Soluble organic nitrogen pools in greenhouse and open field horticultural soils under organic and conventional management: A case study

The aim of this study was to investigate the influence of four different horticultural management practices in open field and in greenhouse conditions under organic and conventional cultivation on the amount of soluble organic nitrogen (SON) present in the soil. Soils used in greenhouses and open field cultivation were sampled in Shanghai, China, where organic farming has been conducted for 3 years or conventional faming has been continued in the same area. The amounts of SON, nitrate (NO₃^?) and ammonium (NH₄⁺) were greater in the greenhouse soils than those under open field cultivation, which indicated a higher degree of soil management was imposed under greenhouse conditions. Greenhouse cultivation is also known to accelerate the turnover of SON in the soils, which may explain the significantly higher amounts of SON present in these soils. Organic farming, which does not use artificial fertilizers and pesticides, also resulted in significantly higher amounts of SON (average 42.10 mg kg^?1) compared with soils under conventional faming (24.59 mg kg^?1). The reasons for the observed differences in pool sizes of soluble inorganic nitrogen (SIN) and NO₃^? in the greenhouse soils and the open fields include (a) the heavy application of both complex fertilizer and organic fertilizer that exceeded crop requirements and (b) warmer temperatures and moist soils in the greenhouses, which are likely to lead to greater rates of N cycling compared with the open field soils. These results suggest that SON may be an important source of N in all horticultural systems, representing a pool of labile N readily available for plant growth. However, its concentration is less sensitive to different management practices than SIN. In contrast to SON, the total soluble nitrogen and inorganic N (SIN) pools varied widely with the different management practices although they were dominated by NO₃^? in all treatments. Soil organic N was positively related to dissolved organic carbon and NO₃^? contents. This relationship indicates that NO₃^? and dissolved organic matter play a key role in the retention of SON in soil.     

Evaluation of safety and pharmacokinetics of vancomycin after intraosseous regional limb perfusion and comparison of results with those obtained after intravenous regional limb perfusion in horses

OBJECTIVE: To evaluate the clinical effects and pharmacokinetics of vancomycin in plasma and synovial fluid after intraosseous regional limb perfusion (IORLP) in horses and to compare results with those obtained after IV regional limb perfusion (IVRLP). ANIMALS: 6 horses. PROCEDURES: 1 forelimb of each horse received vancomycin hydrochloride (300 mg in 60 mL of saline [0.9% NaCl] solution) via IORLP; the contralateral limb received 60 mL of saline solution (control). Solutions were injected into the medullary cavity of the distal portion of the third metacarpal bone. Synovial fluid from the metacarpophalangeal (MTCP) and distal interphalangeal (DIP) joints and blood were collected prior to perfusion and 15, 30, 45, 65, and 90 minutes after beginning IORLP, and synovial fluid from the MTCP joint only and blood were collected 4, 8, 12, and 24 hours after beginning IORLP. Plasma urea and creatinine concentrations and clinical appearance of the MTCP joint region and infusion sites were determined daily for 7 days. Results were compared with those of a separate IVRLP study. RESULTS: Clinical complications were not observed after IORLP. Mean vancomycin concentration in the MTCP joint was 4 microg/mL for 24 hours after IORLP. Compared with IORLP, higher vancomycin concentrations were detected in the DIP joint after IVRLP. Compared with IVRLP, higher vancomycin concentrations were detected in the MTCP joint for a longer duration after IORLP. CONCLUSIONS AND CLINICAL RELEVANCE: IORLP with 300 mg of vancomycin in a 0.5% solution was safe and may be clinically useful in horses. Intravenous and intraosseous routes may be better indicated for infectious processes in the DIP and MTCP joints, respectively.     

Prognostic impact of neoadjuvant aglepristone treatment in clinicopathological parameters of progesterone receptor‐positive canine mammary carcinomas

Neoadjuvant treatment of canine mammary carcinomas with the progesterone receptor (PR) antagonist aglepristone has a PR expression‐related inhibiting effect on proliferation index (PI). The aim of this study was to evaluate the effect of the treatment in the disease‐free period (DFP) and overall survival (OS) of canine mammary carcinomas. Fifty female dogs with mammary carcinomas were treated with aglepristone (n = 34) or oil vehicle (n = 16) before surgery (day 15). PR expression and PI were analysed by immunohistochemistry in samples taken at days 1 and 15. Epidemiological and clinicopathological data were assessed. DFP and OS data were retrieved every 4–6 months for at least 24 months after surgery. Aglepristone treatment increased DFP of animals bearing PR+ tumours with size smaller than 3 cm, complex and mixed tumours, with histologic grades I and II, and with PI ≤ 10%. Although further studies are necessary, current evidence points to treatment with aglepristone as useful for the management of canine mammary tumours.     

