Protocol: optimising hydroponic growth systems for nutritional and physiological analysis of Arabidopsis thaliana and other plants

BACKGROUND Hydroponic growth systems are a convenient platform for studying whole plant physiology. However, we found through trialling systems as they are described in the literature that our experiments were frequently confounded by factors that affected plant growth, including algal contamination and hypoxia. We also found the way in which the plants were grown made them poorly amenable to a number of common physiological assays. RESULTS The drivers for the development of this hydroponic system were: 1) the exclusion of light from the growth solution; 2) to simplify the handling of individual plants, and 3) the growth of the plant to allow easy implementation of multiple assays. These aims were all met by the use of pierced lids of black microcentrifuge tubes. Seed was germinated on a lid filled with an agar-containing germination media immersed in the same solution. Following germination, the liquid growth media was exchanged with the experimental solution, and after 14-21 days seedlings were transferred to larger tanks with aerated solution where they remained until experimentation. We provide details of the protocol including composition of the basal growth solution, and separate solutions with altered calcium, magnesium, potassium or sodium supply whilst maintaining the activity of the majority of other ions. We demonstrate the adaptability of this system for: gas exchange measurement on single leaves and whole plants; qRT-PCR to probe the transcriptional response of roots or shoots to altered nutrient composition in the growth solution (we demonstrate this using high and low calcium supply); producing highly competent mesophyll protoplasts; and, accelerating the screening of Arabidopsis transformants. This system is also ideal for manipulating plants for micropipette techniques such as electrophysiology or SiCSA. CONCLUSIONS We present an optimised plant hydroponic culture system that can be quickly and cheaply constructed, and produces plants with similar growth kinetics to soil-grown plants, but with the advantage of being a versatile platform for a myriad of physiological and molecular biological measurements on all plant tissues at all developmental stages. We present ‘tips and tricks’ for the easy adoption of this hydroponic culture system.Simon J Conn, Bradleigh Hocking, Maclin Dayod, Bo Xu, Asmini Athman, Sam Henderson, Lucy Aukett, Vanessa Conn, Monique K Shearer, Sigfredo Fuentes, Stephen D Tyerman and Matthew Gilliha

Gender differences in best friendships

Prior investigations of friendship patterns have reported gender differences, with women's same-gender friendships tending to be richer and having a possible therapeutic value, as compared to those of men. Compared to same-gender best friendships, opposite-gender best friendships have been described as less fulfilling for women and more fulfilling for men. The present study explored such differences more fully in a sample of 65 female and 58 male predominantly white college students. Subjects completed four modified versions of P. H. Wright's [(1985) “The Acquaintance Description Form,” In S. F. Duck and D. Pearlman (Eds.), Understanding Personal Relationships: An Interdisciplinarian Approach, London: Sage] Acquaintance Description Form, describing their actual and ideal same-gender best friendships and their actual and ideal opposite-gender best friendships. They also responded to several measures of dysphoria. In the present study, the lowest scores for the friendship scales were reported by male subjects describing same-gender friendships, both ideal and actual. For both male and female subjects, dysphoria was positively correlated with a discrepancy between ideal and actual friendships with same-gender or opposite-gender individuals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45601/1/11199_2004_Article_BF00289323.pd

Correlation of intra-operative duplex findings during carotid endarterectomy with neurological events and recurrent stenosis at one year

Objectives: carotid endarterectomy has been used to treat both asymptomatic and symptomatic disease and this has meant that recurrent stenosis and its effect on late stroke risk have become increasingly important. In this study we compared anatomical defects and residual stenosis identified intra-operatively with recurrent stenosis and new symptoms developing in the first year after surgery, Design, Materials & Methods: two hundred and forty-four consecutive patients undergoing carotid endarterectomy were studied prospectively, Residual anatomical defects were noted; residual stenosis was defined by intra-operative duplex ultrasound as >50%. New stenoses and clinical events during the one-year surveillance period were documented. Results: there was an increased incidence of recurrent stenosis at one year in vessels with residual stenoses (p < 0.001) and in vessels containing a residual anatomical defect (p = 0.037). There was no significant difference in recurrent stenosis rate with respect to closure (primary or patch) or seniority of surgeon but recurrent stenosis was increased in females (p = 0.026). The majority (70%) of restenotic lesions were localised to the origin of the internal carotid artery. The late stroke rate was 0.9% and was not related to recurrent stenosis or symptoms. Conclusions: residual stenosis and intra-luminal defects at completion increase the recurrent stenosis rate at one year, The aetiology of recurrent stenosis is multi-factorial and further studies are required to determine whether it is justified to modify the criteria for re-exploration with a view to reducing recurrent stenosis