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Results indicate that carbon dioxide reduces the expression of capsular polysaccharide type 5 at the transcriptional level in Staphylococcus aureus. Regulation of capsular polysaccharide type 8 expression is strain dependent, suggesting that genetic background determines the carbon dioxide response.

Research findings demonstrate that a Cbbr transcriptional regulator homolog of carbon dioxide concentrating mechanism-related gene, cmpR, plays a role in the induction of cmp operon at low carbon dioxide levels in two cyanobacterial strains.

Research shows that most ndh genes occur as single copies and some of them encode for the type I NAD(P)H dehydrogenase proton-pumping complex. Results of this present study demonstrate that the enzyme plays a role in the carbon uptake.

Results demonstrate that carbon dioxide and nisin synergistically influence the growth of Listeria monocytogenes. Data show that membrane permeabilization is altered consistent with nisin's action being influenced by the membrane fluidity.

Research was conducted to examine the molecular dissection of a basic COOH-terminal domain of Cx32 that inhibits gap junction gating sensitivity. Site-directed mutagenesis and chimeric construction methods were used to characterize domains of Cx32 and connexin38 potentially involved in CO2-induced channel gating in Xenopus oocyte pairs. Results indicate the possibility that the inhibition of gating sensitivity is caused by electrostatic interactions between CT1 and the cytoplasmic loop.

Problems associated with intermittent and variable degrees of sample blackening are often reported for studies involving the preparation of C[O.sub.2]-bearing silicate glasses in piston-cylinder apparatus. This phenomenon is generally attributed to H infiltration, which leads to the reduction of C[O.sub.2] and the precipitation of graphite with the concomitant formation of water. In this study we demonstrate that carbon diffusion into platinum capsules may be a common cause of blackened glasses and this process may be detected using fourier transform infrared spectroscopy (FTIR) to identify the presence of CO without elevated [H.sub.2]O contents. The simulated infiltration of 12C from a graphite furnace into a 13C-bearing sample is illustrated using secondary ion mass spectroscopy (SIMS) and microFTIR analysis. Careful FTIR monitoring of variable sample reduction has helped to identify the precautions required to reduce C (and H) infiltration in solid media assemblies and it appears that physical barriers can be more important than the chemical buffers traditionally employed.

Monitoring end-tidal carbon dioxide (CO2) in neonatal intensive care units can be accurate in in identifying levels of arterial CO2, but does not seem to be very precise in predicting high or low imbalances of CO2 which can be dangerous. End-tidal monitoring establishes levels of CO2 at the end of an outward breath. It was hoped this non-invasive form of monitoring might be more useful in predicting danger levels., Background. Continuous noninvasive monitoring of arterial carbon dioxide ([CO.sub.2]) in neonatal intensive care unit (NICU) patients would help clinicians avoid complications of hypocarbia and hypercarbia. End-tidal [CO.sub.2] monitoring has not been used in this population to date, but recent technical advances and the introduction of surfactant therapy, which improves ventilation-perfusion matching, might improve the clinical utility of end-tidal monitoring. Objective. To determine the accuracy and precision of end-tidal [CO.sub.2] monitoring in NICU patients. Design. Nonrandomized recording of simultaneous end-tidal and arterial [CO.sub.2] pairs. Setting. Two university NICUs. Patients. Forty-five newborn infants receiving mechanical ventilation who had indwelling arterial access, and a predefined subsample of infants who were [is less than] 1000 g birth weight, [is less than] 8 days of age, and who received surfactant therapy (extremely low birth weight [ELBW] [is less than] 8). Outcome Measures. The correlation coefficient, degree of bias, and 95% confidence interval were determined for both the overall population and the ELBW [is less than] 8 subgroup. Those factors which significantly influenced the bias were identified. The ability of the end-tidal monitor to alert the clinician to instances of hypocarbia or hypercarbia was determined. Results. There were 411 end-tidal/arterial pairs analyzed from 45 patients. The correlation coefficient was 0.833 and the bias was -6.9 mm Hg (95% confidence interval, [+ or -] 11.5 mm Hg). The results did not differ markedly in the ELBW [is less than] 8 infants. Measures of the degree of lung disease, the ventilation index and the oxygenation index, had small influences on the degree of bias. This type of capnometry identified 91% of the instances when the arterial [CO.sub.2] pressure was between 34 and 54 mm Hg using an end-tidal range of 29 to 45 mm Hg. End-tidal values outside this range had a 63% accuracy in predicting hypocarbia or hypercarbia. Conclusion. End-tidal [CO.sub.2] monitoring in NICU patients is as accurate as capillary or transcutaneous monitoring but less precise than the latter. It may be useful for trending or for screening patients for abnormal arterial [CO.sub.2] values. Pediatrics 1998;101:648-653; hypocarbia, hypercarbia, noninvasive monitoring, blood gas., ABBREVIATIONS. NICU, neonatal intensive care unit; [CO.sub.2], carbon dioxide; [Paco.sub.2], arterial [CO.sub.2] pressure; IVH, intraventricular hemorrhage; [PCO.sub.2], partial pressure of carbon dioxide; [EtCO.sub.2], end-tidal [CO.sub.2]; ELBW, extremely low birth weight; [...]

