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At least 19 recordsLinked to original sources
PubMed2026

Cooperation and the evolution of bacterial niche breadth.

Bacteria exhibit varying niche breadths, with generalists thriving in diverse environments and specialists confined to specific habitats. Although genes for cooperative traits have been suggested to influence niche breadth evolution, their precise role remains unclear. We used a combination of phylogeny-based comparative methods to test causal hypotheses about the directionality of the relationship between genes for cooperation and bacterial niche breadth evolution across 25,785 species. Our results revealed 1) a positive correlation between the proportion of genes for cooperation and niche breadth; 2) genes for cooperation influenced niche breadth evolution, with a decreased proportion of such genes promoting niche contraction as the predominant evolutionary direction; and 3) genes for cooperation experience more frequent gain and loss within species rather than across species. These findings suggest a role of bacterial cooperation in influencing niche breadth evolution and maintaining the ecological versatility of bacteria. While our results are consistent with a simple relationship under the hypotheses tested, more complex causal scenarios are possible, including the role of factors that influence both cooperation and niche breadth.

Phylogeny↗
PubMed2025

Competition and cooperation: The plasticity of bacterial interactions across environments.

Bacteria live in diverse communities, forming complex networks of interacting species. A central question in bacterial ecology is whether species engage in cooperative or competitive interactions. But this question often neglects the role of the environment. Here, we use genome-scale metabolic networks from two different open-access collections (AGORA and CarveMe) to assess pairwise interactions of different microbes in varying environmental conditions (provision of different environmental compounds). By computationally simulating thousands of environments for 10,000 pairs of bacteria from each collection, we found that most pairs were able to both compete and cooperate depending on the availability of environmental resources. This modeling approach allowed us to determine commonalities between environments that could facilitate the potential for cooperation or competition between a pair of species. Namely, cooperative interactions, especially obligate, were most common in less diverse environments. Further, as compounds were removed from the environment, we found interactions tended to degrade towards obligacy. However, we also found that on average at least one compound could be removed from an environment to switch the interaction from competition to facultative cooperation or vice versa. Together our approach indicates a high degree of plasticity in microbial interactions in response to the availability of environmental resources.

Microbial Interactions↗
PubMed1975

[Effects of thymectomy on the natural bactericidal power of thymectomized mice].

T and B-dependent systems are correlated between themselves and with the macrophage system in eliciting the immune humoral response. Not all immunogens require T-B interactions to elicit the antibody response: consequently, the problem of the limits of T-dependence, with regard to different immunogen stimulations, remains open. The comparative study of the serum antibody response in mice, thymectomized at birth and in the normal ones, inferred from the values of bactericidal activity (b.a.), detected versus E. coli, S. typhi and S. albus strains did point out evident variation. Thymectomy has impaired b.a. against E. coli; it seems to have no consequence on b.a. against S. typhi; is not possible to the results of our investigation, it seems that the response to the immunogens, responsible for the so-called natural antibodies does require T-B cooperation only for some bacterial species and not for others. A higher bactericidal capacity of normal serum with regard to Gram positive as compared with Gram negative bacteria, is confirmed.

Animals↗
PubMed1977

Respiratory infection in an intensive care unit.

A postmortem bacteriological study of Black children in a respiratory intensive care unit showed that Pseudomonas aeruginosa was the most common opportunistic pathogen and that it usually complicated a viral infection. In a parallel study of non-debilitated patients in general hospital wards Klebsiella aerogenes and Escherichia coli were the most frequently isolated organisms. Counter-immuno-electrophoresis was used for the identification of Pseudomonas-precipitating antibody in serum and tracheal secretions, and also of Pseudomonas antigen in the latter.

Antigens, Bacterial↗
PubMed1976

Automatic quantitative radiometric assay of bacterial metabolism.

