Thesis (Ph. D.)--University of Michigan, 1940. / Caption title. Thesis note on slip mounted on p. 171. "Contribution from the Department of Zoology, University of Michigan." "Reprinted from Transactions of the American Microscopical Society, vol. LX, no. 2, April, 1941." Bibliography: p. 208-210.

Thesis (Ph. D.)--University of Michigan, 1940. / Cover title. "Contribution from the Department of zoology, University of Michigan." "Reprinted from Transactions of the American microscopical society, vol. LX, no. 2, April, 1941." Bibliography: p. 258-260.

No description available.

The oxygen consumptions of gill and kidney tissues of the cutthroat trout (Salmo clarki clarki) were determined by the direct method of Warburg. The respiration rates of tissues from fish ranging from 10 to 100 gm. were examined in relation to body weight. A decline in weight specific oxygen consumption for both tissues was observed. On a log-log plot, the regression coefficient for kidney was -.148 while that for gill was -.139. The decline did not support the .73 rule (Brody, 1945) at the level of tissue respiration. The oxygen consumptions of kidney and gill tissues were examined during a 168 hour period after transfer of the fish from fresh water to 65% standard sea water. A sharp initial rise in QO₂ of kidney tissue was noted during the first 48 hours after transfer, reaching a maximum at 20 hours. The kidney tissue respiration during the remainder of the experimental period remained significantly higher than the parallel control level. The gill tissue respiration declined rapidly during the first 10 hours after transfer and remained significantly below the control level during the whole experimental period. The results are discussed in relation to recent observations of Holmes, Chester Jones, Phillips, and Sexton, concerning possible hormonal regulation of salt-electrolyte and water metabolism by vasopressin and adrenocortical steroids in euryhaline species of salmonids. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Thesis (doctoral)--Universität Bonn, 1893. / Cover title. At head of title: Mittheilung aus dem zoologisch. und vergleichend-anatomisch. Institut der Univ. Bonn." Vita. "Separat-abdruck aus: Zeitschrift für wissensch. Zoologie. Bd. LV. 4. Heft"--T.p. verso.

The cellular mechanisms responsible for rectal acidification in the desert locust, Schistocerca gregaria, were investigated in isolated recta mounted as flat sheets in modified Ussing chambers. In the absence of exogenous CO₂, HCO₃⁻, and phosphate, the isolated rectum (under both open- and short-circuit current conditions) was capable of rates of net acid secretion (J[subscript]H+) similar to those observed in vivo, demonstrating the viability of the preparation and suggesting that rectal acidification was due to proton secretion rather than selective movements of HCO₃⁻ or phosphate. The possibility that trace levels of metabolic CO₂ might be generating sufficient HCO₃⁻ to account for the observed rates of rectal acidification (via HCO₃⁻ reabsorption) was assessed by adding exogenous CO₂/HCO₃⁻ to the contraluminal bath. The small increases in J[subscript]H+ observed after addition of 2% or 5% CO₂ were shown to be due to simple hydration of CO₂ which had diffused into the lumen (from the contraluminal bath), rather than changes in rates of HCO₃⁻ reabsorption. Since measurable quantities of luminal HCO₃⁻ did not directly affect the apical acid/base transport mechanism per se, it was concluded that metabolic CO₂ could not generate sufficient HCO₃⁻ in the lumen to account for the rates of rectal acidification observed under nominally CO₂/HCO₃⁻-free conditions and that J[subscript]H+ must be due to a proton secretory rather than bicarbonate reabsorptive mechanism. Microelectrode measurements of intracellular pH (pHi) and apical and basolateral membrane potentials (Va and Vb respectively) indicated that luminal pH was not in equilibrium with either contraluminal pH or pHi and that the mechanism responsible for active luminal acid secretion resided on the apical membrane. Preliminary measurements of bath total ammonia (ie. NH₃ + NH₄+) levels in the previous experiments suggested that the rectum was actively secreting ammonia at significant rates across the apical membrane into the lumen. If the ammonia crossed the apical membrane as NH₃ rather than NH₄+, rates of luminal ammonia secretion (J[subscript]Amm) would have to be added to J[subscript]H+ to obtain corrected values of luminal proton secretion. In the absence of exogenously added ammonia and CO₂, ammonia was preferentially secreted into the lumen under both open- and short-circuit current conditions. J[subscript]Amm was dependent on the presence of luminal amino acids and was relatively unaffected by K[superscript]+ removal or changes in luminal pH from 7.00 to 5.00. Bilateral Na+ substitution or luminal addition of ImM amiloride reduced J[subscript]Amm by 63% and 65% respectively. The data consistently demonstrate that the rectum secretes significant quantities of endogenously produced ammonia preferentially into the lumen as NH₄+ rather than NH₃ via an apical Na[superscript]+/NH₄[superscript]+ exchange mechanism. Clearly, rates of net acid secretion estimated by titratable acidity do not have to include a correction for luminal ammonia secretion. Although J[subscript]H+ was completely unaffected by changes in contraluminal pH, it could be progressively reduced (and eventually abolished) by imposition of either transepithelial pH gradients (lumen acid) or transepithelial electrical gradients (lumen positive). Under short-circuit current conditions, the bulk of J[subscript]H+ was not dependent on Na[superscript]+, K[superscript]+, CI⁻, Mg₂+, or Ca+ and was due to a primary electrogenic proton translocating mechanism located on the apical membrane. A small component (10-16%) of J[subscript]H+ measured under these conditions could be attributed to an apical amiloride-inhibitable Na[superscript]+/H[superscript]+ exchange mechanism. Inhibition of JH+ by anoxia or reduction of luminal pH unmasked a significant proton diffusional pathway on the apical membrane in parallel with the active proton pump. The fact that J[subscript]H+ was significantly inhibited (42%-66%) by contraluminal addition of ImM cAMP and relatively unaffected by changes in contraluminal pCO₂ or pH suggests that net acid secretion in the locust rectum in vivo is modulated by circulating hormonal factors rather than haemolymph pH or pCO₂ per se. / Science, Faculty of / Zoology, Department of / Graduate

