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Chaudhari N, Strutton PH, Wickham AJ, McGregor AH, Mullington CJ. Heat stress associated with aerosol PPE and its impact. Occup Med (Lond) 2023; 73:120-127. [PMID: 36282602 PMCID: PMC10132207 DOI: 10.1093/occmed/kqac114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Aerosol personal protective equipment (PPE) is subjectively reported to negatively impact healthcare workers' performance and well-being, but this has not been assessed objectively. AIMS This randomized controlled crossover study aimed to quantify the heat stress associated with aerosol PPE and to investigate its impact upon mood, cognitive and motor function, and task performance. METHODS Sixteen healthy, young, lean participants (eight males) undertook an exercise protocol, which simulated the metabolic expenditure of hospital work: once wearing aerosol PPE (PPE visit) and once wearing standard surgical attire (control visit). Participants walked on a treadmill for 2 h followed by 30-min rest. Core temperature, heart rate, urine specific gravity, weight, grip strength, mood (Bond-Lader scale) and task performance (Intubation of a Manikin) were recorded. Values are between-visit mean (standard deviation) differences. RESULTS On the PPE visit core temperature (+0.2 (0.3)°C; P < 0.01), heart rate (+12 (13) bpm; P < 0.001), urine specific gravity (+0.003 (0.005); P < 0.05) and intubation task time (+50 (81) s; P < 0.01) were greater than on the control visit; and alertness (-14 (21) mm; P < 0.001), contentment (-14 (15) mm; P < 0.001) and grip strength (-4 (4) N; P < 0.01) were less. CONCLUSIONS This study demonstrates that wearing aerosol PPE in a simulated hospital environment results in heat exhaustion and has a negative impact upon mood, motor function, and task performance. Whilst wearing PPE is important to prevent disease transmission, strategies should be developed to limit its impact upon healthcare workers' performance and well-being.
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Affiliation(s)
- N Chaudhari
- MSk Lab, Imperial College London, London W12 0BZ, UK
| | - P H Strutton
- MSk Lab, Imperial College London, London W12 0BZ, UK
| | - A J Wickham
- Theatres and Anaesthesia, Imperial College Healthcare NHS Trust, London W2 1NY, UK
| | - A H McGregor
- MSk Lab, Imperial College London, London W12 0BZ, UK
| | - C J Mullington
- MSk Lab, Imperial College London, London W12 0BZ, UK
- Theatres and Anaesthesia, Imperial College Healthcare NHS Trust, London W2 1NY, UK
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2
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Chai H, Chaudhari N, Kornhaber R, Cuttle L, Fear M, Wood F, Martin L. Chemical burn to the skin: A systematic review of first aid impacts on clinical outcomes. Burns 2022; 48:1527-1543. [DOI: 10.1016/j.burns.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/09/2022] [Indexed: 11/02/2022]
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Lawler NB, Evans CW, Romanenko S, Chaudhari N, Fear M, Wood F, Smith NM, Wallace VP, Swaminathan Iyer K. Millimeter waves alter DNA secondary structures and modulate the transcriptome in human fibroblasts. Biomed Opt Express 2022; 13:3131-3144. [PMID: 35774325 PMCID: PMC9203081 DOI: 10.1364/boe.458478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/14/2022] [Accepted: 04/14/2022] [Indexed: 05/08/2023]
Abstract
As millimetre wave (MMW) frequencies of the electromagnetic spectrum are increasingly adopted in modern technologies such as mobile communications and networking, characterising the biological effects is critical in determining safe exposure levels. We study the exposure of primary human dermal fibroblasts to MMWs, finding MMWs trigger genomic and transcriptomic alterations. In particular, repeated 60 GHz, 2.6 mW cm-2, 46.8 J cm-2 d-1 MMW doses induce a unique physiological response after 2 and 4 days exposure. We show that high dose MMWs induce simultaneous non-thermal alterations to the transcriptome and DNA structural dynamics, including formation of G-quadruplex and i-motif secondary structures, but not DNA damage.
