bluuebunny/crossref_metadata_2025 huggingface dataset:
A review of in situ spores in Silurian land plants
Authors: Fanning U , Richardson J B , Edwards D
Published: November 2023

Spores are described from the sporangia of six rhyniophytoid taxa from early Pridoli (late Silurian) strata at Perton Lane, Hereford and Worcester, England. Those from species of Cooksonia are crassitate: C. pertoni subsp. pertoni contains Ambitisporites sp.; C. pertoni subsp. synorispora, Synorisporites verruca/us; and C. cambrensis has a crassitate spore with microgranulate sculpture on both proximal and distal surfaces, which has not yet been recorded in dispersed spore assemblages and will probably require a new genus. Retusoid spores of diverse aspect have been isolated from Salopella sp. and two new taxa. The Salopella spores are exceptionally large and provisionally assigned to Retusotriletes sp., the genus also used for spores of Caia langii which has elongate spinous sporangia. Spores of Pertonella dactylethra (characterized by sporangia of Cooksonia shape, but with spines) have a distinctive sculpture following the curvaturae perfectae, and are close to Retusotriletes coronadus from the Silurian of Spain.
Tetrahedraletes, Nodospora, and the ‘cross’ tetrad: accretion of myth
Authors: Gray Jane
Published: November 2023

An important group of pre-Late Silurian land plants produced spores that first appear in the mid-Ordovician. This benchmark may mark their first adaptive radiation on land or merely the acquisition of a preservable structure.
Diversification of modern heterosporous pteridophytes
Authors: Collinson Margaret E
Published: November 2023

The fossil record of the heterosporous lycopsids (lsoetales and Selaginellales) and water ferns (Marsileales and Salviniales) is reviewed. Fertile whole plants and dispersed megaspores with attached microspores or microspore massulae are the crucial fossils for understanding the evolution, diversification, and phylogeny of these plants. Salviniales are particularly well represented with fertile fossil plants substantiating an extensive dispersed spore record. Azollaceae (Azolla) and Salviniaceae (Salvinia) are distinct, and the modern genera clearly identifiable, from the earliest Tertiary onwards. Azolla and extinct relatives are also known in the late Cretaceous. A mosaic of characters is presented by these late Cretaceous fossils most of which is lost during the early Tertiary. Marsileales are represented by one sporocarp species in the early Tertiary but otherwise only by a patchy record of dispersed spores from the early Cretaceous onwards. Isoetales and Selaginellales have a longer history.
Determining character polarities 1n pollen
Authors: Zavada M S
Published: November 2023

Four widely used methods for establishing the polarity of character transformations, namely the outgroup method, the parsimony method, the palaeontological method, and the ontogenetic method, are considered in relation to characters relevant to discussions of seed plant phylogeny. Special emphasis is given to discussions of ontogenetic data. Two basic patterns of development of the primexine into sexine are described, and it is suggested that in the ancestral condition for seed plants primexine deposition is immediately followed by deposition of protosporopollenin on sites corresponding to the future tectum, and then the infrastructural layer. Problems arising from the occurrence of preangiospermous dispersed fossil pollen that possesses features considered characteristic of angiosperms are discussed in detail.
Development of tapetum and orbicules of Catharanthus roseus (Apocynaceae)
Authors: El-Ghazaly G A , Nilsson S
Published: November 2023

The development of the tapetum and orbicules in Catharanthus roseus (L.) G. Don has been examined using transmission electron microscopy (TEM). Precursors of orbicules are formed as spheroidal vesicles within the tapetal cytoplasm and are associated with the endoplasmic reticulum. The pro-orbicules are extruded through the cell membrane of the tapetal cell and this coincides with the dissolution of the ta petal cell wall and the callosic wall of the microspores. The orbicules are developed by irregular deposition of sporopollenin on the pro-orbicules. A thin membranous layer is developed between the orbicules, forming the orbicular membrane. At free microspore stage globular bodies are seen in the cytoplasm of the tapetal cells. Some of these bodies are large and coated with a thin electron-dense layer, others are small bodies, electron-dense and gathered in groups. At vacuolate stage the tapetal cells extend into the anther locule, acting as a periplasmodial tapetum. At late vacuolate stage the tapetal cells retreat from the anther locule and possess an organized and apparently functional structure. The tapetal cells start to degenerate just before an thesis of the pollen grains. The diversity in the structure of orbicules and tapetum may suggest different functions at different stages of development and may have arisen by remarkable processes of adaptation.
Structural and functional variation 1n pollen intines
Authors: Heslop-Harrison J , Heslop-Harrison Y
Published: November 2023

The basic three-layered organization of the angiosperm intine is related primarily to its function during pollen hydration, activation, germination and early tube growth. Structural variation amongst families, genera, and species is attributable mainly to two circumstances: that the intine necessarily tends to conform with the architecture of the exine, and that the additional adaptations concerned with regulating the water economy of the grain and controlling germination rate are present in some groups.
Denitrification: the denitrifying bacteria and their interactions with plants
Authors: von Berg Karl-Heinz Linne , Vosswinkel Renate , Bothe Hermann
Published: November 2023

