Do digger wasps time their provisioning activity to avoid cuckoo wasps (Hymenoptera: Crabronidae and Chrysididae)?

Strategies adopted by parasitoids and kleptoparasites co-evolve with the defensive adaptations of their hosts, and vice-versa. Hedychrum rutilans and Hedychrum nobile are brood parasites of, respectively, Philanthus triangulum and Cerceris arenaria, two digger wasps that share most aspects of their nesting biology (solitary females dig aggregated nests in the ground and mass-provision the brood with paralyzed insects). We tested the hypothesis that similarity in the hosts’ nesting habits corresponds to similar defensive strategies against these cuckoo wasps. Peak provisioning activity by P. triangulum occurred in late afternoon (and early morning in 1 year) while peak H. rutilans activity was in early afternoon. In contrast, peak provisioning by C. arenaria and peak H. nobile activity occurred in early afternoon. Thus, P. triangulum (as previously found in other populations) appears to have timed its provisioning to avoid its brood parasite whereas C. arenaria did not, rejecting our hypothesis. The daily activity of both chrysidid wasps was positively correlated to air temperature. Host nest density positively affected only H. rutilans activity, in agreement with previous reports for other populations of this species, whereas the daily pattern of activity of the host was the key correlate with the activity of H. nobile. Mortality due to cuckoo wasps was low for both digger wasps, although it was somewhat higher at sites with many nests of P. triangulum. We suggest that perhaps the degree to which digger wasps time their activity to avoid cuckoo wasps is related to the degree of specialization in host choice by their brood parasite. H. rutilans is more highly dependent on P. triangulum, which may have had a greater effect on the timing of provision by its host.     

Enhanced Ca2+ storage in sphingosine-1-phosphate lyase-deficient fibroblasts

Sphingosine-1-phosphate (S1P) regulates cell growth and survival, migration and adhesion in many cell types. S1P is generated by sphingosine kinases (SphKs), and dephosphorylated by phosphatases or cleaved by S1P lyase. Extracellular S1P activates specific G protein-coupled receptors while intracellular S1P can mobilize Ca²⁺ from thapsigargin-sensitive stores. Here, we have studied Ca²⁺ signalling in mouse embryonic fibroblasts (MEFs) deficient in S1P lyase. In these cells, S1P and sphingosine concentrations were elevated about 6-fold and 2-fold, respectively, as measured by liquid chromatography/tandem mass spectrometry. Measurements with fura-2-loaded cells in suspension revealed that resting [Ca²⁺]_i was elevated and agonist-induced [Ca²⁺]_i increases were augmented in S1P lyase-deficient MEFs both in the presence and absence of extracellular Ca²⁺. Importantly, [Ca²⁺]_i increases and Ca²⁺ mobilization induced by the SERCA inhibitor, thapsigargin, were augmented, indicating enhanced Ca²⁺ storage in S1P lyase-deficient MEFs. Measurements with single cells expressing the calmodulin-based Ca²⁺ sensor, cameleon, revealed that at least two cell types could be distinguished in both MEF cell populations, one with a rapid and transient [Ca²⁺]_i increase and the other with a slower and prolonged [Ca²⁺]_i elevation upon stimulation with thapsigargin. The area under the time course of thapsigargin-induced [Ca²⁺]_i increases, reflecting overall Ca²⁺ release, was significantly increased by more than 50% in both rapidly and slowly responding S1P lyase-deficient cells. It is concluded that elevated concentrations of S1P and/or sphingosine lead to enhanced Ca²⁺ storage and elevated basal [Ca²⁺]_i. S1P metabolism thus plays a role not only in acute Ca²⁺ mobilization but also in long-term regulation of Ca²⁺ homeostasis.     

Thermodynamics of binding of regulatory ligands to tissue transglutaminase

Amino Acids - The transamidating activity of tissue transglutaminase is regulated by the ligands calcium and GTP, via conformational changes which facilitate or interfere with interaction with the...     