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Affiliation(s)
- Nicholas B Lawler
- Department of Physics, The University of Western Australia, Perth, WA 6009, Australia
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Cameron W Evans
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Sergii Romanenko
- Department of Sensory Signaling, O.O. Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, 01601, Ukraine
| | - Nutan Chaudhari
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Mark Fear
- Burn Injury Research Unit, School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia
| | - Fiona Wood
- Fiona Stanley and Princess Margaret Hospitals, Burns Service of Western Australia, Perth, WA, Australia
| | - Nicole M Smith
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Vincent P Wallace
- Department of Physics, The University of Western Australia, Perth, WA 6009, Australia
| | - K Swaminathan Iyer
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
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4
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Alghamdi MA, AL-Eitan LN, Stevenson A, Chaudhari N, Hortin N, Wallace HJ, Danielsen PL, Manzur M, Wood FM, Fear MW. Secreted Factors from Keloid Keratinocytes Modulate Collagen Deposition by Fibroblasts from Normal and Fibrotic Tissue: A Pilot Study. Biomedicines 2020; 8:biomedicines8070200. [PMID: 32650468 PMCID: PMC7400315 DOI: 10.3390/biomedicines8070200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 12/03/2022] Open
Abstract
Interactions between keratinocytes and fibroblasts in the skin layers are crucial in normal tissue development, wound healing, and scarring. This study has investigated the role of keloid keratinocytes in regulating collagen production by primary fibroblasts in vitro. Keloid cells were obtained from removed patients’ tissue whereas normal skin cells were discarded tissue obtained from elective surgery procedures. Fibroblasts and keratinocytes were isolated, cultured, and a transwell co-culture system were used to investigate the effect of keratinocytes on collagen production using a ‘scar-in-a-jar’ model. Keloid fibroblasts produced significantly more collagen than normal skin fibroblasts in monoculture at the RNA, secreted protein, and stable fibrillar protein level. When keloid keratinocytes were added to normal skin fibroblasts, expression of collagen was significantly upregulated in most samples, but when added to keloid fibroblasts, collagen I production was significantly reduced. Interestingly, keloid keratinocytes appear to decrease collagen production by keloid fibroblasts. This suggests that signaling in both keratinocytes and fibroblasts is disrupted in keloid pathology.
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Affiliation(s)
- Mansour A. Alghamdi
- Department of Anatomy, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia;
- Genomics and Personalized Medicine Unit, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia
| | - Laith N. AL-Eitan
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan;
- Department of Biotechnology and Genetic Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Andrew Stevenson
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
| | - Nutan Chaudhari
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
| | - Nicole Hortin
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
| | - Hilary J. Wallace
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
- School of Medicine, The University of Notre Dame Australia, Fremantle 6959, Australia
| | - Patricia L. Danielsen
- Department of Dermatology and Copenhagen Wound Healing Center, Copenhagen University Hospital, DK-2400 Copenhagen NV, Denmark;
| | - Mitali Manzur
- Telethon Kids Institute, Perth Children’s Hospital, The University of Western Australia, Nedlands 6009, Australia;
| | - Fiona M. Wood
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
- Burns Service of Western Australia, Perth Children’s Hospital and Fiona Stanley Hospital, Department of Health, Perth 6009, Australia
- Fiona Wood Foundation, Fiona Stanley Hospital, Murdoch, Perth 6150, Australia
| | - Mark W. Fear
- Burn Injury Research Unit, School of Biomedical Sciences, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; (A.S.); (N.C.); (N.H.); (H.J.W.); (F.M.W.)
- Correspondence:
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5
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Clemons TD, Singh R, Sorolla A, Chaudhari N, Hubbard A, Iyer KS. Distinction Between Active and Passive Targeting of Nanoparticles Dictate Their Overall Therapeutic Efficacy. Langmuir 2018; 34:15343-15349. [PMID: 30441895 DOI: 10.1021/acs.langmuir.8b02946] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The role of nanoparticles in cancer medicine is vast with debate still surrounding the distinction between therapeutic efficacy of actively targeted nanoparticles versus passively targeted systems for drug delivery. While it is commonly accepted that methodologies that result in homing a high concentration of drug loaded nanoparticles to the tumor is beneficial, the role of intracellular trafficking of these nanoparticles in dictating the overall therapeutic outcome remains unresolved. Herein we demonstrate that the therapeutic outcome of drug loaded nanoparticles is governed beyond simply enabling nanoparticle internalization in cells. Using two model polymeric nanoparticles, one decorated with the GE11 peptide for active targeting of the epidermal growth factor receptor (EGFR) and the other without, we demonstrate that EGFR mediated intracellular internalization results in an enhanced therapeutic effect compared to the nontargeted formulation. Our findings demonstrate that the intracellular destination of nanoparticles beyond its ability to internalize is an important parameter that has to be accounted for in the design of targeted drug delivery systems.
