Species and geographic distribution patterns of the macaque prealbumin polymorphism

A polymorphism for thyroxine-binding prealbumin (TBPA) is investigated in regards to mode of inheritance as well as distribution within eight species of macaques from known geographic areas. It is found that an electrophoretically slow variant seems to be due to a codominant allele present in six of the species tested.While the slow form has a frequency of less than 30% in most other populations tested, it is fixed at 100% in the Japanese macaques (M. fuscata). The locus is inHardy-Weinberg equilibrium in all populations however. Since TBPA is intimately related to thyroxine levels in the blood the polymorphism may be an adaptation to cold environments.     

On the uniqueness of the flagellum ofThiobacillus thiooxidans

The flagellum of the obligate chemolithotrophThiobacillus thiooxidans was found to retain its integrity and function under environmental conditions that characterize it as among the most stable of alloplasmatic structures. Although a simple, presumably unsheathed organelle approximately 17 mµ in diameter, it is operationally active at a hydrogen ion concentration measured as low as pH 0.6. It was found to resist 1 hr exposures at 37 C to 6m urea, 10m acetamide, 1n H₂SO₄, 2°_o trypsin, and heating to 70 C for 45 min at pH 5.0. It was, however, destroyed after 1 hr in 10n H₂SO₄ at room temperature. In addition, the flagellum can be synthesized at pH 1.1, but only in the presence of sulfur. The synthesis requires a longer time than in chemoorganotrophic cubacteria.     

A test of homology between the B chromosome of maize and abnormal chromosome 10, involving the control of nondisjunction in B's

Summary Nondisjunction of B and B-translocation chromosomes occurs regularly in maize at the second pollen mitosis (Roman, 1947; Blackwood, 1956). The mechanism of nondisjunction was studied using the A-B interchange, TB-9b. The B⁹ chromosome of the interchange undergoes nondisjunction at the second pollen mitosis, while the 9^B chromosome does not (Roman, 1947). It was shown that the 9^B chromosome must be present in a plant for nondisjunction of the B⁹ to occur. This is consistent with the reports of Roman on TB-4a (1949) and Longley on TB-10a (1956). It was also demonstrated that the influence of the 9^B chromosome is limited to pollen grains containing it, and does not extend to all the pollen of a plant.A test of homology between the B chromosome and abnormal chromosome 10 was also made. The ability of abnormal 10 to substitute for the 9^B chromosome and induce nondisjunction of the B⁹ was tested. Nondisjunction did not occur at a detectable rate in the presence of abnormal 10, and the results failed to support Ting's proposal (1958) concerning the origin of abnormal 10.     

An evolvant ofEscherichia coli that employs thel-fucose pathway also for growth onl-galactose andd-arabinose

Summary l-Galactose,d-arabinose, andl-fucose form six-membered rings with identical stereoconfigurations. However, onlyl-fucose can serve as the sole carbon and energy source of wild-typeEscherichia coli K-12. A mutant that can grow onl-galactose andd-arabinose was isolated by alternate selection on the two sugars. Thel-fucose pathway became inducible by all three sugars. Transduction into the mutant of the wild-type fuc⁺ region containing both the regulatory and structural genes abolished the novel growth abilities onl-galactose andd-arabinose, whereas transduction into the mutant of a fuc deletion abolished the growth abilities on all three sugars. Introduction of the wild-type fucR⁺ (which encodes the activator protein for the fuc regulon) on a multicopy plasmid depressed the growth abilities of the mutant onl-galactose andd-arabinose, but not onl-fucose. The results suggest that the effector specificity of the activator protein in the mutant was broadened. It is proposed that an adaptive response of an activator-controlled system is more likely than that of a repressor-controlled system to achieve fixation in a population, because the first variant to emerge in response to a novel metabolic demand has a good chance of having an altered specificity of regulation. Such a change entails little or no metabolic liability during the absence of the novel substrate. In contrast, the first variant of a negatively controlled system to emerge has an overwhelming chance of being the result of a random mutation that destroys repressor function. Although negatively controlled systems can be more opportunistic in exploiting new conditions than positively controlled systems, an adaptive change is less likely to become fixed because of the cost associated with gratuitous constitutive gene expression in the absence of the substrate.     

