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A study on the types of sperm ditíscidos question evolution of sex characteristics of male competition. As in “arms race”, changes in the female reproductive tract to the semen forced to adapt.
(Sperm beetle presents a variety of shapes and structures. Image: Dawn Higginson / University of Arizona)
American researchers have studied the sperm and female morphology of 42 species of beetles. These data have identified large variations in the structure of sperm-related developmental changes in the genitalia of females.
“Both sperm morphology and female reproductive tracts have experienced many diversifications in aquatic beetles,” explains to SINC Dawn Higginson, author of the study and researcher at the University of Arizona (USA).
“The dimensions of the sperm and the presence of conjugates (clusters formed in the male sperm that are transferred in copulation) are correlated significantly with the dimensions of the attributes of females,” says Higginson.
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Japanese researchers have succeeded for the first time in mice the production of a pituitary gland from embryonic stem cells. The paper detailing this operation, which involved complex juxtaposition of different types of tissue, appears this week in the latest issue of the journal Nature .
(Enlargement of the pituitary tissue created from embryonic stem cells. Image: Yoshiki Sasai)
The adenohypophysis or anterior pituitary functions as an important center of production of hormones. At present, no type of stem cell culture is capable of generating this type of tissue in humans, but Japanese scientists have just successfully in mice and intend to create a human pituitary in the next three years.
One of the authors of the study, Yoshiki Sasai, the group of Neurogenesis and Organogenesis of the Riken Center for Developmental Biology (Kobe, Japan) has explained to SINC that “as an extension of this success, we plan to apply our technology to human stem cells from the ES (embryonic) and IPS (induced pluripotent). We hope to develop an efficient method for producing human pituitary in the coming years. “
The mouse embryonic stem cells were stimulated in a culture that mimicked three-dimensional tissue interactions, to thereby produce the five hormones generated by different cell types present in the pituitary. The corticotrophic, for example, showed they were capable of secreting the hormone adenocorticotrópica in response to corticotropin-releasing hormone.
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Reveal for the first time that the plesiosaur, a prehistoric marine reptile, not reproduced by eggs but gave birth to live young. The study, published in the journal Science , has made the Marshal University in Huntington (USA) and the Institute of Dinosaurs Museum of Natural History in Los Angeles (NHM, for its acronym in English) from a fossil 78 million years that houses an embryo inside.
(Recreation of the birth of a baby plesiosaur. Image: S. Abramovicz)
The new hall of dinosaurs from the Natural History Museum of Los Angeles has a unique example of adult plesiosaur fossil. As reported in the latest edition of the journal Science , a group of researchers from the museum and the Marshal University in Huntington has found that it is a fossil marine reptile embryo on the inside of the fossil from his mother.
The research, led by Robin O’Keefe, Marshall University in Huntington, and Luis Chiappe, director of the Institute of Dinosaurs Museum of Natural History shows that this double is the first fossil evidence that plesiosaurs gave birth to offspring alive and not incubating eggs in the soil.
This is a Polycotylus latippinus of 15.4 feet in length . A giant reptile, carnivore with four fins called plesiosaurs, which lived during the Mesozoic Era. “The skeleton of the embryo contained inside this issue we also provides information on the development of body, ribs, vertebrae 20, shoulders, hips and bones of the fins,” explained the expert.
”Although there is evidence that other groups of aquatic reptiles of the Mesozoic also gave birth to offspring (and therefore, were viviparous), so far no evidence had been found earlier in an order as important as that of the plesiosaurs’ research aims.
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A study has involved the National Research Council (CSIC) has identified the non-coding DNA sequences oldest known, some of which are present in humans and in relatives of corals. Comparison of the genomes of many animals, distributed by branches of the tree of life, has revealed that not only proteins that we build, but also some instructions on how and where to use them were present in our ancestors for more than 550 million years.
(Zebrafish embryo with human DNA sequence. Image: CSIC.)
