Stratigraphy and Carbonate Petrology of the Pennsylvanian Upper Canyon Group in Stephens and Palo Pinto Counties, Texas

The strata of Pennsylvanian age in north-central Texas dip gently and uniformly to the northwest. They are subdivided, in ascending order, into the Strawn, Canyon and Cisco Groups. The study area was limited to the upper part of the Canyon Group in Stephens and Palo Pinto counties. Four formations were mapped and the petrology described; they are, in ascending order, the Placid Shale, Ranger Limestone, Colony Creek Shale and Home Creek Limestone; also mapped were outliers of the Trinity Group (Cretaceous). All the formations show lateral and vertical lithologic changes; therefore detailed field tracing was necessary to insure accurate stratigraphic correlations. A detailed petrographic study of the carbonates showed that the limestones are composed almost entirely of comminuted organic material and have undergone little recrystallization. Much of the original sediment was mechanically deposited, and most lateral and vertical lithologic changes are believed to be related to variations in the physical environment. The limestone members are not characterized by a single rock type, but are divisible into distinct lithologies that generally can be traced throughout the area. The units vary from calcilutites to limestone conglomerates and appear to occur in rhythmic vertical succession

Environmental factors influencing the distribution of Barbatia domingensis (Mollusca, Bivalvia) on the Bermuda Platform

Eight localities, representing four generalized environments, were sampled to determine the environmental relations of the small, byssally attached arcid bivalve Barbalia (Acar) domingensis on the Bermuda Platform. The species was most abundant in turbulent environments and least abundant in the protected bays and sounds. It usually attaches to the underside of corals; occasionally it is found attached to rocks. The principal limiting factor on the distribution of the species appears to be the availability of suitable coral substrata for attachment

Notes on the History and Philosophy of Science: 2. Barker on Simplicity in Historical Geology

In the literature of the philosophy of science the principle of simplicity is usually analyzed by reference to examples taken from mathematics and the abstract physical sciences. Thus Mario Bunge, in the Panel Discussion of Simplicity of Scientific Theories, which was conducted at the 1960 meetings of the American Association for the Advancement of Science in New York City, chose four of his six basic examples from physics and astrophysics. These were the Copernican and Ptolemaic theories, the gravitational theory of Einstein and others, the beta-decay theory, and Newton\u27s and Hamilton\u27s formulation of dynamics. At this same symposium, however, Stephen Barker broke with tradition and selected a geological example upon which to base his analysis of simplicity

A Preliminary Report on the Pennsylvanian Canyon Carbonates in North Central Texas

The Canyon Group comprises an alternating sequence of limestone and shale formations, with sandstone members being common in the shales. The entire succession is crudely cyclic. Within the thickest limestone formation, the Winchell, detailed petrographic studies have shown the existence of regular vertical changes in texture. Three textural units occur, each commencing with arenitic textures at the base and grading upward to lutitic textures in the upper portion. These have been traced over several units and are believed to be referrable to regular changes in the depositional interface of the Winchell Bank with respect to energy base

Constraining functional hypotheses: controls on the morphology of the concavo-convex brachiopod Rafinesquina

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72447/1/j.1502-3931.1998.tb00519.x.pd

Common ataxia telangiectasia mutated haplotypes and risk of breast cancer: a nested case–control study

INTRODUCTION: The ataxia telangiectasia mutated (ATM) gene is a tumor suppressor gene with functions in cell cycle arrest, apoptosis, and repair of DNA double-strand breaks. Based on family studies, women heterozygous for mutations in the ATM gene are reported to have a fourfold to fivefold increased risk of breast cancer compared with noncarriers of the mutations, although not all studies have confirmed this association. Haplotype analysis has been suggested as an efficient method for investigating the role of common variation in the ATM gene and breast cancer. Five biallelic haplotype tagging single nucleotide polymorphisms are estimated to capture 99% of the haplotype diversity in Caucasian populations. METHODS: We conducted a nested case–control study of breast cancer within the Nurses' Health Study cohort to address the role of common ATM haplotypes and breast cancer. Cases and controls were genotyped for five haplotype tagging single nucleotide polymorphisms. Haplotypes were predicted for 1309 cases and 1761 controls for which genotype information was available. RESULTS: Six unique haplotypes were predicted in this study, five of which occur at a frequency of 5% or greater. The overall distribution of haplotypes was not significantly different between cases and controls (χ(2 )= 3.43, five degrees of freedom, P = 0.63). CONCLUSION: There was no evidence that common haplotypes of ATM are associated with breast cancer risk. Extensive single nucleotide polymorphism detection using the entire genomic sequence of ATM will be necessary to rule out less common variation in ATM and sporadic breast cancer risk