Adaptive Response of Bacillus sp. F26 to Hydrogen Peroxide and Menadione

The adaptive and cross-protection responses to oxidants were investigated in Bacillus sp. F26. The cells were treated with sublethal concentrations of either H₂O₂ or menadione (a superoxide-generating agent) to induce an adaptive response. The results showed that the cells treated with menadione exhibited cross-protection against, but in another case, those cells treated with H₂O₂ did not show significant resistance to menadione. It suggests that Bacillus sp. F26 possesses two separate adaptive responses that respond to the two different kinds of oxidants. The adaptability is regarded as that which is accompanied by the inductions of some antioxidant enzymes. It was found that catalase (CAT) production was increased about 1.6-fold after treatment with 600 μM H₂O₂, whereas the presence of 50 μM menadione induced CAT, superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), and glutathione reductase (GR) by 2-, 2-, 2-, and 1.6-fold, respectively. The results can be used to explain why menadione-treated cells have higher adaptability to lethal concentrations of oxidants than that of those H₂O₂-treated. In addition, it was found that growing Bacillus sp. F26 in high-salinity media causes it to become more resistant to H₂O₂ and menadione stress, which may be partially due to the induction of CAT and SOD production under high NaCl concentration.     

Properties of the sugar carrier in baker’s yeast

The uptake by baker’s yeast of monosaccharides (d-arabinose,d-xylose,d-ribose,d-glucose,d-galactose) at very low concentrations (0.02–2mm) shows a distinct asymmetry, the apparent intracellular concentrations attaining values up to 85 times higher than in the medium. A practically irreversible binding inside the cell appears to be involved. The binding has an apparent activation energy of 11000 cal/mole. It is not affected by metabolic inhibitors but requires cell integrity for its occurrence. Some features of the binding suggest that the monosaccharides are partly incorporated into cell components, but whether the process is enzymic in nature remains unclear.     

Statistical tests for QTL and QTL-by-environment effects in segregating populations derived from line crosses

Quantitative trait locus (QTL) studies in plants frequently employ phenotypic data on a population of lines (doubled haploid lines, recombinant inbred lines, etc.) tested in multiple environments. An important feature of such data is the genetic correlation among observations on the same genotype in different environments. Detection of QTL-by-environment interaction requires tests which take this correlation into account. In this article, a comparison was made of the properties of several such tests by means of simulation. The results indicate that a split-plot analysis of variance (anova), being an approximate method, tends to be too liberal under departures from the Huynh-Feldt condition. A standard two-way anova, which ignores genetic correlation, yields inappropriate tests and should be avoided. In contrast, mixed model approaches as well as univariate and multivariate repeated-measures anova yield valid results. This supports the use of a flexible mixed model framework in more complex settings, which are difficult to tackle by repeated-measures anova.This paper is dedicated to Prof. Dr. H. F. Utz on the occasion of his 65th birthday.     

Synthesis and assembly of fungal melanin

Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from l-3,4-dihydroxyphenylalanine (l-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances.     

A comparison of airborne and dust-borne allergens and toxins collected from home,office and outdoor environments both in New Haven,United States and Nanjing,China

In this study, the airborne and dust-borne concentrations of endotoxin, (1,3)-β-d-glucan and five house dust allergens were measured in office, home, and outdoor environments both in New Haven, United States and Nanjing, China. Air samples were collected using a BioSampler at a flow rate of 12.5 l/min for 30 min. Dust samples were simultaneously collected using a surface sampler. Dust samples went through extraction and dilution before analysis, while air samples were analyzed directly. Limulus Amoebocyte Lysate (LAL) Pyrochrome and Glucatell assays were used to quantify endotoxin and (1,3)-β-d-glucan concentration levels, respectively. Enzyme-linked sorbent assay was used to measure the dust mites, cat, dog, and cockroach allergens. The experimental results indicated that endotoxin, (1,3)-β-d-glucan and allergen concentrations vary greatly both with samples and environments. In all tested environments, endotoxin concentration ranged from 0.8 to 83.7 ng/m³ for air, and 7.8 to 14.3 ng/mg for dust. (1,3)-β-d-glucan concentration ranged from 0.1 to 9.8 ng/m³ for air, and 6.6 to 110 ng/mg for dust. Cockroach allergens were detected only in New Haven office and outdoor environments, and other allergens ranged from 0.1 to 90 ng/mg for dust samples, and from 1.5 to 1,282 ng/m³ for air samples. In general, similar profiles of allergens and toxins were observed in New Haven and Nanjing environments. Linear regression analysis showed that there were better endotoxin and (1,3)-β-d-glucan linear correlations (R ² = 0.78, 0.87, respectively) between the dust and air samples compared to those of the allergens Der f 1 and Der p 1 (R ² = 0.5, 0.7, respectively). This research contributes to the development of robust biological exposure assessment and the elaboration of airborne and dust-borne bio-mass in the living environments.     

