舒城县干汊河镇农村集体“三资”管理现状与建议

阐述了舒城县干汊河镇农村集体"三资"管理取得的成效,指出了管理过程中存在的问题,并提出了加强农村集体"三资"管理的建议。     

Pharmacokinetics of xylazine after 2-, 4-, and 6-hr durations of continuous rate infusions in horses

Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg⁻¹ hr⁻¹ for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration–time curves following bolus and CRI were best described by a one-compartment model. No differences were found between pharmacokinetic estimates of the CRIs for the fractional elimination rate constant (K_e), half-life (t_1/2e), volume of distribution (V_d), and clearance (Cl). Median and range were 0.42 (0.15–0.97)/hr, 1.68 (0.87–4.52) hr, 5.85 (2.10–19.34) L/kg, and 28.7 (19.6–39.5) ml min⁻¹ kg⁻¹, respectively. Significant differences were seen for area under the curve ( ) (p < .0002) and maximum concentration (C_max) (p < .04). This indicates that with increasing duration of infusion, XYL may not accumulate in a clinically relevant way and hence no adjustments are required in a longer XYL CRI to maintain a constant level of sedation and a rapid recovery.     

Carbon stocks and carbon fluxes from a 10‐year prescribed burning chronosequence on a UK blanket peat

Prescribed burning is a common land management technique in many areas of the UK uplands. However, concern has been expressed at the impact of this management practice on carbon stocks and fluxes found in the carbon‐rich peat soils that underlie many of these areas. This study measured both carbon stocks and carbon fluxes from a chronosequence of prescribed burn sites in northern England. A range of carbon parameters were measured including above ground biomass and carbon stocks; net ecosystem exchange (NEE), net ecosystem respiration (R_eco) and photosynthesis (P_g) from closed chamber methods; and particulate organic carbon (POC). Analysis of the CO₂ data showed that burning was a significant factor in measured CO₂ readings but that other factors such as month of sampling explained a greater proportion of the variation in the data. Carbon budget results showed that whereas all the plots were net sources of carbon, the most recent burn scars were smaller sources of carbon compared with the older burn scars, suggesting that burning of Calluna‐dominated landscapes leads to an ‘avoided loss’ of carbon. However, this management intervention did not lead to a transition to a carbon sink and that for carbon purposes, active peat‐forming conditions are desirable.     

Greater humification of belowground than aboveground biomass carbon into particulate soil organic matter in no-till corn and soybean crops

Quantifying the amount of carbon (C) incorporated from decomposing residues into soil organic carbon (C_S) requires knowing the rate of C stabilization (humification rate) into different soil organic matter pools. However, the differential humification rates of C derived from belowground and aboveground biomass into C_S pools has been poorly quantified. We estimated the contribution of aboveground and belowground biomass to the formation of C_S in four agricultural treatments by measuring changes in δ¹³C natural abundance in particulate organic matter (C_POM) associated with manipulations of C₃ and C₄ biomass. The treatments were (1) continuous corn cropping (C₄ plant), (2) continuous soybean cropping (C₃), and two stubble exchange treatments (3 and 4) where the aboveground biomass left after the grain harvest was exchanged between corn and soybean plots, allowing the separation of aboveground and belowground C inputs to C_S based on the different δ¹³C signatures. After two growing seasons, C_POM was primarily derived from belowground C inputs, even though they represented only ∼10% of the total plant C inputs as residues. Belowground biomass contributed from 60% to almost 80% of the total new C present in the C_POM in the top 10 cm of soil. The humification rate of belowground C inputs into C_POM was 24% and 10%, while that of aboveground C inputs was only 0.5% and 1.0% for soybean and corn, respectively. Our results indicate that roots can play a disproportionately important role in the C_POM budget in soils. Keywords Particulate organic matter; root carbon inputs; carbon isotopes; humification rate; corn; soybean.     

Effect of miR-19a on lipid catabolism in hepatocyte LO2

AIM: To observe the effect of microRNA-19a (miR-19a) on the lipid catabolism of hepatocyte LO2, and to explore the potential mechanism. METHODS: miR-19a was over-expressed or silenced by transfection of miR-19a mimics or miR-19a inhibitor into LO2 cells, then the mRNA level of miR-19a was detected by real-time PCR. The potential target of miR-19a was found by the method of bioinformatics through internet website. The effect of miR-19a on the 3' UTR of peroxisome proliferator-activated receptor α (PPARα) was measured by dual luciferase reporter assay, and the protein level of PPARα and its 2 major downstream rate-limiting enzymes involved in lipid catabolism, acyl-coenzyme a dehydrogenase (ACADM) and carnitine palmitoyltransferase 1A (CPT1A), were detected by Western blotting. Meanwhile, the effect of miR-19a on the generation of ketone body was measured by beta-hydroxybutyric acid (β-OHB) detection assay. RESULTS: The mRNA level of miR-19a was dramatically elevated by the transfection of miR-19a mimics, and sharply decreased by the transfection of miR-19a inhibitor (P<0.05). PPARα was found as a potential target of miR-19a, and dual luciferase reporter assay and Western blotting confirmed the regulatory effect of miR-19a on the expression of PPARα, with the protein level changes of ACADM and CPT1A. miR-19a mimics down-regulated, while miR-19a inhibitor up-regulated the concentration of β-OHB in LO2 cells (P<0.05). CONCLUSION: miR-19a regulates the lipid catabolism of hepatocytes by targeting the PPARα and its 2 downstream rate-limiting enzymes.     