提高内切葡聚糖酶活力及其在毕赤酵母中的表达研究

以中性内切葡聚糖酶基因EG和真菌Corticium rolfsii的碳水化合物结合模块(FCBM)为模块,构建融合基因重构体EG-FCBM和CD-FCBM,并利用高效表达载体在毕赤酵母中对其进行高效表达。酶活及性质分析显示,EG-FCBM和CD-FCBM在诱导表达84~96h后,其对微晶纤维素的活力分别为951和676 U·mL-1,较原始基因EG(526U·mL-1)提高81%、28%,而酶学性质两者间无较大差异。这一结果表明,FCBM在催化水解纤维素的过程中有着极为重要的作用,通过增加FCBM来提高纤维素酶活性方法可行。     

重庆市北碚区耕地面积变化及其驱动力分析

利用重庆市北碚区2000—2012年的耕地面积和社会经济统计数据,分析其耕地资源的数量变化特征,采用主成分分析法定量分析了影响耕地面积变化的驱动因素,揭示了耕地面积变化的驱动机制。结果表明,北碚区耕地面积与人均耕地面积均呈现快速减少—缓慢减少的阶段变化特征;经济发展、农业发展因素、城市化水平和交通因素是影响北碚区耕地面积变化的四大主要驱动因子;可以从减少建设占用耕地、加强土地开发整理、加强高标准基本农田建设等方面达到保护耕地的目的。     

真鲷与黑鲷杂交与多倍体育种系列研究-Ⅰ

真鲷属于鲷科,真鲷属,分布于我国四大海域。黑鲷属于鲷科,鲷属,我国沿海均有分布。真鲷与黑鲷杂交属于属间远缘杂交。本研究利用春季繁殖的真鲷种群与春季繁殖的黑鲷种群进行交配。用HCG与LHRH-A_2催产,网箱内自然受精。正交以真鲷为♀,黑鲷为♂;反交以黑鲷为♀,真鲷为♂。两种杂交组合的雌雄性比均为1:1.5。正交组合的受精率为73％,反交组合为67％。正交组合的孵化率为85％,反交组合为87％。该研究证明海水鱼属间远缘杂交可以成功,并为海水鱼杂交育种推广应用奠定了基础。     

冬种黑麦草最终割草时间对早稻生长发育和产量的影响

通过田间试验研究了对冬种黑麦草最终刈割时间对早稻生长发育及产量的影响。结果表明,在所设计的４种时间间隔中,间隔１５ｄ的处理最为理想,对早稻的分蘖,生长高度,有效分蘖,穗长,千粒重和产量等性状在该处理条件下表现最佳,因此,建议ＩＲＲ系统中黑麦草和早稻前后作采用１５ｄ的间隔时间。     

搜爆犬自主作业能力的培养

随着我国经济的快速发展,社会矛盾逐渐步入凸显期,爆炸案及爆炸恐吓案的数量也在不断上升。作为搜爆现场的排头兵,搜爆犬的作用显得尤为重要,但是在搜索方式上,还有待改进。据笔者所知,我国许多地方现场使用搜爆犬     

美洲落葵的组织培养及快速繁殖

以美洲落葵试管苗的茎段为材料,通过正交实验设计,以平均增殖倍数和茎段平均长度为指标,对美洲落葵的组培快繁培养基进行了筛选.结果表明:MS 0.08 mg·L-1BA 0.03 mg·L-1NAA 0.5 mg·L-1GA3是最佳培养基,在该培养基中,5种材料的平均增殖倍数均在20倍以上,除U2外,茎段平均长度提高均在7 cm以上.在添加1/2 MS 0.03 mg/L的生根培养基中,7～10 d开始长根,15 d后即可长出1.0～2.0 cm的须根3～6条,生根率可达100%.     

Effectiveness of selection at CIMMYT's main maize breeding sites in Mexico for performance at sites in Africa and vice versa

The exchange of elite breeding materials across regions is an important way in which multinational maize breeding programmes access new genetic variation, improve efficiency and reduce costs. Our objectives were to examine whether CIMMYT's breeding programmes for tropical and subtropical environments in Mexico and Eastern and Southern Africa (ESA) can effectively share materials. Sets of selected and unselected lines were evaluated for per se and testcross performance in multiple environments in Mexico and ESA for grain yield, days to anthesis and plant height. Genotypic correlations between performance in Mexico and ESA as testcross and line per se were high (≥ 0.72) for all experiments, and indirect selection efficiency ranged from 67 to over 100% for all traits. Lines selected in ESA or Latin America performed equally well in each region, indicating selection was for broad rather than regional adaptation. Thus, breeding programmes of CIMMYT in both Mexico and ESA can benefit tremendously by exchanging breeding materials and test results, and elite selections from each region should be fast‐tracked for evaluation in the other.