Plant physiologists are well aware that plants and many micro-organisms assimilate nitrate to meet their nitrogen requirements. Dissimilatory nitrate reduction, on the contrary, is only performed by prokaryotes and can clearly be differentiated from nitrate assimilation. The synthesis of the enzymes of nitrate assimilation, nitrate and nitrite reductases, is repressed by or organic nitrogen compounds and is unaffected by The expression of dissimilatory nitrate reduction is not dependent on or organic nitrogen but requires -exclusion or low -tensions. Some exceptional bacteria, such as Aquaspirillum magnetotacticum (Bazylinski and Blakemoore 1983) or Thiosphaera pantotropha (Robertson and Kuenen 1984) perform dissimilatory nitrate reduction even in air. These isolates are of particular interest, because they may be useful for the removal of nitrate in waste water treatment.
Plant-animal interactions on hard substrata in the north-east Atlantic
Authors: Hawkins S J , Hartnoll R G , Kain (Jones) J M , Norton T A
Published: November 2023

The composition of intertidal and subtidal communities within this area is briefly outlined with reference to the British Isles. A major feature is a general trend of decreasing plant dominance and greater numbers of grazers and filter feeders from shelter to wave-exposure in the eulittoral. This pattern changes from north to south, with animal-dominated communities extending further into shelter at more southerly locations. Similarly, southwards, dominance by kelp beds declines low on the shore and in the subtidal, and red algal turfs become more important and grazer diversity increases. The role of plant-animal interactions in energy flow within the mid-intertidal is discussed. Sheltered-shore fucoid beds are net exporters of energy, primarily to the detrital pathway. More exposed shores are net importers of energy, although most in situ microalgal production is consumed within the community. Shores of intermediate exposure are probably modest net exporters. Comparatively little macroalgal production passes through the grazing pathway. The way in which plant-animal interactions structure communities on the environmental gradients of wave-exposure and tidal height/depth in the British Isles is considered. Patella grazing prevents establishment of fucoids on more exposed shores. On moderately exposed shores, escapes offucoids from grazing help to generate patchiness. Within these patchy communities, a complex suite of both positive and negative interactions occurs between plants and animals. On the vertical gradient, grazing is a major structuring agency in the midshore region and just below the kelp canopy in the subtidal. The balance of the interactions is altered by latitude, and grazing becomes less effective further north.
Tropical east Atlantic and islands: plant-animal interactions on shores free of biotic reefs
Authors: John David M , Price, James H , Lawson George W
Published: November 2023

The western coast of Africa and offshore islands lying between the Tropics contrast with most other tropical regions in the absence of biotic reefs. There is, however, a remarkable biotic resemblance between rocky shores of similar wave-exposure and type within the region, despite its vast size. Animals and non-geniculate coralline algae invariably dominate wave-exposed shores, whilst foliose and other soft algae dominate those protected from wave-action provided that algivorous fish are present in low numbers. Molluscs are unquestionably important grazers on many shores, although little information exists other than the observation that removal of Siphonaria from the upper eulittoral leads to a lush growth of blue-green algae. Unexplored experimentally is the grazing of seaweeds and microalgae by the larger limpet Patella safiana, littorinids, other molluscan genera and amphipods. Some experimental evidence exists that sea urchin grazing and seasonal changes in the physical environment are responsible for the absence or patchiness of noncalcareous algae at lower levels on unprotected shores. Shore organisms are affected by the climatic seasons: the stormy, wetter period favours intertidal algae by reducing desiccation while adversely affecting subtidal algae by causing instability of cobble banks and increasing turbidity; the calmer drier period has the reverse effect, with conditions more severe for shore algae and favourable to those growing subtidally.
Ecological and physiological aspects of herbivory in benthic suspension-feeding molluscs
Authors: Bayne B L , Hawkins A J S
Published: November 2023

Benthic suspension-(or filter-) feeding bivalve molluscs such as mussels, oysters, and clams act as important agents of sedimentation in estuaries and coastal systems. Some investigations suggest that suspension-feeding may be a dominant factor controlling phytoplankton biomass, although hydrodynamic and other factors may act to limit the availability of particulate seston to the feeding currents of the bivalves. These animals may also affect nutrient regeneration, directly via nitrogenous excretion or indirectly via microbial mineralization of their bio deposits. Many filter-feeding bivalves are opportunistic feeders, relying on phyto-plankton, organic detritus and bacteria in proportions that vary with location and with season. We consider some key physiological aspects of these interactions and conclude that feeding behaviour is flexible in response to changes in food quantity and quality; rates of nitrogen excretion, although variable, may be modelled as a function of rates of nitrogen ingestion; and there are circumstances under which bivalves may be carbonrather than nitrogen-limited by the available food.
Endosymbiosis in marine cnidarians
Authors: Davies P Spencer
Published: November 2023

Endosymbiotic relationships with either prokaryote or algal symbionts are found in the marine benthos, in members of the Protozoa, Porifera, Cnidaria, Turbellaria, and Mollusca. This review will concentrate upon the most widespread association, that of the dinoflagellate Symbiodinium microadriaticum (zooxanthellae) and its anthozoan hosts. During the daytime, photosynthetically fixed carbon compounds, mainly glycerol and lipids, pass from the symbiont to the host tissue. The magnitude of this flux has now been quantified and related to the nutritional requirements of the host. Both carbon and energy budget studies indicate that in shallow water and on clear sunlit days, the total photosynthetic production exceeds the requirements of symbiont and host. The excess is excreted, mainly as mucus-lipid and is thereby available to the food chain. Zooxanthellae also play a role in the uptake of dissolved inorganic nitrogen and in the recycling of nitrogenous excretory products back to the host as amino acids.
The ‘cyclotron resonance’ hypothesis: experimental evidence and theoretical constraints
Authors: Liboff A R
Published: November 2023

