Designing a Genetic Screen to Identify Factors Required for Meiotic Nuclear Rejuvenation

During the natural cycle of life, most eukaryotic organisms grow old, age, and die. A common natural mechanism by which organisms “reset” their lifespan is through sexual reproduction; however, how this rejuvenation takes place remains unknown. My lab has found that meiosis in budding yeast, the developmental program that forms sex cells, eliminates age-induced damage. This involves the formation of a novel nuclear compartment, the Gametogenesis Uninherited Nuclear Compartment (GUNC), which acts as a trash can for accumulated age-induced damage. To understand the molecular details of this process, I worked on designing a screen for genes involved in GUNC formation. My mentor and I fused three different proteins targeted to the GUNC and a protein that is able to bind to a drug-resistance plasmid, in order to couple the inheritance of a selectable DNA marker with the elimination of age-induced damage. Initial testing of these three fusion proteins suggested that they were unable to successfully target the plasmid to the GUNC; as such, testing of additional candidate proteins is necessary. We plan to eventually use this system to identify mutations that disrupt GUNC formation and cause inheritance of the drug-resistance plasmid. By identifying and perturbing proteins involved in GUNC formation, we are hoping to be able to drive the inheritance of specific types of age-induced damage, allowing for the determination of what a symptom versus a cause of aging is.

Comparative results of rearing pure species and hybrid forms of the Siberian and Russian sturgeons

In the paper, rearing results and comparative assessment of interspesific hybrids and pure species of the Siberian sturgeon Acipenser baerii (Brandt, 1869)and the Russian sturgeon Acipenser gueldenstaedti (Вrandt, 1833) have been provided at various stages of ontogenesis by combinated cultivation under RAS conditions and in an industrial uniflow tank farm. Investigations were carried out at the “Konakovski” department of the Branch on Freshwater Fisheries FSBSI “VNIRO” (VNIIPRKh). To obtain the experimental material breeders were used of the Siberian sturgeon from the sixth domestication generation and of the Russian sturgeon from the third one. Fish fry, switched to mixed feeding ongrowing and further rearing, were cultivated under production conditions in normal technological mode and separately from each female using different granulated mixed feeds (BioMar firm) of different recipes. Up to 41 day-age fish were reared in RAS, further in race-ways and tanks of the shop with uniflow water-supply. The middle water temperature was 16ºC during the all period of experimental works (557 days). Best results of the mass accumulation showed interspecific LS×RS hybrids, at the second position seemed to be RS×LS hybrids. Pure species of the Siberian and Russian sturgeons showed practically similar middle weights to the end of the experimental stage. As a result of the histological analysis, it has been ascertained that gonads of pure species of one-year-old Siberian and Russian sturgeons and their hybrids had comparatively the same picture of sex cells development, but some advantage possessed the Siberian sturgeon and LS×RS hybrid. Thus, malesʼ cysts and femalesʼ nests of one-year-old fish show multiple mitotic divisions of sex cells (spermatogonia and oogonia) what corresponds with the first stage of gonades maturity in males and the first one and the beginning of the second ones in females.

Ethical problems of mitochondrial replacement

Применение любой новой вспомогательной репродуктивной технологии, связанной с манипуляциями человеческими половыми клетками и эмбрионами неизбежно будет спорным с этической точки зрения. Такой технологией является митохондриальное замещение, которое позволяет родить здорового ребенка женщине, страдающей митохондриальным заболеванием. The use of any new assisted reproductive technology related to the manipulation of human sex cells and embryos will inevitably be controversial from an ethical point of view. This technology is mitochondrial replacement, which allows a woman suffering from mitochondrial dysfunction to give birth to a healthy child.

The Case of Qualitative Genetics in Fish

Character inheritance or heredity is the inheritance of traits from parents to their children (offspring). The event or process by which a cell of an organism tends to become or possess the characteristics of its parents. The discovery of recombinant DNA opened up developments in genetic engineering. Genetic engineering technology provides a lot of hope for us in various areas of need including gene therapy efforts. Inheritance is the traits or traits of living things that are passed down from generation to generation or passed down from parent to offspring. The traits of a living being are inherited through male sex cells and female sex cells. Normal pigmented goldfish are mated with yellow-striped goldfish on the dorsal spine to produce 100% fish with yellow lines on the dorsal spine.

