Spectral sensitivity of cones in the goldfish, Carassius auratus

The spectral sensitivities of retinal cones isolated from goldfish (Carassius auratus) retinas were measured in the range 277-737 nm by recording membrane photocurrents with suction pipette electrodes (SPE). Cones were identified with lambda max (+/- S.D.) at 623 +/- 6.9 nm, 537 +/- 4.7 nm, 447 +/- 7.7 nm, and about 356 nm (three cells). Two cells (lambda max 572 and 576 nm) possibly represent genetic polymorphism. A single A2 template fits the alpha-band of P447(2), P537(2), and P623(2). HPLC analysis showed 4% retinal:96% 3-dehydroretinal. Sensitivity at 280 nm is nearly half that at the lambda max in the visible. The lambda max of the beta-band (in nm) is a linear function of the lambda max of the alpha-band and follows the same relation as found for A1-based cone pigments of a cyprinid fish.     

Resistance to extinction in the goldfish (Carassius auratus).

Examined resistance to extinction of 180 goldfish in a trials-equated alley situation. A reverse partial reinforcement effect (100% vs. 57% reinforcement) was found following brief acquisition training, while a conventional partial reinforcement effect was obtained after extended acquisition training. Extended acquisition training with a partial reinforcement sequence that had N lengths of 3 (an N length is the number of consecutive nonreinforcements before at least 1 reinforced trial) produced greater resistance to extinction than training with a sequence that had N lengths of 1. After brief acquisition training Ss with the shorter N length produced greater resistance to extinction. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dorsal specification in blastoderm at the blastula stage in the goldfish, Carassius auratus

Onchocerciasis is endemic on the island of Bioko, Equatorial Guinea, where it is transmitted by the 'Bioko form' of the Simulium damnosum complex, a cytospecies unique to the island. To determine the distribution of vector breeding, three dry season and two wet season expeditions were made in 1989, 1996 and 1997, and 226 of the island's 247 rivers (91.5%) were visited. Of these 226 rivers, 130 (58%) were flowing during the dry season, forty-five (20%) supported aquatic stages of Simuliidae of any species and twenty-five (11%) contained larvae or pupae of the S. damnosum complex. The twenty-one rivers not prospected were in the mountainous south of the island, where an additional seventeen rivers were reached but not satisfactorily prospected. Of these thirty-eight rivers, twenty-nine were considered highly likely to support vector breeding, bringing the total number of rivers which could harbour the vector during the dry season to fifty-four (21.9% of the island's total). Breeding was believed to be limited to river stretches below 1000 m altitude, and during the dry season the total length of those stretches which could support breeding on Bioko was estimated to be 1020 km. A combination of factors, including low river discharges during the dry season, the relatively low water temperature on Bioko, the suitability of limited stretches of most rivers as vector breeding sites and the close proximity of many rivers within a small geographical area, render the vector vulnerable to eradication by aerial treatment of rivers with insecticide. The isolation of the Bioko form of the S. damnosum complex suggests that reinvasion following treatment would be unlikely, and eradication of the vector might be achieved by a dry season larviciding programme in one or two years.     

Sensitivity of central units in the goldfish, Carassius auratus, to transient hydrodynamic stimuli

This study describes the discharges of central units in the medulla of the goldfish, Carassius auratus, to hydrodynamic stimuli received by the lateral line. We stimulated the animal with a small object moving in the water and recorded activity of 85 medullary lateral line units in response to different motion directions and to various object distances, velocities, accelerations and sizes. All but one unit increased discharge rate when the moving object passed the fish laterally. Five response types were distinguished based on temporal patterns of unit responses. Ten units were recorded which encoded motion direction by different temporal discharge patterns. In general, discharge rates decreased when object distance was increased and when object speed was decreased. When object size was decreased, discharge rates decreased systematically in one group of units, but they were comparable for all but the smallest object tested in a second group of units. Units responded about equally well whether an object was moved at a constant velocity or was accelerated when it passed the fish. The data indicate that medullary lateral line units in the goldfish can encode motion direction but are not tuned to other aspects of an object moving in the water. The functional properties of units in the medulla of goldfish are similar to those reported for medullary units in the catfish Ancistrus sp., suggesting that the central mechanisms for processing complex hydrodynamic stimuli may be quite similar in fish species that occupy habitats with different hydrodynamic conditions.     

