The structure of FSTL3.activin A complex. Differential binding of N-terminal domains influences follistatin-type antagonist specificity

Transforming growth factor beta family ligands are neutralized by a number of structurally divergent antagonists. Follistatin-type antagonists, which include splice variants of follistatin (FS288 and FS315) and follistatin-like 3 (FSTL3), have high affinity for activin A but differ in their affinity for other ligands, particularly bone morphogenetic proteins. To understand the structural basis for ligand specificity within FS-type antagonists, we determined the x-ray structure of activin A in complex with FSTL3 to a resolution of 2.5 A. Similar to the previously resolved FS.activin A structures, the ligand is encircled by two antagonist molecules blocking all ligand receptor-binding sites. Recently, the significance of the FS N-terminal domain interaction at the ligand type I receptor site has been questioned; however, our data show that for FSTL3, the N-terminal domain forms a more intimate contact with activin A, implying that this interaction is stronger than that for FS. Furthermore, binding studies revealed that replacing the FSTL3 N-terminal domain with the corresponding FS domain considerably lowers activin A affinity. Therefore, both structural and biochemical evidence support a significant interaction of the N-terminal domain of FSTL3 with activin A. In addition, structural comparisons with bone morphogenetic proteins suggest that the interface where the N-terminal domain binds may be the key site for determining FS-type antagonist specificity.     

Phycobiliproteins as a commodity: trends in applied research,patents and commercialization

Phycobiliproteins are a group of colored proteins commonly present in cyanobacteria and red algae possessing a spectrum of applications. They are extensively commercialized for fluorescent applications in clinical and immunological analysis. They are also used as a colorant, and their therapeutic value has also been categorically demonstrated. However, a comprehensive knowledge and technological base for augmenting their commercial utilities is lacking. Hence, this work is focused towards this objective by means of analyzing global patents and commercial activities with application oriented research. Strategic mining of patents was performed from global patent databases resulting in the identification of 297 patents on phycobiliproteins. The majority of the patents are from USA, Japan and Europe. Patents are grouped into fluorescent applications, general applications and production aspects of phycobiliproteins and the features of each group are discussed. Commercial and applied research activities are compared in parallel. It revealed that US patents are mostly related to fluorescent applications while Japanese are on the production, purification and application for therapeutic and diagnostic purposes. Fluorescent applications are well represented in research, patents and commercial sectors. Biomedical properties documented in research and patents are not ventured commercially. Several novel applications are reported only in patents. The paper further pinpoints the plethora of techniques used for cell breakage and for extraction and purification of phycobiliproteins. The analysis identifies the lacuna and suggests means for improvements in the application and production of phycobiliproteins.     

The Natural Progression of Gambiense Sleeping Sickness: What Is the Evidence?

Gambiense human African trypanosomiasis (HAT, sleeping sickness) is widely assumed to be 100% pathogenic and fatal. However, reports to the contrary exist, and human trypano-tolerance has been postulated. Furthermore, there is uncertainty about the actual duration of both stage 1 and stage 2 infection, particularly with respect to how long a patient remains infectious. Understanding such basic parameters of HAT infection is essential for optimising control strategies based on case detection. We considered the potential existence and relevance of human trypano-tolerance, and explored the duration of infectiousness, through a review of published evidence on the natural progression of gambiense HAT in the absence of treatment, and biological considerations. Published reports indicate that most gambiense HAT cases are fatal if untreated. Self-resolving and asymptomatic chronic infections probably constitute a minority if they do indeed exist. Chronic carriage, however, deserves further study, as it could seed renewed epidemics after control programmes cease.     

Bacterial Growth Efficiency in the Tropical Estuarine and Coastal Waters of Goa,Southwest Coast of India

Bacterial growth efficiency (BGE) is an index of organic carbon passing through bacteria in an aquatic system. BGE values of natural bacterioplankton assemblages were measured in tropical estuarine and adjacent coastal waters in Goa along the southwest coast of India. The BGE values for estuarine and coastal waters were 18 (±7.84%) and 11 (±4.19%), respectively. BGE in these waters were at the lower end of what is usually found in productive systems. This may be due to the high respiration rates. Further, it was observed that grazers also influenced BGE. As BGE was positively correlated with bacterial productivity, the observed variation in BGE was attributed to bacterial productivity. BGE was inversely related to C:N ratio, indicating a close coupling between the nature of the substrates and BGE. Being system-dependent, the variations in BGE at the two locations were dynamic and were regulated by the quality of the substrates. Therefore, a constant value for BGE would lead to error in carbon budgets in these waters.     

