Functional Self-assembling Peptide Research Articles

Cooperative assembly of a designer peptide and silk fibroin into hybrid nanofiber gels for neural regeneration after spinal cord injury.

Local reconstruction of a permissive environment with biomaterials is a promising strategy to treat spinal cord injury (SCI). We reported a hybrid hydrogel fabricated from a small functional self-assembling peptide (F-SAP) and large silk fibroin (SF). The diffusion of SF micelles into F-SAP solution was driven by the dynamic synergy between osmotic pressure and F-SAP/SF electrostatic interactions, resulting in the rearrangement of SF micelles and the formation of rod-like filaments with axes nearly perpendicular to F-SAP nanofibers. Spectroscopy analysis, including circular dichroism, Raman and fluorescence, indicated conformation changes of SF from random coil to β sheet, which contributed to enhanced mechanical properties of the resultant hybrid hydrogel. Furthermore, the F-SAP/SF hybrid hydrogel coupled with controlled release of NT-3 provided a permissive environment for neural regeneration by providing nanofibrous substrates for regenerating axons, inflammatory modulation and remyelination, consequently resulting in improved locomotion and electrophysiological properties. This hydrogel could be used as a long-term stent in vivo for the treatment of SCI.

Repair of critical-sized rat cranial defects with RADA16-W9 self-assembled peptide hydrogel

Bone defects are common in orthopaedics and there is an urgent need to explore effective bone repair materials with osteoinductive activity. Peptide self-assembled nanomaterials have a fibrous structure like that of the extracellular matrix and are ideal bionic scaffold materials. In this study, a short peptide WP9QY (W9) with strong osteoinductive effect was tagged to a self-assembled peptide RADA16 molecule through solid phase synthesis to design a RADA16-W9 peptide gel scaffold. A rat cranial defect was used as a research model to explore the effect of this peptide material on the repair of bone defects in vivo. The structure characteristic of the functional self-assembling peptide nanofiber hydrogel scaffold RADA16-W9 was evaluated by atomic force microscopy (AFM). Then adipose stem cells (ASCs) were isolated from Sprague-Dawley (SD) rat and cultured. the cellular compatibility of scaffold was evaluated through Live/Dead assay. Furthermore, we explore the effects of hydrogels in vivo with the critical-sized mouse calvarial defect model. Micro-CT analysis showed that the RADA16-W9 group had higher levels of bone volume/total volume (BV/TV) (P < 0.05)，Trabecular number(TB.N) (P < 0.05)，bone mineral density (BMD)(P < 0.05) and trabecular thickness (Tb. Th) (P < 0.05) compared with the RADA16 and PBS groups. Hematoxylin and eosin (H&E) staining showed that RADA16-W9 group had the highest bone regeneration level. Histochemical staining showed significantly higher expression levels of osteogenic factors such as alkaline phosphatase (ALP) and osteocalcin (OCN) in the RADA16-W9 group than in the other two groups (P < 0.05). Reverse transcription polymerase chain reaction (RT-PCR) quantification showed higher mRNA expression levels of osteogenic-related genes ALP, Runt-related transcription factor 2(Runx2), OCN, Osteopontin (OPN) in the RADA16-W9 group than in the RADA16 and PBS groups (P < 0.05). The live/dead staining results showed that RADA16-W9 is not toxic to rASCs and has good biocompatibility. In vivo experiments show that it accelerates the process of bone reconstruction, significantly promoting bone regeneration and can be used to develop a molecular drug for bone defect repair.

Remodeling Microenvironment for Endogenous Repair through Precise Modulation of Chondroitin Sulfate Proteoglycans Following Spinal Cord Injury.

