bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflex effects on the cardiovascular system: role of changes in respiration
Authors: Daly M de Burgh
Published: November 2023

In the spontaneously breathing animal, selective stimulation of the carotid bodies causes hyperventilation but often has variable effects on heart rate and systemic vascular resistance. The evidence indicates that the variable cardiovascular responses are due, at least in part, to mechanisms initiated by this hyperventilation and that when these are controlled, bradycardia and vasoconstriction in most vascular beds invariably occur. These latter responses have been designated the primary cardiac and vascular responses of carotid body stimulation. Hyperventilation modulates these responses through various mechanisms and may completely override them, although there are species differences in the extent to which this occurs. Stimulation of the aortic bodies also causes hyperventilation but the size of the response is much smaller than that resulting from the same excitatory stimulus applied to the carotid bodies.
Carotid bodies: ‘primary’ cardiovascular responses
Authors: Daly M de Burgh
Published: November 2023

Under experimental conditions in which respiration is maintained constant, stimulation of the carotid bodies elicits a number of primary reflex cardiovascular responses. These include a bradycardia, largely of vagal origin, an increase in total peripheral vascular resistance due to a predominance of vasoconstriction, a constriction of most capacitance vessels, and an increased secretion of suprarenal catecholamines. Changes in resistance in the various vascular beds are described in detail. Evidence is presented that there are differential reflex responses in various parts of the sympathetic outflow on stimulation of the carotid bodies.
Aortic bodies: ‘primary’ cardiovascular responses
Authors: Daly M de Burgh
Published: November 2023

Stimulation of the aortic bodies causes bradycardia or tachycardia, an increase in left ventricular dP/dt max, hypertension, an increase in total systemic vascular resistance, vasoconstriction in the limbs and abdominal circulation, and a reduction in capacitance in the abdominal circulation. However, some variable results have been reported. This is due partly to the species variations in the distribution of the thoracic chemoreceptor tissue and partly to the use of several different chemical agents to excite the chemoreceptors. Many of these experimental agents are not selective in their action and have other effects such as on autonomic ganglia. Secondary effects of changes in blood pressure have not always been adequately controlled. Some advantages are gained by the technique of vascularly isolating the aortic arch and its major intrathoracic branches and perfusing the region with blood under controlled conditions incorporating left-, and sometimes right-, heart bypass. This enables a natural stimulus, hypoxic blood, to be used.
Primary reflex effects on the pulmonary and bronchial circulations
Authors: Daly M de Burgh
Published: November 2023

Evidence is presented that under rigidly controlled experimental conditions, stimulation of the carotid chemoreceptors causes an increase in pulmonary vascular resistance due to constriction of the pulmonary vessels. The efferent pathway is via the sympathetic supply to the lungs. Studies of the nervous control of the pulmonary vessels are complicated by the need to control a number of variables which can affect pulmonary vascular resistance passively. These are reviewed in detail with special reference to the bronchial circulation, changes in which, through anastomotic channels between the bronchial and pulmonary vascular systems, can result in passive changes in pulmonary vascular resistance. The bronchial vascular system is also under reflex control from the carotid bodies, their excitation causing vasodilatation, probably through activation of vagal efferent fibres.
Clinical implications of chemoreceptor reflexes
Authors: Daly M de Burgh
Published: November 2023

The possible involvement of peripheral arterial chemoreceptor reflexes in various clinical conditions is discussed. Any condition of asphyxia which involves excitation of the carotid bodies and which is accompanied by depression of breathing or apnoea, evoked centrally or reflexly, will enhance the chemoreceptor bradycardia and possibly put the patient’s life at risk. The paradox of this situation is that intense carotid body excitation in the presence of a powerful inhibitory input to the inspiratory neurones, while causing bradycardia or even cardiac arrest, will not usually restart breathing. Such conditions include attempts at prolonging the period of underwater swimming by prior voluntary hyperventilation, various sleep hypopnoea-apnoea syndromes, sudden infant death syndrome, and inhalation of irritant gases or vapours.
Major events in cephalopod evolution
Authors: Engeser T S
Published: November 2023

Previous classifications of the major groups of cephalopods are based mainly on features of the shell and the siphuncle and are phenotypic. In a new approach, the classification is reinvestigated by means of cladistic analysis. The Cephalopoda are a monophyletic group of molluscs. Despite obvious differences between, for example, Nautilus and the Coleoidea, there are some unique synapomorphies that are exclusively shared by these two distinct evolutionary lines. The latest common ancestor of the cephalopods will be considered.
Evolutionary radiations In the Trilobita
Authors: Fortey R A , Owens R M
Published: November 2023

Radiations have been understood in several ways; the trilobites have a good fossil record which can be used to examine these different usages. Supposed radiations in the sense of accelerated cladogenesis (especially involving higher taxa) are discussed at two important times: the basal Cambrian radiation; and the basal Ordovician radiation at the inception of the ‘Palaeozoic evolutionary fauna’. At the Precambrian-Cambrian boundary a cladistic analysis of trilobite relationships shows that the fossil record inadequately represents the early history of the Trilobita, both with regard to the relationships of the group to other arthropods, and with regard to early vicariant or migration events resulting in fauna) provinces.
Sporogenesis 1n simple land plants
Authors: Brown R C , Lemmon B E
Published: November 2023

