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Summary: The intricate and interconnecting reactions of C3 photosynthesis are often limited by one of two fundamental processes: the conversion of solar energy into chemical energy, or the diffusion of CO2 from the atmosphere through the stomata, and ultimately into the chloroplast. In this review, we explore how the contributions of stomatal morphology and distribution can affect photosynthesis, through changes in gaseous exchange. The factors driving this relationship are considered, and recent results from studies investigating the effects of stomatal shape, size, density and patterning on photosynthesis are discussed. We suggest that the interplay between stomatal gaseous exchange and photosynthesis is complex, and that a disconnect often exists between the rates of CO2 diffusion and photosynthetic carbon fixation. The mechanisms that allow for substantial reductions in maximum stomatal conductance without affecting photosynthesis are highly dependent on environmental factors, such as light intensity, and could be exploited to improve crop performance. Significance Statement: Plant photosynthesis relies on diffusion of CO2 from the atmosphere to the chloroplasts through the stomatal pores. The distribution and morphological characteristics of stomata influence this and are of particular importance when attempting to understand or improve on rates of carbon fixation. Nonetheless, alterations expected to affect stomatal conductance do not always cause corresponding alterations in photosynthetic carbon assimilation. This review explores the factors that are likely to cause this observed disconnect between maximum stomatal conductance and photosynthesis. [ABSTRACT FROM AUTHOR]

Summary: Much of humanity relies on rice (Oryza sativa) as a food source, but cultivation is water intensive and the crop is vulnerable to drought and high temperatures. Under climate change, periods of reduced water availability and high temperature are expected to become more frequent, leading to detrimental effects on rice yields.We engineered the high‐yielding rice cultivar 'IR64' to produce fewer stomata by manipulating the level of a developmental signal. We overexpressed the rice epidermal patterning factor OsEPF1, creating plants with substantially reduced stomatal density and correspondingly low stomatal conductance.Low stomatal density rice lines were more able to conserve water, using c. 60% of the normal amount between weeks 4 and 5 post germination. When grown at elevated atmospheric CO2, rice plants with low stomatal density were able to maintain their stomatal conductance and survive drought and high temperature (40°C) for longer than control plants. Low stomatal density rice gave equivalent or even improved yields, despite a reduced rate of photosynthesis in some conditions.Rice plants with fewer stomata are drought tolerant and more conservative in their water use, and they should perform better in the future when climate change is expected to threaten food security. [ABSTRACT FROM AUTHOR]

We have developed a novel human laboratory model to examine two primary aspects of stress-precipitated tobacco relapse: (1) Does stress reduce the ability to resist the first cigarette? (2) Once the first cigarette is initiated, does stress facilitate subsequent smoking? Using a within-subject design, daily smokers (n = 37) who were nicotine deprived overnight received a personalized imagery induction (stress or neutral) on two separate days, and then had the option of initiating a tobacco self-administration session or delaying initiation for up to 50 min in exchange for three levels of monetary reinforcement. Subsequently, the tobacco self-administration session entailed a 1-hour period in which subjects could choose to smoke using a smoking topography system. Following the stress induction, subjects were less able to resist smoking, smoked more intensely (increased puffs, shorter inter-puff interval, and greater peak puff velocity), and perceived greater satisfaction and reward from smoking. Stress significantly increased hypothalamus— pituitary—adrenal (HPA) axis reactivity, tobacco craving, negative emotion, and physiologic reactivity relative to the neutral condition. In addition, increased cortisol, ACTH, and tobacco craving were associated with reduced ability to resist smoking following stress. These findings have implications for understanding the impact of stress on smoking relapse and model development to assess smoking lapse behavior. [ABSTRACT FROM PUBLISHER]

