Plant cell walls are enfeebled when attempting to preserve native lignin configuration with poly-p-hydroxycinnamaldehydes: evolutionary implications

The lignin deficient double mutant of cinnamyl alcohol dehydrogenase (CAD, cad-4, cad-5 or cad-c, cad-d) in Arabidopsis thaliana [Sibout, R., Eudes, A., Mouille, G., Pollet, B., Lapierre, C., Jouanin, L., Séguin, A., 2005. Cinnamyl alcohol dehydrogenase-C and -D are the primary genes involved in lignin biosynthesis in the floral stem of Arabidopsis. Plant Cell 17, 2059-2076], was comprehensively examined for effects on disruption of native lignin macromolecular configuration; the two genes encode the catalytically most active CAD's for monolignol/lignin formation [Kim, S.-J., Kim, M.-R., Bedgar, D.L., Moinuddin, S.G.A., Cardenas, C.L., Davin, L.B., Kang, C., Lewis, N.G., 2004. Functional reclassification of the putative cinnamyl alcohol dehydrogenase multigene family in Arabidopsis. Proc. Natl. Acad. Sci., USA 101, 1455-1460]. The inflorescence stems of the double mutant presented a prostrate phenotype with dynamic modulus properties greatly reduced relative to that of the wild type (WT) line due to severe reductions in macromolecular lignin content. Interestingly, initially the overall pattern of phenolic deposition in the mutant was apparently very similar to WT, indicative of comparable assembly processes attempting to be duplicated. However, shortly into the stage involving (monomer cleavable) 8-O-4' linkage formation, deposition was aborted. At this final stage, the double mutant had retained a very limited ability to biosynthesize monolignols as evidenced by cleavage and release of ca. 4% of the monolignol-derived moieties relative to the lignin of the WT line. In addition, while small amounts of cleavable p-hydroxycinnamaldehyde-derived moieties were released, the overall frequency of (monomer cleavable) 8-O-4' inter-unit linkages closely approximated that of WT for the equivalent level of lignin deposition, in spite of the differences in monomer composition. Additionally, 8-5' linked inter-unit structures were clearly evident, albeit as fully aromatized phenylcoumaran-like substructures. The data are interpreted as a small amount of p-hydroxycinnamaldehydes being utilized in highly restricted attempts to preserve native lignin configuration, i.e. through very limited monomer degeneracy during template polymerization which would otherwise afford lignins proper in the cell wall from their precursor monolignols. The defects introduced (e.g. in the vascular integrity) provide important insight as to why p-hydroxycinnamaldehydes never evolved as lignin precursors in the 350,000 or so extant vascular plant species. It is yet unknown at present, however, as to what levels of lignin reduction can be attained in order to maintain the requisite properties for successful agronomic/forestry cultivation. Nor is it known to what extent, if any, such deleterious modulations potentially compromise plant defenses. Finally, prior to investigating lignin primary structure proper, it is essential to initially define the fundamental characteristics of the biopolymer(s) being formed, such as inter-unit frequency and lignin content, in order to design approaches to determine overall sequences of linkages.     

Mobility of individual roach <Emphasis Type="Italic">Rutilus rutilus</Emphasis> (L.) in three weir-fragmented Belgian rivers

Adult roach Rutilus rutilus (L.) (N = 24; 19.9–36.1 cm FL) from three highly fragmented Belgian rivers were tagged with surgically implanted radio transmitters. Their seasonal movements were observed from March to August 2004 (circum reproduction period) in river stretches delimited by two physical barriers. In the three rivers, roach displayed similar patterns of movements which were mainly influenced by the date of observation (movements increased in late April–May) and water temperature (travel distances were more important when water temperature ranged between 10°C and 14°C). Roach sometimes cleared physical obstacles. The mean distances travelled in each river were relatively short (max. 2.5 km) and mainly influenced by the length of the study reach, which was delimited by physical barriers.     

Impact of vCJD on blood supply.

