Structural Properties of the Caenorhabditis elegans Neuronal Network

Despite recent interest in reconstructing neuronal networks, complete wiring diagrams on the level of individual synapses remain scarce and the insights into function they can provide remain unclear. Even for Caenorhabditis elegans, whose neuronal network is relatively small and stereotypical from animal to animal, published wiring diagrams are neither accurate nor complete and self-consistent. Using materials from White et al. and new electron micrographs we assemble whole, self-consistent gap junction and chemical synapse networks of hermaphrodite C. elegans. We propose a method to visualize the wiring diagram, which reflects network signal flow. We calculate statistical and topological properties of the network, such as degree distributions, synaptic multiplicities, and small-world properties, that help in understanding network signal propagation. We identify neurons that may play central roles in information processing and network motifs that could serve as functional modules of the network. We explore propagation of neuronal activity in response to sensory or artificial stimulation using linear systems theory and find several activity patterns that could serve as substrates of previously described behaviors. Finally, we analyze the interaction between the gap junction and the chemical synapse networks. Since several statistical properties of the C. elegans network, such as multiplicity and motif distributions are similar to those found in mammalian neocortex, they likely point to general principles of neuronal networks. The wiring diagram reported here can help in understanding the mechanistic basis of behavior by generating predictions about future experiments involving genetic perturbations, laser ablations, or monitoring propagation of neuronal activity in response to stimulation

Can a speed breeding approach accelerate genetic gain in pigeonpea?

Pure line breeding is a resource-intensive activity that takes 10 years or more to develop a new cultivar. In some crops, conducting off-season nurseries has significantly reduced the length of the breeding cycle. This approach could not be exploited in pigeonpea [Cajanus cajan (L.) Millsp.], because traditionally it has been a photoperiod-sensitive crop that requires long periods of darkness to induce flowering. However, the recent success of breeding early maturing photoperiod-insensitive genotypes has opened up the possibility of adopting ‘speed breeding’ techniques to enable rapid generation turnover. This paper outlines a speed breeding approach that integrates the use of immature seed germination for rapid generation advancement and a "single pod descent" method of breeding. To accelerate line development, while conserving genetic variability, the approach permits four generations per year and can fast-track field evaluation of resulting homozygous lines. Therefore, the breeding strategy conserves resources and has potential to deliver new early maturing cultivars within a substantially reduced timeframe of 4–5 years

Plant growth promoting rhizobia: Challenges and opportunities

Modern agriculture faces challenges, such as loss of soil fertility, fluctuating climatic factors and increasing pathogen and pest attacks. Sustainability and environmental safety of agricultural production relies on eco-friendly approaches like biofertilizers, biopesticides and crop residue return. The multiplicity of beneficial effects of microbial inoculants, particularly plant growth promoters (PGP), emphasizes the need for further strengthening the research and their use in modern agriculture. PGP inhabit the rhizosphere for nutrients from plant root exudates. By reaction, they help in (1) increased plant growth through soil nutrient enrichment by nitrogen fixation, phosphate solubilization, siderophore production and phytohormones production (2) increased plant protection by influencing cellulase, protease, lipase and β-1,3 glucanase productions and enhance plant defense by triggering induced systemic resistance through lipopolysaccharides, flagella, homoserine lactones, acetoin and butanediol against pests and pathogens. In addition, the PGP microbes contain useful variation for tolerating abiotic stresses like extremes of temperature, pH, salinity and drought; heavy metal and pesticide pollution. Seeking such tolerant PGP microbes is expected to offer enhanced plant growth and yield even under a combination of stresses. This review summarizes the PGP related research and its benefits, and highlights the benefits of PGP rhizobia belonging to the family Rhizobiaceae, Phyllobacteriaceae and Bradyrhizobiaceae

AN INFORMATION THEORETIC APPROACH TO THE CONSTRUCTION OF EFFICIENT DECISION TREES

This paper treats the problem of construction of efficient decision trees. Construction of optimal decision trees is an NP-complete problem and, therefore, a heuristic approach for the design of efficient decision trees is considered. The approach is based on information theoretic concepts and the proposed algorithm provides us with a simple procedure for the construction of near-optimal decision trees

Mechanically induced helix-coil transition in biopolymer networks

The quasi-equilibrium evolution of the helical fraction occurring in a biopolymer network (gelatin gel) under an applied stress has been investigated by observing modulation in its optical activity. Its variation with the imposed chain extension is distinctly non-monotonic and corresponds to the transition of initially coiled strands to induced left-handed helices. The experimental results are in qualitative agreement with theoretical predictions of helices induced on chain extension. This new effect of mechanically stimulated helix-coil transition has been studied further as a function of the elastic properties of the polymer network: crosslink density and network aging

Breakthroughs in Groundnut Production Communities in Nigeria

Ms. Hadja Talatu Idrissa (Fig. 6.1), a community women leader, is the chairperson of the Bunkure women group that is active in groundnut production and oil processing. The group which counts 25 members joined the TL projects’ family 4 years ago. They started growing a small seed pack of 5 kg in their community farmland. “It was the harvest of this seed pack that we revolved and planted in a bigger farm plot in the following year,” reported. Hadja. On 1 ha plot, the Bunkure women harvested a total 25 bags of the improved variety SAMNUT 24 against 13 bags they got from 1 ha plot with the old variety. In addition, the group made more money out of the haulms of the improved variety SAMNUT 24. “We sold the haulms of the improved variety up to 30 000 Naira against 12 000 Naira of the local variety,” says Idrissa (1USD equals 360 Nigerian Naira during that period). “The improved variety, SAMNUT 24, has higher haulms yield and is much appreciated for animal feeding because of its taste and digestibility which is better,” she adds

Impact Stories and Testimonies from Diverse Actors in Groundnut Value Chain in Tanzania

Adamu, a groundnut farmer from Maugura village, Masasi, shared his success story for being involved in TL projects (Figs. 2.1 and 2.2). “I was taught how to grow the seeds, carry out diagnosis, how to store them, among other things. This year, there are some seeds that I have begun putting on the ground so that I can continue conducting research about them. Naliendele Institute gave me about 20 lines and I am working on all of them. In fact, they have not yet been named. I’ve just planted them in plots; from plot number one to plot number twenty.” Nyirenda is reaping big from his seed production business. “Last year, I got 90 bags of groundnut from 4 acres, and I sold 47 bags through Naliendele. I sold to other farmers the remaining 43 bags” he said. One bag equals to 42 kg. Nyirenda does not regret his decision to venture into groundnut seed production. “First, I have six children; two are in secondary school and two are in primary school. I pay their fees from the money I earn in the groundnut business. I have built a good house and bought more land to expand the planting area from the proceeds of the groundnut business as well. Generally, I would say, for me this a self-sufficient business.” Nyirenda, however, appeals to the government to purchase planters on behalf of the farmers as this will reduce the cost of production and increase profits. He also thinks that if a factory is set up for groundnut value addition, farmers like him will not struggle any longer with lack of market