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An MIDAS-400 Customised Data Acquisition System was deployed to obtain current velocity and suspended sediment concentration profiles over the intertidal flat at Wanggang, on the Jiangsu coast (China). At the same time, seawater temperature, conductivity and pressure were measured. Using a data sampling rate of 4 Hz, the high-frequency pressure signals in response to water surface fluctuations were recorded and subsequently transformed into wave parameters. The analytical results show that the apparent bed roughness length has a magnitude close to the height of sand ripples, which is much larger than the grain size diameter. The bottom shear stress associated with current-wave interaction is higher than the tidally-induced stress and intensified turbulent mixing and resuspension. Furthermore, several suspended sediment concentration peaks occurred during a tidal cycle, which can be related to strong turbulence near the bed caused by frontal tidal currents and the enhanced resuspension; advection and extreme weather conditions (e. g. storms and strong winds) also played an important role. Finally, large net suspended sediment fluxes were observed to present when the flood or ebb currents prolonged, i.e. the flow became quasi-unidirectional during a tidal cycle. In general, the MIDAS-400 is a suitable tool for high-resolution data collection for the situations of combined current-wave action over intertidal flats; the data obtained can be used to analyze the processes and mechanisms of material transport. [ABSTRACT FROM AUTHOR]

A MIDAS-400 customized data acquisition system has been used for the high-resolution sediment dynamic measurements over the Dafeng intertidal flats of northern Jiangsu during 6 tidal cycles from July 3 to July 10, 2003. The bed shear stress and bedload transport rates, in response to wave-current interactions, are calculated, which indicate that wind waves enhance the bottom shear stress and bedload transport rates. At the station for measurements, bedload transport was directed to seaward, with a sediment discharge of 30-150 kg·m-1 per tidal cycle. The surficial sediment samples were collected from a grid with 10 m spatial intervals over a rectangle 2 × 104 m² experimental area, near the MIDAS-400 during the spring tide of July 4, 2003, and the neap tide of July 9, 2003. In addition, leveling survey was undertaken to obtain the detailed topography of the sampling area. Grain-size trend analysis of the sediment samples shows that the bedload transport patterns are complex, mainly controlled by the hydrodynamics and local geomorphology (e.g. tidal creeks) over the intertidal flats. Furthermore, the grain-size trends pattern during the neap tide rather than during the spring tide is consistent with the calculated bedload transport, and the grain-size trend vectors for the spring tide are larger than those for [ABSTRACT FROM AUTHOR]

The gonad is an essential organ for generating sperm and ova in vertebrates. This review describes several pilot studies on gonad gene manipulation and development in fish. With antisense RNA techniques, we suppressed the gonad development, and thus the fertility, of an antisense gonadotropin-releasing hormone (sGnRH) transgenic common carp. Then, using a tissue-specific exogenous gene excision strategy with sexual compensation, we knocked out the gonad-specific transgene. Under the control of the rainbow trout protamine promoter, the transgenic fish expressed the reporter gene eGFP specifically in the spermary. These results indicate that the fish gonad is a new model organ that can improve contemporary biotechnology experiments. Herein we discuss the potential of fish gonad manipulation for resolving important biosafety problems regarding transgenic fish generation and producing the new transgenic animal bioreactor. [ABSTRACT FROM AUTHOR]

Reports that transgenes for growth hormone in common carp promotes thymus development. Observation of the thymus development between the transgenics and non-transgenic controls; Increase in both size and weight of the thymus in a one-year old transgenics; Confirmation that fish growth hormone promotes thymus development and thymocyte proliferation and retards thymus degeneration.

Presents a study of single later blastula nuclei from AB strain of zebrafish (Danio rerio) that were transplanted into enucleated unfertilized eggs of a Long fin strain. The number of reconstructed embryos that developed into fry from the cloning embryos; Similarity of the cloned fish's DNA fingerprinting systems with those of the nuclear donor fish and distinction from those of the nuclear recipient fish; Conclusion that the genetic material came from a nuclear donor cell other than the nuclear recipient egg; Suggestion of a breakthrough in the basic nuclear transplantation technique used with different strains of zebrafish; Implication for studies on gene function and animal development.

