This paper describes the first thermoelectric devices based on the V-VI-compounds Bi/sub 2/Te/sub 3/ and (Bi,Sb)/sub 2/Te/sub 3/ which can be manufactured by means of regular thin film technology in combination with microsystem technology. Fabrication concept, material deposition for some 10-/spl mu/m-thick layers and the properties of the deposited thermoelectric materials will be reported. First device properties for Peltier-coolers and thermogenerators will be shown as well as investigations on long term and cycling stability. Data on metal/semiconductor contact resistance were extracted form device data. Device characteristics like response time for a Peltier-cooler and power output for a thermogenerator will be compared to commercial devices

The trimeric main light-harvesting complex (LHC-II) is the only antenna complex of higher plants of which a high-resolution 3D structure has been obtained (Kühlbrandt, W., Wang, D., and Fujiyoshi, Y. (1994) Nature 367, 614-621) and which can be refolded in vitro from its components. Four different recombinant forms of LHC-II, each with a specific chlorophyll (Chl) binding site removed by site-directed mutagenesis, were refolded from heterologously overexpressed apoprotein, purified pigments, and lipid. Absorption spectra of mutant LHC-II were measured in the temperature range from 4 to 300 K and compared to likewise refolded wild-type complex and to native LHC-II isolated from pea chloroplasts. Chls at different binding sites have characteristic, well-defined absorption sub-bands. Mixed occupation of binding sites with Chls a and b is not observed. Temperature-dependent changes of the mutant absorption spectra reveal a consistent shift of the major difference bands but an irregular behavior of minor bands. A model of the spectral substructure of LHC-II is proposed which accounts for the different absorption properties of the 12 individual Chls in the complex, thus establishing a first consistent correlation between the 3D structure of LHC-II and its spectral properties. The spectral substructure is valid for recombinant and native LHC-II, indicating that both have the same spatial arrangement of Chls and that the refolded complex is fully functional.

Summary Group B Streptococcus (GBS) is a frequent cause of bacterial sepsis and meningitis in neonates. During the course of infection, GBS colonizes and invades

Group B streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis in neonates. N-terminal sequencing of major proteins in the culture supernatant of a clinical isolate of GBS identified a protein of about 50 kDa which could be detected in all of 27 clinical isolates tested. The corresponding gene, designated pcsB, was isolated from a GBS cosmid library and subsequently sequenced. The deduced PcsB polypeptide consists of 447 amino acid residues (M r , 46,754), carries a potential N-terminal signal peptide sequence of 25 amino acids, and shows significant similarity to open reading frames of unknown function from different organisms and to the murein hydrolase P45 from Listeria monocytogenes. Northern blot analysis revealed a monocistronic transcriptional organization for pcsB in GBS. Insertional inactivation of pcsB in the genome of GBS resulted in mutant strain Sep1 exhibiting a drastically reduced growth rate compared to the parental GBS strain and showing an increased susceptibility to osmotic pressure and to various antibiotics. Electron microscopic analysis of GBS mutant Sep1 revealed growth in clumps, cell separation in several planes, and multiple division septa within single cells. These data suggest a pivotal role of PcsB for cell division and antibiotic tolerance of GBS.Group B streptococcus (GBS), also known as Streptococcus agalactiae, is part of the normal human flora colonizing the respiratory, gastrointestinal, and urogenital tracts. It is also the leading cause of bacterial sepsis and meningitis in neonates in the United States and western Europe, and it is a major cause of endocarditis and fever in parturient women (2). In the last decade, the incidence of GBS infections has increased especially in the elderly and in immunocompromised persons (58), but despite its clinical importance, GBS is only poorly understood on the molecular level.Bacterial cell division is a complex interplay of topological processes, biosynthetic reactions, and cleavage mechanisms. Septum formation is initiated by the cooperative action of division inhibitors, topological specificity factors, and proteins constituting the cell division apparatus both found in gramnegative and gram-positive bacteria (reviewed in reference 5, 31, and 42). In globular cells, like streptococci, the division septum can be arranged in several orientations, resulting in the generation of two daughter cells of the same size and shape. The choice of the division plane determines the three-dimensional organization of the multicellular arrays of progeny cells that are formed. In GBS, the plane of division is approximately the same in each division cycle, resulting in the formation of frequently long chains (20). The division septum that is formed between the daughter cells is composed of newly synthesized membrane and peptidoglycan components. Peptidoglycan biosynthesis is accomplished by the insertion of peptide-carrying disaccharide units into the existing murein sacculus by transglycosylation and transpeptidation (34). Cell divi...