Effects of protein hydrolysate in weaning diets for Atlantic cod (Gadus morhua L.) and Atlantic halibut (Hippoglossus hippoglossus L.)

The study aims to test whether predigested dietary protein enhances the utilization of formulated diets at weaning, and also whether it stimulates intestinal maturation. In this study, Atlantic cod [ Gadus morhua L.; 41 days posthatch (dph)] and Atlantic halibut [ Hippoglossus hippoglossus L.; 63 days postfirst feeding (dpff)] were weaned onto diets with graded levels of protein hydrolysate. By increasing the inclusion of dietary protein as hydrolysate from 0 to 400 g kg⁻¹, cod increased the rate of survival from 7 ± 1% to 18 ± 2% (82 dph; regression, P =  4*10⁻⁷). In halibut, the survival rate decreased from 57 ± 9% to 22 ± 7% as the inclusion of protein in the form of hydrolysate increased from 0 to 450 g kg⁻¹ (119 dpff; regression, P =  8*10⁻⁵). Growth was not affected in any of the species. Results in specific activities of the intestinal enzymes leucine aminopeptidase (LAP) and alkaline phospatase (AP) supported the results in survival in halibut and partly also in cod, by showing increased activities in groups with increased survival ( anova , P <  0.05). The lower optimal level of hydrolysed protein in halibut than in cod is suggested mainly because of a slower feeding practice in halibut, which allows more extensive nutrient leaching before ingestion.     

软化病感染家蚕的碱性磷酸酶活力测定及病理学研究

为了研究感染软化病的家蚕碱性磷酸(ALKP)的活力并研究酶组织病理学,通过ALKP活力测定证实感染黑胸败血病的软化病家蚕ALKP,活力变化的规律与正常家蚕相似而单位更低．石蜡切片显示感病家蚕丝腺组织内充满丝胶类物质,家蚕吐丝结茧受阻．用冰冻切片法以ALKP反应底物对病蚕的丝腺组织进行活性测定,显示出感病家蚕的丝腺内外膜均呈现较强的酶反应,暗示了膜上活跃的磷酸转运系统．而脂肪体内的某些部位也呈现出点状深着色,证明脂肪体内含有ALKP,合成组织．     

性早熟中华绒螯蟹肝胰腺与性腺的酸性和碱性磷酸酶活性

采用磷酸苯二钠法在520nm波长测定了未成熟、早熟和正常成熟中华绒螯蟹肝胰腺与性腺中的酸性磷酸酶（ACP）和碱性磷酸酶（ALP）。结果表明：（1）各组蟹肝胰腺ACP和ALP活性都显著高于性腺;（2）早熟蟹肝胰腺中ACP活性都显著高于未成熟蟹而低于正常成熟蟹,在各发育阶段没有性别差异,但是,早熟雌蟹和正常成熟雌蟹卵巢中ACP活性都较早熟雄蟹和正常雄蟹精巢低,早熟与正常成熟个体没有差异;（3）早熟雌蟹肝胰腺ALP活性显著高于未成熟和正常成熟雌蟹,而与三组雄蟹处于同一水平,但是,早熟和正常成熟雌雄蟹的性腺中ALP活性没有显著差异。由此得出结论：（1）性腺发育所需营养物质的动员或合成主要与肝胰腺ACP有关;（2）性早熟的发生与肝胰腺中ACP和ALP活性的显著升高有关。     

有机解磷菌对天鹅湖潟湖沉积物中磷释放的影响

为探讨天鹅湖中有机解磷菌(OPB)的优势种属以及解磷菌对潟湖沉积物磷释放的影响,通过平板培养和16S rDNA序列分析对沉积物中OPB进行筛选鉴定,选取3株代表性菌株(Geobacillus stearothermophilus、Bacillus flexus、Bacillus altitudinis)在沉积物灭菌和非灭菌条件下进行模拟试验,探究OPB接种对上覆水总磷(TP)及沉积物碱性磷酸酶活性(APA)、磷赋存形态的影响。结果表明：芽孢杆菌属(Bacillus sp.)是天鹅湖冬季沉积物中OPB的优势属。沉积物是否灭菌对上覆水TP浓度影响显著,表现为灭菌组的3个接种处理的TP浓度均显著高于非灭菌组。OPB接种促进了天鹅湖沉积物中磷的释放,试验期间灭菌组各处理水体TP浓度变幅为0.049～0.335 mg·L^-1,其中弯曲芽孢杆菌(Bacillus flexus)和短小芽孢杆菌(Bacillus altitudinis)增幅较大。在试验结束时,大多数处理沉积物中APA和弱吸附态磷(NH₄Cl-P)含量明显增加,而可还原态磷(BD-P)和铁铝...     

