The atypical presence of the paternal mitochondrial DNA in somatic tissues of male and female individuals of the blue mussel species Mytilus galloprovincialis

<p>Abstract</p> <p>Background</p> <p>In animals mtDNA inheritance is maternal except in certain molluscan bivalve species which have a paternally inherited mitochondrial genome (genome M) along with the standard maternal one (genome F). Normally, the paternal genome occurs in the male gonad, but it can be often found, as a minority, in somatic tissues of males and females. This may happen in two ways. One is through "sperm mtDNA leakage" into somatic tissues, a deviation from the normal situation in which the sperm mtDNA vanishes in females or ends up exclusively in the germ line of males. The other is through "egg heteroplasmy", when the egg contains, in small quantities, the paternal genome in addition to maternal genome.</p> <p>Findings</p> <p>To test the two hypotheses, we compared the sequences of one of the most variable domains of the M molecule in a somatic tissue (foot) and in the sperm of ten male and in the foot of ten female individuals of <it>M. galloprovincialis</it>. Presence of the M genome was rarer in the foot of females than males. The M genome in the sperm and in the foot of males was identical.</p> <p>Conclusions</p> <p>Given that the surveyed region differs from individual to individual, the identity of the M genome in the foot and the sperm of males supports strongly the hypothesis that, at least for the tissue examined, the presence of the M genome is due to sperm mtDNA leakage.</p

Herd behavior in the drybulk market: An empirical analysis of the decision to invest in new and retire existing fleet capacity

We examine whether investors herd in their decision to order or scrap vessels in the drybulk market. We decompose herding into unintentional and intentional, and test for herd behavior under asymmetric effects with respect to freight market states, cycle phases, risk-return and valuation profiles, and ownership of the vessel. We detect unintentional herd behavior during down freight markets and contractions. Furthermore, we find evidence of spill-over unintentional herding effects from the newbuilding to the scrap market. Finally, asymmetric herd effects are evident between traditional and liberal philosophy towards the ownership of the vessel, and during extreme risk-return and valuation periods

First report of Vibrio anguillarum isolation from diseased big scale sand smelt, Atherina boyeri Risso 1810, in Limnos, Greece

Vibriosis is an important disease of farmed and wild fish, caused by species of the genus Vibrio. During December 2000, high mortalities were observed in a wild population of big scale sand smelt Atherina boyeri in Limnos, Greece. The microbiological analysis of the moribund fish resulted in the isolation of a pure culture of Vibrio anguillarum. The bacterium was identified by bacteriological procedures and slide agglutination reaction. Focal or more extensive necrosis was found in almost all organs, in all fish examined and the retina of the eyes appeared corrugated. The pathogenicity of the strain for sea bass was confirmed by bath challenge causing mortalities up to 97%. Factors contributing to the outbreak of the disease were considered to be the presence of parasites (Platyhelminthes) in the intestinal tract. No simultaneous infection at a fish farm in the vicinity had been reported. However, since there are disease interactions between wild and cultured fish, infected wild fish, can act as a reservoir of the pathogen

Freight Derivatives Pricing for Decoupled Mean-Reverting Diffusion and Jumps

We develop an accurate valuation setup for freight options, featuring an exponential meanreverting model for the freight rate with distinct reversion scales for its jump and diffusion components. We calibrate to Baltic option prices and analyze the freight rate dynamics. More specifically, we observe that jumps dissipate faster than the diffusive deviations about the equilibrium level. We benchmark against practitioners’ model of choice, i.e., the lognormal model and variants, and find that our approach reduces the pricing error while preserving analytical tractability and computational competence. We also find that neglecting fast mean-reverting jumps leads to nontrivial option mispricings