Background: Nondaily smoking and heavy alcohol use are prevalent behaviors among young adults, with nondaily smoking occurring primarily in the context of alcohol use. Although the relationship between drinking and daily smoking has been well characterized in young adults, few epidemiological investigations have investigated the association between nondaily smoking and drinking behavior. Methods: We examined Wave 1 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; Grant et al., 2003b ; n = 43,093). Young adults (aged 18 to 25 years; n = 5,838) were stratified on current smoking behavior (daily, nondaily, and nonsmokers in the past 12 months) and differences in weekly quantity of alcohol use, frequency of alcohol use, frequency of binge drinking behavior, rates of NIAAA-defined hazardous drinking, and rates of DSM-IV alcohol diagnoses were investigated. College student status was examined. Results: Twenty-five percent were current smokers and 7% were smoking on a nondaily basis. Seventy-one percent were current drinkers, 39% reported binge drinking at least once a month, 41% met criteria for hazardous drinking, and 18% had alcohol use disorders. Across all measures of alcohol use, there was a significant effect of smoking status, with daily smokers having greater alcohol use patterns, compared with nondaily smokers, with nonsmokers consuming the least. Nondaily smokers were more likely to report any binge drinking in the past 12 months. However, daily smokers were more likely to report daily binge drinking. With regard to hazardous drinking and alcohol use disorders, nondaily smoking conferred the greatest risk, followed by daily smoking with nonsmoking as the reference group. Multinomial logistic regression demonstrated that the odds of being a hazardous drinker were 16 times greater (95% CI 9.46–26.48) in a nondaily smoker compared with a nonsmoker, whereas the odds for a daily smoker were increased by 7-fold (95% CI 5.54–9.36). A similar pattern of results was demonstrated for DSM-IV alcohol diagnoses. No differences across college student status were observed. Conclusions: The increased risk of hazardous drinking and alcohol use disorders conferred by nondaily smoking supports the findings that nondaily smoking and drinking are highly concomitant behaviors. Results such as these suggest that interventions disengaging alcohol and cigarette use patterns (e.g., smoking bans in alcohol venues) might serve to limit the occurrence of hazardous drinking among young adults at heightened risk for this behavior. [ABSTRACT FROM AUTHOR]

Background: Binge drinking (heavy episodic alcohol use) is associated with high rates of impaired driving and myriad alcohol-related accidents. However, the underlying reasons for the heightened accident risk in this demographic group are not known. This research examined acute alcohol effects on simulated driving performance and subjective ratings of intoxication and driving ability in binge and nonbinge drinkers. Methods: Young social drinking college students (24 binge drinkers and 16 nonbinge drinkers) participated in this study. Participants attended a session during which they received a moderate dose of alcohol (0.65 g/kg) and a session during which they received a placebo. A simulated driving task measured participants’ driving performance in response to each dose. Subjective responses to each dose were also assessed, including ratings of sedation, stimulation, and driving ability. Results: The acute dose of alcohol impaired multiple aspects of driving performance in both binge and nonbinge drinkers. Under alcohol, all participants had greater difficulty in maintaining their lane position, maintaining the appropriate speed and made multiple driving errors compared to placebo performance. By contrast, compared with nonbinge drinkers, binge drinkers reported feeling less sedated by the alcohol and reported having a greater ability to drive following the acute dose of alcohol. Conclusions: Reduced subjective intoxication and perceived driving impairment in binge drinkers may account for the greater accident risk in this demographic group. Binge drinkers may lack the internal sedation cue that helps them accurately assess that they are not able to effectively drive a vehicle after drinking. [ABSTRACT FROM AUTHOR]

Background and Objectives: Limiting alcohol consumption may help prevent alcohol-mediated smoking relapse in heavy drinking smokers. This pilot study examined whether combining a nicotine patch with nicotine nasal spray has stronger attenuating effects on alcohol response and consumption than a nicotine patch alone., Methods: Twenty-two non-alcohol dependent heavy drinking smokers completed the double-blind cross-over, placebo-controlled study (21 mg nicotine patch + nicotine or placebo nasal spray). Six hours after 21 mg nicotine patch application, subjective and physiological responses to a priming drink (0.3 g/kg) were assessed, followed by two 1-hr alcohol self-administration periods, with possible consumption of up to 4 drinks per period (each 0.15 g/kg). Nasal spray (1 mg [active] or 0 mg [placebo] per dose) was administered 10 min prior to the priming dose and each self-administration period., Results: Active nasal spray did not increase serum nicotine levels, compared with placebo administration. The number of drinks consumed did not differ by the nasal spray conditions. However, positive subjective responses to the priming drink were lower in the active nasal spray condition than the placebo nasal spray condition. During the self-administration period, urge to drink was also lower in the active spray condition than the placebo condition., Conclusions and Scientific Significance: Augmenting the nicotine patch with nicotine nasal spray attenuated positive subjective alcohol response and craving and suggests that future studies should investigate whether these findings translate to a clinical setting., (Copyright © American Academy of Addiction Psychiatry.)

