Isolation of a neurosecretory substance which stimulates RNA synthesis in regenerating planarians

Summary An approach to the isolation of neurosecretory material from planarians is described. This material stimulated RNA synthesis, in a dose-dependent response, in regeneratingDugesia tigrina. The data support the concept that neurosecretion plays a key role in the process of regeneration in planarians.Supported by funds from the National Research Council of Canada.     

The occurrence and physiological functions of melatonin in the most primitive eumetazoans,the planarians

Asexual planarians of the speciesDugesia dorotocephala exhibit a distinct circadian rhythm of fissoning (asexual reproduction) under the influence of normal photoperiod; fissioning occurs only at night. This rhythm is broken down by continuous illumination, continuous darkness or by decapitation. The fissioning rate increases when planarians are exposed to light for less than 1 hour/day or when they are decapitated. Fissioning of decapitated planarians is suppressed by continuous treatment with melatonin, whereas fissioning resumes when these are returned to normal culture water. Interestingly, fissioning occurs at night when decapitates are treated with melatonin in the daytime, while it is observed in the daytime with night-time melatonin treatment. Endogenous melatonin was detected by HPLC and RIA. The endogenous melatonin level is always higher in those heads collected in the scotophase than in those collected in the photophase. A type of neurosecretory cell, which may synthesize melatonin, is found in the assembly of photoreceptor cells.     

Mise en évidence d'un système de corrélations intervenant dans la régénération des Planaires d'eau douce

Summary We show that there are correlations in regenerative fresh water planarians between all the parts of the body. When planarians are wounded in any part of the body, this mutilation will set regenerative cells in movement, which are able to travel a very long way in their migration. The extent and the speed of migration haves been shown by the method of localized X-ray irradiations.When the regenerative cells that are nearest to the wound have been killed with X-rays, regeneration occurs through the access of cells from the farther parts of the body. The nature of the stimulus is not yet known.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Planarians possess amazing abilities to regulate tissue homeostasis and regenerate missing body parts. These features reside on the presence of a population of pluripotent/totipotent stem cells, the neoblasts, which are considered as the only planarian cells able to proliferate in the asexual strains. Neoblast distribution has been identified by mapping the cells incorporating bromodeoxyuridine, analyzing mitotic figures and using cell proliferation markers. Recently identified molecular markers specifically label subgroups of neoblasts, revealing thus the heterogeneity of the planarian stem cell population. Therefore, the apparent totipotency of neoblasts probably reflects the composite activities of multiple stem cell types. First steps have been undertaken to understand how neoblasts and differentiated cells communicate with each other to adapt the self-renewal and differentiation rates of neoblasts to the demands of the body. Moreover, the introduction of molecular resource database on planarians now paves the way to renewed strategies to understand planarian regeneration and stem cell-related issues.     

Melatonin: presence and formation in invertebrates

In vertebrates, it is now clearly demonstrated that the pineal gland is implicated in conveying photoperiodic information via the daily pattern of melatonin secretion. Invertebrates, like vertebrates, use photoperiodic changes as a temporal cue to initiate physiological processes such as reproduction or diapause. How this information is integrated in invertebrates remains an unsolved question. Our review will be an attempt to evaluate the possible role of melatonin in conveying photoperiodic information in invertebrates. It is now well demonstrated in both vertebrates and invertebrates that melatonin as well as its precursors or synthesizing enzymes are present in various organs implicated in photoreceptive processes or in circadian pacemaking. Melatonin, serotonin or N-acetyltransferase have been found in the head, the eyes, the optic lobe and the brain of various invertebrate species. In some species it has also been shown that melatonin is produced rhythmically with high concentrations reached during the dark period. Moreover, the physiological effects of melatonin on various periodic processes such as rhythmic contractions in coelenterates, fissioning of asexual planarians or reproductive events in flies have been reported in the literature. All these results support the hypothesis (refs 36, 37) that melatonin is not solely a pineal hormone but that it may be an evolutionary conservative molecule principally involved in the transduction of photoperiodic information in all living organisms.     

