Mutation detection, interpretation, and applications in the clinical laboratory setting

Mutation detection plays an increasingly significant role in clinical diagnostic testing, posing formidable challenges for laboratories. The expanding indications for clinical molecular testing and the nuances of interpreting test results are discussed. Methods for screening mutation detection platforms and monitoring assay reliability are presented, and results of platform comparisons are described. The potential for irrevocable medical interventions following a positive mutation analysis is highlighted to stress the imperative for accuracy in mutation detection and vigilance in the clinical arena.     

Monotony and the Information Content of Richardson's Ground Squirrel (Spermophilus richardsonii) Repeated calls: Tonic Communication or Signal Certainty?

The repetition of elements within an alarm signal is commonly thought to ensure that receivers have detected that signal, or to promote residual vigilance in light of the dangerous circumstances prompting the signal's initial production (tonic communication). Beyond alerting others and maintaining that state of alertness, however, repetitive signal elements may be parsed so as to encode information about the nature of potential threats. To determine how call length and variation in intersyllable latency might prove informative in the repetitive alarm vocalizations of Richardson's ground squirrels (Spermophilus richardsonii), we conducted a field‐based playback experiment quantifying antipredator responses to manipulated alarm calls. Free‐living juvenile squirrels were exposed to playbacks of 12 syllable (long) and six syllable (short) calls with a constant (monotonous) or changing (variable) call rate. The length of calls had no significant effect on the behaviour of call recipients during and immediately after call production; however, call recipients showed greater vigilance after the playback of monotonous calls than after variable calls. The absence of a call length effect is not consistent with tonic communication in the strict sense; rather, enhanced responsiveness to monotonous relative to variable calls suggests that multiple syllables, and the emergent patterns of intersyllable latency, communicate information about response urgency or the distance to a predatory threat. Only monotonous calls convey those aspects with any certainty on the part of the signaller and hence are selectively attended to by receivers.     

The effects of group size and reproductive status on vigilance in captive Callithrix jacchus

Previous work on mammals and birds has often demonstrated a negative relationship between group size and individual vigilance. However, this relationship has received only weak support in nonhuman primates. This result may be due to the failure to distinguish different forms of vigilance such as antipredatory vigilance and social monitoring. Here, we tested the effects of group size, reproductive status (breeding vs. nonbreeding), and sex on antipredatory vigilance and social monitoring in captive common marmosets (Callithrix jacchus). Behavioral observations using one-zero sampling were conducted on adult members of three captive groups of small, medium, and large size. Data were analyzed using a series of general linear models (GLMs) analyses of covariance (ANCOVAs). We found an overall negative group size effect on antipredatory vigilance and that breeders, especially breeding males, were significantly more vigilant than nonbreeders. Conversely, we found that social monitoring increased with group size. Unlike the results for antipredatory vigilance, neither breeders and nonbreeders nor males and females differed in their amounts of social monitoring. However, the effect of group size appeared to differ for nonbreeding males compared to all other adults. Our results generally support the idea that individuals in larger groups are safer with breeding males likely playing a prominent role in protection from predation. The increase in social monitoring may be related to increased reproductive competition with the presence of adult offspring, but future studies need to clarify the target of social monitoring in both breeders and nonbreeders. Overall, the study underlines the importance of distinguishing different forms of vigilance and other factors as they may confound the effects of group size on antipredatory vigilance.     

Number of neighbors instead of group size significantly affects individual vigilance levels in large animal aggregations

The group size effect states that animals living in groups gain anti‐predator benefits through reducing vigilance levels as group size increases. A basic assumption of group size effect is that all individuals are equally important for a focal individual, who may adjust its vigilance levels according to social information acquired from them. However, some studies have indicated that neighbors pose greater influences on an individual's vigilance decisions than other group members, especially in large aggregations. Vigilance has also been found to be directed to both predators (anti‐predation vigilance) and conspecifics (social vigilance). Central individuals might rely more on social vigilance than peripheral individuals. To test these hypotheses, we examined the effects of flock size, number of neighbors and position within a flock on vigilance and competition of greater white‐fronted goose Anser albifrons that form large foraging flocks in winter, controlling the effects of other variables (group identity, winter period and site). We found that individual vigilance levels were significantly affected by number of neighbors and position within a flock, whereas flock size showed no effect. Individuals devoted a large component of vigilance to nearby flock mates. Central individuals directed a relatively larger proportion of vigilance to monitor neighbors than peripheral ones, indicating that central individuals more relied on social information acquired from neighbors, possibly caused by the more blocked visual field of central individuals. Moreover, some social vigilance may function as conducting or preventing agonistic interactions since competition intensity was positively correlated with number of neighbors. Our study therefore demonstrate that the number of neighbors is more important than group size in determining individual vigilance in large animal groups. Further studies are still needed to unravel which neighbors pose greater influence on individual vigilance, and the factors that influence individuals to acquire information from their neighbors to adjust vigilance behaviors.     

