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Oxygen uptake and carbon dioxide release by rainbow trout (Oncorhynchus mykiss Walb.) embryos exposed to constant magnetic fields of 5 and 10 mT (oxygen uptake and carbon dioxide release) and 50, 150, and 300 mT (oxygen uptake) were measured. The data were compared with those recorded in embryos developing under natural magnetic field (control). The magnetic fields tested were found to stimulate respiratory processes in the rainbow trout embryos as shown by a significantly increased oxygen consumption, particularly during periods of intensified morphogenesis. Exposure to 5 and 10 mT magnetic fields resulted in a slightly higher carbon dioxide release, the oxygen consumption being observed to increase as well. The respiratory quotient of the embryos exposed to magnetic fields was slightly higher than that in the control.
A device for transporting and storage of fish gametes, developing eggs, and newly hatched fry in a constant, adjustable (3-9 mT) magnetic field was constructed. The device has a relatively large, thermally insulated, biological material storage compartment, exposed to highly uniform (± 2.5%) magnetic field.
The number of activated spermatozoa of vendace (Coregonus albula L.) and their motility under natural conditions at the fishing ground were determined. The percentage of spermatozoa activated upon contact with water was found to be relatively high, and motility period (turbulent and smooth phase of progressive movement, and oscillatory movement) - fairy long, i.e. exceeding 2 min.
Trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walb.) embryos developing in eggs incubated in the geomagnetic field are oriented NW-SE. Artificial horizontal magnetic fields of 0.5 and 1.0 mT, i.e., higher than that of the natural one but of the same direction resulted in a changed alignment of the embryos examined. The embryos placed in those artificial fields were aligned N-S and NE-SW. A 90° clockwise rotation of the artificial horizontal magnetic field poles, relative to the geomagnetic one, resulted in embryos′ orientation being changed to N-S and NE-SW.
Background. Salmonid spermatozoa are characterised by a very short time of activity in the water, therefore sudden water pollution in the form of increased salinity on the spawning grounds may have a negative effect on the sperm motility parameters, thus affecting the subsequent egg fertilisation and, consequently, the number of hatched individuals of the species. The aim of this study was to determine the effect of water salinity on the motility parameters of spermatozoa of brook trout, Salvelinus fontinalis (Mitchill, 1814). Materials and Methods. Sperm motility was monitored with a camera (Basler A312fc) coupled with Nikon Eclipse 50i light microscope from the moment of their activation (contact with water) until the cessation of movement. The following water-salinity treatments were tested: 1.0‰, 3.0‰, 5.0‰, and 10.0‰. The motility parameters: VCL, VSL, VAP, ALH, BCF, LIN, STR, WOB, and MOT, were analysed with Computer Assisted Sperm Analysis (CASA). Results. The mean values of the studied motility parameters of the brook trout spermatozoa (obtained within 30 s), whose activation took place in the water of 0.35‰ salinity and in water of 1.0‰ and 3.0‰ salinity, did not differ significantly. The highest mean values of motility parameters were recorded for the water of 5.0‰ salinity. The 10.0‰ treatment caused a distinct decrease in the values of all the studied parameters. The percentage of MOT was the highest (37.5%) in the sample activated in the water used for fish rearing (0.35‰). In the remaining samples the MOT was lower, and in the water of 10.0‰ salinity it was only 9.1%. No spermatozoa movement of any kind was recorded in the 35th second of the experiment. Conclusion. The values of the motility parameters as well as the percentage of motile spermatozoa (MOT) in the semen decrease with increasing salinity of the water used for activation, and with increasing time of exposure.
Spermatozoa quality of two grayling (Thymallus thymallus L.) populations: free-living and bred in ponds, was compared. The percentage of spermatozoa activated upon contact with water, time of progressive movement (turbulent and smooth phase), time of oscillatory movement and the spermatocrit were determined. Males living in a river, as compared with those reared in a pond, displayed a significantly higher percentage of activated spermatozoa, whereas both populations did not significantly differ in spermatozoa motility and spermatocrit.
Background. After their deposition in water, eggs of perch form characteristic, long gelatinous ribbons (strands) floating within the water column. The ultrastructure of the external gelatinious egg envelope of members of the family Percidae was believed to be amorphous. The aim of the presently reported study was to describe the ultrastructure and function of the gelatinous egg envelope composing the perch egg ribbon. Materials and Methods. Fresh eggs of European perch, Perca fluviatilis L., were collected, in the form of egg ribbons, from females caught at the spawning grounds on the Odra River side canal Dziewoklicz, within the city limits of Szczecin, Poland. After fertilization eggs were fixed in 4%formaldehyde. In the laboratory, the commonly accepted techniques (dehydration, critical-point drying, sputter coating) were used to prepare samples for examination with a scanning electron microscope (SEM). The observations were photographically documented. Results. Closely below the surface of the gelatinous egg ribbon we observed a network of microtubules. These microtubules opened at the egg ribbon surface in the form of ring-like or nozzle-like pores. Conclusion. The gelatinous egg envelope of perch is a complex microtubular network that likely performs a skeletal role for the egg ribbon. Our results also suggest that the regular surface openings of the aforementioned network may play an attachment function (micro-suckers) reciprocally between eggs and between eggs and other objects, thereby facilitating the fastening the eggs to underwater vegetation.
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