Mammals Started Out as Nocturnal

Mammals Switched to Daytime
Activity after Dinosaur Extinction
London – November 6, 2017 -- Mammals only started being active in the daytime after non-avian dinosaurs were wiped out about 66 million years ago (mya), finds a new study led by UCL [University College London] and Tel Aviv University’s Steinhardt Museum of Natural History.

A long-standing theory holds that the common ancestor to all mammals was nocturnal, but the new discovery reveals when mammals started living in the daytime for the first time. It also provides insight into which species changed behavior first.

The study, published today in Nature Ecology & Evolution, analyzed data of 2415 species of mammals alive today using computer algorithms to reconstruct the likely activity patterns of their ancient ancestors who lived millions of years ago.

Two different mammalian family trees portraying alternative timelines for the evolution of mammals were used in the analysis. The results from both show that mammals switched to daytime activity shortly after the dinosaurs had disappeared. This change did not happen in an instant – it involved an intermediate stage of mixed day and night activity over millions of years, which coincided with the events that decimated the dinosaurs.

“We were very surprised to find such close correlation between the disappearance of dinosaurs and the beginning of daytime activity in mammals, but we found the same result unanimously using several alternative analyses,” explained lead author, PhD student Roi Maor (Tel Aviv University and UCL).    

The team found that the ancestors of simian primates – such as gorillas, gibbons and tamarins – were among the first to give up nocturnal activity altogether. However, the two evolutionary timelines varied, giving a window between 52-33 mya for this to have occurred.

This discovery fits well with the fact that simian primates are the only mammals that have evolved adaptations to seeing well in daylight. The visual acuity and color perception of simians is comparable to those of diurnal reptiles and birds – groups that never left the daytime niche.

“It’s very difficult to relate behavior changes in mammals that lived so long ago to ecological conditions at the time, so we can’t say that the dinosaurs dying out caused mammals to start being active in the daytime. However, we see a clear correlation in our findings,” added co-author Professor Kate Jones (UCL Genetics, Evolution & Environment).

“We analyzed a lot of data on the behavior and ancestry of living animals for two reasons – firstly, because the fossil record from that era is very limited and secondly, behavior as a trait is very hard to infer from fossils,” explained co-author, Professor Tamar Dayan (Chair of The Steinhardt Museum of Natural History, Tel Aviv University).

“You have to observe a living mammal to see if it is active at night or in the day. Fossil evidence from mammals often suggests that they were nocturnal even if they were not. Many subsequent adaptations that allow us to live in daylight are in our soft tissues.”

The team says further research is needed to better populate the mammalian family tree to give more accurate information on when the behavior of species changes from night time to day time activity.

http://www.ucl.ac.uk/news/news-articles/1117/061117-Mammals-switched-to-daytime-activity-after-dinosaur-extinction

Growing Better Stem Cells

Stanford Researchers Develop a Gel for Growing Large Quantities of Neural Stem Cells

A new gel could help grow the large quantities of neural stem cells needed for sought-after therapies. Its success depends on the cells’ ability to stay in touch.

By Andrew Myers

Stanford – November 2, 2017 -- In many ways, stem cells are the divas of the biological world. On the one hand, these natural shapeshifters can transform themselves into virtually any type of cell in the body. In that regard, they hold the promise of being able to cure ills ranging from spinal cord injuries to cancers.

An advance in growing large amounts of stem cells is described in a new journal article by Sarah Heilshorn, associate professor of materials science and engineering. (Image credit: luismmolina / Getty Images)

On the other hand, said associate professor of materials science and engineering Sarah Heilshorn, stem cells, like divas, are also mercurial and difficult to work with.

“We just don’t know how to efficiently and effectively grow massive numbers of stem cells and keep them in their regenerative state,” Heilshorn said. “This has prevented us from making more progress in creating therapies.”

