Abstract:
:Many urological studies rely on models of animals, such as rats and pigs, but their relation to the human urinary system is poorly understood. Here, we elucidate the hydrodynamics of urination across five orders of magnitude in body mass. Using high-speed videography and flow-rate measurement obtained at Zoo Atlanta, we discover that all mammals above 3 kg in weight empty their bladders over nearly constant duration of 21 ± 13 s. This feat is possible, because larger animals have longer urethras and thus, higher gravitational force and higher flow speed. Smaller mammals are challenged during urination by high viscous and capillary forces that limit their urine to single drops. Our findings reveal that the urethra is a flow-enhancing device, enabling the urinary system to be scaled up by a factor of 3,600 in volume without compromising its function. This study may help to diagnose urinary problems in animals as well as inspire the design of scalable hydrodynamic systems based on those in nature.
journal_name
Proc Natl Acad Sci U S Aauthors
Yang PJ,Pham J,Choo J,Hu DLdoi
10.1073/pnas.1402289111subject
Has Abstractpub_date
2014-08-19 00:00:00pages
11932-7issue
33eissn
0027-8424issn
1091-6490pii
1402289111journal_volume
111pub_type
杂志文章abstract::The empirical criteria for defining a clinical subtype of lung cancer are gradually transiting from histopathology to genetic variations in driver genes. Targeting these driver mutations, such as sensitizing epidermal growth factor receptor (EGFR) mutations, has dramatically improved the prognosis of advanced non-smal...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1510837112
更新日期:2015-08-11 00:00:00
abstract::A 43-kDa peripheral membrane protein is known to copurify with acetylcholine receptor (AcChoR)-rich membranes isolated from the electric organ of Torpedo californica. Immunoelectron microscopy and crosslinking studies have demonstrated that this 43-kDa protein is closely associated with the cytoplasmic domain(s) of th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.23.8270
更新日期:1985-12-01 00:00:00
abstract::The presence of nerve growth factor (NGF) mRNA and protein in the rat central nervous system is documented. Blot-hybridization analysis showed an abundance of NGF mRNA in the hippocampus, cerebral cortex, and olfactory bulb. Enzyme immunoassay confirmed significant levels of a NGF-like protein in the hippocampus and c...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.3.817
更新日期:1986-02-01 00:00:00
abstract::To monitor inaccuracy in gene expression in living cells, we designed an experimental system in the bacterium Bacillus subtilis whereby spontaneous errors can be visualized and quantified at a single-cell level. Our strategy was to introduce mutations into a chromosomally encoded gfp allele, such that errors in protei...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0912989107
更新日期:2010-06-22 00:00:00
abstract::Bacterial populations are subject to complex processes of diversification that involve mutation and horizontal DNA transfer mediated by transformation, transduction, or conjugation. Tracing the evolutionary events leading to genetic changes allows us to infer the history of a microbe. Here, we combine experimental and...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0803654105
更新日期:2008-10-14 00:00:00
abstract::The mammalian form of the protozoan parasite Leishmania mexicana contains high activity of a cysteine proteinase (LmCPb) encoded on a tandem array of 19 genes (lmcpb). Homozygous null mutants for lmcpb have been produced by targeted gene disruption. All life-cycle stages of the mutant can be cultured in vitro, demonst...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.93.12.6008
更新日期:1996-06-11 00:00:00
abstract::Sinuous patterns traced by fluid flows are a ubiquitous feature of physical landscapes on Earth, Mars, the volcanic floodplains of the Moon and Venus, and other planetary bodies. Typically discussed as a consequence of migration processes in meandering rivers, sinuosity is also expressed in channel types that show lit...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1214074110
更新日期:2013-05-21 00:00:00
abstract::The Millennium Ecosystem Assessment (MA) introduced a new framework for analyzing social-ecological systems that has had wide influence in the policy and scientific communities. Studies after the MA are taking up new challenges in the basic science needed to assess, project, and manage flows of ecosystem services and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0808772106
更新日期:2009-02-03 00:00:00
abstract::The boreal forests, identified as a critical "tipping element" of the Earth's climate system, play a critical role in the global carbon budget. Recent findings have suggested that terrestrial carbon sinks in northern high-latitude regions are weakening, but there has been little observational evidence to support the i...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1111576109
更新日期:2012-02-14 00:00:00
abstract::We used a sensitive and specific cDNA polymerase chain reaction assay to detect hepatitis C virus (HCV) RNA in serum samples from 128 unselected southern African Blacks with hepatocellular carcinoma (HCC) and found HCV RNA in 26 (20.3%) of these patients. Antibodies to HCV (anti-HCV) were detected in 59 patients (46.1...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.5.1848
更新日期:1993-03-01 00:00:00
abstract::13C-labeled precorrin-6x is biosynthesized by cell-free protein preparations from Pseudomonas denitrificans in separate experiments using delta-amino[5-13C]levulinic acid and the corresponding delta-amino[4-13C]- and delta-amino[3-13C]levulinic acid-labeled forms in conjunction with S-[methyl-13C]adenosylmethionine fo...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.22.8800
更新日期:1990-11-01 00:00:00
abstract::The combination of catalytic amounts of optically active dipyridylphosphine and CuF(2) along with hydride donor PhSiH(3) generated in situ a remarkably reactive catalyst system (substrate-to-ligand molar ratio up to 100,000) for the highly enantioselective hydrosilylation of a broad spectrum of aryl alkyl ketones (up ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0409043102
更新日期:2005-03-08 00:00:00
abstract::Toll-like receptor 3 (TLR3) is a key effector of the innate immune system against viruses. Activation of TLR3 exerts an antitumoral effect through a mechanism of action still poorly understood. Here we show that TLR3 activation by polyinosinic:polycytidylic acid induces up-regulation of microRNA-29b, -29c, -148b, and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1304610110
更新日期:2013-06-11 00:00:00
