Effects of fish protein hydrolysate on growth performance and humoral immune response in large yellow croaker (Pseudosciaena crocea R.)

We investigated the effects of fish protein hydrolysate (FPH) on growth performance and humoral immune response of the large yellow croaker (Pseudosciaena crocea R.). One thousand and two hundred large yellow croakers [initial average weight: (162.75±23.85) g] were divided into four groups and reared in floating sea cages (3 m×3 m×3 m). The animals were fed with 4 diets: basal diet only (control) or diets supplemented with 5%, 10% and 15% (w/w) FPH. The results show that dietary FPH levels significantly influenced the growth and immunity of the large yellow croaker. Compared with the control group, total weight gain (TWG) in all treatment groups, relative weight gain (RWG) and specific growth rate (SGR) in fish fed with diets supplemented with 10% and 15% FPH were significantly increased (P<0.05). Similar results were observed in immune parameters [lysozyme activity, serum complements, immunoglobulin M (IgM)]. Lysozyme activity, complement C4 and IgM were also significantly increased (P<0.05) in fish fed with diets supplemented with 10% and 15% FPH, while complement C3 level was significantly increased (P<0.05) in all treatment groups. In general, with the supplementation of FPH, particularly at dose of 10%, the growth performance and immunity of the large yellow croaker can be improved effectively.

Photophysical Behavior of Heteroduplexes Formed from Naphthalene Incorporated Foldamers,and Linear Donors and Pyromellitic Diimide Incorporated Foldamers

The authors synthesized the electron-rich 1,5-dioxonaphthyl group incorporated foldamers, and linear donors and electron-deficient pyromellitic diimide incorporated foldamers, which were investigated in organic solvents. There is an evident charge transfer process from the donors to the electron-deficient foldamers, due to the donor-acceptor interaction of the heteroduplexes formed from the donors and the electron-deficient foldamers in chloroform, observed by using the ultraviolet（UV） visible method. The charge transfer process of the heteroduplexes depends on the molecular structure（not only the number of 1,5-dioxonaphthyl groups and pyromellitic diimide groups in the heteroduplex, but also the intermolecular double hydrogen bond in the heteroduplex）, the intercalative π-π stacking motif, the initial concentration of heteroduplexes, and the polarity of the solvent. Fortunately, the authors found a critical bumping concentration（CBC） of the donors in acetonitrile or chloroform, which is useful in quantitative research, by using the fluorescence method. The value of CBC depends not only on intramolecular folding and the intramolecular hydrogen bond, but also on intramolecular π-π stacking and the solvent. The electron-deficient foldamers quenched the fluorescence of the donors. Fluorescence quenching depends not only on the number of pyromellitic diimide groups and 1,5-dioxonaphthyl groups in the heteroduplex, but also on the intercalative π-π stacking motif between the donor and the acceptor.

Linear and Nonlinear QSPR Models for Predicting Thermal Stabilities of Nitroaromatic Compounds

Quantitative structure-property relationships（QSPRs） have been developed to predict the thermal stability for a set of 22 nitroaromatic compounds by means of the theoretical descriptors derived from electrostatic potentials on molecular surface. Several techniques, including partial least squares regression（PLS）, least-squares support vector machine（LSSVM） and Gaussian process（GP） have been utilized to establish the relationships between the structural descriptor and the decomposition enthalpy. The nonlinear LSSVM and GP models have proven to own a better predictive ability than the linear PLS method. Moreover, owing to its ability to handle both linear- and nonlinear-hybrid relationship, GP gives a stronger fitting ability and a better predictive power than LSSVM, and therefore could be well applied to developing QSPR models for the thermal stability of nitroaromatic explosives.

Minor Groove Binding between Norfloxacin and DNA Duplexes in Solution: A Molecular Dynamics Study

Molecular dynamics were used to investigate the interaction between norfloxacin and DNA duplex. The results showed that norfloxacin was situated in the minor groove of DNA, binding to the TCGA region of d [ATATCGATAT] 2- Specific hydrogen bonds were formed between norfloxacin and guanine base of DNA during the 2 ns MD, which may be the reason for the preferentiality of quinolone antibacterial towards the guanine base of DNA duplex.