Until now, that is. In a recent paper in Nature Materials, Heilshorn described a solution to the dual challenges of growing and preserving neural stem cells in a state where they are still able to mature into many different cell types. The first challenge is that growing stem cells in quantity requires space. Like traditional farming, it is a two-dimensional affair. If you want more wheat, corn or stem cells, you need more surface area. Culturing stem cells, therefore, requires a lot of relatively expensive laboratory real estate, not to mention the energy and nutrients necessary to pull it all off.

The second challenge is that once they’ve divided many times in a lab dish, stem cells do not easily remain in the ideal state of readiness to become other types of cells. Researchers refer to this quality as “stemness.” Heilshorn found that for the neural stem cells she was working with, maintaining the cells’ stemness requires the cells to be touching.

Heilshorn’s team was working with a particular type of stem cell that matures into neurons and other cells of the nervous system. These types of cells, if produced in sufficient quantities, could generate therapies to repair spinal cord injuries, counteract traumatic brain injury or cure some of the most severe degenerative disorders of the nervous system, like Parkinson’s and Huntington’s diseases.

Heilshorn’s solution involves the use of better materials in which to grow stem cells. Her lab has developed new polymer-based gels that allow the cells to be grown in three dimensions instead of two. This new 3-D process takes up less than 1 percent of the lab space required by current stem cell culturing techniques. And because cells are so tiny, the 3-D gel stack is just a single millimeter tall, roughly the thickness of a dime.

“For a 3-D culture, we need only a 4-inch-by-4-inch plot of lab space, or about 16 square inches. A 2-D culture requires a plot four feet by four feet, or about 16 square feet,” more than 100-times the space, according to first author Chris Madl, a recent doctoral graduate in bioengineering from Heilshorn’s lab

In addition to the dramatic savings of lab space, the new process demands fewer nutrients and less energy, as well.

The gels the team developed allow the stem cells to remodel the long molecules and maintain physical contact with one another to preserve critical communication channels between cells.

“The simple act of touching is key to communication between stem cells and to maintaining stemness. If stem cells can’t remodel the gels, they can’t touch one another,” Madl explained.

“The stem cells don’t exactly die if they can’t touch, but they lose that ability to regenerate that we really need for therapeutic success,” Heilshorn added.

Striking results

This need for neural stem cell to remodel their environment differs from what Heilshorn has found in working with other types of stem cells. For those cells, it is the stiffness of the gels – not the ability to remodel – that is the key factor in maintaining stemness. It is as if for these other types of stem cells, gels must mimic the rigidity of the tissue in which the cells will eventually be transplanted. Not so with neural progenitors, said Heilshorn.

“Neural cell stemness is not sensitive to stiffness and that was a big surprise to us,” she said.

The result was so striking and unexpected that Heilshorn, at first, didn’t believe her own results. The lab ended up testing three entirely different gels to see if their conclusion held, an unusual supplementary step in this kind of research. With each new material, they saw that those that could be remodeled produced quality stem cells; those that could not be remodeled had a negative effect on stemness.

Next up on Heilshorn’s research agenda is to create gels that can be injected directly from the lab dish into the body. The possibilities have her feeling optimistic about stem cell therapies again. For a time, she said, it felt as if the field had hit a wall, as initial excitement for regeneration gave way to uninspiring results in the clinic. With her new finding, she said, it feels like new things may be just around the corner.

“There’s this convergence of biological knowledge and engineering principles in stem cell research that has me hopeful we might finally actually solve some big problems,” she said.

https://news.stanford.edu/2017/11/02/gel-helps-grow-large-quantities-stem-cells-limited-space/

Critters Don't Have Wheels

Several organisms are capable of rolling locomotion; however, true wheels and propellers—despite their utility in human vehicles—do not appear to play a significant role in the movement of living things (with the notable exception of certain flagella, which function like corkscrews). Biologists have expounded on the reasons for this apparent absence of biological wheels, and wheeled creatures have appeared often in speculative fiction.

