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Results for “environmental variability”

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PubMed1976

A family study of coarctation of the aorta.

Families of 100 patients with coarctation of the aorta and 50 controls for age, sex, and social status were studied to assess the influence of genetic and environmental variables in the aetiology. A tendency to familial aggregation of the condition and other congenital heart defects compatible with multifactorial inheritance was discerned. Recurrence risk for sibs is approximately 1 in 200 for coarctation of the aorta, and 1% for any form of congenital heart defect. The heritability of coarctation is estimated at 58%. The tendency for other non-cardiac defects to occur in the patients with coarctation does not appear in their sibs and is not so pronounced as in some other congenital heart conditions. Of the several environmental variables examined, there was no definitive association with any other than season of birth, which implies a possible association with maternal infection; there is also a suggestion of a paternal age effect, but these require investigation in a prospective survey.

Abnormalities, Multiple↗

PubMed2026

Climate-Driven Niche Tracking and Genomic Resilience Shape Future Distribution of a Widespread Agricultural Weed.

Understanding how agriculturally important species respond to environmental change is critical for maintaining productivity, mitigating agroecosystem threats and sustaining resilience. While crops have traditionally been the focus in agroecosystems, agricultural weeds are integral components that often face even stronger selective pressures, making them powerful models for investigating ecological and evolutionary responses to climatic and human-mediated challenges. Insights from how weeds adapt rapidly under these pressures can inform strategies to improve agricultural outcomes, since both pests and crops evolve under the same multivariate selective pressures. Here, we integrate two centuries of distribution records with whole-genome sequencing from natural populations of the most damaging weed in Europe-Alopecurus myosuroides (blackgrass) - to examine its ecological and evolutionary responses in agroecosystems. Blackgrass largely maintained its historical climatic niche, expanding its range primarily by tracking environments analogous to those it historically occupied. Genome-wide analyses revealed a polygenic basis of environmental responses, with most loci linked to single environmental variables and a subset showing limited environmental pleiotropy, indicating modular adaptation to the complex selective pressures of managed agricultural landscapes. Coupling these genomic-environment relationships with projected climate change and genomic offset analyses indicated that most blackgrass populations will remain well aligned with future conditions. Our findings show that ecological niche tracking and polygenic adaptation allow agricultural weeds like blackgrass to persist under rapid environmental change, offering insights relevant not only for weed management but also for designing resilient cropping systems under future climates.

Plant Weeds↗

PubMed1979

Comparative effects of Aroclor 1254 (polychlorinated biphenyls) and phenanthrene on glucose uptake by freshwater microbial populations.

The effects of polychlorinated biphenyl (PCB) and phenanthrene stress on glucose uptake by natural microbial populations were examined by the heterotrophic potential technique. Temporal and spatial distributions in glucose uptake velocities were examined for natural samples as well as PCB- and phenanthrene-stressed samples. Statistical analysis indicated significant variability among the various samples. It was demonstrated that the environmental variables contributed significantly to the variability in uptake kinetics. Although general trends indicated a PCB-induced stimulation in uptake velocities, these trends were in part masked by sample variability. Data analysis indicated no statistically significant PCB or phenanthrene effect on either total glucose uptake velocities or the proportion of 14CO2 evolved, as compared to natural unstressed samples.

Aroclors↗

PubMed1975

The comparative evolutionary biology of the sibling species, Drosophila melanogaster and D. simulans.

1. D. melanogaster and D. simulans are sibling species; they are morphologically almost identical and genetically very similar. Whereas their sexual behavior patterns are qualitatively similar, hybrids are rarely produced and when they are, they are sterile. 2. Although not all data are in agreement, D. melanogaster generally exhibits more chromosomal, enzyme, and protein polymorphism than does D. simulans. Utilizing this relationship, as well as arguments presented in the literature, one can argue for an association between genetic variability and level of ecological heterogeneity. This association is found for two major environmental variables, temperature and light dependence. 3. On a seasonal basis, D. melanogaster achieves large population numbers early in the summer, as D. simulans does in the autumn...

Animals↗

PubMed1977

Dislodgeable residues of ethion in Florida citrus and relationships to weather variables.

Five different treatments of ethion on Valencia orange trees were compared for decay rates and for ethion monoxon and ethion dioxon production under different environmental conditions. The oxon metabolite levels observed were low and always below the residue level of ethion itself. There were no significant differences in the decay rates of ethion between treatments. A model of ethion decay utilizing environmental variables as a time base is presented. This model explains 94% of the variation observed in ethion decay during very wet and very dry periods in Florida. The application of these results and general experimental approach to worker safety reentry standards is discussed.

