Tilapia Mariae Research Articles

Hunting behavior of Florida largemouth bass, Micropterus salmoides floridanus, in a channelized river

The distribution and behavior of Florida largemouth bass, Micropterus salmoides floridanus, and their main prey (sunfish, genus Lepomis, and the cichlid Tilapia mariae) were studied in southern Florida to determine how fish behave in the simplified habitats found in channelized rivers. Time budgets were constructed from focal animal observations on 69 bass. Patterns of behavior associated with hunting were performed during a significantly higher proportion of the time when bass were in vegetated habitats. Scan samples of the behavior of 236 observed bass revealed that hunting was more common in areas of high structural complexity. Only 38% of observed bass were solitary, with the majority occurring in groups with either conspecifics or in mixed-species groups with similar sized bluegill sunfish, Lepomis macrochirus. Largemouth bass (n=1014) and sunfish (n=1372) were significantly more abundant in areas with vegetation and were almost entirely absent from the water column in the center of the canal. All species of fish avoided the water column, where currents were swift and no cover was available. The structure of the habitat appears to be important in the way largemouth bass organize their activity patterns. This suggests that habitat availability in channelized rivers significantly influences important behaviors such as hunting, thus potentially altering energy budgets and population dynamics of both predator and prey.

Combined retrograde tracing and immunohistochemistry of trigeminal ganglion neurons projecting to gingiva or tooth pulps in the lower jaw of the cichlid Tilapia mariae.

Rat trigeminal ganglion neurons projecting to the oral mucosa or to tooth pulps have different cell diameters and contain different chemical markers. In the present paper we examine whether trigeminal ganglion neurons sending axons to gingiva or tooth pulps in the lower jaw of the cichlid Tilapia mariae differ in a similar way. Retrograde tracing with fluorescent latex microspheres revealed labelled gingival and pulpal neurons in the caudal part of the trigeminal ganglion. The gingival neurons had a unimodal size distribution (peak 11 microns; range 8-14 microns) and the pulpal neurons exhibited a bimodal size distribution (peaks 12 and 25 microns; range 10-40 microns). Immunohistochemistry revealed a calcitonin gene-related peptide-like immunoreactivity in some 40% of the gingival neurons and a substance P-like immunoreactivity in 30%. Of the small pulpal neurons about 60% exhibited a calcitonin gene-related peptide-like immunoreactivity and 15% showed a substance P-like immunoreactivity. Of the large pulpal neurons some 70% exhibited a calcitonin gene-related peptide-like immunoreactivity. These neurons did not show a substance P-like immunoreactivity. In some animals a few trigeminal ganglion neurons showed a neuropeptide Y- or a vasoactive intestinal polypeptide-like immunoreactivity. Perikarya with a tyrosine hydroxylase- or a choline acetyl transferase-like immunoreactivity were not observed. We conclude that gingiva and tooth pulps in the lower jaw of T. mariae are innervated by trigeminal ganglion neurons, the cell diameters and neuropeptide contents of which differ in a pattern similar to that in the rat. Hence, this seems to represent a conserved evolutionary pattern.

Occurrence of axons with certain immunohistochemical markers in teleost gingiva and teeth

The occurrence of axons with certain neurochemical markers in gingiva and teeth in the lower jaw of the cichlid Tilapia mariae was examined by immunohistochemistry. It was found that gingival and pulpal axons can be labelled with antibodies against calcitonin gene-related peptide, substance P, tyrosine hydoxylase, neuropeptide Y, choline acetyl transferase and vasoactive intestinal polypeptide. It is concluded that both gingival and dental domains in T. mariae contain axons with sensory and autonomic chemical phenotypes, the occurrence and distribution of which are generally similar to the mammalian counterpart.

Immunohistochemical and electron microscopic demonstration of nerve fibres in relation to gingiva, tooth germs and functional teeth in the lower jaw of the cichlid Tilapia mariae

Immunohistochemistry revealed the presence of numerous neurofilament (NF)-like immunoreactive axons in relation to gingiva and dental follicles surrounding mineralizing tooth germs. The gingival nerve fibres frequently approached the prospective papilla of early tooth primordia. Electron microscopic (EM) analysis revealed the presence of bundles of unmyelinated axons immediately below the epithelial-proprial junction of the gingiva. Bundles of nerve fibres were also present in the border zone between the prospective papilla of bud-stage tooth germs and surrounding mesenchyme and in close proximity to blood vessels of the follicles surrounding older tooth germs, but no axons were observed within the emerging dental papilla. In the individual functional tooth, a bundle of NF-like immunoreactive nerve fibres entered the apical part of the pulp forming a subodontoblastic plexus at mid-pulpal levels. EM analysis showed that the apical bundle consisted of many unmyelinated and a few myelinated axons invested by Schwann cell processes. The subodontoblastic plexus contained unmyelinated axons only. Thin, axon-like profiles were also seen in predentinal tubules. Nerve fibres were not observed at pulpal horn levels and in the ligamentous attachment. It is concluded that both immature and mature parts of the lower-jaw dentition of the cichlid T. mariae are innervated and that the microscopic anatomy of this innervation is partly similar to the pattern seen in developing and adult mammals.