In a two-compartment scintillation vial, suspensions of bacteria were cultured with 1 muCi of [U-14C] glucose and the released 14C02 was measured continuously, cumulatively, and automatically in a liquid-scintillation counter modified to maintain sample temperature at 37 degrees C. We could follow the metabolism of bacterial populations through their early phase of exponential growth with good precision. The data were obtained conveniently, with use of conventional reagents, glassware, and counting equipment. From analysis of the exponential portion of the curves for cumulative activity vs. time, we could measure cell replication rate precisely in units of time. The resulting values were demonstrably independent of some common experimental variables, including the number of bacteria in the inoculum and counting system sensitivity. Sensitivity of the bacteria to antibiotics was measured to within a few percent by noting the relative prolongation of replication time in the presence of those inhibitors. The digital data from the scintillation counter are susceptible to on- or off-line computer analysis, thus providing the prospect for a totally-automated analytical system. The method shows promise for the mechanized quantitative analysis of bacterial growth, and its inhibition.

Anti-Bacterial Agents↗
PubMed1977

Cooperative and antagonistic interactions of peptidyl-tRNA and antibiotics with bacterial ribosomes.

There is a single-site interaction of [methylene-14C]thiamphenicol and [methylene-14C]chloramphenicol with run-off ribosomes with dissociation constants Kd = 6.8 micronM and Kd = 4.6 micronM respectively. Similar affinities for the antibiotics are observed in polysomes totally deprived of nascent peptides, or bearing nascent peptides on the A-site. However, two types of interaction are observed in endogenous polysomes with some ribosomes bearing nascent peptides on the P-site and other in the A-site. The lower-affinity bindings (dissociation constants Kd = 6.4 micronM and Kd = 1.5 micronM for thiamphenicol and chloramphenicol respectively) are due to the ribosomes bearing nascent peptides on the A-site. The higher-affinity bindings (dissociation constants Kd = 2.3 micronM and Kd = 1.5 micronM for thiamphenicol and chloramphenicol, respectively) are due to the ribosomes bearing nascent peptides on the P-site. Therefore binding of nascent peptides to the A-site does not affect the affinities of thiamphenicol and chloramphenicol for the ribosome. On the other hand interaction of the nascent peptides with the P-site of the ribosomes increases the affinities of both antibiotics for the ribosome. Thiamphenicol and chloramphenicol are thus good inhibitors of peptide bond formation in ribosomes and polysomes. Their affinities are increased precisely when the peptidyl-tRNA is placed in the P-site preceeding the peptide bond formation step, which is specifically blocked by the antibiotics. There is a single-site interaction per ribosome for [35S]thiostrepton, which does not appear to be affected by the attachment to the ribosomes of mRNA, tRNA and nascent peptides either to the A or the P-site. [N-methyl-14C]Lincomycin, [N-methyl-14C]erythromycin, [G-3H]streptogramin B and [G-3H]-streptogramin A bind to run-off ribosomes and polysomes totally free from nascent peptides. However, these antibiotics do not interact with ribosomes bearing nascent peptides either in the A or the P-site and therefore are not active on preformed polysomes. Thus lincomycin and streptogramin A only interact with free ribosomes and 50-S subunits and block the early rounds of peptide bond formation prior to polysome formation. Erythromycin and streptogramin B do not inhibit either initiation or the first round of peptide bond formation. However, erythromycin and streptogramin B, prebound to the ribosome, block peptide elongation probably by steric hindrance with the growing oligopeptide chain when this reaches a certain critical length.

Anti-Bacterial Agents↗
PubMed1975

The effects of protein deprivation on cell-mediated immunity.

The effect of protein insufficiency on immune responsiveness was investigated in inbred mice fed isocaloric diets low and normal in protein. Mice were tested for aberrations of cell-mediated and humoral immunities. Protein insufficiency enhances cell-mediated immunity while depressing or not affecting humoral immunity. Cell-mediated immunity was enhanced in testing: allogeneic skin graft rejection, spleen cell responsiveness to phytohemagglutinin, the graft-vs-host reaction, macrophage function, and resistance to viral and bacterial infections.

Animals↗
PubMed1979

[Therapy of bacterial endocarditis].

