Optimization of parameters in the batch kinetic studies of glucose isomerisation by arthrobacter sp.

Vital parameters like temperature, pH and agitation are optimized in the kinetic studies of glucose isomerisation carried out in a batch fashion. A 4-litre fermentor with temperature, pH, agitation and other controls is used. It is found that the two parameters — temperature and pH, do not have an interacting effect on each other. A temperature of 60°C, a pH of 8.0 and a speed of 200 rpm are found to be better suited for the production of fructose syrups starting from glucose by arthrobacter sp. An upper limit of 20 minutes on the residence time is suggested for use in the design of flow reactors.     

Development of fluorescence imaging probes for nicotinic acetylcholine α4β21 receptors

Nicotinic acetylcholine α4β2¹ receptors (nAChRs) are implicated in various neurodegenerative diseases and smoking addiction. Imaging of brain high-affinity α4β2¹ nAChRs at the cellular and subcellular levels would greatly enhance our understanding of their functional role. Since better resolution could be achieved with fluorescent probes, using our previously developed positron emission tomography (PET) imaging agent [¹⁸F]nifrolidine, we report here design, synthesis and evaluation of two fluorescent probes, nifrodansyl and nifrofam for imaging α4β2¹ nAChRs. The nifrodansyl and nifrofam exhibited nanomolar affinities for the α4β2¹ nAChRs in [³H]cytisine-radiolabeled rat brain slices. Nifrofam labeling was observed in α4β2¹ nAChR-expressing HEK cells and was upregulated by nicotine exposure. Nifrofam co-labeled cell-surface α4β2¹ nAChRs, labeled with antibodies specific for a β2 subunit extracellular epitope indicating that nifrofam labels α4β2¹ nAChR high-affinity binding sites. Mouse brain slices exhibited discrete binding of nifrofam in the auditory cortex showing promise for examining cellular distribution of α4β2¹ nAChRs in brain regions.     

Polysaccharide components from the scape of Musa paradisiaca: main structural features of water-soluble polysaccharide component

Polysaccharide components present in the pseudo-stem (scape) of M. paradisiaca were purified from acetone powder of the scape by delignification followed by extraction with aqueous solvents into water soluble polysaccharide (WSP), EDTA-soluble polysaccharide (EDTA-SP), alkali-soluble polysaccharide (ASP) and alkali-insoluble polysaccharide (AISP) fractions. Sugar compositional analysis showed that WSP and EDTA-SP contained only D-Glc whereas ASP contained D-Glc, L-Ara and D-Xyl in ∼ 1:1:10 ratio, respectively, and AISP' contained D-Glc, L-Ara and D-Xyl in ∼ 10:1:2 ratio, respectively. WSP was further purified by complexation with iso-amylalcohol and characterized by specific rotation, IR spectroscopy, Iodine affinity, ferricyanide number, blue value, hydrolysis with α-amylase and glucoamylase, and methylation linkage analysis, and shown to be a amylopectin type α-D-glucan. This revised version was published online in November 2006 with corrections to the Cover Date.     

Lysophosphatidylserine dependent incorporation of acyl CoA into phospholipids in rat brain microsomes

[¹⁴C]OleoylCoA was incorporated into phosphatidylinositol 4$\text{1}\text{2}$ times more efficiently than into phosphatidylserine in rat brain and liver microsomes when incubated with various levels of 1-acyl-sn-glycero-3-phosphoserine. In contrast, 1-acyl-sn-glycero-3-phosphocholine dependent incorporation of oleoylCoA was only into phosphatidylcholine. When [l-³H]serine labeled 1-acyl-sn-glycero-3-phosphoserine was used as the labeled substrate, no phosphatidylserine synthesis could be detected in rat brain microsomes. OleoylCoA incorporation in phospholipids in the presence of lysophosphatidylserine was primarily at the 2-position while stearoylCoA was incorporated at the 1-position. These results are interpreted to suggest that there is no acylCoA:1-acyl-sn-glycero-3-phosphoserine acyltransferase in rat brain microsomes and the lysophosphatidylserine dependent position-specific incorporation of acylCoA into various phospholipids may be due to an exchange reaction. A simple highly reproducible one dimensional thin-layer chromatographic system is described for the separation of all the major phospholipids of brain and liver.     

