Institution of Learning

Annotation Assignment

In the United States, women usually live longer than men do. The same tendency can be observed in other countries all around the world. Still, the human mind is curious and never satisfied with the bare statistics. It wants to know specific reasons that stand behind every phenomenon on the Earth. The truth is that people are still looking for sources of eternal youth and mean for prolongation of their lives. They dream of creating copies that would outlive their prototypes. For that reason, heavy investments are made in reproduction technologies nowadays. Scientists make every effort to find the means of increasing the human lifespan. Researchers in Japan seems to have made some progress in getting closer to the intended goal. Professors Manabu Kawahara and Tomohiro Kono found an interesting connection between the longevity of mice and the genome of their parents. Their study “Longevity of Mice without a Father” shows that longevity increases when the paternal genome is absent.

Purpose of the Study

Though women are historically known to live longer than men do, there is no clear explanation for that. Different scholars within the decades tried to determine whether longevity depends on the genome of both parents or the genome of one of them. Nevertheless, there was no possibility to acquire such data since two parents of different gender were necessary for the reproduction. However, with the technological progress and implementation of the cloning technique, obtaining such data became possible. Scholars received the opportunity of reproduction without male involvement and of finding out the outcomes of one. Therefore, the purpose of this study is to clarify the role of the maternal genome in the longevity found in progeny.

Method

The following steps were taken to conduct this research. First, the research group prepared a “bi-maternal mouse” (the ones produced without sperm). For that, female mice were collected and injected with chorionic gonadotropin. When the growing cycle stimulated by injection was completed, the scholars took ovulated oocytes from mice. After certain chemical manipulations, the scholars received bi-maternal embryos of two different genotypes. The obtained embryos were transferred into the uterus of female mice for two and a half days. The scholars recover formed bi-maternal mice recovered from the pregnant mice after 19 days. After that, they started observation on the bi-maternal mice and control mice from natural mating. Both groups of mice were housed together under special conditions. They had enough food throughout the day and environment without the pathogens. The main point of observation was to notice the differences in longevity between the two types of genetically identical mice. Besides, the research group aimed at determining the lifespan of the control mice and those produced without sperm. To determine the time of death, both mice were checked at least once a day. If the mice had got ill, the scientists killed them and considered their lifespan “as the best available estimate of its natural lifespan” (Kawahara & Kono, 2010, p.458).

Results

Comparison of longevity between the artificially reproduced mice and those from natural mating revealed significant differences. Even when mice had enough food and no pathogens, bi-maternal mice outlived the control mice by 30% as they lived 186 days longer. Besides, the immune system of the bi-maternal mice was higher than that of mice from natural mating. To add even more, both bi-maternal mice and the controls displayed different physical traits, such as weight and leukocyte composition. In particular, the bodyweight of the bi-maternal mice was lower than the control mice displayed. However, special conditions had no impact on longevity, therefore, one should deduce that it was affected mainly by the genome composition. The results of the study revealed that the bi-maternal genotype unmistakably altered the total survival curve, signifying a delay in the expression of all causes of mortality.

Discussion and Conclusion

Different scientists have their own explanations of why women live longer than men do. Still, none of the existing theories provides one with a clear reason, which differences in the aging process contribute to that phenomenon. The authors’ findings indicate the relation between the genome composition of the mammals’ parents and the longevity of one. In particular, bi-maternal genotype has a positive influence on the longevity of the offspring. The results are impressive even more when one takes into account that cloned mice have a shorter lifespan than mice from natural mating. It shows that the paternal genome hurts the longevity of the progeny. The authors’ suggestion for further research implies studying the viability of mammals in the context of genome composition.

To conclude, the research of professors Kawahara and Kono gave people an insight into the possible consequences of human cloning by the mice’s example. It showed that extracting the male genome from the genotype might elongate one’s life. Still, there is a long way ahead of the studying of the lifespan regularities. Even when the scholars determine that the paternal genome has a detrimental influence on progeny, it does not change much. People cannot avoid natural reproduction, so the paternal genome will always be present in the offspring genotype. Maybe future research should concentrate on the ways of “deactivating” the paternal genome without ruining its structure. Besides, there must be alternative ways of prolonging the lifespan apart from cloning mammals.