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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Mathematical model of an experimental ecological system with spatially separated components].

The paper describes a model of an experimental ecological system consisting of autotrophic and heterotrophic components and a nutrient medium. The system has a zero stationary state and needs a correction. The life time of the system and the level of the necessary correction have been determined for the experimental ecological system: lettuce - slugs - nutrient solution. Optimal conditions for the conjugation of trophic components of the system have been established.

Ecological Systems, Closed↗
PubMed2026

Trichoderma specialized metabolites in biocontrol: gene-metabolite links, ecological functions, and translational bottlenecks.

Trichoderma spp. produce a diverse repertoire of metabolites with specific activities that contribute to biocontrol through direct antagonism, ecological signalling, and modulation of plant responses. However, current knowledge remains uneven: many metabolites are chemically described, whereas fewer are supported by robust gene-metabolite associations, experimentally validated ecological functions, and realistic translational evidence. Progress in this field will depend less on expanding compound catalogues than on integrating mechanistic, ecological, and translational evidence. This review examines the specialized metabolism of Trichoderma with emphasis on biosynthetic gene clusters, regulatory networks, ecological roles, and biosafety constraints relevant to biocontrol. Major metabolite classes, including polyketides, terpenoids, peptaibols, siderophores, diketopiperazines, and volatile organic compounds, are discussed together with representative case studies for which genetic and functional evidence is available. We further propose a translational framework to distinguish metabolites with mainly descriptive support from those approaching application readiness, based on four criteria: gene-level validation, demonstrated ecological role, manageable biosafety profile, and feasible delivery/stability. This perspective helps explain why metabolite inventories continue to expand faster than field translation. Recent advances in genomics, transcriptomics, metabolomics, genome editing, and formulation science are reshaping how Trichoderma metabolites are prioritized for future development.

Biosafety↗
PubMed2026

Biocontrol potential and molecular basis of predation in a marine raptorial ciliate.

Predator-prey interactions are widespread across organisms and are key drivers of morphological and behavioral evolution. Despite this, predation remains poorly understood among microbial eukaryotes, mostly due to the absence of a tractable experimental system that allows quantitative, reproducible investigation. This study establishes the marine raptorial ciliate Chaenea vorax as a highly efficient predator, with Rosenzweig-MacArthur model simulations based on predation data showing that only a few dozen individuals can eliminate the vast majority of the facultatively pathogenic ciliate Uronema marinum within 1-2 days, providing a quantitative basis for developing predator-based biocontrol strategies in aquaculture. Genomic analysis shows that C. vorax possesses a highly fragmented macronuclear genome enriched with predation-related pathways, including calcium-mediated contractility, cellular proteolysis, toxin expulsion systems, among others. Transcriptomic profiling during predation events further demonstrates significant upregulation of genes involved in cytoskeletal remodeling, proteolytic activity, and cellular detoxification. Evolutionary analyses suggest that C. vorax has an extremely long evolutionary history, exceptionally high nucleotide diversity even among ciliates, and gene family expansions linked to predatory adaptation. Although the prey possesses certain defensive mechanisms (e.g. trichocysts), these are largely ineffective against short-term predation in closed aquatic environments. These findings provide fundamental insights into the molecular basis of predation in ciliates and suggest the potential utility of C. vorax in biocontrol applications targeting pathogenic ciliates.

Ciliophora↗
PubMed1979

Host-parasite relationship in schistosomiasis mansoni in the mutation diabetic mouse (db/db).