“For more than 500 million years of evolution has been selecting ways to combine protein, so that the organs and their physiology have evolved through generations, leading to all kinds of animals living today or that existed in the past. For this reason, one of the goals of contemporary research in biology is to understand the combinatorial mechanism and its evolution, “explains researcher CSIC José Luis Gómez-Skarmeta, the Andalusian Centre for Developmental Biology.
Only 5% of the DNA of vertebrates is coding. This means that only a small part of the genome containing genes capable of generating RNA that serves as a messenger between DNA and the mechanisms that are responsible for developing protein. The remaining 95% of non-coding DNA has been for many years called junk DNA.
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European researchers have discovered a tropical plant ( Marcgravia evenia ), which is pollinated by bats, has developed a parabola-shaped leaves with great resonance. The results, which are now published in Science , show that the pollinators that feed on nectar and flowers can be found two times faster than through echolocation.
(Photomontage of the tropical vine Marcgravia evenia with a bat pollinator. Image: Science)
Bees and birds are guided visually to pollinate flowers with bright colors. But there are signs that attract bioacoustics other pollinators such as bats and allow the dispersal of seeds? Until now little was known about the subject.
The vine of Cuba ( Marcgravia evenia ) has developed a concave blade with flowers reminiscent of a parabolic reflector. According to the British and German scientists, the sheet acts as an acoustic beacon “ideal” strong signals and multi-returns, with acoustic signs easily recognizable and unchanged, to detect bats echolocate flowers.
“This acoustic beacon has benefits for plants and bats. On the one hand increases the efficiency of foraging bats that feed on nectar and flowers visited numerous times each night to meet their energy needs. On the other hand, M. evenia played so little that requires highly mobile pollinators, “said Marc Holderied, co-author and researcher at the School of Biological Sciences, University of Bristol (United Kingdom).
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Neanderthals ceased to exist in Europe 40,000 years ago and still no scientific explanation for this disappearance. Research by the University of Cambridge (UK) published in Science suggests that the invasion was the most advanced Homo sapiens , from Africa to reach populations up to ten times higher, which ended up conquering the territory of the Neanderthals.
What did the Neanderthals, who dominated Europe for 300,000 years and were reproduced and survived the cold temperatures suddenly disappear? A study published this week in the journal Science could offer an explanation to this question that has intrigued scientists for decades.
A team from the University of Cambridge (UK) has been determined by analytical methods detailed the invasion of the population of Homo sapiens , from Africa, was in some places up to ten times that of the Neanderthal himself. Numerical supremacy of Homo sapiens , its most advanced techniques and greater mastery of technique allowed more efficiently take advantage of scarce resources in dispute, and favored the “withering” of the Neanderthal disappearance.
“Our interpretation is that the ancestor of modern man living in larger towns and just flooded the Neanderthals. With this simple explanation, it was speculated for a long time, I did it myself in 1973, but until now we had no concrete data to support this theory.
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An international team of scientists demonstrated in the latest issue of the journal Science , that fishing for species found at the end of the food chain in many ways to harm marine ecosystems. The partial disappearance of sardines, herring and mackerel directly affects marine mammals and seabirds and larger fish.
Until now, scientists had made it clear that the capture of marine predators located at the top of the food chain has severe effects on species of lower trophic level. A new study now shows in the journal Science , where fishing of species at lower levels also hurts.
“Overfishing of species of the later levels have effects on other species in the food chain, especially predators dependent on these small fish. Fishing for these species compete with predators for the same food source, “Anthony explains to SINC DM Smith, author of the study and researcher at the Community Organization of Scientific and Industrial Research (Australia).
The team reviewed five ecosystems around the world and found that fishing anchovies, sardines, herring and mackerel, even at sustainable levels, has impacts on marine mammals, seabirds, sharks and larger fish and commercially important.
“But not all species of higher levels are negatively affected. Some even increased their populations when small fish are overfished, “says Smith.
