Bioethanol and biodiesel: Alternative liquid fuels for future generations

The global population is expected to increase by approximately 3 billion people by 2050. With this increase in population, industry, transportation the cost of fossil fuels will grow dramatically. New technologies are needed for fuel extraction using feedstocks that do not threaten food security, cause minimal or no loss of natural habitat and soil carbon. At the same time, waste management has to be improved and environmental pollution should be minimized or eliminated. Liquid biofuels such as lignocellulosic‐based ethanol from plant biomass and algal‐based biodiesel are sustainable, alternative biofuels that could stabilize national security and provide clean energy for future generations. Ideally, the technology should also foster recycling of agricultural feedstocks and improve soil fertility and human health. This article provides updated information on the energy potential and breadth of liquid biofuel biotechnology.     

Prolidase contamination in commercial bovine serum albumin

Bovine serum albumin from a number of commercial sources were screened for the presence or absence of peptidase contamination. Peptidase activity was monitored using various peptides as substrates. Two commercial preparations were found to have peptidase activity, and the enzyme was identified, on the basis of its substrate specificity, as prolidase (EC 3.4.14.9). The contaminating activity was in the order of 3–4 units/g albumin.     

Peptide transport across the animal cell plasma membrane: recent developments.

Transfer of intact peptides across the plasma membrane of animal cells, especially in the small intestine and the kidney, is a well established phenomenon. This process plays an important role in the maintenance of protein nutrition. Evidence is accumulating which suggests that the process may also have a great potential for pharmacological and clinical applications. It is therefore important to understand various aspects of peptide transport such as its function, chemical nature of the transport protein and its gene, the operational mechanisms and their regulation, and the relevance of the transport system to health and disease. Recent years have witnessed considerable progress in the field. The driving force for the transport system has been identified as the proton motive force which makes the system unique and distinct from the majority of solute transport systems in animal cells which are driven by a sodium motive force. A great deal is now known on the chemical nature of the active site. The protein responsible for the transport process in the small intestine has been purified and characterized. The system has been successfully expressed in its functional form in Xenopus laevis oocytes by microinjection into the oocytes of poly(A)+ mRNA isolated from intestinal mucosal cells. There is no doubt that the coming years will bring even more exciting information on the transport system, especially in areas such as hormonal regulation, clinical applicability and cloning, and characterization of the gene encoding the transport system.     

Site frequency spectra from genomic SNP surveys

Genomic survey data now permit an unprecedented level of sensitivity in the detection of departures from canonical evolutionary models, including expansions in population size and selective sweeps. Here, we examine the effects of seemingly subtle differences among sampling distributions on goodness of fit analyses of site frequency spectra constructed from single nucleotide polymorphisms. Conditioning on the observation of exactly two alleles in a random sample results in a site frequency spectrum that is independent of the scaled rate of neutral substitution (θ). Other sampling distributions, including conditioning on a single mutational event in the sample genealogy or randomly selecting a single mutation from a genealogy with multiple mutations, have distinct site frequency spectra that show highly significant departures from the predictions of the biallelic model. Some aspects of data filtering may contribute to significant departures of site frequency spectra from expectation, apart from any violation of the standard neutral model.