Evidence for a Neural Influence on Tooth Germ Generation in a Polyphyodont Species

It has been suggested that nerve endings emanating from the dental nerve plexus of the jaw might be involved in the formation of tooth germs. In the present study we examine the effect of unilateral denervation on the formation of tooth germs in the lower jaw of a polyphyodont teleost—the cichlid Tilapia mariae . Repeated inspection of the lower jaw dentition in normal animals over a period of about 300 days showed that the functional time of an average individual tooth is 101 days. In operated animals, the functional time was normal on the unoperated side, but on the denervated side tooth turnover ceased about 100 days after surgery. Radiographic plates from lower jaw specimens revealed that mineralized replacement teeth were present on the unoperated side, but not on the denervated side, 300 days after denervation. Light microscopic examination of semi-thin transverse sections from decalcified plastic-embedded lower jaws showed that soft-tissue tooth primordia and nerves were lacking on the denervated side, while present within the undisturbed half-jaw. It is concluded that the local presence of mandibular nerve branches is necessary for the formation of tooth germs in the lower jaw of the cichlid T. mariae.

Nodes of Ranvier and myelin sheath dimensions along exceptionally thin myelinated vertebrate PNS axons.

The trigeminal alveolar branch in the lower jaw of the cichlid Tilapia mariae was examined by light and electron microscopy on single and serial sections, and by light microscopy on teased fibre preparations. The principal purpose was to find out if the exceptionally thin myelinated axons (d < 1 micron) present in this nerve possess true nodes of Ranvier, and to determine the dimensions of their myelin sheaths. This necessitated analysis of the whole size range of myelinated fibres, with respect to nodal and internodal morphology. The results show that the exceptionally thin myelinated fibres exhibit primitive nodal regions, with patches of axolemmal undercoating, and few Schwann cell processes in the node gap. This contrasts with the more complex nodal organization seen in larger trigeminal alveolar branch fibres. For the whole population of myelinated fibres the number of myelin lamellae increases rectilinearly with axon diameter, and sheath length increases with fibre diameter according to a logarithmic expression. The myelin sheaths of the exceptionally thin trigeminal alveolar branch fibres are composed of 10-20 lamellae, and extend 35-50 microns along the axon. These results show that the structural complexity of nodal regions in the trigeminal alveolar branch decreases with decreasing fibre size, that the exceptionally thin myelinated trigeminal alveolar branch fibres possess primitive nodes and that they have very short myelin sheaths. Our crude theoretical calculations suggest that these fibres might be capable of saltatory conduction.

An assessment of genetic differentiation among feral Australian tilapia populations

Feral populations in Australia of the introduced cichlid, tilapia, were compared by using cellulose- acetate electrophoresis to examine degrees of genetic differentiation among the disjunctive populations. Evidence was obtained to support the recognition of three morphs: two 'good' species (Oreochromis mossambicus and Tilapia mariae) and a third morph that is a potential interspecies hybrid between O. mossambicus and one or more of the related Oreochromis species O. honorum, O. niloticus and O. aureus. Distributions of the three morphs are described, and their likely origins and potential impacts on native fauna are discussed.

Partner Attack Inhibition in the Sexually Monomorphic Biparental Cichlid Tilapia Mariae

Abstract Courtship behaviour was investigated in the sexually monochromatic biparental cichlid, Tilapia mariae, with particular emphasis on the role of submissive behaviour in the process of pair formation. Pair formation successfully occurred when the female had prior residence in the tank, and could occur within a few minutes. Dominant females generally had priority of access to males. In the experiment where pairing occurred, dominant females and males showed practically no overt aggression towards each other. In the confines of a small tank, with no other subordinate conspecifics present, male and female T. mariae did show aggression to one another, but in this case courtship behaviour was entirely absent. Closed-fin postures were employed by both sexes of Tilapia mariae in the early stages of courtship: it is suggested that these served as 'Partner Attack Inhibition' displays. Submissive displays of the kind employed in agonistic encounters are not used in courtship.

Trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae: evidence for continual axon generation and presence of exceptionally small myelinated axons.

Cross sections from the trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae were examined by electron microscopy. The nerve fibers are arranged in groups with a core of unmyelinated and small myelinated axons, surrounded by myelinated axons of varying sizes. The core contains large bundles of unmyelinated axons collectively ensheathed by circumferentially located Schwann cells, as well as smaller bundles of unmyelinated axons partly separated from each other by Schwann cell processes. Among the unmyelinated axons, occasional scattered profiles resembling growth cones are seen. The total number of axons in this tooth-related nerve increases from approximately 1,500 to 5,000, as the animals grow in length from 4.5 to 21.5 cm. Some 24-49% of the axons are unmyelinated. The myelinated axons have maximum diameters of 1.0-3.0 micron, depending on body size. Most myelinated axons have diameters less than 1.0 micron and the smallest ones reach down to 0.3 micron. These results show that there is a continual addition of axons to the alveolar nerve of the lower jaw in Tilapia mariae and that the critical diameter for myelination in this peripheral nerve is similar to that typically found in the mammalian CNS.

