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Men, your sperm know how heavy you are. A new study reveals that sperm carry different chemical tags on their DNA depending on whether their owner is lean or obese. The findings suggest that men may be able to pass information about the availability of food in their environment down to their offspring, which could influence their child's odds of being overweight.

Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? Before a meiotic cell divides, its two sets of chromosomes come together and cross over, or swap, segments. The first animation shows normal crossing over, where the X and Y chromosomes exchange pieces only at their tips. The second animation shows a rare mistake in which the Y chromosome transfers a gene called SRY to the X chromosome, resulting in sex-reversed babies. Studies of sex-reversed individuals led researchers to identify the master switch for sex determination, the SRY gene, which tells a fetus to become a boy.

Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? Before a meiotic cell divides, its two sets of chromosomes come together and cross over, or swap, segments. The first animation shows normal crossing over, where the X and Y chromosomes exchange pieces only at their tips. The second animation shows a rare mistake in which the Y chromosome transfers a gene called SRY to the X chromosome, resulting in sex-reversed babies. Studies of sex-reversed individuals led researchers to identify the master switch for sex determination, the SRY gene, which tells a fetus to become a boy.

The team, led by senior authors Qi Zhou and Xiao-Yang Zhao, both from the Institute of Zoology at the Chinese Academy of Sciences, took embryonic stem cells from mice and treated them to a series of carefully worked out steps that included first exposing the stem cells to testicular cells in newly born male mice. The scientists then recreated the chemical environment that sperm cells need to grow, including early development factors and sex hormones including testosterone, follicle stimulating hormone and a growth factor from the pituitary gland.

This interrupted case study explores the role of cytoskeletal structures on human health, specifically on respiratory function, sperm motility, and female fertility. It follows the story of a couple struggling to conceive a child and the doctors working to help them. Students are presented with clinical histories, narrative elements, documentary-style videos, and microscopic evidence in order to determine the cause of the couple's infertility. Along the way, they learn about the three types of cytoskeletal elements and the roles these play in cellular biology and human physiology. The use of videos makes it suitable for the "flipped classroom," allowing students to prepare outside the classroom for the case study, which they then complete in class. An original video by the author on the structure and function of microtubules, microfilaments, and intermediate filaments is included. The case was developed for an introductory level general biology course and could be delivered during a unit on the cell structure and function. The case could also be used in a cell biology course.

Scientists were investigating a tantalizing but controversial hypothesis: that a man's experiences can alter his sperm, and that those changes in turn may alter his children.

In 1674, Antonie van Leeuwenhoek looked at a drop of lake water through his homemade microscope and discovered an invisible world that no one knew existed. His work inspired countless microbiology researchers, including HHMI investigator Bonnie Bassler, one of the narrators of this animated feature. Leeuwenhoek was a haberdasher and city official in Delft, The Netherlands. He started making simple microscopes and using them to observe the world around him. He was the first to discover bacteria, protists, sperm cells, blood cells, rotifers, and much more. 

Using a pre-drawn template can be helpful during a consultation to explain single gene inheritance. Our template shows one pair of chromosomes for each parent. Each chromosome has a single gene highlighted that can be coloured in to illustrate a gene alteration. You can then show which sperm and/or eggs contain the chromosome with the gene alteration and the different genetic combinations that could be present at conception.

Following on the achievements of Chinese researchers, scientists in the United States have used CRISPR to manipulate the genomes of viable human embryos, MIT Technology Review reported yesterday (July 26). The work, not yet published, reportedly corrected defective genes from sperm donors in dozens of embryos, which were allowed to grow for several days.

groups of cells in the blastula are synchronized to divide at the same time through mitosis. Some of these cells will eventually give rise to the sand dollar's germ cells. Others will play important roles in various developmental processes, such as cell differentiation, the formation of the digestive system, and the development of the exoskeleton. Despite their different characteristics and roles, all of the sand dollar's cells (except for eggs or sperm) are genetically identical due to mitosis.