Even more new taxa from South and East Anatolia II

10 new Turkish taxa are described:Arenaria eliasiana, A. sivasica, A. monscragus, A. angustifolioides; Campanula lycica; Scutellaria orientalis subsp.tortumensis; Stachys choruhensis, S. tundjeliensis; Calamintha caroli-henricana; Aristolochia rechingeriana, the latter two species named in honour ofKarl Heinz Rechinger;Allium vuralii. Dedicated to Prof. DrKarl Heinz Rechinger on the occasion of his 80th birthday. For part I see Pl. Syst. Evol.154, 111–128.     

Nucleotide sequence of the herpes simplex virus type 2 (HSV-2) thymidine kinase gene and predicted amino acid sequence of thymidine kinase polypeptide and its comparison with the HSV-1 thymidine kinase gene

To analyze the boundaries of the functional coding region of the HSV-2(333) thymidine kinase gene (TK gene), deletion mutants of hybrid plasmid pMAR401 H2G, which contains the 17.5 kbp BglII-G fragment of HSV-2 DNA, were prepared and tested for capacity to transform LM(TK-) cells to the thymidine kinase-positive phenotype. These studies showed that hybrid plasmids containing 2.2-2.4 kbp subfragments of HSV-2 BglII-G DNA transformed LM(TK-) cells to the thymidine kinase-positive phenotype and suggested that the region critical for transformation might be less than 2 kbp. That the activity expressed in the transformants was HSV-2 thymidine kinase was shown by experiments with type-specific enzyme-inhibiting rabbit antisera and by disc-polyacrylamide gel electrophoresis analyses. DNA fragments of the HSV-2 TK gene were subcloned in phage M13mp9 and M13mp8. A sequence of 1656 bp containing the entire coding region of the TK gene and the flanking sequences was determined by the dideoxynucleotide chain termination method. Comparisons with the HSV-1(Cl 101) TK gene revealed that PstI, PvuII, and EcoRI cleavage sites had homologous locations as did promoter, translational start and stop, and polyadenylation signals. Extensive homology was observed in the nucleotide sequence preceding the ATG translational start signal and in portions of the coding region of the genes. Comparisons of the predicted amino acid sequences of the HSV-1 and HSV-2 thymidine kinase polypeptides revealed that both were enriched in alanine, arginine, glycine, leucine, and proline residues and that clear, but interrupted homology existed within several regions of the polypeptide chains. Stretches of 15-30 amino acid residues were identical in conserved regions. The possibility is suggested that domains containing some of the conserved amino acid sequences might have a role in substrate binding and as major antigenic determinants.     

DNA-replication recovery inhibition and subsequent reinitiation in UV-radiation-damaged E. coli: a strategy for survival

Using the incorporation of [14C]thymine to measure DNA accumulation, it was shown that exposure of the B/r strain of Escherichia coli to 10 J/m2 of ultraviolet radiation (UV) inhibits replication for about 20 min, but then resumption of replication occurs. Pulse-labelling with [3H]thymidine after exposure of the WT strain to this fluence confirmed the transient inhibition and recovery of DNA replication. After recovery, the rate of accumulation of DNA in the culture increases, to exceed that of the exponentially growing culture, so that eventually the amount of DNA almost equals that of the unirradiated culture. After a higher fluence (20 J/m2), an inhibition of replication recovery was revealed. This fluence delays the reinitiation of DNA accumulation in the culture, measured by [14C]thymine incorporation, for 25 min more, in addition to the 20-min recovery period. This finding was confirmed with pulse-labelling studies, which revealed that the higher exposure represses the rates of replication for 45 min before replication at the normal rate reinitiates in the culture. It was proposed that the inhibition of recovery revealed by these investigations is effected by the UV-induction of an active DNA-replication recovery-inhibition process. With the uvrA strain, rate studies revealed that 1.5 J/m2 of UV (a reduced fluence necessary because of the greater sensitivity of the strain) induces a transient inhibition of DNA replication, with considerable recovery following. Exposure to 3.0 J/m2 induces the transient inhibition of replication, followed by massive recovery inhibition after 20 min of incubation. With uvrA recA, both the lower and the higher fluence resulted in an immediate block of replication with no recovery, confirming the recA gene dependency of the recovery process. The decrease in rate of replication comparable to that seen in the uvrA strain after 20 min, and taken as evidence of the function of the recovery-inhibition process, was not seen. The evidence supports the concept that a process somehow triggered by higher UV fluences functions to repress replication temporarily, presumably allowing time for repair processes to take place before replication overruns closely linked pyrimidine dimers on opposite strands to create lethal lesions.     

