Biomedical subjects

A Lombarte

Publications and source records attributed to A Lombarte.

4 recordsLinked to original sources

PubMed2006

Fish otolith asymmetry: morphometry and modeling.

Mathematical modeling suggests that relatively large values of otolith mass asymmetry in fishes can alter acoustic functionality and may be responsible for abnormal fish behavior when subjected to weightlessness during parabolic or space flight [D.V. Lychakov, Y.T. Rebane, Otolith mass asymmetry in 18 species of fish and pigeon, J. Grav. Physiol. 11 (3) (2004) 17-34; D.V. Lychakov, Y.T. Rebane, Fish otolith mass asymmetry: morphometry and influence on acoustic functionality, Hear. Res. 201 (2005) 55-69]. The results of morphometric studies of otolith mass asymmetry suppose that the absolute value and the sign of the otolith mass asymmetry can change many times during the growth of individual fish within the range +/-20% [D.V. Lychakov, Y.T. Rebane, Otolith mass asymmetry in 18 species of fish and pigeon, J. Grav. Physiol. 11 (3) (2004) 17-34; D.V. Lychakov, Y.T. Rebane, Fish otolith mass asymmetry: morphometry and influence on acoustic functionality, Hear. Res. 201 (2005) 55-69]. This implies that the adverse effects of otolith asymmetry on acoustic and vestibular functionality could change during the lifetime of an individual fish. The aims of the present article were to examine the nature of otolith mass asymmetry fluctuation and to quantify otolith mass asymmetry in a large number of teleost fishes to verify our previous measurements. A dimensionless measure of otolith mass asymmetry, chi, was calculated as the difference between the masses of the right and left paired otoliths divided by average otolith mass. Saccular otolith mass asymmetry was studied in 59 Mediterranean teleost species (395 otolith pairs), 14 Black Sea teleost species (42 otolith pairs), red drum (196 otolith pairs) and guppy (30 otolith pairs). Utricular otolith mass asymmetry was studied in carp (103 otolith pairs) and goldfish (45 otolith pairs). In accordance with our previous results the value of chi did not depend on fish size (length or mass), systematic or ecological position of the fish, or otolith growth rate. In the great majority of the fishes studied, the saccular otolith chi was small /chi/ <0.05 (or <5%). Mathematical modeling indicates that values of chi vary among individual fish, but that the value is probably stable during a fish's lifetime.

Animals↗

PubMed2000

Distribution pattern of taste buds along hyoidal barbels of Mullus barbatus and M. surmuletus.

The external taste buds of bony fishes are differentiated and grouped throughout the body epithelium, concentrating in the buccopharyngeal cavity or in certain external organs such as the lips, barbels or fins. The family Mullidae (goatfishes) is characterized by having barbels covered with taste buds (TBs). However, It is not known how the TBs are distributed and how their characteristics vary along the barbels. To obtain answers to these questions, the morphological variability in taste bud density (deltaTB), pore area (A(P)) and taste bud area (A(TB)) was studied in Mullus barbatus (L., 1758) (red mullet) and M. surmuletus (L., 1758) (striped red mullet), for fish ranging in size from 58 to 227 and from 56 to 287 mm in total length (L(T)), respectively. Assuming that larger fish are older, in both species the pore area (A(P)) and taste bud area (A(TB)) increased with ontogenic development. Also, in both species clear differences were observed along the barbel. The delta(TB) increased from the basal area to the apical area, whereas both the A(P) and A(TB) had an inverse pattern.

Animals↗

PubMed1994

Quantitative analyses of postembryonic hair cell addition in the otolithic endorgans of the inner ear of the European hake, Merluccius merluccius (Gadiformes, Teleostei).

Bony fishes add sensory hair cells to the saccule and lagena of the ear for at least several years after hatching. However, it is not known whether hair cell proliferation occurs for the whole lifetime of an animal, whether proliferation occurs in all endorgans of the ear, or whether the rate of proliferation is the same in all of the endorgans. To obtain answers to these questions, the extent of postembryonic hair-cell proliferation was determined in the saccule, lagena, and utricle of the ear in the European hake, Merluccius merluccius, for fish ranging from 7 to 75 cm in total length (6 months to 9 years of age). Results demonstrated that hair-cell addition continued throughout this period in all three otic endorgans, although endorgan size was proportionally greatest in smaller animals. Of the three endorgans, cell addition was greatest in the saccule. Moreover, far more cells were added to the caudal end of the saccule than to the rostral end. Each saccule of the largest hake had over 900,000 hair cells. It is estimated that each saccule adds approximately 110,000 new hair cells each year (or 302 cells/day) over the life span of the fish studied. A significant number of small ciliary bundles, thought to represent newly proliferated hair cells, was found throughout each endorgan, and the number of such bundles declined as the rate of hair cell proliferation decreased. The results demonstrate that extensive proliferation occurs in all three otolithic endorgans of the ears in a fish and that such proliferation continues for virtually the whole life of the animal. The functional significance of this addition is not known.

Animals↗

PubMed1993

Damage and regeneration of hair cell ciliary bundles in a fish ear following treatment with gentamicin.

Sensory hair cells in the striolar regions of the utricle and lagena of a teleost fish, the oscar (Astronotus ocellatus), were damaged following intramuscular injections of gentamicin sulfate. In order to determine whether fish can regenerate hair cells, the time course of damage and recovery was followed over a period of four weeks by scanning electron microscopy. Maximum loss of ciliary bundles occurred at about day 10 after the first of four daily injections of gentamicin (20 mg/kg) in 4-6 cm long fish. The striolar regions were almost totally denuded of ciliary bundles, and there was evidence of considerable hair cell loss. The time course for damage was longer in larger fish, but the recovery of the ciliary bundles appeared to be complete about 10 days after maximal damage was seen in both the smaller and larger fish. These data indicate that Astronotus is able to repair damage to hair cells for an extended period of time post-embryonically.

Analysis of Variance↗