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ORIGINS OF SEX. "Any heterotypic recognition/adhesion pairs (hereafter H1/H2) in a protoeukaryote would be candidates for the next posited stage in the origins of sex, namely, the exclusive expression of H1 in gametes that we will generically call plus mating type and exclusive expression of H2 in gametes that we will call minus mating type.' http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

SELF RECOGNITION MOLECULES. "The original self-recognition molecules in protoeukaryotic gametes might have engaged in homotypic interactions, like present-day cadherins that adhere to one another. Alternatively, the interactions might have been heterotypic, like present-day integrins that adhere to intercellular adhesion molecules (ICAMs)." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

VAST PERIANTH DIVERSITY. "Within the angiosperms, other morphological features could be explained by homeosis, primarily in the sterile floral organs, collectively termed the perianth. These organs show enormous diversity in their morphology." https://lnkd.in/dVXk7jP View in LinkedIn

BREAKING THE SPECIES BARRIER. "That said, there are examples in which hybrids that have formed from cross-species cell–cell fusions have ultimately given rise to new species, such as the posited origin of S. cerevisiae from an ancestral whole genome duplication event following fusion of two related, but different, yeast species." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

"HERMAPHRODITIC AXES could have evolved through the simple restriction of B gene expression to part of a conelike structure, yielding both male and female organs on the same axis." https://lnkd.in/dVXk7jP View in LinkedIn

SPECIES INCOMPATIBILITY. "When different yeast species are induced to fuse with each other, their hybrid is unable to proceed smoothly through meiosis, even if all the chromosomes are colinear and syntenic, because a higher level of DNA mismatches provokes the mismatch repair machinery to abort meiotic recombination events, and spores fail to germinate." https://lnkd.in/ebVhXPf View in LinkedIn

TRANSITION ACROSS AXES. "One of the long-standing questions in seed plant evolution was how an ancestor with separate male and female reproductive axes (e.g., pinecones) made the transition to an angiosperm-like plant with hermaphroditic axes (flowers)." https://lnkd.in/dVXk7jP View in LinkedIn

SPECIES BARRIERS. "Modern sexual recognition systems are overwhelmingly prezygotic—cells recognize “self” via pheromones or cell-surface molecules that stimulate zygotic cell fusion—but postzygotic mechanisms have also evolved that permit cells to monitor how similar their chromosomal sequences are with respect to their fusion partner." https://lnkd.in/ebVhXPf View in LinkedIn

FRAGMENT FROM NATURE continues the curated contemplation on flower structure from last weekend. Flowers are an exemplar of many forms in nature, of how they evolved, and why. Being discrete and familiar, these lovely structures can open our minds to the complicated evolutionary paths that led to their current forms, not the least of it is the development of distinct sexes and mixed sex plants. Plants have among the most diverse and interesting types of reproductive strategies. Enjoy the tiptoe through the tulips for this last weekend. View in LinkedIn

SELF MODULES. "Self-recognition modules presumably existed in the protoeukaryotic gene pool that, with evolutionary tinkering, allowed like-like haploid cell adherence to trigger intracellular signals that elicited the conditions for cell–cell fusion." https://lnkd.in/ebVhXPf View in LinkedIn