SEARCH · Search PubMed

Results for “mutualism breakdown”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

8 recordsLinked to original sources

PubMed2026

Concurrent ecological and evolutionary processes contribute to mutualism breakdown between legumes and rhizobia.

Though they jointly shape community responses to environmental perturbations, ecology and evolution are often examined separately, even in microorganisms where both occur over short timescales. Here we examine ecological and evolutionary responses to 33 years of nitrogen fertilization using the legume-rhizobium mutualism. Pairing a manipulative inoculation study with full-length 16S rRNA gene amplicon sequencing and structural equation modeling allows us to synthesize across biological scales: whole bacterial community, genus Rhizobium, Rhizobium ASVs, and symbiosis plasmids. Clover's preferred partner decreases in N-addition soils, limiting host growth, while a diverse and largely uncharacterized Rhizobium community increases. This ecological change is compounded by a concurrent evolutionary degradation of symbiont partner quality via changing frequencies of symbiotic plasmids. Ecological (rarer symbionts) and evolutionary (inferior symbionts) processes each accounted for roughly half of this loss of host benefit, revealing that ecology and evolution jointly shape mutualism breakdown over the short timescales typical of microbial systems.

ecology↗

PubMed1978

Studies on xylan hydrolases from different strains of Streptomyces and their mutual influences in the breakdown of xylan.

A good proportion of Sreptomyces isolates from natural sources produced extracellular xylan hydrolase. Nineteen isolated showing high activity were able to completely or partially degrade wheat bran in the growth medium. Chromatographic analysis of commercial xylan degradation products suggested that the isolates produced either endo- or exo-xylan hydrolases or their mixtures. Mixed additions of culture fluids showed a highly synergistic effect, up to an increase by 200%. In a few cases antagonism was seen which, however, could be removed by dialysis of the culture fluid.

Glycoside Hydrolases↗

PubMed1978

Behavioral contracting in a burn care facility: a strategy for patient participation.

Behavioral contracting is a valuable tool for resolving persistent behavioral problems interfering with the treatment and recovery of severely burned patients. Coercive bidding of the patients for more control occurs in an environment where they experience extreme forms of loss of control and associated enforced regression. The ensuing conflicts between patient and staff often lead to breakdown in mutual cooperation, with deleterious effects on patient-staff morale. Staff experience highly ambivalent feelings toward a problem patient and may wish to withdraw from him, feeling threatened in their image of themselves as competent professionals. Beyond reducing disruptive conflicts on the ward, behavioral contracting aims to mobilize patient and staff around common and explicit goals, and to maximize patient cooperation and productive control in the recovery process. Contracts are valuable because: 1) they facilitate productive communication about issues which underlie patient-staff conflict; 2) they facilitate solutions to problem interactions between patients and staff; 3) they afford both patients and staff a sense or self-control. We provide a rationale for behavioral contracting and discuss the indications for initiating contracts with hospitalized burn patients, and describe methods for developing, implementing, and managing behavioral contracts in order to improve communication and effectiveness in patient-staff interactions.

Adolescent↗

PubMed1976

The cohesiveness of alcoholism-complicated marriages and its influence on treatment outcome.

One-hundred husbands, diagnosed as suffering from alcoholism, and their wives, were followed up twelve months after initial consultation and assessment. Follow-up information was complete in 89 cases. On the basis of both husband and wife accounts of the husband's drinking behaviour during the follow-up period, and their assessment of the drinking problem at twelve-months follow-up, 28 were classified as having a 'good' outcome and 29 as having a 'bad' outcome. In the remaining 32 cases outcome was considered 'equivocal'. A composite measure of marital cohesion was predictive of twelve-month outcome classification, cohesive marriages being significantly more likely to have a good outcome. The measure of marital cohesion was based upon husband and wife reports of mutual affection and of husband involvement in family tasks, favourable spouse perceptions and meta-perceptions, and optimism about the future of the marriage. Composite measures of dominance balance within the marriage were not predictive of outcome. Husband's job status, husband's self-esteem, and wife's reported hardship were not independent of marital cohesion, and were themseleves predictive of twelve-months outcome. When these variables were partially controlled it was found that marital cohesion remained predictive for husbands with relatively low status jobs and husbands with relatively low levels of self-esteem. It is an over-simplification to state that either the marriage, the spouse, or the severity of the patient's condition is alone the cause of variation in outcome. It is possible to integrate these findings with those of other studies on the influence of family variables on the outcom of conditions other than alcoholism. Together these studies suggest a general hypothesis linking a breakdown in the cohesiveness, or mutual rewardingness, of family relationships and unfavourable outcomes following treatment or consultation for psychological disorder.

Adult↗

PubMed1977

Convergence of rod and cone signals in the cat's retina.