The fluid-filled cystic cavity sealed by a dense scar developed following traumatic spinal cord injury (SCI) has been a major obstacle to neural regeneration and functional recovery. Here the transected lesion is bridged using a functional self-assembling peptide (F-SAP) hydrogel loaded with membrane-permeable intracellular sigma peptide (ISP) and intracellular LAR peptide (ILP), targeted at perturbing chondroitin sulfate proteoglycan (CSPG) inhibitory signaling. As compared to F-SAP hydrogel loaded with chondroitinase ABC, the F-SAP+ISP/ILP promotes a beneficial anti-inflammatory response via manipulation of microglia/macrophages infiltration and assembly of extracellular matrix (ECM) molecules into fibrotic matrix rather than scarring tissues. The remodeled ECM creates a permissive environment that supports axon regrowth and the formation of synaptic connections with neurons derived from endogenous neural stem cells. The remodeled networks contribute to functional recovery, as demonstrated by improved hind limb movements and electrophysiological properties. This work proposes a unique mechanism that ECM remodeling induced by CSPG-manipulation-based anti-inflammation can construct a permissive environment for neural regeneration, and shed light on the advancement of manipulation of cascading cellular and molecular events potential for endogenous repair of SCI.

Sa12b-Modified Functional Self-Assembling Peptide Hydrogel Enhances the Biological Activity of Nucleus Pulposus Mesenchymal Stem Cells by Inhibiting Acid-Sensing Ion Channels

Various hydrogels have been studied for nucleus pulposus regeneration. However, they failed to overcome the changes in the acidic environment during intervertebral disc degeneration. Therefore, a new functionalized peptide RAD/SA1 was designed by conjugating Sa12b, an inhibitor of acid-sensing ion channels, onto the C-terminus of RADA16-I. Then, the material characteristics and biocompatibility of RAD/SA1, and the bioactivities and mechanisms of degenerated human nucleus pulposus mesenchymal stem cells (hNPMSCs) were evaluated. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) confirmed that RAD/SA1 self-assembling into three-dimensional (3D) nanofiber hydrogel scaffolds under acidic conditions. Analysis of the hNPMSCs cultured in the 3D scaffolds revealed that both RADA16-I and RAD/SA1 exhibited reliable attachment and extremely low cytotoxicity, which were verified by SEM and cytotoxicity assays, respectively. The results also showed that RAD/SA1 increased the proliferation of hNPMSCs compared to that in culture plates and pure RADA16-I. Quantitative reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and western blotting demonstrated that the expression of collagen I was downregulated, while collagen II, aggrecan, and SOX-9 were upregulated. Furthermore, Ca2+ concentration measurement and western blotting showed that RAD/SA1 inhibited the expression of p-ERK through Ca2+-dependent p-ERK signaling pathways. Therefore, the functional self-assembling peptide nanofiber hydrogel designed with the short motif of Sa12b could be used as an excellent scaffold for nucleus pulposus tissue engineering. Moreover, RAD/SA1 exhibits great potential applications in the regeneration of mildly degenerated nucleus pulposus.

Engineering an Injectable Electroactive Nanohybrid Hydrogel for Boosting Peripheral Nerve Growth and Myelination in Combination with Electrical Stimulation.

Electrical stimulation (ES) can be used to manipulate recovery after peripheral nerve injuries. Although biomaterial-based strategies have already been implemented to gain momentum for ES and engineer permissive microenvironments for neural regeneration, the development of biomaterials for specific stimuli-responsive modulation of neural cell properties remains a challenge. Herein, we homogeneously incorporate pristine carbon nanotubes into a functional self-assembling peptide to prepare a hybrid hydrogel with good injectability and conductivity. Two-dimensional (on the surface) and three-dimensional (within the hybrid hydrogel) culturing experiments demonstrate that ES promotes axon outgrowth and Schwann cell (SC) migration away from dorsal root ganglia spheres, further revealing that ES-enhanced interactions between SCs and axons result in improved myelination. Thus, our study not only advances the development of tailor-made materials but also provides useful insights into comprehensive approaches for promoting nerve growth and presents a practical strategy of repairing peripheral nerve injuries.

