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PubMed2004

Changes in alcohol involvement, cognitions and drinking and driving behavior for youth after they obtain a driver's license.

OBJECTIVE: This study tested whether obtaining a driver's license was associated with increases in alcohol and other drug involvement and changes in alcohol-related cognitions for youth, and whether drinking and driving behavior increased with driving experience. METHOD: Confidential, anonymous surveys were conducted at two time points (fall, spring) with students at four high schools in San Diego county (N = 2,865, 51% female). Data were collected on alcohol, cigarette and marijuana use, license status, alcohol use by peers, attitudes towards drinking and driving and drinking and driving behaviors. RESULTS: Nondrivers (60%), new drivers (obtained a license between Time 1 and Time 2) and experienced drivers (26%) were compared on study variables at both time points and over time. Initially obtaining a driver's license was associated with increased frequency of substance use. Results were not significant for quantity of alcohol use, frequency of heavy drinking or perceived alcohol use norms. Attitudes towards drinking and driving reflected an increase in the perceived dangerousness of this behavior for new drivers. Drinking and driving behavior during the last 30 days increased with increased driving experience. CONCLUSIONS: The results indicate a number of changes in substance involvement after obtaining a driver's license. However, initially this transition may also indicate a period of protection against drinking and driving. These results may have implications for the target and content of drinking and driving interventions.

Adolescent↗
PubMed2006

Young adult drivers' sensitivity to changes in speed and driving mode in a simple vehicle simulator.

The study was done to check replication of changes in sensitivity with a simple simulator as had been obtained in an experiment using the real road situation. Another purpose was to control simulator sickness which could have confounded data from testing with a simulator or in actual driving. Sensitivity of the drivers (72 healthy young adults, M age = 24 yr., SD = 5) while performing the driving task was measured in terms of subjective ratings of simulator sickness and affect, and physiological measures (i.e., galvanic skin responses and skin temperature) at different driving speeds and in driving mode conditions, using a simple vehicle simulator. Analysis showed measures of drivers' state, including simulator sickness, physiological indices, and subjective reports, increased with driving speed (30 --> 90 -->120 km/hr.) and driving mode change from the regular speed to sudden increasing to sudden decreasing speeds. Particularly, the results suggest that the increased autonomic nervous activation induces increase of rated simulator sickness. Based upon the same tendency in change of the simulator sickness and physiological state with driving speed and driving mode conditions, it was concluded that, if the results obtained from the simulator experiment can be generalized to the real situation, the simulator sickness must be considered a confounding factor. The results also suggest that the changes in human sensitivity are dependent upon aspects related to speed of a vehicle and driving mode.

Acceleration↗
PubMedDate not supplied

Occupational therapy assessment of open-road driving performance: validity of directed and self-directed navigational instructional components.

OBJECTIVE: The purpose of this study was to validate an assessment tool used by occupational therapists to evaluate on-road driving performance. METHODS: The driving assessment was conducted over a 15-km route that consisted of a range of traffic situations and contained both directed and self-directed navigational instruction. The driving performance of four groups of drivers of different ages and visual characteristics was assessed independently by an occupational therapist and driving instructor using a range of scoring criteria. RESULTS: The occupational therapist scores were significantly affected by the drivers' age and visual characteristics (directed navigation, F(3,133) = 6.05, p = 0.001; self-directed navigation, F(3,133) = 5.04, p < 0.002), and these group differences were greater for self-directed navigational instruction. The occupational therapist scores were highly correlated with the driving instructor's global driver safety rating (r = 0.76, p < 0.001). DISCUSSION: The driving assessment instrument was a valid measure of on-road driving performance relative to an independent global driving safety evaluation. The instrument provided detailed information regarding driving performance and highlighted areas of difficulty, particularly when drivers followed self-navigational instruction.

Adult↗
PubMed2002

Differential residual effects of zaleplon and zopiclone on actual driving: a comparison with a low dose of alcohol.

