La radiación de Fukushima ya causa mutaciones en mariposas.
http://sociedad.elpais.com/sociedad/2012/08/14/actualidad/1344944520_986936.html
No ha pasado año y medio del accidente nuclear de Fukushima (Japón) y un grupo de científicos locales ya ha encontrado las primeras consecuencias en la biodiversidad de la región. Una investigación concluye que tres generaciones de mariposas de la clase Zizeeria maha han sufrido “malformaciones graves”. “Hemos llegado a la firme conclusión de que la radiación liberada en la planta de Fukushima ha dañado los genes de las mariposas”, ha asegurado el profesor Joji Otaki, de la Universidad de Ryukyu en Okinawa.
El equipo de investigadores recogió 144 adultos de la mariposa en 10 lugares diferentes de Japón, uno de ellos fue las proximidades de la central nuclear de Fukushima, para comparar su desarrollo. El estudio, publicado en la revista Scientific Reports, del grupo editorial de Nature, revela que alrededor del 12% de las mariposas que fueron expuestas a la lluvia radiactiva inmediatamente después del accidente nuclear, cuando eran larvas, presentaron anormalidades como alas más pequeñas y ojos dañados.
Los descendientes de estos insectos procedentes de Fukushima, que se criaron y desarrollaron en un laboratorio alejada de la zona de alta radioactividad, sufrieron malformaciones en un 18%. Esta cifra se elevó al 34% en la tercera generación de mariposas, a pesar de que solo uno de los progenitores procedía de la zona contaminada.
Los investigadores también recolectaron otras 240 mariposas en Fukushima, en septiembre del año pasado, seis meses después del desastre. Las anomalías se registraron en el 52% de la descendencia de estos ejemplares, lo que supone "una proporción muy alta", dice Otaki.
La presente noticia, sacada de la versión digital del periódico El País, nos muestra un caso más de los múltiples accidentes ocurridos después del fatídico catástrofe de la central nuclear de Fukushima, en Japón.
En este caso se nos muestra las anomalías causadas en las mariposas de la clase Zizeeria maha.
El alto porcentaje de mariposas con anomalías es alarmante.
Una vez más se nos muestra el gran peligro que provocan estos accidentes, afectando y provocando serios riesgos, tanto a animales, como a las personas.
El 30% de las amenazas para las especies proceden del comercio internacional.
http://sociedad.elpais.com/sociedad/2012/06/06/actualidad/1339004523_805682.html
El café que millones de personas toman en el desayudo parece inofensivo desde el punto de vista del medio ambiente, pero la próxima vez que se prepare una taza puede pensar si la expansión de los cultivos de esa planta tan aromática y estimulante es una amenaza para la biodiversidad allá donde se cultiva. Lo es. Para conocer y medir el efecto del consumo, sobre todo en los países desarrollados, no basta con buscar en el entorno inmediato, hay que mirar lejos. Por ejemplo en México, Colombia y en Indonesia, en el caso del café. Pero hay muchísimos más productos consumidos en unos rincones del globo responsables de la devastación de hábitats en otros, y además, pasando por una intrincada red de distribución comercial o de transformación de las materias primas. Un equipo internacional de científicos ha cuantificado este fenómeno a gran escala y concluye que al menos el 30% de las amenazas para la biodiversidad, excluyendo la debida a las especies invasoras, proceden del comercio internacional. Los diez países más importantes que importan esas amenazas (asociadas al consumo de bienes producidos fuera de sus fronteras) son Estados Unidos, Japón. Alemania, Francia, Reino Unido, Italia, España, Corea del sur y Canadá. Los diez primeros de la lista deexportadores son: Camerún, Camboya, Rusia, Tailandia, Sri Lanka, Filipinas, Malasia, Papúa Nueva Guinea, Madagascar e Indonesia, según los cálculos realizados por el equipo de expertos, liderado por Manfred Lenzen (Universidad de Sidney, en Australia).