1. In an attempt to understand the convergence of rod and cone signals in the cat's retina, ganglion cells that received inputs from both rods and cones were stimulated using lights chosen to excite one or other receptor system or both together.2. If a mesopic background was chosen to allow the ganglion cell to be excited by a blue-green test flash primarily through rods and a deep red flash primarily through cones, one light could not be alternated with the other without eliciting a response from the cell.3. This appears to be a result of the different temporal properties of the scotopic and photopic systems. On the mesopic background responses to blue-green test flashes were transient. Responses to red test flashes arose with similar latency, but were more sustained.4. Rod and cone systems responded with similar latencies in the presence of the mesopic background that substantially light-adapted the rod system but left the full sensitivity of the cone system undiminished. When equivalently light-adapted, the cone system was faster.5. When brief flashes that acted through rods were presented with flashes that acted through cones the ganglion cell's response was the sum of the responses to the two flashes presented separately, as long as the flashes were weak. This linear relation ceased to hold when flashes were strong, but the breakdown appears not to be the result of mutual inhibition between rod and cone signals.6. When a background light excited both rod and cone systems it appeared to reduce sensitivity independently in each.7. The scotopic and photopic receptive fields of a given ganglion cell always were of the same type, on- or off-centre, and, within the limits of measurement, the central regions of the receptive fields were concentric and both the same size.

Action Potentials↗

PubMed2016

Genomic heterozygosity and hybrid breakdown in cotton (Gossypium): different traits, different effects.

BACKGROUND: Hybrid breakdown has been well documented in various species. Relationships between genomic heterozygosity and traits-fitness have been extensively explored especially in the natural populations. But correlations between genomic heterozygosity and vegetative and reproductive traits in cotton interspecific populations have not been studied. In the current study, two reciprocal F2 populations were developed using Gossypium hirsutum cv. Emian 22 and G. barbadense acc. 3-79 as parents to study hybrid breakdown in cotton. A total of 125 simple sequence repeat (SSR) markers were used to genotype the two F2 interspecific populations. RESULTS: To guarantee mutual independence among the genotyped markers, the 125 SSR markers were checked by the linkage disequilibrium analysis. To our knowledge, this is a novel approach to evaluate the individual genomic heterozygosity. After marker checking, 83 common loci were used to assess the extent of genomic heterozygosity. Hybrid breakdown was found extensively in the two interspecific F2 populations particularly on the reproductive traits because of the infertility and the bare seeds. And then, the relationships between the genomic heterozygosity and the vegetative reproductive traits were investigated. The only relationships between hybrid breakdown and heterozygosity were observed in the (Emian22 × 3-79) F2 population for seed index (SI) and boll number per plant (BN). The maternal cytoplasmic environment may have a significant effect on genomic heterozygosity and on correlations between heterozygosity and reproductive traits. CONCLUSIONS: A novel approach was used to evaluate genomic heterozygosity in cotton; and hybrid breakdown was observed in reproductive traits in cotton. These findings may offer new insight into hybrid breakdown in allotetraploid cotton interspecific hybrids, and may be useful for the development of interspecific hybrids for cotton genetic improvement.

Chromosomes, Plant↗

PubMedDate not supplied

Presidential Address-1976. Social support as a moderator of life stress.

Social support is defined as information leading the subject to believe that he is cared for and loved, esteemed, and a member of a network of mutual obligations. The evidence that supportive interactions among people are protective against the health consequences of life stress is reviewed. It appears that social support can protect people in crisis from a wide variety of pathological states: from low birth weight to death, from arthritis through tuberculosis to depression, alcoholism, and the social breakdown syndrome. Furthermore, social support may reduce the amount of medication required, accelerate recovery, and facilitate compliance with prescribed medical regimens.

Affective Symptoms↗

PubMed1979

The consciously rejected child: legal and social issues.

With increasing frequency, we are observing the phenomenon of the parentally abandoned or rejected child. This can in large measure be attributed to several social/historical developments in American society (Crandall and Grossberg, 1978). Important factors contributing to the phenomenon include the much publicized "breakdown" of traditional family structures; increasing divorce rates; the urbanization of the American population, which creates a cloak of social anonymity; and the establishment of a state/federal welfare bureaucracy, which in part supplants the caretaking functions traditionally carried out by parents. Children who become the victims of parental abandonment find themselves in circumstances in which they come to the attention of an remain, at least for a time, the responsiblity of the legal system and the mental health professions. The interaction of these two institutions, with their overlapping obligations of responsibility toward protecting children, often creates its own problems. Problems arise in part from the somewhat different "interests" of children whom the legal and mental health professions seek to protect and in part from a lack of mutual understanding and knowledge concerning the respective goals, duties, and professional obligations of the two professions. By becoming familiar with the complexity of legal issues which surround the topic of intrafamily relationships in general and parental rights in particular, the psychiatric practitioner can anticipate certain problems which might occur during the course of treatment and can in some instances specify conditions or introduce safeguards in order to minimize the impact of legal intrusions upon the treatment program. The following discussion is designed to help the practitioner to achieve these goals.

Child↗