Crystallization and Preliminary Crystallographic Analysis of Laminarinase from Rhodothermus marinus: A Case of Pseudomerohedral Twinning

Thermophilic endo-1,3(4)-beta-glucanase (laminarinase) from Rhodothermus marinus was crystallized by the hanging-drop vapor diffusion method. The needle-like crystals belong to space group P2(1) and contain two protein molecules in the asymmetric unit with a solvent content of 51.75%. Diffraction data were collected to a resolution of 1.95 angstrom and resulted in a dataset with an overall R-merge of 10.4% and a completeness of 97.8%. Analysis of the structure factors revealed pseudomerohedral twinning of the crystals with a twin fraction of approximately 42%.

Effects of inhibition gastric acid secretion on arterial acid-base status during digestion in the toad Bufo marinus

Digestion affects acid-base status, because the net transfer of HCl from the blood to the stomach lumen leads to an increase in HCO3- levels in both extra- and intracellular compartments. The increase in plasma [HCO3-], the alkaline tide, is particularly pronounced in amphibians and reptiles, but is not associated with an increased arterial pH, because of a concomitant rise in arterial Pco(2) caused by a relative hypoventilation. In this study, we investigate whether the postprandial increase in Paco(2) of the toad Bufo marinus represents a compensatory response to the increased plasma [HCO3-] or a state-dependent change in the control of pulmonary ventilation. To this end, we successfully prevented the alkaline tide, by inhibiting gastric acid secretion with omeprazole, and compared the response to that of untreated toads determined in our laboratory during the same period. In addition, we used vascular infusions of bicarbonate to mimic the alkaline tide in fasting animals. Omeprazole did not affect blood gases, acid-base and haematological parameters in fasting toads, but abolished the postprandial increase in plasma [HCO3-] and the rise in arterial Pco(2) that normally peaks 48 h into the digestive period. Vascular infusion of HCO3-, that mimicked the postprandial rise in plasma [HCO3-], led to a progressive respiratory compensation of arterial pH through increased arterial Pco(2) Thus, irrespective of whether the metabolic alkalosis is caused by gastric acid secretion in response to a meal or experimental infusion of bicarbonate, arterial pH is being maintained by an increased arterial Pco(2). It seems, therefore, that the elevated Pco(2), occuring during the postprandial period, constitutes of a regulated response to maintain pH rather than a state-dependent change in ventilatory control. (C) 2003 Elsevier B.V. All rights reserved.

Sex ratio, growth and recruitment of the pelagic shrimp Acetes americanus on the southeastern coast of Brazil

We evaluated the population dynamics of Acetes americanus Ortmann, 1893 focusing on sex ratio, individual growth, longevity, and the juvenile recruitment period. Samples were collected monthly from January 2006 to June 2007 in the bay of Ubatuba, Brazil. Specimen growth was identified for each gender, and the chosen cohorts were fitted in a von Bertalanffy Growth Model (VBGM); longevity was estimated by the von Bertalanffy inverse equation, considering 99% of the asymptotic length. A total of 6881 individuals (2343 males and 4538 females) were captured. On average the body size (total length) was greater in females (14.64 ± 3.34 mm) than in males (12.27 ± 1.86 mm). The mean growth curves (obtained by grouping the cohorts for each sex), provided estimates of TL∞ = 19.33 mm, k = 0.02 and t0 = -0.12 days for females and TL∞ = 15.13 mm, k = 0.03 and to = -0.07 days for males, where TL∞ is the asymptotic length, k is coefficient of growth and to is the theorical age when the size is equal to 0. Longevity was estimated at 0.61 years for females and 0.50 years for males. The sex ratio tended to favor females, which corroborates with others studies of sergestids. Our finding that males of A. americanus have higher values of k and therefore achieve a smaller size relative to females has been observed in other penaeids. We concluded that this differential growth pattern between the sexes is found across Dendrobranchiata. The life cycles of penaeids have an average duration of approximately 1-2 years, but our results corroborate other studies that estimate a shorter longevity for Acetes, as species of this genus are typically smaller in size. We found continuous recruitment with two main peaks observed during the study period, corroborating previous studies of Acetes. © The Crustacean Society, 2013. Published by Brill NV, Leiden.