“Las actividades humanas están causando la sexta extinción masiva del planeta, un caída acelerada actual de la reserva de biodiversidad biológica con tasas entre cien y mil veces superiores a la era preindustrial”, recuerdan estos investigadores en su artículo publicado en la revista Nature. “Históricamente, la intrusión —de bajo impacto— en los hábitats de las especies respondía a la demanda local de comida, combustible y espacio habitable. Sin embargo, en la actual economía cada vez más globalizada, las cadenas de comercio internacional aceleran la degradación de hábitats muy lejos de los lugares de consumo”. Los mecanismos implicados y los efectos se conocen mal.
Pero los casos de amenaza para la biodiversidad a distancia son numerosos, recuerdan estos científicos: la soja y la producción de carne con su efecto negativo sobre la selva en Brasil; la pesca den Nueva Guinea Papúa, las plantaciones para obtener aceite de palma en Indonesia y en Malasia o la captura de peces de colores para acuarios en Vietnam, por citar unos pocos. Uno de los casos concretos que apuntan los investigadores es el del mono araña (Ateles geoffroyi), que está en peligro y amenazado por pérdida de hábitat a medida que se extienden las plantaciones de café y cacao en México y Centroamérica. Lenzen y sus colegas de Australia, Italia y Japón han cruzado los datos de 15.000 especies amenazadas en la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza (IUCN) con más de 15.000 productos originados en 187 países para evaluar el impacto ambiental. Además han tenido en cuenta en sus análisis las intrincadas vías de distribución y transformación desde el productor original de la materia prima hasta el consumidor del bien acabado, en las que a menudo están implicados más de dos países. Productos agrícolas y madera de Guinea Nueva Papúa (donde 171 especies están amenazadas por estas importaciones) acaban en Japón, pero pasando por Malasia, Indonesia, Hong Kong, Taiwan, Australia o Tailandia. “Lo que hemos descubierto demuestra que las amenazas locales están directamente alimentadas por la actividad económica y la demanda de los consumidores en todo el mundo”, escriben Lenzen y sus colegas en Nature. Para manejar todos los datos debidamente, han desarrollado un complejo modelo por ordenador que relaciona la presión medioambiental y el impacto en los ecosistemas con la producción y el comercio mundiales.
La biodiversidad, además, no es la única amenaza medioambiental cuya responsabilidad recae, en gran medida, a distancia del daño infringido. Lo mismo pasa con la contaminación, por ejemplo en China, generada por la producción pasiva de bienes y productos para la exportación.
Si usted compra un juego de ajedrez con piezas hechas de marfil, puede sospechar que está contribuyendo a la matanza de elefantes. Pero si compra una salchicha no puede saber si el cerdo con el que se ha hecho estaba alimentado de soja de una granja que se ha extendido en lo que antes era el hábitat de los elefantes. El efecto sobre la diversidad de las especies, sin embargo, es similar”, señala el especialista noruego Edgar Hertwich al comentar en Nature el trabajo de sus colegas.La investigación no se limita a desentrañar la interrelación entre pérdida de biodiversidad y consumo remoto, sino que toma en consideración iniciativas que pueden atenuar los efectos. Y los mecanismos para una justa distribución de las responsabilidades no tienen por qué partir de cero. Lenzen y sus colegas recuerdan que las autoridades chinas apuntan que debería recaer parte de emisiones de gases de efecto invernadero de su país en la contabilidad de los países importadores de esos bienes. La biodiversidad podría aprovechar idénticos conceptos y métodos, dicen estos expertos. Otra iniciativa interesante es la del Convenio Cites, que regula el comercio internacional de especies amenazadas (actualmente protege más de 30.000) con certificados, cuotas y regulaciones. ¿Por qué limitarse a la protección directa de las especies y no abarcar también las actividades económicas que las ponen en peligro?, sugiere el equipo de Lenzen. La concienciación de la sociedad, el etiquetado apropiado con información sobre la huella en la biodiversidad en muchos producto o la extensión de las regulaciones medioambientales a los países que reciben en su territorio actividades económicas deslocalizadas son ideas a tener en cuenta.