Variant Creutzfeldt-Jakob disease (vCJD) is an at present inevitably lethal neurodegenerative disease which can only be diagnosed definitely post mortem. The majority of the approximately 200 victims to date have resided in the UK where most contaminated beef materials entered the food chain. Three cases in the UK demonstrated that vCJD can be transmitted by blood transfusion. Since BSE and vCJD have spread to several countries outside the UK, it appears advisable that specific risk assessments be carried out in different countries and geographic areas. This review explains the approach adopted by Germany in assessing the risk and considering precautionary measures. A fundamental premise is that the feeding chain of cattle and the food chain have been successfully and permanently cleared from contaminated material. This raises the question of whether transmissions via blood transfusions could have the potential to perpetuate vCJD in mankind. A model calculation based on actual population data showed, however, that this would not be the case. Moreover, an exclusion of transfusion recipients from blood donation would add very little to the safety of blood transfusions, but would have a considerable impact on blood supply. Therefore, an exclusion of transfusion recipients was not recommended in Germany.     

Hormones of youth?

Ageing is doubtless complicated, lifelong process regarding many body systems, including endocrine system. Human hormonal system changes with age. Although these changes concern secretion of many hormones, they are not unidirectional, there are hormones secretion of which is diminished, whereas secretion of the others is augmented or not changed with age. A possible role of hormones which are often termed "hormones of youth"(growth hormone, melatonin, and dehydroepiandrosterone) in the ageing process is discussed in the present article. Although some experimental and clinical data indicate that these hormones may play some role in the human ageing process, it appears from presented data that we are still far away from conclusion that, indeed, one (or more) of the discussed hormones could be considered as "hormone of youth", which may slow down ageing process. However, some symptoms of the quality of life improvement following administration of dehydroepiandrosterone, melatonin, and growth hormone may suggest that they may promote so called "successful aging".     

Assessment of prolactin secretion in children: a profile of circadian prolactin secretion and the principles for interpreting it

INTRODUCTION: Prolactin (Prl) is secreted in a circadian pattern, although no method of interpreting it has yet been established. The aim of the study was to assess Prl secretion in children on the basis of the Prl circadian profile and to establish principles for the interpretation of the results obtained by this method. MATERIAL AND METHODS: The analysis comprised 41 healthy short children (25 boys); aged 5.2-16.3 years, in whom hormonal disorders and chronic diseases had been excluded. The children were divided into prepubertal or pubertal subgroups. Serum Prl concentrations were measured every 3 hours for 24 hours. To assess the rhythm the parameters of macroscopic analysis were calculated and receiver operating characteristic (ROC) analysis was performed. The group for comparison consisted of 30 children aged 8.9-17.2 years with hyperprolactinaemia. RESULTS: In each subgroup significantly higher Prl concentrations were observed at night than by day. No statistical differences were noticed between the groups regarding Prl concentrations at particular time points or parameter values during circadian Prl rhythm evaluation. In the group analysed weak correlations were found between age and Prl peak and trough levels. On the basis of ROC analysis criteria for the existence of normal circadian Prl rhythm in children were established. CONCLUSIONS: 1. The presence of normal circadian Prl rhythm is observed if at least one of the following three criteria is fulfilled: amplitude >1.8779; X(n)/X(d) ratio >1.685; regression index <-0.4107. 2. No interpretation in relation to sex, age and stage of puberty is necessary for the circadian prolactin secretion rhythm in children.     

Differential Gene Expression in a Marine Sponge in Relation to Its Symbiotic State

The molecular mechanisms involved in the establishment and maintenance of sponge photosymbiosis, and in particular the association with cyanobacteria, are unknown. In the present study we analyzed gene expression in a common Mediterranean sponge (Petrosia ficiformis) in relation to its symbiotic (with cyanobacteria) or aposymbiotic status. A screening approach was applied to identify genes expressed differentially in symbiotic specimens growing in the light and aposymbiotic specimens growing in a dark cave at a short distance from the illuminated specimens. Out of the various differentially expressed sequences, we isolated two novel genes (here named PfSym1 and PfSym2) that were up-regulated when cyanobacterial symbionts were harbored inside the sponge cells. The sequence of one of these genes (PfSym2) was found to contain a conserved domain: the scavenger receptor cysteine rich (SRCR) domain. This is the first report on the expression of sponge genes in relation to symbiosis and, according to the presence of an SRCR domain, we suggest possible functions for one of the genes found in the sponge-cyanobacteria symbiosis.