The variability of baroreflex sensitivity in juvenile, spontaneously hypertensive rats

In this study the baroreflex sensitivity of conscious, juvenile, spontaneously hypertensive rats (SHRs) was compared. The study population consisted of 19 eight-week-old male SHRs. The baroreflex sensitivity was quantified as the derivative of the variation in heart rate (HR) and the variation of mean arterial pressure (baroreflex sensitivity = Delta HR/Delta MAP). MAP was manipulated with sodium nitroprusside (SNP) and phenylephrine (PHE), administered via an inserted cannula in the right femoral vein. The SHRs were divided into four groups: (1) low bradycardic baroreflex (LB) where the baroreflex gain (BG) was between 0 and 1 bpm/mmHg with PHE; (2) high bradycardic baroreflex (HB), where the BG was < -1 bpm/mmHg with PHE; (3) low tachycardic baroreflex (LT) where the BC was between 0 and 3 bpm/mmHg with SNP; (4) high tachycardic baroreflex (HT) where the BG was > 3 bpm/mmHg with SNP. We noted that 36.8% of the rats presented with an increased bradycardic reflex, while 27.8% demonstrated an attenuated tachycardic reflex. No significant alterations were noted regarding the basal MAP and HR. There were significant differences in the baroreflex sensitivity between SHRs in the same laboratory. One should be careful when interpreting studies employing the SHR as a research model.

Evaluating the annual nature of juvenile rings in Bolivian tropical rainforest trees

Knowledge on juvenile tree growth is crucial to understand how trees reach the canopy in tropical forests. However, long-term data on juvenile tree growth are usually unavailable. Annual tree rings provide growth information for the entire life of trees and their analysis has become more popular in tropical forest regions over the past decades. Nonetheless, tree ring studies mainly deal with adult rings as the annual character of juvenile rings has been questioned. We evaluated whether juvenile tree rings can be used for three Bolivian rainforest species. First, we characterized the rings of juvenile and adult trees anatomically. We then evaluated the annual nature of tree rings by a combination of three indirect methods: evaluation of synchronous growth patterns in the tree- ring series, (14)C bomb peak dating and correlations with rainfall. Our results indicate that rings of juvenile and adult trees are defined by similar ring-boundary elements. We built juvenile tree-ring chronologies and verified the ring age of several samples using (14)C bomb peak dating. We found that ring width was correlated with rainfall in all species, but in different ways. In all, the chronology, rainfall correlations and (14)C dating suggest that rings in our study species are formed annually.

Characterizations of juvenile stages of some semaeostome Scyphozoa (Cnidaria), with recognition of a new family (Phacellophoridae)

Phacellophora camtschatica has long been assigned to the semaeostome scyphozoan family Ulmaridae. Early stages (scyphistomae, strobilae, ephyrae, postephyrae, and young medusae) of the species were compared with those of several other semaeostomes currently assigned to Ulmaridae, Pelagiidae, and Cyaneidae. Juveniles of P. camtschatica did not strictly conform with characters of those of any of these families, and appeared intermediate between Cyaneidae and Ulmaridae. A new family, Phacellophoridae, is proposed to accommodate P. camtschatica.

Rhyacian (2.23-2.20 Ga) juvenile accretion in the southern Sao Francisco craton, Brazil: Geochemical and isotopic evidence from the Serrinha magmatic suite, Mineiro belt

