Sexual dimorphism in contraction properties and fibre of the flexor carpi radialis muscle of the frog (Rana temporaria L.)

Zusammenfassung Es wird ein Sexualdimorphismus beim Daumenbeugemuskel (m. flexor carpi radialis) des Frosches (Rana temporaria L.) mit Bezug auf das Kontraktionsverhalten, wie auch in histochemischer Richtung, festgestellt. Kontraktions- und Relaxationszeit sind bei männlichen Muskeln veralaugsamt mit entsprechender ATPase-Aktivität. Saionbedingte, geschlechtstypische Testosteronkonzentrationen stehen damit im Zusammenhang.     

A study of excitation-contraction coupling in frog tonic muscle fibers ofRana temporaria

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Tonofilament aggregations in ultimobranchial gland cells of Rana temporaria L.

Résumé Observations ultrastructurales sur les corps ultimobranchiaux des grenouilles adultes (Rana temporaria) au printemps ont montré des accumulations de microfibrilles cytoplasmiques.     

Topography of the tecto-tectal component of the main ipsilateral visual pathway of the frog (Rana esculenta L.)]

The detailed topography of the tecto-tectal component of the Frog's ipsilateral visual pathway is electrophysiologically obtained by mapping the optic lobes. This linkage transfers the visual information explored along a transversal tectal row on to an homologous line oriented at 130 degrees on the opposite tectum. The ipsilateral projection of the temporo-nasal axis of the retina, but not of the antero-posterior axis of the visual field, is reversed compared to its contralateral projection. Finally, the majority of the homologous tectal points are asymmetrical with respect to the animal's sagittal axis.     

Histochemical characterization of the red fibres in pigeon pectoralis muscle

Summary Red fibres of the pigeon pectoralis muscle showed high ATPase reaction at pH 9.4. Veronal-acetate pretreatment completely inhibited the ATPase reaction in these red fibres but not in type I fibres of the gastrocnemius. The former are type II red muscle fibres and hence are unlike type I red, the so-called slow-twitch muscle fibres.     

Histochemical characterization of the red fibres in pigeon pectoralis muscle.

Red fibres of the pigeon pectoralis muscle showed high ATPase reaction at pH 9.4. Veronal-acetate pretreatment completely inhibited the ATPase reaction in these red fibres but not in type I fibres of the gastrocnemius. The former are type II red muscle fibres and hence are unlike type I red, the so-called slow-twitch muscle fibres.     

Dopamine regulation of testicular activity in intact and hypophysectomized frogs,Rana esculenta

In intact frogs, both GnRHA and L-dopa were able to increase testicular and plasma androgen levels and to induce spermiation. The dopamine antagonist pimozide inhibited both the effects of L-dopa but not those of GnRHa. Hypophysectomy reduced androgen levels, but spermiation was still induced by both GnRHa and L-dopa, suggesting that these agents can directly influence the testis through a route not involving the pars distalis. Again, pimozide antagonised spermiation induced by L-dopa but not that induced by GnRHa.This work was supported (40% and 60%) by the Italian Ministry of Education and the C.N.R. Special Project.     

Seasonal variations in the sexual activity of the male genet (Genetta genetta L.)]

The Genet testis shows a spermatogenic activity throughout the year. The plasmatic androgen level presents two periods where the values are higher; one in spring the other in autumn. The spring testosterone rise co?ncides with a mating period.     

DNA synthesis in the nuclei of differentiating muscle fibers of the silkworm,Bombyx mori L.

Summary Incorporation of³H-thymidine (³HTdr) into the nuclei of myofibril-containing myofibers of larvae of the silkworm,Bombyx mori, was shown by means of light microscope (LM) and electron-microscope (EM) autoradiography. The number of DNA-synthesizing myonuclei attains 42% 12–18 h after each molt. Thus in the developing silkworm DNA replication and myofibrillogenesis are coexisting and not mutually exclusive processes as is the rule in vertebrate somatic myogenesis.     

Speed of in vitro reassociation of gonadotropin subunits in a teleost fish, the carp (Cyprinus carpio L.)]

Purified gonadotropin subunits of a teleost Fish, the Carp, reassociated in vitro, according to a second order rate reaction. The rate constant was temperature dependent. Compared to ovine LH, the Q10 was about three times less and the rate constant much greater (160 times for instance at 20 degrees C). The possible physiological significance of these differences is underlined.     

Annual cycle of plasma testosterone and thyroxine in the European badger (Meles meles L.)]

In the male European Badger there are important variations in the plasma testosterone and thyroxine levels during the annual cycle. During the summer, plasma testosterone concentrations are low while plasma thyroxine rises to a very high level. In winter, when the thyroid activity is minimal, testicular activity increases. From February to May, the plasma testosterone remains at a high level, and then, after a sudden fall, a second peak occurs in June at which time the concentration of thyroxine is low.     

Effect of water oxygenation on oxygen consumption and gill ventilation of the crab, Carcinus maenas (L.)]

At 15 degrees C, the oxygen uptake rate of Carcinus maenas was practically independent of the ambient oxygen pressure betueen 50 and 500 Torr. Within this range, hyperventilatory and hypoventilatory responses were observed in hypoxic and hyperoxic conditions respectively whereas the oxygen extraction coefficient remained more or less constant.     

Inhibition of corticotropic function by administration of GABA in carp (Cyprinus carpio L.)]

The intracardiac injection (50 microgram/g) of GABA to Carps clearly inhibits the rise of the plasma cortisol level which occurs usually in response to the blood sampling manipulations. The inhibition starts thirty minutes after injection and lasts till the end of the experiment two hours later. The hypothesis that this neurotransmitter has a regulatory function on the corticotrop cells, especially on the excretion of ACTH has to be considered.     

Effects of injections of ecdysterone on the molt and regeneration in the crab Carcinus maenas (L.)]

Two successives injections of 10 microng/g of ecdysterone induce precocious ecdysis in 66% of Crabs. This induction of precocious ecdysis is always accompanied by an inhibiting effect on regeneration: tiny abnormal regenerates or none are obtained. A majority of recipients of ecdysterone underwent successful ecdysis. Experimental results are discussed; a morphological and cytological study of ecdysterone effects on regeneration is announced.