Monthly changes in various drone characteristics of Apis mellifera ligustica and Apis mellifera syriaca

This study was conducted to investigate drone rearing activity and semen production of Apis mellifera ligustica and Apis mellifera syriaca . Tendency of worker bees of both subspecies towards egg laying under semiarid conditions were also monitored in the experiments. Differences were not observed in drone brood production between both honeybee subspecies throughout the investigation. Worker bees of both subspecies needed a significantly shorter time to start egg laying during February and March in comparison with the time those workers needed for laying eggs during the remaining months of the study. Syrian bee workers started egg laying earlier than Italian bee workers. Drones from laying workers were much smaller and produced less sperms with more abnormalities than normal drones. Drones produced from queens in May were heavier and produced more sperms with less abnormalities than those produced during the other months. The drone brood rearing of both subspecies tended to follow the same general cycle in 2005 and 2006. The study suggests that virgin queens have a better chance to receive adequate viable sperm amounts from drones in April and May in semiarid Mediterranean conditions.     

Serum deprivation induced autophagy and predominantly an AIF-dependent apoptosis in hippocampal HT22 neurons

Neuronal death induced by serum deprivation (SD) in HT22-cells was accompanied by a moderate activation of caspase-3, a prominent upregulation of AIF and its translocation into the nucleus. In addition protein levels of autophagy markers such as LC3 and beclin-1 were affected by SD. The ratio of LC3-II/LC3-I was significantly increased in serum deprived cultures. Furthermore, the addition of the pan-caspase inhibitor z-VAD(OMe)-FMK (zVAD) does not protect HT22-cells from SD-induced neurodegeneration. However, addition of the autophagy inhibitors such as 3-methyladenine (3-MA) or bafilomycin A1 (BafA1) provided a potentiation of cell death induced by SD. z-VAD and 3-MA in combination were not only ineffective in rescuing cells from the damaging effects of SD, but seem likely to act in synergy to potentiate slightly SD-induced cell death. The results of the current study suggest that SD induced predominantly caspase-independent apoptosis in hippocampal HT22 cells and that inhibition of autophagy is rather deleterious than protective.     

A universal core genetic map for rice

To facilitate the creation of easily comparable, low-resolution genetic maps with evenly distributed markers in rice (Oryza sativa L.), we conceived of and developed a Universal Core Genetic Map (UCGM). With this aim, we derived a set of 165 anchors, representing clusters of three microsatellite or simple sequence repeat (SSR) markers arranged into non-recombining groups. Each anchor consists of at least three, closely linked SSRs, located within a distance below the genetic resolution provided by common, segregating populations (<500 individuals). We chose anchors that were evenly distributed across the rice chromosomes, with spacing between 2 and 3.5 Mbp (except in the telomeric regions, where spacing was 1.5 Mbp). Anchor selection was performed using in silico tools and data: the O. sativa cv. Nipponbare rice genome sequence, the CHARM tool, information from the Gramene database and the OrygenesDB database. Sixteen AA-genome accessions of the Oryza genus were used to evaluate polymorphisms for the selected markers, including accessions from O. sativa, O. glaberrima, O. barthii, O. rufipogon, O. glumaepatula and O. meridionalis. High levels of polymorphism were found for the tested O. sativa × O. glaberrima or O. sativa × wild rice combinations. We developed Paddy Map, a simple database that is helpful in selecting optimal sets of polymorphic SSRs for any cross that involves the previously mentioned species. Validation of the UCGM was done by using it to develop three interspecific genetic maps and by comparing genetic SSR locations with their physical positions on the rice pseudomolecules. In this study, we demonstrate that the UCGM is a useful tool for the rice genetics and breeding community, especially in strategies based on interspecific hybridisation.     

Translocation of the Serine Protease Omi/HtrA2 from Mitochondria into the Cytosol Upon Seizure-Induced Hippocampal Injury in the Neonatal Rat Brain

Omi/HtrA2 is a pro-apoptotic mitochondrial serine protease involved in caspase-dependent as well as caspase-independent cell death upon various brain injuries. However, the role of Omi/HtrA2 in neuronal death induced by status epilepticus (SE) in the immature brain has not been reported. In this study, we analyzed the contribution of serine protease Omi/HtrA2, its substrate X-linked inhibitor of apoptosis protein (XIAP) and the caspase-3 activation to damage of hippocamplal CA1 cells following lithium-pilocarpine SE in P14 rat pups. Status epilepticus in the immature brain significantly induced translocation of Omi/HtrA2 from mitochondria into the cytosol, increased cytosolic accumulation of Omi/HtrA2, induced appearance of XIAP-breakdown products and enhanced caspase-3 activity in the selectively vulnerable hippocampal CA1-subfield. Taken together, these results demonstrate for the first time that SE in the immature brain results in Omi/HtrA2 accumulation in the cytosol, where it probably promotes neuronal death by neutralizing and cleaving XIAP, one of the most potent endogenous inhibitors of apoptosis.     

