杏果实发育过程中有机酸积累与相关代谢酶的关系

以新世纪杏为试材,测定了果实发育过程中有机酸质量分数及相关代谢酶—柠檬酸合成酶(CS)、磷酸烯醇式丙酮酸羧化酶(PEPC)、乌头酸酶(ACO)和苹果酸脱氢酶(MDH)的活性,并对果实中有机酸积累与酶活性的关系进行了分析。结果表明,杏果实有机酸主要有苹果酸和柠檬酸,成熟果实中苹果酸占总酸量的95%以上,在果实发育过程中,有机酸质量分数缓慢上升,花后51d达最大值,之后逐渐下降。相关分析表明,苹果酸质量分数与MDH活性呈正相关,与CS活性及ACO活性呈负相关。柠檬酸质量分数与CS活性呈正相关,与MDH活性呈显著负相关,相关系数为-0.8675*。研究认为,CS、MDH和ACO是杏果实有机酸积累的主要酶,PEPC的作用不大。

氮磷钾配比施肥对巨尾桉叶片及根系有机酸质量分数的影响

采用正交L9（3^4）试验设计，研究不同氮（N）磷（P）钾（K）配比施肥下巨尾桉GL9（ Ecu alyptus grandis＆#215; E．urophylla）叶片、根系中有机酸种类及质量分数和根系有机酸酶活性。结果表明：叶片有机酸质量分数是根系的4．03～6．64倍；与对照（CK）相比，N3P2K1、N2P3K1的叶片有机酸质量分数分别比CK低7．44％和19．70％，其余配比均比CK高；而根系中N1P2K2、N1P3K3、N2P3K1的有机酸质量分数比CK低22．02％～31．07％，有机酸质量分数越低，表明巨尾桉的养分越均衡，肥料的元素配比越合理。叶片中苹果酸、柠檬酸、乙酸占所有酸的85．21％～95．32％，根系中苹果酸及柠檬酸占所有酸的54．99％～85．21％。相关分析表明，叶片与根系的总有机酸质量分数均与苹果酸、柠檬酸显著相关（ p＜0．05），这两种酸作为巨尾桉的优势酸，可能是植物遭受养分胁迫的指示型酸；而有机酸酶PEPC、NAD－IDH酶活性与根系有机酸质量分数显著相关（p＜0．05），PEPC是促进巨尾桉根系苹果酸、柠檬酸积累的重要酶，NAD－IDH是与有机酸分解相关的酶。 N素和P素是影响有机酸的主要因子，高氮低磷的配比加剧植物养分胁迫，产生更多的有机酸。综合分析表明，中氮高磷低钾的配比即N2P3K1遭受的养分胁迫最小，有机酸的质量分数最低，推荐最佳N、P2O5、K2O施肥量分别为15、9、6 g·株^-1。

关于杏果实发育过程中有机酸代谢酶的几个问题讨论

以新世纪杏为试材,测定了果实发育过程中有机酸代谢酶—柠檬酸合成酶(CS)、磷酸烯醇式丙酮酸羧化酶(PEPC)、乌头酸酶(ACO)和苹果酸脱氢酶(MDH)的活性,并对果实中有机酸积累与酶活性的关系进行了分析。结果表明:苹果酸含量与MDH活性呈正相关,与CS活性及ACO活性呈负相关。柠檬酸含量与CS活性呈正相关,与MDH活性呈显著负相关,相关系数为-0.8675*。研究认为,CS,MDH和ACO是杏果实有机酸积累的主要酶,PEPC的作用不大。

Effects of Metal Ions and Organic Solvents on Alkaline Phosphatase from Rice-field Eel

[Objective]The mechanism of alkaline phosphatase（ALP） was studied to promote rice-field eel aquaculture industry. [ Method] The effects of effectors such as multiple metal ions and organic solvents on ALP in viscera of rice-field eel. [ Result] Na^＋ and K ^＋ didn＇t generate big influences on enzyme activity;Mg^2＋ and Ca^2＋ could promote ALP while Li^＋,Cu^2＋ and Zn^2＋ could restrain ALP enzyme activity. Both HPO4^2- and WO4^2- generated by en- zyme catalyzing disodium phenyl phosphate possessed strong inhibitory effects on emzymc, and 9.5 mmol/L HPO4^2 - would make enzyme activity decline by 13% while 9.5 mmol/L WO4^3- would make enzyme decline by 34%. The inhibition types of them were both competitive inhibition on enzyme activity. The organic solvents such as methanol, ethanol,ethylene glycol,isopropannl all generated influences on ALP and the order according to their inhibitory effects was isopropanol 〉 ethanol 〉 methanol 〉 ethylene glycol. [ Conclusion] The inflncnces of various effeetors on ALP aetivity of rice-field eel were studied from dynamics perspective to provide theoretical basis for further clarifying ALP mechanism.