Mapping human vigilance: The influence of conspecifics

A considerable volume of animal research on detecting threat and foraging reveals that the co-presence of conspecifics reduces vigilance and enhances foraging. Monitoring threat is an adaptive process and is of considerable relevance to humans. It is therefore important to understand how the presence of others influences threat monitoring - namely vigilance - and consequently the capacity to detect threats. We examine this with a novel paradigm, that simulates a “foraging under threat” situation, with an eye-tracker (allowing the examination of the allocation of attention). Our results show, as predicted, that participants in the individual condition (versus co-presence) allocated more attentional resources to scanning the environment and thereby sacrificing foraging, which increased their likelihood of detecting threatening events. Thus, the presence or absence of others modulates vigilance strategies in humans. These findings highlight the heuristic value of animal vigilance models to understand humans threat monitoring with considerable applied relevance.     

Conspecific Influences on Vigilance Behavior in Wild Chimpanzees

Diurnal primates rely on visual monitoring behavior to collect various kinds of ecological and social information. Vigilance behavior is monitoring specifically to detect external threats. Previous studies of vigilance behavior were focused mainly on the influence of predation threats, whereas the influences of conspecific factors, such as intragroup threats, have been relatively unstudied. Individual vigilance is predicted to be inversely related to the group size or the number of individuals nearby if the main target of the vigilance is a predation threat and positively related if the main target of the vigilance is a conspecific threat. I studied wild chimpanzees (Pan troglodytes schweinfurthii) in Mahale Mountains National Park, Tanzania, and measured the vigilance duration when they are resting on the ground via 2-min focal observation. In both males and females, vigilance duration increased as the number of individuals nearby increased. This result agrees with the idea that the chimpanzees are vigilant toward other group members. In addition, maternal vigilance monitors and protects the safety of dependent offspring as the duration of maternal vigilance was longer when a dependent infant was separated from its mother than when the offspring was in contact with its mother. The results indicate that the vigilance behavior in wild chimpanzees was affected by conspecific factors.     

Coordination and synchronisation of anti-predation vigilance in two crane species

Much of the previous research on anti-predation vigilance in groups has assumed independent scanning for threats among group members. Alternative patterns that are based on monitoring the vigilance levels of companions can also be adaptive. Coordination of vigilance, in which foragers avoid scanning at the same time as others, should decrease the odds that no group member is alert. Synchronisation of vigilance implies that individuals are more likely to be vigilant when companions are already vigilant. While synchronisation will increase the odds that no one is vigilant, it may allow a better assessment of potential threats. We investigated temporal sequences of vigilance in family flocks consisting of two parents and at most two juveniles in two species of cranes in coastal China. We established whether the observed probability that at least one parent is alert was greater (coordination) or lower (synchronisation) than that predicted under the null hypothesis of independent vigilance. We documented coordination of vigilance in common cranes (Grus grus) foraging in an area with high potential for disturbance by people. We documented synchronisation of vigilance in red-crowned cranes (Grus japonensis) in the less but not in the more disturbed area. Coordination in small flocks leads to high collective vigilance but low foraging rates that may not be suitable in areas with low disturbance. We also argue that synchronisation should break down in areas with high disturbance because periods with low vigilance are riskier. Results highlight the view that temporal patterns of vigilance can take many forms depending on ecological factors.     

The molecular genetics of cyanobacterial toxicity as a basis for monitoring water quality and public health risk

Toxic cyanobacteria pose a significant hazard to human health and the environment. The recent characterisation of cyanotoxin synthetase gene clusters has resulted in an explosion of molecular detection methods for these organisms and their toxins. Conventional polymerase chain reaction (PCR) tests targeting cyanotoxin biosynthesis genes provide a rapid and sensitive means for detecting potentially toxic populations of cyanobacteria in water supplies. The adaptation of these simple PCR tests into quantitative methods has additionally enabled the monitoring of dynamic bloom populations and the identification of particularly problematic species. More recently, DNA microarray technology has been applied to cyanobacterial diagnostics offering a high-throughput option for detecting and differentiating toxic genotypes in complex samples. Together, these molecular methods are proving increasingly important for monitoring water quality.     