SUN-027 Delivery of MSCs with a Hybrid β-sheet Peptide Hydrogel Consisting IGF-1C Domain and D-form Peptide for Acute Kidney Injury Therapy

By providing an appropriate microenvironment, synthetic biomaterials have been progressively successful in stem cell-based tissue regeneration by enhancing the engraftment and survival of transplanted cells. The designs with bioactive motifs to influence cell behavior and with D-form amino acid to modulate scaffold stability will be critical for the development and optimization of self-assembling biomimetic hydrogel scaffolds for stem cell therapy. In this study, we linked naphthalene (Nap) covalently conjugated a short D-form peptide (Nap-DFDFG) to C domain of insulin-like growth factor-1 (IGF-1C) as a functional peptide-based scaffold. Our purpose is to provide a functional self-assembling peptide hydrogel with encapsulated human placenta derived mesenchymal stem cells (hP-MSCs) and thereby to enhance the therapeutic efficiency of hP-MSCs in murine acute kidney injury (AKI) model. Our results revealed that a typical β-sheet conformation was confirmed and this self-assembling peptide hydrogel exhibited higher affinity with IGF-1 receptor. Furthermore, this hydrogel could provide a favorable niche for hP-MSCs and thereby ameliorate renal function in an AKI model by promoting cell survival and angiogenesis. In conclusion, by covalently linking the desired functional group to D-form peptide to create a functional hydrogel, this self-assembling β-sheet peptide hydrogel will serve as a promising platform for future tissue-engineering and stem cell therapy. We prepared a supramolecular self-assembly peptide Nap-DFDFG-IGF-1C by standard solid phase peptide synthesis (SPPS), and profiled the characteristics by circular dichroism (CD) analysis, surface plasmon resonance (SPR), transmission electron microscope (TEM) and rheological analysis. For real-time tracing the cell fate post transplantation, we introduced dual fusion MSCs which express firefly luciferase and GFP simultaneously. Also we utilized the bioluminescence imaging (BLI) to longitudinally monitor the dynamics of cell retention and renal angiogenesis. Serial experiments have bee done to evaluate the putative therapeutic effect for AKI. We here reported a hybrid self-assembly peptide Nap-DFDFG-IGF-1C. CD analysis revealed the peptide was constrained to a typical β-sheet conformation via a heating-cooling pathway, leading to an enhanced affinity with recombinant human IGF-1 receptor (rhIGF-1R) comfirmed by SPR. A cross-linked nanofibrous structure was observed by TEM and the rheological analysis evidenced its hydrogel property. Our BLI results showed that delivery of MSCs with the IGF-1C hydrogel contribute to an enhanced cell retention and renal angiogenesis, which rsulted in repair and regeneration post AKI. In summary, we reported a cell enhancement strategy with a hybrid β-sheet peptide hydrogel which holds bioactive motif IGF-1C as functional backbone for the first time. This hydrogel favors cell retention, provides a pro-angiogenesis niche for the transplanted cells, and thereby restored the renal architecture and function post AKI. This study introduced a brand-new strategy for integration of self-assembly peptide and stem cell therapy and might shed light into the development of tissue engineering as well as regeneration medicine.

Delivery of MSCs with a Hybrid β-Sheet Peptide Hydrogel Consisting IGF-1C Domain and D-Form Peptide for Acute Kidney Injury Therapy

