Hepatic silver binding protein (Ag BP) from sparrow (Passer domesticus)

Summary A silver binding protein (Ag BP) has been identified in the liver ofsparrows administered a tracer dose of^110mAg. The protein as purified by gel-filtration shows a major absorption maximum at 260 nm and a minor one at 225 nm. It has a mol.wt of 9500 daltons and is stable when exposed to high temperature (64°C for 15 min) as well as to acidic pH (2.2).     

Demonstration of a specific androgen binding protein (ABP) in the seminal plasma of the ram]

A specific androgen binding protein has been demonstrated in the seminal plasma of adult Ram. This protein binds especially to 5 alpha-DHT and testosterone and much lower to oestradiol-17 beta. Its characteristics such as Ka (in order 10(9) M(-1) at 4 degrees C), relative mobility (Rf) and its specificity are similar to those of the androgen binding protein (ABP) of the Rete Testis Fluid and the epididymal plasma of the Ram. It is probable that this protein secreted from the testis, crosses the epididymis before being secreted in the seminal plasma at the moment of the ejaculation.     

Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments

The long-wavelength-sensitive (LWS) opsins form one of four classes of vertebrate cone visual pigment and exhibit peak spectral sensitivities (λ(max)) that generally range from 525 to 560 nm for rhodopsin/vitamin-A(1) photopigments. Unique amongst the opsin classes, many LWS pigments show anion sensitivity through the interaction of chloride ions with a histidine residue at site 197 (H197) to give a long-wavelength spectral shift in peak sensitivity. Although it has been shown that amino acid substitutions at five sites (180, 197, 277, 285 and 308) are useful in predicting the λ(max) values of the LWS pigment class, some species, such as the elephant shark and most marine mammals, express LWS opsins that possess λ(max) values that are not consistent with this 'five-site' rule, indicating that other interactions may be involved. This study has taken advantage of the natural mutation at the chloride-binding site in the mouse LWS pigment. Through the use of a number of mutant pigments generated by site-directed mutagenesis, a new model has been formulated that takes into account the role of charge and steric properties of the side chains of residues at sites 197 and 308 in the function of the chloride-binding site in determining the peak sensitivity of LWS photopigments.     

A blue light-reversible reaction in an animal system (Daphnia pulex)

Summary A photoreversible reaction, previously found only in plants and fungi, has now been found in an animal system. Activation of development in diapausing embryos ofDaphnia pulex, induced with white light, was suppressed with subsequent exposure to narrow-band (470 nm) or wide-band (410–525 nm) blue light. Pulses of wide-band blue light repeatedly reversed white light activation.     

A SAXS-based ensemble model of the native and phosphorylated regulatory domain of the CFTR

The cystic fibrosis transmembrane conductance regulator (CFTR), the defective protein in cystic fibrosis, is an anion channel activated by protein kinase A phosphorylation. The regulatory domain (RD) of CFTR has multiple phosphorylation sites, and is responsible for channel activation. This domain is intrinsically disordered, rendering the structural analysis a difficult task, as high-resolution techniques are barely applicable. In this work, we obtained a biophysical characterization of the native and phosphorylated RD in solution by employing complementary structural methods. The native RD has a gyration radius of 3.25 nm, and a maximum molecular dimension of 11.4 nm, larger than expected for a globular protein of the same molecular mass. Phosphorylation causes compaction of the structure, yielding a significant reduction of the gyration radius, to 2.92 nm, and on the maximum molecular dimension to 10.2 nm. Using an ensemble optimization method, we were able to generate a low-resolution, three-dimensional model of the native and the phosphorylated RD based on small-angle X-ray scattering data. We have obtained the first experiment-based model of the CFTR regulatory domain, which will be useful to understand the molecular mechanisms of normal and pathological CFTR functioning.     

