If you plunge into the warm, blue waters of the Caribbean today, what you’ll see in most regions is actually quite bleak. Where there were once vibrant coral reefs teeming with sharks, groupers, and lobsters, there are now piles of rubble, carpets of green seaweed, and only the meager remains of a once colorful sea of coral.

Over the last 50 years, more than half of all hard corals — colonies of tiny animals called polyps that grow skeletons and build coral reefs — have disappeared in the Caribbean. The picture is even grimmer nearby in the Florida Keys, where coral has declined by 90 percent. As corals die, seaweed often takes over, which can make it hard for the reef to recover…

The small island of Bonaire, however, tells a different story.

East of Curaçao in the south Caribbean, Bonaire is a volcanic island just half the size of Chicago. And within its waters is a bustling marine metropolis. A large reef circles the island with towering, centuries-old corals, where countless creatures reside, from seahorses and sea turtles to hammerhead sharks and rays.

“Bonaire is what a well-functioning, healthy reef should be,” said Sophie McCoy, a marine ecologist at the University of North Carolina Chapel Hill, who researches mats of algae-like bacteria that colonize these ecosystems. “We’ve been studying Bonaire in my lab as an example of how a reef should be functioning.”

…But there’s another potentially critical reason why coral in Bonaire is so abundant: half a century of fishing restrictions. The island banned spearfishing in 1971 and soon after established one of the world’s first marine parks. The park, or marine protected area (MPA), encircles the entire island and prohibits certain kinds of fishing, anchoring, and other activities that can damage coral. Unlike most MPAs in the Caribbean, which fail to limit commercial activities, this park has successfully restrained fishing…

The virtue of MPAs as a coral conservation strategy is surprisingly controversial. What’s clear is that even the strongest protections, whether they prevent fishing, pollution, or any other local impacts, won’t do much for reefs during an extreme heat wave or storm. Such threats don’t care about park boundaries. That’s why some scientists have railed against MPAs as a coral-saving strategy.

“They can’t keep temperatures out,” John Bruno, a marine ecologist at the University of North Carolina Chapel Hill, told me. “They can’t keep climate out.”

READ FULL ARTICLE

If you’ve ever taken a trip to a higher elevation, you know that the air gets thinner as you go up. If you’re not acclimated to the altitude, it can feel harder to breathe. That thinner air also makes it more difficult for birds and airplanes to fly, because it’s harder to produce the lift forces in thinner air. But it turns out that turkey vultures have a way of dealing with that problem.

Researchers observed turkey vultures in flight at different altitudes and found that rather than flapping harder or more rapidly to deal with decreased lift, the turkey vulture exploits the lower drag in thinner air to fly faster, using increased speed to help balance the lift equation. Dr. Jonathan Rader, a postdoctoral research associate in biology at the University of North Carolina Chapel Hill and an author of a report on this research published in the Journal of Experimental Biology, joins SciFri’s Charles Bergquist to explain how flying things work to adapt to different flight conditions.

LISTEN

“…That individual fish have a harder time swimming against eddies “is not exactly shocking,” said Ty Hedrick, a biologist at the University of North Carolina at Chapel Hill who was not involved in the work. “After all, getting knocked around by turbulence in the water is probably going to require some extra energy.”

What was surprising, he said, was that the turbulence didn’t affect the fish in a school at all, a result that suggested the formation was somehow changing the water’s flow. But, at least for now, this finding holds only for giant danio swimming in strictly controlled lab conditions. “This is great,” Dr. Hedrick said, adding, “It’s a start, not a finish.”

READ FULL ARTICLE

The C. elegans hermaphrodite distal tip cell (DTC) leads gonadogenesis. Loss-of-function mutations in a C. elegans ortholog of the Rac1 GTPase (ced-10) and its GEF complex (ced-5/DOCK180, ced-2/CrkII, ced-12/ELMO) cause gonad migration defects related to directional sensing; we discovered an additional defect class of gonad bifurcation in these mutants. Using genetic approaches, tissue-specific and whole-body RNAi, and in vivo imaging of endogenously tagged proteins and marked cells, we find that loss of Rac1 or its regulators causes the DTC to fragment as it migrates. READ MORE

Mechanical and biochemical feedback combine to generate complex contractile oscillations in cytokinesis https://doi.org/10.1016/j.cub.2024.06.037

