The C-value Paradox and Its Implications

The Genome and the C-value Paradox

The genome for all pant species features large variations with a complexity in their ploidy and genome size. It has since led scientists into discovering the concept of the C-value paradox that implies to the fact that different organisms tend to exhibit varying chemical, morphological and organic elements even in situations where they fall under the same genus. The variations are what are generally perceived to be the expression of different C-values (MacGregor 2013, p. 259). It is especially worth noting that the C-value is not limited to plants alone as it is featured even in the genome of animal species. In any group of animals or plants the minimum genome size that is needed in producing a particular grade of organization that is often considerably smaller when compared to the maximum genome that is expressed in that particular group (Ni & Guo 2005, p. 2372).

The Background and History of the C-value

The understanding of the plication of the C-value necessitate a reflection into the background and history in the understanding of the advances in genome knowledge. The first genome measurements are thought to have been made in the late 1940s and through the developments within this time, many other surveys have been developed. The understanding of the role of the C-value paradox has resulted in almost 3800 animal genomes being described less than a century later based on the reports that have emerged in the recent studies (Rosbash et al. 1974, p. 3748). The reality is that within much of a 50-year history of genome expression it has become evident that there is a major taxonomic discrepancy in the genome data reports. The most important of the historical advances in scientific literature on genome expression was the study by Mirsky and Ris that showed that there is a disconnect in the genome size and the complexity of organisms. The realization led many theorists to be challenges because for a long time, it had been assumed that the C-value is constant because it was believed that the DNA was primarily an expression of a stuff of genes. It is thus understood that the appreciation that many eukaryotes’ DNA is noncoding acted a resolution to the common misconception that has spread in the field of science and molecular biology (Dover 1990, p. 62).

The Complexity of the C-value Concept

There are many expressions that are sued to refer to the concept of the C-value complex. A significant example would be the assessment of how the C-value affects the complexity of the genome in many organisms. It is primarily based on the understanding that the genome size of many organism range between 0.5 to 150 pg while that of insects has since been described to be between 0.05 to 15 pg. That of annelid worms is stated to fall between 0.7 to 8 pg (Ormerod et al. 1999, p. 847). The variation is especially significant in particular genuse such as the case of salamanders where the genome size is described to range from 18 to 69pg (Sheth & Thaker 2012, p. 917). It is significant because while the complexity is evident in the C-value paradox, the animals often look alike and demonstrate remarkable similarities. However, a closer examination shows that there are massive differences in the behavioral, ecological and developmental elements that implies that the C-value is a complex concept in genome expression (Ormerod et al. 1999, p. 850).

The Implication of the C-value Enigma

It is particularly significant to note that while the C–value paradox was understood from the perceptive that the DNA of most eukaryotic organisms tends to be noncoding a greater subject of C-value enigma has resulted. The apprehension has necessitated the need to describe implication on gene expression. The description is founded on the fact that questions have been raised regarding the sources, the mechanisms of spread, the effects on phenotypical expression and the differential expression of the nongenomic organisms that are the majority (Bennett & Leitch 2005, p. 95). The C-value enigma is a running puzzle that is founded on the complexity in the genome of living organism as pertains the foundation of the C-value complex. More research has been focused on the basis of genomic and evolutionary theory to elucidate the implications on the genomes of living organisms. One critical area has been on the “parasitic” transposable elements (TEs) that relates to the operation of the genomes within the context of natural selection when examined at the sub genomic level (Daily et al. 2000, p. 396). The TEs have been found to play a critical role in the expression of the organism at the phenotypical level. The multiselection complex has, however, been described only at the higher levels especially as pertains the groups and species. The field of C-value of enigma has necessitated the investigation into the role that particular organisms plays in the expression of unmatched diversity considering that most animal genomes reside in the arthropod cells.

The Impact of C-value on Genome Expression

The subject of genome expression has thus been influenced greatly by the knowledge that has been gained over the years from the apprehension of the significant of the C-value. Intriguingly, scientists have realized that a large genome size does not necessarily relate to ecological competiveness or evolutionary advancement (Gregory 2005, p. 138). The case of plants is especially critical because those with large genomes have been found to have a reduced photosynthetic efficiency and tend not the be respected in the extreme environments. Furthermore, the eukaryotes that have large genomes have a low species of diversity and they also evolve at a slower rate compared to other animals. The subject of the C-value has thus brought into perception a greater area of the paleopolyploidy in the angiosperms (Praça-Fontes et al. 2011, p. 2303). The variations in the C-value have been a major force in the evolution of plants because most crops are polyploidy in nature. Most notably, the genome of cotton, tobacco, sugarcane, wheat and oat are alloploids while banana, watermelon and alfalfa are autoploids. The expression of either is primarily based on the complexity in the genome factor and the preponderance of ploidization based on their diploid progenitors (Leitch et al. 2005, p. 209).

Conclusion

In summary, it is worth noting that the subject of the C-value is based on the description of the nature of the haploid genome. Different organisms tend to have varying expressions of the C-value as some tend to be expressed more than others. While the subject is understood both from the perspective of the animals and plants, the understanding of the variation in plants is especially significant. The increased awareness has led to a more complex area that is described as the C-value enigma that has necessitated the appreciation of the significance of the C-value.

References

Bennett, M.D. & Leitch, I.J., 2005. Genome evolution in plants. In The Evolution of the Genome. pp. 89–162. Available at: http://www.scopus.com/inward/record.url?eid=2-s2.0-84882468079&partnerID=tZOtx3y1.

Daily, G.C. et al., 2000. Ecology. The value of nature and the nature of value. Science (New York, N.Y.), 289(5478), pp.395–6. Available at: http://www.ncbi.nlm.nih.gov/pubmed/10939949.

Dover, G., 1990. Yes, we have no C-value paradox. Trends in Ecology and Evolution, 5(2), p.62.

Gregory, T.R., 2005. The C-value enigma in plants and animals: A review of parallels and an appeal for partnership. In Annals of Botany. pp. 133–146.

Leitch, I.J. et al., 2005. Evolution of DNA amounts across land plants (Embryophyta). In Annals of Botany. pp. 207–217.

MacGregor, H.C., 2013. C-Value Paradox. In Brenner’s Encyclopedia of Genetics: Second Edition. pp. 258–258.

Ni, L.P. & Guo, S.L., 2005. Review on relationship between invasiveness of plants and their DNA C-value. Acta Ecologica Sinica, 25(9), pp.2372–2381.

Ormerod, S.J., Pienkowski, M.W. & Watkinson, A.R., 1999. Communicating the value of ecology. Journal of Applied Ecology, 36(6), pp.847–855.

Praça-Fontes, M.M., Carvalho, C.R. & Clarindo, W.R., 2011. C-value reassessment of plant standards: An image cytometry approach. Plant Cell Reports, 30(12), pp.2303–2312.

Rosbash, M., Ford, P.J. & Bishop, J.O., 1974. Analysis of the C-value paradox by molecular hybridization. Proceedings of the National Academy of Sciences of the United States of America, 71(9), pp.3746–50. Available at:a http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=433853&tool=pmcentrez&rendertype=abstract.

Sheth, B.P. & Thaker, V.S., 2012. RbcL: A key to c value paradox in plants. Plant Archives, 12(2), pp.915–919.