Shipping equity risk behavior and portfolio management

This paper investigates the dynamics of stock price volatility for different vessel-type segments of the U. S, water transportation industry . We measure market exposure by a portfolio of tanker, dry bulk, container, and gas stocks to examine tail behavior and tail risk dependence. The role of mixture distributions in predicting future volatility is studied from both statistical and economic perspectives. We further test for predictability in co-movements in the tails of sectors returns . Findings indicate that large losses are strongly correlated, supporting asymmetric transmission processes for financial contagion. Finally, using a non-parametric approach, we extend the model to the multivariate case and assess the value of volatility and correlation timing in optimal portfolio selection. The results can help to improve the understanding of time-varying volatility, correlation and tail systemic risk of shipping stock markets, and consequently, have implications for risk management and asset allocation practices, as well as regulatory policies

Freight options: Price modelling and empirical analysis

This paper discusses an extension of the traditional lognormal representation for the risk neutral spot freight rate dynamics to a diffusion model overlaid with jumps of random magnitude and arrival. Then, we develop a valuation framework for options on the average spot freight rate, which are commonly traded in the freight derivatives market. By exploiting the computational efficiency of the proposed pricing scheme, we calibrate the jump diffusion model using market quotes of options on the trip-charter route average Baltic Capesize, Panamax and Supramax Indices. We show that the jump-extended setting yields important model improvements over the basic lognormal setting

Affine-Structure Models and the Pricing of Energy Commodity Derivatives

We consider a seasonal mean-reverting model for energy commodity prices with jumps and Heston-type stochastic volatility, and three nested models for comparison. By exploiting the affine form of the log-spot models, we develop a general valuation framework for futures and discrete arithmetic Asian options. We investigate five major petroleum commodities from Europe (Brent crude oil, gasoil) and US (light sweet crude oil, gasoline, heating oil) and analyse the effects of the competing fitted spot models in futures pricing, Asian options pricing and hedging. We find evidence that price jumps and stochastic volatility are important features of the petroleum price dynamics

Shipping Investor Sentiment and International Stock Return Predictability

Stock return predictability by investor sentiment has been subject to constant updating, but reaching a decisive conclusion seems rather challenging as academic research relies heavily on US data. We provide fresh evidence on stock return predictability in an international setting and show that shipping investor sentiment is a common leading indicator for financial markets. We establish out-of-sample predictability and demonstrate that investor sentiment is also economically significant in providing utility gains to a mean-variance investor. Finally, we find evidence that the predictive power of sentiment works best when negative forecasts are also taken into account

Reproductive Biology Of The Shi Drum (Umbrina Cirrosa) In Captivity And Induction Of Spawning Using Gnrha

The reproductive biology of the shi drum (Umbrina cirrosa) in culture was histologically exam- ined and sperm quality was monitored during an entire reproductive period. Already in April, the ovary contained oocytes in all stages of maturation, from primary oocytes to full vitellogenesis, as expected from a group-synchronous multiple-batch spawning fish. Vitellogenesis of the first batch of oocytes occurred very rapidly and their mean diameter (500 μm) did not increase sig- nificantly (p>0.05) as the reproductive period proceeded. The spermiation index peaked in May- June, but fish never produced copious amounts of milt upon abdominal pressure. The sperma- tozoa motility percentage remained unchanged throughout the spawning season (80%) and a significant percentage (40%) maintained viability after overnight storage at 4°C. Sperm density and motility duration increased during the reproductive period and varied 13-26 x109 spermato- zoa/ml and 26-40 s, respectively. Spontaneous spawning was not observed during the two-year study. Injection of post-vitellogenic females with an agonist of gonadotropin-releasing hormone (GnRHa) was successful in inducing a single spawning after two days, with fertilization, hatch- ing and 4-day larval survival rates of 65%, 42-76% and 46-80%, respectively. The results under- line the failure of female shi drum in culture to undergo final oocyte maturation and, although GnRHa injection was effective in inducing spawning of viable eggs, multiple treatments did not induce multiple spawns, as was expected from fish with multiple-batch group-synchronous ovar- ian biology