BioQuakes

AP Biology class blog for discussing current research in Biology

Author: Thans

New Species Discovered in a Famously Sexual Animal Family

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On February 27, 2014

In Student Post

The Antechinus family of rodents has one of the most peculiar sex lives in the animal kingdom, and just recently another species was discovered. These small  dasyurid marsupial are carnivores who live in Australia and New Guinea. The most extraordinary aspect of the Antechinus family is their sexual cycle. Most males live only long enough to breed, being born in November and reaching sexual maturity around August of the following year. By the time the males are old enough, they cease to function except for the sole purpose of finding a mate. The shrews stop eating and sleeping and begin to shut down bodily functions deemed ‘unnecessary’ so as to save energy for finding a mate and passing on genetic material. This ‘sacrifice’ of bodily functions goes so far as to shut down the immune system and strips the body of vital proteins. As a result of these sacrifices, the males do not long outlive their first sexual experience, which can last about 12 hours. The females live slightly longer, lasting the entire mating season and storing all of the semen within their bodies until ovulation at the end of the season, producing liters with children from various fathers. Although some females manage to survive up to 3 seasons, most die after their first litter.

A relative of the new species from the genus Antechinus

The new species, the black-tailed antechinus, was previously thought to be part of the dusky antechinuses species which is significant in that males are larger and commonly live for multiple mating seasons. It is unknown at this point whether the black-tailed antechinus shares that advantage or if the males simply die after their first season like most of the members of their genus. Other than their peculiar mating habits, the fact that a previously unknown species was discovered in Australia is remarkable, because new mammal species are extremely rare. However finds such as this of new species demonstrate how many new and interesting species of mammals and other organisms may still be out there.

Spinal Neurogenesis

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On February 27, 2014

In Student Post

An astrocyte cell grown in tissue culture as viewed by Gerry Shaw

Normally, when spinal neurons are lost during life due to disease or injury, they are lost for good, however, thanks to a recent study done by  Zhida Su and his colleagues at the University of Texas Southwestern Medical Center that may no longer be the case. The team took astrocytes—star-shaped support cells in the nervous system— from the spines of living mice and converted them into neurons. This research was based of the previous works of  Marius Wernig from the Stanford University School of Medicine, who first converted rat skin cells into stem cell like cells and then into neurons, Benedikt Berninger from Ludwig –Maximillians University Munich, who took certain brain cells and turned them into neurons, and Olof Torper from Lund University, who transformed astroytes from the brains of mice into neurons. Su and his team were drawn to spinal astrocytes because they form scar tissue after spinal cord injuries.

Su and his team accomplished this transformation by injecting a series of viruses into the mice, one of which, SOX2, managed to convert the spinal astrocytes into neuroblasts, both in culture and in living mice who had suffered spinal injuries. Some of these neuroblasts then went on to form functioning neurons and with the addition of valproic acid the number of cells which matured doubled and actually interacted with existing motor neurons.  Although this process is slow and can take up to four weeks, it is incredibly promising and it is even suggested that, “For each reprogrammed [cell], perhaps more than one new neuron could be generated,” meaning that each neuroblast could divide and create multiple neurons. Although this research is extremely promising, only 3-6% of astrocytes effected become neuroblasts which has been in no way enough to study the effects on the health of the mice. However, this research is very young and could lead to major achievments in neurogenesis in the future and the “curing” of paralysis and other conditions that result from the destruction of neurons.

The Movie of Autism

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On January 20, 2014

In Student Post

Stacking repetitively is a behavior often associated with Autism

According to a recent study, “children with autism spectrum disorders (ASD) have trouble integrating simultaneous information from their eyes and their ears,” which has been compared to by Stephen Camarata, Ph.D., professor of Hearing and Speech Sciences at Vanderbilt as similar to, “watching a foreign movie that was badly dubbed.” This study was recently published by Mark Wallace, Ph.D., director of the Vanderbilt Brain Institute and co-authored by Camarata. Their work is incredibly important in the field of diseases such as Autism. Unlike many other

researchers, Wallace and his team have focused on sensory function. Their experiment involved putting groups of children, both with normal function and with high functioning Autism and putting them through a variety of audiovisual stimuli that included, “simple flashes and beeps, more complex environmental stimuli like a hammer hitting a nail, and speech stimuli.” After these tests were done, the researchers asked the subjects to identify which auditory and which visual stimuli occurred at the same time. These test showed that children with Autism have, an :enlargement in something known as the temporal binding window (TBW),” which means they have trouble associating sights and sounds with specific times.

A second aspect of the study also showed that children have trouble associating visual and auditory stimuli from speech, which may have something to do with their constant covering of their ears. Although the data here is not conclusive, it has lead the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition to add sensory processing as a key problem for those who suffer from Autism. The whole study has opened up a new field of inquiry on Autism studies and has the possibility of leading to new advances with other psychiatric diseases such as schizophrenia.

