The oxytocic activity of the neurointermediate lobe of the pituitary of the elasraobranch, Squalus acanthias (Pacific variety), was studied with chromatographic and pharmacological techniques, in an effort to determine whether the activity was due to a single or to a number of similar neurohypophysial principles. Neurointermediate lobes (NIL's) were dissected from live specimens of Squalus acanthias caught on the Pacific coast of Canada during 1966-67. The tissues were acetone dried and extracted in 0.25% acetic acid in saline. The extracts were assayed on the isolated rat uterus for their oxytocic activity, both in the presence and absence of magnesium ions, and in one case for rabbit milk ejection activity and antidiuretic activity in the anaesthetized rat. The ratio of milk ejection:rat uterus: rat antidiuretic activity was 2.6:1:0.046 which was in excellent agreement with the observations of previous investigators. However, this ratio contrasts with the 1:1:1 ratio of International standard ox posterior pituitary powder and indicates the presence of an elasmobranch oxytocic principle or principles similar to but not identical with oxytocin. This result was confirmed by the potentiation of the elasmobranch oxytocic activity in the presence of magnesium ions, a property typical of oxytocin analogues but not of oxytocin itself. The elasmobranch extracts showed a 1.2 – 3.2 fold range of magnesium potentiations and agreed with the values published by Sawyer (1965b). However, no extract in the 16 samples assayed showed sufficient potentiation to indicate the presence of significant amounts of a highly potentiated peptide (6 - 10 fold potentiation) such as postulated by Heller and Roy (1964) or Acher, Chauvet, Chauvet and Crepy (1965). Paper chromatography of the oxytocic activity using butanol/ acetic acid (glacial)/water (4:1:5) solvent system, was extended from the low oxytocic activity load levels utilized by Perks (i960) to loads beyond those used by Heller and Roy (196k) in which they detected two separable oxytocic activity peaks. Paper chromatography of our crude extracts at loads of 30 - 500 milli-units (without Mg⁺⁺), showed only one chromatographic peak, with an Rf approximating 0.4 - 0.5, which ran slightly slower than synthetic oxytocin Rf 0.5 - 0.6. No magnesium potentiation greater than a 3-fold potentiation could be detected in any regions of these chromatograms. Crude extracts ranging from 1148 to 7356 milliunits oxytocic activity were partially purified by the mild procedure of gel filtration on Sephadex G-15 in order that higher loads of oxytocic activity could be chrornatogrammed without artifacts due to overloading with protein. Despite the chromatography of levels of oxytocic activity higher than any previously.reported, the oxytocic activity never resolved into more than one chromatographic peak, and no region of the chromatograms potentiated beyond 3.4 when assayed with magnesium. The study of 16 different extracts from the neurointermediate lobes of Squalus acanthias (Pacific variety) gave no evidence for any large content of an oxytocic neurohypophysial principle potentiated 6-10 fold by magnesium ions. The use of paper chromatography techniques identical to those used by Heller and Roy (1964) failed to resolve more than one oxytocic principle, despite the use of oxytocic activity loads beyond those used by these authors. It is concluded that in the case of certain extracts of the oxytocic moiety of the Squalus acanthias (Pacific variety) neurointermediate lobe, there is no evidence for the presence of more than one oxytocic neurohypophysial principle. / Science, Faculty of / Zoology, Department of / Graduate

1) Using the corrosion casting technique, which utilises a fast polymerising monomer resin, the vasculature of the rectal gland in Scyliorhinm canicula was studied using light and scanning electron microscopy. Possible control sites for altering blood flow through the rectal gland were identified. 2) A viable and reliable isolated perfused preparation of the rectal gland of S. canicula was developed by optimising flow rate, time of perfusion and viability of individual preparations. The combination of dibutryl cyclic adenosine monophosphate plus the potent phosphodiesterase inhibitor Isobutyl-methyl xanthine, was used as a test of viability for individual preparations. This combination potently stimulated chloride clearance rates from the isolated perfused rectal gland. 3) The isolated perfused preparation was then used to test a variety of hormones that could be involved in the control of rectal gland activity. The hormones, vasoactive intestinal peptide and urotensin II did not stimulate chloride clearance rates from the isolated perfused gland. However, the endogenous natriuretic peptide, C-type natriuretic peptide did stimulate chloride clearance rate from the perfused rectal gland in a dose dependant manner. Endogenous glucagon also stimulated chloride clearance rate. 4) Using cannulated fish, administration of angiotensin II and C-type natriuretic peptide in vivo, produced vasopressor and vasodepressor responses respectively and C-type natriuretic peptide inhibited the vasopressor action of angiotensin II when the two peptides were administered simultaneously. Administration of angiotensin II to the isolated perfused rectal gland produced a vasoconstrictor effect, increasing perfusion pressure. C-type natriuretic peptide did not produce any significant effect. A combination of the two peptides in vitro appeared to reduce the vasoconstrictor effect of angiotensin II. In addition this hormonal combination in vitro appeared to exert a synergistic effect increasing chloride clearance rates from the isolated perfused rectal gland. 5) The lack of a VIP stimulatory effect on the isolated perfused rectal gland in the present study is in agreement with previous reports. Using protein purification techniques including, gel-permeation, and reverse-phase high performance liquid chromatography an endogenous gut peptide was obtained that stimulated rectal gland activity in 5. canicula. This peptide was subsequently characterised as scyliorhinin II and it is proposed that the previously identified rectin and scyliorhinin II are the same peptide.

