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421.
422.
Several hypotheses have been proposed to explain why femalebirds either
copulate repeatedly with a single mate or copulatewith multiple partners even
though only a single copulationmay be sufficient to fertilize an entire
clutch. We hypothesizethat females may directly benefit from high frequencies
of copulationand multiple copulation partners if they receive a cloacal
inoculationof beneficial sexually transmitted microbes (STMs) that caneither
protect them against future encounters with pathogensand/or serve as therapy
against present infections. Experimentsin domestic animal production,
wildlife rehabilitation, andclinical medicine indicate that inoculations of
beneficial microbesderived from the indigenous microflora of hosts can lead
tonutritional benefits, resistance to colonization by pathogens,the
elimination of infection, and improved immune system functioningin
recipients. Our hypothesis predicts greater copulatory rateswhen the
probability of the transmission of beneficial microbesexceeds that of
pathogens and when the positive effects of beneficialmicrobes on host fitness
exceed the negative effects of pathogens.Patterns of copulatory behavior in
birds suggest the potentialutility of our hypothesis. We discuss our
hypothesis in thecontext of observed patterns of copulation in birds and
proposesome ways to directly test our hypothesis. Information on the
probabilitiesof transmission during copulation of beneficial and pathogenic
microbesand their relative potencies in birds are needed to directlytest the
predictions of our hypothesis. 相似文献
423.
Verónica A. Lombardo Anje Sporbert Salim Abdelilah-Seyfried 《Journal of visualized experiments : JoVE》2012,(67)
Embryogenesis is a dynamic process that is best studied by using techniques that allow the documentation of developmental changes in vivo. The use of genetically-encoded fluorescent proteins has proven a valuable strategy for elucidating dynamic morphogenetic processes as they occur in the intact organism. During the past decade, the development of photoactivatable and photoconvertible fluorescent proteins has opened the possibility to investigate the fate of discrete subpopulations of tagged proteins1. Unlike photoactivatable proteins, photoconvertible fluorescent proteins (PCFPs) are readily tracked and imaged in their native emission state prior to photoconversion, making it easier to identify and select regions by optical inspection. PCFPs, such as Kaede2, KikGR3, Dendra4 and EosFP5, can be shifted from green to red upon exposure to UV or blue light due to a His-Tyr-Gly tripeptide sequence which forms a green chromophore that can be photoconverted to a red one by a light-catalyzed β-elimination and subsequent extension of a π-conjugated system3. PCFPs and their monomeric variants are useful tools for tracking cells6-10 and studying protein dynamics11-14, respectively. During recent years, PCFPs have been expressed in different animal model, such as zebrafish6, chicken7,8 and mouse9,10 for cell fate tracking. Here we report a protocol for cell-specific photoconversion of PCFPs in the living zebrafish embryo and further tracking of photoconverted proteins at later developmental stages. This methodology allows studying, in a tissue-specific manner, cell biological events underlying morphogenesis in the zebrafish animal model. 相似文献
424.
Wei He Gerrik F. Verhees Nikhil Bhagwat Ye Yang Dhananjaya S. Kulkarni Zane Lombardo Sudipta Lahiri Pritha Roy Jiaming Zhuo Brian Dang Andriana Snyder Shashank Shastry Michael Moezpoor Lilly Alocozy Kathy Gyehyun Lee Daniel Painter Ishita Mukerji Neil Hunter 《Developmental cell》2021,56(14):2073-2088.e3
425.
L. Colombo A. Barbaro A. Libertini P. Benedetti A. Francescon I. Lombardo 《Zeitschrift fur angewandte Ichthyologie》1995,11(1-2):118-125
The European sea bass, Dicentrarchus labrax L., was successfully subjected to chromosome manipulation. Triploidy was induced by cold-shocking eggs at 0–2°C for 20 min starting 5 min after fertilization in order to prevent the extrusion of the second polar body. Meiogynogenesis was also obtained by fertilizing eggs with UV-irradiated sperm (3300 and 6600 erg m−2 ) and subsequently doubling the chromosome set by meiotic block as above. The commercial advantages of culturing triploid and gynogenetic sea bass are discussed. 相似文献