Quadripartitioning of the sporocyte into a tetrad of spores during meiosis is one of the most distinct examples of precise geometrical division in the plant kingdom. The cytoskeleton is of fundamental importance in the establishment and maintenance of quadripolarity. The microtubule systems associated with establishment of polarity in sporocytes are quite different from those in mitosis of vegetative tissue where the future division plane is marked by a component of the cytoskeleton known as the preprophase band of microtubules (PPB). PP Bs do not occur in meiocytes. Instead, quadripolarity in simple land plants is marked in a variety of ways. Cytoplasmic lobing of the spore mother cells ofbryophytes dramatically predicts future cytokinetic planes. Quadripolarity is most elegantly marked in monoplastidic meiosis of mosses, hornworts, and the vascular cryptogams Isoetes and Selaginella by plastid polarity manifested in plastid migration and the development of a unique quadripolar microtubule system (QM S). The QM S, which develops in meiotic prophase, contributes to predictive quadripositioning of plastids and participates directly in spindle ontogeny.
Plant-animal trophic relationships In the Posidonia oceanica ecosystem of the Mediterranean Sea: a review
Authors: Mazzella L , Buia M C , Gambi M C , Lorenti M , Russo G F , Scipione, M B , Zupo V
Published: November 2023

In the Mediterranean Sea, beds of the endemic phanerogam Posidonia oceanica, characterized by both high subsurface and high photosynthetic biomass, form one of the most productive systems of the basin. The biomass values can exceed those of other phanerogams and the plant shows distinct partitioning, often mainly directed into the lignified rhizomes, which can account for up to 90 per cent of total biomass. Leafborne algal flora can at times contribute up to 30 per cent of overall production. Part of the energy produced by the plant is exported to adjacent systems through leaf detritus, but the major part is stored by the plant and recycled within the system. Because of some intrinsic features of P. oceanica living tissue few direct herbivores, apparently relatively unselective or generalist feeders (such as echinoids, isopods or the fish Sarpa salpa), have been found. Yet ‘herbivores’ and ‘herbivores-deposit feeders’ constitute the dominant feeding categories among the animal communities of the leaf stratum.
Mesoherbivores
Authors: Brawley Susan H
Published: November 2023

Arthropod mesoherbivores affect the species composition and stability of marine communities. Many mesograzers attain densities of thousands of animals m-2, but their nocturnal activity has hindered recognition of their abundance and importance. The difference between the potential and realized diets of mesoherbivores is discussed in the context of factors (e.g., predation, short life-spans) that may limit overgrazing of macroalgae.
Evidence that hypolocomotion induced by peripheral or central injection of CCK in the mouse is mediated by peripherally located CCKA receptors
Authors: O’Neill Michael F , Dourish Colin T
Published: November 2023

CCK reduces locomotor activity in rodents when given peripherally or centrally (Crawley et al. 1981; Van Ree et al. 1983). The receptor mechanism by which CCK exerts its influence on activity and the anatomical location of these receptors is as yet unclear. Initially, two subtypes of receptor were proposed on the basis of differential affinities of CCK fragments for binding to membranes from brain and peripheral tissues. Subsequent studies by Moran et al. (1986) showed that both peripheral type (CCKA) and brain type (CCKB) CCK receptors were present in brain tissue.
Satiation in humans induced by the dipeptide L-aspartyl-L-phenylalanine methyl ester (aspartame): possible involvement of CCK
Authors: Rogers Peter J , Blundell John E
Published: November 2023

In a series of studies we have used intense sweeteners, such as saccharin, aspartame, and acesulfame-K, as experimental tools to separate the influences of sweetness and caloric dilution on appetite control (e.g. Rogers and Blundell, 1989b). However, in addition to their sweet taste, there is the possibility that at least some of these substances may have biologically significant postingestive effects (Rogers and Blundell 1989a). This was confirmed by studies which showed that oral administration of capsulated aspartame suppresses food intake in humans (Rogers et al. 1990). Since the aspartame was ingested without being tasted, the effect must be due to post-ingestive action. Moreover, this anorexic effect of aspartame is both robust and potent. We have replicated the result in six separate experiments to date in which, for example, 200 mg of aspartame produced an acute 10-15 per cent reduction in food intake (Rogers et al. 1990 and unpublished data).
Immunohistochemical and in situ hybridization studies of the coexistence of CCK and dopamine in mesencephalic neurons
Authors: Hökfelt T , Schalling M , Seroogy K , Frey P , Walsh J , Goldstein M
Published: November 2023

