Inhibition of Membrane-Active Peptides by Fatty Acid–Peptide Hybrids

Nine fatty acid–peptide hybrid molecules were constructed using the general formula CH₃(CH₂) _n CO-Phe Asp Cys-amide and tested for their ability to inhibit cell lysis induced by the membrane-active peptide melittin. All of these molecules, where n = 4–14, inhibited the action of melittin to some extent, but the longer carbon chains were most effective. Several potential inhibitors were also constructed with conservative substitutions in the peptide portion of the molecule. All were effective to varying degrees. We concluded that in the hexapeptide inhibitor published by Blondelle et al. (1993), the role of the first three residues is only to provide hydrophobic interaction with the melittin and has no particular amino acid sequence specificity. Some of these inhibitors were found to inhibit the lytic activity of a melittin analogue which had only superficial sequence similarity to melittin and also a truncated form of melittin, indicating the generality of the action of the inhibitors.Deceased 5/4/98     

Measuring ecological impact of water consumption by bioethanol using life cycle impact assessment

Purpose  

Though the development of biofuel has attracted numerous studies for quantifying potential water demand applying life cycle thinking, the impacts of biofuel water consumption still remain unknown. In this study, we aimed to quantify ecological impact associated with corn-based bioethanol water consumption in Minnesota in responding to different refinery expansion scenarios by applying a life cycle impact assessment method.     

The effects of androgens on the β-glands of the tokay (Gekko gecko): Modification of an hypothesis

Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β-gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot-pad, shows a pattern of histogenesis directly comparable to that of β-glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis.     

Regulation of G(1) cell-cycle progression by oncogenes and tumor suppressor genes.

Progression of resting quiescent G(0) cells into early G(1) and transition across the restriction point are highly regulated processes. Mutation of proto-oncogenes and tumor suppressor genes regulating these transitions are targeted during oncogenesis. Recent work has underscored the importance of the G(0) to early G(1) transition and metabolism to neoplastic cells.     

Sampling for Explosives-Residues at Fort Greely,Alaska

Fort Greely, Alaska has an extensive complex of weapon training and testing areas located on lands withdrawn from the public domain under the Military Lands Withdrawal Act (PL106-65). The Army has pledged to implement a program to identify possible munitions contamination. Because of the large size (344,165,000 m²) of the high hazard impact areas, characterization of these constituents will be difficult. We used an authoritative sampling design to find locations most likely to contain explosives-residues on three impact areas. We focused our sampling on surface soils and collected multi-increment and discrete samples at locations of known firing events and from areas on the range that had craters, pieces of munitions, targets, or a designation as a firing point. In the two impact areas used primarily by the Army, RDX was the most frequently detected explosive. In the impact area that was also used by the Air Force, TNT was the most frequently detected explosive. Where detected, the explosives concentrations generally were low (<0.05 mg/kg) except in soils near low-order detonations, where the explosive-filler was in contact with the soil surface. These low-order detonations potentially can serve as localized sources for groundwater contamination if positioned in recharge areas.     

Using Haplotype Trees for Phylogeographic and Species Inference in Fish Populations

Genetic variation is now routinely screened at the DNA sequence level in many studies. If the DNA region being screened has not experienced excessive amounts of recombination, it is often possible to reconstruct the evolutionary history of the genetic variation in the form of a haplotype tree. This tree estimates the evolutionary pathway that interconnects all the different haplotypes (sequence variants) observed in the sample. This haplotype tree can be used to define a series of nested branches (clades) that reflects the relative temporal history of the haplotypes and groups of haplotypes. Geographical information can then be overlaid upon this temporal series to test for significant associations between geography and temporal position in the haplotype tree. This allows a reconstruction of how the genetic variation arose and spread in both space and time. Such reconstructions can yield many insights into the joint roles of recurrent events such as gene flow and of historical events such as fragmentation or range expansion. These points are illustrated with studies on the chub, Leuciscus cephalus. There is also a need to extend such nested phylogeographic analyses to a phylo/reticulate geographic analysis that incorporates both assortment and recombination between and within DNA regions. A preliminary phylo/reticulate geographic analysis is presented of the transferrin locus in the brown trout, Salmo trutta, species complex that reveals the importance of hybridization in the recent evolutionary history of this group. This example shows the inadequacy of a strictly phylogenetic approach and illustrates the need to incorporate reticulate evolution. The results of nested clade phylogeographic analysis and the new phylo/reticulate geographic analysis are then used for inferring species status of the marbled trout. The results indicate that an old hybridization event may have played a role in the origin of the marbled trout. Currently the marbled trout is primarily endangered by hybridization with introduced brown trout. These results show both the positive and negative impacts of hybridization upon biodiversity. Such phylo/reticulate geographic studies will challenge both our concepts of species and our conservation management strategies.