Poisonous Catfish Described

In contrast to the exhaustive research into venom produced by snakes and spiders, venomous fish have been neglected and remain something of a mystery. Now, a study of 158 catfish species, published in the open access journal BMC Evolutionary Biology, has catalogued the presence of venom glands and investigated their biological effects.


Jeremy Wright, from the University of Michigan, USA, carried out the investigation. He said, "I used histological and toxicological techniques to elucidate the diversity and distribution of venomous catfish. I found that at least 1250, and possibly over 1600 species of catfish may be venomous, a number far greater than any previous estimate of venomous catfish diversity"


Catfish venom glands are found in association with sharp, bony spines along the leading edge of the dorsal and pectoral fins, which can be locked into place when the catfish is threatened. When a spine enters a potential predator, the membrane surrounding the venom gland cells is torn, releasing venom into the wound. Wright describes how catfish venoms are neurotoxic and hemolytic, and are capable of producing a variety of effects such as severe pain, ischemia, muscle spasm and respiratory distress. However, as any one species examined produces no more than three distinct toxins in its venom, each species may not display all of these properties.

Wright's analyses indicate that there are at least two independent evolutionary origins of catfish venom glands. In addition, the toxic peptides show strong similarities with, and might be derived from, previously characterized toxins found in catfish epidermal secretions. "Further examination of the chemical composition of the venoms will provide valuable insight into the mechanisms and potential selective factors driving venom evolution in fishes," comments Wright.

All Octopuses Are Venomous: Could Lead To Drug Discovery

Once thought to be only the realm of the blue-ringed octopus, researchers have now shown that all octopuses and cuttlefish, and some squid are venomous. The work indicates that they all share a common, ancient venomous ancestor and highlights new avenues for drug discovery.


Conducted by scientists from the University of Melbourne, University of Brussels and Museum Victoria, the study was published in the Journal of Molecular Evolution.
 
Dr Bryan Fry from the Department of Biochemistry at the Bio21 Institute, University of Melbourne said that while the blue-ringed octopus species remain the only group that aredangerous to humans, the other species have been quietly using their venom for predation, such as paralysing a clam into opening its shell.


“Venoms are toxic proteins with specialised functions such as paralysing the nervous system” he said.


“We hope that by understanding the structure and mode of action of venom proteins we can benefit drug design for a range of conditions such as pain management, allergies and cancer.”

While many creatures have been examined as a basis for drug development, cephalopods (octopuses, cuttlefish and squid) remain an untapped resource and their venom may represent a unique class of compounds.

Dr Fry obtained tissue samples from cephalopods ranging from Hong Kong, the Coral Sea, the Great Barrier Reef and Antarctica.

The team then analysed the genes for venom production from the different species and found that a venomous ancestor produced one set of venom proteins, but over time additional proteins were added to the chemical arsenal.


The origin of these genes also sheds light on the fundamentals of evolution, presenting a prime example of convergent evolution where species independently develop similar traits.

The team will now work on understanding why very different types of venomous animals seem to consistently settle on the similar venom protein composition, and which physical or chemical properties make them predisposed to be useful as toxin.

“Not only will this allow us to understand how these animals have assembled their arsenals, but it will also allow us to better exploit them in the development of new drugs from venoms,” said Dr Fry.

“It does not seem a coincidence that some of the same protein types have been recruited for use as toxins across the animal kingdom.”

Scientists Tap Into Antarctic Octopus Venom

Researchers have collected venom from octopuses in Antarctica for the first time, significantly advancing our understanding of the properties of venom as a potential resource for drug development.


The study, conducted by an international team of researchers from the University of Melbourne, the Norwegian University of Technology and Science and the University of Hamburg, provides the first insight into the properties of Antarctic octopus venom. It has also revealed the existence of four new species of octopus.


Venom has long been recognised as a potentially valuable resource for drug development. However, scientists have only recently discovered the largely untapped resource cephalopods such as octopuses, cuttlefish and squid, possess in their unique venom properties -- especially the species that live in sub-zero temperatures.

Team Leader, Dr Bryan Fry from the Bio21 Institute says it was a mystery how venomous animals have adapted their venom to have an effect even in sub-zero temperatures, where most venoms would normally lose their function.

"This is the first study that has collected Antarctic octopus venom and confirmed that these creatures have adapted it to work in sub zero temperatures -- the next step is to work out what biochemical tricks they have used," he says.

Dr Fry says the venom analysis revealed that Antarctic octopus venom harbours a range of toxins, two of which had not previously been described.

"We have discovered new small proteins in the venom with very intriguing activities -- these are potentially useful in drug design, but more will be revealed as the study continues," he says.

