Thicklip Grey Mullet Chelon Labrosus Research Articles

Cloning and expression pattern of peroxisome proliferator-activated receptors, estrogen receptor α and retinoid X receptor α in the thicklip grey mullet Chelon labrosus

Aquatic organisms are exposed to diverse xenobiotics that cause peroxisome proliferation and/or endocrine disruption, both modulated in vertebrates by transcription factors of the nuclear receptor (NR) superfamily. Peroxisome proliferators are agonists of peroxisome proliferator-activated receptors (PPARs) that heterodimerize with the retinoid X receptor (RXR). Many xenoestrogens activate the estrogen receptor (ER). Here, 1090 bp of PPARα, 1255 bp of PPARγ, 278 bp of RXRα, and 578 bp of ERα of thicklip grey mullet Chelon labrosus were cloned. Sequences were highly conserved, although relevant changes with respect to mammalian homologs were identified in PPARγ and ERα. Semi-quantitative RT-PCR was used to determine if these NRs were expressed in different tissues of male, female and undifferentiated mullets captured in January and June. Expression of PPARs was highest in liver and lowest in muscle. RXRα expression was homogeneous excepting a low expression in male and female gill in January and brain and heart of undifferentiated fish in January and June. ERα expression predominated in liver and female gonad in June. The expression level of PPARs and ERα was significantly higher in liver in January than in gills in January or June. The present results show tissue-dependent modulation of expression of NRs in mullets.

Cloning and expression pattern of peroxisomal enzymes in the mussel Mytilus galloprovincialis and in the thicklip grey mullet Chelon labrosus: Generation of new tools to study peroxisome proliferation

Aquatic organisms living in coastal/estuarine areas show peroxisome proliferation after exposure to different environmentally relevant pollutants. In order to generate new tools to assess peroxisome proliferation in aquatic animals, peroxisomal enzymes were cloned using degenerate primers in the mussel Mytilus galloprovincialis and in the thicklip grey mullet Chelon labrosus. Fragments of catalase (CAT), thiolase (THIO), polyamine oxidase (POX) and xanthine oxidoreductase (XOR) were cloned and their expression pattern studied in different tissues by semi-quantitative RT-PCR. In mussels, CAT, THIO, POX and XOR were expressed in digestive gland, mantle and gills while in mullets CAT, THIO and POX were expressed in liver, spleen, brain, heart, muscle and gills. XOR was mainly expressed in liver and heart. Mature mullets showed the highest expression of peroxisomal enzymes in liver, spleen and brain, while in juveniles expression was mainly found in muscle tissues, liver and gills. Laboratory experiments of exposure to organic pollutants are being performed to study the usefulness of these tools to study peroxisome proliferation in pollution biomonitoring programmes.

The functional morphology of the copulatory apparatus of Ergenstrema labrosi and Ligophorus angustus, monogenean gill parasites of Chelon Labrosus

SUMMARYThe male intromittent apparatus of Ergenstrema labrosi and Ligophorus angustus, monogenean parasites of the thick-lipped grey mullet Chelon labrosus, consists of a slender flexible penis tube with an expanded proximal region and whose distal end passes freely through a canal in an accessory sclerite; the tube is surrounded by a sleeve of longitudinal muscle and the apparatus works in a manner generally similar to an engineer's Bowden cable. There is a substantial difference in the form of the accessory sclerite in the two species. In both parasites there is a slender sclerotized vagina which, in L. angustus, is short and straight or curved but in E. labrosi is about 7 times longer and forms a spiral. The special role of the sclerotization of the distal part of the vagina may be to resist perforation of the wall by the exceedingly fine penis tube and the consequent discharge of sperms into the parenchyma.

Ergenstrema Labrosi sp.nov. (Monogenea) on The Gills of The Thick-Lipped Grey Mullet Chelon Labrosus at Plymouth

Ergenstrema mugilis Paperna, 1964, the only member of the genus, has been collected in the Mediterranean from the gill rakers of the thin-lipped grey mullet Liza ramada (Risso, 1810) by Paperna (1964) and Lambert & Sanfilippo (1977); this parasite, under the name of ‘Dactylogyridea sp.’, was collected also from the same microhabitat of the same host from the coast of Albania by Ergens (1960). At Plymouth, parasites clearly belonging to the genus Ergenstrema have been collected from both the gill rakers and lamellae of a different host, the thick-lipped grey mullet Chelon labrosus (Risso, 1826).

Adaptability of Chelon labrosus (Risso) and Liza saliens (Risso) (Pisces, Mugilidae) to fresh water

Experiments were conducted to determine the adaptability of young thick-lip grey mullet Chelon labrosus (Risso) and leaping grey mullet Liza saliens (Risso) to various salt concentrations. Young thick-lip grey mullet (total length 18–32 mm) were subjected to abrupt changes from saltwater to freshwater media. No mortality occurred with salinity decrease, even with an abrupt change from 100% sea water ( S = 39‰) to fresh water ( S = 0.4‰). Young leaping grey mullet (total length 25–43 mm) were subjected to abrupt changes from saltwater to freshwater media. No mortality occurred with salinity decrease, even with an abrupt change from 100% sea water ( S = 39‰) to 5% sea water ( S = 1.95‰). Sixty five percent of the fish died with abrupt salinity change from 100% sea water to 0% sea water ( S = 0.4‰). With a gradual decrease from 5% sea water to fresh water ( S = 0.4‰) all fish survived.