Trace metal concentrations in edible tissue of snapper, flathead, lobster, and abalone from coastal waters of Victoria, Australia

The concentrations of heavy metals in the edible tissue of commonly fished species of the Victorian coast of Australia are reported. The metals studied were As, Cd, Cu, Hg, Pb, Se, and Zn and the fish species examined were snapper (Pagruss auratus), flathead (Platycephalus bassenssis and Neoplatycephalus richardsoni), lobster (Jasus edwardsii), and abalone (Haliotis rubra). None of the fish species studied had average concentrations exceeding the maximum levels specified for As, Cd, Hg, and Pb by the Food Standards Australia and New Zealand Food Standards code. Additionally, the concentrations of Cu, Se, and Zn were close to or below the median values generally expected in these species. Essential trace elements Se and Zn were found to be well regulated by all fish species. Although also essential, Cu was not so well regulated, especially in abalone. Nonessential metals As, Cd, and Hg are not regulated in the studied fish and their concentrations in the fish tissue are dependent on size and fishing zone. Metal concentrations were not largely affected by sex. Surprisingly, the concentrations of metals in fish in Port Phillip Bay, a zone, which includes the major cities of Melbourne and Geelong and is known to have high concentrations of metals in the water and sediment, were not consistently higher than those in other less-populated fishing zones.

Gas chromatography-chemical ionization-mass spectrometric fatty acid analysis of a commercial supercritical carbon dioxide lipid extract from New Zealand green-lipped mussel (Perna canaliculus)

Supercritical fluid extracts of New Zealand green-lipped mussels (NZGLM) have been suggested to have therapeutic properties related to their oil components. The large number of minor FA in NZGLM extract was characterized by a GC-CIMS/MS method that excels at identification of double-bond positions in FAME. The extract contained five major lipid classes: sterol esters, TAG, FFA, sterols, and polar lipids. The total FA content of the lipid extract was 0.664 g/mL. Fifty-three unsaturated FA (UFA) were fully identified, of which 37 were PUFA, and a further 21 UFA were detected for which concentrations were too low for assignment of double-bond positions. There were 17 saturated FA, with 14∶0, 16∶0, and 18∶0 present in the greatest concentration. The 10 n−3 PUFA detected included 20∶5n−3 and 22∶6n−3, the two main n−3 FA; n−3 PUFA at low concentrations were 18∶3, 18∶4, 20∶3, 20∶4, 21∶5, 22∶5, 24∶6, and 28∶8. There were 43 UFA from the n−4, n−5, n−6, n−7, n−8, n−9, n−10, n−11 families, with 16∶2n−4, 16∶1n−5, 18∶1n−5, 18∶2n−6, 20∶4n−6, 16∶1n−7, 20∶1n−7, 16∶1n−9, 18∶1n−9, and 20∶1n−9 being the most abundant. In general, we estimated that FAME concentrations greater than 0.05% (w/w) were sufficient to assign double-bond positions. In total, 91 FA were detected in an extract of the NZGLM, whereas previous studies of fresh flesh from the NZGLM had reported identification of 42 FA. These data demonstrate a remarkable diversity of NZGLM FA.

Lipid, FA, and sterol composition of New Zealand green lipped mussel (Perna canaliculus) and Tasmanian blue mussel (Mytilus edulis)

The lipid, FA, and sterol composition of the New Zealand green lipped mussel (NZGLM, Perna canaliculus) and of the Tasmanian blue mussel (TBM, Mytilus edulis) were compared using TLC-FID and GC-MS. The respective mussel species were obtained from three different sites in both New Zealand (NZ) and Tasmania. Lipid class distribution of both mussel species was characterized by a high proportion of phospholipid (PL, 57–79%) and TG (10–25%), FFA (7–12%), and sterols (ST, 12–18%). The NZGLM had higher proportions of TG, FFA, and ST (P<0.01), whereas the TBM had a higher proportion of PL (P<0.01). There were higher proportions of total PUFA, saturated FA, n−3 FA, and hydroxy and nonmethyleneinterrupted FA (P<0.05) in the TBM compared with the NZGLM. The major FA in the NZGLM were 16∶0 (15–17%), 20∶5n-3 (14–20%), and 22∶6n-3 (11–17%). The same FA dominated lipids in the TBM, although there were significantly higher proportions of 16∶0 (P=0.000) and 22∶6 n−3 (P=0.003) and lower proportions of 20∶5n-3 (P=0.0072) in the TBM. A novel PUFA, 28∶8n-3, was detected in both mussels with higher amounts in the TBM, which probably reflects a greater dietary contribution of dinoflagellates for this species. Cholesterol was the dominant sterol in both mussels. Other major sterols included brassicasterol, 22-methylcholesterol, trans-22-dehydrocholesterol, and desmosterol. There were significant differences (P<0.05) between the NZGLM and TBM for 12 of the 20 sterols measured. Six sterols showed significant site differences for the NZGLM, and 10 for the TBM. The differences in the FA and sterol composition between the two species may be due to the diet of the NZGLM being more diatom-derived and the diet of the TBM having a greater dinoflagellate component.