The Serrinha magmatic suite (Mineiro belt) crops out in the southern edge of the Sao Francisco craton, comprising the Brito quartz-diorite, Brumado de Cima and Brumado de Baixo granodiorites, granophyres and felsic sub-volcanic and volcanic rocks, part of which intruded into the Nazareno greenstone belt. The suite rocks have petrographic features that are consistent with magma supercooling due to the low water content combined with volatile loss, leading to crystallization of quartz and alkaline feldspar at the rims of plagioclase phenocrysts (granophyric intergrowth). The investigated rocks are sub-alkaline, calc-alkaline and show low content in rare earth elements. The U-Pb zircon crystallization ages for the Brumado de Cima granodiorite [2227 +/- 22 (23) Ma] and a coeval granophyre [2211 +/- 22 (23) Ma], coupled with available single-zircon Pb evaporation ages for the Brito and Brumado de Baixo plutons, are significantly older than the ""Minas orogeny"" (ca. 2100-2050 Ga) of Quadrilatero Ferrifero area, eastward from the Serrinha suite. Our data establish an early Rhyacian event tectonically linked with the evolution of the Mineiro belt. The bulk Nd isotopic signature [low negative to positive epsilon(Nd(t)) values] of the Serrinha samples are consistent with the important role of Paleoproterozoic mantle components in the magma genesis. The integrated geologic, geochemical and isotopic information suggests that Paleoproterozoic evolution of the Mineiro belt initiated in a passive continental margin basin with deposition of the Minas Supergroup at ca. 2500 Ma. This stage was succeeded by outboard rupture of the oceanic lithosphere with development and coalescence of progressively younger magmatic arcs during Rhyacian time. One of the earliest arcs formed the Serrinha suite. The tectonic collage of the Serrinha and Ritapolis (2190-2120 Ma) arcs produced the NE-SW Lenheiro shear zone, resulting in mylonitization and recrystallization of both the granitoid intrusions and host rocks. As a matter of fact juxtaposition of distinct magmatic units in age and origin took place along the Lenheiros structure in this sector of the Mineiro belt. (C) 2009 Elsevier Ltd. All rights reserved.

February 2003: Juvenile Collection Serves WU Community

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Contribution to the chemoreception capacity of juvenile Loggerhead sea turtles (Caretta caretta, L.)

Loggerhead sea turtle juveniles (Caretta caretta), pelagic stage, are found in waters of Madeira archipelago. Pelagic turtles are in the main growth phase of their life cycle and consequently higher energy needs. However, knowledge about the ecology of pelagic loggerhead sea turtles is still quite rudimentary, mainly about the mechanisms that lead them to find food in the vast ocean. Studies with other pelagic species, such as procellariiform birds, revealed that the olfactory system play an important role for the detection of feeding areas, through the detection of concentration peaks of DMS (dimethylsulfide), a scent compound that naturally exists in the marine environment and it is related to areas of high productivity. Based on the assumption that loggerhead sea turtles use a similar mechanism, behavioural experiments were conducted in order to analyze the chemoreception capacity to DMS (airborne chemoreception - theoretically responsible for the long distance detection of areas with food patches; and aquatic chemoreception - theoretically responsible for the short distance detection of preys). The first step was to observe if pelagic loggerheads demonstrate sensitivity to DMS and the second was to verify if they really use the DMS, in natural conditions, as an airborne cue to find areas where food patches might be available. Four juveniles of loggerhead sea turtles were tested in captivity and three wild turtles in the open ocean. The results of airborne chemoreception experiments in captivity revealed that one turtle clearly demonstrated sensitivity to DMS and the sea experiments confirmed this result. However, the experiments were not conclusive on the question whether the pelagic turtles actually use the DMS as an airborne cue to detect long distance food patches. In aquatic chemoreception experiments was not observed sensitivity to DMS by the three sea turtles tested. In the classical conditioning experiment, where DMS and food were given nearly at the same time revealed that after a certain period of time, the sea turtle tested did not associated the DMS stimulus with a possible food reward. The main cause of mortality of loggerhead sea turtles in Madeira waters is due to the accidental capture (bycatch) by deep pelagic longlines fishery which the target species is the black-scabbard (Aphanopus carbo) fish. Chub mackerel (Scomber japonicus) is one of the baits used in this fishery. Aquatic chemoreception experiments were conducted in order to evaluate the attractiveness of the chub mackerel for sea turtles. For the three sea turtles tested, the results showed that in 90% of the cases the sea turtles were extremely attracted by the underwater smell of this fish.

