The effects of different preservation methods on ide (Leuciscus idus) sperm and the longevity of sperm movement.

The present study investigated the effects of chilled storage and cryopreservation on ide sperm motility and fertilizing capacity alongside the longevity of sperm movement. The parameters of motility (progressive motility-pMOT, curvilinear velocity-VCL and straightness-STR) have been recorded during 48 h of chilled storage (4 °C) at 24-h intervals. The longevity of sperm movement was measured following activation for up to 120 s (in a range at 10-120 s) in freshly stripped and thawed sperm. A formerly established cryopreservation method was tested on ide sperm where motility parameters, hatching rate and larval malformation (according to 7 category groups) were investigated. Significant decrement of pMOT has already been observed after 24 h (6 ±â€¯5%) compared to the freshly stripped sperm (49 ±â€¯22%). pMOT and STR showed no significant changes for up to 120 s following activation in fresh sperm, whereas VCL showed significant difference between 10 (51 ±â€¯11 µm/s), 90 (33 ±â€¯3 µm/s) and 120 (31 ±â€¯4 µm/s) seconds as well as between 20 (48 ±â€¯12 µm/s), and 120 s. No negative effect of cryopreservation was recorded on pMOT (fresh: 49 ±â€¯19%, cryopreserved: 22 ±â€¯22%), VCL (fresh: 45 ±â€¯9 µm/s and cryopreserved: 57 ±â€¯5 µm/s), STR (fresh: 81 ±â€¯3% and cryopreserved: 92 ±â€¯1%) hatching rate (fresh: 22 ±â€¯15%, cryopreserved: 33 ±â€¯18%) or larval malformation (fresh: 12 ±â€¯4%, cryopreserved: 12 ±â€¯4%). No significant correlation was found between the three motility parameters and hatching rate. Cryopreservation had no effect on hatching and the prevalence of larval deformity. Furthermore craniofacial and eye deformities were characteristic in the group originating from fertilization with cryopreserved sperm, while edemas (pericardial, yolk) occurred more frequently in the control. The formerly developed cryopreservation protocol (method for cyprinids) was applicable to ide sperm.

Impact of environmental and genetic factors on the scale shape of zebrafish, Danio rerio (Hamilton 1822): a geometric morphometric study.

Intraspecific morphological variability may reflect either genetic divergence among groups of individuals or response of individuals to environmental circumstances within the frame of phenotypic plasticity. Several studies were able to discriminate wild fish populations based on their scale shape. Here we examine whether the variations in the scale shape in fish populations could be related to genetic or environmental factors, or to both of them. In the first experiment, two inbred lines of zebrafish, Danio rerio (Hamilton 1822) reared under identical environmental conditions were compared. Secondly, to find out what effect environmental factors might have, offsprings were divided into two groups and reared on different diets for 12 weeks. Potential recovery of scales from an environmental effect was also assessed. Experimental groups could successfully be distinguished according to the shape of scales in both experiments, and the results showed that both genetic and environmental factors may notably influence scale shape. It was concluded that scale shape analysis might be used as an explanatory tool to detect potential variability of environmental influences impacting genetically homogeneous groups of fish. However, due to its sensitivity to environmental heterogeneity, the applicability of this technique in identifying intraspecific stock membership of fish could be limited.