Cytological Studies of Artemia salina. II

Nakanishi, Yuh H.; Okigaki, Tohru; Kato, Hatao; Iwasaki, Tamiko

doi:10.2183/pjab1945.39.306

Cited by 16 publications

(10 citation statements)

References 4 publications

(2 reference statements)

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“…Five representative stages were analyzed, namely (i) postdiapause, (ii) before emergence (10-hour-incubated), (iii) after emergence (14-h-incubated), (iv) newly hatched nauplius, and (v) postlarval stage. Due to the ubiquitous heteroploidies and aneuploidies in Artemia (14,26), two parameters, the Geo Mean of DNA content with total events and the ratio of M2 events/M1 events (here M2 was defined as a G 2 /M region and M1 as a G 0 /G 1 region), were used for the analysis. The results (Fig.…”

Section: Association Between Rsk Activation and Termination Of Cell Cmentioning

confidence: 99%

“…As a strategy to cope with such environmental stresses, Artemia has evolved a special reproductive mode in that in addition to giving birth to nauplii by the ovoviviparous pathway, this genus also releases encysted embryos by the oviparous pathway (10). Released encysted embryos are developmentally arrested at the gastrula stage with a low metabolic rate and complete turnoff of replication, transcription, and translation; however, without loss of embryonic viability (11,12).Another interesting phenomenon in the development of Artemia-encysted embryos is that no cell division or DNA synthesis occurs before emergence (13,14). In the emergence process, the prenauplius starts to push out of the cyst shell, and finally, it develops into a true swimming nauplius.…”

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confidence: 99%

“…Another interesting phenomenon in the development of Artemia-encysted embryos is that no cell division or DNA synthesis occurs before emergence (13,14). In the emergence process, the prenauplius starts to push out of the cyst shell, and finally, it develops into a true swimming nauplius.…”

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Involvement of p90 Ribosomal S6 Kinase in Termination of Cell Cycle Arrest during Development of Artemia-encysted Embryos

Dai

Zhu

Liu

et al. 2008

Journal of Biological Chemistry

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Artemia has evolved a unique developmental pattern of encysted embryos to cope with various environmental threats. Cell divisions totally cease during the preemergence developmental stage from gastrula to prenauplius. The molecular mechanism of this, however, remains unknown. Our study focuses on the involvement of p90 ribosomal S6 kinase (RSK), a family of serine/threonine kinase-mediating signal transduction downstream of mitogen-activated protein kinase cascades, in the termination of cell cycle arrest during the post-embryonic development of Artemia-encysted gastrula. With immunochemistry, morphology, and cell cycle analysis, the identified Artemia RSK was established to be specifically activated during the post-embryonic and early larval developmental stages when arrested cells of encysted embryos resumed mitoses. In vivo knockdown of RSK activity by RNA interference, kinase inhibition, and antibody neutralization consistently induced defective larvae with distinct gaps between the exoskeleton and internal tissues. In these abnormal individuals, mitoses were detected to be largely inhibited in the affected regions. These results display the requirement of RSK activity during Artemia development and suggest its role in termination of cell cycle (G 2 /M phase) arrest and promotion of mitogenesis. Our findings may, thus, provide insights into the regulation of cell division during Artemia post-embryonic development and reveal further aspects of RSK functions. p90 ribosomal S6 kinase (p90 RSK , also known as RSK) is a family of serine/threonine kinase that mediates signal transduction downstream of mitogen-activated protein kinase cascades (1). RSKs 2 consist of two distinct and functional kinase domains, the N-terminal kinase domain and the C-terminal kinase domain connected by a regulatory linker (2). The typical RSK possesses six phosphorylation sites, and its in vivo activation is achieved upon their consecutive phosphorylations. Mutation analysis reveals four of the six sites are essential for the kinase activation (Ser-221 in N-terminal kinase domain, Ser-363 and Ser-380 in the linker, and Thr-573 in C-terminal kinase domain, according to the human RSK1 sequence) (3).RSKs are present in most vertebrate species (1, 4), and RSKrelated molecules have also been identified in several invertebrates (5, 6). RSK family members have been reported to be multifunctional in the regulation of diverse cellular processes including transcriptional regulation, cell cycle control, cell survival, and many others (4). Within mammalian cells, RSKs are thought to promote G 1 progression by stimulating growth-related protein synthesis and inhibiting negative regulation (7). It is, thus, shown that the RSK inhibitor SL0101 can effectively inhibit proliferations of the human breast cancer cell and the hamster ovary cell (8, 9).Artemia possesses powerful adaptations to extreme environments that often include aspects of hypersalinity, anoxia, and large changes in ionic composition and temperature. As a strategy to cope with such en...

