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1.
J. W. Tudor Thomas 《BMJ (Clinical research ed.)》1953,2(4828):109-113
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A.J. Lustig 《Journal of the history of biology》2000,33(2):221-246
In the period 1875–1920, a debate about the generality and applicability of evolutionary theory to all organisms was motivated
by work on unicellular ciliates like Paramecium because of their peculiar nuclear dualism and life cycles. The French cytologist Emile Maupas and the German zoologist August
Weismann argued in the 1880s about the evolutionary origins and functions of sex (which in the ciliates is not linked to reproduction),
and death (which appeared to be the inevitable fate of lineages denied sexual conjugation), an argument rooted in the question
of whether the ciliates and their processes where homologous to other cellular organisms. In the beginning of the twentieth
century, this question of homology came to be less important as the ciliates were used by the British protozoologist Clifford
Dobell and the American zoologist Herbert Spencer Jennings to study evolutionary processes in general rather than problems
of development and cytology. For them, homology mattered less than analogy. This story illustrates two partially distinct
problems in evolutionary biology: first, the question of whether all living things have common features and origins; and second,
whether their history and current nature can be described by identical mechanisms. Where Maupas (contra Weismann) made the ciliates qualitatively the same as all other organisms in order to create a cohesive evolutionary theory for biology, Jennings and Dobell made them qualitatively
different in order to achieve the same end.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
E. F. Annison R. E. Brown R. A. Leng D. B. Lindsay C. E. West 《The Biochemical journal》1967,104(1):135-147
1. Rates of entry and oxidation of a range of metabolites have been measured in tracheostomized sheep (diet, 800g. of lucerne chaff and 100g. of maize/day) by combining isotope-dilution techniques with the continuous measurement of total respiratory gas exchange, and 14CO2 production during the intravenous or intraruminal infusion of 14C-labelled substrates. 2. Mean entry rates in fed and starved (24hr.) sheep respectively, expressed as mg./min./kg. body wt.0·75, were: glucose, 5·0 (range 4·8–5·1, 2 observations) and 3·8 (3·2–4·2, 4); acetate, 10·8 (9·1–13·5, 4) and 5·8 (1); d(−)-β-hydroxybutyrate, 1·4 (1) and 1·5 (0·8–2·4, 4); palmitate, oleate and stearate (starved sheep only) 1·0 (0·6–1·9, 7), 0·9 (0·2–1·6, 10) and 0·9 (0·5–1·1, 11) respectively. 3. Production rates of propionate and butyrate in continuously feeding sheep were 6·4 (4·7–8·3, 4) and 4·3 (3·4–6·1, 4) mg./min./kg.0·75 respectively, and in starved (24hr.) sheep were 2·5 (2·2–2·9, 2) and 1·0 (0·8–1·2, 2) mg./min./kg.0·75 respectively. 4. Calculated terminal values for the specific radioactivity of respiratory 14CO2 during measurements of entry rates and production rates were used to calculate the contributions of individual substrates to overall oxidative metabolism. Mean values for fed and starved sheep respectively were: glucose, 9·1 (8·6–9·6, 2) and 11·2 (5·9–15·1, 4)%; acetate, 31·6 (26·8–38·1, 4) and 22·1 (1)%; d(−)-β-hydroxybutyrate, 10·4 (1) and 4·8 (1·9–7·7, 4)%; propionate, 23·0 (13·8–29·9, 4) and 7·1 (6·8–7·4, 2)%; butyrate, 16·5 (13·7–20·5, 4) and 5·3 (5·2–5·3, 2)%; palmitate, oleate and stearate (starved sheep only), 4·7 (2·0–7·7, 7), 4·0 (1·2–6·6, 10) and 4·4 (3·8–5·8, 9)% respectively. The sum of these values for individual substrates in fed and starved sheep, excluding that of β-hydroxybutyrate and after correction of the glucose value for the known interrelations of this substrate with propionate, accounted for 76% and 58% respectively of total production of carbon dioxide. 5. Calculations based on the proportion of substrate entry directly oxidized indicated that the substrates studied accounted for 63% (fed sheep) and 43% (starved sheep) of total energy expenditure measured by oxygen uptake. The contribution of β-hydroxybutyrate was excluded, and corrections were made for glucose–propionate interrelations, and for the different rates of oxidation of the methyl and carboxyl fragments of acetate. 6. The present results have been combined with those obtained earlier in this Laboratory to examine the relationships between rates of substrate entry and oxidation, and concentrations of substrate in blood. Rates of entry of acetate, glucose, d(−)-β-hydroxybutyrate, palmitate and oleate (but not stearate) were well correlated with concentration in blood, and substrate contribution to production of carbon dioxide showed a similar correlation to blood concentration, except with glucose. 7. It was concluded that the general technique is of potential value in providing valid quantitative parameters of animal metabolism. 相似文献
4.
