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Author: Jianbo Zhang
( Inserted on 12/04/2009 - 6061 Reads)

A new mechanism of the generation of new genes is presented in the animation. Ac/Ds transposition requires a pair of one Ac/Ds 5′ end and one Ac/Ds 3′ end. In standard transposition, the Ac/Ds 5′ and 3′ ends are part of a single transposon, and the outcome of transposition is the excision of the element from a donor site and insertion into a target site. However, transposition reactions can also involve the 5′ and 3′ ends of different Ac/Ds elements, which can be in either a direct or reversed orientation with respect to each other. These alternative transposition events can generate deletions, duplications, inversions, reciprocal translocations, and other sequence rearrangements. These chromosomal rearrangements can generate new chimeric genes and alter the expression of genes near the breakpoint, which could promote the fixation of chromosomal rearrangements during evolution. This work is published in PLoS Genet. 2006 October; 2(10): e164. http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.0020164

This work was supported by the National Science Foundation under awards 0110170 and 0450243. The animation was generated using Adobe Flash Pro. Resolution was lost when converting the animation into a format compatible with youtube, a high-resolution (smaller-sized file) animation can be found on http://jzhang.public.iastate.edu/ES.swf

Author: Arunika Gunawardena
( Inserted on 28/03/2009 - 6331 Reads)

Perforation formation in the aquatic lace plant leaf is a unique and fascinating example of developmental programmed cell death (PCD). This unique plant is an excellent model for studying developmental PCD in vivo. Here we demonstrate some cellular changes that occur in lace plant leaf cells during the late stages of PCD using a 15 min time-lapse video (played at 50x speed). A rapid shrinkage of the nucleus and cessation of cytoplasmic streaming likely infers tonoplast rupture; the Brownian motion of condensed, white chloroplasts continues, but is soon followed by the collapse of the plasma membrane. Note the novel chloroplast ring formation around nuclei commonly observed in late stage lace plant PCD. Wright, H., van Doorn W., and Gunawardena, AHLAN (2009). In vivo study of developmental programmed cell death using the lace plant (Aponogeeton madagascariensis; Aponogetonaceae) leaf model system (Appendix S5 [online]), American Journal of Botany 96(5) 865-876.

Author: Daniel von Wangenheim
( Inserted on 12/04/2009 - 13453 Reads)

The miracle of life relies in its cells.

The root hair is one of the fastest growing cells in the plant. To allow this rapid growth, continuous delivery of membrane and cell wall material to the growing tip of the hair cell is required. A component part of this material is protein, which is synthesized by ribosomes along the Endoplasmic Reticulum, modified in the Golgi apparatus and packaged into vesicles. The vesicles are finally delivered to the plasma membrane by motor proteins along the cytoskeleton. How do vesicles find their target membranes? The specificity of target recognition is mediated by the interaction of v-SNARE proteins on the vesicle surface with t-SNARE proteins on the target membrane. Among others, small G-proteins regulate this process. One group of small G-proteins is the so-called RabGTPases.

To visualize the distribution of such a RabGTPase proteins within the cells, they are tagged with the Green Fluorescent Protein. The video shows the germination of Arabidopsis thaliana seeds, zooming in on the root hairs, which display movement of fluorescent vesicles through the cytoplasm, and finally one can see an animation of myosin VI motor proteins dragging the fluoresently marked vesicles along actin filaments.

Author: Debbie Swarthout
( Inserted on 12/04/2009 - 6758 Reads)

This video clip is a description of the genetic changes that can occur during the life cycle of flowering plants. The clip was made as a visual aid for instructors and students of introductory plant biology when studying the evolutionary history of plant life on earth. The main objective is to provide a visualization of the main processes that occur during the genetic diversification in the cohort of seed that is produced in each generation. A great emphasis was placed on explaining why alternation of generations in flowering plants brings about genetic variation in the offspring of the next generation of plants. A suitable narration was blended with music and digital art to show the important processes that can occur during seeds germination, flower and seed production. Time-lapse photography was used to show growth and development during germination and flower production of a few plant species. Light micrographs of prepared slides of various anatomical stages of flower development were combined with botanical photographs that were taken on various trips to interesting botanical gardens in South Africa. Water-color painting and digital editing in Adobe Photoshop (Elements version 7.0) were used to link various concepts together as we made our journey through the processes that occur during the sexual reproduction and genetic diversification of the flowering plants. The music pieces were original compositions using a classical guitar and resonator bars.

Author: Zach Jarou
( Inserted on 14/04/2009 - 30887 Reads)

This video tutorial demonstrates how to use Photoshop to measure leaf area, an important metric for use in plant growth analysis. The purpose of this tutorial is to demonstrate how to use Adobe Photoshop to determine the exposed surface area of plants leaves for use in growth analysis research. Let's get started.

