Mitogenomic phylogeny of Acanthocephala reveals novel Class relationships

The Acanthocephala is a phylum of obligate endoparasitic animals comprising four classes (Archiacanthocephala, Palaeacanthocephala, Eoacanthocephala and Polyacanthocephala), although the phylogenetic interrelationships of these classes still remains unresolved. To investigate phylogenetic relationships of major acanthocephalan groups, we characterized the complete mitochondrial genome sequences of two palaeacanthocephalan species Centrorhynchus aluconis and Prosthorhynchus transversus (representing two different families of the order Polymorphida), and Polyacanthorhynchus caballeroi (the first mitogenomic representative of the class Polyacanthocephala) and used these new sequences for phylogenetic analyses, along with 32 platyzoan mtDNAs, including 10 additional acanthocephalans. Phylogenetic analyses using concatenated amino acid sequences for 12 protein‐coding genes with maximum likelihood and Bayesian inference methods supported monophyly of Acanthocephala. Within the phylum, Archiacanthocephala was positioned as the sister to the clade containing all three other acanthocephalan classes, with the polyacanthocephalan species P. caballeroi nested within Eoacanthocephala. This result contradicts morphology‐based classification systems that treated polyacanthorhynchids as one of the palaeacanthocephalan families, and instead suggests Polyacanthocephala is a member of Eoacanthocephala. Within the Palaeacanthocephala, Polymorphida monophyly was strongly supported and this is inconsistent with nuclear rDNA‐based molecular hypotheses that suggest non‐monophyly.     

Specificity and promiscuity in human glutaminase interacting protein recognition: insight from the binding of the internal and C-terminal motif

A large number of cellular processes are mediated by protein-protein interactions, often specified by particular protein binding modules. PDZ domains make up an important class of protein-protein interaction modules that typically bind to the C-terminus of target proteins. These domains act as a scaffold where signaling molecules are linked to a multiprotein complex. Human glutaminase interacting protein (GIP), also known as tax interacting protein 1, is unique among PDZ domain-containing proteins because it is composed almost exclusively of a single PDZ domain rather than one of many domains as part of a larger protein. GIP plays pivotal roles in cellular signaling, protein scaffolding, and cancer pathways via its interaction with the C-terminus of a growing list of partner proteins. We have identified novel internal motifs that are recognized by GIP through combinatorial phage library screening. Leu and Asp residues in the consensus sequence were identified to be critical for binding to GIP through site-directed mutagenesis studies. Structure-based models of GIP bound to two different surrogate peptides determined from nuclear magnetic resonance constraints revealed that the binding pocket is flexible enough to accommodate either the smaller carboxylate (COO(-)) group of a C-terminal recognition motif or the bulkier aspartate side chain (CH(2)COO(-)) of an internal motif. The noncanonical ILGF loop in GIP moves in for the C-terminal motif but moves out for the internal recognition motifs, allowing binding to different partner proteins. One of the peptides colocalizes with GIP within human glioma cells, indicating that GIP might be a potential target for anticancer therapeutics.     

The ultrastructural indicators of aquatic ecosystem health

Analyses by transmission electron microscopy (TEM) of the smallest organisms in surface waters can be used to assess ecosystem health; the evidence for this statement is reviewed and recommendations are made for optimal use of TEM technology in providing such assessments. Those groups of small organisms currently being considered as indicators of ecosystem health (viruses, bacteria, autotrophic picoplankton, and autotrophic nanoplankton) are reviewed briefly as subjects for monitoring by TEM. New information on direct counting by TEM of viral femtoplankton indicates that viruses can be present in numbers 10³ to 10⁷ times greater than previously estimated by the traditional counts of plaque-forming units using various host bacteria. Such concentrations indicate that virus infections may exert ecological control over planktonic microbes. Ultrastructural research on prokaryotic picoplankton suggests that TEM analyses of cells in ultra-thin sections can be used to speciate the picoplankton and to diagnose them for cytological modifications related to environmental stress. Considering their great importance, episodically, to primary productivity and to modulating the speciation of higher levels in the food web, such picoplankton ultrastructural analyses could be pursued with profit as a diagnostic tool. For decades, the ultrastructure of some eukaryotic nanoplankton has been known to vary in specific ways to specific stresses in laboratory experiments. An extension of these structure-function correlations is potentially a useful tool to provide indicators of ecosystem health. The barriers to progress in such research are now understood and can be overcome.     

