Aphid transmission and a polypeptide are specified by a defined region of the cauliflower mosaic virus genome

Infection of young turnip leaves with an aphid-transmissible isolate, Cabb B-JI, of cauliflower mosaic virus (CaMV) causes synthesis of an Mr 18 000 polypeptide (p18) which co-purifies with virus inclusion bodies. This polypeptide is not detectable in leaves infected with either of two aphid non-transmissible isolates. Campbell and CM4-184. Construction in vitro, of hybrid genomes between Cabb B-JI and Campbell isolates demonstrates that aphid transmissibility and presence of p18 is dependent on the small genome fragment from the BstEII site to the XhoI site. A deletion made in this fragment within open reading frame (ORF) II causes loss of aphid transmissibility and also terminates production of p18. We conclude that aphid transmissibility and the presence of p18 are related to the expression of ORF II of the CaMV genome.     

Taxonomic assessment of opal phytoliths from grasses of deltaic West Bengal,India

In the present study, taxonomic potential of opal phytoliths was examined in grasses from lower Gangetic delta, West Bengal, India. The study revealed that finer classification of phytoliths can increase the efficacy of opal silica as taxonomic proxy by minimizing the influences of multiplicity and redundancy. We isolated 187 phytolith sub‐morphotypes, categorized under 10 major groups, from 110 grass species belonging to 45 genera, 21 sub‐tribes, 13 tribes and 7 subfamilies. Cluster and correspondence analyses showed that all the significantly represented subfamilies can be clearly distinguished on the basis of either principal morphotypes or sub‐morphotypes. However, genus/species level discrimination may only be possible by deploying phytolith based identification key developed by utilizing detailed grass phytolith micro‐morphometry and frequency attributes. We conclude that grass phytolith characteristics provide useful and significant information for distinguishing grass taxa of deltaic West Bengal.     

Rutile TiO2 Inverse Opal Anodes for Li‐Ion Batteries with Long Cycle Life,High‐Rate Capability,and High Structural Stability

Rutile TiO₂ inverse opals provide long cycle life and impressive structural stability when tested as anode materials for Li‐ion batteries. The capacity retention of TiO₂ inverse opals (IOs) is greater than previously reported values for other rutile TiO₂ nanomaterials, and the cycled crystalline phase and material interconnectivity is maintained over thousands of cycles. Consequently, this paper offers insight into the importance of optimizing the relationship between the structure and morphology on improving electrochemical performance of this abundant and low environmental impact material. TiO₂ IOs show gradual capacity fading over 1000 and 5000 cycles, when cycled at specific currents of 75 and 450 mA g^?1, respectively, while maintaining a high capacity and a stable overall cell voltage. TiO₂ IOs achieve a reversible capacity of ≈170 and 140 mA h g^?1 after the 100th and 1000th cycles, respectively, at a specific current of 75 mA g^?1, corresponding to a capacity retention of ≈82.4%. The structural stability of the 3D IO phase from pristine rutile TiO₂ to the conductive orthorhombic Li_0.5TiO₂ is remarkable and maintains its structural integrity. Image analysis conclusively shows that volumetric swelling is accommodated into the predefined pore space, and the IO periodicity remains constant and does not degrade over 5000 cycles.     

The α- and β-Tubulin Genes of Euplotes octocarinatus

ABSTRACT. The α- and the β-tubulin genes of the hypotrichous ciliate Euplotes octocarinatus were isolated from a size-selected macronuclear DNA library. The α-tubulin gene is located on a 1,587 bp macronuclear DNA molecule and the β-tubulin gene on a 1,524 bp macronuclear DNA molecule. Sequencing revealed that all the cysteine residues of the two genes are encoded by the common cysteine codons UGU and UGC and none by an UGA codon. This is in contrast to the genes of E. octocarinatus sequenced so far, where some of the cysteines are encoded by the opal codon UGA. The tubulin genes end like other Euplotes genes with a TAA. They do not contain introns. The last codon for an amino acid in the α-tubulin gene is a GAA which codes for glutamic acid. This is in contrast to what has been reported for most α-tubulin genes, but it supports findings for other hypotrichous ciliates. No evidence for the existence of more than one type of α- and one type of β-tubulin genes could be obtained.     