Background: Substance use disorders and obesity are often inversely related to one another, hypothetically due to competition over shared neurobiological reward circuitry. However, obesity and substance use disorders share common risk factors, such as other psychiatric disorders. It is unknown whether the inverse relationship between obesity and substance use disorders continues to exist in the presence of shared risk factors., Methods: For the current study, we examined the associations between major depression, alcohol and drug use disorders, and overweight/obesity status in a nationally representative sample of U.S. adults (n=40,715)., Results: Our findings demonstrated that adults with major depression were more likely to be obese, whereas adults with alcohol or drug use disorders were less likely to be obese. However, the inverse relationship between substance use and obesity continued to exist in adults with co-morbid depression. Adults with depression disorders co-morbid with alcohol (Relative Risk [RR]=0.63, 95% CI=0.47-0.84) or drug (RR=0.54, 95% CI=0.36-0.81) use disorders were less likely to be obese vs normal weight., Conclusions: Our findings provide support for the proposal that excess food consumption and excess drug use appear to compete over shared neurobiology even when the motivation to self-medicate with either food or substances might be elevated., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Background: It is known that daily smoking is associated with the development of alcohol use disorders. However, non-daily smoking is prevalent in young adults and is associated with increased rates of problematic alcohol use in cross-sectional data. It is unknown whether non-daily smoking is predictive of hazardous drinking and alcohol use disorders using longitudinal data. The primary aim of the present investigation was to explore the temporal relationship between non-daily smoking and drinking in young adults, and secondarily, whether college status modified this relationship., Methods: Using Waves 1 (2001-2002) and 2 (2004-2005) of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC), we examined the predictive relationship of smoking status at Wave 1 and change in college status between Waves on alcohol drinking, hazardous drinking, and alcohol abuse and dependence disorders at Wave 2. The sample was restricted to individuals aged 18-25 years at Wave 1., Findings: Daily and non-daily smokers at Wave 1, compared to nonsmokers, were at a greater risk for hazardous drinking and alcohol use disorders at Wave 2, after controlling for Wave 1 drinking. College status did not modify smoking and drinking interactions., Conclusions: The findings indicate non-daily smoking is predictive of increased, problematic alcohol use among young adults longitudinally and they support increasing evidence that non-daily smokers represent an important population. Future research should be conducted to continue developing targeted interventions. Early treatments for smoking behavior might have a beneficial effect on reducing the development of problematic patterns of alcohol use and alcohol use disorders., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Background: Recognition of the risks associated with alcohol intoxication and driver distraction has led to a wealth of simulated driving research aimed at studying the adverse effects of each of these factors. Research on driving has moved beyond the individual, separate examination of these factors to the examination of potential interactions between alcohol intoxication and driver distraction. In many driving situations, distractions are commonplace and might have little or no disruptive influence on primary driving functions. Yet, such distractions might become disruptive to a driver who is intoxicated., Methods: The present study examined the interactive impairing effects of alcohol intoxication and driver distraction on simulated driving performance in 40 young adult drivers using a divided attention task as a distracter activity. The interactive influence of alcohol and distraction was tested by having drivers perform the driving task under four different conditions: 0.65 g/kg alcohol; 0.65 g/kg alcohol+divided attention; placebo; and placebo+divided attention., Results: As hypothesized, divided attention had no impairing effect on driving performance in sober drivers. However, under alcohol, divided attention exacerbated the impairing effects of alcohol on driving precision., Conclusions: Alcohol and distraction continue to be appropriate targets for research into ways to reduce the rates of driving-related fatalities and injuries. Greater consideration of how alcohol and distraction interact to impair aspects of driving performance can further efforts to create prevention and intervention measures to protect drivers, particularly young adults., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Individuals with schizophrenia have higher plasma nicotine levels in comparison to non-psychiatric smokers, even when differences in smoking are equated. This difference may be related to how intensely cigarettes are smoked but this has not been well studied. Mecamylamine (MEC), a non-competitive nicotinic acetylcholine receptor (nAChR) antagonist, which has been shown to increase ad-lib smoking and to affect smoking topography, was used in the current study as a pharmacological probe to increase our understanding of smoking behavior, smoking topography, and resulting nicotine levels in smokers with schizophrenia. This preliminary study used a within-subject, placebo-controlled design in smokers with schizophrenia (n=6) and healthy control smokers (n=8) to examine the effects of MEC (10mg/day) on ad-lib smoking behavior, topography, nicotine levels, and tobacco craving across two smoking deprivation conditions (no deprivation and 12-h deprivation). MEC, compared to placebo, increased the number of cigarettes smoked and plasma nicotine levels. MEC increased smoking intensity and resulted in greater plasma nicotine levels in smokers with schizophrenia compared to controls, although these results were not consistent across deprivation conditions. MEC also increased tobacco craving in smokers with schizophrenia but not in control smokers. Our results suggest that antagonism of high-affinity nAChRs in smokers with schizophrenia may prompt compensatory smoking, increasing the intensity of smoking and nicotine exposure without alleviating craving. Further work is needed to assess whether nicotine levels are directly mediated by how intensely the cigarettes are smoked, and to confirm whether this effect is more pronounced in smokers with schizophrenia.