By providing an appropriate microenvironment, synthetic biomaterials have been progressively successful in stem cell-based tissue regeneration by enhancing the engraftment and survival of transplanted cells. The designs with bioactive motifs to influence cell behavior and with D-form amino acid to modulate scaffold stability will be critical for the development and optimization of self-assembling biomimetic hydrogel scaffolds for stem cell therapy. In this study, we linked naphthalene (Nap) covalently conjugated a short D-form peptide (Nap-DFDFG) to C domain of insulin-like growth factor-1 (IGF-1C) as a functional peptide-based scaffold. Our purpose is to provide a functional self-assembling peptide hydrogel with encapsulated human placenta derived mesenchymal stem cells (hP-MSCs) and thereby to enhance the therapeutic efficiency of hP-MSCs in murine acute kidney injury (AKI) model. Our results revealed that a typical β-sheet conformation was confirmed and this self-assembling peptide hydrogel exhibited higher affinity with IGF-1 receptor. Furthermore, this hydrogel could provide a favorable niche for hP-MSCs and thereby ameliorate renal function in an AKI model by promoting cell survival and angiogenesis. In conclusion, by covalently linking the desired functional group to D-form peptide to create a functional hydrogel, this self-assembling β-sheet peptide hydrogel will serve as a promising platform for future tissue-engineering and stem cell therapy.

Neural differentiation of bone marrow mesenchymal stem cells with human brain-derived neurotrophic factor gene-modified in functionalized self-assembling peptide hydrogel in vitro.

To investigate the biocompatibility and differentiation of human brain-derived neurotrophic factor (hBDNF) gene-modified bone marrow mesenchymal stem cells (hBDNF-rMSCs) in a functionalized self-assembling peptide hydrogel. hBDNF was engineered in rMSCs using adenovirus vector and the enhanced green fluorescence protein (eGFP) was used as a reporter gene. Mesenchymal stem cell-specific surface markers (CD90, CD29, and CD45) were used for identifying rat-derived MSCs. Fluorescence microscope was used to detect the transfection of rMSCs. hBDNF-rMSCs and control cells (eGFP-rMSCs) were seeded in a functional self-assembling peptide hydrogel (RADA16-PRG hydrogel) and a control hydrogel (RADA16 hydrogel). Cells were divided into three groups (hBDNF-rMSCs + RADA16 hydrogel, hBDNF-rMSCs + RADA16-PRG hydrogel, and eGFP-rMSCs + RADA16-PRG hydrogel) and a control group (eGFP-rMSCs + RADA16 hydrogel). Cell growth, cell proliferation, expression of hBDNF-mRNA, the level of hBDNF, neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP) protein were analyzed for each group. rMSCs were positive for CD90 and CD29 and negative for CD45, green fluorescence was strongly visible at 72 hours after transfection. Compared with control group, the expression of hBDNF-mRNA and levels of hBDNF protein in both hBDNF group were significantly increased (P < 0.01), the cell growth, cell proliferation, and levels of NSE and GFAP protein were significantly increased in three groups ( P < 0.01). Cell growth, cell proliferation, expression of hBDNF-mRNA, and levels of hBDNF, NSE, and GFAP protein in hBDNF-rMSCs + RADA16-PRG hydrogel group were significantly higher than that of hBDNF-rMSCs + RADA16 hydrogel group ( P < 0.01). Bone marrow MSCs can be induced into neural cells by the human brain-derived neurotrophic factor gene in a RADA16-PRG functionalized self-assembling peptide hydrogel.

Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells.

A modular route to prepare functional self-assembling dendritic peptide amphiphiles decorated with mannosides, to effectively target antigen-presenting cells, such as macrophages, is reported. The monomeric building blocks were equipped with tetra(ethylene glycol)s (TEGs) or labeled with a Cy3 fluorescent probe. Experiments on the uptake of the multifunctional supramolecular particles into murine macrophages (Mφs) were monitored by confocal microscopy and fluorescence-activated cell sorting. Mannose-decorated supramolecular polymers trigger a significantly higher cellular uptake and distribution, relative to TEG carrying bare polymers. No cytotoxicity or negative impact on cytokine production of the treated Mφs was observed, which emphasized their biocompatibility. The modular nature of the multicomponent supramolecular polymer coassembly protocol is a promising platform to develop fully synthetic multifunctional vaccines, for example, in cancer immunotherapy.

Functional self-assembling peptide nanofiber hydrogel for peripheral nerve regeneration.

