Generation 2 Research Articles

Blindness in Smoky Joe roosters results in advanced sexual maturation

Perttula, J. and Bédécarrats, G. Y. 2012. Blindness in Smoky Joe roosters results in advanced sexual maturation. Can. J. Anim. Sci. 92: 483–491. In chickens, an increase in photoperiod activates the hypothalamo-pituitary gonadal axis resulting in sexual maturation. Although it is well established that light can directly stimulate the hypothalamus, the relative contribution of the eye in the control of reproduction is still controversial. Using a genetically blind line of chickens (Smoky Joe), we investigated the relative importance of the retina of the eye in sexual maturation in roosters. Furthermore, to evaluate the effect of photostimulation, three generations of blind and sighted Smoky Joe roosters were utilize. Generation 1 (G1) was photostimulated at 17 wk of age, while generation 2 (G2) was left un-photostimulated and generation 3 (G3) was photostimulated at 12 wk of age. Blind roosters in G1 and G2 matured between 17 and 19 wk of age (testicular weight, comb length) independently of photostimulation whereas maturation of sighted animals was significantly delayed in G2. However, this advanced sexual maturation was no longer evident when birds were stimulated at 12 wk of age. Blind roosters in G2 showed advanced spermatogenesis when compared with sighted animals. No significant difference in plasma testosterone levels was observed for any of the three generations. In conclusion, although still photosensitive, blind rooster sexually matured spontaneously earlier than their sighted counterpart.

Blindness in Smoky Joe roosters results in advanced sexual maturation

Perttula, J. and Bedecarrats, G. Y. 2012. Blindness in Smoky Joe roosters results in advanced sexual maturation. Can. J. Anim. Sci. 92: 483-491. In chickens, an increase in photoperiod activates the hypothalamo-pituitary gonadal axis resulting in sexual maturation. Although it is well established that light can directly stimulate the hypothalamus, the relative contribution of the eye in the control of reproduction is still controversial. Using a genetically blind line of chickens (Smoky Joe), we investigated the relative importance of the retina of the eye in sexual maturation in roosters. Furthermore, to evaluate the effect of photostimulation, three generations of blind and sighted Smoky Joe roosters were utilize. Generation 1 (G1) was photostimulated at 17 wk of age, while generation 2 (G2) was left un-photostimulated and generation 3 (G3) was photostimulated at 12 wk of age. Blind roosters in G1 and G2 matured between 17 and 19 wk of age (testicular weight, comb length) independently of photostimulati...

Synthesis and characterization of dendritic salicylaldimine complexes of copper and cobalt and their use as catalyst precursors in the aerobic hydroxylation of phenol

A series of generation 1 (G1) and generation 2 (G2) salicylaldimine functionalized polypropylene imine dendrimers were used to prepare a range of new copper and cobalt metallodendrimers. These were found to be efficient catalysts in the aerobic hydroxylation of phenol using H2O2 and molecular oxygen as oxidants. The major products obtained were catechol and hydroquinone. The selectivity to these two products was greatly influenced by the nature of the metallodendrimer as well as by the pH of the reaction medium.

Therapeutic Anti-Methamphetamine Antibody Fragment-Nanoparticle Conjugates: Synthesis and in Vitro Characterization

Treatments specific to the medical problems caused by methamphetamine (METH) abuse are greatly needed. Toward this goal, we are developing new multivalent anti-METH antibody fragment-nanoparticle conjugates with customizable pharmacokinetic properties. We have designed a novel anti-METH single chain antibody fragment with an engineered terminal cysteine (scFv6H4Cys). Generation 3 (G3) polyamidoamine dendrimer nanoparticles were chosen for conjugation due to their monodisperse properties and multiple amine functional groups. ScFv6H4Cys was conjugated to G3 dendrimers via a heterobifunctional PEG cross-linker that is reactive to a free amine on one end and a thiol group on the other. PEG modified dendrimers were synthesized by reacting the PEG cross-linker with dendrimers in a stoichiometric ratio of 11:1, which were further reacted with 3-fold molar excess of anti-METH scFv6H4Cys. This reaction resulted in a heterogeneous mix of G3-PEG-scFv6H4Cys conjugates (dendribodies) with three to six scFv6H4Cys conjugated to each dendrimer. The dendribodies were separated from the unreacted PEG modified dendrimers and scFv6H4Cys using affinity chromatography. A detailed in vitro characterization of the PEG modified dendrimers and the dendribodies was performed to determine size, purity, and METH binding function. The dendribodies were found to have affinity for METH identical to that of the unconjugated scFv6H4Cys in saturation binding assays, whereas the PEG modified dendrimers had no affinity for METH. These data suggest that an anti-METH scFv can be successfully conjugated to a PEG modified dendrimer nanoparticle with no adverse effects on METH binding properties. This study is a critical step toward preclinical characterization and development of a novel nanomedicine for the treatment of METH abuse.