The cyclotron resonance hypothesis (Liboff 1985) may be succinctly stated: many of the weak-field extremely low-frequency (ELF) magnetic interactions with cells that have been reported are either consistent with, or obey, the ion cyclotron resonance (CR) condition, suggesting an underlying electromagnetic interaction with cells that is rather different from current concepts. This hypothesis is strengthened in a circumstantial way when one realizes that the resonance frequencies for biologically important ions are all in the ELF range at geomagnetic field levels (Fig. 7.1). The CR hypothesis provides a tentative explanation (Liboff and McLeod 1988) for the so-called calcium-efflux experiments (Bawin et al. 1975; Blackman et al. 1982; Dutta et al. 1984). It has also served as the basis of a group of predicted experiments in a variety of model systems -timing behaviour in rats (Thomas et al. 1986; Liboff et al. 1989), diatom motility (McLeod et al. 1987; Smith et al. 1987), calcium incorporation in lymphocytes (Rozek et al. 1987), and growth rate of chick femur (Smith et al. 1988). In addition, Conti et al. (1986) have suggested that the CR hypothesis may explain the altered mitogenic response in lymphocytes that follows low-frequency magnetic field exposures.
9. Toxic range plants and their constituents
Authors: Molyneux Russell j.
Published: November 2023

As settlers moved westward across North America they encountered an environment which became increasingly hostile to both themselves and their livestock. It was an environment with which they were completely unfamiliar, far removed in character from the ‘European’ type of grazing lands typical of the Eastern seaboard. The climate was generally arid or semi-arid, with diverse plant communities, and while many of the plants provided excellent forage they were intermixed with other species which proved to be extremely toxic to livestock.
Plant Galls: A Perspective
Authors: Williams Michele A J
Published: November 2023

Galls have been of interest to man from historical times to the present day. Despite or because of this fact, the term ‘plant gall’ has been applied to many different systems. Definitions of the term arc mostly inadequate and its employment as a general expression rather than a term suggesting scientific precision is preferred. Manifestations which have been called plant galls are caused by a wide variety of organisms interacting with a broad range of hosts. These interactions in turn provide opportunities for complex assemblages of organisms. Cecidology, the study of plant galls, uses a diverse range of biological techniques and involves many disciplines, a representative selection of which are drawn upon to provide the material for this volume.
Interactions between Trichochermes walkeri (Homoptera: Psylloidea) and other Homoptera on Rhamnus catharticus
Authors: Mclean I F G
Published: November 2023

The psyllid Trichochermes walkeri Forster (Psylloidea: Triozidae) forms leaf roll galls on buckthom, Rhamnus catharticus L. As part of a long-term study of the population dynamics of T walkeri the interactions between this gall-forming insect and other, free-living, Homoptera associated with buckthom have been investigated. The free-living psyllids and aphids are associated with leaves galled by T walkeri to varying extents, ranging from obligate, through showing a preference for feeding on galled leaves, to showing no significant association. These different degrees of association can be related to the phenologies of the free-living species, while it is speculated that the nutritional advantage of feeding on galled leaves has been responsible for free-living Homoptcra becoming more closely associated with, and eventually dependent upon, the presence of T walkeri galls.
Galls and the evolution of social behaviour in aphids
Authors: Foster W A , Northcott P A
Published: November 2023

In several aphid species there is a soldier caste that actively defends the aphid colony. All the aphids that produce soldiers belong to species that induce galls on their host plants. Gall formation and soldier production arc restricted to two of the families within the Aphidoidea-the Hormaphididae and the Pemphigidac. Information about the behaviour of the species (approximately 30) in which soldiers have been described is summarized. The paper examines how living in a gall might affect the social organization of aphids and increase the likelihood of the production of soldiers and the evolution of cooperation. The argument is proposed that the gall is important in providing a resource that can be readily defended and kept clean. In addition, the gall is important in providing a ring-fence around the clones, increasing the likelihood that aphids are related to their close neighbours. Soldier production might be encouraged in those galls that arc relatively long lived.
The biogeography and population genetics of the invading gall wasp Andricus quercuscalicis (Hymenoptera: Cynipidae)
Authors: Sunnucks Paul , Stonet G N , Schonrogget K , Csokat G
Published: November 2023

Andricus quercuscalicis is one of a group of five European cynipid gall wasps which have a life cycle involving alternation of generations between English oak, Qyercus robur and Turkey oak, Q, cerris. The natural range of this species is limited to areas where the two oaks occur together, in Europe south of the Alps, Tatras, and Carpathians and east of the Carpathians in a small region of the Ukraine. While Q, robur is widespread and abundant in much of Europe north and west of these regions, Q, cerris is only found where it has been planted by man in parks and gardens. Although Q, cerris can self-seed in much of its new range, over the time scale involved (200-300 years) this species has probably yet to spread significantly away from introduction sites.
Phytochemistry of some plants used in traditional medicine for the treatment of protozoal Diseases
Authors: Phillipson J D , Wright1 C W , Kirby G C , Warhurst D C
Published: November 2023