Effects of α-tocopheryl acetate supplementation in preslaughter diet on antioxidant enzyme activities and fillet quality of commercial-size Sparus macrocephalus

This study examined the effects of dietary α-tocopheryl acetate supplementation on antioxidant enzyme activities and fillet quality in commercial-size Sparus macrocephalus. Three hundred fish [main initial weight (350±12) g] were divided into three groups (E250, E500 and E1000) and reared in 9 cages. The fish were fed for 8 weeks with three diets containing different levels of dietary α-tocopheryl acetate (289, 553, 1 069 mg/kg). Over the experimental period, fish were fed to satiation and reached a final mean weight of (465±28) g without significant body weight difference and proximate composition difference. Fillet α-tocopherol was significantly (P<0.05) different between groups, reaching levels of 14.2, 22.1, 30.9 μg/mg fillet for groups E250, E500 and E1000, respectively. Total serum superoxide dismutase (SOD) activity increased significantly (P<0.05) in fish fed the diets high in α-tocopheryl acetate, but serum glutathione peroxidase (GPX) activity was unaffected. In storage on ice, fillets of fish fed the diets high in α-tocopheryl acetate exhibited significantly lower (P<0.05) levels of oxidation. These results suggested that increased dietary α-tocopheryl acetate could increase its flesh deposition, increase the activity of SOD and prevent lipid peroxi-dation of Sparus macrocephalus fillets in retail storage on ice.

Effects of the dietary supplementation with fructooligosaccharides on the excretion of nitrogen and phosphorus in Miichthys miiuy fries

Effects of dietary supplementation with fructooligosaccharides on the excretion of nitrogen and phosphorus in Miichthys miiuy fries were investigated. Nine hundred Miichthys miiuy fries were divided into 3 groups, each with triplicates. The basal diet and the basal diet supplemented with carnitine groups were considered as the negative and positive controls respectively. Results showed that the nitrogen concentration in excreted feces decreased significantly in fries fed the diet supplementation with 1000×10?6 fructooligosaccharides and 200×10?6 carnitine (P<0.05). The ammonic-nitrogen concentration decreased significantly in the carnitine group only (P<0.05), indicating the decreasing tendency caused by the supplementation with fructooligosaccha-rides. Supplementation with both did not have significant effects on the concentration of phosphorus in feces of Miichthys miiuy fries.

Influence of fasting on muscle composition and antioxidant defenses of market-size Sparus macrocephalus

The study was conducted to investigate fasting effects on flesh composition and antioxidant defenses of market-size Sparus macrocephalus. Two hundred fish (main initial weight 580 g) were divided into two groups (control and fasted) and reared in 6 cages. After two weeks of adaptation, group I fasted for 28 d; group II was fed normally as a control. In 3, 7, 14, 21 and 28 d, 6 fish per group were sampled for proximate flesh composition, liver antioxidant enzyme activities and malondialdehyde flesh content analyses. In fasted fish, the reduction of lipid content in muscle occurred after day 3, and, compared to controls, the content of protein decreased from day 14, the activities of liver antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) increased from day 3, and flesh malondialdehyde levels increased from day 21. Flesh fat reduction shows that fasting may be used as a technique to reduce flesh lipid content in Sparus macrocephalus. However, considering flesh protein loss and the subsequent oxidative stress, the fasting technique should be used with precautions.

QSPR of Thermal Stability of Nitroaromatic Explosives Using Theoretical Descriptors Derived from Electrostatic Potentials on the Molecular Surface

In the present study,geometrical optimization and electrostatic potential calcula-tions have been performed for 22 nitroaromatic compounds at the HF/6-31G level of theory.A number of statistically based parameters have been obtained.Linear relationship between the decomposition enthalpy（taken as a macroscopic property related to explosibility） of nitroaromatic compounds and the structural descriptors have been established by multiple regression method.The result shows that the quantities derived from electrostatic potentialsΣ V sind＋,,Vsind- and Vs,max can be well used to express the quantitative structure-decomposition enthalpy relationship of nitroa-romatic compounds,which proves the general applicability of this parameter set to a great extent.Good predictive capabilities have also been demonstrated.