Given the ubiquity of the wheel in human technology, and the existence of biological analogues of many other technologies (such as wings and lenses), the lack of wheels in the natural world would seem to demand explanation—and the phenomenon is broadly explained by two main factors. First, there are several developmental and evolutionary obstacles to the advent of a wheel by natural selection, addressing the question "Why can't life evolve wheels?" Secondly, wheels are often at a competitive disadvantage when compared with other means of propulsion (such as walking, running, or slithering) in natural environments, addressing the question "If wheels could evolve, why might they be rare nonetheless?" This environment-specific disadvantage also explains why some historical civilizations have abandoned wheels.

Biological Barriers to Wheeled Organisms

The absence of wheels in nature is frequently attributed to constraints imposed by biology: natural selection constrains the evolutionary paths available to species, and the processes by which multicellular organisms grow and develop may not permit the construction of a functioning wheel.

Disadvantages of Wheels

Wheels incur mechanical and other disadvantages in certain environments and situations that would represent a decreased fitness when compared with limbed locomotion. These disadvantages suggest that, even barring the biological constraints discussed above, the absence of wheels in multicellular life may not be the "missed opportunity" of biology that it first seems. In fact, given the mechanical disadvantages and restricted usefulness of wheels when compared with limbs, the central question can be reversed: not "Why does nature not produce wheels?", but rather, "Why do human vehicles not make more use of limbs?" The use of wheels rather than limbs in many engineered vehicles can likely be attributed to the complexity of design required to construct and control limbs, rather than to a consistent functional advantage of wheels over limbs.

Wheeled Creatures in Fiction

Toy animals with wheels dating from the Pre-Columbian era were uncovered by archaeologists in Veracruz, Mexico, in the 1940s. The indigenous peoples of this region did not use wheels for transportation prior to the arrival of Europeans.

                                      Toy animal with wheels from pre-Columbian Mexico

Several twentieth century writers explored possibilities of wheeled creatures. L. Frank Baum's 1907 children's novel Ozma of Oz features humanoid creatures with wheels instead of hands and feet, called Wheelers. Their wheels are composed of keratin, which has been suggested by biologists as a means of avoiding nutrient and waste transfer problems with living wheels. Despite moving quickly on open terrain, the Wheelers are stymied by obstacles in their path that do not hinder creatures with limbs.

In the latter half of the twentieth century, wheeled creatures were featured in works by fantasy and science fiction writers including Clifford D. Simak, Piers Anthony, David Brin, K. A. Applegate, Philip Pullman, and Ian Stewart and Jack Cohen. Some of these works address the developmental and biomechanical constraints on wheeled creatures: Brin's creatures suffer from arthritic axles, and Pullman's are not born with wheels, but use seed pods found in their environment.

                 https://en.wikipedia.org/wiki/Rotating_locomotion_in_living_systems

Hole in Ozone Layer Is Smaller

Warm Air Helped Make 2017
Ozone Hole Smallest Since 1988
Measurements from satellites this year showed the hole in Earth’s ozone layer that forms over Antarctica each September was the smallest observed since 1988, scientists from NASA and NOAA announced today.

By Katy Mersmann, November 3, 2017 -- According to NASA, the ozone hole reached its peak extent on Sept. 11, covering an area about two and a half times the size of the United States – 7.6 million square miles in extent - and then declined through the remainder of September and into October. NOAA ground- and balloon-based measurements also showed the least amount of ozone depletion above the continent during the peak of the ozone depletion cycle since 1988. NOAA and NASA collaborate to monitor the growth and recovery of the ozone hole every year.

“The Antarctic ozone hole was exceptionally weak this year,” said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “This is what we would expect to see given the weather conditions in the Antarctic stratosphere.”

The smaller ozone hole in 2017 was strongly influenced by an unstable and warmer Antarctic vortex – the stratospheric low pressure system that rotates clockwise in the atmosphere above Antarctica. This helped minimize polar stratospheric cloud formation in the lower stratosphere. The formation and persistence of these clouds are important first steps leading to the chlorine- and bromine-catalyzed reactions that destroy ozone, scientists said. These Antarctic conditions resemble those found in the Arctic, where ozone depletion is much less severe.

