Autolysis in vitro of cotton (Gossypium hirsutum) fibre cell walls

Root growth of partly defoliated young peach seedlings [ Prunus persica (L.) Batsch. cv. Lovell] was significantly promoted by application of myo-inositol to the cut surface of the stem. Addition of benzylaminopurine (BA) combined with sucrose enhanced the promotive effect of myo-inositol on root growth, but addition of sucrose alone, suppressed it. Spraying rooted peach cuttings (nectarine cv. Sunred) with myo-inositol and defoliating them after 5 days increased the incorporation of amino acids into proteins in excised roots, obtained from the sprayed plants, as compared with roots from plants sprayed with water, or sucrose, or sucrose + myo-inositol. Myo-inositol applied in combination with kinetin or BA to stems of young peach seedlings (cv. Lovell) or rooted peach cuttings (cv. Almog) promoted the basipctal translocation of the two cytokinins in the stem and acropetally into the small lateral roots. Addition of sucrose voided this effect on the cytokinins. BA, when applied together with myo-inositol, was partly converted into an additional cytokinin-active compound in the roots.
Application of BA to either roots or tops of rooted peach cuttings (cv. Almog) resulted in the accumulation of myo-inositol (supplied through the cut surface of the stem) in the plant part to which BA had been applied.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Approaches to breeding for salinity tolerance - a case study on Porteresia coarctata

Cereals are the world's major source of food for human nutrition. Among these, rice (Oryza sativa) is the most prominent and represents the staple diet for more than two-fifths (2.4 billion) of the world's population, making it the most important food crop of the developing world (Anon., 2000a). Rice production in vast stretches of coastal areas is hampered due to high soil salinity. This is because rice is a glycophyte and it does not grow well under saline conditions. In order to increase rice production in these areas there is a need to develop rice varieties suited to saline environments. Research has shown that Porteresia coarctata, a highly salt tolerant wild relative of rice growing in estuarine soils, is an important material for transferring salt tolerant characteristics to rice. It is quite possible that Porteresia may be used as a parent for evolving better and truly salt resistant varieties. The inadequate results and the difficulties associated with conventional breeding techniques necessitate the use of the tools of crop biotechnology in unravelling some of the characteristics of Porteresia that have been highlighted in this report. In view of the limited resources available for increasing salinity tolerance to the breeders to wild rice germplasm, Porteresia is undoubtedly one of the key source species for elevating salinity tolerance in cultivated rice.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Sampling to Assess a Re-Established Appalachian Forest in Ohio Based on Gelechioid Moths (Lepidoptera: Gelechioidea)

A list of microlepidoptera belonging to the superfamily Gelechioidea was produced from June trap samples from sites within the Wayne National Forest (Lawrence County), an Appalachian forest in Southern Ohio that was once a greatly disturbed area and has since re-established over a period of nearly 100 years. The composition and diversity of Lawrence county is compared to lists of gelechioid moths generated by other surveys in the eastern United States: the Great Smoky Mountains National Park, an Ohio study (Summerville and Crist 2003), and unpublished data from Connecticut (Wagner). From comparison with these studies, we address two questions: (1) How well do passive surveys of Gelechioidea compare to more labor intensive surveys? (2) How does the regenerated Wayne National Forest compare to other well documented areas with respect to gelechioid diversity? Our sample of diversity, though more narrow in time and area, compares favorably to more exhaustive sampling and demonstrates that it may be more efficient to focus on target groups in focal localities when time and resources are limited rather than conduct extensive sampling programs.     

Bacteriocinogenic Potential of Bacillus amyloliquefaciens Isolated from Kimchi,a Traditional Korean Fermented Cabbage

