Incompletely base-paired flip-flop terminal loops link the two DNA strands of the vaccinia virus genome into one uninterrupted polynucleotide chain

The nature of the ends of the vaccinia virus genome was determined by nucleotide sequencing. Our finding of terminal hairpins indicated that the linear double-stranded DNA molecule consists of a single continuous polynucleotide chain. The 104 nucleotide apex of the hairpin contains predominantly A and T residues and is incompletely base-paired. These loops exist in two forms, which when inverted with respect to each other are complementary in sequence. Both forms of the 104 nucleotide loop are present in nearly equimolar amounts at each end of the genome. A set of 13 tandem 70 bp repeats begins 87 bp from the proximal segment of the terminal loop, followed by a unique sequence of 325 bp, and then by a second set of 18 tandem 70 bp repeats. The sequence of the 70 bp repeats reveals a 13 bp internal redundancy. Self-priming and de novo start replication models, which involve a site-specific nick in one DNA strand proximal to the 104 nucleotide loop, account for the observed sequence inversions and incomplete base-pairing. Similar mechanisms may be involved in replication of the ends of the eucaryotic chromosome.     

Reproduction of the Indian wild dog (Cuon alpinus) in captivity

The reproductive behavior and development of 3 wild-caught and 2 captive-born dholes (Cuon alpinus) was observed at the Arignar Anna Zoological Park during 4 successive mating seasons. Courtship was characterized by frequent urine marking and vocalizing by both sexes, by olfactory inspection of marked spots and of partners' genitalia, and by the female's licking and mounting of the male. Dholes exhibited the copulatory tie and back-to-back copulatory posture that is typical of other canids. Estrus may be longer, and the frequency of copulation higher, than is seen in other canids, however. The 4 litters born to the wild-caught pair yielded information on growth and development. A captive-born pair first began to show signs of sexual activity at 11 months of age. © 1992 Wiley-Liss Inc.     

Enhancing Protein A performance in mAb processing: A method to reduce and rapidly evaluate host cell DNA levels during primary clarification

The use and impact of 3M™ Emphaze™ AEX Hybrid Purifier, a single-use, fully synthetic chromatographic product, was explored to reduce host cell DNA (HC-DNA) concentration during the primary clarification of a monoclonal antibody (mAb). An approximately 5-log reduction in HC-DNA was achieved at an Emphaze AEX Hybrid Purifier throughput of 200 L/m². The appreciable reduction in HC-DNA achieved during primary clarification enhanced Protein A chromatography performance, resulting in a sharper and narrower elution profile. In addition, a 24× improvement in host cell protein (HCP) removal and fewer impurities nonspecifically bound to the Protein A column were observed compared to those resulting from the use of depth filtration for clarification. The use of a rapid, qualitative acidification assay to facilitate HC-DNA monitoring was also investigated. This assay involves the acidification-induced precipitation of HC-DNA, enabling the easy and rapid detection of DNA breakthrough across purification media such as Emphaze AEX Hybrid Purifier by means of turbidimetric and particle size measurements.     

Integrating structure-based machine learning and co-evolution to investigate specificity in plant sesquiterpene synthases

Sesquiterpene synthases (STSs) catalyze the formation of a large class of plant volatiles called sesquiterpenes. While thousands of putative STS sequences from diverse plant species are available, only a small number of them have been functionally characterized. Sequence identity-based screening for desired enzymes, often used in biotechnological applications, is difficult to apply here as STS sequence similarity is strongly affected by species. This calls for more sophisticated computational methods for functionality prediction. We investigate the specificity of precursor cation formation in these elusive enzymes. By inspecting multi-product STSs, we demonstrate that STSs have a strong selectivity towards one precursor cation. We use a machine learning approach combining sequence and structure information to accurately predict precursor cation specificity for STSs across all plant species. We combine this with a co-evolutionary analysis on the wealth of uncharacterized putative STS sequences, to pinpoint residues and distant functional contacts influencing cation formation and reaction pathway selection. These structural factors can be used to predict and engineer enzymes with specific functions, as we demonstrate by predicting and characterizing two novel STSs from Citrus bergamia.     

Sodium nitroprusside enhances callus induction and shoot regeneration in high value medicinal plant Canscora diffusa

Plant Cell, Tissue and Organ Culture (PCTOC) - In different countries, mostly in EU, rules for strawberry nursery propagation impose the use of micropropagation only to produce stock virus free...     

FUS contributes to mTOR-dependent inhibition of translation

The amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD)–linked RNA-binding protein called FUS (fused in sarcoma) has been implicated in several aspects of RNA regulation, including mRNA translation. The mechanism by which FUS affects the translation of polyribosomes has not been established. Here we show that FUS can associate with stalled polyribosomes and that this association is sensitive to mTOR (mammalian target of rapamycin) kinase activity. Specifically, we show that FUS association with polyribosomes is increased by Torin1 treatment or when cells are cultured in nutrient-deficient media, but not when cells are treated with rapamycin, the allosteric inhibitor of mTORC1. Moreover, we report that FUS is necessary for efficient stalling of translation because deficient cells are refractory to the inhibition of mTOR-dependent signaling by Torin1. We also show that ALS-linked FUS mutants R521G and P525L associate abundantly with polyribosomes and decrease global protein synthesis. Importantly, the inhibitory effect on translation by FUS is impaired by mutations that reduce its RNA-binding affinity. These findings demonstrate that FUS is an important RNA-binding protein that mediates translational repression through mTOR-dependent signaling and that ALS-linked FUS mutants can cause a toxic gain of function in the cytoplasm by repressing the translation of mRNA at polyribosomes.