Esta noticia, extraída del la versión digital del periódico El País, nos habla de cómo afectan cosas que creíamos sin la más mínima importancia al medio ambiente. Por ejemplo,el cultivo del café afecta a aquellos lugares en los que se cultiva (México, Colombia e Indonesia). Otros casos son la soja y la producción de carne con su efecto negativo sobre la selva en Brasil; la pesca den Nueva Guinea Papúa, las plantaciones para obtener aceite de palma en Indonesia y en Malasia o la captura de peces de colores para acuarios en Vietnam.
Las actividades humanas están causando la sexta extinción masiva del planeta.
Pero estas investigaciones no se limitan a desentrañar la interrelación entre pérdida de biodiversidad y consumo remoto, sino que toman en consideración iniciativas que pueden atenuar los efectos.
It is amazing that so many early birds had large leg feathers. These findings are important for both flight origin and feather evolution. These fossil traces, however, do not indicate how these ancient animals used their rear set of feathers and this small sampling does not prove that four wings was the rule for all early birds. This four wings might have helped early birds out by allowing the hindlimbs to become dedicated legs that could help them get around better on the ground. But he origin of flight is not going to come from just one discovery.
Scientists have found the answer to why female killer whales have the longest menopause of any non-human species -- to care for their adult sons. Led by the Universities of Exeter and York and published in the journal Science (Sept. 14, 2012) the research shows that, for a male over 30, the death of his mother means an almost 14-fold-increase in the likelihood of his death within the following year.
The reason for the menopause remains one of nature's great mysteries and very few species have a prolonged period of their lifespan when they no longer reproduce, as in humans. However, female killer whales stop reproducing in their 30s-40s, but can survive into their 90s. While different theories have been put forward for the evolution of menopause in humans, including the well-established 'grandmother' hypothesis, there has been no definitive answer to why females of a small number of other species, including killer whales, also stop reproducing part-way through their lives.
The research team, from the Universities of Exeter and York (UK), the Center for Whale Research (USA) and Pacific Biological Station (Canada) analysed records spanning 36 years, of the members of two populations of killer whales (Orcinus orca) in the North Pacific ocean, off the coast of the USA and Canada.
They found that the presence of a female who was no longer reproducing significantly increased her older offspring's survival. In the case of males over the age of 30, a mother's death meant a 14-fold increase in the likelihood of their death within a year. Females also stay within their mother's group but for daughters of the same age, the difference is just under three-fold. For females under the age of 30, the death of their mothers had no effect on their survival rates.
Killer whales live in unusual social groups, with sons and daughters staying with their mothers in a single group throughout their lives. With this close association, older mothers have the opportunity to increase the transmission of their genes by helping their adult offspring survive and reproduce. When sons mate, their offspring are cared for by females in another group, whereas when daughters reproduce the offspring stay in the group, which increases local competition for resources within the group.
Theory predicts that in order to have the best chance of spreading their genes, without carrying an additional burden, mothers should focus their efforts on their sons. This research backs up this theory and demonstrates the extent to which older sons are dependent on their mothers for survival.
Lead author on the paper University of Exeter PhD student Emma Foster said: "Killer whales are extraordinary animals and their social groups are really unusual in that mothers and their sons are lifelong companions. Our research suggests that they have developed the longest menopause of any non-human species so that they can offer this level of commitment to their older offspring."
Dr Dan Franks, from the Department of Biology at the University of York, said: "Our analysis shows that male killer whales are pretty much mommy's boys and struggle to survive without their mother's help. The need for mothers to care for their sons into adulthood explains why killer whales have evolved the longest post-reproductive lifespan of any non-human animal."
Dr Darren Croft of the University of Exeter added: "Both humans and killer whales are unusual in having a long menopause. Although they share this trait, the way older females benefit from ceasing reproduction differs, reflecting the different structure of human and killer whale societies. While it is believed that the menopause evolved in humans partly to allow women to focus on providing support for their grandchildren, it seems that female killer whales act as lifelong carers for their own offspring, particularly their adult sons. It is just incredible that these sons stick by their mothers' sides their entire
lives."
