Discovery of a Homolog of Siderophilin in a Plant

Members belonging to the siderophilin family are iron-binding and iron-transporting proteins, which includes transferrin and lactoferrin. They have only been found in animals previously. If siderophilin could be found in and isolated from a plant, its production and subsequent extensive application could be increased. The present study is the first to report the discovery of a homolog of siderophilin in a plant. In order to purify antifreeze proteins from Ammopiptanthus mongolicus （Maxim.） Cheng f., the authors processed the proteins from the leaves using techniques such as column chromatography using DEAE-Cellulose-52, gel filtration via Sephacryl S-100 HR medium, hydrophobic interaction chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Mass spectroscopy was performed on the three proteins purified and the sequence of one of the proteins （containing 32 amino acids） was found to have 97% homology with the corresponding part of one type of human lactoferrin. Moreover, one of the two peptides belongs to an iron-binding domain. So, it is possible that siderophilin also exists in plants and plays a role as an antibacterial and antifungal, among other actions.     

Evaluation of genotoxicity in a group of workers from a petroleum refinery aromatics plant

Petroleum refinery workers are potentially exposed to a wide range of petroleum-derived hydrocarbons and chemical substances used in the manufacturing of petroleum derivatives. Benzene, toluene and xylene (BTX) are produced by distillation in the aromatics units and used as raw materials for petrol and petrochemical products. The aim of this study was to evaluate the genotoxic effects of occupational exposure to BTX in a petroleum refinery in the North of Portugal. The exposed group consisted of 48 workers from the aromatics plant and the control group consisted of 30 persons matched for various confounding factors. Chromosome aberrations (CA), micronuclei (MN), and DNA damage (evaluated by means of the comet assay) were measured in peripheral blood leukocytes. t,t-Muconic acid (t,t-MA), hippuric acid (HA) and methylhippuric acid (MHA) concentrations were measured in urine samples collected at the end of the workshift. The results suggest that occupational exposure to toluene and xylene is very low. A statistically significant increase in t,t-MA excretion was found in the exposed group although t,t-MA levels were found to be lower than the biological exposure index (BEI). Significant increases were found for CA, MN and comet tail length (TL) in the exposed group (p<0.05). No association was found between tobacco smoking and the effect biomarkers analysed. A positive association was found between CA and MN with age in the control group (p<0.05).     

Occurrence of a winged perispore in a new world species of polypodium

Spores ofPolypodium chnoodes Spreng. were found to possess a large winged perispore surrounding the exospore. This character had hitherto been found only in the closely related families of the aspidioid-dennstaedtioid complex. Its presence in a species ofPolypodium is another example of the remarkable parallelisms which occur in ferns.     

The geometry and efficacy of cation-pi interactions in a diagonal position of a designed beta-hairpin

Cation-pi interactions are common in proteins, but their contribution to the stability and specificity of protein structure has not been well established. In this study, we examined the impact of cation-pi interactions in a diagonal position of a beta-hairpin peptide through comparison of the interaction of Phe or Trp with Lys or Arg. The diagonal interactions ranged from -0.20 to -0.48 kcal/mole. Our experimental values for the diagonal cation-pi interactions are similar to those found in alpha-helical studies. Upfield shifting of the Lys and Arg side chains indicates that the geometries of cation-pi interactions adopted in the 12-residue beta-hairpin are comparable to those found in protein structures. The Lys was found to interact through the polarized Cepsilon, and the Arg is stacked against the aromatic ring of Phe or Trp. Folding of these peptides was found to be enthalpically favorable (DeltaH degrees equals approximately -3 kcal/mole) and entropically unfavorable (DeltaS degrees equals approximately -8 cal mole(-1) K(-1)).     