O gênero Squalus Linnaeus, 1758 (Elasmobranchii: Squaliformes) compreende um grupo cosmopolita de tubarões com alta complexidade taxonômica devido à dificuldade de distinção morfológica entre os representantes, exigindo revisão. Atualmente, há cerca de 24 espécies listadas como válidas que estão divididas em três complexos de espécies de acordo com a similaridade morfológica entre elas: grupos S. acanthias, S. megalops e S. mitsukurii. A perda do holótipo de espécies nominais, identificações equivocadas na literatura e dificuldade de obtenção de séries representativas consistem em empecilhos secundários que interferem na realização de uma revisão mundial do gênero. Esta problemática também serve para as espécies distribuídas ao longo do oceano Atlântico Sul Ocidental, incluindo as espécies brasileiras, pois estas carecem de uma caracterização morfológica precisa. Desta maneira, acompanhando uma tendência mundial contemporânea, uma revisão taxonômica regional do gênero Squalus foi desenvolvida com o intuito de investigar quais são as espécies válidas para o oceano Atlântico Sul Ocidental bem como elucidar quais caracteres diagnósticos são eficientes para a separação de espécies. O estudo ora proposto analisou detalhadamente a morfologia externa e interna (esquelética) de grandes séries representativas de espécimes de Squalus e validou quatro espécies nominais disponíveis para o oceano Atlântico Sul Ocidental, entre elas, Squalus acanthias, S. blainvillei, S. megalops e S. cubensis, incluindo também a caracterização de Squalus sp. Aspectos da morfometria externa, dentição, padrão de coloração, dados merísticos relevantes e caracteres do esqueleto dos espécimes analisados foram ilustrados e comparados, posteriormente, com exemplares de outras regiões geográficas. / The genus Squalus Linnaeus, 1758 (Elasmobranchii: Squalidae) comprises a group of cosmopolitan sharks species with a high taxonomic complexity due to difficulties in morphologically differentiating its component species, many of which must be taxonomically reviewed. Currently, there are 24 valid species of Squalus which have been divided into three species-complexes according to morphological similarity: the S. acanthias group, the S. megalops group, and the S. mitsukurii group. Loss of type-specimens of nominal species, the propagation of erroneous identifications in the literature, and difficulties in obtaining representative series for comparison are secondary challenges that impede a global taxonomical revision of Squalus. This problem applies very clearly to species from the Southwestern Atlantic Ocean as well, including species that occur off Brazil, mostly because of a complete lack of detailed morphological revisions. Following a current global tendency, a regional taxonomic review of Squalus was conducted in order to investigate which species are valid in the Southwestern Atlantic Ocean as well elucidate which diagnostic morphological characters can be efficiently used to separate species. The present proposal aimed to conduct a taxonomic review of the genus Squalus from the Southwestern Atlantic Ocean through a comparative and detailed analysis of external and skeletal morphology from representative series of specimens of Squalus from the region. The results obtained validate four available nominal species, Squalus acanthias, S. blainvillei, S. megalops, S. cubensis, and also includes characterization of Squalus sp. The results are based on aspects of external morphometry, dentition, color pattern, meristic data, and characters from the skeleton (primarily neurocrania) which were illustrated and compared with specimens of Squalus from other geographic regions.

