated with electron‐dense material, which is located outside the limiting membrane of the proacrosomal vesicles and disappears in late spermatids. Another feature of spermatogenesis in C. pacifica is the localization of the axoneme and flagellum development. Early spermatogenic cells lack typical flagellum, while in spermatogonia, spermatocytes, and early spermatids, the axoneme is observed in the cytoplasm. In late spermatids, the axoneme is located along the nucleus, and the flagellum is oriented anteriorly. During sperm maturation, the bent flagellum is transformed into the typical posteriorly oriented tail. Spermatozoa of C. pacifica are of ect‐aqua sperm type with a bullet‐like head of about 5.8 μm in length and 1.8 μm in width, consisting of a well‐developed dome‐shaped acrosomal complex, an elongated barrel‐shaped nucleus filled with granular chromatin, and a midpiece with mainly four rounded mitochondria. A comparative analysis has shown a number of common traits in C. pacifica and Neotrapezium sublaevigatum.

ACS Style

Olga V. Yurchenko; Oleg G. Borzykh; Alexander V. Kalachev. Ultrastructural aspects of spermatogenesis in Calyptogena pacifica Dall 1891 (Vesicomyidae; Bivalvia). Journal of Morphology 2020, 282, 146 -159.

AMA Style

Olga V. Yurchenko, Oleg G. Borzykh, Alexander V. Kalachev. Ultrastructural aspects of spermatogenesis in Calyptogena pacifica Dall 1891 (Vesicomyidae; Bivalvia). Journal of Morphology. 2020; 282 (1):146-159.

Chicago/Turabian Style

Olga V. Yurchenko; Oleg G. Borzykh; Alexander V. Kalachev. 2020. "Ultrastructural aspects of spermatogenesis in Calyptogena pacifica Dall 1891 (Vesicomyidae; Bivalvia)." Journal of Morphology 282, no. 1: 146-159.

Brief communication
Published: 09 September 2020 in Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
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Larvae of many echinoids are known to be phenotypically plastic and capable of changing the growth rate of their post‐oral arms depending on the microalgae concentration in their habitat. As literature data show, developing larvae use chemosensation to detect algae in the environment and “adjust” the rate of growth of their post‐oral arms through dopamine signaling. According to our results, dopamine has a significant effect on the post‐oral arm growth in early larvae of two sea urchin species, Mesocentrotus nudus and Strongylocentrotus intermedius. The dopamine effect depends on concentration: the higher the dopamine concentration in the water, the shorter the post‐oral arms. We suggest that the pattern of response to variation in dopamine concentration, manifested by early larvae of both species, is similar to that observed at different concentrations of microalgae.

ACS Style

Alexander V. Kalachev. Effect of dopamine on early larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution 2020, 334, 373 -380.

AMA Style

Alexander V. Kalachev. Effect of dopamine on early larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 2020; 334 (6):373-380.

Chicago/Turabian Style

Alexander V. Kalachev. 2020. "Effect of dopamine on early larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius." Journal of Experimental Zoology Part B: Molecular and Developmental Evolution 334, no. 6: 373-380.

Original research article
Published: 30 June 2020 in Frontiers in Neuroanatomy
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In bivalves neurotransmitters are involved in a variety of behaviors, but their diversity and distribution in the nervous system of these organisms remains somewhat unclear. Here, we first examined immunohistochemically the distributions of neurons containing different neurotransmitters, neuropeptides, and related enzymes, as well as the proliferative status of neurons in the ganglia of the mussel Crenomytilus grayanus. H-Phe-Met-Arg-Phe-NH2 (FMRFamide), choline acetyltransferase (ChAT), γ-aminobutyric acid (GABA) and tyrosine hydroxylase (TH) were found to be expressed by neurons in all the ganglia, whereas serotonin (5-HT) neurons were found only in the cerebropleural and pedal, but not visceral ganglia. Moreover, incubation of living mussels in the presence of a 5-HT precursor (5-HTP) confirmed the absence of 5-HT-containing neurons from the visceral ganglia, indicating that the “serotonin center” of the visceral nervous system is located in the cerebral ganglia. Furthermore, immunostaining of molecules related to neurotransmission together with α-acetylated tubulin demonstrated that this cytoskeletal protein may be a potential pan-neuronal marker in bivalves. Adult mussel neurons do not proliferate, but a population of proliferating PCNA-LIP cells which do not express any of the neurotransmitters examined, perhaps glia cells, was detected in the ganglia. These novel findings suggest that the nervous system of bivalves contains a broad variety of signal molecules most likely involved in the regulation of different physiological and behavioral processes. In addition, proliferating cells may maintain and renew glial cells and neurons throughout the lives of bivalves.

