Cloning and characterization of theNeisseria gonorrhoeae MS11folC gene

The gene coding for folylpoly-(γ)-glutamate synthetase (FPGS)-dihydrofolate synthetase (DHFS) ofNeisseria gonorrhoeae (Ngo) has been cloned by functional complementation of anEscherichia coli folC mutant (SF4). The sequence encodes a 224-residue protein of 46.4 kDa. It shows 46% identity to theE. coli FPGS-DHFS and 29% identity to the PFGS ofLactobacillus casei. Sequence comparisons between the three genes reveal regions of high homology, including ATP binding sites required for bifunctionality, all of which may be important for FPGS activity. In contrast toL. casei FPGS, theE. coli andNgo enzymes share some additional regions which may be essential for DHFS activity. The products ofNgo folC and flanking genes were monitored by T7 promoter expression. Interestingly, deletion of the upstreamfolI gene, which encodes a 16.5 kDa protein, abolishes the capacity offolC to complementE. coli SF4 to the wild-type phenotype. The ability to complement can be restored byfolI providedin trans. UnlikefolC mutants, gonococcalfolI mutants are viable and display no apparent phenotype. Thus, in contrast toE. coli, Ngo folC is expressed at a sufficiently high level from its own promoter, in the absence of FolI. This study provides the first insights into the genetic complexity of one-carbon metabolism inNgo.     

A novel approach to the analysis of the initiation of embryo development in gramineae

An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.     

Carbonized food plants of Pompeii,Herculaneum, and the Villa at Torre Annunziata

The remains of carbonized plants recovered from sites destroyed by Mount Vesuvius in A.D. 79 furnish valuable historical evidence on many staple food plants used by the ancient Campanians of the 1st century A.D. Carbonized seeds,grains, nuts, and fruits of 24 species identified from documented materials at Pompeii, Herculaneum, and the Roman villa at Torre Annunziata include: filbert, Corylus avellana;broadbean, Vicia fabavar. minor;bittervetch. Vicia ervilia;chickpea, Cicer arietinum;carob, Ceratonia siliqua;lentil, Lens culinaris;European chestnut, Castanea sativa;English or Persian walnut, Juglans regia;common onion, Allium cepa;garlic, Allium sativum;fig, Ficus carica;olive, Olea europaea;date, Phoenix dactylifera;stone pine, Pinus pinea;six-rowed barley, Hordeum vulgare;emmer wheat, Triticum dicoccon;common millet, Panicum miliaceum;Italian millet, Setaria italica;oat, Avena sativa;almond, Prunus dulcis;sour cherry, Prunus cerasus;pear, Pyrus communis;crabapple, Malussp.;and grape, Vitis vinifera.     

Fluid transport in a thick layer above an active ciliated surface.

The discrete cilia approach is employed to describe the flow field above an active ciliated surface in a layer of finite depth. The infinite-size cilia surface model predicts a uniform flow above the cilia surface. Modifications as a result of a finitely extending cilia surface inside a finite-size dish predict a backward parabolic profile above an active cilia surface. Experiments are described which demonstrate a good fit between theoretical predictions and observations. The results provide a sound physical basis for the proper interpretation of fluid-flow observations close to an active ciliary field.     

Dielectric behavior of linear polyelectrolytes

The dipolar correlation function for a system of counterions diffusing on the surface of a polyelectrolyte cylinder is computed. Repulsive coulombic interactions between the counterions are taken into account. Lateral dissociation and reassociation to the cylinder is treated microscopically. Numerical calculations needed to obtain quantitative results for the long time behavior are presented. The model dependence on its parameters is interpreted with special emphasis on parameter values typical of DNA.