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Hall KE, James MC. Predation of satellite-tagged juvenile loggerhead turtles Caretta caretta in the Northwest Atlantic Ocean. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01165] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We present evidence of predator interactions with 8 juvenile loggerhead sea turtles Caretta caretta equipped with pop-up satellite archival transmitting tags (PSATs) following incidental capture in the Northwest Atlantic. Ingestion of PSATs occurred up to 5 mo after tagging and was identified by an abrupt change in depth distribution, a stabilization and/or increase in ambient temperature and a marked drop in light levels to near zero, with cessation of diel light level cycling. In some cases, following expulsion from the digestive tract of predators, positively buoyant PSATs descended to the sea floor or beyond the programmed release depth threshold (1800 m), indicating that they remained tethered to the indigestible carapaces of turtles and that the entire turtle was originally consumed. PSAT data, combined with the sudden termination of satellite uplinks from 2 loggerheads also equipped with platform transmitting terminals, provided additional evidence of whole-turtle predation. PSAT data indicated that both endothermic and ectothermic sharks ingested tags. Based on PSAT-logged temperature data, dive patterns and geographic distribution, the following shark species were considered as candidate predators: white, porbeagle, shortfin mako, tiger and blue. This study represents the first analysis of data collected by loggerhead turtle PSATs inside predators. The results expand the list of shark species known to prey on large juvenile loggerheads and point to the importance of acknowledging predation as an important source of mortality for loggerhead turtles in the Northwest Atlantic Ocean.
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Affiliation(s)
- KE Hall
- Population Ecology Division, Fisheries and Oceans Canada, Bedford Institute of Oceanography, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
| | - MC James
- Population Ecology Division, Fisheries and Oceans Canada, Bedford Institute of Oceanography, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
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Nordstrom B, James MC, Worm B. Jellyfish distribution in space and time predicts leatherback sea turtle hot spots in the Northwest Atlantic. PLoS One 2020; 15:e0232628. [PMID: 32407338 PMCID: PMC7224493 DOI: 10.1371/journal.pone.0232628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 04/17/2020] [Indexed: 11/18/2022] Open
Abstract
Leatherback sea turtles (Dermochelys coriacea) migrate to temperate Canadian Atlantic waters to feed on gelatinous zooplankton (‘jellyfish’) every summer. However, the spatio-temporal connection between predator foraging and prey-field dynamics has not been studied at the large scales over which these migratory animals occur. We use 8903 tows of groundfish survey jellyfish bycatch data between 2006–2017 to reveal spatial jellyfish hot spots, and matched these data to satellite-telemetry leatherback data over time and space. We found highly significant overlap of jellyfish and leatherback distribution on the Scotian Shelf (r = 0.89), moderately strong correlations of jellyfish and leatherback spatial hot spots in the Gulf of St. Lawrence (r = 0.59), and strong correlations in the Bay of Fundy (r = 0.74), which supports much lower jellyfish density. Over time, jellyfish bycatch data revealed a slight northward range shift in the Gulf of St. Lawrence, consistent with gradual warming of these waters. Two-stage generalized linear modelling corroborated that sea surface temperature, year, and region were significant predictors of jellyfish biomass, suggesting a climate signal on jellyfish distribution, which may shift leatherback critical feeding habitat over time. These findings are useful in predicting dynamic habitat use for endangered leatherback turtles, and can help to anticipate large-scale changes in their distribution in response to climate-related changes in prey availability.
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Affiliation(s)
- Bethany Nordstrom
- Biology Department, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biological Sciences, University of Western Australia, Perth, Australia
- * E-mail:
| | - Michael C. James
- Population Ecology Division, Fisheries and Oceans Canada, Dartmouth, Nova Scotia, Canada
| | - Boris Worm
- Biology Department, Dalhousie University, Halifax, Nova Scotia, Canada
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James MC, May PW, Allan NL. Ab initio study of negative electron affinity from light metals on the oxygen-terminated diamond (1 1 1) surface. J Phys Condens Matter 2019; 31:295002. [PMID: 30978712 DOI: 10.1088/1361-648x/ab18ef] [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] [Indexed: 06/09/2023]
Abstract
Recent computational work has shown that light metals adsorbed onto the oxygenated diamond (1 0 0) surface have the potential to give diamond a temperature-stable negative electron affinity (NEA). Here, we use density functional theory to study three of these metals, lithium, magnesium and aluminium, on the (1 1 1) surface. We show that all three of these metals adsorbed onto the ketone O-terminated diamond surface can possess a large NEA and adsorption energies above that of H-termination at monolayer (ML) or sub-ML coverages. Adsorption onto the ether O-terminated surface gives similarly large NEAs but lower adsorption energies. These results are promising for the development of novel NEA surfaces such as those required for thermionic devices.