新型道路修补材料研制及微观分析

利用X-射线、电镜和差热分析等方法对明矾石的物理和化学性质进行了分析，通过对明矾石进行加工处理，研制出一种含有明矾石的新型道路修补材料，该材料与水泥基材料具有相似的性能和较好的相容性，为明矾石的开发利用提供了一个新的方法和途径。     

Museums and scientific material culture at the University of Toronto

Since its foundation in the mid-nineteenth century, the University of Toronto has accumulated a substantial number of historically-significant scientific objects. As Canada’s largest research university, much of this material is of national significance. Despite numerous attempts since the late 1970s to establish a universal policy for the preservation and safeguarding of scientific apparatus, the survival of Toronto’s scientific material heritage has depended partly on the initiatives of dedicated individuals, partly on luck.The following examination seeks a comprehensive history of the material culture of science at the University, focussing on scientific instrumentation and natural history collections. It examines the circumstances under which some material survives and traces efforts to develop a curated collection, concluding with some recent progress in acquiring storage and developing an online catalogue. It argues that early university science museums formed an important venue through which the University fulfilled its public function of studying the frontier and assisting the expansion of the colonies. The display and interpretation of scientific material culture had an important impact on the University’s early history.     

混凝土材料非线性多轴动态强度准则

将广义非线性强度理论的4个材料参数转化为混凝土材料的基本强度参数,通过混凝土材料的基本强度特性,分析了4个材料参数的变化规律与取值范围.基于S准则建立了混凝土材料4个基本强度参数的率效应表达式,建立了混凝土材料的非线性多轴动态强度准则,分析了动态强度参数的率效应规律,结果表明,混凝土材料的强度特性随着应变率的提高,逐渐向金属材料的强度特性过渡,在应变率从-3~3,应变率对混凝土动态强度的影响较大,并且动强度不是随着应变率的提高无限增大的,而是存在动强度峰值.通过与3组双轴压-压和2组双轴拉-压动态加载时混凝土材料试验结果的比较,表明非线性多轴动态强度准则可较好地描述混凝土材料双轴动强度规律.在同一应变率下,可较好地描述强度的非线性特性;不同应变率下,动强度面互不相交,即应变率效应与多轴应力状态对强度规律不存在耦合影响.     

21世纪冶金和材料制备学的发展及对策

21世纪中冶金学及材料制备学的发展在于两个方向。其一是信息论冶金学和材料制备学；其二是在若干外加物理场综合作用下的7台金和材料制备过程。前者意在创建冶金学及材料制备学的一个新的高度。所以，由基础研究到过程控制有5个平台包含在此概念之中。关于第二个方向，本文讨论了超强磁场、脉冲电磁场、脉冲电流、超声波、等离子体以及离子选择性高效透过膜的应用可能性。对企业的发展提出了一个建议：应懂得技术储备的重要。     

Prothymosin alpha is not a nuclear polypeptide

Using a radioimmunoassay for the NH2-terminus of prothymosin alpha, the crossreactive material was measured in subcellular fractions of calf thymus and liver. No significant amount of crossreactive material was found in the nucleus. This provides experimental evidence against a recent hypothesis, based on structural evidence, that prothymosin alpha is a nuclear polypeptide.     

The Garching nuclear egg: Teaching contemporary history beyond the linguistic turn

In my paper I argue for mobilising recent material heritage at universities in teaching history of contemporary science. Getting your hands dirty in the messy worlds of the laboratory and the storage room, and getting entangled with the commemorative practices of scientists and technicians does not belong to the common experiences of students in history and philosophy of science. Despite the recent material turn in cultural studies, students’ engagement with the material world often remains a linguistic exercise, extending at most to an excursion to the sanitised and academically encultured world of the museum exhibit.I contrast this approach by drawing on experiences of taking students to the Atomei, Germany’s oldest research reactor at the Garching campus of the Munich University of Technology. Decommissioned since 2000, the installation and its history are still controlled by scientists. Studying contemporary laboratories and their materiality has so far been the domain of sociologists and ethnographers. I argue for opening these spaces to historians of science and engaging with the ‘unfinished’ material world of contemporary science. Taking the material seriously beyond the linguistic turn and asking students to explore laboratories and other sites of knowledge production challenges existing histories and historiographies. By exploring local university departments and their recent histories through their material heritage, we can observe everyday science and confront scientists and technicians’ cultures with those of historians’. By engaging with recent material heritage as historians and archivists, students can make an important contribution to enhancing the awareness about this heritage, its implications for history writing, as well as its documentation and preservation.     