Impairment of cell-mediated immunity has been described in chemically-induced as well as mutation diabetes in the mouse. The present report examines the host-parasite relationship during the acute phase of schistosomiasis mansoni in the mutation diabetic mouse (db/db). Cercarial penetration and maturation and egg output by adult worms were similar in the db/db mice and their littermate controls (db/+). In contrast, the pathological consequences of schistosomiasis were much less in the db/db mice. The mean liver weight computed as a percentage of body weight in db/db mice was 4.6 +/- 0.2 and following 8 weeks of infection it was 5.7 +/- 0.3 (difference is not statistically significant), whereas in infected db/+ mice it was 7.2 +/- 0.5. Infection in db/+ mice increased their mean portal pressure by 124% in contrast to an increase of only 12% in db/db animals. The most striking difference was noted in the mean granuloma diameter in the liver: 402 +/- 35 micrometer in db/+ in comparison to 147 +/- 10 micrometer in db/db mice (P less than 0.001). This study demonstrates the crucial role of the host granulomatous response in the causation of disease due to Schistosoma mansoni. Furthermore, it underlines the decreased pathological consequences when the host granulomatous response is suppressed, which can be compared to the response of modulated animals with chronic schistosomiasis.

Animals↗
PubMed1979

An experimental study of the pathology and ecology of Yersinia enterocolitica infection in mice.

Four experiments are described in which laboratory mice were infected with Y. enterocolitica using an American serotype 0:8 (WA) and two European strains, serotypes 0:3 and 0:9. The pathogenicity and histopathological responses of strain WA (0:8) were determined in the Porton white outbred mouse by three route of inoculation. The LD50 after infection by the intraperitoneal route was 8.8 x 10(1) organisms, which is similar to results obtained by previous workers using disease-free and hybrid mouse strains. European strains 0:3 and 0:9 were shown to infect the Porton white outbred mice when injected intraperitoneally but no deaths occurred. Chronic faecal excretion was demonstrated up to 135 days. Specific antibodies were detected in the 0:3 and 0:9 infected mice and the immune response was further assessed by challenging the excreter mice with 50LD50S of the virulent WA strain. A significant degree of protection occurred in mice previously injected with 10(7) organisms of the avirulent strains. No evidence of phenotypic variation, as measured by 40 markers, was detected in 67 isolates of Y. enterocolitica recovered during the course of the four experiments. These results suggest that laboratory rodents could be a useful model for studying the infection produced by virulent and avirulent strains, and since it has been clearly established that a wide range of serotypes and non-typeable strains may be isolated from wild rodents, our findings could be extrapolated to the wildlife situation. Further work on the laboratory model could give a more detailed insight into the mechanism and extent to which rodents act as reservoirs of Y. enterocolitica.

Animals↗
PubMed2025

Reproductive Isolation due to Divergent Ecological Selection Is Accompanied by Vast Genomic Instability in Experimentally Evolved Yeast Populations.

Populations evolving independently in divergent environments accumulate genetic differences and potentially evolve reproductive isolation as a by-product of divergence. The speed and mechanisms underlying this process are difficult to investigate because we rarely get the opportunity to witness them in natural settings, and histories of selection and gene flow between populations are often unknown. Here, we experimentally evolved yeast for 1000 generations of evolution in both divergent and parallel environments. At regular time points during experimental evolution, we made crosses between parallel- and divergent-evolving populations to measure postzygotic reproductive isolation (gamete viability). We used whole genome population sequencing to determine the mutational load, the number and types of structural variation, and other genomic features of the parent, F1 and F2 intraspecific hybrids. We found evidence for large-scale phenotypic and genome-wide differentiation in response to divergent laboratory selection. Divergent-selected populations produced hybrids with reduced gamete viability-a classic signature of postzygotic reproductive isolation in the form of hybrid breakdown. Parallel-selected populations, on the other hand, remained more reproductively compatible (with exceptions). We found that F2 hybrid genomes contained vast genomic instability, that is, new structural variants (especially insertions, deletions and interchromosomal translocations) that were not observed in parent and F1 genomes, which is likely a result of chromosome missegregation and recombination errors in hybrid meiosis. Our results provide phenotypic and genomic evidence that partial reproductive isolation evolved due to adaptation to divergent environments, consistent with predictions of ecological speciation theory.

Reproductive Isolation↗
PubMedDate not supplied

[Ecology of leishmaniasis in the south of France. 11. Canine leishmaniasis: successful experimental transmission from dog to dog by the bite of Phlebotomus ariasi Tonnoir, 1921 (author's transl)].