Indicators and trade-offs of ecosystem services in agricultural soils along a landscape heterogeneity gradient

Soil functions can be classified as supporting (nutrient cycling) and provisioning (crop production) ecosystem services (ES). These services consist of multiple and dynamic functions and are typically assessed using indicators, e.g. microbial biomass as an indicator of supporting services. Agricultural intensification negatively affects indicators of soil functions and is therefore considered to deplete soil ES. It has been suggested that incorporating leys into crop rotations can enhance soil ES. We examined this by comparing indicators of supporting soil services – organic carbon, nitrogen, water holding capacity and available phosphorous (carbon storage and nutrient retention); net nitrogen mineralisation rate and microbial biomass (nutrient cycling and retention) – in barley fields, leys and permanent pastures along a landscape heterogeneity gradient (100, 500 and 1000 m radii). In addition, barley yields (provisioning service) were analysed against these indicators to identify trade-offs among soil services. Levels of most indicators did not differ between barley and ley fields and were consistently lower than in permanent pastures. Leys supported greater microbial biomass than barley fields. Landscape heterogeneity had no effect on the indicators or microbial community composition. However, landscape heterogeneity correlated negatively with yield and soil pH, suggesting that soils in heterogeneous landscapes are less fertile and therefore have lower yields. No trade-offs were found between increasing barley yield and the soil indicators. The results suggest that soil ES are determined at the field level, with little influence from the surrounding landscape, and that greater crop yields do not necessarily come at the expense of supporting soil services.     

Cross‐linked polyacrylates in post‐mining substrates: persistence and effects on plant growth

Application of hydrophilic polymers composed of cross‐linked polyacrylate can improve soil water‐holding capacity and accelerate the restoration of post‐mining substrates. In this work, we studied the persistence of a polyacrylate polymer incorporated into a soil and its impact on plant nutrients at a reclamation site of former lignite mining in Lusatia (Germany). In contrast to autumn application, the incorporation of the polymer enhanced the sequestration of plant‐derived carbon in the soil, which was reflected by a significant increase in the concentration of a lignin marker. Attenuated total reflexion–Fourier transform infrared spectra (ATR‐FTIR) and total elemental contents in the applied polymer suggested an intensive cation exchange between the polymer framework and the soil‐forming substrate. In addition, there was an enrichment of carbonaceous material, which seems to reduce the swelling and thus the water‐holding capacity of the cross‐linked polyacrylate. Conversely, this process protected the polymer structure from rapid decomposition.     

呼伦贝尔地区苜蓿人工草地CO_2通量变化特征

试验采用密闭箱技术对呼伦贝尔地区种植的苜蓿人工草地进行碳通量研究,采用反硝化-分解作用模型(DNDC)进行模拟。试验结果表明:对苜蓿人工草地CO2通量24h连续观测发现,CO2通量全天变化的平均值(238.15mg/(m2·h)与11∶00(245.32mg/(m2·h)的通量变化值接近,试验从早上9∶00~11∶00进行温室气体的采集方法合理、可行;在整个生长季变化表明,7、8月CO2通量变化较显著(P0.05),且受到降水的影响较大,伴随降水的发生,CO2通量会发生不同幅度的变化,土壤温度和含水量对CO2通量有一定的影响(r0.45,P0.05);通过DNDC模型的模拟,能较好的反映苜蓿人工草地CO2通量的变化情况,但模拟结果数值普遍有些偏高。     

浅议保护性耕作技术推广过程中存在的问题及解决途径

土地采用保护性耕作方法,可有效的防止水土流失,增加土壤蓄水能力,提高雨水利用率,培肥地利,增加土壤有机质,减少耕作次数,降低生产成本,各种农作物增产明显。     

持续被动运动通过抑制软骨细胞NO合成下调MMP-1和MMP-13表达

目的：观察持续被动运动（CPM）和补充一氧化氮（NO）供体——硝酸甘油（NG）对兔骨关节炎（OA）模型中软骨基质金属蛋白酶-1（MMP-1）和MMP-13表达以及NO含量的影响，探讨CPM下调MMPs的可能机制。方法：30只3~4月龄雄性新西兰大白兔，其中6只进行假手术作为正常对照组（NC组），另外24只建立膝关节OA模型，术后随机分为4组，即OA对照组（OA组）、OA硝酸甘油给药组（NG组）、OA持续被动运动组（CPM组）、OA持续被动运动+硝酸甘油给药组（CPM+NG组），每组各6只。NC组和OA组不作处理，NG组给予NG软膏膝关节局部涂抹，CMP组在CPM训练仪上进行膝关节持续被动运动，CMP+NG组即在运动干预的同时给予NG局部涂抹。4周后取各组软骨组织，硝酸还原酶法测定NO含量，HE染色观察软骨形态学变化并进行Mankin''s评分，实时荧光定量PCR（RQ-PCR）检测MMP-1和MMP-13 mRNA水平，免疫组织化学法测定MMP-1和MMP-13蛋白表达量。结果：NO含量、Mankin''s评分以及MMP-1和MMP-13 mRNA和蛋白水平在OA组明显高于NC组（P<0.01），NG组高于OA组（P<0.01），CPM组低于OA组和NG组（P<0.01），CPM+NG组低于NG组（P<0.01），但高于CPM组（P<0.01）。结论：CPM通过抑制软骨细胞NO合成下调MMP-1和MMP-13表达，进而对软骨细胞起保护作用。