scholarly journals Leeches run cold, then hot

2011 ◽  
Vol 7 (6) ◽  
pp. 941-943 ◽  
Author(s):  
Ann M. Petersen ◽  
Wendy Chin ◽  
Kara L. Feilich ◽  
Grace Jung ◽  
Jessica L. Quist ◽  
...  

Food processing is costly, potentially limiting the energy and time devoted to other essential functions such as locomotion or reproduction. In ectotherms, post-prandial thermophily, the selection of a warm environmental temperature after feeding, may be advantageous in minimizing the duration of this elevated cost. Although present in many vertebrate taxa, this behaviour had not previously been observed in invertebrates. Sanguivorous leeches ingest large blood meals that are costly to process and limit mobility until excess fluid can actively be expelled to reduce body volume. When presented with a temperature gradient from 10°C to 30°C, leeches select a temperature that is significantly warmer (24.3 ± 0.9°C, n = 6) than their acclimation temperature ( T a , 21°C). Unfed leeches preferred temperatures that were significantly cooler than ambient (12.8 ± 0.9°C, n = 6). This behavioural strategy is consistent with minimizing the time course of elevated post-feeding energy costs and reducing energy expenditure during fasting. Our observations raise the possibility that thermoregulatory behaviour of this type is an unrecognized feature of other invertebrate taxa.

1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.


Author(s):  
César Camisón

The key premise of economics, which views people as utilitarian individuals who make completely rational economic decisions, has influenced other disciplines as Strategy. However, the developments in behavioural neuroscience have opened a major understanding of the mental processes that explain managers's behaviour and effectiveness.This article presents a review of the contributions from behavioural neuroscience to the study of managerial decision-making and offers a critical evaluation of its implications for management and organization studies, especially in the field of strategy. The paper reviews the most recent literature on neurostrategy and maps out the main strands of the debate and their implications for understanding the behaviour of strategy-makers. The study of neuronal and psicological foundations for strategy-makers behaviours and decision-making has identified the problems of the general model of the rational problem-solving process in information, perception, and selection of strategies, and how behavioural strategy can help us to identify them and prevent them.


1977 ◽  
Vol 55 (3) ◽  
pp. 590-594 ◽  
Author(s):  
E. T. Garside ◽  
D. G. Heinze ◽  
S. E. Barbour

Thermal preferences were determined in spacious thermal gradients of fresh water and sea water (32‰ salinity (S))for acclimations of 5, 15, and 25 °C in sea water, for samples of threespine stickleback Gasterosteus aculeatus L. Preferred temperatures increased through acclimations of 5–25 °C, with those for the freshwater tests being about 2 °C lower at each acclimation. Final preferenda were 16 and 18 °C for freshwater tests and seawater tests, respectively. The final preferendum in such haloplastic species is defined as the highest obtainable preferendum that equals acclimation temperature. A later series of disjunct preference determinations in approximately isosmotic water (10.5‰ S) for subjects acclimated to 7, 15, and 20 °C yielded mean values of 17.7, 18.2, and 18.7 °C, respectively. A final preferendum has not been designated since the samples were of separate origins. A parallel exists between these responses and the response of this and other haloplastic species in the determination of upper lethal temperatures. The immediate cause appears to be differentials in metabolic loading occasioned by l stresses.


2005 ◽  
Vol 67 (8) ◽  
pp. 1437-1445 ◽  
Author(s):  
M. E. Berryhill ◽  
K. Kveraga ◽  
L. Webb ◽  
H. C. Hughes
Keyword(s):  