Usefulness of molecular markers for detecting population bottlenecks via monitoring genetic change

It is important to detect population bottlenecks in threatened and managed species because bottlenecks can increase the risk of population extinction. Early detection is critical and can be facilitated by statistically powerful monitoring programs for detecting bottleneck-induced genetic change. We used Monte Carlo computer simulations to evaluate the power of the following tests for detecting genetic changes caused by a severe reduction in a population's effective size ( N _e): a test for loss of heterozygosity, two tests for loss of alleles, two tests for change in the distribution of allele frequencies, and a test for small N _e based on variance in allele frequencies (the 'variance test'). The variance test was most powerful; it provided an 85% probability of detecting a bottleneck of size N _e = 10 when monitoring five microsatellite loci and sampling 30 individuals both before and one generation after the bottleneck. The variance test was almost 10-times more powerful than a commonly used test for loss of heterozygosity, and it allowed for detection of bottlenecks before 5% of a population's heterozygosity had been lost. The second most powerful tests were generally the tests for loss of alleles. However, these tests had reduced power for detecting genetic bottlenecks caused by skewed sex ratios. We provide guidelines for the number of loci and individuals needed to achieve high-power tests when monitoring via the variance test. We also illustrate how the variance test performs when monitoring loci that have widely different allele frequency distributions as observed in five wild populations of mountain sheep ( Ovis canadensis ).     

Effects of exposure to electromagnetic fields emitted by GSM 900 and WCDMA mobile phones on cognitive function in young male subjects

Results of studies on the possible effects of electromagnetic fields emitted by mobile phones on cognitive functions are contradictory, therefore, possible effects of long‐term (7 h 15 min) electromagnetic field (EMF) exposure to handset‐like signals of Global System for Mobile Communications (GSM) 900 and Wideband Code‐Division Multiple Access (WCDMA) on attention and working memory were studied. The sample comprised 30 healthy male subjects (mean ± SD: 25.3 ± 2.6 years), who were tested on nine study days in which they were exposed to three exposure conditions (sham, GSM 900 and WCDMA) in a randomly assigned and balanced order. All tests were presented twice (morning and afternoon) on each study day within a fixed timeframe. Univariate comparisons revealed significant changes when subjects were exposed to GSM 900 compared to sham, only in the vigilance test. In the WCDMA exposure condition, one parameter in the vigilance and one in the test on divided attention were altered compared to sham. Performance in the selective attention test and the n‐back task was not affected by GSM 900 or WCDMA exposure. Time‐of‐day effects were evident for the tests on divided and selective attention, as well as for working memory. After correction for multiple testing, only time‐of‐day effects remained significant in two tests, resulting in faster reactions in the afternoon trials. The results of the present study do not provide any evidence of an EMF effect on human cognition, but they underline the necessity to control for time of day. Bioelectromagnetics 32:179–190, 2011. © 2010 Wiley‐Liss, Inc.     

Vigilance in Przewalski's gazelle: effects of sex, predation risk and group size

Vigilance in social animals is often aimed at detecting predators. Many social and environmental factors influence vigilance, including sex, predation risk and group size. During the summer of 2007, we studied Przewalski's gazelle Procapra przewalskii , an endemic ungulate to the Qinghai-Tibet Plateau, to test whether and how these three factors affect vigilance. We distinguished groups consisting of males, mothers with lambs and females without lambs making observations on groups in the presence or absence of nearby predators. We assessed the group-size effect on vigilance and how this varied with levels of predation risk and sex. Males and mothers scanned longer and with a higher frequency than females without lambs. Individuals were more vigilant under direct predation threat. Although vigilance generally decreased with group size, the extent of the decrease was independent of predation risk and was not significant in males. The results suggest that mothers are more vigilant suggesting greater vulnerability and that males may have increased their vigilance to compete for higher social ranks. The positive correlation between vigilance and predation risk and the negative correlation between vigilance and group size are consistent with earlier findings, but we failed to find an interaction between group size and predation risk on vigilance perhaps because vigilance levels are low even in small groups, thus making similar vigilant upward adjustments in both small and large groups.     

