Membrane attack complex/perforin/cholesterol-dependent cytolysin (MACPF/CDC) proteins constitute a major superfamily of pore-forming proteins that act as bacterial virulence factors and effectors in immune defence. Upon binding to the membrane, they convert from the soluble monomeric form to oligomeric, membrane-inserted pores. Using real-time atomic force microscopy (AFM), electron microscopy (EM), and atomic structure fitting, we have mapped the structure and assembly pathways of a bacterial CDC in unprecedented detail and accuracy, focussing on suilysin from Streptococcus suis. We show that suilysin assembly is a noncooperative process that is terminated before the protein inserts into the membrane. The resulting ring-shaped pores and kinetically trapped arc-shaped assemblies are all seen to perforate the membrane, as also visible by the ejection of its lipids. Membrane insertion requires a concerted conformational change of the monomeric subunits, with a marked expansion in pore diameter due to large changes in subunit structure and packing.DOI: http://dx.doi.org/10.7554/eLife.04247.001

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An experiment was conducted to evaluate the effect of TIBA (0, 20, 50, 100, 150 mg/l) on the growth and yield attributes of BARI Mung-5 laid out in RBD. Plant height decreased due to TIBA treatments. Number of branches and leaves per plant were found to increase in all the treatments at all the ages of growth except at 7 DAS and the maximum number of branches and leaves were recorded due to 20 mg/l TIBA treatment. Dry matter per plant increased due to 20 mg/l TIBA in most cases and was significantly highest at harvest. All the yield contributing characters showed positive response to 20 mg/l TIBA treatment. Number of pods and seeds per plant and fresh and dry weights of pods significantly differed from all other treatments. Increase in yield per plant and yield per hectare following 20 mg/l TIBA was 22.60 and 22.80% over the control, respectively. The highest harvest index was also recorded from 20 mg/l TIBA followed by control.

Effects of 100 and 200 ppm of naphthalene acetic acid (NAA) on yield attributes and yield of two varieties of rice during 2009 -2010 Boro season were evaluated. The highest plant height was observed due to 200 ppm in both BRRI dhan-29 (V 1 ) and BRRI dhan-50 (V 2 ). Number of tillers per plant were found to increase due to 100 ppm NAA only in BRRI dhan-29 and varied non-significantly. Yield attributes, viz. number of branches per panicle, number of grains per panicle and filled grains per panicle increased in BRRI dhan-29, following both 100 and 200 ppm NAA, whereas, most of the yield parameters decreased in BRRI dhan-50. Due to 100 and 200 ppm NAA, grain yield per plant increased by 27.67 and 6.85%, respectively in BRRI dhan-29 though not statistically significant. However, in BRRI dhan-50 grain yield per plant decreased by 26.54% due to 100 ppm and 27.67% due to 200 ppm. Out of the two concentrations 100 ppm NAA produced better stimulation.The use of growth regulators is considered as one of the way of increasing yield. NAA, a synthetic growth regulator has proved its potentiality that in appropriate concentration NAA affects the growth and yield of a number of plants viz. tomato (Chhonker and Singh 1959), bitter gourd (Jahan and Fattah 1991) and cowpea ( Ullah et al. 2007). Reports regarding the growth and yield aspect with NAA on cereal plants including rice are available in other countries (Misra and Sahu 1957, Chaudhuri et al.1980, Singh and Gill 1985, Grewal and Gill 1986, Muthukumar et al. 2005. In Bangladesh very limited research has been done on growth and yield aspects on cereal crops with NAA. Therefore, the present investigation was undertaken to study the effect of NAA on yield attributes and yield of two varieties of rice.The pot experiment was conducted in the garden of the Department of Botany, University of Dhaka during the period from November, 2009 to April, 2010. Each pot (about 30 cm in diameter at the top) was filled with 9.0 kg air dried soil. Cow-dung was mixed uniformly during pot preparation and 2 g of gypsum was also added in each pot (equals to 444 kg/ha). The experiment was laid out in a randomized complete block design (RCBD) with three replications. Plant materials were collected from Bangladesh Rice Research Institute (BRRI), Joydebpur, Gazipur. BRRI dhan-29 is a high yielding variety released in 1994 and BRRI dhan-50 is an aromatic variety released in 2008. Seeds were sterilized by 0.5% calcium hypochlorite solution and were sown on November 7, 2009. Seedlings were transplanted to pots at 5-leaf stage at 36 days after sowing. Five hills were placed in each pot, each hill containing one seedling. Thinning was done in such way that a healthy seedling of uniform size and vigour was allowed to grow. Irrigation was done as per necessity. Weeding was done twice on 25 and 45 day after transplanting (DAT). Split applications of urea were applied twice at the rate of 1 g per pot (equals to 222 kg/ha) at 20 DAT and at 50 DAT. There were three treatments as follows; T 0 = distilled...

A pot experiment showed that 100 and 200 ppm naphthalene acetic acid (NAA) plant height, number of leaves per plant and number of tillers per plant were found to increase due to 100 ppm NAA only in BRRI dhan-29 (V 1 ) and varied significantly at 60 DAS. Total dry matter (TDM) was found to increase up to harvest due to both the treatments in V 1 , whereas, in BRRI dhan-50 (V 2 ) also increased at 15 and 30 DAS and the variation was non-significant. There was an increasing tendency in leaf area per plant due to T 1 treatment in both the varieties except at 45 DAS in V 2 .Significant variations were observed at 15 and 30 DAS only in V 1 . Relative growth rate (RGR) was maximum at early stage of growth and then declined in both the varieties. RGR was significant during 0 to15 and 45 to 60 DAS in case of V 1 . Net assimilation rate (NAR) was non-significantly affected and found to increase during 15 to 30 DAS following both the treatments in V 1 , but in V 2 due to T 2 treatment only. Out of the two concentrations 100 ppm NAA produced better stimulation.