Control of xyloglucan endotransglucosylase activity by salts and anionic polymers

Crude extracts of cauliflower florets had high xyloglucan endotransglucosylase (XET) activity, but this was largely lost after partial purification and de-salting. Activity was restored (promoted up to 40-fold) by any of a wide variety of inorganic and organic salts. Optimum concentrations for Na⁺, K⁺ and NH₄⁺ salts were typically ~300 mM. The chlorides of Ca²⁺, Mg²⁺, Al³⁺ and La³⁺ were optimally active at lower concentrations (e.g. 0.1 mM LaCl₃), but became inhibitory at higher concentrations (e.g. 5 mM LaCl₃). Some anionic polysaccharides at 0.04–0.2% w/v (e.g. gum arabic, pectin and hypochlorite-oxidised xyloglucan) promoted the XET activity of de-salted enzyme, especially if a sub-optimal concentration of NaCl was also present; others (e.g. homogalacturonan, 4-O-methyl-glucuronoxylan and alginate) were inhibitory. Similar ionic effects were noted on the XET activity of the Arabidopsis protein XTH24 (heterologously expressed by insect cells); in this case carboxymethylcellulose was also stimulatory. To look for endogenous modulators of XET activity, we prepared a cold-water extract of cauliflower florets; after boiling and centrifugation, the supernatant [boiled cauliflower preparation (BCP)] promoted the XET activity of de-salted cauliflower enzyme and of XTH24. About half the activator present in BCP was an ethanol-precipitable, anionic polymer of apparent M_r <5,000. After acid hydrolysis the polymer yielded much arabinose and galactose, and small amounts of galacturonic and glucuronic acids amino acids were also present. The polymer may thus contain arabinogalactan-proteins. We suggest that acidic polymers and/or other apoplastic ions are naturally occurring regulators of XET action in vivo, and may thus control cell wall assembly, loosening, and growth.Abbreviations AGP Arabinogalactan-protein - BCP Boiled cauliflower preparation (cold-water-extract of cauliflower florets that was then boiled) - CMC Carboxymethylcellulose - DE Degree of esterification - GalA Galacturonic acid - GlcA Glucuronic acid - K_av Elution volume relative to those of Blue Dextran (K_av=0) and glucose (K_av=1) - TFA Trifluoroacetic acid - V₀ Void volume (centre of elution peak of Blue Dextran) - V_i Totally included volume (centre of elution peak of glucose) - XEH Xyloglucan endohydrolase (activity) - XET Xyloglucan endotransglucosylase (activity) - XLLGol A xyloglucan-derived oligosaccharide, xylose₃·glucose₃·galactose₂·glucitol - XTH Xyloglucan endotransglucosylase/hydrolase (protein) - µ Ionic strength     

Physiological factors in stretcher carriage performance

In this study we examined the anthropometric and physiological factors that may account for the ability to carry a casualty on a stretcher. Eleven young soldiers were pretested to obtain their anthropometry, body composition, physical fitness, and muscle cross-sectional areas. They then performed a two-person manual carry of a stretcher containing an 82-kg manikin while walking on a treadmill at a speed of 4.8 km/h. Subjects walked until volitional fatigue, as indicated by slippage of the stretcher from their hands. Average (SD) carriage time was 2.7(1.4) min with a range of 1.4-6.4 min. A stepwise multiple linear regression revealed that forearm bone-plus-muscle cross-sectional area, thigh muscle cross-sectional area, and push-up performance accounted for most of the variance in hand carriage time (r2 = 0.99, P < 0.001). These data suggest that muscle cross-sectional area and upper-body muscular endurance are important physiological factors in the ability to carry a loaded stretcher by hand.     

The water-soluble fraction of bee venom produces antinociceptive and anti-inflammatory effects on rheumatoid arthritis in rats

