Composição de desembarque, conhecimento tradicional e risco de extinção: a captura de elasmobrânquios do estado da Paraíba, Brasil

Tese de mestrado em Ecologia Marinha, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

Fishery and biology of deep-sea chondrichthyans off the southwest coast of india

Elasmobranchs comprising sharks, skates and rays have traditionally formed an important fishery along the Indian coast. Since 2000, Indian shark fishermen are shifting their fishing operations to deeper/oceanic waters by conducting multi-day fishing trips, which has resulted in considerable changes in the species composition of the landings vis- a-vis those reported during the 1980’s and 1990’s. A case study at Cochin Fisheries Harbour (CFH), southwest coast of India during 2008-09 indicated that besides the existing gillnet–cum- hooks & line and longline fishery for sharks, a targeted fishery at depths >300-1000 m for gulper sharks (Centrophorus spp.) has emerged. In 2008, the chondrichthyan landings (excluding batoids) were mainly constituted by offshore and deep-sea species such as Alopias superciliosus (24.2%), Carcharhinus limbatus (21.1%), Echinorhinus brucus (8.2%), Galeocerdo cuvier (5.4%), Centrophorus spp. (7.3%) and Neoharriotta pinnata (4.2%) while the contribution by the coastal species such as Sphyrna lewini (14.8%), Carcharhinus sorrah (1.4%) and other Carcharhinus spp. has reduced. Several deep-sea sharks previously not recorded in the landings at Cochin were also observed during 2008-09. It includes Hexanchus griseus, Deania profundorum, Zameus squamulosus and Pygmy false catshark (undescribed) which have been reported for the first time from Indian waters. Life history characteristics of the major fished species are discussed in relation to the fishery and its possible impacts on the resource

Extremely high conservation in the untranslated Region as well as the coding region of CNP mRNAs throughout elasmobranch species

C-type natriuretic peptide (CNP) is a crucial osmoregulatory hormone in elasmobranchs, participating in salt secretion and drinking. In contrast to teleosts and tetrapods in which the NP family is composed of a group of structurally related peptides, we have shown that CNP is the sole NP in sharks. In the present study, CNP cDNAs were cloned from four species of batoids, another group of elasmobranchs. The cloned batoid CNP precursors contained a plausible mature peptide of 22 amino acid residues that is identical to most shark CNP-22s, but five successive amino acids were consistently deleted in the prosegment compared with shark precursors, supporting the diphyletic classification of sharks and rays. In addition, molecular phylogenetic trees of CNP precursors were consistent with a diphyletic interpretation. Except for the deletion, the nucleotide and deduced amino acid sequences of the CNP cDNAs are extremely well-conserved among all elasmobranch species, even between sharks and rays. Surprisingly, high conservation is evident not only for the coding region, but also for the untranslated regions. It is most likely that the high conservation is due to the low nucleotide substitution rate in the elasmobranch genome, and high selection pressure. The 3′-untranslated region of the elasmobranch CNP cDNAs contained three to six repeats of the ATTTA motif that is associated with the regulation of mRNA stability and translation efficiency. Alternative polyadenylation sites were also found; the long 3′-untranslated region contains a core of ATTTA motifs while the short form has only one or no ATTTA motif, indicating that the post-transcriptional modification of mRNA is important for regulation of CNP synthesis. These characteristics in the 3′-untranslated region were conserved among all elasmobranch CNP cDNAs. Since CNP has been implicated as a fast-acting hormone to facilitate salt secretion from the rectal gland, the conserved 3′-untranslated region most likely contributes to rapid regulation of CNP synthesis in elasmobranchs in response to acute changes in internal and external environments.

Osmoregulation in elephant fish Callorhinchus Milii (Holocephali), with special reference to the rectal gland

Osmoregulatory mechanisms in holocephalan fishes are poorly understood except that these fish are known to conduct urea-based osmoregulation as in elasmobranchs. We, therefore, examined changes in plasma parameters of elephant fish Callorhinchus milii, after gradual transfer to concentrated (120%) or diluted (80%) seawater (SW). In control fish, plasma Na and urea concentrations were about 300 mmol l^–1 and 450 mmol l^–1, respectively. These values were equivalent to those of sharks and rays, but the plasma urea concentration of elephant fish was considerably higher than that reported for chimaeras, another holocephalan. After transfer to 120% SW, plasma osmolality, urea and ion concentrations were increased, whereas transfer to 80% SW resulted in a fall in these parameters. The rises in ion concentrations were notable after transfer to 120% SW, whereas urea concentration decreased predominantly following transfer to 80% SW. In elephant fish, we could not find a discrete rectal gland. Instead, approximately 10 tubular structures were located in the wall of post-valvular intestine. Each tubular structure was composed of a putative salt-secreting component consisting of a single-layered columnar epithelium, which was stained with an anti-Na⁺,K⁺-ATPase serum. Furthermore, Na⁺,K⁺-ATPase activity in the tubular structures was significantly increased after acute transfer of fish to concentrated SW (115%). These results suggest that the tubular structures are a rectal gland equivalent, functioning as a salt-secreting organ. Since the rectal gland of elephant fish is well developed compared to that of Southern chimaera, the salt-secreting ability may be higher in elephant fish than chimaeras, which may account for the lower plasma NaCl concentration in elephant fish compared to other chimaeras. Since elephant fish have also attracted attention from a viewpoint of genome science, the availability of fish for physiological studies will make this species an excellent model in holocephalan fish group.

