Buried Sites Research Articles

Reversible association as a possible regulatory mechanism for controlling the activity of the non-specific leucine-binding protein from Escherichia coli

The non-specific leucine-binding protein (LIV-protein) from E. coli tends to associate in the linear structures with buried binding sites. The association is reversible and depends on the protein and substrate concentrations. It is manifested in a negative cooperativity of binding at low protein concentration and in the dependence of the apparent dissociation constant and apparent number of binding sites on both protein and substrate concentrations. Such properties of the LIV-protein may have a regulatory significance.

Amino acid sequence of rabbit muscle aldolase and the structure of the active center.

Elucidation of the amino acid sequence of fructose-1,6-bis-phosphate aldolase from rabbit muscle has made it possible to assign the positions of the functional groups known to play specific roles in the catalytic activity, and also to locate the buried, exposed, and active site cysteine residues. The results indicate that the middle portion of the polypeptide chain, including Cys-134, Cys-149, Cys-177, and Cys-l99, is buried in the native structure, with regions containing Cys-72, Lys-107, Lys-227, Cys-336, His-359, and the COOH-terminal residue (Tyr-361) folded into the active center of the enzyme, at or near the surface of the enzyme molecule.

Magnetic mapping of buried archaeological sites

Magnetic mapping of buried archaeological sites

Magnetic methods of archaelogical prospecting—advances in instrumentation and evaluation techniques

Rapid survey of many minor archaeological sites gives a more balanced picture of the past in a given region. The development of accurate portable magnetometers now allows mapping of such buried sites in many types of soils. New differential instruments are more convenient, eliminating most external distur­bances. The major remaining problem is the separation of weak archaeological magnetic 'signals' from ‘noise’ due to minor geological irregularities. Digital filtering, nonlinear processing and a system of data display which makes use of the eye’s ability to see faint shapes in confused backgrounds have been developed for use with a large computer. Optimum filter techniques can be worked out from computed theoretical model studies of signals and noise.

Techniques used in archeological field surveys

As with radiocarbon dating also the subject of archaeological prospecting now has a reasonably long and full development. Even so it is probable that there remain those both on the archae­ological and on the scientific side who are not completely clear as to what has and can be done. Thus it was most opportune that the present paper could be included in the symposium in the hope that this may encourage even further use and development of the methods. While there exist a whole range of possible techniques for archaeological field surveys those of geophysical prospecting enter most closely within the general topic of this symposium and so will mainly be concentrated upon. In all cases the basic aim of any survey will be that of discovering information on buried archaeological sites either before or instead of excavation. The value of such information in part depends on the fact that normally the archaeological deposits will not be disturbed while almost always the surveying can be carried out relatively rapidly; at least compared to the time required for excavation. This gaining of information on the hidden archaeological features is the main reason for the use of prospecting methods. However their value for archaeology has been greatly increased as a result of the difficulties caused by modern developments. So many of these tend to result in damage to or even complete destruction of archaeological sites. Often either the existence of a site or its exact extent will be unknown with the result that there is no chance to undertake an adequate investigation before all is lost. If a sufficiently clear idea could be obtained sufficiently quickly then much more could be done. Such applications represent one of the most important aids offered to archae­ology by prospecting techniques. Even so it must not be forgotten that they have much to offer irrespective of these present-day practical problems and it is worth underlining their value in giving information, often in some detail, without any disturbance to the archaeological features.

Macroglobulin rheumatoid factors directed toward buried antigenic sites of human gamma-globulins.

