Synthesis and biological evaluation of (-)-laulimalide analogues

Analogues of the marine natural product (-)-laulimalide were prepared by total synthesis and evaluated in vitro for anticancer activity.     

Reduced cardiac output is associated with decreased mitochondrial efficiency in the non-ischemic ventricular wall of the acute myocardial-infarcted dog

Cardiogenic shock is the leading cause of death among patients hospitalized with acute myocardial infarction (MI).Understanding the mechanisms for acute pump failure is therefore important.The aim of this study is to examine in anacute MI dog model whether mitochondrial bio-energetic function within non-ischemic wall regions are associated withpump failure.Anterior MI was produced in dogs via ligation of left anterior descending (LAD) coronary artery,thatresulted in an infract size of about 30% of the left ventricular wall.Measurements of hemodynamic status,mitochondrialfunction,free radical production and mitochondrial uncoupling protein 3 (UCP3) expression were determined over 24h period.Hemodynamic measurements revealed a>50% reduction in cardiac output at 24 h post infarction when com-pared to baseline.Biopsy samples were obtained from the posterior non-ischemic wall during acute infarction.ADP/Oratios for isolated mitochondria from non-ischemic myocardium at 6 h and 24 h were decreased when compared to theADP/O ratios within the same samples with and without palmitic acid (PA).GTP inhibition of (PA)-stimulated state 4respiration in isolated mitochondria from the non-ischemic wall increased by 7% and 33% at 6 h and 24 h post-infarctionrespectively when compared to sham and pre-infarction samples.This would suggest that the mitochondria are uncoupledand this is supported by an associated increase in UCP3 expression observed on western blots from these same biopsysamples.Blood samples from the coronary sinus measured by electron paramagnetic resonance (EPR) methods showedan increase in reactive oxygen species (ROS) over baseline at 6 h and 24 h post-infarction.In conclusion,mitochondrialbio-energetic ADP/O ratios as a result of acute infarction are abnormal within the non-ischemic wall.Mitochondria ap-pear to be energetically uncoupled and this is associated with declining pump function.Free radical production may beassociated with the induction of uncoupling proteins in the mitochondria.     

Targeting of proteins of the striatin family to dendritic spines: role of the coiled-coil domain

Striatin, SG2NA and zinedin, the three mammalian members of the striatin family are multimodular WD-repeat, calmodulin and calveolin-binding proteins. These scaffolding proteins, involved in both signaling and trafficking, are highly expressed in neurons. Using ultrastructural immunolabeling, we showed that, in Purkinje cells and hippocampal neurons, SG2NA is confined to the somatodendritic compartment with the highest density in dendritic spines. In cultured hippocampal neurons, SG2NA is also highly concentrated in dendritic spines. By expressing truncated forms of HA-tagged SG2NAbeta, we demonstrated that the coiled-coil domain plays an essential role in the targeting of SG2NA within spines. Furthermore, co-immunoprecipitation experiments indicate that this coiled-coil domain is also crucial for the homo- and hetero-oligomerization of these proteins. Thus, oligomerization of the striatin family proteins is probably an obligatory step for their routing to the dendritic spines, and hetero-oligomerization explains why all these proteins are often co-expressed in the neurons of the rat brain and spinal cord.     

Mutations in the SPARC-related modular calcium-binding protein 1 gene, SMOC1, cause waardenburg anophthalmia syndrome

Waardenburg anophthalmia syndrome, also known as microphthalmia with limb anomalies, ophthalmoacromelic syndrome, and anophthalmia-syndactyly, is a rare autosomal-recessive developmental disorder that has been mapped to 10p11.23. Here we show that this disease is heterogeneous by reporting on a consanguineous family, not linked to the 10p11.23 locus, whose two affected children have a homozygous mutation in SMOC1. Knockdown experiments of the zebrafish smoc1 revealed that smoc1 is important in eye development and that it is expressed in many organs, including brain and somites.     

Core and intact polar glycerol dibiphytanyl glycerol tetraether lipids of ammonia-oxidizing archaea enriched from marine and estuarine sediments

Glycerol dibiphytanyl glycerol tetraether (GDGT)-based intact membrane lipids are increasingly being used as complements to conventional molecular methods in ecological studies of ammonia-oxidizing archaea (AOA) in the marine environment. However, the few studies that have been done on the detailed lipid structures synthesized by AOA in (enrichment) culture are based on species enriched from nonmarine environments, i.e., a hot spring, an aquarium filter, and a sponge. Here we have analyzed core and intact polar lipid (IPL)-GDGTs synthesized by three newly available AOA enriched directly from marine sediments taken from the San Francisco Bay estuary ("Candidatus Nitrosoarchaeum limnia"), and coastal marine sediments from Svalbard, Norway, and South Korea. Like previously screened AOA, the sedimentary AOA all synthesize crenarchaeol (a GDGT containing a cyclohexane moiety and four cyclopentane moieties) as a major core GDGT, thereby supporting the hypothesis that crenarchaeol is a biomarker lipid for AOA. The IPL headgroups synthesized by sedimentary AOA comprised mainly monohexose, dihexose, phosphohexose, and hexose-phosphohexose moieties. The hexose-phosphohexose headgroup bound to crenarchaeol was common to all enrichments and, in fact, the only IPL common to every AOA enrichment analyzed to date. This apparent specificity, in combination with its inferred lability, suggests that it may be the most suitable biomarker lipid to trace living AOA. GDGTs bound to headgroups with a mass of 180 Da of unknown structure appear to be specific to the marine group I.1a AOA: they were synthesized by all three sedimentary AOA and "Candidatus Nitrosopumilus maritimus"; however, they were absent in the group I.1b AOA "Candidatus Nitrososphaera gargensis."     