Effects of natural sediment properties on test results in bioassays with oyster larvae (Crassostrea gigas) on sediment elutriates

Toxicity tests with oyster larvae are becoming increasingly important as sensitive bioassays for assessing water and sediment quality. In 1983 a procedure was presented specifically for the testing of seawater elutriates of sediment samples. Testing sediment elutriates with oyster larvae in a sediment-water system invokes specific problems related to natural sediment characteristics. Experiments were set up to study the effects of these sediment properties on the bioassay results. The effects of sediment grain size, suspended solids, elutriation period, as well as the possible effects of naturally occurring toxic nutrients, like ammonia, were studied. Also the effect of presence or absence of the elutriated sediment and the distribution of larvae in the test vessels were studied.It is concluded that natural sediment properties can have substantial effects on the test results in elutriate tests with sediment present in the test vessel. Recommendations are formulated to minimize these effects or to use other test fractions for predicting bulk sediment toxicity.     

Sleeping gulls monitor the vigilance behaviour of their neighbours

Individuals in groups are often thought to scan their surroundings for threats independently of one another. Models, however, suggest that foragers should monitor the vigilance level of their neighbours to prevent cheating, and to gather information about incipient predation risk. Evidence for monitoring of vigilance is scant. Here, I examined changes in vigilance levels in sleeping gulls (Larus sp.) surrounded by neighbours in various states of alertness. Controlling for group size and neighbour density, gulls interrupted sleep more often to scan their surroundings, and were therefore more vigilant, when their neighbours were alert rather than sleeping or preening. The results provide evidence for copying of vigilance within groups of birds, suggesting a complex flow of information about predation risk in groups.     

Non-Parametric Methods for the 2-Period-Cross-Over Design Under Weak Model Assumptions

A nonparametric analysis for the two period cross-over design has first been suggested by Koch (1972) and has been discussed by Hills and Armitage (1979). As known rank tests on sums or differences of the data are applied in this procedure, the results on the one hand are not invariant under monotonous transformations and on the other hand the procedure is only correct for models with additive effects. Therefore, in the present article generalized effects will first be defined in the 2-period cross-over design without the assumption of a linear model and then rank test will be presented which test tese effects without the need of sums or differences of the data. In the appendix the equivalence of the hypothesis for the generalized effects to the known hypotheses for the effects in the linear model will be shown. The application of the procedures will be demonstrated by means of an example in literature.     

Many eyes or many ewes: vigilance tactics in female bighorn sheep Ovis canadensis vary according to reproductive status

In gregarious animals, there is usually a negative relationship between individual vigilance and group size. This effect of group size is generally explained by increasing probability of predator detection (the many-eyes hypothesis) and by the dilution of risk occurring in larger groups. Few studies have attempted to examine the specific implications of either hypothesis on the expected vigilance pattern of an animal. Here we examine whether reproductive status affects vigilance patterns in bighorn sheep Ovis canadensis ewes. We also test whether the observed vigilance patterns are consistent with predictions from dilution or detection models of vigilance. Although vigilance decreased with increasing group size, vigilance tactics differed between barren and lactating females. Lactating ewes relied solely on predator detection. In contrast, barren ewes benefited from both detection and dilution effects when group size increased and adjusted vigilance effort according to the proportion of lactating ewes in their group. It is generally assumed that gregariousness increases safety. Here we further show that reproductive status influenced how animals reduce predation risk and that some individuals take advantage of the vigilance effort provided by others.     

Adverse changes in mood and cognitive performance of house officers after night duty.

The effects of long hours of work by junior doctors are the subject of growing concern. Experimental investigations of the effects of night duty on young doctors are few and have given inconclusive results. To measure the effects of long hours of work and reduced sleep on cognitive performance and mood 20 house officers (14 men and six women; mean age 25, range 24-35) were examined for 35 minutes in one session towards the end of a normal working day and in a second session at the same time after working for up to 31 continuous hours with reduced sleep. The order of the sessions was counterbalanced across the subjects. Each session comprised a series of cognitive tests: choice reaction time, vigilance reaction time, and haptic sorting tests and completion of a profile of mood states and a general questionnaire. After night duty there was a significant slowing in cognitive processing together with a decline in reaction times in the vigilance test. Loss of sleep contributed only to increased variability in the choice reaction time. Significant deleterious changes in mood after night duty occurred in all the mood scales after night duty. Continuous working may adversely affect the cognitive function and mood to the detriment of the welfare of doctors and their patients.     

