Colonization patterns of the date mussel Lithophaga lithophaga (L., 1758) on limestone breakwater boulders of a marina

Background and Purpose: The European date mussel (Lithophaga lithophaga) is widespread along the whole Mediterranean rocky coastline where it is frequently but illegally harvested. It is well known that the growth of the date mussel is very slow; however, patterns of recolonization of exploited surfaces have been scarcely investigated. The objective of this study is to assess colonization patterns of the date mussel on limestone boulders which have been in the sea for 19 years. These results could be useful in predicting the reconstitution of natural populations of the date mussel after harvesting. Materials and Methods: Limestone breakwater boulders were placed along the dike of the Marina of Rovinj (northern Adriatic, Istrian peninsula, Croatia) in 1984. Sampling was carried out in summer 2003 by SCUBA diving from six habitats of different inclination and topography: horizontal, inclined, vertical, sheltered, vaults, and whole stones. The abundance and biomass of L. lithophaga at the Marina were compared with those in natural control locations. Results: At the Marina, no date mussels were found on the horizontal and inclined sides of the boulders, and very few date mussels were found on the vertical side. On the contrary, sheltered and vault sides of boulders and whole stones were intensively colonized by L. lithophaga. In vaults, the abundance was similar to that in nature. In these habitats, L. lithophaga biomasswas generally lower than in nature. However, large date mussels, of lengths from 50 to 70 mm, were already present on boulders of theMarina. They amounted to 35% in the sheltered habitat, 24% in vaults, and 3% of the total number in whole stones. Conclusions: An unexpected high colonization rate and growth of date mussels was detected in certain unexposed rocky habitats at the boulders of the Marina. However, on the natural rocky Istrian coast, the date mussel was mostly collected on exposed inclined and vertical rocky surfaces where repopulation after harvesting may require very long periods

Biometrijske razlike između prstaca Lithophaga lithophaga koji koloniziraju umjetne i prirodne strukture

Shell width and body live weight related to shell length of the endolithic bivalve Lithophaga lithophaga (date mussel) colonizing a specific habitat (vaults under boulders) formed by artificial and natural structures were examined. Artificial structures consisted of limestone boulders of a breakwater (Marina Rovinj, northern Adriatic Sea, Croatia) constructed 19 years before sampling of the date mussel. Date mussels’ density (around 80 individuals per 0.1 m2) did not differ between the two types of structure. However, the length frequency distribution in artificial structures (25th percentile = 3.20, median = 4.30 and 75th percentile = 5.10 cm) differed from that in natural structures (25th percentile = 3.66, median = 5.15 and 75th percentile = 6.20 cm) leading to a substantial difference in total biomass (0.3 and 0.8 kg per 0.1 m2 for artificial and natural structures, respectively). Parameter estimates of regression functions for width against length (linear function) and for live weight against length (allometric function) also significantly differed, indicating variations in date mussels’ morphometry between the two types of structure. Analyses of variance did not detect differences in width or weight for date mussels in the length range from 3 to 3.5 cm. However, width (average ± s.d., n = 18) of individuals in the range from 5.5 to 6 cm was significantly lower in artificial structures (1.46 ± 0.13 cm) than in natural structures (1.66 ± 0.10 cm). Consistent with this, live weight in artificial structures (8.36 ± 1.17 g) was significantly lower than that in natural structures (12.33 ± 1.48 g). It is suggested that these patterns reflect a growth rate of the date mussel that is higher in artificial than in natural structures. Information about date mussels’ biometric patterns in different habitats is important in planning studies assessing the resilience capability of natural populations after illegal destructive harvesting, particularly as,such studies are lacking.Istražene su širina ljušture i težina živog organizma u odnosu na dužinu ljušture endolitskogškoljkaša Lithophaga lithophaga (prstac) u specifičnom staništu (svodovi ispod blokova) sastavljenomod umjetnih i prirodnih struktura. Umjetne strukture su bile vapnenački blokovi lukobrana(Marina Rovinj, sjeverni Jadran, Hrvatska), izgrađenog 19 godina prije uzorkovanja prstaca.Brojnost prstaca (oko 80 jedinki po 0.1 m2) nije se razlikovala između tipova struktura. Međutim,raspodjela frekvencije dužina u umjetnim strukturama (25. percentil = 3,20, medijan = 4,30 i 75.percentil = 5,10 cm) razlikovala se od one u prirodnim strukturama (25. percentil = 3,66, medijan =5,15 i 75. percentil = 6,20 cm) što je dovelo do značajne razlike u ukupnoj biomasi (0,3 kg po 0.1m2 za umjetne i 0,8 kg po 0.1 m2 za prirodne strukture). Nadalje, procijenjeni parametri regresijskihfunkcija širine u odnosu na dužinu (linearna funkcija) i težine u odnosu na dužinu (alometrijskafunkcija) značajno su se razlikovali, što upućuje na morfometrijske razlike prstaca između tipovastruktura. Analizom varijance nije ustanovljena razlika u širini ili težini prstaca u rasponu dužineod 3 do 3,5 cm. Međutim, širina (aritmetička sredina ± s.d., n = 18) jedinki u rasponu od 5,5 do 6cm bila je značajno manja u umjetnim (1,46 ± 0,13 cm) nego u prirodnim strukturama (1,66 ± 0,10cm). U skladu s time, i težina jedinki u umjetnim strukturama (8,36 ± 1,17 g) je bila manja nego uprirodnim strukturama (12,33 ± 1,48 g). Pretpostavlja se da su navedene razlike bile posljedica većebrzine rasta prstaca u umjetnim nego u prirodnim strukturama. Informacije o biometrijskim karakteristikamaprstaca u različitim staništima su važne za planiranje studija o obnovi prirodne populacijenakon nezakonitog destruktivnog sakupljanja, te takve studije zasada nedostaju