Peripheral nerves are fragile and easily damaged, usually resulting in nervous tissue loss, motor and sensory function loss. Advances in neuroscience and engineering have been significantly contributing to bridge the damage nerve and create permissive environment for axonal regrowth across lesions. We have successfully designed two self-assembling peptides by modifying RADA 16-I with two functional motifs IKVAV and RGD. Nanofiber hydrogel formed when combing the two neutral solutions together, defined as RADA 16-Mix that overcomes the main drawback of RADA16-I associated with low pH. In the present study, we transplanted the RADA 16-Mix hydrogel into the transected rat sciatic nerve gap and effect on axonal regeneration was examined and compared with the traditional RADA16-I hydrogel. The regenerated nerves were found to grow along the walls of the large cavities formed in the graft of RADA16-I hydrogel, while the nerves grew into the RADA 16-Mix hydrogel toward distal position. RADA 16-Mix hydrogel induced more axons regeneration and Schwann cells immigration than RADA16-I hydrogel, resulting in better functional recovery as determined by the gait-stance duration percentage and the formation of new neuromuscular junction structures. Therefore, our results indicated that the functional SAP RADA16-Mix nanofibrous hydrogel provided a better environment for peripheral nerve regeneration than RADA16-I hydrogel and could be potentially used in peripheral nerve injury repair.

Transplantation of RADA16-BDNF peptide scaffold with human umbilical cord mesenchymal stem cells forced with CXCR4 and activated astrocytes for repair of traumatic brain injury.

In this reach, we specifically linked RGIDKRHWNSQ, a functional peptide derived from BDNF, to the C-terminal of RADARADARADARADA (RADA16) to structure a functional self-assembling peptide hydrogel scaffold, RADA16-BDNF (R-B-SPH scaffold) for the better transplantation of the double cell unit. Also, the novel scaffold was used as cell-carrier for transplantation double cell unit (hUC-MSCs/astrocyte) for treating traumatic brain injury. The results of this study showing that R-B-SPH scaffold was pliancy and flexibility to fit the brain lesion cavity and promotes the outgrowth of axons and dendrites of the neurons derived from hUC-MSCs in vitro and in vivo, indicating the 3D R-B-SPH scaffold provided a suitable microenvironment for hUC-MSC survival, proliferation and differentiation. Also, our results showing the double-cells transplantation system (hUC-MSCs/astrocyte) may be a novel cell-based therapeutic strategy for neuroregeneration after TBI with potential value for clinical application.

Functional Self-Assembling Peptide Nanofiber Hydrogels Designed for Nerve Degeneration.

Self-assembling peptide (SAP) RADA16-I (Ac-(RADA)4-CONH2) has been suffering from a main drawback associated with low pH, which damages cells and host tissues upon direct exposure. In this study, we presented a strategy to prepare nanofiber hydrogels from two designer SAPs at neutral pH. RADA16-I was appended with functional motifs containing cell adhesion peptide RGD and neurite outgrowth peptide IKVAV. The two SAPs were specially designed to have opposite net charges at neutral pH, the combination of which created a nanofiber hydrogel (-IKVAV/-RGD) characterized by significantly higher G' than G″ in a viscoelasticity examination. Circular dichroism, Fourier transform infrared spectroscopy, and Raman measurements were performed to investigate the secondary structure of the designer SAPs, indicating that both the hydrophobic/hydrophilic properties and electrostatic interactions of the functional motifs play an important role in the self-assembling behavior of the designer SAPs. The neural progenitor cells (NPCs)/stem cells (NSCs) fully embedded in the 3D-IKVAV/-RGD nanofiber hydrogel survived, whereas those embedded within the RADA 16-I hydrogel hardly survived. Moreover, the -IKVAV/-RGD nanofiber hydrogel supported NPC/NSC neuron and astrocyte differentiation in a 3D environment without adding extra growth factors. Studies of three nerve injury models, including sciatic nerve defect, intracerebral hemorrhage, and spinal cord transection, indicated that the designer -IKVAV/-RGD nanofiber hydrogel provided a more permissive environment for nerve regeneration than the RADA 16-I hydrogel. Therefore, we reported a new mechanism that might be beneficial for the synthesis of SAPs for in vitro 3D cell culture and nerve regeneration.