Research has established how allosteric bicarbonate HCO3- molecules bind to haemoglobin in red blood cells belonging to the reptile Alligator mississippiensis. Experiments show that carbon dioxide is absorbed into the bloodstream and carried by erythrocytes until it is excreted from the lungs. The binding of HCO3- molecules to haemoglobin is described.

The acetogenic bacterium Peptostreptococcus productus U-1 uses carbon dioxide (CO2) as an electron acceptor to synthesize acetate. Under limited CO2 concentration, P. productus U-1 grown in fructose is observed to synthesize lactate in high amounts as a reduced end product, but in the absence of CO2, the bacteria produces lactate and succinate as reduced end products. In contrast, bacteria grown in glycerol synthesizes high levels of ethanol in the absence of CO2. The results indicate that acetogens undergo fermentation to augment the absence of CO2 during lactate formation.

We have isolated mutants of Synechocystis PCC6803 that grew very slowly in a low-sodium medium, which is unfavorable for [Mathematical Expression Omitted] transport, and examined two of these mutants (SC1 and SC2) for their ability to take up C[O.sub.2] and [Mathematical Expression Omitted] in the light. The C[O.sub.2] transport activity of SC1 and SC2 was much lower than that of the wild type (WT), whereas there was no difference between the mutants and the WT in their activity of [Mathematical Expression Omitted] transport. A clone containing a 3.9-kilobase-pair insert DNA that transforms both mutants to the WT phenotype was isolated from a genomic library of WT Synechocystis. Sequencing of the insert DNA in the region of mutations in SC1 and SC2 revealed an open reading frame (designated cotA), which showed significant amino-acid sequence homology to cemA encoding a protein found in the inner envelope membrane of chloroplasts. The cotA gene is present in a single copy and was not cotranscribed with any other gene(s). cotA encodes a protein of 247 amino acids containing four transmembrane domains. There was substitution of a single base in SC1 and two bases in SC2 in their cotA genes. A possible role of the cotA gene product in C[O.sub.2] transport is discussed.

The role of the regB gene in bacterial signal transduction and CO2 fixation regulation in Rhodobacter sphaeroides was studied. Results revealed that aside from photosystem synthesis, the gene also plays a crucial role in the control of the Calvin cycle CO2 fixation operon. When light is available, regulation proceeds anaerobically. In the dark, however, it occurs aerobically. This suggests that regB belongs to a two-component system which codes for a sensor kinase controlling the regulation of light-independent and dependent CO2 fixation and the biosynthesis of the photosystem.

A study of an autonomous analytical system for calculation of the partial pressure differences of carbon dioxide (CO2) between the atmosphere and the sea surface reveals that time series records of CO2 partial pressures can be procured from moorings by using instrumentation based on commercially available technology. The accuracy of the calculations are within 2 micro atmospheressufficient for the estimation of air-sea CO2 changes and biologically produced in situ changes.

The coelomic and blood CO2 concentrations in the body fluids of hydrothermal vent Riftia pachyptila, observed on the East Pacific Rise at the 13 degrees site, show extraordinary levels up to 50 mmol/l. Gel filtration analysis reveals major CO2 retention by the protein-free fractions. The nature of such base excess in the protein-free fractions may be attributed to 3 functions: CO2 retention in the body fluids during low external partial pressures P(sub CO2), buffer action during high P(sub CO2) and to provide a CO2 store for carbon fixation by symbiotic bacteria during variations in CO2 supply.

