Wolves in sheep’s clothing: three new cases of aggressive mimicry in Red Sea coral reef fishes

ABSTRACT

Here we document three cases of mimicry in coral reef fishes not previously reported in the literature involving two groupers (Epinephelus leucogrammicus and Plectropomus marisrubri) and a soapfish (Diploprion drachi) as mimics, and two wrasses (Larabicus quadrilineatus and Cheilinus quinquecinctus) and a blenny (Meiacanthus nigrolineatus) as models. All three cases are of aggressive mimicry, with a predatory species mimicking a harmless one, and in one of the cases, the mimicry is also Müllerian, where both the predator and harmless species are unpalatable.     

The occurrence and significance of C25HBI in Cenozoic saline lacustrine source rocks from the Western Qaidam Basin,NW China

The saline lacustrine deposit of the Oligocene Lower Ganchaigou Formation is the main source rock for the Western Qaidam Basin,NW China.In this study,abundant highly branched isoprenoids with 25 carbon atoms (C25HBI) were detected in the upper section of the Lower Ganchaigou Formation.C25HBI is a biomarker for diatoms,and can provide information regarding biogeochemical processes during production and preservation of sedimentary organic matter.The carbon isotopic values of C25HBI in these source rocks were in the range of-18‰ to-20‰.The relative enrichment in 13C of C25HBI suggests that these isoprenoids were derived from diatom blooms.In this case,the diatoms used HCO3-as an additional carbon source to dissolved CO2 in water column due to their high biological productivity.Conversely,the diatom blooms indicated an abundant nutrient supply to the environment and high primary productivity.Thus,the occurrence of 13C-enriched C25HBI could be an ideal marker for good source rocks.The decreased concentration of CO2(aq) in the water column induced by diatom blooms can result in an enrichment in 13C of organic matter synthesized by primary producers.This may be a possible reason for the occurrence of 13C-enriched organic matter in the Cenozoic source rocks of the Western Qaidam Basin.Previous studies have shown that the high carbon number n-alkanes sourced from diatoms have no carbon preference.Hence,the sources of n-alkanes in regional source rocks are complex,and should be considered when discussing the sources of organic matter in future studies.     

Gastric mucus effusion elicited by oral copper compounds: Potential anti-ulcer activity

Summary In rats, both Cu(I) and Cu(II) show an irritancy profile not shared with Cu^o or Zn(II) or Ni(II). The gastric response to Cu(II), i.e. copius fluid and mucus secretion, can protect the stomach from the acute ulcerative effects of aspirin or physical stress administered subsequently.to whom all enquiries should be addressed, Supported by grants from the National Health and Medical Research Council (Austr.) and University of Tasmania Research Commitee.Acknowledgments: ProfessorsW. R. Walker (Newcastle, Austr.) andL. Field (Nashville, Tenn.) for gifts of Cu(I) and Zn complexes;Dr. J. R. J. Sorenson (Cincinnatti, Ohio) for illuminating discussion; Drs.D. D. Perrin (Canberra) andR. P. Agarwal (Washington D. C.) for providing stability constants and much helpful advice.     

Investigation on the synthesis mechanism of β-FeSi2 prepared by pulsed laser deposition

The FeSi2 target alloy was fabricated by conventional powder metallurgy technology, and then, β-FeSi2 thin films was successfully prepared by pulsed laser deposition (PLD). X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the structure, composition, and their changes in the process of β-FeSi2 preparation. In addition, a laser sintering process was also employed to prepare FeSi2 alloy. The analysis of radiation heat transfers in different-sized FeSi2 melt indicates that the cooling rate of the melt depends on the size, i.e., the cooling rate of the micron sized melt is 103 times greater than that of the millimeter-sized melt. The product α-FeSi2 by laser sintering and β-FeSi2 by PLD reveals the different phase transition process in crystallization of milli-meter-sized and micron-sized (or submicron-sized) FeSi2 melt. The results of PLD preparation process shows that β-FeSi2 could be pre-pared through a liquid-phase sintering, followed by a rapid cooling.     

Acid glycosaminoglycan composition of aortic tissue from chickens fed on commercial and on cholesterol-supplemented diets

Zusammenfassung Es wird gezeigt, dass die Verteilung von Glukosaminoglykane in der Hühneraorta offenbar im Unterschied zu menschlichem Aortengewebe in Abhängigkeit der topographischen Lage steht. Höchste Gesamtwerte für Glykosaminoglykan wurden in der Brustaorta, niedrigste in der abdominalen Aorta gefunden.     

Deposition of 1.88-billion-year-old iron formations as a consequence of rapid crustal growth

Iron formations are chemical sedimentary rocks comprising layers of iron-rich and silica-rich minerals whose deposition requires anoxic and iron-rich (ferruginous) sea water. Their demise after the rise in atmospheric oxygen by 2.32?billion years (Gyr) ago has been attributed to the removal of dissolved iron through progressive oxidation or sulphidation of the deep ocean. Therefore, a sudden return of voluminous iron formations nearly 500?million years later poses an apparent conundrum. Most late Palaeoproterozoic iron formations are about 1.88?Gyr old and occur in the Superior region of North America. Major iron formations are also preserved in Australia, but these were apparently deposited after the transition to a sulphidic ocean at 1.84?Gyr ago that should have terminated iron formation deposition, implying that they reflect local marine conditions. Here we date zircons in tuff layers to show that iron formations in the Frere Formation of Western Australia are about 1.88?Gyr old, indicating that the deposition of iron formations from two disparate cratons was coeval and probably reflects global ocean chemistry. The sudden reappearance of major iron formations at 1.88?Gyr ago--contemporaneous with peaks in global mafic-ultramafic magmatism, juvenile continental and oceanic crust formation, mantle depletion and volcanogenic massive sulphide formation--suggests deposition of iron formations as a consequence of major mantle activity and rapid crustal growth. Our findings support the idea that enhanced submarine volcanism and hydrothermal activity linked to a peak in mantle melting released large volumes of ferrous iron and other reductants that overwhelmed the sulphate and oxygen reservoirs of the ocean, decoupling atmospheric and seawater redox states, and causing the return of widespread ferruginous conditions. Iron formations formed on clastic-starved coastal shelves where dissolved iron upwelled and mixed with oxygenated surface water. The disappearance of iron formations after this event may reflect waning mafic-ultramafic magmatism and a diminished flux of hydrothermal iron relative to seawater oxidants.