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Affiliation(s)
- Michael C James
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom. HH Wills Physics Laboratory, Bristol Centre for Functional Nanomaterials, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom
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Yang T, Haas HL, Patel S, Smolowitz R, James MC, Williard AS. Blood biochemistry and haematology of migrating loggerhead turtles ( Caretta caretta) in the Northwest Atlantic: reference intervals and intra-population comparisons. Conserv Physiol 2019; 7:coy079. [PMID: 30746149 PMCID: PMC6366141 DOI: 10.1093/conphys/coy079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/06/2018] [Accepted: 01/28/2019] [Indexed: 05/28/2023]
Abstract
We documented blood biochemistry and haematology of healthy loggerhead turtles (Caretta caretta) in the Northwest (NW) Atlantic in order to establish clinical reference intervals (RIs) for this threatened population. Blood samples were analysed from migratory loggerheads captured off the Mid-Atlantic coast of the USA in 2011, 2012, 2013 and 2016 as part of a long-term research program. Blood variables were determined using a point-of-care analyser, and a veterinary diagnostic laboratory service. We calculated 95% RIs with associated 90% confidence intervals (CIs) for each blood variable. We compared results obtained from our study of migratory loggerheads with published data for similarly sized loggerheads resident at a seasonal temperate latitude foraging area. Significant differences in several blood variables between migratory and resident turtles provided insight on energetic and health status during different behavioural states. Temperature was significantly correlated with several blood variables: lactate, pCO2, sodium, haemoglobin and lactate dehydrogenase. Our assessment of blood chemistry in healthy loggerhead turtles in the NW Atlantic provides a baseline for clinical comparisons with turtles impacted by anthropogenic and environmental threats, and highlights the importance of identifying unique aspects of biochemical and haematological profiles for sea turtles at the intra-population level.
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Affiliation(s)
- Tiffany Yang
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA
| | - Heather L Haas
- National Oceanographic and Atmospheric Administration, Northeast Fisheries Science Center, Woods Hole, MA, USA
| | - Samir Patel
- Coonamessett Farm Foundation, East Falmouth, MA, USA
| | | | - Michael C James
- Fisheries and Oceans Canada, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, NS, Canada
| | - Amanda S Williard
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA
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Archibald DW, James MC. Prevalence of visible injuries to leatherback sea turtles Dermochelys coriacea in the Northwest Atlantic. ENDANGER SPECIES RES 2018. [DOI: 10.3354/esr00920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Wallace BP, Zolkewitz M, James MC. Discrete, high-latitude foraging areas are important to energy budgets and population dynamics of migratory leatherback turtles. Sci Rep 2018; 8:11017. [PMID: 30030495 PMCID: PMC6054646 DOI: 10.1038/s41598-018-29106-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 01/23/2018] [Accepted: 07/02/2018] [Indexed: 11/09/2022] Open
Abstract
Many broadly distributed migratory species exhibit fidelity to fine-scale areas that support vital life history requirements (e.g., resource acquisition, reproduction). Thus, such areas are critical for population dynamics and are of high conservation priority. Leatherback sea turtles are among the world's most widely distributed species, and their breeding and feeding areas are typically separated by thousands of kilometres. In this study, we analysed turtle-borne video data on daytime feeding rates and energy acquisition in Nova Scotia, Canada, to quantify the importance of this discrete, seasonal foraging area for leatherback energy requirements. Based on daytime foraging only, we estimate that a single foraging season in Nova Scotia could support 59% of a non-breeding leatherback's annual energy budget, and 29% of energetic requirements for a female on a typical 2-year reproductive cycle. However, maximum energy intake rates for leatherbacks are nearly four times lower than those of mammals and birds due the low energy content of leatherbacks' gelatinous zooplankton prey. These results illustrate that high quality, local-scale foraging areas such as Nova Scotia are critically important to the stability and future growth of the leatherback population in the Northwest Atlantic Ocean. Thus, as with other migratory species, efforts to reduce threats and maintain habitat quality in such areas should be high conservation priorities.