CCK was originally isolated by Mutt and Jorpes (1968) from porcine intestine. Vanderhaeghen et al. (1975) described CCK/gastrin-like material in the rat brain, and it was then shown to represent mainly the C-terminal octapeptide (CCK-8) (Dockray 1976, 1980; Muller et al. 1977; Dockray et al. 1978; Rehfeld 1978a, b; Beinfeld et al. 1980). In fact, in several brain regions CCK-8 is the most abundant neuropeptide (Crawley 1985). In addition to these radioimmunoassay studies, numerous immunohistochemical investigations showing extensive CCK immunoreactive neuron systems in the brain and spinal cord have been published (Innis et al. 1979; Larsson and Rehfeld 1979; Lorén et al. 1979; Vanderhaeghenetal. 1980, 1982; Kiyamaetal. 1983; Kubota et al. 1983; Fuji et al. 1985; Hökfelt et al. 1985, 1988; Vanderhaeghen 1985). More recently, in situ hybridization with radio-labelled probes complementary to CCK messenger RNA (mRNA) has been employed and not only confirmed most results from immunohistochemical studies but also provided interesting new findings (Siegel and Young 1985; Burgunder and Young 1988, 1990; Savasta et al. 1988, 1989; Voigt and Uhl 1988; Ingram et al. 1989; Lanaud et al. 1989; Seroogy et al. 1989b, 1990; Cortés et al. 1991a, b; Jayaraman et al. 1990; Sutin and Jakobowitz 1990).
Involvement of central dopamine and CCKA receptors in the apomorphine-induced hypotensive response in the anaesthetized rat
Authors: Sturman Gillian
Published: November 2023

Apomorphine has been shown to relieve parkinsonian rigidity in humans, and this is thought to be due to direct stimulation of dopamine receptors in the basal ganglia (Anden et al. 1967). After intravenous (i.v.) administration of apomorphine, there is a transient fall in blood pressure. Whether this effect is due to the involvement of the central or peripheral dopamine receptors is under debate (Finch and Haeusler 1973; Mugabo et al. 1983). Hökfelt et al. (1980) have reported that dopaminergic neurons in the mid-brain contain CCK. This peptide has been shown to facilitate dopamine-induced hyperlocomotion and apomorphine-induced stereotypy in the rat (Crawley et al. 1984), suggesting that it increases the neuronal responsiveness to dopamine agonists. With the development of devazepide, a highly potent CCKA receptor antagonist (Chapter 2 of this volume), and L-365,260, a selective CCK8 receptor antagonist (Lotti and Chang 1989; Chapter 2 of this volume), the possible involvement of CCK and its receptors in the apomorphine-induced hypotensive response in the anaesthetized rat can be investigated.Male Wistar rats (250-350 g) anaesthetized with urethane (1.0-1.25 g/kg i.p,) were used in the tests. The systemic blood pressure was measured via a cannulated carotid or femoral artery using a Bell & Howell physiological pressure transducer and a Lectromed two-channel pen recorder. All su,bstances used were dissolved in isotonic saline, in volumes not greater than’ l ml/kg, and injected into either a jugular or a femoral vein at a rate of 0.1 ml/s, with a subsequent 0.1 ml saline injection. Apomorphine (10-30 nmol/kg), sulphated CCK octapeptide (CCK-8S) (0.5-5 nmol/kg), and dopamine (0.1-30 µmol/kg) produced immediate dose-dependent alterations in blood pressure. After establishing standard dose-response curves in each rat, the antagonists were injected intravenously (i.v.) at least 10 min before apomorphine, CCK, and dopamine administration was repeated. Each antagonist was tested in a minimum of 10 rats. In some anaesthetized rats, bilateral vagotomy or pithing was performed instead of antagonist administration.
Opioid control of CCK release from the rat spinal cord-interaction between µ, o, and K receptors
Authors: Benoliel J J , Bourgoin S , Mauborgne A , Hamon M , Cesselin F
Published: November 2023

Numerous data in the literature suggest that CCK interacts with opioids in pain mechanisms. Thus large doses of CCK have been shown to induce a naloxonereversible analgesia, whereas small doses of this peptide can prevent the antinociceptive action of opioids (Chapters 43 and 44 of this volume). The latter pharmacological observation is in line with a hypothetical opioid antagonist property of CCK under physiological conditions. Indeed, the blockade of CCK receptors by proglumide or selective CCKA and CCKB antagonists results in a marked enhancement in morphine- or β-endorphin-induced analgesia (Chapters 43 and 44 of this volume). Furthermore, tolerance to the analgesic effect of morphine is markedly delayed when CCK receptors are blocked, which suggests that chronic stimulation of opioid receptors by morphine may trigger a progressive compensatory increase in the activity of CCK-containing neurons in the CNS (Baber et al. 1989; Dourish et al. 1990; Chapters 43 and 44 of this volume).
In vivo release of CCK-8 from the dorsal horn of the rat: modulation by selective opioid agonists
Authors: Rodriguez Raquel E
Published: November 2023

The octapeptide form of CCK (CCK-8) predominates in the CNS of mammalian species, including man Beinfeld 1983). Many of the physiological roles of CCK-8 in the CNS are unknown, and the physiological actions attributed to this peptide are as diverse as its distribution. CCK-8 shows an excitatory action in the gastro-intestinal tract, and it is a potent activator of digestion, pancreatic secretion, and gall bladder contraction. In the CNS, the physiological actions attributed to CCK-8 include regulation of satiation, modulation of catecolaminergic activity, and regulation of hypothalamic peptides. A variety of effects have been observed after central administration of CCK-8. These include hypothermia (Katsuura et al. 1981), hyperglycemia (Morley and Levine 1980), and sometimes analgesia (Pittaway et al. 1987). Also, electrophysiological data have shown both excitatory and inhibitory actions of CCK-8 in the CNS (Salt and Hill 1982 There is supporting evidence that CCK-8 may interact with opioid systems. CCK-8 increases respiration physiologically (Gillis et al. 1983), whereas a wellknown side-effect of morphine is respiratory depression. Probably the most important point is that many of the CCK-8-containing loci are areas observed to contain high concentrations of endogenous opioids, many of which are implicated in pain modulation (Baber et al. 1989). Also, the distributions of enkephalins and CCK are very similar, and a functional relationship may exist between them. It should be noted, however, that sulphated CCK-8 does not bind to opioid receptors in the brain (Stengaard-Pedersen et al. 1981). In antinociceptive tests CCK has been shown to block opioid analgesia, whereas CCK antagonists produce the opposite effect (Baber et al. 1989; Chapters 43 and 44 of this volume
Seeking a role for CCK in control of spinal reflexes
Authors: Clarke Robert W , Harris John , Ford Timothy W
Published: November 2023

