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271.
A. Turner 《Human Evolution》1986,1(5):419-430
Human evolution is considered from the perspective of the recognition concept of species, which views species as an epiphenomenon
of shared fertilisation systems in sexually reproducing organisms. It is argued that this concept predicts the controversial
pattern of punctuated equilibrium, and offers an understanding of the hominid fossil evidence in line with that pattern. Changes
in the nature of the fertilization system in the human lineage over time are discussed in relation to the pattern of morphological
continuity between proposed species. 相似文献
272.
273.
Summary The mouse peritoneal macrophage has a prominent cell coat, clearly demonstrated by ruthenium red staining, probably containing significant amounts of acidic mucosubstances and tightly adherent to the cell membrane. Aldehyde-fixed autologous red cells are recognized at the level of a protein layer which can be readily removed without removing the cell coat.We are grateful to Professor R. Barer for his advice and criticism. The work was supported by a grant from the Medical Research Council. The three junior authors took part in this project as part of the B. Sc. Honours course in the Department. Much of the technical work was carried out by Miss Anne Edwards. 相似文献
274.
DNA replication has been reconstituted in vitro with yeast proteins, and the minimal system requires the coordinated assembly of 16 distinct replication factors, consisting of 42 polypeptides. To understand the molecular interplay between these factors at the single residue level, new structural biology tools are being developed. Inspired by advances in single-molecule fluorescence imaging and cryo-tomography, novel single-particle cryo-EM experiments have been used to characterise the structural mechanism for the loading of the replicative helicase. Here, we discuss how in silico reconstitution of single-particle cryo-EM data can help describe dynamic systems that are difficult to approach with conventional three-dimensional classification tools. 相似文献
275.
The Recognition Concept of Species is examined for its potential usefulness in discriminating speciation events in the hominid
fossil record. Controversies over species-specific characteristics amongHomo erectus and archaicHomo sapiens have centred on traits of the skull, largely because this element is most commonly preserved. Modern humans have an intuitive
knowledge of their own Specific Mate Recognition System (SMRS), and therefore have the opportunity to compare their own SMRS
to that of fossil hominids and the extent pongids. Such comparison suggests that our own skeletal SMRS may depend less on
features of the skull than on the morphology of the postcranial anatomy. We propose that these components be further examined
in this regard. We tentatively conclude that examination of the Recognition Concept of Species indicates that from lateHomo erectus onwards, the same SMRS has been shared in common by all hominids, including modernHomo sapiens. This suggests that, following the SMRS criterion, none of these forms can be categorized as separate species. 相似文献