Secretion of cytokinins in vivo and in vitro byAlternaria brassicicola and their role in pathogenesis

Summary Formation of green islands in the host (mustard leaves) beneath the infection-drops containing germinating conidia ofAlternaria brassicicola (Schw.) Wiltsch. has been correlated with the secretion of cytokinins by the pathogen.A. brassicicola also synthesized cytokinins in the liquid synthetic medium. Cytokinins produced in vitro were extracted, and their application on the detached mustard leaves evoked the formation of green islands.     

Structures and molecules involved in generation and regulation of biological rhythms in vertebrates and invertebrates

Melatonin from the retina and the pineal gland functions in neuroendocrine hierarchies. Photoreceptors — eyes and extraretinal — detect light. Oscillators — pineal and suprachiasmatic nuclei — act as pacemakers. Driven neuroendocrine rhythms carry temporal hormone signals throughout the body. Light controls melatonin: light sets the phase of the melatonin rhythm and determines the duration of melatonin synthesis. By these means, circadian rhythms (e.g. in locomotor activity and body temperature) and seasonal rhythms (e.g. in reproduction) are controlled.     

Telomeres and meiosis in health and disease

Beyond their role in replication and chromosome end capping, telomeres are also thought to function in meiotic chromosome pairing, meiotic and mitotic chromosome segregation as well as in nuclear organization. Observations in both somatic and meiotic cells suggest that the positioning of telomeres within the nucleus is highly specific and believed to be dependent mainly on telomere interactions with the nuclear envelope either directly or through chromatin interacting proteins. Although little is known about the mechanism of telomere clustering, some studies show that it is an active process. Recent data have suggested a regulatory role for telomere chromatin structure in telomere movement. This review will summarize recent studies on telomere interactions with the nuclear matrix, telomere chromatin structure and factors that modify telomere chromatin structure as related to regulation of telomere movement.     

Differences in the content and turnover of noradrenaline in rat heart atria and ventricles and circadian-phase-dependency

In light-dark-synchronized male rats the levels of noradrenaline in heart atria were about 3 times that found in heart ventricles. Noradrenaline turnover rate which were about 8-9 fold greater for the atria than for the ventricles displayed a circadian-phase-dependency with increased rates in the dark period in both parts of the rat heart.     

Telomeres and meiosis in health and disease

Meiotic dysfunction increasingly afflicts women as they age, resulting in infertility, miscarriage and handicapped offspring. How aging disrupts meiotic function in women remains unclear, but as women increasingly delay childbearing, this issue becomes urgent. Telomeres, which mediate aging in mitotic cells, may also mediate aging during meiosis. Telomeres shorten during DNA replication. In mammals, oocytes remain quiescent, but their precursors replicated during fetal oogenesis. Moreover, eggs ovulated from older women entered meiosis later during fetal oogenesis than eggs ovulated when younger, and therefore underwent more replications. Telomeres also shorten from reactive oxygen, which triggers a DNA repair response, so the prolonged interval between fetal oogenesis and ovulation in some women would further shorten telomeres. Mice normally do not exhibit age-related meiotic dysfunction (interestingly, their telomeres are manyfold longer than telomeres in women), but genetic or pharmacologic shortening of mouse telomeres recapitulates the reproductive aging phenotype of women. This has led to a telomere theory of age-related meiotic dysfunction in women, and underlined the importance to human health of a mechanistic understanding of telomeres and meiosis.     

Telomeres and meiosis in health and disease

The aim of this review is threefold. First, we want to report on recent observations on the role of telomeres in the alignment of homolog and non-homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and the relationship of early telomere clustering to later recombination events. Second, we compare the similarities and differences between synaptic and asynaptic yeasts. Third, we report on the increasing evidence of the effect of meiosis on telomeric sequences that suggest an induction of a specific form of recombination processes termed telomere rapid deletion.     

Studies of total and protein-bound plasma Mg++ in wild and hatchery-reared coho salmon smolts in freshwater and in seawater

Summary Total plasma Mg⁺⁺ and Ca⁺⁺, Mg⁺⁺ in erythrocytes as well as protein-bound plasma Mg⁺⁺ were investigated in wild and hatchery-reared smolts. The proportion of plasma Mg⁺⁺ which was bound to plasma protein did not change significantly during entry into seawater, even though the in vitro addition of exogenous Mg⁺⁺ to the plasma showed that additional binding was possible.     