Biological Evaluation of Human Degenerated Nucleus Pulposus Cells in Functionalized Self-Assembling Peptide Nanofiber Hydrogel Scaffold

Nucleus pulposus (NP) tissue engineering has been proposed as a novel biological treatment for early-stage intervertebral disc degeneration. In this study, a novel functional self-assembling peptide PKP was first designed by linking the short functional motif of bone morphogenetic protein-7 (BMP7) to the C-terminal of RADA16-I, and another new functional self-assembling peptide was obtained by mixing RKP with RADA16-I. Then, the biocompatibilities and bioactivities of RKP and RAD-RKP for human degenerated nucleus pulposus cells (hNPCs) were studied in vitro. Atomic force microscopy and scanning electron microscopy (SEM) confirmed that both RKP and RAD-RKP could self-assemble into three-dimensional (3D) nanofiber hydrogel scaffolds in a culture medium at 37°C. After the hNPCs were cultured in 3D scaffolds, both RKP and RAD-RKP exhibited reliable attachment and extremely low cytotoxicities (<14%), which were verified by SEM and cytotoxity assays, respectively. Our results also showed that the functional-based scaffolds could increase the proliferation and migration of hNPCs after 7 days compared with culture plates and pure RADA16-I. Quantitative real-time polymerase chain reaction demonstrated that the expressions of collagen II α1, Sox-9, and aggrecan were upregulated, while collagen I α1 was downregulated by functional-based scaffolds after 28 days. Furthermore, we also confirmed that RAD-RKP exhibited a higher hNPC proliferation, migration, and expression of Sox-9 and aggrecan compared with pure RKP. Therefore, the results of this study indicated that the BMP7 short motif-designed functional self-assembling peptide nanofiber hydrogels could be used as excellent scaffolds in NP tissue engineering, and RAD-RKP might have further potential application in human mild degenerated NP tissue regeneration.

Neural stem cells encapsulated in a functionalized self-assembling peptide hydrogel for brain tissue engineering

Brain injury is almost irreparable due to the poor regenerative capability of neural tissue. Nowadays, new therapeutic strategies have been focused on stem cell therapy and supplying an appropriate three dimensional (3D) matrix for the repair of injured brain tissue. In this study, we specifically linked laminin-derived IKVAV motif on the C-terminal to enrich self-assembling peptide RADA16 as a functional peptide-based scaffold. Our purpose is providing a functional self-assembling peptide 3D hydrogel with encapsulated neural stem cells to enhance the reconstruction of the injured brain. The physiochemical properties reported that RADA16-IKVAV can self-assemble into nanofibrous morphology with bilayer β–sheet structure and become gelationed hydrogel with mechanical stiffness similar to brain tissue. The in vitro results showed that the extended IKVAV sequence can serve as a signal or guiding cue to direct the encapsulated neural stem cells (NSCs) adhesion and then towards neuronal differentiation. Animal study was conducted in a rat brain surgery model to demonstrate the damage in cerebral neocortex/neopallium loss. The results showed that the injected peptide solution immediately in situ formed the 3D hydrogel filling up the cavity and bridging the gaps. The histological analyses revealed the RADA16-IKVAV self-assembling peptide hydrogel not only enhanced survival of encapsulated NSCs but also reduced the formation of glial astrocytes. The peptide hydrogel with IKVAV extended motifs also showed the support of encapsulated NSCs in neuronal differentiation and the improvement in brain tissue regeneration after 6 weeks post-transplantation.