Background: Alcohol and tobacco dependence are highly comorbid disorders, with preclinical evidence suggesting a role for nicotinic acetylcholine receptors (nAChRs) in alcohol consumption. Varenicline, a partial nicotinic agonist with high affinity for the alpha4beta2 nAChR receptor, reduced ethanol intake in rodents. We aimed to test whether varenicline would reduce alcohol consumption and alcohol craving in humans., Methods: This double-blind, placebo-controlled investigation examined the effect of varenicline (2 mg/day vs. placebo) on alcohol self-administration using an established laboratory paradigm in non-alcohol-dependent heavy drinkers (n = 20) who were daily smokers. Following 7 days of medication pretreatment, participants were first administered a priming dose of alcohol (.3 g/kg) and subjective, and physiologic responses were assessed. A 2-hour alcohol self-administration period followed during which participants could choose to consume up to 8 additional drinks (each .15 g/kg)., Results: Varenicline (.5 +/- SE = .40) significantly reduced the number of drinks consumed compared to placebo (2.60 +/- SE = .93) and increased the likelihood of abstaining from any drinking during the self-administration period. Following the priming drink, varenicline attenuated alcohol craving and reduced subjective reinforcing alcohol effects (high, like, rush, feel good, intoxicated). Adverse events associated with varenicline were minimal and, when combined with alcohol, produced no significant effects on physiologic reactivity, mood, or nausea., Conclusions: This preliminary investigation demonstrated that varenicline significantly reduced alcohol self-administration and was well tolerated, alone and in combination with alcohol in heavy-drinking smokers. Varenicline should be investigated as a potential treatment for alcohol use disorders.

Alcohol use may facilitate the development of nicotine dependence. Alcohol is often paired with cigarette smoking, particularly in those experimenting with smoking. However, little research has examined episodic patterns of alcohol and cigarette use. This study examined patterns of alcohol and cigarette use in a college-aged sample (n=237) designated as experimenters or smokers based on their smoking history. Participants reported their consumption of drinks and cigarettes by hour, for each hour, of a typical drinking and smoking episode. Self-reported pleasure and desire associated with smoking generally and while drinking was assessed. No group difference was observed in total number of drinks. However, experimenters delayed smoking until more drinks were consumed, suggesting they smoked after reaching binge levels of alcohol. By contrast, smokers smoked after fewer drinks. Both groups reported increased smoking while drinking and increased pleasure and desire when smoking while drinking. The increase was greater in experimenters. Concurrent alcohol and cigarette use may facilitate the development of tobacco dependence and interventions interrupting their pairing might impede the transition from experimenter to smoker.

