Association between fear of hypoglycemia and physical activity in youth with type 1 diabetes: The SEARCH for diabetes in youth study.

BACKGROUND: Youth with type 1 diabetes (T1D) are encouraged to participate in physical activity (PA). Studies have identified fear of hypoglycemia (FOH) as a barrier to participating in PA. OBJECTIVES: To examine (a) PA patterns in youth with T1D by age group and (b) the relationship between both parental and youth FOH and youth PA. METHODS: A cross-sectional analysis from the SEARCH cohort study visit of youth ages 10 to 17 years with T1D (n = 1129) was conducted. Linear regression models estimated the association between self-reported number of days of vigorous PA (VPA) and moderate PA (MPA) and both youth- and parent-reported FOH. Multivariable models were adjusted for age, sex, race, duration of T1D, HbA1c, use of continuous glucose monitoring (CGM), recent severe hypoglycemia, primary insulin regimen, and BMI. RESULTS: Participants were 52% female, had mean (sd) age 14.4 (4.2) years, diabetes duration 7.5 years (1.8), HbA1c 9.2% (1.7). Older youth were less likely to engage in VPA (P < .01), or sports teams (P < .01), but more likely to engage in MPA (P < .01). Higher youth FOH (behavior subscale) was associated with increased levels of VPA (ß (se) 0.30 (0.11), P = .01) but not significantly associated with MPA (P = .06). There was no statistically significant association between parental FOH and youth PA. CONCLUSIONS: In SEARCH participants with T1D, VPA, and team sports participation declined with age, while MPA increased. We observed that higher scores on the youth FOH behavioral subscale were associated with increased VPA levels, suggesting that FOH may be less of a barrier to PA than previously thought.

Product recovery of an enzymatically synthesized (-)-menthol ester in a deep eutectic solvent.

Deep eutectic solvents (DESs) have gained increased attention as alternative reaction media for biocatalysis in recent years. There are many investigations on biotransformations in a variety of DESs, but the purification of bioproducts from DES reaction mixtures has not yet been sufficiently addressed. The present study demonstrates a product recovery strategy from a DES reaction medium composed of (-)-menthol and dodecanoic acid. Since the DES is not formed by equimolar amounts of the substrates, but the eutectic point occurs at a 3:1 molar ratio, product isolation is an important task for effective biocatalytic process development, even if the limiting substrate is converted completely. Both DES compounds acted as substrates and reaction solvent in the lipase-catalyzed esterification to synthesize (-)-menthyl dodecanoate. The product (-)-menthyl dodecanoate ester was separated from the DES reaction mixture by a vacuum distillation step and a second esterification reaction can be performed with the recovered (-)-menthol.

Optimization of solvent-free enzymatic esterification in eutectic substrate reaction mixture.

The Candida rugosa lipase catalyzed esterification of (-)-menthol and lauric acid (LA) was studied in a eutectic mixture formed by both substrates((-)-menthol:LA 3:1, mol/mol). No additional reaction solvent was necessary, since the (-)-menthol:LA deep eutectic solvent (DES) acts as combined reaction medium and substrate pool. Therefore, the esterification is conducted under solvent-free conditions. The thermodynamic water activity (aw) was identified as a key parameter affecting the esterification performance in the (-)-menthol:LA DES. A response surface methodology was applied to optimize the esterification conditions in terms aw, amount of C. rugosa lipase (mCRL) and reaction temperature. Under the optimized reaction conditions (aw = 0.55; mCRL =60 mg; T =45 °C), a conversion of 95 ± 1% LA was achieved (one day), the final (-)-menthyl lauric acid ester concentration reached 1.36 ± 0.04 M (2.25 days). The experimental product formation rate agreed very well with the model prediction.

Summering on the bank: Seasonal distribution and abundance of monkfish on Georges Bank.