Lei KANG Jing HU Xue-shan XIA Jian-guo WU 《Virologica Sinica》2007,22(6):443-450
Human immunodeficiency virus (HIV) is the infectious agent causing acquired immu-nodeficiency syndrome (AIDS),a deadliest scourge of human society. Hepatitis C virus (HCV) is a major causative agent of chronic liver disease and infects an estimated 170 million people worldwide,resulting in a serious public health burden. Due to shared routes of transmission,co-infection with HIV and HCV has become common among individuals who had high risks of blood exposures. Among hemophiliacs the co-infection rate accounts for 85%; while among injection drug users (IDU) the rate can be as high as 90%. HIV can accelerate the progression of HCV-related liver disease,particularly when immunodeficiency has developed. Although the effect of HCV on HIV infection is controversial,most studies showed an increase in mortality due to liver disease. HCV may act as a direct cofactor to fasten the progression of AIDS and decrease the tolerance of highly active antiretroviral therapy (HARRT). Conversely,HAART-related hepatotoxicity may enhance the progression of liver fibrosis. Due to above complications,co-infection with HCV and HIV-1 has imposed a critical challenge in the management of these patients. In this review,we focus on the epidemiology and transmission of HIV and HCV,the impact of the two viruses on each other,and their treatment. 相似文献
5.
Daniel Liu 《Journal of the history of biology》2017,50(4):889-925
This article revisits the development of the protoplasm concept as it originally arose from critiques of the cell theory, and examines how the term “protoplasm” transformed from a botanical term of art in the 1840s to the so-called “living substance” and “the physical basis of life” two decades later. I show that there were two major shifts in biological materialism that needed to occur before protoplasm theory could be elevated to have equal status with cell theory in the nineteenth century. First, I argue that biologists had to accept that life could inhere in matter alone, regardless of form. Second, I argue that in the 1840s, ideas of what formless, biological matter was capable of dramatically changed: going from a “coagulation paradigm” (Pickstone, 1973) that had existed since Theophrastus, to a more robust conception of matter that was itself capable of movement and self-maintenance. In addition to revisiting Schleiden and Schwann’s original writings on cell theory, this article looks especially closely at Hugo von Mohl’s definition of the protoplasm concept in 1846, how it differed from his primordial utricle theory of cell structure two years earlier. This article draws on Lakoff and Johnson’s theory of “ontological metaphors” to show that the cell, primordial utricle, and protoplasm can be understood as material container, object, and substance, and that these overlapping distinctions help explain the chaotic and confusing early history of cell theory. 相似文献
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Fusarium, graminearum KF 370 isolate is able to simultaneous biosynthesis of three toxic metabolites, namely: fusarenone-X (FUS), nivalenol (NIV) and zearalenone (F-2). After metabolites extraction with methanol — water (3:1) and defatting with n-heptane toxins were partitioned into chloroform layer. Purification of the? compounds was performed on Celite 545 — charcoal — Aluminiumoxid 90 column then metabolites were separated on Kieselgel 60 (200–300 mesh) column with developing solvent chloroform — methanol. This way FUS, NIV and F-2 were obtained as crystalline or high purity standards. 相似文献
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When Do Allocations and Constructs Respect Material,Energy, Financial,and Production Balances in LCA and EEIO?
