Late Devonian benthic marine communities of the central Appalachian Allegheny Front

Four benthic marine communities occur in the clastic facies of the prograding Upper Frasnian-Lower Famennian (Upper Devonian) Foreknobs Formation in the Central Appalachians along the Allegheny Front in Maryland, West Virginia, and Virginia. Deep-water, rapidly prograding environments were inhabited by the Ambocoelia-Chonetes Community, dominated by an epifauna of unattached brachiopods. Offshore bar environments were inhabited by the Cyrtospirifer-Camarotoechia Community, exhibiting adaptations to shallow-water, high-energy conditions and probably lowered salinities. Shallow-water, sublittoral environments were inhabited by the Atrypa-Cypricardella Community, a community in which existed a variety of life habitats and a diverse epifaunal and infaunal association of brachiopods and bivalve molluscs. The Leptodesma-Tylothyris Community flourished in nearshore bar-protected environments in the southern region of the study area, whereas in the north the Cyrtospirifer-Camarotoechia Community inhabited nearshore environments in conjunction with the onshore development of a large fluviodeltaic system.     

Fatty Acid and Chlorophyll Levels of Coastal Bermudagrass during the Day and during Maturation

Lipids were extracted from fresh, field-grown coastal bermudagrass (Cynodon dactylon (L.) Pers.) and the fatty acids determined by gas chromatography. Total fatty acid levels (dry weight basis) increased during the day and reached a single maximum at sunset in 2-week-old grass; whereas, in older grass, the fluctuations in fatty acid levels showed two maxima. The first maximum occurred 4 h after sunrise and the second maximum occurred at sunset. Total fatty acid levels, based on dry weight, decreased during the first 6 weeks of growth and changed very little after an additional 4 weeks' growth in bermudagrass leaf blades. Chlorophyll levels (dry weight basis) continuously decreased during the entire growth period (10 weeks). Chlorophyll alb ratios increased at sunset in 2- and 6-week-old grass, but this ratio did not change during the day in subsequent growth stages. The results of these experiments show that stages of maturity affected fatty acid fluctuations during the day as well as total fatty acid and chlorophyll levels in Coastal bermudagrass leaf blades. Chlorophyll alb ratios varied independently of fatty acid levels.     

A Cannibal in the National Museum: The Early Career of Franz Boas in America

Franz Boas spent several weeks at Fort Rupert, British Columbia, at the end of 1894, when he saw the Kwakiutl hamatsa ritual in situ for the first time. Soon after his return east Boas posed for a series of photographs in the U.S. National Museum for a diorama of the hamatsa dance. These photographs, now published for the first time, are a sharp reminder of Boas' constant (and sometimes forced) collaboration with the limited number of anthropological institutions in America at the end of the century, and of his personal difficulties in establishing himself professionally in America.     

Messenger RNA metabolism of animal cells: possible involvement of untranslated sequences and mRNA-associated proteins

The past several years have seen a virtual revolution in the study of eukaryotic mRNA. Among the notable recent achievements are the positive identification of mRNA precursors in HnRNA, the enumeration of the DNA sequences from which mRNA is transcribed, and the finding that mRNA in cultured cells is much more stable than was previously believed. One of most far-reaching discoveries has been the finding that mRNA in eukaryotes contains poly A. This discovery, aside from providing a powerful tool for mRNA isolation, has generated a large body of research into the properties and metabolism of poly A itself. In addition, the finding of a poly A-associated protein has given a renewed stimulus to the study of proteins associated with mRNA. This review is devoted to a discussion of these and related achievements, and some of their implications     

The Genetic Structure and Evolutionary Fate of Parthenogenetic Amphibian Populations as Determined by Markovian Analysis

SYNOPSIS. One-locus, two-allele models are presented which describethe genetic consequences of naturally occurring andexperimentallyinduced parthenogesis in triploid and diploid amphibians. Themodels may in general be used to investigate genetic changeresulting from apomictic (ameiotic) and automictic (meiotic)parthenogenetic reproduction. These models quantify the influence of mutation, segregation,and selection upon genetic variability in parthenogeneticpopulations.They also allow an estimate of the relative importance of stochasticforces in altering this variability. They thus provide a basisfor understanding evolution in these populations. Some of the conclusions derived from this study contradict previouspredictions regarding genetic variability in parthenogeneticpopulations. First, if mutation is the sole source of geneticchange (i.e., strict apomixis), parthenogenetic populationsshould not become completely heterozygous. Second, small amountsof segregation occurring in apomictic populations have enormouseffects upon the genetic variability of these populations, i.e.,they should lose much of their heterozygosity. In addition to these conclusions, the results of this studysuggest that studies of protein variability in parthenogeneticspecies should contribute toward answering the question: Howmuch of the genetic variability observed in nature is evolutionarilyrelevant?     

Dating of graptolite zones by sedimentation rates: implications for rates of evolution

Preliminary determinations of ancient pelagic sedimentation rates agree with modern rates at about 4 meters per million years. By combining data on the thickness of graptolite zones from the North American Cordillera with data from other parts of the world, we have refined the Early Silurian time scale and obtained much better resolution than is possible for radiometric dates. The new Early Silurian time scale allows estimation of true rates of change in graptolite diversity. The Llandoverian diversity explosion is twice as rapid as was previously thought. The brevity of diversity lows and rapidity of speciation support modern theories of quantum evolution.     

A new spectrophotometric assay for enzymes of purine metabolism. II. Determination of guanase activity.

A new method for the determination of guanase is described. Xanthine, the product of the guanase reaction, is oxidized by xanthine oxidase, forming uric acid and hydrogen peroxide. Hydrogen peroxide is further reduced to water by catalase in the presence of ethanol. The acetaldehyde formed in this reaction step is dehydrogenated NAD or NADP dependent by aldehyde dehydrogenase. The NADH or NADPH production is measured and utilized for the calculation of the guanase activity. The sensitivity of the method can be doubled by the addition of uricase, which oxidizes uric acid to permit the formation of another mole of hydrogen peroxide.     

In-depth qualitative and quantitative analysis of composite glycosylation profiles and other micro-heterogeneity on intact monoclonal antibodies by high-resolution native mass spectrometry using a modified Orbitrap

Here, we describe a fast, easy-to-use, and sensitive method to profile in-depth structural micro-heterogeneity, including intricate N-glycosylation profiles, of monoclonal antibodies at the native intact protein level by means of mass spectrometry using a recently introduced modified Orbitrap Exactive Plus mass spectrometer. We demonstrate the versatility of our method to probe structural micro-heterogeneity by describing the analysis of three types of molecules: (1) a non-covalently bound IgG4 hinge deleted full-antibody in equilibrium with its half-antibody, (2) IgG4 mutants exhibiting highly complex glycosylation profiles, and (3) antibody-drug conjugates. Using the modified instrument, we obtain baseline separation and accurate mass determination of all different proteoforms that may be induced, for example, by glycosylation, drug loading and partial peptide backbone-truncation. We show that our method can handle highly complex glycosylation profiles, identifying more than 20 different glycoforms per monoclonal antibody preparation and more than 30 proteoforms on a single highly purified antibody. In analyzing antibody-drug conjugates, our method also easily identifies and quantifies more than 15 structurally different proteoforms that may result from the collective differences in drug loading and glycosylation. The method presented here will aid in the comprehensive analytical and functional characterization of protein micro-heterogeneity, which is crucial for successful development and manufacturing of therapeutic antibodies