bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Isochromanquinones
Authors: Winters M P , Stranberg M , Moore, H W
Published: November 2023

Discussion Points What is the the mechanism of the bromination steps involved in the synthesis of compound 2? Suggest a structure for the unstable intermediate 6. Suggest a reaction mechanism for the thermal rearrangement of cyclobutenone 8 into the isochromanhydroquinone 9. Further Reading For a recent study of squarate ester reactivity see: L.A. Paquette and T. Morwick, J. Am. Chem. Soc., 1995, 117, 1451. For a review, in German, of the reactions of squaric acid and its derivatives see: A. H. Schmidt, Synthesis,1980, 961. For a recent application of this rearrangement to 4-allenylcyclobutanones see: M. Taing and H. W. Moore, J. Org. Chem.,1996, 61,329.
Total Synthesis of (+)-Longifolene
Authors: Lei B , Fallis, A G
Published: November 2023

Discussion Points Explain the selectivity obtained in step f and give reasons for the use of cadmium chloride in the condensation reaction. Which one of the cyclopentadienyl regioisomers 6 a-c leads to compound 7? Propose structures for the other possible Diels-Alder adducts. Further Reading For a review on the use of microwave heating, see: G. Bond, R. B. Moyes and D. A. Whan, Cat. Today,1993, 17,427. For a study of the influence of tether length on intramolecular Diels-Alder reactions, see: J. R. Stille and R. H. Grubbs, J. Org. Chem.,1989, 54,434.
Synthesis of the AB Ring Moiety of Ciguatoxin
Authors: Oguri H , Hishiyama S , Oishi T , Hirama, M
Published: November 2023

Discussion Points During the sequence d-e a new chiral centre is introduced. Which one of the steps is responsible for the stereoselectivity observed? In step j the selective protection of one hydroxyl group is accomplished. Suggest a reason for this selectivity. Give reasons for the stereoselectivity observed in the Yamamoto cyclisation of step q. Explain the regioselectivity of the DBU mediated elimination of step u. The compound obtained from Dess-Martin oxidation w proved to be unstable and had to be used without purification. Suggest a structure for the more stable compound formed on storage of 9. Which analytical technique could be used to determine the absolute configuration of 11 a, b?
Approach Towards the Asteriscanolide Skeleton
Authors: Booker-Milburn K I , Cowell, J K
Published: November 2023

Discussion Points What is the mechanism of the photolysis step c? What dictates the relative stereochemistry of the product 4? Propose a mechanism for the rearrangement sequence leading to the epimeric cyclooctanones 8 and 9. An attempt at oxidising the carboxylic acid 4 under the conditions reported in step e resulted in the formation of lactone 10. Rationalise the formation of this product bearing in mind the mechanism of this kind of oxidation.
Total Synthesis of (-)-Suaveoline
Authors: Fu X , Cook J M J
Published: November 2023

Discussion Points What is the mechanism of step d? Which of the products 6,7 and 8 is formally derived from a magnesium-ene reaction? Suggest a reason why it was necessary to protect the aldehydes 7 and 8 before the oxidative demolition steps m and n. When methanol was used as the solvent for debenzylation step p, compound 11 was isolated. Give an explanation for its formation.
Total Synthesis of (–)-Cephalotaxine
Authors: Isono N , Mori, M
Published: November 2023

Discussion Points Give an explanation for the diastereoselectivity observed in the formation of compound 2. A small amount of compound 14 is formed in step I. Explain the formation of this product.
Synthesis of (20S)-Camptothecin
Authors: Curran D P , Ko S -B , Josien, H
Published: November 2023

Discussion Points Explain the regioselectivity observed in the reaction sequence a to d and give reasons for the fact that it is possible to use a nucleophilic base such as n-BuLi in step c. What is the mechanism of the reductive etherification step e? Suggest structures for the intermediates formed in the radical cascade reaction of 8 with phenyl isonitrile.
Enantioselective Total Synthesis of (–)-Strychnine
Authors: Knight S D , Overman L E , Pairaudeau, G
Published: November 2023

Discussion Points Suggest a structure for compound 7. Give a method for the preparation of starting material 1 or its enantiomer. Explain the diastereoselectivity in the reduction of 2 to 3. What is the mechanism for the elimination step d? What is the mechanism for step q? What is the purpose of sodium methoxide in step u?
Properties of odorous molecules
Authors: Gardner Julian W , Bartlett Philip N
Published: November 2023

The odours that we perceive in the world around us arise through the interaction of molecules, given off by the odorous material, with sensory cells located in our nose. When we sniff a rose, for example, we are drawing up into our nose volatile molecules given off by the rose. The smell of the rose is the result of the interaction of these molecules with our sensory cells and our interpretation of the nerve impulses generated by this interaction. Typically, the odour of a flower or of a foodstuff or some other natural material will comprise a large and complex mixture of molecules of different types present in the mixture at different concentrations. On the other hand, in some cases a single, pure compound comprising molecules of just one type can be the dominant odour.
Energy and biomass consumption patterns in India
Authors: Ravindranath N H , Hall D O
Published: November 2023