In 2016, warmer stratospheric temperatures also constrained the growth of the ozone hole. Last year, the ozone hole reached a maximum 8.9 million square miles, 2 million square miles less than in 2015. The average area of these daily ozone hole maximums observed since 1991 has been roughly 10 million square miles.  

Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.

Scientists said the smaller ozone hole extent in 2016 and 2017 is due to natural variability and not a signal of rapid healing.

First detected in 1985, the Antarctic ozone hole forms during the Southern Hemisphere’s late winter as the returning sun’s rays catalyze reactions involving man-made, chemically active forms of chlorine and bromine. These reactions destroy ozone molecules.

Thirty years ago, the international community signed the Montreal Protocol on Substances that Deplete the Ozone Layer and began regulating ozone-depleting compounds. The ozone hole over Antarctica is expected to gradually become less severe as chlorofluorocarbons—chlorine-containing synthetic compounds once frequently used as refrigerants – continue to decline. Scientists expect the Antarctic ozone hole to recover back to 1980 levels around 2070.

Ozone is a molecule comprised of three oxygen atoms that occurs naturally in small amounts. In the stratosphere, roughly 7 to 25 miles above Earth’s surface, the ozone layer acts like sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and also damage plants. Closer to the ground, ozone can also be created by photochemical reactions between the sun and pollution from vehicle emissions and other sources, forming harmful smog.

Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected. This is because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.

NASA and NOAA monitor the ozone hole via three complementary instrumental methods. Satellites, like NASA’s Aura satellite and NASA-NOAA Suomi National Polar-orbiting Partnership satellite measure ozone from space. The Aura satellite’s Microwave Limb Sounder  also measures certain chlorine-containing gases, providing estimates of total chlorine levels.

NOAA scientists monitor the thickness of the ozone layer and its vertical distribution above the South Pole station by regularly releasing weather balloons carrying ozone-measuring “sondes” up to 21 miles in altitude, and with a ground-based instrument called a Dobson spectrophotometer.

The Dobson spectrophotometer measures the total amount of ozone in a column extending from Earth’s surface to the edge of space in Dobson Units, defined as the number of ozone molecules that would be required to create a layer of pure ozone 0.01 millimeters thick at a temperature of 32 degrees Fahrenheit at an atmospheric pressure equivalent to Earth’s surface.

This year, the ozone concentration reached a minimum over the South Pole of 136 Dobson Units on September 25— the highest minimum seen since 1988. During the 1960s, before the Antarctic ozone hole occurred, average ozone concentrations above the South Pole ranged from 250 to 350 Dobson units. Earth's ozone layer averages 300 to 500 Dobson units, which is equivalent to about 3 millimeters, or about the same as two pennies stacked one on top of the other.

"In the past, we've always seen ozone at some stratospheric altitudes go to zero by the end of September," said Bryan Johnson, NOAA atmospheric chemist. "This year our balloon measurements showed the ozone loss rate stalled by the middle of September and ozone levels never reached zero."

                  https://www.nasa.gov/feature/goddard/2017/warm-air-helped-make-2017-ozone-hole-smallest-since-1988

Colorectal Cancer Research

New System for Treating Colorectal
Cancer Can Lead to Complete Cure
Novel three-step pretargeted radioimmunotherapy offers safe, effective treatment
From the Society of Nuclear Medicine and Molecular Imaging (SNMMI)

RESTON, Va. – November 2, 2017 -- Researchers at Memorial Sloan Kettering Cancer Center in New York City and Massachusetts Institute of Technology in Boston have developed a new, three-step system that uses nuclear medicine to target and eliminate colorectal cancer. In this study with a mouse model, researchers achieved a 100-percent cure rate—without any treatment-related toxic effects. The study is reported in the November featured article in The Journal of Nuclear Medicine.

Until now, radioimmunotherapy (targeted therapy) of solid tumors using antibody-targeted radionuclides has had limited therapeutic success. “This research is novel because of the benchmarks reached by the treatment regimen, in terms of curative tumor doses, with non-toxic secondary radiation to the body’s normal tissues,” explains Steven M. Larson, MD, and Sarah Cheal, PhD, of Memorial Sloan Kettering Cancer Center. “The success in murine tumor models comes from the unique quality of the reagents developed by our group, and the reduction to practice methodology, including a theranostic approach that can be readily transferred, we believe, to patients.”