An international team of scientists recently announced the discovery of a new species of blind deep-sea crab whose legs are covered with long, pale yellow hairs. This crab was first observed in March 2005 by marine biologists using the research submarine Alvin to explore hydrothermal vents along the Pacific-Antarctic ridge, south of Easter Island. Because of its hairy legs, this animal was nicknamed the "Yeti crab," after the fabled Yeti, the abominable snowman of the Himalayas.
The Yeti crab is a crustacean unlike any other. It measures about 15 inches and is 10 feet (such as crayfish). He is blind, has no eyes and instead there is only a remnant of them, a membrane.
They live in deep, dark waters of the Pacific. They were discovered recently, in 2005 and now at last six years later, scientists tell us they have found out details about their behavior.
His real name is Kiwa hirsuta. 'Kiwa' in honor of the goddess of the shells of the mythology of Easter Island, where it was discovered. And 'shaggy' for their hair.
The cyanobacterium Synechocystis produces several toxins. However, most of the time they cannot become active because the unicellular organism usually only produces them together with an antitoxin that neutralizes their poisonous effect. This is a trick of nature: The genes for the toxin and the antitoxin are located together on a plasmid, i.e. a fragment of DNA that exists independently of the actual bacterial chromosome. In contrast to the toxin, the antitoxin is not very stable. When a cell loses the plasmid during cell division, both of the genes are lost. Since the toxin is more stable than the antitoxin and is thus effective for a longer period of time, these cells eventually die off. Hence, the toxin-antitoxin pairs constitute a natural selection mechanism that sees to it that only cells which retain the plasmid survive.
This is a trick of nature.
When a cell loses the plasmid during cell division, both of the genes are lost. Since the toxin is more stable than the antitoxin and is thus effective for a longer period of time, these cells eventually die off.
So the toxin-antitoxin pairs constitute a natural selection mechanism that sees to it that only cells which retain the plasmid survive.
If the plasmid with this system gets lost in cell division, several toxins thus see to it that the bacterium is killed.
This system has special significance for the cyanobacterial cell.
Early birds flew on four wings
http://www.nature.com/news/early-birds-flew-on-four-wings-1.12613
Instead of two wings, the first birds might have used four feathered limbs to stay aloft, according to research published today in Science.
Birdlike dinosaurs, such as Microraptor and Sinornithosaurus, are known to have had long, sturdy feathers on their hindlimbs. But until now, researchers were not sure whether the earliest birds had already abandoned this extra plumage when they emerged to take to the Cretaceous skies over 100 million years ago.
The researchers, led by Xing Xu, a palaeontologist at the Institute of Geology and Paleontology in Shandong, China, found evidence of feathers on the hindlimbs of 11 basal bird specimens (gathered from the Lower Cretaceous Jehol Group in China). On some of the individuals, these feathers appeared to be veined flight feathers that stood perpendicular to the leg bones, similar to those in the basal bird Archaeopteryx.
One specimen, attributed to the Sapeornis genus, had at least one hindlimb feather longer than 50 millimetres. Feathers on the feet were shorter, but were still more than 30 millimetres long.
"It is amazing that so many early birds had large leg feathers," Xu says. The first winged dinosaurs were discovered just 10 years ago, he notes. These findings "are important for both flight origin and feather evolution".
These fossil traces, however, do not indicate how these ancient animals used their rear set of feathers — whether for gliding assistance, steering or both. And this small sampling does not prove that four wings was the rule for all early birds, says Mark Norell a palaeontologist at the American Museum of Natural History in New York. "Flight is many things to many people," he notes. "The origin of flight is not going to come from just one discovery."
Since the era of these early four-winged fowl, scales have replaced most feathers on modern birds' legs. But with a few genetic changes, these coverings can turn back into feathers, such as in Silkie chickens, which have feathered feet. One specimen from the latest study, belonging to the genusYanornis, already had some scales below its feathered parts. And modern fowl have not lost all their rear plumage, which is now downier and used for warmth.
Downsizing from four wings might have helped early birds out by allowing the hindlimbs to become dedicated legs that could help them get around better on the ground, the researchers suggest. And as exciting as the discovery of hind-leg flight feathers might be, says Norell, other clues are needed to really understand the locomotion of birds. “What would really be a smoking gun is if they found footprints.”
