SYNTHESIS OF NUCLEIC ACIDS AND LOCALIZATION OF ATRIAL NATRIURETIC PEPTIDE IN THE CRAYFISH HAEMOCYTES
M. G. Martynova, O. A. Bystrova, V. N. Parfenov
Institute Cytology RAS, St. Petersburg;
e-mail: heartdev@mail.cytspb.rssi.ru
IThree types of cells circulate in haemolymph of the crayfish Astacus astacus: agranular haemocytes (HCs I), small-granule haemocytes (HCs II) and
large-granule haemocytes (HCs III). Their proliferation, differentiation and function remain poorly understood. By means of light and electron microscopic
autoradiography using [3H]-thymidine, we have revealed that only HCs I are capable of DNA synthesis and mitosis whereas HCs II and HCs III are
replicatively inactive. To determine whether the HCs I are proliferating progenitor cells for the granular HCs, we have analyzed autographs of HC population in 1, 2, 7
and 21 days after a single [3H]-thymidine administration. Contrary to the expectation, we have failed to find labeled HCs II and HCs III. These findings
raise doubts on the capacity of the HCs I to differentiate into two other types of HCs. By autoradiography using 3H-uridine, it has been detected that
intensity of the RNA synthesis was the greatest in HCs I and less by a factor of two and four in HCs II and HCs III, respectively. Additionally, by EM
immunocytochemistry, ANP-like immunoreactivity was revealed in the large granules of the HCs III. We assume that availability of ANP in secretory granules
extends the possible functions of the crayfish HCs and suggests their participation in regulation of water-salt balance and immune responses.
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