Longitudinal distribution and lateral pattern of megalopal settlement and juvenile recruitment of Carcinus maenas (L.) (Brachyura, Portunidae) in the Mira River Estuary, Portugal

Settlement is a critical process in the life history of crabs, and thus affecting the abundance, distribution and structure of estuarine communities. The spatial pattern of settlement of megalopae of the shore crab Carcinus maenas along a longitudinal estuarine gradient (Mira River Estuary, Portugal) was examined, as well as its effects on the juvenile population. To measure megalopal settlement, four replicate collectors were deployed in six equally spaced stations along the estuarine axis. Juveniles were collected on the same locations with a quadrat randomly deployed on the substrate. To assess fine-scale megalopal settlement within a curved region of the estuary, replicate collectors were deployed on both margins along Moinho da Asneira curve. Megalopae settled differently along the six longitudinal points, with a tendency to attenuate their settlement upstream. Within the curved region, megalopae preferentially settled on the left margin collectors, probably due to the weaker velocity speeds felt on this margin. Concerning the overall juvenile density, there were significant differences among the stations distributed along the estuary, but they did no reflect a longitudinal dispersion attenuation pattern. Size-frequency distribution of the juvenile population showed that the average size is higher on the left margin. Recruits (carapace length between 1.0 mm and 3.4 mm) were more abundant on the upstream stations. Density of early juveniles (3.4 mm-6.5 mm) and juveniles (6.5 mm-10 mm) was more stable throughout the estuary axis than that of recruits. This distribution pattern may result from tidal excursion processes or mechanisms to avoid biotic interactions, such as predation and competition. (c) 2006 Elsevier Ltd. All rights reserved.

Parasitology of juvenile mullet (Mugil liza) and effect of formaldehyde on parasites and host

Few studies have been performed with parasites of marine and estuarine fish in southern Brazil. In the present study, unpublished results show the ways of parasitism of juvenile mullet by parasites. The toxicity of formaldehyde and the effectiveness of this chemotherapy in controlling parasites in reared juvenile mullet Mugil liza were also studied. Juvenile mullets (1 +/- 0.26 g; 4.1 +/- 0.4 cm) were exposed to different concentrations of 37% formaldehyde: control group and five formaldehyde concentrations which were tested: T1 (13.5), T2 (21.6), T3 (40.5), T4 (81) and T5 (135) mg L-1 with 8 fish per repetition in triplicate. To verify the drug effectiveness in parasitic control, juvenile mullets were exposed to 1 h prophylactic bath of 37% formaldehyde with a control group and five formaldehyde concentrations: T1 (67.5), T2 (135), T3 (270), T4 (405) and T5 (540) mg L-1, 8 fish per repetition in triplicate. Ligophorus cf. uruguayensis (Monogenoidea: Ancyrocephalidae) and Solostamenides cf. platyorchis (Monogenoidea: Microcotylidae) were identified in the gills. Digenea and Nematoda were observed in the intestines. This is the first occurrence of S. cf. platyorchis in Brazil. During the toxicity test, the LC50-96 h was estimated at 20.77 mg L-1 of formaldehyde. During the 1 h formaldehyde prophylactic bath, all parasites were eliminated in formaldehyde concentrations between 135 and 540 mg L-1. High survival rate was observed in all treatments. Values of prevalence and intensity of infestation observed in this study showed the potential damage caused by Monogenoidea to mullet. Formaldehyde baths with 135 mg L-1 are recommended to control Monogenoidea in mullet and the safe limits for formaldehyde use were presented. Besides, the endoparasites were tolerant to formaldehyde exposure. (C) 2012 Elsevier B.V. All rights reserved.

Probiotic in feeding of juvenile matrinxã (Brycon amazonicus): economic viability

Objetivou-se analisar a viabilidade econômica do uso do probiótico Bacillus subtilis na alimentação de matrinxã Brycon amazonicus, em tanques-rede. O experimento foi conduzido no Polo Regional do Vale do Ribeira, no município de Pariquera-Açu, São Paulo, Brasil, entre fevereiro e julho de 2009. Foram avaliados 960 peixes juvenis, divididos em 12 tanques-rede de 2,7 m³ (1,5 x 1,5 x 1,2 m) em uma área total de 600 m², com profundidade média de 1,50 m. Os testes foram conduzidos com um tratamento testemunha (T1), duas doses de probiótico (T2 = 5 g e T3 = 10 g kg-1 de ração) e quatro repetições. Os resultados mostraram que o T2 proporcionou melhor desempenho zootécnico e econômico da matrinxã na fase de engorda no sistema intensivo de criação.

Stress responses in juvenile pacu (Piaractus mesopotamicus) submitted to repeated air exposure.

