Tubes From Pollen Headed for an Egg Cell

Pictured here are pollen tubes emerging from pollen grains on the stylar surface of Austrobaileya scandens, a vine endemic to the Australian rainforest. The stigma is the part of the flower that receives pollen, and it can be very far from the egg. The structures have been stained with aniline blue in order to visualize callose, a type of carbohydrate made up of sugar molecules that can be rapidly synthesized and secreted in plant cell walls. Callose stains bright yellow-green under ultraviolet light. The colors are created by the mix of fluorescence with faint background bright light to highlight the structural features of the pollen wall and stigma.

A Zeiss Axioplan II light microscope equipped for fluorescence was used to both fluoresce and backlight the image at the same time. The pollen tubes exit the pollen grain from a slit-like opening that can be most clearly seen in the pollen grain on the right side. The tubes are about 10 microns (one one hundredth of a millimeter) wide, but they can grow well over 6 millimeters to reach an egg, all in less than 24 hours after pollination, which is when this photo was taken.

This research was performed by Joseph Williams, an evolutionary biologist at the University of Tennessee who is investigating why flowering plants have diversified so much more quickly than cone-bearing plants. There are an estimated 270,000 known species of angiosperms (flowering plants) but only about 900 species of gymnosperms (nonflowering plants like conifers, cycads and ginkgoes).

Williams is studying the nature of this process of getting sperm to the egg in a group of early-diverging lineages of flowering plants in order to find out if there are commonalities in the fertilization process among them. Such commonalities would suggest ancient features of the fertilization process that cannot be studied in fossil lineages. To learn more about Williams' research, visit his website Here. [Research supported by National Science Foundation grant DEB 06-40792.]

(Date of Image: August 2007)

Credit: Joseph H. Williams, Department of Ecology and Evolution, University of Tennessee

NASA to Hold News Conference on Asteroid Mission Results

Dwayne Brown

Headquarters, Washington     

202-358-1726

dwayne.c.brown@nasa.gov

 

Jia-Rui Cook

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-0850

jccook@jpl.nasa.gov

WASHINGTON -- NASA will host a news conference on Thursday, May 10, at 2 p.m. EDT to present a new analysis of the giant asteroid Vesta using data from the agency’s Dawn spacecraft.

The event will be held in the James E. Webb Auditorium at NASA Headquarters located at 300 E St. SW in Washington. The event will be broadcast live on NASA Television and streamed on the agency’s website. The journal Science has embargoed the findings prior to the news conference.

The panelists for the briefing are:

-- Carol Raymond, Dawn deputy principal investigator, NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

-- Harry McSween, chair, Dawn surface composition working group, University of Tennessee, Knoxville

-- Vishnu Reddy, Dawn framing camera team member, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, and the University of North Dakota, Grand Forks

-- David O’Brien, Dawn participating scientist, Planetary Science Institute, Tucson, Ariz.

-- Maria Cristina De Sanctis, Dawn co-investigator and visible and infrared mapping spectrometer team lead, Italian National Institute for Astrophysics, Rome

     

Reporters unable to attend the briefing in-person can ask questions from other NASA centers, by telephone or via Twitter using the hashtag #asknasa. To obtain dial-in information, journalists must send their name, affiliation and telephone number to dwayne.c.brown@nasa.gov by noon on May 10.

For NASA TV streaming video, downlink and scheduling information, visit http://www.nasa.gov/ntv.

The event will be streamed live on Ustream with a moderated chat available at http://www.ustream.com/nasajpl2.

For more information about Dawn, visit http://www.nasa.gov/dawn.

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Studying Sundew Plant Adhesive (Image 2)

A sundew plant. Sundew plants are carnivorous, consuming insects by capturing them with small adhesive balls on the ends of their tentacles.

Mingjun Zhang of the Nano Biosystems and Bio-mimetics Lab at the University of Tennessee is studying the adhesive properties of sundew plants on the nanoscale, which may lead to improvements in medical replacement operations such as hip replacements. In a paper published in the Journal of Nanobiotechnology, Zhang's group reported that the naturally occurring nanofibers and nanoparticles from the secreted adhesive of the sundew show a high compatibility for attaching cells.

The sundew's adhesive has remarkable elasticity, stretching to 1 million times its normal size (most rubber bands can only stretch to six times their original size). Such elasticity would make the adhesive dew secreted from the plant an effective choice for coating replacement body parts, regenerating dying tissues, healing wounds and improving synthetic adhesives. It is also economical--it's so sticky and elastic that less than a microliter (smaller than the period at the end of a sentence) would cover 25 millimeters squared (or the size of George Washington's face on a dollar bill). Zhang's research was supported in part by grants from the National Science Foundation (NSF) (CMMI 10-29953 and CBET 09-65877).

To learn more about this research, see the NSF Discovery story from October 2011, The Nanotechnology of Sundew and English Ivy. (Date of Image: 2010)

Credit: Pelagie Favi, Samantha Tracht, University of Tennessee

Studying Sundew Plant Adhesive (Image 1)

A sundew plant. Sundew plants are carnivorous, consuming insects by capturing them with small adhesive balls on the ends of their tentacles.

Mingjun Zhang of the Nano Biosystems and Bio-mimetics Lab at the University of Tennessee is studying the adhesive properties of sundew plants on the nanoscale, which may lead to improvements in medical replacement operations such as hip replacements. In a paper published in the Journal of Nanobiotechnology, Zhang's group reported that the naturally occurring nanofibers and nanoparticles from the secreted adhesive of the sundew show a high compatibility for attaching cells.

The sundew's adhesive has remarkable elasticity, stretching to 1 million times its normal size (most rubber bands can only stretch to six times their original size). Such elasticity would make the adhesive dew secreted from the plant an effective choice for coating replacement body parts, regenerating dying tissues, healing wounds and improving synthetic adhesives. It is also economical--it's so sticky and elastic that less than a microliter (smaller than the period at the end of a sentence) would cover 25 millimeters squared (or the size of George Washington's face on a dollar bill). Zhang's research was supported in part by grants from the National Science Foundation (CMMI 10-29953 and CBET 09-65877).

To learn more about this research, see the NSF Discovery story The Nanotechnology of Sundew and English Ivy. (Date of Image: 2010)

Credit: Pelagie Favi, Samantha Tracht, University of Tennessee

12th Annual Human Remains Recovery School

During the week of March 14, 2011, the Knoxville Division hosted the 12th annual Human Remains Recovery School in partnership with the University of Tennessee at Knoxville (UTK) and the University of Tennessee Medical Center. Evidence Response Team members from FBI field offices across the country studied forensic science at the UTK Anthropology Research Facility and were provided both lecture and hands-on practical training by subject matter experts such as forensic entomologists, forensic anthropologists, pathologists, and odontologists. The practical exercises involved the recovery of actual human remains as well as documentation and mapping exercises. Pictured are members of the 2011 class.