A note on the prebiotic synthesis of organic acids in carbonaceous meteorities

Strong similarities between monocarboxylic and hydroxycarboxylic acids in the Murchison meteorite suggest corresponding similarities in their origins. However, various lines of evidence apparently implicate quite different precursor compounds in the synthesis of the different acids. These seeming inconsistencies can be resolved by postulating that the apparent precursors also share a related origin. Pervasive D enrichment indicates that this origin was in a presolar molecular cloud. The organic acids themselves were probably synthesised in an aqueous environment on an asteroidal parent body, the hydroxy (and amino) acids by means of the Strecker cyanohydrin reaction.     

Intragenic duplication and divergence in the spectrin superfamily of proteins

Many structural, signaling, and adhesion molecules contain tandemly repeated amino acid motifs. The alpha-actinin/spectrin/dystrophin superfamily of F-actin-crosslinking proteins contains an array of triple alpha-helical motifs (spectrin repeats). We present here the complete sequence of the novel beta-spectrin isoform beta(Heavy)- spectrin (beta H). The sequence of beta H supports the origin of alpha- and beta-spectrins from a common ancestor, and we present a novel model for the origin of the spectrins from a homodimeric actin-crosslinking precursor. The pattern of similarity between the spectrin repeat units indicates that they have evolved by a series of nested, nonuniform duplications. Furthermore, the spectrins and dystrophins clearly have common ancestry, yet the repeat unit is of a different length in each family. Together, these observations suggest a dynamic period of increase in repeat number accompanied by homogenization within each array by concerted evolution. However, today, there is greater similarity of homologous repeats between species than there is across repeats within species, suggesting that concerted evolution ceased some time before the arthropod/vertebrate split. We propose a two-phase model for the evolution of the spectrin repeat arrays in which an initial phase of concerted evolution is subsequently retarded as each new protein becomes constrained to a specific length and the repeats diverge at the DNA level. This evolutionary model has general applicability to the origins of the many other proteins that have tandemly repeated motifs.      

Biocatalytic oxidation of S-alkylcysteine derivatives by chloroperoxidase and Beauveria species

Treatment of N-methoxycarbonyl C-carboxylate ester derivatives of S-methyl- -cysteine by chloroperoxidase (CPO)/hydrogen peroxide resulted in oxidation at sulfur to produce the (R_S) sulfoxide in moderate to high diastereomeric excess (DE). The (S_S) natural product sulfoxide chondrine was obtained via biotransformation of the N-t.boc derivative of -4-S-morpholine-2-carboxylic acid using Beauveria bassiana or Beauveria caledonica.     

Effects of recombinant adenovirus-mediated expression of IL-2 and IL-12 in human B lymphoma cells on co-cultured PBMC

Background  

Modulation of the immune system by genetically modified lymphoma cell vaccines is of potential therapeutic value in the treatment of B cell lymphoma. However, the anti-tumor effect of any single immunogene transfer has so far been limited. Combination treatment of recombinant IL-2 and IL-12 has been reported to be synergistic for inducing anti-tumor responses in solid tumors but the potential of IL-2/IL-12 gene modified B cell lymphoma cells has not been explored yet.     

Appendage morphogenesis in Drosophila: a developmental study of the rotund (rn) gene

Summary The phenotype of rotund (rn) null alleles is described, and compared to wild type. The mutants are expressed zygotically and cause position specific defects in certain imaginal discs (antenna, legs, wing, haltere and proboscis) and their corresponding adult derivatives. In the discs, specific folds are absent in rn mutants compared to wild type. Clonal analysis shows that the rn ⁺ gene is partially autonomous in its expression in cells destined to form certain distal parts of the adult appendages. The results are consistent with the idea that the rn ⁺ gene is required for normal morphogenesis of specific distal parts of the adult appendages.     

Understanding Selective Refusal of Eye Donation

Corneal transplantation is the most common form of organ transplantation performed globally. However, of all organs, eyes have the highest rate of refusal of donation. This study explored the reasons why individuals decide whether or not to donate corneas. Twenty-one individuals were interviewed who had made a donation decision (13 refused corneal donation and eight consented). Analysis was performed using Grounded Theory. Refusal of corneal donation was related to concerns about disfigurement and the role of eyes in memory and communication. The request for donation therefore raised concerns about a potential adverse change in the ongoing relationship with the deceased, even in death. For those who refused donation, these concerns overshadowed awareness of need or benefit of transplantation. Adjusting the donation message to be more congruent with the real, lived experience of corneal donation may to some extent “prepare” individuals when the donation question is raised.