Influence of dietary conjugated linoleic acid on growth, fatty acid composition and hepatic lipogenesis in large yellow croaker (Pseudosciaena crocea R.)

We examined the effects of conjugated linoleic acid (CLA) on growth, fatty acid composition and enzyme activity of fatty acid oxidation in the liver of large yellow croaker. We divided 1600 fish (average initial weight 150 g) into 4 groups and reared them in 8 cages. Four dietary treatments were formulated to contain 0%, 1%, 2% and 4% (w/w) CLA, respectively. The fish were fed for 10 weeks ad libitum twice daily. We found that the dietary CLA had no effect on growth, biometric parameters and whole body proximate (P>0.05), but showed some significant effects on the fatty acid composition in both muscle and the liver. The activities of lipogenic enzymes were slightly depressed in fish fed with increasing levels of CLA when compared with control (P>0.05). Dietary CLA supplementation had no effects on liver lipid content, but significantly increased the contents of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) (P<0.05) and decreased monounsaturated fatty acid (MUFA) content in both muscle and the liver. Dietary CLA inclusion resulted in significant increases of the biologically active cis-9, trans-11 and trans-10, cis-12 isomers in both tissues (P<0.05). The total accumulation of CLA was higher in the liver (3.83%, w/w) than in muscle (3.77%, w/w) when fed with 4% (w/w) CLA. This study demonstrates that large yellow croakers are capable of absorbing and depositing CLA and long-chain n-3 PUFA in the liver and muscle, showing that this species fed with CLA could be an important human food source for these healthful fatty acids.

Ab Initio Calculations on Halogen Bond Between N—Br and Electron-donating Groups

Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ^＊ to gain a deeper insight into the nature of the N--Br halogen bonding. For the small complexes, H3 C--Br… NH3 and H2 N--Br…NH3 , the primary calculation has demonstrated that the N--Br in H2 N--Br… NH3 can form a much stronger halogen-bonding complex than the C--Br. A comparison of neutral hydrogen bond complex series reveals that the electron-donating capacities of the atoms decrease in the order, N 〉 O 〉 S; 0 （ sp^3 ） 〉 0 （ sp^2 ）, which is adequate for the C--Br halogen bonding. Interaction energies, in conjunction with the geometrical parameters show that the affinitive capacity of trihalide anions X^-3 with N-bromosuccinimide are markedly lower than that of the corresponding X^- with N-bromosuccinimide, even lower than those of neutral molecules with N-bromosueeinimide. AIM analyses further eorffirmed the above results.

Syntheses and Crystal Structures of Two One-dimensional Coordination Polymers Constructed from a Flexible Hinge-like Ligand

By using the flexible hinge-like ligand 2,2＇-bis（3-hydroxy-l,4-naphthoquinone） （H2bhnq）, two isomorphous one-dimensional zigzag chain coordination polymers have been obtained. Single-crystal X-ray analyses revealed that the metal centers in these two complexes are distorted octahedra involving four oxygen atoms of two bhnq2 anions, and two oxygen atoms of two DMF molecules situated in trans positions to one another. Crystal data for [Mn（bhnq）（DMF）2]n 1： C26H22MnN2O8, Mr = 545.40, monoclinic, space group C2/c, a = 14.936（3）, b = 10.362（2）, c = 15.901（3）A., β = 99.86（3）°, V = 2424.7（8）A3, Z = 4, Dc = 1.494 g/cm^3, F（000） = 1124,μ = 0.599 mm^-1, final GOOF = 1.025, R = 0.0654 and wR = 0.1537. Crystal data for [Cd（bhnq）（DMF）2]n 2： C26H22CdN2O8, Mr = 602.86, monoclinic, space group C2/c, a = 14.839（3）, b = 10.493（2）, c = 16.034（3）A, β = 99.40（3）°, V = 2463.1（9）A^3, Z = 4, Dc = 1.626 g/cm^3, F（000） = 1216,μ = 0.941 mm^-1, final GOOF = 1.069, R = 0.0358 and wR = 0.0944.

