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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts |News Archive Sep 17, 2013



Drosophila, or Fruit Fly, is teaching us that hman life expectancy
may be passed down from mother to daughter, father to son.

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Like mother, like daughter — like father, like son

Evolutionary biologists at the universities in Bielefeld and Uppsala (Sweden) now show that this proverb also applies to inheriting a long life – at least for fruit flies (Drosophila).

A research team found that the descendants of these insects mostly inherit their lifespan from their own sex: male descendants will very probably live about as long as their fathers; female descendants, about as long as their mothers. The scientists have published their findings on Thursday 12 September in the renowned journal American Naturalist.

This new study by the German–Swedish research team, has turned a previous assumption by biologists and physicians upside down. Up to now, scientists thought the genetic risk for disease was equally strong in both female and male descendants.

The study idea proceeded from the assumption that average life expectancy of women and men differs – possibly for genetic reasons, but also due to different lifestyles. The German–Swedish research team wanted to find out how far this sex difference in lifespan depends on genetic make-up.

To carry out their experiments, they manipulated the heredity of fruit flies by cross-breeding them with special fly mutants, breeding 50 hemi-clones. A hemi-clone is one-half a genetic genetic identical of a parent, and one half completely unrelated. From each hemi-clone, the researchers determined the lifespan of 400 females and 400 males. ['A hemiclone is equivalent to the offspring produced by randomly picking a group of eggs from a base population, then fertilizing each egg with a cloned copy of the same sperm,' National Academic Press]

"What’s special about this approach is that it enables us to measure the influence of this 50 per cent identical genetic make-up in both sexes," says Dr. Holger Schielzeth from the Faculty of Biology – one of the authors of the study.

The authors then used the data from the hemi-cloned fruit flies to read off how similar the individuals in a hemi-clone are and how far females and males from one hemi-clone share the same lifespan.

Results showed that lifespan was very similar within sexes, with the relation between sexes slight.

Methuselah genes in the father exert only a limited influence on female descendants – at least in fruit flies.

Vice versa, long-lived females do not necessarily have long-lived brothers, fathers, or sons.

Approximately three-quarters of genetic components for life expectancy are effective only within the same sex.

The researchers concluded that risk for a fatal hereditary disease is passed on—above all—within the same sex.

"Gene variants that could be problematic for one sex seem to have only a comparatively low influence on the life expectation of the other sex," says Holger Schielzeth.

In principle, this finding could also generalize to human beings as human life expectancy is also hereditary.

According to Schielzeth, sex-specific heredity may also be relevant in medicine, and medical therapies should pay more attention to sex-specific risks.

Abstract and publication:
Anne Lehtovaara, Holger Schielzeth, Ilona Flis, and Urban Friberg: "Heritability of lifespan is largely sex-limited in Drosophila," American Naturalist, http://dx.doi.org/10.1086/673296, published online on 12 September 2013.

For further information in the Internet, go to:

Original press releas:http://ekvv.uni-bielefeld.de/blog/uninews/entry/inheritance_of_lifespan_is_sex