Morning Anaerobic Performance Is Not Altered by Vigilance Impairment

The aim of this study was to determine the role played by vigilance on the anaerobic performance recorded during a Wingate test performed at the bathyphase (nadir) of the circadian rhythmicity. Twenty active male participants performed a 60-s Wingate test at 6 a.m. during 3 test sessions in counter-balanced order the day after either (i) a normal reference night, (ii) a total sleep deprivation night, or (iii) a total sleep deprivation night associated with an extended simulated driving task from 9 p.m. to 5 a.m. During this task, the number of inappropriate line crossings (ILCs) was used to control and quantify the effective decrease in the level of vigilance. The main findings show that (i) vigilance of each participant was significantly altered (i.e., a drastic and progressive increase in ILCs is shown during the 7.5 hours of driving) by the sleep deprivation night associated with an extended driving task; (ii) the subjective evaluation of vigilance performed by self-rated scale revealed an increased impairment of the vigilance level between the normal reference night, the total sleep deprivation night and the total sleep deprivation night associated with an extended driving task; and (iii) the morning following this last condition, during the Wingate test, the recorded cycling biomechanical parameters (peak power, mean power and fatigue index values, power decrease, and cycling kinetic and kinematic patterns) were not significantly different from the two other conditions. Consequently, these results show that anaerobic performances recorded during a Wingate test performed at the bathyphase of the circadian rhythmicity are not altered by a drastic impairment in vigilance. These findings seem to indicate that vigilance is probably not a factor that contributes to circadian variations in anaerobic performance.     

Supraorbital transcutaneous neurostimulation has sedative effects in healthy subjects

Background

Transcutaneous neurostimulation (TNS) at extracephalic sites is a well known treatment of pain. Thanks to recent technical progress, the Cefaly^® device now also allows supraorbital TNS. During observational clinical studies, several patients reported decreased vigilance or even sleepiness during a session of supraorbital TNS. We decided therefore to explore in more detail the potential sedative effect of supraorbital TNS, using standardized psychophysical tests in healthy volunteers.

Methods

We performed a double-blind cross-over sham-controlled study on 30 healthy subjects. They underwent a series of 4 vigilance tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale, d2 test). Each subject was tested under 4 different experimental conditions: without the neurostimulation device, with sham supraorbital TNS, with low frequency supraorbital TNS and with high frequency supraorbital TNS.

Results

As judged by the results of three tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale) there was a statistically significant (p < 0.001) decrease in vigilance and attention during high frequency TNS, while there were no changes during the other experimental conditions. Similarly, performance on the d2 test was impaired during high frequency TNS, but this change was not statistically significant.

Conclusion

Supraorbital high frequency TNS applied with the Cefaly^® device decreases vigilance in healthy volunteers. Additional studies are needed to determine the duration of this effect, the underlying mechanisms and the possible relation with the stimulation parameters. Meanwhile, this effect opens interesting perspectives for the treatment of hyperarousal states and, possibly, insomnia.

     

SO2对大蒜根尖细胞遗传损伤作用的研究

研究SO2（14,35,84mg/m^2）对大蒜幼根细胞的遗传损伤效应。结果表明：大蒜幼苗短时间暴露于高浓度SO2环境中,或者长时间生长在低浓度SO2环境中,均可导致根尖细胞微核和双核频率明显增高,并引起根尖部分细胞核固缩。SO2的上述效应具有明显的时间－效应和课题－效应关系,细胞中的微核、双核及核固缩率与SO2浓度间呈线性相关,研究结果表明：SO2可引起植物细胞遗传物质的损伤,大蒜根尖细胞有可能用作监测SO2污染的生物计量计。     

Noise, predation risk compensation and vigilance in the chaffinch Fringilla coelebs

Background noise should in theory hinder detection of auditory cues associated with approaching danger. We tested whether foraging chaffinches Fringilla coelebs responded to background noise by increasing vigilance, and examined whether this was explained by predation risk compensation or by a novel stimulus hypothesis. The former predicts that only inter-scan interval should be modified in the presence of background noise, not vigilance levels generally. This is because noise hampers auditory cue detection and increases perceived predation risk primarily when in the head-down position, and also because previous tests have shown that only interscan interval is correlated with predator detection ability in this system. Chaffinches only modified interscan interval supporting this hypothesis. At the same time they made significantly fewer pecks when feeding during the background noise treatment and so the increased vigilance led to a reduction in intake rate, suggesting that compensating for the increased predation risk could indirectly lead to a fitness cost. Finally, the novel stimulus hypothesis predicts that chaffinches should habituate to the noise, which did not occur within a trial or over 5 subsequent trials. We conclude that auditory cues may be an important component of the trade-off between vigilance and feeding, and discuss possible implications for anti-predation theory and ecological processes.