It is amazing that so many early birds had large leg feathers. These findings are important for both flight origin and feather evolution. These fossil traces, however, do not indicate how these ancient animals used their rear set of feathers and this small sampling does not prove that four wings was the rule for all early birds. This four wings might have helped early birds out by allowing the hindlimbs to become dedicated legs that could help them get around better on the ground. But he origin of flight is not going to come from just one discovery.
Long Menopause Allows Killer Whales to Care for Adult Sons
http://www.sciencedaily.com/releases/2012/09/120913141415.htm
Scientists have found the answer to why female killer whales have the longest menopause of any non-human species -- to care for their adult sons. Led by the Universities of Exeter and York and published in the journal Science (Sept. 14, 2012) the research shows that, for a male over 30, the death of his mother means an almost 14-fold-increase in the likelihood of his death within the following year.
The reason for the menopause remains one of nature's great mysteries and very few species have a prolonged period of their lifespan when they no longer reproduce, as in humans. However, female killer whales stop reproducing in their 30s-40s, but can survive into their 90s. While different theories have been put forward for the evolution of menopause in humans, including the well-established 'grandmother' hypothesis, there has been no definitive answer to why females of a small number of other species, including killer whales, also stop reproducing part-way through their lives.
The research team, from the Universities of Exeter and York (UK), the Center for Whale Research (USA) and Pacific Biological Station (Canada) analysed records spanning 36 years, of the members of two populations of killer whales (Orcinus orca) in the North Pacific ocean, off the coast of the USA and Canada.
They found that the presence of a female who was no longer reproducing significantly increased her older offspring's survival. In the case of males over the age of 30, a mother's death meant a 14-fold increase in the likelihood of their death within a year. Females also stay within their mother's group but for daughters of the same age, the difference is just under three-fold. For females under the age of 30, the death of their mothers had no effect on their survival rates.
Killer whales live in unusual social groups, with sons and daughters staying with their mothers in a single group throughout their lives. With this close association, older mothers have the opportunity to increase the transmission of their genes by helping their adult offspring survive and reproduce. When sons mate, their offspring are cared for by females in another group, whereas when daughters reproduce the offspring stay in the group, which increases local competition for resources within the group.
Theory predicts that in order to have the best chance of spreading their genes, without carrying an additional burden, mothers should focus their efforts on their sons. This research backs up this theory and demonstrates the extent to which older sons are dependent on their mothers for survival.
Lead author on the paper University of Exeter PhD student Emma Foster said: "Killer whales are extraordinary animals and their social groups are really unusual in that mothers and their sons are lifelong companions. Our research suggests that they have developed the longest menopause of any non-human species so that they can offer this level of commitment to their older offspring."
Dr Dan Franks, from the Department of Biology at the University of York, said: "Our analysis shows that male killer whales are pretty much mommy's boys and struggle to survive without their mother's help. The need for mothers to care for their sons into adulthood explains why killer whales have evolved the longest post-reproductive lifespan of any non-human animal."
Dr Darren Croft of the University of Exeter added: "Both humans and killer whales are unusual in having a long menopause. Although they share this trait, the way older females benefit from ceasing reproduction differs, reflecting the different structure of human and killer whale societies. While it is believed that the menopause evolved in humans partly to allow women to focus on providing support for their grandchildren, it seems that female killer whales act as lifelong carers for their own offspring, particularly their adult sons. It is just incredible that these sons stick by their mothers' sides their entire
lives."
Menopause is a rare phenomenon in the natural world. In most species, the female disappears once their reproductive period ends, because there is no practical advantage in survival. For many years, scientists have wondered the causes of this phenomenon and found that in some animals, such as orcas, the situation is similar to the humans. Females live post-reproductive stage that lasts decades. They begin to be fertile at the age of 12, stop reproducing at 30-40 and live until 90. The strange thing is that this does not happen in males, who die young. So mothers living longer, better ensure the survival of the children. It seems a clear evolutionary advantage.