Selective breeding and preliminary commercial performance of Penaeus vannamei for resistance to white spot syndrome virus (WSSV)

White spot syndrome virus (WSSV) has caused significant economic losses in shrimp farming industry. In this paper, WSSV was injected into Penaeus vannamei and the survivors were used for breeding of WSSV-resistant broodstock. During year 2002 to 2007, 120 full-sib WSSV-resistant families were established. Experimental WSSV challenging tests showed that the survival rates of generation 2 (G2), G3, G4 and G5 were 5.57±9.83%, 7.78±10.89%, 9.52±8.84% and 13.79±11.52%, respectively. Furthermore, the time-until-death prolonged gradually from G2 to G5. Shrimps with the highest WSSV resistance from G4 families were selected and assayed for commercial performance in outdoor ponds. In commercial outdoor ponds, the survival rate, production and harvest body weight of these shrimps were 25.33%, 82.14% and 34.51% higher than those of unselected shrimps, respectively, and the feed coefficient was 13.86% lower. Thus, the WSSV resistance and commercial performance of these shrimps have been apparently improved.

Dendrimer–Fullerenol Soft-Condensed Nanoassembly

Nanoscale assembly is an area of research that has vast implications for molecular design, sensing, nanofabrication, supramolecular chemistry, catalysis, and environmental remediation. Here we show that poly(amidoamine) (PAMAM) dendrimers of both generations 1 (G1) and 4 (G4) can host 1 fullerenol per 2 dendrimer primary amines as evidenced by isothermal titration calorimetry, dynamic light scattering and spectrofluorometry. Thermodynamically, the interactions were similarly spontaneous between both generations of dendrimers and fullerenols, however, G4 formed stronger complexes with fullerenols resulting from their higher surface charge density and more internal voids, as demonstrated by spectrofluorometry. In addition to hydrogen bonding that existed between the dendrimer primary amines and the fullerenol oxygens, hydrophobic and electrostatic interactions also contributed to complex formation and dynamics. Such hybrid of soft and condensed nanoassembly may have implications for environmental remediation of discharged nanomaterials and entail new applications in drug delivery.

Effect of Size, Surface Charge, and Hydrophobicity of Poly(amidoamine) Dendrimers on Their Skin Penetration

The barrier functions of the stratum corneum and the epidermal layers present a tremendous challenge in achieving effective transdermal delivery of drug molecules. Although a few reports have shown that poly(amidoamine) (PAMAM) dendrimers are effective skin-penetration enhancers, little is known regarding the fundamental mechanisms behind the dendrimer-skin interactions. In this Article, we have performed a systematic study to better elucidate how dendrimers interact with skin layers depending on their size and surface groups. Franz diffusion cells and confocal microscopy were employed to observe dendrimer interactions with full-thickness porcine skin samples. We have found that smaller PAMAM dendrimers (generation 2 (G2)) penetrate the skin layers more efficiently than the larger ones (G4). We have also found that G2 PAMAM dendrimers that are surface-modified by either acetylation or carboxylation exhibit increased skin permeation and likely diffuse through an extracellular pathway. In contrast, amine-terminated dendrimers show enhanced cell internalization and skin retention but reduced skin permeation. In addition, conjugation of oleic acid to G2 dendrimers increases their 1-octanol/PBS partition coefficient, resulting in increased skin absorption and retention. Here we report that size, surface charge, and hydrophobicity directly dictate the permeation route and efficiency of dendrimer translocation across the skin layers, providing a design guideline for engineering PAMAM dendrimers as a potential transdermal delivery vector.