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Affiliation(s)
- Bryan P Wallace
- Conservation Science Partners, Inc., 5 Old Town Square, Suite 205, Fort Collins, CO, 80524, USA. .,Nicholas School of the Environment, Duke University, Beaufort, NC, USA.
| | | | - Michael C James
- Population Ecology Division, Fisheries and Oceans Canada, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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James MC, Croot A, May PW, Allan NL. Negative electron affinity from aluminium on the diamond (1 0 0) surface: a theoretical study. J Phys Condens Matter 2018; 30:235002. [PMID: 29697065 DOI: 10.1088/1361-648x/aac041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Density functional theory calculations were performed to model the adsorption of up to 1 monolayer (ML) of aluminium on the bare and O-terminated (1 0 0) diamond surface. Large adsorption energies of up to -6.36 eV per atom are observed for the Al-adsorbed O-terminated diamond surface. Most adsorption sites give a negative electron affinity (NEA), with the largest NEAs -1.47 eV on the bare surface (1 ML coverage) and -1.36 eV on the O-terminated surface (0.25 ML coverage). The associated adsorption energies per Al atom for these sites are -4.11 eV and -5.24 eV, respectively. Thus, with suitably controlled coverage, Al on diamond shows promise as a thermally-stable surface for electron emission applications.
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Affiliation(s)
- Michael C James
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom. Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
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Ceriani SA, Roth JD, Sasso CR, McClellan CM, James MC, Haas HL, Smolowitz RJ, Evans DR, Addison DS, Bagley DA, Ehrhart LM, Weishampel JF. Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles. Ecosphere 2014. [DOI: 10.1890/es14-00230.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Casey JP, James MC, Williard AS. Behavioral and metabolic contributions to thermoregulation in freely swimming leatherback turtles at high latitudes. J Exp Biol 2014; 217:2331-7. [DOI: 10.1242/jeb.100347] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Leatherback turtles in the Northwest Atlantic Ocean have a broad geographic range that extends from nesting beaches near the equator to seasonal foraging grounds as far north as Canada. The ability of leatherbacks to maintain core body temperature (Tb) higher than that of the surrounding water is thought to be a key element of their biology that permits them to exploit productive waters at high latitudes. We provide the first recordings of Tb from freely swimming leatherbacks at a northern foraging ground, and use these data to assess the importance of behavioral adjustments and metabolic sources of heat for maintenance of the thermal gradient (Tg). The mean Tb for individual leatherbacks ranged from 25.4±1.7 to 27.3±0.3°C, and Tg ranged from 10.7±2.4 to 12.1±1.7°C. Variation in mean Tb was best explained by the amount of time that turtles spent in the relatively warm surface waters. A diel trend in Tb was apparent, with daytime cooling suggestive of prey ingestion and night-time warming attributable to endogenous heat production. We estimate that metabolic rates necessary to support the observed Tg are ~3 times higher than resting metabolic rate, and that specific dynamic action is an important source of heat for foraging leatherbacks.
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Affiliation(s)
- James P. Casey
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA
- Department of Biology, Barnard College, New York, NY 10027, USA
| | - Michael C. James
- Fisheries and Oceans Canada, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, NS, Canada, B2Y 4A2
| | - Amanda S. Williard
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA
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Hamelin KM, Kelley DE, Taggart CT, James MC. Water mass characteristics and solar illumination influence leatherback turtle dive patterns at high latitudes. Ecosphere 2014. [DOI: 10.1890/es13-00158.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Stewart KR, James MC, Roden S, Dutton PH. Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters. J Anim Ecol 2013; 82:791-803. [DOI: 10.1111/1365-2656.12056] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 01/08/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Kelly R. Stewart
- Protected Resources Division, Southwest Fisheries Science Center; National Marine Fisheries Service; National Oceanic and Atmospheric Administration; 8901 La Jolla Shores Dr; La Jolla; CA; 92037; USA
| | | | - Suzanne Roden
- Protected Resources Division, Southwest Fisheries Science Center; National Marine Fisheries Service; National Oceanic and Atmospheric Administration; 8901 La Jolla Shores Dr; La Jolla; CA; 92037; USA
| | - Peter H. Dutton
- Protected Resources Division, Southwest Fisheries Science Center; National Marine Fisheries Service; National Oceanic and Atmospheric Administration; 8901 La Jolla Shores Dr; La Jolla; CA; 92037; USA
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Heaslip SG, Iverson SJ, Bowen WD, James MC. Jellyfish support high energy intake of leatherback sea turtles (Dermochelys coriacea): video evidence from animal-borne cameras. PLoS One 2012; 7:e33259. [PMID: 22438906 PMCID: PMC3306388 DOI: 10.1371/journal.pone.0033259] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 02/12/2012] [Indexed: 11/18/2022] Open
Abstract