Basking Shark
http://new-brunswick.net/new-brunswick/sharks/species/basking.html
The basking shark is the second largest fish in the world, second only to another filter feeder, the whale shark. This animal can attain lengths of at least 10 meters (33 feet), but the average size is 7-9 meters. They can weigh up to 4 tons. The shape of its snout is conical and the gill slits extend around the top and bottom of its head. Associated with the gills are structures called gill rakers. These gill rakers are dark and bristle like and are used to catch plankton as water filters through the mouth and over the gills. The basking shark is usually grayish-brown in colour and often seems to have a mottled appearance. The caudal (tail) fin has a strong lateral keel and a crescent shape. The teeth in the basking shark are very small and numerous and often number one hundred per row. The teeth themselves have a single conical cusp, are curved backwards and are the same on both the upper and lower jaws.
Basking sharks are a migrating species and are believed to overwinter in deep waters. They may occur in either small schools or alone. Small schools in the Bay of Fundy have been seen swimming nose to tail in circles in what may be a form of mating behavior. Basking sharks are not aggressive and generally harmless to people. The number of basking sharks is unknown, but may be decreasing since the basking shark is hunted for its meat, fins and oil.
Basking sharks are a migrating species and are believed to overwinter in deep waters. They may occur in either small schools or alone. Small schools in the Bay of Fundy have been seen swimming nose to tail in circles in what may be a form of mating behavior. Basking sharks are not aggressive and generally harmless to people. The number of basking sharks is unknown, but may be decreasing since the basking shark is hunted for its meat, fins and oil.
Fish that feed on plankton, small fish and invertebrates. You could say that the basking shark is a "fish person" as it moves very slowly and just open his mouth and capturing everything going his way.
The basking shark is a fish completely harmless to humans despite their size and look so menacing. They have come to see species more than 12 meters and with more than 9 tons, which were highly sought by anglers for its high amount of meat and oil. Although I must say that the size of these basking sharks is about 6-7 meters.
*Formerly when this fish skeletons found believed to be of prehistoric animals, particularly sea snakes.
*It is a semi-protected fish. In many countries trade in their meat or products is prohibited.
*The shark-fish is a major attraction for tourists and divers, being an animal dramatic yet very quiet and slow is ideal to observe in their natural environment.
Discovery of the "Yeti Crab"
http://www.mbari.org/news/homepage/2006/yeti-crab.html
An international team of scientists recently announced the discovery of a new species of blind deep-sea crab whose legs are covered with long, pale yellow hairs. This crab was first observed in March 2005 by marine biologists using the research submarine Alvin to explore hydrothermal vents along the Pacific-Antarctic ridge, south of Easter Island. Because of its hairy legs, this animal was nicknamed the "Yeti crab," after the fabled Yeti, the abominable snowman of the Himalayas.
The Yeti crab was discovered during the Easter Microplate expedition to the southeast Pacific, led by MBARI scientist Bob Vrijenhoek. The primary goal of this expedition was to learn how bottom-dwelling animals from one deep-sea hydrothermal vent are able to colonize other hydrothermal vents hundreds or thousands of miles away. Vrijenhoek and his team were addressing this question by comparing the DNA of animals at hydrothermal vents in different parts of the Pacific Ocean.
During one Alvin dive, marine biologist Michel Segonzac, from Institut français de recherche pour l'exploitation de la mer (IFREMER) in France, noticed an unusually large (15-cm-long) crab with hairy arms lurking on the seafloor. Segonzac asked the Alvin pilots to collect this crab and bring it back to the surface.
The researchers saw more of these unusual crabs during subsequent Alvin dives. Most of the crabs were living at depths of about 2,200 meters (7,200 feet) on recent lava flows and areas where warm water was seeping out of the sea floor. According MBARI biologist Joe Jones, "Many of the crabs were hiding underneath or behind rocks—all we could see were the tips of their arms sticking out."
After returning to shore, researchers Segonzac and Jones worked with Enrique Macpherson from the Consejo Superior de Investigaciones Científicas (CSIC) in Spain to identify the crab they had collected. They found that the crab was not only a new species (which they named Kiwa hirsuta), but an entirely new family (Kiwaidae). The Yeti crab is a distant relative to the hermit crabs commonly seen lurking in tide pools.
