Gonad development and reproduction in the monoecious species Chlorophthalmus agassizi (Actinopterygii: Aulopiformes: Chlorophthalmidae) from the Sardinian Waters (Central-Western Mediterranean)

Background. The shortnose greeneye, Chlorophthalmus agassizi Bonaparte, 1840, is a species with a circumglobal distribution and is among the most abundant commercial fishes in some Mediterranean areas. The knowledge of the biology and ecology of this species is poor and geographically limited, then the aim of this study is to provide a contribution to the knowledge on the reproductive biology of this monoecious deep-sea fish in Sardinian waters. Materials and Methods. In this paper the morphology and the development of the gonads, the mean size at maturity, the monthly evolution in the percent frequency of the maturity stages, and of the indices related to reproduction of the shortnose greeneye were examined. Individuals were caught by trawls, between 270 and 504 m of depth in the Sardinian seas. Results. The ovarian pattern is of an asynchronous type, characterized by releasing of eggs in successive batches. Seven stages of development for the ovary and four for the testis were identified on the basis of macroscopic and histological features. The female portion is the most evident component and shows a later maturation than the male portion. The spawning period is unique and takes place from May to September. Conclusion. The identification of spawning period and the adopted reproductive strategy is essential to obtain a better understanding of its biology and a good management of its fisheries

Genetic variability of the blue and red shrimp Aristeus antennatus in the Western Mediterranean Sea inferred by DNA microsatellite loci

Genetic variation at eight microsatellite loci was studied in nine populations of the blue and red shrimp Aristeus antennatus to investigate whether distinct stocks are present in the Western Mediterranean Sea. A high level of gene flow and no evidence of genetic partitioning were discovered. No significant variation was found (FST = 0.00673, P-value = 0.067) even when shrimps from exploited and those from deep-water unexploited grounds were compared. No evidence of reduction or expansion of population size in the recent past was found, as indicated by the bottleneck and interlocus g-tests. Our results are consistent with previous studies using mitochondrial gene methods and allozymes, indicating that, for this species, extensive pelagic larval dispersal and adult migration are probably responsible for the genetic homogeneity observed. In particular, due to a different bathymetric distribution of males and females, reported to be associated with different water masses and hence with possible differential dispersal capacity between sexes, the hypothesis of sex-biased dispersal was tested. Mean values of corrected assignment indices and mean relatedness values were higher for males, suggesting that females are the more widely dispersing sex. Molecular assessment of A. antennatus from the Western Mediterranean provides data of biological and evolutionary interest for the successful management of such a highly valuable fishery resource

Basin-scale occurrence and distribution of mesophotic and upper bathyal red coral forests along the Italian coasts

The analysis of 879 ROV dives carried out along the Italian coasts on hard substrata at mesophotic and upper bathyal depths (40-775 m) allowed us to evaluate the current basin-scale presence, relative abundance, bathymetric limits, and habitat preferences of one of the most charismatic Mediterranean habitat-former anthozoan species, Corallium rubrum (Linnaeus, 1758). The species is widespread, and its occurrence ranged from 13% of the explored sites in Ionian Calabria to a hotspot of approximately 80% in Sardinia. Population relative densities were generally low (< 10 colonies m-2), except along the Sardinian coasts and in some areas along the Apulian coast. Almost no red coral colonies were observed between 60 m and 590 m in the nine explored offshore seamounts in the Ligurian and Tyrrhenian Seas. A distinctive coastal distribution discontinuity was found in the Ionian Sea. The optimum bathymetric distribution was between 75 m and 125 m, and no colonies were found below 247 m. Red coral colonies showed a preference for biogenic habitats dominated by crustose coralline algae (CCA) and vertical substrata. The species was absent on iron wrecks. Corallium rubrum disappeared from 14% of the historical fishing banks, while it was confirmed in 86% of them, some of which have been deeply harvested in the past. In particular, the still flourishing Sardinian populations could be supported by the high reproductive potential and favourable hydrodynamic conditions in the area

Ethanol exposure and withdrawal differentially affect the GABA - A receptor plasticity and function in two different neuronal populations

