Endothelioma cells expressing the polyoma middle T oncogene induce hemangiomas by host cell recruitment

Mouse endothelioma cells expressing the polyoma middle T oncogene induced hemangiomas in a variety of species such as mice, rats, chicks, and quails. In embryos and newborn mice the hemangiomas expanded within 10-18 hr of injection, disrupting the vasculature and causing the death of the animal. In contrast, the hemangiomas formed a stable structure reminiscent of benign human hemangiomas in adult mice within 5 days. Analysis of the cells comprising the hemangioma revealed that over 95% of the endothelial cells were host derived. No induction of host cell proliferation was detected, and no endothelial mitogens were secreted by the endothelioma cells in vitro. The maintenance of the hemangioma appeared to require the continuous presence of endothelioma cells. The results indicate that these endothelioma cells act as a potent stimulating agent in the rapid formation of hemangiomas by recruiting nonproliferating host endothelial cells.     

Isolation and characterization of a large,neurite-associated glycoconjugate from neuroblastoma cells

A high molecular weight glycoconjugate has been isolated from neurite-producing neuronal tumor cells in culture and has been designated as I(0) based on its elution characteristics in gel filtration chromatography. This molecule cannot be found in a variety of nonneuronal cells. I(0) is found in the substratum-attached material or cell fraction of neurite-producing neuroblastoma cells, depending upon culture conditions. It is found in the substratum-bound fraction of B104 rat neuroblastoma cells during serum starvation and in the EGTA-detached cell fraction of B104 cells grown in chemically defined N2 medium. It occurs only in the cell fraction of the human neuroblastoma line Platt. Examination of behavioral variants of the B104 rat line further strengthens the association of I(0) with neurite production; the constitutive neurite-producing E(R)B9 variant contains I(0) while the non-neurite-producing E(R)A11 variant does not. I(0) is large, eluting in the void volume of sepharose-CL2B columns. Radioiodination of intact cells with lactoperoxidase shows I(0) to be a cell surface component. Metabolic radiolabeling studies show that it contains a high proportion of polysaccharide to protein, does not contain mannose, and is unsulfated. Alkaline borohydride reduction release two size classes of large polysaccharide chain. The alkaline reduction results, along with the mannose incorporation studies, show the presence of O-glycosidic linkages and few, if any, N-linkages. Resistance to nitrous acid deamination, insensitivity to glycosaminoglycan lyases, and the absence of sulfation, indicate that I(0) does not contain the glycosaminoglycans hyaluronic acid, chondroitin-, dermatan-, or heparin- sulfates. Affinity column chromatography reveals high binding affinity of I(0) to polyornithine and no binding to gelatin (collagen) or the glycosaminoglycans hyaluronate and heparin. These studies describe a unique high molecular weight glycoconjugate on the surface of neurite-producing neuroblastoma cell lines from two species.     

Nature of Escherichia coli B(P1) Yielder Cells at the Time of Infection with Restricted T1

In the infection of Escherichia coli B(P1) with restricted T1, it was shown that yielder cells consist of both special and nonspecial cells. Special or predetermined yielders occurred only among the earliest yielders. In most instances, yielder-cell formation was most easily explained by assuming that the first step was a chance escape of the restricted phage DNA from the degrading enzyme of the restricting cell.     

Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal

We have developed a new approach to the measurement of phylogenetic signal in character state matrices called relative apparent synapomorphy analysis (RASA). RASA provides a deterministic, statistical measure of natural cladistic hierarchy (phylogenetic signal) in character state matrices. The method works by determining whether a measure of the rate of increase of cladistic similarity among pairs of taxa as a function of phenetic similarity is greater than a null equiprobable rate of increase. Our investigation of the utility and limitations of RASA using simulated and bacteriophage T7 data sets indicates that the method has numerous advantages over existing measures of signal. A first advantage is computational efficiency. A second advantage is that RASA employs known methods of statistical inference, providing measurable sensitivity and power. The performance of RASA is examined under various conditions of branching evolution as the number of characters, character states per character, and mutations per branch length are varied. RASA appears to provide an unbiased and reliable measure of phylogenetic signal, and the general approach promises to be useful in the development of new techniques that should increase the rigor and reliability of phylogenetic estimates.      

Experimental and computational analysis of the ancestry of an evolutionary young enzyme from histidine biosynthesis

The conservation of fold and chemistry of the enzymes associated with histidine biosynthesis suggests that this pathway evolved prior to the diversification of Bacteria, Archaea, and Eukaryotes. The only exception is the histidinol phosphate phosphatase (HolPase). So far, non-homologous HolPases that possess distinct folds and belong to three different protein superfamilies have been identified in various phylogenetic clades. However, their evolution has remained unknown to date. Here, we analyzed the evolutionary history of the HolPase from γ-Proteobacteria (HisB-N). It has been argued that HisB-N and its closest homologue d -glycero-d -manno-heptose-1,7-bisphosphate 7-phosphatase (GmhB) have emerged from the same promiscuous ancestral phosphatase. GmhB variants catalyze the hydrolysis of the anomeric d -glycero-d -manno-heptose-1,7-bisphosphate (αHBP or βHBP) with a strong preference for one anomer (αGmhB or βGmhB). We found that HisB-N from Escherichia coli shows promiscuous activity for βHBP but not αHBP, while βGmhB from Crassaminicella sp. shows promiscuous activity for HolP. Accordingly, a combined phylogenetic tree of αGmhBs, βGmhBs, and HisB-N sequences revealed that HisB-Ns form a compact subcluster derived from βGmhBs. Ancestral sequence reconstruction and in vitro analysis revealed a promiscuous HolPase activity in the resurrected enzymes prior to functional divergence of the successors. The following increase in catalytic efficiency of the HolP turnover is reflected in the shape and electrostatics of the active site predicted by AlphaFold. An analysis of the phylogenetic tree led to a revised evolutionary model that proposes the horizontal gene transfer of a promiscuous βGmhB from δ- to γ-Proteobacteria where it evolved to the modern HisB-N.     

Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability

We have analyzed nucleic acid and amino acid sequence alignments of a variety of voltage-sensitive ion channels, using several methods for phylogenetic tree reconstruction. Ancient duplications within this family gave rise to three distantly related groups, one consisting of the Na+ and Ca++ channels, another the K+ channels, and a third including the cyclic nucleotide-binding channels. A series of gene duplications produced at least seven mammalian homologues of the Drosophila Shaker K+ channel; clones of only three of these genes are available from all three mammalian species examined (mouse, rat, and human), pointing to specific genes that have yet to be recovered in one or another of these species. The Shaw-related K+ channels and the Na+ channel family have also undergone considerable expansion in mammals, relative to flies. These expansions presumably reflect the needs of the high degree of physiological and neuronal complexity of mammals. Analysis of the separate domains of the four-domain channels (Ca++ and Na+) supports their having evolved by two sequential gene duplications and implies the historical existence of a functional two-domain channel.      

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.