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131.
Maynard F. Moseley 《Brittonia》1973,25(4):356-370
Some of the important vegetative characters of amentiferous families described in research papers concerned with interfamilial relationships and published since 1947–1948 are briefly summarized. Important conclusions by the writers are also reviewed. Thus, Bataceae are considered derivatives of the Centrospermae ; Betulaceae, Casuarinaceae, and Ulmaceae are hamamelidaceous derivatives; Garryaceae and Cornaceae are closely related; and Julianiaceae and Anacardiaceae are plausible relatives. A more extensive tabulation of vegetative characters of essentially all amentiferous and ranalean families and Dilleniaceae is also presented, and the data are utilized to compare the percentages of advanced and primitive characters in these same taxa. The logic for considering trends whose evolutionary directions were initiated previous or incidental to angiospermous origin as more valid than other evolutionary trends is offered. The following principal conclusions are based upon the analysis of the tabulation: (1) the Amentiferae have sufficient advanced vegetative characters to preclude consideration of them as earliest angiosperms or their direct derivatives unless a large number of primitive features of other sorts offers strong counter evidence; (2) they also have sufficient primitive characters to discount the concept that they are highly evolved; (3) most Amentiferae clearly possess many more advanced vegetative characters than do most Magnoliales, Laurales, Trochodendrales, or Dilleniaceae ; and (4) relationships of several Amentiferae to various, unrelated angiospermous families have been demonstrated. 相似文献
132.
On the phospholipids of Bacillus megaterium 总被引:12,自引:0,他引:12
133.
Summary Tomato plants were cultured at various levels of rubidium and potassium in water culture. Growth as measured by dry-weight accumulation was reduced by the substitution of rubidium for potassium. The reduction in root growth was greater than the reduction in top growth; therefore, increased shoot/root values were noted with increasing rubidium concentration. In other experiments the potassium and rubidium content of the root and aerial portions were determined. It was found that rubidium tended to accumulate in the roots rather than the tops; it is postulated that this accumulation may be responsible for the observed inhibition of root growth. Potassium concentrations were similar in both the roots and tops indicating that the two cations did not behave similarly in these experiments.Contribution from the Massachusetts Agricultural Experiment Station, Amherst, Massachusetts. 相似文献
134.
135.
Phylogenetic screening of the human genome: identification of differentially hybridizing repetitive sequence families 总被引:1,自引:0,他引:1
The phi-screen, a method of phylogenetic screening, can be employed to
detect repetitive sequence families that differentially hybridize between
closely related species. Such differences may involve sequence divergence
or variations in copy number, including total presence versus absence of a
family of repeated DNA. We present the results of a phi-screen comparing
the human genome to that of the prosimian, Galago crassicaudatus. Three
human repetitive families that are divergent or not present in galago have
been detected. One of these families is described in detail; it is similar
among the anthropoids but is present in a lower copy number and/or
divergent form in prosimians. The family is clearly related to the
transposon-like human element (THE) described by Paulson et al. (1985).
THEs have long terminal repeats reminiscent of retroviruses but are unique
in that they have no sequence similarity to known mammalian retroviruses.
The sequence of a solo long terminal repeat, found unassociated with THE
internal sequence, is presented. This family member, THE p2, is bordered by
a 5-bp target-site repeat and is interrupted by the insertion of an Alu
element. A solo THE element sequenced by Wiginton et al. (1986) contains an
insertion of Alu at precisely the same position as does THE p2.
相似文献
136.
The alcohol dehydrogenase (Adh) region from five planitibia subgroup
species of Hawaiian picture-wing Drosophila has been cloned. A total of 15
kb of DNA in and around the Adh gene has been compared among the five
species. Genetic distances were calculated to determine evolutionary
relationships. These distances agree with previous distances determined by
protein polymorphism and DNA hybridization techniques and can be
interpreted in terms of specific island colonization and speciation
(founder) events over the past 5 Myr. Examination of the restriction maps
of the cloned Adh region from the five species shows many instances of
small deletions, insertion of a transposable element in D. heteroneura, and
the existence of a highly variable region on the 3' side of the Adh gene.
Clustering relationships and rates of DNA change are calculated and
compared with the relationship found for other species of Drosophila.
相似文献
137.
138.
Maynard Case 《Cell calcium》1984,5(4):419
139.
Maynard W. Quimby 《Economic botany》1953,7(1):89-92
Extensive investigation has shown that khellin, an active principle obtained from this plant, is of value in treating angina pectoris and bronchial asthma. 相似文献
140.
Rhea J. C. Levine Maynard M. Dewey David E. Colflesh 《The Journal of cell biology》1973,57(2):591-593