A CIRCADIAN RHYTHM OF MATING TYPE REVERSALS IN PARAMECIUM MULTIMICRONUCLEATUM SYNGEN 2 AND ITS GENETIC CONTROL
A CIRCADIAN RHYTHM OF MATING TYPE REVERSALS IN PARAMECIUM MULTIMICRONUCLEATUM SYNGEN 2 AND ITS GENETIC CONTROL
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DOI：
10.1002/jcp.1040670206
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发表时间：
1966-01-01
影响因子：
5.6
通讯作者：
BARNETT, A
中科院分区：
文献类型：
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作者：
BARNETT, A
两个新的等位基因，C和C，参与交配型的表达被证明。一个显性等位基因，C（循环），必须存在的节奏的表达，涉及一个连续的交替的2个互补的交配类型（III和IV）。培养物可以伴随着明暗循环。每个克隆的相可以通过其相对于给定光-暗循环的零时的HI到IV和IV到III的转变来表征。在无性繁殖过程中，相位是一个稳定的表型性状，但在有性繁殖过程中，相位不表现孟德尔分离。相反，相位是通过核分化来确定的，即，所述性状由不同确定的大核同源体（类核遗传）控制，所述同源体在接合后通常在第二细胞/分裂处分离。克隆在其遗传限度内的阶段是在夹带处理中使用的光组分和光强度的函数。通过检查一些克隆，发现交配型周期和诱导光暗周期之间的相位角不同。性不反应因而不表达节律的分裂细胞可以被诱导，在诱导之后，相位通过在连续黑暗或连续昏暗的光下以大于每天一次分裂的速率重复细胞复制而遗传。这一系统独有的结果表明，这种昼夜节律的阶段和周期的细胞过程通过重复的细胞复制持续存在（未表达：性反应需要轻微的饥饿），即使分裂周期比表达的昼夜节律周期短得多。在连续的黑暗或光照（持续6天）中，节律的昼夜周期小于24小时。交配型的逆转在较高强度的连续光照下停止。隐性等位基因c（无环）纯合的细胞不会逆转交配型，而是交配型III或IV，这也是核分化的结果。由于具有显性等位基因的个体细胞表达两种交配型，交配型的分化不能涉及大核中交配型决定因子的缺失。
Two new alleles, C and c, involved in mating type expression were demonstrated. A dominant allele, C(cycler), must be present for the expression of the rhythm involving a sequential alternation of the 2 complementary mating types (III and IV). Cultures can be entrained with light-dark cycles. The phase of each clone can be characterized by its HI to IV and IV to III transitions in relation to the zero hour of a given light-dark cycle. Phase is a stable phenptypic trait during asexual reproduction, but following sexual reproduction it does not display Mendelian segregation. Instead phase is determined through nuclear differentiation i.e., the trait is controlled by differently determined macronuclear analgen (caryonidal inheritance) which normally segregate at the second cell/division after conjugation. The phase of a clone within its genetic limits is a function of the photofractions and the light intensities used in the entraining treatment. By examining a number of clones a variety of phase angles between the mating type cycle and the entraining light-dark cycle are found. Dividing cells which are sexually unreactive and therefore do not express the rhythm can be entrained and following entrainment, phase is inherited through repeated cell replications at a rate greater than one fission a day in continuous darkness or continuous dim light. This result unique to this system indicates that the cellular processes underlying the phase and period of this circadian rhythm persist (unexpressed: sexual reactivity requires slight starvation) through repeated cell replications even when the division cycle is considerably shorter than the expressed circadian period. The rhythm has a circadian period in continuous darkness or light (ested for 6 days) of les than 24 hrs. The reversal of mating type ceases in continuous light at higher intensities. Cells homozygous for the recessive allele, c(acyclic), do not reverse mating type but are either mating type III or IV, again as a consequence of nuclear differentiation. Since individual cells with the dominant allele express both mating types, differentiation for mating type can not involve the absence in the macronucleus of mating type determining factors.