Effects of Exogenous Organic Acids on Dehydrogenase Activity in Dark Brown Forest Soils under Nutrient Deficiency

Objective] This study aimed to investigate the effects of exogenous or-ganic acids on dehydrogenase activity in dark brown forest soils under nutrient defi-ciency. [Method] Different proportions of A1 and B horizon dark brown forest soils （A1∶B=1∶2） were utilized to establish soil conditions with nutrient deficiency for cultivation of Larix olgensis seedlings. The effects of oxalic acid, citric acid and succinic acid on dehydrogenase activity in dark brown forest soils under nutrient deficiency were studied systematical y by adding different concentrations of organic acid solutions. [Result] Under nutrient deficiency, dehydrogenase activity in dark brown forest soils was reduced significantly, and the reduction increased with the extension of stress duration. Most organic acid treatments improved dehydrogenase activity in nutrient-deficient dark brown forest soils, and the effects varied with different treatment du-ration and types and concentrations of organic acids. Furthermore, 10.0, 5.0 and 10.0 mmol/L organic acid treatments exhibited the most significant effects on day 10, 20 and 30, respectively. The increment of dehydrogenase activity in different durations showed a downward trend of 30 d〉20 d〉10 d; the improvement effects of three organic acids on dehydrogenase activity showed a downward trend of succinic acid〉 citric acid〉oxalic acid. [Conclusion] Exogenous organic acids improved signifi-cantly dehydrogenase activity in dark brown forest soils under nutrient deficiency and also improved the microbial activity and soil fertility to a certain extent.

Pickering interfacial biocatalysis with enhanced diffusion processes for CO_(2) mineralization

Utilization of carbon dioxide(CO_(2))has become a crucial and anticipated solution to address environmental and ecological issues.Enzymes such as carbonic anhydrase(CA)can efficiently convert CO_(2) into various platform chemicals under ambient conditions,which offers a promising way for CO_(2) utilization.Herein,we constructed a Pickering interfacial biocatalytic system(PIBS)stabilized by CA‐embedded MOFs(ZIF‐8 and ZIF‐L)for CO_(2) mineralization.Through structure engineering of MOFs and incorporation of Pickering emulsion,the internal and external diffusion processes of CO_(2) during the enzymatic mineralization were greatly intensified.When CO_(2) was ventilated at a flow rate of 50 mL min^(–1) for 1 h,the pH value of PIBS dropped from~8.00 to~6.50,while the average pH value of free system only dropped to~7.15,indicating that the initial reaction rate of CO_(2) mineralization of PIBS is nearly twice that of the free system.After the 8^(th) cycle reaction,PIBS can still produce more than 9.8 mg of CaCO_(3) in 5 min,realizing efficient and continuous mineralization of CO_(2).

Effect of Organic vs. Inorganic Selenium Supplementation on Expression of Selected Defensin Genes in Somatic Milk Cells of Dairy Cows

The aim of the study was to evaluate the impact of organic selenium supplementation （selenium yeast） vs. inorganic selenium （selenium selenite） on the expression of selected defensin genes in milk somatic cells （MSC） of dairy cows. Sixteen Polish Holstein-Friesian cows in second parity, with similar milk yield and milk composition were randomly divided into two equal groups. At the beginning of experiment, the animals were in the middle of their lactation curve （150, standard deviation （SD） = 26 d） and this experiment lasted 90 d. The basic diet, for both groups, consisted of corn silage, wilted grass silage and concentrates. The diet of control group was supplemented with commercial mineral and vitamin mixture with inorganic selenium and the for the experimental group daily selenium need was covered by the addition of Se-yeast （6 mg Se/cow/d）. Milk samples were collected three times during experiment （before experiment; on day 55; after the end the experiment）. Total RNA was isolated from milk somatic cells and the levels of transcripts of bovine β1-defensin （DEFB1）, β4-defensin （BNBD4）, β5-defensin （BNBDS）, β10-defensin （BNBD10） and lingual antimicrobial peptide （LAP） were measured with real time PCR, using glyceraldehyde 3-phosphate dehydrogenase （GAPDH） as a reference gene. The expressions of almost all studied genes were influenced by environmental conditions （very low and negative temperature）. However, BNBD4 （P 〈 0.05） and LAP （P ≤ 0.001 ） genes were influenced by selenium supplementation but in opposite ways, depending on the form of Se. These findings support that selenium is an important factor affecting the mRNA level in MSC, but the effect of the form of selenium might depend on genes.