We recently demonstrated that bee venom (BV) injection into the Zusanli acupoint produced a significantly more potent anti-inflammatory and antinociceptive effect than injection into a non-acupoint in a Freund's adjuvant induced rheumatoid arthritis (RA) model. However, the precise BV constituents responsible for these antinociceptive and/or anti-inflammatory effects are not fully understood. In order to investigate the possible role of the soluble fraction of BV in producing the anti-arthritic actions of BV acupuncture, whole BV was extracted into two fractions according to solubility (a water soluble fraction, BVA and an ethylacetate soluble fraction, BVE) and the BVA fraction was further tested.Subcutaneous BVA injection (0.9 mg/kg/day) into the Zusanli acupoint was found to dramatically inhibit paw edema and radiological change (i.e. new bone proliferation and soft tissue swelling) caused by Freund's adjuvant injection. BVA treatment also reduced the increase in serum interleukin-6 caused by RA induction to levels observed in non-arthritic animals. In addition, BVA therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). Finally, BVA treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. In contrast, BVE treatment (0.05 mg/kg/day) failed to show any anti-inflammatory or antinociceptive effects on RA.The results of the present study demonstrate that BVA is the effective fraction of whole BV responsible for the antinociception and anti-inflammatory effects of BV acupuncture treatment. Thus it is recommended that this fraction of BV be used for long-term treatment of RA-induced pain and inflammation. However, further study is necessary to clarify which constituents of the BVA fraction are directly responsible for these anti-arthritis effects.     

Does a linear position transducer placed on a stick and belt provide sufficient validity and reliability of countermovement jump performance outcomes?

Manufacturers recommend that linear position transducers (LPTs) should be placed on the side of a barbell (or wooden dowel) to measure countermovement jump (CMJ) height, but the validity and reliability of this placement have not been compared to other attachment sites. Since this recommended attachment site is far from the centre of mass, a belt attachment where the LPT is placed between the feet may increase the validity and reliability of CMJ data. Thirty-six physical education students participated in the study (24.6 ± 4.3 years; 177.0 ± 7.7 cm; 77.2 ± 9.0 kg). Parameters from the two LPT attachments (barbell and belt) were simultaneously validated to force plate data, where the nature of bias was analysed (systematic vs random). The within-session and between-session reliability of both attachment sites were compared to force plate data using a test-retest protocol of two sets of 5 CMJs separated by 7 days. The LPT provided highly reliable and valid measures of peak force, mean force, mean power, and jump height, where the bias was mostly systematic (r² > 0.7; ICC > 0.9). Peak velocity, mean velocity, and peak power were in very good agreement with the force plate and were highly reliable (r² > 0.5; ICC > 0.7). Therefore, both attachment sites produced similar results with a systematic bias compared to force plate data. Thus, both attachment sites seem to be valid for assessing CMJs when the measuring tool and site remain consistent across measurements. However, if LPT data are to be compared to force plate data, recalculation equations should be used.     

Botanical affinity of pollen harvested by Apis mellifera L. in a semi-arid area from Bahia,Brazil

We analysed the botanical composition of pollen harvested by Apis mellifera L. in the Canudos Biological Station, Bahia, Brazil, and the influence of climatic factors on pollen sample composition was assessed. Forty-six pollen types were identified belonging to species occurring in the study area. The family Leguminosae was of significant importance amongst the samples, represented by ten pollen types. Diodia radula, Rhaphiodon echinus, and Mimosa misera pollen types occurred most constantly among the samples. We observed that isolated pollen class characterises samples analysed. It was also observed that pollen type richness is directly linked to rainfall, reflecting the strong influence of this climatic parameter on flowering intensity, and thus on the ability of the bees to obtain food resources.     

Differential label‐free quantitative proteomic analysis of avian eggshell matrix and uterine fluid proteins associated with eggshell mechanical property

Eggshell strength is a crucial economic trait for table egg production. During the process of eggshell formation, uncalcified eggs are bathed in uterine fluid that plays regulatory roles in eggshell calcification. In this study, a label‐free MS‐based protein quantification technology was used to detect differences in protein abundance between eggshell matrix from strong and weak eggs (shell matrix protein from strong eggshells and shell matrix protein from weak eggshells) and between the corresponding uterine fluids bathing strong and weak eggs (uterine fluid bathing strong eggs and uterine fluid bathing weak eggs) in a chicken population. Here, we reported the first global proteomic analysis of uterine fluid. A total of 577 and 466 proteins were identified in uterine fluid and eggshell matrix, respectively. Of 447 identified proteins in uterine fluid bathing strong eggs, up to 357 (80%) proteins were in common with proteins in uterine fluid bathing weak eggs. Similarly, up to 83% (328/396) of the proteins in shell matrix protein from strong eggshells were in common with the proteins in shell matrix protein from weak eggshells. The large amount of common proteins indicated that the difference in protein abundance should play essential roles in influencing eggshell strength. Ultimately, 15 proteins mainly relating to eggshell matrix specific proteins, calcium binding and transportation, protein folding and sorting, bone development or diseases, and thyroid hormone activity were considered to have closer association with the formation of strong eggshell.     

