Variability of ecdysteroid-induced cell cycle alterations in Drosophila Kc sublines

The cell cycle of two lines isolated from Drosophila Kc cells was followed by flow cytofluorometry and cell counting. The first line is the 8-9K clone which grew in a medium supplemented with 5% serum; the second, named subline KcO, grew in a serum-free medium. The stationary phase is characterized by a G2 cell accumulation: 73% in the 8-9K clone and 50% in the KcO subline. When the medium was supplemented with the steroid moulting hormone 20-hydroxyecdysone, more than 90% of 8-9K cells and 65% of KcO cells were progressively arrested in G2. In the continuous presence of 20-hydroxyecdysone, most of the 8-9K cells remain G2-arrested; no massive G2 release into M was observed and only a few cells were able to divide. When treated for only 3 or 7 days, a transient release into M and proliferation occurred after hormone-free medium renewal, largely masked by G2 cell death. These results are discussed in comparison with other reports on cell cycle alteration induced by ecdysteroids.     

Global trends of habitat destruction and consequences for parrot conservation

Human advance on natural habitats is a major cause of biodiversity loss. This transformation process represents a profound change in wooded environments, disrupting original communities of flora and fauna. Many species are highly dependent on forests, especially parrots (Psittaciformes) with almost a third of their species threatened by extinction. Most parrot species occur in tropical and subtropical forests, and given the forest dependence of most species, this is the main reason why habitat loss has been highlighted as the main threat for the group. Such habitat loss acts in synergy with other important threats (e.g., logging and poaching), which become especially problematic in certain developing countries along tropical latitudes. In this study, we used available information on parrot distributions, species traits, IUCN assessment, habitat loss and timber extraction for different periods, and distribution of protected areas, to determine conservation hotspots for the group, and analyze potential changes in the conservation status of these species. We detected four conservation hotspots for parrots: two in the Neotropics and two in Oceania, all of them facing different degrees of threat in regard of current habitat loss and agricultural trends. Our results suggest that the future of the group is subject to policymaking in specific regions, especially in the northeastern Andes and the Atlantic Forest. In addition, we predicted that agricultural expansion will have a further negative effect on the conservation status of parrots, pushing many parrot species to the edge of extinction in the near future. Our results have conservation implications by recommending protected areas in specific parrot conservation hotspots. Our recommendations to mitigate conservation risks to this group of umbrella species would also benefit many other coexisting species as well.     

Hemodynamic Impact of Absent or Reverse End-Diastolic Flow in the Two Umbilical Arteries in Growth-Restricted Fetuses

Objective

To determine if bilateral absent or reverse end-diastolic (ARED) flow in the two umbilical arteries (UAs) at the perivesical (PVC) segment represents a more severe degree of hemodynamic compromise than unilateral ARED flow at the PVC segment in singleton pregnancies complicated by intrauterine growth restriction (IUGR).

Methods

This was a prospective observational study. One hundred nine fetuses with IUGR underwent a total of 225 ultrasound (US) examinations. We measured the pulsatility index (PI) from the two UAs at the PVC segment, UA in the free floating cord (FFC), middle cerebral artery (MCA), ductus venosus (DV) and the aortic isthmus blood flow index (IFI). Three groups were classified according to bilateral positive end-diastolic (PED) flow, unilateral ARED flow or bilateral ARED flow in the UAs at the PVC segment.

Results

The proportions of US examinations with PED flow, unilateral ARED flow and bilateral ARED flow in the UAs were 54.7%, 20.4%, and 24.9%, respectively. At the last US examination, the IFI z-scores were significantly lower in the bilateral ARED group (-6.28±4.30) compared to the unilateral ARED group (-1.72±3.18, p<0.05) and the bilateral PED group (-0.83±2.36, p<0.05), the DV-PI z-scores were significantly higher in the bilateral ARED group (2.15±3.79) compared to the bilateral PED group (0.64±1.50, p<0.05). Before 32 weeks of gestation, the interval between US examination and delivery was significantly shorter in the bilateral ARED group (8.9 days ±8.2) than the unilateral ARED group (15.9 days ±13.4, p<0.05) and the bilateral PED group (30.3 days±25.7, p<0.05).

Conclusion

There are significant differences in fetal blood fluxes between left and right UA. Doppler examination at the PVC segment significantly improves the comparability of UA-PI between two successive US examinations and allows a longitudinal and independent hemodynamic investigation of each UA. Examination of a single UA in free floating cord may miss a large fraction of unilateral ARED flow. In singleton IUGR fetuses, a bilateral ARED flow in the UAs at the PVC segment indicates more severe hemodynamic compromise and worse fetal conditions than unilateral ARED flow.     

Systems biological approach to investigate the lack of familial link between Down's Syndrome & Neural Tube Disorders

Systems Biology involves the study of the interactions of biological systems and ultimately their functions. Down''s syndrome (DS) is one of the most common genetic disorders which are caused by complete, or occasionally partial, triplication of chromosome 21, characterized by cognitive and language dysfunction coupled with sensory and neuromotor deficits. Neural Tube Disorders (NTDs) are a group of congenital malformations of the central nervous system and neighboring structures related to defective neural tube closure during the first trimester of pregnancy usually occurring between days 18-29 of gestation. Several studies in the past have provided considerable evidence that abnormal folate and methyl metabolism are associated with onset of DS & NTDs. There is a possible common etiological pathway for both NTDs and Down''s syndrome. But, various research studies over the years have indicated very little evidence for familial link between the two disorders. Our research aimed at the gene expression profiling of microarray datasets pertaining to the two disorders to identify genes whose expression levels are significantly altered in these conditions. The genes which were 1.5 fold unregulated and having a p-value <0.05 were filtered out and gene interaction network were constructed for both NTDs and DS. The top ranked dense clique for both the disorders were recognized and over representation analysis was carried out for each of the constituent genes. The comprehensive manual analysis of these genes yields a hypothetical understanding of the lack of familial link between DS and NTDs. There were no genes involved with folic acid present in the dense cliques. Only – CBL, EGFR genes were commonly present, which makes the allelic variants of these genes – good candidates for future studies regarding the familial link between DS and NTDs.

