Bioinformatics for glycomics: status, methods, requirements and perspectives

The term 'glycomics' describes the scientific attempt to identify and study all the glycan molecules - the glycome - synthesised by an organism. The aim is to create a cell-by-cell catalogue of glycosyltransferase expression and detected glycan structures. The current status of databases and bioinformatics tools, which are still in their infancy, is reviewed. The structures of glycans as secondary gene products cannot be easily predicted from the DNA sequence. Glycan sequences cannot be described by a simple linear one-letter code as each pair of monosaccharides can be linked in several ways and branched structures can be formed. Few of the bioinformatics algorithms developed for genomics/proteomics can be directly adapted for glycomics. The development of algorithms, which allow a rapid, automatic interpretation of mass spectra to identify glycan structures is currently the most active field of research. The lack of generally accepted ways to normalise glycan structures and exchange glycan formats hampers an efficient cross-linking and the automatic exchange of distributed data. The upcoming glycomics should accept that unrestricted dissemination of scientific data accelerates scientific findings and initiates a number of new initiatives to explore the data.     

A coupled model of photosynthesis,stomatal conductance and transpiration for a rose leaf (Rosa hybrida L.)

The following three models were combined to predict simultaneously photosynthesis, stomatal conductance, transpiration and leaf temperature of a rose leaf: the biochemical model of photosynthesis of Farquhar, von Caemmerer and Berry (1980, Planta 149: 78-90), the stomatal conductance model of Ball, Woodrow and Berry (In: Biggens J, ed. Progress in photosynthesis research. The Netherlands: Martinus Nijhoff Publishers), and an energy balance model. The photosynthetic parameters: maximum carboxylation rate, potential rate of electron transport and rate of triose phosphate utilization, and their temperature dependence were determined using gas exchange data of fully expanded, young, sunlit leaves. The stomatal conductance model was calibrated independently. Prediction of net photosynthesis by the coupled model agreed well with the validation data, but the model tended to underestimate rates of stomatal conductance and transpiration. The coupled model developed in this study can be used to assist growers making environmental control decisions in glasshouse production.     

LOX-DB-- database on lipoxygenases

SUMMARY: Lipoxygenases are a family of enzymes involved in a variety of human diseases like inflammation, asthma, artherosclerosis and cancer. The lipoxygenases database (LOX-DB) aims to be a web accessible compendium of information in particular on the mammalian members of this multigene family. This resource includes molecular structures, reference data, tools for structural and computational analysis as well as links to related information maintained by others. The data can be retrieved by the use of various search options and analyzed applying publicly available visualization tools. AVAILABILITY: LOX-DB is available at http://www.dkfz-heidelberg.de/spec/lox-db/     

GLYCO-FRAGMENT: A web tool to support the interpretation of mass spectra of complex carbohydrates

Mass spectrometry is frequently used to analyze complex oligosaccharides and glycopeptides. The spectra of glycans can be complicated and difficult to interpret without reference data. Unfortunately, no libraries of suitably pure and homogeneous standards have so far been compiled. The web-based tool GLYCO-FRAGMENT allows the generation of all theoretically possible MS relevant fragments of oligosaccharides as defined using the extended IUPAC nomenclature. The main focus of GLYCO-FRAGMENT is to support the manual assignment of all peaks contained in mass spectra of complex carbohydrates. The service is available at http://www.dkfz.de/spec/projekte/fragments/.     

A conformational change in the adeno-associated virus type 2 capsid leads to the exposure of hidden VP1 N termini

The complex infection process of parvoviruses is not well understood so far. An important role has been attributed to a phospholipase A2 domain which is located within the unique N terminus of the capsid protein VP1. Based on the structural difference between adeno-associated virus type 2 wild-type capsids and capsids lacking VP1 or VP2, we show via electron cryomicroscopy that the N termini of VP1 and VP2 are involved in forming globules inside the capsids of empty and full particles. Upon limited heat shock, VP1 and possibly VP2 become exposed on the outsides of full but not empty capsids, which is correlated with the disappearance of the globules in the inner surfaces of the capsids. Using molecular modeling, we discuss the constraints on the release of the globularly organized VP1-unique N termini through the channels at the fivefold symmetry axes outside of the capsid.     

