Growing healthy sweetpotato: best practices for producing planting material

Sweetpotato is a major food crop in Papua New Guinea, with about 2.9 million tonnes grown each year. But sweetpotato is prone to pests and diseases, particularly viruses, which can significantly reduce yields. Because there are no varieties known to be resistant to viruses, the next best solution is to produce planting material that is free from infection, and to make this readily available to growers. This manual is aimed at researchers and technicians, and describes how to test for sweetpotato viruses and to keep vines free from infection. The methods described should help locals in PNG and other Pacific nations produce disease-free planting material for sweetpotato and other root and tuber crops

Axonal Dynamics of Excitatory and Inhibitory Neurons in Somatosensory Cortex

Electrophysiology-delivery of fluorescent viral vectors-and two-photon microscopy were used to demonstrate the rapidity of axonal restructuring of both excitatory and inhibitory neurons in rodent cortical layer II/III following alterations in sensory experience

Growing healthy sweetpotato: best practices for producing planting material

Sweetpotato is a major food crop in Papua New Guinea, with about 2.9 million tonnes grown each year. But sweetpotato is prone to pests and diseases, particularly viruses, which can significantly reduce yields. Because there are no varieties known to be resistant to viruses, the next best solution is to produce planting material that is free from infection, and to make this readily available to growers. This manual is aimed at researchers and technicians, and describes how to test for sweetpotato viruses and to keep vines free from infection. The methods described should help locals in PNG and other Pacific nations produce disease-free planting material for sweetpotato and other root and tuber crops

Change in axonal density plotted as a function of days of deprivation.

<p>Expressed as a ratio of axonal length at the indicated duration of deprivation to that measured before deprivation. The green line depicts axons of inhibitory interneurons whose somata are located in deprived barrel columns and are projecting into the non-deprived barrel columns. The yellow line depicts axons of excitatory neurons in the non-deprived barrel columns that are projecting into the deprived barrel columns.</p

Short term changes in axonal length and bouton number.

<p>Over hours following the onset of plucking for inhibitory interneurons whose soma are located in deprived rows. (A) Location of boutons with respect to cortical topography. (B) Reconstruction of axons following whisker plucking. (C) Time course of change in axonal length (%). (D) Time course of change in bouton number (%).</p

Excitatory axons originating from neurons within non-deprived barrel columns.

<p>(A) Excitatory axons located within non-deprived barrel columns. Left, axons located in rows A and B before whisker plucking. Right, same area following 1 mo of whisker plucking. (B–D) Axonal density in non-deprived cortex after 14 (B), 30 (C), and 60 (D) d of whisker plucking. Left column, first imaging session. Right column, second imaging session after the indicated period of plucking. As in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1000395#pbio-1000395-g005" target="_blank">Figure 5</a>, the axonal density at each pair of time points was averaged over a set of mice and normalized by dividing each bin by the maximum region of local density in the baseline condition. Normalized mean axonal density is plotted (in arbitrary units) in 50 µm×50 µm bins with the respect to the injection site (asterisk) at coordinate (0,0,0). Distances are expressed in µm from injection site. Average location of barrel column for animals in each condition is indicated on each graph. Green labels refer to non-deprived barrel columns.</p

Axons of inhibitory interneurons located in the non-deprived rows following whisker plucking.

<p>(A) Top, the whisker barrel map. Rectangular box depicts the region of axonal reconstructions shown on the right. Middle, axons located within non-deprived rows before whisker plucking. Right, same area after 2 d of plucking. In the reconstruction, the axons that persisted over both sessions are shown in blue, axons retracted from the first to second imaging session in red, and new axons in yellow. Scale bar  = 50 µm. (B–D) Changes in axonal length for 2 (B), 14 (C), and 30 (D) d of whisker plucking. Left, the distribution of axonal length that was lost between each baseline and post-plucking time point. Right, the distribution of axonal length that was gained between the baseline and post-plucking time points. The data for each pair of time points were obtained by averaging over several mice. Here, the magnitude of the axonal changes for each data pair is normalized with respect to the maximum length of axon that was retracted within any bin. The maximum length of retracted axon in each data pair is therefore 1.0 (in arbitrary units of length), and the length of added axon is measured with respect to that value. The dimensions of the bins are 50 µm×50 µm. The average locations of barrel columns for animals in each condition are marked on each map, with deprived barrel columns indicated in white and non-deprived barrel columns indicated in green.</p

Changes in axonal density following varying durations of whisker plucking.

<p>(A–D) For 2 (A), 14 (B), 30 (C), and 60 (D) d. Left column, first imaging session. Right column, second imaging session. The axonal length in each bin was averaged over multiple animals and then normalized. The normalization was performed by dividing all the bins in each baseline condition by the value of the highest density bin maximum in that condition. The bins in the corresponding post-plucking time point were divided by the same number. The maximum mean axonal length for any bin in each baseline graph is therefore 1.0 (expressed in arbitrary units, A.U.), and the length in the corresponding post-plucking graph is expressed relative to that standard. The bins in the histogram are 50 µm×50 µm; the injection site is located at coordinate (0,0,0). Average location of barrel column for animals in each condition is indicated on each graph. White text depicts deprived barrel columns. Green text depicts non-deprived barrel columns.</p