ACS Style

Elena Kotsyuba; Alexander Kalachev; Polina Kameneva; Vyacheslav Dyachuk. Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus. Frontiers in Neuroanatomy 2020, 14, 35 .

AMA Style

Elena Kotsyuba, Alexander Kalachev, Polina Kameneva, Vyacheslav Dyachuk. Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus. Frontiers in Neuroanatomy. 2020; 14 ():35.

Chicago/Turabian Style

Elena Kotsyuba; Alexander Kalachev; Polina Kameneva; Vyacheslav Dyachuk. 2020. "Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus." Frontiers in Neuroanatomy 14, no. : 35.

Short communication
Published: 31 August 2019 in Tissue and Cell
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In oysters, nutrients are stored in a special type of cells referred to as vesicular-connective tissue cells (VCT-cells). These cells accumulate and provide nutrient to satisfy various needs of the organism, including gametogenesis. During the annual reproductive cycle, VCT-cells pass through a series of changes in their morphology associated with nutrients mobilization for developing germ cells. The results presented here show an approximately 33-35% increase in the number of autophagic vesicles in cytoplasm of VCT-cells in the gonadal area of C. gigas during the stage of active gametogenesis as compared to the resting stage of reproductive cycle. No destruction of VCT-cells due to autophagy or any other factors was observed, both in males and females. Our results indicate that autophagy does increase in VCT-cells of C. gigas and plays a certain role in nutrient mobilization from these cells.

ACS Style

Alexander V. Kalachev; Olga V. Yurchenko. Autophagy in nutrient storage cells of the Pacific oyster, Crassostrea gigas. Tissue and Cell 2019, 61, 30 -34.

AMA Style

Alexander V. Kalachev, Olga V. Yurchenko. Autophagy in nutrient storage cells of the Pacific oyster, Crassostrea gigas. Tissue and Cell. 2019; 61 ():30-34.

Chicago/Turabian Style

Alexander V. Kalachev; Olga V. Yurchenko. 2019. "Autophagy in nutrient storage cells of the Pacific oyster, Crassostrea gigas." Tissue and Cell 61, no. : 30-34.

Journal article
Published: 29 March 2019 in International Journal of Molecular Sciences
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Recent investigations show that exogenously applied small interfering RNAs (siRNA) and long double-stranded RNA (dsRNA) precursors can be taken up and translocated in plants to induce RNA interference (RNAi) in the plant or in its fungal pathogen. The question of whether genes in the plant genome can undergo suppression as a result of exogenous RNA application on plant surface is almost unexplored. This study analyzed whether it is possible to influence transcript levels of transgenes, as more prone sequences to silencing, in Arabidopsis genome by direct exogenous application of target long dsRNAs. The data revealed that in vitro synthesized dsRNAs designed to target the gene coding regions of enhanced green fluorescent protein (EGFP) or neomycin phosphotransferase II (NPTII) suppressed their transcript levels in Arabidopsis. The fact that, simple exogenous application of polynucleotides can affect mRNA levels of plant transgenes, opens new opportunities for the development of new scientific techniques and crop improvement strategies.

ACS Style

Alexandra S. Dubrovina; Olga A. Aleynova; Alexander V. Kalachev; Andrey Suprun; Zlata V. Ogneva; Konstantin V. Kiselev. Induction of Transgene Suppression in Plants via External Application of Synthetic dsRNA. International Journal of Molecular Sciences 2019, 20, 1585 .

