Tag: microtomography

The Secret to Drought Tolerance Lies in a Lilac Crypt

The Secret to Drought Tolerance Lies in a Lilac Crypt

Growing in the wild and in gardens, from Humboldt forests all the way to San Diego chaparral, the California lilac is a plant genus divided into two groups, Ceanothus and Cerastes. Ceanothus are associated with moister climates, whereas Cerastes have adaptations for surviving drier conditions. While both categories have stomata, pores that open and close to regulate CO2 intake, Cerastes pores have a special configuration—they’re housed in leaf indentations called stomatal crypts.

“Stomatal crypts are very rare among plants,” said Joseph Zailaa, Yale doctoral student and the corresponding author on a study of the California lilac. “This anatomical structure is thought to help provide drought tolerance.”

Using Beamline 8.3.2 at the Advanced Light Source (ALS), his research team has now uncovered secrets from the Cerastes crypts. “Classic microscopy techniques only give us a 2D picture of the leaf’s internal structure,” said Zailaa, “but microtomography at the ALS allowed us to image and view these crypts in three dimensions for the first time.” They also obtained 3D models of hydrated and dehydrated samples, allowing the researchers to observe the plants’ responses to drought.

Many arid-climate plants are drought tolerant. “They maintain functions such as water transport and photosynthesis despite the onset of drought, which uses up the plant’s water reserves,” Zailaa explained. California lilacs have developed an additional adaptation: drought avoidance. “Their stomata close and they shut down most of their function at the onset of drought to conserve water reserves,” Zailaa described. “This delays the plant from experiencing damage caused by excessive dehydration,” he added. His team’s work showed how stomatal crypts provide even further benefits to Cerastes. The researchers found that Cerastes had greater water storage capacity and water use efficiency than Ceanothus.

Read more on ALS website

Image: Ceanothus megacarpus is a member of the Cerastes subgroup of California lilacs. This species has a characteristic associated only with Cerastes, the stomatal crypts. In this 3D visualization obtained at ALS Beamline 8.3.2, white arrows indicate stomata, which are found exclusively within the crypts, or indentations in the leaf. The stomatal crypts help Cerastes species survive drought. Scale bar is 200 µm.

Credit: Craig Brodersen and Joseph Zailaa/Yale School of the Environment; Leila Fletcher/Southern Oregon University Biology Department

Trilobite’s last meal revealed by synchrotron microtomography

Trilobite’s last meal revealed by synchrotron microtomography

The gut contents of a 465 million-year-old fossilised trilobite were imaged at the ESRF using synchrotron microtomography technique. The results, published in Nature, shed light on the feeding habits and lifestyle of one of the most common and well-known fossil arthropods. The research fills a fundamental gap in the understanding of trilobite ecology and their role in Paleozoic ecosystems.

Trilobites are among the most iconic of fossils and formed a highly diverse, abundant and important component of marine ecosystems during most of their 270-million-year-long history from the early Cambrian period to the end Permian period. More than 20,000 species have been described to date.

Despite numerous fossil specimens, the feeding habits of these animals have had to be inferred indirectly, because no known fossil specimens with internal gut contents have previously been reported. This knowledge gap limits the ability to understand trilobites’ ecological roles, which in turn affects the overall understanding of the ecosystems that they inhabited. A specimen of the trilobite Bohemolichas incola, with partly visible shelly gut contents, was present in a Czech public collection, but the inability to image and identify the individual shell fragments without destroying the fossil limited its research potential.

A team of researchers led by Per Erik Ahlberg at Uppsala University, Sweden, and Valéria Vaškaninová at Charles University, Czech Republic, came to the ESRF to investigate this rare fossil using propagation phase-contrast synchrotron microtomography, at ESRF ID19 beamline. The technique enabled the scientists to non-destructively image all the shell fragments in the gut in 3D and at high resolution. The result was a complete map showing the position and identity of each shell fragment in the gut.

“ESRF played an absolutely pivotal role in this study” says lead author Per Ahlberg, professor at Uppsala University. “The resolution and scan quality it provides – this scan was made on the old ID19 beamline before the upgrade, even better results are possible now – were essential to identify the gut contents, piece by piece. A conventional CT scan would have told us that the trilobite had been eating; only ESRF could tell us what it had been eating.”

Read more on ESRF website

Image: The trilobite Bohemolichas incola. 

Credit: Jiri Svoboda