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Affiliation(s)
- Tristan D Clemons
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , Western Australia Australia , 6009
| | - Ruhani Singh
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , Western Australia Australia , 6009
- CSIRO Manufacturing , New Horizons Centre , 20 Research Way , Clayton , Victoria Australia 3168
| | - Anabel Sorolla
- Harry Perkins Institute of Medical Research , 6 Verdun Street , Nedlands , Western Australia Australia 6009
| | - Nutan Chaudhari
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , Western Australia Australia , 6009
| | - Alysia Hubbard
- Centre for Microscopy, Characterisation and Analysis , University of Western Australia , 35 Stirling Highway , Crawley , Western Australia Australia , 6009
| | - K Swaminatha Iyer
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , Western Australia Australia , 6009
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6
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Chaudhari N, Toshniwal P, Clemons T, Stevenson A, Ryan E, Jarolimek W, Wood F, Fear M. 527 Targeting Lysyl Oxidase (LOX) Activity to Improve Scar Appearance. J Burn Care Res 2018. [DOI: 10.1093/jbcr/iry006.450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- N Chaudhari
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - P Toshniwal
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - T Clemons
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - A Stevenson
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - E Ryan
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - W Jarolimek
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - F Wood
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
| | - M Fear
- University of Western Australia, Crawley, Australia; Pharmaxis Ltd, Sydney, Australia; burns service Western Australia, Murdoch, Australia
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7
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Clemons TD, Bradshaw M, Toshniwal P, Chaudhari N, Stevenson AW, Lynch J, Fear M, Wood FM, Iyer KS. Coherency image analysis to quantify collagen architecture: implications in scar assessment. RSC Adv 2018; 8:9661-9669. [PMID: 35540841 PMCID: PMC9078703 DOI: 10.1039/c7ra12693j] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/27/2018] [Indexed: 11/21/2022] Open
Abstract
A novel technique for the fast and robust quantification of collagen architecture following scarring.
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Affiliation(s)
- T. D. Clemons
- School of Molecular Sciences M313
- The University of Western Australia
- Crawley
- Australia
| | - M. Bradshaw
- School of Molecular Sciences M313
- The University of Western Australia
- Crawley
- Australia
| | - P. Toshniwal
- School of Molecular Sciences M313
- The University of Western Australia
- Crawley
- Australia
| | - N. Chaudhari
- School of Molecular Sciences M313
- The University of Western Australia
- Crawley
- Australia
| | - A. W. Stevenson
- Fiona Wood Foundation and Burn Injury Research Unit
- The University of Western Australia, M318
- Crawley
- Australia
| | - J. Lynch
- Fiona Wood Foundation and Burn Injury Research Unit
- The University of Western Australia, M318
- Crawley
- Australia
- Royal College of Surgeon's of Ireland
| | - M. W. Fear
- Fiona Wood Foundation and Burn Injury Research Unit
- The University of Western Australia, M318
- Crawley
- Australia
| | - F. M. Wood
- Fiona Wood Foundation and Burn Injury Research Unit
- The University of Western Australia, M318
- Crawley
- Australia
| | - K. Swaminathan Iyer
- School of Molecular Sciences M313
- The University of Western Australia
- Crawley
- Australia
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8
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Modi L, Suthar B, Chaudhari C, Chaudhari N, Nakhashi H, Modi F. Trace minerals profile of blood serum and estrual mucus in repeat breeder Kankrej cows. Vet World 2013. [DOI: 10.5455/vetworld.2013.143-146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Chaudhari C, Suthar B, Sharma V, Dabas V, Chaudhari N, Panchasara H. Estrus induction and fertility response in delayed pubertal Kankrej heifers treated with norgestomet ear implant. Vet World 2012. [DOI: 10.5455/vetworld.2012.453-458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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10
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Affiliation(s)
- N Chaudhari
- Department of Physiology and Biophysics, and Neuroscience Program, University of Miami School of Medicine, 33101, Miami, FL, USA
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Abstract
Sensory transduction for many taste stimuli such as sugars, some bitter compounds and amino acids is thought to be mediated via G protein-coupled receptors (GPCRs), although no such receptors that respond to taste stimuli are yet identified. Monosodium L-glutamate (L-MSG), a natural component of many foods, is an important gustatory stimulus believed to signal dietary protein. We describe a GPCR cloned from rat taste buds and functionally expressed in CHO cells. The receptor couples negatively to a cAMP cascade and shows an unusual concentration-response relationship. The similarity of its properties to MSG taste suggests that this receptor is a taste receptor for glutamate.