As part of a study of visceral leishmaniasis in the Cévennes in southern France, an infection was transmitted from dog to dog by the bite of a single sandfly, Phlebotomus ariasi Tonnoir, 1921. The role of this species as a vector, suspected from earlier studies, is, therefore, confirmed. Twenty female sandflies, which had engorged on a naturally infected dog 23 +/- 2 days previously were put with a healthy dog which, after an incubation period of 15 months, developed viscero-cutaneous leishmaniasis. In dissections of the sandflies immediately after contact with the experimental dog, it was found that only one had engorged. All of 17 sandflies dissected had midgut infections: 10 of these also had infections in the pharynx. The engorged specimen additionally had parasites in the proboscis, a condition thought by many workers to be necessary for the parasite to be transmitted by bite.

Animals↗
PubMed2025

The ecology and evolution of microbial immune systems: a look on the wild vibrio side.

Natural populations of vibrio beyond the well-studied pandemic strains of Vibrio cholerae, provide a powerful model for investigating the eco-evolutionary dynamics of microbial immune systems. Their genetic diversity, ecological versatility, ease of culturability and the availability of time-series data enable detailed studies of phage-host interactions in natural contexts. This review synthesizes recent advances in vibriophage research, highlighting key findings and emerging tools. High-throughput assays and genomic tools have offered new perspectives on phage specificity, host range and the evolutionary pressures shaping these interactions. Theoretical frameworks, such as arms race and fluctuating selection dynamics, are informed by empirical data from vibrio-phage systems, with time-series sampling providing crucial insights into their temporal and spatial dynamics. A major finding is the role of mobile genetic elements (MGEs) in encoding bacterial defence systems, which shape phage-host coevolution. Discoveries like the phage satellite PICMI illustrate how MGEs facilitate the transfer of antiviral systems, influencing ecological and evolutionary dynamics. The paradox of generalist vibriophages, rare despite their broad host ranges, is also explored. By integrating experimental approaches with field observations, vibriophage research advances microbial ecology and informs sustainable applications in aquaculture and phage therapy, reinforcing vibrios as a versatile model system.This article is part of the discussion meeting issue 'The ecology and evolution of bacterial immune systems'.

Bacteriophages↗
PubMed1976

[Increase of resistance to Pseudomonas aeruginosa infection in mice caused by Staphylococcus aureus].

In our study of opportunistic pathogens, we have some indication that Staphylococcus aureus can increase resistance in mice against Pseudomonas aeruginosa. Intraperitoneal injections of sublethal doses of S. aureus had a protective effect in mice against lethal doses of P. aeruginosa, more so if living and coagulase-positive S. aureus strains were injected. This protective effect was obtained both with laboratory and freshly isolated hospital strains. The interval between these infections can be extended from 2 h up to 1 week and it is still possible to observe the resistance phenomenon. The increased resistance was accompanied by a decrease in viable units of P. aeruginosa in the peritoneal cavity of mice 6 h after the injection of this species. There was no protection by S. aureus against Candida albicans in similar experimental conditions. These observations indicate that intermicrobial ecology, understood here as the previous presence of another species in a host, may be a significant factor in the resistance to infection with opportunistic pathogens such as P. aeruginosa.

Antitoxins↗
PubMed1978

[Effect of sulfide water from natural springs on the properties of Vibrino cholerae].

The authors studied the properties of E1 Tor cholera vibrios isolated from sulfide water of the natural sources. There was demonstrated under experimental and natural conditions the influence of ecological conditions of sulfide water on such vibrio properties as cholerogenicity, sensitivity to diagnostic and typing phages, hemolytic activity and the value of the hemolysin-destructive factor. A short-liver stay of cholera vibrios in sulfide water was accompanied by some reduction of their virulence.