Chromatography, Gas↗

PubMed1975

Environmental and lactational variables affecting prolactin concentrations in bovine milk.

Relationships were examined between prolactin concentrations in bovine milk and various environmental and lactational variables. Prolactin was quantified by radioimmunoassay in 1.316 milk samples from two experiments. Environmental temperatures preceding milking, stage of lactation, daily miik yield, and dominance rank of the cow were correlated significantly with milk prolactin concentration. Stepwise multiple regression analysis was used to determine, in order of importance, the variables having significant independent effects on milk prolactin. Ambient temperature extremes, high and low, exerted the greatest effects and were each associated with elevated concentrations of prolactin. In Experiment I,conducted throughout the year, the variable representing maximum temperature preceding milking accounted for 14.3% of the variation in milk prolactin. In Experiment II, conducted during late fall and early winter, the minimum temperature preceding milking accounted for 21.1% of the variation. Although earlier stages of lactation and larger daily milk yields were associated with higher prolactin concentrations, inclusion of lactation stage in the stepwise regression model tended to eliminate almost all the variance of prolactinpreviously associated with daily yield. Dominance measurements indicated that more submissive cows had higher milk prolactin. Individual cows tended to have characteristic prolactin, but this tendency was eliminated by statistical adjustment of the data for environmental and lactational variables.

Animals↗

PubMed2026

Rapid and exceptionally small-scale adaptation of the alpine plant Cardamine resedifolia to mining-contaminated soils in multi-stress condition.

The mechanisms by which plants tolerate soil contamination have been studied in details in controlled laboratory conditions, but they still remain largely unexplored in natural conditions where mixtures of contaminants are present in soils and their effects might interact with other environmental variables. This is especially true in high-altitude alpine environments, where abiotic stress is naturally heightened, but which so far have received little attention in environmental pollution studies. As we were interested in the tolerance mechanisms at play on very fine spatiotemporal scales for alpine plants growing under multi-stress conditions, we chose Cardamine resedifolia as our biological model. This plant is indeed frequently found in areas contaminated by Trace Metals and Metalloids and Polycyclic Aromatic Hydrocarbons in high elevation. We studied populations from former copper, silver-lead, and coal mines in alpine environments, along with populations growing on nearby reference soils. We measured genetic variability within populations as well as genetic differentiation between them, and tested for local adaptation to soil contamination using reciprocal transplants. Population pairs showing signs of local adaptation were then examined using genome scans to identify genes potentially under selection. We found high levels of genetic differentiation between populations growing on contaminated and reference soils a few dozen meters apart. In most cases local adaptation was detected, especially in former copper mines. Genome scans identified genes involved in metal stress management as potentially being under selection. This study provides evidence for rapid adaptation to human-induced pollution in alpine plants at remarkably small spatial scales. It offers new insights into the short-term ecological and evolutionary consequences of mining activities in alpine ecosystems, particularly in relation to substrate-driven differentiation.

Alpine plants↗

PubMedDate not supplied

State-dependent peculiarities of cocaine-induced behavioral sensitization and their possible reasons.

To study determinants and possible reasons of cocaine-induced behavioral sensitization, locomotor effects of the drug (COC, 15 mg/kg, IP; 5 daily injections followed by a "challenge," four days later) and various stimuli associated (procedure of injection, placement in the test cage) and nonassociated (tail-pinch) with its administration were measured in rats under different experimental conditions. When COC was injected in quite conditions, two hours after animal habituation to the test cages, locomotor response to the first drug injection was only slightly higher compared to one of saline and these responses were relatively stable following repeated treatment (no sensitization). An enhanced locomotor response to the procedure of injection (needle prick) without changes in responsivity to other stimuli used were found in these COC-treated rats. When COC was injected in activated conditions (animal placement in test cages), locomotor response to the first drug administration was significantly higher compared to one of saline and COC used in the quiet state and it was enhanced following repeated treatment (sensitization). More intense locomotion associated with placement in test cages without any changes in responses to other stimuli was found in rats after this procedure of treatment. Thus, locomotor effects of COC and dynamics of its changes following repeated treatment depend upon the organism's functional state accompanying the drug's effect. Reinforcing action of COC determining development of interinfluence of its effects and ones triggered by environmental variables (learning based on conditioning) is considered as a proposed initial cause and a main mechanism both for enhanced reactivity to cocaine administered under conditions of its previous use and to various environmental events associated with previous cocaine effects.

