Baulina Olga, Gorelova Olga, Solovchenko Alexei, Chivkunova Olga, Semenova Larisa, Selyakh Irina, Scherbakov Pavel, Burakova Olga, Lobakova Elena
Department of Bioengineering, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia.
Department of Bioengineering, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia
FEMS Microbiol Ecol. 2016 Apr;92(4):fiw031. doi: 10.1093/femsec/fiw031. Epub 2016 Feb 15.
We report on common and strain-specific responses to nitrogen (N) starvation recorded in four closely related symbiotic Desmodesmus strains from taxonomically very distant animals (hydroids, a sponge and a polychaete) dwelling in the White Sea. A number of common for the studied strains and free-living microalgae as well as some specific patterns of acclimation to the N starvation were documented. The common responses included a slowdown of cell division, a reduction of photosynthetic apparatus and a vast expansion of storage subcompartments of the cell. Although these responses were qualitatively similar to those known in free-living chlorophytes, in the studied strains they occurred in a strain-specific manner. The specific N-starvation responses comprised formation of chloroplast envelope membrane twirls, thinning of the appressed thylakoid membranes and a loss of the luminal depositions and channeling of the fixed carbon to cell wall polysaccharide layer. Desmodesmus sp. from a hydroid featured a unique, among the studied strains, capability of 'emergency' degradation of Rubisco, apparently to salvage the N contained in this protein. The obtained results are discussed in view of the remarkable physiological plasticity of the symbiotic Desmodesmus spp. and their survival under the harsh conditions of the subarctic sea habitat.
我们报告了在来自白海的分类学上差异很大的动物（水螅、一种海绵和一种多毛纲动物）体内的四种密切相关的共生衣藻属菌株中记录到的对氮（N）饥饿的常见和菌株特异性反应。记录了一些在所研究的菌株和自由生活的微藻中常见的反应，以及一些适应氮饥饿的特定模式。常见反应包括细胞分裂减缓、光合装置减少以及细胞储存亚区室的大量扩张。尽管这些反应在性质上与自由生活的绿藻中已知的反应相似，但在所研究的菌株中，它们以菌株特异性的方式发生。特定的氮饥饿反应包括叶绿体包膜膜卷曲的形成、紧贴类囊体膜的变薄以及腔内沉积物的丧失，以及固定碳向细胞壁多糖层的转移。来自水螅的衣藻属菌株在所研究的菌株中具有独特的“紧急”降解核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）的能力，显然是为了挽救该蛋白质中所含的氮。鉴于共生衣藻属物种显著的生理可塑性及其在亚北极海洋栖息地恶劣条件下的生存情况，对所得结果进行了讨论。