Theranostics, a term derived from therapy and diagnostics, is the use of a single agent to both diagnose and treat disease. The theranostic agent first finds the cancer cells, then destroys them, leaving healthy cells unharmed—minimizing side effects and improving quality of life for patients.

In this study, the glycoprotein A33 (GPA33), an antigen found on over 95 percent of primary and metastatic human colorectal cancers, was targeted with a bispecific antibody for A33 tumor antigen and a second antibody for a small-molecule radioactive hapten, a complex of lutetium-177 (¹⁷⁷Lu) and S-2-(4-aminobenzyl)1,4,7,10-tetraazacyclododecane tetra-acetic acid (¹⁷⁷Lu-DOTA-Bn).

The DOTA-pretargeted radioimmunotherapy (PRIT) strategy was tested on a mouse model. In randomly selected mice undergoing treatment, serial SPECT/CT imaging was used to monitor treatment response and calculate radiation-absorbed doses to tumors. All the DOTA-PRIT–treated animals tolerated the treatment well, and all 9 assessed mice had no trace of cancer remaining upon microscopic examination. There was also no detectable radiation damage to critical organs, including bone marrow and kidneys.

The 100-percent cure rate in the mouse model is a promising preliminary finding that suggests that anti-GPA33-DOTA-PRIT will be a potent radioimmunotherapy regimen for GPA33-positive colorectal cancer tumors in humans.

According to the Centers for Disease Control and Prevention, colorectal cancer is the third most common cancer affecting both men and women. Each year, approximately 140,000 new cases are diagnosed in the United States and 50,000 people die of the disease.

The applications of this nuclear medicine treatment protocol could extend to other cancers as well. Larson and Cheal state, “If clinically successful, our approach will expand the repertoire of effective treatments for oncologic patients. The system is designed as a ‘plug and play’ system, which allows for the use of many fine antibodies targeting human tumor antigens and is applicable, in principle, to virtually all solid and liquid tumors in man.” They add, “There is a huge unmet need in oncology, especially for the solid tumors, for curative treatments for advanced disease. This includes, colon, breast, pancreas, melanoma, lung, and esophageal, to name a few.”

http://www.snmmi.org/NewsPublications/NewsDetail.aspx?ItemNumber=25460

Animals Making Decisions

Do Animals Think Rationally?
Researcher Suggests Rational Decision-Making Doesn’t Require Language
By Jeannie Kever, University of Houston

November 1, 2017 -- Previous research has shown that animals can remember specific events, use tools and solve problems. But exactly what that means – whether they are making rational decisions or simply reacting to their environment through mindless reflex – remains a matter of scientific dispute.

Cameron Buckner, assistant professor of philosophy at the University of Houston, argues in an article published in Philosophy and Phenomenological Research that a wide range of animal species exhibit so-called “executive control” when it comes to making decisions, consciously considering their goals and ways to satisfy those goals before acting.

He acknowledges that language is required for some sophisticated forms of metacognition, or thinking about thinking. But bolstered by a review of previously published research, Buckner concludes that a wide variety of animals – elephants, chimpanzees, ravens and lions, among others – engage in rational decision-making.

“These data suggest that not only do some animals have a subjective take on the suitability of the option they are evaluating for their goal, they possess a subjective, internal signal regarding their confidence in this take that can be deployed to select amongst different options,” he wrote.

The question has been debated since the days of the ancient philosophers, as people considered what it means to be human. One way to address that, Buckner said, is to determine exactly what sets humans apart from other animals.

Language remains a key differentiator, and Buckner notes that serious attempts in the 1970s and ‘80s to teach animals human language – teaching chimpanzees to use sign language, for example – found that although they were able to express simple ideas, they did not engage in complex thought and language structures.