Animals↗

PubMed1979

Familial aggregation of blood pressure and weight in adoptive families. II. Estimation of the relative contributions of genetic and common environmental factors to blood pressure correlations between family members.

An analysis of the familial aggregation of blood pressure (BP) was conducted to provide estimates of the role of genes and household environment in determining the phenotypic resemblance between biologically related family members. The biological model used for this analysis parameterizes the correlations between family members into the contributions of genetic and environmental variability shared within and across generations. Hypothesis testing about different parameters in the model suggests that shared environment explains larger fractions of the parent-natural child and the full sib correlations for diastolic BP than for systolic BP. For diastolic BP, children in a household share the effects of common environment in addition to the effects which they share with their parents. Dependence of the degree of resemblance between household members on the effects of environmental factors shared within and a-ross generations is not explained by the variability of length of cohabitation among individuals.

Adolescent↗

PubMed2026

Phylogenetic Constraints and Environmental Filtering Jointly Drive Adaptive Evolution in Phragmites australis: From Genetic Structure to Trait Decoupling on the Mongolian Plateau.

The Mongolian Plateau, a typical arid and semi-arid zone in Eurasia, is characterized by highly heterogeneous and fragmented wetland habitats. Phragmites australis, a common wetland species in this region, exhibits remarkable adaptability. Unraveling the coordination between phylogenetic history and local environmental filtering is crucial for elucidating its adaptive mechanisms. Integrating landscape genomics and trait-based phylogenetic analyses, we analyzed transcriptome-wide SNPs, multidimensional functional traits, and environmental variables across 90 individuals from 30 natural P. australis populations. This study aims to reveal the genetic and phenotypic variation patterns underlying population genetic structure and trait variation, specifically distinguishing the roles of geographic isolation, environmental filtering, and phylogenetic history. Results reveal a significant drainage-dependent pattern in genetic structure. Populations in hydrologically connected basins show extensive admixture, whereas those in isolated endorheic basins form distinct lineages. While geographic isolation underpins genetic differentiation, environmental filtering independently explains ~33.84% of the genetic variation, driven primarily by moisture heterogeneity (precipitation seasonality and soil moisture). Crucially, we observed differentiated evolutionary trajectories across functional traits. Structural traits (e.g., plant height, leaf thickness) are phylogenetically conserved; in contrast, physiological traits (e.g., water use efficiency) are decoupled from phylogeny, showing patterns consistent with high plasticity regulated by local environments. This evolutionary decoupling strategy enables P. australis to flexibly adapt to heterogeneous habitats while maintaining structural stability. This study uncovers the synergistic mechanisms by which geographic isolation and environmental filtering jointly shape the genetic patterns of this cosmopolitan species at a regional scale, clarifies that its evolutionary responses may depend heavily on the differentiated plasticity of trait types, and provides valuable regional insights into how widespread wetland species adapt to heterogeneous environments under global change.

Mongolia Plateau↗

PubMed1979

The physiological effects of restrictive environmental conditions on Dictyostelium discoideum spore germination.

Spores may be reversibly activated by the application of heat, dimethyl sulfoxide, urea, or ethylene glucol. Severe changes in four environmental variables (high osmotic pressure, low oxygen tension, low or high pH, and low or high temperature) interfere with the germination process. Spores at the end of the postactivation lag phase of germination were usually deactivated if exposed to severe environmental conditions and thus did not swell; spores in the swelling and oxygen uptake which began during spore activation was primarily attributable to a cyanide-sensitive pathway and secondarily to a salicylhydroxamic acid (SHAM) sensitive pathway. Inhibition of the SHAM-sensitive pathway did not cause spore deactivation while the addition of cyanide resulted in rapid spore deactivation. Treatment of activated spores with azide or environmental shifts also resulted in inhibition of oxygen uptake and spore deactivation. Deactivating spores did not demonstrate the amino acid incorporation, uridine incorporation, and expression of trehalase activity which is found in the later stages of germinating control spores. Protein synthesis inhibitors did not cause spore deactivation or a decrease in oxygen uptake but they inhibited amino acid incorporation and the expression trehalase activity in swollen spores. It is concluded that control of respiratory activity is involved in regulation of reversible activation.

Azides↗

PubMed1975

Cancer of the colon: socioeconomic variables in a community.