Functional dendritic polymer architectures as stimuli-responsive nanocarriers

Stimuli-responsive polymer architectures are molecular systems which evolve with an external signal. The observed changes are mainly decomposition, isomerization, polymerization, activation, supramolecular aggregation, and structural modifications of these molecules. The external stimuli, which can be combined in order to provoke these molecular changes, are numerous. In this review, we have chosen to present an overview on different mechanisms to impart responsiveness to dendritic polymers, with the particular aim of delivery and release of bioactive molecules.     

The Planktonic Index of Biotic Integrity (P-IBI): An approach for assessing lake ecosystem health

Using historical (1970) and more recent (1996) Lake Erie plankton and trophic status data, we developed a Planktonic Index of Biotic Integrity (P-IBI) to measure changes in lake ecosystem health. We used discriminant analysis to determine phytoplankton and zooplankton community characteristics (metrics) that distinguished among levels of impairment. Traditional measures of lake trophic status classes (i.e., oligotrophic, mesotrophic, eutrophic), such as chlorophyll a and total phosphorus concentrations, were used to classify sites on a gradient of impairment. We then judged the ability of plankton metrics to distinguish among trophic status classes. Because of the temporal variability found in plankton communities, we conducted analyses on a monthly basis (May–September). For June, July and August we found five unique metrics that could distinguish among trophic status classes. The P-IBI showed an increase in water quality in Lake Erie between 1970 (<3 = eutrophic) and the mid-1990s (1996 and 1997) (3–4 = mesotrophic) (which reflected mean (±standard error) total phosphorus concentrations (μg/L) 1970 > 1996; western basin (41.53 ± 2.68 > 29.75 ± 1.39), eastern basin (14.84 ± 0.82 > 7.74 ± 0.28) and mean (±standard error) chlorophyll a concentrations (μg/L) uncorrected for pheophytin 1970 > 1996; western basin (12.58 ± 1.82 > 5.40 ± 0.22), central basin (5.90 ± 0.36 > 3.17 ± 0.54), and eastern basin (5.17 ± 0.38 > 1.67 ± 0.18)), with declining water quality in the late 1990s (1998 and 1999) (3) and 2002 (<3). We recommend that the techniques used in creating the P-IBI be investigated for determining ecosystem health of other lakes.     

Curcumin inhibits ultraviolet light induced human immunodeficiency virus gene expression

Recently, we reported that the herbal drug St. John's Wort is a potent inhibitor of UV-induced HIV-LTR activation in stably transfected HIVcat/HeLa cells [35]. Our previous studies have demonstrated that the activation of p38 MAP kinase (stress-activated protein kinase-2) and NF-B are both required for a full UV-induced HIV gene expression response. In this study we have investigated the mechanism by which curcumin inhibits UV-activated HIV-LTR gene expression. We found that treatment of HIVcat/HeLa cells with micromolar concentrations of curcumin completely abolished UV activation of HIV gene expression. Curcumin treatment at similar doses as those used to inhibit HIV gene expression also effectively blocked UV activation of NF-B, as demonstrated by electrophoretic mobility shift assay. In contrast, curcumin did not inhibit UV-induced phosphorylation of p38 MAP kinase. This observation was also supported by findings that curcumin did not inhibit UV-induced phosphorylation of CREB/ATF-1 and ATF-2. Although curcumin was ineffective in preventing UV-induced p44/42 MAP kinase phosphorylation, the JNK (1 and 2) and AP-1 activation were efficiently blocked by curcumin in HeLa cells. We conclude that the mechanism by which curcumin modulates UV activation of HIV-LTR gene expression mainly involves the inhibition of NF-B activation.     

Exogenous thermospermine has an activity to induce a subset of the defense genes and restrict cucumber mosaic virus multiplication in Arabidopsis thaliana

We previously proposed the defensive role of a signal pathway triggered by the polyamine spermine (Spm) in the reaction against avirulent viral pathogens in Nicotiana tabacum and Arabidopsis thaliana. In this study, we showed that thermospermine (T-Spm), an isomer of Spm, is also active in inducing the expression of the genes involved in the Spm-signal pathway at a similar dose as Spm. Furthermore, we found that T-Spm enhances the expression of a subset of pathogenesis-related genes whose expression is induced during cucumber mosaic virus (CMV)-triggered hypersensitive response. In consistent with the above observation, we further showed that exogenous T-Spm can repress CMV multiplication with same efficiency as Spm. KEY MESSAGE: Polyamine thermospermine, an isomer of spermine, is able to induce a subset of hypersensitive response-related defense genes and can suppress cucumber mosaic virus multiplication in Arabidopsis thaliana.