Endogenous opioid peptides are inhibitory modulators of spinal reflex function. Work from many laboratories, including our own, has demonstrated that opioid antagonists such as naloxone increase reflex responses in dog (McClane and Martin 1967), cat (Goldfarb and Hu 1975; Bell and Martin 1977; Duggan et al. 1984), man (Boureau et al. 1978), and rabbit (Catley et al. 1983; Clarke and Ford 1987; Clarke et al. 1989a). These findings indicate that there is a tonic release of opioid peptides in the spinal cord which results in suppression of reflex responses. Further, intense electrical stimulation of the high threshold afferents of peripheral nerves has been shown to evoke prolonged (15-40 min) naloxone-reversible inhibition of reflexes in cat (Chung et al. 1983) and rabbit (Catley et al. 1984; Clarke et al. 1989b), suggesting that intense afferent barrage augments activity in spinal opioidergic neurons.
Blockade of CCKB receptors by L-365,260 induces analgesia in the squirrel monkey
Authors: O’ Michael F , Spencer Tye Neill , Dourish Colin T
Published: November 2023

CCK receptors are found in high concentrations in the CNS in areas that are associated with nociception such as the dorsal horn of the spinal cord and periaqueductal grey (PAG) (Baber et al. 1989). Two subtypes of CCK receptor have been identified, CCKA and CCKB, which have greater preponderance in alimentary and brain tissues respectively (Moran et al. 1986). Recently a series of non-peptide CCK antagonists have been described which differ in their relative affinities for these subtypes of CCK receptor. L-365,031 and devazepide (Chang and Lotti 1986; Evans et al. 1986) have nanomolar affinity for CCKA receptors, whereas L-365,260 has nanomolar affinity for CCKB receptors (Bock et al. 1989; Lotti and Chang 1989). Thus the functional roles of CCKA and CCKB receptor subtypes in mediating the effects of CCK can be studied.
Exploiting behaviourally active phytochemicals in crop protection
Authors: Pickett John A , Wadhams lester J , Woodcock christine M
Published: November 2023

Rapid and efficient destruction of invertebrate pests can be achieved by using synthetic pesticides that selectively disrupt the nervous system. Alternatives to these agents are urgently sought, partly because of real problems such as pesticide resistance but also because of misconceptions concerning the toxicity and synthetic nature of the compounds involved. Although some early organochlorine compounds persisted to an un acceptable extent in the environment and accumulated in predators at the top of the food chain, these have now been replaced by the much less persistent organophosphorus, carbamate, and pyrethroid insecticides. Certainly, with the pyrethroids, the likelihood of environmental pollution or human hazard is extremely slight when correctly used in agriculture. None the less, non-target invertebrates can be at risk, and, much more importantly, there are serious problems of control failure through the selection of populations of pests resistant to these agents.
The lichen thallus: a symbiotic phenotype of nutritionally specialized fungi and its response to gall producers
Authors: Hawksworth* David L , Honegger† Rosmarie
Published: November 2023

The view that lichen thalli should be regarded as analagous to insect and fungal galls produced on plants is critically analysed. Ten similarities and 13 differences are recognized and discussed. In view of the fundamental differences identified, the analogy cannot be upheld. Lichen thalli are regarded as a particular biological phenomenon with no exact analogue. An expanded definition of ‘lichen’ is provided. Coevolutionary and systematic aspects of the lichen mutualism are considered, stressing the need to emphasize non-coevolved structures in supraspecific taxonomies. Attention is also drawn to the galls produced on established lichen thalli by invasive fungi and other organisms, including nematodes and arthropods.
A breadfruit amongst the dipterocarps: galls and atavism
Authors: Jenkins R M , Mabberley D J
Published: November 2023

For nearly three centuries the spinose gall of the Indian tree, Hopea ponga (Dennst.) Mabberley (Dipterocarpaceae) was mistaken for a fruit, especially one of a species of Artocarpus Forster & Forster f. (Moraceae). The history of the taxonomic confusion is related and the significance of the superficial resemblance of the gall to a fruit is discussed. Fieldwork in Malabar has led to an understanding of the development and ecology of the gall and these are considered in relation to the life cycle of the cecidozoan, an undescribed species in the Beesonia-Gallacoccus complex (Homoptera: Coccoidea).
Parasitoids as a driving force in the evolution of the gall size of Urophora on Cardueae hosts
Authors: Zwölfer H , Arnold-Rinehart F
Published: November 2023