O gênero Squalus Linnaeus, 1758 (Elasmobranchii: Squaliformes) compreende um grupo cosmopolita de tubarões com alta complexidade taxonômica devido à dificuldade de distinção morfológica entre os representantes, exigindo revisão. Atualmente, há cerca de 24 espécies listadas como válidas que estão divididas em três complexos de espécies de acordo com a similaridade morfológica entre elas: grupos S. acanthias, S. megalops e S. mitsukurii. A perda do holótipo de espécies nominais, identificações equivocadas na literatura e dificuldade de obtenção de séries representativas consistem em empecilhos secundários que interferem na realização de uma revisão mundial do gênero. Esta problemática também serve para as espécies distribuídas ao longo do oceano Atlântico Sul Ocidental, incluindo as espécies brasileiras, pois estas carecem de uma caracterização morfológica precisa. Desta maneira, acompanhando uma tendência mundial contemporânea, uma revisão taxonômica regional do gênero Squalus foi desenvolvida com o intuito de investigar quais são as espécies válidas para o oceano Atlântico Sul Ocidental bem como elucidar quais caracteres diagnósticos são eficientes para a separação de espécies. O estudo ora proposto analisou detalhadamente a morfologia externa e interna (esquelética) de grandes séries representativas de espécimes de Squalus e validou quatro espécies nominais disponíveis para o oceano Atlântico Sul Ocidental, entre elas, Squalus acanthias, S. blainvillei, S. megalops e S. cubensis, incluindo também a caracterização de Squalus sp. Aspectos da morfometria externa, dentição, padrão de coloração, dados merísticos relevantes e caracteres do esqueleto dos espécimes analisados foram ilustrados e comparados, posteriormente, com exemplares de outras regiões geográficas. / The genus Squalus Linnaeus, 1758 (Elasmobranchii: Squalidae) comprises a group of cosmopolitan sharks species with a high taxonomic complexity due to difficulties in morphologically differentiating its component species, many of which must be taxonomically reviewed. Currently, there are 24 valid species of Squalus which have been divided into three species-complexes according to morphological similarity: the S. acanthias group, the S. megalops group, and the S. mitsukurii group. Loss of type-specimens of nominal species, the propagation of erroneous identifications in the literature, and difficulties in obtaining representative series for comparison are secondary challenges that impede a global taxonomical revision of Squalus. This problem applies very clearly to species from the Southwestern Atlantic Ocean as well, including species that occur off Brazil, mostly because of a complete lack of detailed morphological revisions. Following a current global tendency, a regional taxonomic review of Squalus was conducted in order to investigate which species are valid in the Southwestern Atlantic Ocean as well elucidate which diagnostic morphological characters can be efficiently used to separate species. The present proposal aimed to conduct a taxonomic review of the genus Squalus from the Southwestern Atlantic Ocean through a comparative and detailed analysis of external and skeletal morphology from representative series of specimens of Squalus from the region. The results obtained validate four available nominal species, Squalus acanthias, S. blainvillei, S. megalops, S. cubensis, and also includes characterization of Squalus sp. The results are based on aspects of external morphometry, dentition, color pattern, meristic data, and characters from the skeleton (primarily neurocrania) which were illustrated and compared with specimens of Squalus from other geographic regions.

Squalidae compreende dois gêneros de tubarões, Squalus e Cirrhigaleus cujas espécies apresentam taxonomia complexa devido à dificuldade de distinção morfológica entre elas, associado a uma incerteza à aplicação de várias espécies nominais. A revisão taxonômica e morfológica dos representantes da família foi conduzida para delimitar globalmente as espécies válidas e fornecer caracteres diagnósticos eficientes através de análises detalhada da morfologia externa e esquelética. Foram reconhecidas 30 espécies válidas para a família, classificadas em dois gêneros. Squalus compreende um gênero menor com três espécies de tubarões com manchas brancas no corpo. Um segundo gênero, separado de Squalus, é reconhecido para abrigar 27 espécies de tubarões sem manchas. Assim, a hipótese de subdivisão do gênero Squalus em “grupos/complexos de espécies” (grupos S. acanthias, S. mitsukurii e S. megalops) foi refutada. Sete espécies novas são descritas para os Oceanos Atlântico Sul e Índico Ocidental, e duas espécies nominais são ressuscitadas como válidas. Cinco espécies são propostas como novos sinônimos de outras espécies dentro deste contexto. Cirrhigaleus é um gênero válido e menos diverso, incluindo três espécies com barbilhão nasal. A alocação genérica da espécie nominal “asper”, antes em constantes discussões na literatura, é finalmente esclarecida para Cirrhigaleus. A classificação taxonômica de Cirrhigaleus dentro de Squalidae, contudo, é questionada e uma nova família para Squaliformes é proposta para abrigar este gênero. Características do esqueleto em Squalidae exibem complexidade e variação maior do que antes descrito. Caracteres esqueléticos são também apresentados para serem integrados em análise filogenética futura / Squalidae comprises two genera of sharks, Cirrhigaleus Squalus, whose species have complex taxonomy due to difficulty of morphological distinction between them, associated to an uncertainty to the application of its available nominal species. A taxonomic and morphological revision of the family was conducted in order to globally delimitate the valid species and provide efficient diagnostic characters through detailed analyses of external and skeletal morphology. Squalus is herein recognized as a smaller group, which comprises three species of spotted-dogfish. A second genus is raised as separated from Squalus with 27 species of non-spotted dogsharks. Thus, the hypothesis of subdivision of Squalus into three groups/complexes of species (S. acanthias, S. mitsukurii and S. megalops groups) is refuted. Seven new species are described for the South Atlantic and West Indian Oceans, and two nominal species are resurrected as valid for the family. Five species are proposed as new synonyms from other species within this context. Cirrhigaleus is a valid and less diverse genus, comprising three species of barbel-bearing dogfish. Generic allocation of the nominal species “asper”, beforehand under constant discussions on literature, is elucidated for Cirrhigaleus. However, taxonomic classification of Cirrhigaleus within Squalidae is questioned and a new family for Squaliformes is proposed to incorporate the genus. Characteristics of the skeleton in Squalidae reveal to be more complex than previously thought. Morphological characters are also provided for integrating future phylogenetic analysis