Involvement of spleen components of mature fowl in the primary and secondary humoral antibody response following experimental EDS'76 virus infection

Summary

Cellular changes in spleens of mature fowl in relation to both the primary and secondary humoral antibody response following experimentalEDS'76 virus infection were studied. The influence of splenectomy on humoral antibody response was also examined.

Experimental fowl had been naturally infected with fowl adenovirus (FAV) but did not possess precipitins to these viruses at the time of EDS’ 76 virus infection. Since EDS'76 infection provokes a recall of the group antibody to FAV, this infection simultaneously induces a primary response against EDS’ 76 virus and a secondary response due to the recall of the group antibody to FAV.

HI and precipitating antibodies toEDS'76 virus (primary response) werefirst detected at 6 and 8 days p.i. respectively. Curves of HI, precipating and neutralising antibody titres were biphasic; the first peak (IgM peak) occurred at 10–11 days p.i., the second (IgG peak) at 16–28 days p.i.

Precipitating antibodies to FAV (secondary response) were demonstrated from 4 days p.i. The curve of these antibody titres was also biphasic, with peaks at the same times as in the primary response.

Based on HI and AGP testing of primary and secondary immune response in both splenectomised and non‐splenectomised fowl it is concluded that in the primary response the spleen of the adult fowl is involved significantly in only IgM secretion, while in the secondary response it is likely that bothIgM and IgG are secreted in considerable amounts.

Clusters of lymphoblasts and plasmablasts were observed at 3 days p.i. in the red pulp. It is very likely that antigen‐antibody complexes are formed from that time and circulate bound to the surface of lymphocytes. These antigen‐loaded lymphocytes are ‘picked up’ from the blood stream by

– red pulp macrophages, leading to enhanced formation of lymphoblasts in the red pulp. Great numbers of these cells (which are very probably IgM secreting cells) were present on days 6 and 7 p.i., but were no longer detectable after day 10 p.i.

– macrophages of the macrophagalellipsoidal corona (MEC), leading to significant enlargement of the periellipsoidal lymphoid tissue(PELT) by an increase of the number of lymphocytes observedfrom days 4–12 p.i. The MEC was significantly enlarged from 7–12 days p.i., very likely due to an increased number of macrophages.

Following deposition of antigen in the white pulp, formation of follicles begins. The number of small, intact follicles includingfollicle precursors increasedfrom 6 days p.i. From 15 days p.i. to the end of the experiment both the number and size of follicles increased significantly.

Uptake and processing of antigen by macrophages is probably accompanied by death of some of these cells. This might explain the degenerative changes observed in large mesenchymal cells, probably macrophages, at 3 and 5 days p.i. in the red pulp and at 5 and 6 days especially in the MEC. Splenitis which was present at 3 and 5 days p.i. and oedema observed in and around ellipsoidal cells at 5 days p.i. may be due to mediators released from these degenerative macrophages.

A significantly increased number of follicles with lymphoblasts was seen from 2–15 days p.i. while lymphoblasts and plasmablasts were present in the PELT from 5–15 days p.i., but predominantly at 6 and 7 days p.i. It is likely that disruption of follicles and blast transformation of white pulp lymphoid cells are secondary response events. White pulp lymphoblastsand plasmablastsare probably IgG secreting cells.

Splenomegaly was observed at 3, 5 and 6 days after infection and was mainly due to swelling of red pulp macrophages and infiltration of granulocytes in the red pulp. Ellipsoidal and periellipsoidal changes could contribute to the splenomegaly at 5 and 6 days p.i.     

轻轨(地下段)振动环境影响分析及应用实例

指出了振动环境影响评价是城市轨道交通建设项目环境影响评价的重点评价专题,剖析了轻轨(地下段)振动环境影响评价重点值得关注的几个问题,结合实例进一步探讨了城市快速轨道交通对环境振动产生的影响,为污染防治提供依据。     

九龙口湿地水环境与生态恢复分析

指出了湿地是自然界最富生物多样性的生态景观和人类最重要的生存环境之一,不仅具有丰富的资源,还具有巨大的环境调节功能和环境效益。通过对九龙口湿地水环境的分析,提出了湿地恢复与重建的方案。     

