Molecular effects of a variable environment on Sydney rock oysters, Saccostrea glomerata: Thermal and low salinity stress, and their synergistic effect.

Bivalves are frequently exposed to salinity and temperature fluctuations in the estuary. This study explored the molecular effect of these fluctuations by exposing Sydney rock oysters, (Saccostrea glomerata), native to Australia, to either low salinity, elevated temperature or a combined salinity and temperature stress. Following the exposures, RNA-Seq was carried out on the collected oyster tissues.

Estrogen therapy offsets thermal impairment of vitellogenesis, but not zonagenesis, in maiden spawning female Atlantic salmon ().

In female Atlantic salmon (), exposure to warm summer temperatures causes a reduction in plasma 17β-estradiol (E2), which impairs downstream vitellogenesis and zonagenesis, and reduces egg fertility and embryo survival. The aim of the present study was to determine whether E2-treatment could offset thermal impairment of endocrine function and maintain egg quality in maiden (first-time-spawning) reared at 22 °C. Treatment with E2 at 22 °C stimulated vitellogenin () gene expression and subsequent protein synthesis which promoted oocyte growth and increased egg size relative to untreated fish at 14 and 22 °C.

Effects of GnRHa treatment during vitellogenesis on the reproductive physiology of thermally challenged female Atlantic salmon ().

Tasmanian Atlantic salmon () broodstock can experience temperatures above 20 °C, which impairs reproductive development and inhibits ovulation. The present study investigated the prolonged use of gonadotropin releasing hormone analogue (GnRHa) during vitellogenesis as a means of maintaining endocrine function and promoting egg quality at elevated temperature in maiden and repeat spawning . GnRHa-treatment during vitellogenesis did not compensate for the negative effects of thermal challenge on the timing of ovulation, egg size, egg fertility or embryo survival in any fish maintained at 22 °C relative to 14 °C.

Combined exposure to pyrene and fluoranthene and their molecular effects on the Sydney rock oyster, Saccostrea glomerata.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitously detected in the water column, associated with particulate matter or in the tissue of marine organisms such as molluscs. PAH exposure and their resultant bioaccumulation in molluscs can cause a range of serious physiological effects in the affected animals. To examine the molecular response of these xenobiotics in bivalves, Sydney rock oysters (Saccostrea glomerata) were exposed to pyrene and fluoranthene for seven days.

Identification of differentially expressed reproductive and metabolic proteins in the female abalone (Haliotis laevigata) gonad following artificial induction of spawning.

Inefficient control of temperate abalone spawning prevents pair-wise breeding and production of abalone with highly marketable traits. Traditionally, abalone farmers have used a combination of UV irradiation and application of temperature gradients to the tank water to artificially induce spawning. Proteins are known to regulate crucial processes such as respiration, muscle contraction, feeding, growth and reproduction.

Transcriptome Analysis of the Sydney Rock Oyster, Saccostrea glomerata: Insights into Molluscan Immunity.

Background: Oysters have important ecological functions in their natural environment, acting as global carbon sinks and improving water quality by removing excess nutrients from the water column. During their life-time oysters are exposed to a variety of pathogens that can cause severe mortality in a range of oyster species. Environmental stressors encountered in their habitat can increase the susceptibility of oysters to these pathogens and in general have been shown to impact on oyster immunity, making immune parameters expressed in these marine animals an important research topic.

Quantitative genetic properties of four measures of deformity in yellowtail kingfish Seriola lalandi Valenciennes, 1833.

The main aim of this study was to estimate the heritability for four measures of deformity and their genetic associations with growth (body weight and length), carcass (fillet weight and yield) and flesh-quality (fillet fat content) traits in yellowtail kingfish Seriola lalandi. The observed major deformities included lower jaw, nasal erosion, deformed operculum and skinny fish on 480 individuals from 22 families at Clean Seas Tuna Ltd. They were typically recorded as binary traits (presence or absence) and were analysed separately by both threshold generalized models and standard animal mixed models.

Predictive model for the growth of spoilage bacteria on modified atmosphere packaged Atlantic salmon produced in Australia.

Most existing models for the spoilage of modified atmosphere packed Atlantic salmon are based on the growth of the spoilage organism Photobacterium phosphoreum. However, there is evidence that this organism is not the specific spoilage organism on salmon produced and packaged in Australia. We developed a predictive model for the growth of bacteria in Australian-produced Atlantic salmon stored under modified atmosphere conditions (30-98% carbon dioxide in nitrogen) at refrigeration temperatures (0-10 °C).

Evidence that the major hemolymph protein of the Pacific oyster, Crassostrea gigas, has antiviral activity against herpesviruses.

Viruses belonging to the family Malacoherpesviridae currently pose a serious threat to global production of the Pacific oyster, Crassostrea gigas. Hemolymph extracts from C. gigas are known to have potent antiviral activity.

Anti-viral gene induction is absent upon secondary challenge with double-stranded RNA in the Pacific oyster, Crassostrea gigas.

