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19. The Winchcombe meteorite, a unique and pristine witness from the outer solar system

Author

King, A.J., Daly, L., Rowe, J., Joy, K.H., Greenwood, R.C., Devillepoix, Hadrien, Suttle, M.D., Chan, Q.H.S., Russell, S.S., Bates, H.C., Bryson, J.F.J., Clay, P.L., Vida, D., Lee, M.R., O’Brien, Á., Hallis, L.J., Stephen, N.R., Tartèse, R., Sansom, Ellie, Towner, Martin, Cupak, Martin, Shober, P.M., Bland, Phil, Findlay, R., Franchi, I.A., Verchovsky, A.B., Abernethy, F.A.J., Grady, M.M., Floyd, C.J., Van Ginneken, M., Bridges, J., Hicks, L.J., Jones, R.H., Mitchell, J.T., Genge, M.J., Jenkins, L., Martin, P.E., Sephton, M.A., Watson, J.S., Salge, T., Shirley, K.A., Curtis, R.J., Warren, T.J., Bowles, N.E., Stuart, F.M., Nicola, L.D., Györe, D., Boyce, A.J., Shaw, K.M.M., Elliott, T., Steele, R.C.J., Povinec, P., Laubenstein, M., Sanderson, D., Cresswell, A., Jull, A.J.T., Sýkora, I., Sridhar, S., Harrison, R.J., Willcocks, F.M., Harrison, C.S., Hallatt, D., Wozniakiewicz, P.J., Burchell, M.J., Alesbrook, L.S., Dignam, A., Almeida, N.V., Smith, C.L., Clark, B., Humphreys-Williams, E.R., Schofield, P.F., Cornwell, L.T., Spathis, V., Morgan, G.H., Perkins, M.J., Kacerek, R., Campbell-Burns, P., Colas, F., Zanda, B., Vernazza, P., Bouley, S., Jeanne, S., Hankey, M., Collins, G.S., Young, J.S., Shaw, C., Horak, J., Jones, D., James, N., Bosley, S., Shuttleworth, A., Dickinson, P., McMullan, I., Robson, D., Smedley, A.R.D., Stanley, B., Bassom, R., McIntyre, M., Suttle, A.A., Fleet, R., King, A.J., Daly, L., Rowe, J., Joy, K.H., Greenwood, R.C., Devillepoix, Hadrien, Suttle, M.D., Chan, Q.H.S., Russell, S.S., Bates, H.C., Bryson, J.F.J., Clay, P.L., Vida, D., Lee, M.R., O’Brien, Á., Hallis, L.J., Stephen, N.R., Tartèse, R., Sansom, Ellie, Towner, Martin, Cupak, Martin, Shober, P.M., Bland, Phil, Findlay, R., Franchi, I.A., Verchovsky, A.B., Abernethy, F.A.J., Grady, M.M., Floyd, C.J., Van Ginneken, M., Bridges, J., Hicks, L.J., Jones, R.H., Mitchell, J.T., Genge, M.J., Jenkins, L., Martin, P.E., Sephton, M.A., Watson, J.S., Salge, T., Shirley, K.A., Curtis, R.J., Warren, T.J., Bowles, N.E., Stuart, F.M., Nicola, L.D., Györe, D., Boyce, A.J., Shaw, K.M.M., Elliott, T., Steele, R.C.J., Povinec, P., Laubenstein, M., Sanderson, D., Cresswell, A., Jull, A.J.T., Sýkora, I., Sridhar, S., Harrison, R.J., Willcocks, F.M., Harrison, C.S., Hallatt, D., Wozniakiewicz, P.J., Burchell, M.J., Alesbrook, L.S., Dignam, A., Almeida, N.V., Smith, C.L., Clark, B., Humphreys-Williams, E.R., Schofield, P.F., Cornwell, L.T., Spathis, V., Morgan, G.H., Perkins, M.J., Kacerek, R., Campbell-Burns, P., Colas, F., Zanda, B., Vernazza, P., Bouley, S., Jeanne, S., Hankey, M., Collins, G.S., Young, J.S., Shaw, C., Horak, J., Jones, D., James, N., Bosley, S., Shuttleworth, A., Dickinson, P., McMullan, I., Robson, D., Smedley, A.R.D., Stanley, B., Bassom, R., McIntyre, M., Suttle, A.A., and Fleet, R.