The main focus of this book is to explore the potential and feasibility of bioenergy options in meeting the energy needs of a developing country such as India and to draw some lessons from this for other such countries. The first step in such an exercise is to understand the current energy scene, particularly that of biomass energy. Detailed information is required on the sources and end uses of biomass fuel, sustainability of its supply, features of use such as efficiency and socio-economic aspects, and production and conservation potential. Unfortunately, the data available on biomass energy are very poor compared to commercial energy data in most countries. Among developing countries, India was a pioneer in rural energy studies in the aftermath of the first oil crisis, with detailed micro-level (Ravindranath et al. 1981; Reddy 1982) and macro-level (NCAER 1981,1985) studies. The Indian energy research scene has been active and several studies are available on rural energy use (ABE 1985; Leach 1987; Veena 1988; Bose et al. 1991; Bhide 1992; Joshi et al. 19926). This does provide an opportunity to analyse the bioenergy situation in India. But as seen later in this chapter, the database is rather weak on certain aspects of biomass energy, for example, on the sources of the fuel wood used in rural India. In this chapter, an attempt is made to consolidate the existing information on various aspects of energy use in India with particular reference to biomass energy.
Bioenergy—a modernized fuel option for India
Authors: Ravindranath N H , Hall D O
Published: November 2023

The analysis of energy use patterns for India has shown the continued dominance of biomass, particularly in rural areas. Biomass use is usually characterized by low efficiency of use and lower quality of life. In order to promote development it is necessary to provide quality fuels (liquid and gaseous fuels) and electricity in a sustainable, equitable, and affordable way. The main focus of this book is on exploring the potential of bioenergy in meeting the energy needs of developing countries such as India. This is attempted here by defining the goals of development, the services requiring energy, the forms of energy required, and analysing the potential of bioenergy in comparison with other options.
Environmental and socio-economic benefits of bioenergy
Authors: Ravindranath N H , Hall D O
Published: November 2023

The current trends of energy provision and use based on commercial energy were shown to be non-sustainable, environmentally damaging, and leading to inequities. It will be useful first to understand the socio-economic and environmental implications of continuing with the existing patterns (business as usual, BAU) and the possible implications of adopting the proposed bioenergy options. Major environmental problems such as deforestation, submergence of forest (from hydroelectric projects), acid rain, global warming, and local air pollution are all linked in various ways to the extraction, processing, and use of energy. Environmental considerations have, however, rarely determined decisions on energy in the past. Now, due to local and global pressure, there is a change in the attitude of developing as well as industrialized countries, and environmental considerations are frequently included in energy planning. India, for example, has a clear policy to promote renewables on a medium- and long-term basis (Box 6.1). The need for and the potential of bioenergy options in meeting rural energy needs were presented in earlier chapters. In this chapter the social, economic, and environmental implications and opportunities created by adoption of bioenergy options in India are discussed.
Approaches to implementing bioenergy programmes
Authors: Ravindranath N H , Hall D O
Published: November 2023

One of the important aspects to be considered in utilizing the bioenergy potential in India is the feature of dispersed rural human settlements encompassing 75 per cent of the country’s population. Bioenergy options can provide a decentralized village-level, self-reliant energy system to meet village needs in a sustainable and environmentally sound way (Chapters 6 and 8). The next question we should ask is how can this be done. An approach to the implementation of rural bioenergy centre (RBC) schemes (which are at the heart of the proposed biomass-based energy programme) and of the large- scale bioenergy systems is considered in this chapter. Here we suggest an approach based largely on the Indian experience.
Principles and Tools: Questionnaires, Structured Interviews, Diaries, and Calendars
Authors: Jensen R , Bendtsen L
Published: November 2023

Headache is mainly a subjective phenomenon and we urgently need a biological marker, both in the diagnostic process and in the long-term follow-up guiding the physicians in the treatment strategy. In headache, we have to rely on the history of the patients and on a negative workup, where other diseases are excluded. In clinical practice, the efficiency of taking the history can be greatly augmented by the use of various instruments because headache patients, like most other pain patients, tend to report the most recent and the most severe headaches.
Trigeminal Autonomic Cephalalgias
Authors: Goadsby P J
Published: November 2023

The Trigeminal Autonomic Cephalalgias (TACs) is a grouping of headache syndromes recognized in the second edition of the International Headache Society classification. The term was coined to reflect some part of the pathophysiology of these conditions that is a common thread, viz., excessive cranial parasympathetic autonomic reflex activation to nociceptive input in the ophthalmic division of the trigeminal nerve.
A case of Hemicrania Continua Overlapping With Other Forms of Strictly Unilateral Headaches Associated With Autonomic Symptoms
Authors: Nappi G , Tassorelli C , Sances G , Cecchini A P , Guaschino E , Sandrini G
Published: November 2023

At two decades from its first description Hemicrania Continua (HC) remains an enigma in the field of primary headaches in terms of etiology and pathogenesis. In the recently released second edition of the International Classification of Headache Disorders (ICHD-II), HC has been aggregated to the fourth group ‘Other Primary Headaches’, not without a vivacious and prolonged discussion among the members of the Classification Subcommittee.
Hyperhomocysteinemia Due to MTHFR C677T Polymorphism as a Possible Link Between Stroke and Migraine In Young Populations
Authors: Marchione P , Giacomini P , Fortini D , Vento C , Samà D , Corigliano D , Nappi G
Published: November 2023

