The effect of coupled cardiovascular and respiratory afferent signals on the central processes of human information processing

On the basis of contemporary knowledge on close functional connections between respiratory and cardiovascular afferents a computerized experimental device was developed by means of which central information processing can be studied in dependence on respiration phase and the level of baroreceptor activity. In all the examined parameters (time of motor reaction of two hands, latency of eye-lid reflex) the greatest changes were observed at maximum baroreceptor activity. These changes were clearly distinguished by direction during the phases of inhalation and exhalation. Such effect is probably based on the fact that the influence of cardiovascular afferents on the level of central activity is modulated in respiration rhythm through the mechanism of breath "gating" of postsynaptic STN structures.     

Decidual cells in the human ovary at term: II. Morphometric analysis of cytoplasmic processes and organelles

Morphometric analysis of human ovarian decidual cells was performed with a Videoplan computer, and mean values were established for the area and perimeter of cellular processes and organelles. Two-hundred forty electron micrographs representing 160 cells were analyzed. The mean decidual cell area was 218.7 microns2, of which 34.5 microns2 was occupied by the nucleus (15.8% of the cytoplasmic area); the nucleus contained 1.74 micron2 of nucleolar material (0.8%). The endoplasmic reticulum occupied 13.63 microns2 (6.2%). Mitochondria occupied 7.3 microns2 (3.3%) and the Golgi network 5.49 microns2 (2.5%). Decidual secretory bodies occupied 0.91 micron2 (0.42%) and cytoplasmic processes 1.89 micron2 (0.94%). The remainder of the cytoplasm, containing inclusions and cytoskeleton, represented 71% of the cell area. Perimeter measurements indicated an average decidual cell was surrounded by 87.8 microns of plasma membrane. The mean nuclear membrane measured 28.3 microns (representing 32.3% of the plasma membrane, pm, or 4.1% of total cellular membranes, cm). Outer mitochondrial membranes measured 156.6 microns (178% pm, 23.5% cm); endoplasmic reticulum membranes measured 350.3 microns (400% pm, 52.6% cm); Golgi membrane measured 30.77 microns (35% pm; 4.5% cm) and membrane surrounding secretory bodies measured 9.8 microns (11.2% pm; 1.4% cm). A mean of 280 secretory bodies per ovarian decidual cell was calculated. The plasma membranes of evaginated cytoplasmic processes represented 22.3% of the total pm (19.6 microns or 2.9% cm). A mean of seven such processes was observed per 87.8 microns of plasma membrane (160/cell). These morphometric data provide a baseline for comparisons of human ovarian decidual cells with uterine decidua, in vivo and in vitro, as well as with decidual cells of other species.     

Mechanism of ribosomal subunit association: discrimination of specific sites in 16 S RNA essential for association activity.

Modification of 30 S ribosomal subunits with kethoxal causes loss of their ability to associate with 50 S subunits under tight couple conditions. To identify those 16 S RNA sequences important for the association. ³²P-labeled 30 S subunits were partially inactivated by reaction with kethoxal. The remaining association-competent 30 S subunits were selected from the modified population by their ability to form 70 S ribosomes. Comparison of kethoxal diagonal maps of the association-competent subunits with those of the total population of modified subunits reveals nine sites in 16 S RNA whose modification leads to loss of association activity. Eight of these sites were previously found to be protected from kethoxal attack and one was shown to have enhanced reactivity in 70 S ribosomes (Chapman &; Noller, 1977). As before, these sites are not distributed thoughout the molecule, but are found to be clustered in two regions, at the middle and at the 3′ terminus of the 16 S RNA chain.We interpret these findings in terms of a simple preliminary model for the functional organization of 16 S RNA, supported by the observations of other investigators, in which we divide the molecule into four domains. (1) Residues 1 to 600 are involved mainly in structural organization and assembly. (2) Residues 600 to 850 include sites which make contact with the 50 S subunit and are essential for subunit association. (3) Sites from the domain comprising residues 850 to 1350 line a pocket at the interface between the two ribosomal subunits. and contribute to the binding site(s) for transfer RNA. (4) Residues 1350 to 1541 also contain sequences which bind the 50 S subunit, but some sites in this domain alternatively participate in the initiation of protein synthesis.     

Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

DNA polymerases (Pols) ε and δ perform the bulk of yeast leading- and lagging-strand DNA synthesis. Both Pols possess intrinsic proofreading exonucleases that edit errors during polymerization. Rare errors that elude proofreading are extended into duplex DNA and excised by the mismatch repair (MMR) system. Strains that lack Pol proofreading or MMR exhibit a 10- to 100-fold increase in spontaneous mutation rate (mutator phenotype), and inactivation of both Pol δ proofreading (pol3-01) and MMR is lethal due to replication error-induced extinction (EEX). It is unclear whether a similar synthetic lethal relationship exists between defects in Pol ε proofreading (pol2-4) and MMR. Using a plasmid-shuffling strategy in haploid Saccharomyces cerevisiae, we observed synthetic lethality of pol2-4 with alleles that completely abrogate MMR (msh2Δ, mlh1Δ, msh3Δ msh6Δ, or pms1Δ mlh3Δ) but not with partial MMR loss (msh3Δ, msh6Δ, pms1Δ, or mlh3Δ), indicating that high levels of unrepaired Pol ε errors drive extinction. However, variants that escape this error-induced extinction (eex mutants) frequently emerged. Five percent of pol2-4 msh2Δ eex mutants encoded second-site changes in Pol ε that reduced the pol2-4 mutator phenotype between 3- and 23-fold. The remaining eex alleles were extragenic to pol2-4. The locations of antimutator amino-acid changes in Pol ε and their effects on mutation spectra suggest multiple mechanisms of mutator suppression. Our data indicate that unrepaired leading- and lagging-strand polymerase errors drive extinction within a few cell divisions and suggest that there are polymerase-specific pathways of mutator suppression. The prevalence of suppressors extragenic to the Pol ε gene suggests that factors in addition to proofreading and MMR influence leading-strand DNA replication fidelity.     

Human impact on the ecological performance of Potamogeton species in northwestern Germany

The changes in habitat quality of lowland rivers in Lower Saxony (Germany) during the past 40 years are outlined. Almost all chemical, physical, and morphological parameters have changed, resulting in most cases in an enhanced potential productivity, accompanied by a complex disturbance regime. Historical reconstruction of the change in river vegetation is presented to compare the frequency of macrophyte species 40 years ago with the situation of today. For a total of 289 sampling sites, the floristic change was exactly reconstructed. Nearly all species show a decline in frequency. This trend is also recognizable in Potamogeton, with the exception of two narrow-leaved species.An attempt is made to explain both decline and maintenance in terms of life history characters (vital attributes) allowing the species to react to the changing habitat conditions. The successful species are characterized by certain life history characteristics which enable them to survive under the current disturbance regime. Most important aspects of life history are the ability to reproduce by means of turions and other fragments, a long-lived, deep-rooting rhizome system, phenotypic plasticity of above-ground parts, synchronous shoot polymorphism, and the potential to regenerate quickly from remaining buds after disturbance. The decline of formerly frequent species can be attributed mainly to the lack of certain key characters; however, physiological characters also may be important. The extirpation of some rare species could also be caused by random fluctuations in small populations. The general importance of population ecological research, particularly demography, life history theory, and the modelling of clonal populations in conservation ecology is stressed.     

RecX Facilitates Homologous Recombination by Modulating RecA Activities

The Bacillus subtilis recH342 strain, which decreases interspecies recombination without significantly affecting the frequency of transformation with homogamic DNA, carried a point mutation in the putative recX (yfhG) gene, and the mutation was renamed as recX342. We show that RecX (264 residues long), which shares partial identity with the Proteobacterial RecX (<180 residues), is a genuine recombination protein, and its primary function is to modulate the SOS response and to facilitate RecA-mediated recombinational repair and genetic recombination. RecX-YFP formed discrete foci on the nucleoid, which were coincident in time with RecF, in response to DNA damage, and on the poles and/or the nucleoid upon stochastic induction of programmed natural competence. When DNA was damaged, the RecX foci co-localized with RecA threads that persisted for a longer time in the recX context. The absence of RecX severely impaired natural transformation both with plasmid and chromosomal DNA. We show that RecX suppresses the negative effect exerted by RecA during plasmid transformation, prevents RecA mis-sensing of single-stranded DNA tracts, and modulates DNA strand exchange. RecX, by modulating the “length or packing” of a RecA filament, facilitates the initiation of recombination and increases recombination across species.     

