ANTARCTIC DISTRIBUTION,PIGMENT AND LIPID COMPOSITION,AND MOLECULAR IDENTIFICATION OF THE BRINE DINOFLAGELLATE POLARELLA GLACIALIS (DINOPHYCEAE)1

Polarella glacialis (Montresor et al.) was identified in Davis Station sea ice by morphological and DNA sequence comparison of cultures with those of the authentic strain P. glacialis CCMP 1383 isolated from McMurdo Sound. Cells and cysts of the Davis isolate (FL1B) were morphologically indistinguishable from P. glacialis, and comparison of the large subunit rDNA of both cultures demonstrated only 0.2% sequence divergence over 1366 base pairs. The photosynthetic pigments of P. glacialis (strains FL1B and CCMP 1383) were typical of dinoflagellates, with peridinin (contributing up to 31%) as the major accessory pigment. Extremely high levels of polyunsaturated fatty acids (PUFA, up to 76.3%) were characteristic of P. glacialis isolate FL1B. The high PUFA concentration of this species is thought to be an adaptation to survive the cold temperatures of the upper fast ice. The sterol profile of FL1B was atypical of dinoflagellates, with 4‐desmethylsterols (up to 79%) in greater abundance than 4α‐methyl sterols (up to 24%). 27‐Nor‐24‐methylcholest‐5,22E‐dien‐3β‐ol was identified as the principle sterol in P. glacialis, contributing up to 64% of the total sterol composition.     

HIV-1 Neutralizing Antibody Signatures and Application to Epitope-Targeted Vaccine Design

1. Download high-res image (267KB)
2. Download full-size image

     

The metabolic potential of the single cell genomes obtained from the Challenger Deep,Mariana Trench within the candidate superphylum Parcubacteria (OD1)

Candidate phyla (CP) are broad phylogenetic clusters of organisms that lack cultured representatives. Included in this fraction is the candidate Parcubacteria superphylum. Specific characteristics that have been ascribed to the Parcubacteria include reduced genome size, limited metabolic potential and exclusive reliance on fermentation for energy acquisition. The study of new environmental niches, such as the marine versus terrestrial subsurface, often expands the understanding of the genetic potential of taxonomic groups. For this reason, we analyzed 12 Parcubacteria single amplified genomes (SAGs) from sediment samples collected within the Challenger Deep of the Mariana Trench, obtained during the Deepsea Challenge (DSC) Expedition. Many of these SAGs are closely related to environmental sequences obtained from deep‐sea environments based on 16S rRNA gene similarity and BLAST matches to predicted proteins. DSC SAGs encode features not previously identified in Parcubacteria obtained from other habitats. These include adaptation to oxidative stress, polysaccharide modification and genes associated with respiratory nitrate reduction. The DSC SAGs are also distinguished by relative greater abundance of genes for nucleotide and amino acid biosynthesis, repair of alkylated DNA and the synthesis of mechanosensitive ion channels. These results present an expanded view of the Parcubacteria, among members residing in an ultra‐deep hadal environment.     

DNA EVIDENCE FOR NONHYBRID ORIGINS OF PARTHENOGENESIS IN NATURAL POPULATIONS OF VERTEBRATES

Naturally occurring unisexual reproduction has been documented in less than 0.1% of all vertebrate species. Among vertebrates, true parthenogenesis is known only in squamate reptiles. In all vertebrate cases that have been carefully studied, the clonal or hemiclonal taxa have originated through hybridization between closely related sexual species. In contrast, parthenogenetic reproduction has arisen in invertebrates by a variety of mechanisms, including likely cases of “spontaneous” (nonhybrid) origin, a situation not currently documented in natural populations of vertebrates. Here, we present molecular data from the Neotropical night lizard genus Lepidophyma that provides evidence of independent nonhybrid origins for diploid unisexual populations of two species from Costa Rica and Panama. Our mitochondrial and nuclear phylogenies are congruent with respect to the unisexual taxa. Based on 14 microsatellite loci, heterozygosity (expected from a hybrid origin) is low in Lepidophyma reticulatum and completely absent in unisexual L. flavimaculatum. The unique value of this system will allow direct comparative studies between parthenogenetic and sexual lineages in vertebrates, with an enormous potential for this species to be a model system for understanding the mechanisms of nonhybrid parthenogenesis.     

The plant glycosyltransferase clone collection for functional genomics

The glycosyltransferases (GTs) are an important and functionally diverse family of enzymes involved in glycan and glycoside biosynthesis. Plants have evolved large families of GTs which undertake the array of glycosylation reactions that occur during plant development and growth. Based on the Carbohydrate‐Active enZymes (CAZy) database, the genome of the reference plant Arabidopsis thaliana codes for over 450 GTs, while the rice genome (Oryza sativa) contains over 600 members. Collectively, GTs from these reference plants can be classified into over 40 distinct GT families. Although these enzymes are involved in many important plant specific processes such as cell‐wall and secondary metabolite biosynthesis, few have been functionally characterized. We have sought to develop a plant GTs clone resource that will enable functional genomic approaches to be undertaken by the plant research community. In total, 403 (88%) of CAZy defined Arabidopsis GTs have been cloned, while 96 (15%) of the GTs coded by rice have been cloned. The collection resulted in the update of a number of Arabidopsis GT gene models. The clones represent full‐length coding sequences without termination codons and are Gateway^® compatible. To demonstrate the utility of this JBEI GT Collection, a set of efficient particle bombardment plasmids (pBullet) was also constructed with markers for the endomembrane. The utility of the pBullet collection was demonstrated by localizing all members of the Arabidopsis GT14 family to the Golgi apparatus or the endoplasmic reticulum (ER). Updates to these resources are available at the JBEI GT Collection website http://www.addgene.org/ .     

Effect of Repeat Dosing of Engineered Oncolytic Herpes Simplex Virus on Preclinical Models of Rhabdomyosarcoma

Rhabdomyosarcoma (RMS), a tumor of skeletal muscle origin, is the most common sarcoma of childhood. Despite multidrug chemotherapy regimens, surgical intervention, and radiation treatment, outcomes remain poor, especially in advanced disease, and novel therapies are needed for the treatment of these aggressive malignancies. Genetically engineered oncolytic viruses, such as herpes simplex virus-1 (HSV), are currently being explored as treatments for pediatric tumors. M002, an oncolytic HSV, has both copies of the γ₁34.5 gene deleted, enabling replication in tumor cells but thwarting infection of normal, postmitotic cells. We hypothesized that M002 would infect human RMS tumor cells and lead to decreased tumor cell survival in vitro and impede tumor growth in vivo. In the current study, we demonstrated that M002 could infect, replicate in, and decrease cell survival in both embryonal (ERMS) and alveolar rhabdomyosarcoma (ARMS) cells. Additionally, M002 reduced xenograft tumor growth and increased animal survival in both ARMS and ERMS. Most importantly, we showed for the first time that repeated dosing of oncolytic virus coupled with low-dose radiation provided improved tumor response in RMS. These findings provide support for the clinical investigation of oncolytic HSV in pediatric RMS.