Effect of salinity changes on the midgut gland of Artemesia longinaris (Decapoda, Penaeidae)

Abstract

ABSTRACT. The response of the midgut gland of Artemesia longinaris to salinity changes was evaluated by analyzing its histological changes. Animals were exposed gradually and abruptly to 33, 29, 25 and 16 psu for different time intervals and readapted to 33 psu for 30 days. Individuals maintained 10 days at 16 psu showed the lowest survival and presented histopathologies which were not present in those readapted to 33 psu. Shrimps abruptly transferred from 33 to 16 psu died in 3-5 h but did not show midgut gland alterations likely due to the brief exposure. Only shrimps abruptly transferred from 33 to 25 psu presented histopathologies after 96 h. When readapted to 33 psu for 30 days, the midgut gland recovered an unaltered structure. Except E-cells, which did not vary in height among treatments, F, R and B-cells were taller in animals gradually adapted to 29 than to 16 psu. Abrupt salinity changes had a significant effect on the mean height of F, R and B-cells of those animals transferred from 33 to 25 psu (from 24 to 96 h after transfer F and R-cells heights decreased, and from 96 to 144 h after transfer B-cells height increased). Our study shows the effect of osmotic stress at the tissue level on the midgut gland and, at least partially, explains the reason for the mortalities at low salinities. Keywords: midgut gland, hepatopancreas, osmotic stress, histopathology, salinity, A. longinaris, Argentina. Efecto de los cambios de salinidad sobre el hepatopáncreas deArtemesia longinaris (Decapoda, Penaeidae) RESUMEN. Se evaluó la respuesta del hepatopáncreas de Artemesia longinaris a los cambios de salinidad. Los animales fueron expuestos gradual y abruptamente a 33, 29, 25 y 16 psu durante distintos intervalos y readaptados a 33 psu por 30 días. Los individuos gradualmente adaptados a 16 psu tuvieron baja supervivencia y presentaron alteraciones histológicas ausentes en los readaptados a 33 psu. Aquellos transferidos repentinamente de 33 a 16 psu murieron en 3-5 h pero no mostraron alteraciones, posiblemente debido a la breve exposición. Sólo los transferidos repentinamente de 33 a 25 psu por más de 96 h presentaron daño tisular. Cuando se readaptaron a 33 psu durante 30 días, el hepatopáncreas mostró una estructura normal. Exceptuando las células E que no variaron en altura entre tratamientos, las F, R y B fueron más altas en los animales gradualmente adaptados de 33 a 29 psu. Los cambios súbitos de salinidad tuvieron un efecto significativo en la altura media de las células F, R y B solamente en animales transferidos de 33 a 25 psu (24 a 96 h después de la transferencia disminuyó la altura de las células F y R, y 96 a 144 h después hubo un aumento en la altura de las células B). El presente estudio muestra el efecto de los cambios de salinidad sobre el hepatopáncreas y explica, al menos parcialmente, la razón de la mortalidad a bajas salinidades.

Effect of Dietary Astaxanthin on Free Radical Scavenging Capacity and Nitrite Stress Tolerance of Postlarvae Shrimp, Pleoticus muelleri

“…muelleri was a pathological feature observed with all nitrite concentrations tested. This alteration was also observed in marine crustaceans acclimatized to low salinities, such as Artemesia longinaris and P. muelleri, and freshwater prawn Palaemonetes argentinus under hypersaline conditions .…”

“…In the present work, degenerative desquamation of the tubular epithelium in the midgut gland of P. muelleri was a pathological feature observed with all nitrite concentrations tested. This alteration was also observed in marine crustaceans acclimatized to low salinities, such as Artemesia longinaris 32 and P. muelleri, 33 and freshwater prawn Palaemonetes argentinus under hypersaline conditions. 34 The increased desquamation produced by different stressors resulted in a high rate of cell loss that does not make possible the restitution of the damage tissue.…”

Use of computer‐assisted image analysis for semi‐quantitative histology of the hepatopancreas in whiteleg shrimp Penaeus vannamei (Boone)

“…Morphological alterations of the HP, such as reduction in the tubular area and enlargement of the lumen area, variation in the number of B‐cells, F‐cells and R‐cells, infiltration of haemocytes in the intertubular spaces, have been described by different authors in case of pathogens, food deprivation, changes in salinity and food ingredients (Nakamura ; Sánchez‐Paz et al . ; Tam & Avenant‐Oldewage ; Diaz, Sousa & Petriella ; Masson, Diaz & Petriella ; Sacristán et al . ).…”