abstract::Surface Ig (sIg) of follicular lymphoma (FL) is vital for tumor cell survival. We found previously that the Ig in FL is unusual, because the variable region genes carry sequence motifs for N-glycan addition. These are introduced by somatic mutation and are tumor specific. Unexpectedly, added glycans terminate at high ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1009388107
更新日期:2010-10-26 00:00:00
abstract::The intracellular levels of many proteins are regulated by ubiquitin-dependent proteolysis. One of the best-characterized enzymes that catalyzes the attachment of ubiquitin to proteins is a ubiquitin ligase complex, Skp1-Cullin-F box complex containing Hrt1 (SCF). We sought to artificially target a protein to the SCF ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.141230798
更新日期:2001-07-17 00:00:00
abstract::Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut mic...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1521741113
更新日期:2016-08-23 00:00:00
abstract::Gene function is typically evaluated by sampling the continuum of gene expression at only a few discrete points corresponding to gene knockout or overexpression. We argue that this characterization is incomplete and present a library of engineered promoters of varying strengths obtained through mutagenesis of a consti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0504604102
更新日期:2005-09-06 00:00:00
abstract::Diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein (or contre lumière) can be studied most reliably from above the earth's atmosphere with equipment flown in artificial satellites. We review the techniques used and some of the difficulties encountered ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.69.3.694
更新日期:1972-03-01 00:00:00
abstract::The spleen from a patient with adult Gaucher's disease was shown to be deficient in a beta-glucosidase (EC 3.2.1.21) isoenzyme that has optimal activity at pH 4.0-4.3, and is stimulated by 0.02% Triton X-100. A mixture of spleen homogenates from a control and from the patient contained beta-glucosidase activity equiva...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.68.11.2810
更新日期:1971-11-01 00:00:00
abstract::A three-plasmid system for heterologous expression of 6-deoxyerythronolide B synthase (DEBS) has been developed to facilitate combinatorial biosynthesis of polyketides made by type I modular polyketide synthases (PKSs). The eryA PKS genes encoding the three DEBS subunits were individually cloned into three compatible ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.21.11740
更新日期:1999-10-12 00:00:00
abstract::Although neurotrophins are primarily associated with long-term effects on neuronal survival and differentiation, recent studies have shown that acute changes in synaptic transmission can also be produced. In the hippocampus, an area critically involved in learning and memory, we have found that brain-derived neurotrop...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.17.8074
更新日期:1995-08-15 00:00:00
abstract::The early simian virus 40 (SV40) gene product, large tumor (T) antigen, is responsible for the initiation of viral DNA replication and the autoregulation of early gene expression through direct protein-DNA interactions. We investigated the role of T antigen in late viral gene expression, independent of its function in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.7.2040
更新日期:1984-04-01 00:00:00
abstract::[Ala3-15N][Val1]Gramicidin A has been prepared by solid-phase peptide synthesis and studied by solid-state 15N nuclear magnetic resonance spectroscopy. The synthesis of desformyl[Ala3-15N][Val1]gramicidin A employed N-hydroxysuccinimide esters of 9-fluorenylmethoxycarbonyl-N alpha-amino acids and completely avoided th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.5.1384
更新日期:1988-03-01 00:00:00
abstract::Branching morphogenesis in the mammary gland is achieved by the migration of epithelial cells through a microenvironment consisting of stromal cells and extracellular matrix (ECM). Here we show that galectin-1 (Gal-1), an endogenous lectin that recognizes glycans bearing N-acetyllactosamine (LacNAc) epitopes, induces ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1609135113
更新日期:2016-08-16 00:00:00
abstract::The DNA origami method permits folding of long single-stranded DNA into complex 3D structures with subnanometer precision. Transmission electron microscopy, atomic force microscopy, and recently cryo-EM tomography have been used to characterize the properties of such DNA origami objects, however their microscopic stru...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1316521110
更新日期:2013-12-10 00:00:00
abstract::Phototropin is a blue light photoreceptor for tropic responses, relocation of chloroplasts, and stomata opening in plants. Phototropin has two chromophoric domains named light-oxygen-voltage-sensing (LOV) 1 and 2 in the N-terminal half, and a serine/threonine (Ser/Thr) protein kinase motif in the C-terminal half. Conc...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0506402102
更新日期:2005-09-13 00:00:00
abstract::The introduction of foreign genes into early mouse embryos and embryonic stem (ES) cells is invaluable for the analysis of gene function and regulation in the living animal. The use of vectors derived from retroviruses as gene transfer vehicles in this setting has had limited success because of silencing of transgene ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.251682798
更新日期:2002-02-19 00:00:00
abstract::Telomeric repeat-containing RNA (referred to as TERRA), a noncoding RNA molecule, has recently been found in mammalian cells. The detailed structural features and function of the TERRA RNA at human chromosome ends remain unclear, although this RNA molecule may be a key component of the telomere machinery. In the prese...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1001177107
更新日期:2010-08-17 00:00:00
abstract::Male oriental fruit flies (Dacus dorsalis) from colonies in Taiwan and Hawaii were evaluated for limit of response to various analogues of methyl eugenol. The results are interpreted in terms of the geometry and allosteric requirements of the antennal receptor that triggers the characteristic methyl eugenol reflex. Th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.76.4.1561
更新日期:1979-04-01 00:00:00
abstract::Vascular endothelial cells (ECs) sense and respond to hemodynamic shear stress, which is critical for circulatory homeostasis and the pathophysiology of vascular diseases. The mechanisms of shear stress mechanotransduction, however, remain elusive. We previously demonstrated a direct role of mitochondria in the purine...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2014029117
更新日期:2020-12-29 00:00:00