A rapid technique to predict malting quality in barley prior to harvest

Samples of grain from three spring barley cultivars of differing malting quality were collected at regular intervals during four weeks prior to harvest. The samples were dried, then assessed for relative grain hardness using the "Milling Energy" test. Ranking order of the cultivars for this character, which relates strongly to malting quality, was unaltered throughout. In a further experiment, it was demonstrated that selection for milling energy could be successfully practised on oven-dried grain collected six weeks after ear emergence.     

Dynamics of chest wall in preterm infants

The chest wall of the preterm infant has visible paradoxical movement during breathing, because of its greater flexibility than those of older children and adults. We studied the dynamics of the chest wall in 10 preterm infants to describe the interaction of the chest wall volume, as partitioned by the inductance plethysmograph, and the transthoracic and abdominal pressures. There was considerable hysteresis between the chest wall volume and the transthoracic pressure, and it had linear pressure-volume behavior during airway occlusion, late inspiration, and early expiration. The slope of this pressure-volume relationship, or the instantaneous chest wall compliance, averaged 0.89 +/- 0.16 and 0.94 +/- 0.18 ml/cmH2O for the respiratory effort during airway occlusion and early expiration, respectively. The dynamic compliance was considerably greater, averaging 7.8 +/- 2.3 ml/cmH2O. This resistive pressure-volume behavior was not related to the absolute value of or the rate of development of the esophageal or abdominal pressures. This additional degree of freedom of motion of the chest wall suggests that its linkage to the diaphragm is flexible, which provides a braking force for expiration and allows free movement of the diaphragm for breathing movements before birth.     

Microbial Transport, Survival, and Succession in a Sequence of Buried Sediments

Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded.     

Distinct Roles for the p110α and hVPS34 Phosphatidylinositol 3′-Kinases in Vesicular Trafficking, Regulation of the Actin Cytoskeleton, and Mitogenesis

We have examined the roles of the p85/ p110α and hVPS34 phosphatidylinositol (PI) 3′-kinases in cellular signaling using inhibitory isoform-specific antibodies. We raised anti-hVPS34 and anti-p110α antibodies that specifically inhibit recombinant hVPS34 and p110α, respectively, in vitro. We used the antibodies to study cellular processes that are sensitive to low-dose wortmannin. The antibodies had distinct effects on the actin cytoskeleton; microinjection of anti-p110α antibodies blocked insulin-stimulated ruffling, whereas anti-hVPS34 antibodies had no effect. The antibodies also had different effects on vesicular trafficking. Microinjection of inhibitory anti-hVPS34 antibodies, but not anti-p110α antibodies, blocked the transit of internalized PDGF receptors to a perinuclear compartment, and disrupted the localization of the early endosomal protein EEA1. Microinjection of anti-p110α antibodies, and to a lesser extent anti-hVPS34 antibodies, reduced the rate of transferrin recycling in CHO cells. Surprisingly, both antibodies inhibited insulin-stimulated DNA synthesis by 80%. Injection of cells with antisense oligonucleotides derived from the hVPS34 sequence also blocked insulin-stimulated DNA synthesis, whereas scrambled oligonucleotides had no effect. Interestingly, the requirement for p110α and hVPS34 occurred at different times during the G1–S transition. Our data suggest that different PI 3′-kinases play distinct regulatory roles in the cell, and document an unexpected role for hVPS34 during insulin-stimulated mitogenesis.     

Sulfation of fucoidin in focus embryos: III. Required for localization in the rhizoid wall

Zygotes of the brown alga Fucus distichus L. Powell accumulate a sulfated polysaccharide (fucoidin) in the cell wall at the site of rhizoid formation. Previous work indicated that zygotes grown in seawater minus sulfate do not sulfate the preformed fucan (an unsulfated fucoidin) but form rhizoids. Under these conditions, we determined whether sulfation of the fucan is required for its localization in the rhizoid wall. This was accomplished by developing a specific stain for both the fucan and fucoidin. Using a precipitin assay, we demonstrated in vitro that the lectin ricin (RCA(I)) specifically complexes with both the sulfated and desulfated polysaccharide. No precipitate is observed when either is incubated in 0.1 M D-galactose or when RCA(I) is mixed with laminarin or alginic acid, the other major polysaccharides in Fucus. RCA(I) conjugated with fluorescein isothiocyanate (FITC) is also shown to bind specifically to fucoidin using a filter paper (DE81) assay. When added to zygotes, RCA(I)-FITC binds only to the site of fucoidin localization, i.e., the rhizoid cell wall. However, RCA(I)-FITC is not observed in the rhizoid wall of zygotes grown in the absence of sulfate. This observation is not due to inability of RCA(I)-FITC to bind to the fucan in vivo. Chemically desulfated cell walls that contained fucoidin in the rhizoid wall bind RCA(I)-FITC only in the rhizoid region. Also, the concentration of fucose-containing polymers and polysaccharides that form precipitates with RCA(I) is the same in embryos grown in the presence or absence of sulfate. If sulfate is added back to cultures of zygotes grown without sulfate, fucoidin is detected at the rhizoid tip by RCA(I)-FITC several hours later. These results support the conclusion that the enzymatic sulfation of the fucan is a modification of the polysaccharide required for its localization and/or assembly into a specific region of the cell wall.     