Antibacterial effect of 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine onStaphylococcus aureus

The mechanism by which a new naphthoquinone derivative, the 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (INQI-E) has antibacterial effect againstStaphylococcus aureus was studied. The interaction of INQI-E with the bacteria was followed by absorption spectroscopy at 323 and 490 nm. The absorption band of INQI-E at 490 nm undergoes a hypochromic shift with a decrease of intensity. This effect was found to be reversible by oxygenation during the first hours of incubation. The participation of an oxidation-reduction process related to the respiratory chain was demonstrated by oxygen consumption. An increase in O₂ uptake and inhibition ofS. aureus growth was observed. Experiments with three inhibitors of the respiratory chain demonstrated that the pathway induced by INQI-E was antimycin-resistant and KCN- and salicylhydroxamic acid (SHAM)-sensitive, which suggests that INQI-E is capable of diverting the normal electron flow to an alternate superoxide-producing route. On the other hand, experiments with Tiron, a specific scavenger of superoxide, hindered the effect of INQI-E againstS. aureus, indicating that the inhibitory growth effect of this quinone-imine is mainly due to the production of the cytotoxic superoxide radical.     

Theory (In-)Equivalence and conventionalism in f(R) gravity

f(R) Gravity is the most natural extension of General Relativity within Riemannian Geometry. Due to (inter alia) its potential capacity for a unified treatment of early and late-time cosmic expansion, it has enjoyed recent attention in astrophysics and cosmology. I critically examine three inter-related claims found in the pertinent physics literature, of general interest to the philosopher of science. 1. f(R) Gravity is equivalent to a particular Brans-Dicke Theory. 2. The spacetime geometry underpinning f(R) Gravity has substantial conventional elements. 3. f(R) Gravity is an instance of a theory in which the distinction between matter and spacetime is conventional. Whilst the first claim can be vindicated in precise terms, the remaining two claims, I submit, are unwarranted – at least for the reasons usually adduced. On different grounds, though, the case for conventionalism about spacetime geometry in f(R) Gravity (as well as General Relativity) turns out to be considerably stronger.     

Structural organization and cellular localization of tuftelin-interacting protein 11 (TFIP11)

Tuftelin-interacting protein (TFIP11) was first identified in a yeast two-hybrid screening as a protein interacting with tuftelin. The ubiquitous expression of TFIP11 suggested that it might have other functions in non-dental tissues. TFIP11 contains a G-patch, a protein domain believed to be involved in RNA binding. Using a green fluorescence protein tag, TFIP11 was found to locate in a novel subnuclear structure that we refer to as the TFIP body. An in vivo splicing assay demonstrated that TFIP11 is a novel splicing factor. TFIP11 diffuses from the TFIP body following RNase A treatment, suggesting that the retention of TFIP11 is RNA dependent. RNA polymerase II inhibitor (-amanitin and actinomycin D) treatment causes enlargement in size and decrease in number of TFIP bodies, suggesting that TFIP bodies perform a storage function rather than an active splicing function. The TFIP body may therefore represent a new subnuclear storage compartment for splicing components.Received 8 December 2004; received after revision 27 January 2005; accepted 8 March 2004The nucleotide sequence for the cDNA to mouse TFIP11 (previously known as TIP39 and TIP39kDa) has been submitted to Gen- Bank^TM/ EBI Data Bank with accession numbers AF290474 and NM_018783. The accession number for the human TFIP11 homologueis NM_012143.     

Functional mechanisms of the cellular prion protein (PrPC) associated anti-HIV-1 properties

The cellular prion protein PrP(C)/CD230 is a GPI-anchor protein highly expressed in cells from the nervous and immune systems and well conserved among vertebrates. In the last decade, several studies suggested that PrP(C) displays antiviral properties by restricting the replication of different viruses, and in particular retroviruses such as murine leukemia virus (MuLV) and the human immunodeficiency virus type 1 (HIV-1). In this context, we previously showed that PrP(C) displays important similarities with the HIV-1 nucleocapsid protein and found that PrP(C) expression in a human cell line strongly reduced HIV-1 expression and virus production. Using different PrP(C) mutants, we report here that the anti-HIV-1 properties are mostly associated with the amino-terminal 24-KRPKP-28 basic domain. In agreement with its reported RNA chaperone activity, we found that PrP(C) binds to the viral genomic RNA of HIV-1 and negatively affects its translation. Using a combination of biochemical and cell imaging strategies, we found that PrP(C) colocalizes with the virus assembly machinery at the plasma membrane and at the virological synapse in infected T cells. Depletion of PrP(C) in infected T cells and microglial cells favors HIV-1 replication, confirming its negative impact on the HIV-1 life cycle.     