The endangered leatherback turtle is a large, highly migratory marine predator that inexplicably relies upon a diet of low-energy gelatinous zooplankton. The location of these prey may be predictable at large oceanographic scales, given that leatherback turtles perform long distance migrations (1000s of km) from nesting beaches to high latitude foraging grounds. However, little is known about the profitability of this migration and foraging strategy. We used GPS location data and video from animal-borne cameras to examine how prey characteristics (i.e., prey size, prey type, prey encounter rate) correlate with the daytime foraging behavior of leatherbacks (n = 19) in shelf waters off Cape Breton Island, NS, Canada, during August and September. Video was recorded continuously, averaged 1:53 h per turtle (range 0:08–3:38 h), and documented a total of 601 prey captures. Lion's mane jellyfish (Cyanea capillata) was the dominant prey (83–100%), but moon jellyfish (Aurelia aurita) were also consumed. Turtles approached and attacked most jellyfish within the camera's field of view and appeared to consume prey completely. There was no significant relationship between encounter rate and dive duration (p = 0.74, linear mixed-effects models). Handling time increased with prey size regardless of prey species (p = 0.0001). Estimates of energy intake averaged 66,018 kJ•d−1 but were as high as 167,797 kJ•d−1 corresponding to turtles consuming an average of 330 kg wet mass•d−1 (up to 840 kg•d−1) or approximately 261 (up to 664) jellyfish•d-1. Assuming our turtles averaged 455 kg body mass, they consumed an average of 73% of their body mass•d−1 equating to an average energy intake of 3–7 times their daily metabolic requirements, depending on estimates used. This study provides evidence that feeding tactics used by leatherbacks in Atlantic Canadian waters are highly profitable and our results are consistent with estimates of mass gain prior to southward migration.
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Affiliation(s)
- Susan G. Heaslip
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (SGH); (MCJ)
| | - Sara J. Iverson
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W. Don Bowen
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Fisheries and Oceans, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
| | - Michael C. James
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Fisheries and Oceans, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
- * E-mail: (SGH); (MCJ)
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Davenport J, Plot V, Georges JY, Doyle TK, James MC. Pleated turtle escapes the box--shape changes in Dermochelys coriacea. ACTA ACUST UNITED AC 2012; 214:3474-9. [PMID: 21957111 DOI: 10.1242/jeb.057182] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Typical chelonians have a rigid carapace and plastron that form a box-like structure that constrains several aspects of their physiology and ecology. The leatherback sea turtle, Dermochelys coriacea, has a flexible bony carapace strengthened by seven longitudinal ridges, whereas the plastron is reduced to an elliptical outer bony structure, so that the ventrum has no bony support. Measurements of the shell were made on adult female leatherbacks studied on the feeding grounds of waters off Nova Scotia (NS) and on breeding beaches of French Guiana (FG) to examine whether foraging and/or breeding turtles alter carapace size and/or shape. NS turtles exhibited greater mass and girth for a given curved carapace length (CCL) than FG turtles. Girth:CCL ratios rose during the feeding season, indicating increased girth. Measurements were made of the direct (straight) and surface (curved) distances between the medial longitudinal ridge and first right-hand longitudinal ridge (at 50% CCL). In NS turtles, the ratio of straight to curved inter-ridge distances was significantly higher than in FG turtles, indicating distension of the upper surfaces of the NS turtles between the ridges. FG females laid 11 clutches in the breeding season; although CCL and curved carapace width remained stable, girth declined between each nesting episode, indicating loss of mass. Straight to curved inter-ridge distance ratios did not change significantly during the breeding season, indicating loss of dorsal blubber before the onset of breeding. The results demonstrate substantial alterations in size and shape of female D. coriacea over periods of weeks to months in response to alterations in nutritional and reproductive status.
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Affiliation(s)
- John Davenport
- School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, Ireland.
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Mrosovsky N, Ryan GD, James MC. Leatherback turtles: the menace of plastic. Mar Pollut Bull 2009; 58:287-289. [PMID: 19135688 DOI: 10.1016/j.marpolbul.2008.10.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/26/2008] [Accepted: 10/29/2008] [Indexed: 05/27/2023]
Abstract
The leatherback, Dermochelyscoriacea, is a large sea turtle that feeds primarily on jellyfish. Floating plastic garbage could be mistaken for such prey. Autopsy records of 408 leatherback turtles, spanning 123 years (1885-2007), were studied for the presence or absence of plastic in the GI tract. Plastic was reported in 34% of these cases. If only cases from our first report (1968) of plastic were considered, the figure was 37%. Blockage of the gut by plastic was mentioned in some accounts. These findings are discussed in the context of removal of top predators from poorly understood food chains.
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Affiliation(s)
- N Mrosovsky
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario, Canada M5S 3G5.
