Research Articles (Genetics)

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    Fast developing Russian wheat aphid biotypes remains an unsolved enigma
    (Elsevier Inc., 2020-12-30) Botha, Anna-Maria
    Diuraphis noxia, commonly known as the Russian wheat aphid, is an economically important cereal pest species, highly invasive and reproduces mostly asexually. Remarkably, many new virulent populations continue to develop, despite the lack of genetic diversity in the aphid. Russian wheat aphid is a phloem feeder and is therefore engaged in a continuous arms battle with its cereal host, with the acquisition of virulence central to the breakdown of host resistance. In the review, most attention is given to recent topics about mechanisms and strategies whereby the aphid acquires virulence against its host, with special reference given to the role of noncoding RNA elements, bacteria, and the epigenetic pathway in possibly directing virulence.
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    Improving crops for a changing world
    (Frontiers Media S.A, 2021-09-06) Lloyd, James Richard; Kossmann, Jens
    Plant biotechnology has been fundamental to the development of human civilisation. The domestication of plants helped increase food production, allowing the sustenance of populations in large settlements and they provide most calories in the human diet alongside being used as fodder for farm animals. They are also good sources of both therapeutic drugs and industrial feed stocks, while more recently they have been used to produce pharmaceutical proteins and biofuels. There are neverthelessmany areas where plants can be improved through geneticmanipulation and there are pressing reasons why this needs to be accomplished.
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    Patterns and tempo of PCSK9 pseudogenizations suggest an ancient divergence in mammalian cholesterol homeostasis mechanisms
    (Springer Nature, 2021-01-30) Van Asch, Barbara; Da Costa, Luís Filipe Teixeira
    Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a central role in cholesterol homeostasis in humans as a major regulator of LDLR levels. PCSK9 is an intriguing protease in that it does not act by proteolysis but by preventing LDLR recirculation from endosomes to the plasma membrane. This, and the inexistence of any other proteolytic substrate but itself could suggest that PCSK9 is an exquisite example of evolutionary fine-tuning. However, the gene has been lost in several mammalian species, and null alleles are present (albeit at low frequencies) in some human populations without apparently deleterious health effects, raising the possibility that the PCSK9 may have become dispensable in the mammalian lineage. To address this issue, we systematically recovered, assembled, corrected, annotated and analysed publicly available PCSK9 sequences for 420 eutherian species to determine the distribution, frequencies, mechanisms and timing of PCSK9 pseudogenization events, as well as the evolutionary pressures underlying the preservation or loss of the gene. We found a dramatic difference in the patterns of PCSK9 retention and loss between Euarchontoglires—where there is strong pressure for gene preservation—and Laurasiatheria, where multiple independent events have led to PCSK9 loss in most species. These results suggest that there is a fundamental difference in the regulation of cholesterol metabolism between Euarchontoglires and Laurasiatheria, which in turn has important implications for the use of Laurasiatheria species (e.g. pigs) as animal models of human cholesterol-related diseases.
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    Use of pawpaw (Carica papaya) seed in tilapia sex reversal
    (Reviews in Agricultural Science, 2020-10-18) Omeje, Victor Okonkwo; Lambrechts, Helet; Brink, Danie
    Tilapia breeds effortlessly in captivity, with this attribute which is considered as the “Achilles heel” of the species, because it predisposes pond systems to overcrowding and low weight at harvest. Efforts to mitigate this shortcoming include mono-sex culture using exogenous hormone to reverse the sex of sexually undifferentiated fish. This is premised on the fact that improvement in the growth by mono-sex culture will lead to shortened production times and a more uniform weight at harvest, which will ultimately benefit the producers. However, the use of exogenous hormones in aquaculture has recently raised concerns about the effect on farm workers, consumers and on the environment. Recently research has focused on the use of substances of plants origin which mimic the action of hormones as a potential approach to achieve sex reversal in fish. Pawpaw (Carica papaya) seed contains phytochemicals that hold great promise as a sex reversal and a reproductive inhibition agent in aquaculture. The purpose of this study was to conduct a systematic review of the relevant literature on the possibility of using a less harmful phytochemicals abundant in the plant to effect sex reversal of sexually undifferentiated tilapia.
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    Molecular characterisation of apple accessions with respect to aminocyclopropane-1-carboxylic acid synthase gene (ACS1) polymorphism
    (Czech Academy of Agricultural Sciences, 2020-02-07) Mhelembe, Khethani; Kriel, Johan; Bester, Cecilia; Louw, Esme; Roodt-Wilding, Rouvay; Tobutt, Kenneth
    The ARC apple gene bank collection was genotyped for the fruit expressed gene ACS1, in which a short-interspersed element (SINE) in the promoter is known, when homozygous, to correlate with the delayed ethylene production. Primers were designed amplifying products less than 500 bp and 224 cultivars of domestic apple were analysed, 169 not previously genotyped. Of these, 82 were aa (homozygous for the high ethylene allele at 202 bp), 73 were ab and 14 bb (homozygous for the low ethylene allele, with the SINE, at 339 bp). The difference between the allele sizes, 137 bp, observed in the current study is consistent with the indel of 138 bp originally described, but differs considerably from the indel of 166 bp reported in literature. In addition, 21 accessions of other Malus species were analysed. Only one, M. ‘Golden Hornet’, had the b allele, which suggests it may have been introgressed from M. pumila.