Using the marquee tool, located to the left of the image viewing area, make a rough selection of the area of interest. In our case, we will be selecting three plants of the same phenotype for which we would like to obtain an average size. Next, open the color range tool, located under "Select" on the Main Menu. Once the dialogue box is open, ensure that the radio button is on "Selection" and the Selection Preview drop-down is set to "Black Matte." Begin by making an initial selection of the plant using the eyedropper tool in either the image viewing window or the color range dialogue box. Notice how the selection gradient changes depending upon which part of the plant is selected first. To capture the full area of the leaf, hold down shift & click the darker areas of the leaves. Notice how the eyedropper has changed to include a plus sign. The selection area can also be increased by dragging the "Fuziness" bar to the right. Do this slowly so that you can continue to add hues along the way. Finally, to ensure no tones are left out, increase the fuziness as much as you can, until the point where unwanted regions of the image are added to the selection, such as the growing container or soil artifacts. To finalize the selection, simply click the "OK" button. Now that the leaves have been selected, it is necessary to find the number of pixels within the selection. This can be done using the histogram located in the palettes toolbar on the right hand side of the screen. Ensure that the view is in "Expanded" mode with the "Show Statistics" option selected. The number of pixels can be found in the bottom left hand corner of the statistics display. In this case, there are ______ pixels selected. Occasionally, the histogram will display an error message, indicating that it needs to be regenerated with uncached data. This is easily remedied by selecting the refresh above the histogram & must be done to ensure that an accurate pixel count is obtained. Finally to convert pixels into physical units, we must measure the number of pixels of an object within the image for which the real-world size is already known; in our case this is a white block with a size of 4 square centimeters. By selecting this square with the marquee tool, we can see that it is _______pixels.

Author: Franz Hoffmann
( Inserted on 17/04/2009 - 10396 Reads)

Plant cells are shaped by rigid cell walls. Osmotic forces press the plasma membrane tightly against these walls. The walls can be removed with enzymes. The remaining structures, the protoplasts, are now bordered by the plasma membrane. Since the shaping force of the wall is missing, isolated plant protoplasts are usually perfectly spherical in shape as a result of non-directional osmotic forces. However, not all isolated plant protoplasts are spherical. Through cytoplasmic streaming, cytoplasmic strands continuously change their length, branching and attachment, and as a result the shape of the protoplast may change. A laser microsurgery experiment provides proof that the inner tension built by the cytoplasmic network is moving the cell. A laser beam focused at a cytoplasmic strand will cut the strand and cause the network to collapse without destroying the integrity of the cell. As a result osmotic forces can take over and round the protoplast. Moving around is not an option for most cells of higher plants, and cytoplasmic streaming serves normally the intracellular transport - but they have not totally lost the basic skills that would enable them to move.

Author: John Davis
( Inserted on 17/04/2009 - 6235 Reads)

This is a Texas Tech University's entry for the Chlorofilms.org YouTube contest. Scientists at Texas Tech are trying to determine if plants can retain information about past experiences in small R...

Author: Karl Haro von Mogel
( Inserted on 16/03/2009 - 7465 Reads)

Pollination Methods: Cucurbits is part of a series of step-by-step, instructional videos on how to make controlled crosses with plants. The videos will cover a wide range of techniques applicable to open-pollinated, insect-pollinated, and self-pollinated crops, ranging from agronomic to horticultural species. The controlled pollination method videos are technically-oriented and are targeted to high school and college students with some background in plant biology. They will be useful for students learning about plant breeding methods, and may be of interest to backyard and commercial hybridizers of various crops. The cucurbit video explains the biology and origin of common cucurbit species, which ones can cross with each other, and how to make controlled crosses yourself. Some of the methods commercial seed producers use are mentioned, and finally, the genetics of seedless watermelons are explained. Additional Information - Also available in a higher quality at: http://www.wisconsinplantbreeding.com/educators/videos/pollination-methods-cucurbits/

Author: Burkhard Schulz
( Inserted on 12/04/2009 - 3150 Reads)

This video is a visual 10 step instruction manual how to use a pressure bomb for measuring water pressure in the xylem of transpiring leaves. It is an entry for the www.ChloroFilms.org video competition. Water in the xylem is under negative pressure. This tension can be measured by a “pressure bomb”. Tension pressure in a non-transpiring leaf is “equivalent” to water potential of cells surrounding the xylem (mesophyll cells), because the xylem’s osmotic potential is negligible. A single leaf is sealed in the pressure chamber with the cut surface protruding through a rubber stopper. Pressure is applied to the shoot from a tank of compressed air (or nitrogen) until xylem sap appears at the cut ends of the xylem. The hydrostatic pressure inside the xylem elements is then identical to the applied external pressure. The amount of pressure that must be applied to force water out of the leaf cells into the xylem is regarded as equal to the xylem tension when the leaf was cut from the plant.

This video was created to serve as visual instruction in a Plant Physiology course (HORT301) at Purdue University. Videos are powerfull tools to present experimental approaches, research methodology, and theory that the students have to deal with during their course work. This is especially true for experimental components of plant biology courses where students have to work hands-on with material and equipment which is often new to them. This way, additional background material that explains necessary equipment, concepts and essential steps of an experimental procedure can be made accessible as a video reference on course websites. This will engage students in critical discussion with contemporary research and permit its presentation to peers in the course and the public. The idea is for students to translate basic scientific information into a more popular visual language, that engages the students. The objective is not to let the students do the work of generating teaching material, but involve them in a process of active and action learning which enhances the study success and connects the students with the course and the teaching content more intensely. This video was produced with the help of graduate students who were involved as teaching assistents in this course. Video camera equipment was supplied by Purdue University’s Digital Learning Collaboratory at ITaP (http://dlc.purdue.edu/cs4.cfm) and through an Instructional Innovation grant by the College of Agriculture. Editing of the material and production of musical score has been done by Diana Nucera (Video artist, Detroit, MI). More background information on our video productions can be found at http://www.hort.purdue.edu/hort/academics/HortMedia/hortmedia.html.

Author: Stephen Saupe
( Inserted on 14/04/2009 - 5667 Reads)

This movie depicts the response of Selaginella lepidophylla to drying and moisture.

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