AMA Style

Alexandra S. Dubrovina, Olga A. Aleynova, Alexander V. Kalachev, Andrey Suprun, Zlata V. Ogneva, Konstantin V. Kiselev. Induction of Transgene Suppression in Plants via External Application of Synthetic dsRNA. International Journal of Molecular Sciences. 2019; 20 (7):1585.

Chicago/Turabian Style

Alexandra S. Dubrovina; Olga A. Aleynova; Alexander V. Kalachev; Andrey Suprun; Zlata V. Ogneva; Konstantin V. Kiselev. 2019. "Induction of Transgene Suppression in Plants via External Application of Synthetic dsRNA." International Journal of Molecular Sciences 20, no. 7: 1585.

Short communication
Published: 21 December 2018 in Tissue and Cell
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An ultrastructural study of developing spermatids in sea urchins, Strongylocentrotus intermedius, showed that macroautophagy is involved in formation of residual bodies and removal of excessive cytoplasm by spermatids during spermatogenesis in this species. During late stages of spermatogenesis spermatids sequester excessive cytoplasm into vesicles, surrounded by a double membrane. Subsequently, these vesicles fused to one another into larger vacuoles, up to 1.5 μm in diameter. Finally, the vacuoles transformed into residual bodies by condensing their content into finely granular material of varying electron density, separated from cytoplasm by a single membrane. An immunoelectron microscopic study of late spermatids with the antibodies, raised against microtubule-associated protein 1 A/1B-light chain 3 (LC3), which is a marker of autophagosomes, showed that residual bodies in late spermatids of S. intermedius were LC3-positive.

ACS Style

Alexander V. Kalachev; Olga V. Yurchenko; Konstantin V. Kiselev. Macroautophagy is involved in residual bodies formation during spermatogenesis in sea urchins, Strongylocentrotus intermedius. Tissue and Cell 2018, 56, 79 -82.

AMA Style

Alexander V. Kalachev, Olga V. Yurchenko, Konstantin V. Kiselev. Macroautophagy is involved in residual bodies formation during spermatogenesis in sea urchins, Strongylocentrotus intermedius. Tissue and Cell. 2018; 56 ():79-82.

Chicago/Turabian Style

Alexander V. Kalachev; Olga V. Yurchenko; Konstantin V. Kiselev. 2018. "Macroautophagy is involved in residual bodies formation during spermatogenesis in sea urchins, Strongylocentrotus intermedius." Tissue and Cell 56, no. : 79-82.

Journal article
Published: 01 December 2018 in Invertebrate Zoology
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ACS Style

A. V. Kalachev; O. V. Yurchenko; V. G. Osten. Phenotypic plasticity in pre-feeding larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius. Invertebrate Zoology 2018, 15, 420 -433.

AMA Style

A. V. Kalachev, O. V. Yurchenko, V. G. Osten. Phenotypic plasticity in pre-feeding larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius. Invertebrate Zoology. 2018; 15 (1):420-433.

Chicago/Turabian Style

A. V. Kalachev; O. V. Yurchenko; V. G. Osten. 2018. "Phenotypic plasticity in pre-feeding larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius." Invertebrate Zoology 15, no. 1: 420-433.

Journal article
Published: 24 November 2018 in Tissue and Cell
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Successful gametogenesis in invertebrates is tightly associated with functioning of specific nutrient-storing cells. In oysters, cells of vesicular connective tissue (VCT-cells), also referred to as storage cells, which form a meshwork around gonadal acini, are the major population of cells that accumulate and provide nutrients for developing gametes. During the annual reproductive cycle, populations of developing germ cells and VCT-cells demonstrate the inversely proportional size dynamics: the larger the acini, the smaller the VCT-cells. In the present study, the morphology of VCT-cells in the Pacific oyster, Crassostrea gigas, at the active gametogenesis stage of reproductive cycle has been studied using light and transmission electron microscopy. At this stage, VCT-cells are big, irregularly shaped cells containing large nucleus with a single large nucleolus. The cytoplasm contains weakly developed endoplasmic reticulum, mitochondria in the perinuclear area and at periphery of the cell, numerous lipid droplets, and glycogen particles. Ultrastructure of VCT-cells is similar to the organization of brown adipocytes in mammals. The surface of cells has numerous cytoplasmic processes that are presumably associated with the transport function and provide close interaction with adjacent cells. The spatial relationship between VCT-cells and myoepithelial elements of the gonad area is demonstrated and discussed.

