Differential 24‐Hour Variation of Alertness and Subjective Tension in Process Controllers: Investigation of the Relationship with Body Temperature and Heart Rate

The effects of shift and time‐on‐shift on alertness and perceived tension, as well as related physiological variables, were investigated in satellite controllers working a rapid forward rotating three‐shift system. In controlled laboratory conditions, subjective tension and HR have been reported to display circadian variation and marked sensitivity to external factors. We examined whether circadian variations were masked for these particular variables in real‐job conditions, unlike for alertness and body temperature, which have been repeatedly shown to display circadian variation in these conditions. This hypothesis was tested in a repeated‐measures design by collecting alertness and tension self‐reports and recording operators' sublingual temperature on three occasions on each shift and HR continuously throughout shifts. Alertness and body temperature varied according to a typical diurnal trend; subjective tension was only enhanced on the initial recording of each shift (compared to the remaining ones), while HR displayed an intermediary trend. Intra‐subject correlations revealed a positive relationship between alertness, oral temperature, and HR, while no such relationship was found for subjective tension. These results support the hypothesis of a close dependence of alertness and temperature, and to a lesser extent for HR, on endogenous mechanisms in this job‐situation. In addition, some situation‐specific factors, such as job‐demand, would affect subjective tension and partially mask the circadian variations in HR.     

Is RAD‐seq suitable for phylogenetic inference? An in silico assessment and optimization

Inferring phylogenetic relationships between closely related taxa can be hindered by three factors: (1) the lack of informative molecular variation at short evolutionary timescale; (2) the lack of established markers in poorly studied taxa; and (3) the potential phylogenetic conflicts among different genomic regions due to incomplete lineage sorting or introgression. In this context, Restriction site Associated DNA sequencing (RAD‐seq) seems promising as this technique can generate sequence data from numerous DNA fragments scattered throughout the genome, from a large number of samples, and without preliminary knowledge on the taxa under study. However, divergence beyond the within‐species level will necessarily reduce the number of conserved and non‐duplicated restriction sites, and therefore the number of loci usable for phylogenetic inference. Here, we assess the suitability of RAD‐seq for phylogeny using a simulated experiment on the 12 Drosophila genomes, with divergence times ranging from 5 to 63 million years. These simulations show that RAD‐seq allows the recovery of the known Drosophila phylogeny with strong statistical support, even for relatively ancient nodes. Notably, this conclusion is robust to the potentially confounding effects of sequencing errors, heterozygosity, and low coverage. We further show that clustering RAD‐seq data using the BLASTN and SiLiX programs significantly improves the recovery of orthologous RAD loci compared with previously proposed approaches, especially for distantly related species. This study therefore validates the view that RAD sequencing is a powerful tool for phylogenetic inference.     

Genetic variability in the wingless subantarctic genus Anatalanta (Diptera, Sphaeroceridae): a preliminary approach

The first study on the genetic variability of a wingless subantarctic fly (Diptera: Sphaeroceridae) at Iles Crozet is presented. Flies of the genus Anatalanta live mainly in seabird colonies from the littoral level to 700 m a.s.l. Two species are known: A. aptera Eaton and A. crozetensis Enderlein. Several morphological forms from 2 islands have been surveyed and 21 enzyme systems, involving 30 common putative enzyme loci, were scored from reared individuals. Mean heterozygosity values vary from 0.053 to 0.169. Genetic differentiation is weak with low Nei's distances. Noticeable gaps between morphological and genetic data are emphasized and question the real taxonomic status of the two recognized species. It is now necessary to compare populations of the genus Anatalanta from its whole distributional range (Iles Crozet, Iles Kerguelen and Heard Island). An improved understanding of the historical processes by which these islands were colonized could result from these studies. Received: 12 August 1996 / Accepted: 30 June 1997     

Multiple amylase genes in Drosophila ananassae and related species.

The number and organization of amylase genes in Drosophila ananassae were investigated through classical genetic methods and in situ and filter hybridizations. At least four genes may be active in D. ananassae, organized as two independent pairs of closely linked copies on the 2L and 3L chromosomal arms. Several other species of the D. ananassae subgroup were studied and show the same chromosomal locations, suggesting an ancient duplication event. However, the number of Amy copies seems to be higher in the D. ananassae multigene family, and there is a striking intraspecific molecular differentiation.     

Cloning and characterization of KM190, a specific satellite DNA family of Drosophila kitumensis and D. microlabis.