3-D Molecular Mixtures of Catalytically Functionalized [vinylSiO1.5]10/[vinylSiO1.5]12. Photophysical Characterization of Second Generation Derivatives

Fluoride ion catalyzed rearrangement of −[vinylSiO1.5]n– oligomers and polymers in THF (tetrahydrofuran) provides essentially quantitative conversion to mixtures of the three dimensional (3-D) cage compounds [vinylSiO1.5]10 and [vinylSiO1.5]12 with small amounts of the [vinylSiO1.5]14 cage. These mixtures are easily transformed into their respective styrenyl analogs by metathesis with p-R-styrene to give 100% conversion to the Generation 1 (GEN1) compounds [p-R-styrenylSiO1.5]10/12. The R = Br compounds are then easily modified by Heck coupling with p-R-styrene in >90% yields and ≈100% conversion to the Generation 2 (GEN2) compounds [p-R-stilbenevinylSiO1.5]10/12. These studies were designed to map structure–photophysical properties in these 3-D molecules with the goal of finding replacements for C60 and C70 electron acceptor compounds currently in use in most hybrid organic photovoltaics. Photophysical characterization indicates that the GEN2 compounds have average band gaps that are slightly smaller tha...

Abstract 4261: Epigenetic reprogramming affects malignant properties of human liver cancer cells

Abstract Background: A plastic phenotype is a significant hallmark of aggressive tumors and embryonic stem cells (ESC). Cancer plasticity is dynamically regulated both by cell microenvironment and epigenetic machinery therefore playing important roles in transcriptional reprogramming and cell fate stable changes. Objective: We have explored the relationship between epigenetic alterations and local microenvironment in regulation of cancer stem cells (CSCs) using Zebularine (Zeb), a DNA-methyltransferase1 inhibitor, in combination with the modulation of cellular density in culture. Methods: Seven human hepatoma cell lines, including two primary HCC cell lines, were plated at high (HD) and low density (LD) and grown in the presence or absence of Zeb for 3 days. After, cells were propagated in serum-free condition for evaluation of sphere-forming capacity. Primary tumor-spheres were passaged every 10 days to produce generation 1 (G1) trough G5. Spheres at different generations were examined for differences in gene expression and tumorigenic capacity in vivo. The sphere-derived mRNA and microRNA gene expression signatures generated for different passages were integrated with human HCC database and tested for their prognostic value by Kaplan-Meier. Results: Cells grown under LD failed to form spheres when placed in non-adherent growth conditions. Cells cultured at HD displayed a sphere forming potential at G1 but were unable to maintain extended sphere forming capacity regardless of Zeb pre-treatment. In contrast, Zeb-treated LD (LDZ) cells showed unique features in terms of self renewal potential both in vitro and vivo. LDZ-derived spheres were more proliferative as indicated by Ki67 staining whereas HDZ-spheres showed activation of apoptotic pathway and dowregulation of NF-kB protein levels. LDZ also maintained a higher expression of CSC related markers (CD133, CD44, EpCAM) as well as key factors involved in ESC self-renewal and pluripotency (Bmi1 and αSuz12, subunit of distinct polycomb complexes, PRC1 and PRC2). Also, LDZ-derived spheres consistently expressed higher levels of DNMT1 and DNMT3a. In addition, LDZ spheres exhibited epithelial-mesenchymal transition attributes as judged by the upregulation of β-catenin, ZEB1, VIM and SNAL1 markers as compared to HD spheres. Finally, only G1 LDZ-spheres derived cells showed higher in vivo tumorigenicity and could give rise to brain metastasis. Consistently, global transcriptome analysis confirmed that LDZ sphere signature was enriched in oncogenic molecules associated with metastasis, invasion and resistance to apoptosis, including SMAD2, CD133, CD44 and NF-kB and was able to predict the clinical outcome of liver cancer patients. Conclusions: Epigenetic reprogramming of liver cancer cell lines induced by a combined modulation of DNA methylation and cellular microenviroment generates long lasting memory effects changing the CSC malignant capacity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4261. doi:1538-7445.AM2012-4261

Abstract 1954: Synthesis and self-assembly of highly PEGylated dendron-coils: A potential nanocarrier platform