Distribution related to temperature and salinity of the shrimps Acetes americanus and Peisos petrunkevitchi (Crustacea: Sergestoidea) in the south-eastern Brazilian littoral zone

The abundance and ecological distribution of Acetes americanus and Peisos petrunkevitchi were investigated from July 2006 to June 2007, in Ubatuba, Brazil. Eight transects were identified and sampled monthly: six of these transects were located in Ubatuba bay, with depths reaching 21 m, and the other two transects were in estuarine environments. A total of 33,888 A. americanus shrimp were captured, with the majority coming from the shallower transects (up to 10 m). Conversely, 6,173 of the P. petrunkevitchi shrimps were captured in deeper areas (from 9 to 21 m). No individuals from either species were found in the estuary. The highest abundances obtained for both species were sampled during the summer. Canonical correlation analysis resulted in a coefficient value of 0.68 (P = 0.00). The abundance of both species was strongly correlated with depth. Variations in temperature and salinity values were also informative in predicting the seasonal presence of P. petrunkevitchi in deeper areas and A. americanus in the shallower areas of the bay. It is conceivable that the shrimp adjust their ecological distribution according to their intrinsic physiological limitations. © 2012 Marine Biological Association of the United Kingdom.

Correlações fisiológicas da carga parasitária em Rhinella icteriucus (Anura: marinus)

A presença de parasitas, que podem afetar inúmeros aspectos da biologia de seus hospedeiros, possivelmente levando a uma queda em seu desempenho. Entretanto, ao longo do estabelecimento da associação parasita-hospedeiro, alterações na fisiologia e morfologia deste último podem representar mecanismos compensatórios para os danos causados pelos parasitas. Sendo assim, carga parasitária deve ser um importante determinante do valor adaptativo (fitness) do hospedeiro. O objetivo do presente trabalho foi estabelecer possíveis correlações entre carga parasitária, massas de diversos órgãos e desempenho locomotor no sapo-cururu, Rhinella ictericus (Anura: Bufonidae). O desempenho locomotor dos indivíduos capturados de R. ictericus foi medido através do uso de uma pista circular de madeira. Durante um período de 10 minutos, os animais foram forçados a manter desempenho locomotor constante e a distância total percorrida foi corrigida para o comprimento rostro-cloacal. Depois das medidas de desempenho locomotor, os órgãos internos foram dissecados, tendo seus parasitas contabilizados. As massas de todos os órgãos escalaram positivamente com a massa corpórea. O número de parasitas nos pulmões e o índice corpóreo também se mostraram positivamente relacionados à variação em massa corpórea. Indivíduos com maior carga parasitária intestinal foram também aqueles que apresentaram um maior número total de parasitas, sugerindo a existência de variação individual na susceptibilidade a diferentes parasitas. O desempenho locomotor foi negativamente associado à carga parasitária total, demonstrando um efeito deletério causado pelos parasitas ao hospedeiro em um aspecto crucial de sua história de vida. Hospedeiros com maior carga parasitária pulmonar apresentaram maior massa intestinal e renal, sugerindo possíveis mecanismos compensatórios dos possíveis danos causados pelos parasitas

Willem Marinus Dudok. Progetti urbani per la citta' di Hilversum

Il tema principale affrontato dalla presente ricerca è quello dell’architettura della città; attraverso lo studio dei progetti urbani redatti dall’architetto Willem Marinus Dudok per la città di Hilversum, la tesi vuole confermare l’ipotesi che la costruzione dei “luoghi urbani” collettivi è il fulcro dell’idea di architettura che porta alla costruzione della città. La ricerca si propone di studiare il contributo dato da Dudok al progetto dello sviluppo urbano della città olandese, considerando un arco temporale che va dal 1915, anno in cui l’architetto viene designato a ricoprire la carica di direttore del locale ufficio Lavori Pubblici, al 1954, anno simbolico della sua nomina a cittadino onorario di Hilversum. Il lavoro di ricerca vuole individuare quelle caratteristiche formali e tipologiche, insite nei quartieri progettati dall’architetto olandese, in grado di definire una struttura urbana capace di sostenere un ragionamento architettonico indipendente dal luogo e dal tempo, un ragionamento impostato sulla definizione della forma urbis. Non desidera certo delineare un modello, vista la consapevolezza che ogni progetto ha un proprio luogo e un proprio tempo, cerca di tratteggiare, piuttosto, uno scenario possibile per il progetto urbano, capace di assurgere ad exemplum per la costruzione della città. I progetti analizzati riguardano edifici residenziali e spazi urbani per la collettività; questi rappresentano veri e propri nuclei aggregativi per la costruzione dei complessi di alloggi popolari, dei quali definiscono la scena fissa delle vicende umane. Lo studio di questi quartieri rappresenta, pertanto, il tentativo di decodificare un “modo” di comporre la città dal quale sia possibile estrapolare temi validi e di carattere generale che permettano di formalizzare una serie di utili insegnamenti, tramite i quali poter pensare alla realizzazione della stessa, nella convinzione che “la qualità del progetto consiste nella qualità dei caratteri del tema e nel loro riconoscimento nelle forme dell’architettura”.

