Discovering Genes That Cause Disease
Kenneth L. Brigham in Gene Therapy for Diseases of the Lung, 2020
So are such efforts doomed? In the spirit of recent experience, apparently insurmountable obstacles are still likely to yield to advancing genome technology. For the case of common diseases, the solution will likely be found in one of three approaches: (1) Identification of a prevalent predisposing haplotype (linkage disequilibrium) in a genetically homogeneous population. The recent use of this strategy to clone the gene for diastrophic dysplasia in Finland (21) lends strong support to the concept that such populations allow tracking of a much more refined predisposing region. Counting on such linkage disequilibrium to come to the rescue in a more outbred population may be risky, however. (2) Identification of a syntenic animal model. Animal models of human disease may not necessarily reflect the same predisposing loci, of course; but if genetic linkage analysis indicates that a small syntenic region is contributing relative risk in animals and humans, shifting the analysis to the animal species will be a highly attractive option. The ability to perform selective cross-breeding allows much more precise mapping of a polygene in animal experiments than in humans. (3) If all else fails, the availability of a highly dense transcript map (reducing the hunt for candidate genes to a computer exercise), coupled with powerful methods to search for sequence variation over large numbers of candidate DNA segments (where DNA chip hybridization (22) may greatly speed throughput), may still prevail.
Classification and Systematics
Jacques Derek Charlwood in The Ecology of Malaria Vectors, 2019
Interbreeding between populations that have ecologically diverged, by either niche specialisation or invasion of a new niche (such as the water bodies created during rice cultivation), produces hybrid individuals of lower fitness in each of the parental habitats. Ecological speciation theory predicts that reproductive isolation is environment-dependent; in other words, it is driven by ecological selective forces such as resource competition or predation. The strength of reproductive isolation is correlated with the degree of ecological divergence, rather than time since lineage splitting. Thus, the separation of, say, optimal breeding sites may result in ecological speciation. Although the incipient species may for many aspects occupy the same geographical space and the same niche (i.e., they are sympatric), at certain points they must be separated (i.e., they are allopatric). Not all available habitats may be occupied at any one time. Populations, particularly at the margins of the mosquitoes’ distribution, may become locally extinct leaving the habitat unoccupied until it is recolonised. In other words, they are likely to form a metapopulation.
Institutional Approaches to Healthful Eating
Emily Crews Splane, Neil E. Rowland, Anaya Mitra in Psychology of Eating, 2019
The end of the 1960s is now referred to as the beginning of the “Green Revolution.” The Green Revolution resulted in global increases in crop production and was the result of significant advances in agricultural production techniques, including the development of high-yield varieties of crops which had a shorter time to maturity (Pingali, 2012). These high-yielding varieties were developed by cross-breeding different strains of the same crop so that the next generation of crops had specific desirable traits (e.g., rust-resistance and dwarfism in wheat crops). These cross-bred strains were used in conjunction with higher quality fertilizers and pesticides, better irrigation methods, and increased mechanization of the harvesting process (Borlaug, 1970). Had it not been for these agricultural innovations, the 1960s and 1970s would have been characterized by mass famines in many parts of the developing world. Dr. Norman Borlaug (1914–2009) is credited as being the Father of the Green Revolution; estimates say that the high-yielding, disease-resistant varieties of wheat and rice he was involved in creating may have saved more than one billion human lives from hunger. For this work he was awarded the Nobel Peace Prize in 1970. Despite his scientific and humanitarian contributions to the world, his work was considered controversial by some as it involved cross-breeding to produce desirable traits in the offspring. This may be considered a precursor to the more modern (and targeted) technology of genetic modification of plants and animals.