Increased homocysteine levels are associated with various pathological conditions in humans, including stroke and cardiovascular disorders. A recent study suggests that the MTHFR gene, causing mild hyperhomocysteinemia, may be a genetic risk factor for migraine. Homocysteine acts as an excitatory amino acid in vivo and may influence the threshold of migraine headache. The aim of this study is to evaluate the prevalence of migraine in stroke patients with hyperhomocysteine due to MTHFR polymorphism.
Posttraumatic Migraine Secondary to Organic Lesions
Authors: Pascual A M , Salvador A , Gil R , Láinez M J A
Published: November 2023

Posttraumatic Headache (PTH) is usually, one of the several symptoms of ‘post- concussion syndrome’ and therefore, may be accompanied by additional cognitive, behavioral, or somatic problems. A variety of pain patterns may develop after head injury and may closely resemble primary headache disorders. Tension-type is the most common variety of PTH, followed by cervicogenic headache, migraine, and cluster-like headaches.
National and International Action Plans for Improving Headache Diagnosis
Authors: Steiner T J
Published: November 2023

Headache disorders are ubiquitous, common, and disabling. Migraine alone, according to the World Health Organization (WHO), is nineteenth in the list of all causes of years of healthy life lost to disability (YLDs). There are huge consequential financial costs. Effective healthcare can alleviate much of this illness burden. The problem is that it depends not only on the existence of efficacious therapies, which we have, but also on the allocation of healthcare resources to deliver them to those who need them.
Genetics Of Rheumatoid Arthritis
Authors: Gregersen Peter K , Plenge, Robert M , Gulko Pércio S
Published: November 2023

Over the last five years, it has become apparent that the genetic factors underlying rheumatoid arthritis are more various and more complex than many in the field had originally thought. The major histocompatibility complex (MHC) remains the most important contributor to genetic risk for rheumatoid arthritis (RA), although HLA-DRB1 is clearly not the only locus involved in these MHC associations. The entire field of human genetics, particularly the genetics of complex disease, is currently under-going dramatic change, driven in part by astounding advances in genotyping technology, accompanied by substantial decreases in costs.
Skin infections in the cancer patient
Authors: Hay Roderick J
Published: November 2023

In many parts of the world infections of the skin are the commonest manifestations of skin disease. This is because the major factors determining the risk of infection are the ease of transmission of the organisms and their intrinsic pathogenicity rather than the underlying condition of the host. Many skin pathogens cause disease in a variety of different human hosts irrespective of the host’s underlying immune status. Infections such as bacterial pyoderma (impetigo), dermatophytosis or ringworm, scabies and viral warts (human papillomavirus or HPV infections) are all examples of these common infections (Table 9.1). Their transmission is generally determined by simple risk factors for exposure, such as communal activities including use of public swimming pools, overcrowding, and sometimes, lack of hygiene. Opportunities for spread between individuals under these circumstances are frequent. These infections are also seen in the immunosuppressed patient. Generally in such individuals their prevalence is no commoner, and sometimes less frequent, than that seen in the healthy population. The reasons for reduced prevalence may reflect a lower opportunity for spread due, for example, to reduction of communal activities. However, in immunologically predisposed patients skin infections may present with clinical manifestations that are either similar to those seen in normal individuals or more widespread, atypical in presentation or recalcitrant to therapy. For instance the lesions of furunculosis (staphylococcal boils) in the neutropenic patient may be widely distributed rather than clustered in one region or there may be an abnormal evolution of infection such as occurs in disseminated Fusarium infections originating from an infected toenail in the severely neutropenic patient. In short the presence of immunosuppression does not affect the prevalence of the infection but may alter its clinical expression (Chren et  al 1995).
Eye infections
Authors: Jayaram Hari , Graham Elizabeth
Published: November 2023

Cancer and its treatments increase the risk of developing infection and also create a risk from opportunistic pathogens that would not cause disease in normal individuals. The aim of this chapter is to highlight those conditions that may be encountered in the eye in the immunocompromised cancer patient, and facilitate early recognition, referral and initiation of treatment.
The Biology of Alpine Habitats
Authors: Nagy Laszlo , Grabherr Georg
Published: November 2023

This book is unique in providing a global overview of alpine (high mountain) habitats that occur above the natural (cold-limited) tree line, describing the factors that have shaped them over both ecological and evolutionary timescales. The broad geographic coverage helps synthesise common features whilst revealing differences in the world’s major alpine systems from the Arctic to the Tropics. The words “barren” and “wasteland” have often been applied to describe landscapes beyond the treeline. However, a closer look reveals a large diversity of habitats, assemblages and individual taxa, largely connected to topographic diversity within individual alpine regions. The book considers habitat-forming factors (landforms, energy and climate, hydrology, soils, and vegetation) individually, as well as their composite impacts on habitat characteristics. Evolution and population processes are examined in the context of the responsiveness / resilience of alpine habitats to global change. Finally, a critical assessment of the potential impacts of climate change, atmospheric pollutants and land use is made and related to the management and conservation options available for these unique habitats.
High mountains in latitude life zones: a worldwide perspective
Authors: Nagy Laszlo , Grabherr Georg
Published: November 2023

