نتایج جستجو برای: assisted reproductive technique

تعداد نتایج: 817930  

Journal: :Biology letters 2009
Hitoshi Araki Becky Cooper Michael S Blouin

Supplementation of wild populations with captive-bred organisms is a common practice for conservation of threatened wild populations. Yet it is largely unknown whether such programmes actually help population size recovery. While a negative genetic effect of captive breeding that decreases fitness of captive-bred organisms has been detected, there is no direct evidence for a carry-over effect o...

Journal: :The American naturalist 2012
Sandra Bouwhuis Rémi Choquet Ben C Sheldon Simon Verhulst

Longitudinal studies of senescence accumulate rapidly from natural populations. However, it is largely unknown whether different fitness components senesce in parallel, how reproductive and survival senescence contribute to declines in reproductive value, and how large the fitness cost of senescence is (the difference between the observed reproductive value and the hypothetical reproductive val...

Journal: :Asian journal of andrology 2009
Dan Gong Yu-Lin Liu Zhong Zheng Yi-Fei Tian Zheng Li

Beyond the scientific progress in assisted reproductive technologies (ART), it is necessary to discuss the ethical considerations behind these advances. Ethical issues concerning sperm donation have been considered and discussed by government and non-governmental agencies, the public, media and academic institutions in many countries. Recommendations and guidelines concerning sperm donation iss...

Journal: :Journal of medical genetics 1994
J R Gray A B Bridges M J Faed T Pringle P Baines J Dean M Boxer

This study in north east Scotland has shown that Marfan syndrome has a minimal birth incidence of 1:9802 live births, a minimal prevalence of 1:14217, and that 8/30 (26.7%) of cases in our series are new mutations. The calculated mutation rate is 15 +/- 6.7 x 10(-6) and there is evidence of reduced reproductive fitness.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1998
Y Ouyang C R Andersson T Kondo S S Golden C H Johnson

In some organisms longevity, growth, and developmental rate are improved when they are maintained on a light/dark cycle, the period of which "resonates" optimally with the period of the endogenous circadian clock. However, to our knowledge no studies have demonstrated that reproductive fitness per se is improved by resonance between the endogenous clock and the environmental cycle. We tested th...

2013
Andreea Velişcu Bogdan Marinescu Mihai Mitran Marilena Băluță Lucia Costoiu Cristina Damian

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