The first visible effect following the application of sublethal doses of 4-chloro-5-(dimethylamino)-2-(a ,a,a-trifluoro-mtolyl)-3(2H)-pyridazinone (hereafter referred to as 6706, manufacturer's code number) to germinating wheat grains was the formation of albinistic seedlings. These seedlings grew and developed as well as untreated seedlings for 9 days. Hilton et al. (12) studied the effect of 6706 on established green leaves and meristematic tissues of several different species. They found that Hill reaction and CO2 fixation were inhibited in green leaves and that chloroplast development was blocked in embryonic cells.The action of 6706 on wheat seedlings grown under high light intensities appears to be similar to that of 3-amino-s-triazole (4) and of 3,4-dichlorobenzylmethylcarbamate (5). These herbicides cause the loss of grana-fret membranes and chloroplast ribosomes. Burns et al. (9) suggested that the mode of action of these herbicides was the inhibition of carotenoid synthesis. We investigated the effect of 6706 on the ultrastructure, ribosome, and pigment composition of the aberrant plastids of wheat seedlings which were grown in dark only, light only, or dark followed by light.MATERILIS AND METHODS Wheat seedlings (Triticum vulgare L. var. Maricopa) were germinated and grown in Petri dishes (15 grains per dish) containing either 10 ml of 0.1 mi 6706 or distilled water, under one of the following conditions: (a) 6 days in light at 1 ft-c, or 1500 ft-c, 16-hr photoperiod, 21 C; (b) 6 days in darkness except for exposure to dim green light during watering, 23 C; or (c) 6 days in darkness followed by 1, 4, or 12 hr of light. The light intensity used during greening was either 1 ft-c, 75 ft-c, or 1500 ft-c, 23 C. Following germination, plants were watered with distilled water. On the 6th day shoots were harvested, weighed, and prepared for either ultrastructural, sedimentation, or pigment studies.Sedimentation and ultrastructural studies were performed as discribed in an earlier publication (5) except that (a) grinding media used to isolate ribosomes contained 4% Triton X-100 (Rohm and Haas, Philadelphia) and (b) fixing solutions used in electron microscope preparations contained 0.01 M cacodylate-HCI buffer (pH 7.2) instead of phosphate buffer.

The isolation of chloroplast and nuclear DNA from darkand light-grown, control-and 3-amino-1,2,4-triazoletreated wheat seedlings, Triticum vulgare, is described. Contrary to a previous report, we found that chloroplast and nuclear DNA had similar buoyant densities (1.702 grams per cubic centimeter) and that they could not be resolved by buoyant density centrifugation in CsCl. Difference in renaturation behavior of the chloroplast and nuclear DNA was used as the criterion for distinguishing one from the other. Only chloroplast DNA readily renatured whereas nuclear DNA renatured only slightly. Light-grown, 3-amino-1,2,4-triazole-treated plants were found to lack detectable quantities of chloroplast DNA whereas treated, dark-grown plants contained plastid DNA. We suggest that 3-amino-1,2,4-triazole affects the accumulation of chloroplast DNA by inhibiting the formation of chloroplast membranes, enzymes, and pigments.The buoyant density of chloroplast DNA in CsCl has become a subject of controversy. From 1963 to 1967 several investigators (5,6,12,13,21,24) reported that chloroplast DNA of many dicotyledonous plants had a much higher buoyant density than their corresponding nuclear DNA. The chloroplast DNA of only a few monocotyledonous plants has been studied. Mache and Waygood (16) reported that buoyant density of wheat chloroplast DNA was higher than the nuclear DNA, and their results were similar to the earlier studies. Recently, more rigorous studies of dicotyledonous plants demonstrated that buoyant density of chloroplast DNA was similar or identical to nuclear DNA and that the two types of DNA could not be separated in CsCl density gradient (1,14,25,26). However, DNAs are distinguished from each other by the fact that chloroplast DNA will readily renature whereas nuclear DNA will not. In this study we report the existence in wheat seedlings of chloroplast DNA which has a buoyant density identical to the nuclear DNA.Light-grown wheat seedlings treated with 3-amino-1,2 ,4-triazole have been shown to lack chloroplast ribosomes (2). Scott

Abnormal EEG features are a hallmark of epilepsy, and abnormal frequency and network features are apparent in EEGs from people with idiopathic generalised epilepsy in both ictal and interictal states. Here, we characterise differences in the resting-state EEG of individuals with juvenile myoclonic epilepsy and assess factors influencing the heterogeneity of EEG features. We collected EEG data from 147 participants with juvenile myoclonic epilepsy through the Biology of Juvenile Myoclonic Epilepsy study. 95 control EEGs were acquired from two independent studies (Chowdhury et al. (2014) and EU-AIMS Longitudinal European Autism Project). We extracted frequency and functional network-based features from 10-20 s epochs of resting-state EEG, including relative power spectral density, peak alpha frequency, network topology measures and brain network ictogenicity: a computational measure of the propensity of networks to generate seizure dynamics. We tested for differences between epilepsy and control EEGs using univariate, multivariable and receiver operating curve analysis. Additionally, we explored the heterogeneity of EEG features within and between cohorts by testing for associations with potentially influential factors such as age, sex, epoch length and time, as well as testing for associations with clinical phenotypes including anti-seizure medication, and seizure characteristics in the epilepsy cohort. P-values were corrected for multiple comparisons. Univariate analysis showed significant differences in power spectral density in delta (2-5 Hz) (p = 0.0007, hedges’ g = 0.55) and low-alpha (6-9 Hz) (p = 2.9 × 10−8, g = 0.80) frequency bands, peak alpha frequency (p = 0.000007, g = 0.66), functional network mean degree (p = 0.0006, g = 0.48) and brain network ictogenicity (p = 0.00006, g = 0.56) between epilepsy and controls. Since age (p = 0.009) and epoch length (p = 1.7 × 10−8) differed between the two groups and were potential confounders, we controlled for these covariates in multivariable analysis where disparities in EEG features between epilepsy and controls remained. Receiver operating curve analysis showed low-alpha power spectral density was optimal at distinguishing epilepsy from controls, with an area under the curve of 0.72. Lower average normalized clustering coefficient and shorter average normalized path length were associated with poorer seizure control in epilepsy patients. To conclude, individuals with juvenile myoclonic epilepsy have increased power of neural oscillatory activity at low-alpha frequencies, and increased brain network ictogenicity compared to controls, supporting evidence from studies in other epilepsies with considerable external validity. In addition, the impact of confounders on different frequency-based and network-based EEG features observed in this study highlights the need for careful consideration and control of these factors in future EEG research in idiopathic generalised epilepsy particularly for their use as biomarkers.