Cause Of Polymorphism Research Articles

Postcovid syndrome — polymorphism of disorders in a new coronavirus infection

COVID-19, having not completed its epidemic development, gradually passes into the stage of prolonged diseases, which at the clinical level is designated as «postcovid syndrome». The symptomatology of these negative phenomena is quite diverse, covers the dysfunction of many organs and systems, and deserves the formulation of polymorphism of secondary and delayed complications. They are based on the consequences of the transferred acute phase of inflammation, systemic prolonged metabolic and structural disorders, including the studied genetic disorders. Possible causes of polymorphism of disorders and their manifestations in the postcovid period are considered.

630 ̊С±30 ̊С - Nodal (Critical) Temperature of Iron and Carbon Steel

The article deals with the problems of withstanding harsh temperatures by steel and iron. The authors of the work discuss iron denser high-temperature of γ modification and maximums and minimums of impact. In addition, the article analyses the transformations of iron and anomalies of properties: peak of heat capacity, acceleration of diffusion, etc. The authors take into account the consensus on the causes of polymorphism and the theoretical model of ferromagnetism. Besides, there is a consideration of "transformation" in interaction between Fe atoms that produce anomalies of steel properties. It is necessary to note the transformation detected by anomalies of any properties including mechanical. In the presented work the authors have made an attempt to prove transformations in iron at ~650 °C on the basis of extreme values of hardness and microhardness, metallographic structure, parameters of fine structure, precipitation resistance force depending on temperature. Therefore, the analysis of literature sources on physical and mechanical properties of iron and its derivatives has been made.

Olive cultivar origin is a major cause of polymorphism for Ole e 1 pollen allergen.

BackgroundPollens from different olive (Olea europaea L.) cultivars have been shown to differ significantly in their content in Ole e 1 and in their overall allergenicity. This allergen is, in addition, characterized by a high degree of polymorphism in its sequence. The purpose of this study is to evaluate the putative presence of divergences in Ole e 1 sequences from different olive cultivars.ResultsRNA from pollen individually collected from 10 olive cultivars was used to amplify Ole e 1 sequences by RT-PCR, and the sequences were analyzed by using different bioinformatics tools. Numerous nucleotide substitutions were detected throughout the sequences, many of which resulted in amino acid substitutions in the deduced protein sequences. In most cases variability within a single variety was much lower than among varieties. Key amino acid changes in comparison with "canonical" sequences previously described in the literature included: a) the substitution of C19-relevant to the disulphide bond structure of the protein-, b) the presence of an additional N-glycosylation motif, and c) point substitutions affecting regions of Ole e 1 already described like relevant for the immunogenicity/allergenicity of the protein.ConclusionVarietal origin of olive pollen is a major factor determining the diversity of Ole e 1 variants. We consider this information of capital importance for the optimal design of efficient and safe allergen formulations, and useful for the genetic engineering of modified forms of the allergen among other applications.

A set of conserved PCR primers for the analysis of simple sequence repeat polymorphisms in chloroplast genomes of dicotyledonous angiosperms

Short runs of mononucleotide repeats are present in chloroplast genomes of higher plants. In soybean, rice, and pine, PCR (polymerase chain reaction) with flanking primers has shown that the numbers of A or T residues in such repeats are variable among closely related taxa. Here we describe a set of primers for studying mononucleotide repeat variation in chloroplast DNA of angiosperms where database information is limited. A total of 39 (A)n and (T)n repeats (n > or = 10) were identified in the tobacco chloroplast genome, and DNA sequences encompassing these 39 regions were aligned with orthologous DNA sequences in the databases. Consensus primer pairs were constructed and used to amplify total genomic DNA from a hierarchical set of angiosperms. All 10 primer pairs generated PCR products from members of the Solanaceae, and 8 of the 10 were also functional in most other angiosperm species. Levels of interspecific polymorphism within the genera Nicotiana, Lycopersicon (both Solanaceae), and Actinidia (Actinidiaceae) proved to be high, while intraspecific variation in Nicotiana tabacum, Lycopersicon esculentum, and Actinidia chinensis was limited. Sequence analysis of PCR products from three primer pairs revealed variable numbers of A, G, and T residues in mononucleotide arrays as the major cause of polymorphism in Actinidia. Our results suggest that universal primers targeted to mononucleotide repeats may serve as general tools to study chloroplast variation in angiosperms.

Map order and linkage distances of molecular markers close to the supernodulation (nts-1) locus of soybean.