The study follows from Dr Fry's revelation last year that all octopuses are venomous. The team of scientists then embarked on a huge task to collect and study completely novel venoms to gain a greater understanding of how they work.

"An understanding of the structure and mode of action of venom found in all octopuses may help design drugs for conditions like pain management, allergies and cancer."

Through funding from the Australian Antarctic Division, the team collected 203 octopuses from Antarctic waters. They then genetically profiled each specimen to identify the species and collected venom to analyse in the lab.

"Not only do Antarctic octopuses have the most unique venoms out there, but there is a lot more species than we originally thought."

Potentially Hazardous Asteroid Might Collide With the Earth in 2182

The potentially hazardous asteroid '(101955) 1999 RQ36' has a one-in-a-thousand chance of impacting the Earth, and more than half of this probability indicates that this could happen in the year 2182, based on a global study in which Spanish researchers have been involved. Knowing this fact may help design in advance mechanisms aimed at deviating the asteroid's path.

"The total impact probability of asteroid '(101955) 1999 RQ36' can be estimated in 0.00092 -- approximately one-in-a-thousand chance -- but what is most surprising is that over half of this chance (0.00054) corresponds to 2182," explains María Eugenia Sansaturio, co-author of the study and researcher of Universidad de Valladolid (UVA). The research also involved scientists from the University of Pisa (Italy), the Jet Propulsion Laboratory (USA) and INAF-IASF-Rome (Italy).




Scientists have estimated and monitored the potential impacts for this asteroid through 2200 by means of two mathematical models (Monte Carlo Method and line of variations sampling). Thus, the so called Virtual Impactors (VIs) have been searched. VIs are sets of statistical uncertainty leading to collisions with the Earth on different dates of the XXII century. Two VIs appear in 2182 with more than half the chance of impact.



Asteroid '(101955) 1999 RQ36' is part of the Potentially Hazardous Asteroids (PHA), which have the possibility of hitting the Earth due to the closeness of their orbits, and they may cause damages. This PHA was discovered in 1999 and has around 560 meters in diameter.



The Yarkovsky effect



In practice, its orbit is well determined thanks to 290 optical observations and 13 radar measurements, but there is a significant "orbital uncertainty" because, besides gravity, its path is influenced by the Yarkovsky effect. Such disturbance slightly modifies the orbits of the Solar System's small objects because, when rotating, they radiate from one side the radiation they take from the sun through the other side.



The research, which has been published in the journal Icarus, predicts what could happen in the upcoming years considering this effect. Up to 2060, divergence of the impacting orbits is moderate; between 2060 and 2080 it increases 4 orders of magnitude because the asteroid will approach the Earth in those years; then, it increases again on a slight basis until another approach in 2162, it then decreases, and 2182 is the most likely year for the collision.



"The consequence of this complex dynamic is not just the likelihood of a comparatively large impact, but also that a realistic deflection procedure (path deviation) could only be made before the impact in 2080, and more easily, before 2060," stands out Sansaturio.



The scientist concludes: "If this object had been discovered after 2080, the deflection would require a technology that is not currently available. Therefore, this example suggests that impact monitoring, which up to date does not cover more than 80 or 100 years, may need to encompass more than one century. Thus, the efforts to deviate this type of objects could be conducted with moderate resources, from a technological and financial point of view."

Structure of the solar system

The principal component of the Solar System is the Sun, a main sequence G2 star that contains 99.86 percent of the system's known mass and dominates it gravitationally. The Sun's four largest orbiting bodies, the gas giants, account for 99 percent of the remaining mass, with Jupiter and Saturn together comprising more than 90 percent.




Most large objects in orbit around the Sun lie near the plane of Earth's orbit, known as the ecliptic. The planets are very close to the ecliptic while comets and Kuiper belt objects are frequently at significantly greater angles to it. All the planets and most other objects also orbit with the Sun's rotation (counter-clockwise, as viewed from above the Sun's north pole). There are exceptions, such as Halley's Comet.



The overall structure of the charted regions of the Solar System consists of the Sun, four relatively small inner planets surrounded by a belt of rocky asteroids, and four gas giants surrounded by the outer Kuiper belt of icy objects. Astronomers sometimes informally divide this structure into separate regions. The inner Solar System includes the four terrestrial planets and the main asteroid belt. The outer Solar System is beyond the asteroids, including the four gas giant planets. Since the discovery of the Kuiper belt, the outermost parts of the Solar System are considered a distinct region consisting of the objects beyond Neptune.



