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PubMed2026

Herbicide Resistance Genes in Crops: Mechanisms, Progress, and Future Perspectives.

While previous reviews have largely focused on individual crops or single target-site mechanisms, the full-chain comparative landscape across major cereal crops remains unexplored. Here, we fill this critical gap by providing the first systematic, cross-crop comparative review that spans herbicide targets, resistance mechanisms, and breeding applications across four major cereals-rice, maize, wheat, and sorghum. Weed infestation is a serious constraint on crop production. Chemical weed control faces challenges such as herbicide resistance evolution and ecological risks. Developing herbicide-resistant varieties is a fundamental approach to achieve green and sustainable weed management. This review systematically summarizes research progress on herbicide resistance genes from three aspects: herbicide classification, resistance mechanisms, and crop breeding applications. It highlights key differences among four major cereal crops (rice, maize, wheat, and sorghum) in resistance-gene discovery and translational progress. Rice has the richest target-site resistance-gene resources. Maize leads in commercialization of transgenic herbicide resistance. Wheat focuses on endogenous precise editing due to genome complexity and regulatory constraints. Sorghum relies on specific mutations to serve cereal-legume intercropping systems. Based on this comparison, this review identifies the core trends in resistance breeding: from single-gene to multi-gene stacking, and from exogenous gene introduction to endogenous gene editing. It also points out common bottlenecks, including insufficient systematic mining of resistance-gene resources, lagging elucidation of non-target-site resistance regulatory networks, and strong genotype dependence in genetic transformation. Future efforts should focus on exploring broad-spectrum resistance genes, optimizing precise editing technologies, and developing sustainable resistance management strategies. This review provides a theoretical framework and practical references for molecular breeding of herbicide-resistant crops.

crop breeding↗

PubMedDate not supplied

Documented clinical experiences of primary care RN students: a preliminary report.

A student-patient encounter form was developed for documenting patients' visits in the practicums of three primary care courses--obstetric-gynecology, pediatrics, and general adult patients--and from January 1973 to June 1974, 22 registered nurse students completed 1,027 student-patient encounter forms. Health problems were identified, using the Weed system and classified by the International Classification of Disease adapted for use in the United States. The study demonstrated that the encounter form facilitated the documentation of base-line data for student practicums. Preliminary analysis of the data revealed that: 1) health problems of patients classified as "without sickness" were important in the case loads of registered nurse students in obstetric-gynecologic and pediatric practicums; 2) health problems of patients classified as "symptoms of ill-defined conditions" were also important in all three student practicums, particularly with general adult patients: and 3) students encountered a cluster of health problems in dealing with patients in the three practicums. The study suggested a need to develop a classification scheme for health problems encountered in primary care nursing services.

Chicago↗

PubMed1989

[The value of sonography in the therapeutic supervision of induratio penis plastica (Peyronie's disease)].

The article reports on 18 sonographically examined patients with clinically verified Peyronie's disease (induratio penis plastica) who underwent a basic sonographical classification according to the system of Kelami. Four weeds after the initial sonography a control study was carried out in 17 patients. 10 of these received a treatment by local instillation with Ontosein, whereas seven patients remained without treatment. In one patient an operation (Nesbit) had been performed in the meantime. 10 of the 17 examined patients presented a change of the initial findings. Seven patients out of the number of the patients who had received treatment presented a change, whereas three patients showed no change of their basic findings. The untreated group of seven patients demonstrated in three cases a change of the sonographic pattern, and four cases were unchanged. The most significant change of the sonographic appearance (treated or untreated) was an increased echogenicity of the corpora cavernosa. In some cases no plaques could be found, in one cases a new plaque developed. In two cases the initial hypoechogenic rings sign disappeared. Sonography, however, cannot prove the success of a specific therapeutic regimen, because 50% of all patients recover without treatment.

Adolescent↗

PubMed1990

Epigenesis theory: a mathematical model relating causal concepts of pathogenesis in individuals to disease patterns in populations.

A mathematical modeling approach called epigenesis theory is presented which relates three aspects of pathogenesis to the population distribution of disease. The three aspects of pathogenesis involve how two or more measured variables interact. They are 1) whether the measured variables are related to the same causal action, 2) whether there is only one pathogenic process leading to disease, and 3) whether the measured variables contribute to the same pathogenic process. Epigenesis theory defines the following multivariable relations between two disease causes: 1) "Complementary" causes contribute different causal actions to the sole pathogenic process leading to disease. They have multiplicative relations. 2) "Separate process" causes contribute different causal actions to different pathogenic processes. They have the relations of simple independent action which are slightly less than additive. 3) "Intermediate" causes contribute different causal actions to the same pathogenic process in the presence of additional pathogenic processes where at most one of them may also participate. They have relations somewhere between multiplicative and simple independent actions. 4) "Cooperative-competitive" causes share the same causal action and act within the same pathogenic process. Their relations can change from greater than multiplicative to less than simple independent action at increasing dichotomization points of the measured variables. Epigenesis theory unifies the sufficient-component causes model and the simple independent action model and exceeds either model in the range of observations it can explain. It is most useful given directly causal measured variables and specific disease outcomes, but it will assist in etiologic investigations of nonspecific outcomes in which new disease classifications are proposed. While it is less useful given surveillance-type variables such as age or sex or outcomes resulting from numerous pathogenic processes such as death, it gains utility as more causal variables are entered into an analysis and as more cut points of continuous complementary, independent, or intermediate variables are distinguished.

Adult↗

PubMed1977

Investigation of immunological relationships among myosin light chains and troponin C.

Two classes of myosin light chains can be distinguished functionally: those that restore calcium regulation to "desensitized" scallop myofibrils, and those that do not (Kendrick-Jones, J., et al. (1976), J. Mol. Biol. 104, 747--775). Despite this functional classification, chemical analyses reveal few patterns unique to regulatory light chains, and, indeed, sequence comparisons suggest structural similarities between both classes of myosin subunits (Collins, J. H. (1977), Nature (London) 259, 699--700; Kendrick-Jones, J., and Jakes, R. (1977), in International Symposium on Myocardial Failure at Tegernsee, Riecker, G., and Boehringer, Ed., Munich, West Germany, Springer-Verlag, pp. 28--40). Immunological assays using antisera to regulatory and to nonregulatory light chains showed no correlation between antigenic activity and the presence or absence of regulatory function. Weak cross-reactivity was observed, however, among myosin light chains and troponin C, consistent with the suggestion made on the basis of sequence homologies that these subunits contain similar structural domains (Weeds, A. G., and McLachlan, A. D. (1974), Nature (London) 252, 646--649). Unexpectedly, the strongest cross-reactivity observed was that between the vertebrate myosin alkali 1 and DTNB light chains.

Animals↗