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PubMed2002

Natural TWIST protein variants in a panel of eleven non-human primates: possible implications of TWIST gene-tree for primate species tree.

The twist gene is implied in head morphogenesis, as human patients heterozygous at TWIST and heterozygous M-twist mutant mice present similar cranial-facial abnormalities. M-twist and TWIST are respectively unique genes, coding for a B-HLH transcription factor. We identified twist coding sequences from 11 species representing 7 families of primates, report their conservation and genus-specific amino acid substitutions, and present a tentative gene-tree of these sequences. Amino acid changes result in natural Twist variants, which might contribute to generating distinct head morphologies in species. These data suggest twist as a molecular marker, which could be used to refine controversial classification.

Amino Acid Sequence↗

PubMed1994

Application of minimal spanning trees in glioma grading--a CLIPPER program for the calculation and construction of minimal spanning trees.

We present a CLIPPER program for the calculation and graphical representation of minimal spanning trees (MST) which is available on request on diskette from the authors. The MST are a useful parameter for structural cluster detection. They can be applied to grading problems in tumour biology. We present and discuss the applicability of MST by an example from the field of astrocytoma grading.

Algorithms↗

PubMed1975

Photosynthetic action spectra of trees: I. Comparative photosynthetic action spectra of one deciduous and four coniferous tree species as related to photorespiration and pigment complements.

Comparative isoenergetic action spectra of net photosynthesis for intact, current year foliage of five tree species were determined from 400 to 710 nm by CO(2) exchange analysis. The blue (400 to 500 nm) peak of net photosynthetic activity for the green broadleaves of red alder (Alnus rubra Bong.) was reduced to a plateau for the green needle-leaves of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and Sitka spruce (Picea sitchensis [Bong.] Carr.), a shoulder for the blue-green needles of Colorado spruce (Picea pungens Engelm.), and a reduced shoulder for the blue-white needles of Blue spruce (Picea pungens var. hoospii). These differences were attributable neither to a differential blue light stimulation of photorespiration nor to a differential presence of a nonplastid screening pigment. The conifers all had similar carotenoid-chlorophyll ratios, with approximately 50% more carotenoid relative to chlorophyll as compared to red alder. Blue light absorption and low efficiency of energy transfer by the carotenoids probably accounts for the low net photosynthetic activity of the green conifers in blue light as compared to red alder. Leaf form per se (broad versus needle) had no distinguishable influence on these results.

Journal Article↗

PubMed2004