Hydroxyproline concentration in soluble and insoluble material from serum treated with trichloroacetic acid in postpartum mice

Summary The hydroxyproline concentration in both the soluble and insoluble material from trichloroacetic acid-treated serum from postpartum mice was determined. The hydroxyproline concentration in the insoluble material increased, but that in the soluble material did not increase during the uterine involuting period.     

Hydroxyproline concentration in soluble and insoluble material from serum treated with trichloroacetic acid in postpartum mice

The hydroxyproline concentration in both the soluble and insoluble material from trichloroacetic acid-treated serum from postpartum mice was determined. The hydroxyproline concentration in the insoluble material increased, but that in the soluble material did not increase during the uterine involuting period.     

Prothymosin alpha is not a nuclear polypeptide

Summary Using a radioimmunoassay for the NH₂-terminus of prothymosin alpha, the crossreactive material was measured in subcellular fractions of calf thymus and liver. No significant amount of crossreactive material was found in the nucleus. This provides experimental evidence against a recent hypothesis, based on structural evidence, that prothymosin alpha is a nuclear polypeptide.     

Epistemic benefits of the material theory of induction

C. D. Broad famously labelled the problem of providing our inductive practices with a proper justification “the scandal of philosophy” (Broad, 1952). Recently, John Norton has provided a dissolution of this problem (2014). According to Norton, inductive inference is grounded in particular facts obtaining within particular domains (J. Norton, 2003b, 2010, 2014). Because the material theory does not involve a universal schema of induction, Norton claims it dissolves the problem of induction (which implies that such universal schemas cannot be justified).In this paper, I critically evaluate Norton's dissolution. In particular, I argue that the problem of induction is an epistemological problem, that Norton's material theory entails an externalist epistemology, and that it is a common feature of such epistemologies that they dissolve the problem of induction. The upshot is that the material theory is not unique in its ability to reap the specifically epistemic benefits of dissolving the problem of induction, and thus that the epistemic advantages of the material theory over extant alternatives in this regard are fewer than it may appear at first sight.     

Intranuclear crystalloids in arcuate nucleus neurons after clomiphene citrate administration

Summary The action of high doses of clomiphene citrate on the nuclei of hypothalamic arcuate neurons of male cats has been studied. Clomiphene produces an accumulation of typical crystalloid material in the nuclei. After administration of a protein-synthesis inhibitor, no such material was observed in clomiphene-treated animals.These ultrastructural features could possibly be due to a more intense protein synthesis in the hypothalamic arcuate neurons.     

Attraction of primordial germ cells by notochord in seven somites chick embryo

Summary Chemical studies in chick embryo have indicated the existence of proteoglycan in notochordal sheath. Primordial germ cells were observed with scanning electron microscope on the notochord dorsal face, surrounded with perichordal material. We postulate the identification of such a material with proteoglycan which could attract primordial germ cells to the notochord.     

Intranuclear crystalloids in arcuate nucleus neurons after clomiphene citrate administration

The action of high doses of clomiphene citrate on the nuclei of hypothalamic arcuate neurons of male cats has been studied. Clomiphene produces an accumulation of typical crystalloid material in the nuclei. After administration of a protein-synthesis inhibitor, no such material was observed in clomiphene-treated animals. These ultrastructural features could possibly be due to a more intense protein synthesis in the hypothalamic arcuate neurons.     

Demonstration of a basal lamina in cocultures of thyroid cells and embryonal swine skin cells]

Porcine thyroid and embryo skin cells were isolated and cultured. Cultures from each kind of cells, as well as cocultures were fixed twice a week for electron microscopy. On day 8th a basal lamina like material appears only in the cocultures, along the basal plasmalemma of the reassociated thyroid cells. This amorphous material increases up to day 17th.     

聚氨酯材料在生物医学中的研究进展

聚氨酯是一种合成的高分子化合物，有较好的机械性能、高弹性和理想的生物相容性，被广泛地用于生物医学领域。本文综述了聚氨酯在凝胶材料、弹性体材料、膜材料以及抗菌材料等方面的研究现状及应用前景。