Applications of proteomic methodologies to human pregnancy research: a growing gestation approaching delivery?

Maternal and perinatal morbidity and mortality rates are significantly higher in pregnancies complicated by preterm labor, pre-eclampsia and fetal growth restriction. Decades of research have not translated into a clear understanding of the underlying pathophysiologies or effective identification of women who are at high risk of developing these complications. Often the severity of these diseases does not correlate with the clinical symptoms, and current diagnostic methods are unable to accurately predict the conditions prior to clinical presentation. Though several potential markers have been proposed for each of these disorders, to date none have proven clinical utility. Emerging proteomic technology is only beginning to be employed in pregnancy research. A comprehensive analysis of gestational tissues can be expected to contribute to the elucidation of the complex molecular mechanisms of pregnancy and related complications. Comparison of the expression profiles of normal and pathogenic tissues and biofluids may also highlight novel candidate marker proteins that have so far remained undetected. More interestingly, rapidly evolving technologies using sophisticated bioinformatic tools are demonstrating their potential in disease diagnostics by using overall protein profiles to detect diseases. The clinical significance of these methodological advances is enormous. Early diagnosis together with improved understanding of underlying molecular mechanisms can enhance outcomes and increase effective management and therapeutic options.     

Plant parasite control and soil fauna diversity

The use of pesticides to control plant parasites and diseases has generated serious problems of public health and environmental quality, leading to the promotion of alternative Integrated Pest Management strategies that tend to rely more on natural processes and the active participation of farmers as observers and experimenters in their own fields. We present three case studies that point at different options provided by locally available populations of soil organisms, the maintenance of diverse populations of pests or increased resistance of plants to pest attacks by their interactions with earthworms and other useful soil organisms. These examples demonstrate the diversity of options offered by the non-planned agro-ecosystem diversity in pest control and the need to identify management options that maintain this biodiversity.     

Effects of short-term chemical ablation of the GIP receptor on insulin secretion, islet morphology and glucose homeostasis in mice

Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone secreted by endocrine K-cells in response to nutrient absorption. In this study we have utilized a specific and enzymatically stable GIP receptor antagonist, (Pro3)GIP, to evaluate the contribution of endogenous GIP to insulin secretion and glucose homeostasis in mice. Daily injection of (Pro3)GIP (25 nmol/kg body weight) for 11 days had no effect on food intake or body weight. Non-fasting plasma glucose concentrations were significantly raised (p<0.05) by day 11, while plasma insulin concentrations were not significantly different from saline treated controls. After 11 days, intraperitoneal glucose tolerance was significantly impaired in the (Pro3)GIP treated mice compared to control (p<0.01). Glucose-mediated insulin secretion was not significantly different between the two groups. Insulin sensitivity of 11-day (Pro3)GIP treated mice was slightly impaired 60 min post injection compared with controls. Following a 15 min refeeding period in 18 h fasted mice, food intake was not significantly different in (Pro3)GIP treated mice and controls. However, (Pro3)GIP treated mice displayed significantly elevated plasma glucose levels 30 and 60 min post feeding (p<0.05, in both cases). Postprandial insulin secretion was not significantly different and no changes in pancreatic insulin content or islet morphology were observed in (Pro3)GIP treated mice. The observed biological effects of (Pro3)GIP were reversed following cessation of treatment for 9 days. These data indicate that ablation of GIP signaling causes a readily reversible glucose intolerance without appreciable change of insulin secretion.     

Increased zinc content in transplastomic tobacco plants expressing a polyhistidine-tagged Rubisco large subunit

Rubisco is a hexadecameric enzyme composed of two subunits: a small subunit (SSU) encoded by a nuclear gene (rbcS), and a large subunit (LSU) encoded by a plastid gene (rbcL). Due to its high abundance, Rubisco represents an interesting target to express peptides or small proteins as fusion products at high levels. In an attempt to modify the plant metal content, a polyhistidine sequence was fused to Rubisco, the most abundant protein of plants. Plastid transformation was used to express a polyhistidine (6x) fused to the C-terminal extremity of the tobacco LSU. Transplastomic tobacco plants were generated by cotransformation of polyethylene glycol-treated protoplasts using two vectors: one containing the 16SrDNA marker gene, conferring spectinomycin resistance, and the other the polyhistidine-tagged rbcL gene. Homoplasmic plants containing L8-(His)6S8 as a single enzyme species were obtained. These plants contained normal Rubisco amounts and activity and displayed normal photosynthetic properties and growth. Interestingly, transplastomic plants accumulated higher zinc amounts than the wild-type when grown on zinc-enriched media. The highest zinc increase observed exceeded the estimated chelating ability of the polyhistidine sequence, indicating a perturbation in intracellular zinc homeostasis. We discuss the possibility of using Rubisco to express foreign peptides as fusion products and to confer new properties to higher plants.     