Abstract

Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth’s water.

Published
2022

22. Neoproterozoic copper cycling, and the rise of metazoans

Author

Parnell, J. and Boyce, A.J.

Subjects
Oxygen, Atmosphere, Earth, Planet, lcsh:R, Animals, Paleontology, lcsh:Medicine, lcsh:Q, lcsh:Science, Article, Copper
Abstract

The rise of animal life is temporally related to the increased availability of oxygen in the hydrosphere and atmosphere during the Neoproterozoic. However, the earliest metazoans probably needed relatively low oxygen concentrations, suggesting additional environmental and/or biochemical developments were involved. Copper was required in the exploitation of oxygen by the evolving animals, through the development of respiratory proteins and the extracellular matrix required for structural support. We synthesize global data demonstrating a marked enrichment of copper in the Earth’s crust that coincided with the biological use of oxygen, and this new biological use of copper. The copper enrichment was likely recycled into the surface environment by weathering of basalt and other magmatic rocks, at copper liberation rates up to 300 times that of typical granitic terrain. The weathering of basalts also triggered the Sturtian glaciation, which accelerated erosion. We postulate that the coincidence of a high availability of copper, along with increased oxygen levels, for the first time during the Neoproterozoic supported the critical advances of respiration and structural support in evolving animals.

Published
2019

23. Forming an economic bentonite resource in a volcanic arc environment: timescales, fluids and thermal drivers.

Author

Miles A.J., Barfod D.N., Boyce A.J., Kemp S.J., Naden J., Tapster S.R., Miles A.J., Barfod D.N., Boyce A.J., Kemp S.J., Naden J., and Tapster S.R.

Abstract

This study identifies new key parameters that have resulted in the formation of an economic-scale bentonite resource on the emergent island of Milos. It is concluded that in an emergent volcanic arc setting, the hydrology needed to form a bentonite deposit is not constrained to the marine environment and can be connected to emergent parts of the volcanic edifice. High-precision geochronology indicates bentonite development happens on volcanic timescales (10-100 kyrs.) A cumulative volcanic and sub-volcanic pile coeval with the formation of bentonite suggests that multiple magmatic episodes over narrow timeframes provide and sustain the thermal driver for significant bentonite development., This study identifies new key parameters that have resulted in the formation of an economic-scale bentonite resource on the emergent island of Milos. It is concluded that in an emergent volcanic arc setting, the hydrology needed to form a bentonite deposit is not constrained to the marine environment and can be connected to emergent parts of the volcanic edifice. High-precision geochronology indicates bentonite development happens on volcanic timescales (10-100 kyrs.) A cumulative volcanic and sub-volcanic pile coeval with the formation of bentonite suggests that multiple magmatic episodes over narrow timeframes provide and sustain the thermal driver for significant bentonite development.

Published
2021

25. Exhumation of an active magmatic-hydrothermal system in a resurgent caldera environment: the example of Ischia (Italy)

Author

Sbrana, A., Fulignati, P., Marianelli, P., Boyce, A.J., and Cecchetti, A.

