Genetic polymorphism of natural Epstein-Barr virus isolates from infectious mononucleosis patients and healthy carriers.

We analyzed Epstein-Barr virus (EBV) genomes from lymphoblastoid cell lines isolated from patients with infectious mononucleosis and from healthy subjects from California, Hawaii, and Hong Kong between 1970 and 1987. Using genetic polymorphism as epidemiological markers, we found that several genotypes of EBV cocirculate in a community and that although most EBV strains isolated from California and Southern China may be differentiated genotypically, there was no specific association between genotype and disease or time of isolation.     

Digest: The evolution of sexual imprinting as an assortative mating mechanism*

In this issue, Yeh et al. (2018) investigated whether sexual imprinting could act as an assortative mating mechanism, reducing hybridization and increasing premating isolation. While they indeed find that imprinting leads to assortative mating and reduced hybridization, the strength at which imprinting evolves is usually intermediate, because it is counterbalanced by the costs of imprinting and the benefits of adaptive hybridization. Thus, while sexual imprinting can act as an assortative mating mechanism, it is often not the sole element of female mate choice.     

Does Wood Fuel Gathering for Household Use Follow an Optimality Model? A Study from Kakamega Forest,Western Kenya

Successful management of forests, especially in the context of subsistence wood fuel use, can be improved by the application of theoretic models that predict patterns of use. A first step in this approach is understanding the decision rules of people using forests. While optimal foraging theory is normally applied to foraging for food, it also makes sense to apply it in the context of “foraging” for wood fuel. In this study, we applied a time allocation model of optimal foraging theory to wood gathering decisions in communities around Kakamega Forest, a mid-altitude seasonal tropical rain forest. The model predicts that the amount of wood gathered should increase with the distance to the wood source. We found that the predictions of OFT are supported, but only for adults and more strongly on a weekly scale. Based upon the results, we then discuss future improvements of the model to better understand and predict human use.     

DNA sequencing and expression of the formyl coenzyme A transferase gene, frc, from Oxalobacter formigenes.

Oxalic acid, a highly toxic by-product of metabolism, is catabolized by a limited number of bacterial species utilizing an activation-decarboxylation reaction which yields formate and CO2. frc, the gene encoding formyl coenzyme A transferase, an enzyme which transfers a coenzyme A moiety to activate oxalic acid, was cloned from the bacterium Oxalobacter formigenes. DNA sequencing revealed a single open reading frame of 1,284 bp capable of encoding a 428-amino-acid protein. A presumed promoter region and a rho-independent termination sequence suggest that this gene is part of a monocistronic operon. A PCR fragment containing the open reading frame, when overexpressed in Escherichia coli, produced a product exhibiting enzymatic activity similar to the purified native enzyme. With this, the two genes necessary for bacterial catabolism of oxalate, frc and oxc, have now been cloned, sequenced, and expressed.     

Arabidopsis acyl-CoA-binding protein ACBP6 localizes in the phloem and affects jasmonate composition

Arabidopsis thaliana ACYL-COA-BINDING PROTEIN6 (AtACBP6) encodes a cytosolic 10-kDa AtACBP. It confers freezing tolerance in transgenic Arabidopsis, possibly by its interaction with lipids as indicated by the binding of acyl-CoA esters and phosphatidylcholine to recombinant AtACBP6. Herein, transgenic Arabidopsis transformed with an AtACBP6 promoter-driven β-glucuronidase (GUS) construct exhibited strong GUS activity in the vascular tissues. Immunoelectron microscopy using anti-AtACBP6 antibodies showed AtACBP6 localization in the phloem especially in the companion cells and sieve elements. Also, the presence of gold grains in the plasmodesmata indicated its potential role in systemic trafficking. The AtACBP6 protein, but not its mRNA, was found in phloem exudate of wild-type Arabidopsis. Fatty acid profiling using gas chromatography-mass spectrometry revealed an increase in the jasmonic acid (JA) precursor, 12-oxo-cis,cis-10,15-phytodienoic acid (cis-OPDA), and a reduction in JA and/or its derivatives in acbp6 phloem exudates in comparison to the wild type. Quantitative real-time PCR showed down-regulation of COMATOSE (CTS) in acbp6 rosettes suggesting that AtACBP6 affects CTS function. AtACBP6 appeared to affect the content of JA and/or its derivatives in the sieve tubes, which is consistent with its role in pathogen-defense and in its wound-inducibility of AtACBP6pro::GUS. Taken together, our results suggest the involvement of AtACBP6 in JA-biosynthesis in Arabidopsis phloem tissues.     

