Satralkar Moses K, Khare Padmakar V, Keny Vanlalhriatpuia L, Chhakchhuak Vanlalnghaka, Kasture Mahesh S, Shivagaje Ashok J, Iyyer Sunder B, Barnabas Rajneesh J, Joshi Dilip S
Zoology Department, Ahmednagar College, Ahmednagar, MS India.
Chronobiol Int. 2007;24(3):389-405. doi: 10.1080/07420520701420295.
The effects of varying photophase and altitude of origin on the phase angle difference (Psi) of the circadian rhythm of oviposition during entrainment to light-dark (LD) cycles and the aftereffects of such photophases on the period of the free-running rhythm (tau) in constant darkness (DD) were evaluated in two Himalayan strains of Drosophila ananassae, the high-altitude (HA) strain from Badrinath (5,123 m above sea level=ASL) and the low-altitude (LA) strain from Firozpur (179 m ASL). The Psi (i.e., the hours from lights-on of the LD cycle to oviposition median) of both strains was determined in LD cycles in which the photophase at 100 lux varied from 6 to 18 h/24 h. The HA strain was entrained by all LD cycles except the one with 6 h photophase in which it was weakly rhythmic, but the LA strain was entrained by only three LD cycles with photophases of 10, 12, and 14 h, but photophases of 6, 8, 16, and 18 h rendered it arrhythmic. Lights-off transition of LD cycles was the phase-determining signal for both strains as oviposition medians of the HA strain occurred approximately 6 h prior to lights-off, while those of the LA strain occurred approximately 1 h after lights-off. The Psi of the HA strain increased from approximately 2 h in 8 h photophase to approximately 11 h in 18 h photophase, while that of the LA strain increased from approximately 11 h in 10 h photophase to approximately 15 h in 14 h photophase. The aftereffects of photophase of the prior entraining LD cycles on tau in DD were determined by transferring flies from LD cycles to DD. The tau of the HA strain increased from approximately 19 to approximately 25 h when transferred to DD from LD 8:16 and LD 18:6 cycles, respectively, whereas the tau of the LA strain increased from approximately 26 to approximately 28 h when transferred to DD from LD 10:14 and LD 14:10 cycles, respectively. Thus, these results demonstrate that the photophases of entraining LD cycles and the altitude of origin affected several parameters of entrainment and the period of the free-running rhythm of these strains.
在两个喜马拉雅果蝇（Drosophila ananassae）品系中，评估了不同光期和起源海拔对产卵昼夜节律的相位角差（Psi）的影响，该相位角差是在适应明暗（LD）循环过程中产生的，同时还评估了这些光期对在持续黑暗（DD）中自由运行节律周期（tau）的后续影响。这两个品系分别是来自海拔5123米的巴德里纳特的高海拔（HA）品系和来自海拔179米的菲罗兹布尔的低海拔（LA）品系。在光照强度为100勒克斯的LD循环中，测定了两个品系的Psi（即从LD循环开灯到产卵中位数的小时数），其中光期在6至18小时/24小时之间变化。除了光期为6小时的LD循环（在此循环中该品系节律较弱）外，HA品系能被所有LD循环所驯化，但LA品系仅能被光期为10、12和14小时的三个LD循环所驯化，而光期为6、8、16和18小时的循环会使其失去节律。LD循环的熄灯转换是两个品系的相位决定信号，因为HA品系的产卵中位数大约在熄灯前6小时出现，而LA品系的产卵中位数大约在熄灯后1小时出现。HA品系的Psi从光期为8小时时的约2小时增加到光期为18小时时的约11小时，而LA品系的Psi从光期为10小时时的约11小时增加到光期为14小时时的约15小时。通过将果蝇从LD循环转移到DD中，确定了先前驯化LD循环的光期对DD中tau的后续影响。当分别从LD 8:16和LD 18:6循环转移到DD时，HA品系的tau分别从约19小时增加到约25小时，而当分别从LD 10:14和LD 14:10循环转移到DD时，LA品系的tau分别从约26小时增加到约28小时。因此，这些结果表明，驯化LD循环的光期和起源海拔影响了这些品系的几个驯化参数以及自由运行节律的周期。
