A serotonergic system in the brain of the Antarctic fish, Trematomus bernacchii

The immunohistochemical distribution of serotonin-containing nerve fibres and cells has been described in the brain of the Antarctic fish, Trematomus bernacchii. The largest serotonergic system was associated with the diencephalic and rhombencephalic ventricles. In particular, serotonin-positive cells have been found in the lateral recess and neuropile zone of the diencephalic ventricle, where we have identified the serotonergic portion of the paraventricular organ. Numerous serotonin cells were localized in the dorsal nucleus of the raphe, the dorsal tegmental nucleus and the central gray. Two large cell groups, arranged in a pair of well-defined columns and connecting the central gray with the dorsal reticular formation, were immunostained in the region of the trigeminal nuclei. In addition, few positive cells have been found in the preoptic area and the cerebellar valvula, and few serotonergic nerve fibres, probably belonging to the lateral lemniscus, have been identified. The distribution of serotonin elements in the brain of T. bernacchii has been compared with that described in other fish, where it showed some modifications in the immunoreactive pattern. Finally, the lack of a serotonergic system at the level of the reticular superior formation has been reported; however, it was not possible to rule out a phylogenetic or environmental explanation.     

Multiple attractors,catastrophes and chaos in seasonally perturbed predator-prey communities

A classical predator-prey model is considered in this paper with reference to the case of periodically varying parameters. Six elementary seasonality mechanisms are identified and analysed in detail by means of a continuation technique producing complete bifurcation diagrams. The results show that each elementary mechanism can give rise to multiple attractors and that catastrophic transitions can occur when suitable parameters are slightly changed. Moreover, the two classical routes to chaos, namely, torus destruction and cascade of period doublings, are numerically detected. Since in the case of constant parameters the model cannot have multiple attractors, catastrophes and chaos, the results support the conjecture that seasons can very easily give rise to complex populations dynamics.     

Adsorption of chitosan on PET films monitored by quartz crystal microbalance

The adsorption behavior of chitosan on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance (QCM) technique. QCM with a dissipation unit (QCM-D) represents a very sensitive technique for adsorption studies at the solid/liquid interface in situ, with capability of detecting a submonolayer of adsorbate on the quartz crystal surface. Chitosan as well as PET were chosen for this study due to their promising biocompatible properties and numerous possibilities to be used in biomedical applications. As a first step, PET foils were activated by alkaline hydrolysis in order to increase their hydrophilicity. Model thin films were prepared from PET foils by the spin coating technique. The chemical composition of the obtained model PET films was analyzed using X-ray photoelectron spectroscopy (XPS) and their morphology was characterized by atomic force microscopy (AFM). Furthermore, the adsorption behavior of chitosan on these activated PET films and the influence of adsorption parameters (pH, ionic strength and chitosan solution concentration) were investigated in detail. Additionally, the surface chemistry and morphology of the PET films and the chitosan coated PET films were analyzed with XPS and AFM.     

The role of monocyte/macrophages as vehicles of dissemination of Simkania negevensis: an in vitro simulation model

Exposure to Simkania negevensis (Sn), an intracellular microorganism that has been associated with respiratory tract infections in infants and adults, is prevalent. Sn can multiply within free-living amoebae and has been detected in domestic water supplies, which may constitute a source of infection with the organism. Its path of transport from its portal of entry to the body to its target organs is unknown. In this study, the possibility that monocytes/macrophages may serve as vehicles of transmission was examined. In vitro cocultivation of Sn-infected Acanthamoeba polyphaga with the monocyte/macrophage cell line U937 resulted in the death of the amoebae and infection of the U937 cells. Sn entered and multiplied in U937 cells within short periods of time, and the microorganism could be transferred from U937 cells to cell cultures of various origins. Uninfected monocyte/macrophages could become infected when in contact with either actively or persistently Sn-infected cell cultures. Persistently infected cultures in contact with uninfected U937 cells became actively infected. The results of this study provide a basis for determination of the molecular mechanisms of monocyte/macrophage-cell interactions in transfer of infection and may contribute to a better understanding of the pathogenesis of Sn infections in vivo.     

LuTHy: a double‐readout bioluminescence‐based two‐hybrid technology for quantitative mapping of protein–protein interactions in mammalian cells

Information on protein–protein interactions (PPIs) is of critical importance for studying complex biological systems and developing therapeutic strategies. Here, we present a double‐readout bioluminescence‐based two‐hybrid technology, termed LuTHy, which provides two quantitative scores in one experimental procedure when testing binary interactions. PPIs are first monitored in cells by quantification of bioluminescence resonance energy transfer (BRET) and, following cell lysis, are again quantitatively assessed by luminescence‐based co‐precipitation (LuC). The double‐readout procedure detects interactions with higher sensitivity than traditional single‐readout methods and is broadly applicable, for example, for detecting the effects of small molecules or disease‐causing mutations on PPIs. Applying LuTHy in a focused screen, we identified 42 interactions for the presynaptic chaperone CSPα, causative to adult‐onset neuronal ceroid lipofuscinosis (ANCL), a progressive neurodegenerative disease. Nearly 50% of PPIs were found to be affected when studying the effect of the disease‐causing missense mutations L115R and ?L116 in CSPα with LuTHy. Our study presents a robust, sensitive research tool with high utility for investigating the molecular mechanisms by which disease‐associated mutations impair protein activity in biological systems.     