Subjects
Ischia, Italy -- Natural history, Calderas -- Structure, Hydrothermal systems (Geology) -- Structure, Rocks, Igneous -- Inclusions, Rocks, Igneous -- Environmental aspects, Earth sciences
Abstract

Ischia is a rare case of a well-exposed caldera system that has experienced rapid recent resurgence, which can be used to dissect the anatomy of an otherwise inaccessible active hydrothermal system developed in a caldera-forming environment. Integrated analyses of melt and fluid inclusions, mineralogy and stable isotopic compositions of pumices, tufts and syenitic xenoliths of the Ischia volcanic system provide strong physico-chemical constraints on the shallow magmatic reservoir and the hydrothermal system. The hydrothermal system has been exposed by the rapid uplift of the Mt. Epomeo resurgent block. The engine of the hydrothermal system of Ischia can be identified in the shallow magmatic system (at around 2 km depth) that hosts hot (c. 1000[degrees]C) trachytic magma. The hydrothermal system developed principally within thick intracaldera ignimbrite deposits, and extended to a depth of at least 1 km, defining a series of facies characterized by associations of alteration mineral assemblages typical of a seawater-dominated high-temperature geothermal system. Supplementary material: Sample descriptions and analytical methods are available at http://www.geolsoc.org.uk/SUP18371. doi: 10.1144/0016-76492009-030.

Published
2009

26. Temporal variation in phenetic affinity of early upper Egyptian male cranial series

Author

Keita, S.O.Y. and Boyce, A.J.

Subjects
Periodization (Social Sciences) -- Usage -- Research, Skull -- Identification and classification -- Properties -- Research -- Usage, Biological sciences, Identification and classification, Usage, Research, Properties
Abstract

We carried out an exploratory historical biology study using temporally distinguished groups of predynastic-Early Dynastic male crania from the region of Upper Egypt. The objectives were, first, to determine the overall pattern of phenetic affinity between temporally sequential series and in relation to the earliest series and, second, to explore the possible meanings of the pattern of relationship to sociohistorical change. The cranial series were designated early predynastic, late predynastic, terminal predynastic, and Dynasty I. Craniometric phenetic affinity was ascertained using Mahalanobis distances; a 5% level of probability was chosen for significance. The distance matrix values were ordered into hierarchies of dissimilarity from each series (distance hierarchies) and tabulated for time-successive groups, including the temporally earliest series (i.e., serialized by time). The principal observations were as follows. The overall pattern was not one in which the values between all series were statistically insignificant; nor was it one of consistent sequential increase of biological distance from the earliest series. There was a notable and statistically significant distance between the early and late predynastic groups, with the late and terminal predynastic groups mutually having the lowest and statistically insignificant distances with each other. The value between the terminal predynastic and Dynasty I series was generally larger than the values between other groups and was statistically significant. The overall pattern is possibly consistent with archeological interpretations that postulate increasing intraregional interactions during the late and terminal predynastic periods and the rise of an Egyptian state that eventually included northern Egypt. KEY WORDS: CRANIOFACIAL VARIATION, MAHALANOBIS DISTANCES, EGYPT, AFRO-ASIATIC LANGUAGES., We present the results of a study of Upper Egyptian male crania from the predynastic through the beginning of the dynastic period (about 4400?-3050 B.C.). Upper Egypt was the site [...]

Published
2008

27. Magmatic fluids implicated in the formation of propylitic alteration: oxygen, hydrogen, and strontium isotope constraints from the Northparkes porphyry Cu-Au District, New South Wales, Australia

Author

Pacey A., Boyce A.J., Millar I.L., Wilkinson J.J., Pacey A., Boyce A.J., Millar I.L., and Wilkinson J.J.

