A Free-living Panagrolaimus sp. from Armenia Can Survive in Anhydrobiosis for 8.7 Years

Although the ability of plant-parasitic nematodes to survive in a dehydrated or anhydrobiotic state for long periods of time has been well documented, the ability of free-living nematodes has not. Here we report on the survival of a free-living nematode, Panagrolaimus sp., from Armenia in the anhydrobiotic state for 8.7 years. This Panagrolaimus sp. can be cultured and maintained readily and may provide a good system for studying anhydrobiosis in nematodes.     

Alterations of energy metabolism induced by hexadecane in mice

Two groups of young male OF-1 mice were fed for 60 days with cafeteria or, as controls, with standard pellet diet respectively. At that time, both groups were daily treated with hexadecane (HDK) on the skin. HDK induced a drastic body weight loss much higher in cafeteria than control mice. White adipose tissue were exhausted after 4 days of treatment in controls but not after 10 days in cafeteria ones. HDK resulted in mobilization of liver glycogen in both groups while muscle glycogen decreased slightly in the end. Hexadecane treatment did not result in massively enhanced nitrogen metabolism, as the actual oxidation of amino acids decreased considerably as indicated by the low levels of plasma urea. The results could be explained by powerful and lasting effects of hexadecane on thermogenesis and metabolic reserve balance. The use of this material for pharmacological manipulation of body weight appeared difficult.     

Adsorptive control of water in esterification with immobilized enzymes: II. fixed-bed reactor behavior

Experimental and theoretical studies are conducted to understand the dynamic behavior of a continuous-flow fixed-bed reactor in which an esterification is catalyzed by an immobilized enzyme in an organic solvent medium. The experimental system consists of a commercial immobilized lipase preparation known as Lipozyme as the biocatalyst, with propionic acid and isoamyl alcohol (dissolved in hexane) as the reaction substrates. A complex dynamic behavior is observed experimentally as a result of the simultaneous occurrence of reaction and adsorption phenomena. Both propionic acid and water are adsorbed by the biocatalyst resulting in lower reaction rates. In addition, an excessive accumulation of water in the reactor leads to a rapid irreversible inactivation of the enzyme. A model based on previously-obtained adsorption isotherms and kinetic expressions, as well as on adsorption rate measurements obtained in this work, is used to predict the concentration and thermodynamic activity of water along the reactor length. The model successfully predicts the dynamic behavior of the reactor and shows that a maximum thermodynamic activity of water occurs at a point at some distance from the reactor entrance. A cation exchange resin in sodium form, packed in the reactor as a selective water adsorbent together with the catalyst particles, is shown to be an effective means for preventing an excessive accumulation of water formed in the reaction. Its use results in longer cycle times and greater productivity. As predicted by the model, the experimental results show that the water adsorbed on the catalyst and on the ion exchange resin can be removed with isoamyl alcohol with no apparent loss in enzyme activity.     

Morphological and Molecular Evaluation of a Meloidogyne hapla Population Damaging Coffee (Coffea arabica) in Maui,Hawaii

An unusual population of Meloidogyne hapla, earlier thought to be an undescribed species, was found causing large galls, without adventitious roots, and substantial damage to coffee in Maui, Hawaii. Only in Brazil had similar damage to coffee been reported by this species. Unlike M. exigua from South and Central America, this population reproduced well on coffee cv. Mokka and M. incognita-susceptible tomato but poorly on tomato with the Mi resistance gene. Characterization included SEM images, esterase isozymes, and five DNA sequences: i) the D3 segment of the large subunit (LSU-D3 or 28S) rDNA, ii) internal transcribed spacer (ITS-1) rDNA, iii) intergenic spacer (IGS) rDNA, iv) the mitochondrial interval from cytochrome oxidase (CO II) to 16S mtDNA, and v) the nuclear gene Hsp90. Sequences for ITS-1, IGS, and COII were similar to other M. hapla populations, but within species ITS-1 variability was not less than among species. One LSU-D3 haplotype was similar to a previously analyzed population with two minor haplotypes. Hsp90 exhibited some variation between Maryland and Hawaiian populations distinct from other species. Females were narrow with wide vulval slits, large interphasmidial distances, and more posterior excretory pores; 20% of perineal patterns had atypical perivulval lines. Males had a low b ratio (<12 µm). Juveniles had a short distance between stylet and dorsal gland orifice. Juvenile body length was short (<355 µm) and was different between summer and winter populations.     