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Abstract
1. Biological and statistical complexity are features common to most ecological data that hinder our ability to extract meaningful patterns using conventional tools. Recent work on implementing modern statistical methods for analysis of such ecological data has focused primarily on population dynamics but other types of data, such as animal movement pathways obtained from satellite telemetry, can also benefit from the application of modern statistical tools. 2. We develop a robust hierarchical state-space approach for analysis of multiple satellite telemetry pathways obtained via the Argos system. State-space models are time-series methods that allow unobserved states and biological parameters to be estimated from data observed with error. We show that the approach can reveal important patterns in complex, noisy data where conventional methods cannot. 3. Using the largest Atlantic satellite telemetry data set for critically endangered leatherback turtles, we show that the diel pattern in travel rates of these turtles changes over different phases of their migratory cycle. While foraging in northern waters the turtles show similar travel rates during day and night, but on their southward migration to tropical waters travel rates are markedly faster during the day. These patterns are generally consistent with diving data, and may be related to changes in foraging behaviour. Interestingly, individuals that migrate southward to breed generally show higher daytime travel rates than individuals that migrate southward in a non-breeding year. 4. Our approach is extremely flexible and can be applied to many ecological analyses that use complex, sequential data.
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Affiliation(s)
- Ian D Jonsen
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H4J1.
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Abstract
Leatherback sea turtles, Dermochelys coriacea, undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.
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Affiliation(s)
- Michael C James
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1.
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James MC, Andrea Ottensmeyer C, Myers RA. Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecol Lett 2005. [DOI: 10.1111/j.1461-0248.2004.00710.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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James MC, Martin K, Dutton PH. Hybridization Between a Green Turtle, Chelonia mydas, and Loggerhead Turtle, Caretta caretta, and the First Record of a Green Turtle in Atlantic Canada. ACTA ACUST UNITED AC 2004. [DOI: 10.22621/cfn.v118i4.59] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Green Turtle (Chelonia mydas) principally occupies tropical and subtropical waters, although juveniles are known to occur seasonally in temperate coastal waters. Collaboration with commercial fishers in eastern Canada yielded the most northerly records of this species in the northwest Atlantic. Here we report on the first confirmed record of a Green Turtle in eastern Canada and on the occurrence of a rare Green Turtle–Loggerhead Turtle (Caretta caretta) hybrid. Hybridization between the Carettini and Chelonini is extraordinary given that these groups have been genetically distinct for 50 million years or more.
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James MC, Mrosovsky N. Body temperatures of leatherback turtles (Dermochelys coriacea) in temperate waters off Nova Scotia, Canada. CAN J ZOOL 2004. [DOI: 10.1139/z04-110] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The leatherback sea turtle, Dermochelys coriacea (Vandelli, 1761), has the most extensive range of any reptile, migrating from tropical and subtropical nesting areas to distant foraging habitats, including those in temperate and even boreal waters. This implies flexible thermal functioning. It has been inferred that leatherbacks support active foraging by keeping warm in cold water, rather than becoming lethargic as other marine turtles do. However, data consistent with this view have come from captive turtles in unnatural and stressful conditions. In the present case, foraging leatherbacks were captured at sea off Nova Scotia and their body temperature recorded within 10 min, before such large animals could change their body temperatures appreciably. Mean excess temperature over that of the sea surface (15.0–16.7 °C) averaged 8.2 °C. These results attest to, but underestimate, the capacity of free-swimming leatherbacks to keep warm in northern waters, as data from another turtle that was instrumented to record ocean temperature while diving revealed that leatherbacks foraging in this area at the same time of year may spend 40% of their time diving to waters cooler than the surface.
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Abstract
Two distinct products are specified by the CDKN2A locus, the p16INK4a cyclin dependent kinase inhibitor and a protein termed ARF. ARF has been shown to bind to the Mdm2-p53 complex, resulting in stabilisation of both proteins, and a feedback loop exists through which ARF levels are negatively regulated by p53. Significantly, ARF expression is positively regulated by members of the E2F family of transcription factors. This provides a link between the Rb and p53 pathways and a mechanism whereby inactivation of Rb and release of E2F will lead to the stabilisation and functional activation of p53. The alternative exon encoding the functional amino terminal portion of ARF presumably represents an independent gene that has become co-localized with p16INK4a in order to exploit a common regulatory mechanism or purpose.