Cancer characterization and feature set extraction by discriminative margin clustering

Background  

A central challenge in the molecular diagnosis and treatment of cancer is to define a set of molecular features that, taken together, distinguish a given cancer, or type of cancer, from all normal cells and tissues.     

Inversion leads to quantitative, not qualitative, changes in face processing

Humans are remarkably adept at recognizing objects across a wide range of views. A notable exception to this general rule is that turning a face upside down makes it particularly difficult to recognize. This striking effect has prompted speculation that inversion qualitatively changes the way faces are processed. Researchers commonly assume that configural cues strongly influence the recognition of upright, but not inverted, faces. Indeed, the assumption is so well accepted that the inversion effect itself has been taken as a hallmark of qualitative processing differences. Here, we took a novel approach to understand the inversion effect. We used response classification to obtain a direct view of the perceptual strategies underlying face discrimination and to determine whether orientation effects can be explained by differential contributions of nonlinear processes. Inversion significantly impaired performance in our face discrimination task. However, surprisingly, observers utilized similar, local regions of faces for discrimination in both upright and inverted face conditions, and the relative contributions of nonlinear mechanisms to performance were similar across orientations. Our results suggest that upright and inverted face processing differ quantitatively, not qualitatively; information is extracted more efficiently from upright faces, perhaps as a by-product of orientation-dependent expertise.     

Pythons metabolize prey to fuel the response to feeding

We investigated the energy source fuelling the post-feeding metabolic upregulation (specific dynamic action, SDA) in pythons (Python regius). Our goal was to distinguish between two alternatives: (i) snakes fuel SDA by metabolizing energy depots from their tissues; or (ii) snakes fuel SDA by metabolizing their prey. To characterize the postprandial response of pythons we used transcutaneous ultrasonography to measure organ-size changes and respirometry to record oxygen consumption. To discriminate unequivocally between the two hypotheses, we enriched mice (= prey) with the stable isotope of carbon (13C). For two weeks after feeding we quantified the CO2 exhaled by pythons and determined its isotopic 13C/12C signature. Ultrasonography and respirometry showed typical postprandial responses in pythons. After feeding, the isotope ratio of the exhaled breath changed rapidly to values that characterized enriched mouse tissue, followed by a very slow change towards less enriched values over a period of two weeks after feeding. We conclude that pythons metabolize their prey to fuel SDA. The slowly declining delta13C values indicate that less enriched tissues (bone, cartilage and collagen) from the mouse become available after several days of digestion.     

Plastid-targeting peptides from the chlorarachniophyte Bigelowiella natans

Chlorarachniophytes are marine amoeboflagellate protists that have acquired their plastid (chloroplast) through secondary endosymbiosis with a green alga. Like other algae, most of the proteins necessary for plastid function are encoded in the nuclear genome of the secondary host. These proteins are targeted to the organelle using a bipartite leader sequence consisting of a signal peptide (allowing entry in to the endomembrane system) and a chloroplast transit peptide (for transport across the chloroplast envelope membranes). We have examined the leader sequences from 45 full-length predicted plastid-targeted proteins from the chlorarachniophyte Bigelowiella natans with the goal of understanding important features of these sequences and possible conserved motifs. The chemical characteristics of these sequences were compared with a set of 10 B. natans endomembrane-targeted proteins and 38 cytosolic or nuclear proteins, which show that the signal peptides are similar to those of most other eukaryotes, while the transit peptides differ from those of other algae in some characteristics. Consistent with this, the leader sequence from one B. natans protein was tested for function in the apicomplexan parasite, Toxoplasma gondii, and shown to direct the secretion of the protein.