The American monkfish is an important commercial species that is widely distributed across a range of depths and temperatures from North Carolina to southern Nova Scotia, including on Georges Bank. We examined changes in the seasonal distribution and relative abundance of monkfish in the scallop access areas in Closed Area I and Closed Area II on Georges Bank using catch data from a three-year seasonal scallop dredge survey. Over the course of the survey, more than 6,000 monkfish were caught and measured, and clear seasonal changes in monkfish abundance were documented. Monkfish catch peaked in the summer and early fall when they were caught across the entire survey area, while they were caught only in deeper waters at the edges of the bank in the winter. Monkfish relative abundance was modeled using a generalized linear mixed model with a Tweedie distribution, and the final model, with month, depth, and bottom temperature as fixed effects, effectively explained the seasonal shifts in the location and relative abundance of monkfish observed during this study. The results suggest that monkfish movements are driven by seasonal changes in bottom temperature. Management measures for monkfish are determined primarily based on data collected during the Northeast Fisheries Science Center bottom trawl surveys, yet this survey catches few monkfish, adding uncertainty to stock assessments. Our research indicates that increasing the use of dredge surveys to collect data on monkfish would be a positive step toward improving monkfish assessments. If monkfish movements are impacted by changes in thermal habitat, their distributions may shift in response to climate change, increasing the need for improved monkfish assessment strategies to effectively manage the species in the future.

Changeable camouflage: how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?

Flounder change colour and pattern for camouflage. We used a spectrometer to measure reflectance spectra and a digital camera to capture body patterns of two flounder species camouflaged on four natural backgrounds of different spatial scale (sand, small gravel, large gravel and rocks). We quantified the degree of spectral match between flounder and background relative to the situation of perfect camouflage in which flounder and background were assumed to have identical spectral distribution. Computations were carried out for three biologically relevant observers: monochromatic squid, dichromatic crab and trichromatic guitarfish. Our computations present a new approach to analysing datasets with multiple spectra that have large variance. Furthermore, to investigate the spatial match between flounder and background, images of flounder patterns were analysed using a custom program originally developed to study cuttlefish camouflage. Our results show that all flounder and background spectra fall within the same colour gamut and that, in terms of different observer visual systems, flounder matched most substrates in luminance and colour contrast. Flounder matched the spatial scales of all substrates except for rocks. We discuss findings in terms of flounder biology; furthermore, we discuss our methodology in light of hyperspectral technologies that combine high-resolution spectral and spatial imaging.

Longitudinal changes in the dietary inflammatory index: an assessment of the inflammatory potential of diet over time in postmenopausal women.

BACKGROUND/OBJECTIVES: The dietary inflammatory index (DII) measured at one time point is associated with risk of several chronic diseases, but disease risk may change with longitudinal changes in DII scores. Data are lacking regarding changes in DII scores over time; therefore, we assessed changes in the DII in the Women's Health Initiative (WHI). SUBJECTS/METHODS: DII scores were calculated using data from repeated food frequency questionnaires in the WHI Observational Study (OS; n=76 671) at baseline and year 3, and the WHI Dietary Modification trial (DM; n=48482) at three time points. Lower DII scores represent more anti-inflammatory diets. We used generalized estimating equations to compare mean changes in DII over time, adjusting for multiple comparisons, and multivariable-adjusted linear regression analyses to determine predictors of DII change. RESULTS: In the OS, mean DII decreased modestly from -1.14 at baseline to -1.50 at year 3. In the DM, DII was -1.32 in year 1, -1.60 in year 3 and -1.48 in year 6 in the intervention arm and was -0.65 in year 1, -0.94 in year 3 and -0.96 in year 6 in the control arm. These changes were modified by body mass index, education and race/ethnicity. A prediction model explained 22% of the variance in the change in DII scores in the OS. CONCLUSIONS: In this prospective investigation of postmenopausal women, reported dietary inflammatory potential decreased modestly over time. Largest reductions were observed in normal-weight, highly educated women. Future research is warranted to examine whether reductions in DII are associated with decreased chronic disease risk.

Association of adherence to a Mediterranean diet with glycemic control and cardiovascular risk factors in youth with type I diabetes: the SEARCH Nutrition Ancillary Study.