From Fin to Foot

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On January 19, 2014

In Student Post

It is widely understood in the scientific community that, at some point, life evolved from aquatic to terrestrial. In that evolution, at some point fish must have evolved into amphibians. The question of this evolutionary jump still remains a mystery, but the discovery of a new fossil has shed new light on the issue, filling in some of the many gaps in this evolutionary story. This new fossil, discovered in Canada was of the Tiktaalik, a proto-amphibian of the Devonian period. Although this species was not necessarily a new find, it was a complete fossil. Prior to the discovery of this specific fossil scientists only had the front half of the Tiktaalik fossil, and as such could only speculate about its back half. The accepted evolutionary story at the time was that front legs developed first as the power behind walking on land, with back legs functioning only as weak supports. However, this new fossil was fully complete and showed a highly developed pair of back legs with a very developed pelvis, quite unlike any found. Although the bones in the fishes back leg were not as complicated as those of modern amphibians, they were far more advanced than the average fish of the time and more advanced than the widely accepted belief of the scientific community had suggested. This Tiktaalik fossil discovered by Dr. Neil Shubin, has fascinated the scientific community, as it is a great example of a creature exhibiting a myriad of evolutionary changes. Although the bone structure development here still favors the fin, there is astounding development in both the fore and hind legs that show that mark this creature as a key link between aquatic and terrestrial life.

This image of the Tiktaalik shows an artists representation of the creature before its powerful hind were discovered

Big Cats of the Past

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On November 19, 2013

In Student Post

A snow leopard at the Toronto Zoo The snow leopard is the closest living relative to the Panthera blytheae

In Tibet in 2010  Z. Jack Tseng and Juan Liu travelled to a remote section of the Tibetan Plateau. Whilst there they came across a collection of prehistoric fossils, mostly antelope and other known herbivores, with one notable exception, the skull of a previously undiscovered big cat which they called Panthera blytheae. This skull and the accompanying jawbone fragments belong to what is now, to date, the oldest known big cat. After analysis of its teeth, it has been theorized that this cat would have been quite similar in habitat and hunting style to the modern snow leopard. “In terms of the overall size it would be a little bit smaller than a snow leopard– the size of a clouded leopard and those living cats grow up to around 20kg [44lb],” said Jack Tseng, the discoverer.

Skull of a snow leopard, which is very similar to the skull of the newly found Panthera blytheae

This discovery is quite significant with regards to big cat evolutionary history. Current experts hold that big cats broke from the main felinea subfamily some time around 6.37 million years ago. However, until this find, the oldest big cat fossil was a 3.5 million year old fossil from Tanzania. P. blytheae not only pushes the date back almost two million years, being estimated to have lived between 4.10 and 5.95 million years ago, but also gave weight to the theory that big cats originated first in Asia, not in Africa. Anjali Goswami, a palaeobiologist at University College London said, “This beautiful fossil supports the Asian origin for the group, bringing together molecular, living and fossil data into a unified view of pantherine evolution. It also supports the idea that the Tibetan plateau was, and remains, an important biogeographic region for large mammals and is the center of origin for many important groups. Nailing down the place of origin for pantherines also means that we can better understand the environmental and ecological context in which this group evolved.”

Deforestation is Out of Control

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On November 18, 2013

In Student Post

Deforestation has always been viewed as a problem by modern observers. No one can deny that the cutting down of forests is necessary for economic development and continued prosperity in some lumber rich nations, however, things are getting out of control. In a recent study, it was revealed that a total loss of 2.3 million acres of forest was destroyed in between 2000 and 2012. To put that amount in perspective, it is equivalent to six Californians or the entirety of the United States east of the Mississippi River. This massive loss of forest land was countered by a gain of only .8 million acres, resulting in a 1.5 million acre net loss of forest land around the globe.

According to Ritchie King, a reporter on the subject, “Deforestation at this scale is having a tremendous ecological impact, on both species and climate. From 2000 to 2011, deforestation effectively added 14.5 billion tonnes (16 billion tons) of carbon to the atmosphere, about 13% of the world’s total contribution to climate change.”  Some nations who, in the past, have been the greatest culprits of deforestation, such as Brazil, have cut back their logging and have greatly reduced the rate at which land is cleared, however, in other parts of the world, particularly Indonesia, (if you scroll to the bottom of the article there is a graphic) deforestation has sped up rapidly. Not only does deforestation threaten the world as a whole through the production of a large precent of the earths greenhouse gases, but it also threatens the delicate forest ecosystems around the world. Heavy deforestation in areas with Rain forests, such as Brazil and Indonesia threatens the unique species of plants and animals which live there, and threatens to reduce the biodiversity present on Earth.

Deforestation in Brazil

Solar Power

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On September 25, 2013

In Student Post

Copyright © 2005 David Monniaux

As of September 24th, 2013 there is a new world record for solar cell efficiency. The scientists of the Fraunhofer Institute for Solar Energy Systems ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin jointly announced that they have developed a new solar cell which converts, “44.7% of the solar spectrum’s energy, from ultraviolet through to the infrared, into electrical energy.” This new breakthrough pushes the scientific community one step closer to its goal of 50% efficiency.

The new cells are used in concentrator photovoltaics which are twice as efficient as the conventional PV power plants. The reason for the increased efficiency is the so-called III-V multi-junction solar cells which are made of of several different solar cells which absorb different wavelength ranges of the solar spectrum.

This new development in the field of alternative energy is incredibly important in our current energy crisis. The native country of the scientists from this section is the leading country in the world with regards to solar energy. Germany as a nation is devoted to making solar energy and other renewable energy sources their only source of electricity by 2050. This German renewable resource initiative is quite ahead of our own. What do you think about the future of using renewable resources and the goals of countries like Germany who hope to end their reliance on fossil fuels within the next half century?

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