Major deglaciation of east Antarctica during the early Late Pliocene? Not likely from a marine perspective

We have conducted an integrated study of ice-rafted debris (IRD) and oxygen isotopes (measured on Cibicides, Globigerina bulloides, and Neogloboquadrina pachyderma, using identical samples). We used samples from the early Late Pliocene Gauss Chron from ODP Site 114–704 on the Meteor Rise in the subantarctic South Atlantic.During the early Gauss Chron, the oxygen isotopic ratios are generally up to 0.5‰–0.6‰ less than their respective Holocene values. The lowest values in this record can accommodate a warming of about 2.5 °C OR a sea-level rise of about 50 m, but not both, and probably result from some warming and a small reduction in global ice volume. Starting with isotope stage MG2 [3.23 Ma on the Berggren et al. (1985) time scale; 3.38 on the Shackleton et al. (1995b) time scale] oxygen-isotopic values generally increase (and oscillate about a Holocene mean). The first significant IRD appears at the same time. There is a subsequent increase in IRD amounts upsection. In order to reach the site, this material must have been transported by large, tabular icebergs derived from Antarctic ice shelves or ice tongues, similar to occasional, large modern icebergs.This combined record suggests strongly that the Antarctic ice sheet was essentially intact; some warming at the drill site is indicated, but not a major reduction in ice-volume on Antarctica.     

Comparative seroprevalence and immunogenicity of six rare serotype recombinant adenovirus vaccine vectors from subgroups B and D

Recombinant adenovirus serotype 5 (rAd5) vector-based vaccines are currently being developed for both human immunodeficiency virus type 1 and other pathogens. The potential limitations associated with rAd5 vectors, however, have led to the construction of novel rAd vectors derived from rare Ad serotypes. Several rare serotype rAd vectors have already been described, but a detailed comparison of multiple rAd vectors from subgroups B and D has not previously been reported. Such a comparison is critical for selecting optimal rAd vectors for advancement into clinical trials. Here we describe the construction of three novel rAd vector systems from Ad26, Ad48, and Ad50. We report comparative seroprevalence and immunogenicity studies involving rAd11, rAd35, and rAd50 vectors from subgroup B; rAd26, rAd48, and rAd49 vectors from subgroup D; and rAd5 vectors from subgroup C. All six rAd vectors from subgroups B and D exhibited low seroprevalence in a cohort of 200 individuals from sub-Saharan Africa, and they elicited Gag-specific cellular immune responses in mice both with and without preexisting anti-Ad5 immunity. The rAd vectors from subgroup D were also evaluated using rhesus monkeys and were shown to be immunogenic after a single injection. The rAd26 vectors proved the most immunogenic among the rare serotype rAd vectors studied, although all rare serotype rAd vectors were still less potent than rAd5 vectors in the absence of anti-Ad5 immunity. These studies substantially expand the portfolio of rare serotype rAd vectors that may prove useful as vaccine vectors for the developing world.     

Aortic and ventricular dilation and myocardial reduction in gestation day 17 ICR mouse fetuses of diabetic mothers

BACKGROUND: Maternal diabetes mellitus is associated with increased fetal teratogenesis, including cardiovascular defects. Information regarding cardiovascular changes in late-gestation fetal mice, related to maternal hyperglycemia, is not present in the literature. METHODS: Late-gestation fetal heart and great vessel morphology were analyzed in fetuses from control and diabetic mice. Female ICR mice were injected with streptozocin (200 mg/kg IP) prior to mating to induce diabetes (n = 8). Nonhyperglycemic females were used as controls (n = 8). At day 17 of gestation, females were euthanized and one fetus was arbitrarily selected per litter to analyze the heart and great vessels. Six additional fetuses from different litters, showing external malformations (spina bifida and/or exencephaly), were also evaluated from the diabetic group. Fetal thoraxes were processed using routine histopathologic techniques, and 7-mum transversal sections were stained with hematoxylin-eosin. Digital images of sections were made and analyzed using NIH Image J software to compare regional cardiac development. Student's t tests for means were performed to determine differences between groups (p < .05). RESULTS: Maternal hyperglycemia caused a dilation of late-gestation fetal ventricular chambers, a reduction of total ventricular myocardial area, and an increase in transversal ascending thoracic aortic area. Three of six fetuses that displayed external malformations showed an overt cardiac defect, beyond the ventricular and myocardial changes. CONCLUSIONS: Maternal hyperglycemia altered morphology of the late-gestation fetal mouse heart. Postnatal persistence or consequences of late-gestation heart chamber dilation and myocardial reduction are not yet known.     

Origin and divergence of Afro-Indian Picrodendraceae: linking pollen morphology,dispersal modes,fossil records,molecular dating and paleogeography

The pantropical Picrodendraceae produce mostly spheroidal to slightly oblate, echinate pollen grains equipped with narrow circular to elliptic pori that can be hard to identify to family level in both extant and fossil material using light microscopy only. Fossil pollen of the family have been described from the Paleogene of America, Antarctica, Australia, New Zealand, and Europe, but until now none have been reported from Afro-India. Extant pollen described here include representatives from all recent Picrodendraceae genera naturally occurring in Africa and/or Madagascar and south India and selected closely related tropical American taxa. Our analyses, using combined light microscopy and scanning electron microscopy, show that pollen of the Afro-Indian genera encompass three morphological types: Type 1, comprising only Hyaenanche; Type 2, including Aristogeitonia, Mischodon, Oldfieldia and Voatamalo; Type 3, comprising the remaining two genera, Androstachys and Stachyandra. Based on the pollen morphology presented here it is evident that some previous light microscopic accounts of spherical and echinate fossil pollen affiliated with Arecaceae, Asteraceae, Malvaceae, and Myristicaceae from the African continent could belong to Picrodendraceae. The pollen morphology of Picrodendraceae, fossil pollen records, a dated intra-familial phylogeny, seed dispersal modes, and the regional Late Cretaceous to early Cenozoic paleogeography, together suggest the family originated in the Americas and dispersed from southern America across Antarctica and into Australasia. A second dispersal route is believed to have occurred from the Americas into continental Africa via the North Atlantic Land Bridge and Europe.     