In the tephritid genus Urophora, gall forming evolved from non-galling ancestors whose larvae mined within the achenes and receptables of Asteraceae flower heads. In the Palearctic Urophora species an evolutionary trend to increase the proportion of lignified gall tissue can be recognized. This includes the transition from unilocular to multilocular galls. The structure and size of Urophora galls influences larval survival and parasitization rates by a complex of parasitoids with a distinct guild structure and an ancient and stable association with Urophora hosts. The available evidence leads to the conclusion that parasitoid pressure was one of the driving forces in the evolution of Urophora galls.
Strategy in the search for new biologically active plant constituents
Authors: Hostettmann K , Marston A , Wolfender J L
Published: November 2023

The plant kingdom represents an extraordinary reservoir of novel molecules. Of the estimated 250,000-500,000 plant species around the globe, only a small percentage has been investigated phytochemically and the fraction subjected to biological or pharmacological screening is even lower. Since plants may contain hundreds or even thousands of metabolites, there is currently a resurgence of interest in the vegetable kingdom as a possible source of new lead compounds for introduction into therapeutical screening programmes. The rapid disappearance of tropical forests and other important areas of vegetation has meant that it is essential to have access to methods which lead to the rapid isolation and identification of bioactive natural products.
Acetogenins from Annonaceae
Authors: Cave A
Published: November 2023

Acetogenins from Annonaceae are a series of C-35/C-37 natural products of polyketide origin derived from fatty acids. Their structure is characterized by a long alkyl chain bearing a terminal unsaturated methyl y-lactone (sometimes rearranged to a propanone y-lactone), one or two tetrahydrofuran rings, several oxygenated substituents (hydroxyl, acetoxyl, ketone), and in some cases a double bond and/or epoxy group (Fig. 10.1). To date, they have been isolated only from the Annonaceae.Annonaceous acetogenins exhibit a broad range of potent biological activities, especially antitumoural, cytotoxic, antiparasitic, and pesticidal properties.
Bioactive compounds from plants and higher fungi of Ethiopia
Authors: Dagne E , Abate D
Published: November 2023

The application of plants for medicinal purposes has been known to man since time immemorial. In Africa, as in many parts of the world, medicinal plants still play a pivotal role in treating the ill. It is estimated that the tropical African flora comprises over 30, 000 plant species grouped into about 2500 genera and distinguished by a high degree of endemism (Brenan 1978). Ethiopia, with its diverse topography including great mountain ranges, has a rich endemic element in its flora. Approximately 7000 higher plant species are known to occur in Ethiopia (Hepper 1979).
Panamanian flora: source of bioactive compounds
Authors: Gupta M P
Published: November 2023

The isthmus of Panama joins North and South America and contains a mixture of the biota in these two parts of the continent. This geographical position and its typical tropical climate have given rise to great biological diversity. For example, the flora of Panama is one of the 25 richest in the world: it has been estimated that there are between 8000 and 10000 vascular species in Panama, of which 17.3 per cent are endemic. There are also large numbers of non-vascular species, but these have not been fully investigated. Tables 16.1 and 16.2 give general information about the Panamanian flora.
Partitioning of photosynthetic carbon: the role of nitrate activation of protein kinases
Authors: Foyer C H , Champigny M L , Aladier M -H V , Ferrarii S
Published: November 2023

Sucrose is the main product of photosynthesis in crop plants, but photosynthesis is also required for primary nitrogen (N) assimilation in leaves. The reductive assimilation of N0-to the level of glutamine (Gin) and glutamate (Glu) must be coordinated with photosynthesis, since the energy required for the assimilation process is derived from photosynthetic electron flow, and the carbon (C) skeletons needed for amino acid synthesis are provided by photosynthetic CO assimilation. In addition, it is evident that complex molecular strategies are employed to regulate the partitioning of photosynthetic C between sucrose and amino acid synthesis. Over large distances, for example between the shoots and roots, cycling of N and C compounds allows information on the C and N status to be conveyed from one tissue to another. This is used to modulate N-absorption in the roots to match the demand for N. In the leaf cytoplasm, a multifactorial network of regulatory processes is employed to modulate the relative fluxes of assimilated C through the two metabolic pathways. The levels of sucrose and amino acids in the foliar cytosol act as endogenous regulators at the molecular and metabolic levels. Sucrose-phosphate synthase (SPS), nitrate reductase (NR), and phosphoenolpyruvate carboxylase (PEPCase) are considered to be the gateways to the assimilatory pathways of sucrose synthesis and N assimilation and the anaplerotic pathway respectively. These cytosolic enzymes are modulated in response to the addition of N to the plants and their activities vary with the rate of photosynthesis. The regulation of PEPCase and NR gene expression by N is well characterized as is the regulation of NR gene expression by sucrose (Cheng et al. 1986; Galangau et al. 1988; Sugiharto and Sugiyama 1992). In addition, all these enzymes are subject to covalent modulation via protein phosphorylation (S.C. Huber et al. 1994). NR and SPS, for example, are inactivated rapidly by phosphorylation in response to changes in irradiance or CO2 supply.
Molecular and biochemical properties of calmodulin-like domain protein kinases
Authors: Harmon A C , Yoo B -C , Lee J -Y , Zhang Y , Roberts D M
Published: November 2023