SummaryFifty rheumatoid sera with high FII hemagglutination titers have been examined for the presence of agglutinating factors directed toward an antigenic site revealed by pepsin digestion of human γ2‐globulins; 19 sera (38% of the sera examined) contained such factors.The agglutinating factor directed toward the buried site was characterized in 13 sera by sulfhydryl reduction, column chromatography and density gradient ultracentrifugation experiments. In 12 sera the agglutinating factor was a 19S protein. 7S agglutinators were present in two sera.By hemagglutination inhibition studies, it was demonstrated that proteolysis of human γ2‐globulins with pepsin reveals an antigenic site which is not available in the intact molecules. This buried site was present only in the electrophoretic fractions of human sera which contain γ‐globulins. Pepsin treatment of bovine and rabbit γ‐globulins failed to reveal a similar determinant.The possible significance of the heterogeneity in combining specificities and molecular size of the agglutinating factors is discussed.RésuméCinquante sérums de malades atteints de polyarthrite chronique évolutive, ayant un titre élevé au test F II selon Heller, ont été examinés quant à la présence de facteurs agglutinants dirigés contre un site antigénique manifeste après digestion peptique des gamma2‐globulins: 19 sérums (38% des sérums examinés) contenaient ces facteurs.Les caractères du facteur agglutinant dirigé contre ce site antigénique interne ont été déterminés par des expériences de réduction sulfhydrique, de chromatographic sur colonne et d'ultracentrifugation. Dans 12 sérums, le facteur agglutinant était une protéine 19 S. Dans 2 sérums, le facteur agglutinant était une protéine 7 S.Des tests d'inhibition d'hémagglutination ont démontré que la protéolyse des gamma2‐globulines humaines par la pepsine révèle un site antigénique non détectable sur les molécules intactes. Ce site antigénique interne n'était présent que dans les fractions électrophorétiques d'un sérum humain contenant des gamma‐globulines. Le traitement par la pepsine de gamma‐globulines de bœuf et de lapin ne révélait pas la présence d'un déterminant antigénique similaire.La signification de la présence de facteurs agglutinants, de spécificité et de grandeur moléculaire différentes, est discutée.ZusammenfassungFünfzig Rheumatikerseren mit hohen F II‐Hämagglutinationstitern wurden auf die Anwesenheit agglutinierender Faktoren gegen Antigenbezirke, die bei Pepsinbehandlung von menschlichen γ2‐Globulinen freigelegt werden, untersucht. In 19 Seren, d. h. in 38% der untersuchten Seren gelang es, solche Faktoren nachzuweisen.In 13 Seren wurde der gegen den abgedeckten Antigenbezirk gerichtete agglutinierende Faktor durch Sulfhydrylreduktion, Säulenchromatographie sowie Ultrazentrifugenuntersuchung im Dichtegradienten näher charakterisiert. In 12 Seren erwies sich der agglutinierende Faktor als 19 S‐Protein. In zwei Seren waren 7 S‐Agglutinatoren vorhanden.Mit Hilfe von Hämagglutinationshemmungsversuchen gelang es zu zeigen, daß bei der Pepsin‐Proteolyse von menschlichem γ2‐Globulin ein Antigenbezirk freigelegt wird, der am intakten Molekül für serologische Reaktionen nicht zur Verfügung steht. Diese abgedeckte Antigendeterminante war in den elektrophoretisch aufgetrennten Serumeiweißfraktionen nur in jenen nachweisbar, die γ‐Globuline enthielten. Bei Pepsinbehandlung von Rinder‐ und Kaninchen‐γ‐Globulin wurde keine analoge Determinante freigelegt.Die Bedeutung der Heterogenität der kombinierten Spezifitäten sowie der unterschiedlichen Molekülgroße solcher agglutinierender Faktoren wird diskutiert.

Air Reconnaissance in Britain, 1951–5

Accounts of air reconnaissance in Britain have already been printed in this Journal (XLI, for north Britain; XLIII, for south Britain): the present paper records recent discoveries, bringing the previous records up to date.Of the last five summers only in 1955 was there a marked drought favourable to the development of crop marks; but it has been possible to observe different parts of the country under a wide variety of conditions. These have allowed advantage to be taken of different combinations of weather, crops, and soil, so that a buried site invisible one year might be seen in another. Moreover, opportunities for reconnaissance in March and April have meant that large areas could be observed soon after spring ploughing, when soil-patterns in bare fields often reveal disturbances in the ground. These conditions have been particularly valuable for studying Celtic field-systems on the chalk downs and traces of ancient agriculture in the Fenland.In the north, reconnaissance has revealed an interesting new group of military works, apparently of early date, at Troutbeck on the margin of the Lake District, besides yielding much fresh information at sites already known. This is particularly true of the extensive Roman sites in Scotland that often now lie within several different fields, not all of which are under suitable crops in any one year. Two forts, two signal-stations, and some sixteen temporary camps may be added to the list of discoveries given in JRS XLI.