Coupling bio-logging with nutritional geometry to reveal novel insights into the foraging behaviour of a plunge-diving marine predator

It is widely believed that predators maximise their energy intake while foraging and consume prey that are nutritionally similar. We combined GPS data loggers, miniaturised cameras, dietary sampling and nutritional geometry to examine the nutritional variability in the prey and selected diet, and foraging performance, of the masked booby (Sula dactylatra tasmani), a wild carnivore and marine top predator. Data loggers also revealed no significant differences between sexes in the foraging performance of chick-rearing adults. Females provided more food to their chicks than the males and, regardless of the nutritional variability of prey consumed, both sexes showed similar amounts of protein and lipid in their diets. Miniaturised cameras combined with nutritional analysis of prey provided, for the first time, fine-scale detail of the amounts of macronutrients consumed in each plunge dive and the overall foraging trip. Our methodology could be considered for future studies that aim to contribute to the general understanding of the behavioural and physiological mechanisms and ecological and evolutionary significance of animal foraging (e.g. energy expenditure budgets and prey selection for self- and offspring-feeding that could lead to sex-specific foraging strategies).     

Comparison of microsomal lipid peroxidation in fish and rats

Lipid peroxidation, which is promoted in animal tissues by a variety of toxic agents, is believed to be associated with disruption of cell membranes and loss of activity of membrane-bound enzymes. While the process of lipid peroxidation has been well studied in mammals, only a few non-mammalian species have been examined.¹ In the present study, in vitro assays for lipid peroxidation were performed using microsomes prepared from the livers of rats (Rattus rattus) and a marine fish, mullet (Mugil cephalus). Although lipid peroxidation was observed in microsomes prepared from both mullet and rat tissues, and was stimulated by xenobiotics, the mechanisms of generation appeared to be different. In contrast to rats, NADH was much more effective than NADPH in stimulating lipid peroxidation in mullet liver microsomes. The results suggest that NADH-dependent, as well as NADPH-dependent, lipid peroxidation may be important in vertebrate tissues.     

Predictions of the extent of self-enrichment in oxygen of giant metal-poor H ii regions

In general, H  ii regions do not show clear signs of self-enrichment in products from massive stars  ( M ≥ 8 M_⊙)  . In order to explore why I modelled the contamination with Wolf–Rayet star ejecta of metal-poor  ( Z = 0.001)  H  ii regions, ionized either by a  10⁶ M_⊙  cluster of coeval stars (cluster 1) or by a cluster resulting from continuous star formation at a rate of  1 M_⊙ yr⁻¹  (cluster 2). The clusters have   Z = 0.001  and a Salpeter initial mass function from 0.1 to  120 M_⊙  . Independent one-dimensional constant density simulations of the emission-line spectra of unenriched H  ii regions were computed at the discrete ages 1, 2, 3, 4 and 5 Myr, with the photoionization code cloudy , using as input, radiative and mechanical stellar feedbacks predicted by the evolutionary synthesis code starburst99 . Each H  ii region was placed at the outer radius of the adiabatically expanding superbubble of Mac Low & McCray. For models with thermal and ionization balance time-scales of less than 1 Myr, and with oxygen emission-line ratios in agreement with observations, the volume of the superbubble and the H  ii region was uniformly and instantaneously polluted with stellar ejecta predicted by starburst99 . I obtained a maximum oxygen abundance enhancement of 0.025 dex, with cluster 1, at 4 Myr. It would be unobservable.     

贺兰山北段牛头沟金矿区围岩的原岩恢复、时代及其地质意义

牛头沟金矿区位于华北陆块鄂尔多斯地块西缘贺兰山北段之基底杂岩带,赋矿地层为一套古元古界宗别立群第二亚群(Pt1Z2)中-深程度变质岩系,主要岩石类型是黑云斜长片麻岩和变粒岩。岩石地球化学特征分析及原岩恢复说明,蚀变岩型金矿体的围岩由正、副变质岩类共同组成,其中变粒岩的原岩为沉积碎屑岩,黑云斜长片麻岩的原岩为花岗闪长质侵入岩。离子探针锆石U-Pb定年表明,表壳岩的形成时代小于2120Ma,花岗闪长岩锆石U-Pb年龄为1950±8.9Ma,辉绿岩脉的侵入与花岗闪长岩属同期。综合研究表明,矿区变质岩的原岩形成时代不是前人认为的晚太古代,而是古元古代。同时应将属于正变质岩类黑云斜长片麻岩(原岩为花岗闪长岩)从宗别立群(Pt1Z)地层中分离出来,作为侵入岩单元考虑。     

Interactions of cadmium with sulfhydryl-containing compounds in striped mullet (mugil cephalus L.)

Interactions between cadmium and sulfhydryl-containing compounds in striped mullet, Mugil cephalus, were examined. Exposure to 10 mg Cd/liter for up to 6 weeks caused an increase in the acid-soluble thiol (AST) content of the liver. Although the AST concentration was elevated at 1·4 weeks, increases in the glutathione and cysteine contents were not observed until after 4 weeks of exposure. Homogenates of livers were fractionated on a Sephadex G-75 column. A homogenate of livers of mullet injected with ¹⁰⁹Cd 2 days prior to sampling had an elution profile for thiols similar to controls. After 3 weeks exposure to 10 mg Cd/liter the 9400 MW thiol peak increased 3·6-fold and the peak with the same retention volume as glutathione increased 4·3-fold. Greater than 70% of the thiols in these two peaks were acid-soluble. In both experiments, almost all the cadmium was associated with the 9400 MW peak. The ratio in the 9400 MW peak declined from 14·1 (controls) to 3·2 after 3 weeks exposure. No cadmium was associated with glutathione in the bile.