STUDY OBJECTIVES: To compare residual effects of zaleplon 10 mg, zopiclone 7.5 mg, and placebo, and a social dose of alcohol on car driving, memory, and psychomotor performance. DESIGN: Two-part placebo controlled, crossover study. Part 1 was single blind, Part 2 double blind. SETTING: University research institute. PARTICIPANTS: Thirty healthy volunteers (15 men and 15 women, mean age 32 +/- 7 years) INTERVENTIONS: In Part 1 alcohol and alcohol-placebo drinks were administered around noon. In Part 2 single oral doses of zaleplon 10 mg, zopiclone 7.5 mg and placebo were administered at bedtime. MEASUREMENT AND RESULTS: A highway driving test, laboratory tests of word learning, critical tracking and divided attention, and subjective assessments of sleep, mood, and effects of treatments on driving. Driving started 40 minutes after a second alcohol dose in Part 1, and 10 hours after drug intake in Part 2. The results demonstrated that alcohol, at average plasma concentrations of approximately 0.030 g/dl, significantly impaired performance in all tests. Zaleplon's residual effects did not differ significantly from those of placebo in any test. In contrast, zopiclone had significant residual effects on driving, divided attention, and memory. The magnitude of impairment in the driving test observed the morning after zopiclone 7.5 mg was twice that observed with alcohol. CONCLUSION: Zaleplon 10 mg has no residual effects on driving when taken at bedtime, 10 hours before driving. In contrast, zopiclone 7.5 mg can cause marked residual impairment. Patients should be advised to avoid driving the morning after zopiclone administration.

Acetamides↗
PubMed2002

Can patients taking opioids drive safely? A structured evidence-based review.

A structured evidence-based literature review was completed to determine if there was epidemiological evidence of an association of opioid use and intoxicated driving, motor vehicle accidents (MVA) and MVA fatalities; to rate the quality of this research evidence according to Agency for Health Care Policy and Research (AHCPR) type of evidence and strength and consistency of the evidence rating scales; and according to this evidence determine whether patients taking opioids can drive safely. Relevant references were located from Medline, Psychological Abstracts, Science Citation Index and the National Library of Medicine Data Query databases by appropriate subject headings. A manual search was also performed utilizing the reference lists of the retrieved articles. All references relating to intoxicated driving, MVA and MVA fatalities were retrieved and reviewed in detail. Of these, references addressing opioid use were isolated and research information from these references was placed into tabular form under three major headings: Intoxicated driving and opioids; MVA and opioids; and MVA fatalities and opioids. Data were extracted from these references according to the following format: research question addressed, sample size, statistical analysis and results. The type of evidence each study represented was rated according to the AHCPR type of evidence rating scale. Each research area (intoxicated driving, MVA, MVA fatalities) represented by all the studies in each table was then rated utilizing the strength and consistency of the evidence AHCPR rating scale. Of the 6 reports addressing intoxicated driving, 5 were well designed non-experimental studies and one was a well designed experimental study. All studies in this group reported a prevalence for opioid use which was approximately 1/10 that of the point prevalence use for opioids in the general population. This evidence indicated that opioids probably are not associated with intoxicated driving. Overall, the evidence indicates that opioids are not associated with MVA. Of the 9 studies addressing MVA, 5 were well designed quasi-experimental studies and 4 were well designed experimental studies. All reports in this group except one indicated that opioids are not associated with MVA. Of the 10 studies addressing MVA fatalities, 10 represented Type IV studies. For the vast majority of the studies, the prevalence percentages for an opioid association with MVA fatalities was 1/5 that of the point prevalence percentage for opioid use reported in the general population. Only 1 study reported a possible association between opioid use and MVA fatalities. The evidence in this review indicates that opioids do not appear to be associated with intoxicated driving, MVA and MVA fatalities, and consistently indicated that opioids are not associated with MVA. Although the comparison of point prevalence rates to the point prevalence may be problematic, the results of this systematic review support the contention that patients taking opioids may be allowed to drive. As in all clinical decisions, this determination should be individualized according to clinical factors.

Accidents, Traffic↗
PubMed1983

[Applied physiology: the work of driving an industrial heavy-duty truck on the highway].

