Dating and rating of Harris's lines

Well-preserved skeletons of 50 Dutch whalers from the 17th and 18th centuries, buried on the island of Zeeusche Uytkyck , were excavated during the Spitsbergen Expedition 1980. In order to estimate the biological age of these skeletons at the time that Harris's lines were formed, a method which was developed from routine X-ray data on tibial growth was tested. Formation ages of diaphyseal lines and strong metaphyseal lines appear to correspond well with hypoplastic enamel deformations within the same individuals. Because of the involvement of both the bone and tooth developmental systems, and of the resistance of these lines to bone remodeling, it can be assumed that they generally are the result of serious health insults.     

On the nature and causes of luminescent lines and bands in coral skeletons: II. Contribution of skeletal crystals

Slices cut from skeletons of massive Porites display two types of luminescence when illuminated by ultra-violet (UV) light: (1) faint luminescent banding associated with the annual skeletal density banding pattern and (2) narrow lines of strong luminescence associated with monsoonal runoff of fresh water from nearby land. Barnes and Taylor [Barnes, D.J. Taylor, R.B. 2001a. On the nature and causes of luminescent lines and bands in coral skeletons. Coral Reefs 19, 221-230] showed how larger skeletal holes could give rise to increased luminescence—thus accounting for the link between skeletal density banding and faint luminescent banding. Work described here tests the notion that strongly luminescent lines are also regions of lower skeletal density. Experiments involving real and artificial coral skeletons indicated that likely changes in hole size in real skeletons cannot account for the amount of luminescence associated with luminescent lines. Larger particles (< 50 μm) of powdered skeleton from cut from luminescent lines were more luminescent than similar particles cut from adjacent less luminescent skeleton. However, very small particles (< 3 μm) from the two regions of skeleton showed no difference in luminescence. Since skeletal crystals would have been largely destroyed by powdering skeleton to very small particle sizes, most of the luminescence of strongly luminescent lines is probably associated with changed crystal size and packing, with changed crystal chemistry, or with a combination of these possibilities.     

Skeletal development in Hermesinum adriaticum Zacharias, a flagellate from the Salton Sea, California

Hermesinum adriaticum is a rarely reported unicellular biflagellated organism with a solid siliceous skeleton. Live specimens were not observed but many skeletons were found in sediments and, in small numbers, in cyanobacterial mats and the water column of the Salton Sea, a salt lake in California, U.S.A. Stages of the developing skeleton were studied with scanning electron microscopy, and the progression from small tetraxial daughter skeletons to complete asymmetrical adult skeletons is presented. Some variability in the adult skeletons is illustrated.     

Paleodontologic study of skeletal findings at Takht-i Suleiman, West Iran

Within this paleodontological study 26 Achemenid and 8 Islamic skeletons from the excavations at Tahkt-i Suleiman (Western Iran) were investigated. The diagnosis of age and sex was done repeatedly according to various methods. The adult Achemenids reached an average age of 54.4 years (n = 16; SD = +/- 9.9 y), while the Islamic adult individuals reached a lifespan of 36.9 (n = 8; SD = +/- 11.0 y). The skeletons of the Achemenid children had an average of 6.8 years (n = 9; SD = +/- 3.3 y). In the specific dental investigations the teeth of all skeletons were checked for missing teeth or dental diseases or alterations of the jaws. For the whole series intravital loss of 19.3% of the teeth was found. 21.6% of the teeth were lost postmortally. The intravital loss of single teeth was 21.9% in the Achemenid teeth, disregarding the wisdom tooth and Dentes decidui; the respective value was 12% in the Islamic skeletons. The investigation for caries yielded a morbidity of 50% in the Achemenid skeletons, and 57% in the Islamic teeth. The frequency of caries was 6.2% in Achemenids and 9% in Islamic individuals. In the Dentes decidui the frequency of caries was found to be 3.6%. Dental tartar was present in 44.8% of the teeth, 42% of Achemenid teeth and 58% of Islamic teeth being affected. 33% of all teeth showed garlands of dental tartar. Signs of parodontolysis were investigated considering the health of the individual and the preservation of the skeleton. All adult teeth showed age-dependent parodontolysis, the means of which were quantified.     