High mountains occur across all continents, from the Arctic to as far as 55°S, disregarding Antarctica (Fig. 2.1), in all broadly defined latitude zones (arctic, boreal, temperate, subtropical, and tropical) (Table 2.1). The definition of these broad latitude zones follows a simple model of a presumed climate effect, temperature, in particular, on living organisms from the Equator to the poles. However, there are difficulties in generalizing even simple temperature–vegetation latitude zone models. For example, a well-fitting Europe-wide model that uses annual mean temperatures to delineate vegetation zones (Ozenda 1994) has little applicability when extended to the scale of Eurasia, or beyond (Fig. 2.2). Temperature depends not only on the distance from the Equator, but indirectly, on the distance from the oceans; continentality is an important factor that results in such cold winters in Siberia that the annual temperatures average below zero there. According to the simple model in Fig. 2.2, this would cause a temperature climate akin to that in the Arctic. A much-refined pattern in variability is observed when a measure of growing season length is introduced (Fig. 2.3). In addition to temperature, the amount of precipitation, both in absolute terms, and relative to temperature and vegetation cover is important for living things. The main areas that have an arid or desert climate are shown in Fig. 2.4.
Concluding remarks
Authors: Nagy Laszlo , Grabherr Georg
Published: November 2023

Alpine environments are ‘cold’; however, in other aspects they encompass a large variability along three main axes: altitude, moisture, and seasonality (Fig. 11.1). There are many combinations possible in an environmental space that is bounded by these variables. Arctic alpine environments have a high seasonality, low precipitation, and negligible air density impact (bottom back left-hand side of Fig. 11.1). At the opposite end of the spectrum, aseasonal tropical alpine environments have very little seasonality, medium to high precipitation, and a marked reduction in air density (top front right-hand in Fig. 11.1). Ordering mountain regions in this way highlights the variety of alpine environments world-wide.

This virtual ordination space allows us to recount what we know about alpine environments, their habitats and biology. With regard to biodiversity, the effort in terms of coverage of alpine areas and organism groups has been uneven. On average, we have a reasonably good knowledge of the vascular plant flora of all the mountain regions (sometimes found in little known local literature). This knowledge can be in the form of very detailed accurate accounts in extensive mountain ranges where there is a long tradition of research. Few mountain range level accounts, if any match that in the Alps (Flora Alpina; Aeschimann et al. 2004), the existence of which allowed a recent systematic assessment of plant diversity patterns at the scale of the whole Alps range (INTRABIODIV). This is not the general pattern, however, and in most botanically well-known mountain ranges one has to piece the jigsaw together from country accounts (e.g. Scandinavia), or county-and state-level accounts (e.g. North American ranges).
Patients with upper gastrointestinal cancers
Authors: Watson Dr Max , Barrett Ann , Spence Roy AJ , Twelves Chris
Published: November 2023

Patients who are suitable for radical surgery do substantially better than those who are not. This is complex surgery best done by a specialized team. Surgery remains the only potentially curative modality for tumours in the lower two-thirds of oesophagus. By contrast, surgery is usually not appropriate for patients with tumours of the upper third, which require management in collaboration with specialist head and neck surgeons and oncologists. Unfortunately as a result of the tendency of oesophageal tumours to spread longitudinally through the submucosa, circumferentially to other mediastinal structures, and to lymph nodes early in their course, the results from surgery are disappointing. Neo-adjuvant chemotherapy with cisplatin and 5-fluorouracil improves resectability and reduces the likelihood of local and distant relapse. Studies have not as yet established that the increased morbidity is justified in terms of response and survival benefits Chemoradiotherapy may also be used with radical intent in tumours in the lower two-thirds of oesophagus in patients with localized disease who are unfit for surgeryEndoscopic placement of stents or radiotherapy may provide palliation.
Patients with tumours of the central nervous system
Authors: Watson Dr Max , Barrett Ann , Spence Roy AJ , Twelves Chris
Published: November 2023

Where it is possible, surgical resection alone for some low-grade tumours may be curative. Radiotherapy may be used as an alternative or adjunct to surgery. For higher grade lesions, decompression of the tumour may provide palliation and facilitate post-operative radiotherapy. Radiotherapy may be given if surgery is incomplete depending on the site. Delayed radiotherapy is probably as effective as immediate radiotherapy in this situation. It has recently been shown that the addition of chemotherapy to radiotherapy has an advantage in some patients.
Patients with sarcomas
Authors: Watson Dr Max , Barrett Ann , Spence Roy AJ , Twelves Chris
Published: November 2023