BACKGROUND/OBJECTIVES: This study aimed to determine the association between a Mediterranean diet and glycemic control and other cardiovascular risk factors among youth with type I diabetes (TID). SUBJECTS/METHODS: Incident TID cases aged <20 years at diagnosis between 2002 and 2005 were included. Participants were seen at baseline (N=793), 1-year (N=512) and 5-year follow-up visits (N=501). Mediterranean diet score was assessed using a modified KIDMED index (mKIDMED). Multivariate linear regression and longitudinal mixed model were applied to determine the association between mKIDMED score and log-HbA1c, lipids, blood pressure (BP) and obesity. RESULTS: In cross-sectional analyses using baseline data, for individuals with the hemoglobin A1c (HbA1c) of 7.5%, a two-point higher mKIDMED score (1 s.d.) was associated with 0.15% lower HbA1c (P=0.02). A two-point higher mKIDMED score was associated with 4.0 mg/dl lower total cholesterol (TC) (P=0.006), 3.4 mg/dl lower low-density lipoprotein cholesterol (LDL-C) (P=0.004), 3.9 mg/dl lower non-high-density lipoprotein cholesterol (non-HDL-C) (P=0.004) and 0.07 lower LDL-C/HDL-C ratio (P=0.02). Using longitudinal data, a two-point increase in mKIDMED score was associated with 0.01% lower log-HbA1c (P=0.07), 1.8 mg/dl lower TC (P=0.05), 1.6 mg/dl lower LDL-C (P=0.03) and 1.8 mg/dl lower non-HDL-C (P=0.03) than would otherwise have been expected. HbA1c mediated ∼20% of the association for lipids in both cross-sectional and longitudinal models. An unexpected positive association between mKIDMED score and systolic BP was found among non-Hispanic white youth in cross-sectional analyses (P=0.009). Mediterranean diet was not associated with obesity. CONCLUSIONS: Mediterranean diet may improve glycemic control and cardiovascular health in TID youth.

Associations of coffee consumption with markers of liver injury in the insulin resistance atherosclerosis study.

BACKGROUND: Coffee consumption has been associated with reduced risk of developing type 2 diabetes mellitus (T2DM) however, the mechanism for this association has yet to be elucidated. Non-alcoholic fatty liver disease (NAFLD) characterizes and predicts T2DM yet the relationship of coffee with this disorder remains unclear. Our aim was to investigate the associations of coffee with markers of liver injury in 1005 multi-ethnic, non-diabetic adults in the Insulin Resistance Atherosclerosis Study. METHODS: Dietary intake was assessed using a validated 114-item food frequency questionnaire. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and fetuin-A were determined in fasting blood samples and the validated NAFLD liver fat score was calculated. Multivariate linear regression assessed the contribution of coffee to variation in markers of liver injury. RESULTS: Caffeinated coffee showed significant inverse associations with ALT (ß = -0.08, p = 0.0111), AST (ß = -0.05, p = 0.0155) and NAFLD liver fat score (ß = -0.05, p = 0.0293) but not with fetuin-A (ß = 0.04, p = 0.17). When the highest alcohol consumers were excluded, these associations remained (ALT ß = -0.11, p = 0.0037; AST ß = -0.05, p = 0.0330; NAFLD liver fat score ß = -0.06, p = 0.0298). With additional adjustment for insulin sensitivity, the relationship with ALT remained significant (ALT ß = -0.08, p = 0.0400; AST ß = -0.03, p = 0.20; NAFLD liver fat score ß = -0.03, p = 0.27). There were no significant associations of decaffeinated coffee with liver markers. CONCLUSIONS: These analyses indicate a beneficial impact of caffeinated coffee on liver morphology and/or function, and suggest that this relationship may mediate the well-established inverse association of coffee with risk of T2DM.

Associations of dietary intake patterns identified using reduced rank regression with markers of arterial stiffness among youth with type 1 diabetes.

BACKGROUND/OBJECTIVES: Youth with type 1 diabetes (T1DM) are at substantially increased risk for adverse vascular outcomes, but little is known about the influence of dietary behavior on cardiovascular disease (CVD) risk profile. We aimed to identify dietary intake patterns associated with CVD risk factors and evaluate their impact on arterial stiffness (AS) measures collected thereafter in a cohort of youth with T1DM. SUBJECTS/METHODS: Baseline diet data from a food frequency questionnaire and CVD risk factors (triglycerides, low density lipoprotein-cholesterol, systolic blood pressure, hemoglobin A1c, C-reactive protein and waist circumference) were available for 1153 youth aged ⩾10 years with T1DM from the SEARCH for Diabetes in Youth Study. A dietary intake pattern was identified using 33 food groups as predictors and six CVD risk factors as responses in reduced rank regression (RRR) analysis. Associations of this RRR-derived dietary pattern with AS measures (augmentation index (AIx75), n=229; pulse wave velocity, n=237; and brachial distensibility, n=228) were then assessed using linear regression. RESULTS: The RRR-derived pattern was characterized by high intakes of sugar-sweetened beverages (SSB) and diet soda, eggs, potatoes and high-fat meats and low intakes of sweets/desserts and low-fat dairy; major contributors were SSB and diet soda. This pattern captured the largest variability in adverse CVD risk profile and was subsequently associated with AIx75 (ß=0.47; P<0.01). The mean difference in AIx75 concentration between the highest and the lowest dietary pattern quartiles was 4.3% in fully adjusted model. CONCLUSIONS: Intervention strategies to reduce consumption of unhealthy foods and beverages among youth with T1DM may significantly improve CVD risk profile and ultimately reduce the risk for AS.