Band 3 tyrosine kinase. Association with the human erythrocyte membrane

Band 3, the anion transport protein of the human erythrocyte membrane, is known to be phosphorylated in ghosts at tyrosine 8. The band 3 tyrosine kinase is now shown to be associated with the Triton X-100 insoluble membrane skeleton but not with spectrin or actin. The kinase was reversibly dissociated from membranes and skeletons at elevated ionic strength (50% at mu = 0.15). The binding capacity of the membranes exceeded their native complement of the kinase by at least 60-fold. Prior removal of all peripheral proteins from the cytoplasmic surface of inside-out vesicles did not diminish the rebinding of the kinase, whereas prior removal of band 3 and other accessory proteins from skeletons abolished the rebinding of the kinase. An excess of glyceraldehyde-3-P dehydrogenase, which binds to band 3 in the region of the phosphate acceptor tyrosine 8, both inhibited the phosphorylation of band 3 and released the kinase into solution. Soluble 40/45-kDa chymotryptic fragments from the cytoplasmic pole of band 3 were phosphorylated at least as well as membranous band 3 and caused the release of the kinase from Triton-extracted skeletons. Membrane skeletons lacked most of the membrane band 3, but retained most of the kinase. Nevertheless, the band 3 population solubilized by Triton X-100 from prelabeled ghosts was as well phosphorylated as the population of band 3 retained by the skeletons. Furthermore, the fraction of band 3 not associated with the skeletons following Triton X-100 extraction was a good substrate for the solubilized kinase. We conclude that this tyrosine kinase is reversibly bound to the membrane through electrostatic interactions with the polyacidic sequence surrounding the phosphate accepting tyrosine 8 on band 3. The kinase appears to be preferentially linked to those band 3 molecules associated with the membrane skeleton, but it impartially phosphorylates band 3 species free in the bilayer as well as band 3 fragments in solution. The resemblance of its plasma membrane binding behavior to that of tyrosine kinases of certain viruses causing oncogenic transformation is discussed.     

Carbon allocation in wild-type and Glc+ Rhodobacter sphaeroides under photoheterotrophic conditions.

The photosynthetic bacterium Rhodobacter sphaeroides is capable of producing H2 via nitrogenase when grown photoheterotrophically in the absence of N2. By using 14C-labeled malate, it was found that greater than 95% of this substrate was catabolized completely to CO2 during H2 production. About 60% of this catabolism was associated with H2 biosynthesis, while almost 40% provided reductant for other cellular purposes. Thus, only a small fraction of malate provided carbon skeletons. The addition of ammonium, which inhibited nitrogenase activity, increased substrate conversion into carbon skeletons threefold. Catabolism of malate occurred primarily via the tricarboxylic acid cycle, but gluconeogenesis was also observed. The wild-type organism grew poorly on glucose, accumulated gluconate and 2-keto-3-deoxygluconate, and did not produce H2. More than 50% of metabolized glucose appeared in carbon skeletons or in storage compounds. A glucose-utilizing mutant was five times more effective in utilizing this substrate. This mutant produced H2 from glucose, using 74% of metabolized substrate for this purpose. Glucose converted to storage products or to other carbon skeletons was reduced to 8%. Fixation of CO2 competed directly with H2 production for reducing equivalents and ATP. Refixation of CO2 released from these substrates under H2-producing conditions was, at most, 10 to 12%. Addition of ammonium increased refixation of respired CO2 to 83%. Patterns of carbon flow of fixation products were associated with the particular strains and culture conditions.     

Carbon allocation in wild-type and Glc+ Rhodobacter sphaeroides under photoheterotrophic conditions