Made available in DSpace on 2014-06-11T19:32:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-17Bitstream added on 2014-06-13T21:03:49Z : No. of bitstreams: 1 penha_capv_dr_sjrp.pdf: 2323263 bytes, checksum: 5e66f0d4f644321ae88c6671e1d49f8f (MD5) / O sistema de excreção em artrópodes terrestres é formado de estruturas denominadas túbulos de Malpighi. São órgãos extremamente importantes nos insetos, pois mantêm a osmorregulação. Encontram-se localizados na cavidade corporal, podendo apresentar-se livres ou inseridos na parede do reto, formando um arranjo conhecido como sistema criptonefridial. Os túbulos de Malpighi podem se apresentar com regiões morfologicamente diferentes, cada uma dessas regiões apresentando um determinado tipo celular. Em numerosas espécies pode ocorrer a existência de segmentos, cada qual com um tipo celular diferente. Especializações secundárias são observadas em túbulos de Malpighi, onde uma região do túbulo pode estar envolvida na produção de determinada substância, enquanto outra região é responsável pela produção de outro produto. Isto é o que ocorre com algumas espécies de insetos da ordem Neuroptera, cujos túbulos produzem o fio de seda do casulo durante a última fase larval. As células dos túbulos de Malpighi de Myrmeleon sp sofrem endorreplicação, durante o desenvolvimento larval, tornando-se altamente poliplóides no último estádio. Contudo, essa ploidia aumentada não se estabelece em todo o segmento do túbulo, mas apenas em determinadas regiões, fazendo com que se acredite que apenas determinados locais no túbulo sofram essas modificações para a produção da seda, sendo que as regiões restantes do túbulo permanecem com a função básica de osmorregulação. No presente estudo foram utilizadas técnicas citoquímicas (Azul de Toluidina, Xylidine Ponceau, Impregnação por Íons Prata) e de citogenética molecular (Hibridação in situ fluorescente - FISH). Estas técnicas permitiram a observação de alterações... / The land arthropod secretory system is formed by structures called Malpighian tubules. These tubules are extremely important in insects because they maintain osmoregulation. They are located in the body cavity. They are either free or inserted in the rectum wall, forming an arrangement known as the cryptonephridial system. The Malpighian tubules may have morphologically different regions, with each one formed by a specific cell type. Secondary specializations are found in Malpighian tubules, in which a region of the tube may be involved in the production of some substances, while other regions are responsible for other products. This is what occurs in cases of certain species of the order Neuroptera, which utilize tubules to produce cocoon silk thread during the last larva stage. The cells of Malpighian tubules of Myrmeleon sp undergo endoreduplication during the species' larval development, and they become highly polyplodic in the last larvae stage. However, this increased ploidy does not establish itself in all parts of the tubule, but only in select regions, which suggests that only some parts of the tubule undergo these modifications for silk production while the other regions of the tubule are still used for basic functions of osmoregulation. In this study, the following cytochemical techniques were used: Toluidine Blue, Xylidine Ponceau, Impregnation by AgNOR and the molecular cytogenetic technique called Fluorescence In Situ Hybridization (FISH). These techniques allowed us to see alterations on both the cellular and cytoplasmic levels. These alterations were evidence of an increase in synthesis of the substances secreted by specific cell types during the course of larval development. Ultrastructural analyses were also performed... (Complete abstract click electronic access below)

