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At least 847 records · Page 47

SU-E-T-605: Performance Evaluation of MLC Leaf-Sequencing Algorithms in Head-And-Neck IMRT

Purpose: To investigate the efficiency of three multileaf collimator (MLC) leaf-sequencing algorithms proposed by Galvin et al, Chen et al and Siochi et al using external beam treatment plans for head-and-neck intensity modulated radiation therapy (IMRT). Methods: IMRT plans for head-and-neck were created using the CORVUS treatment planning system. The plans were optimized and the fluence maps for all photon beams determined. Three different MLC leaf-sequencing algorithms based on Galvin et al, Chen et al and Siochi et al were used to calculate the final photon segmental fields and their monitor units in delivery. For comparison purpose, the maximum intensity of fluence map was kept constant in different plans. The number of beam segments and total number of monitor units were calculated for the three algorithms. Results: From results of number of beam segments and total number of monitor units, we found that algorithm of Galvin et al had the largest number of monitor unit which was about 70% larger than the other two algorithms. Moreover, both algorithms of Galvin et al and Siochi et al have relatively lower number of beam segment compared to Chen et al. Although values of number of beam segment and total number of monitor unit calculated by different algorithms varied with the head-and-neck plans, it can be seen that algorithms of Galvin et al and Siochi et al performed well with a lower number of beam segment, though algorithm of Galvin et al had a larger total number of monitor units than Siochi et al. Conclusion: Although performance of the leaf-sequencing algorithm varied with different IMRT plans having different fluence maps, an evaluation is possible based on the calculated number of beam segment and monitor unit. In this study, algorithm by Siochi et al was found to be more efficient in the head-and-neck IMRT. The Project Sponsored by the Fundamental Research Funds for the Central Universities (J2014HGXJ0094) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

61 RADIATION PROTECTION AND DOSIMETRY↗

SU-F-T-527: A Novel Dynamic Multileaf Collimator Leaf-Sequencing Algorithm in Radiation Therapy

Purpose: A novel leaf-sequencing algorithm is developed for generating arbitrary beam intensity profiles in discrete levels using dynamic multileaf collimator (MLC). The efficiency of this dynamic MLC leaf-sequencing method was evaluated using external beam treatment plans delivered by intensity modulated radiation therapy technique. Methods: To qualify and validate this algorithm, integral test for the beam segment of MLC generated by the CORVUS treatment planning system was performed with clinical intensity map experiments. The treatment plans were optimized and the fluence maps for all photon beams were determined. This algorithm started with the algebraic expression for the area under the beam profile. The coefficients in the expression can be transformed into the specifications for the leaf-setting sequence. The leaf optimization procedure was then applied and analyzed for clinical relevant intensity profiles in cancer treatment. Results: The macrophysical effect of this method can be described by volumetric plan evaluation tools such as dose-volume histograms (DVHs). The DVH results are in good agreement compared to those from the CORVUS treatment planning system. Conclusion: We developed a dynamic MLC method to examine the stability of leaf speed including effects of acceleration and deceleration of leaf motion in order to make sure the stability of leaf speed did not affect the intensity profile generated. It was found that the mechanical requirements were better satisfied using this method. The Project is sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

60 APPLIED LIFE SCIENCES↗

Polymeric peptide pigments with sequence-encoded properties

Melanins are a family of heterogeneous polymeric pigments that provide ultraviolet (UV) light protection, structural support, coloration, and free radical scavenging. Formed by oxidative oligomerization of catecholic small molecules, the physical properties of melanins are influenced by covalent and noncovalent disorder. We report the use of tyrosine-containing tripeptides as tunable precursors for polymeric pigments. In these structures, phenols are presented in a (supra-)molecular context dictated by the positions of the amino acids in the peptide sequence. Oxidative polymerization can be tuned in a sequence-dependent manner, resulting in peptide sequence–encoded properties such as UV absorbance, morphology, coloration, and electrochemical properties over a considerable range. Short peptides have low barriers to application and can be easily scaled, suggesting near-term applications in cosmetics and biomedicine.

36 MATERIALS SCIENCE↗

Robust deep learning–based protein sequence design using ProteinMPNN

Although deep learning has revolutionized protein structure prediction, almost all experimentally characterized de novo protein designs have been generated using physically based approaches such as Rosetta. Here, we describe a deep learning–based protein sequence design method, ProteinMPNN, that has outstanding performance in both in silico and experimental tests. On native protein backbones, ProteinMPNN has a sequence recovery of 52.4% compared with 32.9% for Rosetta. The amino acid sequence at different positions can be coupled between single or multiple chains, enabling application to a wide range of current protein design challenges. We demonstrate the broad utility and high accuracy of ProteinMPNN using x-ray crystallography, cryo–electron microscopy, and functional studies by rescuing previously failed designs, which were made using Rosetta or AlphaFold, of protein monomers, cyclic homo-oligomers, tetrahedral nanoparticles, and target-binding proteins.

59 BASIC BIOLOGICAL SCIENCES↗

Improved High-Quality Draft Genome Sequence of the Eurypsychrophile Rhodotorula sp. JG1b, Isolated from Permafrost in the Hyperarid Upper-Elevation McMurdo Dry Valleys, Antarctica

Here, we report the draft genome sequence of Rhodotorula sp. strain JG1b, a yeast that was isolated from ice-cemented permafrost in the upper-elevation McMurdo Dry Valleys, Antarctica. The sequenced genome size is 19.39 Mb, consisting of 156 scaffolds and containing a total of 5,625 predicted genes. This is the first known cold-adapted Rhodotorula sp. sequenced to date.

