The prosthecae (stalks) of dimorphic caulobacters of the genera Caulobacter and Asticcacaulis are distinguished among such appendages by the presence of disk-like components known as stalk bands. Whether bands are added to a cell's stalk(s) as a regular event coordinated with the cell's reproductive cycle has not been settled by previous studies. Analysis of the frequency of stalks with i, i + 1, i + 2, etc. bands 'among more than 7,000 stalks of Caulobacter crescentus revealed that in finite (batch) cultures (in which all offspring accumulate), the proportion of stalks with i + 1 hands was regularly 50% of the proportion of stalks with i bands. This implied that the number of bands correlated with the number of reproductive cycles completed by a stalked cell. In chemostat-maintained perpetual cultures, the proportion was greater than 50% because stalked cells, with their shorter reproductive cycle times, contributed a larger proportion of offspring to the steady-state population than did their swarmer siblings. In Asticcacaulis biprosthecum cells, which bear twin prosthecae, the twins on a typical cell possessed the same number of bands. For both genera, stalk bands provide a unique morphological feature that could be employed in an assessment of age distribution and reproductive dynamics within natural populations of these caulobacters.
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机译:在这些附肢中,鳞茎杆菌属和曲霉属的双形Caulobacter的假体(茎)的区别在于存在被称为茎带的盘状成分。以前的研究尚未确定是否将条带作为与细胞繁殖周期相协调的常规事件添加到细胞的茎上。对带有i,i + 1,i + 2等带的茎的频率进行的分析表明,在7,000多棵新月形杆菌的茎中,发现在有限的(分批)培养物中(所有后代都在其中积累), i + 1手通常是带i的秸秆比例的50%。这暗示带的数量与茎细胞完成的生殖周期的数量相关。在由恒化器维持的永久性培养物中,该比例大于50%,因为与繁殖群相比,具有较短繁殖周期时间的茎细胞对稳态种群的后代贡献更大。在带有双胞胎假体的双孢假单胞菌细胞中,典型细胞上的双胞胎具有相同数量的条带。对于这两个属,茎带均具有独特的形态学特征,可用于评估这些花杆菌的自然种群内的年龄分布和生殖动力学。
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