Nucleotide sequence of the 3' end of MCF 247 murine leukemia virus

We isolated DNA clones of MCF 247, a leukemogenic, recombinant type C virus obtained from the thymus of an AKR mouse. We determined the nucleotide sequence of the viral long terminal repeat (LTR) and the 3' end of env, and we compared the sequences to corresponding sequences of the genome of Akv virus, the putative ecotropic parent of MCF 247. By analogy with Moloney leukemia virus, we identified the amino terminus of Prp15E, the C-terminal proteolytic cleavage product of env and precursor to mature virion p15E. In MCF 247 the presumptive Prp15E is encoded by a 603-nucleotide open reading frame. The majority of this sequence is identical to that of Akv. However, a recombination event near the 3' end of the Prp15E-coding region introduces nonecotropic sequences into MCF 247, and these extend to the 3' end through the U3 portion of the LTR. The U3 regions of Akv and MCF 247 are about 83% homologous. The R and U5 regions of the LTR of MCF 247 and Akv are identical. Large RNase T1-resistant oligonucleotides analyzed previously in numerous ecotropic and MCF viral genomes were located within the Akv and MCF 247 DNA sequences. The resulting precise T1 oligonucleotide maps of the 3' ends of MCF viral genomes reveal that the biologically defined, leukemogenic class I MCFs isolated from thymic neoplasms of inbred mice all share the sequence pattern seen in MCF 247, a representative of this group; they possess recombinant Prp15E genes and derive U3 from their nonecotropic parents.     

Flow cytoenzymology of intracellular tartrate-resistant acid phosphatase.

Tartrate-resistant acid phosphatase (TRACP) is a cytochemical marker for hairy cell leukemia, macrophages, dendritic cells, and osteoclasts. Our purpose was to develop multicolor cytofluorometric methods to evaluate intracellular TRACP enzymic activity using a fluorogenic cytochemical reaction in combination with immunochemical stains for distinct surface membrane antigens. Monocyte-derived dendritic cells (DCs) were the model TRACP-expressing cells studied. Intracellular TRACP activity was disclosed using naphthol-ASBI phosphate as substrate with fast red-violet LB salt as coupler for the reaction product. Before the TRACP enzymic reaction, surface antigens, CD86 and CD11c of DCs, were bound with specific fluorescent antibodies to test compatibility of surface labeling and intracellular staining. TRACP activity varied in DCs from donor to donor but was reproducible on repeated examinations of each sample. Samples could be stained for simultaneous analysis of surface antigens and intracellular TRACP activity, provided certain technical details were observed. The TRACP reaction time should not exceed 9 min and the cell number should not exceed 2 x 10(5)/100 micro l test. Fluorescent surface labels did not affect the intensity of the TRACP stain, but the intensity of some surface labels may be diminished by elution of low-affinity antibodies during the TRACP reaction. Readjustment of the threshold settings in triple-labeled cells is needed to compensate for this phenomenon. Intracellular TRACP activity can be quantitated in subpopulations of cells within mixed cell populations by flow cytofluorometry using simple cytochemical methods in combination with fluorescent antibodies to cell-surface and other differentiation antigens. The cytochemical method should be useful for basic investigations of differentiation, maturation, and function of macrophages, DCs, and osteoclasts, and for diagnosis and management of hairy cell leukemia.