Immunolocalization of Na+/K+-ATPase, carbonic anhydrase II, and vacuolar H+-ATPase in the gills of freshwater adult lampreys, Geotria australis

As adults, anadromous lampreys migrate from seawater into freshwater rivers, where they require branchial ion (NaCl) absorption for osmoregulation. In teleosts and elasmobranchs, pharmological, immunohistochemical, and molecular data support roles for Na⁺/K⁺-ATPase (NPPase), carbonic anhydrase II (CAII), and vacuolar H⁺-ATPase (V-ATPase) in two different models of branchial ion absorption. To our knowledge, these transport-related proteins have not been studied in adult freshwater lampreys, and therefore it is not known if they are expressed, or have similar functions, in lampreys. The purpose of this study was to localize NPPase, CAII, and V-ATPase in the gills of adult freshwater lampreys and determine if any of these transport-related proteins are expressed in the same cells. Heterologous antibodies were used to localize the three proteins in gill tissue from pouched lamprey (Geotria australis). Immunoreactivity (IR) for all three proteins occurred between, and at the base of, lamellae in cells that match previous descriptions of mitochondrion-rich-cells (MRCs). NPPase-IR was always on the basolateral side of cells that did not stain for CAII or V-ATPase. In contrast, CAII-IR was always on the apical side of cells that also contained diffuse V-ATPase-IR. Therefore, we have identified two types of MRC in adult freshwater lamprey gills based on immunohistochemical staining for three transport proteins. A model of ion transport, based on our results, is proposed for adult freshwater lampreys. 

Osmoregulation in elephant fish, CALLORHYNCHUS MILLII (HOLOCEPHALI)

Osmoregulatory mechanisms in holocephalan fishes are unknown except that they conduct urea-based osmoregulation as in elasmobranchs. We, therefore, examined changes in plasma parameters of elephant fish, Callorhynchus millii, after gradual transfer to concentrated (120%) or diluted (80%) seawater (SW). In control fish, plasma Na and urea concentrations were about 300mM and 450mM, respectively. These values were equivalent to those of sharks and rays, but the plasma urea concentration of elephant fish was considerably higher than that reported for chimaeras, another holocephalan. After transfer to 120% SW, the plasma Na concentration markedly increased, while a conspicuous decrease in plasmaurea concentration was observed following transfer to 80% SW. In elephant fish, we could not find a discrete rectal gland. Instead, approximately 10 tubular structures were located in the wall of post-valvular intestine. Each tubular structure was composed of a putative salt-secreting component consisting of a single-layered columnar epithelium, which was stained with anti-Na+,K±ATPase serum. It is most likely that the tubular structures in the posterior intestine represent a primitive form of the rectal gland in elephant fish. In addition, we have identified two C-type natriuretic peptides (CNPs) from the heart and brain of elephant fish, which may contribute to the control of NaCl excretion from the rectal gland of elephant fish as it does in elasmobranchs.

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

In marine cartilaginous fish, reabsorption of filtered urea by the kidney is essential for retaining a large amount of urea in their body. However, the mechanism for urea reabsorption is poorly understood due to the complexity of the kidney. To address this problem, we focused on elephant fish (Callorhinchus milii) for which a genome database is available, and conducted molecular mapping of membrane transporters along the different segments of the nephron. Basically, the nephron architecture of elephant fish was similar to that described for elasmobranch nephrons, but some unique features were observed. The late distal tubule (LDT), which corresponded to the fourth loop of the nephron, ran straight near the renal corpuscle, while it was convoluted around the tip of the loop. The ascending and descending limbs of the straight portion were closely apposed to each other and were arranged in a countercurrent fashion. The convoluted portion of LDT was tightly packed and enveloped by the larger convolution of the second loop that originated from the same renal corpuscle. In situ hybridization analysis demonstrated that co-localization of Na(+),K(+),2Cl(-) cotransporter 2 and Na(+)/K(+)-ATPase α1 subunit was observed in the early distal tubule and the posterior part of LDT, indicating the existence of two separate diluting segments. The diluting segments most likely facilitate NaCl absorption and thereby water reabsorption to elevate urea concentration in the filtrate, and subsequently contribute to efficient urea reabsorption in the final segment of the nephron, the collecting tubule, where urea transporter-1 was intensely localized.

