Yu. V. Chebotareva

The effect of an alternating electromagnetic field upon early development in roach (Rutilus rutilus: Cyprinidae, cypriniformes)

The effect of an alternating electromagnetic field (EMF) upon three stages of roach’s (Rutilus rutilus) early development was studied. The studies covered the periods before gastrulation; from gastrulation until hatching; and from hatching until yolk sac resorption. It has been shown that the EMF effect is as stronger as earlier in the embryogenesis the roach was subjected to an impact. The following responses to EMF were registered: earlier hatching of prelarvae, increase in the morphological diversity of juvenile fish, decrease in body lengths and weights, and changes in the number of vertebrae in yearlings.

Effects of an induced magnetic storm on the early ontogenesis of roach Rutilus rutilus (L.)

The influence that an induced magnetic storm (IMS) modeled in a confined volume has on the early ontogenesis of Rutilus rutilus was studied. The significant effects of the IMS were observed for the hatching rate of roach embryos, the size-weight and morphometric parameters of the fry, the variability of the vertebral column, and ontogeny stability in the roach offspring.

Effect of a magnetic field and copper upon activity of hydrolytic enzymes in roach (Rutilus rutilus) underyearlings

Remote effects of separate and combined exposure to copper (0.001 mg/L and 0.01 mg/L) and a low-frequency magnetic field during early embryogenesis in roach (Rutilus rutilus) underyearlings were studied. The study revealed that exposures lead to changes in the linear and weight parameters, activity of glycosidases, and kinetic characteristics of carbohydrates hydrolysis in the fish intestine. Copper decreases the activity of glycosidases and modifies the effect of a magnetic field. The exposure-induced decrease in the value of the seeming Michaelis constant of carbohydrate hydrolysis indicates the increase in the enzyme-substrate affinity. This phenomenon may be attributed to the adaptive reactions in response to negative effects of copper and a magnetic field during early ontogenesis in roach.

Effect of ultralow concentrations of N-methyl-N′-nitro-N-nitrosoguanidine upon early development in roach (Rutilis rutilus): 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 Km 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.

Delayed consequences of extremely low-frequency magnetic fields and the influence of adverse environmental conditions on roach Rutilus rutilus embryos

This study presents data collected over a 6 year period on the effects of extremely low-frequency magnetic fields (MFs) (1.4-1.6 µT, 500 Hz and 1.4-1.6 µT, 72.5 Hz) and MFs in combination with other environmental stressors (elevated temperature, 0.01 mg l(-1) trichlorfon, 0.01 mg l(-1) copper sulphate pentahydrate) on roach Rutilus rutilus embryos. Effects were studied during different stages of early development. Rutilus rutilus were raised in ponds for 4 months after exposure to MFs. The mass, standard length (LS ) and morphological characteristics of underyearlings which were exposed as embryos were recorded. An increase in embryo mortality and a decrease in LS and mass indices in underyearlings were noted after they had been exposed to a combination of MFs and different adverse environmental factors. In addition, exposure to MFs led to changes in the total number of vertebrae and the number of seismosensory system openings in the mandibular bones of underyearlings. MFs of different frequency caused both increases (500 Hz) and decreases (72.5 Hz) in morphological diversity. The stressors used in this study, however, did not increase the fluctuating asymmetry of bilateral morphological characteristics. The possible microevolutionary effects of exposure to MFs alone and in combination with other adverse environmental factors upon natural fish populations are discussed.

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.

Impact of simulated geomagnetic storm on activity of digestive glycosidases in roach Rutilus rutilus underyearlings

Long-term consequences of simulated geomagnetic storm action on early stages (0–24 h, 24–48 h, 48–72 h and 72–96 h post fertilization) of roach Rutilus rutilus embryogenesis were studied. The study revealed that fluctuations of magnetic field resulted in the decrease in the fish body length and weight, as well as in the differently directed changes in the activities of glycosidases (maltase, sucrase, and amylolytic activity) and kinetic characteristics of carbohydrates hydrolysis in the intestine of 4 month-old roach. The most pronounced changes in the fish body sizes were noted after exposure to magnetic field fluctuations within the time period of 48–72 h post fertilization. Relatively low values of Michaelis constant were revealed in the fish developed during embryonic stage either in the hypomagnetic conditions or under impact of simulated geomagnetic storm. This phenomenon may be considered as a response of fish digestive system to changes in the magnetic field during embryogenesis.

Anomalies in the backbone structure in roach (Rutilus rutilus) (Cyprinidae, Cypriniformes) underyearlings following toxic impacts during early developmental stages

The roach eggs were developed for 54 h postfertilization in solutions of chlorophos at low concentrations (10−6, 10−5, 10−4, 10−3, and 10−2 mg/l) and of N-methyl-M′-nitro-N-nitrozoguanidin (MNNG) (0.3 mg/l). The underyealings developed in these eggs differed from control ones by presence of higher number of backbone anomalies. The following axial skeleton anomalies were found in juvenile fish: fusions of vertebrae; underdevelopment of vertebrae; deformations of vertebrae; open-ended neural or hemal arcs; lack of vertebral arcs; nonunion of arc with body of vertebra; dislocation of branch base of the neural or hemal arcs to the neighboring vertebra; presence of extra branch of the arc. The positive correlation between number of anomalies in underyearlings and survival of experimental fish was revealed.

Some morphological features of roach Rutilus rutilus (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.

Patterns of development of the coldwater lacustrine-riverine form of the Drjagin charr (genus Salvelinus) from Lake Lama (the Taimyr Peninsula) during the larval period

Reproduction of the lacustrine-riverine form of the Drjagin charr (genus Salvelinus) from Lake Lama (the Noril’sk-Pyasina aquatic system on the Taimyr Peninsula) in a mountain tributary, the Bunisyak River, as well as the formation and development of skeletal elements in embryos and larvae reared under different experimental conditions are described. Patterns of the development and the heterochrony between the rates of somatic growth and osteogenesis are an adaptation to the extremely low water temperature and oligotrophic spawning habitat of the mountain stream. Still, the formation of vertebral centrae is retarded even at rather high rearing temperatures. As compared to larvae of the small normal (nondwarf) planktivorous lacustrine form of Arctic charr from Lake Davatchan (Transbaikalia) reared at 3°C, larvae of Drjagin charr from Lake Lama reared at 1°C are characterized by accelerated growth and heterochronies of osteogenesis. The divergence of the lacustrine-riverine form of Drjagin charr from the generalized form of Salvelinus alpinus in morphology begins during the larval period of the ontogeny.