Pavlovian analysis of avoidance conditioning in the goldfish (Carassius auratus).

Conducted 2 experiments in which 144 and 54 goldfish, respectively, were trained in a shuttlebox with light as CS and brief shock as UCS. Performance was measured in terms of "initial response" to the CS (at least 1 crossing of the hurdle on any trial) and-where the CS was not terminated by the initial response-in terms of "multiple response" to the CS (more than 1 crossing on any trial). The level of initial responding was as high in classically conditioned Ss (shocked on every trial) as in avoidance Ss, whether or not the CS was terminated by response, but lower in control Ss, yoked with the avoidance Ss, and lower also in punished Ss (shocked only if they responded). Multiple responding was negligible in avoidance Ss, but common in classically conditioned and in punished Ss. Results can be accounted for in purely Pavlovian terms, no reference to instrumental learning being required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Incorporation of bromodeoxyuridine in regenerating fin tissue of the goldfish Carassius auratus

We have investigated the pattern of incorporation of 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU) by proliferating cells during regeneration of the tail fin of Carassius auratus. Fifteen days after amputation, intraperitoneal injection of a single dose of 0.25 mg/g wet weight of BrdU and subsequent immunocytochemical detection on sections revealed groups of replicating cells in the blastema and epidermis at different proximodistal levels. Proliferating blastemal cells were confined to a crowded, compact distal area that lost its replicative capacity laterally, causing the differentiation of scleroblasts, which synthesize the lepidotrichia hemisegments. Proximally, but centrally located, the blastemal cells did not incorporate BrdU and they differentiated giving rise to the mature intraray connective tissue. An independent cell-proliferation process was noted in the epidermis. The distal cap did not proliferate; the lateral faces of the epidermis showed high rates of cell replication in the central layer at every level of the regenerate rays; quiescent cells remained in the superficial layers. The basal epidermal cells did not incorporate BrdU when actinotrichia were present. The possible role of basal epidermal cells in the synthesis of actinotrichia, the contribution of these collagen macrofibrils to the morphogenetic process, and the different pathways of cell differentiation during fin regeneration are discussed.     

Visual discrimination of orientation by the goldfish (Carassius auratus).

Trained 4 large goldfish to choose a vertically oriented grating when it appeared along with gratings of other orientations on a circular field. Ss produced psychometric functions of responses correct as a function of stimulus orientation. 2 psychophysical methods, constant stimuli and stimulus tracking, yielded similar orientation thresholds which ranged from about 14 to 30. of tilt for the 4 Ss. One of these Ss and 2 untrained Ss were subsequently trained to choose a grating tilted 45., and yielded similar thresholds, ranging from 15 to 28.. Results are discussed in relation to orientation detectors which have been investigated neurophysiologically in the visual systems of several species. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of two-tone complexes by the goldfish (Carassius auratus)

Smooth, highly spherical, crosslinked chitosan microspheres in the size range of 45-300 microns loaded with progesterone were prepared by glutaraldehyde crosslinking of an aqueous acetic acid dispersion of chitosan containing progesterone in a non-aqueous dispersion medium consisting of liquid paraffin and petroleum ether stabilized using sorbitan sesquioleate. In vitro release of the drug into phosphate buffer at 37 degrees C was determined as a function of crosslinking density of the microspheres and particle size. The extent of drug release had a remarkable dependence on the crosslinking density of the microspheres, the highly crosslinked spheres releasing only around 35% of the incorporated steroid in 40 days compared to 70% from spheres lightly crosslinked. Determination of the in vivo bioavailability of the steroid from microsphere formulation by intramuscular injection in rabbits showed that a plasma concentration of 1 to 2 ng/ml was maintained up to 5 months without a high 'burst effect'. Data obtained suggest that the crosslinked chitosan microspheres would be an interesting system for long term delivery of steroids.     

