Variation in selected unsaturated fatty acids during vitellogenesis in the Florida freshwater crayfishProcambarus paeninsulanus

Fatty Acids in the Eggs of Red King Crabs from the Barents Sea

The red king crab, Paralithodes camtschaticus, was introduced into the Barents Sea where, after a period of 30 years of adaptation, it has established a new population. This population has been commercially exploited over the past two decades, supporting profitable fisheries in both Russia and Norway. Biochemical studies aimed at assessing fatty acid profiles have been conducted, focusing primarily on the edible parts of red king crabs. Only recently have by-products been included in this research. Capture of female red king crabs is prohibited in Russia but is allowed in Norway. The fatty acids of the egg masses carried by these females have not yet been studied. To fill this knowledge gap, we assayed the fatty acid composition of eggs using gas-liquid chromatography. Our results showed a predominance of polyunsaturated fatty acids, while the concentrations of saturated and monounsaturated fatty acids were similar. Multivariate comparisons showed no significant differences in fatty acid profiles in terms of egg developmental stage (nauplius vs. metanauplius), habitat conditions (soft vs. hard bottoms), female size class, or number of autotomized limbs. However, individual comparisons showed some differences in fatty acids, the most important being the lower content of docosahexaenoic acid in eggs at the metanauplius stage compared to eggs at the nauplius stage, which is likely due to its essential role in the development of red king crab embryos. The total fatty acid content (53.94 mg g-1) was 2-87 times higher in eggs than in other red king crab tissues, confirming the critical role that fatty acids play in maintaining physiological processes during vitellogenesis. The high content of essential fatty acids and an optimal omega-3-to-omega-6 ratio (4.9) suggest that red king crab eggs are a good product for a healthy diet and a valuable source for extracting essential fatty acids.

Transcriptome profiling of banana shrimp (Fenneropenaeus merguiensis) ovaries and testes: Insights into FoxL2

The banana shrimp is found in the Pacific and Indian Oceans. Female shrimp are preferred for consumption because they are larger than males. Understanding the mechanism of sex differentiation is important for developing techniques to increase the number of female shrimp for economic benefits. This study investigates the reproductive development of F. merguiensis using transcriptome analysis. Sxl2, dsx, AGH, FEM-1, and Nrg-X2 were classified as essential genes for testes development during the juvenile stage. Several genes were required for both juvenile and adult male development. Additionally, the expression of several genes was shown to be required for juvenile and adult ovarian development, including SOP1, SOP2, Ptgr1, EST, Vgr, Vmol1, and TR-beta A. Interestingly, high levels of FoxL2 expression were observed in the testes, in contrast to previous studies in humans and other mammals. The binding of FoxL2 to the Vtg promoter was demonstrated in silico with the highest relative binding score (RS = 0.89) using the JASPAR program. Knock-down of the FoxL2 gene with dsRNA significantly suppressed FoxL2 at 2, 4, and 6 d. As a result, Vtg expression increased when compared with the control at 2, 4, and 6 d, indicating that FoxL2 plays an important role in Vtg expression in the ovary. Our findings highlight the role of FoxL2 in banana shrimp reproduction and provide valuable information on the genes associated with the F. merguiensis reproductive system.

Modulation of the PGE2-Mediated Pathway in the Eclosion Blocking Effect of Flumethrin and Terpenoid Subfraction Isolated from Artemesia nilagirica in Rhipicephalus annulatus

Prostaglandins are a group of important cell-signaling molecules involved in the regulation of ovarian maturation, oocyte development, egg laying and associated behaviors in invertebrates. However, the presence of prostaglandin E₂ (PGE₂), the key enzymes for PGE₂ biosynthesis and its interference by drugs were not investigated previously in the ovary of ticks. The present study was undertaken to assess the modulation of the PGE₂-mediated pathway in the eclosion blocking effect of flumethrin and terpenoid subfraction isolated from Artemisia nilagirica in Rhipicephalus annulatus ticks. The acaricidal activities and chemical profiling of the terpenoid subfraction were performed. The localization of the cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) enzymes and the quantification of PGE₂ in the ovaries of the ticks treated with methanol (control), flumethrin and terpenoid subfraction were also undertaken. In addition, the vitellogenin concentration in hemolymph was also assayed. Both flumethrin and the terpenoid subfraction of A. nilagirica elicited a concentration-dependent inhibition of fecundity and blocking of hatching of the eggs. The COX1 could not be detected in the ovaries of treated and control ticks, while there was no significant difference observed in the concentration of vitellogenin (Vg) in them. The presence of PGES in the oocytes of control ticks was confirmed while the immunoreactivities against PGES were absent in the vitellogenic oocytes of ticks treated with flumethrin and terpenoid subfraction. The levels of PGE₂ were below the detection limit in the ovaries of the flumethrin-treated ticks, while it was significantly lower in the ovaries of the terpenoid subfraction-treated ticks. Hence, the prostaglandin E synthase and PGE₂ were identified as very important mediators for the signaling pathway for ovarian maturation and oviposition in ticks. In addition, the key enzyme for prostaglandin biosynthesis, PGES and the receptors for PGE₂ can be exploited as potential drug targets for tick control. The detection of PGES by immunohistochemistry and quantification of PGE₂ by LC-MSMS can be employed as valuable tools for screening newer compounds for their eclosion blocking acaricidal effects.

