A study of muscle spindles in two synergistic avian muscles was undertaken to determine whether morphological or quantitative differences existed between muscle spindles residing in a slow-red (tonic) muscle and a fast-white (twitch) muscle. The avian anterior (ALD) and posterior (PLD) latissimus dorsi muscles were chosen since they are unique among vertebrates as paradigms of a slow-red and a fast-white muscle respectively. Serial frozen sections of muscle were stained with Haematoxylin and Eosin or Gomori triehrome and muscle spindles residing in the ALD were assessed and compared with those in the PLD with regard to organization, distribution and density, Contents of muscle spindles were examined for intrafusal fibre size, number and morphology. Attention was also directed to the relationship between muscle spindles and the surrounding extrafusal muscle in which they were located. Differences were found between muscle spindles residing in the two muscles. In the slow ALD, muscle spindles were relatively evenly distributed, whereas in the fast PLD, they were concentrated around the single nerve entry point into the muscle. The ALD muscle spindle index was the highest yet published for chicken muscle and was 2.3 times higher than that of its fast counterpart. A bimodal trend in intrafusal fibre diameter was noted in the ALD, and a trimodal trend was found in the PLD. The former had 42% fewer intrafusal fibres than the latter. Muscle spindles were shorter in the ALD, with an average length of 1.9mm compared with 2.3mm in the PLD. An interesting feature of the slow muscle was the monofibril muscle spindle, containing a single intrafusal fibre. With a few exceptions, ALD muscle spindles were located within the interfascicular perimysium close to a neurovascular trunk. PLD muscle spindles were rarely seen in these areas but were frequently found within a muscle fascicle, surrounded by closely apposed extrafusal fibres. Moreover, neurovascular trunks were less frequently seen in the PLD. As an adjunct to this study, three ALD-PLD pairs from the Storrs Connecticut strain of muscular dystrophic chickens were also examined to compare muscle spindles in these muscles with those of normal animals. In the PLD, which is known to exhibit early and progressive pathological change, muscle spindles appeared relatively normal until marked extrafusal fibre degeneration had occured. By this time evidence of muscle spindle involvement included capsular hypertrophy and intrafusal fibre splitting. Whereas the slow ALD has been reported to retain apparent normalcy in muscular dystrophy, subtle changes were seen in some of the muscle spindles examined. These included an increase in number of intrafusal fibres per muscle spindle compared with those in the normal. / Land and Food Systems, Faculty of / Graduate

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1. The ALD and PLD muscles from the chicken.were studied throughout ex ovo development from 3 days of age until early adulthood. These two muscles provided a model for studying phasic fast fibres and tonic slow fibres. 2. Development over the first 30 days was compared in control groups and groups immobilised in two positions, "resting" and shortened. Analysis included histochemically staining for Myosin ATPase, Phosphorylase, Succinic Dehydrogenase and histological staining for nuclei/cytoplasm and nerve endings. The ALD was shown to have 2 tonic fibre types described by both contractile and metabolic enzyme markers. The PLD was shown to have different fibre types when stained for phosphorylase activity. These types were not observed with the traditional Myosin ATPase stain. The PLD also exhibited a few, p9ssibly foetal fibres during the first two weeks of ex ovo growth. Immobilisation in both positions caused the histochemically displayed activities of these enzymes to become reduced. 3. Biochemically assays for Mg 2+-activated myofibrillar ATPase (both a alone and total activity a+ b) activity were developed for chicken muscle. These assays were used to study the changes in the ALD and PLD muscles across development and with immobilisation in both positions. Both enzymes’ activities increased during normal development with peaks in activity shown at 15 days. The PLD was shown to have 4 times the Mg2+-activated myofibrillar ATPase activity than the ALD at 51 days age. For the same age, total phosphorylase activity was 3 times higher in the PLD muscles than the ALD muscles. The higher activities 161 exhibited by the fast-phasic PLD muscle over the slow-tonic ALD muscle is in agreement with the theory that the PLD-is a faster contracting, highly anaerobic, muscle and. the ALD a slow-contracting) aerobic muscle. Immobilisation in both positions showed an initial reduction in both enzyme's activities followed by a recovery despite longer periods of immobilisation. The growth peaks exhibited by these enzymes appeared to be displaced in time when inactivity through immobilisation was imposed. 4. Chickens were thyroidectomized from 6 weeks age for 4 weeks and the ALD, PLD and ST muscles were analysed for Mg 2+ -activated myofibrillar ATPase and phosphorylase (a and a+ b) activity. Sham-operated birds acted as controls. The muscles were also stained histochemically for Myosin ATPase and phosphorylase. Thyroidectomy caused a differential effect in the PLD and ST with the ALD in terms of changes in these enzymes, activities. The PLD and ST showed a significant reduction in activity of both main enzymes (phosphorylase a activity was unchanged). The ALD however, exhibited no change in activity of the two main enzymes. In conclusion the reduced presence of thyroid hormone slows down fastphasic chicken muscles but has little effect on slow-tonic chicken muscles. 5. A study was made on. the pCa-tension relationship for skinned single fibres from the ALD and PLD muscles from 9 week old chickens. The threshold for calcium activation of contraction was found to at a pCa-of 7.5 for the ALD and of 6.63 for the PLD. The ALD showed a minimum calcium binding site number of 2 and the PLD of 3. The maximum isometric tension observed was approximately 8.3 Nom- 2 for 162 both muscles. The ALD-therefore will contract at extremely low free calcium levels whereas the PLD needs almost 0.2 micro M higher free calcium to contract. Possible explanations for this difference and the differences in physiology and. function of the two muscles are presented.