Synthesis and Crystal Structure of a Tetranuclear Cu(Ⅰ) Complex with Vinylidenebis(diphenylphosphine)

The vinylidenebis（diphenylphosphine） （vdpp） reacts with CuBr to give a tetranuclear complex, [Cu4（μ3-Br）2（μ2-Br）2（μ2-vdpp）2（CH3CN）2]·（CH3CN）2 1. The title complex has crystallo- graphically imposed centrosymmetry and presents a CuaBr4 core with distorted stair-like structure. All copper（I） atoms in 1 assume distorted tetrahedral coordination geometry. The distance of 2.7745（11） A between the two copper centers indicates the presence of ligand-supported Cu…Cu interactions. Crystal data for 1： C_60H_56Br_4Cu_4N_4P_4, Mr= 1530.77, triclinic, space group P1, a = 11.6593（9）, b = 11.7181（9）, c = 13.8711（11） А, a = 110.1020（10）, β = 102.0050（10）, γ = 109.8040（10）°, V = 1557.5（2） А^3, Z = 1, Dc = 1.632 g/cm^3, F（000） = 760, λ= 0.71073А, T = 298（2） K, 2θmax = 50.04°,μ= 4.056 mm^-1, S = 1.181, R = 0.0507 and wR = 0.1025.

1,3- and 1,5-Sigmatropic Shifts: Insights into the Structure-Reactivity Relationship from ab initio Calculations

Thermal [ 1,n]-sigmatropic rearrangements of hydrogen shift have been of considerable theoretical and experimental interests during the past several decades.[1,2] In this paper, a group of intramolecular proton transfers in hydrocarbons and heteroatom substituted analogues, including twelve 1,3- and twelve corresponding 1,5-sigmatropic rearrangements (Scheme 1), have been investigated at the QCISD(T)/6-3 1 1G(d,p)∥B3LYP/6-311++G(d,p) level of theory.……

A QSRR Study on the Relative Retention Time of Halogenated Methyl-phenyl Ethers

Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.

A One-dimensional Pseudo-helical Coordination Polymer with 4,4′-(Hexafluoroisopropylidene)bis(benzoic acid)

The title complex [Zn2（hfipbb）2（2,2′-bpy）2], 1 has been hydrothermally synthesized from Zn（NO3）2·6H2O, 4,4′-（hexafluoroisopropylidene）bis（benzoic acid） and 2,2′-bipyridine. Singlecrystal X-ray analysis reveals that 1 presents a one-dimensional coordination polymer with pseudo-helical chain structure. Two Zn（Ⅱ） atoms in an unsymmetrical unit of 1 adopt distorted octahedral and square-pyramidal coordination geometries, respectively. The packing of parallel chains gives a three-dimensional supramolecular network supported by π-π stacking interactions. Crystal data： C54H32F12N4O8Zn2, Mr = 1223.58, monoclinic, space group P2 1/c, a = 27.557（6）, b = 16.751（3）, c = 11.350（2） A, β= 99.21（3）°, V= 5171.5（18） A^3, Z= 4, Dc = 1.572 g/cm^3, F（000） = 2464, μ= 1.030 mm^-1, the final R = 0.0552 and wR = 0.1070 for 6631 observed reflections （I〉 2σ（I））.

Three-dimensional Quantitative Structure-activity Relationship Models of HIV-1 Integrase Inhibitors of DKAs

