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41.
To investigate the embryonic development of the central nervous system of the lamprey Lampetra fluviatilis, we have isolated and analysed the expression patterns of members of the LIM-homeodomain, Pax, Hedgehog and Nkx2.1 families. Using degenerate RT-PCR, single representatives of Lhx1/Lhx5, Lhx2/Lhx9, Pax3/Pax7 and Hedgehog families could be isolated in L. fluviatilis. Expression analysis revealed that the lamprey forebrain presents a clear neuromeric pattern. We describe the existence of 4 embryonic diencephalic prosomeres whose boundaries can be identified by the combined and relative expressions of LfPax37, LfLhx15 and LfLhx29. This suggests that the embryonic lamprey and gnathostome forebrain are patterned in a highly similar manner. Moreover, analysis of the LfHh gene, which is expressed in the hypothalamus, zona limitans intrathalamica and floor plate, reveals the possible molecular origin of this neuromeric brain pattern. By contrast, LfHh and LfNkx2.1 expressions suggest major differences in patterning mechanisms of the ventral telencephalon when compared to gnathostomes. In summary, our findings highlight a neuromeric organisation of the embryonic agnathan forebrain and point to the possible origin of this organisation, which is thus a truly vertebrate character. They also suggest that Hh/Shh midline signalling might act as a driving force for forebrain evolution.  相似文献   
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Low concentrations of HgCl2 elicited, in Saccharomyces cerevisiae, a transitory increase in the ATP level followed by a decrease of its concentration, until almost disappearance. At 1 microM HgCl2, the increase in ATP lasted for about 30 min, while at 10 microM the increase was only observed in the first 5 min of treatment. The initial burst of ATP was accompanied by a decrease in the level of hexose phosphates, whereas during the decrease of ATP an increase in the inosine and hexose phosphates levels took place. The treatment with HgCl2 inhibited the plasma membrane proton ATPase but not the activities of hexokinase or 6-phosphofructokinase.  相似文献   
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We analyzed 19 samples of Baird's tapir feces from La Sepultura Biosphere Reserve, collected between March and July 1999. We also took samples directly from a male tapir captured at the Montes Azules Biosphere Reserve. Both reserves are in Chiapas, Mexico. We used five techniques: flotation, MacMaster, micrometric, Ritchie's sedimentation and Ferreira's quantitative. In addition, we collected ectoparasites from animals captured in both reserves and from a captive couple from Tuxtla Gutierrez, Chiapas. These nematodes and protozoans were found: Agriostomun sp., Lacandoria sp., Neomurshidia sp., Trichostrongylus sp., Strongylus sp., Brachylumus sp, and an unidentified species of ancilostomaide. We also found Eimeria sp. and Balantidium coli, as well as the mites Dermacentor halli, Dermacentor latus, Amblyomma cajannense, Amblyomma coelebs, Amblyomma ovale, Anocentor nitens and Ixodes bicornis.  相似文献   
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Mimetic wing coloration evolves in butterflies in the context of predator confusion. Unless butterfly eyes have adaptations for discriminating mimetic color variation, mimicry also carries a risk of confusion for the butterflies themselves. Heliconius butterfly eyes, which express recently duplicated ultraviolet (UV) opsins, have such an adaptation. To examine bird and butterfly color vision as sources of selection on butterfly coloration, we studied yellow wing pigmentation in the tribe Heliconiini. We confirmed, using reflectance and mass spectrometry, that only Heliconius use 3-hydroxy-DL-kynurenine (3-OHK), which looks yellow to humans but reflects both UV- and long-wavelength light, whereas butterflies in related genera have chemically unknown yellow pigments mostly lacking UV reflectance. Modeling of these color signals reveals that the two UV photoreceptors of Heliconius are better suited to separating 3-OHK from non-3-OHK spectra compared with the photoreceptors of related genera or birds. The co-occurrence of potentially enhanced UV vision and a UV-reflecting yellow wing pigment could allow unpalatable Heliconius private intraspecific communication in the presence of mimics. Our results are the best available evidence for the correlated evolution of a color signal and color vision. They also suggest that predator visual systems are error prone in the context of mimicry.  相似文献   
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In this study α and β diversity patterns of five leaf litter arthropod groups (ants, predatory ants, oribatid mites, spiders and other arachnids) were described and compared in 39 sampling patches of a transformed landscape in southwestern Colombia, that represented five vegetation types: secondary forest, riparian forest, giant bamboo forest, pasture and sugarcane crop. It was also assessed whether some taxa could be used as diversity surrogates. A total of 6,765 individuals grouped in 290 morphospecies were collected. Species richness in all groups was lower in highly transformed vegetation types (pasture, sugarcane crop) than in native ones (forests). In contrast, there were no clear tendencies of β diversity among vegetation types. Considering sampling patches, 0.1–42% of the variation in α diversity of one taxonomic group could be explained from the α diversity of another, and 0.2–33% of the variation of β diversity of a given taxon was explained by that in other groups. Contrary to recent findings, we concluded that patterns of α diversity are more congruent than patterns of β diversity. This fact could be attributed to a sampling effect that promotes congruence in α diversity and to a lack of a clear regional ecological gradient that could promote congruent patterns of β diversity. We did not find evidence for an ideal diversity surrogate although diversity patterns of predatory ants had the greatest congruencies. These results support earlier multi-taxon evaluations in that conservation planning should not be based on only one leaf litter arthropod group.  相似文献   
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