ACS Style

Olga V. Yurchenko; Alexander V. Kalachev. Morphology of nutrient storage cells in the gonadal area of the Pacific oyster, Crassostrea gigas (Thunberg, 1793). Tissue and Cell 2018, 56, 7 -13.

AMA Style

Olga V. Yurchenko, Alexander V. Kalachev. Morphology of nutrient storage cells in the gonadal area of the Pacific oyster, Crassostrea gigas (Thunberg, 1793). Tissue and Cell. 2018; 56 ():7-13.

Chicago/Turabian Style

Olga V. Yurchenko; Alexander V. Kalachev. 2018. "Morphology of nutrient storage cells in the gonadal area of the Pacific oyster, Crassostrea gigas (Thunberg, 1793)." Tissue and Cell 56, no. : 7-13.

Journal article
Published: 17 January 2018 in Zoological Journal of the Linnean Society
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The soft-shell clam Mya arenaria Linnaeus, 1758 is a commercially important fishery resource that occurs in boreal and temperate environments in the Northern Hemisphere. Whether the soft-shell clam is a single species with a circumboreal range or a species complex also comprising Mya japonica Jay, 1857 distributed in the north Pacific has long been debated by malacologists and palaeontologists based on slight differences in shell morphology. We used an integrative taxonomic approach incorporating available Mya spp. mitochondrial COI and 16S rRNA, and nuclear 28S rRNA gene sequences, as well as spermatozoan and shell morphological characters to test the validity of M. japonica and examine the range of soft-shell clam distribution. Although differences in shell morphology were minor, the results from tree topologies, pairwise uncorrected p-distances, Automatic Barcode Gap Discovery (ABGD) and spermatozoan ultramorphological data confirm the validity of M. japonica in both its endemic region in the northwest Pacific, and as here newly reported introduced populations in British Columbia in the northeast Pacific, and show that M. arenaria is distributed in the northeast Pacific, North Atlantic, Barents Sea (Arctic Ocean) and Mediterranean. We estimate these two closely related sister species diverged 4.1–12.5 Myr during early Pliocene to late Miocene, which is consistent with current evolutionary theory regarding M. arenaria. In addition, ABGD indicated the congener Mya truncata Linnaeus, 1758 may represent a species complex, but additional evidence is still needed to clarify its taxonomic status.

ACS Style

Junlong Zhang; Olga V Yurchenko; Konstantin Lutaenko; Alexander Kalachev; Ivan O Nekhaev; Robert Aguilar; Zifeng Zhan; Matthew B Ogburn. A tale of two soft-shell clams: an integrative taxonomic analysis confirms Mya japonica as a valid species distinct from Mya arenaria (Bivalvia: Myidae). Zoological Journal of the Linnean Society 2018, 184, 605 -622.

AMA Style

Junlong Zhang, Olga V Yurchenko, Konstantin Lutaenko, Alexander Kalachev, Ivan O Nekhaev, Robert Aguilar, Zifeng Zhan, Matthew B Ogburn. A tale of two soft-shell clams: an integrative taxonomic analysis confirms Mya japonica as a valid species distinct from Mya arenaria (Bivalvia: Myidae). Zoological Journal of the Linnean Society. 2018; 184 (3):605-622.

Chicago/Turabian Style

Junlong Zhang; Olga V Yurchenko; Konstantin Lutaenko; Alexander Kalachev; Ivan O Nekhaev; Robert Aguilar; Zifeng Zhan; Matthew B Ogburn. 2018. "A tale of two soft-shell clams: an integrative taxonomic analysis confirms Mya japonica as a valid species distinct from Mya arenaria (Bivalvia: Myidae)." Zoological Journal of the Linnean Society 184, no. 3: 605-622.

