Optimization of sperm cryopreservation protocol for Basa catfish (Pangasius bocourti).

The aim of this study was to optimize a sperm cryopreservation protocol for Basa catfish (Pangasius bocourti). Key factors for the efficiency of cryopreservation, including cryoprotectants, thawing conditions, equilibration times, dilution ratios and freezing methods, were investigated. The suitable time for post-thaw storage as well as pre-freezing cool storage was also examined. Five cryoprotectants (dimethyl sulfoxide, Me2SO; dimethylformamide, DMF; ethylene glycol, EG; propylene glycol, PG; N-methylacetamide, MA) at different final concentrations (5, 10 and 15%) were tested, 10% PG provided the best cryoprotective effect. Thawing temperature at 30-40 °C yielded significantly higher post-thaw motility than 20, 25, 50 or 60 °C. No obvious effect on sperm motility was detected either in equilibrated or thawed samples during a 2-h equilibration. Regarding dilution ratio (semen/cryomedium, v/v), percentage of motile spermatozoa was significantly higher at ratios of 2:1, 1:1 and 1:3 than those with higher ratios (1:5, 1:7 and 1:9). Thawed sperm was sensitive to post-thaw storage, but no reduction in motility was detected within 30 min. Further evaluation of the effective pre-freezing storage time indicated that sperm in diluted form had more advantage in maintaining its freezability, which could be chilled for 24 h before freezing without compromising post-thaw sperm motility. P. bocourti sperm could be successfully cryopreserved with both a programmable freezer and the floating frame technique (frozen 5 or 7 cm above the surface of liquid nitrogen). Cryopreserved sperm (77.5 ± 5.1%) fertilization was not significantly different from fresh sperm (80.9 ± 4.7%) at the ratio of 2 × 105 spermatozoa per egg. Our results provided more detailed suitable conditions for P. bocourti sperm cryopreservation than previous studies. Standardizing the cryopreservation protocol and storage time would be helpful in facilitating artificial reproduction in this species.

Successful short-term sperm cryopreservation in brown-marbled grouper (Epinephelus fuscoguttatus) with the utility of ultra-freezer (-80°C).

Production of cryopreserved semen in fish generally requires liquid nitrogen (LN), which is not always easily available in remote areas. To reduce reliance on LN, the aim of the present study was to evaluate whether electric freezer could be a feasible LN-free alternative to cryopreserve brown-marbled grouper sperm. After loading, semen straws were put directly into freezers (-30 or -80°C) for freezing and then transferred to LN for storage. Compared with the conventional LN vapour freezing (straws were put horizontally 3 cm above the surface of LN), there was a significant reduction in all tested post-thaw sperm quality parameters in samples frozen at -30°C for 10 min, including kinetic parameters (total motility: 85.0% vs. 48.6%), viability (84.7% versus 51.7%), high mitochondrial membrane potential (86.4% vs. 63.7%), ATP content (106.9 nM/109 cells vs. 72.9 nM/109 cells) and hatching rate (86.3% vs. 45.7%), accompanied with an increasing lipid peroxidation level (MDA content: 11.9 nM/109 cells vs. 4.9 nM/109 cells). In contrast, frozen with -80 °C ultra-freezer (10 min or 12 hr) produced similar sperm quality parameters to those using LN, except that temporary storage (12 hr) at -80°C yielded lower average path velocity. In conclusion, this study confirmed that -80°C ultra-freezer is an effective alternative to LN for sperm freezing in brown-marbled grouper.

Morin as a Preservative for Delaying Senescence of Banana.

Banana is a climacteric fruit with desirable palatability and high nutritional value. It ripens rapidly accompanied with metabolite changes during postharvest storage. In this work, morin was applied to treat banana to delay senescence. Nuclear magnetic resonance (NMR) spectroscopy was used to monitor the changes of metabolite composition and levels in banana. The results showed that morin significantly delayed the changes of color and firmness. 1D and 2D NMR spectra reflected that the levels and composition of metabolites were changed with the senescence initiation. The principal component analysis revealed that the first principal components responsible for banana senescence were carbohydrates, amino acids, lipids and phenolics. Morin treatment delayed the transformation of starch to glucose, fructose and sucrose, accelerated the accumulations of alanine and γ-Amino-butyrate (GABA), postponed the generations of valine and l-aspartic acid, suppressed the degradation of saponin a. It indicated that morin was effective in delaying banana senescence.

Phytochemical analyses of Ziziphus jujuba Mill. var. spinosa seed by ultrahigh performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

Ziziphus jujuba Mill. var. spinosa (Z. jujuba) seeds have attracted much attention within the field of medicine due to their significant effects against disturbances of the central nervous system. Secondary metabolites composition is key to the influence of the pharmaceutical and commercial qualities of this plant. In this work, the phytochemical profile of Z. jujuba seeds was analysed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS). The UPLC-MS/MS information identified the main secondary metabolites in Z. jujuba seeds, including flavonoid C-glycosides, triterpene acids and unsaturated fatty acids. The leading chemical identified by UPLC-MS/MS was betulinic acid, and oleic acid was the leading volatile from the GC-MS results. All the samples tested showed similar phytochemical profiles, but levels of the chemical compounds varied. Principal component analysis revealed the principal secondary metabolites that could define the differences in quality. It was confirmed that the combination of UPLC-MS/MS and GC-MS was an effective technique to demonstrate the pharmaceutical quality of Z. jujuba seeds.

Structural analysis of water-soluble polysaccharides in the fruiting body of Dictyophora indusiata and their in vivo antioxidant activities.

The water-soluble Dictyophora indusiata polysaccharides (DIP) were extracted from the fruiting body of D. indusiata. The structural features of purified DIPs I and II were investigated. The results indicated that DIP I was composed of glucose (Glc) and mannose (Man) with molecular weight of 2100kDa, while DIP II comprised of xylose (Xyl), galactose (Gal), glucose (Glc) and Man with molecular weight of 18.16kDa. The glycosidic linkage of DIP I was composed of →1)-Glc-(6→: →1)-Man-(3,6→ with the ratio of 5.6:1.0, while DIP II was composed of →1)-Glc-(6→: →1)-Man-(3,6→: →1)-Xyl-(5→: →1)-Gal-(3→: →1)-Gal-(6→: with the ratio of 4.9: 15.5: 7.8: 1.0: 5.7. DIP significantly (P<0.05) decreased the malondialdehyde (MDA), lipofuscin levels and increased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities of mice. The strong in vivo antioxidant activity indicated DIP had great potential as functional food.

Use of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation.

The potential of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation was elucidated. Four strains of T. halophilus isolated from fish sauce mashes were inoculated to anchovy mixed with 25% NaCl with an approximate cell count of 10(6) CFU/mL. The α-amino content of 6-month-old fish sauce samples inoculated with T. halophilus was 780-784 mM. The addition of T. halophilus MRC10-1-3 and T. halophilus MCD10-5-10 resulted in a reduction of histamine (P < 0.05). Fish sauce inoculated with T. halophilus showed high contents of total amino acids with predominantly high glutamic acid. Major volatile compounds in fish sauce were 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde. T. halophilus-inoculated fish sauce samples demonstrated the ability to reduce dimethyl disulfide, a compound contributing to a fecal note. The use of T. halophilus for fish sauce fermentation improves amino acid profiles and volatile compounds as well as reduces biogenic amine content of a fish sauce product.