Estudo morfo-funcional comparativo da retina dos peixes antárticos Notothenia (Gobionotothen) Gibberifrons Lonnberg, 1905 e Trematomus newnesi Boulenger, 1902

Orientadora: Doutora Edith Susana Elisabeth FantaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Curso de Pós-Graduação em MorfologiaInclui referências: p. 69-74Área de concentração: Biologia CelularResumo: Os peixes Antárticos Notothenia (Gobionotothen) gibberifrons Lònnberg, 1905 e Trematomus newnesi Boulenger, 1902, apresentam diferentes comportamentos visuais e estão sujeitos a diferentes fotoperíodos durante o ano. Com base nestas afirmativas, esta pesquisa foi feita com o objetivo de se verificar se a morfologia retiniana seria correspondentemente diferenciada, qual sua estrutura e suas adaptações, comparativamente. Exemplares de 15 à 18 cm de comprimento total, foram coletados na Baía do Almirantado, Ilha do Rei George, e observados em condições ambientais controladas por 10 dias. Os olhos foram fixados em Líquido de Bouin, emblocados em "Paraplast Plus", cortados em 3 micrômetros de espessura, corados em: Hematoxilina-Eosina, para evidenciar núcleo e citoplasma; Tricrômico de Mallory, para evidenciar tecidos do olho; Hematoxilina Férrica de Heidenhain para destacar as porções dendríticas e axônicas das células da retina; Novelli que evidencia regiões que contêm mitocôndrias. Estas espécies de peixes possuem diferentes campos visuais. N. (G.) gibberifrons apresenta movimentos independentes dos olhos, retina larga, cones e bastonetes finos e longos. Em T newnesi os cones são grandes e largos e os bastonetes largos e curtos. Em ambos, o mosaico de cones é na forma de quadrado e apresenta três tipos destas células, com o segmento interno dos cones duplos subdividido e levemente torcido. Em T. newnesi há diferenças estruturais da retina na região do fundo do olho e em N. (G.) gibberifrons nas porções laterais. Em luz contínua há expansão dos pigmentos do epitélio pigmentar, que passam a recobrir os bastonetes. Quando no escuro continuamente, estes pigmentos se retraem. Em nenhum caso verificou-se movimentos retinomotores dentro do ritmo circadiano de ambas as espécies. Todas estas características morfológicas dos olhos permitem reações visuais rápidas e direcionadas, em meia água e na superfície em T. newnesi, e reações visuais lentas em amplo campo da região próxima ao fundo em N. (G.) gibberifrons.Abstract: Two Antarctic fish Notothenia (Gobionotothen) gibberifrons Lonnberg, 1905 and Trematomus newnesi Boulenger, 1902 show different visual behavior and are submitted to different photo periods along the year. The aim of this study was to detect possible corresponding morphological characteristic and adaptations of the retina. Individuals between 15 and 18 cm total length were caught at the Admiralty Bay, King George Island, and observed under controlled environmental conditions for 10 days, after acclimation. Their eyes were fixed in Bouin's fluid, embedded in "Paraplast Plus", cut in 3 micrometers sections, stained with: Haematoxylin - Eosin for nuclear and cytoplasmic differentiation; Mallory trichrome to evidence different tissues; Heidenhein Iron Haematoxylin to evidence dendritic and axonic regions of the retinal cells; Novelli that shows regions that contain mitochondria. These species of fish have different visual fields, and N (G.) gibberifrons shows independent eyes movements, having a thick retina with a great number of thin and long cones and rods. In T. newnesi cones are thick and big and rods thick and short. In both, the cone mosaic is arranged in square and showing three types of these cells, being the internal segment of the double cones subdivided and slightly bent. Structural differences between regions occur laterally in N. (G.) gibberifrons and at the hind region of the retina in T newnesi. In constant light the pigments expand covering the rods, the opposite being observed in long dark periods. In both species, no retinomotor movements were observed in the circadian rhythms in these light conditions. These characteristic allow a fast and directed visual reaction in mid water and surface for T. newnesi, and slow visual reactions in a broad area close to the bottom in N. (G.) gibberifrons

Histopathological effects of silver nanoparticles in Rhamdia quelen after oral exposure

The studies about silver nanoparticles (AgNP) increased in the last years but few is known about their effects in Brazilian neotropical freshwater fish species. The current study investigated the effects of AgNP on adult silver catfish Rhamdia quelen after subchronic oral exposure. After nanoparticle (NP) size and area characterization fish were administrated with three different doses for 15 days (0.03, 0.3 and 3 μg g-1). The concentration of silver in liver and kidney was measured to evaluate the bioaccumulation and discuss its effects in the target organs. Liver bioaccumulated 15, 1.7 and 0.2 % of administered doses while kidney bioaccumulated 1.33, 0.33 and 0.9 % (respectively for 0.03, 0.3 and 3 μg g-1). The histopathological findings were considered in both organs to evaluate the effects of AgNP, according to Bernet’s Lesion Index (BLI). Also were included the melano-macrophages center (MMC) and new nephrons (NN) counting respectively in liver and posterior kidney. The results revealed morphological injuries as inflammation in both studied organs and vascular congestion and steatosis in liver, in a concentration dependent way. The presence of AgNP in the tissues revealed the bioavailability of the nanoparticle while the damages and morphological disturbs showed the potential risk of exposure in R. quelen, even under environmental relevant concentrations

