As more complete genomes are sequenced, phylogenetic analysis is entering a new era — that of phylogenomics. One branch of this expanding field aims to reconstruct the evolutionary history of organisms on the basis of the analysis of their genomes. Recent studies have demonstrated the power of this approach, which has the potential to provide answers to several fundamental evolutionary questions. However, challenges for the future have also been revealed. The very nature of the evolutionary history of organisms and the limitations of current phylogenetic reconstruction methods mean that part of the tree of life might prove difficult, if not impossible, to resolve with confidence.

/pdf/phylogenomics-and-the-reconstruction-of-the-tree-of-life-4ket7rjhwa.pdf

Phylogenomics and the reconstruction of the tree of life.

Microorganisms are able to utilize nitrogen (N) from a wide range of organic and mineral compounds. In this paper, we review the current knowledge about the regulation of the enzyme systems involved in the acquisition of N and propose a conceptual model on the factors affecting the relative importance of organic and mineral N uptake. Most of the N input into soil is in the form of polymers, which first have to be broken down into smaller units by extracellular enzymes. The small organic molecules released by the enzymes can then be taken up directly or degraded further and the N taken up as ammonium (NH4+). When NH4+ is available at high concentrations, the utilization of alternative N sources, such as nitrate (NO3−) and organic molecules, is generally repressed. In contrast, when the NH4+ availability is low, enzyme systems for the acquisition of alternative N sources are de-repressed and the presence of a substrate can induce their synthesis. These mechanisms are known as N regulation. It is often assumed that most organic N is mineralized to NH4+ before uptake in soil. This pathway is generally known as the mineralization-immobilization-turnover (MIT) route. An advantage of the MIT route is that only one transporter system for N uptake is required. However, organic N uptake has the advantage that, in addition to N, it supplies energy and carbon (C) to sustain growth. Recent studies have shown that the direct uptake of organic molecules can significantly contribute to the N nutrition of soil microorganisms. We hypothesize that the relative importance of the direct and MIT route during the decomposition of residues is determined by three factors, namely the form of N available, the source of C, and the availability of N relative to C. The regulation system of soil microorganisms controls key steps in the soil N cycle and is central to determining the outcome of the competition for N between soil microorganisms and plants. More research is needed to determine the relative importance of the direct and MIT route in soil as well as the factors affecting the enzyme systems required for these two pathways.

Pathways of nitrogen utilization by soil microorganisms - a review.

Regulation of trehalose mobilization in fungi.

Inorganic fertilizers containing ammoniacal nitrogen or formulations releasing this form of N in the soil are most effective for suppressing nematode populations. Anhydrous ammonia has been shown to reduce soil populations of Tylenchorhynchus claytoni, Helicotylenchus dihystera, and Heterodera glycines. The rates required to obtain significant suppression of nematode populations are generally in excess of 150 kg N/ha. Urea also suppresses several nematode species, including Meloidogyne spp., when applied at rates above 300 kg N/ha. Additional available carbon must be provided with urea to permit soil microorganisms to metabolize excess N and avoid phytotoxic effects. There is a direct relation between the amount of "protein" N in organic amendments and their effectiveness as nematode population suppressants. Most nematicidal amendments are oil cakes, or animal excrements containing 2-7% (w:w) N; these materials are effective at rates of 4-10 t/ha. Organic soil amendments containing mucopolysaccharides (e.g., mycelial wastes, chitinous matter) are also effective nematode suppressants. Key words: amendments, biological control, fertilizers, microbial ecology, nonchemical control, pest management, waste management.

/pdf/organic-and-inorganic-nitrogen-amendments-to-soil-as-30jw3jw9g8.pdf

Organic and inorganic nitrogen amendments to soil as nematode suppressants.

