Abstract: As a group phenomenon, human variables exhibit a rhythm with a period (tau) equal to 24 h. However, healthy human adults may differ from one another with regard to the persistence of the 24-h periods of a set of variables' rhythms within a given individual. Such an internal desynchronization (or individual circadian dyschronism) was documented during isolation experiments without time cues, both in the present study involving 78 male shift workers and in 20 males and 19 females living in a natural setting. Circadian rhythms of sleep-wake cycles, oral temperature, grip strength of both hands, and heart rate were recorded, and power-spectra analyses of individual time series of about 15 days were used to quantify the rhythm period of each variable. The period of the sleep-wake cycle seldom differed from 24 h, while rhythm periods of the other variables exhibited a trimodal distribution (tau = 24 h, tau > 24 h, tau < 24 h). Among the temperature rhythm periods which were either < 24 h or > 24 h, none was detected between 23.2 and 24 h or between 24 and 24.8 h. Furthermore, the deviations from the 24-h period were predominantly grouped in multiples of +/- 0.8 h. Similar results were obtained when the rhythm periods of hand grip strength were analyzed (for each hand separately). In addition, the distribution of grip strength rhythm periods of the left hand exhibited a gender-related difference. These results suggested the presence of genetically controlled variability. Consequently, the distribution pattern of the periods was analyzed to elucidate its compatibility with a genetic control consisting of either a two-allele system, a multiple-allele system, or a polygenic system. The analysis resulted in structuring a model which integrates the function of a constitutive (essential) gene which produces the exact 24-h period (the Dian domain) with a set of (inducible) polygenes, the alleles of which, contribute identical time entities to the period. The time entities which affected the rhythm periods of the variables examined were in the magnitude of +/- 0.8 h. Such an assembly of genes may create periods ranging from 20 to 28 h (the Circadian domain). The model was termed by us “The Dian-Circadian Model.” This model can also be used to explain the beat phenomena in biological rhythms, the presence of 7-d and 30-d periods, and interindividual differences in sensitivity of rhythm characteristics (phase shifts, synchronization, etc.) to external (and environmental) factors.

Abstract: The present study was carried out to determine effect of different photoperiod regimes on sperm quality parameters,
ovulation/spermiation time and hatchery performance of rainbow trout (Oncorhynchus mykiss) broodstock. The designation
was done as combination of different long and short photoperiod regimes such as: 18L:6D and 18D:6L (group I); 14L:10D
and 14D:10L (group II) and natural lighting (control group). All treatments were carried out as three replications at each
group.
As a result, the highest mean spermatozoa motility (83.0±2.1 %) and motility period (67.2±6.3 s) were determined in
control group. It was determined that the longest ovulation was occured in female rainbow trout broodstock at 265 days in
group I. Although the highest mean absolute egg productivity was determined as 3654.7±298.3 eggs/fish in group I, the
highest mean relative egg productivity was determined as 137.3±24.5 eggs/kg in control group. Furthermore, the highest mean
egg diameter (4.6±0.1 mm) and fertilization rate (87.0±2.5 %) were determined in control group. Statistical analyses revealed
that spermatozoa motility, spermatozoa motility period and spermatozoa density positively correlated with fertilization rate in
all photoperiod regimes (P>0.05). On the other hand, semen volume and semen pH negatively correlated with fertilization rate
in all photoperiod regimes (P>0.05). It is interesting to note that only statistically important positive correlation was
determined between relative fecundity and fertilization rate in 18L:6D/18D:6L photoperiod regime (r=0.452, P<0.05).
Consequently, results revealed that combined long and short artificial photoperiod regimes can advance ovulation and
spermiation and also can effect gamete quality and hatchery performance of rainbow trout during out-of-season spawning.