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Guillaume Majeau‐Bettez Richard Wood Edgar G. Hertwich Anders Hammer Strømman 《Journal of Industrial Ecology》2016,20(1):67-84
Conservation of mass and energy are essential to physical accounting, just as price and market balances are essential to economic accounting. These principles guide data collection and inventory compilation in industrial ecology. The resulting balanced surveys, however, can rarely be used directly for life cycle assessment (LCA) or environmentally extended input‐output (EEIO) analysis; some modeling is necessary to recast coproductions by multifunctional activities as monofunctional unit processes (a.k.a. Leontief production functions or technical “recipes”). This modeling is done with allocations in LCA and constructs in input‐output. In this article, we ask how these models respect or perturb the balances of the original inventory. Which allocations or constructs, applied to what type of data set, have the potential to simultaneously respect its multiple physical, financial, and market balances? Our analysis builds upon the recent harmonization of allocations and constructs and the ongoing development of multilayered supply and use inventory tables. We derive the necessary and sufficient conditions for balanced models, investigate the role of data aggregation, and clarify these models' relation to system expansion. We find that none of the modeling families in LCA and EEIO are balanced in general, but special data characteristics can allow for the respect of multiple balances. An analysis of these special cases allows for clear guidance for data compilation and methods integration. 相似文献
9.
Partial sequence homologies between cytoskeletal proteins,c-myc,Rous sarcoma virus and adenovirus proteins,transducin, and β- and γ-crystallins 总被引:1,自引:0,他引:1
Computer based sequence comparisons indicate partial sequence homology between human c-myc, Rous sarcoma virus, adenovirus 7, and simian sarcoma virus proteins and the cytoskeletal proteins desmin, keratin and vimentin. In addition, sections of the oncogene proteins showed partial but significant homology to and subunits of transducin, -II and -BP crystallins showed partial but significant homology to the cytoskeletal proteins keratin, vimentin, desmin, and -tubulin, and to adenovirus 7 and simian sarcoma virus transforming gene proteins. -BP crystallin showed partial but significant homology to Rous sarcoma virus protein, and to and y subunits of transducin. Both crystallins showed partial sequence homology to the GTP-binding protein elongation factor TU fromEscherichia coli . These sequence homologies suggest a link between the mechanisms of normal lens cell differentiation, involving modifications to the cytoskeleton and subsequent changes to the pattern of protein synthesis, and mechanisms of neoplastic transformation. Furthermore the transducin-like region on -crystallin may be important for its interaction with lens membranes and the maintenance of short-range order for lens transparency. 相似文献
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Sucrose, sucrosyl oligosaccharides, and oxidative stress: scavenging and salvaging? 总被引:2,自引:0,他引:2
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In nature, no single plant completes its life cycle withoutencountering environmental stress. When plant cells surpassstress threshold stimuli, chemically reactive oxygen species(ROS) are generated that can cause oxidative damage or act assignals. Plants have developed numerous ROS-scavenging systemsto minimize the cytotoxic effects of ROS. The role of sucrosyloligosaccharides (SOS), including fructans and the raffinosefamily oligosaccharides (RFOs), is well established during stressphysiology. They are believed to act as important membrane protectorsin planta. So far a putative role for sucrose and SOS duringoxidative stress has largely been neglected, as has the contributionof the vacuolar compartment. Recent studies suggest a link betweenSOS and oxidative defence and/or scavenging. SOS might be involvedin stabilizing membrane-associated peroxidases and NADPH oxidases,and SOS-derived radicals might fulfil an intermediate role inoxido-reduction reactions taking place in the vicinity of membranes.Here, these emerging features are discussed and perspectivesfor future research are provided. Key words: Fructan, oxidative stress, raffinose, ROS, sucrose, sucrosyl oligosaccharides
Received 25 September 2008; Revised 20 October 2008 Accepted 23 October 2008 相似文献
16.