The photosynthetic bacterium Rhodobacter sphaeroides is capable of producing H2 via nitrogenase when grown photoheterotrophically in the absence of N2. By using 14C-labeled malate, it was found that greater than 95% of this substrate was catabolized completely to CO2 during H2 production. About 60% of this catabolism was associated with H2 biosynthesis, while almost 40% provided reductant for other cellular purposes. Thus, only a small fraction of malate provided carbon skeletons. The addition of ammonium, which inhibited nitrogenase activity, increased substrate conversion into carbon skeletons threefold. Catabolism of malate occurred primarily via the tricarboxylic acid cycle, but gluconeogenesis was also observed. The wild-type organism grew poorly on glucose, accumulated gluconate and 2-keto-3-deoxygluconate, and did not produce H2. More than 50% of metabolized glucose appeared in carbon skeletons or in storage compounds. A glucose-utilizing mutant was five times more effective in utilizing this substrate. This mutant produced H2 from glucose, using 74% of metabolized substrate for this purpose. Glucose converted to storage products or to other carbon skeletons was reduced to 8%. Fixation of CO2 competed directly with H2 production for reducing equivalents and ATP. Refixation of CO2 released from these substrates under H2-producing conditions was, at most, 10 to 12%. Addition of ammonium increased refixation of respired CO2 to 83%. Patterns of carbon flow of fixation products were associated with the particular strains and culture conditions.     

Paleodemographic age‐at‐death distributions of two Mexican skeletal collections: A comparison of transition analysis and traditional aging methods

Traditional methods of aging adult skeletons suffer from the problem of age mimicry of the reference collection, as described by Bocquet‐Appel and Masset (1982). Transition analysis (Boldsen et al., 2002) is a method of aging adult skeletons that addresses the problem of age mimicry of the reference collection by allowing users to select an appropriate prior probability. In order to evaluate whether transition analysis results in significantly different age estimates for adults, the method was applied to skeletal collections from Postclassic Cholula and Contact‐Period Xochimilco. The resulting age‐at‐death distributions were then compared with age‐at‐death distributions for the two populations constructed using traditional aging methods. Although the traditional aging methods result in age‐at‐death distributions with high young adult mortality and few individuals living past the age of 50, the age‐at‐death distributions constructed using transition analysis indicate that most individuals who lived into adulthood lived past the age of 50. Am J Phys Anthropol 152:67–78, 2013. © 2013 Wiley Periodicals, Inc.     

Uranium in scleractinian coral skeletons

Accurate determinations have been made of the distribution of uranium in fresh and diagenetically altered coral skeletons occurring both naturally and grown under a variety of experimental conditions. Whereas live coral skeletons are homogeneous in uranium distribution, dead skeletons show heterogeneities relating to lithothamnioid algal encrustations and endolithic sponges. In the analyses of over 100 live coral skeletons, no zonal uranium distributions, described by previous workers, were found. In skeletons, free from organic material, uranium was found to exchange readily with the coral skeleton and/or to be precipitated along trabecular axes and skeletal margins. Bioeroded specimens contained higher uranium concentrations than freshly formed aragonite; they were similar to fossil coral skeletons used by previous researchers for uranium scrics dating.     

Design, synthesis, and biochemical evaluation of novel cruzain inhibitors with potential application in the treatment of Chagas' disease

A series of compounds bearing tetrahydronaphthalene, benzophenone, propiophenone, and related rigid molecular skeletons functionalized with thiosemicarbazone or unsaturated carbonyl moieties were prepared by chemical synthesis and evaluated for their ability to inhibit the enzyme cruzain. As potential treatment agents for Chagas' disease, three compounds from the group demonstrate potent inhibition of cruzain with IC(50) values of 17, 24, and 80 nM, respectively.     

Conformation and elasticity of the isolated red blood cell membrane skeleton.

We studied the structure and elasticity of membrane skeletons from human red blood cells (RBCs) during and after extraction of RBC ghosts with nonionic detergent. Optical tweezers were used to suspend individual cells inside a flow chamber, away from all surfaces; this procedure allowed complete exchange of medium while the low-contrast protein network of the skeleton was observed by high resolution, video-enhanced differential interference-contrast (DIC) microscopy. Immediately following extraction in a 5 mM salt buffer, skeletons assumed expanded, nearly spherical shapes that were uncorrelated with the shapes of their parent RBCs. Judging by the extent of thermal undulations and by their deformability in small flow fields, the bending rigidity of skeletons was markedly lower than that of either RBCs or ghosts. No further changes were apparent in skeletons maintained in this buffer for up to 40 min at low temperatures (T less than 10 degrees C), but skeletons shrank when the ionic strength of the buffer was increased. When the salt concentration was raised to 1.5 M, shrinkage remained reversible for approximately 1 min but thereafter became irreversible. When maintained in 1.5 M salt buffer for longer periods, skeletons continued to shrink, lost flexibility, and assumed irregular shapes: this rigidification was irreversible. At this stage, skeletons closely resembled those isolated in standard bulk preparations. We propose that the transformation to the rigid, irreversibly shrunken state is a consequence of spectrin dimer-dimer reconnections and that these structural rearrangements are thermally activated. We also measured the salt-dependent size of fresh and bulk extracted skeletons. Our measurements suggest that, in situ, the spectrin tethers are flexible, with a persistence length of approximately 10 nm at 150 mM salt.     