Reactions of the goldfish (Carassius auratus auratus L.) to quantified mechanical and thermal stimuli

Goldfish can differentiate between mechanical and thermal stimuli components in combined stimulations. Reactions to heated thermode (deltaT = + 3 degrees C) differ from those to isotherm thermode by up to 30%. Additional pretension (0.5 p) increases the reaction more than double; at simultaneously varied temperature (deltaT = + 3 degrees C and + 5 degrees C), there is a further increase in reaction of 25% and 35%. The significance for the organism of the two stimuli components is discussed.     

Effects of thyroxine administration on plasma thyroxine levels in the goldfish, Carassius auratus L

Melittin, a basic polypeptide from bee venom, inhibits basal and thyrotropin-stimulated adenylate cyclase of beef thyroid membranes with a Ki approximately 10 micron. Although this property resides in the basic C-terminal and not the N-terminal portion of the molecule, inhibition is due primarily to its detergent-like nature rather than charge effects. There is also a small enhancing effect of both basal and thyrotropin-stimulated adenylate cyclase of 0.3-3 micron melittin.     

Ascending spinal projections to the optic tectum, facial and vagal lobes in the goldfish, Carassius auratus

Using biotinylated dextran-amines as tracer, we observed prominent ascending spinal projections to three unreported areas in the gold fish brain viz. the optic tectum (OT), facial (FL) and vagal (VL) lobes. From the lateral spinal lemniscus (LSL), some fiber tracts separated off and extended mediodorsally, fanned out and innervated the FL. The VL was clearly laminated and showed three layers-the inner primary motor neuron and fiber layer (PMNF), outer secondary neuron layer (SN) and middle primary and secondary fiber layer (PSF). The PMNF received maximal innervation. Besides several fibers extending directly into the SN from the LSL, a few fibers extended dorsolaterally from the PMNF and innervated the SN. Several ascending fibers extended into the torus semicircularis, thalamic and pretectal areas and innervated the OT. The possible functional significance of the spinal innervation of these brain areas has been discussed.     

Masking of tones by noise for the goldfish (Carassius auratus).

Using a classical respiratory conditioning technique, tonal thresholds were measured for 4 goldfish at 5 frequency points between 100 and 1,200 Hz in quiet and under 3 levels of broadband noise. Masking was a linear function of noise level at all frequencies. Signal-to-noise ratios were lowest at 100 Hz (13 db) and increased linearly with log frequency at a rate of 3 db/octave. The values at frequencies above 200 Hz were about 2.5 db above those previously found for the cat and at 1,200 Hz were considerably below those for the rat. Below 200 Hz, however, the values fell below those reported for humans. This sensitivity of the fish in detecting signals in noise provides support for the notion that a mechanical frequency-to-place transformation at the periphery of an auditory system is not a necessary assumption in accounting for some aspects of frequency analysis. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethyl alcohol: Relationships to memory for aversive learning in goldfish (Carassius auratus).

Trained 96 goldfish in a shuttle-avoidance task under various ethanol dosages. Ss were tested for recall of the task under either changed or unchanged drug states. Alcohol increased shock-avoidance performance in a dose-related manner. Decrements in recall were also dose related with poorer recall associated with greater changes in drug state. Extended exposure to ethanol did not eliminate the decrements in recall. Alcohol also increased reactivity to and detectability of electric shock. Alcohol-induced changes in responsiveness to stimuli seemed responsible for increased avoidance learning. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Operant and Pavlovian control of a defensive shuttle response in goldfish (Carassius auratus).

Found that when a visual signal preceded electric shock, goldfish acquired shuttle responses both when a response avoided the shock (operant contingency) and when shock was not avoidable (Pavlovian contingency). Asymptotic levels of responding were significantly higher when shock could be avoided, but were still substantial when shock was not avoidable. Response termination of the signal had little effect on performance. A control experiment showed that responding resulted from the signal-shock contingency and not from nonassociative factors. A search within the Pavlovian contingency for an UCR similar in form to the CR was inconclusive. (PsycINFO Database Record (c) 2010 APA, all rights reserved)