Animals↗
PubMed2026

Functional unknomics of the SAR11 clade reveal hidden genetic potential underlying adaptation to bottom-up and top-down pressures.

UNLABELLED: A substantial fraction of the genes in bacteria lack detectable sequence similarity to genes with known functions. These functionally uncharacterized genes-collectively referred to as the "unknome"-represent a largely unexplored genetic repertoire harboring insights into marine bacterial ecology. In this study, we explored the function of the unknome of the SAR11 clade, the most abundant bacterial lineage in the ocean, with a particular focus on genes that provide insight into its ecology. Based on the Clusters of Orthologous Genes and Kyoto Encyclopedia of Genes and Genomes classifications, approximately 56% of SAR11 ortholog groups were classified as members of the unknome. Among the SAR11 unknome, we successfully inferred the functions of 57 ortholog groups that are conserved in the SAR11 clade by protein structure similarity searches and genomic context analyses. These ortholog groups include putative transporter components, supporting the current ecological understanding that the SAR11 clade is specialized in substrate uptake to adapt to oligotrophic marine environments. Furthermore, structural analysis indicated that the DUF2237-containing protein, enriched in marine environments, may interact with purine nucleotide-containing compounds. This may suggest the existence of unique nucleotide utilization mechanisms in marine bacteria. In addition, we identified candidate viral defense systems within the unknome, indicating that diverse defense systems are present in at least one-third of cultured SAR11 strains. The presence of these defense systems, even within streamlined SAR11 genomes, suggests that they confer significant ecological advantages. Our analyses provide insights into the genetic basis of bottom-up processes (adaptation to oligotrophic environments) and top-down processes (antiviral defense strategy) contributing to ecological success. IMPORTANCE: Many microbial genes have no experimentally established function, limiting our ability to explain how microorganisms adapt to their environments. We examined this uncharacterized gene space, or "unknome" in SAR11, the most abundant bacterial clade in the ocean, by integrating evolutionary conservation, genomic context, predicted protein structure, and environmental distribution. This approach enabled us to prioritize components of the SAR11 unknome, including a core unknome conserved across the clade and genes enriched in specific lineages, and to identify several candidates with possible ecological roles in nutrient acquisition and defense against viruses. Our results suggest that the SAR11 unknome contains important clues to the ecological success of SAR11 rather than merely reflecting incomplete annotation or gene-prediction artifacts. Our study highlights the potential value of unknome analysis for identifying ecologically relevant genes in environmental microorganisms.

Pelagibacterales↗
PubMed1979

The effect of different zooxanthellae on the growth of experimentally reinfected hosts.

1. A method is given enabling the differential effects of different strains of zooxanthellae on host growth to be assessed. This technique uses the increase in the number of tentacles as the measure of growth. 2. Aposymbiotic polyps of the anemone Aiptasia pulchella reinfected with strains of Symbiodinium microadriaticum isolated from the anemone Aiptasia pulchella and the scyphozoan Cassiopea xamachana grow as well as normal Aiptasia polyps. 3. Aposymbiotic Aiptasia polyps reinfected with zooxanthellae from the gastropod Melibe pilosa and the clam Tridacna maxima grew no better than polyps lacking zooxanthellae. 4. These results lead to the conclusion that strains of zooxanthellae differ in their ability to enhance growth of Aiptasia polyps under the experimental conditions and that these differences may have important ecological consequences.

Animals↗
PubMed1979

The uses of experimental ecosystems.

The experiments conducted so far with large experimental ecosystems have probably taught us more about the general ecological interactions in such systems than about subtle long-term effects of pollutants. This knowledge is not only valuable in its own right but may be more useful in an indirect rather than a direct way, in understanding the robustness of these systems and so evaluating the general effects of stresses.

Animals↗
PubMed1976

Broader investigation into the external environment of the specific antigen of the infectious agent in epizootiological observation and study of the structure of natural foci of plague.

