High impact information on Amoeba

• Myosin II heavy chain (MHC)-specific protein kinase C (MHC-PKC) isolated from the ameba, Dictyostelium discoideum, regulates myosin II assembly and localization in response to the chemoattractant cAMP (Abu-Elneel et al. 1996. J. Biol. Chem. 271:977- 984) [1].
• We conclude that this ameba nonmuscle myosin shares with the muscle myosins of vertebrates and invertebrates an ancestral heavy chain gene [2].
• Purified antibodies to GP-260 reacted with both 260,000- and 240,000-mol-wt polypeptides in samples of whole ameba proteins separated by gel electrophoresis in SDS, but only the 260,000-mol-wt polypeptide was extracted from the cell with 0.34 M sucrose and purified in this study [3].
• Low concentrations of capping protein increased the critical concentration for muscle and ameba actin polymerization from 0.1 to 0.6 microM in Mg++ and EGTA [4].
• Ameba COX showed little homology with COX-1/2 enzymes from different species at the nucleotide and amino acid levels [5].

Biological context of Amoeba

• The initial step in the synthesis involves reductive alkylation of phenylglycine methyl esters with Ameba resin [6].
• Protection was dependent on the presence of the YopE translocation domain but was independent from the antibody response to the ameba lectin [7].
• Similar to higher animal cells, ameba cells of the cellular slime mold Dictyostelium discoideum form contractile rings containing filaments of myosin II during mitosis, and it is generally believed that contraction of these rings bisects the cells both on substrates and in suspension [8].
• Despite cathepsin B-like substrate specificities, all of the ameba polypeptides are structurally related to cathepsin L-like enzymes [9].

Anatomical context of Amoeba

• Previously a cloned emetine-resistant mutant of the protozoal parasite Entamoeba histolytica was shown to overexpress a gene for an ameba homolog of the mammalian P-glycoprotein, a plasma membrane pump that removes hydrophobic drugs from multidrug-resistant tumor cells [10].
• E. histolytica infection induced a cyclic depression of DNA synthesis when spleen lymphocytes were stimulated with a T-cell mitogen (Con A), a T- and B-cell (PWM) mitogen, or an ameba antigen [11].

Associations of Amoeba with chemical compounds

• PGE2 produced by ameba was constitutive but highly dependent on exogenous arachidonic acid substrate [5].
• In the ameba, dominant-negative mutations in the Gal/GalNAc lectin affect adhesion and cytolysis, whereas mutations in meromyosin affect cytoskeletal function [12].
• Similarly, the mortality rate for animals receiving tetracycline and amebas (60%) was higher than the mortality in the ameba controls (10%) (P equal 0.0286) [13].
• The mortality rate for those animals receiving methylprednisolone and amebas (50%) was found to be greater than the mortality in ameba controls (10%) (P equal 0.074) [13].
• Cyclic AMP (cAMP) appears to play multiple roles in the development of the social ameba Dictyostelium discoideum, serving as the chemoattractant mediating aggregation, and perhaps also regulating gene transcription in both early and late stages of differentiation [14].

Gene context of Amoeba

• The time-courses of expression differed slightly between the two ameba CHS genes, as in contrast to CHS-1 RNA, expression of CHS-2 RNA was more transient and no plateau was observed between 8 and 16 hours of encystation [15].
• Recently, we have established that N. fowleri expresses a "CD59-like" surface protein, but the function of this protein in the ameba has not been elucidated [16].
• Interestingly, male and female mice differed in early cytokine production in response to ameba infection [17].
• IFN-gamma inactivated at pH 2 had no effect on DNA synthesis by the ameba, thus suggesting that IFN-gamma is responsible for the observed inhibition of parasite growth [18].
• These results suggest that the antioxidant peroxiredoxin is important for protection against endogenously generated hydrogen peroxide in the nonpathogenic ameba [19].

Analytical, diagnostic and therapeutic context of Amoeba

• Molecular cloning techniques were used to isolate an ameba gene encoding a putative 33-kDa serine/thyronine-kinase [20].

References