Morphological variability and molecular phylogeny of the nematophagous fungus Monacrosporium drechsleri

An isolate of the nematode-trapping fungus Monacrosporium drechsleri was collected from cultures of the root-knot nematode Meloidogyne arenaria that had been maintained on tomato roots in greenhouse pots in Beltsville, Maryland. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita and Pratylenchus zeae and the free-living nematodes Caenorhabditis elegans and Panagrellus redivivus were placed on colonies of M. drechsleri grown in Petri dishes to study ability of the isolate to trap various nematode hosts. None of the nematodes placed near adhesive knobs were motile within 1 d. To determine where M. drechsleri fits within the existing phylogeny of nematode-trapping fungi, the ITS1-ITS2 regions of rDNA and the nuclear gene EF1-alpha were sequenced for the new isolate of M. drechsleri, for the species M. parvicolle and M. lysipagum, and for an isolate of M. ellipsosporum distinct from the one listed in GenBank. Parsimony trees were constructed showing the closest molecular relative of M. drechsleri to be the newly sequenced isolate of M. ellipsosporum; the latter had a highly divergent sequence from the sequence recorded in GenBank for a different isolate of M. ellipsosporum. Unique, consistent and discrete morphological characters are absent in these related taxa, so an independent molecular character should be considered essential for their accurate identification.     

Novel checkpoint response to genotoxic stress mediated by nucleolin-replication protein a complex formation

Human replication protein A (RPA), the primary single-stranded DNA-binding protein, was previously found to be inhibited after heat shock by complex formation with nucleolin. Here we show that nucleolin-RPA complex formation is stimulated after genotoxic stresses such as treatment with camptothecin or exposure to ionizing radiation. Complex formation in vitro and in vivo requires a 63-residue glycine-arginine-rich (GAR) domain located at the extreme C terminus of nucleolin, with this domain sufficient to inhibit DNA replication in vitro. Fluorescence resonance energy transfer studies demonstrate that the nucleolin-RPA interaction after stress occurs both in the nucleoplasm and in the nucleolus. Expression of the GAR domain or a nucleolin mutant (TM) with a constitutive interaction with RPA is sufficient to inhibit entry into S phase. Increasing cellular RPA levels by overexpression of the RPA2 subunit minimizes the inhibitory effects of nucleolin GAR or TM expression on chromosomal DNA replication. The arrest is independent of p53 activation by ATM or ATR and does not involve heightened expression of p21. Our data reveal a novel cellular mechanism that represses genomic replication in response to genotoxic stress by inhibition of an essential DNA replication factor.     

Modulation of lipid metabolism and vitamin A by conjugated linoleic acid

The term conjugated linoleic acid (CLA) refers to a collection of positional and geometrical isomers of octadeca- dienoic acid with conjugated double bonds. CLA has been shown to possess several beneficial activities in different experimental models, however, out of 28 isomers only two, c9, t11 and t10, c12 have been thus far demonstrated to be biologically active.The discovery that it can be elongated and desaturated as a regular fatty acid in human and animal tissues brought a new possibility that its activity may be related to its properties as a peculiar unsaturated fatty acid. In fact, CLA is able to be incorporated in lipid classes as oleic acid, accumulating in those tissues rich in neutral lipids; to be metabolized as linoleic acid and so influencing linoleic acid desaturation and elongation; and to be beta oxidized in peroxisomes which may account for, through activation of PPARs, its ability to increase free retinol levels and influence gene expression. These activities are amplified where CLA accumulates more such as mammary and adipose tissues and may explain its peculiar beneficial properties, at relative low dietary concentrations, in these tissues. Furthermore, it has been demonstrated that CLA can be endogenously formed by delta 9 desaturation of vaccenic acid (t11 18:1) thus forming the isomer c9, t11. Either endogenously formed or through dietary intake, CLA showed to be metabolized in the same way and to exert the same biological properties. We may conclude that a regular intake of CLA, or/and vaccenic acid as its precursor, should work as an excellent preventive agent by modulating lipid metabolism in target tissues thus conferring protection against the attack of insults of different type.     

Incorporation and metabolism of c9,t11 and t10,c12 conjugated linoleic acid (CLA) isomers in rat brain

Conjugated linoleic acid (CLA) has been shown to exert several biological activities in different organs, in particular organs such as adipose and mammary tissue where CLA accumulates preferentially because of its high incorporation into neutral lipids. However, despite numerous studies carried out in different experimental models, both in vivo and in vitro, very little is known about the accumulation and metabolism of CLA in the brain. In this communication we present data showing that the two CLA isomers c9,t11 and t10,c12 are actively incorporated and metabolised in rat brain, and in cultures of astrocytes in vitro with patterns remarkably similar to those previously reported to occur in other tissues and cells. However, beta oxidation of CLA was found to be more efficient in brain than in other tissues, with t10,c12 a better substrate than the c9,t11 isomer. CLA incorporation and metabolism have been linked to antiinflammatory and antiproliferative activities in experimental models. Therefore, CLA activity in brain could have a positive impact on neurological disorders, such as Alzheimer's disease, Parkinson's disease and adrenoleukodystrophy, where an observed increase in inflammatory responses seems to contribute heavily to the pathogenesis.