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Affiliation(s)
- N Chaudhari
- Program in Neuroscience, University of Miami School of Medicine, P.O. Box 016430 (R430), Miami, Florida 33101, USA.
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12
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Yang H, Wanner IB, Roper SD, Chaudhari N. An optimized method for in situ hybridization with signal amplification that allows the detection of rare mRNAs. J Histochem Cytochem 1999; 47:431-46. [PMID: 10082745 DOI: 10.1177/002215549904700402] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In situ hybridization (ISH) using nonradioactive probes enables mRNAs to be detected with improved cell resolution but compromised sensitivity compared to ISH with radiolabeled probes. To detect rare mRNAs, we optimized several parameters for ISH using digoxygenin (DIG)-labeled probes, and adapted tyramide signal amplification (TSA) in combination with alkaline phosphatase (AP)-based visualization. This method, which we term TSA-AP, achieves the high sensitivity normally associated with radioactive probes but with the cell resolution of chromogenic ISH. Unlike published protocols, long RNA probes (up to 2.61 kb) readily permeated cryosections and yielded stronger hybridization signals than hydrolyzed probes of equivalent complexity. RNase digestion after hybridization was unnecessary and led to a substantial loss of signal intensity without significantly reducing nonspecific background. Probe concentration was also a key parameter for improving signal-to-noise ratio in ISH. Using these optimized methods on rat taste tissue, we detected mRNA for mGluR4, a receptor, and transducin, a G-protein, both of which are expressed at very low abundance and are believed to be involved in chemosensory transduction. Because the effect of the tested parameters was similar for ISH on sections of brain and tongue, we believe that these methodological improvements for detecting rare mRNAs may be broadly applicable to other tissues. (J Histochem Cytochem 47:431-445, 1999)
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Affiliation(s)
- H Yang
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, Florida 33101, USA
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13
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Abstract
Recent molecular analyses have demonstrated that a metabotropic glutamate receptor, mGluR4, is expressed in taste buds from rat circumvallate and foliate papillae. Behavioral studies demonstrated that L(+)-2-amino-4-phosphonobutyric acid (L-AP4), an agonist for mGluR4 and related receptors, mimics the taste of monosodium glutamate (MSG) in rats. mGluR4 is known to signal through inhibition of the cyclic adenosine-5',3'-monophosphate (cAMP) cascade. Circumvallate and foliate taste buds exhibit decreases of cAMP levels following stimulation with MSG, and the response is potentiated by 5'-inosine monophosphate, suggesting that it is related to umami taste. Further, experiments on mice with the mGluR4 gene knocked out support the interpretation that mGluR4 is a key component in glutamate taste. Glutamate may also stimulate taste buds through an ionotropic receptor pathway. In patch-clamp studies, glutamate evokes two types of currents, similar to those elicited by N-methyl-D-aspartate (NMDA) and L-AP4. We speculate upon the significance of two glutamate receptor pathways in taste buds.
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Affiliation(s)
- N Chaudhari
- Department of Physiology and Biophysics, University of Miami School of Medicine, Florida 33101, USA.