Preliminary observations of a bacteriophage infecting Xenorhabdus luminescens (Enterobacteriaceae)

A bacteriophage infective to Xenorhabdus luminescens, a bacterial symbiont of heterorhabditid nematodes, was recovered from insects that supported poor nematode development. Plaque tests showed the phage particles to be infective only to primary and not secondary colonies of X. luminescens. The phage was not infective to X. nematophilus primaries or secondaries. The bacteriophage particles ranged 80-90 nm in length, with the head ranging from 40 to 50 nm in diameter. Restriction analysis was performed on isolated bacteriophage DNA. This first report of a bacteriophage from Xenorhabdus species has practical implications since it could be detrimental to cultures of Heterorhabditis nematodes that are being produced throughout the world for the biological control of insects.     

The cystic fibrosis transmembrane conductance regulator (CFTR) and its stability

The cystic fibrosis transmembrane conductance regulator (CFTR) is responsible for the disease cystic fibrosis (CF). It is a membrane protein belonging to the ABC transporter family functioning as a chloride/anion channel in epithelial cells around the body. There are over 1500 mutations that have been characterised as CF-causing; the most common of these, accounting for ~70 % of CF cases, is the deletion of a phenylalanine at position 508. This leads to instability of the nascent protein and the modified structure is recognised and then degraded by the ER quality control mechanism. However, even pharmacologically ‘rescued’ F508del CFTR displays instability at the cell’s surface, losing its channel function rapidly and it is rapidly removed from the plasma membrane for lysosomal degradation. This review will, therefore, explore the link between stability and structure/function relationships of membrane proteins and CFTR in particular and how approaches to study CFTR structure depend on its stability. We will also review the application of a fluorescence labelling method for the assessment of the thermostability and the tertiary structure of CFTR.     

Syntrophin proteins as Santa Claus: role(s) in cell signal transduction

Syntrophins are a family of cytoplasmic membrane-associated adaptor proteins, characterized by the presence of a unique domain organization comprised of a C-terminal syntrophin unique (SU) domain and an N-terminal pleckstrin homology (PH) domain that is split by insertion of a PDZ domain. Syntrophins have been recognized as an important component of many signaling events, and they seem to function more like the cell’s own personal ‘Santa Claus’ that serves to ‘gift’ various signaling complexes with precise proteins that they ‘wish for’, and at the same time care enough for the spatial, temporal control of these signaling events, maintaining overall smooth functioning and general happiness of the cell. Syntrophins not only associate various ion channels and signaling proteins to the dystrophin-associated protein complex (DAPC), via a direct interaction with dystrophin protein but also serve as a link between the extracellular matrix and the intracellular downstream targets and cell cytoskeleton by interacting with F-actin. They play an important role in regulating the postsynaptic signal transduction, sarcolemmal localization of nNOS, EphA4 signaling at the neuromuscular junction, and G-protein mediated signaling. In our previous work, we reported a differential expression pattern of alpha-1-syntrophin (SNTA1) protein in esophageal and breast carcinomas. Implicated in several other pathologies, like cardiac dys-functioning, muscular dystrophies, diabetes, etc., these proteins provide a lot of scope for further studies. The present review focuses on the role of syntrophins in membrane targeting and regulation of cellular proteins, while highlighting their relevance in possible development and/or progression of pathologies including cancer which we have recently demonstrated.     