The decapod researcher’s guide to the galaxy of sex determination

The objective of this study was to assess the frequency of use of marine resources in recruitment of Southern Hemisphere native riverine fish Galaxias maculatus from rivers across a latitudinal gradient. To do this, we analysed the concentrations of δ³⁴S in vertebral column tissues from fish collected in ten Chilean river systems across latitudes 36°–47°S. The analyses of δ³⁴S signatures in these rivers suggest that the use of marine resources by riverine populations of G. maculatus in large river systems in Chile is variable, with marine resources playing a limited role in more northern large rivers, characterised by warmer temperatures and predictable flow regimes and floodplain inundations. This is in contrast to life histories described for G. maculatus in rivers from New Zealand and Australia, where riverine populations are believed to be characterised by an obligatory recruitment phase in marine environments. Recruitment of G. maculatus in Chilean large rivers appears to depend on their freshwater productivity driven by climate as well as both longitudinal (headwaters lakes-estuary) and lateral (main channel-floodplains) hydrologic connectivities.     

Evaluation of genes involved in Norway lobster (<Emphasis Type="Italic">Nephrops norvegicus</Emphasis>) female sexual maturation using transcriptomic analysis

In marine ecosystems, the most significant migration observed in terms of biomass distribution is the one connected with the vertical movements in the water column. In the present study, the vertical profiles of the mesopelagic shrimps Gennadas elegans, Eusergestes arcticus, Sergia robusta, and the epipelagic Parasergestes vigilax in the Balearic Sea (western Mediterranean), during the stratified (summer) and non-stratified (autumn) hydrographic conditions, were investigated through their ontogeny, from the larval to adult stages. The mesopelagic adults were observed to move down to the deeper layers during the night more than during the daylight hours. Most larvae aggregated within the limits of the upper water column. The P. vigilax larvae were collected only during the stratified period. The first two larval stages vertical distribution indicates that the mesopelagic crustacean spawning could occur at greater depths. During the non-stratified period, the larvae of the mesopelagic species tended to remain at about 500 m depth at night, rising towards the upper layers at sunrise. Vertical patterns are discussed, as strategies associated with predator–prey trade-offs. To our knowledge, the present study is the first such attempt to jointly analyze the vertical migrations of the developmental stages of the pelagic shrimps in the Mediterranean Sea.     

Cerebrospinal Fluid from Sporadic Amyotrophic Lateral Sclerosis Patients Induces Mitochondrial and Lysosomal Dysfunction

In our laboratory, we have developed (1) an in vitro model of sporadic Amyotrophic Lateral Sclerosis (sALS) involving exposure of motor neurons to cerebrospinal fluid (CSF) from sALS patients and (2) an in vivo model involving intrathecal injection of sALS-CSF into rat pups. In the current study, we observed that spinal cord extract from the in vivo sALS model displayed elevated reactive oxygen species (ROS) and mitochondrial dysfunction. Quantitative proteomic analysis of sub-cellular fractions from spinal cord of the in vivo sALS model revealed down-regulation of 35 mitochondrial proteins and 4 lysosomal proteins. Many of the down-regulated mitochondrial proteins contribute to alterations in respiratory chain complexes and organellar morphology. Down-regulated lysosomal proteins Hexosaminidase, Sialidase and Aryl sulfatase also displayed lowered enzyme activity, thus validating the mass spectrometry data. Proteomic analysis and validation by western blot indicated that sALS-CSF induced the over-expression of the pro-apoptotic mitochondrial protein BNIP3L. In the in vitro model, sALS-CSF induced neurotoxicity and elevated ROS, while it lowered the mitochondrial membrane potential in rat spinal cord mitochondria in the in vivo model. Ultra structural alterations were evident in mitochondria of cultured motor neurons exposed to ALS-CSF. These observations indicate the first line evidence that sALS-CSF mediated mitochondrial and lysosomal defects collectively contribute to the pathogenesis underlying sALS.