Abstract Dendron-based amphiphilic copolymers possess unique features such as well-defined structure, self-assembling capability, and precise controllability over functionalities and high hydrophilicity. To assess the ability of dendron-based copolymers for use in drug delivery, we have synthesized novel, highly PEGylated dendron-coils (PDC) with controlled hydrophilic-lipophilic ratios (HLs) ranging from 52:48 to 91:9. We then systematically compared their self-assembly properties with those of linear-block copolymer (LBC) counterparts at similar HLs. PDCs were synthesized via a multistep synthetic procedure. A hydroxyl-terminated generation 3 (G3) polyester dendron bearing a focal acetylene moiety was conjugated with poly(α-caprolactone) (PCL) by ‘click’ chemistry followed by PEGylation of the dendron surface with multiple methoxy poly(ethylene glycol) (mPEG) moieties. Four types of both PCL-G3-mPEG PDCs and PCL-mPEG LBCs with different block lengths were prepared and their structures were confirmed using 1H NMR, FT-IR, and GPC. The critical micelle concentration (CMC) of PDCs varied from 6.50 × 10-8 to 3.52 × 10-7 M. The CMC values of the LBCs were up to 2 orders of magnitude higher than those of the PDCs at the same HLs demonstrating superior thermodynamic stability of PDC micelles. TEM images revealed that the PDCs formed spherical micelles with diameters less than 100 nm with narrow size distributions, which was further supported by dynamic light scattering measurements. To understand in molecular detail the differences in self-assembly between PDCs and LBCs we utilized atomistic molecular dynamics (MD) simulations. Individual PDC copolymers were observed to adopt a stable conical shape in water, which is ideal for precise packing into spherical structures. Interestingly, the core was more completely covered by PEG in PDC micelles. The higher PEG surface coverage of PDC micelles may result in longer circulation half-lives due to decreased opsonization and enhanced accumulation at the therapeutic target site. Each micelle formulation was found to exhibit controlled release properties over 3 days using indomethacin as a model drug. PDCs exhibited no apparent toxicity up to concentrations as high as 100 μM evaluated by MTS assay. The low CMC of the PDCs at high HLs, controlled micelle morphologies, controlled release properties, and high PEG surface coverage all indicates their superiority over LBC counterparts. We expect PDCs to play a sizeable role in the future of targeted nanomedicine. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1954. doi:1538-7445.AM2012-1954

Characterization of magnetic nanoparticles modified with thiol functionalized PAMAM dendron for DNA recovery

Magnetic nanoparticles (MNPs) modified with the thiol functionalized polyamidoamine (PAMAM) dendron were synthesized to estimate their DNA recovery capabilities. Aminosilane-modified MNPs and MNPs surrounded by a phospholipid (distearoylphosphatidylethanolamine (DSPE)) bilayer were used as core particles. Cystamine-core PAMAM dendrimers were reduced by dithiothreitol to dendron thiols and chemically conjugated to the core particles. Characterization of the synthesis revealed an increase of the surface amine charge from generation 1 (G1) to G6, starting with an aminosilane initiator. Particle size distribution analysis indicated that G6 PAMAM-modified MNPs exhibited monodispersity in an aqueous solution. G6 PAMAM–MNPs and G6 PAMAM–PE–MNPs synthesized by the proposed method have equivalent DNA recovery abilities to PAMAM–MNPs prepared by the conventional divergent synthesis method. In optimized conditions, 96% of λDNA was recovered using G6 PAMAM–PE–MNPs. Therefore, the method for preparing PAMAM–MNPs and PAMAM–PE–MNPs proposed in this study will be a novel approach for producing DNA carriers for efficient DNA purification by magnetic separation.