Mémoire sur les médailles de Marinus, frappées à Philippopolis,

Half title-page: Médailles de Marinus et de Jotanianus.

Genetic analysis of complex demographic scenarios: Spatially expanding populations of the cane toad, Bufo marinus

Inferring the spatial expansion dynamics of invading species from molecular data is notoriously difficult due to the complexity of the processes involved. For these demographic scenarios, genetic data obtained from highly variable markers may be profitably combined with specific sampling schemes and information from other sources using a Bayesian approach. The geographic range of the introduced toad Bufo marinus is still expanding in eastern and northern Australia, in each case from isolates established around 1960. A large amount of demographic and historical information is available on both expansion areas. In each area, samples were collected along a transect representing populations of different ages and genotyped at 10 microsatellite loci. Five demographic models of expansion, differing in the dispersal pattern for migrants and founders and in the number of founders, were considered. Because the demographic history is complex, we used an approximate Bayesian method, based on a rejection-regression algorithm. to formally test the relative likelihoods of the five models of expansion and to infer demographic parameters. A stepwise migration-foundation model with founder events was statistically better supported than other four models in both expansion areas. Posterior distributions supported different dynamics of expansion in the studied areas. Populations in the eastern expansion area have a lower stable effective population size and have been founded by a smaller number of individuals than those in the northern expansion area. Once demographically stabilized, populations exchange a substantial number of effective migrants per generation in both expansion areas, and such exchanges are larger in northern than in eastern Australia. The effective number of migrants appears to be considerably lower than that of founders in both expansion areas. We found our inferences to be relatively robust to various assumptions on marker. demographic, and historical features. The method presented here is the only robust, model-based method available so far, which allows inferring complex population dynamics over a short time scale. It also provides the basis for investigating the interplay between population dynamics, drift, and selection in invasive species.

Testosterone secretion and pharmacological spermatozoal recovery in the cane toad (Bufo marinus)

The cane toad (Bufo marinus) was used as a model to study male anuran reproductive endocrinology and to develop a protocol for non-invasive sperm recovery. Circulating testosterone concentrations in 6-hourly samples did not vary significantly (P < 0.05) over a 24 h period although there was a tendency (P = 0.06) for testosterone to be elevated at 19:00 h relative to other times of the day, which may be related to the nocturnal activity pattern of this species. Testosterone secretion after intraperitoneal (IP) injection of either a GnRH agonist (5 mu g IP) or hCG (1000 IU) was also examined. While the GnRH agonist did not produce a significant increase above basal plasma testosterone (0.29, 95% C.I. of 0.05-1.10 ng/ml), injection of hCG resulted in an increase (P < 0.01) of plasma testosterone with peak concentrations at approximately 120 min (4.17, 95% C.I. of 2.69-7.44 ng/ml) after injection. Non-invasive pharmaceutical sperm recovery was attempted following IP injection of graded doses of GnRH agonist, hCG or FSH. Urine was collected at 3, 6 and 12 h after treatment to assess sperm quality and quantity. The optimal protocol for sperm recovery in cane toads was injection of either 1000 or 2000 IU hCG; there was no significant difference in the quality of the spermic urine samples obtained using either dose of hCG or with respect to collection time. The findings indicated that hCG can be used to assess testicular steroidogenic status and also to induce sperm recovery in the cane toad. The hCG protocols developed in this study will have application in studies on the reproductive biology of rare and endangered male anurans. (c) 2005 Elsevier B.V. All rights reserved.

Population ecology of the sea lamprey (Petromyzon marinus) as an invasive species in the Laurentian Great Lakes and an imperiled species in Europe.

The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range.

Performance of a vertical slot fish pass for the sea lamprey Petromyzon marinus L. and habitat recolonization.

