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51.
C. A. Baile F. Anne Scott J. Mayer 《Cellular and molecular life sciences : CMLS》1967,23(12):1033-1034
Résumé Par des lésions bilatérales hypothalamiques on a rendu des rats aphagiques et adipsiques. Durant la période de convalescence, on a injecté dans le ventricule latéral du pentotal de sodium (ce qui normalement fait manger les animaux) et une solution saline hypertonique (qui normalement les fait boire). On a trouvé qu'après les lésions les rats ne réagissent que lorsqu'ils sont redevenus capables de manger et de boire spontanément.
This work was supported in part by a grant from the National Institute of Neurological Diseases and Blindness, No. NB 01941, of the National Institutes of Health, U.S. Public Health Service, Bethesda, Maryland; by a grant from the National Science Foundation, No. GB-4594, Washington, D.C.; and the Fund for Research and Teaching of the Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts. 相似文献
This work was supported in part by a grant from the National Institute of Neurological Diseases and Blindness, No. NB 01941, of the National Institutes of Health, U.S. Public Health Service, Bethesda, Maryland; by a grant from the National Science Foundation, No. GB-4594, Washington, D.C.; and the Fund for Research and Teaching of the Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts. 相似文献
52.
Chromatin-modifying enzymes as modulators of reprogramming 总被引:2,自引:0,他引:2
Onder TT Kara N Cherry A Sinha AU Zhu N Bernt KM Cahan P Marcarci BO Unternaehrer J Gupta PB Lander ES Armstrong SA Daley GQ 《Nature》2012,483(7391):598-602
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54.
Centrioles are necessary for flagella and cilia formation, cytokinesis, cell-cycle control and centrosome organization/spindle assembly. They duplicate once per cell cycle, but the mechanisms underlying their duplication remain unclear. Here we show using electron tomography of staged C. elegans one-cell embryos that daughter centriole assembly begins with the formation and elongation of a central tube followed by the peripheral assembly of nine singlet microtubules. Tube formation and elongation is dependent on the SAS-5 and SAS-6 proteins, whereas the assembly of singlet microtubules onto the central tube depends on SAS-4. We further show that centriole assembly is triggered by an upstream signal mediated by SPD-2 and ZYG-1. These results define a structural pathway for the assembly of a daughter centriole and should have general relevance for future studies on centriole assembly in other organisms. 相似文献
55.
Epigenetic concepts are fundamentally shaped by a legacy of negative definition, often understood by what they are not. Yet the function and implication of negative definition for scientific discourse has thus far received scant attention. Using the term epimutation as exemplar, we analyze the paradoxical like-but-unlike structure of a term that must simultaneously connect with but depart from genetic concepts. We assess the historical forces structuring the use of epimutation and like terms such as paramutation. This analysis highlights the positive characteristics defining epimutation: the regularity, oxymoronic temporality, and materiality of stable processes. Integrating historical work, ethnographic observation, and insights from philosophical practice-oriented conceptual analysis, we detail the distinctive epistemic goals the epimutation concept fulfils in medicine, plant biology and toxicology. Epimutation and allied epigenetic terms have succeeded by being mutation-like and recognizable, yet have failed to consolidate for exactly the same reason: they are tied simultaneously by likeness and opposition to nouns that describe things that are assumed to persist unchanged over space and time. Moreover, negative definition casts the genetic-epigenetic relationship as an either/or binary, overshadowing continuities and connections. This analysis is intended to assist practitioners and observers of genetics and epigenetics in recognizing and moving beyond the conceptual legacies of negative definition. 相似文献
56.
Marscher AP Jorstad SG D'Arcangelo FD Smith PS Williams GG Larionov VM Oh H Olmstead AR Aller MF Aller HD McHardy IM Lähteenmäki A Tornikoski M Valtaoja E Hagen-Thorn VA Kopatskaya EN Gear WK Tosti G Kurtanidze O Nikolashvili M Sigua L Miller HR Ryle WT 《Nature》2008,452(7190):966-969
Blazars are the most extreme active galactic nuclei. They possess oppositely directed plasma jets emanating at near light speeds from accreting supermassive black holes. According to theoretical models, such jets are propelled by magnetic fields twisted by differential rotation of the black hole's accretion disk or inertial-frame-dragging ergosphere. The flow velocity increases outward along the jet in an acceleration and collimation zone containing a coiled magnetic field. Detailed observations of outbursts of electromagnetic radiation, for which blazars are famous, can potentially probe the zone. It has hitherto not been possible to either specify the location of the outbursts or verify the general picture of jet formation. Here we report sequences of high-resolution radio images and optical polarization measurements of the blazar BL Lacertae. The data reveal a bright feature in the jet that causes a double flare of radiation from optical frequencies to TeV gamma-ray energies, as well as a delayed outburst at radio wavelengths. We conclude that the event starts in a region with a helical magnetic field that we identify with the acceleration and collimation zone predicted by the theories. The feature brightens again when it crosses a standing shock wave corresponding to the bright 'core' seen on the images. 相似文献
57.
