Analysis of sclerotia and conidia formation in the filamentous ascomycete Aspergillus flavus suggests that formation of these structures is cell density dependent. Specifically, high cell density cultures yield conidia, whereas low cell density triggers sclerotia formation. Review the structure and function of conidia and sclerotia, and formulate a hypothesis to explain why their development would be regulated in a density-dependent manner. List several specific testable predictions based on your hypothesis.
Read the original paper: Horowitz-Brown, S., et al. 2008. Morphological transitions governed by density dependence and lipooxygenase activity in Aspergillus flavus. Appl. Environ. Microbiol. 74:5674.
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Chapter 25 Solutions
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- Stinkhorn mushrooms embed their spores in a foul-smelling material that is attractive to flies. Explain why this occurs and where else this is observed (what is this referred to in other groups)?arrow_forwardIdentify: 1. A part of the chloroplast in the green algae important in carbon dioxide fixation and for production and concentration of starch. 2. Subgroup of Kingdom Viridiplantae with cytokinesis marked by phragmoplast formation. 3. Subgroup of Kingdom Viridiplantae with centrioles and closed mitosis. 4. Chloroplast morphology of the Chlamydomonas. 5. The characteristic life cycle of Chlamydomonas. 6. Sexual reproduction in Chlamydomonas characterized by the fusion of morphologically similar gametes. 7. Sexual reproduction in Volvox characterized by the fusion of a large, immotile female gametes with small, motile male gametes. 8. The common name of the genus Chara. 9. The specific structure that produce the male gametes in Chara. 10. The specific structure that produce the female gametes in Chara.arrow_forwardThis is a longitudinal section of a Marchantia sp. gametophyte body. Label the following structures: A.) thallus, B.) gemma cup, C.) gemmae.arrow_forward
- Zygomycete bread molds such as Rhizopus stolonifer (black bread mold) produce sporangia in both sexual and asexual reproductive cycles. Which of the following do the sexual sporangia of Rhizopus stolonifer originate from (i.e. what does the sporangia grow out of)? Select one: O a. from the aseptate hyphae O b. from the zygosporangium O c. from the substrate O d. from the gametangiaarrow_forwardDefine germ pore. Differentiate between amyloid, dextrinoid (pseuodamyloid), and inamyloid reactions. Describe the reactions that result in cyanophilous structures and metachromatic structures. Describe the mitic system of mushrooms.arrow_forwardSuperficially, Apiosporina morbosa (causal agent of black knot of cherry) appears morphologically similar to members of the Xylariales as both produce melanized stroma. However, the former is found in the Class Loculoascomycetes while the latter are found in the Class Pyrenomycetes. Why? Discuss the main differences.arrow_forward
- Find the large nucleus located near the cell. Make several outline drawings to illustrate the successive changes of 1. shape of the amoeba. Make drawings of the Amoeba you observe, and label its structures. C O O liko mer 0 AS 6 0 O Paramecium -- Paramecia are quite large, straw-colored, slipper-shaped and move rapidly, and they are thus very noticeable. If there are Paramecia in your field of view you probably will recognize them immediately. Often, however, students do have difficulty both finding a Paramecium, and after they have found one, making it move slowly enough so they can study it at high magnification. The trick to finding a Paramecium is to scan the entire slide quickly using the scanning lens. Then, if you do not find one, make a new slide and search again. Often, Paramecia tend to move to the edges of the coverslip, and even "escape" the coverslip at its edges. The trick to slowing the Paramecia is to mix a drop of methyl cellulose with a drop of the cell culture, as…arrow_forwardThe figure below shows the life cycle of the fungus Neurospora. The adult stage of the Neurospora is a multicellular haploid. a) Between which two stages of the Neurospora life cycle (shown above) do most mitotic cell division oarrow_forwardidentify the following:1. The sexual fruiting body in the genus Coprinus.2. The specific layer of the lichen body or thallus that is photosynthetic in function.3. A club shaped structure that directly produce haploid spores in the Coprinus sp.arrow_forward
- Compare and contrast the production of a planttumor by Agrobacterium tumefaciens and a root noduleby a Rhizobium species. In what ways are thesestructures similar? In what ways are they different?Of what importance are plasmids to the developmentof both structures?arrow_forward4.1 Attine ants cultivate a garden of Leucocoprini fungus for its nourishment, while the fungus receives all its requirements for growth from the ants. The ants also promote the growth of an actinomycete, Pseudonocardia, which produces an antimicrobial compound that inhibits the growth of another fungus, Escovopsis which is a parasite of Leucocoprini. Check all the applicable interactions observed in this multi-species interaction from the choices givenarrow_forwardObelia (the one that is being referred too below) In the colony, how well integrated are the feeding polyps, the repudctive polyps, and the maim axes? What strucutres are haploid and which are diploid? Whats the function of the various strucutres and what are the similarties and differences in the fuctions of the colonial vs. the medusa phases? Does obelia have an alternation of genrations like that observed in the plants earlier this semster? Is obelia diploblastic or triploblastic? does it have coelom? Whats the similarties and differences are there between obelia and grantia? what are obelias ecological attributes and ecnomic uses?arrow_forward