Researchers create genetically matched embryonic stem cells for transplantation
...hods exist for deriving embryonic stem cells using sperm from men, but these techniques are as technically challenging and inefficient as somatic cell nuclear transfer, Daley says.) There are also potential safety concerns. Embryonic stem cells created through parthenogenesis have altered expression of ce...Durable critters providing insight for human egg preservation
... the interior plasma membrane. As soon as a single sperm penetrates, it triggers intracellular signaling th...meable structure and with good reason: if multiple sperm penetrate, chromosomal abnormalities result. Interestingly, traditional freezing, even with cryopres...A new male-specific gene in algae unveils an origin of male and female
...ise to reproduction though the joining of distinct sperm and egg cells. The findings, which indicate that a...ed during evolution to participate in sex-specific sperm development, are reported by Hisayoshi Nozaki and colleagues at the University of Tokyo, Rikkyo (St....The case of the snuggling skunks -- Is it better to brave winter alone or in a group?
...low body temperature can lead to difficulties with sperm production. Why don't all skunks form communal huddling groups in the winter? The authors point out that there is a higher risk of disease or parasite transmission in communal dens. In addition, predator detection and depletion of resources are also ...Male contraception -- UVa discovery stirring interest among basic scientists and drug developers
...drugs." The newly discovered protein is called sperm flagellar energy carrier (SFEC). It is the fourth ...g developers because of where it is located in the sperm and the kind of energy-making process that occurs there. "One approach to male contraception is t...Rodent sperm work together for better results
Although, sperm are inseminated in millions each sperm goes it alone. However, under some circumstances it might be advantageous for sperm to cooperate wit...Beyond nature vs. nurture: Williams syndrome across cultures
...ulty recombination event during the development of sperm or egg cells. As a result, almost invariably the same set of about 20 genes surrounding the gene for elastin is deleted from one copy of chromosome seven, catapulting the carrier of the deletion into a world where people make much more sense than obj...How does one sex grow larger than the other?
...lthough it is generally cheaper to produce (small) sperm than (large) eggs, it may be costlier to produce male gonads and genitalia than it is to produce female gonads and genitalia. As a result, males might need more time to mature at larger body sizes. This world-wide collaboration developed because m...Male-killing bacteria makes female butterflies more promiscuous
... to fatigue in males. They start producing smaller sperm packages. Unfortunately, the female butterflies in...h female mating frequency and the size of the male sperm package (Spermatophore) per copulation to find how female promiscuity was affected by the sex ratio....Manipulating nature: Scientists query wildlife birth-control method
... prevent either fertilization or the production of sperm and ova. Proponents of the technique, which was first tested nearly 20 years ago, regard it as more humane than the conventional methods of controlling wildlife populations, such as shooting, trapping, poisoning or viral diseases. It has drawn sup...New hope for regenerative medicine
...m cells where both genomes are solely derived from sperm of one male (androgenetic), adding fertile males to the potential patient pool. Since uniparental ES cells are not derived from viable embryos, their harvesting and use sidesteps many of the ethical concerns that plague traditional ES cell therapie...Investigating the trochus 'El Dorado'
...reproductive cycle of fish, where spawned eggs and sperm combine in the sea to produce microscopic larvae that disperse and later settle to become juveniles, they tend to attribute the control of fish populations to other factors, including supernatural forces," he says. While these beliefs remain and th...Penn researchers replace organ in adult mice using 'single-parent' stem cells
... cells - created from a single donor's eggs or two sperm - and, for the first time, successfully used them to repopulate a damaged organ with healthy cells in adult mice. Their findings demonstrate that single-parent stem cells can proliferate normally in an adult organ and could provide a less controver...Universities in San Antonio and Hawaii study safety of assisted reproductive technologies
...ansfer, pre-implantation culture, intracytoplasmic sperm injection and round spermatid injection with mice produced by natural reproduction. The scientists reviewed the DNA of each group looking for "point mutations," genetic errors that are known to underlie many genetic diseases in humans. The analy...The cost of keeping eggs fresh for mother cockroaches
...in the size of their gametes. Males make many tiny sperm while females make only a few large eggs. This suggests that sperm are cheap while eggs are expensive. Yet sperm can be very long lived, while eggs degenerate quickly ...Size matters if you're a rodent
...female rodents, leading to competition between the sperm of rival males over who fertilizes the eggs. It now seems that possessing a longer penis may give males an advantage in this competition, according to new research to be published in the March issue of The American Naturalist. Dr. Steve Ramm, an evo...Treating male infertility with stem cells
... genetically (via mutations in a gene required for sperm production). The donor GFP-expressing cells too...differentiate into cells of the testes involved in sperm production, both germ cells and supporting cells. Interestingly, the germ cells did not differentiat......mones act on the testes, causing the production of sperm as well as the secretion of testosterone. Testoste... for research aimed at improving the production of sperm in men suffering from fertility disorders. Further research is vital if we are to understand the o...Spiders: Chastity belts stop cuckoos in the nest
...ulically: the tip of a transformed leg filled with sperm is inserted into the females sexual orifice like ...f reproductive encounters, a male transfers enough sperm to fertilise all his partners eggs. However, if a rival male then gets a look in, his sperm cells co...Too much weight spells double trouble for couples trying to conceive
... the womans weight and fertility, or where donated sperm was used, the researchers were left with data on 47,835 couples. Ms Ramlau-Hansen said: In this cohort, we had 6.8% obese men, 8.2% obese women and 1.4% couples where both were obese. The percentages of persons with normal weight were 53% for men a...