Impact of Ocean Warming and Ocean Acidification on Larval Development and Calcification in the Sea Urchin Tripneustes gratilla

Background: As the oceans simultaneously warm, acidify and increase in P-CO2, prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming.Methodology/Principal Findings: We examined the interactive effects of near-future ocean warming and increased acidification/P-CO2 on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/P-CO2 treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/P-CO2 and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3 degrees C) stimulated growth, producing significantly bigger larvae across all pH/P-CO2 treatments up to a thermal threshold (+6 degrees C). Increased acidity (-0.3-0.5 pH units) and hypercapnia significantly reduced larval calcification. A +3 degrees C warming diminished the negative effects of acidification and hypercapnia on larval growth.Conclusions and Significance: This study of the effects of ocean warming and CO2 driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization) shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high P-CO2 ocean would likely impair their performance with negative consequent effects for benthic adult populations

Metabolic inactivation of estrogens in breast tissue by UDP-glucuronosyltransferase enzymes: an overview

The breast tissue is the site of major metabolic conversions of estradiol (E(2)) mediated by specific cytochromes P450 hydroxylations and methylation by catechol-O-methytransferase. In addition to E(2 )itself, recent findings highlight the significance of 4-hydroxylated estrogen metabolites as chemical mediators and their link to breast cancer development and progression, whereas, in opposition, 2-methoxylated estrogens appear to be protective. Recent data also indicate that breast tissue possesses enzymatic machinery to inactivate and eliminate E(2 )and its oxidized and methoxylated metabolites through conjugation catalyzed by UDP-glucuronosyltransferases (UGTs), which involves the covalent addition of glucuronic acid. In opposition to other metabolic pathways of estrogen, the UGT-mediated process leads to the formation of glucuronides that are devoid of biologic activity and are readily excreted from the tissue into the circulation. This review addresses the most recent findings on the identification of UGT enzymes that are responsible for the glucuronidation of E(2 )and its metabolites, and evidence regarding their potential role in breast cancer

Overview of phenotypic plasticity in echinoid larvae, 'Echinopluteus transversus' type vs. typical echinoplutei

Many sea urchin echinoplutei exhibit phenotypic plasticity, increasing arm length to enhance food capture in nutrient poor conditions. We tested this phenomenon in species with contrasting larval forms reared in similar feeding conditions. Heliocidaris tuberculata has a typical echinopluteus larva with 4 pairs of arms while Centrostephanus rodgersii larvae have only 1 pair of arms (‘Echinopluteus transversus’ type larva). Larvae were exposed to high, medium and no food treatments. The ratio ‘postoral arm length’ to ‘midline body length’ (PO:MBL) was used to document phenotypic plasticity. Fed H. tuberculata larvae developed short postoral arms and low PO:MBL, while starved larvae developed long postoral arms and high PO:MBL, indicative of plastic arm growth. In contrast, well fed C. rodgersii larvae had the longest arms and high PO:MBL, indicating the absence of plastic arm growth. Taking MBL into account, ANCOVA revealed that differences among treatments were due to PO. The hypothesis that starved C. rodgersii larvae would develop long arms was not supported. Principal component analysis confirmed that larvae in different food treatments had distinct morphologies and that H. tuberculata and C. rodgersii had opposite growth patterns with respect to food treatment. We suggest that ‘Echinopluteus transversus’ type larvae are adapted for long distance dispersal, and with only 2 arms for feeding and swimming, there may be an imperative to maintain arm length irrespective of food conditions. Phenotypic plasticity in echinopluteal arm growth is not universal and may be influenced by phylogeny, latitude and the hydromechanics of larval form.Natalie Anne Soars, Thomas Aelfwyn Arthur Prowse, Maria Byrn