Abbreviations

NTD - Neural Tube Disorders, DS - Down''s Syndrome, MTHFR - Methylenetetrahydrofolate reductase, MTRR– 5 - methyltetrahydrofolate-homocysteine methyltransferase reductase.     

Development of a strain-specific real-time PCR assay for the detection and quantification of the biological control agent Fo47 in root tissues

Being able to identify specifically a biological control agent at the strain level is not the only requirement set by regulations (EC)1107/2009, it is also necessary to study the interactions of the agent with the plant and the pathogen in the rhizosphere. Fo47 is a soil-borne strain of Fusarium oxysporum which has the capacity to protect several plant species against the pathogenic formae speciales of F. oxysporum inducing wilts. A strain-specific sequence-characterized amplified region marker has been designed which makes it possible to distinguish Fo47 from other strains of F. oxysporum. In addition, a real-time PCR assay has been developed to quantify Fo47 in root tissues. The proposed assay has been validated by following the dynamics of root colonization of tomato plants grown in soil infested with Fo47. Results showed that with the method it is possible to quantify Fo47 in roots in the absence or presence of the pathogen and in the absence or in presence of the native microbial communities.     

Water velocity dependence of phosphate uptake on a coral-dominated fringing reef flat,La Réunion Island,Indian Ocean

Phosphate uptake (P-uptake) into coral reef communities has been hypothesized to be mass-transfer limited. One method of demonstrating mass-transfer limitation of P-uptake is to show dependence of P-uptake on water velocity. Water velocity across reef flats varies with tides and swell; thus, we measured P-uptake over the entire reef flat on eight different days, representing a range in water velocities. P-uptake was calculated from changes in P concentration of the water column. Changes in P concentration were measured by water sampling at six sites along a 300-m cross-reef transect while simultaneously measuring water velocity. To smooth the variability in phosphate concentrations, peristaltic pumps were used to get time-integrated water samples for 4–6 h at each site. Water velocities were measured in the middle of the transect using an acoustic Doppler current profiler and were averaged to match the time-integrated water sampling. Depth-averaged cross-reef water velocities were 0.031 ± 0.013 m s⁻¹ (mean ± SD), while the root-mean-square water velocities, accounting for oscillatory flow, averaged 3.3 times higher, 0.101 ± 0.021 m s⁻¹ (mean ± SD). Phosphate decreased along all transects. The first-order rate constant for P-uptake (S) was 8.5 ± 2.4 m d⁻¹ (mean ± SD) and increased linearly with root-mean-square water velocity. The Stanton number derived from oscillatory flow, the ratio of the first-order rate constant for P-uptake to the root-mean-square water velocity (S/U _rms), was (9.4 ± 1.2) × 10⁻⁴ (mean ± SD). P-uptake ranged from 0.2 to 1.1 mmol P m⁻² d⁻¹, demonstrating that P-uptake is variable on short time scales and is directly related to P concentration and water velocity.

     

New thiocyanato and azido adducts of the redox-active Fe(η-C5Me5)(η-dppe) center: Synthesis and study of the Fe(II) and Fe(III) complexes

The new thiocyanato- (5) and azido- (6) complexes were synthesized and studied under their Fe(II) and Fe(III) redox states. For the first time among the various [Fe(η⁵-C₅Me₅)(η²-dppe)]-based cationic radicals studied so far, the magnitude and spatial orientation of the g-tensor diagonal values were experimentally determined for 5[PF₆]. These data are in good agreement with those issued from a DFT modelization. The changes experienced by the electronic structure of the Fe(II) complexes subsequent to oxidation are reminiscent of these previously observed for the known arylalkynyl analogues, albeit some differences can be pointed out. Thus, the differences observed in the ¹H NMR spectra of 5[PF₆] and 6[PF₆] are attributed to a slower electronic spin relaxation and to the differently oriented magnetic anisotropy. The sizeable spin density evidenced by DFT on the terminal atom of the ligands of the Fe(III) complexes renders these new paramagnetic metallo-ligands quite appealing for accessing larger polynuclear molecular assemblies with magnetically interacting centers.     

Peptides targeting the PDZ domain of PTPN4 are efficient inducers of glioblastoma cell death

PTPN4, a human tyrosine phosphatase, protects cells against apoptosis. This protection could be abrogated by targeting the PDZ domain of this phosphatase with a peptide mimicking the C-terminal sequence of the G protein of an attenuated rabies virus strain. Here, we demonstrate that glioblastoma death is triggered upon intracellular delivery of peptides, either from viral origin or from known endogenous ligands of PTPN4-PDZ, such as the C terminus sequence of the glutamate receptor subunit GluN2A. The killing efficiency of peptides closely reflects their affinities for the PTPN4-PDZ. The crystal structures of two PTPN4-PDZ/peptide complexes allow us to pinpoint the main structural determinants of binding?and to synthesize a peptide of high affinity for PTPN4-PDZ enhancing markedly its cell death capacity. These results allow us to propose a potential mechanism for the efficiency of peptides and provide a target and a robust framework for the design of new pro-death compounds.