Response of mucous cells of the gills of traíra (Hoplias malabaricus) and jeju (Hoplerythrinus unitaeniatus) (Teleostei: Erythrinidae) to hypo- and hyper-osmotic ion stress

The mucous cells (MC) of traíra, Hoplias malabaricus, and jeju, Hoplerythrinus unitaeniatus, two ecologically distinct erythrinid species, were analyzed in fish exposed to deionized (DW) and high ion concentration (NaCl and Ca2+) water (HIW) during 15 days to evaluate the MC responses to ion challenge. MCs are localized in the leading and trailing edge and, interlamellar region of the gill filament epithelium but, in H. unitaeniatus, they are also found in the breathing or lamellar epithelium. MC density is lower in H. malabaricus, the exclusively water-breathing fish, than in H. unitaeniatus, a facultative air-breathing fish. The transference to DW or HIW did not change the MC density and surface area, excepting in H. malabaricus, in the first day of exposure to DW. A single MC containing three types of glycoproteins (neutral, acidic and sulphated) was identified in the gill epithelium of both, H. malabaricus and H. unitaeniatus. The amount (based on the intensity of histochemistry reaction) of these glycoproteins differed between the species and were altered after exposure to DW and HIW showing little adjustments in the amount of mucosubstances in the MC of H. malabaricus and reduction of acidic and sulphated glycoproteins in H. unitaeniatus. The decreasing of these glycoproteins in H. unitaeniatus reduced the mucus protection against desiccation of gill tissue when change the ion concentration in water.(AU)

As células mucosas (CM) em traíra, Hoplias malabaricus, e jeju, Hoplerythrinus unitaeniatus, dois eritrinídeos ecologicamente distintos, foram analisadas em espécimes expostos a água deionizada (DW) e água com alta concentração de íons (NaCl + Ca2+, HIW) durante 15 dias para avaliar as respostas das CMs. As CMs estão localizadas no lado aferente e eferente e região interlamelar no epitélio do filamento branquial, mas em H. unitaeniatus, CMs estão presentes no epitélio respiratório ou lamelar. A densidade de CMs é menor em H. malabaricus, espécie com respiração exclusivamente aquática, do que em H. unitaeniatus, espécie com respiração aérea facultativa. A transferência para AD e HIW não alterou a densidade de CMs e a sua superfície, exceto em H. malabaricus, no primeiro dia de exposição à AD. Um único tipo de CM contendo três tipos de glicoproteínas (neutra, ácida e ácida sulfatada) foi identificado no epitélio branquial de H. malabaricus e H. unitaeniatus. A quantidade das glicoproteínas (avaliada pela intensidade da reação histoquímica) diferiu nas duas espécies e foi alterada após a transferência para AD e HIW mostrando pequeno ajuste na quantidade de cada mucosubstância secretada pelas CMs em H. malabaricus e redução de glicoproteínas ácidas e sulfatadas em H. unitaeniatus. A diminuição dessas glicoproteínas em H. unitaeniatus reduz a proteção do muco sobre o tecido branquial quando é alterada a concentração de íons na da água.(AU)

Response of mucous cells of the gills of traíra (Hoplias malabaricus) and jeju (Hoplerythrinus unitaeniatus) (Teleostei: Erythrinidae) to hypo- and hyper-osmotic ion stress

The mucous cells (MC) of traíra, Hoplias malabaricus, and jeju, Hoplerythrinus unitaeniatus, two ecologically distinct erythrinid species, were analyzed in fish exposed to deionized (DW) and high ion concentration (NaCl and Ca2+) water (HIW) during 15 days to evaluate the MC responses to ion challenge. MCs are localized in the leading and trailing edge and, interlamellar region of the gill filament epithelium but, in H. unitaeniatus, they are also found in the breathing or lamellar epithelium. MC density is lower in H. malabaricus, the exclusively water-breathing fish, than in H. unitaeniatus, a facultative air-breathing fish. The transference to DW or HIW did not change the MC density and surface area, excepting in H. malabaricus, in the first day of exposure to DW. A single MC containing three types of glycoproteins (neutral, acidic and sulphated) was identified in the gill epithelium of both, H. malabaricus and H. unitaeniatus. The amount (based on the intensity of histochemistry reaction) of these glycoproteins differed between the species and were altered after exposure to DW and HIW showing little adjustments in the amount of mucosubstances in the MC of H. malabaricus and reduction of acidic and sulphated glycoproteins in H. unitaeniatus. The decreasing of these glycoproteins in H. unitaeniatus reduced the mucus protection against desiccation of gill tissue when change the ion concentration in water.(AU)