Journal article
Published: 28 March 2016 in Protoplasma
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Two types of cells were observed in germinative epithelium of male and female sea urchins: germ cells and somatic accessory cells; the latter referred to as nutritive phagocytes. At the onset of gametogenesis, nutritive phagocytes accumulate nutrients and greatly increase in their size. As gametogenesis progresses, the accumulated nutrients are transferred from nutritive phagocytes into developing gametes, and size of the nutritive phagocytes decreases. An electron microscopic study of nutritive phagocytes in sea urchins, Strongylocentrotus intermedius, at different stages of annual reproductive cycle showed for the first time that both macro- and microautophagy take place in nutritive phagocytes. Both processes occur simultaneously and regulate size and composition of nutritive phagocytes in male and female sea urchins. Nutritive phagocytes consume redundant cytoplasm via macroautophagy. Microautophagy is probably involved in consumption of redundant membranes that appear within nutritive phagocytes due to destruction of nutrient-storing globules, macroautophagy, and phagocytosis of germ cells or their remnants.

ACS Style

Alexander V. Kalachev; Olga V. Yurchenko. Microautophagy in nutritive phagocytes of sea urchins. Protoplasma 2016, 254, 609 -614.

AMA Style

Alexander V. Kalachev, Olga V. Yurchenko. Microautophagy in nutritive phagocytes of sea urchins. Protoplasma. 2016; 254 (1):609-614.

Chicago/Turabian Style

Alexander V. Kalachev; Olga V. Yurchenko. 2016. "Microautophagy in nutritive phagocytes of sea urchins." Protoplasma 254, no. 1: 609-614.

Journal article
Published: 23 March 2016 in Journal Of Molluscan Studies
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The present study focuses on two apparent species: the giant thyasirid Conchocele bisecta (Conrad, 1849), which is the dominant species of the benthic community in a gas hydrate area with cold-water methane-rich vents at a depth of about 800 m on the slope off Paramushir Island (Kuril Islands, Sea of Okhotsk) and small unidentified thyasirid bivalves from this same community. An examination of the shell morphology of these thyasirids showed that the small bivalves were in fact young specimens of C. bisecta, characterized by a high individual and age variability. A transmission electron microscopic study of C. bisecta revealed gills with ‘Type 3’ filaments, which were extended abfrontally and had a distinct bacteriocyte zone with extracellular symbionts. The symbiotic bacteria found were spherical, similar to thiotrophic symbionts of other thyasirids. The isotopic δ13С values of C. bisecta soft tissues (from −39.6 to −33.8‰) were much heavier than those of methane in the Paramushir gas-hydrate area and matched the range characteristic of symbiotrophic bivalves harbouring sulphur-oxidizing chemoautotrophic bacteria. The variations in δ13С and δ15N recorded for large and small C. bisecta can be related to ontogenetic differences in life habit: small individuals are totally buried in the sediment, while large ones are half-buried. Data from fatty acid (FA) analysis indicate that sulphur-oxidizing symbionts constitute almost the entire nutrition of C. bisecta, with no significant contribution of symbiotic or free-living methanotrophs. Furthermore, neither FA nor isotopic compositions provided evidence for photosynthetic sources as food items for C. bisecta through filter feeding.

ACS Style

Vladimir I. Kharlamenko; Gennady M. Kamenev; Alexander Kalachev; Serguei I. Kiyashko; Victor Ivin. Thyasirid bivalves from the methane seep community off Paramushir Island (Sea of Okhotsk) and their nutrition. Journal Of Molluscan Studies 2016, 82, 391 -402.

AMA Style

Vladimir I. Kharlamenko, Gennady M. Kamenev, Alexander Kalachev, Serguei I. Kiyashko, Victor Ivin. Thyasirid bivalves from the methane seep community off Paramushir Island (Sea of Okhotsk) and their nutrition. Journal Of Molluscan Studies. 2016; 82 (3):391-402.

Chicago/Turabian Style

Vladimir I. Kharlamenko; Gennady M. Kamenev; Alexander Kalachev; Serguei I. Kiyashko; Victor Ivin. 2016. "Thyasirid bivalves from the methane seep community off Paramushir Island (Sea of Okhotsk) and their nutrition." Journal Of Molluscan Studies 82, no. 3: 391-402.