Biochemistry and molecular biology of exocellular fungal beta-(1,3)- and beta-(1,6)-glucanases

Many fungi produce exocellular beta-glucan-degrading enzymes, the beta-glucanases including the noncellulolytic beta-(1,3)- and beta-(1,6)-glucanases, degrading beta-(1,3)- and beta-(1,6)-glucans. An ability to purify several exocellular beta-glucanases attacking the same linkage type from a single fungus is common, although unlike the beta-1,3-glucanases, production of multiple beta-1,6-glucanases is quite rare in fungi. Reasons for this multiplicity remain unclear and the multiple forms may not be genetically different but arise by posttranslational glycosylation or proteolytic degradation of the single enzyme. How their synthesis is regulated, and whether each form is regulated differentially also needs clarifying. Their industrial potential will only be realized when the genes encoding them are cloned and expressed in large quantities. This review considers what is known in molecular terms about their multiplicity of occurrence, regulation of synthesis and phylogenetic diversity. It discusses how this information assists in understanding their functions in the fungi producing them. It deals largely with exocellular beta-glucanases which here refers to those recoverable after the cells are removed, since those associated with fungal cell walls have been reviewed recently by Adams (2004). It also updates the earlier review by Pitson et al. (1993).     

Competition and succession among coral endosymbionts

Host species often support a genetically diverse guild of symbionts, the identity and performance of which can determine holobiont fitness under particular environmental conditions. These symbiont communities are structured by a complex set of potential interactions, both positive and negative, between the host and symbionts and among symbionts. In reef‐building corals, stable associations with specific symbiont species are common, and we hypothesize that this is partly due to ecological mechanisms, such as succession and competition, which drive patterns of symbiont winnowing in the initial colonization of new generations of coral recruits. We tested this hypothesis using the experimental framework of the de Wit replacement series and found that competitive interactions occurred among symbionts which were characterized by unique ecological strategies. Aposymbiotic octocoral recruits within high‐ and low‐light environments were inoculated with one of three Symbiodiniaceae species as monocultures or with cross‐paired mixtures, and we tracked symbiont uptake using quantitative genetic assays. Priority effects, in which early colonizers excluded competitive dominants, were evidenced under low light, but these early opportunistic species were later succeeded by competitive dominants. Under high light, a more consistent competitive hierarchy was established in which competitive dominants outgrew and limited the abundance of others. These findings provide insight into mechanisms of microbial community organization and symbiosis breakdown and recovery. Furthermore, transitions in competitive outcomes across spatial and temporal environmental variation may improve lifetime host fitness.     

Upper limb H reflexes and somatosensory evoked potentials modulated by movement.

In the human lower limb, the magnitudes of both Hoffmann (H) reflexes and primary somatosensory evoked potentials (SEPs) from scalp electrodes, are reduced by active and/or passive movement. We surmised that similar effects occur for the upper limb and specifically hypothesised that amplitudes of median nerve induced flexor carpii radialis H reflexes and cortical SEPs are reduced with passive movement about the wrist or elbow. The results showed (P<0. 05) that either movement significantly attenuated mean magnitudes of SEPs elicited from stimulation at elbow or wrist and that reflex magnitudes attenuated with wrist movement. Thus, the upper limb shows similar movement-induced modulation to the lower limb. These attenuations of fast conducting sensory paths consequent to movement per se, may be a basic level of motor control, initiated from muscle mechanoreceptor discharge. Upon this basic level, more complex modulations then may be laid as appropriate for the particular characteristics of active motor tasks.     

Kinetic measures of restabilisation during volitional stepping reveal age-related alterations in the control of mediolateral dynamic stability

Research examining age-related changes in dynamic stability during stepping has recognised the importance of the restabilisation phase, subsequent to foot-contact. While regulation of the net ground reaction force (GRF_net) line of action is believed to influence dynamic stability during steady-state locomotion, such control during restabilisation remains unknown. This work explored the origins of age-related decline in mediolateral dynamic stability by examining the line of action of GRF_net relative to the centre of mass (COM) during restabilisation following voluntary stepping. Healthy younger and older adults (n=20 per group) performed three single-step tasks (varying speed and step placement), altering the challenge to stability control. Age-related differences in magnitude and intertrial variability of the angle of divergence of GRF_net line of action relative to the COM were quantified, along with the peak mediolateral and vertical GRF_net components. The angle of divergence was further examined at discrete points during restabilisation, to uncover events of potential importance to stability control. Older adults exhibited a reduced angle of divergence throughout restabilisation. Temporal and spatial constraints on stepping increased the magnitude and intertrial variability of the angle of divergence, although not differentially among the older adults. Analysis of the time-varying angle of divergence revealed age-related reductions in magnitude, with increases in timing and intertrial timing variability during the later phase of restabilisation. This work further supports the idea that age-related challenges in lateral stability control emerge during restabilisation. Age-related alterations during the later phase of restabilisation may signify challenges with reactive control.