In his recent review of the developing theory of insect-plant interactions, Gilbert (52) identified four major thrusts in research: insect-plant coevolution, host plants as islands, plant apparency and chemical defense, and resource predictability versus evolutionary strategies of insects. From his review it is evident that, with a few exceptions (23, 45, 53, 64), developing theory is addressing primarily a two trophic level system. In reality, of course, all terrestrial communities based on living plants are composed of at least three interacting trophic levels: plants, herbivores, and natural enemies of herbivores. We argue that theory on insect-plant interactions cannot progress realistically without consideration of the third trophic level. A closer look at the mechanisms of interactions reveals a paradox, and plants have many effects, direct and indirect, positive and negative, not only on herbivores but also on the enemies of herbivores. The third trophic level must be considered as part of a plant's battery of defenses against herbivores.

http://max2.ese.u-psud.fr/epc/conservation/PDFs/HIPE/Price1980.pdf

Interactions Among Three Trophic Levels: Influence of Plants on Interactions Between Insect Herbivores and Natural Enemies

Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.

The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders.

With the help of the highly specific and sensitive fluorescence method of Falck and Hillarp together with the histochemical and pharmacological criteria for the specificity of the fluorescence reaction convincing evidence has been obtained that the fine, varicose nerve fibres observed in a vast number of regions in the mammalian central nervous system (mouse, hamster, rat, guineapig, rabbit, cat), which exhibit a green or yellow fluorescence, contain primary catecholamines and 5-HT respectively. Strong support has been given for the view that CA fibres showing a rapid recovery after administration of α-MMT contain DA, while those showing a slow recovery contain NA. There is little doubt that the monoamine-containing fibres in the brain represent the terminal ramifications of axons belonging to specific monoamine neurons and that they are true synaptic terminals. They seem to make their contacts via the varicosities which have extremely high concentrations of amines and in all probability represent the presynaptic structures, specialized for synthesis, storage and release of the amines. The central monoamine terminals thus have the same characteristic appearance as the adrenergic synaptic terminals in the peripheral nervous system. All the data strongly support the view that the specific central neurons giving rise to the terminals are monoaminergic, i.e. function by releasing their amines from the synaptic terminals. Consequently, DA, NA and 5-HT seem to be central neurotransmitters. Not only the median eminence but also the nuc. caudatus putamen, tuberculum olfactorium, nuc. accumbens and the small circumscribed areas medial to nuc. accumbens contain very fine (partly sublightmicroscopical) CA terminals. These areas react to treatment with reserpine, nialamide-dopa and α-MMT in the same way and since the nuc. caudatus putamen and tuberculum olfactorium are known to have a high DA content it seems likely that abundant DA terminals are accumulated in these special areas.

Evidence for the existence of monoamine neurons in the central nervous system. 3. the monoamine nerve terminal.

Humans are unable to synthesise L-ascorbic acid (L-AA, ascorbate, vitamin C), and are thus entirely dependent upon dietary sources to meet needs. In both plant and animal metabolism, the biological functions of L-ascorbic acid are centred around the antioxidant properties of this molecule. Considerable evidence has been accruing in the last two decades of the importance of L-AA in protecting not only the plant from oxidative stress, but also mammals from various chronic diseases that have their origins in oxidative stress. Evidence suggests that the plasma levels of L-AA in large sections of the population are sub-optimal for the health protective effects of this vitamin. Until quite recently, little focus has been given to improving the L-AA content of plant foods, either in terms of the amounts present in commercial crop varieties, or in minimising losses prior to ingestion. Further, while L-AA biosynthesis in animals was elucidated in the 1960s, 1 it is only very recently that a distinct biosynthetic route for plants has been proposed. 2 The characterisation of this new pathway will undoubtedly provide the necessary focus and impetus to enable fundamental questions on plant L-AA metabolism to be resolved. This review focuses on the role of L-AA in metabolism and the latest studies regarding its bio- synthesis, tissue compartmentalisation, turnover and catabolism. These inter-relationships are considered in relation to the potential to improve the L-AA content of crops. Methodology for the reliable analysis of L-AA in plant foods is briefly reviewed. The concentrations found in common food sources and the effects of processing, or storage prior to consumption are discussed. Finally the factors that determine the bioavailability of L-AA and how it may be improved are considered, as well as the most important future research needs. # 2000 Society of Chemical Industry