Arraias em rios da região Sudeste do Brasil: locais de ocorrência e impactos sobre a população

INTRODUÇÃO: No presente trabalho objetivamos descrever o processo de colonização da Bacia do Alto Paraná, Sudeste do Brasil, por arraias, demonstrando sua atual situação e provável tendência, os impactos gerados e discutindo algumas ações de manejo e medidas mitigadoras. MÉTODOS: Foram realizadas entrevistas com ribeirinhos e profissionais de saúde para o levantamento de informações sobre a ocorrência de arraias e acidentes associados a estes animais, além de coletas e observações subaquáticas de potamotrigonídeos, entre 2004 e 2009, em localidades situadas nos Estados de São Paulo, Paraná e Mato Grosso do Sul, no Sudeste, Sul e parte do Centro-Oeste do Brasil. RESULTADOS: Três espécies de arraias foram identificadas na área de estudo, demonstrando utilizar os caminhos abertos pela Hidrovia Tietê-Paraná para se dispersarem. Dezesseis vítimas de acidentes envolvendo esses animais foram encontradas, notadamente banhistas e pescadores, chamando a atenção pelo fato dos casos não serem notificados e apresentarem elevada morbidade, com marcante incapacidade temporária para o trabalho. CONCLUSÕES: Este é o primeiro relato de invasão biológica envolvendo espécies de elasmobrânquios conhecido na literatura e, pelas arraias estarem colonizando áreas densamente povoadas e ampliando sua área de distribuição a cada ano, é de se esperar que sua interação negativa com humanos se intensifique, provocando alterações importantes no perfil epidemiológico dos acidentes por animais peçonhentos ocorridos no sudeste brasileiro.

Species delimitation in sharpnose sharks (genus Rhizoprionodon) in the western Atlantic Ocean using mitochondrial DNA

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular organization of 5S rDNA in sharks of the genus Rhizoprionodon: insights into the evolutionary dynamics of 5S rDNA in vertebrate genomes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative study on extracts from the tissue covering the stingers of freshwater (Potamotrygon falkneri) and marine (Dasyatis guttata) stingrays

Stingrays are elasmobranchs found along the seacoast and in some rivers of Brazil. Pain is the most conspicuous symptom observed in patients wounded by the bilaterally retroserrate stingers located in the tail, which are covered by glandular and integument tissues. In addition, cutaneous necrosis is commonly observed in injuries caused by freshwater stingrays. The aim of this work was to characterize and compare certain properties of tissue extracts obtained from the glandular tissues covering the stinger apparatus of Potamotrygon falkneri and Dasyatis guttata stingrays. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), tissue extracts have similar bands above 80kDa, but most differences were observed below this molecular mass. Lethal, dermonecrotic and myotoxic activities were detected only in P. falkneri tissue extract. Edematogenic activity was similar and dose dependent in both tissue extracts. Nociceptive activity was verified in both tissue extracts, but P. falkneri presented a two-fold higher activity than D. guttata tissue extract. No direct hemolysis, phospholipase A(2) and coagulant activities were observed in both tissue extracts. Antigenic cross-reactivity was noticed by ELISA and Western blotting, using antisera raised in rabbits. Species-specific sera reacted with several components of both tissue extracts, noticeably above 22 kDa. Both tissue extracts presented gelatinolytic, caseinolytic and fibrinogenolytic activities, which were not caused by the action of metalloproteinases. Hyaluronidase activity was detected only in P. falkneri tissue extract. Our experimental observations suggest that P. falkneri tissue extract is more toxic than D. guttata tissue extract. These results may explain why injuries caused by freshwater stingrays are more severe in human accidents. (c) 2007 Elsevier Ltd. All rights reserved.

Registro de ocorrência de duas espécies de potamotrigonídeos na região do Alto Rio Paraná e algumas considerações sobre sua biologia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The reproductive hiology and cycle of Rioraja agassizi (Muller and Henle, 1841) (Chondrichthyes : Rajidae) in southeastern Brazil, SW Atlantic Ocean

Specimens of Rioraja agassizi were collected Lit Guaruja pier, São Paulo State, Brazil, from March 2005 to March 2006. A total of: 275 males were captured. Based on the analysis of the clasper length, gonad weight, clasper gland length, alar thorns and lobule diameter, the size-at-maturity was estimated to be 32 cm. There were 1049 females in the record. Size-at-maturity was calculated in 40 cm. Sexual resting females were observed. Gonadosomatic and hepatosomatic indexes varied significantly in both sexes throughout the year. However, ovulation, egg-laying and presence of sperm in the seminal vesicle were observed all year round. For this reason, an annual cycle with at least one peak in the sexual activity is proposed for this species.

Age and growth of the Scalloped Hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Size at maturity of Atlantoraja platana (Gunther, 1880) (Chondrichthyes : Rajidae : Arhynchobatinae) in the south-west Atlantic Ocean

The sexual development of Atlantoraja platana from the south-west Atlantic Ocean was analysed. According to the reproductive variables considered for both sexes, males were found to mature at 620 mm and females at 715 mm total length. (c) 2008 The Authors Journal compilation (c) 2008 The Fisheries Society of the British Isles.