Defect Engineering of Ta3N5 Photoanodes: Enhancing Charge Transport and Photoconversion Efficiencies via Ti Doping

While Ta3N5 shows excellent potential as a semiconductor photoanode for solar water splitting, its performance is hindered by poor charge carrier transport and trapping due to native defects that introduce electronic states deep within its bandgap. Here, it is demonstrated that controlled Ti doping of Ta3N5 can dramatically reduce the concentration of deep-level defects and enhance its photoelectrochemical performance, yielding a sevenfold increase in photocurrent density and a 300 mV cathodic shift in photocurrent onset potential compared to undoped material. Comprehensive characterization reveals that Ti4+ ions substitute Ta5+ lattice sites, thereby introducing compensating acceptor states, reducing the concentrations of deleterious nitrogen vacancies and reducing Ta3+ states, and thereby suppressing trapping and recombination. Owing to the similar ionic radii of Ti4+ and Ta5+, substitutional doping does not introduce lattice strain or significantly affect the underlying electronic structure of the host semiconductor. Furthermore, Ti can be incorporated without increasing the oxygen donor content, thereby enabling the electrical conductivity to be tuned by over seven orders of magnitude. Thus, Ti doping of Ta3N5 provides a powerful basis for precisely engineering its optoelectronic characteristics and to substantially improve its functional characteristics as an advanced photoelectrode for solar fuels applications

Exploring the impact of CMIP5 model biases on the simulation of North Atlantic decadal variability

Instrumental observations, palaeo-proxies, and climate models suggest significant decadal variability within the North Atlantic subpolar gyre (NASPG). However, a poorly sampled observational record and a diversity of model behaviours mean that the precise nature and mechanisms of this variability are unclear. Here, we analyse an exceptionally large multi-model ensemble of 42 present-generation climate models to test whether NASPG mean state biases systematically affect the representation of decadal variability. Temperature and salinity biases in the Labrador Sea co-vary and influence whether density variability is controlled by temperature or salinity variations. Ocean horizontal resolution is a good predictor of the biases and the location of the dominant dynamical feedbacks within the NASPG. However, we find no link to the spectral characteristics of the variability. Our results suggest that the mean state and mechanisms of variability within the NASPG are not independent. This represents an important caveat for decadal predictions using anomaly-assimilation methods

North Atlantic Climate Variability: Phenomena, Impacts and Mechanisms

Variability of the North Atlantic Oscillation and the Tropical Atlantic dominate the climate of the North Atlantic sector, the underlying ocean and surrounding continents on interannual to decadal time scales. Here we review these phenomena, their climatic impacts and our present state of understanding of their underlying caus

Estudo morfo-funcional comparativo da retina dos peixes antárticos Notothenia (Gobionotothen) Gibberifrons Lonnberg, 1905 e Trematomus newnesi Boulenger, 1902

