Low intensity pulsed ultrasound accelerates macrophage phagocytosis by a pathway that requires actin polymerization, Rho, and Src/MAPKs activity.

Phagocytosis is an essential event in the complex process of tissue repair. Here we examined the effect of low intensity pulsed ultrasound (US), which promotes fracture and wound healing, on phagocytosis by mouse macrophage cell line J774A.1 and human monocyte-derived macrophages. First, 10 to 40 min low intensity pulsed US increased uptake of serum opsonized E. coli by J774A.1 cells during a 50 min phagocytosis period. In addition, when the E. coli exposure time was varied between 35 to 80 min, the maximum increase in phagocytosis was observed in the first 35 min upon US exposure. In parallel, US induced robust actin polymerization in a time dependent manner in J774A.1 cells, showing the peak effect 30 min after stimulation. Interestingly, a low concentration of cytochalasin D (0.25-0.5 microM) prevented US-induced phagocytosis of E. coli. Furthermore, we demonstrated US enhanced activation of RhoA. Blocking its downstream effector Rho associated kinase (ROCK) with Y27632 abrogated US-induced phagocytosis. We also show that US induced activation of ERK and p38 MAPK. Pretreatment of the cells with the corresponding inhibitors PD98059 and SB203580 reduced US-induced phagocytosis. In addition, activity of tyrosine kinase Src was required for US-induced phagocytosis. Here Src represents an upstream activator of ERK and p38 MAPK. Depolymerization of actin by cytochalasin D prevented US-induced Src, ERK, and p38 activation. Our data provide a new insight into the cellular and molecular mechanisms by which low intensity pulsed US promotes tissue repair.

Enhanced RNA cleavage within bulge-loops by an artificial ribonuclease.

Cleavage of phosphodiester bonds by small ribonuclease mimics within different bulge-loops of RNA was investigated. Bulge-loops of different size (1-7 nt) and sequence composition were formed in a 3' terminal fragment of influenza virus M2 RNA (96 nt) by hybridization of complementary oligodeoxynucleotides. Small bulges (up to 4 nt) were readily formed upon oligonucleotide hybridization, whereas hybridization of the RNA to the oligonucleotides designed to produce larger bulges resulted in formation of several alternative structures. A synthetic ribonuclease mimic displaying Pyr-Pu cleavage specificity cleaved CpA motifs located within bulges faster than similar motifs within the rest of the RNA. In the presence of 10 mM MgCl2, 75% of the cleavage products resulted from the attack of this motif. Thus, selective RNA cleavage at a single target phosphodiester bond was achieved by using bulge forming oligonucleotides and a small ribonuclease A mimic.

G-specific RNA-cleaving conjugates of short peptides and oligodeoxyribonucleotides.

Artificial ribonucleases, conjugates of short oligodeoxyribonucleotides and peptides built of arginine, leucine, proline, and serine, were synthesized and assessed in terms of ribonuclease activity and specificity of RNA cleavage. A specific group of the conjugates was identified that display T1-ribonuclease-like activity and cleave RNA predominantly at G-X sequences. Circular dichroism study of the structures of the most active conjugates, free peptide (LR)4G, and oligonucleotides revealed that conjugation of oligonucleotide to the peptide results in a specific peptide folding that possibly provides ribonuclease activity to the conjugate.

Covalently attached oligodeoxyribonucleotides induce RNase activity of a short peptide and modulate its base specificity.

New artificial ribonucleases, conjugates of short oligodeoxyribonucleotides with peptides containing alternating arginine and leucine, were synthesized and characterized in terms of their catalytic activity and specificity of RNA cleavage. The conjugates efficiently cleave different RNAs within single-stranded regions. Depending on the sequence and length of the oligonucleotide, the conjugates display either G-X>>Pyr-A or Pyr-A>>G-X cleavage specificity. Preferential RNA cleavage at G-X phosphodiester bonds was observed for conjugate NH2-Gly-[ArgLeu]4-CCAAACA. The conjugates function as true catalysts, exhibiting reaction turnover up to 175 for 24 h. Our data show that in the conjugate the oligonucleotide plays the role of a factor which provides an 'active' conformation of the peptide via intramolecular interactions, and that it is the peptide residue itself which is responsible for substrate affinity and catalysis.

The "Clever Hans Phenomenon" revisited.

In the first decade of the 20th century, a horse named Hans drew worldwide attention in Berlin as the first and most famous "speaking" and thinking animal. Hans solved calculations by tapping numbers or letters with his hoof in order to answer questions. Later on, it turned out that the horse was able to give the correct answer by reading the microscopic signals in the face of the questioning person. This observation caused a revolution and as a consequence, experimenters avoided strictly any face-to-face contact in studies about cognitive abilities of animals-a fundamental lesson that is still not applied rigorously.

The magical number four: A biological, historical and mythological enigma.

Precise recognition of small object numbers without counting is a widespread phenomenon. It is well documented for humans and for a series of non-human vertebrates. Recently this has been confirmed for an invertebrate, the honeybee.(1) This type of inborn numerical competence has been named "subitizing", from the Latin subito = suddenly, immediately. It differs from the classical, sequential counting which has to be trained, starting with the help of our fingers. For humans it had been established since 1871 by Jevons(2) that only up to four objects are precisely recognized and memorized. Under conditions which do not allow sequential counting, mistakes start to occur in case of more than four objects. This result has been confirmed whenever the range of visual attention has been carefully tested under a variety of rigorous conditions. It provides the basis for a novel hypothesis about the evolution of counting and numbering systems in ancient civilizations.(3)  

To bee or not to bee, this is the question : The inborn numerical competence of humans and honeybees.