Diverse stimuli such as growth regulators, stress, pathogen attack, and red light elicit responses by affecting changes in intracellular free calcium concentration in plants. How a single second messenger, Ca+,is involved in bringing about different responses is under current investigation. While the complete answer is not yet known, it is clear that there are many high affinity calcium-binding proteins in plants that differ in function and these proteins are likely to contribute to the specificity of responses. There are several isoforms of calmodulin and of the calmodulin-like domain protein kinase (CDPK), as well as other proteins that are predicted to be calcium-binding proteins. Differences in the Ca+ sensitivity, location, and target proteins with which each interacts would confer specificity as far as which types of calcium signals may be sensed, and which response pathways are turned on.
Plant protein phosphorylation in signal transduction and the control of development: cloning and characterization of protein kinase genes from Arabidopsis and Petunia
Authors: Tregear J W , Decroocq-Ferrant V , Thomas M , Bianchi M W , Le Guen L , Lessard P , Lecharny A , Kreis M
Published: November 2023

Although studies on signal transduction in plants have traditionally lagged behind those on animal and fungal systems, it is becoming increasingly clear that many basic signalling components are conserved between all three groups of organisms. Information previously obtained from other eukaryotic systems has provided a means to study related mechanisms in plants, thus providing the first glimpses of how plant cells respond to both internal and external signals. During evolution, signal transduction components appear to have been conserved not only as individual entities, but also in groups in the form of signal transduction ‘modules’. Our interest in studying the mechanisms controlling development and metabolism in higher plants has led us to look in Arabidopsis thaliana and Petunia hybrida for homologues of protein kinases which might form part of these evolutionarily conserved modules.
Visual motion processing for figure/ground segregation, collision avoidance, and optic flow analysis in the pigeon
Authors: Frost Barrie J , Sun Hongjin
Published: November 2023

In a very rich diversity of species, spanning essentially the entire animal kingdom, one finds great similarities in the fundamental mechanisms that have evolved to process vision. For example we find that vertebrates and invertebrates alike have very circumscribed areas of their visual field specialized for higher acuity or other functions, which result in single or multiple foveae, visual streaks, and even bi- or multifocal optical systems.
Small size in amphibians-its ecological and evolutionary implications
Authors: Clarke B T
Published: November 2023

An overview of the ecological and evolutionary implications of reduced body size in amphibians is presented. Three significant formative influences in the evolution of the modern lissamphibian morphotypes-the limbless, worm-like caecilians, the tailed tetra podurodeles, and the squat, tailless anurans-are outlined. These influences are the shift from an aquatic to a terrestrial lifestyle, the development of concealment and water conservation strategies leading to fossoriality, and a reduction in body size. The last of these ultimately leads to the evolution of extremely small adult body size and is examined in greater detail. Miniaturization may occur sporadically in distantly related forms or in more closely related species, within a monophyletic lineage. Two kinds of miniaturization are identified-primary andsecondary. Primary miniaturization involves some form of radical morphological reorganization. Secondary miniaturization produces morphologically simi lar forms differing mainly in size. A systematic survey of small and miniature amphibians is presented and comment is provided on the morphological consequences of size reduction for each of the three amphibian orders. The ecological, behavioural, and evolutionary advantages of reduced body size to small and miniature amphibians are discussed. The need for further data, particularly accurate ecological and behavioural observational work, is noted.
Carotenoids and colour in fruit and vegetables
Authors: Britton George , Hornero-Méndez Dámaso
Published: November 2023

Carotenoids and anthocyanins are the most important pigments for providing attractive colours in fruit and vegetables. In contrast to the water-soluble anthocyanins, the carotenoids are water-insoluble, isoprenoid lipid molecules, and are usually located in membrane structures in discrete organelles, namely chloroplasts (in green tissues) or chromoplasts (in yellow, orange or red tissues). Carotenoids may be found in, and may provide or contribute to the colour of, all parts of plants: roots, leaves, flowers, fruit and seeds.
Phenolic compounds and oxidative mechanisms in fruit and vegetables
Authors: Amiot Marie J , Fleuriet Annie , Cheynier Veronique , Nicolas Jacques
Published: November 2023

Phenolic compounds form one of the main classes of secondary metabolites with a large range of structures (Table 4.1; Fig. 4.1), and contribute to the organoleptic and nutritional qualities of fruit and vegetables (Macheixet al.,1990). Oxidative mechanisms involving phenolic compounds may modify the quality of fresh or processed fruit and vegetables. Enzymatic browning is one of the main oxidative phenomena inducing the development of undesirable colour, flavour and a loss of nutrients. In heat-processed fruit and vegetables products, non-enzymatic browning (Maillard reaction) can also occur. In some cases, such as in plums, figs or dates, enzymatic browning is required for quality.
Aroma biochemistry of fruits and vegetables
Authors: Sanz Carlos , Olias Jose M , Perez Ana G
Published: November 2023

