A tree-ring and C-14 chronology of the key Sayan-Altai monuments

We present a radiocarbon chronology of key Sayan-Altai monuments from the Scythian period, based on a statistical analysis of dates produced in the 1980s and now supplemented with new dates. These new C-14 dates were produced for samples from the Tuekta-1 barrows (burial mounds) and were measured both in St. Petersburg and Groningen. These tree-ring samples were fitted to the calibration curve. Chronologies were established for the Arzhan, Tuekta-1 and Pazyryk-5 barrows. The time of the construction of the Arzhan and Pazyryk-5 barrows is the 9th and late 5th-4th centuries BC, respectively, and agrees with archaeology. According to new data obtained, the time of the Tuekta-1 barrow construction is some years older than has been accepted thus far by archaeologists.</p

Reply to S Riehl and K Pustovoytov (Journal of Archaeological Science 33 (2006) 143-144)

We appreciate the interest of Simone Riehl and Konstantin Pustovoytov (hereafter R&P) in our publication and here we answer their critical remarks and questions. R&P criticise two aspects: (1) our interpretation of the pollen record from Kutuzhekovo Lake and (2) the information we derived from the St. Petersburg radiocarbon database. We discuss the questions and we show that these do not really affect our earlier conclusions.

Functional Changes in the Snail Statocyst System Elicited by Microgravity

BACKGROUND: The mollusk statocyst is a mechanosensing organ detecting the animal's orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations. METHODOLOGY/PRINCIPAL FINDINGS: In terrestrial gastropod snail we studied the impact of 16- (Foton M-2) and 12-day (Foton M-3) exposure to microgravity in unmanned orbital missions on: (i) the whole animal behavior (Helix lucorum L.), (ii) the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L.), and (iii) the differential expression of the Helix pedal peptide (HPep) and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.). Experiments were performed 13-42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed. CONCLUSIONS/SIGNIFICANCE: Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism's ability to adapt to gravity changes. This simple animal model offers the possibility to describe general subcellular mechanisms of nervous system's response to conditions on Earth and in space