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14
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Abstract
We studied taste transduction in sensory receptor cells. Specifically, we examined the actions of glutamate, a significant taste stimulus, on the membrane properties of taste cells by applying whole cell patch-clamp techniques to cells in rat taste buds isolated from foliate and vallate papillae. In 55 of 91 taste cells, bath-applied glutamate, at concentrations that elicit taste responses in the intact animal (10-20 mM), produced one of two different responses when the cell membrane was held near its presumed resting potential, -85 mV. "Sustained" glutamate responses were observed in the majority of taste cells (51 of 55) and consisted of an outward current (reduction of the maintained inward current). Sustained glutamate responses were voltage dependent, were decreased by membrane depolarization, and were accompanied by a reduction in membrane conductance. An analysis of the reversal potential of sustained responses in different ionic conditions and the effect of ion substitutions suggested that the currents were carried by cations. The data suggest that sustained responses are mediated by the closure of nonselective cation channels. Other taste cells (4 of 55) responded to glutamate with a transient inward current--so-called "transient" responses. Transient glutamate responses were voltage dependent and Na+ dependent, and appeared to be generated by nonspecific cation channels activated by glutamate. L(+)-2-amino-4-phosphonobutyric acid (L-AP4), a specific agonist of a metabotropic glutamate receptor (mGluR4) recently identified in rat taste cells and believed to be involved in taste transduction, mimicked the sustained glutamate responses. These findings indicate that glutamate, at concentrations at or slightly above threshold for taste in rats, produces two different membrane currents. The properties of these two responses suggest that there may be two different sets of nonspecific cation channels in taste cells, one closed by glutamate (sustained response) and the other opened (transient response). Our findings on the effect of L-AP4 suggest that the sustained response is the membrane mechanism mediating, at least in part, taste transduction for glutamate.
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Affiliation(s)
- A Bigiani
- Dipartimento di Scienze Biomediche, Sezione di Fisiologia, Università di Modena, Italy
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15
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Chaudhari N, Yang H, Lamp C, Delay E, Cartford C, Than T, Roper S. The taste of monosodium glutamate: membrane receptors in taste buds. J Neurosci 1996; 16:3817-26. [PMID: 8656276 PMCID: PMC6578609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/1996] [Accepted: 03/25/1996] [Indexed: 02/01/2023] Open
Abstract
Receptor proteins for photoreception have been studied for several decades. More recently, putative receptors for olfaction have been isolated and characterized. In contrast, no receptors for taste have been identified yet by molecular cloning. This report describes experiments aimed at identifying a receptor responsible for the taste of monosodium glutamate (MSG). Using reverse transcriptase (RT)-PCR, we found that several ionotropic glutamate receptors are present in rat lingual tissues. However, these receptors also could be detected in lingual tissue devoid of taste buds. On the other hand, RT-PCR and RNase protection assays indicated that a G-protein-coupled metabotropic glutamate receptor, mGluR4, also is expressed in lingual tissues and is limited only to taste buds. In situ hybridization demonstrated that mGluR4 is detectable in 40-70% of vallate and foliate taste buds but not in surrounding nonsensory epithelium, confirming the localization of this metabotropic receptor to gustatory cells. Expression of mGluR4 in taste buds is higher in preweaning rats compared with adult rats. This may correspond to the known higher sensitivity to the taste of MSG in juvenile rodents. Finally, behavioral studies have indicated that MSG and L-2-amino-4-phosphonobutyrate (L-AP4), a ligand for mGluR4, elicit similar tastes in rats. We conclude that mGluR4 may be a chemosensory receptor responsible, in part, for the taste of MSG.
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MESH Headings
- Amino Acid Sequence
- Animals
- Chemoreceptor Cells/physiology
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Data Interpretation, Statistical
- Epithelium/chemistry
- Epithelium/physiology
- In Situ Hybridization
- Membrane Proteins/physiology
- Molecular Sequence Data
- Polymerase Chain Reaction
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Receptors, Glutamate/drug effects
- Receptors, Glutamate/physiology
- Receptors, Metabotropic Glutamate/drug effects
- Receptors, Metabotropic Glutamate/genetics
- Receptors, Metabotropic Glutamate/physiology
- Sodium Glutamate/pharmacology
- Taste/physiology
- Taste Buds/chemistry
- Taste Buds/drug effects
- Taste Buds/physiology
- Tongue/cytology
- Tongue/ultrastructure
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Ft. Collins 80523, USA
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16
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Abstract
During the early development of skeletal muscle, cardiac isotypes of several contractile proteins are known to be transiently expressed. We report here that skeletal muscle developing in vivo, as well as primary cultures derived from skeletal muscle, express mRNA encoding the cardiac dihydropyridine-sensitive calcium channel. The mRNA is detectable at high concentration at the earliest stage tested in vivo and diminishes rapidly in concentration as myofibers mature. The concentration of the cardiac calcium channel mRNA also diminishes during the in vivo development of skeletal muscle in a genetically paralyzed mouse (mdg), indicating that muscle contractile activity is not necessary for the down-regulation. In contrast, mRNA for the skeletal muscle-specific calcium channel accumulates gradually in developing skeletal muscle. A similar temporal pattern of expression is also seen in primary cultures of skeletal myotubes. These results raise the question of whether the cardiac calcium channel may be functionally important during the early development of skeletal myofibers.
