Biomarkers for cardiovascular disease: challenges and future directions

The accurate diagnosis and prevention of cardiovascular disease (CVD) is an important public health goal. Although clinical characteristics such as age and gender are well-established risk factors for CVD, such features are not sufficient to identify all patients at risk. Cardiovascular biomarkers have the potential to augment clinical risk stratification by aiding in screening, diagnosis and assessment of prognosis. However, most current biomarkers have only modest predictive value, and there is a need to identify additional biomarkers from new biological pathways. The availability of platforms for profiling DNA, RNA, proteins and metabolites in clinical specimens has facilitated the 'unbiased' search for new biomarkers, which can now be tested in a clinical setting. This review highlights recent developments in the field of cardiovascular biomarkers and describes the use of new technologies for the identification of biomarkers.     

The auxin influx carrier LAX3 promotes lateral root emergence

Lateral roots originate deep within the parental root from a small number of founder cells at the periphery of vascular tissues and must emerge through intervening layers of tissues. We describe how the hormone auxin, which originates from the developing lateral root, acts as a local inductive signal which re-programmes adjacent cells. Auxin induces the expression of a previously uncharacterized auxin influx carrier LAX3 in cortical and epidermal cells directly overlaying new primordia. Increased LAX3 activity reinforces the auxin-dependent induction of a selection of cell-wall-remodelling enzymes, which are likely to promote cell separation in advance of developing lateral root primordia.     

Identification of a BMP7 homolog in zebrafish expressed in developing organ systems

The Bone morphogenetic proteins (BMPs) act in many key regulatory processes during development, including dorsoventral axis specification and organ development and are part of a conserved signal pathway. Specifically, BMP7 is a vital signaling molecule for normal development in the mammalian system. The zebrafish mutant snailhouse (snh) was originally isolated as being strongly dorsalized and the mutation was determined to lie within the bmp7 gene. We report here the cloning and expression of a second bmp7 homolog, which we term bmp7b. Sequence alignments show that bmp7b is more closely related to human, mouse and non-mammalian BMP7 than is snh. We further show that bmp7b is strongly expressed in developing organ systems such as the eyes, the ears, the pronephric kidney and the gastrointestinal system.     

MRMer, an interactive open source and cross-platform system for data extraction and visualization of multiple reaction monitoring experiments

Multiple reaction monitoring (MRM) mass spectrometry identifies and quantifies specific peptides in a complex mixture with very high sensitivity and speed and thus has promise for the high throughput screening of clinical samples for candidate biomarkers. We have developed an interactive software platform, called MRMer, for managing highly complex MRM-MS experiments, including quantitative analyses using heavy/light isotopic peptide pairs. MRMer parses and extracts information from MS files encoded in the platform-independent mzXML data format. It extracts and infers precursor-product ion transition pairings, computes integrated ion intensities, and permits rapid visual curation for analyses exceeding 1000 precursor-product pairs. Results can be easily output for quantitative comparison of consecutive runs. Additionally MRMer incorporates features that permit the quantitative analysis experiments including heavy and light isotopic peptide pairs. MRMer is open source and provided under the Apache 2.0 license.     

A gamma-herpesvirus glycoprotein complex manipulates actin to promote viral spread

Viruses lack self-propulsion. To move in multi-cellular hosts they must therefore manipulate infected cells. Herpesviruses provide an archetype for many aspects of host manipulation, but only for alpha-herpesviruses in is there much information about they move. Other herpesviruses are not necessarily the same. Here we show that Murine gamma-herpesvirus-68 (MHV-68) induces the outgrowth of long, branched plasma membrane fronds to create an intercellular network for virion traffic. The fronds were actin-based and RhoA-dependent. Time-lapse imaging showed that the infected cell surface became highly motile and that virions moved on the fronds. This plasma membrane remodelling was driven by the cytoplasmic tail of gp48, a MHV-68 glycoprotein previously implicated in intercellular viral spread. The MHV-68 ORF58 was also required, but its role was simply transporting gp48 to the plasma membrane, since a gp48 mutant exported without ORF58 did not require ORF58 to form membrane fronds either. Together, gp48/ORF58 were sufficient to induce fronds in transfected cells, as were the homologous BDLF2/BMRF2 of Epstein-Barr virus. Gp48/ORF58 therefore represents a conserved module by which gamma-herpesviruses rearrange cellular actin to increase intercellular contacts and thereby promote their spread.     

Electronic structure and bonding of the dinuclear metal M<Subscript>2</Subscript>(CO)<Subscript>10</Subscript> decacarbonyls: applications of natural orbitals for chemical valence

The nature of the chemical metal–metal bond in M₂(CO)₁₀ (M?=?Mn, Re, Tc) dinuclear decacarbonyls complexes was investigated for the first time using the natural orbital chemical valence (NOCV) approach combined with the extended transition state (ETS) for energy decomposition analysis (EDA). The optimized geometries carried out at different levels of theory BP86, BLYP, BLYPD and BP86D, showed that the latter method, i.e., BP86D, led to the best agreement with X-ray experimental measurements. The BP86D/TZP results revealed that the computed covalent contribution to the metal–metal bond are 60.5%, 54.1% and 52.0% for Mn–Mn, Re–Re and Tc–Tc, respectively. The computed total interaction energies resulting from attractive terms (ΔE _orb and ΔE _eles), correspond well to experimental predictions, based on bond lengths and energy interaction analysis for the studied complexes.     

Pyramid Screening: Combining Three Genetic Screens into One Efficient Screen for Shoot Regeneration Mutants in Arabidopsis thaliana

Gain-of-function genetic mutants are typically found by creating a non-permissive condition and screening for plants that overcome the stress. Separate genetic screens are conducted for each condition, a potentially time-consuming effort. In severed Arabidopsis thaliana leaves, high light, suboptimal hormone exposure and old age were each independently found to reduce frequency of shoot regeneration. Rather than conducting three separate mutant screens to dissect these three pathways, a laborious process, we hypothesized that we could undertake a single economical screen to retrieve mutations specific for each trait as well as cross-talk alleles between pathways. Instead of creating non-permissive conditions for each of our three traits of interest, we combined the three suboptimal stress conditions such that only when combined was shoot regeneration abolished. No one stress was primarily responsible for loss of our trait, thus ensuring that we could recover mutant alleles in any of the three pathways of interest. Screening of 18,000 mutagenized plants resulted in 12 SHOOTING UP (stu) mutants. Secondary screening revealed that we had recovered alleles that were both specific for a pathway (light, hormones or age) and which acted through multiple pathways. Our approach, which we refer to as pyramid screening, represents an economical method for mutant screening of multiple pathways in parallel (three screens in one) and has the potential to recover alleles that cross-talk between multiple pathways that underlie a complex trait such as organ regeneration. Pyramid screening should be widely applicable across species.