Effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia (Rachycentron canadum)

This experiment was conducted to investigate the effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia (Rachycentron canadum). Six isonitrogenous diets were prepared to vary in lipid-to-carbohydrate ratio (g/g) as follows: D1, 2.26; D2, 1.31; D3, 0.78; D4, 0.47; D5, 0.34; and D6, 0.23. Cobias were fed to satiety for 8 weeks. The weight gain and protein efficiency ratio in D1 group were significantly lower than those in other groups (P < 0.05), accompanied by a lower level of feed conversion ratio (P < 0.05). Protein retention efficiency in D4 and D6 and whole body protein in D4 and D5 were significantly higher than those in D1 group (P < 0.05). Survival rate in D4 group was the highest among all groups and was significantly higher than that in D1, D2 and D5 (P < 0.05). In terms of serum triglyceride, D1 and D2 were significantly higher than D6 (P < 0.05). Hepatosomatic index in D3 and D4 was significantly lower than that in D1 (P < 0.05). Fructose-1,6-diphosphatase in D4 was significantly higher than that in D1 and D3 (P < 0.05). Phosphofructokinase in D3 and D4 and malic enzyme in D4 and D5 were significantly higher than those in other groups (P < 0.05). Results indicate that cobia utilizes carbohydrates as energy source more efficiently than it utilizes lipids. The optimal lipid-to-carbohydrate ratio in juvenile cobia diets is 0.47.     

Energy metabolism and apoptotic effect of microwave radiation on rat myocardial cells

AIM: To investigate the effect of microwave radiation at different intensities on the rat myocardium and its possible mechanism.METHODS: The rats were radiated by the intensity of 500, 1 000, 1 500 and 2 000 W/m² with 2 450 MHz microwave for 6 min. The heart tissue was collected 6 h after microwave radiation. ATP and mitochondria complex Ⅳ and Ⅴ were measured. The changes of the tissue structures were observed under transmission electron microscope. The apoptosis of the myocardial cells was detected by a cell analyzer. The protein level of cleaved caspase-3 was determined by Western blotting.RESULTS: The concentration of ATP and activity of mitochondria complex Ⅳand Ⅴ signi-ficantly decreased compared with control group in the cardiac tissues. The decreased number, morphological abnormalities such as dissolved cavitation, matrix and obvious tumefaction of mitochondria were observed under transmission electron microscope. The microwave radiation induced the apoptosis of myocardial cells in the rats. The cell apoptotic rate and the protein level of cleaved caspase-3 increased with increasing intensity of microwave radiation(P<0.05).CONCLUSION: Microwave radiation has obvious injury effect on the rat heart, which can cause cardiac energy metabolism dysregulation and cardiac myocyte apoptosis.     

Abnormally modified tau and hypoxic-ischemic brain damage

Tau is the most abundant microtubule-associated protein in the brain. If tau protein lost the normal function, the toxic effect should be showed and plays an important role in various central nervous system lesions. Hypoxic-ischemic encephalopathy (HIE) is an important cause of mortality in the neonatal period and it is mainly characterized by neurological deficits such as cognitive limitations. However, the mechanism still needs further study, and the underlying relationship between tau protein and HIE lacks direct evidence. Some recent clinical study reported that tau protein expression elevated in the serum of asphyxia children and had a high correlation with behavior deficient. In this review, we focus on 3 key points to provide new insights to understand the tau protein-related pathogenesis of HIE as followed: (1) tau protein and its phosphorylation change during central nervous system development; (2) comparison of tau protein expression in developing brain and adult brain under some neurological disorders; (3) potential pathological change of tau in HIE related pathological conditions, such as dysmyelination, inflammation response and glutamate metabolism.     

Effect of Lysine Supplement on the Digestion and Metabolism of the Rumen in Small-tail Han Sheep

5 male Small-tail Han sheep with the body weight of 45 kg at 1.5 years old,fitted with permanent rumen fistula,to study of the effect of the supplement of the untreated commercial lysine on the rumen microbiocoenosis,rumen metabolism and whole body metabolism by 5×5 Latin square design (5 groups:control,control with low urea (equal nitrogen),low lysine,control with high urea (equal nitrogen),high lysine).The amounts of lysine-HCl supplement were 0,4.0 and 8.0 g/kg diet (as DM basis) in each group respectively,with two urea supplement control groups of equal amount of nitrogen.The results showed that by supplement of 4.0 and 8.0 g/kg of lysine-HCl diet (as DM basis) respectively,the voluntary intake of dry matter of sheep were increased by 5.5%(P>0.05) and 11.8%(P<0.05) respectively.The total amount of rumen bacteria were increased by 18.9%(P<0.01) and 23.9%(P<0.01) respectively,as the amount of rumen Coccus was increased by 21.2%(P<0.01) and 30.1%(P<0.01) respectively.The amount of rumen big Bacillus was decreased by 16.7%(P<0.05) and 33.3%(P<0.01) respectively.The total VFA of was increased by 9.6%(P<0.05) and 12.2%(P<0.01) respectively,as the butyric acid was increased by 12.8%(P>0.05) and 20.2%(P<0.01) respectively.The apparent digestibility of organic matter was increased by 6.4%(P>0.05) and 10.0%(P<0.05) respectively,the apparent digestibility of crude protein was increased by 7.0%(P>0.05) and 18.3%(P<0.01) respectively;And nitrogen retention was increased by 46.4%(P>0.05) and 110.7%(P<0.01) respectively.However,there was no effect of lysine supplement on the amounts of the rumen protozoa and fungi,and the concentration of rumen ammonia nitrogen.It was concluded that the supplement of untreated commercial lysine to adult sheep would increase the voluntary intake,digestibility,nitrogen retention the rumen microbiocoenosis and the total amount of rumen bacteria,especially the rumen Coccus of adult sheep.The effect of lysine supplement could not be replaced by urea supplement completely.     

