Preliminary estimation of tropical ornamental fish metabolite production rates

The rational design of closed aquaculture systems requires data on metabolite production rates. The metabolite of primary concern is often ammonia. Ammonia formation rates for a number of tropical ornamental fish types and sizes were determined. Cyprinus carpio, Barbus conchonius, Pseudotropheus auratus and Carassius auratus auratus were used as representative egg-layers while Xiphophorus variatus and Xiphophorus helleri represented the live-bearers. Specific metabolite production rates, R′, were determined not only in terms of mass of fish but also the amount of feed. For instance, R′ (Amm-N) for 1.33 g unit size Barbus conchonius was determined to be 155.9 mg Amm-N kg-fish⁻¹% feed⁻¹ day⁻¹. In an attempt to produce a general model for all the ornamental fish investigated, all values of R′ obtained were correlated with fish sizes to produce an equation R′ (Amm-N) = 1.57-[30×log(itUW)] where UW = unit fish size.     

The predation of trumpet shell, Charonia sp., on eight different marine invertebrate species

In this study, predation of the trumpet shell, Charonia sp., on different invertebrate prey species, e.g. starfish, Asterina pectinifera and Asterias amurensis, abalone Haliotis discus hannai, clam Anadara broughtonii and Tapes phillipiarum, and sea urchin Hemicentrotus pulcherrimus and Anthocidaris crassispina, was measured in a laboratory experiment. Each prey species was placed in a tank with a trumpet shell; prey species were not combined. Each combination of prey and trumpet shell was replicated three times. Trumpet shells did not prey on economically important shellfishes, including Anadara broughtonii, Tapes phillipiarum and Haliotis discus hannai. Sea stars were most preferred by the trumpet shell. The following preference gradient from most to least preferred was found: sea stars > sea cucumber > sea urchin. In selected situations, trumpet shells may be a means of biological control of predators of economically important shellfish.     

Contribution of human alpha-defensin 1, 2, and 3 to the anti-HIV-1 activity of CD8 antiviral factor

It has been known since 1986 that CD8 T lymphocytes from certain HIV-1-infected individuals who are immunologically stable secrete a soluble factor, termed CAF, that suppresses HIV-1 replication. However, the identity of CAF remained elusive despite an extensive search. By means of a protein-chip technology, we identified a cluster of proteins that were secreted when CD8 T cells from long-term nonprogressors with HIV-1 infection were stimulated. These proteins were identified as alpha-defensin 1, 2, and 3 on the basis of specific antibody recognition and amino acid sequencing. CAF activity was eliminated or neutralized by an antibody specific for human alpha-defensins. Synthetic and purified preparations of alpha-defensins also inhibited the replication of HIV-1 isolates in vitro. Taken together, our results indicate that alpha-defensin 1, 2, and 3 collectively account for much of the anti-HIV-1 activity of CAF that is not attributable to beta-chemokines.     

Comparison of volatile generation in serine/threonine/glutamine-ribose/glucose/fructose model systems

Thermal generation of volatiles in nine model reactions was studied and compared. Each of the model systems contained one amino acid and one monosaccharide. The amino acid was serine, threonine, or glutamine, and the monosaccharide was ribose, glucose, or fructose. More unsubstituted pyrazine was generated in serine-sugar systems than threonine-sugar systems. The formation of several furfuryl-substituted pyrazines and pyrroles was observed in some of the studied systems. Total pyrazines were generated more in glutamine-containing systems than in serine- and threonine-containing systems, and the reverse was true for generation of furfuryl-substituted compounds. Acetylpyrazine was generated in serine/threonine/glutamine-glucose and serine/glutamine-fructose systems.     

Protective effects of quercetin and vitamin C against oxidative stress-induced neurodegeneration

Clinical trials of several neurodegenerative diseases have increasingly targeted the evaluation of various antioxidants' effectiveness. The human diet contains several thousand phytochemicals, many of which have significant bioactivities. Vitamin C, a naturally occurring antioxidant, is known to reduce the risk of neurodegenerative disorders such as Alzheimer's disease. Quercetin, one of the major flavonoids in some fruits and vegetables, has much stronger antioxidative and anticarcinogenic activities than vitamin C. Therefore, we investigated the protective effects of quercetin on hydroxy peroxide-induced neurodegeneration. To determine the protective effects, PC12 cells were preincubated with quercetin and vitamin C before H(2)O(2) treatment for 2 h. Results showed that cell viability was clearly improved with quercetin, and quercetin showed a higher protective effect than vitamin C. Because oxidative stress is known to increase neuronal cell membrane breakdown, we further investigated lactate dehydrogenase and trypan blue exclusion assays. We observed that quercetin decreased oxidative stress-induced neuronal cell membrane damage more than vitamin C. These results suggest that quercetin, in addition to many other biological benefits, contributes significantly to the protective effects of neuronal cells from oxidative stress-induced neurotoxicity, such as Alzheimer disease.     