1978 ◽  
Vol 40 (3) ◽  
pp. 433-438 ◽  
Author(s):  
W. H. Close

1. From the relation between metabolizable energy (me) intake and heat loss (H), energy retention (ER), protein (P) and fat (F) deposition the energy costs of maintenance (MEm) and the partial efficiencies of energy retention (k) and protein (kp) and fat (kf) retention were determined in growing pigs at environmental temperatures of 10, 15, 20, 25 or 30°.2. k decreased with increase in environmental temperature from 0.79 at 10° to 0.63 at 30° with 0.67 at the thermally-neutral temperature of 25°. Each 0.04 decrease in k was associated with a 100 kJ/kg0.75 per d decrease in mem Analysis, within several ranges of environmental temperature, suggested a curvilinear relation between ER and me intake indicating a decrease in k with increase in level of feeding, particularly at thermally-neutral temperatures.3. Both kp and kf were similar at each environmental temperature and decreased from 0.78 at 10° to 0.63 at 30°. These values are discussed in relation to those predicted from experimentation and it is suggested that the wide range of predicted estimates of kp could be attributed to differences in the rate of protein turnover.


Perception ◽  
1993 ◽  
Vol 22 (5) ◽  
pp. 597-621 ◽  
Author(s):  
Roberta L Klatzky ◽  
Susan J Lederman

A conceptual model of the human haptic system in relation to object identification is presented. The model encompasses major architectural elements including representations of haptically accessible object properties and exploratory procedures (EPs)—dedicated movement patterns that are specialized to extract particular properties. These architectural units are related in processing-specific ways. Properties are associated with exploratory procedures in keeping with the extent to which a given procedure delivers information about a given property. The EPs are associated with one another in keeping with their compatibility, as determined by parameters of motor execution and interactions with the object and the workspace. The resulting architecture is treated as a system of constraints which guide the exploration of an object during the course of identification. The selection of the next step in a sequence of exploration requires that constraints be optimally satisfied. A network approach to constraint satisfaction is implemented and shown to account for a number of previous empirical results concerning the time course of exploration, object classification speed, and incidental learning about object properties. This system has potential applications for robotic haptic exploration.


1979 ◽  
Vol 32 (1) ◽  
pp. 133 ◽  
Author(s):  
Pamela R Pennycuik

When mice are transferred from a 'temperate' to a hot environment their reproductive output is reduced. To test whether this reduction could be countered by selection, three mouse lines, housed permanently as 32�C, were selected for increase in the numbers of young reared to 3 weeks when pairs were allowed to remain together for 12 weeks. In one line (R95) in which all fertile pairs contributed to the next generation, no improvement was observed in 19 generations. In two other lines (W21 and W34) in which only half the pairs in one generation contributed to the next, productivity returned, in about 12 generations, to almost the same levels as those of controls housed at 21�C.


2021 ◽  
Author(s):  
Stefanie Weber ◽  
Christina M. Ramirez ◽  
Barbara Weiser ◽  
Harold Burger ◽  
Walter Doerfler

