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Some Case Histories
Published in Jacques Derek Charlwood, The Ecology of Malaria Vectors, 2019
Major demographic events leave genetic signatures that could be used to gain important information about the impact of vector control interventions. Using microsatellite data, there was significant differentiation in the genetic structure of the two islands, but there was no evidence of any genetic bottleneck occurring as a result of the eradication campaign undertaken in the early 1980s. In a subsequent study, significant population differentiation revealed by the Fixation index (FST) and the analogous estimator for microsatellite data RST was found between the southernmost collection site, Porto Alegre, and northern localities. The Porto Alegre population was an ‘island within an island’. The observed patterns of population substructure are probably the result of restrictions to gene flow in the less inhabited, more densely forested and mountainous south. In all localities, the A. coluzzii appeared to be experiencing a demographic expansion consistent with a relatively recent (ca. 500 years) founder effect.
Synthetic Biology
Published in Tina Stevens, Stuart Newman, Biotech Juggernaut, 2019
The report explicitly acknowledged the cautionary history of early genetic engineering: “there has been unexpected gene flow from both approved and experimental GM crops into conventional food, sometimes leading affected farmers to have to dispose of ‘contaminated’ crops at great expense.” It also recalled lessons to be learned from the 1980s food crisis triggered by the unanticipated “mad cow disease” (bovine spongiform encephalopathy) (Lloyd’s, 2009). In a particularly well-targeted critique, it noted that, we are far from understanding how genomes work . . . The danger is that we take action based on our understanding now to find later that there were unintended and unimagined consequences. It is possible that two or more benign strands of DNA will interact so that the risk is far greater than the sum of the parts.(Lloyd’s, 2009)
The Impacts of Modern Agriculture on Plant Genetic Diversity
Published in Bill Pritchard, Rodomiro Ortiz, Meera Shekar, Routledge Handbook of Food and Nutrition Security, 2016
Yet, genetically modified crops have been at the center of debates for many years and from multiple viewpoints. Some worries relate to the unexpected consequences of the interaction of the modified trait with other species in the ecosystem – more specifically there is concern for the likelihood of gene flow and introgression from genetically modified crops to the same crops (non-engineered cultivars) and their wild relatives, thus jeopardizing plant genetic diversity. This concern misses the fact that the permanent insertion of genetic material into the receiving plant is not an automatic event; on the contrary it depends on the reproduction system, the viability and fitness of the offspring and the nature of the gene (Andersson and de Vicente 2009). Nonetheless, if hybridization occurred, it could increase or decrease the genetic diversity of the receiving population (Gepts and Papa 2003) – a relevant situation if landrace or wild populations were small, as is the case in centers of crop origin and diversity. But this would also happen if the origin of the trait were a cultivar bred with traditional methods. A similar conclusion applies to the argument that crops genetically modified with a resistant gene questionably maximize the risk of pests and diseases to surpass plant defense mechanisms, making crops continuously vulnerable. It also applies to the reasoning that genetically modified crops pose a threat to the subsistence of crop genetic diversity because they embody the characteristic genetic monocultures of Western agriculture and the concerns over the ownership of seed technologies that prevents farmers from saving and reusing seeds.
Stress memory in two generations of Plantago major from radioactive and chemical contaminated areas after the cessation of exposure
Published in International Journal of Radiation Biology, 2023
Nadezhda S. Shimalina, Vera N. Pozolotina, Natalya A. Orekhova
The development of short roots can be considered as plants’ adaptive trait to the HM-contaminated area. This trait was probably fixed in the population by the selection of resistant genotypes and persisted for three generations after the removal of toxic stress. The assumption of this selection is supported by the decrease in genetic diversity that we observed in P. major populations from the zone of influence of the KCS (Shimalina et al. 2020). It was shown by the case of Lychnis flos-cuculi that loss of genetic variability and high differentiation of plant populations under conditions of TM contamination of soils is associated with a founder or bottle-neck effect during recolonization of heavily contaminated areas or elimination of a significant part of populations under toxic load (Dulya and Mikryukov 2016). Interactions between selection, gene flow, and genetic drift can lead to local adaptation, a mechanism that helps maintain adaptive variability in cenopopopulations (Meyer et al. 2010).
Group-specific component exon 11 haplotypes (D432E and T436K) and risk of albuminuria in type 2 diabetes mellitus patients
Published in Archives of Physiology and Biochemistry, 2022
Manal S. Fawzy, Eman A. Toraih, Essam Al Ageeli, Abeer M. Mohamed, Baraah T. Abu AlSel, Shahad W. Kattan, Walla Alelwani
This study was designed to explore the associations of two common GC polymorphisms, rs7041 and rs4588, with T2DM and DN susceptibility in a sample of Saudi population. We observed that rs4588*A allele and genotypes were associated with T2DM susceptibility and DN. Moreover, despite rs7041*T allele not conferred a risk to T2DM in the study population, it was significantly associated with DN in which macroalbuminuria patients’ group showed the highest and the normoalbuminuria group showed the lowest TT genotype frequency. However, rs7041 genotype frequencies in our cases were different from those we would expect under equilibrium. Therefore, we can assume that one or more of the HWE model’s assumptions are being violated. For example, the relatively small sample size of the current study, which could raise the possibility of genetic drift, gene flow between several populations reside in the local region and the nonrandom mating due to high percentage of the parental consanguinity (Alenizi 2014)
Searching for archaic contribution in Africa
Published in Annals of Human Biology, 2019
Cindy Santander, Francesco Montinaro, Cristian Capelli
Recent studies looking at African hunter-gatherer and farmer populations have explored how deleterious genetic variation amongst human populations is affected by changes in population size and gene flow (Lopez et al. 2018). Specifically, hunter-gatherers are efficient in purifying selection, despite having a recent population collapse (Simons et al. 2014; Lopez et al. 2018). Long-term selection against archaic introgression in Africa has not been looked at, although recent studies have shown that non-African populations demonstrate selection against introgression in regulatory regions more than in protein-coding regions (Petr et al. 2019). A study exploring the genetic relationship between sequenced archaic hominins and Africans showed substantial IBD sharing between Africans (East and West) and Denisovans best explained by interbreeding between the ancestor of humans and other archaic hominins (Povysil and Hochreiter 2016). Whether these short IBD fragments are skewed in their distribution across genic and non-genic regions remains to be confirmed as well if they are putatively introgressed haplotypes under any form of non-neutral selection. However, Durvasula and Sankararaman (2018) have detected a number of regions with archaic ancestry in Yoruba which are in genic regions and that may be under positive selection (Table 1). Nevertheless, it is important to point out that without ancient African samples to confirm archaic introgression in present-day African populations, signs of adaptive introgression will remain putative.