Abstract

Studies have been carried out of the oxygen and hydrogen isotope compositions of propylitic mineral separates (epidote, chlorite, and quartz), selected potassic mineral separates (quartz and magnetite), and quartz-hosted fluid inclusions from around the E48 and E26 deposits in the Northparkes porphyry Cu-Au district, New South Wales, Australia. The strontium isotope composition of epidote was also determined to test for the potential contribution of seawater in the Northparkes system given the postulated island-arc setting and submarine character of some country rocks. The results suggest that warming and equilibrating meteoric water alone cannot have generated the observed fluid characteristics and was not solely responsible for propylitic alteration. Rather, fluids containing a magmatic component must have been present throughout much of the propylitic halo, to distances of at least 1.6 km from the E48 deposit. The most likely scenario is one involving expulsion, cooling, and equilibration of magmatic fluid up to around 3 km from the porphyry system, beyond which a mixing interface with external meteoric waters developed. It is concluded that ore formation was purely an orthomagmatic process driven by thermal and chemical gradients around the quartz monzonite porphyry intrusions., Studies have been carried out of the oxygen and hydrogen isotope compositions of propylitic mineral separates (epidote, chlorite, and quartz), selected potassic mineral separates (quartz and magnetite), and quartz-hosted fluid inclusions from around the E48 and E26 deposits in the Northparkes porphyry Cu-Au district, New South Wales, Australia. The strontium isotope composition of epidote was also determined to test for the potential contribution of seawater in the Northparkes system given the postulated island-arc setting and submarine character of some country rocks. The results suggest that warming and equilibrating meteoric water alone cannot have generated the observed fluid characteristics and was not solely responsible for propylitic alteration. Rather, fluids containing a magmatic component must have been present throughout much of the propylitic halo, to distances of at least 1.6 km from the E48 deposit. The most likely scenario is one involving expulsion, cooling, and equilibration of magmatic fluid up to around 3 km from the porphyry system, beyond which a mixing interface with external meteoric waters developed. It is concluded that ore formation was purely an orthomagmatic process driven by thermal and chemical gradients around the quartz monzonite porphyry intrusions.

Published
2020

28. Stable C, O, and S isotope record of magmatic-hydrothermal interactions between the Faleme Fe skarn and the Loulo Au systems in western Mali

Author

Lambert-Smith J.S., Allibone A., Boyce A.J., Fanning M., Lawrence D.M., Treloar P.J., Lambert-Smith J.S., Allibone A., Boyce A.J., Fanning M., Lawrence D.M., and Treloar P.J.

Abstract

New delta13C, delta18O, and delta34S data from the Karakaene Ndi skarn, Au occurrences along the western margin of the Kofi series, and zircons within plutonic rocks of the Faleme batholith are combined with existing data from the Loulo Au deposits to model the contribution of magmatic volatiles to Au mineralisation. Comparison of the C and O isotope data with water-rock reaction models indicates the Loulo Au deposits formed primarily through unmixing of an aqueous carbonic fluid derived from the devolatilisation of sedimentary rocks with an organic carbon component. Isotopic data suggest the presence of a hypersaline brine that enhanced this phase separation including components derived from both Kofi series evaporite horizons interlayered with the dolostones and a magmatic-hydrothermal brine. This magmatic-hydrothermal component is particularly apparent in O, C, and S isotope data from the Gara deposit and Au prospects immediately adjacent to the Faleme batholith. It is concluded that there was a critical role for magmatism in the development of early alteration assemblages in the Loulo district, in the genesis of the Faleme iron skarns, and in those Au deposits that formed in response to fluid mixing., New delta13C, delta18O, and delta34S data from the Karakaene Ndi skarn, Au occurrences along the western margin of the Kofi series, and zircons within plutonic rocks of the Faleme batholith are combined with existing data from the Loulo Au deposits to model the contribution of magmatic volatiles to Au mineralisation. Comparison of the C and O isotope data with water-rock reaction models indicates the Loulo Au deposits formed primarily through unmixing of an aqueous carbonic fluid derived from the devolatilisation of sedimentary rocks with an organic carbon component. Isotopic data suggest the presence of a hypersaline brine that enhanced this phase separation including components derived from both Kofi series evaporite horizons interlayered with the dolostones and a magmatic-hydrothermal brine. This magmatic-hydrothermal component is particularly apparent in O, C, and S isotope data from the Gara deposit and Au prospects immediately adjacent to the Faleme batholith. It is concluded that there was a critical role for magmatism in the development of early alteration assemblages in the Loulo district, in the genesis of the Faleme iron skarns, and in those Au deposits that formed in response to fluid mixing.

Published
2020

29. Variation in porotic hyperostosis in the Royal Cemetery complex at Abydos, Upper Egypt: a social interpretation

Author

Keita, S.O.Y. and Boyce, A.J.

