Robert G. Webb

Copper adsorption by inactivated cells of Mucor rouxii: Effect of esterification of carboxyl groups

Abstract Inactivated copper-sensitive and copper-tolerant strains of Mucor rouxii cultured at high copper concentration were tested for their potential to adsorb Cu(II) ions from solution. We performed batch experiments to determine the pH profile for Cu(II) binding, binding capacity, and the possibility of removing the Cu(II) that had been adsorbed. The biomasses studied showed a high affinity for Cu(II) ions as the pH increased from 2 to 5. The copper-tolerant strain exhibited a higher copper adsorption than the copper-sensitive strain. Most of the Cu(II) adsorbed by the inactivated cells was desorbed by treatment with 0.1 M HCl. We investigated one of the mechanisms involved in Cu(II) binding through chemically modifying the possible carboxyl groups present on the inactivated cells of Mucor rouxii by esterification with methanol. Cu(II) binding decreased approximately 25% after the carboxyl groups were esterified. The Cu(II) binding ability of the esterified carboxyl groups was regained after base hydrolysis. These preliminary findings suggest that the carboxyl groups could be one of the mechanisms responsible for Cu(II) binding. This phenomenon can have useful applications for metal removal from contaminated water.

Observations on the Life Histories of Turtles (Genus Pseudemys and Graptemys) in Lake Texoma, Oklahoma

Aspects of the life histories of Pseudemys scripta elegans and Graptemys pseudogeographica ouachitensis (Reptilia: Testudines) were studied in Lake Texoma, Oklahoma. Variation in the color patterns of the two species is considered. Males of Pseudemys are sexually mature at a plastron length of 9.0 to 10.0 cm; females at 17.4 to 19.3 The realized annual reproductive capacity of a female Pseudemys is estimated to be 26.4 eggs (3 clutches; 8.8 eggs per clutch). Some males become sexually mature in their third year; females in their fourth. Males of Graptemys are sexually mature at a plastron length of 7.0 cm; females at 15.0 cm. Each Graptemys female lays approximately 19.5 eggs per year (3 clutches; 6.5 eggs per clutch). The elongation of the tail and third claw of the forelimb are secondary sexual characters in males of both species. Growth in both species progresses rapidly prior to maturity, however, Graptemys females seemingly grow more slowly than Pseudemys during this period. Rapid fluctuation of the water level may result in a slowing of growth in Pseudemys, but the evidence is only suggestive, not conclusive. Alternation of habitats along the shoreline due to the changing water level is believed to be responsible for the nomadic behavior of Pseudemys as well as in determining the quality and quantity of food available. The abundance of the red-eared turtle, Pseudemys scripta elegans Wied, and the Ouachita map turtle, Graptemys pseudogeographica ouachitensis Cagle, in Lake Texoma, made possible a comparative life history study at the University of Oklahoma Biological Station, Marshall County, 2 miles east of Willis. Acknowledgments.-I am grateful to Dr. Carl D. Riggs, Director of the Biological Station for permission to utilize facilities in his care. I am indebted further to Dr. Harley P. Brown of the University of Oklahoma Department of Zoology for the analysis of the animal material in the contents of digestive tracts of selected turtles, and to Dr. George J. Goodman of the University of Oklahoma Department of Botany for selected botanical determinations. Finally, thanks are extended to Drs. Fred R. Cagle and Henry S. Fitch for constructive criticism of the manuscript.

Determination of Cu Environments in the Cyanobacterium Anabaena flos-aquae by X-Ray Absorption Spectroscopy

ABSTRACT Whole cells and peptidoglycan isolated from cell walls of the cyanobacterium Anabaena flos-aquae were lyophilized and used at pH 2 and pH 5 in Cu(II) binding studies. X-ray absorption spectra measured at the Cu K-edge were used to determine the oxidation states and chemical environments of Cu species in the whole-cell and peptidoglycan samples. In the whole-cell samples, most of the Cu retained at both pH values was coordinated by phosphate ligands. The whole-cell fractions contained significant concentrations of Cu(I) as well as Cu(II). An X-ray absorption near-edge spectrum analysis suggested that Cu(I) was coordinated by amine and thiol ligands. An analysis of the peptidoglycan fractions found that more Cu was adsorbed by the peptidoglycan fraction prepared at pH 5, due to increased chelation by amine and carboxyl ligands. The peptidoglycan fractions, also referred to as the cell wall fractions, contained little or no Cu(I). The Cu loading level was 30 times higher in the cell wall sample prepared at pH 5 than in the sample prepared at pH 2. Amine and bidentate carboxyl ligands had similar relative levels of importance in cell wall peptidoglycan samples prepared at both pH values, but phosphate coordination was insignificant.