Pacu juveniles (5.2 [plus or minus] 1.5 g) were submitted to two one-minute air exposures in a 24h interval, and sampled before the exposure (control) and 5, 15, 30 and 60 min., 24 and 48h afterwards for whole-body cortisol, sodium, potassium and calcium ion concentrations. For the first air exposure, there was a trend of increased cortisol concentration after 15 min., whereas in the second air exposure, the cortisol concentration increased significantly within 5 min. after stress was induced. Sodium ion concentration increased significantly 24h after both air exposures. Potassium concentration presented fluctuations over the experimental period. Calcium ion concentration increased progressively from 5 to 30 min., in both air exposures. The repeated air exposures exacerbated the cortisol response, but they did not affect the recovery ability of pacu over the experimental period. Additionally, the whole-body cortisol measurement might be a reliable indicator of stress, when sampled fish are smaller and blood volumes are very low, making samples inadequate for analysis.

Stress responses of juvenile matrinxã (Brycon amazonicus) after transport in a closed system under different loading densities

Neste estudo, foram investigadas as densidades de carga adequadas para transporte de matrinxãs juvenis em sistema fechado com sacos plásticos. O transporte de 4h foi feito com peixes (23,5±0,4g; 11,6 (0,08cm) em jejum por 24h, em densidades de 83g L-1 (D1), 125g L-1 (D2), 168g L-1 (D3) e 206g L-1 (D4). Os peixes foram amostrados antes do transporte (AT), logo após o transporte (chegada) (DT) e 24h depois. A qualidade da água foi monitorada antes da captura dos peixes nos tanques de depuração, após o transporte nos sacos plásticos e nos tanques de recuperação. O oxigênio da água diminuiu para valores inferiores a 4mg L-1 em D2, D3 e D4, a temperatura esteve em torno de 32°C, pH 6,5-6,78, a amônia total foi de 1,09-1,7mg L-1, a amônia não-ionizada foi de 3,58-9,33 x 10³mg L-1 e alcalinidade 134-165mg CaCO3 L-1. O cortisol plasmático e a glicose sanguínea aumentaram após o transporte nos peixes em todas as densidades ensaiadas, voltando aos valores controle 24h depois. Os valores de osmolaridade não mudaram logo após o transporte, mas aumentaram 24h depois de modo igual em todas as densidades. O cloreto plasmático diminuiu na chegada, de modo inversamente proporcional à densidade de carga. O hematócrito diminuiu 24h depois da chegada dos peixes, em todas as densidades testadas, mas não houve diferença no número de eritrócitos. Não houve mortalidade até uma semana após o transporte. O matrinxã mostrou ser uma espécie tolerante a altas densidades de carga em embalagens para transporte além de suportar baixos níveis de oxigênio na água.

Dietary L-tryptophan alters aggression in juvenile matrinxa Brycon amazonicus

This study evaluated the effect of dietary supplementation with -tryptophan (L-TRP), a serotonin precursor, on the aggressiveness of juvenile matrinx . Fish were kept in individual aquaria for 7 days receiving the diets: D1 (control: 0.47% of TRP), D2 (0.94% of TRP), D3 (1.88% of TRP), and D4 (3.76% of TRP). After this, they were grouped with an intruder fish to establish a resident-intruder relationship during periods of 20 min. Blood cortisol, glucose, chloride, sodium and calcium; hemoglobin, hematocrit, red blood cell count and volume; liver glycogen and lipids were measured. Territoriality had significant effect on the aggressiveness of matrinx (the residents were more aggressive than intruders, < 0.001) and tryptophan significantly affected their behavior. Fish fed with the D2 diet presented a longer latency until the first attack ( = 0.0069) and bit the intruder fewer times ( = 0.0136) during the period of observation, compared to the control group. The frequency of bites and chases after the first attack was not affected by the dietary supplementation of TRP. Physiological variables were not significantly affected by the diet, except for a moderate increase in cortisol level in fish fed with D2 diet after the fight, indicating slight activation of the hypothalamus-pituitary-interrenal axis. The results show that juvenile matrinx have aggressive and territorial behavior and that a diet containing 9.4 g TRP kg(-1) alter their aggressiveness, without affecting the stress-related physiological parameters.