Almost all snakes reproduce sexually, with the participation of female and male. Only certain species are capable of parthenogenesis, i.e. the reproduction is not transmitted sexually, and from unfertilized eggs without the participation of a male. There among the snakes, as a rare exception, and true hermaphrodites, i.e. individuals who are simultaneously female and male. Such exceptional case was recorded on the small island of Queimada-Grande, South America. There were found the snake, dubbed the island bothrops, among which, in addition to ordinary females and males, meet bisexual individuals who make up the majority of the population. These individuals are females, while the ovaries are the male copulatory organs and Mature testes. Such individuals may in some cases play the role of females and to breed, and the males are fertilizing other females (ordinary or hermaphrodite). The existence in the population of the island bothrops such unusual females is so efficient, the need for normal males has dropped, and their share in recent years has declined.
The female from the male in the overwhelming majority of snake species difficult to distinguish. The serpent the visible Continue reading
Found a gene that determines, will become a gamete sperm or egg
Japanese genetics found in the DNA of fish unusual gene that determines it, will the sex cell sperm or egg, and changed his work so that in the ovaries of female fish began to form spermatozoa and in the testes of males of the egg, according to a paper published in the journal Science .
“We knew that gametes can turn into sperm and ovum, but no one has suggested that these cells in the vertebrate animals have a special gene”switch” that determines their fate – to become a sperm or egg. Our results indicate that the cell is able to go all the way. This is a very important and unexpected discovery” – quoted by RIA “Novosti” scientist Minoru Tanaka from the Institute of General biology of Japan in the city of Okazaki.
Tanaka and his colleagues made this unusual discovery, watching the development of germ cells in testes and ovaries rice fish-oriii (Oryzias latipes). During maturation of sperm and egg cells, researchers monitored changes in the level of activity of different genes, trying to find the differences between future male and female reproductive cells.
The attention of scientists was attracted to gene foxl3 – “archival copy” of the gene foxl2, which is responsible for growth of eggs and maintaining Continue reading
A very large representative of the genus, reaching more than 2 meters in length. The representative of the only two species of bog on the African continent.
Inhabiting rain-forests and on the plains along the rivers almost throughout Equatorial Africa from West to East. This Western Kenya, Uganda, South Sudan, Angola, Gabon, Cameroon, Equatorial Guinea, Central African Republic, Nigeria, Senegal, the Gambia, Benin, Liberia, Guinea, Congo, Zambia. Species readily climbs trees and swims well, is commonly found in scrub, where it hunts birds. Leads nocturnal. Bites to humans are quite dangerous.
This species is named after American naturalist and Explorer William Blanding’s turtles (1772 – 1857). Very interesting and quite a rare snake in terms of content. The peculiarity of this species, in addition to obscure systematic belonging to the genus Boiga by Toxicodryas is rare for snakes sexual dimorphism. Males of this species have bluish-black body with yellow bases at the head and yellow spots in the anterior third of the body. Females have a grey body with brown spots and stripes. Fry first colored the same as adult females, but very quickly the males peretsvetayut.
For the content Continue reading