Structure of DNA-functionalized dendrimer nanoparticles

Atomistic molecular dynamics simulations have been carried out to reveal the characteristic features of ethylenediamine (EDA) cored protonated (corresponding to neutral pH) poly amido amine (PAMAM) dendrimers of generation 3 (G3) and 4 (G4) that are functionalized with single strand DNAs (ssDNAs). The four ssDNA strands that are attached via an alkythiolate [–S(CH2)6–] linker molecule to the free amine groups on the surface of the PAMAM dendrimers are observed to undergo a rapid conformational change during the 25 ns long simulation period. From the RMSD values of ssDNAs, we find relative stability in the case of purine rich (having more adenine and guanine) ssDNA strands than pyrimidine rich (thymine and cytosine) ssDNA strands. The degree of wrapping of ssDNA strands on the dendrimer molecule was found to be influenced by the charge ratio of DNA and the dendrimer. As the G4 dendrimer contains relatively more positive charge than G3 dendrimer, we observe extensive wrapping of ssDNAs on the G4 dendrimer than G3 dendrimer. This might indicate that DNA functionalized G3 dendrimer is more suitable to construct higher order nanostructures. The linker molecule was also found to undergo drastic conformational change during the simulation. During nanosecond long simulation some portion of the linker molecule was found to be lying nearly flat on the surface of the dendrimer molecule. The ssDNA strands along with the linkers are seen to penetrate the surface of the dendrimer molecule and approach closer to the center of the dendrimer indicating the soft sphere nature of the dendrimer molecule. The effective radius of DNA-functionalized dendrimer nanoparticles was found to be independent of base composition of ssDNAs and was observed to be around 19.5 Å and 22.4 Å when we used G3 and G4 PAMAM dendrimers as the core of the nanoparticle respectively. The observed effective radius of DNA-functionalized dendrimer molecules apparently indicates the significant shrinkage in the structure that has taken place in dendrimer, linker and DNA strands. As a whole our results describe the characteristic features of DNA-functionalized dendrimer nanoparticles and can be used as strong inputs to design effectively the DNA–dendrimer nanoparticle self-assembly for their active biological applications.

Cost analysis in choosing group size when group testing for Potato virus Y in the presence of classification errors

In many areas of the world, Potato virus Y (PVY) is one of the most economically important disease problems in seed potatoes. In Taiwan, generation 2 (G2) class certified seed potatoes are required by law to be free of detectable levels of PVY. To meet this standard, it is necessary to perform accurate tests at a reasonable cost. We used a two-stage testing design involving group testing which was performed in Taiwan's Seed Improvement and Propagation Station to identify plants infected with PVY. At the first stage of this two-stage testing design, plants are tested in groups. The second stage involves no retesting for negative test groups and exhaustive testing of all constituent individual samples from positive test groups. In order to minimise costs while meeting government standards, it is imperative to estimate optimal group size. However, because of limited test accuracy, classification errors for diagnostic tests are inevitable; to get a more accurate estimate, it is necessary to adjust for these errors. Therefore, this paper describes an analysis of diagnostic test data in which specimens are grouped for batched testing to offset costs. The optimal batch size is determined by various cost parameters as well as test sensitivity, specificity and disease prevalence. Here, the Bayesian method is employed to deal with uncertainty in these parameters. Moreover, we developed a computer program to determine optimal group size for PVY tests such that the expected cost is minimised even when using imperfect diagnostic tests of pooled samples. Results from this research show that, compared with error free testing, when the presence of diagnostic testing errors is taken into account, the optimal group size becomes smaller. Higher diagnostic testing costs, lower costs of false negatives or smaller prevalence can all lead to a larger optimal group size. Regarding the effects of sensitivity and specificity, optimal group size increases as sensitivity increases; however, specificity has little effect on determining optimal group size. From our simulated study, it is apparent that the Bayesian method can truly update the prior information to more closely approximate the intrinsic characteristics of the parameters of interest. We believe that the results of this study will be useful in the implementation of seed potato certification programmes, particularly those which require zero tolerance for quarantine diseases in certified tubers.

