[Courtship behavior, communicative sound production and resistance to stress in Drosophila mutants with defective agnostic gene, coding for LIMK1].

To elucidate the role of one of the main elements of signal cascade of actin remodeling--LIM-kinase 1 (LIMK1)--in the control of animal behavior we studied the characteristics of courtship behavior, parameters of acoustic communicative signals and their resistance to heat shock (HS, 37 degrees C, 30 min) in Drosophila melanogaster males from the strain with mutation in locus agnostic (agn(ts3)) containing gene CG1848 for LIMK1. The data obtained was compared with the results of our previous similar investigation on wild type CS males (Popov et al., 2006). Flies were divided into 4 groups. The males of control groups were not subjected to heat shock. The rest of males were subjected to heat shock either at the beginning of larval development when predominantly mushroom body neuroblasts are dividing (groups HS1), or at the prepupal stage when the brain central complex is developing (groups HS2), or at the imago stage one hour before the test (groups HS3). All males were tested at the age of 5 days. Virgin and fertilized CS females were used as courtship objects. Comparison of control groups of the two strains--CS and agnostic--have shown that the mutation agn(ts3) has no influence on the main parameters of courtship behavior of intact (not subjected to HS) males (courtship latency, the rapidity of achieving copulation, courtship efficiency) but leads to lowering of their sexual activity, increase of duration of sound trains in the songs and to slight increase of rate and stability of working of singing pacemakers. Agnostic males in comparison to wild type males are more resistant to HS given 1 hour before the test. After HS their courtship intensity does not decrease and the main parameters of their courtship behavior and communicative sound signals in comparison tu wild type males either do not change, or appear to be even better stabilized. The frequency of distorted sound pulses (an indicator of frequency of impairments in the activity pattern of neuro-motor circuits of the singing center) decreases, and the rate and stability of pacemakers of the pulse and the sine songs increases. So, the sharply elevated LIMK1 and p-cofilin concentrations in the cells of agn(ts3) mutants, in comparison to wild type males, leading to derangement of learning and memory (Medvedeva et al., 2008) are accompanied by decline of motivation of males but do not seriously influence the neuro-motor coordination during singing. The higher resistance of characterictics of their behavior and communicative sound signals to heat shock is in agreement with the fact that the extremely high LIMK1 and P-cofilin concentrations in their cells go down to normal values after HS. At the same time the amyloid aggregations disappear and normally defective learning and memory are restore.

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