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Affiliation(s)
- M C James
- Imperial Cancer Research Fund, London, United Kingdom
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Swithinbank LV, Donovan JL, du Heaume JC, Rogers CA, James MC, Yang Q, Abrams P. Urinary symptoms and incontinence in women: relationships between occurrence, age, and perceived impact. Br J Gen Pract 1999; 49:897-900. [PMID: 10818656 PMCID: PMC1313561] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND The prevalence of urinary symptoms that impact on quality-of-life will be important in determining resource allocation in primary care groups. AIM To determine the prevalence of urinary symptoms and their perceived impact in a community population of women. METHOD A postal survey using a validated self-completed questionnaire among all women aged over 18 years and registered with one general practice in a major British city. The prevalence rates and perceived impact of a wide range of urinary symptoms and their relationship with age was determined. Data were analysed using the chi-squared test and the chi-squared test for trend. Spearman's rank correlation was used to assess the relationship between symptom severity and perceived impact. RESULTS The number of completed questionnaires returned was 2075, giving an 80% response rate. Of these, the number of women who reported some degree of incontinence in the previous month was 1414 (69%), although only 578 (30%) indicated that it had social or hygienic impact. Other lower urinary tract symptoms reported included nocturia (19%), poor stream (19%), urgency (61%), and dysuria (23%). The most troublesome symptoms were incontinence for no obvious reason, nocturnal incontinence, and nocturia, with 73%, 69%, and 63% of sufferers, respectively, finding these symptoms troublesome. CONCLUSIONS Incontinence and other urinary symptoms are more common than previously thought. These symptoms are not always perceived as bothersome or as having a social or hygienic impact, and therefore many women who report urinary leakage do not require treatment. Nocturnal symptoms in women are commoner than might have been supposed and are extremely troublesome to sufferers.
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James MC, Jeffrey IW, Pruijn GJ, Thijssen JP, Clemens MJ. Translational control by the La antigen. Structure requirements for rescue of the double-stranded RNA-mediated inhibition of protein synthesis. Eur J Biochem 1999; 266:151-62. [PMID: 10542060 DOI: 10.1046/j.1432-1327.1999.00839.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The La antigen is a protein which can bind both single-stranded and double-stranded forms of RNA and has regulatory effects on gene expression at the levels of transcription and translation. It was previously shown to inhibit the activation of the dsRNA-dependent protein kinase PKR by sequestering and/or unwinding double-stranded RNA. Here, we demonstrate that, as predicted by these properties, the La antigen can rescue protein synthesis in the reticulocyte lysate system from inhibition by low concentrations of dsRNA. This effect is reversed by higher concentrations of dsRNA. Using a series of deletion mutants we have investigated the structural features of the La antigen that are required for these effects. The ability to bind dsRNA is influenced by regions within both the previously characterized N-terminal RNP motif and the C-terminal half of the protein. La mutants with either N-terminal or C-terminal deletions retain the ability to inhibit the protein kinase activity of PKR and to rescue protein synthesis from inhibition by dsRNA. It is notable that sequences in the C-terminal half of the La antigen, including a phosphorylation site at Ser366, which are needed for other regulatory effects of the protein on gene expression are dispensable for the effects of La on PKR. We suggest that La regulates PKR activity solely as a result of its ability to act as an RNA-binding protein that can compete with PKR for limiting amounts of dsRNA.
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Affiliation(s)
- M C James
- Department of Biochemistry, Cellular and Molecular Sciences Group, St. George's Hospital Medical School, London, UK
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Stott FJ, Bates S, James MC, McConnell BB, Starborg M, Brookes S, Palmero I, Ryan K, Hara E, Vousden KH, Peters G. The alternative product from the human CDKN2A locus, p14(ARF), participates in a regulatory feedback loop with p53 and MDM2. EMBO J 1998; 17:5001-14. [PMID: 9724636 PMCID: PMC1170828 DOI: 10.1093/emboj/17.17.5001] [Citation(s) in RCA: 840] [Impact Index Per Article: 32.3] [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: 12/14/2022] Open
Abstract
The two distinct proteins encoded by the CDKN2A locus are specified by translating the common second exon in alternative reading frames. The product of the alpha transcript, p16(INK4a), is a recognized tumour suppressor that induces a G1 cell cycle arrest by inhibiting the phosphorylation of the retinoblastoma protein by the cyclin-dependent kinases, CDK4 and CDK6. In contrast, the product of the human CDKN2A beta transcript, p14(ARF), activates a p53 response manifest in elevated levels of MDM2 and p21(CIP1) and cell cycle arrest in both G1 and G2/M. As a consequence, p14(ARF)-induced cell cycle arrest is p53 dependent and can be abrogated by the co-expression of human papilloma virus E6 protein. p14(ARF) acts by binding directly to MDM2, resulting in the stabilization of both p53 and MDM2. Conversely, p53 negatively regulates p14(ARF) expression and there is an inverse correlation between p14(ARF) expression and p53 function in human tumour cell lines. However, p14(ARF) expression is not involved in the response to DNA damage. These results place p14(ARF) in an independent pathway upstream of p53 and imply that CDKN2A encodes two proteins that are involved in tumour suppression.