Radiolabeling of PAMAM dendrimers conjugated to a pyridine-N-oxide DOTA analog with 111In: Optimization of reaction conditions and biodistribution

Polyamidoamine dendrimers (PAMAMs) of generations 1 (G1) and 4 (G4) were conjugated with a bifunctional pyridine-N-oxide DOTA analog, 10-[(4-carboxy-1-oxidopyridin-2-yl)methyl]-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H4do3a-pyNO−C), through the pyridine-4-carboxylic acid group, and the conjugates were radiolabeled with indium-111. Reaction conditions for the radiolabelling were optimized. Both radiolabeled conjugates, G1-[111In(do3a-pyNO−C)] and G4-[111In(do3a-pyNO−C)], were kinetically stable for at least 48h after preparation; in the presence of competitive ligands, the radiochemical purity of the conjugates slightly decreased (4–7%) over the same time period. The preclinical pharmacokinetics of both agents were evaluated. Biodistribution and elimination in rats were more favorable for the G1-[111In(do3a-pyNO−C)] conjugate than G4-[111In(do3a-pyNO−C)] conjugate. However, the G1-[111In(do3a-pyNO−C)] conjugate was rapidly eliminated from the body, mainly through urine, while, significant and long-term radioactivity uptake in the liver and kidney was observed for the G4-[111In(do3a-pyNO−C)] conjugate.

Sustaining Fidelity Following the Nationwide PMTO™ Implementation in Norway

This report describes three studies from the nationwide Norwegian implementation of Parent Management Training-Oregon Model (PMTO™), an empirically supported treatment for families of children with behavior problems (Forgatch and Patterson 2010). Separate stages of the implementation were evaluated using a fidelity measure based on direct observation of intervention sessions. Study 1 assessed growth in fidelity observed early, mid, and late in the training of a group of practitioners. We hypothesized increased fidelity and decreased variability in practice. Study 2 evaluated method fidelity over the course of three generations of practitioners trained in PMTO. Generation 1 (G1) was trained by the PMTO developer/purveyors; Generation 2 (G2) was trained by selected G1 Norwegian trainers; and Generation 3 (G3) was trained by G1 and G2 trainers. We hypothesized decrease in fidelity with each generation. Study 3 tested the predictive validity of fidelity in a cross-cultural replication, hypothesizing that higher fidelity scores would correlate with improved parenting practices observed in parent-child interactions before and after treatment. In Study 1, trainees' performance improved and became more homogeneous as predicted. In Study 2, a small decline in fidelity followed the transfer from the purveyor trainers to Norwegian trainers in G2, but G3 scores were equivalent to those attained by G1. Thus, the hypothesis was not fully supported. Finally, the FIMP validity model replicated; PMTO fidelity significantly contributed to improvements in parenting practices from pre- to post-treatment. The data indicate that PMTO was transferred successfully to Norwegian implementation with sustained fidelity and cross-cultural generalization.

Polyvalent saccharide-functionalized generation 3 poly(amidoamine) dendrimer–methotrexate conjugate as a potential anticancer agent

A saccharide-terminated generation 3 (G3) polyamidoamine (PAMAM) dendrimer was synthesized as a drug carrier. Utilizing this dendritic platform, we have successfully synthesized polyvalent conjugates (G3-MTX) containing the drug methotrexate (MTX). Surface Plasmon Resonance (SPR) results showed that G3-MTX presented three orders of magnitude enhancement in binding avidity to folate-binding protein (FBP) as compared to the free folic acid (FA). Flow cytometric and confocal microscopic analysis showed that conjugate (G3-MTX-FI) containing imaging agent fluorescein-5(6)-carboxamidohexanoic acid (FI) was internalized into folate receptor (FR)-expressing KB cells in dose-dependent and receptor-mediated fashion. The G3-MTX induced a dose-dependent cytotoxicity in the KB cells. Therefore, the polyvalent G3-MTX may have potential as an anticancer nanodevice for the specific targeting and killing of FR-expressing tumor cells.

Poly(amidoamine) Dendrimers Increase Antifungal Activity of Clotrimazole

Clotrimazole (CLO) is a local imidazolic antifungal agent. A major problem associated with the successful formulation of effective dosage forms containing CLO is its poor aqueous solubility, which presents a hindrance for the local availability of CLO and limits the effective antifungal therapy. In the present study, the effects of various concentrations of poly(amidoamine) (PAMAM) dendrimers generation 2 (G2) and generation 3 (G3) with amine (PAMAM-NH(2)) or hydroxyl surface groups (PAMAM-OH) on aqueous solubility and antifungal activity of CLO were studied. The obtained results showed that all tested PAMAM dendrimers improved the solubility of CLO and the more potent were PAMAM-NH(2) dendrimers. The increase in solubility of CLO was highest at dendrimer concentration of 10 mg/ml. Microbiology studies indicated that only PAMAM-NH(2) dendrimers significantly increased the antifungal activity of CLO (a 4-32-fold increase in the antifungal activity compared to pure CLO) and the most potent was dendrimer PAMAM-NH(2) G2. These observations indicate that PAMAM dendrimers might be considered as potential carriers of CLO and provide further impetus to evaluate these polymers for use in basic drug delivery studies and to design semisolid dosage forms based on dendrimers with antimicrobial drugs, like CLO.