Low-dose adenovirus vaccine encoding chimeric hepatitis B virus surface antigen-human papillomavirus type 16 E7 proteins induces enhanced E7-specific antibody and cytotoxic T-cell responses

Induction of effective immune responses may help prevent cancer progression. Tumor-specific antigens, such as those of human papillomaviruses involved in cervical cancer, are targets with limited intrinsic immunogenicity. Here we show that immunization with low doses (10(6) infectious units/dose) of a recombinant human adenovirus type 5 encoding a fusion of the E7 oncoprotein of human papillomavirus type 16 to the carboxyl terminus of the surface antigen of hepatitis B virus (HBsAg) induces remarkable E7-specific humoral and cellular immune responses. The HBsAg/E7 fusion protein assembled efficiently into virus-like particles, which stimulated antibody responses against both carrier and foreign antigens, and evoked antigen-specific kill of an indicator cell population in vivo. Antibody and T-cell responses were significantly higher than those induced by a control adenovirus vector expressing wild-type E7. Such responses were not affected by preexisting immunity against either HBsAg or adenovirus. These data demonstrate that the presence of E7 on HBsAg particles does not interfere with particle secretion, as it occurs with bigger proteins fused to the C terminus of HBsAg, and results in enhancement of CD8(+)-mediated T-cell responses to E7. Thus, fusion to HBsAg is a convenient strategy for developing cervical cancer therapeutic vaccines, since it enhances the immunogenicity of E7 while turning it into an innocuous secreted fusion protein.     

Evaluation of the new advanced 15-loci MIRU-VNTR genotyping tool in <Emphasis Type=Italic>Mycobacterium tuberculosis</Emphasis> molecular epidemiology studies

Background  

During the last few years, PCR-based methods have been developed to simplify and reduce the time required for genotyping Mycobacterium tuberculosis (MTB) by standard approaches based on IS6110-Restriction Fragment Length Polymorphism (RFLP). Of these, MIRU-12-VNTR (Mycobacterial interspersed repetitive units- variable number of tandem repeats) (MIRU-12) has been considered a good alternative. Nevertheless, some limitations and discrepancies with RFLP, which are minimized if the technique is complemented with spoligotyping, have been found. Recently, a new version of MIRU-VNTR targeting 15 loci (MIRU-15) has been proposed to improve the MIRU-12 format.     

Free and integrated recombinant murine leukemia virus DNAs appear in preleukemic thymuses of AKR/J mice.

We studied the appearance and structure of murine leukemia viral genomes in preleukemic AKR/J mice by Southern hybridization. Up to an average of one to two copies per thymocyte of unintegrated murine leukemia virus DNA appears in the thymuses of preleukemic mice beginning at 4 to 5 months of age and disappears in leukemic thymuses. The free viral genomes are absent in the spleens, livers, and brains of preleukemic mice. Using a series of ecotropic and nonecotropic murine leukemia virus hybridization probes, we showed that the unintegrated viral genomes are structurally analogous to those of recombinant mink cell focus-forming viruses that appear as proviruses in leukemic AKR thymocytes, suggesting that these free viral DNAs are the direct precursors to the leukemia-specific proviruses. The mosaic of ecotropic and nonecotropic sequences within these unintegrated viral DNAs varies from one preleukemic thymus to another but often appears structurally homogeneous within individual thymuses, indicating that often each thymus was being infected by a unique mink cell focus-forming virus. Analysis of high-molecular-weight DNA shows that recombinant proviruses reside in the chromosomal DNA of thymocytes within the preleukemic thymus, with the number rising to an average of several copies per thymocyte, but we do not detect any preferred integration sites. These results suggest that, in general, before the development of thymic leukemias in AKR mice there is a massive infection by a unique mink cell focus-forming virus which then integrates into many different sites of individual thymocytes, one of which grows out to become a tumor.