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Affiliation(s)
- F J Stott
- Imperial Cancer Research Fund Laboratories, P.O. Box 123, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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Hartmann R, Norby PL, Martensen PM, Jorgensen P, James MC, Jacobsen C, Moestrup SK, Clemens MJ, Justesen J. Activation of 2'-5' oligoadenylate synthetase by single-stranded and double-stranded RNA aptamers. J Biol Chem 1998; 273:3236-46. [PMID: 9452437 DOI: 10.1074/jbc.273.6.3236] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [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: 02/06/2023] Open
Abstract
A number of small RNA molecules that are high affinity ligands for the 46-kDa form of human 2'-5' oligoadenylate synthetase have been identified by the SELEX method. Surface plasmon resonance analysis indicates that these RNAs bind to the enzyme with dissociation constants in the nanomolar range. Competition experiments indicate that the binding site for the small RNAs on the 2'-5' oligoadenylate synthetase molecule at least partially overlaps that for the synthetic double-stranded RNA, poly(I).poly(C). Several of the RNAs function as potent activators of 2'-5' oligoadenylate synthetase in vitro, although there is no correlation between binding affinity and ability to activate. The RNA aptamers having the strongest activation potential appear to have few base-paired regions. This suggests that 2'-5' oligoadenylate synthetase, which has previously been believed to be activated only by double-stranded RNA, can also be activated by RNA ligands with little secondary structure. Since 2'-5' oligoadenylate synthetase possesses no homology to other known RNA-binding proteins, the development of small specific ligands by SELEX should facilitate studies of RNA-protein interactions and may reveal novel features of the structure-function relationships involving this enzyme.
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Affiliation(s)
- R Hartmann
- Department of Molecular and Structural Biology, University of Aarhus, C. F. Mollers Allé, Building 130, DK-8000 Aarhus C, Denmark
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James MC, Pruijn GJ, van Venrooij WJ, Clemens MJ. Analysis of the double-stranded RNA binding properties of the La antigen. Biochem Soc Trans 1995; 23:312S. [PMID: 7672342 DOI: 10.1042/bst023312s] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- M C James
- Division of Biochemistry, St George's Hospital Medical School, London, U.K
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Xiao Q, Sharp TV, Jeffrey IW, James MC, Pruijn GJ, van Venrooij WJ, Clemens MJ. The La antigen inhibits the activation of the interferon-inducible protein kinase PKR by sequestering and unwinding double-stranded RNA. Nucleic Acids Res 1994; 22:2512-8. [PMID: 7518914 PMCID: PMC308203 DOI: 10.1093/nar/22.13.2512] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [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: 01/25/2023] Open
Abstract
The La (SS-B) autoimmune antigen is an RNA-binding protein that is present in both nucleus and cytoplasm of eukaryotic cells. The spectrum of RNAs that interact with the La antigen includes species which also bind to the interferon-inducible protein kinase PKR. We have investigated whether the La antigen can regulate the activity of PKR and have observed that both the autophosphorylation of the protein kinase that accompanies its activation by dsRNA and the dsRNA-dependent phosphorylation of the alpha subunit of polypeptide chain initiation factor eIF-2 by PKR are inhibited in the presence of recombinant La antigen. This inhibition is partially relieved at higher concentrations of dsRNA. Once activated by dsRNA the protein kinase activity of PKR is insensitive to the La antigen. We have demonstrated by a filter binding assay that La is a dsRNA binding protein. Furthermore, when recombinant La is incubated with a 900 bp synthetic dsRNA or with naturally occurring reovirus dsRNA it converts these substrates to single-stranded forms. We conclude that the La antigen inhibits the dsRNA-dependent activation of PKR by binding and unwinding dsRNA and that it may therefore play a role in the regulation of this protein kinase in interferon-treated or virus-infected cells.