Infantile cerebral and cerebellar atrophy is associated with a mutation in the MED17 subunit of the transcription preinitiation mediator complex

Primary microcephaly of postnatal onset is a feature of many neurological disorders, mostly associated with mental retardation, seizures, and spasticity, and it typically carries a grave prognosis. Five infants from four unrelated families of Caucasus Jewish origin presented soon after birth with spasticity, epilepsy, and profound psychomotor retardation. Head circumference percentiles declined, and brain MRI disclosed marked cereberal and cerebellar atrophy with severe myelination defect. A search for a common homozygous region revealed a 2.28 Mb genomic segment on chromosome 11 that encompassed 16 protein-coding genes. A missense mutation in one of them, MED17, segregated with the disease state in the families and was carried by four of 79 anonymous Caucasus Jews. A corresponding mutation in the homologous S.cerevisiae gene SRB4 inactivated the protein, according to complementation assays. Screening of MED17 in additional patients with similar clinical and radiologic findings revealed four more patients, all homozygous for the p.L371P mutation and all originating from Caucasus Jewish families. We conclude that the p. L371P mutation in MED17 is a founder mutation in the Caucasus Jewish community and that homozygosity for this mutation is associated with infantile cerebral and cerebellar atrophy with poor myelination.     

Distribution of short interstitial telomere motifs in two plant genomes: putative origin and function

Background  

Short interstitial telomere motifs (telo boxes) are short sequences identical to plant telomere repeat units. They are observed within the 5' region of several genes over-expressed in cycling cells. In synergy with various cis-acting elements, these motifs participate in the activation of expression. Here, we have analysed the distribution of telo boxes within Arabidopsis thaliana and Oryza sativa genomes and their association with genes involved in the biogenesis of the translational apparatus.     

Response to Mechanical Stress Is Mediated by the TRPA Channel Painless in the Drosophila Heart

Mechanotransduction modulates cellular functions as diverse as migration, proliferation, differentiation, and apoptosis. It is crucial for organ development and homeostasis and leads to pathologies when defective. However, despite considerable efforts made in the past, the molecular basis of mechanotransduction remains poorly understood. Here, we have investigated the genetic basis of mechanotransduction in Drosophila. We show that the fly heart senses and responds to mechanical forces by regulating cardiac activity. In particular, pauses in heart activity are observed under acute mechanical constraints in vivo. We further confirm by a variety of in situ tests that these cardiac arrests constitute the biological force-induced response. In order to identify molecular components of the mechanotransduction pathway, we carried out a genetic screen based on the dependence of cardiac activity upon mechanical constraints and identified Painless, a TRPA channel. We observe a clear absence of in vivo cardiac arrest following inactivation of painless and further demonstrate that painless is autonomously required in the heart to mediate the response to mechanical stress. Furthermore, direct activation of Painless is sufficient to produce pauses in heartbeat, mimicking the pressure-induced response. Painless thus constitutes part of a mechanosensitive pathway that adjusts cardiac muscle activity to mechanical constraints. This constitutes the first in vivo demonstration that a TRPA channel can mediate cardiac mechanotransduction. Furthermore, by establishing a high-throughput system to identify the molecular players involved in mechanotransduction in the cardiovascular system, our study paves the way for understanding the mechanisms underlying a mechanotransduction pathway.     