Carcinoma of the colon was studied in Omaha-Douglas County, Nebraska (population 345,000). A total of 154 cases of colon cancer were diagnosed in 1964 (44.7/100,000). The frequency distribution of these patients in specific census tracts of this community was determined. Statistical analysis of the data showed a greater frequency of colon cancer in patients living in census tracts with higher average income. Colon cancer appears to be nonrandomly distributed with respect to the income and socioeconomic status of its victims, suggesting that hypotheses consistent with environmental variables--particularly those characterizing extremely high versus extremely low socioeconomic groups, including occupation, diet and other life patterns--should be pursued. All of these data have implications for cancer epidemiology, cancer control, and carcinogenesis.

Adult↗

PubMed1976

Plasma protein variability in MZ twins.

A previous study had shown that only MZ twins are easily exchanged by trained police dogs. This is certainly due to the superimposability of the biochemical basis of body scent. A different approach has now been tried, based on plasma protein fractionating procedures. A pilot study has shown that PolyAcrilamide Gel Electrophoresis (PAGE) results, as expected, in widely different patterns only in DZ twin pairs. Plasma specimens from a sample of 55 supposedly MZ twin pairs were analysed by PAGE. The substantial superimposability of MZ cotwin patterns was confirmed. Analysis of the different fractions indicates the extent of environmental variability. Application to zygosity determination is suggested.

Blood Proteins↗

PubMed1978

Activities of types A and B MAO and catechol-o-methyltransferase in blood cells and skin fibroblasts of normal and chronic schizophrenic subjects.

We assayed activities of monoamine oxidase (MAO) type B in blood platelets and type A (and B) in fibroblasts cultured from punch biopsy specimens of skin, as well as of catechol-O-methyltransferase (COMT) in erythrocytes and fibroblasts. Fibroblasts contained moderate amounts of both forms of MAO (types A and B) found in human brain and large amounts of COMT activity. Activities of both enzymes correlated poorly between fibroblasts and blood cells. Comparing carefully diagnosed chronic schizophrenics with age-matched normal young men, we found no difference in these biochemical variables, nor could we distinguish patients with paranoid symptoms. In contrast, we confirmed markedly lower MAO activities in platelet samples from chronic patients provided by colleagues at the National Institute of Mental Health. Results concerning MAO and COMT activities are now sufficiently inconsistently characteristic of schizophrenics as to question their clinical applicability and to indicate a need for further critical evaluation, with special attention to diagnosis, matching of subjects, and effects of possible spurious environmental variables.

Adolescent↗

PubMed2026

Metagenomics Reveals Microbial Community Shifts Associated With Contrasting Anthropogenic Impacts in Freshwater Sources of A Coastal Protected Area in Southeastern Brazil.

This study aimed to characterize freshwater microbial communities, environmental drivers, and anthropogenic impact patterns across three sites on Marambaia Island (southeastern Brazil) using metagenomics. Samples collected from freshwater sources used for human consumption were processed through concentration, nucleic acid extraction, and sequencing on the Illumina NextSeq 2000 platform. A total of 67.2 million reads were assembled into 89,230 bacterial contigs, mostly attributed to Gammaproteobacteria, Alphaproteobacteria, and Betaproteobacteria. Sites under lower anthropogenic influence exhibited higher microbial diversity, whereas impacted sites showed enrichment of opportunistic and fecal-associated genera. A heterogeneous anthropogenic impact profile was observed across sites, corroborated by the proposed Anthropogenic Impact Index (AII). Fourteen antimicrobial resistance genes conferring resistance to beta-lactams, quinolones, sulfonamides, tetracyclines, and macrolides were detected predominantly in sewage-impacted areas, indicating potential diffuse contamination. Redundancy analysis revealed that environmental variables explained 88.1% of microbial community variation, with conductivity, salinity, and turbidity as key drivers. These findings demonstrate the applicability of metagenomics as a powerful tool for assessing microbial diversity, ecological dynamics, and contamination risks in vulnerable freshwater systems.

Brazil↗

PubMed1978

Ecology and health.

