Nuclear receptor signaling via NHR-49/MDT-15 regulates stress resilience and proteostasis in response to reproductive and metabolic cues.

The ability to sense and respond to proteotoxic insults declines with age, leaving cells vulnerable to chronic and acute stressors. Reproductive cues modulate this decline in cellular proteostasis to influence organismal stress resilience in Caenorhabditis elegans We previously uncovered a pathway that links the integrity of developing embryos to somatic health in reproductive adults. Here, we show that the nuclear receptor NHR-49, an ortholog of mammalian peroxisome proliferator-activated receptor α (PPARα), regulates stress resilience and proteostasis downstream from embryo integrity and other pathways that influence lipid homeostasis and upstream of HSF-1. Disruption of the vitelline layer of the embryo envelope, which activates a proteostasis-enhancing intertissue pathway in somatic cells, triggers changes in lipid catabolism gene expression that are accompanied by an increase in fat stores. NHR-49, together with its coactivator, MDT-15, contributes to this remodeling of lipid metabolism and is also important for the elevated stress resilience mediated by inhibition of the embryonic vitelline layer. Our findings indicate that NHR-49 also contributes to stress resilience in other pathways known to change lipid homeostasis, including reduced insulin-like signaling and fasting, and that increased NHR-49 activity is sufficient to improve proteostasis and stress resilience in an HSF-1-dependent manner. Together, our results establish NHR-49 as a key regulator that links lipid homeostasis and cellular resilience to proteotoxic stress.

The apical cell - An enigmatic somatic cell in leech ovaries - Structure and putative functions.

Although somatic cells play an integral role in animal gametogenesis, their organization and function are usually poorly characterized, especially in non-model systems. One such example is a peculiar cell found in leech ovaries - the apical cell (AC). A single AC can be found at the apical tip of each ovary cord, the functional unit of leech ovaries, where it is surrounded by other somatic and germline cells. The AC is easily distinguished due to its enormous size and its numerous long cytoplasmic projections that penetrate the space between neighboring cells. It is also characterized by a prominent accumulation of mitochondria, Golgi complexes and electron-dense vesicles. ACs are also enriched in cytoskeleton, mainly in form of intermediate filaments. Additionally, the AC is connected to neighboring cells via junctions that structurally resemble hemidesmosomes. In spite of numerous descriptive data about the AC, its functions remain poorly understood. Its suggested functions include a role in forming skeleton for the germline cells, and a role in defining a niche for germline stem cells. The latter is more speculative, since germline stem cells have not been identified in leech ovaries. Somatic cells with similar morphological properties to those of the AC have been found in gonads of nematodes - the distal tip cell - and in insects - Verson's cell, hub cells and cap cells. In the present article we summarize information about the AC structure and its putative functions. AC is compared with other well-described somatic cells with potentially similar roles in gametogenesis.

Changes in the midgut cells in the European cave spider, Meta menardi, during starvation in spring and autumn.

During the growth period, in surface habitats, spiders catch enough prey to feed normally. In contrast, in the cave entrance zone, prey may be relatively scarce. Meta menardi inhabits this cave section, resulting in temporary starvation. We studied structural changes in the midgut epithelial cells of M. menardi during a short-term and a medium-term controlled starvation to mimic the occasional starvation in caves, during spring and autumn. Digestive cells, secretory cells and adipocytes were examined before the experimental starvation, in the middle and at the end of starvation. We used light microscopy, transmission electron microscopy and specific histochemical methods for the detection of lipids, polysaccharides and proteins. Detection of lysosomes, autolysosomes and apoptosis was also carried out. The general structures of the cells did not change during the experimental starvation in either season, while some specific differences in the ultrastructure were observed. In both sexes, in both seasons, the amounts of lipids, glycogen and proteins decreased during starvation. Larger amounts of lipids were found in autumn, while there were no significant differences in the amounts of glycogen and proteins. In both sexes, in both seasons, autophagy and apoptosis intensified with starvation in progress, but more intensively in females. Thus, autumn individuals, in contrast to spring ones, compile energy-supplying stores to confront the subsequent winter deficiency of prey in caves, while the cellular ultrastructures undergo the same starvation-dependant changes at any time during the growth period.

Magnetite Nanoparticles in Magnetic Hyperthermia and Cancer Therapies: Challenges and Perspectives.

Until now, strategies used to treat cancer are imperfect, and this generates the need to search for better and safer solutions. The biggest issue is the lack of selective interaction with neoplastic cells, which is associated with occurrence of side effects and significantly reduces the effectiveness of therapies. The use of nanoparticles in cancer can counteract these problems. One of the most promising nanoparticles is magnetite. Implementation of this nanoparticle can improve various treatment methods such as hyperthermia, targeted drug delivery, cancer genotherapy, and protein therapy. In the first case, its feature makes magnetite useful in magnetic hyperthermia. Interaction of magnetite with the altered magnetic field generates heat. This process results in raised temperature only in a desired part of a patient body. In other therapies, magnetite-based nanoparticles could serve as a carrier for various types of therapeutic load. The magnetic field would direct the drug-related magnetite nanoparticles to the pathological site. Therefore, this material can be used in protein and gene therapy or drug delivery. Since the magnetite nanoparticle can be used in various types of cancer treatment, they are extensively studied. Herein, we summarize the latest finding on the applicability of the magnetite nanoparticles, also addressing the most critical problems faced by smart nanomedicine in oncological therapies.

Oogenesis in three species of Naidinae (Annelida, Clitellata) is extraovarian of the Stylaria type.

Older observations, which were based solely on light microscopy, suggested that the main stages of oogenesis such as yolk uptake, take place outside the ovary, i.e. in the body or the ovisac cavity in some groups of clitellate annelids. Such extraovarian oogenesis was observed in naidines (Naidinae). Because there are no current data about the ovary organization and the course of oogenesis in Naidinae, we analyzed female gametogenesis in three common representatives of this taxon - Stylaria lacustris, Chaetogaster diaphanus and Ripistes parasita - using light, fluorescent and transmission electron microscopy. We found paired and inconspicuous ovaries only in S. lacustris. These ovaries were made up of four to five syncytial cysts that are composed of oogonia and germ cells, which are synchronously entering meiotic prophase I. The cysts were enveloped by thin somatic cells. No growing oocytes were observed within the ovaries. However, as many as five freely floating germ-line cysts, each clustering about 30 germ cells surrounded by flat somatic cells, were observed within the ovisacs in all three of the species studied. The germ-line cysts that were found in all of the naidines studied had an architecture that is typical for clitellate annelids, i.e. each germ cell was connected to a common and anuclear cytoplasmic mass, the cytophore, via one intercellular bridge. Within these cysts, two morphologically different categories of germ cells arose. One cell usually continued meiosis, gathered nutrients and became the oocyte, whereas the rest of cells did not continue meiosis and did not gather a yolk - these cells appear to supply the oocyte with cytoplasm and cell organelles and are regarded as nurse cells. Generally, as in other microdriles, the species studied produced large, yolky oocytes. The details of oogenesis and oocyte organization are similar to other oligochaetous clitellates that have been studied. Interestingly, peculiar organelles, which are called accessory nuclei, have been found within the perinuclear cytoplasm of Ch. diaphanus vitellogenic oocytes. However, their molecular composition, functions and fate are unknown. The results obtained unequivocally show that in the naidines studied, the majority of oogenesis takes place outside the ovary, i.e. most of oogenesis is extraovarian. For comparative purposes, we propose the term "an ovary of the Stylaria type" to describe the type of extraovarian oogenesis in which polarized germ-line cysts develop freely within the ovisac cavity.