Testosterone changes the electric organ discharge and external morphology of the mormyrid fish, Gnathonemus petersii (Mormyriformes)

Effects of silastic and pellet methyltestosterone implants on the waveform of the electric organ discharge of the weakly electric African mormyrid, Gnathonemus petersii, were investigated. Within seven days of implantation, the duration of the discharge increased dramatically while the associated peak power frequency of the Fourier spectrum decreased in all treated fish. By day 35, hormone-treated fish exhibited up to five-fold increases in EOD duration, as well as multiple discharges and variations in the shape of the positive phase of the discharge. Testosterone treatment also changed body morphology, making immature and adult female fish resemble adult males.     

Ultrastructure and biochemistry of the pineal organ in deep-sea lanternfishes (Myctophidae)

Summary Pineal structural and biochemical adaptations in lanternfishes included: 1) few photoreceptor outer segment discs; 2) conventional synapses between photoreceptors and pineal neurons; and 3) low levels (0–60 pg/pineal) of serotonin compared to those (>1.0 ng/pineal) in the goldfish pineal organ. These findings suggest reduced photosensory and/or neuroendocrine functions in these deep-sea fishes.     

Ultrastructure and biochemistry of the pineal organ in deep-sea lanternfishes (Myctophidae)

Pineal structural and biochemical adaptations in lanternfishes included: 1) few photoreceptor outer segment discs; 2) conventional synapses between photoreceptors and pineal neurons; and 3) low levels (0-60 pg/pineal) of serotonin compared to those (greater than 1.0 ng/pineal) in the goldfish pineal organ. These findings suggest reduced photosensory and/or neuroendocrine functions in these deep-sea fishes.     

Photosensitivity of the pineal organ in the teleost,Salmo irideus (Gibbons)

Zusammenfassung Mikroelektrodenableitung der freigelegten Epiphyse der Regenbogenforelle,Salmo irideus (Gibbons), zeigt eine spontane Impulsaktivität, die bei Belichtung des Organs gehemmt wird und auch nach Entfernung der lateralen Augen bestehen bleibt. Nach Helladaptation des Pinealorgans an ein starkes Licht ist während des nachfolgenden Dunkelaufenthalts eine Empfindlichkeitszunahme um das 10⁵-fache festzustellen. Die Spektralsensitivität der Hemmung ähnelt der Absorptionskurve eines Photopigments mit Maximum bei 505 mµ.     

Synapses of the ribbon type in the pineal organ ofLacerta vivipara (reptiles,lacertilians)

Résumé Un appareil photorécepteur et neuroconducteur est hautement différencié mais quantitativement peu développé dans l'organe pinéal deLacerta vivipara adulte. L'existence de rubans synaptiques typiques, à la jonction des photorécepteurs et des cellules ganglionnaires est démontrée.

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Acknowledgment: our thanks are due to MrsS. Vernerey for her excellent technical assistance.     

Circadian rhythm in the subcommissural organ of the frog,Rana arvalis Nilsson,under natural conditions

Summary A circadian activity of SCO ependymal cells, judged by changes in the nuclear volume, has been found in juvenile frogs (Rana arvalis) under natural summer conditions. The nuclear volume reaches its maximum at 12.00 h and a minimum at 24.00 h. A significant increase in activity occurs between 06.00 and 09.00 h and a gradual decrease is observed from 12.00 to 24.00 h.     

On the structure of the natural dipeptide N-acetyl-aspartyl-glutamic acid (NAAGA)

Riassunto Si descrive la sintesi dei due dipeptidi isomeri acido N-acetil--l-aspartil-l-glutammico (I) e acido N-acetil--l-aspartil-l-glutammico (II). Il loro confronto con il NAAGA, dipeptide precedentemente isolato dal tessuto nervoso di alcuni mammiferi, ha dimostrato l'identità del nuovo metabolita con il-dipeptide (II).     

Effect of cadmium chloride on steroidogenic enzymes in the Bidder's organ of the toad (Bufo melanostictus)

Injection of cadmium chloride in a toad increases both the delta 5-3 beta-hydroxy-steroid dehydrogenase and 17 beta-hydroxysteroid dehydrogenase activities in Bidder's organ.     

Effect of cadmium chloride on steroidogenic enzymes in the Bidder's organ of the toad (Bufo melanostictus)

Summary Injection of cadmium chloride in a toad increases both the ⁵-3-hydroxy-steroid dehydrogenase and 17-hydroxysteroid dehydrogenase activities in Bidder's organ.