Telomeres and meiosis in health and disease

Telomeres are important segments of chromosomes that protect chromosome ends from nucleolytic degradation and fusion. At meiosis telomeres display an unprecedented behavior which involves their attachment and motility along the nuclear envelope. The movements become restricted to a limited nuclear sector during the so-called bouquet stage, which is widely conserved among species. Recent observations suggest that telomere clustering involves actin and/or microtubules, and is altered in the presence of impaired recombinogenic and chromosome related functions. This review aims to provide an overview of what is currently known about meiotic telomere attachment, dynamics and regulation in synaptic meiosis.     

Telomeres and meiosis in health and disease

Telomeres are important segments of chromosomes that protect chromosome ends from nucleolytic degradation and fusion. At meiosis telomeres display an unprecedented behavior which involves their attachment and motility along the nuclear envelope. The movements become restricted to a limited nuclear sector during the so-called bouquet stage, which is widely conserved among species. Recent observations suggest that telomere clustering involves actin and/or microtubules, and is altered in the presence of impaired recombinogenic and chromosome related functions. This review aims to provide an overview of what is currently known about meiotic telomere attachment, dynamics and regulation in synaptic meiosis.     

Fenofibrate inhibits angiogenesis in vitro and in vivo

Fenofibrate, a peroxisome proliferator-activated receptor (PPAR)-alpha activator, used as a normolipidemic agent, is thought to offer additional beneficial effects in atherosclerosis. Since angiogenesis is involved in plaque progression, hemorrhage, and instability, the main causes of ischemic events, this study was designed to evaluate the action of fenofibrate on angiogenesis. Our results show that fenofibrate (i) inhibits endothelial cell proliferation induced by angiogenic factors, followed at high concentrations by an increase in apoptosis, (ii) inhibits endothelial cell migration in a healing wound model, (iii) inhibits capillary tube formation in vitro, and (iv) inhibits angiogenesis in vivo. Concerning the mechanism of action, the inhibition of endothelial cell migration by fenofibrate can be explained by a disorganization of the actin cytoskeleton. At the molecular level, fenofibrate markedly decreased basic fibroblast growth factor-induced Akt activation and cyclooxygenase 2 gene expression. This inhibition of angiogenesis could participate in the beneficial effect of fenofibrate in atherosclerosis.     

Leptin signaling and circuits in puberty and fertility

Leptin is an adipocyte-derived hormone involved in a myriad of physiological process, including the control of energy balance and several neuroendocrine axes. Leptin-deficient mice and humans are obese, diabetic, and display a series of neuroendocrine and autonomic abnormalities. These individuals are infertile due to a lack of appropriate pubertal development and inadequate synthesis and secretion of gonadotropins and gonadal steroids. Leptin receptors are expressed in many organs and tissues, including those related to the control of reproductive physiology (e.g., the hypothalamus, pituitary gland, and gonads). In the last decade, it has become clear that leptin receptors located in the brain are major players in most leptin actions, including reproduction. Moreover, the recent development of molecular techniques for brain mapping and the use of genetically modified mouse models have generated crucial new findings for understanding leptin physiology and the metabolic influences on reproductive health. In the present review, we will highlight the new advances in the field, discuss the apparent contradictions, and underline the relevance of this complex physiological system to human health. We will focus our review on the hypothalamic circuitry and potential signaling pathways relevant to leptin’s effects in reproductive control, which have been identified with the use of cutting-edge technologies of molecular mapping and conditional knockouts.     

Space and Time in Particle and Field Physics

Textbooks present classical particle and field physics as theories of physical systems situated in Newtonian absolute space. This absolute space has an influence on the evolution of physical processes, and can therefore be seen as a physical system itself; it is substantival. It turns out to be possible, however, to interpret the classical theories in another way. According to this rival interpretation, spatiotemporal position is a property of physical systems, and there is no substantival spacetime. The traditional objection that such a relationist view could not cope with the existence of inertial effects and other manifestations of the causal efficacy of spacetime can be answered successfully. According to the new point of view, the spacetime manifold of classical physics is a purely representational device. It represents possible locations of physical objects or events; but these locations are physical properties inherent in the physical objects or events themselves and having no existence independently of them. In relativistic quantum field theory the physical meaning of the spacetime manifold becomes even less tangible. Not only does the manifold lose its status as a substantival container, but also its function as a representation of spacetime properties possessed by physical systems becomes problematic. ‘Space and time’ become ordering parameters in the web of properties of physical systems. They seem to regain their traditional meaning only in the non-relativistic limit in which the classical particle concept becomes approximately applicable.     