Cyanobacteria possess a [CO.sub.2]-concentating mechanism that involves active [CO.sub.2] uptake and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] transport. For [CO.sub.2] uptake, we have identified two systems in the cyanobacterium Synechocystis sp. strain PCC 6803, one induced at low [CO.sub.2] and one constitutive. The low [CO.sub.2]-induced system showed higher maximal activity and higher affinity for [CO.sub.2] than the constitutive system. On the basis of speculation that separate NAD(P)H dehydrogenase complexes were essential for each of these systems, we reasoned that inactivation of one system would allow selection of mutants defective in the other. Thus, mutants unable to grow at pH 7.0 in air were recovered after transformation of a [Delta] ndhD3 mutant with a transposon-bearing library. Four of them had tags within slr1302 (designated cupB), a homologue of sll1734 (cupA), which is cotranscribed with ndhF3 and ndhD3. The [Delta] cupB, [Delta] ndhD4, and [Delta] ndhF4 mutants showed [CO.sub.2]-uptake characteristics of the low [CO.sub.2]-induced system observed in wild type. In contrast, mutants [Delta] cupA, [Delta] ndhD3, and [Delta] ndhF3 showed characteristics of the constitutive [CO.sub.2]-uptake system. Double mutants impaired in one component of each of the systems were unable to take up [CO.sub.2] and required high [CO.sub.2] for growth. Phylogenetic analysis indicated that the ndhD3/ ndhD4-, ndhF3/ndhF4-, and cupA/cupB-type genes are present only in cyanobacteria. Most of the cyanobacterial strains studied possess the ndhD3/ndhD4-, ndhF3/ndhF4-, and cupA/cupB-type genes in pairs. Thus, the two types of NAD(P)H dehydrogenase complexes essential for low [CO.sub.2]-induced and constitutive [CO.sub.2]-uptake systems associated with the NdhD3/NdhF3/CupA-homologues and NdhD4/NdhF4/CupB-homologues, respectively, appear to be present in these cyanobacterial strains but not in other organisms. NAD(P)H dehydrogenase | constitutive [CO.sub.2] uptake | affinity to [CO.sub.2] | [CO.sub.2]-concentrating mechanism

Wild-type Chlamydomonas reinhardtii cells shifted from high concentrations (5%) of [CO.sub.2] to low, ambient levels (0.03%) rapidly increase transcription of mRNAs from several [CO.sub.2]-responsive genes. Simultaneously, they develop a functional carbon concentrating mechanism that allows the cells to greatly increase internal levels of [CO.sub.2] and [HCO.sub.3]. The cia5 mutant is defective in all of these phenotypes. A newly isolated gene, designated Cia5, restores transformed cia5 cells to the phenotype of wild-type cells. The 6,481-bp gene produces a 5.1-kb mRNA that is present constitutively in light in high and low [CO.sub.2] both in wild-type cells and the cia5 mutant. It encodes a protein that has features of a putative transcription factor and that, likewise, is present constitutively in low and high [CO.sub.2] conditions. Complementation of cia5 can be achieved with a truncated Cia5 gene that is missing the coding information for 54 C-terminal amino acids. Unlike wild-type cells or cia5 mutants transformed with an intact Cia5 gene, cia5 mutants complemented with the truncated gene exhibit constitutive synthesis of mRNAs from [CO.sub.2]-responsive genes in light under both high and low [CO.sub.2] conditions. These discoveries suggest that posttranslational changes to the C-terminal domain control the ability of CIA5 to act as an inducer and directly or indirectly control transcription of [CO.sub.2]-responsive genes. Thus, CIA5 appears to be a master regulator of the carbon concentrating mechanism and is intimately involved in the signal transduction mechanism that senses and allows immediate responses to fluctuations in environmental [CO.sub.2] and [HCO.sub.3] concentrations.

Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to [CO.sub.2]-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense [CO.sub.2] availability. Previously, a high-[CO.sub.2]-requiring mutant C16 defective in an induction of the CCM was isolated from C. reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gln repeat characteristic of transcriptional activators. Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast, and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-[CO.sub.2] conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing [CO.sub.2] availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.