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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17
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Chaudhari N. A single nucleotide deletion in the skeletal muscle-specific calcium channel transcript of muscular dysgenesis (mdg) mice. J Biol Chem 1992; 267:25636-9. [PMID: 1281468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The skeletal muscle-specific dihydropyridine-sensitive calcium channel is a critical component of excitation-contraction coupling in skeletal muscle. A recessive mutation in mice, muscular dysgenesis (mdg), has previously been described as resulting in defective excitation-contraction coupling. Although the channel-forming subunit (alpha 1) of the skeletal calcium channel is not detectable immunologically, specific mRNA of normal size is present in dysgenic muscle. cDNA for this calcium channel alpha 1 subunit has now been cloned from dysgenic muscle and sequenced in its entirety. A single nucleotide deletion occurs at nucleotide 4010 of the cDNA, resulting in a shift of the translational reading frame. The mutation has been confirmed by direct sequencing of PCR products from homozygous mutant and normal muscle. The mutant polypeptide is predicted to contain the first three repeating domains, five of the normal six transmembrane helices of the last repeating domain, and an altered and truncated C terminus. The mature mRNA encoding the dysgenic alpha 1 subunit appears to be labile. It is possible that premature termination of translation renders the mutant mRNA subject to degradation by nucleases. This work resolves a long-standing controversy on the nature of the primary genetic defect in muscular dysgenesis.
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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18
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Chaudhari N. Plasmid fragments as accurate markers for northern blots. Biotechniques 1991; 10:601, 605. [PMID: 1910774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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Abstract
Muscular dysgenesis in mice is a genetic disease of skeletal muscle caused by the recessive mutation mdg. Muscle fibres in affected mice are paralysed because of the failure of excitation-contraction coupling. Unlike normal myotubes in primary culture, dysgenic myotubes do not contract, either spontaneously or in response to electrical stimulation. The deficiency results from mutation of the gene for the skeletal muscle dihydropyridine receptor, an essential sarcolemmal component both of excitation-contraction coupling and of the slow calcium-ion channel. It has recently been shown that the addition of fibroblasts from normal (but not dysgenic) mice to cultures of dysgenic myotubes can restore spontaneous contractions in a small fraction of these myotubes, but the mechanism for this 'rescue' was not determined. In principle, if fibroblast nuclei were able to incorporate into myotubes, such nuclei could then supply the missing muscle-specific gene product. We have now investigated this possibility using nuclear, cytoplasmic and plasmalemmal markers. We report that the rescue to contractile ability in genetically paralysed dysgenic muscle is mediated by the previously unrecognized ability of fibroblasts to fuse spontaneously with developing myotubes.
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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21
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Abstract
Muscular dysgenesis (mdg) is a mutation in mice which causes the failure of excitation-contraction coupling in skeletal muscle. Although the sarcolemma, the sarcoplasmic reticulum, and the contractile apparatus all maintain nearly normal function, sarcolemmal depolarization fails to cause calcium release from the sarcoplasmic reticulum. Recently, the primary genetic defect in this mutation was shown to be located in the structural gene for the dihydropyridine receptor. We have examined the developmental expression from Fetal Day 15 onward, in normal and mutant muscle, of several unidentified genes as well as genes which are known markers of muscle differentiation. We find that the majority of mRNA sequences are found at similar concentrations in normal and dysgenic muscles at birth. Many differentiation-related genes also are expressed at normal levels early during myogenesis in mutant mice. However, as late fetal development progresses in dysgenic muscle, the mRNA concentrations for these genes fail to undergo the rapid rise which is characteristic of normal muscle. Several additional, unidentified genes, which normally would be down-regulated during development, remain expressed at a high level in dysgenic muscle. Thus, the primary absence of a functional dihydropyridine receptor appears to prevent the changes in gene expression which are necessary for maturation of skeletal muscle.