Journal article
Published: 18 January 2016 in Marine Biology
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Some pairs of oyster species in the genus Crassostrea can produce viable hybrids, and heterospecific fertilization may be symmetric, asymmetric, or very low. For example, with C. angulata and C. gigas, fertilization is equally successful whether the mature oocytes come from the first or the second species. Fertilization is asymmetric between C. ariakensis and C. virginica, i.e., it is higher when C. ariakensis is the source of the oocytes. Fertilization success is low between C. ariakensis and C. gigas. These differences probably relate chiefly to molecular mechanisms of gamete recognition, but the present study examines whether the size and certain aspects of gamete morphology may also play a role. Individuals of four species of the genus Crassostrea (Ostreidae: Bivalvia), collected from different geographic regions between 2006 and 2011, C. angulata (Penghu Island, Taiwan Strait), C. ariakensis (Nha Trang Bay, South China Sea), C. gigas (Peter the Great Bay, Sea of Japan), and C. virginica (Galveston Bay, Gulf of Mexico), were examined for conspecific relationships between the thickness of the vitelline envelope in mature oocytes and the size of the acrosome or subacrosomal spaces in spermatozoa. Thicker vitelline envelopes corresponded with bigger acrosomes and subacrosomal spaces in three of the four species. The exception was C. gigas, which has the thickest vitelline envelope, but the lytic compartments in its spermatozoa are not the largest. Moreover, sizes of acrosome, subacrosomal space, and vitelline envelope are similar between the species with symmetric heterospecific fertilization, while difference in sizes of these structures increases the possibility of asymmetric cross-fertilization or decreased fertilization rate.

ACS Style

Olga V. Yurchenko; Alexander V. Kalachev. Is gamete morphology involved in hybridization in oysters? Marine Biology 2016, 163, 1 -11.

AMA Style

Olga V. Yurchenko, Alexander V. Kalachev. Is gamete morphology involved in hybridization in oysters? Marine Biology. 2016; 163 (2):1-11.

Chicago/Turabian Style

Olga V. Yurchenko; Alexander V. Kalachev. 2016. "Is gamete morphology involved in hybridization in oysters?" Marine Biology 163, no. 2: 1-11.

Journal article
Published: 01 January 2015 in Micron
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Permeability of testes in sea urchins, Strongylocentrotus intermedius, was investigated by using an electron-opaque tracer, lanthanum nitrate. This tracer is able to enter the basal compartment of germinative epithelium, where developing germ cells are located. However, its ability to penetrate the gonadal lumen was reduced. An incomplete permeability barrier between the basal compartment and the gonadal lumen is supposed to exist in testes of S. intermedius.

ACS Style

Alexander V. Kalachev. An ultrastructural study of testes permeability in sea urchins, Strongylocentrotus intermedius. Micron 2015, 68, 66 -69.

AMA Style

Alexander V. Kalachev. An ultrastructural study of testes permeability in sea urchins, Strongylocentrotus intermedius. Micron. 2015; 68 ():66-69.

Chicago/Turabian Style

Alexander V. Kalachev. 2015. "An ultrastructural study of testes permeability in sea urchins, Strongylocentrotus intermedius." Micron 68, no. : 66-69.

Journal article
Published: 01 December 2014 in Tissue and Cell
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Ultrastructural study of gonadal muscles in sea star, Asterina pectinifera, showed that myoepithelial cells were located only in the epithelial lining of the genital coelomic sinus. No myoepithelial cells were found in the visceral peritoneal epithelium or within connective tissue layer of the outer sac. Morphology of the myoepithelial cells in gonads of A. pectinifera varies during the reproductive cycle. During the gametogenic phase of the reproductive cycle, the myoepithelial cells get an elongated, spindle-like shape having a length of 20–30 m. In prespawning gonads, many of the myoepithelial cells form cytoplasmic extensions of 3–5 m in length, filled with myofilaments and penetrating into the underlying connective tissue of the outer sac or haemal sinus. Besides, myoepithelial cells, simultaneously anchored in the inner and outer sacs, were also observed. These changes result in development of more elaborated musculature and increase in contractility of the gonadal wall in prespawning gonads as compared to that during other stages of the reproductive cycle.