Bacteriocin production is considered a favorable property for various beneficial cultures. In addition to their potential as biopreservatives, bacteriocins are also promising alternatives for the control of multidrug-resistant pathogens and the inhibition of some viruses and cancer cells. The objective of this study was to screen and characterize a bacteriocin-producing strain with the aim of its future application for control of Listeria monocytogenes, an important food-borne pathogen. A total of 22 potentially bacteriocinogenic strains active against L. monocytogenes ATCC15313 were isolated from locally produced kimchi through a three-level approach. Pure cultures were obtained according to good microbiological practices and differentiated through RAPD-PCR using the primers OPL01, OPL09, and OPL11. Altogether, 5 strains were selected for further study. Specific focus was given to strain ST05DL based on its specific inhibitory activity against L. monocytogenes ATCC15313, while not affecting different strains belonging to the genera Lactobacillus, Pediococcus, Leuconostoc, and Weissella, most of which are beneficial microorganisms. The strain ST05DL was identified as Bacillus amyloliquefaciens based on its sugar fermentation profile obtained through API50CHB analysis and 16S rRNA partial sequencing. The antimicrobial compound produced by B. amyloliquefaciens ST05DL was found to be sensitive to pepsin and α-chymotrypsin, evidence of its proteinaceous nature. The presence of skim milk, NaCl, Tween 80, glycerol, and SDS did not affect the antimicrobial activity. The addition of 20% cell-free supernatant (CFS) obtained from a 24-h culture of B. amyloliquefaciens ST05DL to an exponentially growing culture of L. monocytogenes ATCC15313 successfully inhibited the test microorganisms during the monitored 10-h incubation. Optimal bacteriocin production by B. amyloliquefaciens ST05DL was observed during the stationary phase at 12 h (800 AU/mL) and remained stable for the next 15 h. The ratio between live and dead cells during this period was 74.37% and 25.66%, respectively, as determined by flow cytometry. The presence of the virulence genes hblA, hblB, hblC, nheA, nheB, and nheC was not detected in the total DNA of B. amyloliquefaciens ST05DL, and the strain was resistant only to ampicillin out of 10 tested antibiotics. Future evaluation of expressed bacteriocin/s by B. amyloliquefaciens ST05DL (amino acid sequence, molecular mass, cytotoxicity, detailed mode of action, etc.), will be the next step in the characterization and its potential application as biopreservative and/or pharmaceutical product.

     

Assessment of the modulating effects of fructo-oligosaccharides on fecal microbiota using human flora–associated piglets

We first used human flora–associated (HFA) piglets, a significantly improved model for research on human gut microbiota, to study the effects of short-chain fructo-oligosaccharides (scFOS) on the gut bacterial populations. Ten neonatal HFA piglets were assigned to receive basal diets alone or supplemented with scFOS (0.5 g/kg body weight/day) from 1 to 37 days after birth (DAB). The impact of scFOS on the fecal bacterial populations of the piglets before (12 DAB), during (17 DAB), and after (25 and 37 DAB) weaning were monitored by PCR-denaturing gradient gel electrophoresis and real-time quantitative PCR. The Bifidobacterium genus was stimulated consistently, except during weaning, confirming the bifidogenic property of scFOS. At 12 DAB, the Clostridium leptum subgroup was decreased and two unknown Bacteroides-related species were increased; at 25 DAB, the C. leptum subgroup and Subdoligranulum variabile-like species were elevated, whereas one unknown Faecalibacterium-related species was suppressed; and at 37 DAB, the Bacteroides genus was decreased. The results showed that effects of scFOS on non-bifidobacteria varied at different developmental stages of the animals, warranting further investigation into the host-development-related effects of prebiotics on the gut microbiota and the host physiology using the HFA piglets as a model for humans.     