To reach their findings, the researchers put different fish species at various pressures lower levels of fishing. According to the study, the fish most abundant fish in an ecosystem, or those higher up the food web tend to have major impacts on ecosystems.
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The international marine conservation organization Oceana has discovered nearly 400 feet deep, offshore and covering an area of over 100,000 m2, a white coral reef depth in the Alboran Sea during the 2011 expedition the Oceana Ranger. The extent of the reef could exceed 10 hectares and cover much of the surface of a seamount.
(White coral ( Lophelia pertusa ) found in the Mediterranean Sea. Image: Oceana.)
“Not only talking about a large coral reef, but extensive gardens of gorgonians, black coral forests or fields of glass sponges, all of great importance to the health of the Mediterranean,” says Ricardo Aguilar, research director at Oceana Europe. “Also important are the presence of some rare or little known species such as corals ball, carnivorous sponges, octopus bathyal or faux-candle line,” he adds.
The deep-sea coral ecosystems are among the vulnerable. United Nations has asked to be protected because most of these communities have disappeared from large areas of European and Mediterranean waters due to trawling, the changes in water temperature or catastrophic natural events.
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Being at the top of the social hierarchy of wild baboons is more expensive than you thought. This was revealed by an international study led by Princeton University (USA). The results, now published in the journal Science , confirmed that the alpha males (senior) have a higher stress hormone levels than males with a range below, even during periods of stability.
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Alpha males fight more than other males and have to watch more fertile females. Image: SINC.
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“For the baboons, being on top of the social hierarchy has many advantages: better access to food resources and priority for fertile females reproduce more offspring to ensure a more plentiful,” Laurence told SINC Gesquiere, lead author of study and a researcher in the Department of Ecology and Evolutionary Biology, Princeton University (USA).
However, the study, which is now published in Science , shows that these advantages have certain consequences. “Alpha males are more stressed than males immediately below (beta male),” says Gesquiere adding that the alpha males fight more than other males and have to watch fertile females to prevent other males from reproducing.
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Makes between 250,000 and 350,000 years, the species Homo heidelbergensis inhabited the Sima del Elefante Atapuerca (Burgos) and did so in a Mediterranean climate similar to today. This has been known through the study of remains of mammals obtained at higher levels (TE18 and TE19) of the site.
(Remains of mammals found in the Sima del Elefante)
The mammals have proved a valid tool to determine the paleoenvironment and climate of the prehistoric sites and their chronology. At higher levels (TE18 and TE19) of Sima del Elefante Atapuerca (Burgos) 92 remains have been identified belonging to 17 species: three insectivorous, four bats, new rodent and lagomorphs. Their study reveals that makes 250,000 and 350,000 years, the species Homo heidelbergensis who inhabited the area enjoying a Mediterranean climate.
The association of small mammals places the upper levels of the Sima del Elefante between 250,000 and 350,000 years ago, therefore, is more recent than the level 10 Gran Dolina (TD10) (243000-430000 years before present approx.) and very similar to Gallery (250,000 to 500,000 over), all in Atapuerca.
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(Sperm beetle presents a variety of shapes and structures. Image: Dawn Higginson / University of Arizona)
(Enlargement of the pituitary tissue created from embryonic stem cells. Image: Yoshiki Sasai)
(Recreation of the birth of a baby plesiosaur. Image: S. Abramovicz)
(Photomontage of the tropical vine Marcgravia evenia with a bat pollinator. Image: Science)
What did the Neanderthals, who dominated Europe for 300,000 years and were reproduced and survived the cold temperatures suddenly disappear? A study published this week in the journal Science could offer an explanation to this question that has intrigued scientists for decades.
Until now, scientists had made it clear that the capture of marine predators located at the top of the food chain has severe effects on species of lower trophic level. A new study now shows in the journal Science , where fishing of species at lower levels also hurts.