A Robust Platform for Unnatural Amino Acid Mutagenesis in E. coli Using the Bacterial Tryptophanyl-tRNA synthetase/tRNA pair

We report the development of a robust user-friendly Escherichia coli (E. coli) expression system, derived from the BL21(DE3) strain, for site-specifically incorporating unnatural amino acids (UAAs) into proteins using engineered E. coli tryptophanyl-tRNA synthetase (EcTrpRS)-tRNA^Trp pairs. This was made possible by functionally replacing the endogenous EcTrpRS-tRNA^Trp pair in BL21(DE3) E. coli with an orthogonal counterpart from Saccharomyces cerevisiae, and reintroducing it into the resulting altered translational machinery tryptophanyl (ATMW-BL21) E. coli strain as an orthogonal nonsense suppressor. The resulting expression system benefits from the favorable characteristics of BL21(DE3) as an expression host, and is compatible with the broadly used T7-driven recombinant expression system. Furthermore, the vector expressing the nonsense-suppressing engineered EcTrpRS-tRNA^Trp pair was systematically optimized to significantly enhance the incorporation efficiency of various tryptophan analogs. Together, the improved strain and the optimized suppressor plasmids enable efficient UAA incorporation (up to 65% of wild-type levels) into several different proteins. This robust and user-friendly platform will significantly expand the scope of the genetically encoded tryptophan-derived UAAs.     

Hierarchical Porous Carbonized Co3O4 Inverse Opals via Combined Block Copolymer and Colloid Templating as Bifunctional Electrocatalysts in Li–O2 Battery

Hierarchically organized porous carbonized‐Co₃O₄ inverse opal nanostructures (C‐Co₃O₄ IO) are synthesized via complementary colloid and block copolymer self‐assembly, where the triblock copolymer Pluronic P123 acts as the template and the carbon source. These highly ordered porous inverse opal nanostructures with high surface area display synergistic properties of high energy density and promising bifunctional electrocatalytic activity toward both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). It is found that the as‐made C‐Co₃O₄ IO/Ketjen Black (KB) composite exhibits remarkably enhanced electrochemical performance, such as increased specific capacity (increase from 3591 to 6959 mA h g^?1), lower charge overpotential (by 284.4 mV), lower discharge overpotential (by 19.0 mV), and enhanced cyclability (about nine times higher than KB in charge cyclability) in Li–O₂ battery. An overall agreement is found with both C‐Co₃O₄ IO/KB and Co₃O₄ IO/KB in ORR and OER half‐cell tests using a rotating disk electrode. This enhanced catalytic performance is attributed to the porous structure with highly dispersed carbon moiety intact with the host Co₃O₄ catalyst.     

The impacts of abandoned mining shafts: Fauna entrapment in opal prospecting shafts at Coober Pedy, South Australia

Summary  The impacts of uncapped, abandoned mining shafts on small vertebrate species were investigated by monitoring numbers of fauna falling into opal prospecting shafts near Coober Pedy, in the far north of South Australia. Catching devices made from 10 L buckets were installed in the top of 43 shafts and checked regularly by local community members for a total of 10 840 trap nights over a 13-month period. A total of 190 individual reptiles of 18 species were captured in this manner after falling into shafts, including the nationally vulnerable Bronzeback Legless Lizard ( Ophidiocephalus taeniatus ). While the tops of these shafts resemble conventional pitfall traps used in scientific monitoring and therefore readily 'trap' ground-fauna, they may be over 30 m deep and are permanently open. Capture rates in this study, calculated at 4.1 reptiles / shaft / year, highlight the potential impact of the similar shafts that remain uncapped in the Coober Pedy opal fields, roughly estimated to be anywhere from 1 to 2 million shafts. The inferred total number of captures from these shafts may represent 10–28 million reptiles / year or an equivalent of 25–72 tonnes of biomass. The results highlight the potential threat that uncapped shafts may pose to Bronzeback Legless Lizard populations in this area and suggest that they may also have major impacts on other small vertebrate fauna in the Coober Pedy area and in other similar opal mining areas.     