Orientador: Maria Tercília Vilela de Azeredo-Oliveira / Banca: Patrícia Pasquale Parise Maltempi / Banca: Grasiela Dias de Campos Aguiar / Banca: Alba Regina de Abreu Lima Catelani / Banca: Lílian Madi Ravazzi / Resumo: O sistema de excreção em artrópodes terrestres é formado de estruturas denominadas túbulos de Malpighi. São órgãos extremamente importantes nos insetos, pois mantêm a osmorregulação. Encontram-se localizados na cavidade corporal, podendo apresentar-se livres ou inseridos na parede do reto, formando um arranjo conhecido como sistema criptonefridial. Os túbulos de Malpighi podem se apresentar com regiões morfologicamente diferentes, cada uma dessas regiões apresentando um determinado tipo celular. Em numerosas espécies pode ocorrer a existência de segmentos, cada qual com um tipo celular diferente. Especializações secundárias são observadas em túbulos de Malpighi, onde uma região do túbulo pode estar envolvida na produção de determinada substância, enquanto outra região é responsável pela produção de outro produto. Isto é o que ocorre com algumas espécies de insetos da ordem Neuroptera, cujos túbulos produzem o fio de seda do casulo durante a última fase larval. As células dos túbulos de Malpighi de Myrmeleon sp sofrem endorreplicação, durante o desenvolvimento larval, tornando-se altamente poliplóides no último estádio. Contudo, essa ploidia aumentada não se estabelece em todo o segmento do túbulo, mas apenas em determinadas regiões, fazendo com que se acredite que apenas determinados locais no túbulo sofram essas modificações para a produção da seda, sendo que as regiões restantes do túbulo permanecem com a função básica de osmorregulação. No presente estudo foram utilizadas técnicas citoquímicas (Azul de Toluidina, Xylidine Ponceau, Impregnação por Íons Prata) e de citogenética molecular (Hibridação in situ fluorescente - FISH). Estas técnicas permitiram a observação de alterações... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The land arthropod secretory system is formed by structures called Malpighian tubules. These tubules are extremely important in insects because they maintain osmoregulation. They are located in the body cavity. They are either free or inserted in the rectum wall, forming an arrangement known as the cryptonephridial system. The Malpighian tubules may have morphologically different regions, with each one formed by a specific cell type. Secondary specializations are found in Malpighian tubules, in which a region of the tube may be involved in the production of some substances, while other regions are responsible for other products. This is what occurs in cases of certain species of the order Neuroptera, which utilize tubules to produce cocoon silk thread during the last larva stage. The cells of Malpighian tubules of Myrmeleon sp undergo endoreduplication during the species' larval development, and they become highly polyplodic in the last larvae stage. However, this increased ploidy does not establish itself in all parts of the tubule, but only in select regions, which suggests that only some parts of the tubule undergo these modifications for silk production while the other regions of the tubule are still used for basic functions of osmoregulation. In this study, the following cytochemical techniques were used: Toluidine Blue, Xylidine Ponceau, Impregnation by AgNOR and the molecular cytogenetic technique called Fluorescence In Situ Hybridization (FISH). These techniques allowed us to see alterations on both the cellular and cytoplasmic levels. These alterations were evidence of an increase in synthesis of the substances secreted by specific cell types during the course of larval development. Ultrastructural analyses were also performed... (Complete abstract click electronic access below) / Doutor