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Affiliation(s)
- N Chaudhari
- Department of Physiology, Colorado State University, Fort Collins 80523
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22
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Knudson CM, Chaudhari N, Sharp AH, Powell JA, Beam KG, Campbell KP. Specific absence of the alpha 1 subunit of the dihydropyridine receptor in mice with muscular dysgenesis. J Biol Chem 1989; 264:1345-8. [PMID: 2536362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Muscular dysgenesis is a lethal mutation in mice that results in a complete absence of skeletal muscle contraction due to the failure of depolarization of the transverse tubular membrane to trigger calcium release from the sarcoplasmic reticulum. In order to determine whether the defect in muscular dysgenesis leads to a specific loss of one of the components of excitation-contraction coupling or to a generalized loss of all components of excitation-contraction coupling, we have analyzed skeletal muscle from control and dysgenic mice for the sarcoplasmic reticulum and transverse tubular proteins which are believe to function in excitation-contraction coupling. We report that the proteins involved in sarcoplasmic reticulum calcium transport, storage, and release [Ca2+ + Mg2+)-ATPase, calsequestrin, and calcium release channel) are present in dysgenic muscle. Also present in dysgenic muscle is the 175/150-kDa glycoprotein subunit (alpha 2) of the dihydropyridine receptor. However, the 170-kDa dihydropyridine binding subunit (alpha 1) of the dihydropyridine receptor is absent in dysgenic muscle. These results suggest that the specific absence of the alpha 1 subunit of the dihydropyridine receptor is responsible for the defects in muscular dysgenesis and that the alpha 1 subunit of the dihydropyridine receptor is essential for excitation-contraction coupling in skeletal muscle.
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Affiliation(s)
- C M Knudson
- Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City 52242
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23
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Knudson CM, Chaudhari N, Sharp AH, Powell JA, Beam KG, Campbell KP. Specific Absence of the α1 Subunit of the Dihydropyridine Receptor in Mice with Muscular Dysgenesis. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94191-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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24
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Liu L, Chaudhari N, Corle D, Sherins RJ. Comparison of pulsatile subcutaneous gonadotropin-releasing hormone and exogenous gonadotropins in the treatment of men with isolated hypogonadotropic hypogonadism. Fertil Steril 1988; 49:302-8. [PMID: 3123278 DOI: 10.1016/s0015-0282(16)59720-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eight men with isolated hypogonadotropic hypogonadism were treated with pulsatile gonadotropin-releasing hormone (GnRH) after maximal testicular growth and function had already been achieved with human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG). Only four subjects could normalize plasma testosterone (T) levels (group A). After 18 months of GnRH therapy, testicular size of group A increased by 53% (P less than 0.01) over that previously attained with exogenous gonadotropins. However, despite further testicular growth, two men who were previously azoospermic on hCG/hMG remained so on GnRH. In the other two patients, total sperm count increased minimally. Thus, pulsatile gonadotropin levels achieved with GnRH are more effective in stimulating testicular growth, but not necessarily sperm output, than are stable gonadotropin concentrations obtained with hCG/hMG.
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Affiliation(s)
- L Liu
- Developmental Endocrinology Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892
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25
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Owens GP, Chaudhari N, Hahn WE. Response
: Brain "Identifier Sequence". Science 1986; 234:1006. [PMID: 17771341 DOI: 10.1126/science.234.4779.1006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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26
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Abstract
A repeated 82 base pair sequence in genomic DNA of the rat was previously proposed as being a control element governing brain (neuron) specific genetic expression. This intronic sequence, termed the brain "identifier" (ID), is complementary to small RNA species localized in brain cytoplasm, and it was thought to be represented specifically in RNA produced by brain nuclei in vitro. The RNA blot analyses of total nuclear and polyadenylated heterogeneous nuclear RNA described in the present report show that this ID sequence is also present in the liver and kidney in abundances similar to those in the brain. This repeated sequence is not, therefore, restricted to transcripts produced in the brain as suggested from previous transcriptional "runoff" experiments. Measurements on rat and mouse nuclear RNA indicate that the abundance of ID sequence transcript is roughly proportional to the number of copies of this repeat in the respective genomes. This suggests a rather random genomic location and transcription of this sequence. From these results it seems improbable that the ID sequence functions as a transcriptional-level control element in genes expressed specifically in the brain.
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Abstract
The adult mouse brain contains complex populations of polyadenylated [poly(A)+] and nonpolyadenylated [poly(A)-] messenger RNA's (mRNA's). These mRNA's are separate sequence populations, similar in complexity, and in combination are equivalent to approximately 150,000 different mRNA sequences, of average length. Essentially all of the "adult" poly(A)+ mRNA's are present in the brain at birth. In contrast, most of the poly(A)- mRNA's are absent. Brain poly(A)- mRNA's begin to appear soon after birth, but the full adult complement is not reached until young adulthood. This suggests that these poly(A)- mRNA's specify proteins required for the biological capabilities of the brain that emerge during the course of postnatal development.
