Herpes simplex virus 1 alpha regulatory protein ICP0 interacts with and stabilizes the cell cycle regulator cyclin D3.

The herpes simplex virus 1 (HSV-1) infected-cell protein 0 (ICP0) has the characteristics of a promiscuous transactivator of genes introduced into cells by infection or transfection. To identify cellular proteins interacting with ICP0, we used a domain of exon II of ICP0 that is known to be crucial for regulatory function of the protein as bait in the yeast two-hybrid screen. Our results were as follows. (i) A cDNA in a positive yeast colony was found to encode cyclin D3, a cell cycle regulator of G1 phase. (ii) A purified chimeric protein consisting of glutathione S-transferase (GST) fused to cyclin D3 specifically formed complexes with ICP0 contained in HSV-1-infected cell lysate. (iii) To enhance the expression of cyclin D3, the gene was inserted into the viral genome and overexpressed in infected cells. The overexpressed cyclin D3 colocalized with ICP0 in nuclear structures characteristic of ND10 and which earlier have been reported to contain ICP0. (iv) The accumulation of cyclin D3 protein in Vero cells infected with an alpha0 deletion mutant was reduced relative to that of cells infected with wild-type virus or a recombinant virus in which the deleted alpha0 sequences were restored. (v) Lysates of Spodoptera frugiperda Sf9 cells doubly infected with baculoviruses genetically engineered to express cyclin D3 and cyclin-dependent kinase 4 (CDK4) phosphorylated GST fused to retinoblastoma protein (GST-pRb) but did not phosphorylate the GST-alpha0(20-241) or GST-alpha0(543-768) fusion protein or immunoprecipitated ICP0 proteins. Moreover, the chimeric GST-ICP0(exon II) protein shown to bind cyclin D3 had no effect on the activity of the kinase on GST-pRb when added to mixtures of lysates of Sf9 cells which coexpressed cyclin D3 and CDK4. These results indicate that ICP0 interacts with, colocalizes with, and stabilizes the cyclin D3 cell cycle regulator and does not affect its interaction with the cyclin-dependent kinase.     

Chilling-sensitive mutants of arabidopsis

Twenty-one mutants ofArabidopsis thaliana were isolated that developed chlorosis or necrosis upon incubation at low temperature (10°C to 15°C). Crosses among mutants in different phenotypic classes showed that mutants in three of four classes were found in a small number of loci. This article is reproduced fromWeeds World, vol. 1. For electronic access toWeeds World, see PMBR 12(4):302–303.     

Skin ultrastructure in relation to prolactin and MSH function in rainbow trout (Oncorhynchus mykiss) exposed to environmental acidification

The present study describes the effects of 14 days exposure to acidified (pH 4.0) soft water in the absence of aluminium, on the ultrastructure of the skin in rainbow trout (Oncorhynchus mykiss). Compared to control fish, there was a moderate increase in the incidence of necrosis in the filament cells of the fish exposed to pH 4.0, but since the integrity of the tissue appeared to be maintained, most of the ultrastructural changes observed may be considered to be adaptive. There was an increase in epidermal thickness, a higher frequency of electrondense vesicles in filament cells, an increase in the undulation of the basal lamina, and the penetration of the epidermis by cytoplasmatic processes of melanocytes in acid-exposed specimens. An infiltration of leucocytes into the epidermis, and the appearance of serous mucous cells, was also evident. Whether these events were under the control of prolactin and/or -MSH, was also investigated, but no indication for activation or inhibition of either prolactin or -MSH producing cells was obtained. Since a previous study (Balm and Pottinger 1993) had demonstrated that plasma cortisol levels were also identical in control and low pH treated trout throughout a 14 day experimental period, it is concluded that under conditions of environmental acidification, the integument autonomically maintains the adjustments necessary for successful acclimation, presumably via paracrine regulatory circuits.     

Genetic and molecular analysis of the tRNA-tufB operon of the myxobacterium Stigmatella aurantiaca.

The tufB gene, encoding elongation factor Tu (EF-Tu), from the myxobacterium Stigmatella aurantiaca was cloned and sequenced. It is preceded by four tRNA genes, the first ever described in myxobacteria. The tRNA synthesized from these genes and the general organization of the locus seem identical to that of Escherichia coli, but differences of potential importance were found in the tRNA sequences and in the intergenic regions. The primary structure of EF-Tu was deduced from the tufB DNA sequence. The factor is composed of 396 amino acids, with a predicted molecular mass of 43.4 kDa, which was confirmed by expression of tufB in maxicells. Sequence comparisons between S.aurantiaca EF-Tu and other bacterial homologues from E.coli, Salmonella typhimurium and Thermus thermophilus displayed extensive homologies (75.9%). Among the variable positions, two Cys residues probably involved in the temperature sensitivity of E.coli and S.typhimurium EF-Tu are replaced in T.thermophilus and S.aurantiaca EF-Tu. Since two or even three tuf genes have been described in other bacterial species, the presence of multiple tuf genes was sought for. Southern and Northern analysis are consistent with two tuf genes in the genome of S.aurantiaca. Primer extension experiments indicate that the four tRNA genes and tufB are organized in a single operon.     

Molecular mapping of wheat. Homoeologous group 2.

A molecular-marker map of bread wheat having many markers in common with other grasses in the Gramineae family is a prerequisite for molecular level genetic studies and breeding in this crop species. We have constructed restriction fragment length polymorphism maps of the A-, B-, and D-genome chromosomes of homoeologous group 2 of hexaploid wheat (Triticum aestivum L. em. Thell) using 114 F7 lines from a synthetic x bread wheat cross and clones from 11 libraries. Chromosomes 2A, 2B, and 2D comprise 57, 60, and 56 markers and each spans about 200 cM. Comparisons between chromosomes are facilitated by 26 sets of homoeoloci. Genes mapped include a heterologous abscisic acid responsive locus cloned as pBS128, the epidermal waxiness inhibitor W21, and two presumed leaf rust and stem rust resistance genes. Anomalies suggesting ancestral rearrangements in chromosome 2B are pointed out and features of wheat group 2 chromosomes that are common to barley (Hordeum vulgare L.), rice (Oryza spp.), and T. tauschii are discussed.     

Uptake by central nervous tissues as a mechanism for the regulation of extracellular adenosine concentrations

The various facets of the uptake of adenosine by central nervous tissues are described. The uptake process includes the transport of nucleoside across neuronal and glial plasma membranes and its metabolism within the cell. Much of the transported adenosine is phosphorylated into adenosine nucleotides. Inhibitors of adenosine uptake increase extracellular levels of adenosine and can thus potentiate its pharmacological actions. This may be an important component in the actions of various groups of psychoactive drugs.