Systematic deletion analyses of the fla genes in the flagella operon identify several genes essential for proper assembly and function of flagella in the archaeon, Methanococcus maripaludis

The archaeal flagellum is a unique motility apparatus in the prokaryotic domain, distinct from the bacterial flagellum. Most of the currently recognized archaeal flagella-associated genes fall into a single fla operon that contains the genes for the flagellin proteins (two or more genes designated as flaA or flaB ), some variation of a set of conserved proteins of unknown function ( flaC , flaD , flaE , flaF , flaG and flaH ), an ATPase ( flaI ) and a membrane protein ( flaJ ). In addition, the flaD gene has been demonstrated to encode two proteins: a full-length gene product and a truncated product derived from an alternate, internal start site. A systematic deletion approach was taken using the methanogen Methanococcus maripaludis to investigate the requirement and a possible role for these proposed flagella-associated genes. Markerless in-frame deletion strains were created for most of the genes in the M. maripaludis fla operon. In addition, a strain lacking the truncated FlaD protein [FlaD M(191)I] was also created. DNA sequencing and Southern blot analysis confirmed each mutant strain, and the integrity of the remaining operon was confirmed by immunoblot. With the exception of the ΔFlaB3 and FlaD M(191)I strains, all mutants were non-motile by light microscopy and non-flagellated by electron microscopy. A detailed examination of the ΔFlaB3 mutant flagella revealed that these structures had no hook region, while the FlaD M(191)I strain appeared identical to wild type. Each deletion strain was complemented, and motility and flagellation was restored. Collectively, these results demonstrate for first time that these fla operon genes are directly involved and critically required for proper archaeal flagella assembly and function.     

Biological structure and health implications from tooth size at Mission San Luis de Apalachee

This study analyzes dental metric variation to examine the biological structure of the native population at Mission San Luis de Apalachee, a late 17th century mission located in the Apalachee Province of Spanish colonial Florida. Three topics are addressed: (1) comparison of tooth sizes among adult and subadults, (2) analysis of the bio-spatial structure of skeletons within the church area, and (3) comparison of phenotypic profiles of individuals interred within coffins in the ritual nucleus of the church: the altar region. Analyses indicate that subadults had smaller average tooth sizes than adults for the posterior dentition that was particularly evident in mandibular nonpolar molars and premolars. This disparity, also documented in two other mission populations, likely represents ontogenetic stress and resulting increased mortality among those most at risk for early death. Analysis of the spatial structure of graves failed to document biological structuring by side of the aisle or by burial row, although some gross differences were evident when front, middle, and rear church burials were compared. Individuals buried in coffins within the same row were phenotypically similar to one another. However, inter-row comparisons indicated lack of phenotypic similarity among all coffin interments. These analyses suggest maintenance of kin-structured burial for elites alone within the San Luis community.     

Sexual dimorphism of the dental tissues in human permanent mandibular canines and third premolars

Methods of measuring tissue area from images of longitudinal thin tooth sections have been used to assess sexual dimorphism in the permanent dentition. The aim of this study was to demonstrate the extent of sexual dimorphism within the coronal tissue proportions of permanent mandibular canines and premolars, using area measurements of the enamel and dentine-pulp core. The sample consisted of embedded "half-tooth" sections from 45 individuals, all of known age-at-death and sex, collected from the St. Thomas' Anglican Church historic (1821-1874) cemetery site in Belleville, ON, Canada. The relative dentine-pulp area of the third premolars and canines displayed high levels of sexual dimorphism, as well as statistically significant mean differences between the sexes. The male canines and premolars have significantly more dentine than their female counterparts, as well as relatively more dentine with respect to overall crown size. The female canines and premolars have significantly more enamel relative to overall crown area than those of the males. These results suggest that relative area measures of crown tissues are more predictable measures of sexual dimorphism than absolute measures, and tissue proportions may remain constant despite intrasex variation in overall tooth crown size.     

Determinants governing ligand specificity of the Vibrio harveyi LuxN quorum‐sensing receptor

Quorum sensing is a process of bacterial cell–cell communication that relies on the production, release and receptor‐driven detection of extracellular signal molecules called autoinducers. The quorum‐sensing bacterium Vibrio harveyi exclusively detects the autoinducer N‐((R)‐3‐hydroxybutanoyl)‐L‐homoserine lactone (3OH‐C4 HSL) via the two‐component receptor LuxN. To discover the principles underlying the exquisite selectivity LuxN has for its ligand, we identified LuxN mutants with altered specificity. LuxN uses three mechanisms to verify that the bound molecule is the correct ligand: in the context of the overall ligand‐binding site, His210 validates the C₃ modification, Leu166 surveys the chain‐length and a strong steady‐state kinase bias imposes an energetic hurdle for inappropriate ligands to elicit signal transduction. Affinities for the LuxN kinase on and kinase off states underpin whether a ligand will act as an antagonist or an agonist. Mutations that bias LuxN to the agonized, kinase off, state are clustered in a region adjacent to the ligand‐binding site, suggesting that this region acts as the switch that triggers signal transduction. Together, our analyses illuminate how a histidine sensor kinase differentiates between ligands and exploits those differences to regulate its signaling activity.