Legionella pneumophila in the Environment: The Occurrence of a Fastidious Bacterium in Oligotrophic Conditions

Legionella pneumophila, a micro-organism encountered in aquatic environments, can cause serious intracellular infections among humans. Since the bacterium is ubiquitous in aquatic habitats, it appears to be impossible to prevent L. pneumophila from entering man-made water systems. However, many questions concerning the survival and/or growth in the environment, the partners and opponents of L. pneumophila remain unanswered. This review focuses on the factors governing the ecology of L. pneumophila, since there is considerable divergence and even contradiction in literature on its environmental requirements. A key question to be resolved is the discrepancy between the fastidious nature of L. pneumophila in axenic cultures (e.g. 400 mg l⁻¹ L-cysteine and 250 mg l^-1 ferric iron) and the nutritionally poor environments in which it is commonly detected. It is assumed that dense microbial communities, as occurring in sediments and biofilms – but not likely in surface and drinking water, – can provide the necessary growth requirements for L. pneumophila. However, most of the studies concerning L. pneumophila have led to the general opinion that the organism can only multiply in the aquatic environment as a parasite in certain protozoa. The discovery of the non-classical siderophore legiobactin also indicates that the iron requirement for survival and autonomous growth is not as high as has been assumed. It thus appears that in order to control Legionella in the environment, focus should be on the eradication of microbial hotspots in which L. pneumophila resides.     

On the Accessibility of Adaptive Phenotypes of a Bacterial Metabolic Network

The mechanisms by which adaptive phenotypes spread within an evolving population after their emergence are understood fairly well. Much less is known about the factors that influence the evolutionary accessibility of such phenotypes, a pre-requisite for their emergence in a population. Here, we investigate the influence of environmental quality on the accessibility of adaptive phenotypes of Escherichia coli''s central metabolic network. We used an established flux-balance model of metabolism as the basis for a genotype-phenotype map (GPM). We quantified the effects of seven qualitatively different environments (corresponding to both carbohydrate and gluconeogenic metabolic substrates) on the structure of this GPM. We found that the GPM has a more rugged structure in qualitatively poorer environments, suggesting that adaptive phenotypes could be intrinsically less accessible in such environments. Nevertheless, on average ∼74% of the genotype can be altered by neutral drift, in the environment where the GPM is most rugged; this could allow evolving populations to circumvent such ruggedness. Furthermore, we found that the normalized mutual information (NMI) of genotype differences relative to phenotype differences, which measures the GPM''s capacity to transmit information about phenotype differences, is positively correlated with (simulation-based) estimates of the accessibility of adaptive phenotypes in different environments. These results are consistent with the predictions of a simple analytic theory that makes explicit the relationship between the NMI and the speed of adaptation. The results suggest an intuitive information-theoretic principle for evolutionary adaptation; adaptation could be faster in environments where the GPM has a greater capacity to transmit information about phenotype differences. More generally, our results provide insight into fundamental environment-specific differences in the accessibility of adaptive phenotypes, and they suggest opportunities for research at the interface between information theory and evolutionary biology.     

