Electron spectroscopy instrumentation

Lucchesi, Claude A.; Lester, Joseph E.

doi:10.1021/ed050pa205

Cited by 12 publications

(5 citation statements)

References 9 publications

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“…This is similar to the results obtained for sex-linked sternopleural bristle polygenes (A. ROBERTSON in COCK 1964), sex-linked wing length polygenes (see COCK 1964) and for the glucose-6-phosphate dehydrogenase, tryptophane pyrrolase, fumarase and 6-phosphogluconate dehydrogenase structural gene loci (see LUCCHESI 1973). It now seems likely that all sex-linked genes in Drosophila show complete dosage compensation (with the exception of the alleged sexdeterminants which, according to Bridge's theory of sex determination, must be dosage dependent).…”

Section: Discussionsupporting

confidence: 89%

The Nature of Quantitative Genetic Variation in Drosophila. Iii. Mechanism of Dosage Compensation for Sex-Linked Abdominal Bristle Polygenes

Frankham

1977

Genetics

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Seventeen lines, each homozygous for a different × chromosome but all with a common autosomal genetic background, were constructed and assayed for abdominal bristle number to determine whether dosage compensation operates for sex-linked genes affecting this character.—The regression coefficient of male mean on female mean using a logarithmic scale was 0.90 ± 0.13 and the genetic regression coefficient 0.92, neither differing significantly from unity. The genetic components of variance in males and females were also very similar (0.000234 or 0.000228, respectively). These results indicate that dosage compensation is complete (or nearly so) for sex-linked genes affecting this character. The bristle scores of females did not differ in reciprocal crosses between these lines, thus dosage compensation does not operate by paternal × inactivation.—The question of an adequate scale for abdominal bristle number had to be examined during the study. A logarithmic scale appeared to be adequate for both genotypic and environmental differences.

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Section: Discussionsupporting

confidence: 89%

The Nature of Quantitative Genetic Variation in Drosophila. Iii. Mechanism of Dosage Compensation for Sex-Linked Abdominal Bristle Polygenes

Frankham

1977

Genetics

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“…Over this same time period several articles devoted to surface methods have appeared in this Journal (6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Most noteworthy are the papers by Hercules and Hercules (10)(11)(12), which give concise presentations of the fundamentals of XPS, AES, ISS, and SIMS, including examples of their use in the study of coatings, catalysts, and surface reactions.…”

mentioning

confidence: 99%

Instructional materials for teaching surface analysis

Williams¹,

Young²

1991

J. Chem. Educ.

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Surface methods comprise one of the most valuable areas of modem analytical chemistry, and chapters on these techniques are now included in newer editions of standard instrumental analysis textbooks, for example ( 1 4 ) . The marked increase in importance of X-ray Photoelectron Spectroscopy (XPS), one of the most common surface methods, is shown visually in the plot of the number of XPS related articles anoearine in Chemical Abstracts since 1967. The number of arilcles rose sharply in the early 1970's and then levelled off as this method became an established analytical tool.Over this same time period several articles devoted to surface methods have appeared in this Journal (615). Most noteworthv are the papers by Hercules and Hercules (10-12), whichgive concise presentations of the fundamentals of XPS. AES, ISS, and SIMS, including examples of their use in the study of coatings, catalysts, and surface reactions. These references and textbook materials are adequate supdements to a classroom introduction to surface analvsis. ~~ ~ ~ ~However, it is also important that students be expos& to these methods in the laboratory. Unfortunately, the extremely high cost precludes the availability of instrumentation for surface analvsis a t small institutions, and a t laree universities the usage is almost invariably limited to research project% In order the fill this instructional need, a video presentation of the XPS instrumentation of one of the authors (V.Y.Y.) has been prepared with the help of the U.F. Office of Instructional Resources. The tape covers the fundamental conceptsof XI'S and X-ray excited Augerspectroscopy.The components of the Kratos XSAM 800 XPS instrumentation, incl"ding the associated vacuum system, are explained and demonstrated. Use of camera close-ups provides detailed views of such oarts as the inside of the analvsis chamber. the various types of sample holders, the variahle-angle probe, and the comouter terminal. The script also includes discussions of important experimental considerations, such as the need for ultra-hieh vacuum and clean samole-handling procedures, the prokerns associated with thd analysis oinonconductors. the relationshio of take-off angle to sampling depth, and'the time requirements for typica ana1yses;~be ahilitv of XPS to provide chemical bonding information is discussed and demonstrated via high resdution spectra shown on the computer screen.The videotape is viewed in the instrumental analysis lahoratory as part of a "dry-lab" experiment on XPS. Each student is given a survey spectrum of a binary metal salt. After the student has determined successfully the elemental composition from the electron binding energies, he or she is provided with the integration data needed to calculate the atom ratios and the empirical formula of the compound. Tables of electron binding energies (16) and photoionization cross-sections (17) are suoolied alone with the spectra and . . are explained in the videotape. ~l t h o & h it does not demonstrate the use of XPS to obtain oxidation state inform...

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“…Autoradiographic measurements (MUKHERJEE 1966;KORGE 1970;HOLMQUIST 1972) suggest that the dosage compensation process is active at the level of gene transcription. Insight into how this apparent inequality of expression per gene copy is brought about would add to our understanding of the control of eukaryotic gene activity.Two models of dosage compensation were outlined in a recent review by LUCCHESI (1973). One is a system of "negative" control, restricting the activity of X-linked genes in females; the other is a "positive" control system, in which ii special factor in limiting supply is required for the activity of genes on the X…”

mentioning

confidence: 99%

“…Two models of dosage compensation were outlined in a recent review by LUCCHESI (1973). One is a system of "negative" control, restricting the activity of X-linked genes in females; the other is a "positive" control system, in which ii special factor in limiting supply is required for the activity of genes on the X…”

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confidence: 99%

Regulation of Gene Activity by Dosage Compensation at the Chromosomal Level in Drosophila

Stewart

Merriam

1975

Genetics

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Two models of dosage compensation have been tested by the measurement of G6PD and 6PGD enzymatic specific activities in flies hyperploid for regions of the X chromosome. Females duplicated for the proximal half of the X chromosome (2½ X's) have an increased level of G6PD and a normal level of 6PGD. Females duplicated for the distal half of the X chromosome (2½ X's) have a normal level of G6PD and an increased level of 6PGD. Males bearing duplications of various segments of the X chromosome show control levels of G6PD and 6PGD, except where the duplicated region includes the structural gene for G6PD or 6PGD. These results fail to provide evidence for either the presence of discrete X-linked compensator (regulator) genes reducing the activity of other X-linked genes, or for a factor in limiting supply necessary for the transcription of all the genes on the X chromosome. Superfemales (3 X chromosomes) have the same G6PD and 6PGD activity levels as their diploid sisters. It would appear that the regulation of gene activity by dosage compensation is a chromosomal phenomenon in that the level of activity per gene copy for loci on the X chromosome is modulated in a stepwise fashion according to the total number of X chromosomes present.

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Electron spectroscopy instrumentation

Abstract: Considers the history and basic principles of electron spectroscopy and the performance criteria of electron spectroscopy instrumentation.

Cited by 12 publications

References 9 publications

The Nature of Quantitative Genetic Variation in Drosophila. Iii. Mechanism of Dosage Compensation for Sex-Linked Abdominal Bristle Polygenes

The Nature of Quantitative Genetic Variation in Drosophila. Iii. Mechanism of Dosage Compensation for Sex-Linked Abdominal Bristle Polygenes

Instructional materials for teaching surface analysis

Regulation of Gene Activity by Dosage Compensation at the Chromosomal Level in Drosophila

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