The evolution of the long and short repetitive DNA sequences in sea urchins.

The rates of evolution of purified long and short repetitive DNA sequences were examined by hybridisation analysis between the DNAs from several species of sea urchins. We find that the rates of nucleotide substitution are very comparable within mutually retained sequences for the two classes of repetitive DNA. The loss of hybridisable sequences between species also occurs at similar rates among both the short and long repetitive DNA sequences. Between species that separated less than 50 million years ago, hybridisable short repetitive sequences are lost all through the spectrum of reiteration frequencies. The long repeats contain a few sequences which are highly conserved within all of the species examined, and which amount to approximately 1% of the total genome. The short repetitive class, on the other hand, does not seem to contain any such highly conserved elements. The long repetitive sequences internally appear to contain short 'units' of reiteration, which may comprise families within the long repetitive class. We find no evidence to indicate that the majority of long and short repetitive sequences evolve by different mechanisms or at different rates.     

Monoorganobismuth(III) dithiocarboxylates: Synthesis, structures and their utility as molecular precursors for the preparation of Bi2S3 films and nanocrystals

Synthesis of a series of monoorganobismuth dithiocarboxylate complexes, [RBi(S₂CAr)₂] (R = Me, Ph, tol; Ar = Ph, tol), has been reported. They have been characterized by elemental analyses and spectroscopic methods. Molecular structures of [RBi(S₂Ctol)₂] (R = Me or Ph) have been established by single crystal X-ray diffraction studies. The bismuth atom in these complexes adopts a square pyramidal configuration with the R group at the apical position. In the solid state, these complexes show supra-molecular association devoid of Bi?S secondary interactions. Thermolysis of [RBi(S₂Ctol)₂] (R = Me or Ph) in refluxing diphenylether yielded Bi₂S₃ nanocrystals which were characterized by XRD, EDAX and SEM. The complex [PhBi(S₂Ctol)₂] has been employed for deposition of thin films of Bi₂S₃ by AACVD.     

Faithful expression of GFP from the PLCbeta2 promoter in a functional class of taste receptor cells

Phospholipase C-type beta2 (PLCbeta2) is expressed in a subset of cells within mammalian taste buds. This enzyme is involved in the transduction of sweet, bitter, and umami stimuli and thus is believed to be a marker for gustatory sensory receptor cells. We have developed transgenic mice expressing green fluorescent protein (GFP) under the control of the PLCbeta2 promoter to enable one to identify these cells and record their physiological activity in living preparations. Expression of GFP (especially in lines with more than one copy integrated) is strong enough to be detected in intact tissue preparations using epifluorescence microscopy. By immunohistochemistry, we confirmed that the overwhelming majority of cells expressing GFP are those that endogenously express PLCbeta2. Expression of the GFP transgene in circumvallate papillae occurs at about the same time during development as endogenous PLCbeta2 expression. When loaded with a calcium-sensitive dye in situ, GFP-positive taste cells produce typical Ca2+ responses to a taste stimulus, the bitter compound cycloheximide. These PLCbeta2 promoter-GFP transgenic lines promise to be useful for studying taste transduction, sensory signal processing, and taste bud development.     

The effects of core muscle activation on dynamic trunk position and knee abduction moments: Implications for ACL injury

Anterior cruciate ligament (ACL) injury is one of the most common serious lower-extremity injuries experienced by athletes participating in field and court sports and often occurs during a sudden change in direction or pivot. Both lateral trunk positioning during cutting and peak external knee abduction moments have been associated with ACL injury risk, though it is not known how core muscle activation influences these variables. In this study, the association between core muscle pre-activation and trunk position as well as the association between core muscle pre-activation and peak knee abduction moment during an unanticipated run-to-cut maneuver were investigated in 46 uninjured individuals. Average co-contraction indices and percent differences between muscle pairs were calculated prior to initial contact for internal obliques, external obliques, and L5 extensors using surface electromyography. Outside tilt of the trunk was defined as positive when the trunk was angled away from the cutting direction. No significant associations were found between pre-activations of core muscles and outside tilt of the trunk. Greater average co-contraction index of the L5 extensors was associated with greater peak knee abduction moment (p=0.0107). Increased co-contraction of the L5 extensors before foot contact could influence peak knee abduction moment by stiffening the spine, limiting sagittal plane trunk flexion (a motion pattern previously linked to ACL injury risk) and upper body kinetic energy absorption by the core during weight acceptance.     

Gustatory sensory cells express a receptor responsive to protein breakdown products (GPR92)

The ingestion of dietary protein is of vital importance for the maintenance of fundamental physiological processes. The taste modality umami, with its prototype stimulus, glutamate, is considered to signal the protein content of food. Umami was thought to be mediated by the heterodimeric amino acid receptor, T1R1 + T1R3. Based on knockout studies, additional umami receptors are likely to exist. In addition to amino acids, certain peptides can also elicit and enhance umami taste suggesting that protein breakdown products may contribute to umami taste. The recently deorphanized peptone receptor, GPR92 (also named GPR93; LPAR5), is expressed in gastric enteroendocrine cells where it responds to protein hydrolysates. Therefore, it was of immediate interest to investigate if the receptor GPR92 is expressed in gustatory sensory cells. Using immunohistochemical approaches we found that a large population of cells in murine taste buds was labeled with an GPR92 antibody. A molecular phenotyping of GPR92 cells revealed that the vast majority of GPR92-immunoreactive cells express PLCβ2 and can therefore be classified as type II cells. More detailed analyses have shown that GPR92 is expressed in the majority of T1R1-positive taste cells. These results indicate that umami cells may respond not only to amino acids but also to peptides in protein hydrolysates.     

