大头网柄菌的个体发育

【背景】网柄细胞状黏菌是生物学、细胞学及发生生物学研究中一类重要的模式生物,至今已报道了百余种,但每个种的个体发育过程不是很明晰。【目的】了解网柄细胞状黏菌的个体发育。【方法】对采自云南苍山的土壤样品进行网柄菌的分离、培养和鉴定,并详细记录其个体发育全阶段特征。在传统形态学方法基础上,对样品进行基因组18S测序,并将获得序列在GenBank注册。通过双凹载玻片及水琼脂培养基添加大肠杆菌的培养方法,显微观察样品的发育过程,包括孢子、黏变形体、集群、假原质团、拔顶、孢堆果的发育特征。【结果】分离得到大头网柄菌Dictyostelium macrocephalum;该种温度适应范围较广,是亚热带和热带的广布种;其完成一个生活循环历时3 d,接种20 h后孢子开始萌发释放黏变形体,第50 h形成集群,第56 h假原质团形成,第58 h孢堆原形成,第71 h孢堆果完全成熟。【结论】研究分离的大头网柄菌为云南省新记录种,增加了其在我国亚热带的新分布区;明确了该种的个体发育过程。

Ontogeny of Dictyostelium macrocephalum

Background] Dictyostelids cellular slime molds are model organisms for biology, cytology and developmental biology. Although more than one hundred species of dictyostelids have been reported up to now, the developmental process of each species is still unclear. Objective] To understand the ontogenetic characteristics of this group. Methods] Dictyostelids were isolated and identified from soil samples collected from Cang Mountain in Yunnan Province. The ontogeny of isolated dictyostelid species were investigated. The 18S sequences of this species were sequenced. The morphological features and 18S sequence were used to identify the taxonomic status. Furthermore, the development from spore to spore including characteristics of spore, myxamoeba, aggregation, pseudoplasmodia, ascent, and sorocarp were microbiologically observed on bi-concavity slide and water agar in this paper. Results] Dictyostelium macrocephalum was obtained and identified. It adapt a wide range of temperatures, which suggested that this dictyostelid species is common species distributing in subtropical and tropical area. The whole life cycle of D. macrocephalum extends of a period of less than 3 d (71 h). The spores germinated and released myxomoebae 20 h after inoculation. The aggregations formed 50 h after the inoculation, whereas the pseudoplasmodia formation needed 56 h. After that, the sorogen formed needed 56 h, and finally form fruiting sorocarps after 71 h. Conclusion] This new record of Yunnan Province, D. macrocephalum, extented our understanding on the distribution of this species in subtropical areas of China. The developmental process of D. macrocephalum was clarified.