Subjects
Biological research -- Analysis -- Research, Biology, Experimental -- Analysis -- Research, Paleoanthropology -- Research -- Analysis, Anthropology/archeology/folklore, Analysis, Research
Abstract

Variation in the frequency and severity of porotic hyperostosis [porous defects], seen in the skulls of individuals buried at two First Dynasty cemeteries at Abydos, suggested differences in health and social conditions. Those buried near the kings had suffered from childhood deficiencies, while those associated with funerary enclosures in a second cemetery further to the north seemed to have benefited from occupational or social advantages. The author speculates on the possible factors which gave rise to this difference. Keywords: First Dynasty, Egypt, Abydos, cemetery, porotic hyperostosis, Introduction This paper presents the results of a palaeopathological study of skeletal remains from the high status cemetery of Abydos in Upper Egypt associated with the rulers of the First [...]

Published
2006

30. Intracratonic crustal seawater circulation and the genesis of subseafloor zinc-lead mineralization in the Irish orefield

Author

Wilkinson, J.J., Everett, C.E., Boyce, A.J., Gleeson, S.A., and Rye, D.M.

Subjects
Sea-water -- Research, Geology -- Research, Earth -- Crust, Earth -- Research, Earth sciences
Abstract

We have determined the chemical composition of ~350-m.y.-old solutions extracted from fluid inclusions, and strontium isotopic compositions of hydrothermal minerals from the Irish zinc-lead orefield. These data show that ore-forming fluids were derived from evaporated seawater and acquired metals by deep circulation within fractures in continental crust. Mineralization occurred in the near-seafloor environment when these solutions returned to the surface via thermohaline convection and mixed with brines rich in [H.sub.2]S produced by bacterial reduction of seawater sulfate. The results indicate that deep penetration of seawater or evaporated seawater into the continental crust can occur in rift zones or extending passive margins and that this process can generate large volumes of base metal ore-forming solutions. Our results are inconsistent with topographic flow models for mineralization in the district, and support deep convection models for ore formation. The widespread development of evaporitic brines on the Laurussian continental margin under late Paleozoic greenhouse conditions is likely to have been critical for generating numerous accumulations of base metals in sedimentary basins at this time. Keywords: seawater, zinc, mineralization, crust, Ireland, brine.

Published
2005

31. Contrasting evolution of hydrothermal fluids in the PACMANUS system, Manus Basin: the Sr and S isotope evidence

Author

Roberts, S., Bach, W., Binns, R.A., Vanko, D.A., Yeats, C.J., Teagle, D.A.H., Blacklock, K, Blusztajn, J.S., Boyce, A.J., Cooper, M.J., Holland, N., and McDonald, B.

Subjects
Hydrothermal vents -- Research, Hydrothermal fluids, Earth sciences
Abstract

Ocean Drilling Program (ODP) Leg 193 investigated two sites of hydrothermal activity along the crest of the Pual Ridge in the eastern Manus Basin. A site of low-temperature diffuse venting, Snowcap (Site 1188), and a high-temperature black smoker site, Roman Ruins (Site 1189), were drilled to depths of 386 and 206 m below seafloor (mbsf), respectively. Although the two sites are Keywords: hydrothermal vents, sulfides, anhydrite, isotopes.

Published
2003

32. Diachronic patterns of dental hypoplasias and vault porosities during the predynastic in the Naqada region, Upper Egypt

Author

Keita, S.O.Y. and Boyce, A.J.

Subjects
Paleopathology -- Egypt, Enamel, Dental -- Abnormalities, Skull -- Abnormalities, Biological sciences
Abstract

A diachronic decline in stress markers was found in a study of predynastic remains from the Naqada region of Upper Egypt. Dental hypoplasias and porotic hyperostosis were examined in samples representing a period when population density and social complexity were increasing and Nile flooding was decreasing.

Published
2001

33. 'Race': confusion about zoological and social taxonomies and their places in science

Author

Keita, S.O.Y. and Boyce, A.J.