Variation of prostaglandin E2 concentrations in ovaries and its effects on ovarian maturation and oocyte proliferation in the giant fresh water prawn, Macrobrachium rosenbergii

Prostaglandins (PGs) are important bioactive mediators for many physiological functions. In some decapod crustaceans, prostaglandin E2 (PGE2) has been detected in reproductive organs, and may play a role in the control of ovarian maturation. However, in the freshwater prawn, Macrobrachium rosenbergii, the presences of PGE2 and key enzymes for PGE2 biosynthesis, as well as its effects on ovarian maturation have not yet been investigated. In this study we reported the presence of PGE2, cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) in the ovarian tissues of M. rosenbergii, using immunohistochemistry. Intense immunoreactivities of PGE2 (PGE2-ir), COX1 (Cox1-ir) and PGES (PGES-ir) were detected in previtellogenic oocytes (Oc1 and Oc2), while the immunoreactivities were absent in the late vitellogenic oocytes (Oc4). This finding supports the hypothesis that the PGE2 biosynthesis occurs in the ovary of this prawn. To ascertain this finding we used LC-MS/MS to quantitate PGE2 concentrations during ovarian developmental cycle. The levels of PGE2 were significantly higher in the early ovarian stages (St I and II) than in the late stages (St III and IV). Moreover, we found that administration of PGE2 stimulated the ovarian maturation in this species by shortening the length of the ovarian cycle, increasing ovarian-somatic index, oocyte proliferation, and vitellogenin (Vg) level in the hemolymph.

Insights into the prostanoid pathway in the ovary development of the penaeid shrimp Penaeus monodon

The prostanoid pathway converts polyunsaturated fatty acids (PUFAs) into bioactive lipid mediators, including prostaglandins, thromboxanes and prostacyclins, all of which play vital roles in the immune and reproductive systems in most animal phyla. In crustaceans, PUFAs and prostaglandins have been detected and often associated with female reproductive maturation. However, the presence of prostanoid biosynthesis genes remained in question in these species. In this study, we outlined the prostanoid pathway in the black tiger shrimp Penaeus monodon based on the amplification of nine prostanoid biosynthesis genes: cytosolic phospholipase A2, hematopoietic prostaglandin D synthase, glutathione-dependent prostaglandin D synthase, prostaglandin E synthase 1, prostaglandin E synthase 2, prostaglandin E synthase 3, prostaglandin F synthase, thromboxane A synthase and cyclooxygenase. TBLASTX analysis confirmed the identities of these genes with 51-99% sequence identities to their closest homologs. In addition, prostaglandin F2α (PGF2α), which is a product of the prostaglandin F synthase enzyme, was detected for the first time in P. monodon ovaries along with the previously identified PUFAs and prostaglandin E2 (PGE2) using RP-HPLC and mass-spectrometry. The prostaglandin synthase activity was also observed in shrimp ovary homogenates using in vitro activity assay. When prostaglandin biosynthesis was examined in different stages of shrimp ovaries, we found that the amounts of prostaglandin F synthase gene transcripts and PGF2α decreased as the ovaries matured. These findings not only indicate the presence of a functional prostanoid pathway in penaeid shrimp, but also suggest a possible role of the PGF2α biosynthesis in shrimp ovarian development.

Reproductive regulators in decapod crustaceans: an overview

Control of reproductive development in crustaceans requires neuropeptides, ecdysone and methyl farnesoate (MF). A major source of neuropeptides is the X-organ-sinus gland (XO-SG) complex located in the eyestalk ganglia of crustaceans. The other regulatory factors (either peptides or neuromodulators) are produced in the brain and thoracic ganglia (TG). Two other regulatory non-peptide compounds, the steroid ecdysone and the sesquiterpene MF, are produced by the Y-organs and the mandibular organs, respectively. In the current review, I have tried to recapitulate recent studies on the role of gonadal regulatory factors in regulating crustacean reproduction.

Maturation-related variations in prostaglandin and fatty acid content of ovary in the kuruma prawn (Marsupenaeus japonicus)

Total lipid, fatty acids and prostaglandins (PGF(2 alpha) and PGE(2)) in the ovary of kuruma prawns (Marsupenaeus japonicus) were measured during ovarian development. The level of ovarian total lipid increased with an increase in the gonad-somatic index (GSI). No significant difference was found in fatty acid composition among different stages of ovarian development. However, the content of arachidonic acid (precursor of PG(2)), but not eicosapentanoic acid (precursor of PG(3)), was significantly lower at stages I and II than at stage V (P<0.01). When ovarian PGF(2 alpha) and PGE(2) levels were plotted against GSI, no correlation was found in either PG. However, in terms of ovarian developmental stages, the level of ovarian PGs was high (approx. 20 pg/mg) at stage I, followed by marked decreases at stages IV and V (PGF(2 alpha), P<0.01) and stage IV (PGE(2), P<0.01). These results suggest that ovarian PGs and arachidonic acid are deeply involved in ovarian maturation in kuruma prawns.

The synthesis and effects of prostaglandins on the ovary of the crab Oziotelphusa senex senex

The possible involvement of prostaglandins in the regulation of ovarian development in the crab Oziotelphusa senex senex was investigated. Uptake of labelled arachidonic acid into the ovary of the crab was significantly greater than the other tissues. Prostaglandin H synthase activity was significantly increased in the ovary during the late vitellogenic stage when compared to immature ovary. The biosynthesis of different prostaglandins in the ovary was also measured during the crab reproductive cycle. Injection of prostaglandin F(2alpha) and prostaglandin E(2) significantly increased ovarian index and oocyte diameter in a dose-dependent manner. In contrast, injection of prostaglandin D(2) did not affect ovarian growth. These results demonstrate the presence of prostaglandin biosynthetic system in ovary of the fresh water crabs.