The physical characteristics of the members during the International Biomedical Expedition to the Antarctic

Twelve male medical scientists formed the International Biomedical Expedition to the Antarctic (IBEA). Their physical characteristics and maximum oxygen uptakes (VO2max) were measured in association with three series of thermal tolerance tests in Sydney, twice before and once after going to the Antarctic. In the Antarctic they lived in tents and spent 15 days travelling by motor toboggan. Their body mass (BM) and skinfold thickness (SFT) were measured four times during the 69 days the expedition spent in the field. The characteristics of the group were (ranges): age 26-52 years, height 1680-1889 mm, BM 58.5-103.4 kg, fatness 16-34% BM and VO2max 33-49 ml X kg-1 X min-1. In the Antarctic 9 men lost between 0.7 and 5.5 kg (mean 2.7 kg) of BM with a decrease in SFT, whilst 2 men increased BM by 1.2 and 1.9 kg without change in SFT. One man retired early from the expedition. BM and SFT were regained and physical fitness lost during the return voyage to Australia. Consequently there was no difference in average SFT between the pre- and post-Antarctic laboratory tests, but BM was greater after the Antarctic implying gains in fat free mass. VO2max was lower in the final laboratory tests than in the tests before Antarctica.     

On the control of ecdysone biosynthesis by the central nervous system of blowfly larvae

Ecdysone was found to be the major secreted steroid of ring glands dissected from blowfly larvae and incubated in vitro. Other secretory products such as 3-dehydroecdysone and 20-deoxy-makisterone A could not be detected when the glands were labelled with tritiated cholesterol. Ecdysone synthesis and secretion were found to be tightly coupled. The highest rate of secretion was observed a few hours before pupariation. In vitro, the rate of ecdysone secretion by ring glands was affected significantly by coincubation with the central nervous system (CNS). Modulating effects from the CNS to the gland were mediated both by culture medium and by nerve connections. Distinct parts of the CNS revealed multiple and partially opposite effects on ecdysone secretion, suggesting a more complex control than had been anticipated. Multiple neural control systems appear to be involved. Moreover, the observed effects changed with development during the second half of the third instar, reflecting a significant plasticity of neural control. © 1993 Wiley-Liss, Inc.     

A nektaspid arthropod from the Early Cambrian Sirius Passet fauna, with a description of retrodeformation based on functional morphology

ABSTRACT. The Sirius Passet fauna from the Lower Cambrian of North Greenland yields a diverse suite of poorly sclerotized arthropods. A new nektaspid from the fauna described here differs from typical naraoiids in having six thoracic segments and in being isopygous. Soft parts are poorly known, but posterior limbs are preserved in some specimens. Although specimens are invariably highly flattened, details of the axial articulation suggest that the animal could enrol. The widths of the articulating half rings can be used to reconstruct both the degree of rotation at each articulation during enrolment and the height at which each point along the half ring is above the fulcrum, and this in turn may be used to make a full three-dimensional reconstruction of the exoskeleton. This method of retrodeformation is in principle applicable to the reconstruction of other taxa, especially trilobites, found in shales.     

Taxonomy and species boundaries in the coral genus Favia Milne Edwards and Haime, 1857 (Cnidaria: Scleractinia) from Thailand revealed by morphological and genetic data

While Faviidae is a widely and uniformly distributed coral family throughout the Indo-Pacific, the extensive phenotypic plasticity of colony surface and corallite features often confounds the use of macromorphological characters in species identification, and contributes to conflict between traditional classification and molecular analyses of the group. Recent advances in morphological and molecular techniques now provide a suite of methods to re-address coral taxonomy in complex groups, such as that represented by the Faviidae. This study combines morphologic measurements including “3D coordinates landmarks” data with phylogenetic assessments of nuclear (ITS) and mitochondrial (COI-trnM) DNA to assess species boundaries in nine species of Faviidae with para-septothecal walls from Thailand. Strong concordance was found between morphological features and a priori groupings based on both morphospecies and genetically defined groups (ITS and COI-trnM). Favia truncatus was the most well-defined species based on morphological analyses, and it was also shown to be monophyletic using phylogenetic analyses. Besides F. truncatus, the only other species that was found to be monophyletic in analyses of both genes was F. cf. helianthoides, but its skeletal morphology overlapped with the F. favus species complex (comprised of F. favus, F. speciosa, F. matthaii and F. rotumana). Although not genetically monophyletic, the F. favus species complex and F. pallida were fairly well delineated morphologically. Morphospecies within the F. favus species complex are therefore possibly a result of genetic drift and/or stable polymorphisms driven by divergent selection. These results represent a first step toward a taxonomic revision of the Indo-Pacific Favia, which will integrate morphological methods with the study of type material, genetic information, reproductive data, and tests of phenotypic plasticity—given that multiple lines of evidence are needed to resolve ambiguous species and assign species names.     

