Seasonal regulation of a 24-kDa protein from red-osier dogwood (Cornus sericea) xylem

Previously, we showed that an apparent cell wall-plasma membrane interaction in xylem ray parenchyma differed between cold acclimated and non-acclimated red-osier dogwood (Cornus sericea L.) (Ristic and Ashworth 1994). For the present study, a calcium chloride extraction method was used to identify cell-wall-associated xylem proteins that accumulated during periods of cold acclimation. A 24-kDa protein represented the predominant protein in both total protein and CaCl2 extracts during cold acclimation of field-grown plants. Two-dimensional gel electrophoresis separated the 24-kDa protein into four basic isoforms. The most abundant and basic isoform had a high glycine content. In-gel digestion of this basic 24-kDa isoform generated three partial peptide fragments, of which one exhibited homology to the dehydrin protein family. An anti-dehydrin polyclonal antibody cross-reacted with the 24-kDa protein, providing further evidence that this protein is related to dehydrins. The 24-kDa protein began to accumulate in late August, reached a maximum in midwinter, declined during the spring months and was absent in early summer.     

Electrical conductivity in the precambrian lithosphere of western canada

The subcrustal lithosphere underlying the southern Archean Churchill Province (ACP) in western Canada is at least one order of magnitude more electrically conductive than the lithosphere beneath adjacent Paleoproterozoic crust. The measured electrical properties of the lithosphere underlying most of the Paleoproterozoic crust can be explained by the conductivity of olivine. Mantle xenolith and geological mapping evidence indicate that the lithosphere beneath the southern ACP was substantially modified as a result of being trapped between two nearly synchronous Paleoproterozoic subduction zones. Tectonically induced metasomatism thus may have enhanced the subcrustal lithosphere conductivity of the southern ACP.     

Monitoring of South Sinai coral reefs: influence of natural and anthropogenic factors

• 1. To monitor any impacts to coral reefs related to the exponential growth of tourism in the South Sinai region of the Egyptian Red Sea, nine stations were established at key reef sites over 2002–2003. At each station coral cover was determined using a video survey method at depths of 3, 7 and 16 m, and fish abundance by underwater visual census at depths of 3 and 10 m.
• 2. Mean total coral cover (hard plus soft) ranged from 58% to 23% at 3 m, 50% to 14% at 7 m, and 52% to 13% at 16 m, and hard coral cover from 37.5% to 15.7% at 3 m, 32.8% to 7.0% at 7 m, and 17.8% to 2.2% at 16 m. Analyses confirmed differences in coral assemblage related to depth and wave exposure.
• 3. Fish abundances and assemblages also varied with depth and proximity of deep water. Also the one site subject to fishing had lower abundances of some commercial fish families and greater abundances of some herbivores.
• 4. Transects subject to greater tourist use did not segregate from those subject to less tourist use, despite evidence from other work of an effect from visitor damage to corals at some sites. This may be because visitors were more attracted to sites that had higher coral cover.
• 5. Comparison of the present data with that from past studies is difficult because of the differences in sites and method employed, but several observations suggest a moderate decline in coral cover during recent decades. Such a decline would be compatible with the recorded impact of an outbreak of crown‐of‐thorns starfish, Acanthaster planci, as well as with other evidence of accumulating damage by visitors.
• 6. Further monitoring using the same stations and consistent protocols is urgently required.

Copyright © 2008 John Wiley & Sons, Ltd.     

Farm management factors associated with bulk tank somatic cell count in Irish dairy herds

The relationship between bulk tank somatic cell count (SCC) and farm management and infrastructure was examined using data from 398 randomly selected, yet representative, Irish dairy farms where the basal diet is grazed grass. Median bulk tank SCC for the farms was 282,887 cells/ml ranging from 82,209 to 773,028 cells/ml. Two questionnaires were administered through face-to-face contact with each farmer. Herd-level factors associated with bulk tank SCC were determined using linear models with annual somatic cell score (i.e., arithmetic mean of the natural logarithm of bulk tank SCC) included as the dependent variable. All herd level factors were analysed individually in separate regression models, which included an adjustment for geographical location of the farm; a multiple regression model was subsequently developed. Management practices associated with low SCC included the use of dry cow therapy, participation in a milk recording scheme and the use of teat disinfection post-milking. There was an association between low SCC and an increased level of hygiene and frequency of cleaning of the holding yard, passageways and cubicles. Herd management factors associated with bulk tank SCC in Irish grazing herds are generally in agreement with most previous studies from confinement systems of milk production.     

Colossal Magnetoresistance Without Mn3+/Mn4+ Double Exchange in the Stoichiometric Pyrochlore Tl2Mn2O7

Structural analysis from powder neutron and single-crystal x-ray diffraction data for a sample of the Tl2Mn2O7 pyrochlore, which exhibits colossal magnetoresistance (CMR), shows no deviations from ideal stoichiometry. This analysis gives an Mn-O distance of 1.90 angstroms, which is significantly shorter than the Mn-O distances (1.94 to 2.00 angstroms) observed in phases based on LaMnO3 perovskites that exhibit CMR. Both results in Tl2Mn2O7 indicate oxidation states very close to Tl23+Mn24+O7. Thus, Tl2Mn2O7 has neither mixed valence for a double-exchange magnetic interaction nor a Jahn-Teller cation such as Mn3+, both of which were thought to have an important function in CMR materials. An alternate mechanism for CMR in Tl2Mn2O7 based on magnetic ordering driven by superexchange and strong spin-fluctuation scattering above the Curie temperature is proposed here.     

Seasonal variations in soluble sugars and starch within woody stems of Cornus sericea L

Carbohydrate composition changed seasonally in red osier dogwood (Cornus sericea L.) stem tissues. Starch concentration was highest in fall and decreased to a minimum in midwinter. Coincident with the breakdown of starch in fall, there was an increase in the concentrations of soluble sugars. Soluble sugars were present in highest concentrations in midwinter. Glucose, fructose, sucrose, and raffinose were the predominant soluble sugars present in both bark and wood tissues. In early spring, the soluble sugar concentration decreased and the concentration of starch increased. The seasonal interchange between sugars and starch did not simply reflect a general quantitative shift in the balance between sugars and starch because qualitative changes in soluble sugars were also noted. The most striking changes involved the trisaccharide raffinose. Raffinose was barely detectable in summer and early fall, but increased to one fifth and one third of the total soluble sugars in January samples of bark and wood tissues, respectively. The potential physiological role of raffinose in overwintering red osier dogwood tissue is discussed.     

A lupinosis-associated myopathy in sheep and the effectiveness of treatments to prevent it

A lupinosis-associated myopathy occurred in 26 of 48 sheep given a crude toxic extract of Phomopsis leptostromiformis, and in 18 of 34 sheep that grazed a toxic lupin stubble. Treatment with selenium or alpha-tocopherol alone neither prevented nor cured the myopathy, but selenium and alpha-tocopherol together may have been partially effective. Among the group of 48 intoxicated sheep, those with myopathy had a significantly lower mean terminal concentration of alpha-tocopherol in their livers than those with no myopathy. There was no relationship between the severity of liver injury and the occurrence of the myopathy. It was considered that this lupinosis-associated myopathy may have a similar pathogenesis to nutritional myopathy. Data on plasma creatine phosphokinase and erythrocyte glutathione peroxidase activities, plasma alpha-tocopherol concentrations and terminal tissue concentrations of selenium and alpha-tocopherol are presented.