Insulin-like growth factor I and its binding proteins: a study of the binding interface using B-domain analogues

The biological activity of the insulin-like growth factors (IGF-I and IGF-II) is regulated by six IGF binding proteins (IGFBPs 1-6). To examine the surface of IGF-I that associates with the IGFBPs, we created a series of six IGF-I analogues, [His(4)]-, [Gln(9)]-, [Lys(9)]-, [Ser(16)]-, [Gln(9),Ser(16)]-, and [Lys(9),Ser(16)]IGF-I, that contained substitutions for residues Thr(4), Glu(9), or Phe(16). Substitution of Ser for Phe(16) did not affect secondary structure but significantly decreased the affinity for all IGFBPs by between 14-fold and >330-fold, indicating that Phe(16) is functionally important for IGFBP association. While His(4) or Gln(9) substitutions had little effect on IGFBP affinity, changing the negative charge of Glu(9) to a positive Lys(9) selectively decreased the affinities of IGFBP-2 and -6 by 140- and 30-fold, respectively. Furthermore, the effects of mutations to both residues 9 and 16 appear to be additive. The analogues are biologically active in rat L6 myoblasts and they retain native structure as assessed by their far-UV circular dichroism (CD) profiles. We propose that Phe(16) and adjacent hydrophobic residues (Leu(5) and Leu(54)) form a functional binding pocket for IGFBP association.     

LhcaR1 of the red alga Porphyridium cruentum encodes a polypeptide of the LHCI complex with seven potential chlorophyll a-binding residues that are conserved in most LHCs

The accessory light-harvesting polypeptides associated with photosystem I (LHCI) in Porphyridium cruentum bind chlorophyll a, zeaxanthin and -carotene. A cDNA library of P. cruentum was screened with an antiserum specific to the LHCI polypeptides, and an 0.9 kb fragment was identified as coding for an LHCI polypeptide. This cDNA, which we named LhcaR1, has an open reading frame encoding 222 amino acid residues including a putative transit peptide of 28 amino acids. Hydropathy analysis suggests that there are three transmembrane helices in the mature polypeptide. Each of the amino acid residues that bind chlorophyll (six residues) and serve in stabilizing the helices in higher-plant LHCs are conserved in helices 1 and 3 of P. cruentum LhcaR1. The N-terminal flanking regions of these two helices also show high sequence conservation with other LHCs. Helix 2 contains a seventh putative chlorophyll-binding site, but resembles helix 2 of higher-plant LHCs to a lesser degree. A sequence motif of 11 residues found near the N-terminus and in each of the three helices suggests the possibility that the red algal LhcaR1 derives from a gene duplication. Polypeptides of the expected molecular weight in six other red algae (Achrochaetium, Bangia, Callithamnion, Cyanidium, Polysiphonia, Spermothamnion) were recognized by the antiserum to P. cruentum LHCI, indicating a wide distribution of LHCI in rhodophytes.     

Refining the genetic map for the region flanking the X-linked hypophosphataemic rickets locus (Xp22.1–22.2)

An analysis of five of the most common cystic fibrosis (CF) mutations worldwide (F-508, R-553X, G-551D, N-1303K and G-542X) was performed in 36 Chilean patients. Polymerase chain reaction (PCR) amplification of the DNA followed by allele specific restriction enzyme analysis was used for detection. The overall frequencies of the mutations in the chromosomes analyzed were 29.2% for F-508 and 4.2% for R-553X (n=72). The G-542X, G-551D and N-1303 K mutations were absent in the Chilean sample. Our data suggest however that F-508 is not the most common CF mutation in Chilean patients. F-508 and R-553X account for only 33.4% of the alleles; 66.6% of them do not respond to the probes used and still remain uncharacterized.     

Effect of flower traits and hosts on the abundance of parasitoids in perennial multiple species wildflower strips sown within oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis>) crops

Reducing the use of insecticides is an important issue for agriculture today. Sowing wildflower strips along field margins or within crops represents a promising tool to support natural enemy populations in agricultural landscapes and, thus, enhance conservation biological control. However, it is important to sow appropriate flower species that attract natural enemies efficiently. The presence of prey and hosts may also guide natural enemies to wildflower strips, potentially preventing them from migrating into adjacent crops. Here, we assessed how seven flower traits, along with the abundance of pollen beetles (Meligethes spp., Coleoptera: Nitidulidae) and true weevils (Ceutorhynchus spp., Coleoptera: Curculionidae), affect the density of parasitoids of these two coleopterans in wildflower strips sown in an oilseed rape field in Gembloux (Belgium). Only flower traits, not host (i.e. pollen beetles and true weevils) abundance, significantly affected the density of parasitoids. Flower colour, ultraviolet reflectance and nectar availability were the main drivers affecting parasitoids. These results demonstrate how parasitoids of oilseed rape pests react to flower cues under field conditions. Similar analyses on the pests and natural enemies of other crops are expected to help to develop perennial flower mixtures able to enhance biological control throughout a rotation system.