Induced variability and assessment of mutagenic effectiveness and efficiency in sorghum genotypes [Sorghum bicolor (L.) Moench]
Published in International Journal of Radiation Biology, 2022
H. V. Kalpande, S. M. Surashe, Ashok Badigannavar, Ambika More, T. R. Ganapathi
Induced genetic variability for qualitative and quantitative traits is of prime concern for the breeder to develop high yielding varieties with wider adaptability. Among the cereals, sorghum being the dual purpose and drought tolerant crop, it can be genetically modified by the range of mutagens in bringing heritable changes. The present study revealed wide genetic variability and better effectiveness and efficiency for physical (300 Gy) and chemical mutagens (0.2%) and their combination (200 Gy + 0.2%) across sorghum genotypes. Significant correlations identified between quantitative traits will help in selection process. Various viable and high yielding mutants isolated from this study would lead to the development of varieties and unique mutants may be used as germplasm resources in the cross breeding programs.
To mix or not to mix? A rapid systematic review of heterologous prime–boost covid-19 vaccination
Published in Expert Review of Vaccines, 2021
Nan-Chang Chiu, Hsin Chi, Yu-Kang Tu, Ya-Ning Huang, Yu-Lin Tai, Shun-Long Weng, Lung Chang, Daniel Tsung-Ning Huang, Fu-Yuan Huang, Chien-Yu Lin
In contrast, adenovirus-vectored vaccines elicit lower neutralizing and binding antibody levels but produce polyclonal antibodies after vaccination [36]. Protective immunity may be achieved by mediating other antibody-dependent effector mechanisms, including antibody-dependent complement deposition and monocyte-mediated and neutrophil-mediated phagocytosis [33]. Furthermore, potent T cell responses with the production of TNF and IFNγ from CD4 + T cells peaked at 14 days after a single dose of ChAd vaccine. These observations indicate that vaccines produced using different platforms elicit vaccine protection through different pathways. Thus, heterologous vaccination may elicit the immunological benefits of both platforms; similar to what occurs in infected people who receive a vaccination after recovery. Postinfection serum-neutralizing capacity is elevated approximately 1000-fold in convalescent individuals who receive mRNA vaccines, and the interaction of natural immunity and vaccine-generated immunity elicits more robust protection [37,38]. The concept of ‘hybrid vigor immunity’ is derived from plants [39]. When different plant lines breed together, the hybrid line produces a stronger plant. The benefits of heterologous vaccination may be attributed to similar interactions between different immune-mediated pathways, and our review provides more clinical evidence of these benefits.
Assessment of natural variability in leaf morphological and physiological traits in maize inbreds and their related hybrids during early vegetative growth
Published in Egyptian Journal of Basic and Applied Sciences, 2019
Farag Ibraheem, Eman M. El-Ghareeb
Six maize genotypes were used in the current study. These genotypes included the two famous USA inbred lines (B73 and Mo17) and two Egyptian inbred lines (Sids7 and Sids63) along with two of their corresponding single cross hybrids (B73 × Mo17 and Sids7 × Sids63). These inbred lines were selected because of their importance in breeding and genome sequencing programs. B73 and Mo17 are elite US maize inbreds that have been used to develop high yielding B73 × Mo17 hybrid. In addition, they were used as parents of the famous IBMRIL (Intermate B73 × Mo17 Recombinant Inbred Lines) population which is one of the principal biological materials for gene discovery via quantitative trait loci (QTL) approach [34,35]. Further, B73 was selected for the maize genome sequencing project [36]. Moreover, B73 and Mo17 are the ancestors of many modern commercial inbreds [37]. On the other hand, Sids7 and Sids63 are Egyptian inbred lines that were used to develop Sids7 × Sids63 which is one of the high-yielding local maize hybrids and known locally as SC10 [38–40]. The two hybrids were selected because of their high heterotic responses and their intensive commercial use in the USA and in Egypt, respectively. Enough inbred and hybrid seeds were produced by selfing and crossing the selected inbreds respectively.
Related Knowledge Centers
- Chimera
- Heterosis
- Reproductive Isolation
- Sexual Reproduction
- Blending Inheritance
- Genetics
- Chromosome
- Species
- Fertilisation
- Hybrid Speciation