The nucleotide sequences of nine clones, pKA191/l-4 from Drosophila kitumensis and pMR.190/1–5 from D. microlabis, were determined. They represent a tandemly arranged and highly repetitive satellite DNA family, KM190, which is specific for the two species.     

Skp2 induction and phosphorylation is associated with the late G1 phase of proliferating rat hepatocytes.

The changes in phosphoproteins purified with the affinity peptide p9CKShs1 were analyzed from extracts of regenerating rat livers in order to define some G1 and G1/S regulations characteristic of mature hepatocytes stimulated to proliferate. We observed a 47 kDa phosphoprotein that occurred first at the end of G1 before peaking in the S phase. P47 was also found to be phosphorylated in late G1 in primary hepatocyte cultures stimulated with mitogens. P47 was still phosphorylated in extracts depleted of Cdc2, but to a lesser extent after Cdk2 depletion. This phosphoprotein was identified as Skp2. (i) P47 shared the same electrophoretic mobility than Skp2, a cell cycle protein essential for S phase entry in human fibroblasts; (ii) Skp2, like P47, started to be expressed and was highly phosphorylated during the G1/S transition of hepatocytes stimulated to proliferate in vivo and in vitro; (iii) P47 was specifically immunoprecipitated by an antibody directed against Skp2. In addition, cyclin A/Cdk2 complexes from regenerating liver clearly interacted with Skp2. This is the first demonstration that Skp2 is induced and phosphorylated in the late G1 and S phase of hepatocytes in vivo in regenerating liver as well as in vitro in mitogen-stimulated hepatocytes.     

Geographical variability of allozyme variation and genetic divergence between Tunisian lizards of the sand-dwelling lacertid genus Acanthodactylus

Acanthodactylus is a widespread lacertid genus including about thirthy species whose systematics remains much debated.The present study is aimed at improving the taxonomic status of the Tunisian species whose geographical distribution and ecological requirements have been studied elsewhere. Allozymic variation at 22 loci was scored in 14 populations for a total of 249 individuals. High genetic variability is confirmed in all samples; it is higher in species displaying a wide bioclimatic habitat range. No reduction of genetic variability was observed in two insular populations.Any interspecific hybrid could be detected from our genetic data, even in sympatric areas arguing in favor of specific status of four taxons in Northern, Central and Southern Tunisia.Phylogenetic relationships are discussed on the basis of UPGMA and Fitch-Margoliash procedures applied to the genetic distances matrix and centered data analysis of allozyme frequencies.     

New electrophoretic evidence of genetic variation and diploidy inTrypanosoma cruzi,the causative agent of Chagas' disease

By changing electrophoretic conditions additional genetic variability was observed in both previously and newly analysed enzymatic systems inTrypanosoma cruzi. Inferences on the quaternary structure of enzymes emerge from the electrophoretic patterns. The results of the present work are consistent with those obtained formerly in supporting both diploidy and lack of mating. These observations are relevant to the main question of the evolutionary origin ofT. cruzi isozymic strains.     

Dinosaur track record on a shallow carbonate-dominated ramp (Loulle section, Late Jurassic, French Jura)

In 2006, sauropod and theropod trackways were discovered at the locality of Loulle in the French Jura Mountains. During the Late Oxfordian (sensu gallico), Loulle was located at the southeastern margin of the carbonate-dominated French Jura platform. The upper part of the section contains a 94-cm-thick dinosaur track-bearing interval. Dinosaur tracks were recorded in a tidal-flat setting punctuated by frequent flooding and emersion phases leading to desiccation, microbial mat development, and new sediment inputs. Four types of tracks were identified relative to their morphologies and the rheology of the tracked sediment. Tracks were recorded on sediment with different degrees of water saturation, covered with a thick, cohesive, and elastic microbial mat. This mat cover prevented tracks from erosion agents but also prevented the record of trackmaker anatomical details. Early lithification, probably driven by enhanced dolomitization, allowed the rapid fossilization of the tracks, protecting them from reworking during the subsequent dinosaur tracking phases. Sequential analysis reveals that the record of dinosaur tracks was made possible by a gain of accommodation at the scale of elementary (infra-Milankovitch) and small-scale (100 kyr) sequences. The loss of accommodation observed at the scale of medium-scale (400 kyr) and very small scale (20 kyr) sequences enhanced the ramp progradation at the Bimammatum-Planula boundary, allowing dinosaurs to walk on the Loulle tidal-flat, along a narrow ENE/WSW isthmus.