There is a need to develop new antiprotozoal drugs which have novel structures and novel modes of action. Protozoa are responsible for several diseases which are of worldwide importance, including amoebiasis, giardiasis, leishmaniasis, malaria, and trypanosomiasis. It has been estimated that some 270 million people are infected with malaria and that approximately half of the world’s population is at risk because they either live in, or visit, areas where the disease is common (Laitman 1990). Three hundred and fifty million are at risk of contracting leishmaniasis, 90 million, Chagas’ disease (Trypanosoma cruzi infections), and 50 million, African sleeping sickness (T. bruce infections) each year (Laitman 1990). Intestinal protozoa including Entamoeba histolytica, the cause of amoebiasis, and Giardia intestinalis, the cause of giardiasis, are responsible for 42 million and 200 million infections annually, respectively (Guerrant 1986; Boreham 1991).
Molecular and biochemical analyses of plant Snfl-related protein kinases
Authors: Halfordl N G
Published: November 2023

The Snfl class of serine-threonine protein kinases are found in yeast, mammals, and plants, and share a common role in the regulation of certain key enzymes of carbon metabolism (Hardie et al. 1994). In yeast, Snflp phosphorylates and inactivates acetyl-CoA carboxylase (ACC) and glycogen synthase (GS) (Woods et al. 1994; Hardy et al. 1994). It is also an indispensable part of a signal transduction pathway required for the derepression of a number of genes involved in the utilization of alternative carbon sources in response to glucose deprivation (reviewed by Gancedo 1992). This pathway has not been entirely elucidated and the mechanism by which the signal is created in response to glucose levels is not known. It has been hypothesized that a weak protein kinase activity associated with hexokinase may be indicative of a role for this enzyme in the perception of glucose levels (Ma et al. 1989a,b; Rose et al. 1991). Alternatively, glucose flux through glycolysis rather than glucose levels per se may be the relevant parameter for triggering and reversing glucose repression (Ronne 1995). snfl mutants are unable to utilize a variety of carbon sources, including sucrose, fructose, maltose, and non-fermentable carbon sources such as ethanol and glycerol. They are also defective in sporulation and the heat-shock response (Johnston and Carlson 1992; Thompson-Jaeger et al. 1991).
Receptor-like protein kinases
Authors: Walker J C , Stone J , Collinge M , Horn M , Braun D , Smith R
Published: November 2023

Understanding the molecular and cellular mechanisms by which plant cells perceive and respond to their environment is still in its infancy. Much of the research over the past decade has focused on identifying components involved in transducing an extracellular signal into the cell. Two sets of recurring components thought to mediate signal transduction processes in all cells are protein kinases, which catalyse protein phosphorylation, and phosphoprotein phosphatases, which mediate dephosphorylation. Both the protein kinases and protein phosphatases are represented by widely diverse families of genes, each encoding enzymes with potentially unique physiological roles. Understanding the structures and functions of protein kinases and phosphoprotein phosphatases and how they interact with other signalling components promises to generate new insights into the mechanisms by which plants respond to their environment.
Molecular genetics of abscisic acid signal transduction: the involvement of a putative calcium-modulated protein phosphatase
Authors: Leung J , Giraudat J
Published: November 2023

Since its discovery as an acidic inhibitor of coleoptide growth in the late 1940s (Addicott 1983), abscisic acid (ABA) has emerged as an essential hormone (or growth substance) regulating seed development and dormancy, as well as adaptive responses of vegetative tissues to adverse environmental conditions. Although the major physiological roles of ABA are known to some extent, the molecular aspects of its action are still fragmentary and often contradictory. With the advent of Arabidopsis thaliana as a model species (Meyerowitz 1989), some of the more outstanding molecular issues of ABA signal transduction can now be addressed experimentally with the combined use of genetics and molecular biology. Because this chapter is not intended as an exhaustive account of the physiology and biochemistry of ABA, interested readers can find most of the necessary background in several books and recent reviews devoted entirely to this topic (Addicott 1983; Zeevaart and Creelman 1988; Davies and Jones 1991; Hetherington and Quatrano 1991; Giraudat et al. 1994). We outline below selective features of ABA action, first, to illustrate some of the existing information gaps between physiology and molecular biology, and second, to lay a minimum framework for the motivation behind our molecular approach to this complex problem. We then describe our recent results in cloning the AB/l locus of Arabidopsis, which encodes a protein with structural features of a calcium-modulated phosphatase (Leung et al. 1994; Meyer et al. 1994). Finally, we present some testable hypotheses on how this putative phosphatase may participate in certain physiological aspects of ABA signal transduction.
A survey of active vision invertebrates
Authors: Land Michael F , Collett Thomas S
Published: November 2023

Our intention in this review is to try to put together a checklist of the situations in which active vision occurs in invertebrate animals, with the idea of providing colleagues from disciplines other than zoology with a feeling for ‘what is on offer’ amongst the visual systems of animals evolutionarily remote from man. Vision has originated in the invertebrates many times, and as a result many different solutions have been tried out as each group gets to grips with the opportunities offered by the visual modality. There should thus be plenty, in this rich array of pre-tested solutions to problems, that maybeof value to those trying to design artificial seeing systems.
Insect inspired behaviours for the autonomous control of mobile robots
Authors: Weber K , Venkatesh S , Srinivasan M V
Published: November 2023