ACS Style

Alexander V. Kalachev. Reinvestigation of epithelial lining of the genital coelomic sinus in asteroids. An ultrastructural study. Tissue and Cell 2014, 46, 540 -545.

AMA Style

Alexander V. Kalachev. Reinvestigation of epithelial lining of the genital coelomic sinus in asteroids. An ultrastructural study. Tissue and Cell. 2014; 46 (6):540-545.

Chicago/Turabian Style

Alexander V. Kalachev. 2014. "Reinvestigation of epithelial lining of the genital coelomic sinus in asteroids. An ultrastructural study." Tissue and Cell 46, no. 6: 540-545.

Review
Published: 01 March 2013 in General and Comparative Endocrinology
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Over than fifty years starfishes have been widely used as model for studying the mechanisms of cell cycle regulation, oocyte maturation and fertilization. Besides, significant work has been done to investigate the role of nervous system in the control of reproduction and spawning in these animals. Nowadays, sea stars represent one of the most thoroughly studied model for hormonal regulation of reproduction among invertebrates. However, while the general picture of neuroendocrine control of asteroid reproduction can be drawn easily, our knowledge concerning the details of this process still has some gaps. Filling these gaps is essential for studying the diversity of hormonal mechanisms involved in regulation of animal reproduction. The present paper aims to briefly summarize current data on hormonal regulation of reproduction in sea stars and to highlight existing gaps in our knowledge on the details of this process.

ACS Style

Alexander V. Kalachev. A brief summary of neuroendocrine regulation of reproduction in sea stars. General and Comparative Endocrinology 2013, 183, 79 -82.

AMA Style

Alexander V. Kalachev. A brief summary of neuroendocrine regulation of reproduction in sea stars. General and Comparative Endocrinology. 2013; 183 ():79-82.

Chicago/Turabian Style

Alexander V. Kalachev. 2013. "A brief summary of neuroendocrine regulation of reproduction in sea stars." General and Comparative Endocrinology 183, no. : 79-82.

Journal article
Published: 19 August 2010 in Synapse
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The biplexiform cell (bpxRGC) is a relatively and recently discovered type of retinal ganglion cells. Like "ordinary" ganglion cells, bpxRGCs have dendrites arborizing within the inner plexiform layer. However, as distinct from other ganglion cells, they have dendrites ascending to the outer plexiform layer. To date, bpxRGCs have been found in mammals, amphibians, and teleost fishes (Cook et al. [1996] Vis Neurosci 13:517-528). The mammalian and amphibian bpxRGCs form direct contacts with photoreceptors and may participate in rapid signal transmission to the brain (Mariani [1982] Science 216:1134-1136; Straznicky and Gábriel [1995] J Hirnforsch 36:135-141). The synaptic organization of teleost bpxRGCs has not been studied. We have studied the synaptic structure of bpxRGCs in the teleost fish Hexagrammos octogrammus. In the sclerad part of the outer plexiform layer, bpxRGC dendrites occurred among the elements in invaginated ribbon synapses (triads) in cone pedicles and rod spherules. Earlier, we showed that greenling bpxRGCs project to the optic tectum (Podugolnikova et al. [2002] Sensornye systemy 15:44-53). We suggest that greenling bpxRGCs participate in some of the tectum-mediated reactions requiring a quick launch of visuomotor reflexes.

ACS Style

Igor Pushchin; Alexander Kalachev. Biplexiform ganglion cells contact photoreceptors in the retina of the greenling Hexagrammos octogrammus. Synapse 2010, 64, 937 -940.

AMA Style

Igor Pushchin, Alexander Kalachev. Biplexiform ganglion cells contact photoreceptors in the retina of the greenling Hexagrammos octogrammus. Synapse. 2010; 64 (12):937-940.