Why fishing magnifies fluctuations in fish abundance 总被引:1,自引:0,他引:1
Anderson CN Hsieh CH Sandin SA Hewitt R Hollowed A Beddington J May RM Sugihara G 《Nature》2008,452(7189):835-839
It is now clear that fished populations can fluctuate more than unharvested stocks. However, it is not clear why. Here we distinguish among three major competing mechanisms for this phenomenon, by using the 50-year California Cooperative Oceanic Fisheries Investigations (CalCOFI) larval fish record. First, variable fishing pressure directly increases variability in exploited populations. Second, commercial fishing can decrease the average body size and age of a stock, causing the truncated population to track environmental fluctuations directly. Third, age-truncated or juvenescent populations have increasingly unstable population dynamics because of changing demographic parameters such as intrinsic growth rates. We find no evidence for the first hypothesis, limited evidence for the second and strong evidence for the third. Therefore, in California Current fisheries, increased temporal variability in the population does not arise from variable exploitation, nor does it reflect direct environmental tracking. More fundamentally, it arises from increased instability in dynamics. This finding has implications for resource management as an empirical example of how selective harvesting can alter the basic dynamics of exploited populations, and lead to unstable booms and busts that can precede systematic declines in stock levels. 相似文献
58.
Romeo S Pennacchio LA Fu Y Boerwinkle E Tybjaerg-Hansen A Hobbs HH Cohen JC 《Nature genetics》2007,39(4):513-516
Resequencing genes provides the opportunity to assess the full spectrum of variants that influence complex traits. Here we report the first application of resequencing to a large population (n = 3,551) to examine the role of the adipokine ANGPTL4 in lipid metabolism. Nonsynonymous variants in ANGPTL4 were more prevalent in individuals with triglyceride levels in the lowest quartile than in individuals with levels in the highest quartile (P = 0.016). One variant (E40K), present in approximately 3% of European Americans, was associated with significantly lower plasma levels of triglyceride and higher levels of high-density lipoprotein cholesterol in European Americans from the Atherosclerosis Risk in Communities Study and in Danes from the Copenhagen City Heart Study. The ratio of nonsynonymous to synonymous variants was higher in European Americans than in African Americans (4:1 versus 1.3:1), suggesting population-specific relaxation of purifying selection. Thus, resequencing of ANGPTL4 in a multiethnic population allowed analysis of the phenotypic effects of both rare and common variants while taking advantage of genetic variation arising from ethnic differences in population history. 相似文献
59.
Mutations in amphiphysin 2 (BIN1) disrupt interaction with dynamin 2 and cause autosomal recessive centronuclear myopathy 总被引:4,自引:0,他引:4
Nicot AS Toussaint A Tosch V Kretz C Wallgren-Pettersson C Iwarsson E Kingston H Garnier JM Biancalana V Oldfors A Mandel JL Laporte J 《Nature genetics》2007,39(9):1134-1139
Centronuclear myopathies are characterized by muscle weakness and abnormal centralization of nuclei in muscle fibers not secondary to regeneration. The severe neonatal X-linked form (myotubular myopathy) is due to mutations in the phosphoinositide phosphatase myotubularin (MTM1), whereas mutations in dynamin 2 (DNM2) have been found in some autosomal dominant cases. By direct sequencing of functional candidate genes, we identified homozygous mutations in amphiphysin 2 (BIN1) in three families with autosomal recessive inheritance. Two missense mutations affecting the BAR (Bin1/amphiphysin/RVS167) domain disrupt its membrane tubulation properties in transfected cells, and a partial truncation of the C-terminal SH3 domain abrogates the interaction with DNM2 and its recruitment to the membrane tubules. Our results suggest that mutations in BIN1 cause centronuclear myopathy by interfering with remodeling of T tubules and/or endocytic membranes, and that the functional interaction between BIN1 and DNM2 is necessary for normal muscle function and positioning of nuclei. 相似文献