The role of survival motor neuron protein (SMN) in protein homeostasis

Ever since loss of survival motor neuron (SMN) protein was identified as the direct cause of the childhood inherited neurodegenerative disorder spinal muscular atrophy, significant efforts have been made to reveal the molecular functions of this ubiquitously expressed protein. Resulting research demonstrated that SMN plays important roles in multiple fundamental cellular homeostatic pathways, including a well-characterised role in the assembly of the spliceosome and biogenesis of ribonucleoproteins. More recent studies have shown that SMN is also involved in other housekeeping processes, including mRNA trafficking and local translation, cytoskeletal dynamics, endocytosis and autophagy. Moreover, SMN has been shown to influence mitochondria and bioenergetic pathways as well as regulate function of the ubiquitin–proteasome system. In this review, we summarise these diverse functions of SMN, confirming its key role in maintenance of the homeostatic environment of the cell.     

Preliminary observations of a bacteriophage infectingXenorhabdus luminescens (Enterobacteriaceae)

A bacteriophage infective toXenorhabdus luminescens, a bacterial symbiont of heterorhabditid nematodes, was recovered from insects that supported poor nematode development. Plaque tests showed the phage particles to be infective only to primary and not secondary colonies ofX. luminescens. The phage was not infective toX. nenatophilus primaries or secondaries. The bacteriophage particles ranged 80–90 nm in length, with the head ranging from 40 to 50 nm in diameter. Restriction analysis was performed on isolated bacteriophage DNA. This first report of a bacteriophage fromXenorhabdus species has pratical implications since it could be detrimental to cultures ofHeterorhabditis nematodes that are being produced throughout the world for the biological control of insects.     

Microspectrophotometric study of biogenic amines in ganglions of the central nervous system of Crepidula fornicata (Phil.)]

The fluorescent products formed from biogenic amines treated with formaldehyde according to the method of Falck and Owman have been studied in the brain of Crepidula fornicata. The microspectrophotometric analysis of cellular indolamines shows excitation emission maxima at 385--525 nm (serotonine) and catecholamine at 410--475 nm upon HCl treatment catecholamine products show a shift of the excitation peak from 410 to 370 nm (dopamine).     

On partial and differential bleaching experiments with the visual pigments in a fresh water euryhaline teleost (Etroplus suratensis)

Summary Visual pigment was extracted from a fresh water toleost,Etroplus suratensis and the optical density measured over a range of 300–650 nm. The absorption spectrum indicates the _max at 550 nm and a small hump at 530 nm. Through partial bleaching at 630 nm, it was confirmed that the fish possesses a mixture of 2 visual pigments: the one with the _max at 550 nm predominating over the other.     

Regulation of HERG (KCNH2) potassium channel surface expression by diacylglycerol

The HERG (KCNH2) channel is a voltage-sensitive potassium channel mainly expressed in cardiac tissue, but has also been identified in other tissues like neuronal and smooth muscle tissue, and in various tumours and tumour cell lines. The function of HERG has been extensively studied, but it is still not clear what mechanisms regulate the surface expression of the channel. In the present report, using human embryonic kidney cells stably expressing HERG, we show that diacylglycerol potently inhibits the HERG current. This is mediated by a protein kinase C-evoked endocytosis of the channel protein, and is dependent on the dynein–dynamin complex. The HERG protein was found to be located only in early endosomes and not lysosomes. Thus, diacylglycerol is an important lipid participating in the regulation of HERG surface expression and function.     

Juvenile hormone,vitellogenin and haemocyte composition in winter worker honeybees (Apis mellifera)

Summary The haemolymph of winter bees (long life span) in contrast to that of summer bees (short life span) has a low juvenile hormone titre and a high protein titre. It is suggested that the winter bee physiology may be brought about by low JH-production.     

Studies on the metal-complex of acetyl salicylic acid (aspirin)

Summary The present communication deals with the isolation of acetyl salicylic acid (aspirin) complexes with Bi⁺³, Zn⁺² and UO ₂ ⁺² . The characterization of 12 complexes have been carried out with the help of conductometric, pH metric, elemental analysis and IR spectral studies. Spectrophotometric studies in case of UO ₂ ⁺² (the only colored complex) in range of 4.2 to 5.5 pH show absorption at 490 nm and complex obey Beers Law at the concentration range of 0.01 M to 0.1 M.