Molecular dynamics study of the proposed beta-hairpin form of the switch domain from HIV1 gp120 alone and complexed with an inhibitor of CD4 binding

The strong tendency of beta-hairpin peptides to aggregate can prevent their structural resolution. The polar form of the switch peptide (LAV 15mer) at the CD4-binding domain of HIV1 gp120 is such a peptide, and NMR investigations of its interaction with a class of CD4-binding inhibitors developed in this laboratory have been hindered. Detailed knowledge of the interaction is required for the development of more potent switch inhibitors, that act by disrupting the cooperative folding transition necessary for binding to the CD4 receptor. In carrying out molecular dynamics simulation of the free peptide under polar conditions, we found that the properties of the resulting structure agree closely with those observed by circular dichroism. The same conditions, used to model the peptide/ inhibitor complex, produced a stable bimolecular structure with specific interactions between the inhibitor and side chains on the peptide, (e.g., Trp12 and the LPCR tetrad), known to control the folding transition. These help explain existing data on the relative potency of inhibitor derivatives and provide a basis for improved inhibitor design.     

Normalization and calculation of lanthanide element concentrations in environmental samples

Summary A mathematical model for the prediction of lanthanide element concentrations in soil and plant samples is presented. A comparison between pre dicted and measured lanthanide values in soil and plant samples show, that the model produces good results for the elements in the soil samples and for most elements in plant material. The accuracy of prediction worsens with decreasing concentration of the heavier lanthanide elements. The mathematical model presented is not valid on other environmental samples like aerosols, because no data for these matrices are available yet to calibrate our normalized curves.     

Poor physical fitness is independently associated with mild cognitive impairment in elderly Koreans

The purpose of this study was to investigate the association between physical fitness and mild cognitive impairment (MCI) in elderly Koreans. This was a cross-sectional study that involved 134 men and 299 women aged 65 to 88 years. Six senior fitness tests were used as independent variables: 30 s chair stand for lower body strength, arm curl for upper body strength, chair-sit-and-reach for lower body flexibility, back scratch for upper body flexibility, 8-ft up-and-go for agility/dynamic balance, and 2-min walk for aerobic endurance. Global cognitive function was assessed using the Korean version of the Mini-Mental State Examination (MMSE). Potential covariates such as age, education levels, blood lipids, and insulin resistance (IR) markers were also assessed. Compared to individuals without MMSE-based MCI, individuals with MMSE-based MCI had poor physical fitness based on the senior fitness test (SFT). There were significant positive trends observed for education level (p=0.001) and MMSE score (p<0.001) across incremental levels of physical fitness in this study population. Individuals with moderate (OR=0.341, p=0.006) and high (OR=0.271, p=0.007) physical fitness based on a composite score of the SFT measures were less likely to have MMSE-based MCI than individuals with low physical fitness (referent, OR=1). The strength of the association between moderate (OR=0.377, p=0.038) or high (OR=0.282, p=0.050) physical fitness and MMSE-based MCI was somewhat attenuated but remained statistically significant even after adjustment for the measured compounding factors. We found that poor physical fitness was independently associated with MMSE-based MCI in elderly Koreans.     

Evolution of anaerobic ciliates from the gastrointestinal tract: phylogenetic analysis of the ribosomal repeat from Nyctotherus ovalis and its relatives

The 18S and 5.8S rDNA genes and the internal transcribed spacers ITS-1 and ITS-2 of ciliates living in the hindgut of frogs, millipedes, and cockroaches were analyzed in order to study the evolution of intestinal protists. All ciliates studied here belong to the genus Nycrotherus. Phylogenetic analysis revealed that these ciliates from a monophyletic group that includes the distantly related anaerobic free-living heterotrichous ciliates Metopus palaeformis and Metopus contortus. The intestinal ciliates from the different vertebrate and invertebrate hosts are clearly divergent at the level of their rDNA repeats. This argues for the antiquity of the associations and a predominantly vertical transmission. This mode of transmission seems to be controlled primarily by the behavior of the host. The different degrees of divergence between ciliates living in different strains of one and the same cockroach species most likely reflect the different geographical origins of the hosts. In addition, host switches must have occurred during the evolution of cockroaches, since identical ciliates were found only in distantly related hosts. These phenomena prevent the reconstruction of potential cospeciation events.