Induced root-secreted phenolic compounds as a belowground plant defense

Rhizosphere is the complex place of numerous interactions between plant roots, microbes and soil fauna. Whereas plant interactions with aboveground organisms are largely described, unravelling plant belowground interactions remains challenging. Plant root chemical communication can lead to positive interactions with nodulating bacteria, mycorriza or biocontrol agents or to negative interactions with pathogens or root herbivores. A recent study¹ suggested that root exudates contribute to plant pathogen resistance via secretion of antimicrobial compounds. These findings point to the importance of plant root exudates as belowground signalling molecules, particularly in defense responses. In our report,² we showed that under Fusarium attack the barley root system launched secretion of phenolic compounds with antimicrobial activity. The secretion of de novo biosynthesized t-cinnamic acid induced within 2 days illustrates the dynamic of plant defense mechanisms at the root level. We discuss the costs and benefits of induced defense responses in the rhizosphere. We suggest that plant defense through root exudation may be cultivar dependent and higher in wild or less domesticated varieties.Key words: root exudates, plant defense, t-cinnamic acid, fusarium, induced defensePlants grow and live in very complex and changing ecosystems. Because plants lack the mobility to escape from attack by pathogens or herbivores, they have developed constitutive and in addition inducible defenses that are triggered by spatiotemporally dynamic signaling mechanisms. These defenses counteract the aggressor directly via toxins or defense plant structures or indirectly by recruitment of antagonists of aggressors. Whereas induced defenses are well described in aboveground interactions, evidence of the occurrence of such mechanisms in belowground interactions remains limited. The biosynthesis of a defensive molecule could be both constitutive and inducible with a low level of a preformed pool (Fig. 1). In addition, upon encounter of an attacking organism, those levels could be induced to rise locally to a high level of active compound that is able to disarm the pathogen.^2,3 Only a few examples show that root exudates play a role in induced plant defense. Hairy roots of Ocimum basilicum secrete rosmarinic acid only when challenged by the pathogenic fungus Pythium ultimum.⁴ Wurst et al.⁵ reported on the induction of irridoid glycosides in root exudates of Plantago lanceolata in presence of nematodes. In vivo labelling experiments² with ¹³CO₂ showed the induction of phenolic compounds secreted by barley roots after Fusarium graminearum infection and the de novo biosynthesis of root secreted t-cinnamic acid within 2 days. These results show that the pool of induced t-cinnamic acid originated from both pre-formed and newly formed carbon pools (Fig. 1), highlighting a case of belowground induced defense inside and outside the root system.Open in a separate windowFigure 1Suggested mechanisms for the induction of root defense exudates in barley in response to Fusarium attack. Upon pathogen attack by Fusarium, the initial preformed pool of phenolic compounds is increased by the addition of inducible, de novo biosynthesized t-cinnamic acid. Both, the preformed pool and the de novo biosynthesized pool fuel the exudation of defense compounds from infected roots.The concept of fitness costs is frequently presented to explain the coexistence of both constitutive and induced defense.⁶ In the case of induced defense, resources are invested in defenses only when the plant is under attack. In the absence of an infection, plants can optimize allocation of their resources to reproduction and growth to compete with neighbours.⁷ Constitutive defenses are thought to be more beneficial when the probability of attack is high, whereas adjustable, induced defenses are more valuable to fight against an unpredictable pathogen. Non disturbed soil is a heterogeneous matrix where biodiversity is very high and patchy^8,9 and organism motility is rather restricted.¹⁰ As a consequence of the patchiness, belowground environment is expected to be favourable to selection for induced responses.¹¹ The absence of defense root exudates between two infections may form an unpredictable environment for soil pathogens and reduce the chance for adaptation of root attackers. Plants may also use escape strategies to reduce the effect of belowground pathogens. Henkes et al. (unpublished) showed that Fusarium-infected barley plants reduced carbon allocation towards infected roots within a day and increased allocation carbon to uninfected roots. These results illustrate how reallocation of carbon toward non infected root parts represents a way to limit the negative impact of root infection.We have demonstrated the potential of barley plants to defend themselves against soil pathogen by root exudation.² Even the barley cultivar ‘Barke’ used in our study, a modern cultivated variety, was able to launch defense machinery via exudation of antimicrobial compounds when infected by F. graminearum. We suggest that plant defense through root exudation might be cultivar dependent and perhaps higher in wild or less domesticated varieties. Taddei et al.¹² reported that constitutivelyproduced root exudates from a resistant Gladiolus cultivar inhibit spore germination of Fusarium oxysporum whereas root exudates from a susceptible cultivar do not affect F. oxysporum germination. Root exudates from the resistant cultivar contained higher amounts of aromaticphenolic compounds compared to the susceptible cultivar and these compounds may be responsible for the inhibition of spore germination. Metabolic profiling of wheat cultivars, ‘Roblin’ and ‘Sumai3’, respectively, susceptible and resistant to Fusarium Head Blight, showed that t-cinnamic acid was a discriminating factor responsible for resistance/defense function.¹³ Therefore it is likely that wild barley varieties hold higher defense capacities compare to cultivated varieties selected for high yield. In the future, plant breeders in organic and low-input farming could use root-system defense ability as new trait in varietal variation.