Plant L‐ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

Large herbivores must select food from a wide variety of plant parts, species, and strains. These differ in nutritional value (protein, carbohydrate, etc.), toughness, spinosity, etc. Even greater differences are found in types and concentrations of secondary compounds. Every plant produces its own set of secondary chemical compounds, which to a great extent are unique to it or its species. Ingestion of natural concentrations of these compounds can lead to either death or severe physiological impairment. The ubiquitous nature of these compounds would make herbivory impossible unless animals had mechanisms for degrading and excreting them. An animal displaying no obvious symptoms of poisoning is not free of the problem of ridding itself of toxic compounds; if it is eating plants, it almost certainly has this problem. Herbivores are capable of detoxifying and eliminating secondary compounds. Limitations of these mechanisms force mammalian herbivores to consume a variety of plant foods at any one time, to treat new foods with caution, to ingest small amounts on the first encounter, and to sample food continuously. Selection of foods is based on learning in response to adverse internal physiological effects, and herbivores probably cannot predict these from the smell or taste of new foods. Herbivores prefer to eat familiar foods and can seek out and consume foods that rectify specific nutritional deficiencies induced by detoxification. They should prefer to feed on foods that contain small amounts of secondary compounds, and their body size and searching strategies should be adapted to optimize the number of types of foods available with respect to the total amount of food that can be eaten and will be present in the future. Natural selection can increase the efficiency of degrading particular secondary compounds. Specialist herbivores, like koala and mountain viscacha, are expected where a large amount of several related toxic foods is present in a year-round supply. However, few large herbivores are specialized on such a restricted range of foods.

Strategies in herbivory by mammals: the role of

Eine ergiebige Synthese der l-Ascorbinsäure (C-Vitamin)

A new crystalline compound has been isolated from beef adrenal extracts. In three different assay methods using epinephrectomised rats or dogs it was found to be from 30 to 100 times as potent as cortexone (11-deoxy-corticosterone) or its acetate.

Isolation from the adrenals of a new crystalline hormone with especially high effectiveness on mineral metabolism

https://science.sciencemag.org/content/sci/161/3844/861.full.pdf

Heart Poisons in the Monarch Butterfly

Catecholamines are readily converted into highly fluorescent products by treatment with formaldehyde gas, under the condition that the reaction takes place in a dry protein containing layer. The reaction, which has been found to be catalyzed by some amino-acids and peptides, has been studied by examination of the products formed especially from dopamine [β-(3,4-dihydroxyphenyl)-ethylamine] in serum albumin layers.

Fluoreszenzenzmethoden zur histochemischen Sichtbarmachung von Monoaminen. 2.. Identifizierung des fluoreszierenden Produktes aus Dopamin und Formaldehyd

Chemical degradation of the new crystalline mineralocorticoid provisionally called electrocortin has shown that this compound is 11β, 21-dihydroxy-3, 20-diketo-4-pregnen-18-al. In solution this reacts mainly as the 11-hemiacetal. We suggest aldosterone as a definitive name for the compound.

T. Reichstein

Papers

Eine ergiebige Synthese der l-Ascorbinsäure (C-Vitamin)

Isolation from the adrenals of a new crystalline hormone with especially high effectiveness on mineral metabolism

Heart Poisons in the Monarch Butterfly

Fluoreszenzenzmethoden zur histochemischen Sichtbarmachung von Monoaminen. 2.. Identifizierung des fluoreszierenden Produktes aus Dopamin und Formaldehyd

[Constitution of aldosterone, a new mineralocorticoid].