Histochemical survey of transmitters in the central ganglia of the gastropod mollusc Phestilla sibogae

Several investigators of the molluscan nervous system have used TEA, injected into presynptic neurones, to determine whether the connexions made by these neurones are monosynaptic. The increase in spike duration produced by the TEA causes an increase in transmitter release, and hence an increase in the amplitude of the postsynaptic potential if the connexion is direct. If the connexion is indirect, the spike in an intercalated neurone will not be affected by the TEA, and the postsynaptic response will remain constant. Experiments described here show that TEA can cross electrotonic junctions in the gastropod mollusc Planorbis corneus. They also show that each TEA-prolonged presynaptic impulse may produce more than one postsynaptic impulse. A larger postsynaptic potential could therefore be produced by presynaptic injection of TEA in the case of an indirect connexion. This indicates that care must be taken when interpreting the results of experiments using TEA to test for monosynaptic connexions.

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VARIABILITY OF SHELL IN GASTROPODS OF THE GENUS BORYSTHENIA LINDHOLM, 1914: TESTING THE STATISTICAL APPROACH IN SEARCH OF TRAITS FOR THE RECENT AND FOSSIL SPECIES DELIMITATION

Collection of Scientific Works of the Institute of Geological Sciences of the NAS of Ukraine ◽

10.30836/igs.2522-9753.2021.227603 ◽

2021 ◽

Vol 14 (1) ◽

pp. 110-116

Author(s):

Olga Yu. Anistratenko ◽

Diana S. Osipova ◽

Vitaliy V. Anistratenko

Keyword(s):

North Africa ◽

Species Delimitation ◽

Statistical Approach ◽

Statistical Processing ◽

Taxonomic Status ◽

Shell Morphology ◽

Close Relative ◽

Fossil Species ◽

Gastropod Mollusc ◽

Fossil Records

The gastropod mollusc genus Borysthenia Lindholm, 1914 comprises many species throughout Europe, Asia, North Africa and North America but species delimitation, based mainly on shell morphology (only possible concerning the fossil records) is often disputable. Statistical methods used to test if the shell measurements are reliable traits in delimitation of recent and fossil species in gastropod molluscs of the genus Borysthenia. Our analyses based on quantitative study of over 100 specimens of the Borysthenia species both modern and fossil. It is concluded that the dimensional characteristics of their shell are suitable for the differentiation of both recent and fossil (at least of Pontian age) species through the statistical processing of quantitative data. Through the morphological study of type material, taxonomic status of B. jalpuchense Gozhik, 2002 and B. vinogradovkaense Gozhik, 2002 described from the middle-pontian deposits of Ukraine revised. It is suggested that these taxa are considered two distinct though close relative extinct species. Stratigraphic range of B. jalpuchense is expanded up to the Lower Pontian. All the modern individuals of Borysthenia involved are attributed to B. menkeana (Jelski, 1863) due to their exact correspondence to the lectotype of this species.

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