These rare malignant tumours of mesenchymal origin account for around 1% of all cancers but often occur in young people. In the past, treatment involved mutilating surgery and the prognosis was generally poor. Advances in surgery and chemotherapy mean that amputation is often avoided and survival has improved. Sarcomas may arise almost anywhere in the body and typically present with a slow-growing mass and/or pain. They are difficult to diagnose because they are rare. Symptoms are often non-specific and they can be hard to distinguish from much more common benign tumours. X-ray abnormalities are easily missed, and histological diagnosis can be difficult, so specialist pathology and radiology are vital. Unfortunately, in many patients the diagnosis is delayed.
Two surveys of mainland county biochemistry, diet and lifestyle (1983 and 1989) Reliability re-survey in selected mainland counties (1993)
Authors: Chen Junshi , Peto Richard , Pan Wenharn , Liu Boqi , Campbell T Colin , Boreham Jillian , Parpia Banoo , Cassano Patricia , Chen Zhengming , Feng Zulin , Gelband Hellen , Li Junyao , Pan Hongchao , Root Martin , Wu Yanping , Youngman Linda
Published: November 2023

In 1983, a survey of biochemistry, diet and lifestyle was undertaken in 65 of the 69 counties. In 1989, a more detailed survey was undertaken in all 69 of the counties, involving analyses of samples from adults aged 35 to 64 of plasma, of red blood cells, and, from men only, of urine; a three-day weighed household dietary survey, used to estimate average daily intakes of a wide variety of foods and nutrients per “reference man”; questionnaires (including some physical measurements) about dietary, lifestyle, anthropometric, social and economic factors, representing either the individuals being interviewed, their families, or their communities; and geographic characteristics of the county.
Mechanisms of inflammatory hyperalgesia
Authors: Inglis Julia J , Hunt, Stephen P , Kidd Bruce L
Published: November 2023

The ability of the immune response to recognize and eliminate foreign bodies such as viruses and tumours is essential to our survival. However in autoimmune diseases this process falters, and self is recognized as foreign and hence is attacked by the immune system. Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and destruction of the synovial joints. The small joints of the hands, feet, and knees tend to be worst affected, often with symmetrical inflammation. RA affects around 1 per cent of the population with an average age of onset of 35–45 years, with 75 per cent being female. The aetiology of the illness is unknown, with genetic, environmental and infectious factors implicated in disease susceptibility and severity. Whatever the initial trigger, the result is the infiltration of the synovium with leukocytes, proliferation of synovial fibroblasts, increased vascularity and the eventual degeneration of collagen and bone epiphyses.
Pathophysiological considerations in trigeminal neuralgia
Authors: Nurmikko T J
Published: November 2023

Much of the old tradition of pain medicine rested on simple principles, such as provision of pain relief by nerve blockade or necrolysis. Early pain clinicians were impressed by their observations on interruption of afferent pathways leading to major analgesia, albeit short-lived, and assumed that the same approach would be applicable to chronic pain. It eventually became clear that this view was overly simplistic and that in most cases neurodestructive methods fail, and the pain tends to recur and may even increase in intensity. From what is known today of multiple pain pathways, neuroplasticity, and post-injury neural recovery such a failure is no surprise. It is of interest that while these methods eventually fell into disrepute and are hardly used in chonic pain, the opposite happened in the surgical treatment of trigeminal neuralgia (TN) which really got underway over 100 years ago.
Discussion summary Modulation of pain
Authors: Jensen Troels Staehelin
Published: November 2023

Decades ago, research was mainly directed versus the inhibitory control exerted by the brain and brainstem on spinal cord mechanisms. In recent years, focus has been directed at the facilitating mechanisms controlling spinal cord and trigeminal mechanisms in processing noxious input. Important facilitating mechanisms in the lower brainstem have been clarified, using mainly electrophysiological and pharmacological techniques. The major research has been directed towards spinal cord mechanisms. An important issue was raised at the seminar by Barry Sessle, who posed the question of whether the spinal cord and the trigeminal systems are identical in terms of these facilitatory and inhibitory inputs.
Chlorophyll C Pigments And Their Distribution In The Chromophyte Algae
Authors: Jeffrey S W
Published: November 2023

The presence of chlorophyll c is a basic characteristic of the Chromophyte algae. Two light-harvesting chlorophyll c species are known, c  1 and c  2, which differ from all other chlorophylls in being porphyrin rather than chlorin derivatives. Structural similarities to the known chlorophyll a precursors, Mg 2,4-divinyl pheophorphyrin a  5 monomethyl ester (Mg 2,4D) and protochlorophyllide a, suggest that chlorophyll c biosynthesis may occur as a closely related branch of the biosynthetic pathway to chlorophyll a.
Distribution Patterns Of Carotenoids In Relation To Chromophyte Phylogeny And Systematics
Authors: Bjørnland Terje , Liaaen-Jensen Synnøve
Published: November 2023

A brief introduction to carotenoid chemistry, minimum requirements for proper characterization and unequivocal identification of carotenoids, as well as progress in chromatographic and spectrometric methods are given.
Relationships Between The Chromophyte Algae: The Evidence From Studies Of Mitosis
Authors: Green J C
Published: November 2023

