Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 2. The early life stages of the coral Acropora tenuis

The success of early life history transitions of the coral Acropora tenuis were used as endpoints to evaluate thermal stress and the effects of wastewater discharged to a tropical marine environment. The studies assessed the effects of: (i) temperature; (ii) three signature metals of the wastewater, aluminium (Al), vanadium (V) and gallium (Ga); and (iii) the wastewater (at 27 °C and 32 °C) on fertilisation and larval metamorphosis. The median inhibition temperatures for fertilisation and metamorphosis were 32.8 °C and 33.0 °C, respectively. Fertilisation IC₅₀s for Al, V and Ga were 2997, 2884 and 3430 μg L⁻¹, respectively. Metamorphosis IC₅₀s for Al, V and Ga were 1945, 675 and 3566 μg L⁻¹, respectively. The wastewater only affected fertilisation and metamorphosis at moderate concentrations (IC₅₀s = 63% and 67%, v/v, respectively, at 27 °C), posing a low risk to this species in the field. The effects of wastewater and temperature on fertilisation and metamorphosis were additive.     

Why are hatching and emergence success low? Mercury and selenium concentrations in nesting leatherback sea turtles (Dermochelys coriacea) and their young in Florida

Leatherback sea turtles (Dermochelys coriacea) have low hatching and emergence success compared to other sea turtle species. Postmortem examinations of hatchlings showed degeneration of heart and skeletal muscle that was similar to that found in other neonates with selenium deficient mothers. Selenium deficiency can result from elevated concentrations of bodily mercury. Ingested mercury is detoxified by the liver through mercury-selenium compound formation. In animals persistently exposed to mercury, the liver’s ability to detoxify this element may decrease, especially if dietary selenium is insufficient. We measured mercury and selenium concentrations in nesting female leatherbacks and their hatchlings from Florida and compared the levels to hatching and emergence success. Both liver selenium and the liver selenium-to-mercury ratio positively correlated with leatherback hatching and emergence success. This study provides the first evidence for the roles of mercury and selenium in explaining low reproductive success in a globally imperiled species, the leatherback sea turtle.     

饲养场与牲畜防护林的基本设计标准

饲养场与牲畜防护林的基本设计标准ＤａｖｉｄＬ．Ｈｉｎｔｚ饲养场与牲畜防护林的主要目的是为了防止风害与吹雪，在冷天它的背风面防护区可以为牲畜提供广大的御寒场所。经验表明，合理的设计能使饲养场防护林发挥它应有的作用，牲畜能够得到保护并获得最大效益；与此相...     

Perturbation of gene expression and steroidogenesis with in vitro exposure of fathead minnow ovaries to ketoconazole

Ketoconazole is a fungicidal drug that inhibits function of cytochrome P450s in the synthesis of steroids. To examine if inhibition of P450 function affects gene expression in a dynamic manner, we conducted in vitro exposures of ovary tissue from fathead minnows (Pimephales promelas) to 0.5 microM ketoconazole to investigate effects on steroid production and gene expression over time. Expression of four key steroidogenesis genes was examined at 1, 6, and 12h of exposure. 11 beta- and 20 beta-hydroxysteroid dehydrogenases were down regulated at 1h and Cytochrome P450 17 was down-regulated at 12h, consistent with the absence of steroid production. In contrast, cytochrome P450 19A was up-regulated at 6h, indicating feedback regulation. Microarray analysis of 12h exposures indicated enrichment of biological processes involved in neurotransmitter secretion, lymphocyte cell activation, sodium ion transport, and embryonic development. These data suggest that, with the exception of cytochrome P450 19A, these steroid metabolic genes are regulated in a feed forward manner and that the effects of ketoconazole may be broader than anticipated based on the mechanism of action alone.