Reliable and General Route to Inverse Opal Structured Nanohybrids of Carbon‐Confined Transition Metal Sulfides Quantum Dots for High‐Performance Sodium Storage

Sodium‐ion batteries (SIBs) have recently attracted increasing attention as the promising alternative to lithium‐ion batteries due to their multiple advantages of abundant reserves and low cost. However, the development of highly desirable anode materials suitable for SIBs is still hampered by a rather low capacity, poor rate capability, and cycling stability. Herein, a deliberate design to implement reliable and simple fabrication of an inverse opal structured nanohybrid of carbon‐confined various transition metal sulfides quantum dots (QDs) is presented. Comprehensive characterizations demonstrate that the hybrids hold a 3D architecture with uniform dispersion of QDs in a conductive carbon matrix that in turn encapsulates these quantum dots. With Co₉S₈ as an example, such a unique architecture, when applied as the anode of SIBs, endows the hybrids with multiple advantages including a high reversible specific capacity, extraordinary high rate capability, and excellent durability over 2000 cycles charging–discharging process.     

Silicon deficiency and the adaptation of tropical rice ecotypes

Although silicon (Si) is found at much higher concentrations in healthy rice crops than N, P or K, it has received far less study, particularly for upland rice. There are few reports on the existence, causes, and effects of varying Si supplies in different environments. Chemical analyses of soil, water and plant tissue samples from experiments grown on a typical weathered, acidic upland soil in Colombia found concentrations of Si which were 80-90% lower than those in a typical lowland environment. These results corroborate published findings from West Africa and Hawaii, and lend support to a conclusion that acid-soil upland rice environments in the tropics tend to be deficient in Si, increasing disease damage, among other effects. Critical values for diagnosis of Si deficiency in soils, water and rice husk tissue are suggested. These are reasonably consistent with, but extend the application of previously published values derived from lowland rice studies to upland environments, and use simpler sampling and analysis methods. A strong correlation was found (r = -0.91) between high husk Si concentration and low husk discoloration disease damage, among diverse rice genotypes grown in the uplands. These genotypic differences were mainly explained by their ecotypic affinities: those belonging to the tropical japonica ecotype exhibited 93% higher husk Si concentrations than indica ecotypes (ecotypic means of 23 vs. 12 mg kg^-1 ). This is consistent with a hypothesis that the tropical japonicas may have adapted to Si deficiency in their native upland environment by evolving mechanisms to attain relatively higher tissue Si concentrations than indicas, which are believed to have evolved in the lowlands, where the Si supply is generally ample. Increased understanding of Si-mediated disease resistance in different rice environments and ecotypes could help breeders combine the high yield potential of indica types with the more durable disease resistance of the japonicas, and could contribute to the development of integrated disease management strategies.     

Bacterial Insights into the Formation of Opaline Stromatolites from the Chimalacatepec Lava Tube System,Mexico

Abstract

Cave lithifying systems are excellent models to study biomineralization in the dark. The Chimalacatepec Lava Tube System in Mexico harbors diverse biospeleothems where previous studies suggest that the formation of opaline terrestrial stromatolites is related to microorganisms in contiguous mats. However, there is no information regarding their characterization and their role in mineral formation. In this study, we characterized the bacterial and archaeal composition of microbial mats and stromatolites and suggested the main processes involved in the genesis of opaline stromatolites. Our results showed that the microbial mats and stromatolites have a similar 16S rRNA gene composition, but stromatolites contain more Actinobacteria, which have been previously found in other lava tubes together with other key bacteria. Microorganisms found here belonged to groups with the potential to fix carbon and degrade organic matter. We propose that the synergic interaction of autotrophic and heterotrophic microorganisms that thrive in the dark might be inducing carbonate precipitation within the Ca-enriched extracellular polymeric substances (EPS), generating opal-A and calcite laminae. The similar 16S rRNA gene fingerprint and the presence of potential pathways that induce carbonate precipitation in opaline stromatolites and microbial mats suggest that microbial mats lithify and contribute to the stromatolite biotic genesis.