The data obtained from studies of the fine structure of mitosis have allowed the elucidation of systematic affinities and a reassessment of phylogenetic relationships amongst certain algae, notably the green algae. Comparisons of the mitotic process in the chromophyte algae (algae containing chlorophylls a and c, but excluding here the dinoflagellates) are hampered, however, by the paucity of information on several of the major taxa with only a few groups (e.g. the diatoms and prymnesiophytes) having been examined in some detail.
Phylogenetic Relationships Of Dinoflagellates And Their Plastids
Authors: Dodge John D
Published: November 2023

Most photosynthetic dinoflagellates possess chlorophyll c, so it might be assumed that this group should be regarded as a component of the chromophyte series of algae. However, recent studies indicate that the chloroplasts are rather varied both in structure and pigment composition and almost certainly have been derived by endosymbiosis of eukaryotes. This process must have happened several times and is still being ‘experimented with’ by present-day dinoflagellates. The possible phylogenetic relationships of the Dinophyta are investigated by reference to the cell covering, flagella, nucleus and mitosis, mitochondria, ejectile organelles, and RNA. The strongest link to emerge is with the Ciliata with which the dinoflagellates may have shared a common ancestor.
Corethron And MallomonasõSome Striking Morphological Similarities
Authors: Crawford R M , Round F E
Published: November 2023

The marine, centric diatom Corethron is unique among the group in having separate, articulating components to the valves. These components (spines) and the valve structure are compared to the bristles and scales in a number of species of Mallomonas, especially M. plumosa. The close association of characters of strong resemblance is taken to indicate homology. The implications of such conclusions are briefly considered with respect to the phylogenetic relationships between the Synureae or Synurophyceae and the diatoms. We con” sider that the evidence lends further support to our proposal that the diatom frustule is derived from the wall of a scaly ancestor.
The Flagellar Apparatus Of The Oomycetes And Hyphochytriomycetes
Authors: Barr D J S , Désaulniers N L
Published: November 2023

The zoosporic fungi are a polyphyletic group comprising four classes. Two of these, the Oomycetes and Hyphochytriomycetes, are related to the chromophyte algae. The Oomycetes have two types of zoospores. One is reniform with two laterally attached flagella, and the other pyriform with two anteriorly or subapically attached flagella. In both types the anteriorly directed flagellum contains mastigonemes whereas the posterior flagellum is smooth and typically longer. The flagellar apparatus in oomycetous zoospores includes up to six distinct arrays (rootlets) of microtubules. The Hyphochytriomycetes have a single, anteriorly directed flagellum that contains mastigonemes, and the flagellar apparatus includes three rootlets. The flagellar apparatuses in the Oomycetes Phytophthora parasitica and Lagena radicicola have been analysed and are compared with Hyphochytrium catenoides.
The Nervous System
Authors: Bone Q , Goto T
Published: November 2023

Chaetognaths are rapid, active predators feeding on living prey (Chapter 5) and it is not surprising that they have a relatively elaborate nervous system, informed by a variety of different sensory inputs, including nearfield vibration receptors and (in most species) eyes of remarkably diverse structure.
Food and Feeding Behaviour
Authors: Feigenbaum David
Published: November 2023

All species of chaetognaths are carnivorous and may feed on several trophic levels. The benthic species are small and are minor constituents of their ecosystems but planktonic chaetognaths are often abundant. Since they are food for a wide variety of larger organisms (Bigelow 1924; David 1955; Reeve 1966) they occupy a central and sometimes important position in planktonic food webs.
Life history variation in female threespine stickleback
Authors: Baker John A
Published: November 2023

A life history can be viewed as a suite of co-adapted traits fashioned by natural selection to solve a particular ecological problem (Stearns 1976; Tuomi et al. 1983). Selection may act on individual traits in different manners, producing an overall life history that is a compromise among varying selection pressures. Life histories are thought to vary among populations within species, and among species, in a manner that reflects adaptation to local environmental conditions (e.g. Leggett and Carscadden 1978). Because much of the variation in life history traits may have a genetic basis, conditions experienced by a taxon in the past may have moulded some aspects of life history that are not currently adaptive (Ballinger 1983; Dunham et al. 1988). Therefore, phylogenetic constraints and historical relationships among populations and species must be accounted for in assessing the evolution of life histories (Wanntorp et al. 1990). The evolution of life history traits may be further constrained by genetic correlations and covariances among characters (Trendall 1982; Tuomi et al. 1983; Gaillard et al. 1989) and by physiological and energetic limitations on variation.
Palaeobiology and evolution of threespine stickleback
Authors: Bell Michael A
Published: November 2023

The fossil record provides a unique chronological perspective on evolutionary processes. Although it is fragmentary and interpretation of palaeobiological evidence is difficult (Levinton 1988; Hoffman 1989), the fossil record is the only source for most information on rates and patterns of evolutionary change, timing of origin and extinction of taxa, past existence of extinct forms, and previous geographical and ecological distributions. Information from the fossil record has an important role to play in our understanding of evolutionary processes.
Trophic strategies among heterotrophic flagellates
Authors: Sanders Robert W
Published: November 2023