Subjects
Race -- Analysis, Zoology -- Identification and classification, Human biology -- Analysis, Biological sciences
Abstract

Use of the term 'race' is discussed in response to arguments made by B. Bogin and C. Bouchard et al. The concept of race in human biology is considered in relation to the notion of subspecies in zoology.

Published
2001

36. Generation of the Mt Kinabalu granite by crustal contamination of intraplate magma modelled by Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC)

Author

Burton-Johnson, A., Macpherson, C.G., Ottley, C.J., Nowell, G.M., Boyce, A.J., Burton-Johnson, A., Macpherson, C.G., Ottley, C.J., Nowell, G.M., and Boyce, A.J.

Abstract

New geochemical data are presented for the composite units of the Mount Kinabalu granitoid intrusion of Borneo and explore discrimination between crustal- and mantlederived granitic magmas. The geochemical data demonstrate that the units making up this composite intrusion became more potassic through time. This was accompanied by an evolution of isotope ratios from a continental-affinity towards a slightly more mantle-affinity (87Sr/86Sri ~0.7078; 143Nd/144Ndi ~0.51245; 206Pb/204Pbi ~18.756 for the oldest unit compared to 87Sr/86Sri ~0.7065, 143Nd/144Ndi ~0.51250 and 206Pb/204Pbi ~18.721 for the younger units). Oxygen isotope ratios (calculated whole-rock δ18O of +6.5–9.3‰) do not show a clear trend with time. The isotopic data indicate that the magma cannot result only from fractional crystallisation of a mantle-derived magma. Alkali metal compositions show that crustal anatexis is also an unsuitable process for genesis of the intrusion. The data indicate that the high-K units were generated by fractional crystallisation of a primary, mafic magma, followed by assimilation of the partially melted sedimentary overburden. We present a new, Equilibrated Major Element – Assimilation with Fractional Crystallisation (EME-AFC) approach for simultaneously modelling the major element, trace element, and radiogenic and oxygen isotope compositions during such magmatic differentiation; addressing the lack of current AFC modelling approaches for felsic, amphibole- or biotite-bearing systems. We propose that Mt Kinabalu was generated through low degree melting of upwelling fertile metasomatised mantle driven by regional crustal extension in the Late Miocene.

Published
2019

37. A Devonian auriferous hot spring system, Rhynie, Scotland

Author

Rice, C.M., Ashcroft, W.A., Batten, D.J., Boyce, A.J., Caulfield, J.B.D., Fallick, A.E., Hole, M.J., Jones, E., Pearson, M.J., Rogers, G., Saxton, J.M., Stuart, F.M., Trewin, N.H., and Turner, G.

Subjects
Scotland -- Natural history, Geology, Stratigraphic -- Devonian, Hot springs -- Research, Sedimentary basins -- Research, Chert -- Analysis, Hydrothermal deposits -- Analysis, Earth sciences
Abstract

The Early Devonian Rhynie hot spring system is the oldest known and is of the low sulphidation type. It extends for at least 1.5 km along a major fault zone defining the western margin of an outlier of fluvial and lacustrine sediments, plant-bearing sinters and andesitic lavas. The age of sedimentation and hydrothermal activity has been determined by palynological (Pragian) and radiometric (396 [+ or -] 12 Ma) techniques. The outlier is a half graben with a complex stepped western margin. The Devonian rocks show intense hydrothermal alteration along the fault zone. The main alteration minerals are quartz, K-feldspar, calcite, hematite and illitic and chloritic clays. Multiple chert veining and brecciation are widely developed, and geyserite and vent material are also present. Pyrite occurs in veins and all alteration facies. Sinters and altered rocks contain high concentrations of Au, As, Sb, Hg, W and Mo. Gold occurs in arsenian pyrite and as sub-micron particles in oxidized rocks. The fluid(s) responsible for most hydrothermal alteration were near neutral with low sulphur and oxygen activities and dominated by meteoric water. However, incursions of high temperature (300-440 [degrees] C) magmatic fluids occurred with [Delta]D -65[per thousand] and [Delta]18O around +8.5[per thousand]. [Delta]34S (pyrite) and initial 87Sr/86Sr ratios. (vein calcite) lie mainly within the ranges +3.4[per thousand] to +8.5[per thousand] and 0.71138 to 0.71402 respectively. These data indicate that late Proterozoic Dalradian metasediments are a likely source for S and Sr but other sources are possible. [Delta]13C values for caliche and vein calcite imply derivation of carbon from non-organic sources. The Rhynie cherts were deposited from a low salinity fluid of probable meteoric origin ([Delta]18[O.sub.chert] +13.1[per thousand] to +16.5[per thousand]) which had interacted with the basement rocks and sediments (high Xe/Ar, Br/Cl and I/Cl ratios). Plant-bearing chert yielded an 40Ar/39Ar ratio (292.1 [+ or -] 0.6) significantly less than that of modern air and may be the first valid determination of a sample of ancient atmosphere. Keywords: Hot springs, Devonian, Scotland, isotopes.