Aroma compounds contribute heavily to the overall sensory quality of fruit and vegetables. Aroma is a complex mixture of a large number of volatile compounds whose composition is specific to species and often to variety. In some cases the typical fruit and vegetable aromas can be ascribed to a specific compound, although in general the overall aroma quality is the sum of a multitude of compounds. At present, it is difficult to ascertain the relative contribution of each volatile component to a characteristic or a desirable aroma. During the last three decades, physicochemical methods of analysis, such as spectrophotometry, nuclear magnetic resonance, and specially gasliquid chromatography coupled to mass spectrometry allowed the isolation and identification of a large number of volatile compounds from plant aromas. However, rather less work has been done on elucidating the aroma formation mechanisms. These valuable studies are only a beginning to the process of understanding and regulating the aroma quality of fruits and vegetables. In this sense, biotechnological applications for aroma-determining substances in the food industry may support studies leading to a deeper knowledge of aroma biochemistry, since chemical synthesis cannot completely fulfil the requirements of specific chirality found among some aroma impact compounds, or the increasing demand for natural compounds by consumers.
Potentially anticarcinogenic secondary metabolites from fruit and vegetables
Authors: Hertog Michaël G L , Van Poppel Geert , Verhoeven Dorette
Published: November 2023

Cancer embraces a group of diseases which have in common that a cell or a group of cells is altered in such a way that it escapes growth control and replicates, thus prohibiting a normal functioning of the organ in which these cells are located. There is overwhelming evidence from experimental and epidemiological studies that most common forms of human cancers are related to environmental life-style factors such as diet, in combination with genetic factors that influence the susceptibility of individuals to these factors (Doll and Peto, 1981; Steinmetz and Potter, 1991a; Marshall, 1991). A large number of epidemiologic studies have shown that the consumption of vegetables and fruit is inversely associated with risk of cancer, particularly cancers of the alimentary and respiratory tract (Blocket al.,1992). Vegetables and fruit contain a large number of components that could, by a variety of mechanisms, explain these cancer-protective effects. Until recently, most attention has been paid to vitamins such as vitamin C, pro-vitamin A, and dietary fibre in these foods but in recent years it has been shown that these plant tissues contain a whole variety of potentially anticarcinogenic secondary metabolites. These include, amongst others, flavonoids, phenolic acids, terpenes, glucosinolates, and carotenoids (Table 16.1). The term ‘secondary metabolite’ refers to compounds that are not essential to the survival of the whole plant or certain parts of the plant.
The Biological Basis Of Human Patterns Of Mating And Marriage
Authors: Reynolds Vernon
Published: November 2023

Mating and marriage are very different kinds of things. Mating is a kind of behaviour, and is found in all animal species. Marriage is a social institution and, like other such institutions, is found only in human society.

I shall begin by discussing mating rather than marriage, and this will be mainly in the context of non-human primates rather than humans. Secondly, I shall look at human mating patterns in relation to the structure of the human body, and critically assess some scenarios of the original condition of man. Thirdly, I shall look at human marriage patterns and the phenomenon of marriage itself in relation to mating. Fourthly, I shall attempt some reconciliation between the principles of systems of marriage and systems of mating, and try to see whether marriage itself is comprehensible in biological terms. Finally, I shall look at the question of how and why marriage came into existence at all, and try to draw some conclusions.
The pelagic ecosystem
Authors: Hecky R E
Published: November 2023

The structure and function of Lake Tanganyika’s pelagic ecosystem has great relevance to aquatic sciences in general as well as its own intrinsic significance to the human economy of the lake and its environs. The pelagic ecosystem accounts for most of the production of organic carbon in the lake (Hecky & Fee, 1981), and the pelagic fishery, when fully developed, will account for most of the fish yield (Chapt. 7). The most intensively exploited areas yield higher catches per unit area than any other great lake, with a carbon transfer efficiency from primary production to fish production as high as the most efficient marine fisheries (Hecky et al.,1981). Although other great lakes are as large, none of them have Tanganyika’s unique hydrography which accentuates the importance of the pelagic system. Because of its great size, great age, and long water and elemental residence times, the lake occupies an intermediate position on the time and space scales which extend from small lakes to the worlds oceans.
The benthic fish community
Authors: Coulter G W
Published: November 2023

There is a remarkable benthic fish community in deep water in Lake Tanganyika that is rich in endemic species and genetically diverse. Its lower limit is determined by oxygen concentration, some species ranging down to about 200 m depth at the south of the lake where the oxygenated layer is deepest. There is also a group living above the bottom that may more properly be termed bathypelagic. Many of these species occupy wide ranges of depths. Some remain all their lives in deep water while others make diurnal or periodic migrations inshore. They occupy environments much different from those of the littoral or pelagic communities, and should be regarded as an ecologically distinct category.
Steady-State and Transient Operation Of Synchronous Machines and Synchronous Motor Drives
Authors: Vas Peter
Published: November 2023