Fatty acid and sterol composition of frozen and freeze-dried New Zealand green lipped mussel (Perna canaliculus) from three sites in New Zealand

In view of previously reported anti-inflammatory bioactivity of the New Zealand Green Lipped Mussel (NZGLM), the overall lipid profile and fatty acid and sterol composition of the NZGLM from various sites in New Zealand (Hallam Cove, Port Ligar, Little Nikau) were investigated using thin layer  chromatography (TLC) and gas liquid chromatography (GLC). Samples were either frozen (F) or freeze-dried (FD) soon after collection. It was also thought prior to the study, there may be differences in the dietary sources of phytoplankton between the sites, responsible for the bioactivity, however data collected in New Zealand reported no difference in the type of phytoplankton, but a difference in the quantity. There were no major significant differences in the major components of the lipid, fatty acid and sterol composition between FD or frozen samples, nor were there any significant differences in the major composition between sites. The only major difference was between total lipid composition of the freeze-dried and frozen samples due to the removal of water during freeze-drying. Total lipid content on a dry weight basis in FD samples was 8.4 g/100g tissue and was significantly higher than frozen samples (P < 0.05) and there was no significant site variation. The lipid class content between sites was also not significantly different as judged by TLC. Triglyceride (TG) lipid fraction appeared to be the most prominent in the frozen and FD samples. The free fatty acid (FFA) band was the next most prominent band and was visually more prominent in the frozen samples. Sterol esters (SE) were detected in higher amounts in the frozen samples compared with the FD samples. Phospholipid (PL) and sterols (ST) were distributed throughout all samples. Polyunsaturated fatty acids (PUFA) were the main group of fatty acids in both FD and frozen samples (45-46%), most of which were omega-3 (n-3) fatty acids (40-41%). Saturated fatty acids (SFA) accounted for approximately one quarter of total fatty acids, with little variation between FD and frozen samples. The major fatty acids of the NZGLM were docosahexaenoic acid (DHA; 22:6n-3) (19% in both FD and frozen samples), eicosapentaenoic acid (EPA; 20:5n-3) and palmitic acid (16:0) (15% in both FD and frozen samples). Cholesterol was the most prominent sterol (31% of total sterols). Other major sterols included desmosterol/ brassicasterol (co-eluting), 24-methylenecholesterol, trans-22-dehydrocholesterol, 24- nordehydrocholesterol and occelasterol. This study is unique as it compares the lipid composition of the NZGLM from three sites in New Zealand with the additional effect of processing. This is the second comparative study investigating the lipid, fatty acid and sterol composition of the NZGLM with added interest in the effect of freeze drying on the lipid content of the mussel. This study showed that there were no major significant differences in lipid, sterol and fatty acid composition between the FD and frozen samples of the NZGLM for three sites in New Zealand. Food chain studies and further research is warranted to investigate the presence and role of major and minor lipid.
components of the NZGLM.

Comparative effects of the blue green algae Nodularia spumigena and a lysed extract on detoxification and antioxidant enzymes in the green lipped mussel (Perna viridis)

Nodularia spumigena periodically proliferates to cause toxic algal blooms with some aquatic animals enduring and consuming high densities of the blue green algae or toxic lysis. N. spumigena contains toxic compounds such as nodularin and lipopolysaccharides. This current work investigates physiological effects of exposure from bloom conditions of N. spumigena cells and a post-bloom lysis. Biochemical and antioxidative biomarkers were comparatively studied over an acute 3-day exposure. In general, a post-bloom N. spumigena lysis caused opposite physiological responses to bloom densities of N. spumigena. Specifically, increases in glutathione (GSH) and glutathione peroxidase (GPx) and decreases in glutathione S-transferase (GST) were observed from the N. spumigena lysis. In contrast, N. spumigena cell densities decreased GSH and increased GST and lipid peroxidation (LPO) in mussels. Findings also suggest that at different stages of a toxic bloom, exposure may result in toxic stress to specific organs in the mussel.

Characterization of Type 1 ribosome inactivating proteins in edible plants

The ribosome inactivating proteins (RIPs) from plants possess RNA N-glycosidase activity that depurinates the major rRNA, thus damaging ribosome in an irreversible manner and arresting protein synthesis. RIPs occur in fungi, bacteria and plants and are abundant in angiosperms, where they appear to have defensive role. RIPs are presently classified as rRNA N-glycosidase in the enzyme nomenclature (EC 3.2.2.22) and do exhibit other enzymatic activities such as ribonuclease and deoxyribonuclease activities. RIPs are classified into two groups based on their difference in their primary structure. Type I RIPs consist of a single polypeptide chain of approximately 26–35 kDa that possess an RNA N-glycosidase activity. These proteins have attracted a great deal of attention because of their anti-viral, anti-tumor, and anti-microbial activities, which is useful in medical research and development. Here, we describe isolation of a novel protein from Momordica sp, a highclimbing vine from family Cucurbitaceae which is native to the tropical regions of Africa, Asia, Arabia and Caribbean. The purified protein has been verified by SDS-PAGE and mass spectrometry to contain only single chain Type-1 ribosome inactivating proteins (RIPs). With present experiments, we determined the presence of RIPs in edible plant materials, including some that are eaten raw by human beings. The novel protein is further characterized to validate its therapeutic potential.

Comparison of lipid content and fatty acid composition in the edible meat of wild and cultured freshwater and marine fish and shrimps from China

The lipid content and fatty acid composition in the edible meat of twenty-nine species of wild and cultured freshwater and marine fish and shrimps were investigated. Both the lipid content and fatty acid composition of the species were specified due to their unique food habits and trophic levels. Most of the marine fish demonstrated higher lipid content than the freshwater fish, whereas shrimps had the lowest lipid content. All the marine fish and shrimps had much higher total n-3 PUFA than n-6 PUFA, while most of the freshwater fish and shrimps demonstrated much lower total n-3 PUFA than n-6 PUFA. This may be the biggest difference in fatty acid composition between marine and freshwater species. The cultured freshwater fish demonstrated higher percentages of total PUFA, total n-3 PUFA, and EPA + DHA than the wild freshwater fish. Two freshwater fish, including bighead carp and silver carp, are comparable to the marine fish as sources of n-3 PUFA.