Published
1995

38. Molecular and population genetic analysis of allelic sequence diversity at the human beta-globin locus

Author

Fullerton, S.M., Harding, R.M., Boyce, A.J., and Clegg, J.B.

Subjects
Genetic polymorphisms -- Observations, Science and technology
Abstract

An analysis of 36 Melanesians provided an insight into allelic sequence polymorphism at the beta-globin locus. Haplotype associations are evident in connected polymorphisms. Recombination and gene conversion may be responsible for the haplotype diversity. An average age of sequence divergence of around 450,000 years is evident.

Published
1994

39. A computer simulation study of VNTR population genetics: constrained recombination rules out the infinite alleles model

Author

Harding, Rosalind M., Boyce, A.J., Martinson, J.J., Flint, J., and Clegg, J.B.

Subjects
Genetic recombination -- Research, Computer simulation -- Usage, Population genetics -- Models, Proteins -- Analysis, Biological sciences
Abstract

A computer simulation model proposed for the genesis of a locus of variable numbers of tandern repeats (VNTRs) facilitated the analyses of additional rates as well as distinct constraints of recombination. The analyses, confined to population genetics of VNTRs, hypothesize the neutrality of VNTRs and the initial evanescence of VNTR polymorphism. The validation of the intrinsically poor fit to the infinite alleles models of simulated VNTR variations and estimated VNTR polymorphism derivatives of two Papua New Guinean populations.

Published
1993

40. The evolution of tandemly repetitive DNA: recombination rules

Author

Harding, Rosalind M., Boyce, A.J., and Clegg, J.B.

Subjects
DNA, Genetic recombination -- Research, Biological sciences
Abstract

A model describing the evolutionary persistence of single tandemly repetitive DNA (TR-DNA) is analyzed. The study assumes that variable numbers of tandem repeats (VNTRs) can be grouped with satellite DNAs to create a class of TR-DNA. The evolutionary process is likewise assumed to flow from an unbiased recombinational process. Results show that misalignment constraint generates VNTR loci evolution including minisatellites. The results support nonrandom VNTR and other TR-DNA distributions in the human genome.

Published
1992

42. Geochemistry and metallogeny of Neoproterozoic pyrite in oxic and anoxic sediments

Author

Parnell, J., Perez, M., Armstrong, J., Bullock, L., Feldmann, J., and Boyce, A.J.

Abstract

The Neoproterozoic Dalradian Supergroup contains widespread diagenetic sulphides present as pyrite. The sulphides occur in both carbonaceous shales and glacial diamictites, that were deposited in relatively reducing and oxidising conditions respectively. The trace element compositions of the pyrite, and consequently the whole rock compositions, contrast between the two lithologies. The highest concentrations of selenium, tellurium and gold are all found in diamictite-hosted pyrite. The data suggest that increased mobility of these elements in oxidising conditions led to greater uptake when pyrite was precipitated. As one model for the formation of orogenic gold ore deposits assumes a sulphide-rich protolith, pyrite ultimately formed during relatively oxidising conditions could make a contribution, including the widespread pyrite precipitated during the Neoproterozoic ‘Snowball Earth’ glaciations.

