Diurnal rhythm in otolith formation in the goldfish, Carassius auratus

In the teleost fish otolith, the alternate deposition of CaCO 3 -rich and protein-rich layers results in the formation of daily increments. In order to clarify the mechanism of daily increment formation, a precise understanding of the relationship between ionic and organic controls of otolith growth is essential. In the present study, we studied diel variations in the aragonite saturation rate (S a ) of the endolymph and the mRNA expression of 2 major otolith matrix proteins, OMP-1 and otolin-1, in the saccular tissue. A new technique for simultaneously quantifying endolymph S a and mRNA expression in the saccular tissue from an individual rainbow trout was developed. Endolymph Ca 2+ levels, CO 2 partial pressure (P CO 2 ) and pH were simultaneously measured using an automatic pH/gas/electrolyte analyzer, and the S a was calculated. Total RNA was isolated from sacculi of individual fish after the endolymph was obtained. cDNAs were synthesized and used to quantify OMP-1 and otolin-1 mRNA expression levels by real-time PCR. Significant diel variations were observed in endolymph pH and P CO 2 levels in an antiphasic manner. Endolymph S a did not exhibit significant diel variations and was maintained at a value of more than 2.0, indicating that the endolymph was kept supersaturated with respect to aragonite during the day-night cycle. Expression of otolin-1 mRNA had apparent diel variations with high levels at night, whereas that of OMP-1 mRNA was almost constant. These data strongly suggest an organic control of daily increment formation in the otolith. The most probable candidate protein for daily increment formation is otolin-1.KEY WORDS: Calcification · mRNA expression · Endolymph · Daily increment · Aragonite · Otolith · Rainbow trout Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 294: [249][250][251][252][253][254][255][256] 2005 and the dark one is referred to as the D-zone (Kalish et al. 1995). Morphological examinations have revealed that the D-zones contain more organic matrices and less calcium carbonate relative to the L-zones (Mugiya & Muramatsu 1982, Watabe et al. 1982, Morales-Nin 1987; therefore, the alternate manner in which the deposition of mineral-rich and organic-matrix-rich layers occurs is manifested as daily increments. Indeed, Mugiya (1987) reported the discrete antiphasic diel cycles of 45 Ca and 3 H-glutamic-acid uptake into the otoliths in the rainbow trout in vitro and suggested that the daily increments of otoliths were formed by the antiphasic deposition of calcium and organic matrices. Daily variations in otolith calcification have also been demonstrated in the goldfish (Mugiya et al. 1981, Tohse & Mugiya 2002 and in the Atlantic salmon (Wright et al. 1992).The mechanism of these diel variations in otolith calcification and the deposition of the organic matrix is unknown. The otolith can be defined as acellular tissue that grows in an inner ear sacculus filled with endolymph. Consequently, endolymph must contain all the pr...

Section: Discussioncontrasting

confidence: 57%

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 88%

Diel changes in endolymph aragonite saturation rate and mRNA expression of otolith matrix proteins in the trout otolith organ

Takagi¹,

Tohse²,

Murayama³

et al. 2005

“…2). The initiation of the deposition of the discontinuous zone (terminology of Mugiya et al 1981) occurred around the onset of the dark period between 20:30 and 00:OO h (local time). The incremental zone was deposited during the rest of the 24 h period.…”

Section: Resultsmentioning

confidence: 99%

Growth of sprat Sprattus sprattus larvae in the German Bight (North Sea) as inferred by otolith microstructure

Ré¹,

Gonçalves²

1993

Growth of sprat larvae was studied in the German Blght of the North Sea and 2 different statlons (stratlfled and mixed water masses) were compared. Sprat larvae were aged using dally growth increments in sagittal otoliths. The daily nature of otolith growth increments was corroborated using the marginal increment technique. The data presented are consistent with the deposition of one complete increment per 24 h period, indicating that at least larvae with lengths greater than 11.0 mm form daily growth increments in their otoliths. There was some evidence that daily growth increments are deposited on the otoliths of sprat larvae only after the onset of exogenous feeding. Integrated somatic growth rate was 0.406 mm d-'. This value is comparable to others obtained for similar pelaglc clupeoid species. There were no significant differences between growth rates at the 2 stations.

“…In particular, mean aquarium water temperature (20.5OC) during laboratory growth was slightly colder than the minimum water temperature encountered in the wild (seasonal range of daily SST, 22 to 27"C, K. somatic growth rates in B. coalitus (Shafer 1998) Residuals of In (Age) on In (TL) and in other species (Mosegaard et al 1988, width and optical contrast of daily increments between wild and laboratory growth intervals illustrate the capability of B. coalitus otoliths to record significant shifts in environmental and metabolic conditions on a daily basis. Formation of daily increments in fish otoliths is likely an obligatory result of circadian-driven physiological control of plasma calcium levels and calcium uptake rates by otoliths (e.g., Mugiya et al 1981, Mugiya 1987. Otoliths from fish as large as 70 mm TL (-307 d old, Shafer 1998) featured increments comparable in optical properties and widths to increments shown to be daily in experimental fish.…”

Section: Settlement Markmentioning

confidence: 99%

“…Changes in growth, physiology, metabolism, and environment during metamorphosis and settlement all likely contribute to changes in regular otolith accretion (Mugiya et al 1981, Gauldie et al 1995, resultmg in the formation of a settlement mark (e.g., Gauldie 1988). At the end of larval life, transparent/silver Bathygobius spp.…”

Section: Settlement Markmentioning

confidence: 99%

Evaluation of periodic and aperiodic otolith structure and somatic-otolith scaling for use in retrospective life history analysis of a tropical marine goby, Bathygobius coalitus

Shafer¹

2000

Daily increment formation in sagittal otoliths, scaling between otolith and somatlc growth. and the temporal link between settlement and formation of a settlement mark in otolith structure were evaluated for their use in reconstructing aspects of the early Me history of the basalt goby Bathygobius coalitus. Formation of daily increments was validated in sagittae of fish ranging In Life history stage from new recruits to sexually differentiated males and females. Total length (TL) was proportional to other measures of body length, width, and depth, and linearly proportionaI to sagitta radius for fish between 8 and 40 mm TL. Somatic-otolith scaling became more curvilinear in larger fish due to declining growth rate of otoliths relative to TL, especially in fish collected during warmer sea surface temperatures. For fish 8 to 40 mm TL, somatic-otolith scaling was not affected by differential somatic growth rates nor by seasonal water temperature. A settlement mark, clearly identifiable as a distinct and abrupt shift in optical focal plane, contrast, and width of daily increments, was venfied to coincide with settlement. Wider post-settlement increments abruptly followed narrower pre-settlement increments across the settlement mark. These results support the use of daily increments, somatic-otolith scaling, and a settlement mark for reconstruction of hatch and settlement dates, mean daily pre-and post-settlement growth rates, size and age at settlement, and post-settlement size-at-age histories for the basalt goby.