Epithelial response to experimentally introduced intraluminal bacteria in the avian epididymal ducts

The response of the epithelial cells of the various ducts of the avian epididymis, whose function is poorly understood, to intraluminal bacteria was evaluated by the injection of an avirulent strain of Salmonella gallinarium into the RT for 24 h. Ultrastructurally, bacteria and invading mononuclear cells were present in the lumina of the RT, proximal efferent ducts (PED) and distal efferent ducts. However, only the non-ciliated (Type I) cells of the PED epithelium ingested bacteria from the lumen. Fragments of bacteria also occurred in several intercellular spaces in the epithelium of the PED. Some mononuclear cells also contained fragments of bacteria. Neither cell death in the various epithelia nor mononuclear infiltration of the periductal tissue occurred. Therefore, in addition to the established function of absorbing most of the testicular fluid entering the epididymis, the Type I cells also appear capable of recognising and removing foreign particulate matter from the epididymal through-flow in the proximal part of the epididymis.     

Comparison of organic matter dynamics in soil between Japanese cedar (Cryptomeria japonica) forest and adjacent Japanese red pine (Pinus densiflora) forest established on flatland

In order to clarify the effects of tree species on organic matter dynamics in soil, we investigated the amount of forest floor material, leaf litter decomposition rate, soil chemical characteristics, soil respiration rate and cellulose decomposition rate in a Japanese cedar forest (cedar plot) and an adjacent Japanese red pine forest (pine plot) established on a flatland. The amount of forest floor material in the cedar plot was 34.5 Mg ha⁻¹ which was greater than that in the pine plot. Because the leaf litter decomposition rate was higher in the pine plot than in the cedar plot, it is likely that the difference in the amount of forest floor material between the plots is caused by the difference in the leaf litter decomposition rate. The C concentrations of soil in the cedar plot were 1.2–2.1 times higher than those in the pine plot. Soil pH(H₂O)s in the cedar plot were significantly higher than those in the pine plot. The soil respiration rates and the rates of mineralized C in the cedar plot byin vitro incubation were higher than those in the pine plot. From this result, it is assumed that soil organic matter in the cedar plot was decomposed relatively faster compared with the pine plot. Furthermore, microbial activities, which were reflected as cellulose decomposition rates in the cedar plot, were higher than those in the pine plot. A part of this paper was presented at the 109th Annual Meeting of the Japanese Forestry Society (1998).     

日本落叶松在旺苍县引种栽培初步研究

通过对旺苍县盐井河采育场10多年来引种栽培日本落叶松的结果与旺苍县外其它地区的引种栽培试验结果和本地华山松的生长情况进行对比分析,证明引种是成功的,进一步探讨了日本落叶松在旺苍的引种效果和生态适应性,提出了旺苍自然地理分布的引种适生区,是旺苍北部中山区主要速生造林树种之一。     

天然落叶松林树种组成的优化

为研究天然落叶松林的树种组成,对黑河地区１２２块样地的蓄积量和生长量进行聚类分析,并对分析结果和树种组成进行频率分析。研究结果表明：要保证天然落叶松林的高产,落叶松在林分中的比例应占绝对优势,但不完全是１００％。落叶松断面积在阴坡应控制在９０％￣９５％,在阳坡应控制在８５％￣９０％;落叶松株数在阴坡应控制在８６％￣９２％,在阳坡应控制在８０％￣８５％。     

落叶松杂种与亲本ISSR鉴别技术

以兴安落叶松（Larix gmelini）、长白落叶松（Larix olgensis）和日本落叶松（Larix Kaempferi）及其杂种子代当年生嫩叶为研究材料,采用ISSR分子标记技术对落叶松亲本与杂种进行了鉴别.结果表明:用ISSR16和ISSR19号引物扩增的特异条带能够分别鉴别兴安落叶松×长白落叶松杂交种和...     

人工林滑道接运与畜力集材效率的比较

采用现场数据收集和定量分析的方法，从集材距离和集材时间2个方面，对落叶松人工林畜力集材和滑道接运的效率进行比较研究，结果表明：随着集材时间和集材距离的增加，两种集材效率均降低。对于陡坡的落叶松人工林，畜力一滑道集材生产率要优于畜力集材生产率。