Incidence of diabetes mellitus in a population-based cohort of HIV-infected and non-HIV-infected persons: the impact of clinical and therapeutic factors over time.

AIMS: To examine incidence density rate and correlates of incident diabetes mellitus in a cohort of HIV-infected individuals compared with matched non-HIV-infected persons. METHODS: Data were obtained from the South Carolina Medicaid system and the enhanced HIV/AIDS Reporting System surveillance database for persons ≥ 18 years of age who had been attended to during the period 1994 to 2011. Time-dependent proportional hazards analysis and marginal structural models were used to analyse the data. RESULTS: A total of 13 632 individuals (6816, 1:1 matched HIV-infected and non-HIV-infected persons; median age 39 years; 57% male) contributed 88 359 person-years of follow-up. Incidence rate of diabetes was higher in the non-HIV-infected group compared with the HIV-infected group (13.60 vs. 11.35 per 1000 person-years). Multivariable hazards analysis suggested a significantly lower risk of incident diabetes among HIV-infected persons treated with combination antiretroviral therapy compared with the matched non-HIV-infected persons (adjusted hazards ratio 0.55; 95% CI 0.46-0.65). Among HIV-infected persons, marginal structural modelling suggested a significantly higher risk of diabetes with cumulative exposure to protease inhibitors over the observation period (adjusted relative risk 1.35; 95% CI 1.03-1.78), but this association was not significant for exposure to non-nucleoside reverse transcriptase inhibitors. Overall, female gender, older age, non-white race/ethnicity, and pre-existing hypertension, dyslipidaemia, obesity and hepatitis C infection were associated with higher risk of diabetes incidence. CONCLUSIONS: HIV infection may not be independently associated with increased risk of diabetes. Among HIV-infected persons, exposure to protease inhibitor-based regimens may increase the risk of diabetes. Healthcare providers should make every effort to use combination antiretroviral therapy regimens with a better cardiometabolic profile.

Change in DASH diet score and cardiovascular risk factors in youth with type 1 and type 2 diabetes mellitus: The SEARCH for Diabetes in Youth Study.

Youth with diabetes are at an increased risk of cardiovascular disease (CVD). Adherence to the Dietary Approaches to Stop Hypertension (DASH) diet has been shown to improve CVD risk. In this study, we evaluated whether changes in diet quality as characterized by DASH are associated with changes in CVD risk factors in youth with diabetes over time. Longitudinal mixed models were applied to data from 797 participants in the SEARCH for Diabetes in Youth Study representing three time points: baseline, 12- and 60-month follow-up. Data were restricted to youth whose diabetes was first diagnosed in 2002-2005. DASH-related adherence was poor and changed very little over time. However, an increase in DASH diet score was significantly associated with a decrease in HbA1c levels in youth with type 1 diabetes (ß=-0.20, P-value=0.0063) and a decrease in systolic blood pressure among youth with type 2 diabetes (ß=-2.02, P-value=0.0406). Improvements in dietary quality may be beneficial in youth with type 1 or type 2 diabetes. However, further work in larger groups of youth with type 1 and 2 diabetes is desirable.

Factors associated with development of excessive fatness in children and adolescents: a review of prospective studies.

The purpose of this review was to examine the factors that predict the development of excessive fatness in children and adolescents. Medline, Web of Science and PubMed were searched to identify prospective cohort studies that evaluated the association between several variables (e.g. physical activity, sedentary behaviour, dietary intake and genetic, physiological, social cognitive, family and peer, school and community factors) and the development of excessive fatness in children and adolescents (5-18 years). Sixty-one studies met the eligibility criteria and were included. There is evidence to support the association between genetic factors and low physical activity with excessive fatness in children and adolescents. Current studies yielded mixed evidence for the contribution of sedentary behaviour, dietary intake, physiological biomarkers, family factors and the community physical activity environment. No conclusions could be drawn about social cognitive factors, peer factors, school nutrition and physical activity environments, and the community nutrition environment. There is a dearth of longitudinal evidence that examines specific factors contributing to the development of excessive fatness in childhood and adolescence. Given that childhood obesity is a worldwide public health concern, the field can benefit from large-scale, long-term prospective studies that use state-of-the-art measures in a diverse sample of children and adolescents.