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Hahn W, Chaudhari N, Beck L. Activation of genes during postnatal development of the brain. Int J Dev Neurosci 1983. [DOI: 10.1016/0736-5748(83)90216-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- W.E. Hahn
- University of Colorado School of Medicine; Department of Anatomy; 4200 E. 9th Ave. Denver Colorado 80262 U.S.A
| | - N. Chaudhari
- University of Colorado School of Medicine; Department of Anatomy; 4200 E. 9th Ave. Denver Colorado 80262 U.S.A
| | - L. Beck
- University of Colorado School of Medicine; Department of Anatomy; 4200 E. 9th Ave. Denver Colorado 80262 U.S.A
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Hahn WE, Chaudhari N, Beck L, Wilber K, Peffley D. Genetic expression and postnatal development of the brain: some characteristics of nonpolyadenylated mRNAs. Cold Spring Harb Symp Quant Biol 1983; 48 Pt 2:465-75. [PMID: 6202453 DOI: 10.1101/sqb.1983.048.01.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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31
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Abstract
In keeping with earlier reports, we have found that reassociated long repeat DNA from sea urchins is thermostable, indicating the absence of evolutionarily diverged families of repeated sequences. However, we found that when fragments of radiolabeled long repeat DNA were denatured and reassociated with intact long repeat driver DNA, then sheared to 350 basepairs and assayed for thermal stability, the level of mismatch found in the duplexes varied inversely with the length of the starting fragments. This effect was shown to be due directly to the physical size of the molecules involved in reassociation. These results are consistent with, and support a model for, long repeat DNA in which short units of repetition are arranged in precise arrays. The significance of this arrangement of sequence units within long repeat DNA is discussed.
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32
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Craig SP, Chaudhari N, Steinert M. Characterization of long and short repetitive sequences in the sea urchin genome. Biochim Biophys Acta 1979; 565:33-50. [PMID: 508764 DOI: 10.1016/0005-2787(79)90081-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Long and short repetitive sequences were purified from the DNA of Paracentrotus lividus under conditions designed to optimize the yield of complete, end to end sequences. Double-stranded long repeat DNA prepared in this manner ranged in length from approximately 3000 to 15 000 nucleotide pairs with average sizes of approximately 6000 base pairs. In the electron microscope, long repeat DNA was observed to possess continuous sequences that often appeared to be terminated by one or more loops and/or fold backs. Long repeat DNA sequences, resheared to 300 base pairs, were found to have an average melting point identical to that for sheared native DNA. Thus, the reassociated duplexes of long repetitive DNA seem to possess very few mismatched base pairs. Reassociation kinetic analyses indicate that the majority of the long repeat sequences are reiterated only 4--7 times per haploid amount of DNA. Melt-reassociation analyses of short repetitive DNA, at several criteria, support the previously held concept that these sequences belong the sets or families of sequences which are inexact copies of one another. Our studies also support hypotheses suggesting that short repetitive sequences belong to families which may have arisen via distinct salttatory events. The relationships between long and short repetitive DNA sequences are considered with respect to widely held concepts of their sequence organization, evolution, and possible functions within eucaryotic genomes. A model for the possible organization of short repeats within long repetitive DNA sequences is also presented.
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Abstract
The rates of evolution of purified long and short repetitive DNA sequences were examined by hybridisation analysis between the DNAs from several species of sea urchins. We find that the rates of nucleotide substitution are very comparable within mutually retained sequences for the two classes of repetitive DNA. The loss of hybridisable sequences between species also occurs at similar rates among both the short and long repetitive DNA sequences. Between species that separated less than 50 million years ago, hybridisable short repetitive sequences are lost all through the spectrum of reiteration frequencies. The long repeats contain a few sequences which are highly conserved within all of the species examined, and which amount to approximately 1% of the total genome. The short repetitive class, on the other hand, does not seem to contain any such highly conserved elements. The long repetitive sequences internally appear to contain short 'units' of reiteration, which may comprise families within the long repetitive class. We find no evidence to indicate that the majority of long and short repetitive sequences evolve by different mechanisms or at different rates.
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