If autonomous robots are to navigate successfully in unfamiliar environments, they must be able to perceive their environment in an autonomous fashion. For short-range course control, it is vital that obstacles in the path be detected and avoided in a cost-effective (real-time) way. It may also be very desirable to be able to detect and avoid or track other moving objects in the environment.
Cytoplasmic sex-ratio distorters
Authors: Hurst Gregory D D , Hurst Laurence D , Majerus Micheal E N
Published: November 2023

As previously discussed in this book, cytoplasmic factors in animals, be they organellar, bacterial, or otherwise, tend to be inherited exclusively from the mother. One consequence of this is that cytoplasmic factors will typically have zero fitness when in a male. Hence, a cytoplasmic factor that can either force an increase in the proportion of females in its ‘host’s’ brood, or can otherwise increase the survival and reproductive success of infected female hosts, will spread. To put it another way, Fisher’s (1930) prediction of a stable 1 : 1 sex ratio is an analysis of the evolutionary interests of autosomes which does not hold either for sex chromosomes (Hamilton 1967) or for cytoplasmic elements (Hamilton 1979; Cosmides and Tooby 1981). Cytoplasmic genes will be selected to produce a female-bias to the sex ratio. Examples of cytoplasmic sex-ratio distorters have already been discussed in this book, most notably the agents that induce parthenogenesis in a variety of wasps (Chapter 4) and those that are responsible for feminization in crustaceans (Chapter 3). This chapter examines the remaining incidences. For the most part this means vertically transmitted agents that kill males. However, we start with brief consideration of the (limited) evidence for the existence of other classes of cytoplasmic sex-ratio distorters. Discussion of the population genetics and biology of all of these systems is followed by a body of speculation as to the potential impact of these factors on host evolution.
The functional ecology of small fish: some opportunities and consequences
Authors: Miller P J
Published: November 2023

The ecology of small teleosts ( < 100 mm) is discussed in terms of the essential whole organism functions (feeding, surviving, growing, and reproducing). Small size makes available new habitat opportunities for teleosts, ranging from nektonic to cryptobenthic and differing along several ecotopic dimensions. The advantages and disadvantages of small size for teleosts are discussed with reference to whole-organism functions, involving both intrinsic size-related factors and directions of selection within habitat. Appropriate responses in life-history patterns relating to survival and reproduction emphasize the significance of contrasting mortality patterns over potential lifespan in producing extremes of reproductive allocation. Compensation for size-related constraints on offspring size (bestowal) and fecundity is discussed with reference to repeat spawning and the occurrence of viviparity, especially the role of superfoetation in combining frequency of reproduction with high bestowal. Functional interactions of small fish with mankind can be adverse or beneficial, with human interest in aquaria providing a new niche for at least some small fishes.
Ecology of very small terrestrial mammals
Authors: Churchfield Sara
Published: November 2023

Miniaturism among terrestrial mammals is a rare phenomenon, with only 8% of all species being < 15 g in body mass and < 100 mm in body length. It is confined to just three orders (Marsupialia, Insectivora, and Rodentia) and is the major preserve of four families (Dasyuridae, Tenrecidae, Soricidae, and Muridae). The smallest representatives have body masses of 1.5-3.0 g. Most species have a tropical and subtropical distribution, and numbers of species (and their mean body mass) decline with increasing latitude. The predominant feeding modes are insectivory and granivory. Most miniature mammals occur in forest and grassland/steppe habitats and are mainly ground-surface foragers. Very small mammals have lower absolute food requirements than do larger counterparts, and miniature insectivores subsist on small arthropods with low biomass but high abundance. This permits them to inhabit less productive areas at higher latitudes and altitudes compared with larger congeners which rely on richer habitats supporting larger prey such as earthworms. The occurrence of insectivorous shrews, but not miniature granivorous rodents, in Arctic regions probably reflects greater availability of small arthropods than of seeds in winter. Exceedingly small mammals have low population densities and there is evidence of reduced population numbers, body size, and niche breadth when they are sympatric with larger congeners. But differences in body size and niche occupancy help to reduce overlap and competition in communities of similar species. Very small species tend to be more specialized with narrower niches, and have lower levels of overlap, than larger congeners.
Options for the genetic manipulation of astringent and antinutritional metabolites in fruit and vegetables
Authors: Robbins Mark P , Bavage Adrian D , Morris Phillip
Published: November 2023

Fruit and vegetables produce an array of secondary metabolites that are derived from primary metabolic pathways. Such secondary compounds can have a profound effect on the value of individual fruit and vegetable varieties. For example, anthocyanins, carotenoids and chalcones contribute to fruit colour; whereas other secondary compounds such as glucosinolates and volatile phenolics play an important part in flavour characteristics.
Gibberellins and fruit development
Authors: García-Martínez José L , Hedden Peter
Published: November 2023