As células mucosas (CM) em traíra, Hoplias malabaricus, e jeju, Hoplerythrinus unitaeniatus, dois eritrinídeos ecologicamente distintos, foram analisadas em espécimes expostos a água deionizada (DW) e água com alta concentração de íons (NaCl + Ca2+, HIW) durante 15 dias para avaliar as respostas das CMs. As CMs estão localizadas no lado aferente e eferente e região interlamelar no epitélio do filamento branquial, mas em H. unitaeniatus, CMs estão presentes no epitélio respiratório ou lamelar. A densidade de CMs é menor em H. malabaricus, espécie com respiração exclusivamente aquática, do que em H. unitaeniatus, espécie com respiração aérea facultativa. A transferência para AD e HIW não alterou a densidade de CMs e a sua superfície, exceto em H. malabaricus, no primeiro dia de exposição à AD. Um único tipo de CM contendo três tipos de glicoproteínas (neutra, ácida e ácida sulfatada) foi identificado no epitélio branquial de H. malabaricus e H. unitaeniatus. A quantidade das glicoproteínas (avaliada pela intensidade da reação histoquímica) diferiu nas duas espécies e foi alterada após a transferência para AD e HIW mostrando pequeno ajuste na quantidade de cada mucosubstância secretada pelas CMs em H. malabaricus e redução de glicoproteínas ácidas e sulfatadas em H. unitaeniatus. A diminuição dessas glicoproteínas em H. unitaeniatus reduz a proteção do muco sobre o tecido branquial quando é alterada a concentração de íons na da água.(AU)

Alterations on growth and gill morphology of Danio rerio (Pisces, Ciprinidae) exposed to the toxic sediments

The objective of this work was to assess the toxicity of sediment samples from six cascade reservoirs in Tietê river system, in Säo Paulo State, Brazil, through chronic-partial toxicity bioassays with Danio rerio larvae as test-organisms. Histology of gills and biometric measurements were used to determine the existence of toxicity problems. The alterations on gill morphology here detected were considered of first stage (hyperplasia, lamellar junction and excess of mucous cells) in the first reservoirs and very slight in the last ones. The biometric analysis pointed to inadequate conditions for the growth of the test-organisms when exposed to the sediment of the rivers and upstream reservoirs and also indicated an improvement of environmental conditions along the system

Chloride cell responses to ion challenge in two tropical freshwater fish, the erythrinids Hoplias malabaricus and Hoplerythrinus unitaeniatus.

Chloride cell (CC) responses to ion challenge and plasma ion concentration were evaluated in two ecologically distinct erythrinids, Hoplias malabaricus, an exclusively water-breathing species, and Hoplerythrinus unitaeniatus, a facultative air-breathing fish, at one, two, seven, and 15 days of exposure to deionized water and to ion-rich water. H. malabaricus displayed high CC proliferation on filament and lamellar epithelium during exposure to deionized water and significant CC proliferation in the filament epithelium on the first day of exposure to water rich in NaCl and Ca2+ and in the lamellar epithelium on the first, second, and seventh day of exposure to such water. CC proliferation in H. unitaeniatus occurred only in the lamellar epithelium of fish exposed to deionized water. CC proliferation on both species was not accompanied by significant increase of CC density in contact with the external medium. The increase in the CC fractional area (CCFA) resulted from the increase of individual CC apical surface area on the first and second days of exposure to deionized water in H. malabaricus and only on the first day in H. unitaeniatus. Plasma ions in both erythrinid species showed transitory changes and, on the fifteenth day of exposure to the two types of experimental water, the plasma ion concentration was similar to the control fish. The CC responses of these erythrinid fish showed that CC proliferation depends on previous CC density in the gill and is not related solely to exposure to ion-poor water. Furthermore, CC proliferation in gill epithelium did not always involve an increase of CC density in contact with the external medium.