Oyster farming is one of the most important aquaculture industries in the world. However, its productivity is increasingly limited by viral disease and we do not yet have management practices, such as protective vaccination, that can control these disease outbreaks. Hence, in the current study we investigated the expression of known anti-viral genes in oysters (Crassostrea gigas) in response to primary and secondary encounter with a virus associated molecular pattern (dsRNA), and tested whether a common form of epigenetic gene regulation (DNA methylation) was associated with the expression of these anti-viral genes.

Exploiting genomic data to identify proteins involved in abalone reproduction.

Unlabelled: Aside from their critical role in reproduction, abalone gonads serve as an indicator of sexual maturity and energy balance, two key considerations for effective abalone culture. Temperate abalone farmers face issues with tank restocking with highly marketable abalone owing to inefficient spawning induction methods. The identification of key proteins in sexually mature abalone will serve as the foundation for a greater understanding of reproductive biology.

Ontogeny and water temperature influences the antiviral response of the Pacific oyster, Crassostrea gigas.

Disease is caused by a complex interaction between the pathogen, environment, and the physiological status of the host. Determining how host ontogeny interacts with water temperature to influence the antiviral response of the Pacific oysters, Crassostrea gigas, is a major goal in understanding why juvenile Pacific oysters are dying during summer as a result of the global emergence of a new genotype of the Ostreid herpesvirus, termed OsHV-1 μvar. We measured the effect of temperature (12 vs 22 °C) on the antiviral response of adult and juvenile C.

Preliminary stochastic model for managing Vibrio parahaemolyticus and total viable bacterial counts in a Pacific oyster (Crassostrea gigas) supply chain.

Vibrio parahaemolyticus can accumulate and grow in oysters stored without refrigeration, representing a potential food safety risk. High temperatures during oyster storage can lead to an increase in total viable bacteria counts, decreasing product shelf life. Therefore, a predictive tool that allows the estimation of both V.

Dynamics of seawater bacterial communities in a shellfish hatchery.

Bacterial disease is a significant issue for larviculture of several species of shellfish, including oysters. One source of bacteria is the seawater used throughout the hatchery. In this study carried out at a commercial oyster hatchery in Tasmania, Australia, the diversity of the bacterial community and its relationship with larval production outcomes were studied over a 2-year period using terminal restriction fragment length polymorphism and tag-encoded pyrosequencing.

Use of near infrared spectroscopy to predict microbial numbers on Atlantic salmon.

The potential of a near infrared spectroscopy (NIR) method to detect as well as predict microbial spoilage on Atlantic salmon (Salmo salar) was investigated. Principal component analysis (PCA) of the NIR spectra showed clear separation between the fresh salmon fillets and those stored for nine days at 4°C indicating that NIR could detect spoilage. A partial least squares regression (PLS) prediction model for total aerobic plate counts after nine days was established using the NIR spectra collected when the fish was fresh to predict the number of bacteria that would be present nine days later.

Use of a blocking primer allows selective amplification of bacterial DNA from microalgae cultures.

The production of algae is a crucial component of many aquaculture systems and the role of bacteria in this process is an important although complex one. We report the development of a new blocking primer that allowed PCR amplification of bacterial DNA in the presence of algal chloroplast DNA.

Molecular analysis of the bacterial communities in the live Pacific oyster (Crassostrea gigas) and the influence of postharvest temperature on its structure.

Aims: To evaluate the effect of postharvest temperature on bacterial communities in live Pacific oysters (Crassostrea gigas) using nonculture-based methods.

Methods And Results: Live oysters were compared before and after storage at 4, 6, 15, 20 and 30°C using terminal restriction fragment length polymorphism (T-RFLP). Bacterial communities in freshly harvested (control) vs stored oysters were significantly different.

Microbial communities on Australian modified atmosphere packaged Atlantic salmon.

The role of specific spoilage organisms (SSO) in products such as Atlantic salmon has been well documented. However, little is known about what other micro-organisms are present and these organisms may indirectly influence spoilage by their interactions with the SS0. We used a combination of culture-based and DNA-based methods to explore the microbial communities found on Atlantic salmon fillets packed in a modified atmosphere of carbon dioxide and nitrogen.

Predictive models for the effect of storage temperature on Vibrio parahaemolyticus viability and counts of total viable bacteria in Pacific oysters (Crassostrea gigas).

Vibrio parahaemolyticus is an indigenous bacterium of marine environments. It accumulates in oysters and may reach levels that cause human illness when postharvest temperatures are not properly controlled and oysters are consumed raw or undercooked. Predictive models were produced by injecting Pacific oysters (Crassostrea gigas) with a cocktail of V.

Predicting glycogen concentration in the foot muscle of abalone using near infrared reflectance spectroscopy (NIRS).

Near infrared reflectance spectroscopy (NIRS) was used to predict glycogen concentrations in the foot muscle of cultured abalone. NIR spectra of live, shucked and freeze-dried abalones were modelled against chemically measured glycogen data (range: 0.77-40.