Pyruvic acid is attached through its central carbon atom to the amino terminus of the recombinant DNA-derived DNA-binding protein Ner of bacteriophage Mu.

Ner protein of bacteriophage Mu, produced by recombinant DNA techniques in Escherichia coli, has been found to possess a molecule of pyruvic acid attached covalently through carbon-2 to the amino-terminal cysteine residue. The intact protein and the amino-terminal chymotryptic peptide were found by mass spectrometry to be 70 mass units heavier than expected. The modified peptide was unstable under mildly acid or mildly basic conditions. Two-dimensional nuclear magnetic resonance spectroscopy of the modified and unmodified forms of the amino-terminal chymotryptic peptide was consistent with the presence of pyruvate linked through carbon-2 to the amino-terminal Cys residue. Treatment of the modified form with 2,4-dinitrophenylhydrazine in acid medium led to the expected hydrazone of pyruvic acid, which was identified by high pressure liquid chromatography. Of the two proteins known to be modified by pyruvate through its central carbon (the other being human adult hemoglobin, in which the modified form represents only a very minor fraction), Ner is the first protein found to be modified quantitatively. Given the instability of the modification, it may be more prevalent than recognized hitherto. Incubation with 2,4-dinitrophenylhydrazine may offer a useful means of detecting the presence of pyruvate linked to proteins in this way.     

TP53 and p16INK4A, but not H-KI-Ras, are involved in tumorigenesis and progression of pleomorphic adenomas

The putative role of TP53 and p16(INK4A) tumor suppressor genes and Ras oncogenes in the development and progression of salivary gland neoplasias was studied in 28 cases of pleomorphic adenomas (PA), 4 cases of cystic adenocarcinomas, and 1 case of carcinoma ex-PA. Genetic and epigenetic alterations in the above genes were analyzed by Polymerase Chain Reaction/Single Strand Conformational Polymorphism (PCR/SSCP) and sequencing and by Methylation Specific-PCR (MS-PCR). Mutations in TP53 were found in 14% (4/28) of PAs and in 60% (3/5) of carcinomas. Mutations in H-Ras and K-Ras were identified in 4% (1/28) and 7% (2/28) of PAs, respectively. Only 20% (1/5) of carcinomas screened displayed mutations in K-Ras. p16(INK4A) promoter hypermethylation was found in 14% (4/28) of PAs and 100% (5/5) carcinomas. All genetic and epigenetic alterations were detected exclusively in the epithelial and transitional tumor components, and were absent in the mesenchymal parts. Our analysis suggests that TP53 mutations and p16(INK4A) promoter methylation, but not alterations in the H-Ras and K-Ras genes, might be involved in the malignant progression of PA into carcinoma.     

Maternal Control of PIN1 Is Required for Female Gametophyte Development in Arabidopsis

Land plants are characterised by haplo-diploid life cycles, and developing ovules are the organs in which the haploid and diploid generations coexist. Recently it has been shown that hormones such as auxin and cytokinins play important roles in ovule development and patterning. The establishment and regulation of auxin levels in cells is predominantly determined by the activity of the auxin efflux carrier proteins PIN-FORMED (PIN). To study the roles of PIN1 and PIN3 during ovule development we have used mutant alleles of both genes and also perturbed PIN1 and PIN3 expression using micro-RNAs controlled by the ovule specific DEFH9 (DEFIFICENS Homologue 9) promoter. PIN1 down-regulation and pin1-5 mutation severely affect female gametophyte development since embryo sacs arrest at the mono- and/or bi-nuclear stages (FG1 and FG3 stage). PIN3 function is not required for ovule development in wild-type or PIN1-silenced plants. We show that sporophytically expressed PIN1 is required for megagametogenesis, suggesting that sporophytic auxin flux might control the early stages of female gametophyte development, although auxin response is not visible in developing embryo sacs.     

Signaling-mediated control of ubiquitin ligases in endocytosis

Ubiquitin-dependent regulation of endocytosis plays an important part in the control of signal transduction, and a critical issue in the understanding of signal transduction therefore relates to regulation of ubiquitination in the endocytic pathway. We discuss here what is known of the mechanisms by which signaling controls the activity of the ubiquitin ligases that specifically recognize the targets of ubiquitination on the endocytic pathway, and suggest alternative mechanisms that deserve experimental investigation.     

A review on the hybrids of hydroxycinnamic acid as multi-target-directed ligands against Alzheimer’s disease

Alzheimer’s disease (AD), a complex chronic progressive central nervous system degenerative disease and a public health problem of the world, often characters cognitive dysfunction accompaning aggression and depression, and may lead to death. More attentions should be paid on it because there is no modified strategy against AD till now. AD is featured with the loss of cholinergic neurons, the amyloid-beta peptide (Aβ) plaques and the neurofibrillary tangles and several hypotheses were established to explain the pathogenesis of AD. Hydroxycinnamic acids, including caffeic acid (CA) and ferulic acid (FA) are widely distributed in natural plants and fruits. CA and FA exert various pharmacological activities, including anti-inflammatory, antioxidant, neuroprotection, anti-amyloid aggregation and so on. All these pharmacological activities are associated with the treatment of AD. Here we summarized the pharmacological activities of CA and FA, and their hybrids as multi-target-directed ligands (MTDLs) against AD. The future application of CA and FA was also discussed, hoping to provide beneficial information for the development of CA- and FA-based MTDLs against AD.