Analysis of the Arabidopsis cell suspension phosphoproteome in response to short-term low temperature and abscisic acid treatment

To shed light on the early protein phosphorylation events involved in plant cell signaling in response to environmental stresses, we studied changes in the phosphorylation status of the Arabidopsis cell suspension proteome after short-term low temperature and abscisic acid (ABA) treatment. We used radioactive pulse-labeling of Arabidopsis cell suspension cultures and two-dimensional (2-D) gel electrophoresis to identify proteins that are differentially phosphorylated in response to these treatments. Changes in the phosphorylation levels of several proteins were detected in response to short-term (5 min or less) cold (4°C) and chilling (12°C) stress and ABA treatment, and we observed that some of these changes were common between these treatments. In addition, we used Pro-Q Diamond phosphoprotein gel stain to study the steady-state protein phosphorylation status under the same treatments. We demonstrated that Pro-Q Diamond effectively stained phosphorylated proteins, however, the overall Pro-Q Diamond 2-D gel staining pattern of proteins extracted from low-temperature and ABA-treated cells was not consistent with the gel patterns obtained by in vivo radioactive labeling of phosphoproteins. These in vivo pulsed-labeling experiments demonstrate that the Arabidopsis phosphoproteome is dynamic in response to short-term low temperature and ABA treatment, and thus represents a strategy for the identification of signaling proteins that could be utilized in the production of chilling or freeze tolerant crop varieties.     

Spatial and temporal regulation of RACK1 function and N-methyl-D-aspartate receptor activity through WD40 motif-mediated dimerization

Efficient signaling requires accurate spatial and temporal compartmentalization of proteins. RACK1 is a scaffolding protein that fulfils this role through interaction of binding partners with one of its seven WD40 domains. We recently identified the kinase Fyn and the NR2B subunit of the N-methyl-D-Aspartate receptor (NMDAR) as binding partners of RACK1. Scaffolding of Fyn near its substrate NR2B by RACK1 inhibits Fyn phosphorylation of NR2B and thereby negatively regulates channel function. We found that Fyn and NR2B share the same binding site on RACK1; however, their binding to RACK1 is not mutually exclusive (Yaka, R., Thornton, C., Vagts, A. J., Phamluong, K., Bonci, A., and Ron, D. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 5710-5715). We therefore tested the hypothesis that RACK1 forms a homodimer that allows the simultaneous binding of Fyn and NR2B. We found that RACK1 binds to itself both in vitro and in the brain. Deletion analyses identified a RACK1-RACK1 dimer-binding site within the 4th WD40 repeat, and application of the 4th WD40 repeat or a peptide derivative to hippocampal slices inhibited NMDAR activity. We further found that in hippocampal slices, both RACK1 and NR2B associated with another WD40 protein, the beta-subunit of G protein (Gbeta), previously shown to heterodimerize with RACK1 in vitro (Dell, E. J., Connor, J., Chen, S., Stebbins, E. G., Skiba, N. P., Mochly-Rosen, D., and Hamm, H. E. (2002) J. Biol. Chem. 277, 49888-49895). However, activation of the pituitary adenylate cyclase polypeptide (1-38) G protein-coupled receptor, previously found to induce the dissociation of RACK1 from the NMDAR complex (Yaka, R., He, D. Y., Phamluong, K., and Ron, D. (2003) J. Biol. Chem. 278, 9630-9638), attenuated the association of Gbeta with RACK1 and NR2B. Based on these results, we propose that WD40-mediated homo- and heterodimerization of RACK1 mediate the formation of a transient signaling complex that includes the NMDAR, a G protein and Fyn.     

Post-ischemic activation of caspase-3 in the rat hippocampus: evidence of an axonal and dendritic localisation

The relationship between caspase-3 activation and delayed neuronal death after ischemia was examined. Expression of caspase-3 was evaluated by colorimetric assay, immunoblotting and by immunohistochemistry. Apoptosis was characterised by terminal desoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labelling. Immunohistochemistry showed caspase-3 activation in the whole hippocampus as early as 30 min after ischemia with exclusive localisation in fiber systems, especially in the perforant path and mossy fibers, Schaffer-collaterals, as well as apical and basal dendrites of pyramidal cells. One day post-ischemia, the 18 kDa cleavage product of caspase-3 (p18) was seen in all cell compartments (nucleus, cytosol and dendrites) throughout the entire subfields and the dentate gyrus with high distribution in mossy fibers. Two days post-ischemia, p18 kDa was only seen in the nuclei and cytosol of hippocampal cells without specific regional differences among hippocampal subfields. A significant number of apoptotic cells appeared only in the CA1 pyramidal cells at 2-3 days post-ischemia. Our data provides the first evidence that caspase-3 activation was detectable in the trisynaptic pathway fiber bundles which probably correspond to perforant path, alvear path and collaterals of Schaffer, and that activation of caspase-3 led to execution of apoptotic cell death program in selectively vulnerable areas, but not in the resistant area of the hippocampus.