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Affiliation(s)
- Q Xiao
- Department of Cellular and Molecular Sciences, St George's Hospital Medical School, London, UK
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Clemens MJ, Laing KG, Jeffrey IW, Schofield A, Sharp TV, Elia A, Matys V, James MC, Tilleray VJ. Regulation of the interferon-inducible eIF-2 alpha protein kinase by small RNAs. Biochimie 1994; 76:770-8. [PMID: 7534482 DOI: 10.1016/0300-9084(94)90081-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [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: 01/25/2023]
Abstract
This review describes the structure and function of the double-stranded RNA-dependent protein kinase (PKR) and its interaction with RNA activators and inhibitors. The abilities of small virally-encoded RNAs such as VAI RNA of adenovirus, the Epstein-Barr virus encoded (EBER) RNAs and the Tat-responsive region RNA of HIV-1 to bind to and regulate PKR are reviewed, and the physiological implications of such regulation for the control of viral replication and cell growth are discussed. The potential effects on the activity of PKR of other proteins that bind double-stranded RNA and/or small viral and cellular RNAs are also considered.
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Affiliation(s)
- M J Clemens
- Department of Cellular and Molecular Sciences, St George's Hospital Medical School, London, UK
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Abstract
The purpose of this article is to provide an overview of bone marrow transplantation (BMT) as it relates to the practice of physical therapy based on experiences at a cancer research center. This overview includes information on the diseases treated with BMT, patient treatment regimens during hospitalization, and complications commonly encountered. Physical therapy guidelines are suggested for the evaluation of and therapeutic intervention for patients after BMT.
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Singer JW, Brown JE, James MC, Doney K, Warren RP, Storb R, Thomas ED. Effect of peripheral blood lymphocytes from patients with aplastic anemia on granulocytic colony growth from HLA-matched and -mismatched marrows: effect of transfusion sensitization. Blood 1978; 52:37-46. [PMID: 656632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Abstract
Marrow cells from an untreated man with preleukaemia were found to have trisomy for the long arm of chromosome 1 which was translocated to the end of the long arm of number 11, i.e., 46,XY, -11,+t (1:11) (q11 or q12; q25). The same abnormality was found in metaphases from 8 individual granulocytic colonies. With development of acute myelomonocytic leukaemia, in addition to the basic chromosome abnormality, trisomy of chromosome 8 and an extra chromosome number 19 with partial deletion were found. Fibroblasts grown from marrow biopsy material showed a normal diploid complement, 46,XY.
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Kemp RB, Jones BM, Cunningham I, James MC. Quantitative Investigation on the Effect of Puromycin on the Aggregation of Trypsin- and Versene-Dissociated Chick Fibroblast Cells. J Cell Sci 1967; 2:323-40. [PMID: 4293085 DOI: 10.1242/jcs.2.3.323] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Embryonic chick fibroblast cells were used to test the effects of puromycin on cell adhesion and aggregation. Single cell suspensions were prepared by dissociating the muscle tissues of 5- and 9-day-old chick embryos with either trypsin or versene according to standard cell dissociation procedures. Cell aggregation was quantitatively estimated by a turbidimetric method.
Quantitative analyses of the components in cell-free supernatants revealed that both trypsin and versene when used as cell dissociating agents removed substantial amounts of protein from the surfaces of the cells and the intercellular regions. Trypsin removed larger quantities of protein and of N-acetylneuraminic acid than did versene. Nucleic acids were also released during trypsin and versene dissociation, and estimations of these nucleic acids gave a measure of the extent of cell lysis. The proteins and peptides were separated by gel filtration. The solubilized proteins removed by versene treatment were separated into three peaks on Sephadex G. 200. The tryptic digest gave one main peptide peak on Sephadex G.50.
Both trypsin- and versene-dissociated cells, on rotation in Hanks's balanced salts solution with or without serum, began to adhere to one another at the start of the test period, indicating that the cell dissociation procedures had not impaired the adhesive properties of the separated cells.
When puromycin at a final concentration of 10 µg/ml was introduced at zero time into a cell suspension with or without serum, it did not delay the adhesion of cells to one another, and did not prevent the formation in the first hour of initial aggregates; it succeeded only in preventing progress in aggregation beyond the initial stages. Adding puromycin at the 2nd or 3rd hour of the 4-h test period, when aggregation had already taken place, produced results of a similar pattern, progress in aggregation being brought to a halt an hour later. Puromycin at the above concentration effectively blocked protein synthesis by more than 90% as measured by the incorporation of L-[α-14C]leucine into the proteins of the rotated cells. These results implied that aggregation was not dependent on the synthesis of ‘cell aggregating’ material to replenish the loss of such material from the surfaces of the cells owing to the trypsin treatment. It is significant that 2,4-dinitrophenol, which is known to suppress cellular metabolism by inhibiting the production of ATP, also brought cell aggregation to a halt only after a lag period during which initial aggregates were formed.
It is suggested, as evidenced in the results of our investigations, that puromycin may well be exerting its inhibitory effect by ultimately depressing cellular metabolism below the level at which certain basic adhesive mechanisms at the cell surface can operate.
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