Biology

[Hassan Kurd]

Study of life is classified as biology

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Tobacco Mosaic Virus (TMV) is the most extensively studied virus in plants. It was discovered by Iwanowski (1892) and obtained in pure state by Stanley (1935). It has a helical symmetry. TMV is a cylindrical structure with a molecular weight of 40 million and dimension of 160 x 3000 A°. Through X-ray diffraction and electron microscopy various extensive studies have been done.

[Didgevillage]

Tobacco or its traces were found in Egyptian mummies. No doubt that the Egyptians smoked tobacco, long before Columbus.

Tobacco and syphilis were brought to the Japanese islands by the Portuguese sailors and traders along with firearms in the 16th century and they spread immediately to the entire country. If Jesuits played any role in this, I don't know.

Lyme disease is also caused by a modified form of spirochete and tobacco is known (by some) to be effective. An interesting coincidence.

[Tintin]

Absolutely fascinating paper published in 2020 by The Royal Society and its findings suggest that not only is reproductive selection by females evident from social interaction/the 'mating game', but also down to the cellular level, post-intercourse.

With thanks to Massimo on X
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Chemical signals from eggs facilitate cryptic female choice in humans
Source: https://royalsocietypublishing.org/r...litate-cryptic
AVALON Library PDF: https://avalonlibrary.net/Chemical_s....2020.0805.pdf

ABSTRACT
Mate choice can continue after mating via chemical communication between the female reproductive system and sperm. While there is a growing appreciation that females can bias sperm use and paternity by exerting cryptic female choice for preferred males, we know surprisingly little about the mechanisms underlying these post-mating choices. In particular, whether chemical signals released from eggs (chemoattractants) allow females to exert cryptic female choice to favour sperm from specific males remains an open question, particularly in species (including humans) where adults exercise pre-mating mate choice. Here, we adapt a classic dichotomous mate choice assay to the microscopic scale to assess gamete-mediated mate choice in humans.

We examined how sperm respond to follicular fluid, a source of human sperm chemoattractants, from either their partner or a non-partner female when experiencing a simultaneous or non-simultaneous choice between follicular fluids. We report robust evidence under these two distinct experimental conditions that follicular fluid from different females consistently and differentially attracts sperm from specific males. This chemoattractant-moderated choice of sperm offers eggs an avenue to exercise independent mate preference. Indeed, gamete-mediated mate choice did not reinforce pre-mating human mate choice decisions. Our results demonstrate that chemoattractants facilitate gamete-mediated mate choice in humans, which offers females the opportunity to exert cryptic female choice for sperm from specific males.

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Summary by Massimo:

Fertilization is not random, and the fastest sperm does not always win: in reality, the egg decides who succeeds.

While for decades we were taught that fertilization is a race won by the fastest sperm, a study published in Proceedings of the Royal Society B shows how human reproduction actually works.

Scientists analyzed follicular fluid from 60 couples undergoing fertility treatment at St Mary's Hospital in Manchester, UK. They discovered that the egg releases chemical signals (chemoattractants) that actively attract sperm from certain men over others.

Through these chemical signals, the egg exerts its own biological selection, influencing which sperm manage to get close. The egg appears to favor sperm that offer optimal genetic compatibility with its own genome — particularly in genes related to the immune system — which may help produce healthier offspring.

Interestingly, this cellular preference does not always align with the couple’s conscious partner choice. In many cases, eggs showed stronger attraction to sperm from non-partner males.

This chemical communication demonstrates that female biology continues to evaluate and select options even after intercourse. Understanding this process could lead to more precise solutions for unexplained infertility. Science continues to reveal the remarkable level of biological interaction that occurs during reproduction.

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