Binge drinking and non-daily cigarette smoking are behaviors that are both problematic and prevalent in young adults. Although the relationship between drinking and daily smoking has been well categorized, the intersection between drinking and smoking in non-daily smokers has not been heavily researched. Past 30-day and within-episode patterns of alcohol and cigarette use were collected in young adult non-daily smokers (N=40). Results demonstrated that 79% of smoking occurred on drinking days. Alcohol use was significantly greater on smoking days with the result that drinking to risky binge levels was more likely to occur on a smoking day. Smoking typically occurred after a certain level of alcohol pre-load (2.87 drinks). Together these results confirm that young adult non-daily smokers often concurrently use alcohol and cigarettes. Research is needed to identify possible mechanisms underlying the association between binge drinking and cigarette use in this vulnerable population.

Automobile crash reports show that up to 40% of fatal crashes in the United States involve alcohol and that younger drivers are over-represented. Alcohol use among young drivers is associated with impulsive and risky driving behaviors, such as speeding, which could contribute to their over-representation in alcohol-related crash statistics. Recent laboratory studies show that alcohol increases impulsive behaviors by impairing the drinker's ability to inhibit inappropriate actions and that this effect can be exacerbated in conflict situations where the expression and inhibition of behavior are equally motivating. The present study tested the hypothesis that this response conflict might also intensify the disruptive effects of alcohol on driving performance. Fourteen subjects performed a simulated driving and a cued go/no-go task that measured their inhibitory control. Conflict was motivated in these tasks by providing equal monetary incentives for slow, careful behavior (e.g., slow driving, inhibiting impulses) and for quick, abrupt behavior (fast driving, disinhibition). Subjects were tested under two alcohol doses (0.65 g/kg and a placebo) that were administered twice: when conflict was present and when conflict was absent. Alcohol interacted with conflict to impair inhibitory control and to increase risky and impaired driving behavior on the drive task. Also, individuals whose inhibitory control was most impaired by alcohol displayed the poorest driving performance under the drug. The study demonstrates potentially serious disruptions to driving performance as a function of alcohol intoxication and response conflict, and points to inhibitory control as an important underlying mechanism.

Research shows that prior behavioral training in a challenging environment reduces alcohol-induced impairment on simple psychomotor tasks. However, no studies have examined if this relationship generalizes to driving performance. The present study examined simulated driving performance and tested the hypothesis that a challenging training history would protect against the impairing effects of alcohol on driving performance. The challenging training history involved driving in a visually-impoverished environment. Thirty adults were randomly assigned to one of three groups. Two groups were tested under alcohol (0.65 g/kg) after prior experience performing the task under either a visually-impoverished environment or a normal visual environment. The remaining group served as a control and was trained and tested under the visually-impoverished condition environment. Results showed that individuals trained in the impoverished environment displayed sober levels of performance when their performance was subsequently tested under alcohol. By contrast, volunteers trained in a normal environment showed impairment under alcohol. The findings suggest that differences in driving training history can affect a driver's sensitivity to the impairing effects of alcohol., ((c) 2008 APA, all rights reserved.)

The contribution of driver experience to risk for alcohol-related crashes is based on the tacit assumption that driver experience contributes to driver skill which could mediate the impairing effects of alcohol on driving performance. Surprisingly, few studies of alcohol effects on simulated driving performance have examined the role of driver skill as a mediator of the intensity of alcohol impairment. The present study examined the degree to which individual differences in driving skill mediated the intensity of impairment produced by a moderate dose of alcohol in a group of young adult drivers. Twenty-eight participants were familiarized with a simulated driving road test. After determining their baseline skill level, participants' driving performance was re-tested under either an active dose of alcohol (0.65 g/kg) or a placebo. Results showed that alcohol reduced driving precision, as evident by the increased within-lane deviation observed under the drug. Moreover, those individuals with poorer baseline skill levels showed the greater impairments in response to alcohol. The results highlight the importance of understanding interactions between driver skill level and the effects of alcohol and possibly other drugs.