土壤科学与社会发展简论

指出了土壤在农业生产中起着基础性的作用,土壤科学的发展在人类社会的发展中也起到了重要的作用,它提供给人类生存居所及粮食物品,同时对人类所生存的生态环境条件起到了保障性的作用。就当前土壤科学与社会发展最为密切的三个领域展开了论述,指出了在社会的发展过程中,土壤科学的地位与作用越来越不容忽视,在经济社会发展的过程中,土壤科学的重要性应当进一步引起我们的重视,因为在经济发展过程中对土壤环境的破坏必然会阻碍经济社会的进一步发展,所以我们必须合理利用土壤资源,并不断推动现代土壤科学对社会发展的有益影响。     

宁强县茶叶产业发展对策建议

近现代科学研究证实茶叶富含多种有益的成分,具有良好的保健功能。伴随经济发展,茶叶消费日趋旺盛：在市场上,茶叶是一种快速消费品;在农业上,茶叶则是一种极宜作为产业发展的经济作物。宁强县是江北地区的一个产茶大县,其茶叶具有独特的品质特征。为明析该县茶叶生产现状,在查阅相关资料的基础上,本文对该县生态环境状况、茶叶发展现状进行了概述,对茶业发展中的问题进行了探讨,以期为该县茶叶生产和发展提供参考。     

Benefits of Re-Integrating Livestock and Forages in Crop Production Systems

SUMMARY

Specialization is the foundation of contemporary agriculture, yet until the early decades of the 20th century, enterprise diversity was the norm. As agriculture has become more specialized in the intervening years, yields have increased dramatically, but so too have a range of economic, environmental, and health problems. This contribution presents evidence that specialization is an ecologically dysfunctional design for food production, a thesis which is supported by the predominance of problem-solving research in the contemporary literature. As demonstrated by Louis Bromfield in the 1940s and by organic and sustainable farmers today, the strategic integration of crops and livestock/ forage enterprises avoids many of the problems of specialization, while also capturing economic and ecological synergies denied to specialist producers. In addition to providing human foodstuffs, forage-based livestock production also offers a range of novel opportunities to channel natural processes to the service of humanity, from carbon sequestration and site remediation to non-chemical vegetation management.     

四种樟属树种幼树的光合生理特性比较

采用Li-6400光合测定仪系统研究了樟属树种香樟、岩桂、天竺桂、猴樟的幼树在不同生长季节的田间光合生理特性.结果表明,4种樟属树种幼树在春季、夏季的净光合速率日变化都呈“双峰”型曲线变化,出现典型的“光合午休”现象,并且第一峰值高于第二峰值;而在秋季各树种幼树的净光合速率日变化则都呈“单峰”型曲线变化.4种树幼树的光合作用生理指标各不相同,但光适应能力均较强;其中,净光合速率高低排序为香樟、猴樟、天竺桂、岩桂,光饱和点高低排序为香樟、猴樟、天竺桂、岩桂,光补偿点高低排序为天竺桂、猴樟、岩桂、香樟,表观量子效率高低排序为香樟、猴樟、天竺桂、岩桂,CO2补偿点高低排序为猴樟、天竺桂、岩桂、香樟.多元逐步回归分析结果表明,影响净光合速率的关键环境因子随树种不同而变化,对香樟的净光合速率有显著影响的因子是光合有效辐射、气孔导度和胞间CO2浓度,对岩桂和天竺桂的净光合速率有显著影响的因子是气温、气孔导度和胞间CO2浓度,对猴樟的光合速率有显著影响的因子是光合有效辐射和气温.     

转基因作物生物安全的研究进展及问题

近20年来,转基因技术发展迅速,并逐渐形成强大的生物技术产业.随着转基因作物及产品的不断涌现,转基因生物安全问题成为公众关心的焦点.文中主要探讨了转基因作物对人体健康和生态环境2大方面产生的争议,以期使读者对转基因有一个科学的认识.     

鸭梨无公害生产环境及栽培量化指标与调控技术研究

通过多年来的系统研究,明确了鸭梨无公害生产的环境质量指标,制定了鸭梨无公害栽培果实品质性状、树体结构、产量水平及效益指标,以及果实重金属和农药残留限量指标,集成配套了相适应的栽培调控技术,包括水分调控、配方施肥、平衡修剪、疏花疏果、人工授粉、梨果套袋、病虫防治及适期采收等8项关键技术,为鸭梨实现无公害高品质栽培,提高国内外市场竞争力,增加经济效益和出口创汇提供了科学依据。