The diversity of marine sterols and the role of algal bio-masses; from facts to hypothesis

Modern analytical methods have revealed the great variety of marine sterols, which possess many different side chains and unsaturation patterns. Such biochemical transformations require well-defined mechanistic pathways, and there must be some 'Raison d'Etre' for a situation which has withstood evolution and adaptive changes. However, in this area, insufficient and sometimes not very substantial experimental work has made it difficult to see correlations, and hence to form a solid hypothesis. A review is now presented in which the molecules dissolved in sea water, or found in marine organisms are considered with particular reference to algal production, and to the bio-ecological significance of the main sterols.     

Minor nitrogenous sesquiterpenes from the marine spongeAxinella cannabina. A hypothesis for the biogenesis of the spiro-axane skeleton

Summary Three nitrogenous sesquiterpenoids (4–6), possessing an isocyanide, isothiocyanate or formylamino function, have been isolated from the marine spongeAxinella cannabina. The proposed structures were based on interpretation of spectral data including 2D-NMR techniques and chemical evidence. A plausible pathway for the biogenesis of these compounds and the co-occurring spiro-axane (1–3) metabolites is proposed.Work supported by C.N.R. (Progetto Finalizzato Chimica Fine e Secondaria and by MPI Italy.     

The sterols of the echinoderm,Ctenodiscus crispatus retzius

Zusammenfassung Aus dem SchlammsternCtenodiscus crispatus wurde ein kompliziertes Gemisch von Sterolen isoliert, die als Homologe des 5-Cholest-7-en-3-ols und deren 24-Methylderivate erkannt wurden.     

Comparison of sterols from a phytophagous and predacious species of the family coccinellidae

Summary The sterols of a phytophagous and a predacious species of the family Coccinellidae were found to be quite different from each other, indicating that adaptation to different diet regimens is reflected in the utilization and metabolism of dietary sterols.We thank Dr George Angalet, USDA Beneficial Insects Research Laboratory, Federal Research, SEA, Newark, DE, for providing us with the adultCoccinella septempunctata used in this study.     

The sterols of the khapra beetle, Trogoderma granarium Everts

The khapra beetle, Trogoderma granarium Everts, does not dealkylate and convert dietary C28- or C29-Phytosterols to C27-sterols such as cholesterol. There is, however, an increase in the concentration of cholesterol and campesterol in its tissues relative to the dietary concentrations of these sterols, presumably as a result of selective uptake.     

The sterols of the khapra beetle,Trogoderma granarium everts

Summary The khapra beetle,Trogoderma granarium Everts, does not dealkylate and convert dietary C₂₈- or C₂₉-phytostorols to C _2T sterols such as cholesterol. There is, however, an increase in the concentration of cholesterol and campesterol in its tissues relative to the dietary concentrations of these sterols, presumably as a result of selective uptake.We thank Dr S. R. Dutky of the Insect Physiology Laboratory, Agricultural Research, SEA, USDA, Beltsville, Maryland for providing GC-MS analyses.     

Some surprising facts about (the problem of) surprising facts: (from the Dusseldorf Conference,February 2011)

A common intuition about evidence is that if data x have been used to construct a hypothesis H, then x should not be used again in support of H. It is no surprise that x fits H, if H was deliberately constructed to accord with x. The question of when and why we should avoid such “double-counting” continues to be debated in philosophy and statistics. It arises as a prohibition against data mining, hunting for significance, tuning on the signal, and ad hoc hypotheses, and as a preference for predesignated hypotheses and “surprising” predictions. I have argued that it is the severity or probativeness of the test—or lack of it—that should determine whether a double-use of data is admissible. I examine a number of surprising ambiguities and unexpected facts that continue to bedevil this debate.     

The role of bHLH genes in ear development and evolution: revisiting a 10-year-old hypothesis

In mouse ear development, two bHLH genes, Atoh1 and Neurog1, are essential for hair cell and sensory neuron differentiation. Evolution converted the original simple atonal-dependent neurosensory cell formation program of diploblasts into the derived developmental program of vertebrates that generates two neurosensory cell types, the sensory neuron and the sensory hair cell. This transformation was achieved through gene multiplication in ancestral triploblasts resulting in the expansion of the atonal bHLH gene family. Novel genes of the Neurogenin and NeuroD families are upregulated prior to the expression of Atoh1. Recent data suggest that NeuroD and Neurogenin were lost or their function in neuronal specification reduced in flies, thus changing our perception of the evolution of these genes. This sequence of expression changes was accompanied by modification of the E-box binding sites of these genes to regulate different downstream genes and to form inhibitory loops among each other, thus fine-tuning expression transitions.     

Inference to the hypothesis of extended cognition

This paper examines the justification for the hypothesis of extended cognition (HEC). HEC claims that human cognitive processes can, and often do, extend outside our head to include objects in the environment. HEC has been justified by inference to the best explanation (IBE). Both advocates and critics of HEC claim that we can infer the truth value of HEC based on whether HEC makes a positive or negative explanatory contribution to cognitive science. I argue that IBE cannot play this epistemic role. A serious rival to HEC exists with a differing truth value, and this invalidates IBEs for both the truth and the falsity of HEC. Explanatory value to cognitive science is not a guide to the truth value of HEC.     