The possibilities of detection of the infectious agent in natural foci of plague can be expanded to some extent by using the method of search for the specific FI capsular antigen of the plague microbe in such objects of the external environment which have not yet been subjected to laboratory analysis and serological analysis in particular. Such objects include soil from the burrow and the substrate of the nest of the rodent as well as the fleas of rodents and regurgitations of birds of prey. The effectivity and suitability of examination of these objects using immuno-adsorption reactions with standard erythrocyte diagnostics (passive haemagglutination reaction, antibody neutralization reaction) were demonstrated experimentally and confirmed under field conditions in various geographical and ecological zones of the Caucasus. Thus in 1971, an earlier unknown natural focus of plague was found in the Mount Elbrus massif by means of serological analysis of the substrate of the nest and of the soil from the burrows of rodents. It can be expected that broadened serological search for the FI antigen of plague will prove useful in the study of the structure of natural foci of plague, in the reconnaissance or retrospective investigation of poorly explored territories and in the solution of some questions concerning the epizootiology of plague, such as the survival of the infectious agent in the inter-epizootic period, telluric plague, etc.

Animals↗
PubMed1976

Broader investigation into the external environment of the specific antigen of the infectious agent in epizootiological observation and study of the structure of natural foci of plague.

The possibilities of detection of the infectious agent in natural foci of plague can be expanded to some extent by using the method of search for the specific FI capsular antigen of the plague microbe in such objects of the external environment which have not yet been subjected to laboratory analysis and serological analysis in particular. Such objects include soil from the burrow and the substrate of the nest of the rodent as well as the fleas of rodents and regurgitations of birds of prey. The effectivity and suitability of examination of these objects using immuno-adsorption reactions with standard erythrocyte diagnostics (passive haemagglutination reaction, antibody neutralization reaction) were demonstrated experimentally and confirmed under field conditions in various geographical and ecological zones of the Caucasus. Thus in 1971, an earlier unknown natural focus of plague was found in the Mount Elbrus massif by means of serological analysis of the substrate of the nest and of the soil from the burrows of rodents. It can be expected that broadened serological search for the FI antigen of plague will prove useful in the study of the structure of natural foci of plague, in the reconnaissance or retrospective investigation of poorly explored territories and in the solution of some questions concerning the epizootiology of plague, such as the survival of the infectious agent in the inter-epizootic period, telluric plague, etc.

Animals↗
PubMedDate not supplied

[Comparative analysis of the morphogenesis of the Getah virus in cell cultures of vertebrates and mosquitoes].

Reproduction of Getah virus (the genus Alphavirus) in piglet kidney (PK) and A. aegypti mosquito cell cultures was studied morphologically. Inoculation of PK cells resulted in the development of a lytic infection. Virus morphogenesis in these cells showed the features known for other alphaviruses. In mosquito cell cultures persistent infection developed which was not accompanied by any marked changes in morphology or proliferative activity of the culture. All the morphological and cytochemical data indicate that a certain role in the establishment and maintenance of virus persistence in A. aegypti cell culture may be played by exo- and endophagocytic processes owing to which a peculiar "self-purification" of the cells from the virus and its components occurs. Incubation of the persistently infected culture of mosquito cells at a suboptimal temperature resulted in a marked reduction in the number of newly formed virions which sharply increased with the shift up to the optimal temperature. The experimental results give some insights into certain aspects of alphavirus ecology.

Acid Phosphatase↗
PubMed1976

Intervention with premature human infants.

Stimulation has been given to young infants to prevent the development disabilities often associated with prematurity. A review of these experimental programs reveals a lack of knowledge as to the ecology of the premature infant. This is indicated in the assumption that premature infants are sensorily deprived and by the arbitrary differences in the nature of stimulation techniques. Despite various problems in methodological and outcome assessment, stimulated infants tend to perform at higher levels than control-group infants on measures of sensorimotor and development. It is suggested that future research should be directed toward specifying the environment and processing capacities of the premature infant, and that intervention studies should make use of the 4-group design proposed by Solomon and Lessac (1968).

Acoustic Stimulation↗