Catecholamine levels in newborn human plasma in normal and abnormal conditions and in maternal plasma at delivery

Summary High levels of catecholamines have been found in plasma from the umbilical cord of newborn infants, suggesting a release of catecholamine from the fetus during parturition. Plasma catecholamine levels are also elevated in mothers at delivery.     

Pollen flight forecasting in Germany and in Europe

Every tenth person in Central Europe is a pollinosis patient. The time of ripening and release of pollen, as well as pollen flight, all depend on the weather. Because each year is different from every other, mean values from pollen calendars do not provide any practical help for allergy-sufferers. For this reason, in many European countries, measuring networks have been established during the last 10 years as a basis for forecasting the prevalence of airborne pollen for the following 2–3 days, in connection with the weather forecast. Cooperation and communication also exist on a European level, and a European Pollen Database has been established.     

Ethanol-induced changes in plasma glucose,insulin and glucagon in fed and fasted rats

Summary Orally administered ethanol produced dose-related suppression of IRI levels and elevation of IRG levels in fed and fasting rats. Plasma glucose levels were unaffected in the fasting rats, but a moderate hyperglycemic response accompanied the decline in IRI and the rise in IRG observed in the fed rats.This research was supported in part by a grant from the National Institute on Alcohol Abuse and Alcoholism (AA-3218) and by a supplemental grant from the National Council on Alcoholism.     

Hyaluronan synthesis and degradation in cartilage and bone

Hyaluronan (HA) is a large but simple glycosaminoglycan composed of repeating D-glucuronic acid, β1–3 linked to N-acetyl-D-glucosamine β1–4, found in body fluids and tissues, in both intra- and extracellular compartments. Despite its structural simplicity, HA has diverse functions in skeletal biology. In development, HA-rich matrices facilitate migration and condensation of mesenchymal cells, and HA participates in joint cavity formation and longitudinal bone growth. In adult cartilage, HA binding to aggrecan immobilises aggrecan, retaining it at the high concentrations required for compressive resilience. HA also appears to regulate bone remodelling by controlling osteoclast, osteoblast and osteocyte behaviour. The functions of HA depend on its intrinsic properties, which in turn rely on the degree of polymerisation by HA synthases, depolymerisation by hyaluronidases, and interactions with HA-binding proteins. HA synthesis and degradation are closely regulated in skeletal tissues and aberrant synthetic or degradative activity causes disease. The role and regulation of HA synthesis and degradation in cartilage, bone and skeletal development is discussed. Received 5 August 2007; received after revision 19 September 2007; accepted 20 September 2007     

美国联邦政府实验室测度与保证高水平科学研究的做法与启示

本文概述了美国联邦政府实验室在测度与保证高水平科学研究时普遍采用的一些做法，进而以美国陆军实验室(ARL)为例，剖析了它们的具体实践，最后尝试总结出对我国科研管理工作的一些启示。     

Eugenics and politics in Britain in the 1930s

This paper discusses the surprising resurgence in the fortunes of the British eugenics movement in the 1930s. It is argued that although mass unemployment may in the long run have discredited that version of eugenics in which social dependence and destitution were attributed to genetic defect, in the short run the Depression was often perceived as a vindication of the eugenical creed. In particular, the attempt to reduce the fertility of the unemployed by popularising birth control techniques, and the voluntary sterilization campaign aimed at preventing the propagation of defectives from the so-called Social Problem Group, satisfied the urge felt by many conservative members from the professional classes to respond creatively to the country's crisis, without endangering existing social and economic institutions. It is also shown that not until 1938 did events in Germany cause substantial damage to the cause of eugenics in Britain. In fact, the ‘German experiment’ was actually greeted with approval by certain British eugenists of an authoritarian cast of mind. However, the Society as a whole never identified with these right-wing extremists, thanks in part to the moderating influence exercised by its General Secretary, Dr. C. P. Blacker, whose prime concern was with psycho-medical problems likely to concern people of all party persuasions.     

Cholinesterase in the atherosclerotic intima and in fibroblast cultures

Summary Cholinesterase activity was present in the atheromatous plaque of the rabbit's atherosclerotic aorta. Cholinesterase activity was significantly increased in rat fibroblast cultures grown in the presence of hypercholesterolemic serum. Cholesterol ester synthesis in these cultures was inhibited by neostigmine, a cholinesterase inhibitor.Acknowledgments. We thank Patricia Fontaine for technical assistance and Patricia Candow and Barbara English for secretarial help. This work was supported by a grant from the Canadian Heart Foundation. Part of this work was presented at 1977 annual meeting of the Biochemical Society in London.