Effects of a decade of organic fertilizer substitution on vegetable yield and soil phosphorus pools,phosphatase activities,and the microbial community in a greenhouse vegetable production system

Partial substitution of chemical fertilizers by organic amendments is adopted widely for promoting the availability of soil phosphorus (P) in agricultural production.  However, few studies have comprehensively evaluated the effects of long-term organic substitution on soil P availability and microbial activity in greenhouse vegetable fields.  A 10-year (2009–2019) field experiment was carried out to investigate the impacts of organic fertilizer substitution on soil P pools, phosphatase activities and the microbial community, and identify factors that regulate these soil P transformation characteristics.  Four treatments included 100% chemical N fertilizer (4CN), 50% substitution of chemical N by manure (2CN+2MN), straw (2CN+2SN), and combined manure with straw (2CN+1MN+1SN).  Compared with the 4CN treatment, organic substitution treatments increased celery and tomato yields by 6.9−13.8% and 8.6−18.1%, respectively, with the highest yields being in the 2CN+1MN+1SN treatment.  After 10 years of fertilization, organic substitution treatments reduced total P and inorganic P accumulation, increased the concentrations of available P, organic P, and microbial biomass P, and promoted phosphatase activities (alkaline and acid phosphomonoesterase, phosphodiesterase, and phytase) and microbial growth in comparison with the 4CN treatment.  Further, organic substitution treatments significantly increased soil C/P, and the partial least squares path model (PLS-PM) revealed that the soil C/P ratio directly and significantly affected phosphatase activities and the microbial biomass and positively influenced soil P pools and vegetable yield.  Partial least squares (PLS) regression demonstrated that arbuscular mycorrhizal fungi positively affected phosphatase activities.  Our results suggest that organic fertilizer substitution can promote soil P transformation and availability.  Combining manure with straw was more effective than applying these materials separately for developing sustainable P management practices.      

Effects of long-term phosphorus fertilizer inputs and seasonal conditions on organic soil phosphorus cycling under grazed pasture

Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long-term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remains unclear. We collected top-soil (0–75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha⁻¹ year⁻¹ of single super phosphate [SSP], and 376 kg ha⁻¹ year⁻¹ of SSP) for more than 65 years. Olsen P, microbial biomass P, and acid and alkaline phosphatase enzyme activities were measured regularly over a 2-year period. Pasture dry matter and soil chemical properties were also investigated. Results showed that long-term P inputs significantly increased pasture dry matter, total N, and the concentrations of ${\mathrm{NO}}_3^{–}$–N but significantly decreased soil pH and the concentrations of ${\mathrm{NH}}_4^{+}$–N. Total C was not affected by P fertilization. Although Olsen P significantly increased with increasing long-term P inputs, microbial biomass P was similar under P fertilized treatments. Long-term P inputs decreased acid phosphatase activity but increased alkaline phosphatase activity. Microbial biomass P was similar across seasons in the control but decreased in spring and autumn while increased in summer and winter under P fertilized treatments. Acid and alkaline phosphatase activities were significantly affected by season and followed similar seasonal trends being maximum in summer and minimum in winter regardless of P treatment. Correlation and principal component analysis revealed that acid and alkaline phosphatase activities were significantly positively correlated with soil temperature and significantly negatively correlated with soil moisture. In contrast, Olsen P and microbial biomass P were weakly correlated with environmental conditions. The findings of this study highlight the intertwined relationship between organic P cycling and the availability of C and N in soil systems and the need to integrate both soil moisture and temperature in models predicting organic P mineralization, especially in the context of global climate change.     

青稞酸性磷酸酶基因HvnACP2克隆和亚细胞定位研究

为了探索青稞酸性磷酸酶基因 HvnACP2的基因和蛋白结构特点，为青稞磷吸收利用机制研究提供基础。以青稞‘肚里黄’叶片为材料，根据植物基因组数据库Gramene中的大麦 HvACP2基因和启动子区域序列设计引物，通过PCR获得青稞 HvnACP2基因和启动子区域序列。采用生物信息学软件对 HvnACP2基因启动子区域元件以及蛋白理化性质、跨膜结构、磷酸化位点、信号肽、二级、三级结构进行分析。结果表明： HvnACP2有2个外显子和1个内含子，启动子区域有与分生组织、光响应、厌氧、茉莉酸和脱落酸相关的顺式作用元件。HvnACP2蛋白由454个氨基酸组成，分子质量为51 285.15 u,总原子数为7 058,亲水系数为-0.451,理论等电点为6.17,不稳定指数34.54,脂溶性指数为67.05。具有12个磷酸化位点和信号肽，不具有跨膜结构。 HvnACP2中α螺旋、延长链、β转角、无规则卷曲所占比例分别为18.72%、53.96%、23.57%、3.74%。 HvnACP2和其他物种的同源蛋白都有紫色酸性磷酸酶N末端结构域和金属酸性磷酸酶结构域，将 HvnACP2与其他植物的氨基酸序...     

刺槐丛枝菌根酸性磷酸酶的细胞化学研究

对接种从枝菌根真菌摩西球囊霉（Glomus mosseae 的刺槐幼苗进行酸性磷酸酶的细胞化学定位。结果表明,菌根中菌丝和从枝细胞膜均有酶反应,丛枝顶端细胞膜酶反应更为强烈,同时诱导宿主细胞膜产生酶反应对照的菌根细胞内入侵菌丝和根细胞间隙中的菌丝无酶反应。酸性磷酸酶能充分发挥水解大分子磷酸盐颗粒及降解丛枝中其它物质的作用,从而通过丛枝一宿主质膜界面供给宿主磷分、水分等营养物质。