Characterization of Nitrate-Reducing and Amino Acid–Using Bacteria Prominent in Nitrotoxin-Enriched Equine Cecal Populations

Horses can be at risk for nitropoisoning by consuming plants containing 3-nitro-1-propionic acid or 3-nitro-1-propanol and to a lesser extent by plants containing nitrate. Populations of equine cecal microbes enriched for enhanced rates of 3-nitro-1-propionic acid (NPA) or nitrate metabolism were cultured for NPA- or nitrate-metabolizing bacteria on basal enrichment medium or tryptose soy agar supplemented with either 5-mM NPA or nitrate and under H₂:CO₂ (20:80) as the energy source. After 72 hours, separated colonies picked from plates, or roll tubes were cultured in fresh broth medium for 72 hours and then identified by 16S rRNA gene sequencing. Isolates from the NPA-enriched populations were identified as Streptococcus lutetiensis (five strains), Escherichia coli (two strains), and Sporanaerobacter acetigens (one strain). Strains isolated from nitrate-enriched populations were identified as Escherichia coli (one strain) and Wolinella succinogenes (three strains). None of these strains degraded NPA. Enriched populations of equine cecal microbes, the isolated pure strains and the type strain of Denitrobacterium detoxificans, a competent NPA-metabolizing microbe, were examined using denaturing gradient gel electrophoresis (DGGE). The DGGE analysis indicated that none of the strains in the enriched population of equine cecal microbes were similar to D. detoxificans. However, we report for the first time the isolation of the anaerobic amino acid–using Sporanaerobacter acetigenes from the equine cecum.     

5‐Aminolevulinic Acid Activates Antioxidative Defence System and Seedling Growth in Brassica napus L. under Water‐Deficit Stress

The present study assesses the effects of 5‐aminolevulinic acid (ALA, 0, 0.1, 1 and 10 mg l^?1) on the growth of oilseed rape (Brassica napus L. cv. ZS758) seedlings under water‐deficit stress induced by polyethylene glycol (PEG 6000, 0 and ?0.3 MPa). Water‐deficit stress imposed negative effects on seedling growth by reducing shoot biomass, cotyledon water potential, chlorophyll content and non‐enzymatic antioxidants (glutathione and ascorbic acid) levels. On the other hand, water‐deficit stress enhanced the malondialdehyde (MDA) content, reactive oxygen species (ROS) production, enzymatic antioxidants activities, reduced/oxidized glutathione ratio (GSH/GSSG) and reduced/oxidized ascorbic acid (ASA/DHA) ratio in seedlings. Application of ALA at lower dosages (0.1 and 1 mg l^?1) improved shoot weight and chlorophyll contents, and decreased MDA in rape seedlings, whereas moderately higher dosage of ALA (10 mg l^?1) hampered the growth. The study also indicated that 1 mg l^?1 ALA improved chlorophyll content, but reduced MDA content and ROS production significantly under water‐deficit stress. Lower dosages of ALA (0.1 and 1 mg l^?1) also enhanced GSH/GSSG and ASA/DHA as compared to the seedlings under water‐deficit stress. The antioxidant enzymes (ascorbate peroxidase, peroxidase, catalase, glutathione reductase and superoxide dismutase) enhanced their activities remarkably with 1 mg l^?1 ALA treatment under water‐deficit stress. It was also revealed that 1 mg l^?1 ALA treatment alone induced the expression of APX, CAT and GR substantially and under water‐deficit stress conditions ALA treatment could induce the expression of POD, CAT and GR to a certain degree. These results indicated that 0.1–1 mg l^?1 ALA could enhance the water‐deficit stress tolerance of oilseed seedlings through improving the biomass accumulation, maintaining a relative high ratio of GSH/GSSG and ASA/DHA, enhancing the activities of the specific antioxidant enzymes and inducing the expression of the specific antioxidant enzyme genes.     