Orientadora: Doutora Edith Susana Elisabeth FantaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Curso de Pós-Graduação em MorfologiaInclui referências: p. 69-74Área de concentração: Biologia CelularResumo: Os peixes Antárticos Notothenia (Gobionotothen) gibberifrons Lònnberg, 1905 e Trematomus newnesi Boulenger, 1902, apresentam diferentes comportamentos visuais e estão sujeitos a diferentes fotoperíodos durante o ano. Com base nestas afirmativas, esta pesquisa foi feita com o objetivo de se verificar se a morfologia retiniana seria correspondentemente diferenciada, qual sua estrutura e suas adaptações, comparativamente. Exemplares de 15 à 18 cm de comprimento total, foram coletados na Baía do Almirantado, Ilha do Rei George, e observados em condições ambientais controladas por 10 dias. Os olhos foram fixados em Líquido de Bouin, emblocados em "Paraplast Plus", cortados em 3 micrômetros de espessura, corados em: Hematoxilina-Eosina, para evidenciar núcleo e citoplasma; Tricrômico de Mallory, para evidenciar tecidos do olho; Hematoxilina Férrica de Heidenhain para destacar as porções dendríticas e axônicas das células da retina; Novelli que evidencia regiões que contêm mitocôndrias. Estas espécies de peixes possuem diferentes campos visuais. N. (G.) gibberifrons apresenta movimentos independentes dos olhos, retina larga, cones e bastonetes finos e longos. Em T newnesi os cones são grandes e largos e os bastonetes largos e curtos. Em ambos, o mosaico de cones é na forma de quadrado e apresenta três tipos destas células, com o segmento interno dos cones duplos subdividido e levemente torcido. Em T. newnesi há diferenças estruturais da retina na região do fundo do olho e em N. (G.) gibberifrons nas porções laterais. Em luz contínua há expansão dos pigmentos do epitélio pigmentar, que passam a recobrir os bastonetes. Quando no escuro continuamente, estes pigmentos se retraem. Em nenhum caso verificou-se movimentos retinomotores dentro do ritmo circadiano de ambas as espécies. Todas estas características morfológicas dos olhos permitem reações visuais rápidas e direcionadas, em meia água e na superfície em T. newnesi, e reações visuais lentas em amplo campo da região próxima ao fundo em N. (G.) gibberifrons.Abstract: Two Antarctic fish Notothenia (Gobionotothen) gibberifrons Lonnberg, 1905 and Trematomus newnesi Boulenger, 1902 show different visual behavior and are submitted to different photo periods along the year. The aim of this study was to detect possible corresponding morphological characteristic and adaptations of the retina. Individuals between 15 and 18 cm total length were caught at the Admiralty Bay, King George Island, and observed under controlled environmental conditions for 10 days, after acclimation. Their eyes were fixed in Bouin's fluid, embedded in "Paraplast Plus", cut in 3 micrometers sections, stained with: Haematoxylin - Eosin for nuclear and cytoplasmic differentiation; Mallory trichrome to evidence different tissues; Heidenhein Iron Haematoxylin to evidence dendritic and axonic regions of the retinal cells; Novelli that shows regions that contain mitochondria. These species of fish have different visual fields, and N (G.) gibberifrons shows independent eyes movements, having a thick retina with a great number of thin and long cones and rods. In T. newnesi cones are thick and big and rods thick and short. In both, the cone mosaic is arranged in square and showing three types of these cells, being the internal segment of the double cones subdivided and slightly bent. Structural differences between regions occur laterally in N. (G.) gibberifrons and at the hind region of the retina in T newnesi. In constant light the pigments expand covering the rods, the opposite being observed in long dark periods. In both species, no retinomotor movements were observed in the circadian rhythms in these light conditions. These characteristic allow a fast and directed visual reaction in mid water and surface for T. newnesi, and slow visual reactions in a broad area close to the bottom in N. (G.) gibberifrons

ナンキョク サン ギョルイ Trematomus newnesi ト Gobionotothen gibberifrons ニ オケル コトナッタ ヒカリ ジョウケン カ デノ サイエ センリャク ト コウドウ パターン ノ ヒカク ケンキュウ

南極半島にあるキングジョージ島, アドミラルティ湾ではノトセニア科の2種Trematomus newnesiとGobionotothen gibberifronsは生育場所を共にする底生魚である。しかし, 水槽内での飼育観察の結果, 両種の行動は, 24時間連続照明の場合と10時間暗, 14時間明の連続照明の場合とでは相違した。すなわち, 24時間照明の場合, G. gibberifronsはT. newnesiより, 早く, 長時間遊泳したが, 呼吸頻度は低かった。ところが, 10/14周期の場合, 両種の関係は逆転した。また, 生きている端脚類を餌として与えた場合, T. newnesiの採餌成功率は, G. gibberifronsの15倍と高い。形態観察の結果, 視覚の差が, これらの行動の差をもたらしていると考えられる。一方, G. gibberifronsを本種だけで飼育した場合, 採餌は水槽の表面付近でなされるが, T. newnesiが共存すると, G. gibberifronsは底付近でのみ採餌するようになる。餌の飲み込み行動にも差があり, これは味蕾の分布が両種で異なっていることによるものであろう。生育場所を同じくする両種は, それぞれの行動を違えることによって共生している。The behavior of Trematomus newnesi BOULENGER, 1902 and Gobionotothen gibberifrons (LONNBERG, 1905) (Pisces, Nototheniidae), caught in Admiralty Bay, King George Island, during the Antarctic summer, is compared. Experiments were done at 2℃ and two different light conditions. If both species are kept together in light for 24 hours, G. gibberifrons is usually more active than T. newnesi, swimming for longer periods, with higher speed, but showing lower respiratory frequency. An inversion occurs at 10/14 photo period. Rhythms may be observed in both light conditions for some behavioral patterns. If compared to G. gibberifrons the feeding success is 15 times higher for T. newnesi : it seems to detect shapes and movements at longer distances, swimming directly toward the prey, ingesting and swallowing at once. G. gibberifrons, in the presence of T. newnesi, takes a long time to react to the food and catches it only at the bottom, swimming through short jumping movements. If not in the presence of T. newnesi, it may catch the prey near the surface, with slow movements, but in any case food must be tasted inside the mouth before it is accepted as such. G. gibberifrons has more taste buds in the upper lips and in the pharyngeal region of the branchial arches than T. newnesi. The eyes seem better developed in T. newnesi. They are differently planced in both species, leading to different visual fields. One can conclude that when G. gibberifrons and T. newnesi share the same environment, behavioral strategies are developed to avoid each other