Scope of this work was the investigation of the following parameters: energetic metabolism, by O2 consumption measurement using the open-circuit technique; pulmonary ventilation; cardio-circulatory activity behaviour, by recording heart rate, E.C.G., arterial blood pressure and plethysmography of lower limbs; body temperature pattern; visual function, through the determination of the visual field; kidney function through urine analysis; body joints flexibility, by proper test. The subjects chosen for this investigation are three experienced heavy-duty vehicle drivers that where submitted to proper checks before, during and after having driven a 190.38 Model truck fitted with spoiler and an S.R. Viber, high cargo body tarpaulin, PTT, 43.2 tons overall weight truck, over 9 different courses including town traffic, level highway, up and downhill highway with different gradients, in a period from 9 a.m. to 8 p.m. Along the total run of 404 kilometres, covered in 364 minutes, recording of the parameters under investigation was carried out over 249 kilometres covered 240 minutes (72% of overall driving time). Energy expenditure (1.20 +/- .19 Kcal/min at rest) resulted higher on steep uphill stretches with many bends (2.28 +/- .44 Kcal/min) than on less steep up- and downhill stretches and in city traffic (1.82 +/- .21 Kcal/min). The lowest energy expenditure--in some cases lower than the value found in the experimental rest--was recorded during motorway driving (1.28 +/- .19 Kcal/min). Pulmonary ventilation was characterized by frequent changes in rate and tidal air, in strict relationship with driving work bio-mechanical requirements (operation of the steering wheel). Also heart rate underwent ariations well in line with the energy expenditure pattern: of limited magnitude in uphill driving (+33% max over the value at rest), up to values identical with those at rest in the level highway drive. No appreciable variations were recorded in the respiratory quotient, calories/ventilation ratio and oxygen pulse. No significant changes occurred in arterial blood pressure, body temperature, auditory, visual and kidney functions, and in flexibility. Conversely, slight swelling (5%) of lower limbs was noticed at the end of the driving day. It was hence proven that--from the standpoint of energy expenditure--the work performed in driving a vehicle is not too exacting and does not induce particularly high nervous stresses. However, under given conditions, such as steady speed driving in level highway, a pre-sleep state occurs in all cases approximately after the first 30 minutes of driving, which in most cases the driver is not even aware of.(ABSTRACT TRUNCATED AT 400 WORDS)

Automobile Driving↗
PubMed1995

Drivers' differential perceptions of legal and safe driving consumption.

UK drink-drive countermeasures have been grounded in deterrence theory and more specifically through per se legislation. Education and information campaigns to stimulate inhibitory behavioural systems have emphasized the legal limit in terms of "driving safeness". This study examined the relationship between subjective perceptions of safe driving and legal driving consumption limits and other factors important in the decision to drive after drinking. Responses from over 900 drivers established that those who perceived safe consumption levels to be greater than that required to break the law indicated reduced moral commitment to present and possible future countermeasures. These drivers also had previous experience of being breath tested (but not charged with a drink-driving offence), reported comparatively lower estimates of their chances of apprehension and accident involvement when over the legal limit, showed higher consumption levels on a driving trip and greater self-reported driving while impaired by alcohol. The implications of the findings for the development and delivery of measures to counter drink-driving are discussed.

Adolescent↗
PubMed1995

Alzheimer and vascular dementias and driving. A prospective road and laboratory study.