Ancient philosophers relied upon anecdotal evidence to study the issue, but today’s researchers conduct sophisticated controlled experiments. Buckner, working with Thomas Bugnyar and Stephan A. Reber, cognitive biologists at the University of Vienna, last year published the results of a study that determined ravens share at least some of the human ability to think abstractly about other minds, adapting their behavior by attributing their own perceptions to others.

In his latest paper, Buckner offers several examples to support his argument:

• ·                                 Matriarchal elephants in Kenya’s Amboseli National Park were able to determine the threat level of human intruders by differentiating ethnicity, gender and age, suggesting an understanding that adult Maasai tribesmen sometimes kill elephants in competition for grazing or in retaliation for attacks against humans, while Kamba tribesmen and women and children from both tribes don’t pose a threat.
• ·                                 Giraffes are not generally considered prey by lions in Africa, due to the long-necked animals’ ability to deliver skull-crushing kicks. Lions in South Africa’s Selous Game Reserve, however, are reported to have learned that giraffes found in a sandy river bed can get stuck and even trip, making them suitable prey.

His goal, Buckner said, was to compile the empirical research, “to see that we’ve accumulated enough evidence to say that animals really are rational in a distinctive way.”

                     http://www.uh.edu/news-events/stories/2017/november/11012017Buckner-Animal-Cognition.php

Silbo Gomero Whistled Language

Silbo Gomero (Spanish: silbo gomero, 'Gomeran whistle'), also known as el silbo ('the whistle'), is a whistled register of Spanish used by inhabitants of La Gomera in the Canary Islands to communicate across the deep ravines and narrow valleys that radiate through the island. It enables messages to be exchanged over a distance of up to 5 kilometres. Due to this loud nature, Silbo Gomero is generally used in circumstances of public communication. Messages conveyed could range from event invitations to public information advisories. A speaker of Silbo Gomero is sometimes referred to in Spanish as a silbador ('whistler'). Silbo Gomero is a transposition of Spanish from speech to whistling. This oral phoneme-whistled phoneme substitution emulates Spanish phonology through a reduced set of whistled phonemes. It was declared as a Masterpiece of the Oral and Intangible Heritage of Humanity by UNESCO in 2009.

History

Little is known of the original Guanche language or the languages of the Canaries, but it is assumed that their phonological system must have been simple enough to allow an efficient whistled language. Used by the island's original inhabitants, the Guanches, the whistled language existed before the arrival of Spanish settlers and was also spoken on el Hierro, Tenerife, and Gran Canaria. Silbo was adapted to Spanish during the Spanish settlement in the 16th century and was widely spoken throughout the period into the following 17th century. In 1976 Silbo barely remained on el Hierro, where it had flourished at the end of the 19th century.

Use of the language declined in the 1950s, one factor being the economic decline, which forced many speakers to move away to seek better jobs to cope financially. Technological developments such as the telephone played a part in reducing the practicality and utility of the language. The language's earlier survival had been due to its role in overcoming distance and terrain, in addition to the ease with which it is learned by native speakers. Most significantly, in the period from the 1960s to 1980s, many people had turned away from agriculture and so many middle class families did not want their children to speak the language as it was negatively associated with the rural peasants.

In the late 1990s, language revitalization efforts began and initiatives from within the community started. By 1999, the revitalization of Silbo Gomero was furthered by education policies and other legislative measures. It now has official protection as an example of intangible cultural heritage.

Speakers

Many people in La Gomera speak Silbo Gomero, but their expression of the language deviates in minor ways which shows the different origins of the speaker. As reported in a 2009 UNESCO report, all the people living in La Gomera understand the language, but only those born before 1950 and the younger generations who attended school since 1999 can speak the language. Those born before 1950 were taught the language by their elders in their homes, and those who have attended or are attending school since 1999 were taught the language formally in school. Those born between 1950 and 1980 understand the language but are unable to speak it, as the language was hardly used and negatively viewed during their time of language acquisition.

                     https://en.wikipedia.org/wiki/Silbo_Gomero