Bartnicki-Garcia, S. (Rutgers, The State University, New Brunswick, N. J.) and Walter J. Nickerson. Induction of yeastlike development in Mucor by carbon dioxide. J. Bacteriol. 84:829-840. 1962-Vegetative development of Mucor rouxii may follow either one of two patterns of morphogenesis (mold-yeast dimorphism), depending on the atmosphere of incubation. Under air or N(2), a filamentous (moldlike) growth developed, commonly followed by fragmentation of hyphae into spherical cells (arthrospores). Introduction of CO(2) into an anaerobic atmosphere induced development of spherical, budding yeastlike cells. Anaerobically, a pCO(2) of 0.3 atm or higher produced a purely yeastlike development. Presence of oxygen annulled the effect of CO(2) On germination, spores gave rise directly to either type of vegetative development, depending on the atmosphere of incubation. Induction of yeastlike development by CO(2) occurred in five strains of M. rouxii, and in most species of Mucor tested. M. subtilissimus, however, did not require CO(2); it developed in the yeastlike form under anaerobic conditions. Strains of Rhizopus grew under CO(2), but developed only filamentous mycelium. Members of other genera of Mucorales were unable to grow under an atmosphere of CO(2).

Induction of yeastlike development in mucor by carbon dioxide

Never doubt with our offer, because we will always give what you need. As like this updated book, you may not find in the other place. But here, it's very easy. Just click and download, you can own the physiology of fungi. When simplicity will ease your life, why should take the complicated one? You can purchase the soft file of the book right here and be member of us. Besides this book, you can also find hundreds lists of the books from many sources, collections, publishers, and authors in around the world.

Physiology of Fungi

There are a number of illustrations and figures which, on the whole, are quite well selected and of good quality. In some instances, the material presented happens to represent an area over which considerable controversy exists at present and, unfortunately, both sides of the controversy do not receive the same treatment. A student perusing this book should be aware of this so that he may keep an open mind. It would, of course, be beyond the scope of such a conference to try to present all sides of the subject completely, for the book would then become unwieldy in size. On the whole, this is a very useful and informative study which provides and conveys a good impression of the current work being done on the subjects covered.

Perspectives and Horizons in Microbiology.

ology. He also recognizes the role of chemotherapy, endocrinology, and improved instruments for observing the patient. His survey of current conditions is more detailed. Lord Horder is not only a physician interested in life and death, but also an adherent of such related causes as birth control and cremation. His interest in eugenics and biological control of illness has led him to try to get legal sanction for \"... voluntary sterilization of carriers of hereditable disease.....\" He feels voluntary euthanasia is a matter for public rather than professional concern, though he expresses his own doubts as to its value. He advocates \".. . an extended pathology. . .\" to include new points of view dealing with environmental and psychosomatic factors, in preference to establishing these as special branches of medicine. He criticizes the National Health Service in some detail, citing several familiar points: the institution of the program by immediate fiat, continuing budgetary deficits, and the neglect of the general practitioner in planning functioning units. On the other hand, Lord Horder concedes the need for centralized direction of coordinated health services, and argues ideally for a more gradual approach to government sponsorship. He feels that this might have been done through a progressive increase in subsidization of hospitals and medical schools and an expansion of prevailing health insurance. Though hardly to be defined as an historical summary, this little volume is a fluent and entertaining expression of one man's career. This volume is a collection of papers read at the Fourth Symposium of the Society for General Microbiology which was held in London in April 1954. The subject under discussion are those microorganisms which utilize carbon dioxide as their chief or only carbon source. These organisms derive their energy either from the absorption of light or from the oxidation of inorganic compounds such as hydrogen, ammonia, sulfur, and ferrous salts. Van Niel has shown that a strict definition of \"autotrophic\" and \"betero-trophic\" is impossible, we must be content to consider organisms which primarily fix carbon dioxide or which primarily dissimilate organic compounds. In recent years we have learned much concerning the mechanism of photosynthesis, while other autotrophic modes of life have received less attention than they deserve. Biologists can therefore be grateful to the Society for General Microbiology for sponsoring a symposium which treats autotrophy in the proper perspective: a fundamental biological problem, of which photosynthesis is only one specialized …

Wolf Vishniac

Papers

Physiology of Fungi

Perspectives and Horizons in Microbiology.

Autotrophic Micro-Organisms