Fruit development is dependent on the action of each of the five major classes of plant hormones. Gibberellins (GAs) play a major role in this process, inducing fruit-set and the expansion of the pericarp, and, as a consequence, they have important practical applications in fruit production. For example, GA is applied to seedless grapes in order to obtain the required size and shape of the berry (Martín, 1983) and to seedless cultivars of mandarin to enhance fruit set (Monselise, 1979). However, despite the importance ofGAs in fruit development and the large body of physiological, analytical and biochemical data on this subject, fundamental questions about the source of the active GAs and their mode of action in fruit have yet to be answered unequivocally. The significance of the available information is discussed in this review, which is restricted to fleshy fruit; monocotyledoneous plants are not considered.
Toxic compounds from fruit and vegetables
Authors: D’mello J P Felix
Published: November 2023

It is possible to adopt a very wide interpretation of this title, based on conventional meanings of the terms ‘fruit’ and ‘vegetables’. The Oxford dictionary defines fruit as ‘the edible product of a plant or tree, consisting of the seed and its envelope’. The definition for vegetables includes plants ‘cultivated for food’, particularly edible herbs or roots. If one also applies a broad definition for the phrase ‘toxic compounds’, then it is immediately apparent that we would be considering an almost infinite array of deleterious substances in the context of a wide variety of plant products. The constraints of space do not allow such an approach. This chapter therefore focuses on a limited number of toxic constituents in selected fruits and vegetables. In fruits, the adverse effects of allergens, hypoglycin and patulin are considered. In vegetables, the existence of a wider range of toxicants is well recognized, including lectins, isoflavones, glucosinolates, S-methylcysteine sulfoxide, glycoalkaloids, nitrate, oxalates and furanocoumarins. The deleterious effects of these compounds are reviewed, and the risks for human health considered. In many cases the assessment and management of risk necessitates reference to animal studies, particularly where the underlying basis for toxicity is of relevance. The toxicology of these compounds is addressed in a global context in order to illustrate the diversity of these substances. This review excludes issues arising from contamination of fruit and vegetables with pesticide residues.
Continental drift
Authors: Hallam A
Published: November 2023

Unlike the controversies outlined so far, that concerning continental drift has been confined essentially to this century, although the idea that the continents might have moved laterally with respect to each other had been proposed earlier.
Fisheries
Authors: Coulter G W
Published: November 2023

To understand the rather complicated pattern of fishing activities on Lake Tanganyika and the likely direction of future fishery development, it is necessary to view these from the perspectives of the social and physical environments of the local fishermen. Fishery development cannot be viewed entirely in technical terms, or higher fish yields equated simply with improved methods and supply of materials. Ultimately, human priorities and the exigencies imposed by local circumstances regulate fishing activities and schemes for change.
Design of Brushless Permanent-Magnet Motors
Authors: Hendershot J R , Miller TJE
Published: November 2023

Brushless permanent-magnet motors provide simple, low maintenance, easily controlled motive power. New magnetic materials and digital power control techniques continue to widen the scope of their applications. Increasing automation is increasing demand. This book, written by two world leading experts, combines practical and academic experience to produce the most comprehensive and useful design manual for brushless PM motors ever. It will serve the modern computer-based generation of motor engineers in much the same way as the Electro-Craft Handbook served the previous generation on d.c. motors. The book goes hand-in-hand with modern software-based techniques for design and analysis. It covers all the topics of interest to the motor design engineer, and the system engineer, including electrical and magnetic design, materials, control, and many other topics.
Cosmological models
Authors: d’Invemo Ray
Published: November 2023

There are a number of ways of proceeding. The equation can be solved, in general, by using elliptic functions, or resort can be made to computer plots of numerically generated solutions. However, many of the sub-cases can be integrated directly using elementary functions or, failing that, elementary functions can be used to investigate their qualitative features. We shall not give an exhaustive account of this approach here (but see Landsberg and Evans (1977) for details).
Matrices
Authors: Barnett Stephen
Published: November 2023

Techniques of matrix theory find wide application throughout engineering and the physical, life, and social sciences. Consequently, matrix methods comprise an important component in any ‘tool kit’ of applied mathematics. This wide-ranging textbook provides a clearly written and up-to-date account of these methods, suitable for both undergraduates and more advanced students. The aim is to provide a down-to-earth approach with results illustrated by many examples drawn from the areas of application. The range of topics covered is large: from basic matrix algebra to advanced concepts such as generalized inverses and Hadamard matrices, and applications to error-correcting codes, control theory, and linear programming. In addition, the book contains numerous exercises, together with answers, making it ideal for students in any field where matrices are used.
Controllability
Authors: Hocking Leslie M
Published: November 2023

In this chapter we discuss the general question of the controllability of deterministic systems, mainly for linear systems, though some of the results are also true for nonlinear ones.
Time-optimal control
Authors: Hocking Leslie M
Published: November 2023

This chapter contains the heart of Part A. We shall prove the existence of a time-optimal control and find how it can be determined. We shall consider the problem of the uniqueness of the optimal solution. A tightrope walker seeks to maintain an upright position; any deviation from the vertical will result in a catastrophic fall unless it is controlled, and the acrobat’s objective is to regain the (unstable) equilibrium position as quickly as possible.
Linear state equations with quadratic costs
Authors: Hocking Leslie M
Published: November 2023

