Synthesis and evaluation of efavirenz (Sustiva) analogues as HIV-1 reverse transcriptase inhibitors: replacement of the cyclopropylacetylene side chain

Two series of efavirenz analogues have been developed: one in which the cyclopropane ring has been replaced by small heterocycles and another in which the entire acetylenic side chain has been replaced by alkyloxy groups. Several members of both series show equivalent potency to efavirenz against both wild-type virus and the key K103N mutant.     

Mammalian sperm molecules that are potentially important in interaction with female genital tract and egg vestments

Fertilisation is a highly programmed process by which two radically different cells, sperm and egg, unite to form a zygote, a cell with somatic chromosome numbers. Development of the zygote begins immediately after sperm and egg haploid pronuclei come together, pooling their chromosomes to form a single diploid nucleus with the parental genes. Mammalian fertilisation is the net result of a complex set of molecular events which allow the capacitated spermatozoa to recognise and bind to the egg's extracellular coat, the zona pellucida (ZP), undergo the acrosome reaction, and fuse with the egg plasma membrane. Sperm-zona (egg) interaction leading to fertilisation is a species-specific carbohydrate-mediated event which depends on glycan-recognising proteins (glycosyltransferases/glycosidases/lectin-like molecules) on sperm plasma membrane (receptors) and their complementary glycan units (ligands) on ZP. The receptor-ligand interaction event initiates a signal transduction pathway resulting in the exocytosis of acrosomal contents. The hydrolytic action of the sperm glycohydrolases and proteases released at the site of sperm-egg interaction, along with the enhanced thrust generated by the hyperactivated beat pattern of the bound spermatozoon, are important factors regulating the penetration of egg investments. This review focuses on sperm molecules believed to be important for the interaction with the female genital tract, passage through cumulus oophorus and attachment to ZP, induction of the acrosome reaction, secondary binding events, and passage through the ZP. An understanding of the expression and modifications of molecules thought to be important in multiple events leading to fertilisation will allow new strategies to block these modifications and alter sperm function.     

ELF3 modulates resetting of the circadian clock in Arabidopsis

The Arabidopsis early flowering 3 (elf3) mutation causes arrhythmic circadian output in continuous light, but there is some evidence of clock function in darkness. Here, we show conclusively that normal circadian function occurs with no alteration of period length in elf3 mutants in dark conditions and that the light-dependent arrhythmia observed in elf3 mutants is pleiotropic on multiple outputs normally expressed at different times of day. Plants overexpressing ELF3 have an increased period length in both constant blue and red light; furthermore, etiolated ELF3-overexpressing seedlings exhibit a decreased acute CAB2 response after a red light pulse, whereas the null mutant is hypersensitive to acute induction. This finding suggests that ELF3 negatively regulates light input to both the clock and its outputs. To determine whether ELF3's action is phase dependent, we examined clock resetting by using light pulses and constructed phase response curves. Absence of ELF3 activity causes a significant alteration of the phase response curve during the subjective night, and constitutive overexpression of ELF3 results in decreased sensitivity to the resetting stimulus, suggesting that ELF3 antagonizes light input to the clock during the night. The phase of ELF3 function correlates with its peak expression levels in the subjective night. ELF3 action, therefore, represents a mechanism by which the oscillator modulates light resetting.     

The Sda1 protein is required for passage through start

We have used affinity chromatography to identify proteins that interact with Nap1, a protein previously shown to play a role in mitosis. Our studies demonstrate that a highly conserved protein called Sda1 binds to Nap1 both in vitro and in vivo. Loss of Sda1 function causes cells to arrest uniformly as unbudded cells that do not increase significantly in size. Cells arrested by loss of Sda1 function have a 1N DNA content, fail to produce the G1 cyclin Cln2, and remain responsive to mating pheromone, indicating that they arrest in G1 before Start. Expression of CLN2 from a heterologous promoter in temperature-sensitive sda1 cells induces bud emergence and polarization of the actin cytoskeleton, but does not induce cell division, indicating that the sda1 cell cycle arrest phenotype is not due simply to a failure to produce the G1 cyclins. The Sda1 protein is absent from cells arrested in G0 and is expressed before Start when cells reenter the cell cycle, further suggesting that Sda1 functions before Start. Taken together, these findings reveal that Sda1 plays a critical role in G1 events. In addition, these findings suggest that Nap1 is likely to function during G1. Consistent with this, we have found that Nap1 is required for viability in cells lacking the redundant G1 cyclins Cln1 and Cln2. In contrast to a previous study, we have found no evidence that Sda1 is required for the assembly or function of the actin cytoskeleton. Further characterization of Sda1 is likely to provide important clues to the poorly understood mechanisms that control passage through G1.     