Human inborn numerical competence means our ability to recognize object numbers precisely under circumstances which do not allow sequential counting. This archaic process has been called "subitizing," from the Latin "subito" = suddenly, immediately, indicating that the objects in question are presented to test persons only for a fraction of a second in order to prevent counting. In contrast, however, sequential counting, an outstanding cultural achievement of mankind, means to count "1, 2, 3, 4, 5, 6, 7, 8…" without a limit. The following essay will explain how the limit of numerical competence, i.e., the recognition of object numbers without counting, has been determined for humans and how this has been achieved for the first time in case of an invertebrate, the honeybee. Finally, a hypothesis explaining the influence of our limited, inborn numerical competence on counting in our times, e.g., in the Russian language, will be presented. Subitizing versus counting by young Down syndrome infants and autistics and the Savant syndrome will be discussed.

Give me 5 The invention of number five in ancient civilizations: A consequence of our limited inborn numerical competence.

Precise recognition of small numbers of objects without counting is an archaic, inborn ability of humans. Since almost 140 years it is known that we can recognize precisely only up to four objects if sequential counting is prevented. Vertebrates and invertebrates such as honeybees can recognize and remember three and up to four objects, respectively. A synopsis of counting systems in ancient civilizations reveals that our limited ability to recognize only four objects without counting influenced our counting and numbering systems and enforced the need for new symbols for numbers beyond four.

Inactivation of a non-enveloped RNA virus by artificial ribonucleases: honey bees and acute bee paralysis virus as a new experimental model for in vivo antiviral activity assessment.

RNA-containing viruses represent a global threat to the health and wellbeing of humans and animals. Hence, the discovery of new approaches for the design of novel vaccines and antiviral compounds attains high attention. Here we describe the potential of artificial ribonucleases (aRNases), low molecular weight compounds capable to cleave phosphodiester bonds in RNA under mild conditions, to act as antiviral compounds via destroying the genome of non-enveloped RNA viruses, and the potential of utilizing honey bee larvae and adult bees (Apis mellifera) as a novel experimental system for the screening of new antiviral compounds. Pre-incubation of an Acute bee paralysis virus (ABPV) suspension with aRNases D3-12, K-D-1 or Dp12F6 in a concentration-dependent manner increased the survival rate of bee larvae and adult bees subsequently infected with these preparations, whereas incubation of the virus with aRNases ABL3C3 or L2-3 had no effect at all. The results of RT-PCR analysis of viral RNA isolated from aRNase-treated virus particles confirmed that virus inactivation occurs via degradation of viral genomic RNA: dose-dependent inactivation of ABPV correlates well with the cleavage of viral RNA. Electron microscopy analysis revealed that the morphology of ABPV particles inactivated by aRNases remains unaffected as compared to control virus preparations. Altogether the obtained results clearly demonstrate the potential of aRNases as a new virus inactivation agents and bee larvae/ABPV as a new in vivo system for the screening of antiviral compounds.

Number-based visual generalisation in the honeybee.

Although the numerical abilities of many vertebrate species have been investigated in the scientific literature, there are few convincing accounts of invertebrate numerical competence. Honeybees, Apis mellifera, by virtue of their other impressive cognitive feats, are a prime candidate for investigations of this nature. We therefore used the well-established delayed match-to-sample paradigm, to test the limits of honeybees' ability to match two visual patterns solely on the basis of the shared number of elements in the two patterns. Using a y-maze, we found that bees can not only differentiate between patterns containing two and three elements, but can also use this prior knowledge to differentiate three from four, without any additional training. However, bees trained on the two versus three task could not distinguish between higher numbers, such as four versus five, four versus six, or five versus six. Control experiments confirmed that the bees were not using cues such as the colour of the exact configuration of the visual elements, the combined area or edge length of the elements, or illusory contours formed by the elements. To our knowledge, this is the first report of number-based visual generalisation by an invertebrate.

Yeast two-hybrid screens imply involvement of Fanconi anemia proteins in transcription regulation, cell signaling, oxidative metabolism, and cellular transport.

Mutations in one of at least eight different genes cause bone marrow failure, chromosome instability, and predisposition to cancer associated with the rare genetic syndrome Fanconi anemia (FA). The cloning of seven genes has provided the tools to study the molecular pathway disrupted in Fanconi anemia patients. The structure of the genes and their gene products provided few clues to their functional role. We report here the use of 3 FA proteins, FANCA, FANCC, and FANCG, as "baits" in the hunt for interactors to obtain clues for FA protein functions. Using five different human cDNA libraries we screened 36.5x10(6) clones with the technique of the yeast two-hybrid system. We identified 69 proteins which have not previously been linked to the FA pathway as direct interactors of FANCA, FANCC, or FANCG. Most of these proteins are associated with four functional classes including transcription regulation (21 proteins), signaling (13 proteins), oxidative metabolism (10 proteins), and intracellular transport (11 proteins). Interaction with 6 proteins, DAXX, Ran, IkappaBgamma, USP14, and the previously reported SNX5 and FAZF, was additionally confirmed by coimmunoprecipitation and/or colocalization studies. Taken together, our data strongly support the hypothesis that FA proteins are functionally involved in several complex cellular pathways including transcription regulation, cell signaling, oxidative metabolism, and cellular transport.