On nerves and teeth in the lower jaw of the cichlid Tilapia mariae.

The anatomy of the teeth and tooth-related nerves in the lower jaw was examined in the cichlid Tilapia mariae. This was done in order to establish a basis for studies on dental neuroplasticity in a polyphyodont vertebrate. The region of interest was explored in specimens fixed by glutaraldehyde perfusion, and by using X-ray photography, maceration, scanning electron microscopy, gross dissection, and light microscopic examination of serial sections. The results show that the lower jaw carries some 60-65 functional teeth. In addition, numerous replacement teeth and tooth germs in various stages of development are located in a cavity in the dentary bone. Numerous nerve bundles are present in immediate relation to the dental follicles of tooth germs. Unerupted teeth do not contain light-microscopically discernible pulpal axons, but the pulps of functional teeth contain myelinated axons. Both perifollicular and pulpal nerve bundles derive from a nerve plexus, which is formed by branches from r. mandibularis trigemini. This nerve is easily accessible to experimental manipulation, where it courses through the adductor mandibulae muscular complex. Thus, the lower jaw of T. mariae seems to represent a suitable system for the study of tooth-nerve interactions in a polyphyodont species.

Occurence of exotic tropical fish in the cooling pondage of a power station in temperate south-eastren Australia

Three species of exotic tropical fish, the black mangrove or Niger cichlid, Tilapia mariae Boulenger, of West Africa; the convict cichlid, Cichlasoma nigrofasciatum (Gunther), of Central America; and the Jack Dempsey cichlid, Cichlasoma octofasciatum (Regan), of Central and South America, have been recorded from the cooling pondage of a power station in temperate south-eastern Australia. All three species are readily available in the local aquarium fish trade. Black mangrove cichlids and convict cichlids appear to have established self-maintaining populations in the pondage. and also occur in a creek below the pondage.

Range Expansion in Southern Florida of the Introduced Spotted Tilapia, with Comments on its Environmental Impress

The Spotted Tilapia, Tilapia mariae, apparently introduced to Dade County, Florida, between 1972 and 1974, has expanded its range dramatically. This exotic fish is now established in three counties (Broward, Collier, and Dade) in canals and lakes in an area encompassing approximately 2,000 km2.

Immunological determination of injected mammalian prolactin in cichlid fishes

In the present paper an attempt is made to determine, by quantitative radial immunodiffusion, the level of intramuscularly-injected mammalian prolactin (LtH) in serum and organs of two species of cichlid fishes ( Aequidens pulcher and Tilapia mariae) at different times after application. With injections of 0.05 or 0.02 mg/gm bodyweight, the maximum LtH concentration in serum is reached after 1–3 hours. Within 3–25 hours prolactin rapidly disappears, and 28–30 hours after application, it is eliminated totally from circulation. In the kidney the maximum level appears at 2–7 hours after injection, but in this organ LtH concentration decreases somewhat slower than in serum, so that total elimination occurs 7–10 hours later. The hormone could not be identified on other organs (skin, musculature, thyroid-containing tissue, brain, and intestine), except in the liver and spleen of Aequidens, in which minute amounts of prolactin were detectable. There is discussed the correlation of these findings with the control mechanism of some behavioral and histotropic effects which are inducible by mammalian prolactin in cichlid fishes.

IMMUNOLOGISCHE UNTERSUCHUNGEN AN HYPOPHYSENVORDERLAPPENHORMONEN MIT ANTIKÖRPERN VON SÄUGETIEREN UND FISCHEN

ABSTRACT Tropical Cichlid fishes (Tilapia mariae) and guinea pigs are able to produce antibodies to ovine anterior pituitary hormones. The immune response in fish is weaker than in mammals. Antisera of both animal groups are suitable specific ones but the fish immune system does not react very sensitively to small contaminations of the antigens. Electrophoretical examinations of anterior pituitary hormones (LTH, STH, FSH, LH and TSH) on gelatinized cellulose acetate strips show that except STH all the other hormones consist of several components. This is confirmed by immunological methods. There is some evidence that LH occurs in several molecular forms or components. Cross reactions and immunoelectrophoreses show a distinct separation of the immunological properties of the protein LTH and its antibody resp. and the glycoproteids FSH, LH, TSH and their antibodies. The protein STH and its homologous antibody, however, precipitate with all other hormones and their antibodies tested, except TSH. This possibly depends on the contamination of these hormones one with another.