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Orientador: Reginaldo José Donatelli / Banca: Sérgio Roberto Posso / Banca: Márcia Cristina Pascotto / Resumo: As aves Anhimidae (Ordem: Anseriformes) são constituídas por três espécies (Anhima cornuta, Chauna chavaria e C. torquata) endêmicas da América do Sul; seu esqueleto dotado de extrema pneumatização juntamente com a ausência do processo uncinado nas costelas, caracterizam bem esse grupo. Estudos detalhados voltados para anatomia craniana dessa família são escassos. Sendo assim, a osteologia craniana das três espécies da família Anhimidae foi descrita e comparada para verificar se existem variações interespecíficas nos crânios dessas aves e discutir os aspectos morfofuncionais desse grupo; além disso, o crânio dessas espécies foi comparado com o crânio de algumas espécies das famílias Cracidae, Anseranatidae e Anatidae com o intuito de listar um conjunto de caracteres exclusivos dos anhimídeos e discutir como alguns caracteres cranianos evoluíram nessas famílias. Foram identificadas 23 diferenças interespecíficas encontradas no crânio dos membros da família Anhimidae, sendo que a maioria delas diferencia o gênero Chauna de Anhima. Os caracteres que mais caracterizam os anhimídeos são o processo pós-orbital; a aponeurose ossificada do músculo adutor externo; o processo jugal; a fossa coanal do palatino; o processo ótico do quadrado; a fossa medial da mandíbula; e o processo retroarticular da mandíbula. Ainda, o estudo dos caracteres cranianos mostrou maior semelhança entre os anhimídeos e os demais Anseriformes, que quando comparados com os Galiformes, justificando sua posição dentro dos Anseriformes. E concluiu-se que a região esquamosal foi a que mais sofreu modificações compensando o baixo desenvolvimento de suas fossas e a ausência do processo esquamosal; além disso, a mandíbula se destacou como a região mais desenvolvida do crânio com seus longos processos e amplas fossas. Desta forma... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Not available / Mestre

