Experiments were carried out to investigate the effect of five extenders (sucrose, glucose, fructose, KCl and a saline carp sperm extender) and two cryoprotectants (dimethyl-sulfoxide (DMSO) and methanol) on the cryopreservation of common carp sperm. Freezing of sperm using glucose extender and methanol as cryoprotectant resulted in the highest post-thaw motility, fertilization as well as hatching rates (63 ± 9%, 74 ± 15% and 67 ± 17% vs. 87 ± 5%, 84 ± 14% and 69 ± 14% using fresh sperm, respectively). In general, sugar-based extenders combined with methanol as cryoprotectant yielded higher motility, fertilization and hatching rates than ionic extenders in combination with DMSO. The jelly-like agglutination observed after thawing in samples frozen with sugar-based extenders did not reduce fertilization and hatching rates. Frozen-thawed sperm samples were able to successfully fertilize 10 g (8000) eggs.
SummaryIn Central Europe, the challenge in soil tillage throughout the last century can be characterized as a fi ght against extreme climatic and economic situations. From 1800s till the 1970s, the main requirement of soil tillage was to provide suitable soil conditions for plant growth (moreover with fi ne structure). Both climatic and economic diffi culties were benefi cial in establishing new tillage trends, however overestimation of the crop demands have presumably been promoted by the deterioration in soil quality. From the end of the 1990s, new requirements have also been introduced because of the rise in energy prices and because of the need to cut production costs. Th e reduced tillage in Central European region showed some advantages, e.g. less soil disturbance and traffi c however, that resulted in new soil condition defects (e.g. top-and subsoil compaction, structure degradation). Th e ideas of sustainability off ered a better solution that is to conserve soil resources and to protect the environment. A new problem, the global climate change, and the importance of the adaptability fasten to the original sustainable goals. In this paper the features of soil quality deteriorating tillage (conventional, over-reduced) are summarised, the steps of improvement are demonstrated, and factors aff ecting sustainable soil tillage are formulated.
In this study we tried to develop a uniform method of sperm cryopreservation for four cyprinid fish species indigenous to Hungarian waters: the roach (Rutilus rutilus L.), the bream (Abramis brama L.), the silver bream (Blicca bjoerkna L.) and the barbel (Barbus barbus L.). The sperm was frozen in liquid nitrogen vapor in the presence of five extenders (350 mM M fructose, 30 mM M Tris, pH 8.0; 350 mM M glucose, 30 mM M Tris, pH 8.0; 300 mM M sucrose, 30 mM M Tris, pH 8.0; 200 mM M KCl, 30 mM M Tris, pH 8.0 and modified Kurokura's extender) andtwo cryoprotectants: 10% methanol (MeOH) and 10% dimethyl-sulfoxide. The highest post-thaw motility (roach: 77 ± 6%, bream: 77 ± 6%, silver bream: 67 ± 5%, barbel: 75 ± 6%), fertilization (roach: 84 ± 4%, bream: 83 ± 2%, silver bream: 63 ± 2%, barbel: 70 ± 4%) and hatching (roach: 74 ± 2%, bream: 67 ± 6%, silver bream: 54 ± 2%, barbel: 61 ± 4%) rates were found when either fructose or glucose extenders were used in combination with MeOH as cryoprotectant for all four investigated species. Strong correlations were found between post-thaw motility of the sperm and fertilization or hatching rates, which indicates that motility can be used to predict fertilization success in these species.
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