The puzzle of half-integral quanta in the application of the adiabatic hypothesis to rotational motion

We present and discuss an interesting and puzzling problem Ehrenfest found in his first application of the adiabatic hypothesis, in 1913. It arose when trying to extend Planck׳s quantization of the energy of harmonic oscillators to a rotating dipole within the frame of the old quantum theory. Such an extension seemed to lead unavoidably to half-integral values for the rotational angular momentum of a system (in units of ℏ). We present the problem in its original form along with the (few) responses we have found to Ehrenfest׳s treatment. After giving a brief account of the classical and quantum adiabatic theorem, we also describe how Quantum Mechanics provides an explanation for this difficulty.     

Alkaline phosphatase binds to collagen; a hypothesis on the mechanism of extravesicular mineralization in epiphyseal cartilage

Affinity chromatography on Sepharose 4B-collagen gels was used to test the affinity of alkaline phosphatase for collagen. Results indicate that alkaline phosphatase of preosseous cartilage binds to collagen probably by electrostatic interactions, this interaction is inhibited by proteoglycan subunits. These results suggest that, in vivo, the formation of a collagen-alkaline phosphatase complex may be a step of the process leading to cartilage calcification.     

Alkaline phosphatase binds to collagen; a hypothesis on the mechanism of extravesicular mineralization in epiphyseal cartilage

Summary Affinity chromatography on Sepharose 4B-collagen gels was used to test the affinity of alkaline phosphatase for collagen. Results indicate that 1) alkaline phosphatase of preosseous cartilage binds to collagen probably by electrostatic interactions, 2) this interaction is inhibited by proteoglycan subunits. These results suggest that, in vivo, the formation of a collagen-alkaline phosphatase complex may be a step of the process leading to cartilage calcification.This investigation was supported by research grants of C.N.R. (C.T. 82.02437.04), of Ministero della Pubblica Istruzione and of the University of Trieste.To whom correspondence and reprint requests should be addressed.     

Renouvier and the method of hypothesis

Renouvier was among the first philosophers in France to break with the nineteenth-century inductivist tradition and defend the use of hypotheses in science. Earlier in the century, the humanistically-educated eclectic spiritualist philosophers who dominated French academic life had followed Reid in proscribing the use of hypotheses. Renouvier, who was educated in the sciences, took up the Comtean positivist alternative and developed it further. He began by defending hypotheses that anticipate laws governing the phenomena, but then eventually adopted a more liberal attitude towards hypotheses that postulate unobservable entities and processes as well. He also came to the realization that, from an epistemological point of view, all of empirical science is hypothetical. Renouvier used the tentative character of scientific knowledge as a premise from which to critique those who would claim scientific status for their social philosophies, and maintained a distinction between normative philosophical and empirical scientific inquiries.     

An hypothesis to explain the relation between the synthesis and release of animal viruses from infected cells and the lipid content of the viruses

Zusammenfassung Eine Hypothese über die Synthese und die Freisetzung von tierpathogenen Viren wird entwickelt. Diejenigen Viren, die durch einen kontinuierlichen Prozess freigesetzt werden, werden an der Zellperipherie zusammengefügt. Beim Durchtritt durch die Zellmembran erhalten sie eine Schutzhülle aus Lipiden, die aus den in der Zellmembran lokalisierten Lipiden der Wirtszelle stammen. Alle derartigen Viren sind gegen Äther empfindlich und enthalten Lipide als essentiellen Bestandteil. Diejenigen Viren, die stossartig freigesetzt werden, werden dagegen im Innern der Zelle zusammengefügt und enthalten keine essentielle Lipid-Komponente. Diese Hypothese wird auch auf die Tumor-Viren angewandt.     

The influence of several sterols on the conversion ofβ-sitosterol into cholesterol in the cockroach

Zusammenfassung Die Umwandlung von-Sitosterol in Cholesterol in der SchabeBlattella germanica L. wird durch bestimmte Sterine mit unnatürlichen Seitenketten gehemmt. Anhäufung von zwei verschiedenen Metaboliten wurde festgestellt.

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This work was supported by a grant from the National Council for Agricultural Research TNO.     

The localized crossover and a new hypothesis of chromosomal interference

Zusammenfassung Die beiDrosophila beobachtete Herabsetzung der Häufigkeit von Doppelaustausch innerhalb von benachbarten Chromosomenabschnitten lässt sich nicht nur durch die klassische Annahme einer gegenseitigen Interferenz zwischen benachbarten crossing-overs erklären, sondern kann auch durch das Vorkommen von lokalisierten crossing-overs innerhalb von bestimmten, engbegrenzten Chromosomenregionen bedingt sein.

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This work has been supported by a research grant from the National Cancer Institute of the National Institutes of Health, U. S. Public Health Service C-2140.