13,229 research outputs found
Exploring the global topology of the universe
In this talk work done by our group on cosmic topology is reviewed. It ranges
from early attempts to solve a famous controversy about quasars through the
multiplicity of images, to quantum cosmology in this context and an application
to QED renormalization.Comment: 4 pages. Contribution to the XXII Brazilian National Meeting on
Particles and Fields, Sao Lourenco, October 200
Experimental confirmation of protandric simultaneous hermaphroditism in a Caridean shrimp outside of the genus Lysmata
Caridean shrimps display a variety of sexual systems including gonochorism and various forms of protandry but rarely simultaneous hermaphroditism. Protandric simultaneous hermaphroditism (PSH) has thus far only been demonstrated in the genus Lysmata. The first report of simultaneous hermaphroditism in a caridean shrimp was with Exhippolysmata ensirostris. However, this was not confirmed, since this species was also considered to be strictly protandric. Therefore, inconclusive results about this species’ true sexual system led us to examine Exhippolysmata oplophoroides. Mating between female phase individuals resulted in successful spawning, embryonic development and hatching of viable larvae. Furthermore, we have confirmed that this species is not capable of self-fertilization. Juveniles reared in the laboratory matured in a similar manner to that of Lysmata. Data were limited due to the loss of all individuals to a Vibrio infection. However, the results obtained in this study conclusively affirm functionally that PSH occurs outside the genus Lysmata, in E. oplophoroides. Theories examining the evolution of PSH within decapods must be re-examined in light of the present data
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