BioEssays

doi: 10.1002/bies.950040101pmid: N/A

Miller, Henry I.

doi: 10.1002/bies.950040102pmid: N/A

Kridl, Jean C.; Goodman, Robert M.

doi: 10.1002/bies.950040103pmid: N/A

Two groups of plant viruses have DNA in their genomes. One group, the caulimoviruses, are non‐integrating retroviruses that package dsDNA in virions. The other group, the geminiviruses, package small circular ssDNA and include the only DNA viruses known with bipartite genomes. The regulation of transcription of these viruses is not well characterized, but recent work is beginning to yield interesting results. Regulatory sequences from these viruses function in cells of species that are not hosts of the virus and are finding use in constitutive expression of chimeric genes in transformed plants. Development of vectors based on plant viruses requires further characterization at the molecular level of viral life cycles.

Cooper, Jonathan A.

doi: 10.1002/bies.950040104pmid: 3539110

Oncogenes are altered forms of normal cellular genes known as proto‐oncogenes. Several oncogenes encode enzymes that phosphorylate substrate proteins at tyrosine. In most of these cases the oncogene differs from its proto‐oncogene by multiple mutations that alter the structure of the encoded protein product. Here we discuss how structural changes might effect the regulation and substrate specificity of the protein kinase product of a protooncogene so that it gains the potential to transform cells.

Iversen, P. L.; Hines, R. N.; Bresnick, Edward

doi: 10.1002/bies.950040105pmid: 3790107

The heme‐containing cytochromes P‐450 are a ubiquitous family of monooxygenase isozymes responsible for the oxidative metabolism of a wide variety of endogenous as well as exogenous compounds. Many of the compounds metabolized by this enzyme system are effectively detoxified and converted to derivatives more easily eliminated from the organism. However, some compounds can be activated to reactive species capable of eliciting a cascade of toxic lesions, including cancer. Since its discovery nearly 30 years ago, the cytochrome P‐450 enzyme system has received a great deal of attention, particularly in the areas of their mechanisms of metabolism, range of substrate specificity, the purification and characterization of the multiple isozymes and, more recently, the regulation of expression of specific forms. This review will discuss current notions concerning the expression of at least one cytochrome P‐450 isozyme and future directions that should lead to a more complete understanding of cytochrome P‐450 gene expression in general, particularly as it impacts upon biochemical pharmacology.

Fujiwara, Hiromi; Hamaoka, Toshiyuki

doi: 10.1002/bies.950040106pmid: 3491605

This article reviews recent findings that bear on the mechanism(s) of tumor‐specific Lyt‐1+2− T cell‐mediated tumor eradication in vivo A tumor‐immune Lyt‐1+2− T cell subset has been identified which is distinct from T cells mediating in vitro cytotoxicity (Lyt‐1+2+/1−2+). The Lyt‐1+2− cells have a crucial role in rejecting tumor cells when adoptively transferred into T cell‐deprived B cell mice. This indicates that Lyt‐1+2− T cells do not necessarily require recruitment of the host's cytotoxic T cell precursors for implementation of in vivo immunity. Instead, this T cell subset exerts its anti‐tumor effect in collaboration with macrophages as shown with an in vivo tumor cell culture system utilizing a diffusion chamber. A pathway of Lyt‐1+2− T cell‐macrophage interaction leading to tumor cell killing is discussed in terms of its probable relevance to the eradication of tumor cell masses consisting of tumor cells expressing quantitatively and/or qualitatively different tumor antigens.

Gibson, Kenneth M.; Nyhan, William L.; Jaeken, Jaak

doi: 10.1002/bies.950040107pmid: 3790108

Defects in man in four steps of 4‐aminobutyric acid (GABA) metabolism may interefere with the function of this major inhibitory neurotransmitter. Glutamic acid decarboxylase, 4‐aminobutyric acid aminotransferase, succinic semialdehyde dehydrogenase, and homocarnosinase are closely identified with the brain, but two of these enzymes are expressed in cultured peripheral cells, which may permit novel approaches to the study of the metabolism and regulation of GABA.

Dashek, W. V.; Mayfield, J. E.; Llewellyn, G. C.; O'Rear, C. E.; Bata, A.

doi: 10.1002/bies.950040108pmid: 3790109

‘Yellow Rain’, an alleged biological warfare agent thought to be utilized in parts of both South East Asia and Afghanistan, may be composed in part of the mycotoxins, trichothecenes. However, more recent analyses suggest that the ‘Rain’ was mainly honey bee excreta. The history of the controversy together with the biological effects, chemistry as well as the fungi producing these mycotoxins and agricultural commodities affected by trichothecenes are reviewed.

Fantes, Peter

doi: 10.1002/bies.950040109pmid: 3790110

Mommaerts, W. F. H. M.

doi: 10.1002/bies.950040110pmid: 3491606

Evidence is reviewed here that inositol (1, 4, 5) trisphosphate (Ins P3) is a key signal in translating the electrophysiological event in muscle stimulation into the molecular‐mechanical events of contraction. Not least, these findings raise questions about the suitability of the term ‘second messenger’.