Three goldfish were trained to search for food buried 20 cm from a perspex tower. In the absence of food, all fish still searched in the correct location, revealing that fish can use a landmark to locate food. Halving either the width or height of the landmark resulted in searches significantly closer to the tower, suggesting that fish determined their position relative to the landmark using its horizontal and vertical visual angles. 相似文献
This study was conducted to evaluate the ability of a PVA-gel beads filtration (PVA) system using photosynthetic bacteria
to purify water. To accomplish this, duplicate long-term goldfish rearing experiments were conducted using four different
types of aquarium systems (COF, PSB, EMC, and PVA). The results revealed that the concentrations of NH4+-N on the day of a goldfish’s death were significantly higher than the concentrations on other days for all the aquarium systems.
In addition, the mean concentration of NH4+-N during goldfish rearing occurred in the following order: COF system > EMC system > PSB system > PVA system. Furthermore,
the mean values of all other ion concentrations (NO3−-N, NO2−-N, and PO42−-P) were found to be lowest in the PVA system. As a result, there was more prominent decomposition of organic matter in the
aquarium tank containing the PVA system, as well as less turbid aquarium water and more active goldfish. Additionally, the
PVA-gel beads resulted in almost complete denitrification, even after six-months of goldfish rearing. To our knowledge, this
is the first study to report that PVA gel-immobilized photosynthetic bacteria have the ability to purify water. Overall, the
results of this study indicate that this immobilized photosynthetic bacteria system has the potential for use as a component
in circulating filtration systems. 相似文献
Among six species of juvenile fishes (<6 months old), stenohaline species (channel catfish Ictalurus punctatus and goldfish Carassius auratus ) had their highest specific growth rate ( G ) and most efficient food conversion ratio ( E C) and energy absorption efficiency ( I E) in fresh water. Three of the euryhaline species (rainbow trout Oncorhynchus mykiss , striped bass Morone saxatilis and Gulf sturgeon Acipenser oxyrinchus desotoi ) had higher G and had more efficient E C and I E in 3 and 9‰ salinities than in lower salinities (fresh water and 1‰). For brown trout Salmo trutta (age 3–4 months), 9‰ was above the optimum level for G and E C. However, I E for brown trout was not significantly different at 3 and 9‰ salinities. Over the salinity range tested, channel catfish had the largest change in G , E C and I E, while changes for euryhaline species were relatively small. Although all species tested survived and grew in all treatments, salinities as low as 1‰ adversely affected the stenohaline species, and 9‰ adversely affected brown trout. 相似文献
The goldfish (Carassius auratus) Tgf2 transposon is a vertebrate DNA transposon that belongs to the hAT transposon family. In this study, we constructed plasmids containing either the full-length Tgf2 transposon (pTgf2 plasmid) or a partially-deleted Tgf2 transposon (ΔpTgf2 plasmid), and microinjected these plasmids into fertilized zebrafish (Danio rerio) eggs at the one- to two-cell stage. DNA extracted from the embryos was analyzed by PCR to assess transient excision, if any, of the exogenous plasmid and to verify whether Tgf2 is an autonomous transposon. The results showed that excision-specific bands were not detected in embryos injected with the ΔpTgf2 plasmid, while bands of 300–500 bp were detected in embryos injected with pTgf2, which indicated that the full-length Tgf2-containing plasmid could undergo autonomous excision in zebrafish embryos. DNA cloned from 24 embryos injected with pTgf2 was sequenced, and the results suggested that Tgf2 underwent self-excision in zebrafish embryos. Cloning and PCR analysis of DNA extracted from embryos co-injected with ΔpTgf2 and in vitro-transcribed transposase mRNA indicated that partially-deleted-Tgf2-containing ΔpTgf2 plasmid also underwent excision, in the presence of functional transposase mRNA. DNA cloned from 25 embryos co-injected with ΔpTgf2 and transposase mRNA was sequenced, and the results suggested that partially-deleted Tgf2 transposons plasmids were excised. These results demonstrated that excisions of Tgf2 transposons were mediated by the Tgf2 transposase, which in turn confirmed that Tgf2 is an autonomous transposon. 相似文献
To examine the effect of novelty in food selection by fishes, goldfish were trained by feeding them on red or green food pellets. Individual fish and fish in shoals of two, three, and five were then given a choice between equal numbers of familiar pellets and novel (yellow) pellets. In experimental groups, the yellow pellets were soaked in 15% quinine hydrochloride to make them unpalatable. Fish were next presented with equal numbers of familiar and a second novel pellet. It was expected that fish would generalize from their experience with the unpalatable pellets and demonstrate avoidance to sampling a second novel food item. However, as groups, neither controls nor experimentals were reluctant to sample the second novel pellets. Also, fish did not eat significantly more familiar than novel pellets when both were palatable. A third set of experiments examined food preference transitivity in which each pellet type was presented alone and in three pair-wise combinations to individual fish. Although red and yellow pellets were preferred over green, they were preferred equally, indicating an absence of transitivity in pellet choice and, perhaps, a “preference” for a mixture of red and yellow pellets. 相似文献
A cyp19a gene that contains nine exons and eight introns was identified from Carassius auratus and was mainly expressed in the ovary. The cyp19a mRNA level after hatching was initially low, but began to increase from 25 days after hatching. A number of cis‐acting elements, such as the oestrogen receptor, steroidogenic factor 1 and SOX‐5 recognition sites, were found in the promoter of the cyp19 gene, which possesses a promoter function confirmed by a recombination green fluorescent protein checking system in vitro. 相似文献
Many androgenetic fish hybrids are nonviable due to the disturbed interaction between the foreign nucleus and the cytoplasm. It has been proposed that this incompatibility can be overcome if eggs from interspecific hybrids and sperm from one of the parental species are used for diploid androgenesis. Indeed, the androgenetic progeny obtained as a result of the insemination of the enucleated eggs of goldfish and carp hybrids by the carp spermatozoa proved to be viable and fertile. This approach may be used for reconstitution of the genotypes of rare or disappearing fish species with the help of induced androgenesis, if their native or cryoconserved sperm is available. 相似文献
1. 1.|The mitochondrial population in hypothalamic and hypophysial brain tissue from warm (30°C) and cold (5°C) acclimated goldfish (Carassius auralus L.) was analyzed using sterological techniques.
2. 2.|It was revealed that there is a significantly larger volume density (Vv) in the cold acclimated tissue, with no significant difference in either of the surface densities (Svext and Svint) from either of the brain areas.
3. 3.|The hypothalamic brain tissue has a significantly lower specific surface (S/V) in the cold acclimated tissue but there is not a significant difference in this parameter for the hypophysial brain tissue.
4. 4.|The values for these three parameters (Vv, Svext and SVint, and S/V) indicate that mitochondria from acclimated brain tissue undergo shape changes in response to thermal stress.
5. 5.|We suggest that the shape changes may be related to the change in the phospholipid composition of the inner mitochondrial membrane with acclimation temperature.