Published
2018

46. Coordinated repression of BIM and PUMA by Epstein-Barr virus latent genes maintains the survival of Burkitt lymphoma cells

Author

Fitzsimmons, L., Boyce, A.J., Wei, W., Chang, C., Croom-Carter, D., Tierney, R.J., Herold, M.J., Bell, A.I., Strasser, A., Kelly, G.L., and Rowe, M.

Subjects
hemic and lymphatic diseases
Abstract

While the association of Epstein-Barr virus (EBV) with Burkitt lymphoma (BL) has long been recognised, the precise role of the virus in BL pathogenesis is not fully resolved. EBV can be lost spontaneously from some BL cell lines, and these EBV-loss lymphoma cells reportedly have a survival disadvantage. Here we have generated an extensive panel of EBV-loss clones from multiple BL backgrounds and examined their phenotype comparing them to their isogenic EBV-positive counterparts. We report that, while loss of EBV from BL cells is rare, it is consistently associated with an enhanced predisposition to undergo apoptosis and reduced tumorigenicity in vivo. Importantly, reinfection of EBV-loss clones with EBV, but surprisingly not transduction with individual BL-associated latent viral genes, restored protection from apoptosis. Expression profiling and functional analysis of apoptosis-related proteins and transcripts in BL cells revealed that EBV inhibits the upregulation of the proapoptotic BH3-only proteins, BIM and PUMA. We conclude that latent EBV genes cooperatively enhance the survival of BL cells by suppression of the intrinsic apoptosis pathway signalling via inhibition of the potent apoptosis initiators, BIM and PUMA.Cell Death and Differentiation advance online publication, 29 September 2017; doi:10.1038/cdd.2017.150.

Published
2017

50. Multi-decadal accumulation of anthropogenic and remineralized dissolved inorganic carbon at the Extended Ellett Line in the northeast Atlantic Ocean

Author

Humphreys, M.P., Griffiths, A.M., Achterberg, E.P., Holliday, N.P., Rérolle, V.M.C., Barraqueta, J-L.M., Couldrey, M.P., Oliver, K.I.C., Hartman, S.E., Esposito, M., and Boyce, A.J.

Abstract

Marine carbonate chemistry measurements have been carried out annually since 2009 during UK research cruises along the Extended Ellett Line (EEL), a hydrographic transect in the northeast Atlantic Ocean. The EEL intersects several water masses that are key to the global thermohaline circulation, and therefore the cruises sample a region in which it is critical to monitor secular physical and biogeochemical changes. We have combined results from these EEL cruises with existing quality-controlled observational data syntheses to produce a hydrographic time-series for the EEL from 1981 to 2013. This reveals multi-decadal increases in dissolved inorganic carbon (DIC) throughout the water column, with a near-surface maximum rate of 1.80 ± 0.45 µmol kg-1 yr-1. Anthropogenic CO2 accumulation was assessed, using simultaneous changes in apparent oxygen utilization (AOU) and total alkalinity (TA) as proxies for the biogeochemical processes that influence DIC. The stable carbon isotope composition of DIC (δ13CDIC) was also determined, and used as an independent test of our method. We calculated a volume-integrated anthropogenic CO2 accumulation rate of 2.8 ± 0.4 mg-C m-3 yr-1 along the EEL, which is about double the global mean. The anthropogenic CO2 component accounts for only 31 ± 6 % of the total DIC increase. The remainder is derived from increased organic matter remineralization, which we attribute to the lateral redistribution of water masses that accompanies subpolar gyre contraction. Output from a general circulation-ecosystem model demonstrates that spatiotemporal heterogeneity in the observations has not significantly biased our multi-decadal rate-of-change calculations, and indicates that the EEL observations have been tracking distal changes in the surrounding North Atlantic and Nordic Seas.

Published
2016

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