Development of a selective pseudosubstrate-based peptide inhibitor of pp60c-src protein tyrosine kinase

Summary Using a combinatorial peptide library method, we identified YIYGSFK as an efficient and specific peptide substrate for pp60^c-src protein tyrosine kinase (PTK) [Lam et al., Int. J. Pept. Protein Res., 45 (1995) 587]. Employing YIYGSFK as a template, we synthesized and evaluated a series of pseudosubstrate-based inhibitors for pp60^c-src. We found that the efficiency of a given inhibitor was highly dependent on the specific tyrosine analog used at the phosphorylation site of the substrate. One of these pseudosubstrate inhibitors, YI(2-Nal)GSFK, selectively inhibited the kinase activity of pp60^c-src, with a K_i of 24 M. This peptide inhibitor exhibited selectivity for pp60^c-src as compared to other PTKs tested, such as c-Abl and Bcr-Abl. Our results suggest that selective inhibitors for a specific PTK can be developed when the structure of a specific and efficient small peptide substrate for this PTK can be used as a template for structure modification.Abbreviations 1-Nal l-1-naphthylalanine - 2-Nal l-2-naphthylalanine - BOP benzotriazolyl-N-oxy-tris(dimethylamino)-phosphonium hexafluorophosphate - BSA bovine serum albumin - cAPK cyclic AMP-dependent protein kinase - DIEA diisopropylethylamine - EGFR epidermal growth factor receptor - Fmoc fluorenylmethoxycarbonyl - HOBt 1-hydroxybenzotriazole - MES 2-[N-morpholino]ethanesulfonic acid - PBS phosphate-buffered salts - pCl l-p-chlorophenylalanine - pF l-p-fluorophenylalanine - PTK protein tyrosine kinase - TLC thin-layer chromatography     

OBSERVATIONS ON A CHAMAESIPHONACEOIS ALGA (CYANOPHYCEAE) WITH SPECIAL REFERENCE TO EXOCYTE FORMATION1,2

A unicellular cyanophycean culture contaminant had features of both Geitleribactron Kom. and Cyanophanon Geitl. The cells were elongated, sheathless, mostly similar in diameter throughout their length, and attached polarly in rosettes or groups and produced only a single elongated exocyte (=exospore). Young cells were moderately elongated and resembled Geitleribactron. As cells aged, they greatly elongated and then resembled Cyanophanon. Some cells formed Y-shaped bifurcations, features of C. mirabile Geitl. and C. minus Geitl., but they lacked the basal sheath (pseudovagina) of C. mirabile. During exocyte formation, a thick and localized L-II wall layer protuberance extended the exocyte away from the parent cell. This terminal wall thickening then appeared to move to one side from subsequent and unequal cell wall growth. Cells sovnetimes bent abruptly, occasionally opposite a thickening in the L-II wall layer. Further studies in culture of putative Geitleribactron and Cyanophanon isolates are necessary to ascertain the breadth of their structural diversity and the identity of the present taxon.     

Adenovirus core protein synthesis in the absence of viral DNA synthesis late in infection.

The acid extraction of the adenovirus type 5 core proteins V, VII, and pVII (the precursor to VII) from infected cells and the subsequent electrophoresis on a 15% acrylamide-2.5 M urea-0.9 N acetic acid (pH 2.7) gel, revealed that peptide VII has a similar electrophoretic mobility to that of histone H1. The core proteins, which are coded by late adenovirus mRNA, continued to be synthesized late in infection when viral DNA synthesis was inhibited either by cytosine arabinoside in wild-type infections or by shifting adenovirus H5 ts 125-infected cells to the nonpermissive temperature (40 degree C). Only the initiation, not the continuation, of viral DNA replication was essential for core protein synthesis. The synthesis of viral core proteins continued for over 8 h after the cassation of DNA synthesis. This was in contrast to the rapid shutdown of cellular histone synthesis in the absence of cellular DNA synthesis.