OBJECTIVE: To characterize on-the-road, behind-the-wheel driving abilities and related laboratory performances of subjects with mild Alzheimer's disease (AD) and vascular dementia. DESIGN: Prospective, experimental study involving two mild dementia and three age and health control groups. Road test reliability and validity were assessed. SETTING: Greater western Los Angeles. Subjects were enrolled from the community by referral and from the Veterans Affairs dementia and diabetes clinics. PARTICIPANTS: Eighty-seven driving subjects were enrolled; 83 completed the study. A sample of eligible dementia clinic subjects consisting of 15 mild AD patients met National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association probable AD criteria, while 12 met Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition and Hachinski diagnostic criteria for multi-infarct dementia (vascular dementia). Clinic control subjects consisted of 15 age-matched patients with diabetes and without a history of stroke or dementia. Community controls consisted of 26 healthy, age-matched, older subjects (> 60 years) and 16 young subjects (20 to 35 years). MAIN OUTCOME MEASURES: Drive score from the Sepulveda (Calif) road test and laboratory measures of attention, perception, and memory. RESULTS: The drive scores in the mild AD group (mean, 22.1; SD, 3.8) and in the vascular dementia group (mean, 24.0; SD, 7.8) differed significantly (P < .001 studentized range test) from the drive scores in the diabetic control group (mean, 31.5; SD, 3.9), the older control group (mean, 32.6; SD, 2.8), and the young control group (mean, 33.6; SD, 3.2). Drive score among the three control groups did not vary significantly. Short-term memory (Sternberg), visual tracking, and Folstein Mini-Mental State Examination scores correlated best with drive score, with a cumulative R2 of 0.68. Drive score and number of collisions and moving violations per 1000 miles driven were negatively correlated (r = -0.38; P < .02). CONCLUSIONS: Based on this study, type and degree of cognitive impairment are better predictors of driving skills than age or medical diagnosis per se. Specific testing protocols for drivers with potential cognitive impairment may detect unsafe drivers more effectively than using age or medical diagnosis alone as criteria for license restriction or revocation.

Adult↗
PubMed1997

[Driving licence renewal in persons with Parkinson disease].

INTRODUCTION: The legal requirement to renew a driving licence is feared by most symptomatic or already formally diagnosed individuals with Parkinson's disease (PD) as the medical assessment they are required to submit may eventually conclude in withdrawal of their driving licence. OBJECTIVE AND METHODS: The purpose of our study was to gain information about PD patients applying for a driving licence renovation and their willingness to uncover his or her illness to medical personnel in charge, and how often current medical assessment procedures proved unable to detect abnormalities among parkinsonian applicants who retain data on their health status. Using a confidential, 'face-to-face' questionnaire, we obtained information from 62 licensed parkinsonian drivers (32 current drivers) and 120 age and sex matched drivers controls gathered from an identical socioeconomic background. RESULTS: Thirty eight individuals with symptomatic PD (in 30 of who the disorder has been already diagnosed) applied with a view to licence renovation. Drivers with PD did not retain information regarding their health status more often than sex- and age-matched control drivers with various other chronic ailments as 63.1% and 77% respectively, abstained from declaring (z = 0.945; p = 0.344). A parkinsonian subject illegally managed to renew his driving licence without submission to any medical assessment. The attending physicians perceived abnormalities related to motor difficulties in 30.4% of those parkinsonian who withdrew information. A similar proportion of controls (29.1%) were also informed about health problems during their medical assessment, in the vast majority related to sight problems. CONCLUSIONS: Overall, the exam concluded in cancellation of the driving licence in 10.8% of the parkinsonian and 1.6% of the controls, a significant difference (z = 2.075; p = 0.03). We conclude that at the time of renewal of a driving licence parkinsonian patients do not retain problems related to fitness to drive more often than the general population afflicted by other medical conditions do. However, current tests for driving performance appears to be not sensitive enough to detect selective difficulties in motor execution tasks that may impair driving ability in persons with PD.

Aged↗
PubMed1993

Effect of flexible drive diameter and reamer design on the increase of pressure in the medullary cavity during reaming.

