Influence of 17β-oestradiol (E2) and 17α-hydroxyprogesterone (OHP) on ovarian maturation in Penaeus semisulcatus De Haan, 1844 (Decapoda, Dendrobranchiata, Penaeidae) from the Mediterranean Sea off Alexandria, Egypt

This study searches to provide appropriate conditions to trigger spawning in Penaeus semisulcatus in aquaculture. The aim was to test the effect of 17β-oestradiol and 17α-hydroxyprogesterone on ovarian maturation and to study the correlation between the different stages of ovarian maturation and hormonal levels in the ovaries, hepatopancreas, and haemolymph. Female shrimps were collected from Ras El-Tin beach and the fishing port to Abu Qir Bay of the Mediterranean Sea off Alexandria, Egypt from June 2018-August 2019. Shrimps were individually weighed and subsequently killed by thermal shock at a maximum temperature of 45°C. Gonadosomatic and hepatosomatic indices were calculated. The correlation between the gonadosomatic and hepatosomatic indices indicates the presence of endogenous and exogenous vitellogenesis. The haemolymph, hepatopancreas, and ovaries were studied by stereo- and electron microscopy. From 15 females in each season the mentioned tissues were isolated for the extraction and quantification of steroid hormones during the different stages of gonadal maturation using radioimmunoassay. An ecdysteroid- and steroid-extraction protocol was applied. Aliquots were collected from the haemolymph to identify 17β-oestradiol and 17α-hydroxyprogesterone by mass spectrometry. Five stages of gonadal maturation were observed. The hepatopancreas was formed by a set of tubules lined with pseudostratified epithelium composed of five cell types, cell E (undifferentiated), cell F (fibrillar), cell B (vesicular), R (reabsorbing), and M (basal) cells. Steroidogenic tissues were small in size and numerous. The ultrastructure of the ovary and hepatopancreas were studied during oocyte development. There was a high concentration of 17β-oestradiol and 17α-hydroxyprogesterone in stages I and II of ovarian maturation, coinciding with the preparation phase for vitellogenesis. A progressive decrease of these steroid hormones occurred during the course of gonadal maturation, and reached its lowest concentration in the spawning period. The ecdysone concentration did not fluctuate in ripe females. Its level increases from stages I-IV of vitellogenesis onward.

A Comparative Survey on Antioxidant Activity of Iranian Shrimp Waste [Penaeus Semisulcatus] and Synthetic Antioxidants

Shrimp waste, as an important source of natural carotenoids, is produced in large quantities in seafood processing industry. One of the important characteristics of carotenoids is their ability to act as antioxidants, thus protecting cells and tissues from damaging effects of free radicals and singlet oxygen. The aim of this study was to find effective method for carotenoid extraction [Enzymatic and alkaline treatment] from shrimp waste and compare their antioxidant potential with synthetic antioxidants butylated hydroxyanisole [BHA] and butylated hydroxytoluene [BHT] using sunflower oil. The sunflower oil was exposed to three concentration of extracted carotenoid [470, 235 and 118 mg/kg] and synthetic antioxidants. The inhibition of lipid peroxidation was evaluated for Malondialdehyde and peroxide value. The mean values of carotenoid extract were 243 and 170 mg/kg for enzymatic and alkaline treatment, respectively. So the highest efficacy of carotenoid extraction was obtained from enzymatic extraction. The oil samples containing 470 ppm carotenoid, which extracted by alcalase as the default treatment, exhibited the less peroxide value and higher antioxidant potential than the oil samples containing synthetic antioxidants. According to the results, the synthetic antioxidants can be replaced by extracted carotenoids from shrimp waste as a natural antioxidant to inhibit oxidation.