AbstractScientists and the public were alarmed at the first large viral variant of SARS-CoV2 reported in December 2020. We have followed the time course of emerging viral mutants and variants during the SARS-CoV-2 pandemic in ten countries on four continents. We examined complete SARS-CoV-2 nucleotide sequences in GISAID, (Global Initiative of Sharing All Influenza Data) with sampling dates extending until January 20, 2021. These sequences originated from ten different countries: United Kingdom, South Africa, Brazil, USA, India, Russia, France, Spain, Germany, and China. Among the novel mutations, some previously reported mutations waned and some of them increased in prevalence over time. VUI2012/01 (B.1.1.7) and 501Y.V2 (B.1.351), the so-called UK and South Africa variants, respectively, and two variants from Brazil, 484K.V2, now called P.1 and P.2, increased in prevalence. Despite lockdowns, worldwide active replication in genetically and socio-economically diverse populations facilitated selection of new mutations. The data on mutant and variant SARS-CoV-2 strains provided here comprise a global resource for easy access to the myriad mutations and variants detected to date globally. Rapidly evolving new variant and mutant strains might give rise to escape variants, capable of limiting the efficacy of vaccines, therapies, and diagnostic tests.Significance and New Aspects of Study – SynopsisWe examine the time course of emerging mutations in the SARS-CoV-2 genome that have rapidly been selected in the world’s populations through the beginning of 2021. A study of the prevalence of viral mutations in the GISAID database in ten different countries – United Kingdom, South Africa, Brazil, US, India, Russia, France, Spain, Germany, and China - revealed widespread mutations along the genome.We previously identified about 10 hotspot mutations in the SARS-CoV-2 genome that became prevalent in many of the countries studied1. Since the beginning of February, many new mutations arose in the ten countries (and worldwide). The preponderance of variants and mutations correlated with the increased spread of Covid-19.There was a temporal progression from about 10 predominant mutants shared by several countries up to the end of May 2020, followed by a consistent and rapid increase in the number of new mutations between June and December along with the emergence of variants of concern, first reported in December 2020.We examine the relative frequencies of mutations, along with variants of interest, in 10 countries up until January 20, 2021. Investigations on the pathogenic properties of individual SARS-CoV-2 mutations will be urgently needed to understand the kaleidoscopic patterns of worldwide Covid-19 outbreaks and symptoms. Monitoring the frequency and speed of mutant selection have direct relevance to diagnostic testing, vaccines and therapeutics.As an explanation for efficient viral mutagenesis, we hypothesize that the viral spike protein – as documented – facilitates viral entry via the cell’s ACE receptor2. This in turn interacts with the APOBEC polypeptide, an m-RNA editing function. The actually observed frequent C to U (T) transitions and other base exchanges are thus effected. Hence, as one of the earliest steps upon viral entry, active mutagenesis commences, since SARS-CoV-2 exploits one of the cell’s defenses against viral infections.


2007 ◽  
Vol 2 (3) ◽  
pp. 313-357 ◽  
Author(s):  
Koenraad Kuiper ◽  
Marie-Elaine van Egmond ◽  
Gerard Kempen ◽  
Simone Sprenger

Only relatively recently have theories of speech production concerned themselves with the part idioms and other multi-word lexical items (MLIs) play in the processes of speech production. Two theories of speech production which attempt to account for the accessing of idioms in speech production are those of Cutting and Bock (1997) and superlemma theory (Sprenger, 2003; Sprenger, Levelt, & Kempen, 2006). Much of the data supporting theories of speech production comes either from time course experiments or from slips of the tongue (Bock & Levelt, 1994). The latter are of two kinds: experimentally induced (Baars, 1992) or naturally observed (Fromkin, 1980). Cutting and Bock use experimentally induced speech errors while Sprenger et al. use time course experiments. The missing data type that has a bearing on speech production involving MLIs is that of naturally occurring slips. In this study the impact of data taken from naturally observed slips involving English and Dutch MLIs are brought to bear on these theories. The data are taken initially from a corpus of just over 1000 naturally observed English slips involving MLIs (the Tuggy corpus). Our argument proceeds as follows. First we show that slips occur independent of whether or not there are MLIs involved. In other words, speech production proceeds in certain of its aspects as though there were no MLI present. We illustrate these slips from the Tuggy data. Second we investigate the predictions of superlemma theory. Superlemma theory (Sprenger et al., 2006) accounts for the selection of MLIs and how their properties enter processes of speech production. It predicts certain activation patterns dependent on a MLI being selected. Each such pattern might give rise to slips of the tongue. This set of predictions is tested against the Tuggy data. Each of the predicted activation patterns yields a significant number of slips. These findings are therefore compatible with a view of MLIs as single units in so far as their activation by lexical concepts goes. However, the theory also predicts that some slips are likely not to occur. We confirm that such slips are not present in the data. These findings are further corroborated by reference a second smaller dataset of slips involving Dutch MLIs (the Kempen corpus). We then use slips involving irreversible binomials to distinguish between the predictions of superlemma theory which are supported by slips involving irreversible binomials and the Cutting and Bock model’s predictions for slips involving these MLIs which are not.


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