Reaming the medullary cavity before insertion of an intramedullary nail, results in an increase in both temperature and pressure. This may lead to aseptic necrosis of the cortex and to fat embolism, whereby the increased pressure in the medullary cavity plays a significant role. This paper aims to determine whether a reduction of the drive diameter combined with a different reamer design reduces the amount of intramedullary pressure. The pressure levels were measured in plexiglass tubes filled with a mixture of vaseline and paraffin. The viscoelastic properties of this mixture at 20 degrees C were equivalent to those of bovine medullary fat at 36 degrees C. In comparison with the conventional reamer system (9.0 mm drive + 9.5 mm AO reamer), the 7.0 mm drive+AO reamer and the 7.0 mm drive+hollow reamer, the pressure values were reduced as follows: 1. 9.0 mm drive + 9.5 mm hollow reamer: diaphyseally by 19%, metaphyseally by 21% 2. 7.0 mm drive + 9.5 mm AO reamer: diaphyseally by 48%, metaphyseally by 49% 3. 7.0 mm drive + 9.5 mm hollow reamer: diaphyseally by 61%, metaphyseally by 66%. If the gap between the flexible shaft and the wall of the plexiglass tube became large enough, only small pressure values were recorded for all three types of reamer. In summary, it can be stated that the reduction of the drive diameter causes a sustained reduction in the intramedullary pressure, but that the newly developed hollow reamer only leads to a further reduction in pressure in combination with a thin flexible drive.

Equipment Design↗
PubMed2000

Perception of traffic accident risk and decision to drive under light alcohol consumption--a double-blind experimental study.

PURPOSE: Public traffic safety campaigns in Germany have focussed on the changing risk perception of young drivers. While there is some consensus that perceptions of risk affect driving, less is understood about the relationship and interaction of alcohol consumption and risk perception on the decision to drive. We examined the influence of light alcohol consumption on risk perception and decision to drive, and the interaction of alcohol consumption and cognitive feedback on the handicapping effect of alcohol on risk perception and decision to drive. METHOD: In a double-blind block-randomized experimental study of 104 young drivers between 19 and 24 years of age, with two experimentally manipulated independent factors of alcohol consumption (three levels: 0% BAC, 0.015% BAC, 0.03% BAC) and feedback (positive or negative), we assessed three dependent variables: perception of traffic accident risk, subjective judgement about driving-relevant cognitive performance, decision to drive a car. Analyses of variance and covariance were used to analyze differences between levels of experimental factors. RESULTS: We found that persons with 0.015 BAC performed better than persons in both other alcohol conditions on the standardized risk perception task. Perceived handicap of driving was significantly more pronounced for negative feedback compared to positive feedback with no influence of the level of alcohol consumption. No significant influence on decision to drive was found of either level of alcohol consumption, feedback or sex. IMPLICATIONS: Decision to drive in young drivers could not be influenced by feedback or light consumption. Public health approaches have to find better determining factors.

Accidents, Traffic↗
PubMed2000

Speed freaks? A literature review detailing the nature and prevalence of dance drugs and driving.

Considerable interest has lately been expressed in motor car driving whilst under the influence of drugs. Unlike depressant drugs (e.g. alcohol) dance drugs are often perceived to enhance driving skills. The physical effects and the current lack of police roadside testing are possible contributing reasons for dance drug driving. This paper aims to show through a literature review on the subject, the demographics of those involved in dance drug driving and the extent to which certain dance drugs are implicated in drug driving incidents. Drug driving is found to be highest amongst the 18-35 year age group and more prevalent amongst adult males. Prevalence figures for driving under the influence of individual drugs are also given. The numbers of people involved in accidents/fatalities and testing positive for amphetamine, cocaine and other dance drugs is small. Although self-reporting especially of illegal activities is difficult to accurately evaluate, most of the reported studies use actual blood/urine samples and so can be considered accurate. The literature does not highlight any real concerns regarding dance drug driving in terms of prevalence although it does highlight the paucity of research in this area, in particular 'Culture E and driving'.

Journal Article↗
PubMed1998

Lambda waves: incidence and relationship to photic driving.