The combination of quadratic cost functions and linear state equations provides an important class of problems for which the application of the PMP leads to a set of linear equations. We have met particular examples of this kind already, but here we try to find general solutions. We deal first with the simplest case, before considering n-dimensional problems.
Error-Correcting Codes and Finite Fields
Authors: Pretzel Oliver
Published: November 2023

This book provides the reader with all the tools necessary to implement modern error-processing schemes. It assumes only a basic knowledge of linear algebra and develops the mathematical theory in parallel with the codes. Central to the text are worked examples which motivate and explain the theory. The book is in four parts. The first introduces the basic ideas of coding theory. The second and third parts cover the theory of finite fields and give a detailed treatment of BCH and Reed-Solomon codes. These parts are linked by their use of Euclid's algorithm as a central technique. The fourth part is devoted to Goppa codes, both classical and geometric, concluding with the Skorobogatov-Vladut error processor. A special feature of this part is a simplified (but rigorous) treatment of the geometry of curves.
The theory of compact surfaces
Authors: Hemion Geoffrey
Published: November 2023

We have seen that the basic plan for classifying knots involves splitting 3-dimensional manifolds along surfaces. Therefore it is a sensible idea to review quickly the classification theory of surfaces, as it was formulated about 70 years ago. The problem of classifying surfaces is incomparably simpler than the problem of classifying Haken 3-manifolds. To begin with then, we must ask ourselves the question, what is a surface? The answer: it is a compact 2-dimensional manifold. Such surfaces can always be triangulated; that is they can be represented as finite collections of solid, 2-dimensional triangles, which are glued together along their edges.
Piecewise linear topology
Authors: Hemion Geoffrey
Published: November 2023

In this chapter a few of the methods which are developed in the theory of piecewise linear topology will be summarized. The conscientious reader might be well advised to consult one of the standard books on the subject. But broadly speaking, the idea is the following. In an ‘ideal world’ the subject of topology reduces to a process of examining elastic objects which can be stretched and deformed as we like. According to the rules of the game, scissors are not allowed.
Three-dimensional structure of Ras and Ras-related proteins
Authors: Wittinghofer Alfred , Valencia Alfonso
Published: November 2023

The structures of several different wild-type and mutantp21 complexes have been determined by two groups. A listof the published structures is shown in Table 1 togetherwith the resolutions obtained in the crystallographic analyses.For wild-type and one oncogenic mutant both thetriphosphate and diphosphate structures have been determined.For the triphosphate complex of p21 the non-cleavableanalogues GppNHp and Gpp(CH2)p were used,because GTP and even GTPy.i are hydrolysed by p21 duringcrystallization.
The mammalian two-dimensional gel map of small GTP-binding proteins
Authors: Huber Lukas A
Published: November 2023

Full length cDNAs of small GTP-binding proteins wereinserted into PGEM1 under the control of the T7 promoteras described previously (Chavrier et al. 1990; Huber et al.1993). GTP-binding proteins were then transientlyexpressed in BHK 21 cells with the T7 RNA polymeraserecombinantvaccinia virus system (Fuerst et al. 1986;Chavrier et al. 1990; Huber et al. 1993, 1994b). Cells werescraped and fractionated 5 hours after infection/transfectionand membrane fractions applied to high resolution2D-gel electrophoresis.
Ram2p
Authors: Tamanoi Fuyuhiko
Published: November 2023

Its nucleotide sequence and the amino acid sequence of the gene product are shown in Fig. 1. The GenBank accession number is M88584.ProteinRAM2 encodes a protein of 316 amino acid residues. The Ram2 protein shares a significant sequence similarity with the a-subunit of rat farnesyltransferase (they are 30% identical in the COOH-terminal 211 residues) (Chen et al. 1991). The Ram2 protein also shares sequence similarity with the BET4 gene product (Li et al. 1994), which appears to function as the a-subunit of protein geranylgeranyltransferase II of yeast (Armstrong et al. 1993). Internal repeats have been identified within the Ram2 protein (Boguski et al. 1992). This repeat, which contains an invariant tryptophan and a number of other well-conserved residues, is also found in the BET4 protein as well as in the a-subunits of mammalian protein farnesyltransferases.
Dpr1/Ram1p
Authors: Tamanoi Fuyuhiko
Published: November 2023

The DPR1/RAM1 gene was cloned as a gene complementingthe temperature-sensitive growth property of dpr1 orram1 mutation (Goodman eta/. 1988; Powers eta/. 1986).The gene was also cloned using complementation of sgp2phenotypes (Nakayama et al. 1988). The sequence of thegene was determined by Goodman et al (1988) and isshown in Fig. 1. GenBank accession number is M22753. Thegene is transcribed to give rise to an mRNA of approximately1.6 kb (Tamanoi et al. 1988).
Vav
Authors: Altman Amnon , Gulbins Erich
Published: November 2023

vavwas identified as a transforming oncogene during gene transfer studies that involved transfection of murine NIH 3T3 fibroblasts with DNA from several human esophageal carcinomas and tumorigenicity assays in athymic nude mice (Katzav etal. 1989). Analysis of human genomic sequences from the murine tumors identified a DNA fragment that hybridized specifically to a 3.0 kb mRNA present in these murine tumors. This fragment was subsequently used as a probe to clone vavfrom a XgtIOcDNA library derived from a third cycle nude mouse tumor. Analysis of the longest cDNA clone (2.8 kb) and subsequent cDNA cloning of the complete human and murine cDNA sequences of proto-vav (Katzav eta/. 1989,1991, Coppola eta/. 1991),
Ral-GDS
Authors: Giddings Barton W
Published: November 2023

