Assessment of “discreet” vertebral abnormalities, bone mineralization and bone compactness in farmed rainbow trout

The present study aimed to evaluate the importance of “discreet” vertebral abnormalities in normally-shaped rainbow trout in relation to vertebral bone condition in French fish farms. A total of 373 trout (262 ± 2 mm in total length) from 20 fish farms sampled were studied. The fish were radiographed and the axial skeleton examined for vertebral abnormalities. Vertebrae from the middle axial region (V32-38) were selected to evaluate vertebral bone condition. Bone mineralization (BM, %) was estimated by the ratio of ash and dry weight. Bone compactness (BC,%) was measured using Bone Profiler 3.23 images software on digitized radiographs of transverse sections (125 ± 10 μm). Statistical analyses were performed to test the relationships between the occurrence of vertebral abnormalities, and BM and BC. The occurrence of affected trout ranged from 0 to 55% depending on the farm. Trout displayed vertebrae with low BM (< 54.6%) and low BC (< 28.1%) in 40% and 55% of the farm, respectively. No relationships were observed between bone condition parameters (BM, BC) and the occurrence of vertebral abnormalities. These results could be explained by a wide and variable plastic response of bone characters (i.e., vertebral abnormalities, BM and BC) to the various rearing conditions in the fish farms sampled.     

Effects of ingested 20-hydroxyecdysone on development and midgut epithelial cells of Plodia interpunctella (Lepidoptera, Pyralidae)

We describe the effects of ingested 20-hydroxyecdysone on larvae of Plodia interpunctella. It caused significant mortality and provoked cannibalism between larvae. On the other hand, it also induced precocious pupation and adult emergence. A large weight loss of larvae was recorded. Besides, 20-hydroxyecdysone provoked a reduction in protein, glycogen and lipid contents. Using electron microscopy, we have shown that 20-hydroxyecdysone caused a dose-dependent severe cytotoxicity on the midgut epithelial cells, resulting in the disorganization and the vacuolization of the cytoplasm; the nucleus appeared with crenulated envelope and presented many clear areas between the chromatin clumps and finally, the disruption of microvilli and the rupture of the plasma membrane led to the shedding of cytoplasm contents into the midgut lumen. In conclusion, ingested 20-hydroxyecdysone shows potent growth disruptive effects on P. interpunctella.     

Seasonal Variations in Proximate and Fatty Acid Composition of Viscera of Sardinella aurita,Sarpa salpa,and Sepia officinalis from Tunisia

Seasonal variations of the proximate composition and fatty acid profiles in viscera from Sardinella aurita, Sarpa salpa, and Sepia officinalis were studied. Significant seasonal variations were observed in the amounts of moisture, lipid, protein, and ash between species. Viscera protein content undergoes large fluctuations. This tendency is different from results observed for the edible parts or for the whole body of many marine species. Ash content also showed significant differences. Lipid contents varied with seasons, in a proportionally inverse manner to water contents. Fatty acid composition showed significant differences from October to December. Interestingly, the highest total omega-3 contents were comparable to many commercial marine fish oils.     

Bioinsecticidal effect of harmaline on Plodia interpunctella development (Lepidoptera: Pyralidae)

We have investigated the effects of harmaline, a plant secondary metabolic compound belonging to β-carboline alkaloids, on the 4th instar larvae of Plodia interpunctella (Lepidoptera). When incorporated into the diet, harmaline caused weight loss of larvae with a reduction in protein and glycogen contents and an inhibition of α-amylase activity. Using electron microscopy, we showed that harmaline provoked a severe cytotoxicity on the epithelial cells of the midgut resulting in marked vacuolization of the cytoplasm, appearance of numerous autophagic vesicles and lysosomic structures, fragmentation of rough endoplasmic reticulum cisternae, disruption of microvilli, rupture of the plasma membrane leading to shedding of the cytoplasm contents into the midgut lumen. The development of larvae to the pupal and adult stages was prevented and high mortality was recorded.