The Cyanobacterial Heat-Shock Response and the Molecular Chaperones

The studies of the heat-shock response, other stress responses and protein folding have become intimately intertwined during the past few years. The heat-shock response, which was first described in Drosophila melanogaster over 30 years ago (Ritossa, 1962), entails the rapid and selective increased expression of a large class of proteins. Surprisingly, this heat-shock response was described in Escherichia coli long after the phenomenon had been described in numerous eucaryotic organisms. Since that time, work in E. coli has been a very fertile field for an understanding of this response at the genetic and molecular biological levels. However, the key experiments which led to a synthesis of many different disciplines were the analysis of the assembly of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) from chloroplasts. Research on the heat-shock proteins during the 1970s and 1980s demonstrated that such proteins were involved in protein-protein interactions. Research on the assembly of Rubisco in E. coli demonstrated the absolute requirement for specific heat-shock proteins and helped lead to the concept of molecular chaperones.

Determination of copper binding in Anabaena flos-aquae purified cell walls and whole cells by X-ray absorption spectroscopy

In this study, isolated cell wall material and lyophilized whole cells of the cyanobacterium Anabaena flos-aquae (ATCC 22664) were examined for their ability to bind Cu ions. Experiments were performed to gain insight on the chemical groups that may be involved in the binding of Cu ions. We have taken advantage of physical/chemical tools, which allowed us to identify these groups at the atomic level. Atomic absorption spectroscopy was utilized to determine the Cu ion binding capacity of the two biomaterials as a function of pH. Both biomaterials showed a substantial amount of Cu ion binding at pH 5 (26.8 mg/g of biomass for the whole cell group and 90.4 mg/g for the cell wall group). X-Ray absorption spectroscopy was used to determine the speciation of Cu ions bound by cell wall and whole cell materials as well as to elucidate which functional groups were involved in binding of the Cu ions. X-Ray absorption near-edge spectra showed that the majority of the Cu was bound in both biomaterials as Cu(II) and also suggested that Cu(II) ions are binding to oxygen ligands in an environment resembling that of Cu(II) acetate monohydrate.

Taxonomic Notes Concerning the Trionychid Turtle Lissemys punctata (LACEPÈDE)

Although long-conceived as a monotypic species of three subspecies (SMITH, 1931), intergradation has not yet been demonstrated between subspecies of Lissemys punctata. The two subspecies L. p. punctata and L. p. andersoni show intergradation in pattern features of head and carapace, and are similar in osteological features. The configuration of peripheral bones, and advent of well developed plastral callosities at a relatively small size that indicates small maximal size, suggest specific status for L. p. scutata..

Softshell turtles in Hawaii.

Inquiry into the identity of softshell turtles in Hawaii reveals the occurrence of two species, Trionyx steindachneri and T. sinensis, living in wild populations on the island of Kauai, and at least T. steindachneri also occurring on Oahu. Descriptive and life history data are provided for the little-known T. steindachneri.

A New Kingsnake from Mexico, with Remarks on the Mexicana Group of the Genus Lampropeltis

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Life History Aspects of the Mexican Salamander Ambystoma rosaceum (Amphibia, Urodela, Ambystomatidae)

Breeding sites, eggs, small larvae, and neotenes of Ambystoma rosaceum are described. The breeding habitat is slow-moving mountain streams. Preferred deposition sites of single eggs seem to be the undersides of flat rocks. Hatchling larvae are uniformly dark brown until acquisition of a pale-dark mottling near 35 mm SVL. Breeding occurs in summer with the advent of the rainy season, and may occur in winter months. Neoteny and variations in the annual reproductive cycle are probably dependent on permanent water. Life history features are compared with those of Ambystoma ordinarium. The geographic range of A. rosaceum is extended into the Mexican states of Sinaloa and Zacatecas. ated. Anderson and Worthington (1971) reported that the entire life history of Ambystoma ordinarium takes place in fast-moving mountain brooks. Anderson (1961) described certain aspects of the life history of A. rosaceum, reporting that larval development takes place in clear, generally slow-moving mountain streams and requires about one year, and that after metamorphosis adults return to terrestrial habitats. Larvae of A. rosaceum greater than 35 mm snout to vent length (SVL) are strikingly marked with contrasting light and dark stripes, spotting or mottling (Anderson, 1961).

Variation and Distribution of the Iguanid Lizard Sceloporus bulleri, and the Description of a Related New Species

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