Performance of Sweetpotato Foundation Seed after Incorporation into Commercial Operations in Louisiana

Because sweetpotato (Ipomoea batatas) is vegetatively propagated, viruses and mutations can accumulate readily, which can lead to cultivar decline. Sweetpotato foundation seed programs in the United States maintain the integrity of commercial seed stock by providing virus-tested (VT) foundation seed to commercial producers. A survey was conducted in Louisiana from 2007 to 2009 to examine the performance and quality of the foundation seed after it had been integrated into commercial sweetpotato operations. G1 seed [grown 1 year after virus therapy in the foundation seed production field at the Sweet Potato Research Station, Louisiana State University Agricultural Center (LSU AgCenter), at Chase, LA] was used as a reference to compare the yield and virus incidence of growers' generation 2 (G2) and generation 3 (G3) seed roots (grown in the growers' seed production fields 1 or 2 years following the year of foundation seed production). Although yields of plants grown from G2 and G3 seed were 86.3% and 86.1% for U.S. No. 1 and 83.3% and 86.0% for total marketable, respectively, compared with the yields from G1 seed, they were not significantly different. Yield and virus incidence data suggest that seed quality may vary from year to year and from location to location. Results from this study suggest that producers are realizing yield benefits by incorporating VT foundation seed into their production schemes, but further benefits could be attained if ways to reduce re-infection with viruses can be found.

Performance of Sweetpotato Foundation Seed after Incorporation into Commercial Operations in Louisiana

Because sweetpotato (Ipomoea batatas) is vegetatively propagated, viruses and mutations can accumulate readily, which can lead to cultivar decline. Sweetpotato foundation seed programs in the United States maintain the integrity of commercial seed stock by providing virus-tested (VT) foundation seed to commercial producers. A survey was conducted in Louisiana from 2007 to 2009 to examine the performance and quality of the foundation seed after it had been integrated into commercial sweetpotato operations. G1 seed [grown 1 year after virus therapy in the foundation seed production field at the Sweet Potato Research Station, Louisiana State University Agricultural Center (LSU AgCenter), at Chase, LA] was used as a reference to compare the yield and virus incidence of growers' generation 2 (G2) and generation 3 (G3) seed roots (grown in the growers' seed production fields 1 or 2 years following the year of foundation seed production). Although yields of plants grown from G2 and G3 seed were 86.3% and 86.1% for U.S. No. 1 and 83.3% and 86.0% for total marketable, respectively, compared with the yields from G1 seed, they were not significantly different. Yield and virus incidence data suggest that seed quality may vary from year to year and from location to location. Results from this study suggest that producers are realizing yield benefits by incorporating VT foundation seed into their production schemes, but further benefits could be attained if ways to reduce re-infection with viruses can be found.

Complexation of siRNA with Dendrimer: A Molecular Modeling Approach

This paper reports the structural behavior and thermodynamics of the complexation of siRNA with poly(amidoamine) (PAMAM) dendrimers of generation 3 (G3) and 4 (G4) through fully atomistic molecular dynamics (MD) simulations accompanied by free energy calculations and inherent structure determination. We have also done simulation with one siRNA and two dendrimers (2×G3 or 2×G4) to get the microscopic picture of various binding modes. Our simulation results reveal the formation of stable siRNA−dendrimer complex over nanosecond time scale. With the increase in dendrimer generation, the charge ratio increases and hence the binding energy between siRNA and dendrimer also increases in accordance with available experimental measurements. Calculated radial distribution functions of amines groups of various subgenerations in a given generation of dendrimer and phosphate in backbone of siRNA reveals that one dendrimer of generation 4 shows better binding with siRNA almost wrapping the dendrimer when compared to the...