How visual edge features influence cuttlefish camouflage patterning.

Rapid adaptive camouflage is the primary defense of soft-bodied cuttlefish. Previous studies have shown that cuttlefish body patterns are strongly influenced by visual edges in the substrate. The aim of the present study was to examine how cuttlefish body patterning is differentially controlled by various aspects of edges, including contrast polarity, contrast strength, and the presence or absence of "line terminators" introduced into a pattern when continuous edges are fragmented. Spatially high- and low-pass filtered white or black disks, as well as isolated, continuous and fragmented edges varying in contrast, were used to assess activation of cuttlefish skin components. Although disks of both contrast polarities evoked relatively weak disruptive body patterns, black disks activated different skin components than white disks, and high-frequency information alone sufficed to drive the responses to white disks whereas high- and low-frequency information were both required to drive responses to black disks. Strikingly, high-contrast edge fragments evoked substantially stronger body pattern responses than low-contrast edge fragments, whereas the body pattern responses evoked by high-contrast continuous edges were no stronger than those produced by low-contrast edges. This suggests that line terminators vs. continuous edges influence expression of disruptive body pattern components via different mechanisms that are controlled by contrast in different ways.

Fish consumption, insulin sensitivity and beta-cell function in the Insulin Resistance Atherosclerosis Study (IRAS).

BACKGROUND AND AIMS: Previous research on the association between fish consumption and incident type 2 diabetes has been inconclusive. In addition, few studies have investigated how fish consumption may be related to the metabolic abnormalities underlying diabetes. Therefore, we examined the association of fish consumption with measures of insulin sensitivity and beta-cell function in a multi-ethnic population. METHODS AND RESULTS: We examined the cross-sectional association between fish consumption and measures of insulin sensitivity and secretion in 951 non-diabetic participants in the Insulin Resistance Atherosclerosis Study (IRAS). Fish consumption, categorized as <2 vs. ≥2 portions/week, was measured using a validated food frequency questionnaire. Insulin sensitivity (S(I)) and acute insulin response (AIR) were determined from frequently sampled intravenous glucose tolerance tests. Higher fish consumption was independently associated with lower S(I)-adjusted AIR (ß = -0.13 [-0.25, -0.016], p = 0.03, comparing ≥2 vs. <2 portions/week). Fish consumption was positively associated with intact and split proinsulin/C-peptide ratios, however, these associations were confounded by ethnicity (multivariable-adjusted ß = 0.073 [-0.014, 0.16] for intact proinsulin/C-peptide ratio, ß = 0.031 [-0.065, 0.13] for split proinsulin/C-peptide ratio). We also observed a significant positive association between fish consumption and fasting blood glucose (multivariable-adjusted ß = 2.27 [0.68, 3.86], p = 0.005). We found no association between fish consumption and S(I) (multivariable-adjusted ß = -0.015 [-0.083, 0.053]) or fasting insulin (multivariable-adjusted ß = 0.016 [-0.066, 0.10]). CONCLUSIONS: Fish consumption was not associated with measures of insulin sensitivity in the multi-ethnic IRAS cohort. However, higher fish consumption may be associated with pancreatic beta-cell dysfunction.

Comparison of two waist circumference measurement protocols: the SEARCH for diabetes in youth study.

BACKGROUND: Reports comparing waist circumference (WC) measurements from young populations are scarce. OBJECTIVES: We compared two protocols for measuring waist circumference in a sample of youth with diabetes. METHODS: Participants were enrolled in the SEARCH for Diabetes in Youth Study (SEARCH). WC was measured at least twice by the National Health and Nutrition Examination Survey (NHANES) protocol and twice by the World Health Organization (WHO) protocol. Method-specific averages were used in these analyses. RESULTS: Among 6248 participants, the mean NHANES WC (76.3 cm) was greater than the mean WHO WC (71.9 cm). Discrepancies between protocols were greater for females than males, among older participants, and in those with higher body mass index (BMI). In both sexes and four age strata, the WCs using either method were highly correlated with BMI z-score. The within-method differences between the first and second measurements were similar for the two methods. CONCLUSIONS: These analyses do not provide evidence that one of these two methods is more reproducible or is a better indicator of obesity as defined by BMI z-scores.