The actomyosin cortex is an active material that generates force to drive shape changes via cytoskeletal remodeling. Cytokinesis is the essential cell division event during which a cortical actomyosin ring closes to separate two daughter cells. Our active gel theory predicted that actomyosin systems controlled by a biochemical oscillator and experiencing mechanical strain would exhibit complex spatiotemporal behavior. To test whether active materials in vivo exhibit spatiotemporally complex kinetics, we imaged the C. elegans embryo with unprecedented temporal resolution and discovered that sections of the cytokinetic cortex undergo periodic phases of acceleration and deceleration. Contractile oscillations exhibited a range of periodicities, including those much longer periods than the timescale of RhoA pulses, which was shorter in cytokinesis than in any other biological context. Modifying mechanical feedback in vivo or in silico revealed that the period of contractile oscillation is prolonged as a function of the intensity of mechanical feedback. Fast local ring ingression occurs where speed oscillations have long periods, likely due to increased local stresses and, therefore, mechanical feedback. Fast ingression also occurs where material turnover is high, in vivo and in silico. We propose that downstream of initiation by pulsed RhoA activity, mechanical feedback, including but not limited to material advection, extends the timescale of contractility beyond that of biochemical input and, therefore, makes it robust to fluctuations in activation. Circumferential propagation of contractility likely allows for sustained contractility despite cytoskeletal remodeling necessary to recover from compaction. Thus, like biochemical feedback, mechanical feedback affords active materials responsiveness and robustness.

Think of a coral’s skeleton as a house in which tiny algae live and produce nutrients that feed the coral.

That cooperative living arrangement, known as symbiosis, is what Rachel Geyer is studying. As part of her Summer Undergraduate Research Fellowship (SURF), she is trying to understand why some corals grow more complex skeletons, possibly making the coral more resilient. She hopes her findings may help tropical coral species threatened by rapidly warming waters and excess carbon dioxide in the atmosphere.

“Having more skeleton is like increasing the square footage of the house so that more symbionts can live in those nooks and crannies, which is a good thing,” said Geyer. Scientists are looking for traits that increase coral resiliency. “At coral nurseries, when selecting coral to transplant in new coral colonies, they try to repopulate corals with those good traits. The better we can understand what those good traits are, the better those efforts will go.”

Geyer is working in the lab of Karl Castillo, associate professor in the College of Arts and Sciences’ Earth, marine and environmental sciences department (EMES), under the guidance of biology doctoral student Stephanie Peak. The senior from Waxhaw, North Carolina, is majoring in environmental science with minors in journalism and geology. READ MORE

University of North Carolina at Chapel Hill researchers [Duronio Lab] have determined whether a specific chemical modification of a protein that packages the genome called a histone affects gene activity and cell proliferation according to the paper, “Drosophila melanogaster Set8 and L(3)mbt function in gene expression independently of histone H4 lysine 20 methylation,” published in Genes & Development.

In their research, the group found that removing the enzymes responsible for adding a specific histone chemical modification or a protein that binds it disrupts gene activity and cell proliferation. However, the disruptions are not directly due to the chemical modification itself which is the opposite of current models in the field.

“Our study led to a better understanding of genetic regulation mechanisms,” said Bob Duronio, co-author and biology professor. “Such understanding provides foundational information that can help when developing new treatments for diseases like cancer that result from defects in the regulation of gene activity and cell proliferation by targeting the pathways and mechanisms of Set8 that are independent of the histone modification.” READ MORE

Alexander Smith (Allen Hurlbert Lab) used his Summer Undergraduate Research Fellowship to explore how the bugs’ cyclical emergence changed some animals’ feeding habits around the Triangle.

The emergence of millions of cicadas across North Carolina caused a buzz in parts of Chapel Hill and the Triangle this spring as Brood XIX surfaced for the first time in 13 years.

For Alexander Smith, the arrival of the periodical cicadas around Carolina’s campus also presented an opportunity for research.

Smith, a senior biology major, was curious how this year’s addition of millions of bugs would impact the food web dynamics of insects and their predators, including birds, reptiles, arachnids and small mammals.

“When periodical cicadas are introduced into an ecosystem and into a food web, it’s going to alter that food web,” said Smith, who received a Summer Undergraduate Research Fellowship (SURF) grant from the Office for Undergraduate Research to support his work.

A passion for the outdoors

Smith works in the laboratory of biology professor Allen Hurlbert, his SURF advisor. The laboratory experience and community have been central to Smith’s past year at Carolina.

Smith, 28, describes himself as a non-traditional student. After graduating high school, he served in the Army before pursuing the first years of his college career at Cleveland Community College. He transferred to Carolina knowing he wanted to pursue a career related to his love for animals and the outdoors, which he has had since childhood.

READ MORE

We are pleased to announce that Derek Cain has started as the new Associate Chair for Business Administration in the Department of Biology, effective Monday, July 8, 2024.

Derek earned a Master’s of Business Administration in Health Care Management from East Carolina University and a Bachelor’s of Science in Information Systems from UNC Greensboro. He joins us from UNC Health where he served in roles such as a Regional Administrator and, most recently, as the System Equity and Inclusion Manager. He brings a wealth of knowledge and experience in creating and sustaining processes to improve efficiency while maintaining positive relationships with the people connected to those systems. Interesting fact – Derek is a chapter liaison and volunteer for the Food Bank of Central and Eastern North Carolina, as well as an active member of Alpha Phi Alpha Fraternity, Inc.