DTA-6对两种食用豆生理代谢及产量的影响

为探究2-N,N-二乙氨基乙基己酸酯（diethyl aminoethyl hexanoate,DTA-6）对食用豆叶片的生理代谢及产量的调控效应,选用芸豆（英国红）和小豆（龙垦2号）为试验材料,采用大田完全随机试验方法,于芸豆和小豆的初花期叶面喷施DTA-6,以喷施清水为对照（CK）,测定各生育时期叶片光合参数、碳代谢产物、干物质、产量及产量构成因素。结果表明：DTA-6提高了2种食用豆各生育期的SPAD值、盛花期和鼓粒期的净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）和胞间CO₂浓度（C_i）,显著增加了叶片蔗糖和可溶性糖的含量,促进了叶片淀粉的积累;与CK相比,DTA-6提高了2种食用豆的地上部单株干物质积累量,并且显著提高了芸豆和小豆鼓粒期荚分配率;DTA-6可有效调控2种食用豆的单株荚数、单株粒数和百粒重,从而提高产量,DTA-6处理的芸豆和小豆产量分别较CK增加13.30%和12.91%,增产显著。     

Oxygen isotope ratios of plant available phosphate in lowland tropical forest soils

Phosphorus (P) cycles rapidly in lowland tropical forest soils, but the process have been proven difficult to quantify. Recently it was demonstrated that valuable data on soil P transformations can be derived from the natural abundance of stable oxygen isotopes in phosphate (δ¹⁸O_P). Here, we measured the δ¹⁸O_P of soils that had received long-term nutrient additions (P, nitrogen, and potassium) or litter manipulations in lowland tropical forest in Panama and performed controlled incubations of fresh soils amended with a single pulse of P. To detect whether δ¹⁸O_P values measured in the incubations apply also for soils in the field, we examined the δ¹⁸O_P values after rewetting dry soils. In the incubations, resin-P δ¹⁸O_P values converged to ∼3.5‰ above the expected isotopic equilibrium with soil water. This contrasts with extra-tropical soils in which the δ¹⁸O_P of resin-P matches the expected equilibrium with soil water. Identical above-equilibrium resin-P δ¹⁸O_P values were also found in field soils that did not receive P additions or extra litter. We suggest that the 3.5‰ above-equilibrium δ¹⁸O_P values reflect a steady state between microbial uptake of phosphate (which enriches the remaining phosphate with the heavier isotopologues) and the release of isotopically equilibrated cell internal phosphate back to the soil. We also found that soil nutrient status affected the microbial turnover rate because in soils that had received chronic P addition, the original δ¹⁸O_P signature of the fertilizer was preserved for at least eight weeks, indicating that the off-equilibrium δ¹⁸O_P values produced during microbial phosphate turnover was not imprinted in these soils. Overall, our results demonstrate that ongoing microbial turnover of phosphate mediates its biological availability in lowland tropical soils.     

2株可培养细菌氮代谢特性的研究

研究旨在分析土壤中可培养细菌菌株的氮代谢特征,并进一步探讨微生物在土壤氮素转化中的可能作用机制。以2株分离自苹果园土壤的细菌菌株SY5-4和SY11-10为试材,采用传统培养方法结合分子检测技术,分别测定菌株生长特性及其氮素转化能力。研究结果表明,异养条件下,菌株SY5-4和SY11-10的世代时间分别为243.5 min和202.7 min。菌株生长过程中,培养液中铵态氮浓度始终维持在较高水平,铵态氮、亚硝态氮和硝态氮浓度均表现出先升后降的趋势。硝化（amoA和hao）和反硝化（nosZ、norB、nirK和nap）基因检测结果表明,菌株SY11-10具有多种氮素转化潜能。综上,供试菌株培养过程中,培养液中氮素发生变化,并在菌体中检测到不同氮转化基因,表明菌株参与多种氮代谢途径。     

不同包膜肥用量对油菜碳氮代谢产物和产量的影响

为研究包膜肥在直播早熟油菜上的应用效果,采用田间小区试验,探究不同用量包膜肥对‘湘杂油1613’碳氮代谢和籽粒产量的影响。结果表明,施肥量相同条件下,施用包膜肥油菜碳氮代谢活跃,叶绿素含量(SPAD)升高,可溶性糖和游离氨基酸总量增加,含量差异不明显;单株有效分枝数和角果数明显增加,每角果粒数和千粒重小幅提高。施用包膜肥增产效果明显,包膜肥施肥量为1500 kg/hm~2时产量最高,达到2066.9 kg/hm~2。通过拟合建模,包膜肥用量为1611.0 kg/hm~2时,产量达到最高为2164.9 kg/hm~2;而普通肥的用量为1870.5 kg/hm~2时,最高产量为1904.8 kg/hm~2,包膜肥产量增加13.6%,同时用量减少13.9%。