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Made available in DSpace on 2014-06-11T19:27:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-01Bitstream added on 2014-06-13T19:56:03Z : No. of bitstreams: 1 previatto_dm_me_botib.pdf: 968097 bytes, checksum: 84df5889145a8cdc40831e75c48e759a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As aves Anhimidae (Ordem: Anseriformes) são constituídas por três espécies (Anhima cornuta, Chauna chavaria e C. torquata) endêmicas da América do Sul; seu esqueleto dotado de extrema pneumatização juntamente com a ausência do processo uncinado nas costelas, caracterizam bem esse grupo. Estudos detalhados voltados para anatomia craniana dessa família são escassos. Sendo assim, a osteologia craniana das três espécies da família Anhimidae foi descrita e comparada para verificar se existem variações interespecíficas nos crânios dessas aves e discutir os aspectos morfofuncionais desse grupo; além disso, o crânio dessas espécies foi comparado com o crânio de algumas espécies das famílias Cracidae, Anseranatidae e Anatidae com o intuito de listar um conjunto de caracteres exclusivos dos anhimídeos e discutir como alguns caracteres cranianos evoluíram nessas famílias. Foram identificadas 23 diferenças interespecíficas encontradas no crânio dos membros da família Anhimidae, sendo que a maioria delas diferencia o gênero Chauna de Anhima. Os caracteres que mais caracterizam os anhimídeos são o processo pós-orbital; a aponeurose ossificada do músculo adutor externo; o processo jugal; a fossa coanal do palatino; o processo ótico do quadrado; a fossa medial da mandíbula; e o processo retroarticular da mandíbula. Ainda, o estudo dos caracteres cranianos mostrou maior semelhança entre os anhimídeos e os demais Anseriformes, que quando comparados com os Galiformes, justificando sua posição dentro dos Anseriformes. E concluiu-se que a região esquamosal foi a que mais sofreu modificações compensando o baixo desenvolvimento de suas fossas e a ausência do processo esquamosal; além disso, a mandíbula se destacou como a região mais desenvolvida do crânio com seus longos processos e amplas fossas. Desta forma... / Not available

The functions of the elongated tails of birds have been the subject of much discussion in recent years. It is clear that in some cases the tail represents a sexually selected ornament, playing a vital role in mate choice. However. what is becoming increasingly apparent is that the tail can also play vital aerodynamic roles during flight, and can thus be a result of natural selection. Tail length manipulation experiments carried out during this work have shown that elongated graduated tails have an aerodynamic role during gliding flight. A function in the maintenance of stability (ring necked pheasants (Phasianus colchicus)) and optimising gliding performance (black-billed magpie (Pica pica)). thus these elongated graduated tails have been shown to be a product of natural selection. The question of whether correlated evolution occurred between the advent of gliding flight and the graduated tail shape was investigated. It was found that graduated tails did not co-evolve with gliding flight. However, it was shown that graduated tails had correlated evolution with tail elongated. It has been suggested that the forces acting on a triangular tail can be predicted through the application of slender lifting surface theory and the tail being analogous to a delta wing. This would predict that the tail functioned as a consistent lift producing surface. This study considered whether the tail functioned as a lift producer or a control surface. Stereo video of Harris' hawks (Parabuteo unicinctus) was used to assess tail function of a triangular tail. However, the results did not provide conclusive evidence for either theory. In this thesis I show that elongated avian tails perform a number of naturally selected aerodynamic roles during flight.

Sexual dimorphism has been noted to exist in many genera of birds, but it is not until recently that papers have appeared which deal with the actual extent of sexual dimorphism and its possible adaptive significance. The papers of Rand (1952), Sibley (1957), Amadon (1959), and Selander (1966) hypothesize about the possible significance of sexual dimorphism in birds, and the papers of Kilham (1965), Selander (1965), Storer (1966), Ligon(1968), Ingolfsson (1969), and Verner and Willson (1969) examine the relationship between hypotheses on the significance of sexual dimorphism and actual field conditions. None of these papers deals with differences in bone or muscle ratios which may exist between the sexes. A paper by Engels (1938a) on variation in bone length and limb proportion in the coot does examine differences in bone length and limb proportions due to sex, but only in a very cursory manner. It appears that only the most obvious and well known sexually dimorphic birds, i.e. woodpeckers, birds-of-paradise, accipitrines, have been studied. In this paper my purpose is to ascertain osteological and myological differences between the sexes of a bird which does not have a great deal of apparent sexual dimorphism - Sturnella neglecta neglecta Audubon, A.O.U. 501.1.