Multiple Phenotypic Changes Associated with Large-Scale Horizontal Gene Transfer

Horizontal gene transfer often leads to phenotypic changes within recipient organisms independent of any immediate evolutionary benefits. While secondary phenotypic effects of horizontal transfer (i.e., changes in growth rates) have been demonstrated and studied across a variety of systems using relatively small plasmids and phage, little is known about the magnitude or number of such costs after the transfer of larger regions. Here we describe numerous phenotypic changes that occur after a large-scale horizontal transfer event (∼1 Mb megaplasmid) within Pseudomonas stutzeri including sensitization to various stresses as well as changes in bacterial behavior. These results highlight the power of horizontal transfer to shift pleiotropic relationships and cellular networks within bacterial genomes. They also provide an important context for how secondary effects of transfer can bias evolutionary trajectories and interactions between species. Lastly, these results and system provide a foundation to investigate evolutionary consequences in real time as newly acquired regions are ameliorated and integrated into new genomic contexts.     

Histamine stimulates calcium-mediated protein phosphorylation in a colonic epithelial cell line

Protein phosphorylation responses in intact enterocytes were examined by stimulating 32Pi-labeled T84 cell monolayers with histamine and resolving proteins by two-dimensional gel electrophoresis. Histamine increases 32P-incorporation into two acidic proteins of Mr 83,000 and of Mr 29,000, designated p83 and p29. Labeling of p83 and p29 is also increased in cells exposed to ionomycin, but not in cells exposed to vasoactive intestinal peptide under conditions resulting in cAMP-mediated secretion and cAMP-stimulated protein phosphorylation. When T84 cell fractions are incubated with [gamma-32P]ATP, labeling of p83 is stimulated by Ca++, but not by cAMP. Thus, histamine stimulates Ca++-mediated protein phosphorylation during the regulation of Cl- secretion.     

Transforming growth factor-beta is a potent immunosuppressive agent that inhibits IL-1-dependent lymphocyte proliferation

Transforming growth factor-beta (TGF-beta), a product of neoplastic and hemopoietic cells, is a bifunctional regulator of the immune response. At femtomolar concentrations, TGF-beta stimulates monocyte migration, and picomolar quantities induce synthesis of monocyte growth factors, including IL-1, that may promote tissue repair by regulating fibrosis and angiogenesis. Paradoxically, TGF-beta at picomolar concentrations also blocks the ability of IL-1 to stimulate lymphocyte proliferation. At 0.01 to 1.0 ng/ml, TGF-beta 1 and its homologue, TGF-beta 2, suppress the IL-1-dependent murine thymocyte proliferation assay. TGF-beta also inhibits human peripheral blood T lymphocyte mitogenesis. Inhibition of cell division appears to occur after activation of the lymphocytes inasmuch as neither gene expression nor translation of IL-2R is suppressed. Furthermore, TGF-beta does not block synthesis of IL-2. Therefore, TGF-beta 1 and TGF-beta 2 likely act at a site distal to IL-1 to block lymphocyte DNA synthesis. These findings suggest that TGF-beta secreted in an inflammatory site may be beneficial in diminishing lymphocyte function while promoting fibrosis and tissue repair. However, TGF-beta generated by neoplastic tissues may provide a mechanism for unrestricted tumor cell growth through its selective immunosuppressive effects.     

Characterization of purified avian 90,000-Da heat shock protein

The so-called 90,000-Da heat shock protein (hsp90) from chicken liver has been purified and physically characterized in the presence of high levels of the serine phosphatase inhibitor fluoride. The protein is an elongated dimer with a molecular weight of 160,000 and a frictional ratio of 1.6. On two-dimensional electrophoresis it exhibits several isoelectric forms lying between pH 5.1 and 5.8. It contains an average of 5.8 mol of covalently bound phosphate per dimer and is thus extensively phosphorylated. Analysis of the ultraviolet spectrum showed the purified protein to be free of nucleotide-containing components. Molybdate has been shown to stabilize complexes between the 90,000-Da heat shock protein and steroid receptors. However, molybdate has no effect on the sedimentation of the purified heat shock protein. Proteins structurally related to hsp90 have been reported to penetrate the endoplasmic reticulum. However, when purified hsp90 was tested using the partition method of Bordier, which distinguishes hydrophilic and lipophilic proteins, it partitioned totally into the aqueous phase.     

The effect of alpha-interferon, cyclosporine A, and radiation-induced immune suppression on morphine-induced hypothermia and tolerance

An interconnection between the immune and the central nervous systems has been suggested by investigators studying the actions of several types of immune modifying agents and procedures upon opiate related phenomena. These studies have included the effects of altering immune system function by administration of either alpha-interferon, cyclosporine or radiation exposure upon naloxone-precipitated opiate withdrawal and upon opioid antinociceptive effects. The present study extends these earlier investigations by examining the effect of immune modulation upon opiate induced hypothermia. The results demonstrate that interferon and cyclosporine have no effects on baseline temperature or morphine induced hypothermia, while irradiation exposure elicits hyperthermia without affecting morphine-induced hypothermia. Finally, neither cyclosporine nor irradiation affect the development of tolerance to morphine induced hypothermia, while a single injection of the immune system modifier interferon was able to prevent the development of such tolerance. These observations suggest that yet another opiate-related phenomenon may be regulated at least in part by the immune system. These results together with our previous findings are further evidence of a link between the immune system and the CNS mediated through the opioid system. In addition, these studies further support our earlier hypothesis that "Interferon" is one of the endogenous substances which serves to prevent the development of tolerance and dependence to endogenous opioids.     

Morphogenesis of Newcastle Disease Virus in Chorioallantoic Membrane

Chick embryo chorioallantoic membrane, infected with the Blacksburg strain of Newcastle disease virus, was examined with an electron microscope to investigate the sequence of viral-induced host cell alterations. These were evident mostly in the endodermal epithelial cells lining the allantoic sac and were divided arbitrarily into three stages. Stage 1 was characterized by commencement of cell hypertrophy and hyperplasia and presence of fewer cytoplasmic inclusion bodies normally found in the cells; in stage 2, juxtanuclear nucleocapsid-glycogen aggregates appeared, and there were increased numbers of microvilli; stage 3 was characterized by increased cytoplasmic density and evidence of viral assembly and release. The morphological features of viral assembly and the virion are also described.