Mrc1 and DNA polymerase epsilon function together in linking DNA replication and the S phase checkpoint

Yeast Mrc1, ortholog of metazoan Claspin, is both a central component of normal DNA replication forks and a mediator of the S phase checkpoint. We report that Mrc1 interacts with Pol2, the catalytic subunit of DNA polymerase epsilon, essential for leading-strand DNA replication and for the checkpoint. In unperturbed cells, Mrc1 interacts independently with both the N-terminal and C-terminal halves of Pol2 (Pol2N and Pol2C). Strikingly, phosphorylation of Mrc1 during the S phase checkpoint abolishes Pol2N binding, but not Pol2C interaction. Mrc1 is required to stabilize Pol2 at replication forks stalled in HU. The bimodal Mrc1/Pol2 interaction may be an additional step in regulating the S phase checkpoint response to DNA damage on the leading strand. We propose that Mrc1, which also interacts with the MCMs, may modulate coupling of polymerization and unwinding at the replication fork.     

The hatching larva of the priapulid worm Halicryptus spinulosus

Background

Faces, as socially relevant stimuli, readily capture human visuospatial attention. Although faces also play important roles in the social lives of chimpanzees, the closest living species to humans, the way in which faces are attentionally processed remains unclear from a comparative-cognitive perspective. In the present study, three young chimpanzees (Pan troglodytes) were tested with a simple manual response task in which various kinds of photographs, including faces as non-informative cues, were followed by a target.

Results

When the target appeared at the location that had been occupied by the face immediately before target onset, response times were significantly faster than when the target appeared at the opposite location that had been by the other object. Such an advantage was not observed when a photograph of a banana was paired with the other object. Furthermore, this attentional capture was also observed when upright human faces were presented, indicating that this effect is not limited to own-species faces. On the contrary, when the participants were tested with inverted chimpanzee faces, this effect was rather weakened, suggesting the specificity to upright faces.

Conclusion

Chimpanzee's visuospatial attention was easily captured by the face stimuli. This effect was face specific and stronger for upright faces than inverted. These results are consistent with those from typically developing humans.     

Mortality of young-of-the-year rainbow smelt (Osmerus mordax) in Lake Erie associated with the occurrence of Glugea hertwigi

An extensive mortality of young-of-the-year rainbow smelt (Osmerus mordax) occurred in Lake Erie during the fall of 1969. Dead and dying smelt were observed along the north shore from west of Long Point in the central basin to Port Maitland in the eastern basin. No other fish species was involved. Glugea hertwigi, a microsporidan parasite, was observed in 90% of the distressed smelt examined, and is believed to have been a major contributing factor to the mortality.     

Translation inhibitors induce cell death by multiple mechanisms and Mcl-1 reduction is only a minor contributor

There is significant interest in treating cancers by blocking protein synthesis, to which hematological malignancies seem particularly sensitive. The translation elongation inhibitor homoharringtonine (Omacetaxine mepesuccinate) is undergoing clinical trials for chronic myeloid leukemia, whereas the translation initiation inhibitor silvestrol has shown promise in mouse models of cancer. Precisely how these compounds induce cell death is unclear, but reduction in Mcl-1, a labile pro-survival Bcl-2 family member, has been proposed to constitute the critical event. Moreover, the contribution of translation inhibitors to neutropenia and lymphopenia has not been precisely defined. Herein, we demonstrate that primary B cells and neutrophils are highly sensitive to translation inhibitors, which trigger the Bax/Bak-mediated apoptotic pathway. However, contrary to expectations, reduction of Mcl-1 did not significantly enhance cytotoxicity of these compounds, suggesting that it does not have a principal role and cautions that strong correlations do not always signify causality. On the other hand, the killing of T lymphocytes was less dependent on Bax and Bak, indicating that translation inhibitors can also induce cell death via alternative mechanisms. Indeed, loss of clonogenic survival proved to be independent of the Bax/Bak-mediated apoptosis altogether. Our findings warn of potential toxicity as these translation inhibitors are cytotoxic to many differentiated non-cycling cells.