Ever since deep-sea hydrothermal vents were first discovered in the late 1970s, marine biologists have been fascinated by the unique animals that live in these areas. Hydrothermal vents often form near mid-ocean ridges, where hot lava rises up beneath the seafloor, causing the Earth's crust to split apart. The rising lava heats water within these fractured subsurface rocks, which eventually seeps or gushes out of the seafloor, carrying minerals that are rich in sulfur and metals. Specialized bacteria live off of these hot, metal-rich hydrothermal fluids. Amazingly, a variety of deep-sea animals have found ways to incorporate the sulfur-loving bacteria within their bodies, so that they too can obtain nutrition from the chemicals flowing up out of the seafloor.
The Yeti crab is a crustacean unlike any other. It measures about 15 inches and is 10 feet (such as crayfish). He is blind, has no eyes and instead there is only a remnant of them, a membrane.
They live in deep, dark waters of the Pacific. They were discovered recently, in 2005 and now at last six years later, scientists tell us they have found out details about their behavior.
His real name is Kiwa hirsuta. 'Kiwa' in honor of the goddess of the shells of the mythology of Easter Island, where it was discovered. And 'shaggy' for their hair.
Suicidal Bacteria
http://www.sciencedaily.com/releases/2013/03/130315074607.htmThe cyanobacterium Synechocystis produces several toxins. However, most of the time they cannot become active because the unicellular organism usually only produces them together with an antitoxin that neutralizes their poisonous effect. This is a trick of nature: The genes for the toxin and the antitoxin are located together on a plasmid, i.e. a fragment of DNA that exists independently of the actual bacterial chromosome. In contrast to the toxin, the antitoxin is not very stable. When a cell loses the plasmid during cell division, both of the genes are lost. Since the toxin is more stable than the antitoxin and is thus effective for a longer period of time, these cells eventually die off. Hence, the toxin-antitoxin pairs constitute a natural selection mechanism that sees to it that only cells which retain the plasmid survive.
The plasmid pSYSA of the cyanobacterium Synechocystis has not one but seven different systems of this kind and is thus well protected. The reason for this is because in addition to the genes for the seven toxin-antitoxin pairs, the plasmid pSYSA possesses the genetic information for a bacterial immune system. If the plasmid with this system gets lost in cell division, several toxins thus see to it that the bacterium is killed. The fact that the genes responsible for it are combined with a high amount of toxin-antitoxin pairs indicates that this system has special significance for the cyanobacterial cell.
This is a trick of nature.
When a cell loses the plasmid during cell division, both of the genes are lost. Since the toxin is more stable than the antitoxin and is thus effective for a longer period of time, these cells eventually die off.
So the toxin-antitoxin pairs constitute a natural selection mechanism that sees to it that only cells which retain the plasmid survive.
If the plasmid with this system gets lost in cell division, several toxins thus see to it that the bacterium is killed.
This system has special significance for the cyanobacterial cell.
Revista Quo nº207. Diciembre 2012.
Guardaespaldas de corales.
Cuando el Acropora nasuta de la isla Fiji detecta la presencia de algas tóxicas, emite una señal química de auxilio a los peces que lo habitan para que acaben con ellas. Se produce una cuidadosa danza de olores que da la voz de alarma y moviliza a este particular ejército. Se trata de una relación de protección mutua. Los peces gobio que atacan a estas algas comiéndoselas reciben también una protección, ya que los vuelven menos atractivos hacia sus depredadores.
Dinosaurio enano y puercoespín.
Del tamaño de un gato era este dinosaurio Pegomastaxafricanus.
El saurio era hervíboro pero tenía esos colmillos tan poderosos para cortar y arrancar plantas, aunque también para defenderse de los peligros, a lo que quizá también ayudaban sus espinas.
Se han tardado 30 años en identificarlo.
La serpiente que cura.
El veneno mortal de la bamba negra contiene dos toxinas que son capaces de aliviar el dolor con mejores resultados que la morfina, y menos efectos secundarios.
Investigaciones como estas abren las puertas a una nueva generación de analgésicos de gran potencia que no tengan consecuencias por el uso prolongado.
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