The earliest studies on lambda waves in the 1950s postulated a relationship with the photic driving response. Intracranial depth electrode studies from the 1960s showed generators for lambda waves and the occipital driving response to be different but both originating from the posterior hemisphere. Use of computer averaging techniques in the 1980s found these two cerebral responses to be similarly affected by certain diseases. We examined the incidence of lambda over a wider range of ages than previously studied, and also evaluated for a statistical correlation between lambda and occipital driving. Three hundred sixty-seven conventional EEGs were prospectively collected and analyzed. Each record was interpreted for the presence of lambda waves, photic driving, and epileptiform discharges. The incidence of lambda waves, photic driving and epileptiform discharges was 76%, 85%, and 23%, respectively. The incidence of lambda and photic driving exhibited age-dependent characteristics. The amplitude and duration of lambda waves also exhibited age-dependent characteristics. A strong correlation existed between the presence of lambda waves and photic driving (p< 0.001). No significant correlation existed between epileptiform discharges and either lambda waves or photic driving. The strong correlation between the presence of lambda waves and the occipital photic driving response suggests the possibility a common region in the brain needs to be functionally activated in order to express these waveforms.

Adolescent↗
PubMed1996

Drinking and driving: drinking patterns and drinking problems.

Two perspectives guide examinations of alcohol-related injury; studies of drinking behaviors which characterize the activities in which drinkers participate, and studies of drinking patterns which characterize individuals' likelihoods of intoxication. This paper presents a study of self-reported drinking and driving using both perspectives. A theoretical model of the relationships of drinking patterns and drinking behaviors to drinking and driving is derived. This model is used as the basis for analyses of self-reports of driving after drinking and driving while intoxicated. Using cross-sectional data from a study of alcohol-related injury in the United States, these self-reports were related to measures of respondent socio-demographics, drinking patterns, beverage preferences and routine activities. The results showed: (1) that the drinking pattern measures were significantly related to likelihoods of drinking and driving; (2) these measures were superior to alternate measures of drinking patterns in their ability to explain drinking and driving; (3) the measures of beverage preferences were unrelated to either measure of drinking and driving; and (4) that the utilization of certain venues for drinking (bars and restaurants) was significantly related to both measures of drinking and driving. It is concluded that observed socio-demographic differences in drinking and driving (e.g. related to ethnicity and marital status) are due to related differences in drinking patterns and drinking behaviors.

Accidents, Traffic↗
PubMed2001

Clinical significance of the arthroscopic drive-through sign in shoulder surgery.

PURPOSE: During arthroscopy of the shoulder, the ability to pass the arthroscope easily between the humeral head and the glenoid at the level of the anterior band of the inferior glenohumeral ligament is considered a positive drive-through sign. The drive-through sign has been considered diagnostic of shoulder instability and has been associated with shoulder laxity and with SLAP lesions. The goal of this study was to examine the prevalence of the drive-through sign in patients undergoing shoulder arthroscopy and to determine its relationship to shoulder instability, shoulder laxity, and to SLAP lesions. TYPE OF STUDY: Case series. METHODS: We prospectively studied 339 patients undergoing arthroscopy of the shoulder for a variety of diagnosis from 1992 to 1998. The drive-through sign was performed with the patients in a lateral decubitus position and under general anesthesia. The drive-through sign was correlated with preoperative physical findings, intraoperative laxity testing, and with intra-articular pathology at the time of arthroscopy. RESULTS: The arthroscopic evaluation showed that drive-through sign was positive in 234 (69%) shoulders. For the diagnosis of instability, the drive-through sign had a sensitivity of 92%, a specificity of 37. 6%, a positive predictive value of 29.9%, a negative predictive value of 94.2%, and an overall accuracy of 49%. There was an association between the drive-through sign and increasing shoulder laxity, but not with SLAP lesions. CONCLUSIONS: This study shows that a positive drive-through sign is not specific for shoulder instability but is associated with shoulder laxity. This arthroscopic sign should be incorporated with other factors when considering the diagnosis of instability.

Adolescent↗
PubMed1993

Perceived exertion and discomfort associated with driving screws at various work locations and at different work frequencies.

