Índices Parasitários de Brevimulticaecum sp. (Nematoda: Heterocheilidae) Em Potamotrygon motoro (Chondrichthyes: Potamotrygonidae) Capturados no Arquipélago do Bailique, Macapá

O número de nematódeos descritos em elasmobrânquios é relativamente pequeno, sendo encontrados majoritariamente no trato digestório. Apesar de alguns relatos descritos, a literatura a respeito ainda é considerada escassa principalmente sobre a associação parasita-hospedeiro. Diante disso, o objetivo deste trabalho foi avaliar os índices parasitários de larvas Brevimulticaecum sp. na válvula espiral de Potamotrygon motoro provenientes do arquipélago do Bailique, em Macapá no estado do Amapá, Brasil. Registrou-se em 20,41% das raias coletadas a presença de larvas de Brevimulticaecum sp., sendo a intensidade média de 20,10 larvas/peixe e a abundância média de 4,10. São poucos os registros deste parasito em peixes no Brasil, sendo que já foi relatada sua ocorrência no estômago de P. motoro e Potamotrygon falkneri. As diferenças entre os parâmetros parasitários podem ser um indicador de alimentação e/ou diferenças comportamentais entre os sexos. Este é o primeiro estudo sobre nematóides de potamotrigonídeos na região Norte, ampliando o conhecimento da biodiversidade desta região. Palavras-chave: Helmintos. Nematoda; Elasmobrânquio. Válvula Espiral. Abstract The number of nematodes described in elasmobranchs is relatively small, being found mostly in the digestive tract. Despite some reports described, the literature on this subject is still considered scarce, mainly on the parasite-host association. Therefore, the objective of this work was to evaluate the parasitic indices of Brevimulticaecum sp. the Potamotrygon motoro spiral valve from the Bailique archipelago, in Macapá in the state of Amapá, Brazil. Larvae of Brevimulticaecum sp. Were recorded in 20.41% of the rays collected, with an average intensity of 20.10 larvae / fish and an average abundance of 4.10. There are few records of this parasite in fish in Brazil, and its occurrence in the stomach of P. motoro and Potamotrygon falkneri has been reported. Differences between parasitic parameters can be an indicator of diet and / or behavioral differences between genders. This is the first study on potamotrigonid nematodes in the North, expanding knowledge of this region's biodiversity. Keywords: Helminths. Nematoda. Elasmobranchs. Spiral Valve.

Design and evaluation of a novel anti-reflux biliary stent with cone spiral valve

Endoscopic placement of biliary stent is a well-established palliative treatment for biliary obstruction. However, duodenobiliary reflux after stent placement has been a common problem which may lead to dreadful complications. This paper designed a novel anti-reflux biliary stent with a cone spiral valve. Fluid-Structure Interaction (FSI) simulations were established to evaluate the efficiency of the anti-reflux stent comparing with a clinically applied standard stent. According to the stress distribution of the valve, the fatigue performance in the stress concentration area was analyzed. The results show that when the antegrade flow through the valve, the cone spiral valve could stretch and open to realize adequate drainage under the normal physiological pressure of biliary tract; When the duodenal reflux through the valve, the valve would be compressed and close with a result of nearly zero at the outlet flow rate. Furthermore, the anti-reflux stent achieved improved radial mechanical performance with 2.7 times higher radial stiffness than standard stent. Finite element analysis (FEA) also indicates that compared with the standard stent, the addition of the anti-reflux valve had little negative effect on flexibility of the stent. Fatigue analysis results showed that the valve was reliable. This research provides the new stent with a cone spiral valve and proves that it is technically feasible and effective for preventing the duodenobiliary reflux while ensuring the antegrade bile flow without compromising the other biomechanical performances.

Food procurement and processing

Fish display a wide range of adaptations of the mouth and pharynx for specific feeding patterns including planktivory, fin-biting, picking and scraping. Appetite control is complex, involving stimulatory and inhibitory hormones. The gut has a linear plan similar to other vertebrates but with considerable variation between taxa, and a stomach may be absent. Many bony fish possess pyloric caeca, containing digestive enzymes, and may increase surface area for digestion. In chondrichthyes (sharks, etc.), a ‘spiral valve’ increases surface area of the intestine. Smooth muscle contractions in the gut wall pass food along the tract under control of food pressure, the autonomic nervous system and specific peptides. Digestion by hydrolytic enzymes, and absorption occur in the intestine, monomers produced being absorbed mainly through transcellular routes, involving enterocytes, into the blood of the hepatic portal vein to the liver. Dietary requirements and nutrition are discussed.

Etmopterus lailae sp. nov., a new lanternshark (Squaliformes: Etmopteridae) from the Northwestern Hawaiian Islands

A new species of lanternshark, Etmopterus lailae (Squaliformes: Etmopteridae), is described from the Northwestern Hawaiian Islands, in the central North Pacific Ocean. The new species resembles other members of the “Etmopterus lucifer” clade in having linear rows of dermal denticles, and most closely resembles E. lucifer from Japan. The new species occurs along insular slopes around seamounts at depths between 314–384 m. It can be distinguished from other members of the E. lucifer clade by a combination of characteristics, including a longer anterior flank marking branch, arrangement of dermal denticles on the ventral snout surface and body, flank and caudal markings, and meristic counts including number of spiral valve turns, and precaudal vertebrate. A key to species of the Etmopterus lucifer-clade is included.