The 26 amino acid hemolytic melittin peptide was converted into a gene transfer peptide that binds to DNA and polymerized through disulfide bond formation. Melittin analogues were synthesized by the addition of one to four Lys repeats at either the C- or the N-subterminal end along with terminal Cys residues. Melittin analogues were able to bind and polymerize on plasmids resulting in the formation of DNA condensates. In the absence of DNA, melittin analogues retained their red blood cell hemolytic potency but were inactive when bound to plasmid DNA. The in vitro gene transfer efficiency mediated by poly-melittin analogues was equivalent to PEI in HepG2 cells. Attempts to truncate portions of either of the two melittin alpha-helices resulted in concurrent loss of hemolytic potency and gene transfer efficiency. The results demonstrate the ability to transform melittin into a gene transfer peptide by transiently masking its membrane lytic activity by the addition of Lys and Cys residues to promote DNA binding and polymerization.

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IRS-1 overexpression has been associated with breast cancer development, hormone independence and antiestrogen resistance. IRS-1 is a major downstream signaling protein for insulin and IGF1 receptors, conveying signals to PI-3K/Akt and ERK1/2 pathways. In estrogen-sensitive breast cancer cell lines, the widely used antiestrogen tamoxifen treatment reduces IRS-1 expression and function, thereby inhibiting IRS-1/PI-3K signaling. IRS-1 may serve as an alternative target to overexpressed IGF1R in breast cancer. While siRNA technology has become commonplace in many laboratories for in vitro gene knockdown studies, and in vivo stability issues are largely solved, its use in vivo is limited by an inability to efficiently and specifically deliver it to the intended site of action. We previously reported reduced survival of human MCF7 estrogen receptor positive breast cancer cells treated with a normal IRS1 siRNA delivered by a cationic lipid, plus an additive effect in combination with tamoxifen. We now report enhanced cellular uptake, relative to the unconjugated serum-stabilized IRS1 siRNA, of a serum-stabilized IRS1 siRNA conjugated with our previously characterized peptide mimetic of IGF1, D-(Cys-Ser-Lys-Cys), without the use of cationic lipids or electroporation, in MCF7 cells that overexpress IGF1R. Excess native IGF1 blocked uptake. An IRS1 siRNA cholesterol conjugate, targeted universally to cell membranes, was taken up by MCF7 cells as much as the peptide mimetic conjugate. IRS1 mRNA knockdown and IRS-1 protein knockdown were comparable for the IGF1 peptide and cholesterol conjugates. The unconjugated serum-stabilized IRS1 siRNA control showed negligible effects. Viability assays showed additive effects of siRNA treatment in combination with tamoxifen. In summary, we have taken the first step in converting an siRNA into a pharmacologically active agent for breast cancer.

Monthly abundance (CPUE) of larval anchovy in the coastal waters off south‐western Taiwan from 1980 to 1992 (156 months) fluctuated at intervals corresponding to the 4.3‐ and 2.2‐year cycles of the southern oscillation index (SOI). Also, CPUE was significantly correlated with sea surface temperature with a time lag of 3 months and nearly significantly to river flow with a time lag of 4 months, which in turn correlated with SOI at lags of 13–14 months (cross‐correlation and transfer function analyses). The results suggested the presence of linkage between recruitment of the larvae and ENSO episodes, perhaps through oceanographic and meteorological conditions that affect coastal upwelling and river discharge. The Kuroshio Current, which is the western extension of the North Equatorial Current, may be one of the important mechanisms of ENSO's teleconnections affecting local climate and fisheries in the western Pacific region.

Genetic disorders can arise from single base substitutions in a single gene. A single base substitution for wild type guanine in the twelfth codon of KRAS2 mRNA occurs frequently to initiate lung, pancreatic, and colon cancer. We have observed single base mismatch specificity in radioimaging of mutant KRAS2 mRNA in tumors in mice by in vivo hybridization with radiolabeled peptide nucleic acid (PNA) dodecamers. We hypothesized that multi-mutant specificity could be achieved with a PNA dodecamer incorporating hypoxanthine, which can form Watson-Crick basepairs with adenine, cytosine, thymine, and uracil. Using molecular dynamics simulations and free energy calculations, we show that hypoxanthine substitutions in PNAs are tolerated in KRAS2 RNA-PNA duplexes where wild type guanine is replaced by mutant uracil or adenine in RNA. To validate our predictions, we synthesized PNA dodecamers with hypoxanthine, and then measured the thermal stability of RNA-PNA duplexes. Circular dichroism thermal melting results showed that hypoxanthine-containing PNAs are more stable in duplexes where hypoxanthine-adenine and hypoxanthine-uracil base pairs are formed than single mismatch duplexes or duplexes containing hypoxanthine-guanine opposition.

Ac lass of artificial K + channels formed by pillararene-cyclodextrin hybrid molecules have been designed and synthesized.T hese channels efficiently inserted into lipid bilayers and displayed high selectivity for K + over Na + in fluorescence and electrophysiological experiments.The cation transport selectivity of the artificial channels is tunable by varying the length of the linkers between pillararene and cyclodexrin. The shortest channel showed specific transmembrane transport preference for K + over all alkali metal ions (selective sequence:K + > Cs + > Rb + > Na + > Li + ), and is rarely observed for artificial K + channels.T he high selectivity of this artificial channel for K + over Na + ensures specific transmembrane translocation of K + ,a nd generated stable membrane potential across lipid bilayers.

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