A non-pollen palynomorphs contribution to the local environmental history in the Ligurian Apennines: a preliminary study

As part of a regional research project on wetlands, a analysis was carried out on non pollen palynomorphs (NPP) from the upper sediments of a mountain peat bog in the Ligurian Apennines, northwest Italy. The aim of this project was to see if NPPs could yield useful results on local ecology and human activity in connection with the use of resources. More than 60 NPP types were found, among which a new type is described. A good agreement was observed between pollen assemblages and different NPP types, which are still an under-exploited source of information. Coprophilous fungi suggest the presence of livestock at the site after cal. a.d. 770–1160, while various algae and other water-demanding organisms show an increasing eutrophication of the environment in the most recent phase after cal. a.d. 1500. This approach, which is new for this region, confirms the hypothesis that local farming practices, such as management of pasture and woodland, were not recently established here. The site features and both NPP variety and significance show that further improvement of this additional tool could contribute to answering some questions about past cultural landscapes.     

Solid phase subtractive cloning in differentially expressed genes identification

We developed an array-based subtractive hybridization system for one-step high-throughput subtraction. We printed subtractor RNA up to 10.000 times obtaining an excellent contact surface using a little amount of RNA. During hybridization cDNA, common to subtractor and target samples, remains attached to slide immobilized RNA, leaving free in solution target specific cDNA which after retrieval is cloned.     

PNA zipper as a dimerization tool: Development of a bZip mimic

The article describes the use of a PNA duplex (PNA zipper) as a tool to dimerize or bring in close proximity two polypeptides or protein domains. The amino acid sequence to be dimerized is covalently bound to complementary PNA sequences. Annealing of the PNA strands results in dimer formation. To test the ability of the “PNA‐zipper” as a dimerization tool, we designed a GCN4 mimetic, where the leucine‐zipper dimerization domain was replaced by the PNA zipper, whereas the basic DNA‐binding domain was covalently attached to the PNA. The molecule was assembled by chemical ligation of the peptide corresponding to the DNA‐binding domain of GCN4 modified with a succinyl thioester with two complementary PNAs harboring a cysteine residue. Electromobility‐shift experiments show the ability of the PNA zipper‐GCN4 to bind selected DNA duplexes. The PNA zipper‐GCN4 binds both the TRE and CRE DNA sites, but it does not bind TRE and CRE mutants containing even a single base mutation, as the native GCN4. The ability to fold upon complexation with DNA was investigated by CD. A good correlation between the ability of the PNA zipper‐GCN4 to fold into α helices and the ability to bind DNA was found. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 434–441, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

FIRST RECORD OF GRACILARIA VERMICULOPHYLLA (GRACILARIALES,RHODOPHYTA) IN THE PO DELTA LAGOONS,MEDITERRANEAN SEA (ITALY)1

Molecular outcomes led us to report the first occurrence of the invasive alien species Gracilaria vermiculophylla (Ohmi) Papenf. in the Mediterranean Sea. This species was recorded for the first time in the Po Delta lagoons in May and October 2008, probably introduced by the importation of the Manila clam Tapes philippinarum. At present, G. vermiculophylla is spread only near some clam‐farming areas, but its diffusion is expected to increase with the colonization of other lagoons where aquaculture is spread, as already observed for other alien species such as Agardhiella subulata and Solieria filiformis. The present study supplies further information on the morphology of this species, the ecological characteristics of the colonized areas, and the most probable introduction vector, confirming that the species spreading occurs in eutrophic and turbid coastal systems.     

Ethical issues in translational research

The translation of biomedical research knowledge to effective clinical treatment is essential to the public good and is a main focus of current health policy. However, recent health policy initiatives intended to foster the translation of basic science into clinical and public health advances must also consider the unique bioethical issues raised by the increased focus on translational research. Safety of study participants and balancing of risk due to treatment with the potential benefits of the research is tantamount. This article synthesizes theory from clinical ethics, operational design, and philosophy to provide a bioethical framework for the health policy of translational research.     

A duplex real-time PCR assay for detection of mutT4 and mutT2 mutations in Mycobacterium tuberculosis of Beijing genotype

To determine the polymorphism of mutT genes of Mycobacterium tuberculosis of Beijing genotype, we developed a duplex real-time PCR assay based on hybridization probes for the Roche LightCycler instrument. The assay rapidly detects mutations at codons 48 and 58 of genes mutT4 and at mutT2, respectively.