Kepler's laws of planetary motion describe the orbits of objects about the Sun. According to Kepler's laws, each object travels along an ellipse with the Sun at one focus. Objects closer to the Sun (with smaller semi-major axes) travel more quickly, as they are more affected by the Sun's gravity. On an elliptical orbit, a body's distance from the Sun varies over the course of its year. A body's closest approach to the Sun is called its perihelion, while its most distant point from the Sun is called its aphelion. The orbits of the planets are nearly circular, but many comets, asteroids and Kuiper belt objects follow highly elliptical orbits.



Due to the vast distances involved, many representations of the Solar System show orbits the same distance apart. In reality, with a few exceptions, the farther a planet or belt is from the Sun, the larger the distance between it and the previous orbit. For example, Venus is approximately 0.33 astronomical units (AU) farther out from the Sun than Mercury, while Saturn is 4.3 AU out from Jupiter, and Neptune lies 10.5 AU out from Uranus. Attempts have been made to determine a correlation between these orbital distances (for example, the Titius-Bode law), but no such theory has been accepted.



Most of the planets in the Solar System possess secondary systems of their own, being orbited by planetary objects called natural satellites, or moons (some of which are larger than the planet Mercury), or, in the case of the four gas giants, by planetary rings; thin bands of tiny particles that orbit them in unison. Most of the largest natural satellites are in synchronous rotation, with one face permanently turned toward their parent.



The objects of the inner Solar System are composed mostly of rock, the collective name for compounds with high melting points, such as silicates, iron or nickel, that remained solid under almost all conditions in the protoplanetary nebula. Jupiter and Saturn are composed mainly of gases, the astronomical term for materials with extremely low melting points and high vapor pressure such as molecular hydrogen, helium, and neon, which were always in the gaseous phase in the nebula. Ices, like water, methane, ammonia, hydrogen sulfide and carbon dioxide, have melting points up to a few hundred kelvins, while their phase depends on the ambient pressure and temperature. They can be found as ices, liquids, or gases in various places in the Solar System, while in the nebula they were either in the solid or gaseous phase. Icy substances comprise the majority of the satellites of the giant planets, as well as most of Uranus and Neptune (the so-called "ice giants") and the numerous small objects that lie beyond Neptune's orbit. Together, gases and ices are referred to as volatiles.

Discovery and exploration of the Solar System

For many thousands of years, humanity, with a few notable exceptions, did not recognize the existence of the Solar System. People believed the Earth to be stationary at the center of the universe and categorically different from the divine or ethereal objects that moved through the sky. Although the Greek philosopher Aristarchus of Samos had speculated on a heliocentric reordering of the cosmos, Nicolaus Copernicus was the first to develop a mathematically predictive heliocentric system. His 17th-century successors, Galileo Galilei, Johannes Kepler and Isaac Newton, developed an understanding of physics which led to the gradual acceptance of the idea that the Earth moves around the Sun and that the planets are governed by the same physical laws that governed the Earth. In more recent times, improvements in the telescope and the use of unmanned spacecraft have enabled the investigation of geological phenomena such as mountains and craters, and seasonal meteorological phenomena such as clouds, dust storms and ice caps on the other planets.

The Solar System

The Solar System consists of the Sun and those celestial objects bound to it by gravity, all of which were formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. Of the many objects that orbit the Sun, most of the mass is contained within eight relatively solitary planets whose orbits are almost circular and lie within a nearly flat disc called the ecliptic plane. The four smaller inner planets, Mercury, Venus, Earth and Mars, also called the terrestrial planets, are primarily composed of rock and metal. The four outer planets, the gas giants, are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are composed largely of ices, such as water, ammonia and methane, and are often referred to separately as "ice giants".
The Solar System is also home to two regions populated by smaller objects. The asteroid belt, which lies between Mars and Jupiter, is similar to the terrestrial planets as it is composed mainly of rock and metal. Beyond Neptune's orbit lie trans-Neptunian objects composed mostly of ices such as water, ammonia and methane. Within these two regions, five individual objects, Ceres, Pluto, Haumea, Makemake and Eris, are recognized to be large enough to have been rounded by their own gravity, and are thus termed dwarf planets.In addition to thousands of small bodies in those two regions, various other small body populations, such as comets, centaurs and interplanetary dust, freely travel between regions.
The solar wind, a flow of plasma from the Sun, creates a bubble in the interstellar medium known as the heliosphere, which extends out to the edge of the scattered disc. The hypothetical Oort cloud, which acts as the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere.
Six of the planets and three of the dwarf planets are orbited by natural satellites,usually termed "moons" after Earth's Moon. Each of the outer planets is encircled by planetary rings of dust and other particles.