Eo: a history of a mutation

Eighteen mouse t haplotype-carrying strains were found not to express cell-surface E molecules controlled by class II genes of the H-2 complex (= Eo strains). Northern and Southern blot analysis of these and other, non-t strains that also fail to express the E molecule, has revealed two kinds of defect. Three strains (CRO437, tw2, and presumably to) were found to transcribe the E alpha gene, but they were not able to convert the message into a functional protein. All other Eo strains fail to transcribe the E alpha gene because of a deletion encompassing the promoter region, the RNA initiation site, and the first exon. The length of the deletion is approximately 650 +/- 50 bp. These two defects closely resemble those found previously in standard inbred strains carrying the H-2f, H-2q (failure of E mRNA to be expressed functionally), H-2b, and H-2s (deletion of a part of the E alpha gene) haplotypes. In particular, the location and length of the E alpha deletion appear to be the same in the strains carrying this mutation. The E alpha deletion is in linkage disequilibrium with certain alleles at other H-2 loci in some of the strains. These observations, combined with the growing evidence that H-2 haplotypes associated with t chromosomes derive from a single ancestral haplotype, suggest that the E alpha deletion is an old mutation and that it has been disseminated in mouse populations by the t chromosomes.     

A study of the bifurcation behaviour of a model of flow through a collapsible tube

Most of the elastic tubes found in the mammalian body will collapse from a distended circular cross section and when collapsed may undergo flow-induced oscillations. A mathematical model describing fluid flow in a collapsible tube is analysed using the software package AUTO-86. AUTO-86 is used for continuation and bifurcation problems in systems of non-linear ordinary differential equations. The model is a third-order lumped-parameter type and is based on the classical “Starling resistor”; it describes the unsteady flow behaviour and, in particular, the experimentally observed self-excited oscillations, in a way which is simple enough to give physical understanding, yet still firmly based on fluid mechanical principles. Some of the bifurcation types found in this model bear close resemblance to the types suggested by experimental observations of self-excited oscillations in collapsible tubes; they thus shed some light on the various topological changes which occur in practice, particularly in view of the fact that some of the points found numerically are diffcult to achieve experimentally, while the existence of others can only be inferred indirectly and uncertainly from experiment.     

MiR-34a in age and tissue related radio-sensitivity and serum miR-34a as a novel indicator of radiation injury

MiR-34a, a direct target of p53, has shown to exert potent anti-proliferative effects. It has also been found that miR-34a can be induced by irradiation in vitro and in vivo. However, the relationship between miR-34a and radio-sensitivity, and its potential diagnostic significance in radiation biology, remain unclear. This study found that differing responses to ionizing radiation (IR) of young and adult mice were related to miR-34a. First, we found that miR-34a could be induced in many organs by radiation of both young and adult mice. However, the level of miR-34a induced by young mice was much higher when compared to adult mice. Next, we found that miR-34a played a critical role in radio-sensitivity variations of different tissues by enhancing cell apoptosis and decreasing cell viability. We also found that the induction of miR-34a by radiation was in a p53 dependent manner and that one possible downstream target of miR-34a that lead to different radio-sensitivity was the anti-apoptosis molecular Bcl-2. However, over-expression of miR-34a and knockdown of Bcl-2 could significantly enhance the radio-sensitivity of different cells while inhibition of miR-34a could protect cells from radiation injury. Finally, we concluded that miR-34a could be stable in serum after IR and serve as a novel indicator of radiation injury. Taken together, this data strongly suggests that miR-34a may be a novel indicator, mediator and target of radiation injury, radio-sensitivity and radioprotection.     

Transfer of a genetic marker from a megaplasmid of Anabaena sp. strain PCC 7120 to a megaplasmid of a different Anabaena strain.

The 410-kb alpha megaplasmid of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was found to bear the nucA gene that encodes a sugar-nonspecific nuclease. That gene was mutated by insertion of a cassette that confers resistance to neomycin. The resulting strain, AMP2, was mated with a streptomycin-resistant derivative of Anabaena sp. strain PCC 7118, a strain that does not form heterocysts. Cells resistant to both neomycin and streptomycin that were derived from such matings were found to bear the neomycin resistance cassette of the donor strain in a larger megaplasmid characteristic of the recipient strain and did not form heterocysts. This is the first example of transfer of a genetic marker directly between strains of cyanobacteria in which incontrovertible physical evidence of transfer has been obtained. DNA sequences homologous to the nucA gene were present in 13 heterocyst-forming cyanobacteria that were tested but in none of six diverse unicellular strains that were examined.     