The consequences of elevated [CO.sub.2] on plant growth have been well studied on individual plants. The response of a more complex system with several plants interacting is less understood--a situation that limits our capacity to predict the response of natural plant communities. In this study we analyzed the effect of [CO.sub.2] enrichment on intergenotypic competition in Arabidopsis thaliana. Seeds of five genotypes collected from different natural populations were used. Each genotype was cultivated in a pure stand and in a mixture with each of the other four genotypes in two [CO.sub.2] conditions (ambient and elevated). At harvest time, genotype fitness was estimated by the number of fruits and seeds produced per plant. At current levels of [CO.sub.2], genotypes performed better in a pure stand than in a mixture. Kin selection, associated with the low seed dispersal and autogamous reproductive regime of A. thaliana, is invoked to explain these positive responses among plants of similar genotype. Surprisingly, in a high-[CO.sub.2] atmosphere (700 [micro]L/L) the reverse situation was observed: plants performed better in mixtures than in pure stands. Positive frequency-dependent selection under ambient [CO.sub.2] concentration became negative under elevated [CO.sub.2], which could lead more easily to the maintenance of genetic variation. This hypothesis was tested with a simple model of competition. At equilibrium, the simulation did not show coexistence among more genotypes under elevated [CO.sub.2] than under ambient [CO.sub.2] concentration. However, this study allows predictions about evolutionary trajectories under high-[CO.sub.2] conditions. In A. thaliana, genotypes that will maintain the most their ability to grow well in pure stand should be selected under increasing [CO.sub.2]. Key words: Arabidopsis thaliana; elevated [CO.sub.2] and competition among genotypes; fitness; genotype; global change, implications of elevated [CO.sub.2]; intraspecific competition; kin selection; selection, frequency dependent.

Three perennial grass species, perennial ryegrass (Lolium perenne L.), colonial bentgrass (Agrostis capillaris L.), and sheep fescue (Festuca ovina L.), were grown at two [CO.sub.2] concentrations (350 and 700 [micro]L [L.sup.-1]) and under two N regimes: one with a minor addition of 8 kg N [ha.sup.-1] and one with an addition of [approximately equals] 78 kg N [ha.sup.-1], both labeled with [sup.15]N. The effects of elevated [CO.sub.2] on [sup.15]N and N uptake and dynamics in the plant-soil systems were determined after 32 and 55 d, with close attention to the rhizosphere. Total N uptake by the plants was not affected by elevated [CO.sub.2], compared with ambient [CO.sub.2], independent of N treatment and grass species. A clear decrease from 1.77 at ambient [CO.sub.2] to 1.25 at elevated [CO.sub.2] was observed in the shoot/root (S/R) ratio of N, resulting from a significant decrease of the N concentration in shoots, and an unchanged root N concentration. At 700 [micro]L [L.sup.-1] [CO.sub.2], N concentration in the shoots decreased from 12.9 to 9.9 g [kg.sup.-1], even at the low N supply, whereas the slight decrease in root N concentration for plants grown at elevated [CO.sub.2] (7.9 vs. 7.3 g [kg.sup.-1]) was not significantly different. The relative increase of [sup.15]N found in the rhizosphere soil microbial biomass (SMB) and the rhizosphere soil residue under elevated [CO.sub.2] was too small to affect plant growth, even in the low N treatment. The total amount of [sup.15]N recovered in the plants was not affected by the [CO.sub.2] treatment. Although at the second harvest slightly more [sup.15]N was found in the plants than at the first harvest, probably due to turnover of the SMB, no interaction with [CO.sub.2] was observed. This shows that the fertilizer [sup.15]N had not been immobilized to a larger extent or for a longer time by the SMB at elevated [CO.sub.2] than under ambient [CO.sub.2], even independent of N level and grass species. No evidence was found that under elevated [CO.sub.2] substantial amounts of N had been immobilized by the SMB, nor that mineralization of native soil organic matter (SOM) had been stimulated by an increased supply of substrate to the SMB. We conclude that elevated [CO.sub.2] has the potential to induce significant changes in plant N nutrition, modifying N allocation and tissue quality within perennial grasses, but that these effects appear to be independent of the SMB.

Research describing the process of diffusive transportation of monomeric solutes and micelles in carbon dioxide is presented. Particular attention is given to the technique of selecting ionic surfactants with high conductivity as well as electroactive solutes.

Starburst polyamidoamine generation O dendrimers with EDA core were used as the membrane liquid to strongly facilitate CO2 transport.

A software package for reviewing the factors controling O2/CO2 levels in the body is useful for upper-level college and biomedical students. The user is an active participant in the learning process. The manual is a strong part of the package, the main screen of which represents a strip-chart recording, containing seven parameters graphed as a function of time. An alpha key allows interruption of the simulation at any point. However, the graphics are poor, the operation is slow and the user interface is weak. The program is suitable for workshops, independent study, and in laboratories.

As greenhouse warming experts try to predict how much the world's climate may heat up in the next century, they keep bumping up against a mystery: Where does much of […]