Presents a study which discussed the distinct biological effects for multisite-integrated transgenes and provides information on the breeding of fast-growing transgenic fish. Significance of studying transgenic fish; Brood amount of the transgenics and controls; Fertility rate and hatchability of transgenics and controls.

Triploid carp (100%) with 150 (3n=150) chromosomes were obtained by crossing the females of improved tetraploid hybrids (♀, 4n=200) of red crucian carp (♀)×common carp (♂) with the males of diploid yellow river carp (♂, 2n=100). The crosses yielded transgenic triploid carp (positive triploid fish, 44.2% of the progeny) and non-transgenic triploid carp (negative triploid fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish were not able to produce mature gametes during the breeding season. Morphologically, both the positive and negative triploid fish were similar. They had a spindle-shaped, laterally compressed, steel grey body with two pairs of barbells. Most of the quantifiable traits of the triploid carp were intermediate between those of the two parents. The positive and negative triploid fish were raised in the same pond for 2 years. The mean body weight of the positive triploid fish was 2.3 times higher than the negative triploid fish. The weight of the largest positive triploid fish was 2.91 times higher than that of the largest negative triploid fish. Thus, we produced fast-growing transgenic triploid carp that have a reduced ecological risk because of their inability to mate and produce progeny. [ABSTRACT FROM AUTHOR]

Ammonia is toxic to fish in natural and artificial waters. We evaluated the acute (96 h) and chronic (21 d) toxicity of un-ionized ammonia to GH transgenic common carp (Cyprinus carpio L.) and non-transgenic common carp using a static-renewal bioassay. The 24, 48, 72 and 96 h median lethal concentrations (LC50) of un-ionized ammonia were slightly lower in transgenic carp (2.64, 2.44, 2.28 and 2.16 mg N/L, respectively) than in non-transgenic carp (2.70, 2.64, 2.52 and 2.33 mg N/L, respectively). Similarly, the median lethal time (LT50) was significantly shorter for transgenic carp (1.41, 7.91 and 117.42 h) than for non-transgenic common carp (2.53, 14.06 and 150.44 h) following exposure to 3.86, 3.29, or 2.09 mg N/L, respectively. Moreover, the mortality of transgenic carp was significantly higher than that of non-transgenic carp at all un-ionized ammonia concentrations ((0.91 ± 0.12), (0.48 ± 0.06) and (0.12 ± 0.01) mg N/L) during the 21 d chronic toxicity test. Our results suggest that GH transgenic carp are less tolerant of un-ionized ammonia than non-transgenic carp. Our data are useful for evaluating potential environmental risk, optimizing stocking density in intensive aquaculture and establishing water quality criteria for ammonia in aquaculture. [ABSTRACT FROM AUTHOR]

Evidence has accumulated that there is a trade-off between benefits and costs associated with rapid growth. A trade-off between growth rates and critical swimming speed (Ucrit) had been also reported to be common in teleost fish. We hypothesize that growth acceleration in the F3 generation of "all-fish" growth hormone gene (GM) transgenic common carp (Cyprinus carpio L.) would reduce the swimming abilities. Growth and swimming performance between transgenic fish and non-transgenic controls were compared. The results showed that transgenic fish had a mean body weight 1.4-1.9-fold heavier, and a mean specific growth rate (SGR) value 6%-10% higher than the controls. Transgenic fish, however, had a mean absolute Ucrit (cm/s) value 22% or mean relative Ucrit (BL/s) value 24% lower than the controls. It suggested that fast-growing "all-fish" GH-transgenic carp were inferior swimmers. It is also supported that there was a trade-off between growth rates and swimming performance, i.e. faster-growing individuals had lower critical swimming speed. [ABSTRACT FROM AUTHOR]

Reports on the induction of dopaminergic differentiation of expanded rat mesencephalic neural stem cell. Progenitor of neural stem cell; Potentials to differentiate into all phenotypes in the central nervous system; Derivation of neural stem cell from rat mensencephalon; Demonstration that expanded neural stem cell can be induced to differentiate into dopamine neurons in vitro.