Dodatne informacije o plavom trkaču, Caranx crysos (Mitchill, 1815), u sjevernom Jadranu: meristička i molekularna karakterizacija

In October 2014, a blue runner (Caranx crysos) was caught by a professional fisherman in waters off St. Eufemija Point (west Istrian Coast, northern Adriatic Sea, Croatia). This is the second recorded blue runner in the northern Adriatic Sea, which represents the northernmost biogeographic sector of the Mediterranean Sea. Recently, blue runners were recorded in the southern and central Adriatic Sea, suggesting that the central Mediterranean C. crysos is expanding its area of distribution throughout the Adriatic Sea. As a point of interest, this most recent specimen presented an unusual meristic feature: the number of spines of its first dorsal fin was VI, whereas it is generally recognised that the number of such spines characteristic for this species is VIII. Species identity of the specimen was confirmed by DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene. In addition, we provided the first report of C. crysos mitochondrial 16S ribosomal RNA (16S rRNA) partial sequence.U listopadu 2014. godine, ribu plavi trkač (Caranx crysos) je ulovio profesionalni ribar nekoliko stotina metara van rta Sv. Eufemija (zapadna obala Istre, sjeverni Jadran, Hrvatska). Ovo je drugi po redu nalaz ribe plavi trkač koja je ulovljena u sjevernom Jadranu, što predstavlja najsjevernije biogeografsko područje sredozemnog mora. Nedavno ova vrsta je zabilježena u južnom i srednjem Jadranu što ukazuje da se populacija C. crysos iz središnjeg Sredozemnog mora proširuje u Jadranskom moru. Razmatrani primjerak je pokazao neobičnu merističku značajku: broj bodlji u prvoj leđnoj peraji je VI, dok je općenito za ovu vrstu prihvaćeno (priznato) VIII bodlji. Identitet vrste potvrđen je analizom mitohondrijske DNA sekvence za pod-jedinicu I gena citokrom c oksidaze (COI). U ovom radu također je po prvi put analiziran dio mitohondrijske DNA sekvence odgovorne za kodiranje 16S ribosomske RNA (16S rDNA) kod vrste C. crysos

Expression of high- and low-affinity epidermal growth factor receptors in human hepatoma cell lines

AbstractData are presented from a comparative research on expression of epidermal growth factor (EGF) receptors and response to EGF of six independently established cell lines derived from human hepatoma. These lines differ in terms of the degree of differentiation, presence of hepatitis B virus (HBV) DNA copies in integrated form and expression of HBV genes. Our results indicate differential expression of membrane EGF receptors and differential response to EGF under serum- and hormone-free culture conditions. Furthermore, a significant difference in affinity could be detected between EGF receptors of the two highly dedifferentiated cell lines (HA22T/VGH and Li7A) whose replication is inhibited by EGF concentrations capable of stimulating more differentiated phenotypes

A baseline study of the metallothioneins content in digestive gland of the Norway lobster Nephrops norvegicus from Northern Adriatic Sea: Body size, season, gender and metal specific variability

Metallothioneins content was investigated in digestive gland of two wild-caught Norway lobster Nephrops norvegicus populations from the Northern Adriatic Sea, in relation to body size, season and gender. Concomitant accumulation of cadmium, mercury, arsenic, lead, chromium and manganese, reactive oxygen species concentration and energy reserves in digestive gland were also assessed. While differences between genders were not recorded, metallothioneins content seasonal trends were affected by body size. Most of parameters displayed inconsistent trends across sampling sites. Significant correlation between metallothioneins content and cadmium, arsenic and mercury concentrations was recorded only for larger lobsters. A negative correlation of reactive oxygen species concentration and metallothioneins content was observed for small, but not large lobsters. Energy reserves, in particular lipids, could considerably influence biochemical and chemical parameters variations. The present results constitute the essential baseline for future studies aimed at evaluating the N. norvegicus health in relation to metal contamination of coastal sediments