In the normal configuration, a three-phase synchronous machine has a symmetrical three-phase winding on its stator, which is sometimes also referred to as the armature winding, and it is similar to the stator winding of a three-phase induction machine. Its rotor can be either cylindrical or it can have salient poles, as shown in Fig. 2.25. As discussed in Section 2.7.6.2, on the rotor their is a field winding which is excited by d.c., and it is connected to the external d.c. source via slip rings and brushes. Sometimes there are no brushes, but there is brushless excitation by (rotating) diodes. Further-more, sometimes there are also damper windings on the rotor, the roles of which have been described in Section 2.7.6.2. Steam turbine driven synchronous machines (turbogenerators) run at high speeds (they have 2–4 poles) and are equipped with cylindrical rotors, since this construction is mechanically more reliable (it withstands the centrifugal forces at high speeds) than a salient-pole construction. However, water-driven generators (hydrogenerators) and also smaller independent generators (for example, used in emergency power supplies), run at relatively low speeds (a few hundred revolutions per minute) and they are constructed with salient poles (since this requires a larger number of poles; see eqn (4.1-1)). It should be noted that it is possible to construct a three-phase synchronous machine where the d.c. excitation winding is on the stator and the three-phase winding, supplied by a.c. is on the rotor, (inverted machine). However, this would require an increased number of slip rings and the currents through the slip rings would be large. It is an advantage of the application of the wound-rotor machine that the excitation flux can be varied to operate the synchronous machine with any desired value of power factor, which can be lagging, unity, or leading.
Motor And Controller Types
Authors: Hendershot J R , Miller TJE
Published: November 2023

There are several different configurations of brushless motors which use rotating permanent magnets and stationary phase coils. The main reason for so many different variations has to do with the utilization of different magnet grades in addition to the wide range of applications. For example, if an application requires rapid acceleration and deceleration of the load (as in servo systems) then the torque/inertia ratio should be as high as possible. This indicates the use of an interior-rotor motor with high-energy magnets.
Control Systems Performance
Authors: Gray G
Published: November 2023

Brushless permanent-magnet motors have a linear torque/current characteristic, low torque ripple, and fast response. This makes them highly suitable for controlling speed, position or torque, either in a single-quadrant variable control mode, or as four-quadrant servomotors with reverse speed capability and dynamic braking. This chapter describes the brushless permanent-magnet motor and its controller as a control system. It includes a review of the simplified mathematical models that describe the motor and controller, followed by the main types of control system. Control system design is described in relation to closed-loop operation, frequency response, step response, stability, steady-state error, root loci, lead/lag compensation, pole placement, and robustness. The design and tuning of PID controllers is discussed in both linear (analog) and digital forms. Z-transform methods are described for discrete digital systems. The chapter concludes with a review of modern control methods including adaptive control, optimal control, and observers.
Basic algebra of matrices
Authors: Barnett Stephen
Published: November 2023

The first step in the development of matrix algebra is to denote an array by a single letter-almost invariably an upper case (‘capital’) letter is used, for example In some books bold type, A, is used for matrices. The numbers in the array are called the elements of A. The standard notation for elements is to use the same letter but lower case, and with two suffices which describe the position of an element.
Unique solution of linear equations
Authors: Barnett Stephen
Published: November 2023

In this chapter we shall study the solution of n simultaneous linear equations inn unknowns x1, x2,…xn in the form It is tempting to try to extend the ideas of matrix algebra developed in Chapter 2 so as to include ‘division’. We could then solve (3.2) by writing x = b + A, or borrowing the notation from ordinary algebra, If we could find the matrix denoted by A–1, in (3.4), then this would give the desired solution vector x. However, it turns out that the best way to proceed is the reverse: we solve the equations, and then use this solution to find the matrix A-1• The second part of this procedure will be delayed until Chapter 4.
Introduction
Authors: Kockler Norbert
Published: November 2023

Numerical mathematicians develop algorithms for these computational solutions. These algorithms are normally implemented on computers. The most reliable implementations are mainly to be found in the large software libraries mentioned in the preface. That is why students of mathematics, science, engineering and computer science should learn something about software libraries as part of their mathematical education.
Simultaneous Linear Equations
Authors: Kockler Norbert
Published: November 2023

Most application problems in numerical mathematics result in linear systems. There are many methods for their numerical solution. The decision which one to choose depends mainly on the structure of the coefficient matrix: Nonsingular matrix with no special structure: Gaussian elimination.
Nonlinear Equations
Authors: Kockler Norbert
Published: November 2023

The determination of roots of a given function is one of the classical mathematical problems. In most applications this problem is part of a larger one. Often it is a multi-dimensional problem. This means that we have to solve a system of nonlinear equations. Normally it is not possible to find analytical solutions. Therefore we need reliable numerical methods.
An Introduction To Sampling Theory
Authors: Higgins J R
Published: November 2023

Series of this kind and their generalizations and extensions form the subject matter of this book.On the theoretical side, sampling theory methods interact with fields such as interpolation a.nd approximation, special functions and the expansion of special functions in series, expansions associated with eigenvalue problems, constructive function theory, entire functions and the Paley-Wiener theory, numerical analysis and harmonic analysis.
Background In Fourier Analysis
Authors: Higgins J R
Published: November 2023

In this chapter we shall review those parts of cl888ical Fourier analysis that will be needed. This material is collected here for convenience, and since it is extremely well known and available in any good book on the subject, no proofs will be given except in the section on Poisson’s summation formula where a slightly more expanded discussion is given. The classical texts of Butzer and Nessel (1971), Titchmarsh (1948) and, for higher-dimensional Fourier analysis, Stein and Weiss (1971) are excellent source books. For an exposition of the fundamental ideas of Fourier analysis, and a broad range of applications, the book of Dym and McKean (1975) is highly recommended.