Chicago/Turabian Style

Igor Pushchin; Alexander Kalachev. 2010. "Biplexiform ganglion cells contact photoreceptors in the retina of the greenling Hexagrammos octogrammus." Synapse 64, no. 12: 937-940.

Original articles
Published: 01 January 2007 in Invertebrate Reproduction & Development
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The somatic accessory cells in the testes of the sea cucumber, Chiridota pellucida (Holothuroidea: Apoda), are flattened flagellated epithelial cells covering the basal lamina of the germinal epithelium. Their nucleus is irregular or elongated with a prominent nucleolus. The cytoplasm contains the Golgi complex, cisternae of rough and smooth endoplasmic reticulum, numerous electron-lucent vesicles, and lipid droplets. C. pellucida accessory cells differ in ultrastructure from those in other holothurians.

ACS Style

Alexander V. Kalachev; Arkadiy A. Reunov. An ultrastructural study of accessory cells in the testes of the sea cucumberChiridota pellucida(Holothuroidea: Apoda). Invertebrate Reproduction & Development 2007, 50, 103 -107.

AMA Style

Alexander V. Kalachev, Arkadiy A. Reunov. An ultrastructural study of accessory cells in the testes of the sea cucumberChiridota pellucida(Holothuroidea: Apoda). Invertebrate Reproduction & Development. 2007; 50 (2):103-107.

Chicago/Turabian Style

Alexander V. Kalachev; Arkadiy A. Reunov. 2007. "An ultrastructural study of accessory cells in the testes of the sea cucumberChiridota pellucida(Holothuroidea: Apoda)." Invertebrate Reproduction & Development 50, no. 2: 103-107.

Biology of ontogenesis
Published: 01 September 2005 in Russian Journal of Marine Biology
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The ultrastructural mechanism of postspawning sperm resorption in the testes of the sea urchin Strongylocentrotus nudus is described. Two types of phagosomes (containing sperm and containing residual bodies) are formed in the cytoplasm of nutritive phagocytes. The phagosomes fuse with electron-dense globules, and their contents are gradually destroyed. Afterward, phagosomes are transformed into electron-transparent vacuoles, which are finally compressed by the surrounding cytoplasm.

ACS Style

A. V. Kalachev; O. V. Yurchenko; A. A. Reunov. Phagocytic Activity of Accessory Cells in the Gonad of the Sea Urchin Strongylocentrotus nudus. Russian Journal of Marine Biology 2005, 31, 318 -321.

AMA Style

A. V. Kalachev, O. V. Yurchenko, A. A. Reunov. Phagocytic Activity of Accessory Cells in the Gonad of the Sea Urchin Strongylocentrotus nudus. Russian Journal of Marine Biology. 2005; 31 (5):318-321.

Chicago/Turabian Style

A. V. Kalachev; O. V. Yurchenko; A. A. Reunov. 2005. "Phagocytic Activity of Accessory Cells in the Gonad of the Sea Urchin Strongylocentrotus nudus." Russian Journal of Marine Biology 31, no. 5: 318-321.

Biology of ontogenesis
Published: 01 March 2005 in Russian Journal of Marine Biology
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The process of resorption of spermatozoa is described in the testes of the starfish Asterina pectinifera. It is shown that the mode of resorption of the male gametes in this species is different from that in the starfish Asterias vulgaris (see Walker [17, 18]), A. amurensis, and Aphelasterias japonica (see Kas’yanov et al.

ACS Style

Alexander Kalachev; A. A. Reunov. Resorption of Gametes in the Testes of the Sea Star Asterina pectinifera (Mueller et Troschel, 1842). Russian Journal of Marine Biology 2005, 31, 119 -123.

AMA Style

Alexander Kalachev, A. A. Reunov. Resorption of Gametes in the Testes of the Sea Star Asterina pectinifera (Mueller et Troschel, 1842). Russian Journal of Marine Biology. 2005; 31 (2):119-123.

Chicago/Turabian Style

Alexander Kalachev; A. A. Reunov. 2005. "Resorption of Gametes in the Testes of the Sea Star Asterina pectinifera (Mueller et Troschel, 1842)." Russian Journal of Marine Biology 31, no. 2: 119-123.