Complexation thermodynamics and the formation of the binary and the ternary complexes of tetravalent plutonium with carboxylate and aminocarboxylate ligands in aqueous solution of high ionic strength

The stability constants of the binary and the ternary complexes of Pu⁴⁺ have been measured for certain carboxylate and aminocarboxylate ligands in aqueous solution of I = 5.0 M (1 M perchloric acid + 4 M ionic strength perchlorate media) and temperatures of 0-45 °C by the solvent extraction technique. The stability constants of the binary and the ternary complexes increased with increased temperature. The complexation enthalpy and entropy of the binary Pu-Ox and the ternary Pu-EDTA-Ox and DGA complexes indicated the stability of these complexes is due to the highly favorable entropy contribution while complexation enthalpies either oppose complexation or are weakly favorable.     

Characterization of a cinnamoyl-CoA reductase that is associated with stem development in wheat

Cinnamoyl-CoA reductase (CCR) is responsible for the CoA ester to aldehyde conversion in monolignol biosynthesis, which diverts phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understanding of lignin biosynthesis and its biological function, a cDNA encoding CCR was identified from wheat (Triticum aestivum L.), and designated as Ta-CCR1. Phylogenetic analysis indicated that Ta-CCR1 grouped together with other monocot CCR sequences while it diverged from Ta-CCR2. DNA gel-blot and mapping analyses demonstrated that Ta-CCR1 is present as a single copy gene in the wheat genome. Recombinant Ta-CCR1 protein converted feruloyl CoA, 5-OH-feruloyl CoA, sinapoyl CoA, and caffeoyl CoA, but feruloyl-CoA was the best substrate, suggesting the preferential biosynthesis of G-type lignin. RNA gel-blot analysis indicated that Ta-CCR1 was highly expressed in stem, with lower expression in leaves, and undetectable expression in roots. CCR enzyme activity was increased progressively along with the lignin biosynthesis and stem maturity. During stem development, Ta-CCR1 mRNA levels remained high at elongation, heading, and milky stages in the wheat H4564 cultivar, while they declined dramatically at the heading and milky stages in stems of the C6001 cultivar. Ta-CCR1 mRNA expression paralleled extractable CCR enzyme activity in these two cultivars. Furthermore, high Ta-CCR1 mRNA levels and high CCR enzyme activity in wheat stem were correlated with a higher Klason lignin content and greater stem mechanical strength in the H4564 cultivar. This suggests that Ta-CCR1 and its related CCR enzyme may be involved in the regulation of lignin biosynthesis during stem maturity and then contributes to stem strength support in wheat.     

Pollinator visitation to mass-flowering courgette and co-flowering wild flowers: Implications for pollination and bee conservation on farms

Managing the complex relationship between pollinators and their habitat requirements is of particular concern to growers of pollinator-dependent crop species, such as courgette (Cucurbita pepo). Naturally occurring wild flowers (i.e. agricultural weeds) offer a free, sustainable, and often underappreciated resource for pollinators, however, they may compete with crop flowers for visits. To understand the extent to which floral resources mediate pollinator visitation to courgette flowers and courgette fields, plant community and pollinator visitation data were collected at two spatial scales: field scale (in margins, and in the cropped area) and farm scale (500 m and 2000 m radii) for nine courgette fields across the UK. Apis mellifera (honeybees) and Bombus spp. (bumblebees) were the only pollinators observed to visit courgette flowers. Bumblebees were significantly more abundant on courgette flowers in fields with a greater species richness of wild flowers in the crop, whilst honeybees were significantly more abundant on courgette flowers in areas with less semi-natural habitat. For both honeybees and bumblebees, their abundance in field margins did not significantly reduce their abundance on courgette flowers, suggesting that wild flowers were not competing with courgette flowers for pollinator visitation. Although solitary bees were not observed to visit courgette flowers, their abundance and species richness in courgette fields were significantly greater with more semi-natural habitat and a greater species richness of wild flowers. Therefore, allowing uncultivated areas around the crop to be colonised by species-rich wild flowers is an effective way of boosting the abundance of bumblebees, which are important visitors to courgette flowers, as well as the abundance and species richness of solitary bees, thereby benefitting pollinator conservation.