Ending a decade of deception: a valiant failure, a not-so-valiant failure, and a success story

Prior studies involving two methods, Brooks Parsimony Analysis (BPA) and TreeMap, have found BPA to be the more reliable method. Recent criticisms leveled at these studies argue that the tests were unfairly created and biased in favor of BPA. The authors of a recent critique offered new exemplars to demonstrate flaws in BPA, plus a simple fix to correct the flaws found in TreeMap. A re‐evaluation of their exemplars clearly shows that the authors' calculations are incorrect, their understanding of the methods is lacking, and that their simple fix does not work. Additional analyses using TreeMap 2.02 are run to show that TreeMap 2.02, like TreeMap 1.0, cannot adequately deal with widespread parasites, contrary to the claims of its supporters. Furthermore, the exemplars corroborate previous findings that BPA, when calculated correctly, is more reliable than TreeMap1.0 and TreeMap 2.02 and therefore the method of choice in coevolutionary and biogeographic studies.     

On a stochastic integral of a branching process

This paper is concerned with the properties of a stochastic integral which arises in the study of a modified Markov branching process. Explicit expressions are found for the mean and the limit distribution of the integral.     

Altered localisation of the precursor of a secreted protein in E. coli by a carboxyl-deletion

The effect on protein localisation of a carboxy-terminal deletion of periplasmic UDP-glucose hydrolase (5'-nucleotidase) has been determined in vivo using immunoprecipitation. The processed form of the truncated protein was found in the periplasm; however, in contrast to the situation with the normal protein, the preprotein form of the truncated protein was also found in the periplasm. This result confirms previous semi-in vitro data and supports the suggestion that a conformational change in a membrane-bound intermediate is a normal part of the secretory pathway.     

Sealing junctions in a number of arachnid tissues

The junctions present in the central nervous system (CNS), midgut, silk gland and venom gland of arachnids have been investigated. Special care was taken to try to locate tight junctions in tissue other than CNS but they were not found in any of the other tissues. The detailed structure of the junctions present are discussed. The tight junctions present in CNS are somewhat different in appearance and fracturing behaviour to most vertebrate tight junctions and closely resemble only those found in Urochordates (a non-vertebrate chordate). The two types of septate junctions found in the other tissues belong to the pleated septate and smooth septate classes but show some interesting differences. It appears probable that the septate junctions in Arachnida, Merostomata and Myriopoda have different fracturing properties from those found in other arthropods. The finding that only septate junctions are present in most arachnid tissues, although tight junctions are present in CNS, is discussed in the context of the sealing function of septate junctions in invertebrate tissues.     

Absence of carotenes and presence of a tertiary methoxy group in a carotenoid from a thermophilic filamentous photosynthetic bacterium Roseiflexus castenholzii.

We identified pigments in a thermophilic filamentous photosynthetic bacterium Roseiflexus castenholzii strain HL08. We detected neither bacteriochlorophyll (BChl) c nor carotenes in this bacterium cultured under the aerobic dark and the anaerobic light conditions, which may correspond to its lack of chlorosomes. In the cells cultured under the aerobic dark conditions, the carotenoids were derivatives of keto-gamma-carotene, and the major ones were methoxy-keto-myxocoxanthin and keto-myxocoxanthin glucoside fatty acid ester. Although the tertiary methoxy group at C-1' and the double bond at C-3',4' in the psi end group of carotenoid, such as spirilloxanthin, have only been found in purple bacteria, this was the first such report in other bacterial groups. The fatty acid moiety was composed of iso fatty acids, which were rare in the cellular lipids. In the cells cultured under the anaerobic light conditions, in addition to these keto-carotenoids, we also found non-oxidized carotenoids (derivatives of gamma-carotene). Concerning the esterifying alcohol of BChl a, we found a substantial amount of geranylgeraniol, although the major component was phytol. The existence of these pigments makes this bacterium unique among the known species in CHLOROFLEXACEAE.     