The molecular characteristics of markers in the chromosome region surrounding the supernodulation gene (nts-1) of soybean (Glycine max L. Merr.) were investigated in 187 F2 plants from a cross of G. max cv. Bragg (nts) and G. soja PI468.397 (wild-type nodulation). RFLP marker pUTG-132a, linked tightly (0.7+/-0.5 cM) to nts-1, was converted to a PCR marker. The polymorphism resides within a 1.72 kb PstI fragment and consists of an 832 bp insertion in G. max relative to the wild progenitor G. soja. The insertion is flanked by a 35 bp direct duplication that was found only once in G. soja. Data suggest that the pUTG-132a sequence exists only once in the genome, which is compatible with the recessive nature of nts-1. Accordingly, pUTG-132a is a valuable marker for map-based cloning. Another RFLP marker, pA-381, was mapped 4.8 cM distal to nts-1. Marker order, established by Maximum Likelihood Analysis, placed nts-1 between pUTG-132a and pA-381. To generate additional molecular markers, a segregating F2 population was analysed using bulked segregant analysis (BSA) and single oligonucleotide primer-based PCR (DNA amplification fingerprinting; DAF). PCR marker pcr5-4L was mapped to soybean linkage group H and sequenced. The data revealed (i) recombination events and marker order in the nts-1 region; (ii) the molecular nature and cause of polymorphisms in linked molecular markers; (iii) a low density of polymorphisms around nts-1, and (iv) diploidy of the distal region of linkage group H of soybean.

Pollen aperture heteromorphism is not due to unreduced gametophytes

Variations in ploidy level of the sporophyte are usually acknowledged as the main cause of polymorphism in pollen aperture number and pollen size. In heteromorphic species (two or more pollen morphs in all flowers of all plants) the different pollen types could thus be due to the presence of reduced and unreduced gametes. But data from the fossil record indicate that pollen aperture number has increased, suggesting that this trait may have evolved through selection. Our studies of Viola diversifolia have shown that the different aperture morphs have different selective values, also indicating that this character could have evolved and is not always due to ploidy level variations. To test this hypothesis, we measured DNA content of the reproductive nucleus as a test of gametophytic reduction in four heteromorphic species of Viola and in diploid and tetraploid individuals of a Petunia hybrida clone (which also served as a control to test for accuracy of the measurements). Our results show that aperture polymorphism is not due to gametophytic ploidy variations within plants and that variations in the proportions of the different pollen morphs are not correlated with variations of the amount of DNA in the sporophyte.

Heterochronic Dimorphism of Loxoconcha Uranouchiensis (Ostracoda) and its Implication for Speciation

Polymorphism is being actively investigated by ostracode specialists because the phenomenon is widespread and may be a key to understanding speciation patterns and evolutionary processes. However, the methods for recognizing the phenomenon and the cause or causes of polymorphism are still under debate. This study presents an example of genetically controlled ostracode dimorphism in which the relationship between the two forms can be explained in terms of heterochrony. The living males as well as the females of Loxoconcha uranouchiensis in Aburatsubo Cove, central Japan, are found to be dimorphic in size, shape, and surface ornamentation of the carapace. The dimorphic forms appear concurrently in the same microhabitat, suggesting that the dimorphism is genetically rather than environmentally controlled. Although the large and the small forms are indistinguishable in their early stages, morphological differences gradually appear and become complete after the final molting, which is the seventh molting for both forms. The characters determined by the number of moltings, such as the numbers of reticules, bristles, and pores, are identical between adults of the two forms. In contrast, for characters affected by the growth condition of the epidermal-cell system, such as carapace shape and fine surface ornamentation, the small-form adult is similar to the penultimate instar of the large form. Taking the large form as a standard, the small form is paedomorphic. These two forms are reproductively isolated and should be considered different species.

Theoretical Analysis of Electrophoretically Detectable Polymorphisms: Models of Very Slightly Deleterious Mutations

The nature of mutation-selection balance was investigated using models of mutation which assume stepwise production of new alleles in the allele space occupied by one or two type genes and multiple slightly deleterious mutations. The distribution of allelic frequencies and the effective number of alleles at equilibrium were obtained based on deterministic treatments. It was shown that they depend on the ratio between the selection coefficient and the mutation rate (s/v). When this ratio is large, the frequencies of the deleterious alleles become too low to form polymorphism; however, when the ratio is small, such a mutation-selection balance becomes important as a cause of polymorphism. In addition to analytical treatments, extensive Monte Carlo experiments were per. formed to investigate the stochastic effect due to small population size. When the effective population size (Ne) is small so that both Nev and Nes are small, the allele distribution is indistinguishable from the neutral case, while it approaches the deterministic equilibrium as Ne gets larger. The bearing of the present models on observations regarding protein polymorphisms was discussed.