Occurrence and diversity of lipids in modern coral skeletons

Coral skeletons are composite acellular structures, in which organic macromolecules are intimately associated with mineral phases. Previous studies focussed on proteins and sugars of the soluble organic matrices extracted from the skeletons. Here we report the occurrence of diverse lipids which were extracted from the aragonitic skeletons of seven modern coral species. Using thin layer chromatography, we show that these lipids differ in quantity and composition between the species. Higher proportions of sterols and sterol esters in skeleton extracts as compared to a much higher abundance of waxes and triglycerides in previously studied extracts from scleractinian soft tissues suggest a specific, although not yet determined, role in biomineralisation. The occurrence of intraskeletal lipids along with other organic components should also be taken into account when using coral skeletons as bone allografts, as well as in fossilisation processes.     

Lansing man: a half century later

One of the major fossil man finds from the Plains Area of the United States and one of the few from Kansas are the “Lansing Man” skeletons. The discovery was in February 1902 on the west bank of the Missouri River, south of Leavenworth near the town of Lansing, Kansas. Much was written about this skeleton following its discovery and Ale? Hrdli?ka's only trip to Kansas in October 1902 was to observe the skeletons and the site of its discovery. Numerous articles were written suggesting that “Lansing Man” was many thousands of years old. Geologists could not agree on an age of the skeletons, an adult male and a six to seven year old child, because they were discovered in deposits of slumped loess, confusing the geological picture. Hrdli?ka states that the skeletons were physically identical to Indians of that region at the period of historical contact. William Holmes had the skull sent to the U. S. National Museum and the remaining bones were placed in the Museum of Natural History at the University of Kansas. While on the staff of the University of Kansas, I had Carbon-14 tests conducted on bones from the lower limbs by three separate laboratories. These dates range from 2660 to 5020 B.C. with an average date of four samples (1 each from Geochron Laboratories and the University of Michigan and two from the Smithsonian Institution) of 3579 B.C. This suggests that the “Lansing Man” skeletons are Early Middle Archaic and not Paleoindian. They do, however, represent the oldest known human skeletons from Kansas.     

Enthesopathies (lesions of muscular insertions) as indicators of the activities of neolithic Saharan populations

Enthesopathies are bony lesions involving the sites of insertion of muscles or ligaments. Those caused by hyperactivity of the relevant muscles may be distinguished clearly from those of metabolic or inflammatory origin. Observations from sporting and occupational medicine indicate that specific enthesopathies are correlated with different activities. Examination of the enthesopathies present on two groups of well-preserved neolithic skeletons from separate regions of the Sahara with different paleoenvironments show that overall 20% of the skeletons presented lesions. Three different forms of enthesopathy involved the arm, principally the elbow, and may be tentatively correlated with javelin throwing, wood cutting, and archery. Two types of lesion involving the foot were observed in skeletons from a hunter-gatherer population and may be correlated with much walking or running over hard ground. I suggest that the analysis of such lesions on ancient skeletons may, in concert with other archaeological data, throw light on the activities of ancient people.     

A new aid to aging immature skeletons: development of the occipital bone

A total of 150 immature and young adult skeletons from the medieval necropolis at Mistihalj, in southern Yugoslavia, were aged by the standard methods: dentition, osseous development, and extent of vertebral union. The development of the occipital bone was examined in 117 cases to determine if it could be used in aging the skeletons. The stages of development were found to be regular enough to permit reasonable prediction of age for other Yugoslavian specimens. Comparisons with a series of 20 German fetuses suggest measurements of the parts of the occipital bone can be used to help determine the approximate age of skeletons in the fetal to few-months post-natal range. Comparisons with the ten Egyptian skulls and data on 19 unpublished Eskimo skeletons suggest that the stages of development can be used with other populations.     