Characterization of a rabbit kidney prostaglandin F(2{alpha}) receptor exhibiting G(i)-restricted signaling that inhibits water absorption in the collecting duct

PGF(2alpha) is the most abundant prostaglandin detected in urine; however, its renal effects are poorly characterized. The present study cloned a PGF-prostanoid receptor (FP) from the rabbit kidney and determined the functional consequences of its activation. Nuclease protection assay showed that FP mRNA expression predominates in rabbit ovary and kidney. In situ hybridization revealed that renal FP expression predominates in the cortical collecting duct (CCD). Although FP receptor activation failed to increase intracellular Ca(2+), it potently inhibited vasopressin-stimulated osmotic water permeability (L(p), 10(-7) cm/(atm.s)) in in vitro microperfused rabbit CCDs. Inhibition of L(p) by the FP selective agonist latanoprost was additive to inhibition of vasopressin action by the EP selective agonist sulprostone. Inhibition of L(p) by latanoprost was completely blocked by pertussis toxin, consistent with a G(i)-coupled mechanism. Heterologous transfection of the rabbit FPr into HEK293 cells also showed that latanoprost inhibited cAMP generation via a pertussis toxin-sensitive mechanism but did not increase cell Ca(2+). These studies demonstrate a functional FP receptor on the basolateral membrane of rabbit CCDs. In contrast to the Ca(2+) signal transduced by other FP receptors, this renal FP receptor signals via a PT-sensitive mechanism that is not coupled to cell Ca(2+).     

Mitochondrial dysfunction mediated apoptosis of HT-29 cells through CS-PAC-AgNPs and investigation of genotoxic effects in zebra (Danio rerio) fish model for drug delivery

The present study reports the validation of cancer nanotherapy using proanthocyanidin (PAC). Nowadays, in vitro and in vivo deliveries of nanoparticle (NPs) drugs have been paid more attention, intensively. Moreover, the current chemotherapeutic drugs have few first rate drawbacks including lack of specificity and requirement of excessive drug doses. To overcome this problem of chemotherapy, the attainment of high drug loading in combination with degradable polymer nanoparticles (for instance,chitosan) is a trending research in cancer biology. Hence, in this study, the synthesized PAC-AgNPs were successfully crosslinked with chitosan nanoparticles (CS-PAC-AgNPs), which were found to be spherical or polygonal in shape with a median size of 70.68 nm and 52.16 nm as observed by FTIR, FESEM and TEM analysis; thus, being suitable for drug delivery. CS-PAC-AgNPs were taken up via endocytosis by cancer cells and enabled the release cytochrome-C from mitochondria, followed by dysregulation of anti-apoptotic protein Bcl2 family, inducing the apoptotic mediated activation of caspase 9 and 3. To identify the genotoxicity of the synthesized CS-PAC-AgNPs, the mortality, hatching rate, malformation and abnormalities of embryo/larvae of the vertebrate zebra fish model (Danio rerio) were observed in a dose-time-dependent manner. This improved cancer nanotherapy can thus be utilized as a novel nanocombination for inducing apoptosis in vitro and in vivo.     

High confidence proteomic analysis of yeast LDs identifies additional droplet proteins and reveals connections to dolichol synthesis and sterol acetylation

Accurate protein inventories are essential for understanding an organelle’s functions. The lipid droplet (LD) is a ubiquitous intracellular organelle with major functions in lipid storage and metabolism. LDs differ from other organelles because they are bounded by a surface monolayer, presenting unique features for protein targeting to LDs. Many proteins of varied functions have been found in purified LD fractions by proteomics. While these studies have become increasingly sensitive, it is often unclear which of the identified proteins are specific to LDs. Here we used protein correlation profiling to identify 35 proteins that specifically enrich with LD fractions of Saccharomyces cerevisiae. Of these candidates, 30 fluorophore-tagged proteins localize to LDs by microscopy, including six proteins, several with human orthologs linked to diseases, which we newly identify as LD proteins (Cab5, Rer2, Say1, Tsc10, YKL047W, and YPR147C). Two of these proteins, Say1, a sterol deacetylase, and Rer2, a cis-isoprenyl transferase, are enzymes involved in sterol and polyprenol metabolism, respectively, and we show their activities are present in LD fractions. Our results provide a highly specific list of yeast LD proteins and reveal that the vast majority of these proteins are involved in lipid metabolism.