C-phycocyanin as a storage protein in the blue-green alga Spirulina platensis

The possibility that c-phycocyanin serves as a nitrogen source in Spirulina platensis during nitrogen starvation was studied. The following evidence was obtained in support of this idea. 1. Under favourable conditions for growth, c-phycocyanin existed in large excess in the algal cells. 2. When the supply of nitrogen was low, about 30–50% of the c-phycocyanin disappeared without any effect on the maximal growth rate. 3. A culture which was deprived of nitrogen continued to grow unaffectedly for a period, the duration of which depended on the c-phycocyanin content in the cell before nitrogen starvation was initiated. 4. c-phycocyanin was the only nitrogenous compound that was depleted during the course of nitrogen starvation when growth was yet unaffected. 5. When protein synthesis was inhibited either by nitrogen starvation or by methionine sulfoximine (MSO), phycocyanin content began to decline immediately and growth continued at normal rates as long as c-phycocyanin did not decline below 50%. 6. The decrease in c-phycocyanin content during nitrogen starvation was accompanied by an increase in proteolytic activity.     

Buffalo species identification and delineation using genetic barcoding markers

Enrichment of barcode databases with mitochondrial cytochrome c oxidase subunit I (COI) barcode sequences in different animal taxa has become important for identification of animal source in food samples to prevent commercial fraud. In this study, COI barcode sequence in seventy one river buffalo samples were determined, analyzed and deposited in Genbank barcode database and barcode of life database (BOLD) to contribute for construction of public reference library for COI barcode sequence in river buffalo. Moreover COI barcode sequence was used to identify the closely related buffalo groups: river buffalo, swamp buffalo, lowland anoa and African buffalo. Results indicated the success of the COI barcode in the identification of each of the tested groups. Whereas a suggested sequence of other mitochondrial segment representing two successive transfer RNA (tRNA) genes; tRNA-Threonine (MT-TT) and tRNA-Proline (MT-TP) was failed to be used as a barcode marker for differentiation between the tested buffalo groups.     

Mapping the Potential Risk of Mycetoma Infection in Sudan and South Sudan Using Ecological Niche Modeling

In 2013, the World Health Organization (WHO) recognized mycetoma as one of the neglected tropical conditions due to the efforts of the mycetoma consortium. This same consortium formulated knowledge gaps that require further research. One of these gaps was that very few data are available on the epidemiology and transmission cycle of the causative agents. Previous work suggested a soil-borne or Acacia thorn-prick-mediated origin of mycetoma infections, but no studies have investigated effects of soil type and Acacia geographic distribution on mycetoma case distributions. Here, we map risk of mycetoma infection across Sudan and South Sudan using ecological niche modeling (ENM). For this study, records of mycetoma cases were obtained from the scientific literature and GIDEON; Acacia records were obtained from the Global Biodiversity Information Facility. We developed ENMs based on digital GIS data layers summarizing soil characteristics, land-surface temperature, and greenness indices to provide a rich picture of environmental variation across Sudan and South Sudan. ENMs were calibrated in known endemic districts and transferred countrywide; model results suggested that risk is greatest in an east-west belt across central Sudan. Visualizing ENMs in environmental dimensions, mycetoma occurs under diverse environmental conditions. We compared niches of mycetoma and Acacia trees, and could not reject the null hypothesis of niche similarity. This study revealed contributions of different environmental factors to mycetoma infection risk, identified suitable environments and regions for transmission, signaled a potential mycetoma-Acacia association, and provided steps towards a robust risk map for the disease.     

Lotus japonicus karrikin receptors display divergent ligand-binding specificities and organ-dependent redundancy

Karrikins (KARs), smoke-derived butenolides, are perceived by the α/β-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) and thought to mimic endogenous, yet elusive plant hormones tentatively called KAI2-ligands (KLs). The sensitivity to different karrikin types as well as the number of KAI2 paralogs varies among plant species, suggesting diversification and co-evolution of ligand-receptor relationships. We found that the genomes of legumes, comprising a number of important crops with protein-rich, nutritious seed, contain two or more KAI2 copies. We uncover sub-functionalization of the two KAI2 versions in the model legume Lotus japonicus and demonstrate differences in their ability to bind the synthetic ligand GR24^ent-5DS in vitro and in genetic assays with Lotus japonicus and the heterologous Arabidopsis thaliana background. These differences can be explained by the exchange of a widely conserved phenylalanine in the binding pocket of KAI2a with a tryptophan in KAI2b, which arose independently in KAI2 proteins of several unrelated angiosperms. Furthermore, two polymorphic residues in the binding pocket are conserved across a number of legumes and may contribute to ligand binding preferences. The diversification of KAI2 binding pockets suggests the occurrence of several different KLs acting in non-fire following plants, or an escape from possible antagonistic exogenous molecules. Unexpectedly, L. japonicus responds to diverse synthetic KAI2-ligands in an organ-specific manner. Hypocotyl growth responds to KAR₁, KAR₂ and rac-GR24, while root system development responds only to KAR₁. This differential responsiveness cannot be explained by receptor-ligand preferences alone, because LjKAI2a is sufficient for karrikin responses in the hypocotyl, while LjKAI2a and LjKAI2b operate redundantly in roots. Instead, it likely reflects differences between plant organs in their ability to transport or metabolise the synthetic KLs. Our findings provide new insights into the evolution and diversity of butenolide ligand-receptor relationships, and open novel research avenues into their ecological significance and the mechanisms controlling developmental responses to divergent KLs.     

Genetic variability of the tropical grasshopper Poecilocerus bufonius in Saudi Arabia

Electrophoresis for SDS-proteins and isoenzymes was applied to investigate the genetic variability within the tropical grasshopper Poecilocerus bufonius, which inhabits Saudi Arabia. Samples were selected from different localities that are encompassing the Sarawat Mountains in the west and An-Nafud desert in the north and middle. A range of 2 to 14 protein bands were recorded in the studied samples as measured by SDS-polyacrylamide gel electrophoresis, from which only two were common. The maximum number of protein bands has been recorded in the samples from the west and the minimum number has been recorded in the samples from the north and middle. Six arbitrary chosen enzymes were examined by native-polyacrylamide gel electrophoresis. They were peroxidase (Px), aldehyde oxidase (Ao), acid phosphatase (Acph), alcohol dehydrogenase (Adh), á and â ePsterase (Est). Fourteen presumptive gene loci and 26 polymorphic alleles have been recorded with the highest number of alleles in Taif and minimum number of alleles in Qassim. Adh, Px and Acph have not been recorded in samples from the localities of An-Nafud desert. The samples from Taif (Sarawat Mountains) were more genetically variable than the samples from other localities. Most of alleles were monomeric but only the Px-1 showed trimeric alleles in samples from Taif.