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Section: Association Between Rsk Activation and Termination Of Cell Cmentioning

confidence: 99%

mentioning

confidence: 99%

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Involvement of p90 Ribosomal S6 Kinase in Termination of Cell Cycle Arrest during Development of Artemia-encysted Embryos

Dai

Zhu

Liu

et al. 2008

Journal of Biological Chemistry

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“…Artemia nauplia have two types of cells: cells with large nuclei (6-8 µm) and cells with small nuclei (4 µm). The cells with small nuclei are diploid [16]. We analyzed cells with small nuclei in the first three layers near the anal end of the nauplius larvae ( Figure 1).…”

Section: Determination Of Chromatin Condensation Statementioning

confidence: 99%

Electromagnetic field effects on Artemia hatching and chromatin state

et al. 2010

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, exposure time-10s.Afterincubationofthecystsfor48hoursinseawaterthehatchingpercentageofArtemiafromexposedcystswas higherthanincontrols.Thenumberofheterochromatingranuleswassignificantlyhigherinthenauplia(newbornlarvaeofArtemia) developedfromcyststhathadbeenexposedtomagneticand electromagneticfields.Thedataobtaineddemonstratean increase in percentage hatching of Artemia cysts after treatment with magnetic and electromagnetic fields and chromatin condensation in nauplia. We have also shown different effects of right-handed and left-handed rotating magnetic fields on these processes.

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“…In this period, it has been reported that no DNA synthesis (Nakanishi et al, 1962), no extensive RNA synthesis (McClean & Warner, 1971), except ofsome low-molecular-weight species (Susheela &Jayaraman, 1976), and no prominent protein synthesis in vitro on polyribosomal templates occur, but that a significant cell differentiation takes place in these embryos (Benesch, 1969).…”

Section: Experimental (A) Growth and Handling Ofartemia Embryosmentioning

confidence: 99%

Selective resistance to desiccation of nuclear ribonucleic acid synthesis in isolated nuclei of Artemia salina embryos during pre-emergence development

Kondo

1976

Biochemical Journal

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The developing gastrula embryos of Artemia salina are resistant to a complete redesiccation during a period of pro-emergence development. Isolated nuclei from these dehydrated embryos could retain a transcriptional activity in vitro comparable with that of non-desiccated controls. On the other hand, redesiccation of both prenauplii and nauplii completely destroys their viability as well as the nuclear transcriptional activity. However, those gastrula embryos that did not develop in a first incubation period could remain viable and develop with a considerable time-lag after a subsequent second incubation.

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Cytological Studies of Artemia salina. II

Cited by 16 publications

References 4 publications

Involvement of p90 Ribosomal S6 Kinase in Termination of Cell Cycle Arrest during Development of Artemia-encysted Embryos

Involvement of p90 Ribosomal S6 Kinase in Termination of Cell Cycle Arrest during Development of Artemia-encysted Embryos

Electromagnetic field effects on Artemia hatching and chromatin state

Selective resistance to desiccation of nuclear ribonucleic acid synthesis in isolated nuclei of Artemia salina embryos during pre-emergence development

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