A microelectrochemical technique to measure trans‐plasma membrane electron transport in plant tissue and cells in vivo

A novel electrochemical technique was developed to enable high‐resolution measurements of trans‐plasma membrane reductase activity in vivo in growing plant tissue and single cells. Carbon fibre microelectrodes (CFMEs) with a tip diameter of 5 µm were used for electrochemical mapping of the reduction of the external impermeant electron acceptor ferricyanide along the root tip surface of 4‐d‐old maize seedlings. Ferricyanide reduction was detected in all locations along the first 12 mm of the growing root apex. However, a distinct peak in activity was detected at the proximal end of the elongation zone (1·5–4·5 mm from the apex), where reductase activity was three times greater than in more apical or distal regions. The inhibition of the ferricyanide reduction at all locations along the growing apex, by the vitamin K antagonists warfarin and dicumarol, supports previous data showing that electron transfer by the constitutive trans‐plasma membrane reductase is achieved via a quinone shuttle. We demonstrate that in addition to their utility in whole‐tissue/‐organ studies, CFMEs are sensitive enough to monitor trans‐plasma membrane electron transport in single cells.     

Effect of two randomised exercise programmes on bone mass of healthy postmenopausal women.

The effect of two structured exercise programmes on the bone mass of 48 healthy postmenopausal white women aged 50-62 was studied after one year. Volunteers were randomised to group 1 (control), group 2 (aerobic exercise), or group 3 (aerobic and strengthening exercises). Before and after the training programme each subject had evaluations of bone mass (determined by neutron activation analysis and expressed as calcium bone index) and maximum oxygen uptake attained on a multistage exercise treadmill test. After one year both exercise groups had higher levels of fitness and greater bone mass than controls. Mean values (2 SEM) for changes in the calcium bone index were -0.011 (0.037), 0.039 (0.035), and 0.066 (0.036) for groups 1, 2, and 3, respectively. Analysis of variance on the observed data and analysis of covariance adjusting changes to the initial mean value for the whole group showed significant differences between each exercise group and the controls but no difference between the exercise groups themselves. Both exercise groups showed a significant improvement in maximum oxygen uptake. This study suggests that exercise may modify bone loss in healthy postmenopausal women.     

Synthesis and pharmacological exploitation of clioquinol-derived copper-binding apoptosis inducers triggering reactive oxygen species generation and MAPK pathway activation

In the present study, we carried out Mannich-type reaction to synthesize clioquinol-derived 7-methyl-arylsulfonylpiperazine analogs with improved growth-inhibitory effects. 11 bearing 5-nitro group on the quinoline ring exhibited 26-fold more potent than that of clioquinol against HeLa cells with a GI₅₀ value of 0.71 μM. In addition, 11 revealed synergistic effects on the growth inhibition of HeLa cells with GI₅₀ values of 0.65, 0.25, and 0.06 μM in the presence of 1, 10, and 50 μM copper, respectively. Consistent to the clioquinol-mediated apoptosis, mechanistic study indicates that 9- and 11-induced growth inhibition is attributed to caspase-dependent pathway. Detection of reactive oxygen species in response to clioquinol, 9 and 11 confirmed that ROS was dramatically stimulated in the presence of copper and partially abolished upon treatment of 1 mM tempol. Further study indicated that 9- and 11-mediated induction of oxidative stress by ROS generation resulted in the activation MAPK pathway.     

The influence of bakers’ yeast cells on protein adsorption performance in dye-ligand expanded bed chromatography

The influence of whole yeast cells (0–15% w/v) on the protein adsorption performance in dye-ligand chromatography was explored. The adsorption of a model protein, bovine serum albumin (BSA), was selected to demonstrate this approach. The UpFront adsorbent (ρ=1.5 g/cm³) derivatised with Cibacron Blue 3GA and a commercially available expanded bed column (20 mm i.d.) from UpFront Chromatography, Denmark, were employed in the batch binding and expanded bed operation. The BSA binding capacity was demonstrated to not be adversely affected by the presence of yeast cells. The dynamic binding capacity of BSA at aC/C ₀=0..1 biomass concentration of 5, 10, 15% w/v were 9, 8, and 7.5 mg/mL of settled adsorbent, respectively.     

Extreme flooding mobilized dissolved organic matter from coastal forested wetlands

Lifespan of fine root plays an important role in regulating carbon (C) cycling in terrestrial ecosystems. Determination of root lifespan and elucidation of its regulatory mechanism in different plant communities are essential for accurate prediction of C cycling from ecosystem to regional scales. There are three major types of grasslands in the temperate steppes of Inner Mongolia, each dominated by a different species of common grass: Stipa krylovi, Stipa grandis, and Stipa breviflora. There have been no studies to compare the root dynamics among the three types of grasslands. In the present study, we determined root lifespan of the three grasslands using the rhizotron technique. We found that root lifespan differed substantially among the three major types of grasslands within the temperate steppes of Inner Mongolia, such that root lifespan of S. breviflora > S. grandis > S. krylovii grasslands. Root lifespan across the three types of grasslands displayed a similar temporal pattern, such that root lifespan followed the order of autumn-born roots > summer-born roots > spring-born roots. The spatial and temporal differences in root lifespan across the three types of grasslands were mainly related to contents of soluble sugars in roots of the dominant species and BNPP/ANPP ratio of the communities. The differences in root lifespan across the major types of grasslands and different seasons highlight the potential importance of taking these differences into account in models of future carbon cycling and climate change.     

Model systems to study the life cycle of human papillomaviruses and HPV-associated cancers

The prevalent human papillomaviruses(HPVs) infect either cutaneous or mucosal epithelium. Active Infections lead to epithelial hyperprolifeation and are usually cleared in healthy individuals within a year. Persistent infections in the anogenital tracts by certain high-risk genotypes such as HPV-16, HPV-18 and closely related types, can progress to high grade dysplasias and carcinomas in women and men, including cervical, vulva, penile and anal cancers. A significant fraction of the head and neck cancers are also caused by HPV-16. The viral oncogenes responsible for neoplastic conversion are E6 and E7 that disrupt the pathways controlled by the two major tumor suppressor genes, p53 and members of p RB family. Because HPV cannot be propagated in conventional submerged monolayer cell cultures, organotypic epithelial raft cultures that generate a stratified and differentiated epithelium have been used to study the viral life cycle. This article describes several systems to examine aspects of the viral productive phase, along with the advantages and limitations. Animal model systems of HPV carcinogenesis are also briefly described.