In 2011, a vertical-slot fish pass was built at the Coimbra Açude-Ponte dam (Mondego River, Portugal), approximately 45 km upstream from the river mouth. The performance of this infrastructure for sea lamprey passage was evaluated between 2011 and 2015 using several complementary methodologies, namely radio telemetry [conventional and electromyogram (EMG)], passive integrated transponder (PIT) telemetry and electrofishing surveys. During the study period, the electrofishing revealed a 29-fold increase in the abundance of larval sea lamprey upstream of the fish pass. Of the 20 radio-tagged individuals released downstream from the dam, 33% managed to find and successfully surpass the obstacle in less than 2 weeks, reaching the spawning areas located in the upstream stretch of the main river and in one important tributary. Fish pass efficiency was assessed with a PIT antenna installed in the last upstream pool and revealed a 31% efficiency, with differences between and within migratory seasons. Time of day and river flow significantly influenced the attraction efficiency of the fish pass, with lampreys negotiating it mainly during the night period and when discharge was below 50m3 s_1. Sea lampreys tagged with EMG transmitters took 3 h to negotiate the fish pass, during which high muscular effort was only registered during passage, or passage attempts, of the vertical slots. The use of complementary methodologies provided a comprehensive passage evaluation for sea lamprey, a species for which there is a considerable paucity of valuable data concerning behavioural, physiological and environmental influences on obstacle negotiation.

Genetic diversity and population structure of the sea lamprey (Petromyzon marinus L.) across its distributional range

Lampreys are a group of ancient vertebrates with 360 million years of existence. Throughout their evolution, they have acquired local adaptations to the colonized habitats, showing high plasticity and adaptive capacities. The sea lamprey (Petromyzon marinus L.) is a parasitic and anadromous species that occurs in both sides of the North Atlantic. The aims of this study were to analyse, using microsatellite markers, the genetic diversity and population structure of sea lamprey throughout its distributional range. Analyses demonstrated consistent signs of high population differentiation between European and North American samples (two-groups structure), most probably due to isolation by distance, but low differentiation among populations from the same coast. The apparent lack of homing in this species is in line with its high evolutive success, as homing may bring adults back to natal habitats that have changed, or that are intermittently unfavourable. Analyses also demonstrated higher levels of genetic diversity in North American samples; DIVERSIDADE GENÉTICA E ESTRUTURA POPULACIONAL DA LAMPREIA-MARINHA (PETROMYZON MARINUS L.) AO LONGO DA SUA ÁREA DE DISTRIBUIÇÃO Resumo: As lampreias são organismos ancestrais com cerca de 360 milhões de anos de existência. No decorrer da longa escala evolutiva têm vindo a adquirir adaptações aos locais que colonizaram, tendo uma forte capacidade evolutiva e adaptativa. A lampreia-marinha (Petromyzon marinus L.) é uma espécie parasita e anádroma que ocorre em ambas as costas do Atlântico Norte. Este estudo teve como principal objetivo estudar a diversidade genética e a estrutura populacional desta espécie ao longo da sua área de distribuição, através do uso de microssatélites. Os resultados demonstraram forte divergência entre populações das costas Este e Oeste do Atlântico Norte, provavelmente devido à elevada distância entre populações, mas pouca diferenciação entre populações da mesma costa. A ausência de homing nesta espécie terá contribuído para o seu sucesso evolutivo, uma vez que o homing pode levar indivíduos a reproduzirem-se em habitats que se tornaram desfavoráveis ou intermitentemente inapropriados. Os resultados demonstraram também uma maior variabilidade genética nas populações americanas.

Relationships between blood pressure and heart rate in the saltwater crocodile Crocodylus porosus

The cardiac limb of the baroreflex loop was studied in the saltwater crocodile Crocodylus porosus, The classical pharmacological methodology using phenylephrine and sodium nitroprusside was used to trigger blood pressure changes, and the resulting alterations in heart rate were analysed quantitatively using a logistic function. Interindividual differences in resting heart rates and blood pressures were observed, but all seven animals displayed clear baroreflex responses. Atropine and sotalol greatly attenuated the response. A maximal baroreflex gain of 7.2 beats min(-1) kPa(-1) was found at a mean aortic pressure of 6.1 kPa, indicating the active role of the baroreflex in a wide pressure range encompassing hypotensive and hypertensive states. At the lowest mean aortic pressures (5.0 kPa), the synergistic role of the pulmonary-to-systemic shunt in buffering the blood pressure drop also contributes to blood pressure regulation, Pulse pressure showed a better correlation,vith heart rate and also a higher gain than mean aortic, systolic or diastolic pressures, and this is taken as an indicator of the existence of a differential control element working simultaneously with a linear proportional element.