NIH Grant Watch

BioTechniquesVol. 45, No. 3 NIH Grant WatchOpen AccessNIH Grant WatchK. Nybo† & B. Perry††K. Nybo††is assistant editor at BioTechniques.Search for more papers by this author & B. Perry††††is president of NIH Sales, Rockville, MD.Search for more papers by this authorPublished Online:16 May 2018https://doi.org/10.2144/000112941AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail Self-assembling Peptides; Non-invasive Optical Brain ImagingBioTechniques and NIH Sales reviewed grants made by the National Institutes of Health during the last 30 days. Here are some highlights from among the largest 100 R01 and R03 grants awarded during July 2008.Self-assembling Peptides for Tissue Engineering $1,348,457(5R01EB003805-04, National Institute of Biomedical Imaging and Bioengineering) Alan Grodzinsky (Massachusetts Institute of Technology, Cambridge, MA)Goal: To design functional self-assembling peptide sequences for 3-D tissue engineering, measure and model the biophysics of the peptide self-assembly environment, and explore these environments in myocardium, cartilage, and liver. Experts in electrical, mechanical, and chemical engineering will collaborate with chemists, biologists, and clinical scientists to complete these aims.Non-invasive Optical Imaging of Neuropathology In Vivo $800,811(5R01AG026240-03, National Institute on Aging)Brian Bacskai (Massachusetts General Hospital, Boston, MA)Goal: To improve optical imaging techniques and generate novel contrast reagents for near-infrared molecular imaging. The multidisciplinary program includes advancement of the hardware and software of an existing optical imaging system and development of molecular imaging probes that target specific intracranial structures for in vivo imaging of neurological disease.Whole-genome Shotgun Sequencing Strategy and Assembly $759,485(5R01HG003474-04, National Human Genome Research Institute)David Jaffe (Massachusetts Institute of Technology, Cambridge, MA)Goal: To produce better quality genome sequences at lower cost by improving assembly of whole-genome shotgun sequencing data. This program will optimize strategy selection criteria for sequencing new organisms, develop algorithms for more accurate and complete genome assembly, and implement strict tests to maintain internal consistency.Molecular Analysis of Hotspots of Genetic Recombination $749,889(5R01GM031693-26A2, National Institute of General Medical Sciences)Gerald Smith (Fred Hutchinson Cancer Research Center, Seattle, WA)Goal: To understand the mechanism and regulation of recombination along chromosomes and across lifespan. This will be accomplished by studying hotspots of recombination in Escherichia coli and Schizosaccharomyces pombe to determine the proteins involved in recombinant structure formation and their interactions and to assess the roles of chromatin modifications in regulating recombination sites.The following six grants were awarded for the development of databases or software that may become valuable research tools for those working in the biosciences:Yeast Genetic Interaction Map $1,410,493(5R01HG002432-06, National Human Genome Research Institute)Jef Boeke (Johns Hopkins University, Baltimore, MD)Building a Framework for Exploration of Orthologs and Evolutionary Distances $84,500(5R03LM009261-02, National Library of Medicine)Dennis Wall (Harvard University Medical School, Boston, MA)Gene Expression Database for Mouse Development $1,017,606(5R01HD033745-11, National Institute of Child Health and Human Development)Martin Ringwald (Jackson Laboratory, Bar Harbor, ME)Comparative Toxicogenomics Database (CTD) $854,606(5R01ES014065-03, National Institute of Environmental Health Sciences)Carolyn Mattingly (Mount Desert Island Biological Lab, Salisbury Cove, ME)Dissemination of Cross-platform Software for Artifact Detection and Region of Interest $162,238(1R03EB008673-01, National Institute of Biomedical Imaging and Bioengineering)Satrajit Ghosh (Massachusetts Institute of Technology, Cambridge, MA)FiguresReferencesRelatedDetails Vol. 45, No. 3 Follow us on social media for the latest updates Metrics Downloaded 97 times History Published online 16 May 2018 Published in print September 2008 Information© 2008 Author(s)PDF download