Quantum Yields of Decomposition and Homo-Dimerization of Solid <Emphasis Type="SmallCaps">L</Emphasis>-Alanine Induced by 7.2 eV Vacuum Ultraviolet Light Irradiation: An Estimate of the Half-Life of <Emphasis Type="SmallCaps">L</Emphasis>-Alanine on the Surface of Space Objects

One of the leading hypotheses regarding the origin of prebiotic molecules on primitive Earth is that they formed from inorganic molecules in extraterrestrial environments and were delivered by meteorites, space dust and comets. To evaluate the availability of extraterrestrial amino acids, it is necessary to examine their decomposition and oligomerization rates as induced by extraterrestrial energy sources, such as vacuum ultraviolet (VUV) and X-ray photons and high energy particles. This paper reports the quantum yields of decomposition ((8.2 ± 0.7) × 10⁻² photon⁻¹) and homo-dimerization ((1.2 ± 0.3) × 10⁻³ photon⁻¹) and decomposition of the dimer (0.24 ± 0.06 photon⁻¹) of solid l-alanine (Ala) induced by VUV light with an energy of 7.2 eV. Using these quantum yields, the half-life of l-Ala on the surface of a space object in the present earth orbit was estimated to be about 52 days, even when only photons with an energy of 7.2 eV emitted from the present Sun were considered. The actual half-life of solid l-Ala on the surface of a space object orbit around the present day Earth would certainly be much shorter than our estimate, because of the added effect of photons and particles of other energies. Thus, we propose that l-Ala needs to be shielded from solar VUV in protected environments, such as the interior of a meteorite, within a time scale of days after synthesis to ensure its arrival on the primitive Earth.     

An optimum environment for the culturing of Cytospora isolates from stone fruits. III. Nitrogen sources

Summary Four isolates ofCytospora cincta Fr. and 2 ofC. leucostoma Fr. were cultured on media containing 7 different nitrogenous compounds. Maltose served as a constant source of carbon. All experiments were carried out at 25° C.Total growth as determined by mycelial weights, and degree of sporulation as determined by an arbitrary system, revealed that 1) potassium nitrate was most satisfactory as a source of nitrogen, 2) response of the isolates tended to segregate them along species lines, and 3) the pH of the medium appeared to be a factor in the degree of response.Growth-habit experiments emphasized 1) extreme variation in colony characteristics and 2) the need for standardization of laboratory environments for comparative studies of the fungi.Approved by the Director of the Idaho Agricultural Experiment Station as Research Paper No. 518.     

Crucial demonstration of the proliferative growth regulating property of the naturally occurring chemical equilibrium composed of sulfhydryl and its partially oxidized derivatives

Summary and conclusion Four experimental criteria have been set up which are essential for the postulate that growth by increase in cell number is regulated by the naturally occurring chemical equilibrium composed of the sulfhydryl group and its partially oxidized derivatives.It has been shown that two of these have already been satisfied, and that a third can be considered as indirectly established. Report is made of an experiment which discharges the fourth.The cumulative data thus lead to the conclusion that the postulate is a true expression of a basic biological principle.Grateful acknowledgement should be given to the International Cancer Foundation established by Mr. Wm. H.Donner of Philadelphia for support in this work.These experiments were done at The Marine Experiment Station of The Research Institute of The Lankenau Hospital, North Truro, Massachusetts, under grants from Mr.August Bein of Philadelphia, and the Capt. L. D.Baker Estate of Boston and Wellfleet.     

Studies of the effects of aminopterin on the crypts of Lieberkühn in rats

Summary Studies have been made on the effects of an intramuscular injection of aminopterin on the crypts of Lieberkühn in rats. A decrease in the mitotic counts was accompanied by a rapid increase in the number of abnormal cells present in the epithelium of the crypt. Three hours after administration of the aminopterin, an almost complete absence of true metaphase chromosoms was found. By 24 hours, a partial return towards normal mitotic activity was observed but the number of abnormal cells present was still very high. It is suggested that the mitotic changes are in keeping with the conclusion of Grampa and Dustin (1952) of an arrest at interphase but that a secondary arrest at metaphase cannot be excluded.A morphological feature of some of the abnormal cells was the presence of a Feulgen positive granule in the cytoplasm, which by electron microscopy was also shown to contain many cytoplasmic constituents. It is suggested that material is lost from the nucleus and incorporated into a granule in the cytoplasm. A possible explanation of the purpose and function of the granule, as a means of disposing of unwanted or aberrant material, is put forward. Acknowledgements. I am grateful to Professor R. J. Brocklehurst for his continued interest and support of this work, and to the Stage II, B. Sc. students (1964) who counted the cells in many of the specimens as a laboratory exercise. My thanks are also due to Mr. J. Clements for technical assistance.     