ral-GDS was identified by performing polymerase chain reaction (PCR) with degenerate oligonucleotides corresponding to regions conserved between the Saccharomyces cerevisiae gene CDC25 and the Schizosaccharomyces pombe gene ste6 (Albright et al. 1993). Two clones, raIGDSa and raIGDSb, were identified; these clones appear to be alternatively spliced products of the same gene. The DNA sequence of mouse ral-GDSa is shown in Fig. 1. GenBank accession numbers are L07924 (mouse ral-GDSa) and L07925 (rat ral-GDSb).
P120-GAP
Authors: McCormick Frank
Published: November 2023

Bovine p120-GAP was purified from brain, and cloned from a brain cDNA library (Vogel et al. 1988). The protein encoded by this cDNA is 1023 amino acids in length. Human p120-GAP was cloned from placenta, and exists in two forms, as a result of an alternative splice (Trahey et al. 1988).
Rsk
Authors: Chen Rey-Huei
Published: November 2023

Two Xenopus rsk cDNAs were first isolated from a Xenopus ovary library (GenBank accession number J03775) (Jones et al. 1988). The two cDNAs show 91% sequence identity to each other. The larger clone αis 3071 nucleotides long, and the other βis 2991 nucleotides long. These sequences reveal no significant similarities with other known genes. One chicken and two mouse homologs of the Xenopus laevis cDNAs have also been isolated by low stringency hybridization using Xenopus rsk-a clone as the probe (Alcorta etal. 1989).
Cdc25p
Authors: Powers Scott
Published: November 2023

The Cdc25 gene was cloned from yeast DNA expression libraries by complementation of the temperature-sensitive growth of cdc25 mutants (Camonis etal. 1986; Broek etal. 1987; Robinson etal. 1987). The original cdc25 mutant was isolated in a screen for temperature-sensitive cell cycle mutantsand is allelic to cyr2 (reviewed in Matsumoto etal. 1985). The GenBank accession number is M15458.
Sdc25p
Authors: Boy-Marcotte Emmanuelle , Jacquet Michel
Published: November 2023

This gene was originally cloned as a truncated gene by its ability to suppress the thermosensitivity of a cdc25-5 strain (Boy-Marcotte et al. 1989). It was named SCD25 for suppressor of cdc25 but, for the sake of non-redundant yeast nomenclature the name was changed to SDC25 (Damak etal. 1991). The SDC25 gene has been located on the left arm of chromosome XII at 5.5 cM from the centromere. The complete gene encodes a polypeptide of 1253 amino acids. When first cloned from the OL136 yeast strain, the 5’ part contained a deletion, derived from this strain, inactivating the gene (Damak et al. 1991). New constructions on multicopy plasmid with the wild-type gene suppress the cdc25 mutation (unpublished observations). Since truncated constructs are also able to suppress cdc25 mutations irrespective of their orientation, they are supposed to contain internal promoter elements. GenBank accession number: M26647.
Msi2p/Ltelp
Authors: Shirayama Masaki , Matsui Yasushi , Toh-e Akio , Tanaka Kazuma
Published: November 2023

MSI2 was isolated by screening a yeast genomic library based on YEp24for a suppressor of heat shock sensitivity of iral-1 (Shirayama et al. 1994). The nucleotide sequence of the MSI2 gene indicated that it includes the sequence of the previously reported LTE1 gene (Wickner et a/.1987). The DNA sequence of MSI2/LTE1 is shown in Fig. 1. The EMBL/GenBank/DDBJ accession number for MSI2 is D21354.
Rab3b
Authors: Kikuchi Akira , Takai Yoshimi
Published: November 2023

Bovine Rab3b cDNA was isolated from a bovine brain cDNA library using oligonucleotide probes of Rab3a (Matsui etal. 1988). Human Rab3b cDNA was isolated from a human pheochromocytoma cDNA library by use of human Rab3a cDNA as a probe (Zahraoui et al. 1989). The nucleotide sequence of bovine Rab3b and its deduced amino acid sequence are shown in Fig. 1. The GenBank accession numbers are: bovine Rab3b, J03943; human Rab3b, J03000.
Rabl3
Authors: Elferink Lisa A , Schellers Richard H
Published: November 2023

Rab13 was one of seven cDNAs identified by screening a rat brain cDNA library using two cDNAs (Ora-1 and Ora-2) from the marine ray Discopyge ommata, which encode GTPases with significant homology to the yeast Sec4 protein (Elferink et al. 1992; Ngsee et al. 1991). The nucleotide and corresponding deduced amino acid sequences are presented in Fig. 1. The GenBank/EMBL Data Bank accession number is M83678 for rat Rab13 and X75593 for human Rab13.
Rabl4
Authors: Elferink Lisa A , Schellers Richard H
Published: November 2023

The cDNA encoding Rab14 was originally isolated from a rat brain cDNA library, during a screen for Sec4-related GTPases (Elferink etal. 1992). The nucleotide and deduced amino acid sequence for Rab14 is shown in Fig. 1. GenBank accession number M83680.