Gamma-Aminobutyric acid type A (GABA-A) receptors have been implicated as major target sites for the acute and chronic ac- tions of ethanol (EtOH). Prolonged exposure to and withdrawal from EtOH are associated with alterations in GABA-A receptor subunit gene expression as well as in receptor function and phar- macological sensitivity in different in vivo and in vitro experi- mental models. Here, we focus on the effects of chronic EtOH ex- posure and withdrawal on the expression of the delta subunit of the GABA-A receptor in cultured rat hippocampal neurons (HP) and cerebellar granule (CG) neurons. GABA-A receptors contain- ing the delta subunit are preferentially extrasynaptic, are respon- sible for the tonic inhibition, and possess an enhanced sensitivity to the agonist THIP, to the neurosteroid allopregnanolone as well as to low concentrations of EtOH. Immunocytochemical and con- focal microscopy studies showed that delta subunit is preferen- tially expressed on the soma of CG cells, whereas it is mainly den- dritic in HP neurons. Long-term EtOH exposure increased delta subunit mRNA and peptide levels in HP neurons, while it did not significantly modify its expression in CG cells. EtOH withdrawal was associated to a rapid (6 h) marked reduction of delta subunit expression in CG cells, and to a persistent enhancement in HP neurons during the first 6h from withdrawal compared to un- treated control. Patch clamp recordings revealed that these EtOH induced changes in delta subunit expression are associated, in HP and CG cells, to an opposite effect, increase and decrease, respec- tively, of the efficacy of THIP and allopregnanolone to potentiate the chloride currents. Our data demonstrate that the changes in gene expression and function of GABA-A receptor containing the delta subunit induced by long-term EtOH exposure and with- drawal are opposite in HP and CG cells, suggesting a putative dif- ferent role of these extrasynaptic receptors in controlling tonic in- hibition in these two different cell types. The results indicate also a strict association existing between the GABA-A receptors sub- unit diversity and their differential sensitivity to drugs and en- dogenous modulators. This evidence together with the different cellular localization of GABA-A receptors may explain the differ- ent threshold of excitability of selective neuronal populations in specific brain areas. It is well established that ethanol increases plasma and brain levels of GABA-A receptor active neurosteroids by activating the HPA axis. We now show that, in isolated rat hip- pocampal slices, EtOH dose dependently increased the concentra- tion of allopregnanolone as well as the amplitude of GABA-A re- ceptor-mediated inhibitory postsynaptic currents recorded from CA1 pyramidal neurons. This latter effect appears biphasic, con- sisting of a rapid, direct modulatory effect, insensitive to the 5 alfa reductase blocker finasteride, and a delayed, allopregnanolone- mediated action reversed by finasteride. These observations sug- gest that EtOH may modulate GABA-A receptor function through an increase in de novo neurosteroid synthesis in brain that is in- dependent from the HPA axis. Given that neurosteroids play a major role in the physiological modulation of GABA-A receptor plasticity and function this novel mechanism may be important in mediating some effects of ethanol in physiological and pathologi- cal conditions (menstrual cycle, pregnancy, menopause, premen- strual symdrome) and a variety of psychiatric and neurological disorders in which the steroidogenesis undergoes dramatic func- tional changes

On the reproductive biology of the deep-sea lobster, Polycheles typhlops (Decapoda, Palinura, Polychelidae), from the central-western Mediterranean

Data are provided related to the reproductive biology of a deep-sea lobster, Polycheles typhlops, caught in Sardinian waters between 400 and 1400 m depth. Analyses were performed on 1180 females and 935 males. In both sexes, the carapace length decreased markedly and regularly with increasing depth; the females proved to be prevalent at greater bathymetric depths. The temporal evolution of the gonadosomatic index, and of the percentage distribution of the various stages of ovarian development, did not reveal any clear seasonality in reproduction for the species

Evoluzione dell’incremento ponderale alla muta di Palinurus elephas (Fabricius, 1787) in cattività

The mean of weight increment at moult for 11 females (41-71 mm CL) and 12 males (35-76 mm CL) of Palinurus elephas (Fabr., 1787) held in tanks was calculated by weekly weight data. The higher percentage of weight increment ( 82% and 73% respectively in females and males) occurs in a week before the exuviation when the spiny lobsters cease feeding (K fase). 7-10 days after exuviation they resume eating; their shells are completely hardened in one month (T fase). Then the weight remains constant during the following S fase until the next K fase

REGULATION OF alpha 4/delta GABA(A) RECEPTORS IN THE HIPPOCAMPUS OF SOCIALLY ISOLATED MICE EXPOSED TO VOLUNTARY ETHANOL CONSUMPTION

Social isolation in C57BL/6J mice was used as a model of prolonged mild stress to investigate the effects of ethanol (EtOH) in the free-choice drinking paradigm on gene expression and function of GABAA receptor (GABAAR) in the hippocampus. Socially isolated (SI) and group-housed (GH) mice were exposed for 6 weeks to the two-bottle choice (EtOH/H2O). Specific GABAAR subunit expression were measured by RNase protection assay and immunohistochemistry. GABAAR function was evaluated by conventional whole-cell patch clamp recording in brain slices. We found a significant increase in the abundance of both α4 and δ subunits of the GABAAR in the hippocampus of SI mice compared to GH animals. On the contrary the abundance of the α1 subunit mRNA was unchanged in SI mice as compared to GH mice. Voluntary EtOH drinking resulted in a marked increase in δ subunit mRNA levels in GH mice, whereas in SI animals, it completely abolished the increase in α4 subunit mRNA but did not alter that of the δ subunit with respect to the SI mice that consumed only water. Parallel changes in α4 and δ subunit peptides were observed by immunohistochemistry. Patch clamp recording in dentate gyrus granule cells obtained from SI mice revealed a greater enhancement of tonic currents induced by THIP compared to that in GH animals. Voluntary EtOH consumption reduced the increase in tonic current associated with social isolation. These results suggest that voluntary EtOH drinking in SI mice has a selective influence on α4 subunit since it blocks its enhanced expression but fails to alter the up-regulation of δ subunit. Sponsored by NIAAA INIA-Stress Grant #1 U01 AA016670

Impact of Phalacrocorax carbo sinensis (Aves, Phalacrocoracidae) on the fishery resources of a Sardinian lagoon

The negative impact of ichthyophagous birds on fish stocks are now matter of great concern. The aim of this study is to assess the wintering diet of the Great Cormorant (Phalacrocorax carbo sinensis) in the S. Antioco lagoon (south-western Sardinia). Through the morphological analysis of undigested hard body parts, such as otoliths, it was possible to trace to the preyed species, their size, biomass and, then, to the average daily consumption of cormorants