The spectrum of ATM missense variants and their contribution to contralateral breast cancer

Heterozygous carriers of ATM mutations are at increased risk of breast cancer. In this case-control study, we evaluated the significance of germline ATM missense variants to the risk of contralateral breast cancer (CBC). We have determined the spectrum and frequency of ATM missense variants in 443 breast cancer patients diagnosed before age 50, including 247 patients who subsequently developed CBC. Twenty-one per cent of the women with unilateral breast cancer and 17% of the women with CBC had at least one ATM germline missense variant, indicating no significant difference in variant frequency between these two groups. We have found that carriers of an ATM missense mutation, who were treated with radiotherapy for the first breast tumour, developed their second tumour on average in a 92-month interval compared to a 136-month mean interval for those CBC patients who neither received RT nor carried a germline variant, (p = 0.029). Our results indicate that the presence of ATM variants does not have a major impact on the overall risk of CBC. However, the combination of RT and (certain) ATM missense variants seems to accelerate tumour development

ATM variants and cancer risk in breast cancer patients from Southern Finland

BACKGROUND: Individuals heterozygous for germline ATM mutations have been reported to have an increased risk for breast cancer but the role for ATM genetic variants for breast cancer risk has remained unclear. Recently, a common ATM variant, ATMivs38 -8T>C in cis with the ATMex39 5557G>A (D1853N) variant, was suggested to associate with bilateral breast cancer among familial breast cancer patients from Northern Finland. We have here evaluated the 5557G>A and ivs38-8T>C variants in an extensive case-control association analysis. We also aimed to investigate whether there are other ATM mutations or variants contributing to breast cancer risk in our population. METHODS: Two common ATM variants, 5557G>A and ivs38-8T>C, previously suggested to associate with bilateral breast cancer, were genotyped in an extensive set of 786 familial and 884 unselected breast cancer cases as well as 708 healthy controls. We also screened the entire coding region and exon-intron boundaries of the ATM gene in 47 familial breast cancer patients and constructed haplotypes of the patients. The identified variants were also evaluated for increased breast cancer risk among additional breast cancer cases and controls. RESULTS: Neither of the two common variants, 5557G>A and ivs38-8T>C, nor any haplotype containing them, was significantly associated with breast cancer risk, bilateral breast cancer or multiple primary cancers in any of the patient groups or subgoups. Three rare missense alterations and one intronic change were each found in only one patient of over 250 familial patients studied and not among controls. The fourth missense alteration studied further was found with closely similar frequencies in over 600 familial cases and controls. CONCLUSION: Altogether, our results suggest very minor effect, if any, of ATM genetic variants on familial breast cancer in Southern Finland. Our results do not support association of the 5557G>A or ivs38-8T>C variant with increased breast cancer risk or with bilateral breast cancer

Comprehensive analysis of the ATM, CHEK2 and ERBB2 genes in relation to breast tumour characteristics and survival: a population-based case-control and follow-up study

BACKGROUND: Mutations in the ataxia-telangiectasia mutated (ATM) and checkpoint kinase 2 (CHEK2) genes and amplification of the v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 2 (ERBB2) gene have been suggested to have an important role in breast cancer aetiology. However, whether common variation in these genes has a role in the development of breast cancer or breast cancer survival in humans is still not clear. METHODS: We performed a comprehensive haplotype analysis of the ATM, CHEK2 and ERBB2 genes in a Swedish population-based study, which included 1,579 breast cancer cases and 1,516 controls. We followed the cases for 8.5 years, on average, and retrieved information on the date and cause of death during that period from the nationwide Swedish causes of death registry. We selected seven haplotype-tagging SNPs (tagSNPs) in the ATM gene, six tagSNPs in the CHEK2 gene and seven tagSNPs in the ERBB2 gene that predicted both haplotypic and single locus variations in the respective genes with R(2 )values ≥ 0.8. These tagSNPs were genotyped in the complete set of cases and controls. We computed expected haplotype dosages of the tagSNP haplotypes and included the dosages as explanatory variables in Cox proportional hazards or logistic regression models. RESULTS: We found no association between any genetic variation in the ATM, CHEK2 or ERBB2 genes and breast cancer survival or the risk of developing tumours with certain characteristics. CONCLUSION: Our results indicate that common variants in the ATM, CHEK2 or ERBB2 genes are not involved in modifying breast cancer survival or the risk of tumour-characteristic-defined breast cancer