Spatial accessibility and availability measures and statistical properties in the food environment.

Spatial accessibility is of increasing interest in the health sciences. This paper addresses the statistical use of spatial accessibility and availability indices. These measures are evaluated via an extensive simulation based on cluster models for local food outlet density. We derived Monte Carlo critical values for several statistical tests based on the indices. In particular we are interested in the ability to make inferential comparisons between different study areas where indices of accessibility and availability are to be calculated. We derive tests of mean difference as well as tests for differences in Moran's I for spatial correlation for each of the accessibility and availability indices. We also apply these new statistical tests to a data example based on two counties in South Carolina for various accessibility and availability measures calculated for food outlets, stores, and restaurants.

Associations between the intake of caffeinated and decaffeinated coffee and measures of insulin sensitivity and beta cell function.

AIMS/HYPOTHESIS: Although protective relationships between coffee consumption and type 2 diabetes mellitus have consistently been observed, few studies have examined the relationships between coffee consumption and underlying pathophysiological defects that characterise diabetes aetiology. The aim of this study was to explore the associations between caffeinated and decaffeinated coffee consumption and measures of insulin sensitivity and secretion. METHODS: The study population included 954 multi-ethnic non-diabetic adults from the Insulin Resistance Atherosclerosis Study (IRAS). Multiple regression analyses were performed to examine the cross-sectional relationships between caffeinated and decaffeinated coffee intake and insulin sensitivity and acute insulin response, measured by a frequently sampled intravenous glucose tolerance test, 2 h postload glucose measured by OGTT, fasting insulin, and proinsulin to C-peptide ratios. RESULTS: Caffeinated coffee intake was positively associated with insulin sensitivity (ß = 0.054; SE = 0.026; p = 0.04) and inversely related to 2 h postload glucose (ß = -0.37; SE = 0.10; p = 0.0003) in fully adjusted models. Caffeinated coffee intake was not associated with acute insulin response or proinsulin ratios. Decaffeinated coffee intake was inversely related to 2 h postload glucose (ß = -0.47; SE = 0.18; p = 0.0096) and positively related to acute insulin response (ß = 0.191; SE = 0.077; p = 0.0132). Decaffeinated coffee intake was inversely related to the ratios of both intact and split proinsulin to C-peptide (ß = -0.150; SE = 0.061; p = 0.0148; ß = -0.254; SE = 0.068; p = 0.0002, respectively). CONCLUSIONS/INTERPRETATION: In this cross-sectional study, caffeinated coffee was positively related to insulin sensitivity and decaffeinated coffee was favourably related to measures of beta cell function. These results provide pathophysiological insight as to how coffee could impact the risk of type 2 diabetes mellitus.

Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities.

In response to drought stress, the phytohormone abscisic acid (ABA) induces stomatal closure. Thereby the stress hormone activates guard cell anion channels in a calcium-dependent, as well as -independent, manner. Open stomata 1 protein kinase (OST1) and ABI1 protein phosphatase (ABA insensitive 1) represent key components of calcium-independent ABA signaling. Recently, the guard cell anion channel SLAC1 was identified. When expressed heterologously SLAC1 remained electrically silent. Upon coexpression with Ca(2+)-independent OST1, however, SLAC1 anion channels appear activated in an ABI1-dependent manner. Mutants lacking distinct calcium-dependent protein kinases (CPKs) appeared impaired in ABA stimulation of guard cell ion channels, too. To study SLAC1 activation via the calcium-dependent ABA pathway, we studied the SLAC1 response to CPKs in the Xenopus laevis oocyte system. Split YFP-based protein-protein interaction assays, using SLAC1 as the bait, identified guard cell expressed CPK21 and 23 as major interacting partners. Upon coexpression of SLAC1 with CPK21 and 23, anion currents document SLAC1 stimulation by these guard cell protein kinases. Ca(2+)-sensitive activation of SLAC1, however, could be assigned to the CPK21 pathway only because CPK23 turned out to be rather Ca(2+)-insensitive. In line with activation by OST1, CPK activation of the guard cell anion channel was suppressed by ABI1. Thus the CPK and OST1 branch of ABA signal transduction in guard cells seem to converge on the level of SLAC1 under the control of the ABI1/ABA-receptor complex.