The effect of a typical magnetic storm on mitosis in the embryo cells and the length and weight of roach (Rutilus rutilus L.) prolarvae

The action of the tested variants of a typical magnetic storm (MS) has a biological effect on cellular and organismal levels in the prolarva stage. The impact of this environmental factor leads to increased mitotic activity in blastocysts, it can trigger the early hatching of embryos, and it has no negative impact on the size-weight characteristics of free embryos.     

Some morphological features of roach <Emphasis Type="Italic">Rutilus rutilus</Emphasis> (Cyprindae) fry after exposure to toxicants in the early stages of ontogenesis (vertebral phenotypes,plastic features,and fluctuating assymetry)

Roach Rutilus rutilus eggs developed in low-concentration solutions of trichlorfon (10^?6, 10^?5, 10^?4, 10^?3, and 10^?2 mg/l) or N-methyl-N’-nitro-N-nitrosoguanidin (MNNG) with 0.3 mg/l concentration for 54 h after fertilization. Roach fry from different experimental variants differed from the control in terms of growth rate and number of vertebrae in the spinal column and its sections. Irrespective of a change in the direction of growth rate, the number of vertebrae in the spinal column and diversity of vertebral phenotypes increased. The number of vertebrae and Shannon’s index of vertebral column phenotype diversity correlated with the number of anomalies in the structure of axial skeleton. Body proportions of fish with anomalies change due to shortening of deformed fragments of the vertebral column: relative indices of head length and maximum body depth increase. Regarding dispersion of fluctuating asymmetry for the number of openings of seismosensory system in the frontale, dentale and praeoperculum, insignificant differences from the control were found in two cases only: it was lower for the number of openings in dentale in fry exposed to trichlorfon with a concentration of 10^?5 mg/l, and higher for the number of openings in praeoperculum in the variant with MNNG.     

Effect of ultralow concentrations of N-methyl-N′-nitro-N-nitrosoguanidine upon early development in roach (<Emphasis Type="Italic">Rutilis rutilus</Emphasis>): Intestine carbohydrase activities and kinetic characteristics of carbohydrate hydrolysis in the intestine of underyearlings

The prolonged effects of short-term action of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in low concentrations 3 × 10^?7 to 3 × 10^?1 mg/l upon roach (Rutilus rutilus) early development have been studied. It was revealed that the treatment resulted in an increase in fish length and weight, in a decrease in total amylolytic and saccharase activities, and in different changes in parameters of di-and polysaccharide hydrolyses. The concentration-effect dependence is nonlinear. Both ultralow and the highest tested MNNG concentrations cause similar changes in carbohydrase activities and kinetic parameters of carbohydrate hydrolysis. The decrease in K _m values of sucrose hydrolysis evidencing the increase in the enzyme to substrate affinity may be attributed to adaptive reactions of roach at early developmental stages in response to damaging embryotoxic action of MNNG in ultralow concentrations.     

Effect of N-methyl-N-nitro-N-nitrosoguanidine upon early development in roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis>): Characteristics of mitoses in germ cells,hatching dynamics and morphology of larvae

Fertilized roach (Rutilus rutilus) eggs were incubated for the first 48 h in 3 × 10^?7 to 3 × 10^?1 mg/l N-methyl-N-nitro-N-nitrosoguanidine (MNNG) solutions. The incubation resulted in changes in blastomere mitotic indices and an increase in the number of aberrant mitoses. The concentration dependence of the studied parameters is described by a nonlinear curve. Egg incubation in a tested MNNG concentrations range leads to decrease in larvae length and weight.     

Variability in development of bilateral parts of the brain during ontogenesis of roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis>)

A study exploiting the gravimetric method did not reveal identical development of paired parts of the roach (Rutilus rutilus) brain. In the studied sample, the proportion of fish with left or right asymmetry of this organ was 1: 1. The specificity of fluctuating asymmetry in studied plastic parameter depending on the fish age and growth was analyzed. In the ontogenetic sequence, from yearlings to nine-year-old fishes, the higher level of developmental instability was revealed in elder fish, six and more years old. Noted anatomical-morphological feature is likely determined by not only imperfect morphogenesis during early development: potential decrease in the threshold of noise immunity against unfavorable external and internal factors during later stages of fish development may contribute to the feature noted above. The analysis of sex-related traits revealed that in males fluctuating asymmetry of the brain bilateral parts is more pronounced.     

On the impact of low concentrations of chlorophos in the period of early ontogenesis on digestive carbohydrases of underyearlings of roach Rutilus rutilus

The remote effects of brief exposure to low doses of chlorophos (1 × 10^?6 ?1 × 10^?2 mg/l) in the period of early ontogenesis of roach Rutilus rutilus have been studied. Diverse changes of the activity of carbohydrases and of the kinetic characteristics of the hydrolysis of di-and polysaccharides in experimental under-yearlings are revealed. Especially interesting are the data on the greater effect of superlow concentrations on changes of the kinetic characteristics; in some cases adaptive changes in the affinity of enzymes to the substrate are recorded.     

The impact of hypomagnetic conditions and light deprivation on mitosis of germ cells and body length of prelarvae in roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis> L.)

The impact of light deprivation, geomagnetic deprivation, and the combination of these factors on the mitosis of germ cells in roach embryos and the body length of hatched prelarvae have been studied. It has been shown that geomagnetic deprivation leads to changes in the ratio of blastomeres that pass through initial and final phases of mitosis and the increase in the mitotic index of germ cells. The number of chromosomal abnormalities and body length of prelarvae change as well. An additive effect of the embryos exposure to the combination of light and geomagnetic deprivation is expressed as a significant increase in the number of aberrant mitosis and the body length of prelarvae.     

The effect of a temporal shift in diurnal geomagnetic variation on roach Rutilus rutilus L. embryos: A comparison with effects of simulated geomagnetic storms

A study was made of the effects that 6- and 12-h shifts in diurnal geomagnetic variation relative to the night–day light cycles exert on roach Ritulus ritulus L. embryos. Either temporal shift in diurnal geomagnetic variation stimulated blastomere proliferation and early prelarval hatching in exposed embryos compared to controls. Underyearlings developing from exposed embryos displayed higher locomotor activity in a plusshaped maze, a lower number of rays in the anal fin, a redistribution of vertebrae through sections of the vertebral column, and a higher number of seismosensory system openings in the mandibular and preopercular bones. The effects were similar to those described previously for roaches exposed to a simulated geomagnetic storm during embryonic development. The results support the hypothesis that animals perceive geomagnetic storms as a dramatic disturbance that occurs in the habitual diurnal geomagnetic variation at an unusual time relative to the night–day light cycle, which acts as a primary zeitgeber of circadian biological rhythms.