Anatomical factors relative to the racial selectivity of femoral neck fracture

A comparative racial study of 200 femora from 50 American White and 50 American Negro female skeletons was carried out to determine whether any anatomical differences in femoral from exist between these groups which might account for the racial selectivity of hip fracture, Significant racial differences were found in neck-shaft angle, angle of inclination and oblique length. Negro females have longer femora, larger neck-shaft angles and a smaller angle of inclination than have White females. These differences in femoral morphology may, in some measure, contribute to the greater incidence of hip fracture in female Whites.     

Skeletal growth of children from the Iron Age site at K2 (South Africa)

Cross-sectional growth data were obtained from the skeletal remains of children from the Iron Age site of K2 near the Limpopo River. Standard measurements of the diaphyseal lengths of the long bones from both limbs were recorded and compared to published skeletal data. For this purpose, data on Eskimo and Aleut skeletons, Libben skeletons, and skeletons from Indian Knoll and Altenerding were used. An attempt to study growth allometrically was made. K2 children were growing as well as children from these other groups. Comparison of data for K2 children with those on living South African “Cape Coloured” rural children, studied during the late 1980s, shows the similarity of growth of both groups. © 1996 Wiley-Liss, Inc.     

Ultrastructure of the intact skeleton of the human erythrocyte membrane

Filamentous skeletons were liberated from isolated human erythrocyte membranes in Triton X-100, spread on fenestrated carbon films, negatively stained, and viewed intact and unfixed in the transmission electron microscope. Two forms of the skeleton were examined: (a) basic skeletons, stripped of accessory proteins with 1.5 M NaCl so that they contain predominantly polypeptide bands 1, 2, 4.1, and 5; and (b) unstripped skeletons, which also bore accessory proteins such as ankyrin and band 3 and small plaques of residual lipid. Freshly prepared skeletons were highly condensed. Incubation at low ionic strength and in the presence of dithiothreitol for an hour or more caused an expansion of the skeletons, which greatly increased the visibility of their elements. The expansion may reflect the opening of spectrin from a compact to an elongated disposition. Expanded skeletons appeared to be organized as networks of short actin filaments joined by multiple (5-8) spectrin tetramers. In unstripped preparations, globular masses were observed near the centers of the spectrin filaments, probably corresponding to complexes of ankyrin with band 3 oligomers. Some of these globules linked pairs of spectrin filaments. Skeletons prepared with a minimum of perturbation had thickened actin protofilaments, presumably reflecting the presence of accessory proteins. The length of these actin filaments was highly uniform, averaging 33 +/- 5 nm. This is the length of nonmuscle tropomyosin. Since there is almost enough tropomyosin present to saturate the F-actin, our data support the hypothesis that tropomyosin may determine the length of actin protofilaments in the red cell membrane.     

Microscopy electron scanning of fossilized sickle-cells

In a microscopica electronic scanning follow-up study on human skeletons from the Hellenistic Period in the Arab-Persian Gulf, fossilized sickle-cells were found in the bone marrow of one of the excavated skeletons. The ultrastructure of these cells was compared to that of fossilized normal red blood cells of other skeletons from the same site, and to similar pseudo-pathological structures. The finding of fossilized evidence of sickle-cell anemia of that date is withoutprecedent, and makes an evaluation of related gross-anatomical skeletal changes possible.     

Ether Lipids of Planktonic Archaea in the Marine Water Column

Acyclic and cyclic biphytanes derived from the membrane ether lipids of archaea were found in water column particulate and sedimentary organic matter from several oxic and anoxic marine environments. Compound-specific isotope analyses of the carbon skeletons suggest that planktonic archaea utilize an isotopically heavy carbon source such as algal carbohydrates and proteins or dissolved bicarbonate. Due to their high preservation potential, these lipids provide a fossil record of planktonic archaea and suggest that they have thrived in marine environments for more than 50 million years.