D-Amino acid dehydrogenase of Escherichia coli K12: positive selection of mutants defective in enzyme activity and localization of the structural gene

Summary A method for the positive selection of dadA mutants defective in Dolor-amino acid dehydrogenase has been devised. It consists in isolating mutants resistant to -chroro-Dolor-alanine and screening for mutant colony color on a special agar medium. All 70 Escherichia coli K12 dadA mutants isolated either by this method or by other selection procedures map at a locus which is near to hemA and closely linked with dadR. Since some of the dadA mutants are thermosensitive in Dolor-methionine utilization in vivo and have thermolabile Dolor-amino acid dehydrogenase in vitro, it is proposed that the dadA gene codes for the enzyme structure. The broad substrate specificity, apparent membrane localization, inducibility by alanine, and repressibility by glucose strongly suggest that the Dolor-amino acid dehydrogenase coded by the dadA gene is a species variant of the enzyme described under the same name in Salmonella typhimurium. It may be identical or homologous with the enzymes described under the names alaninase, Dolor-alanine oxidase or Dolor-alanine dehydrogenase in E. coli K12 or B.     

On the invagination of the gastrula

Conclusions An experimental study of the problem of gastrulation has yielded evidence which shows that the present prevailing theories are inadequate to account for the facts.Especial attention has been given to the theory ofAssheton, according to which the geometrical relation of nuclei to the cells in the blastula is of fundamental importance to invagination. It was found that an excess of calcium added to the sea water in which the cultures ofS. purpuratus were raised caused a displacement of the nuclei to the inside so that they appeared at the edge of the blastocoele. Lithium larvae on the other hand showed the nuclei disposed toward the periphery in the cells of the blastulae. Since, however, nuclear position did not uniformly correspond to invagination or evagination as the case happened to be, the view that the position of the nuclei determines invagination had to be given up.A modification ofAssheton's view is suggested, namely, that invagination is caused by cell bridges asymmetrically placed. The eccentric attraction between the cells at the vegetal pole therefore presumably depends upon physical structures and not, asAssheton supposed, upon an attraction between the nuclei.I am glad to express my thanks to MissWinnefred Bradway and Mr. S. H.Whong for their assistance in preparing sections and making sketches, and to Mr.Henry Hill of the Yaquina Head Light House for his kindness and hospitality which made part of the work possible.Aided by a grant from the research fund of the University of Oregon.     

An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extremehalophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by l-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, l-tryptophan inhibited activity while l-tyrosine, l-methionine, l-leucine, and l-isoleucine activated the enzyme. l-Isoleucine and l-phenylalanine were effective at M levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by -2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by l-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by l-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.     

Experimental evidence for the adaptive value of sexual reproduction

It is generally believed that recombination by sexual reproduction is unfavourable in constant environments but is of adaptive value under changing environmental conditions. To test this theory, experimental populations of yeast (Saccharomyces cerevisiae) were set up and maintained at different levels of environmental heterogeneity. Recombination was estimated by determining sporulation rates. Sporulation rates first increased in populations living in highly variable environments, but after some time began to decrease. The decrease started last and was slowest in populations which were maintained under the same conditions for a sufficiently long time, to allow some adaptation of the gene pool to the respective environment. Patterns of genotypic variability could not be interpreted in such simple terms, but there was a statistically significant correlation between sporulation rate and genotypic variability. This correlation is to be expected because recombination generates genotypic variability. Summing up, recombination by sexual reproduction is advantageous in changing environments if the population can track the changes in the environment by changing its genotypic structure.     

A polymorphism for heterochromatic supernumerary segments in Chorthippus parallelus

Supernumerary heterochromatic segments have been found in the S₈ bivalent of two populations of Chorthippus parallelus. These segments occur both in the heterozygous and the homozygous states. In both populations the frequencies of basic homozygotes, structural heterozygotes and structural homozygotes conform to a Hardy-Weinberg distribution. In the structurally heterozygous and homozygous states there is a significant increase in the chiasma frequency of the bivalents other than the S₈ itself. It is suggested that the adaptive role of these supernumerary segments can be explained in terms of this interchromosomal effect.To Professor J. Seiler in commemoration both of his 80th birthday and his many distinguished years of cytological service.