Prognosis of an interspawning interval duration in sturgeons reared at a tank uniflow fish farm

The material of long-term research on fixing duration of interspawning Siberian sturgeon and sterlet females maturation has been provided. For the first time, to forecast the next females maturation term under conditions of an industrial farm, showing an average annual heat sum of 5600 degree-days, it is proposed to select sex cells in 6 months after sex products obtaining by biopsy method. Therefore, the females spawning start could be predicted based on histological pattern of oocytes development. It allows to plan females participation in sex products obtaining process for fish reproduction or caviar production.

Fitness differences suppress the number of mating types in evolving isogamous species

Sexual reproduction is not always synonymous with the existence of two morphologically different sexes; isogamous species produce sex cells of equal size, typically falling into multiple distinct self-incompatible classes, termed mating types. A long-standing open question in evolutionary biology is: what governs the number of these mating types across species? Simple theoretical arguments imply an advantage to rare types, suggesting the number of types should grow consistently; however, empirical observations are very different. While some isogamous species exhibit thousands of mating types, such species are exceedingly rare, and most have fewer than 10. In this paper, we present a mathematical analysis to quantify the role of fitness variation—characterized by different mortality rates—in determining the number of mating types emerging in simple evolutionary models. We predict that the number of mating types decreases as the variance of mortality increases.

Procreation Deprived

When professional negligence renders sex cells unusable or reproductive capacities inoperative, shattered dreams of pregnancy and parenthood find little solicitude under American law. Our legal system fails to recognize reproductive suffering from which a plaintiff’s body and bank account emerge unscathed—because tort law usually compensates for intangible losses only if they’re closely connected to material ones. But people deprived of procreation can’t point to any bodily harm or financial setback that’s tied directly to the injury they’ve suffered. Claims almost always fail because patients don’t incur any property damage (eggs and embryos aren’t considered property) or physical intrusion (aside from whatever medical procedure they freely agreed to). Besides, courts point out, even if fertility treatment goes as planned, patients might not have been able to conceive or carry a pregnancy to term anyway—and they can still adopt. Judges who don’t dismiss these suits outright keep a tight rein on damage awards; these courts miss the centrality of procreation to aspiring parents and the magnitude of its wrongful deprivation. Still, badly behaving specialists shouldn’t be liable for the infertility that patients already suffered from, or other reproductive complications they would have anyway, no matter what quality medical care they received. Probabilistic recovery offers a principled way to compute damages for the wrongful destruction of gametes or embryos under these circumstances. The availability of adoption doesn’t negate this reproductive loss or the need for our laws to redress it. Genetic affinity assumes profound meaning in American family life and law.

Natural depletion of histone H1 in sex cells causes DNA demethylation, heterochromatin decondensation and transposon activation

Transposable elements (TEs), the movement of which can damage the genome, are epigenetically silenced in eukaryotes. Intriguingly, TEs are activated in the sperm companion cell – vegetative cell (VC) – of the flowering plant Arabidopsis thaliana. However, the extent and mechanism of this activation are unknown. Here we show that about 100 heterochromatic TEs are activated in VCs, mostly by DEMETER-catalyzed DNA demethylation. We further demonstrate that DEMETER access to some of these TEs is permitted by the natural depletion of linker histone H1 in VCs. Ectopically expressed H1 suppresses TEs in VCs by reducing DNA demethylation and via a methylation-independent mechanism. We demonstrate that H1 is required for heterochromatin condensation in plant cells and show that H1 overexpression creates heterochromatic foci in the VC progenitor cell. Taken together, our results demonstrate that the natural depletion of H1 during male gametogenesis facilitates DEMETER-directed DNA demethylation, heterochromatin relaxation, and TE activation.