Estrogen receptor ligands. Part 6: Synthesis and binding affinity of dihydrobenzodithiins

Dihydrobenzodithiin compounds (1-6) were prepared to explore the expansion of the dihydrobenzoxathiin lead compounds I-III as SERAMs (Selective Estrogen Receptor Alpha Modulators). The dihydrobenzodithiin compounds generally maintained a high degree of selectivity for ERalpha over ERbeta, however, they lacked the in vivo antagonism/agonism activity exhibited by the lead class in an immature rat uterine growth model.     

Over-expression of hydroxynitrile lyase in transgenic cassava roots accelerates cyanogenesis and food detoxification

Cassava (Manihot esculenta, Crantz) roots are the primary source of calories for more than 500 million people, the majority of whom live in the developing countries of Africa. Cassava leaves and roots contain potentially toxic levels of cyanogenic glycosides. Consumption of residual cyanogens (linamarin or acetone cyanohydrin) in incompletely processed cassava roots can cause cyanide poisoning. Hydroxynitrile lyase (HNL), which catalyses the conversion of acetone cyanohydrin to cyanide, is expressed predominantly in the cell walls and laticifers of leaves. In contrast, roots have very low levels of HNL expression. We have over-expressed HNL in transgenic cassava plants under the control of a double 35S CaMV promoter. We show that HNL activity increased more than twofold in leaves and 13-fold in roots of transgenic plants relative to wild-type plants. Elevated HNL levels were correlated with substantially reduced acetone cyanohydrin levels and increased cyanide volatilization in processed or homogenized roots. Unlike acyanogenic cassava, transgenic plants over-expressing HNL in roots retain the herbivore deterrence of cyanogens while providing a safer food product.     

A comparison of adductor pollicis fatigue in older men and women

Sex differences in fatigue resistance of the adductor pollicis (AP) muscle were studied in 24 older adults who were divided into three groups: 12 older men (69.8 +/- 4.60 years), 6 older women not on hormone replacement therapy (HRT) (70.2 +/- 4.02 years), and 6 older women on HRT (68.7 +/- 6.47 years). Fatigue in the AP muscle was induced using an intermittent (5 s contraction, 5 s rest) submaximal voluntary contraction (50% of maximal voluntary contraction (MVC)) protocol, which was continued until exhaustion (i.e., when subjects could either no longer maintain a 5-s contraction at 50% MVC or when the MVC was deemed to be lower than the target force). There was no effect of HRT on MVC or time to fatigue (TTF); therefore, the older women were pooled as one subject group. At baseline, men were stronger than women for MVC (75.9 +/- 18.8 N in men vs. 56.8 +/- 10.0 N in women; P < 0.05) and evoked twitch force (7.3 +/- 1.7 N in men vs. 5.2 +/- 0.8 N in women; P < 0.05). There was no difference in TTF between men and women (14.77 +/- 7.06 min in men vs. 11.53 +/- 4.91 min in women; P > 0.20), nor was there a significant relationship between baseline muscle force and TTF (r = 0.14). There was also no difference in the pattern of fatigue and recovery between the men and women. These results suggest that there is no difference in endurance or fatigue characteristics of the AP muscle in men and women over the age of 65 years, and that baseline muscle force does not predict fatigue resistance in this muscle.     

The Escherichia coli twin-arginine translocase: conserved residues of TatA and TatB family components involved in protein transport

The Escherichia coli Tat system serves to export folded proteins harbouring an N-terminal twin-arginine signal peptide across the cytoplasmic membrane. In this report we have studied the functions of conserved residues within the structurally related TatA and TatB proteins. Our results demonstrate that there are two regions within each protein of high sequence conservation that are critical for efficient Tat translocase function. The first region is the interdomain hinge between the transmembrane and the amphipathic alpha-helices of TatA and TatB proteins. The second region is within the amphipathic helices of TatA and TatB. In particular an invariant phenylalanine residue within TatA proteins is essential for activity, whereas a string of glutamic acid residues on the same face of the amphipathic helix of TatB is important for function.     

The role of mucins in host-parasite interactions: Part II - helminth parasites

Some parasites express mucin-like molecules. These have possible roles in attachment and invasion of host cells and in the avoidance of host immune processes. Enzymes of parasite origin might also facilitate infection, either by degrading host mucus barriers or by generating binding sites on host cells. Host mucins have roles in preventing parasite establishment or in parasite expulsion. They, in turn, might be exploited by parasites, either as sources of fuel or binding sites, or as host-finding targets. Here, we describe the biochemical properties of mucins and mucin-like molecules in relation to interactions (established and putative) between helminth parasites and their hosts.     

Modification of an automated liquid-handling system for reagent-jet, nanoliter-level dispensing

Reducing the scale of biochemical reactions is becoming commonplace. Examples include the screening of large libraries of chemical compounds or gene sequences. These applications demand the ability to transfer sub-microliter volumes of fluid. To this end, we have modified a Hamilton MICROLAB 2200 with high-speed solenoids and a liquid pressurization system to modulate volume delivery down to the nanoliter level. Additional modifications include the use of sapphire-tipped dispensing nozzles and a high-resolution substage to assist in the construction of DNA microarrays. Techniques for characterizing the dispensed volume are presented.