Prisca Augustyn 《Biosemiotics》2009,2(1):1-17
The purpose of this paper is to describe some parallels and theoretical affinities between biosemiotics and biolinguistics. In particular, this paper examines the importance of Uexküll's Umwelt and Peircean abduction as foundational concepts for Sebeok's biosemiotics and Chomsky's biolinguistic program. Other affinities touched upon in this paper include references to concepts articulated by Immanuel Kant, Konrad Lorenz, Marcel Florkin, François Jacob, C.H. Waddington, D'Arcy Thomson and Ernst Haeckel. While both programs share theoretical influences and historiographical parallels in their mid-century origins continuing throughout the late twentieth century, recent articulations of biosemiotics and biolinguistics privilege different intellectual styles and methods of inquiry that define their future objectives as intellectual movements. The goal of this paper is to show that, in spite of the different scholarly agendas of biosemiotics and biolinguistics, both movements share a theoretical and philosophical core in Peirce and Uexküll. 相似文献
17.
《Inorganica chimica acta》1987,131(2):181-189
The dimetal decacarbonyls M2(CO)10, where M2 = Mn2, MnRe, and Re2, do not react with anionic strong oxidants such as Fe(CN)63− or IrCl62− in CH3CN solvent nor with neutral or cationic weak oxidants. Strong cationic oxidants such as NO+, Fe(phen)33+, and Cu2+ rapidly oxidize M2(CO)10 to 2M(CO)5(NCCH3)+ in acetonitrile solvent. The kinetics for the reaction suggest it proceeds according to a bimolecular outer sphere mechanism. 相似文献
18.
F. Bruce Sampson 《Grana》2013,52(3):135-145
The pollen morphology and ultrastructure of Austromatthaea elegans, Hedycarya angustifolia, H. loxocarya, Kibara rigidifolia, Leviera acuminata, Steganthera macooraia and Tetrasynandra laxiflora, are described. All are Australian members of the Monimiaceae sensu stricto of the order Laurales, subclass Magnoliidae. Except for Hedycarya angustifolia, which has pollen grains in permanent tetrads, all species have small, globose, apolar, inaperturate pollen. They can be identified under SEM by their surface ornamentation: Austromatthaea has fossulate sculpturing; Hedycarya angustifolia has tetrads with a warty configuration; H. loxocarya has echinate pollen; Kibara has spherical gemmae with nipple‐like projections; Leviera has stellate sculpturing; Steganthera has a verrucose surface with small spherical projections on each verruca, and Tetrasynandra is gemmate with one to several spiny projections on each gemma. The pollen grains of all genera of Australian Monimiaceae sensu stricto, some the results of previous studies, are summarized in tabular form. The exine has no columellae, foot layer or endexine, in contrast to the family Atherospermataceae (syn. subfamily Atherospermatoideae of the Monimiaceae, sensu lato). The most elaborate type of wall structure consists of radial elements ("radial processes") with white line‐centered regions extending from beyond the intine to the tectal region and a two‐layered intine with an outer channelled part (onciform zone). Trends of evolution from this type are discussed and comparisons are made with other Monimiaceae, Lauraceae, Amborellaceae and Trimeniaceae. 相似文献
19.
Pearson RD 《Trends in parasitology》2005,21(12):555-556
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Arachidonic acid (AA) is metabolized by cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) enzymes into eicosanoids, which are involved in diverse diseases, including type 1 and type 2 diabetes. During the last 30 years, evidence has been accumulated that suggests important functions for eicosanoids in the control of pancreatic β-cell function and destruction. AA metabolites of the COX pathway, especially prostaglandin E(2) (PGE(2)), appear to be significant factors to β-cell dysfunction and destruction, participating in the pathogenesis of diabetes and its complications. Several elegant studies have contributed to the sorting out of the importance of 12-LOX eicosanoids in cytokine-mediated inflammation in pancreatic β cells. The role of CYP eicosanoids in diabetes is yet to be explored. A recent publication has demonstrated that stabilizing the levels of epoxyeicosatrienoic acids (EETs), CYP eicosanoids, by inhibiting or deleting soluble epoxide hydrolase (sEH) improves β-cell function and reduces β-cell apoptosis in diabetes. In this review we summarize recent findings implicating these eicosanoid pathways in diabetes and its complications. We also discuss the development of animal models with targeted gene deletion and specific enzymatic inhibitors in each pathway to identify potential targets for the treatment of diabetes and its complications. 相似文献