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A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
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Identification of the signalling molecules involved in mesoderm formation in amphibian embryos still presents problems. None of the original candidates, such as activin, have been definitively ruled out, and the new factors, such as the nodal-related genes, have come on to the scene. Of the original candidates, activin has been definitively shown to act as a morphogen, whereas bone morphogenetic protein (BMP)-4 has emerged as a ventral inducer and an inhibitor of neural differentiation. The effects of BMP-4 are antagonized by chordin, a molecule related to the product of the Drosophila gene short gastrulation. 相似文献
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Aqueous solutions of a number of biological stains were completely decontaminated to the limit of detection using Amberlite resins. Amberlite XAD-16 was the most generally applicable resin but Amberlite XAD-2, Amberlite XAD-4, and Amberlite XAD-7 could be used to decontaminate some solutions. Solutions of acridine orange, alcian blue 8GX, alizarin red S, azure A, azure B, Congo red, cresyl violet acetate, crystal violet, eosin B, erythrosin B, ethidium bromide, Janus green B, methylene blue, neutral red, nigrosin, orcein, propidium iodide, rose Bengal, safranine O, toluidine blue O, and trypan blue could be completely decontaminated to the limit of detection and solutions of eosin Y and Giemsa stain were decontaminated to very low levels (less than 0.02 ppm) using Amberlite XAD-16. Reaction times varied from 10 min to 18 hr. Up to 500 ml of a 100 micrograms/ml solution could be decontaminated per gram of Amberlite XAD-16. Fourteen of the 23 stains tested were found to be mutagenic to Salmonella typhimurium. None of the completely decontaminated solutions were found to be mutagenic. 相似文献
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Macrophage dependence of peripheral sensory nerve regeneration: possible involvement of nerve growth factor. 总被引:12,自引:0,他引:12
The levels of NGF and NGF receptor mRNA, the degree of macrophage recruitment, and the ability of sensory and motor axons to regenerate were measured in C57BL/Ola mice, in which Wallerian degeneration following a nerve lesion is very slow. Results were compared with those from C57BL/6J and BALB/c mice, in which degeneration is normal. We found that in C57BL/Ola mice, apart from the actual lesion site, recruitment of macrophages was much lower, levels of mRNA for both NGF and its receptor were raised only slightly above normal, and sensory axon regeneration was much impaired. Motor axons regenerated quite well. These results provide in vivo evidence that macrophage recruitment is an important component of NGF synthesis and of sensory (but not motor) axon maintenance and regrowth. 相似文献