Biodegradation of feather keratin with a PEGylated protease of Chryseobacterium gleum

Present study deals with the covalent modification of keratinolytic protease of Chryseobacterium gleum with higher enzyme activity, improved stability, non-immunogenicity and reusability. Protease of C. gleum showing feather degradation ability was modified by covalent attachment to polyethylene glycol. This modification culminated the change in electrophoretic mobility of protease in acrylamide gel. The modified enzyme showed 1.4 times more catalytic activity with better stability than native in aqueous system containing whole feathers as keratin. It showed improved pH, thermal, storage and solvent stability with a broadened range of pH (7–9) and temperature (25–50 °C) than native. The differentiation between modified and native enzyme was authenticated through UV–vis spectroscopy, SEM, XRD, FTIR and DSC. This modification of protease proved to be non-immunogenic in rats. The enzyme extracted after first run could be used for several cycles which clearly demonstrated its reusability in catalytic bioprocess of keratin degradation.     

Receptor specific crosstalk and modulation of signaling upon heterodimerization between β1-adrenergic receptor and somatostatin receptor-5

In the present study we describe heterodimerization, trafficking, coupling to adenylyl cyclase and signaling in HEK-293 cells cotransfected with human-somatostatin receptor 5 (hSSTR5) and β₁-adrenergic receptor (β₁AR). hSSTR5/β₁AR exists as heterodimers in basal conditions which was further enhanced upon synergistic activation of both receptors. Activation of either β₁AR or hSSTR5 displayed dissociation of heterodimerization. In cotransfectants, β₁AR effect on cAMP was predominant; however, blocking β₁AR with antagonist resulted in 60% inhibition of forskolin-stimulated cAMP in the presence of hSSTR5 agonists. cAMP/PKA pathway in cotransfected cells was regulated in receptor-specific manner, in contrast, the status of pERK1/2 and pPI3K/AKT was predominantly regulated by hSSTR5. The expression levels of phosphorylated NFAT remained unchanged indicating blockade of calcineurin-mediated dephosphorylation and nuclear translocation of NFAT, the process predominantly regulated by pJNK in SSTR5 dependent manner. Taken together, the functional consequences of results described here might have relevance in the cardiovascular system where SSTR and AR subtypes play important roles.     

Natural terpenes prevent mitochondrial dysfunction, oxidative stress and release of apoptotic proteins during nimesulide-hepatotoxicity in rats

Nimesulide, an anti-inflammatory and analgesic drug, is reported to cause severe hepatotoxicity. In this study, molecular mechanisms involved in deranged oxidant-antioxidant homeostasis and mitochondrial dysfunction during nimesulide-induced hepatotoxicity and its attenuation by plant derived terpenes, camphene and geraniol has been explored in male Sprague-Dawley rats. Hepatotoxicity due to nimesulide (80 mg/kg BW) was evident from elevated SGPT, SGOT, bilirubin and histo-pathological changes. Antioxidants and key redox enzymes (iNOS, mtNOS, Cu/Zn-SOD, Mn-SOD, GPx and GR) were altered significantly as assessed by their mRNA expression, Immunoblot analysis and enzyme activities. Redox imbalance along with oxidative stress was evident from decreased NAD(P)H and GSH (56% and 74% respectively; P<0.001), increased superoxide and secondary ROS/RNS generation along with oxidative damage to cellular macromolecules. Nimesulide reduced mitochondrial activity, depolarized mitochondria and caused membrane permeability transition (MPT) followed by release of apoptotic proteins (AIF; apoptosis inducing factor, EndoG; endonuclease G, and Cyto c; cytochrome c). It also significantly activated caspase-9 and caspase-3 and increased oxidative DNA damage (level of 8-Oxoguanine glycosylase; P<0.05). A combination of camphene and geraniol (CG; 1:1), when pre-administered in rats (10 mg/kg BW), accorded protection against nimesulide hepatotoxicity in vivo, as evident from normalized serum biomarkers and histopathology. mRNA expression and activity of key antioxidant and redox enzymes along with oxidative stress were also normalized due to CG pre-treatment. Downstream effects like decreased mitochondrial swelling, inhibition in release of apoptotic proteins, prevention of mitochondrial depolarization along with reduction in oxidized NAD(P)H and increased mitochondrial electron flow further supported protective action of selected terpenes against nimesulide toxicity. Therefore CG, a combination of natural terpenes prevented nimesulide induced cellular damage and ensuing hepatotoxicity.     

Cholesterol assimilation and biotransformation by Lactobacillus helveticus

Lactobacillus helveticus, grown at 37°C in MRS medium supplemented with 3 mM cholesterol, assimilated all the cholesterol in 42 h having 68 U mg⁻¹ of intracellular cholesterol oxidase activity. The strain transformed 1 g cholesterol to 0.05 g of androsta-1, 4-diene-3, 17-dione and 0.04 g of androst-4-ene-3, 17 dione within 48 h at 37°C with extracellular cholesterol oxidase activity at 12 U mg⁻¹ and intracellular oxidase at 0.5 U mg⁻¹.