Flagellates are common and abundant in most natural habitats and fulfil every trophic role from primary producer to carnivore. Many are voracious feeders on bacteria and play an important part in nutrient cycling and the degradation of organic matter. Osmotrophic (saprozoic) species are found in organically enriched environments with bacterivores, but are usually a minor component of the community in these habitats. Free-living flagellates can have a significant impact as grazers of algae, and, although few data exist, flagellate predation on other protists and metazoan gametes may affect the population dynamics of the prey species. Many flagellates with photosynthetic abilities are known to ingest prey ranging from bacteria to ciliates. The feeding habits of most species of heterotrophic flagellates are only superficially known. Given their ubiquitous nature, the quantitative and behavioural trophodynamics of heterotrophic flagellates is undoubtedly central to their ecological significance and to the flow of energy and materials through the microbial food web.
Chromatin Structure Of Plant Genes
Authors: Slatter Rosalind E , Gray John C
Published: November 2023

Plant growth and development requires a sophisticated programme of differential expression of nuclear genes. Individual plant cells express only specific sets of genes from the plant’s full gene complement, and knowledge of the mechanisms of differential gene expression is currently an important research objective. However, a full understanding of these processes is obviously a formidable task as it has been estimated that approximately 60000 genes are expressed during the life of a tobacco plant and these genes account for less than 5% of the nuclear genome (Kamalay and Goldberg, 1980). The plant’s transcription machinery is obviously able to identify the necessary genes amongst the vast excess of other genomic DNA and to transcribe them in the desired fashion. It seems reasonable to assume that the transcription apparatus is able to recognise certain features of the chromatin structure of genes to be transcribed, and that this structure is different from that of inactive genes. A major problem is to understand the changes in chromatin structure of active and inactive genes. Unfortunately, at the present time, it is often difficult to know if the detected alterations in chromatin structure are a prerequisite for or a consequence of changes in gene activity. The aim of this review is to provide an overview of the chromatin structure of plant genes, with some emphasis on structural changes that may be correlated with changes in gene activity. An understanding of the organisation of genes in the plant nucleus is an essential part of any attempt to understand the mechanisms of differential gene expression in plants.
Oil crops for the pharmaceutical industry
Authors: Lapinskas Dr Peter
Published: November 2023

Most oils (defined as long-chain fatty acids, normally in triglyceride form) derived from plants are used in pharmaceutical products primarily for their physical properties (Reynolds 1989). For instance, olive oil is used as a demulcent (to protect and soothe inflamed mouth tissue), as a mild laxative, as a component in emollient ointments and liniments, and as a lubricant; castor oil is a well-known ingredient of emollient creams, sesame oil is used as a solvent for steroids; and peanut oil is used as a mild enema and for softening ear wax. In addition, sunflower oil and soybean oil are used to provide energy and essential fatty acids for parenteral (e.g. intravenous) nutrition and some oils, such as castor oil, are used for making soaps and detergents which have medical uses. There is also a product (Lipiodol) based on a mixture of iodine with the ethyl esters of poppy seed oil which is used as a contrast medium for the visualization of the lymphatic system and nasal and other sinuses in radiography.
Conservation Goals and the Configuration of Biodiversity
Authors: Mcnaughton S J
Published: November 2023

Biodiversity in grasslands in the Serengeti National Park vanes widely. Consequently, the variety of food available to grazers also varies widely. Diversity varies hierarchically. The lowest spatial level is point diversity within sampling areas of small extent. The intermediate level is diversity of grassland swards or stands which contribute to diversity at two sub-levels: the communities of which they are members due to similarity of species composition, and the landscapes within which they occur. In the Serengeti grasslands, pattern diversity contributes to biodiversity at all levels. Within a sward about half of the diversity is due to pattern above the point level. At the level of point diversity species richness is almost five times as important as evenness. About half the diversity is variation in one place as compared to others, about a third variety of surrounding species, and about a tenth is due to how evenly species are represented. At the level of communities, classified by similarity of species composition of different swards, stand diversity is the overriding determinant. Integrity of species composition within communities means that there are similar grassland types throughout the ecosystem although they occur in different places. At the level of landscape regions, pattern diversity is an important element of vegetation diversity. However, less of the total variation in vegetation diversity is explained at this level than at any of the other levels, because it cannot be explained by either average diversity of stands or degrees of difference between stands. This is due to intergradation of different communities across a landscape.
Systematic Assessment of Taxic Diversity by Summation
Authors: Vane-Wright R I , Smith C R , Kitching I J
Published: November 2023

Combining data from many different taxonomic groups (up to 20 000 taxa has been suggested) will be necessary if meaningful priority areas analysis for conservation is to be achieved. Rapid analysis of data sets of more than about 1000 taxa using measures more complex than spanning-subtree weighting becomes prohibitively expensive, and coping with 20 000 is beyond present capability. Therefore, a method that combines the results of separate analyses in order to approximate the result of an all-inclusive analysis is required. Using data derived from owls, hawkmoths, milkweed butterflies, and tiger-beetles, analysed with the WORLDMAP program at regional (SE Asia) and national (Thailand) levels, we investigate methods for performing such combinations. An exact summation method is described for taxic richness, but for taxic difference measures (e.g. dispersion) we conclude that no similar exact solution exists. A heuristic measure, based upon re-ranking priority sequences, which can approximate the result of a combined analysis, is described and its limitations are discussed.
Photosynthetic pigments in the Haptophyta
Authors: Jeffrey S W , Wright S W
Published: November 2023