54 ENVIRONMENTAL SCIENCES↗

Draft Genome Sequences of Supercritical CO 2 -Tolerant Bacteria Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214

We report draft genome sequences of Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214 isolated through enrichment of samples from geologic sequestration sites in pressurized bioreactors containing a supercritical (sc) CO 2 headspace. Their genome sequences expand the phylogenetic range of sequenced bacilli and allow characterization of molecular mechanisms of scCO 2 tolerance.

59 BASIC BIOLOGICAL SCIENCES↗

Near-Complete Genome Sequence of Clostridium paradoxum Strain JW-YL-7

ABSTRACT Clostridium paradoxum strain JW-YL-7 is a moderately thermophilic anaerobic alkaliphile isolated from the municipal sewage treatment plant in Athens, GA. We report the near-complete genome sequence of C. paradoxum strain JW-YL-7 obtained by using PacBio DNA sequencing and Pilon for sequence assembly refinement with Illumina data.

59 BASIC BIOLOGICAL SCIENCES↗

Draft Genome Sequence of a Rare Smut Relative, Tilletiaria anomala UBC 951

We present the draft genome sequence of the smut fungus Tilletiaria anomala UBC 951 (Basidiomycota, Ustilaginomycotina). The sequenced genome size is 18.7 Mb, consisting of 289 scaffolds and a total of 6,810 predicted genes. This is the first genome sequence published for a fungus in the order Georgefisheriales (Exobasidiomycetes).

59 BASIC BIOLOGICAL SCIENCES↗

Draft Genome Sequence of Comamonas thiooxydans Strain S23 T (DSM 17888 T ), a Thiosulfate-Oxidizing Bacterium Isolated from a Sulfur Spring in India

The genus Comamonas contains species isolated from various environments, such as termite guts, wetlands, activated sludge, soil, humans, and fresh water. Here, we report the draft genome sequence of Comamonas thiooxydans strain S23 T capable of oxidizing thiosulfate under mixotrophic growth conditions. Based upon draft genome sequencing, the genome is 5.3 Mb and encodes 4,767 proteins. The Comamonas thiooxydans whole-genome sequence will help understand the metabolic diversity in sulfur oxidation pathways.

54 ENVIRONMENTAL SCIENCES↗

Genome Sequence of Prosthecochloris sp. Strain CIB 2401 of the Phylum Chlorobi

ABSTRACT To date, only 13 genomes of green sulfur bacteria (family Chlorobiaceae ) have been sequenced. The sequenced strains do not cover the full phylogenetic diversity of the family. We determined the complete genome sequence of Prosthecochloris sp. strain CIB 2401, thereby increasing the genome information for the poorly represented marine Chlorobiaceae .

59 BASIC BIOLOGICAL SCIENCES↗

Complete Genome Sequences of Four Escherichia coli ST95 Isolates from Bloodstream Infections

Finished genome sequences are presented for four Escherichia coli strains isolated from bloodstream infections at San Francisco General Hospital. These strains provide reference sequences for four major fimH -identified sublineages within the multilocus sequence type (MLST) ST95 group, and provide insights into pathogenicity and differential antimicrobial susceptibility within this group.

59 BASIC BIOLOGICAL SCIENCES↗

Draft Genome Sequences for Two Metal-Reducing Pelosinus fermentans Strains Isolated from a Cr(VI) Contaminated Site and for Type Strain R7

Pelosinus fermentans 16S rRNA gene sequences have been reported from diverse geographical sites since the recent isolation of the type strain. We present the genome sequence of the P. fermentans type strain R7 (DSM 17108) and genome sequences for two new strains with different abilities to reduce iron, chromate, and uranium.

59 BASIC BIOLOGICAL SCIENCES↗

More of an art than a science: Using microbial DNA sequences to compose music

Bacteria are everywhere. Microbial ecology is emerging as a critical field for understanding the relationships between these ubiquitous bacterial communities, the environment, and human health. Next generation DNA sequencing technology provides us a powerful tool to indirectly observe the communities by sequencing and analyzing all of the bacterial DNA present in an environment. The results of the DNA sequencing experiments can generate gigabytes to terabytes of information however, making it difficult for the citizen scientist to grasp and the educator to convey this data. Here, we present a method for interpreting massive amounts of microbial ecology data as musical performances, easily generated on any computer and using only commonly available or freely available software and the ‘Microbial Bebop’ algorithm. Furthermore, using this approach citizen scientists and biology educators can sonify complex data in a fun and interactive format, making it easier to communicate both the importance and the excitement of exploring the planet earth’s largest ecosystem.

59 BASIC BIOLOGICAL SCIENCES↗

Complete Genome Sequence of Acidithiobacillus ferridurans JAGS, Isolated from Acidic Mine Drainage

We report a complete genome sequence of Acidithiobacillus ferridurans JAGS, determined using PacBio single-molecule real-time (SMRT) sequencing. The circular genome of JAGS (2,933,811 bp; GC content, 58.57%) contains 3,001 protein-coding sequences, 46 tRNAs, and 6 rRNAs. Predicted genes indicate the potential to fix CO 2 and N 2 and to utilize Fe 2+ , S0, and H 2 as energy sources.

59 BASIC BIOLOGICAL SCIENCES↗