Biooxidation of a gold-bearing pyrite-arsenopyrite concentrate

Abstract: Two years of BIOX pilot plant data have been examined for steady state conditions and then correlated using logistic kinetics. It was found that the logistic equation not only predicted the performance of individual stages but also the degree of biooxidation across the entire cascade of bioreactors. It was found that the rate constant was 1.3 day^-1 in the first three stages and 0.3 day^-1 in the fourth stage. The maximum removal constant was 0.90 in stage 1 and 0.99 in the remaining stages. Plant retention time ranged from 4 to 12 days with corresponding sulphide oxidation varying from 82 to 98% respectively, and primary stage removal rates varying from 8.9 to 4.4 kg m^-3 day^-l, respectively. In addition, batch biooxidation data were obtained. The biooxidation rate was found to be about half that for the continuous bioreactors. This is in agreement with the findings of several other workers. The specific rates of bioxidation of pyrite and arsenopyrite were very similar for the bulk concentrate at about 0.15 day^-1. However, it was significant that the biooxidation of arsenopyrite in the mixed mineral preceded that of pyrite, suggesting a sequential mechanism. Gold liberation was found to be linearly related to arsenopyrite biooxidation but oxidation of pyrite appears to be preferential in the gold-rich regions.     

Coral encrusted concretions: a key to recognition of a 'shale on shale' erosion surface

Coral encrusted septarian concretions have been found along an obscure diastem within the Penn Yan Shale Member (Genesee Group, Upper Devonian) near Canandaigua Lake, New York. These hiatus-concretions ( sensu Voigt) are found associated with an erosional discontinuity surface in the shale. The restriction of coral growth to exposed concretion and wood found on the erosion surface, indicates a differential substrate preference exhibited by these animals. Diagenesis, both prior to and following this erosion event, produced various physical structures whose time of formation can be estimated from observed cross-cutting relationships with one another. An erosion-related feature establishing an early-diagenetic age for septarial fractures within concretions is described, and the origin and significance of the diastem is discussed.     

Discovery of a new type of restriction and modification in a group of intestinal bacteria]

The adsorption of 23 new lambdoid bacteriophages to 547 strains which isolated from natural population of Enterobacteriaceae was studied. The frequency of positive combinations of phage-bacterium with adsorption is not more than 2%. A study of possible causes of limited growth of lambdoid phages in the bacterial strains revealed that neither homoimmune prophage nor prophage P2 are single factors of the growth limitation. It is found that in natural populations a selection of bacterial strains with the least limitation of phage takes place. Three cases of killing bacteria after infection with high multiplicity are found. The reason of the killing effect is manifestation of some functions by infecting phages. A new restriction-modification system is found which differs from restriction-modification system A, B, K, 15, P1, EcoRI, EcoRII. The most of strains, which adsorb phages but do not support their growth, are supposed to possess several mechanisms of restriction. Thus, the search of new restriction system in Escherichia coli is worthwhile.     

Elastase is a constituent product of T cells

Proteases produced by immune cells have been found to be important components of the immune response to antigen. A protease previously unrecognized as a specific T cell product has been identified which has the gene sequence, serologic crossreactivity, and enzymatic specificity of elastase. T cell elastase, found in combination with the natural elastase inhibitor alpha 1-antitrypsin (alpha 1-protease inhibitor, alpha 1-PI), is produced by both CD4+ and CD8+ T lymphocytes, and is found both in a membrane-bound and in a soluble form in murine T cell lines.     

Production of valine by a Bacillus sp.

A bacterium isolated from Burdwan (India) soil was found to accumulate L-valine in the growth medium and identified to be a strain of Bacillus subtilis. The strain is able to grow and accumulate valine in a purely synthetic medium, but supplementation of the synthetic medium with either Casamino acids or yeast extract or with both, significantly improves the yield. The entire fermentation period can be divided into a growth phase and a production phase, which can be prolonged by adjustment of pH to the neutral range. Among the different carbon and nitrogen sources tested glucose at 8.5% and L-glutamic acid at 0.8%, respectively, were found most suitable. Cane sugar molasses tested as a substitute for glucose significantly stimulated growth but valine production was less. Different vitamins tested stimulated growth and valine yield and an inoculum level of 10% (v/v) of the medium was found to be optimal. The yield of valine under optimal conditions was found to be 4.53 g per litre of the medium. Valine has been isolated in crystalline form from the fermented broth by ion exchange resin chromatography and found to be a pure sample of the L-isomer.