Eighteen subjects drove screws with air-powered tools into perforated sheet metal at three vertical and two horizontal work locations using three different work paces (8, 10, and 12 screws/min). Subjects drove screws with a pistol-shaped tool on the vertical orientation at knee, elbow, and shoulder height. They used an in-line tool to drive screws on the horizontal surface. A horizontal beam was placed just below each subject's elbow height and they drove screws into it with the lower arm perpendicular to the torso and with the arms fully extended. Subjects drove screws for 10 min at each work location and frequency combination before they assessed the condition using the Borg ten-point ratio rating scale. Subjects also ranked seven body areas according to discomfort for each work location. A two-factor ANOVA (and comparable non-parametric statistics) showed that both work location and frequency were significant factors in determining the Borg ratings. As work pace increased, so did the Borg ratings of perceived exertion for each work location. For each incremental increase in work pace, the Borg ratings of perceived exertion increased 12% to 25%, depending on the work location. Driving screws at elbow height on the vertical surface and with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived exertion. The ratings of perceived exertion for driving screws at elbow height on the vertical surface were 18% to 50% lower than the ratings for driving screws at knee or shoulder height and the ratings of perceived exertion for driving screws with the lower arm close to the body on the horizontal surface were 21% to 24% lower than driving screws with the arms fully extended. No significant difference was found among the discomfort ranks given to the various body parts for the two horizontal work locations. Differences were found among the body part discomfort rankings for the vertical work locations. While driving screws at knee height, the torso was most stressed; the wrist and hand were most stressed while driving screws at elbow height, and the shoulder and upper arm were the body parts that were stressed the most while driving screws at shoulder height.

Adult↗
PubMed1999

Meiotic drive of chromosomal knobs reshaped the maize genome.

Meiotic drive is the subversion of meiosis so that particular genes are preferentially transmitted to the progeny. Meiotic drive generally causes the preferential segregation of small regions of the genome; however, in maize we propose that meiotic drive is responsible for the evolution of large repetitive DNA arrays on all chromosomes. A maize meiotic drive locus found on an uncommon form of chromosome 10 [abnormal 10 (Ab10)] may be largely responsible for the evolution of heterochromatic chromosomal knobs, which can confer meiotic drive potential to every maize chromosome. Simulations were used to illustrate the dynamics of this meiotic drive model and suggest knobs might be deleterious in the absence of Ab10. Chromosomal knob data from maize's wild relatives (Zea mays ssp. parviglumis and mexicana) and phylogenetic comparisons demonstrated that the evolution of knob size, frequency, and chromosomal position agreed with the meiotic drive hypothesis. Knob chromosomal position was incompatible with the hypothesis that knob repetitive DNA is neutral or slightly deleterious to the genome. We also show that environmental factors and transposition may play a role in the evolution of knobs. Because knobs occur at multiple locations on all maize chromosomes, the combined effects of meiotic drive and genetic linkage may have reshaped genetic diversity throughout the maize genome in response to the presence of Ab10. Meiotic drive may be a major force of genome evolution, allowing revolutionary changes in genome structure and diversity over short evolutionary periods.

Chromosome Aberrations↗
PubMed2003

Four loci on abnormal chromosome 10 contribute to meiotic drive in maize.

We provide a genetic analysis of the meiotic drive system on maize abnormal chromosome 10 (Ab10) that causes preferential segregation of specific chromosomal regions to the reproductive megaspore. The data indicate that at least four chromosomal regions contribute to meiotic drive, each providing distinct functions that can be differentiated from each other genetically and/or phenotypically. Previous reports established that meiotic drive requires neocentromere activity at specific tandem repeat arrays (knobs) and that two regions on Ab10 are involved in trans-activating neocentromeres. Here we confirm and extend data suggesting that only one of the neocentromere-activating regions is sufficient to move many knobs. We also confirm the localization of a locus/loci on Ab10, thought to be a prerequisite for meiotic drive, which promotes recombination in structural heterozygotes. In addition, we identified two new and independent functions required for meiotic drive. One was identified through the characterization of a deletion derivative of Ab10 [Df(L)] and another as a newly identified meiotic drive mutation (suppressor of meiotic drive 3). In the absence of either function, meiotic drive is abolished but neocentromere activity and the recombination effect typical of Ab10 are unaffected. These results demonstrate that neocentromere activity and increased recombination are not the only events required for meiotic drive.

Centromere↗