Health is commonly conceived as having fixed and universal aims, while conditions interposed by environmental and cultural conditions are often ignored or at least shunted to one side. Rejecting this point of view, the author asserts that health in any society should be defined in terms of ecological reality--that is, in terms of the cultural and environmental variables affecting the population. He also notes that acceptance of this concept does not imply perpetuation of a natural but static situation. Rather, it implies searching for ways to improve the situation without necessarily striving for international goals that may be unsuitable or impossible to achieve. The concept also implies that we should ask how to define a satisfactory health level for a given set of conditions--and then consider how to achieve that level. The search for answers to these questions and subsequent programs based on the results will require a multidisciplinary approach. Within this context two PAHO facilities, the Pan American Center for Human Ecology and Health (ECO) and the Pan American Center and Engineering and Environmental Sciences (CEPIS), can provide strong support for activities in the Americas. Specifically, ECO is in a good position to collaborate on ecological planning, model-building, and research evaluation, while CEPIS is geared to provide advice and assistance in the key field of environmental sanitation.

Cultural Characteristics↗

PubMed2026

A marine-derived fungal genome of Annulohypoxylon annulatoides reveals AT-rich isochores with putative regulatory functions.

Marine and coastal fungi experience intense environmental variability, yet the genomic features associated with tolerance to such conditions remain unclear. From 56 fungal isolates collected along the Lailai rocky shore in northern Taiwan, we selected the coastal isolate Annulohypoxylon annulatoides RYS0019 for phenotypic and genomic investigation because of its prevalence and distinctive stress-response profile. Compared with 5 bark-derived conspecific strains, RYS0019 showed distinct growth and recovery dynamics under salinity, temperature, and UV-associated stress treatments. We generated a high-quality 41.8 Mb de novo genome assembly with 11,523 predicted proteins and compared it with 15 other Hypoxylaceae genomes. Across Annulohypoxylon genomes, we identified variably sized and dispersed AT-rich isochores that are repeat-enriched and gene-poor. Despite variation in AT content, core gene content and Pfam domain profiles remained broadly conserved. Most AT-rich isochores were embedded within syntenically conserved regions and showed limited positional conservation across species, supporting recurrent, lineage-specific formation or expansion after species divergence. These regions also exhibit several sequence and structural features consistent with scaffold/matrix attachment regions, raising the possibility that they influence higher-order genome organization or context-dependent regulation. Together, our findings identify repeat-rich genome architecture as a dynamic feature of Annulohypoxylon genome evolution and provide a framework for testing how such regions may contribute to fungal environmental flexibility.

Genome, Fungal↗

PubMed2026

Multi-omics reveal microbial functional traits and antifungal metabolites associated with lower Pseudogymnoascus destructans loads in bat cave soils.

White-nose syndrome, caused by Pseudogymnoascus destructans (Pd), is a major fungal disease threatening hibernating bats. Cave soils can serve as environmental reservoirs for Pd, yet the microbial and biochemical mechanisms underlying naturally low Pd burdens in some cave environments remain poorly understood. Here, we integrated soil microbiome profiling, metagenomics, metabolomics, multi-omics network analysis, and in vitro validation to investigate the ecological and functional basis of differential Pd loads in hibernating bat caves in Northeast China. The three caves shared cold, humid, and weakly acidic microenvironments, but differed significantly in electrical conductivity, soil water content, nutrient availability, and extracellular enzyme activities. Soil microbial communities showed significant inter-cave variation in composition, diversity, and niche breadth, with stochastic processes contributing substantially to community assembly. Environmental variables, particularly pH and Pd load, were important predictors of microbial community structure. Functional analyses revealed that the low-Pd Gezi Cave was enriched in genes associated with organic carbon degradation, nitrogen input and retention, and secondary metabolism. Metabolomic profiling further identified cave-specific metabolite signatures, among which Biochanin A, 4-Hydroxybenzaldehyde, Vanillin, and Arachidonic acid were negatively correlated with Pd loads. Integrated pathway and network analyses showed that differential genes and metabolites jointly mapped to secondary metabolite biosynthesis, aminobenzoate degradation, and flavonoid degradation pathways, forming a microbe-metabolite-functional gene coupling network involving key taxa such as Rhodococcus, Pseudorhodoplanes, and Rhodoplanes. In vitro assays confirmed that 4-Hydroxybenzaldehyde, Coumarin, and Vanillin inhibited Pd growth. Structural equation modelling further indicated that environmental heterogeneity was associated with variation in Pd loads through microbial functional attributes and metabolite profiles. These findings suggest that naturally low-Pd cave soils are associated with coordinated environmental filtering, microbial functional specialization, and antifungal metabolite production, providing mechanistic insight into microbial and biochemical constraints on Pd persistence in cave reservoirs.

Animals↗