As one of the three viral encoded enzymes of HIV-1 infection, HIV-1 integrase has become an attractive drug target for the treatment. Diketoacid compounds （DKAs） are one kind of potent and selective inhibitors of HIV-1 IN. In the present work, two three-dimensional QSAR techniques （CoMFA and CoMSIA） were employed to correlate the molecular structure with the activity of inhibiting the strand transfer for 147 DKAs. The all-oritation search （AOS） and all-placement search （APS） were used to optimize the CoMFA model. The diketo and keto-enol tautomers of DKAs were also used to establish the CoMFA models. The results indicated that the enol was the dominant conformation in the HIV-1 IN and DKAs complexes. It can provide a new method and reference to identify the bioactive conformation of drugs by using QSAR analysis. The best CoMSIA model, with five fields combined, implied that the hydrophobic field is very important as well as the steric and electrostatic fields. All models indicated favorable internal validation. A comparative analysis with the three models demonstrated that the CoMFA model seems to be more predictive. The contour maps could afford steric, electrostatic, hydrophobic and H-bond information about the interaction of ligand-receptor complex visually. The models would give some useful guidelines for designing novel and potent HIV-1 integrase inhibitors.

Theoretical Study on Enol-keto Tautomerism of α-Fluorine-β-diketones

Density Functional Theory method is applied to investigate the enol-keto tautomerism of both acyclic and cyclic α-fluorine-β-diketones. It is shown that, for acyclic cases, α-fluorine could improve the relative stability of keto tautomer by lessening intramolecular hydrogen bond of enol form, whereas the relative stability of cyclic enol could be attributed to two factors： destabilization of keto and stabilization of enol. Furthermore, the relative stabilities of all enol tautomers are improved in THF to different extents.

Response to weaning and dietary L-glutamine supplementation:metabolomic analysis in piglets by gas chromatography/mass spectrometry

A novel metabolomic method based on gas chromatography/mass spectrometry(GC-MS)was applied to determine the metabolites in the serum of piglets in response to weaning and dietary L-glutamine(Gln)supplementation.Thirty-six 21-d-old piglets were randomly assigned into three groups.One group continued to suckle from the sows(suckling group),whereas the other two groups were weaned and their diets were supplemented with 1%(w/w)Gln or isonitrogenous L-alanine,respectively,representing Gln group or control group.Serum samples were collected to characterize metabolites after a 7-d treatment.Results showed that twenty metabolites were down-regulated significantly(P<0.05)in control piglets compared with suckling ones.These data demonstrated that early weaning causes a wide range of metabolic changes across arginine and proline metabolism,aminosugar and nucleotide metabolism,galactose metabolism,glycerophospholipid metabolism,biosynthesis of unsaturated fatty acid,and fatty acid metabolism.Dietary Gln supplementation increased the levels of creatinine,D-xylose,2-hydroxybutyric acid,palmitelaidic acid,andα-L-galactofuranose(P<0.05)in early weaned piglets,and were involved in the arginine and proline metabolism,carbohydrate metabolism,and fatty acid metabolism.A leave-one-out cross-validation of random forest analysis indicated that creatinine was the most important metabolite among the three groups.Notably,the concentration of creatinine in control piglets was decreased(P=0.00001)compared to the suckling piglets,and increased(P=0.0003)in Gln-supplemented piglets.A correlation network for weaned and suckling piglets revealed that early weaning changed the metabolic pathways,leading to the abnormality of carbohydrate metabolism,amino acid metabolism,and lipid metabolism,which could be partially improved by dietary Gln supplementation.These findings provide fresh insight into the complex metabolic changes in response to early weaning and dietary Gln supplementation in piglets.

Halogen Bonding： An AIM Analysis of the Weak Interactions

A series of complexes formed between halogen-containing molecules and ammonia have been investigated by means of the atoms in molecules （AIM） approach to gain a deeper insight into halogen bonding. The existence of the halogen bond critical points （XBCP） and the values of the electron density （Pb） and Laplacian of electron density （V2pb） at the XBCP reveal the closed-shell interactions in these complexes. Integrated atomic properties such as charge, energy, polarization moment, volume of the halogen bond donor atoms, and the corresponding changes （△） upon complexation have been calculated. The present calculations have demonstrated that the halogen bond represents different AIM properties as compared to the well-documented hydrogen bond. Both the electron density and the Laplacian of electron density at the XBCP have been shown to correlate well with the interaction energy, which indicates that the topological parameters at the XBCP can be treated as a good measure of the halogen bond strength In addition, an excellent linear relationship between the interatomic distance d（X…N） and the logarithm of Pb has been established.