Rheological properties of fast skeletal myosin rod and light meromyosin from walleye pollack and white croaker: contribution of myosin fragments to thermal gel formation

Myosin rod and light meromyosin (LMM) of walleye pollack and white croaker were examined for their rheological properties by measuring dynamic viscoelastic parameters. Rods from walleye pollack and white croaker increased their storage moduli (G') in the ranges of 29-43 degrees C and 31-38 degrees C, respectively, in temperature sweep analysis. Walleye pollack LMM showed no peak of G' upon heating, whereas the white croaker counterpart exhibited a single sharp peak of G' at 35 degrees C. Loss modulus (G") showed similar temperature-dependent changes for the two fish species as the case of G', irrespective of rod and LMM, although G" values were lower than those of G'. Thus, rheological properties of rod and LMM were different between walleye pollack and white croaker. Taken together with data previously reported for myosin, it was considered that both myosin rods from walleye pollack and white croaker are attributed to thermal gel formation of myosin in a low-temperature range, though in a species-specific manner.     

Effects of carnosine on volatile generation from Maillard reaction of ribose and cysteine

Carnosine occurs naturally in meat and meat products in significant quantity, and it possesses strong antioxidant activity that inhibits lipid oxidation and enhances shelf life. In this study, the effects of carnosine on thermal flavor generation were investigated using the model system of cysteine and ribose, which was heated to the roasting temperature of 180 degrees C for 2 h at pH 5 and pH 8.5. The results indicated that carnosine affected volatile formation in a complex manner. Volatiles identified from the liquid phase of the reaction systems of ribose and cysteine showed that the sulfur-containing compounds such as thiophenes, thiazoles, and polysulfides were the most abundant compounds. The addition of carnosine into the reaction mixtures in general caused a reduction in contents of thiophenes and some important meaty flavor compounds such as 2-methyl-3-furanthiol, 2-furfurylthiol, and their associated dimers. On the other hand, it facilitated the generation of several important nitrogen-containing volatiles such as pyrazine, methylpyrazine, 2,6-dimethylpyrazine, and other alkyl pyrazines and thiazoles, which are known to elicit roasty and nutty flavor notes. The results suggested that carnosine acts as a nitrogenous source to facilitate the formation of nitrogen-containing compounds, possibly by degradation to form ammonia.     

Characterization of 2-methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine from thermal degradation of thiamin

Thiamin hydrochloride was thermally degraded in phosphate buffer (pH 6.5) at 110 degrees C for 2 h. A major decomposition product was isolated by column chromatography and structurally identified by spectrometric techniques ((1)H NMR, (13)C NMR, 2D NMR, and MS) as 2-methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine (MAMP). The possible formation pathway of MAMP was studied using two model systems. It is proposed that MAMP is formed by nucleophilic attack of 2-methyl-3-furanthiol on the thiamin.     

温度对微晶氧化铁形成与性质的影响

稀释0.5mol/L Fe(NO₃)₃母液,制成二组0.001mol/L Fe(NO₃)₃,溶液,每组分成5等份,于每份溶液中分别加入不同量的NaOH,使溶液的NaOH/Fe,分子比为0、1.0、1.8、2.7、3.1,然后在70℃烘箱中水解。制备二组试样的主要区别是母液稀释水的最初温度不同,但其最终形成的氧化铁在颗粒大小,结晶度以及显微形貌等方面有明显差别。Ⅰ组试样是用70℃水稀释制备而成,1天后其反应产物呈无定形的非晶物质,在70℃老化很短时间后,便转变成结晶好的针铁矿和赤铁矿。Ⅱ组试样是用室温水(25℃)制备。在整个实验期间,其水解产物具有轮廓明显的小圆球状微晶氧化铁,即使在老化248天后仍属结晶差的针铁矿和赤铁矿,只能用高功率转靶的X射线衍射仪才能反映其特征衍射峰,鉴定其组成。试验结果表明:制备试样时,水的温度对最初水解产物的性质起关键作用,而最初产物的特性对溶液中再溶解再结晶的速率起着重要作用。     

Presumed generalised seizure following caudal epidural administration of morphine and detomidine in a pony

A 9-year-old show pony mare became acutely lame following removal of a bone sequestrum of the distal phalanx of the right thoracic limb. The mare also suffered from ongoing right dorsal colitis secondary to previous long-term nonsteroidal anti-inflammatory drug (NSAID) use. To avoid further NSAID use, a protocol for caudal epidural administration of morphine and detomidine in an increased volume was used to provide analgesia to the thoracic limbs. A total volume of 50 mL (0.2 mL/kg bwt) was administered over approximately 90 s. Immediately following the injection, the pony collapsed into lateral recumbency and experienced an apparent generalised seizure characterised by loss of consciousness and frantic paddling of all four limbs. The pony recovered rapidly without intervention, and no residual neurological deficits were noted. The epidural analgesia resulted in a marked improvement in comfort levels. The speed of injection is thought to have caused a change in epidural and intracranial pressures resulting in a generalised seizure and highlights the importance of administering large volumes slowly.