Reactivation of Ribonucleic Acid and Protein Synthesis During Germination of Blastocladiella Zoospores and the Role of the Ribosomal Nuclear Cap
Reactivation of Ribonucleic Acid and Protein Synthesis During Germination of Blastocladiella Zoospores and the Role of the Ribosomal Nuclear Cap
复制标题
囊枝菌游动孢子萌发过程中核糖核酸的再激活和蛋白质合成以及核糖体核帽的作用
DOI：
10.1128/jb.96.4.962-969.1968
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发表时间：
1968
影响因子：
3.2
通讯作者：
J. S. Lovett
中科院分区：
文献类型：
--
作者：
J. S. Lovett
新鲜收获的芽枝霉游动孢子以每毫升106个游动孢子的密度接种到确定的生长培养基中后约15分钟开始萌发。鞭毛回缩伴随着包囊形成，核糖体核帽的分散在此后不久发生。初生假根在25 ~ 30 min开始出现，约25 ~ 30 min开始分支。第一次核分裂发生在120和190分钟之间。60分钟后每个细胞的干重线性增加，而每个细胞的脱氧核糖核酸在120和240分钟之间翻了一番。总核糖核酸（RNA）的线性增加是从40到45分钟开始检测到的，总蛋白质的线性增加是从80分钟开始检测到的;在核分裂期间，这两个过程都不会中断。包囊和核帽解体与前体掺入RNA和蛋白质的速率急剧上升有关。20 μg/ml的环己酰亚胺可阻止所有阶段的亮氨酸掺入，并抑制最早包囊形成阶段以后的发育。25 μg ~ 50 μg/ml的放线菌素D可阻止尿嘧啶掺入，但在40 ~ 45 min前对亮氨酸掺入或发育无影响。在后一阶段，放线菌素D可导致发育急剧停滞，并开始抑制亮氨酸掺入。它的结论是，早期的蛋白质合成必须发生在核糖体上形成在先前的生长阶段和保存通过游动孢子阶段在核帽。结果进一步表明，这种合成是依赖于信使RNA已经存在于游动孢子萌发前。
Freshly harvested zoospores of Blastocladiella emersonii begin to germinate about 15 min after inoculation into a defined growth medium at a density of 106 zoospores per ml. Flagellum retraction accompanies encystment, and dispersal of the ribosomal nuclear cap takes place shortly thereafter. The primary rhizoid begins to emerge at 25 to 30 min and starts to branch at ca. 60 min. The first nuclear division occurs between 120 and 190 min. The dry weight per cell increases linearly after 60 min, whereas the deoxyribonucleic acid per cell doubles between 120 and 240 min. A linear increase in total ribonucleic acid (RNA) is detectable beginning at 40 to 45 min, and in total protein beginning at 80 min; neither process is interrupted during nuclear division. Encystment and nuclear cap disorganization are associated with a sharp rise in the rates of precursor incorporation into RNA and protein. Cycloheximide at 20 μg/ml prevents leucine incorporation at all stages and inhibits development beyond the earliest encystment stage. Actinomycin D at 25 μg to 50 μg/ml prevents uracil incorporation, but it has no effect on leucine incorporation or development until 40 to 45 min. At the latter stage, actinomycin D causes a sharp developmental arrest and begins to inhibit leucine incorporation. It is concluded that early protein synthesis must occur on the ribosomes formed during the prior growth phase and conserved through the zoospore stage in the nuclear cap. The results further indicate that this synthesis is dependent upon messenger RNA already present in the zoospore before germination.