The successful treatment of bacterial endocarditis requires a close cooperation to a clinical microbiological laboratory. This performs blood cultures, estimation of sensitivity to the different antibiotics, if anyhow possible also quantitatively, and supervision of therapy by serum bactericidal tests. Synergistic combinations by adding one of the aminoglycosides bring the best chances for therapeutic success. Special advices are given in dependence of the numerous causative bacterial agents. Rare ones are sufficiently taken into consideration. If blood cultures remain negative, empiricial chemotherapy is recommended. Surgical treatment by operative replacement of the infected heart valves and insertion of prosthetic ones is indicated in uncontrolled infection, in severe heart failure caused by valve perforation, and in recurrent embolism. Early interventions have a much better prognosis. Special problems are connected to bacterial endocarditis in prosthetic valves. Bacterial endocarditis in drug addicts is of relatively good prognosis in spite of the frequent complications. Patients with suspicious or evident bacterial endocarditis should be transferred to centers owing sufficient diagnostic and therapeutic experiences.

Administration, Oral↗
PubMed1978

The role of OEP-antibodies in Pseudomonas aeruginosa infection.

When mice were challenged intraperitoneally with 2.2 X 10(4) Pseudomonas aeruginosa in 0.5 ml of 2.7% mucin solution, the bacteria markedly increased in the peritoneal cavity, rapidly entered the blood stream, and the mice died, probably of bacteremia, within a short time. However, when mice were injected subcutaneously 4 hours prior to the challenge with 0.2 ml of 0.75% IgG (OEP-HA = 12.8) or IgM (OEP-HA = 64) separated from human plasma or 3% S-IgA EP-HA = 19.2) from fresh human milk, the bacteria were inhibited from propagating and were eliminated from the cavity so that they could not enter the blood stream. As a result, the mice tolerated the challenge and survived. When 3% IgA (OEP-HA less than 0.8) from human plasma was given, a complete cure was not effected in a few mice despite a general tendency of healing. Determination of the number of viable intra- and extracellular bacteria in the peritoneal cavity revealed that the infecting bacteria were rapidly phagocytized and killed by the peritoneal phagocytes in the presence of OEP-antibodies. These findings indicate that the effect of bacterial clearance from the cavity results from the cooperative action of OEP-antibodies and peritoneal phagocytes. Marked enhancement of phagocytosis by the antibodies was observed in an in vitro study in the presence of a heat-labile, complement-like substance(s). This finding is interpreted as evidence of the cooperative activity.

Animals↗
PubMed1977

Streptococcus pneumoniae resistant to penicillin and chloramphenicol.

Three cases of meningitis and two of septicaemia were caused by pneumococci resistant to the penicillins/cephalosporins and chloramphenicol. No beta-lactamase was demonstrated in any of the organisms. All three patients with meningitis died, but the patients with septicaemia recovered after being given appropriate antibiotic therapy.

Anti-Bacterial Agents↗
PubMed1975

Salmonella enteritidis infection in rats: antigens involved in cell-mediated immunity.

When rats are sub-lethally infected with S. entertidis by the intravenous route, there is a period of at least 14 days in which peritoneal exudate cells are unable to migrate from capillary tubes on to glass surfaces; thereafter they migrate as do macrophages from normal animals. The migration of peritoneal cells from rats infected 18-21 days previously is inhibited by lipopolysaccharide (LPS) prepared from homologous and heterologous strains of Salmonella. The apparent non-specificity of LPS activity in the macrophage migration inhibition test has been resolved by demonstrating that lipid A, containing less than 0.01% protein amino acids, is also capable of eliciting this test of cell-mediated immunity.

Animals↗
PubMed1978

Antibodies in the intestinal secretions of rats. Primary and secondary responses to polymeric flagellin.

The antibody responses in serum and secretions obtained from the mucosal surfaces of the small intestine of rats immunized by a parenteral and intestinal route have been compared. Though no significant differences in the mean serum titres were found, the responses of animals immunized via the latter route to large doses of antigen were far less uniform. Apart from the first few days of the primary response, antibody activity was found in three major immunoglobulin classes (IgG2, IgA and IgM), irrespective of the route of immunization. Significant antibody activity appeared in the intestinal surface secretions only after two injections of antigen. In rats immunized parenterally the activity was found only in the IgG2 component. Whilst activity was found in both IgG2 and IgA fractions of the secretions obtained from intestinally immunized rats, it was predominantly of the IgG2 class. The possible significance of this observation is discussed.

Animals↗