A small protein called ubiquitin marks abnormal sperm cells, including cells that have two heads, two tails or are otherwise misshaped. This “recycling tag” on the sperm cell tells the body which cells need to be broken back down into amino acids. This provides evidence that there is an active removal process or marking of defective sperm during the epididymal passage.
“Fertilization is, in a way, a numbers game,” said Peter Sutovsky, associate professor of animal sciences, clinical obstetrics and gynecology in the MU College of Agriculture, Food and Natural Resources. “You need a certain number of normal sperm cells to reach the egg. If too many are tagged with ubiquitin, there may be not enough to fertilize an egg.”
This study suggests that the male reproductive system must be able to evaluate and control the quality of the sperm to insure an optimal chance of fertilization. High levels of ubiquitin in the sperm can indicate low-sperm count or infertility. This process of quality control has been found in both humans and other mammals including bulls, boars and rats.
“In many cases, the cells that are tagged with ubiquitin are obviously abnormal with two tails or two heads, but many of them look like they don’t have defects,” Sutovsky said. “Oftentimes, these cells may look normal but lack proteins that are important to fertility.”
Once sperm cells are tagged as defective, it is unlikely that the process can be reversed. Sutovsky stresses the importance of a healthy lifestyle to reduce the likelihood of abnormal sperm cells. He suggests avoiding exposure to toxic chemicals, abstaining from smoking and maintaining a healthy diet. He suggests people who work with toxins on a daily basis should minimize their exposure by wearing protective clothing and respirators.
Jennifer Faddis | EurekAlert!
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22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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