In most amoeboid cells, the main protein involved in motility is actin. Nematode sperm are an exception, and their amoeboid motility is based on major sperm protein (MSP). We have studied the localization of actin and MSP in spermatids and spermatozoa of Graphidium strigosum (Dujardin, 1845), a species which has elongate male germ cells in which organelles are easily identified. Electrophoreses of G. slrigosum sperm proteins indicate that the main protein band, about 15 kDa in molecular weight, is specifically recognized by an anti-MSP polyclonal antibody developed against MSP of Caenorhabditis elegans (Burke and Ward 1983). Actin is present in small quantities. Immunocytochemical observations reveal that actin and MSP have an identical localization in precise areas of the male germ cells. Spermatids are labelled as dots around a central unlabelled zone, and spermatozoa are labelled only at the level of the anterior cap. Observations in G. strigosum are similar to that previously obtained in Heligmosomoides polygyrus (Mansir and Justine 1996). Co-localization of actin and MSP in the anterior cap of the spermatozoon, the region associated with pseudopod production, does not demonstrate directly that actin is involved in amoeboid movements, but shows that the role of actin in the cytoskeleton of nematode sperm should be re-investigated.
Threshold intensities for epileptic phenomena induced by cortical stimulation were used for comparison of the action of GABA-B and GABA-A antagonists in rats with implanted electrodes. Both CGP 35348 (200 mg/kg i.p.) and bicuculline (4 mg/kg i.p.) significantly decreased thresholds for spike-and-wave afterdischarges and their motor counterpart (clonic seizures) whilst transition into the second, limbic type of afterdischarge as well as threshold for movements directly bound to stimulation remained uninfluenced by either drug., D. Živanović, K. Bernášková, Yu. Kaminskij, P. Mareš., and Obsahuje bibliografii
Dopamine (DA) is known as a primary regulator of prolactin secretion (PRL) and angiotensin II (Ang II) has been recognized as one brain inhibitory factor of this secretion. In this work, estrogen-primed or unprimed ovariectomized rats were submitted to the microinjection of saline or Ang II after previous microinjection of saline or of DA antagonist (haloperidol, sulpiride or SCH) both in the medial preoptic area (MPOA). Our study of these interactions has shown that 1) estrogen-induced PRL secretion is mediated by Ang II and DA actions in the MPOA, i.e. very high plasma PRL would be prevented by inhibitory action of Ang II, while very low levels would be prevented in part by stimulatory action of DA through D2 receptors, 2) the inhibitory action of Ang II depends on estrogen and is mediated in part by inhibitory action of DA through D1 receptors and in other part by inhibition of stimulatory action of DA through D2 receptors., C. M. Leite, G. J. R. Machado, R. C. M. Dornelles, C. R. Franci., and Obsahuje bibliografii a bibliografické poznámky