Sequence alignment of 18S ribosomal RNA and the basal relationships of Adephagan beetles: evidence for monophyly of aquatic families and the placement of Trachypachidae

Current hypotheses regarding family relationships in the suborder Adephaga (Coleoptera) are conflicting. Here we report full-length 18S ribosomal RNA sequences of 39 adephagans and 13 outgroup taxa. Data analysis focused on the impact of sequence alignment on tree topology, using two principally different approaches. Tree alignments, which seek to minimize indels and substitutions on the tree in a single step, as implemented in an approximate procedure by the computer program POY, were contrasted with a more traditional procedure based on alignments followed by phylogenetic inference based on parsimony, likelihood, and distance analyses. Despite substantial differences between the procedures, phylogenetic conclusions regarding basal relationships within Adephaga and relationships between the four suborders of Coleoptera were broadly similar. The analysis weakly supports monophyly of Adephaga, with Polyphaga usually as its sister, and the two small suborders Myxophaga and Archostemata basal to them. In some analyses, however, Polyphaga was reconstructed as having arisen from within Hydradephaga. Adephaga generally split into two monophyletic groups, corresponding to the terrestrial Geadephaga and the aquatic Hydradephaga, as initially proposed by Crowson in 1955, consistent with a single colonization of the aquatic environment by adephagan ancestors and contradicting the recent proposition of three independent invasions. A monophyletic Hydradephaga is consistently, though not strongly, supported under most analyses, and a parametric bootstrapping test significantly rejects an hypothesis of nonmonophyly. The enigmatic Trachypachidae, which exhibit many similarities to aquatic forms but whose species are entirely terrestrial, were usually recovered as a basal lineage within Geadephaga. Strong evidence opposes the view that terrestrial trachypachids are related to the dytiscoid water beetles.     

Compound heterozygosity at the FMR1 gene

Individuals affected with Fragile X syndrome are usually characterized at the DNA level by the presence of at least 200 CGG repeats in the 5' untranslated region of the FMR1 gene; this number of repeats is defined as a full mutation. Repeats that number 50-200 usually define those with premutations and are termed unaffected carriers. We report here a compound heterozygous female who carried CGG repeats in the FMR1 gene that fall within the premutation and full mutation ranges. The former appears to have been inherited from the father, whereas the latter is an expansion of the premutation carried by the proband's mother. Therefore, the offspring of the proband will carry a significant risk of being affected with Fragile X syndrome, and the paternal uncle and any cousins should be counselled for being at risk for this syndrome.     

Akt-mediated phosphorylation of the G protein-coupled receptor EDG-1 is required for endothelial cell chemotaxis

The role of the protein kinase Akt in cell migration is incompletely understood. Here we show that sphingosine-1-phosphate (S1P)-induced endothelial cell migration requires the Akt-mediated phosphorylation of the G protein-coupled receptor (GPCR) EDG-1. Activated Akt binds to EDG-1 and phosphorylates the third intracellular loop at the T(236) residue. Transactivation of EDG-1 by Akt is not required for G(i)-dependent signaling but is indispensable for Rac activation, cortical actin assembly, and chemotaxis. Indeed, T236AEDG-1 mutant sequestered Akt and acted as a dominant-negative GPCR to inhibit S1P-induced Rac activation, chemotaxis, and angiogenesis. Transactivation of GPCRs by Akt may constitute a specificity switch to integrate rapid G protein-dependent signals into long-term cellular phenomena such as cell migration.     

A mammalian sequence-dependent upstream open reading frame mediates polyamine-regulated translation in yeast

In mammals, control of S-adenosylmethionine decarboxylase (AdoMetDC) translation is one component of a feedback network that regulates intracellular levels of the polyamines, spermidine, and spermine. AdoMetDC mRNA from mammals contains a highly conserved upstream open reading frame (uORF) within its leader sequence that confers polyamine-regulated suppression of translation on the associated downstream cistron. This regulation is mediated through an interaction that depends on the amino acid sequence of the uORF-encoded hexapeptide. It remains to be shown whether polyamines participate directly in this interaction or indirectly through a specialized signal transduction pathway. We show that Saccharomyces cerevisiae does not have a uORF associated with its AdoMetDC gene (SPE2) and that ribosome loading on the SPE2 mRNA is not positively influenced by polyamine depletion, as it is in mammalian cells. Nevertheless, the mammalian AdoMetDC uORF, when introduced into a polyamine auxotroph of yeast, conferred polyamine regulation of both translational efficiency and ribosome loading on the associated mRNA. This regulatory activity depended on the amino acid sequence encoded by the fourth and fifth codons of the uORF, as in mammalian cells. The fact that the regulatory properties of this mammalian translational control element are quite similar in both mammalian and yeast cells suggests that a specialized signal transduction pathway is not required. Rather, it seems likely that polyamines may be directly participating in an interaction between the uORF-encoded peptide and a constitutive component of the translation machinery, which leads to inhibition of ribosome activity.     

Reconstruction of the nose damaged by cocaine

Nasal snorting of cocaine crystals causes destruction of the septal and nasal mucosa, which eventually provides exposure of the septal cartilage and nasal bones. This exposure eventually leads to septal chrondritis and nasal bone osteomyelitis. As this process continues, the severe loss of cartilage and bone allows gradual to total collapse of the nose. Correction of this deformity is best achieved by supplying new lining; this is possible by turning nasolabial flaps into the nasal vestibule to replace the lost and released lining. Once this has been accomplished, costal cartilage grafts can be inserted along the bridge and alae to maintain the structural integrity of the reconstruction.