Knowledge of pigment systems is essential to our understanding of taxonomic and biological relationships within algal groups, and is an important parameter for measuring their abundance in aquatic systems. In this paper we review the development of knowledge of haptophyte pigments from the early 1960s to the late 1980s, and then present a new HPLC analysis of 29 species (50 strains) from eight out of 16 haptophyte families. Four pigment types were recognized. All contain chlorophylls a and c1/ ‘ diatoxanthin, diadinoxanthin, and /3,{3-carotene. In addition, Type I has fucoxanthin; Type 2, chlorophyll c3 and fucoxanthin (both types similar to diatoms); Type 3, chlorophyll es and 19’-hexanoyloxyfucoxanthin, and Type 4, chlorophyll es and 19’-butanoyloxfucoxanthin (plus variable amounts of 19’-hexanoyloxyfucoxanthin and fucoxanthin). Seven minor carotenoids, phytylated chlorophyll c and /3,e-carotene are also present in some strains. No clear-cut pigment pattern for all haptophytes has emerged, which emphasizes the caution oceanographers must still exercise in identification of this group of planktonic algae from pigment signatures.
Haptophytes in polar waters
Authors: Marchant Harvey J , Thomsen Helge A
Published: November 2023

Haptophytes are abundant and important constituents of the plankton of polar waters. The colonial stage of Phaeocystis commonly dominates the phytoplankton of the marginal ice zone where it is a major source of particulate and dissolved organic carbon. The extent to which this species contributes to carbon flux to the deep sea is equivocal, but recent evidence indicates that, despite heavy sedimentation, much is utilized by microbial activity and grazing in the upper aphotic zone. Phaeocystis is also a major source of the precursor of dimethyl sulfide, which in air is rapidly oxidized to a number of products including sulfate. It has been proposed that sulfate particles act as cloud condensation nuclei thereby influencing global albedo and therefore climate. Lightly calcified coccolithophorids are a characteristic, but not endemic, element of polar nanoplankton. Originally considered to be autotrophic, it has recently been found that they are heterotrophic. The mixotrophic genus Chrysochromulina occurs associated with the sea ice and in the water column. Finding scales of these organisms in gut contents of Antarctic krill, Euphausia superba, collected from under the ice during winter, has prompted speculation on the importance of mixotrophy in light limited polar waters.
Mixotrophy in haptophytes
Authors: Jones Harriet L J , Leadbeater B S C , Green J C
Published: November 2023

Mixotrophy, the uptake of particulate and dissolved organic carbon by photosynthetic algae, is widespread in haptophyte flagellates, in particular in the genus Chrysochromulina. Some species of Chrysochromulina have been shown to discriminate between particles on the basis of particle size and composition. Relatively large prey cells are selected by several species as well as, and sometimes in preference to, bacteria-sized particles. The digestion of prey has been studied in detail in C. brevifilum using transmission electron microscopy. Ingested food particles have been shown to be digested within food vacuoles. Some experiments have shown an increase in the rate of ingestion of particles under nutrient-limiting conditions though the crucial relationship with regard to mixotrophic behaviour is that between photosynthesis and phagotrophy. It is not yet known whether mixotrophic behaviour is governed by prey density or light intensity, and how this varies between species and between classes. The importance of phagotrophy to algal nutrition has shown that algae can be consumers as well as primary producers within the microbial loop. Evidence from grazing rates has also suggested that haptophyte flagellates may have a significant impact on the occurrence and density of their prey.
Coccolithophorid biocoenosis: production and fluxes to the deep sea
Authors: Takahashi Kozo
Published: November 2023

Coccolithophorids are one of the more important pelagic autotrophic calcium carbonate-producing plankton groups involved in the global carbon cycle. Their calcitic scales are produced in the euphotic layers and eventually become incorporated into sinking particles. Practically all of the coccoliths recovered from the deep sea have been rapidly transported via aggregates, such as marine snow and faecal pellets. Since the coccoliths in the deep sea were transported within a protective organic membrane, intact coccolithophorids can be recovered from deep sediment traps deployed below the calcium carbonate compensation depth. Coccoliths represent approximately two-thirds of the pelagic calcium carbonate production, followed by planktonic foraminifera and pteropods. Coccolithophorid standing stock and production levels, as well as seasonal flux amplitude, diminish towards the northern Polar region, suggesting that there is greater production in subarctic and lower latitudes. Emiliania huxleyi, a cosmopolitan coccolithophorid species, is the dominant form in most parts of the world oceans. In the northern high latitudes in the Atlantic, however, a cold water species, Coccolithus pelagicus, becomes seasonally more important than E. huxleyi during spring and summer. This is especially evident when the average coccolith mass of each species is incorporated in an assessment of the carbonate flux contribution: a placolith of C. pelagicus weighs two orders of magnitude more than a placolith of E. huxleyi.