An interview with Terence Charlston and Alexander Rolton

Keyboard specialist Terence Charlston and his organ student Alexander Rolton discuss their working relationship. Interview by Rhian Morgan

Interactions between Crassostrea virginica larvae and Deepwater Horizon oil: Toxic effects via dietary exposure

International audienceThe Deepwater Horizon (DWH) disaster released crude oil in the Gulf of Mexico for 87 days, overlapping with the reproductive season and recruitment of the oyster Crassostrea virginica. The pelagic larval life stages of C. virginica are particularly vulnerable to contaminants such as polycyclic aromatic hydrocarbons (PAHs) and oil droplets. Based on their lipophilic properties, PAHs and oil droplets can adsorb onto phytoplankton and filter-feeding C. virginica larvae may be exposed to these contaminants bound to suspended sediment, adsorbed onto algal and other particles, or in solution. This study examined the effects of exposure of C. virginica larvae to algae mixed with DWH oil. In a 14-day laboratory exposure, 5 day-old C. virginica larvae were exposed to Tisochrysis lutea mixed with four concentrations of unfiltered DWH oil (HEWAF) in a static renewal system. Larval growth, feeding capacity, abnormality and mortality were monitored throughout the exposure. Total PAH (n = 50) content of the water medium, in which larvae were grown, were quantified by GC/MS-SIM. Oil droplets were observed bound to algae, resulting in particles in the size-range of food ingested by oyster larvae (1–30 μm). After 14 days of exposure, larval growth and survival were negatively affected at concentrations of tPAH50 as low as 1.6 μg L−1. GC/MS-SIM analysis of the exposure medium confirmed that certain PAHs were also adsorbed by T. lutea and taken up by oyster larvae via ingestion of oil droplets and/or contaminated algae. Long-term exposure to chronic levels of PAH (1.6–78 μg tPAH50 L−1) was shown to negatively affect larval survival. This study demonstrates that dietary exposure of oyster larvae to DWH oil is a realistic route of crude oil toxicity and may have serious implications on the planktonic community and the food chain

Nephrocalcinosis in preterm babies

OBJECTIVES—To determine prospectively the incidence and cause of nephrocalcinosis in preterm infants.
STUDY DESIGN—Inborn babies of gestation less than 32 weeks or birth weight less than 1500 g were eligible to be entered into a prospective observational study. Two renal ultrasound scans were performed, the first at 1 month postnatal age and the second at term or discharge. Data were collected on gestation, birth weight, sex, race, family history of renal calculi, oliguria on first day, respiratory support (ventilation, steroid, and oxygen dependency), and use of nephrotoxic drugs (gentamicin, vancomycin, and frusemide). Intake of fluid, calcium, and phosphate and plasma urea, creatinine, calcium, and phosphate were recorded for the first 6 weeks of life. Random urinary calcium/creatinine, oxalate/creatinine, and urate/creatinine ratios and tubular absorption of phosphate were measured once at term.
RESULTS—A total of 101 preterm infants were studied. Twenty three (23%) had abnormal ultrasound scans. Sixteen (16%) had nephrocalcinosis. On univariate analysis, gestational age, male sex, duration of ventilation, oxygen dependency, duration and frequency of gentamicin treatment, toxic gentamicin/vancomycin levels, and postnatal dexamethasone were significantly associated with nephrocalcinosis. In addition, babies with nephrocalcinosis had a lower intake of fluid, calcium, and phosphate, longer duration of total parenteral nutrition, and higher urinary oxalate/creatinine and urate/creatinine ratios than infants who did not have the condition. There was also a significant association with plasma urea and creatinine but not with plasma calcium or phosphate or urinary calcium. Multivariate analysis showed that the strongest predictors of nephrocalcinosis were duration of ventilation, toxic gentamicin/vancomycin levels, low fluid intake, and male sex.
CONCLUSION—16% of babies born at less than 32 weeks gestation developed nephrocalcinosis. The multifactorial origin, in particular, the association with extreme prematurity and severity of respiratory disease, is confirmed. In addition, an association with male sex, frequency and duration of gentamicin use, and high urinary oxalate and urate excretion is shown.


Sensitivity of eastern oyster ( Crassostrea virginica) spermatozoa and oocytes to dispersed oil: Cellular responses and impacts on fertilization and embryogenesis

The 2010 Deepwater Horizon (DWH) oil spill released millions of barrels of oil and dispersant into the Gulf of Mexico. The timing of the spill coincided with the spawning season of Crassostrea virginica. Consequently, gametes released in the water were likely exposed to oil and dispersant. This study aimed to (i) evaluate the cellular effects of acute exposure of spermatozoa and oocytes to surface slick oil, dispersed mechanically (HEWAF) and chemically (CEWAF), using flow-cytometric (FCM) analyses, and (ii) determine whether the observed cellular effects relate to impairments of fertilization and embryogenesis of gametes exposed to the same concentrations of CEWAF and HEWAF. Following a 30-min exposure, the number of spermatozoa and their viability were reduced due to a physical action of oil droplets (HEWAF) and a toxic action of CEWAF respectively. Additionally, reactive oxygen species (ROS) production in exposed oocytes tended to increase with increasing oil concentrations suggesting that exposure to dispersed oil resulted in an oxidative stress. The decrease in fertilization success (1-h), larval survival (24-h) and increase in abnormalities (6-h and 24-h) may be partly related to altered cellular characteristics. FCM assays are a good predictor of sublethal effects especially on fertilization success. These data suggest that oil/dispersant are cytotoxic to gametes, which may affect negatively the reproduction success and early development of oysters