Drosophila Lysophospholipase Gene swiss cheese Is Required for Survival and Reproduction

Drosophila melanogaster is one of the most famous insects in biological research. It is widely used to analyse functions of different genes. The phosphatidylcholine lysophospholipase gene swiss cheese was initially shown to be important in the fruit fly nervous system. However, the role of this gene in non-nervous cell types has not been elucidated yet, and the evolutional explanation for the conservation of its function remains elusive. In this study, we analyse expression pattern and some aspects of the role of the swiss cheese gene in the fitness of Drosophila melanogaster. We describe the spatiotemporal expression of swiss cheese throughout the fly development and analyse the survival and productivity of swiss cheese mutants. We found swiss cheese to be expressed in salivary glands, midgut, Malpighian tubes, adipocytes, and male reproductive system. Dysfunction of swiss cheese results in severe pupae and imago lethality and decline of fertility, which is impressive in males. The latter is accompanied with abnormalities of male locomotor activity and courtship behaviour, accumulation of lipid droplets in testis cyst cells and decrease in spermatozoa motility. These results suggest that normal swiss cheese is important for Drosophila melanogaster fitness due to its necessity for both specimen survival and their reproductive success.

Germ cells commit somatic stem cells to differentiation following priming by PI3K/Tor activity in the Drosophila testis

How and when potential becomes restricted in differentiating stem cell daughters is poorly understood. While it is thought that signals from the niche are actively required to prevent differentiation, another model proposes that stem cells can reversibly transit between multiple states, some of which are primed, but not committed, to differentiate. In the Drosophila testis, somatic cyst stem cells (CySCs) generate cyst cells, which encapsulate the germline to support its development. We find that CySCs are maintained independently of niche self-renewal signals if activity of the PI3K/Tor pathway is inhibited. Conversely, PI3K/Tor is not sufficient alone to drive differentiation, suggesting that it acts to license cells for differentiation. Indeed, we find that the germline is required for differentiation of CySCs in response to PI3K/Tor elevation, indicating that final commitment to differentiation involves several steps and intercellular communication. We propose that CySC daughter cells are plastic, that their fate depends on the availability of neighbouring germ cells, and that PI3K/Tor acts to induce a primed state for CySC daughters to enable coordinated differentiation with the germline.

Morphological and spectroscopic analysis of snow and glacier algae and their parasitic fungi on different glaciers of Svalbard

The results show the morphological analyses and spectroscopic studies of snow and glacier algae and their parasitic fungi in Svalbard (High Arctic). Fixed algal cells of two species, Sanguina nivaloides and Ancylonema nordenskioeldii, were imaged using light microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Fluorescence microscopy using Calcofluor white stain supported the observations of parasitic fungi on the algal cells. Images in brightfield microscopy showed chytrid-like fungi penetrating the cells of both algal species. Parasites were found to colonize the cells of A. nordenskioeldii and hypnozygotes of S. nivaloides, while no fungi infected the cyst stages of S. nivaloides. The autofluorescence analysis revealed the ability of S. nivaloides to glow when excited with different wavelengths, while A. nordenskioeldii did not fluoresce. The hypnozygotes of S. nivaloides emitted brighter fluorescence than the cysts, and the most intense luminosity was observed in the UV range. The Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) spectroscopic analysis showed differences in the chemical composition between samples collected from three different sites. Samples dominated by cyst cells were characterized by the presence of an abundant polysaccharide envelope.

Techno-economic analysis of a new downstream process for the production of astaxanthin from the microalgae Haematococcus pluvialis

The biotechnological production of the carotenoid astaxanthin is done with the microalgae Haematococcus pluvialis (H. pluvialis). Under nutrient deficiency and light stress, H. pluvialis accumulates astaxanthin intracellularly and forms a resistant cyst cell wall that impedes direct astaxanthin extraction. Therefore, a complex downstream process is required, including centrifugation, mechanical cell wall disruption, drying, and supercritical extraction of astaxanthin with CO2. In this work, an alternative downstream process based on the direct extraction of astaxanthin from the algal broth into ethyl acetate using a centrifugal partition extractor (CPE) was developed. A mechanical cell wall disruption or germination of the cysts was carried out to make astaxanthin accessible to the solvent. Zoospores containing astaxanthin are released when growth conditions are applied to cyst cells, from which astaxanthin can directly be extracted into ethyl acetate. Energy-intensive unit operations such as spray-drying and extraction with supercritical CO2 can be replaced by directly extracting astaxanthin into ethyl acetate. Extraction yields of 85% were reached, and 3.5 g of oleoresin could be extracted from 7.85 g homogenised H. pluvialis biomass using a CPE unit with 244 mL column volume. A techno-economic analysis was done for a hypothetical H. pluvialis production facility with an annual biomass output of 8910 kg. Four downstream scenarios were examined, comparing the novel process of astaxanthin extraction from homogenised cyst cells and germinated zoospores via CPE extraction with the conventional industrial process using in-house or supercritical CO2 extraction via an external service provider. After 10 years of operation, the highest net present value (NPV) was determined for the CPE extraction from germinated zoospores.

Examination of Photo-, Mixo-, and Heterotrophic Cultivation Conditions on Haematococcus pluvialis Cyst Cell Germination

The microalgae Haematococcus pluvialis is used for the biotechnological production of astaxanthin. The red carotenoid accumulates in the cytoplasm under unfavorable conditions. Astaxanthin synthesis is associated with the transformation of motile vegetative cells into non-motile cyst cells. In the industrial process, after harvesting, the cyst cells are mechanically disrupted, dried, and finally, astaxanthin is extracted with supercritical CO2. The germination of the cyst cells represents an interesting alternative, replacing the mechanical cyst cell wall disruption. When cyst cells are exposed to favorable growth conditions, germination of the cyst cells occurs and zoospores are released after a certain time. These zoospores show a much weaker cell matrix compared to cyst cells. In this study, germination under phototrophic, mixotrophic, and heterotrophic conditions was examined. Glucose was used as the carbon source for mixotrophic and heterotrophic germination. Applying heterotrophic conditions, up to 80% of the cells were in the zoospore stage 49 h after the start of germination, and extraction yields of up to 50% were achieved using the solvent ethyl acetate for the extraction of astaxanthin from the algal broth containing zoospores. An extraction yield of up to 64% could be achieved by doubling the nitrate concentration and combining mixotrophic and heterotrophic cultivation.

Stem cells commit to differentiation following multiple induction events in the Drosophila testis.

How and when potential becomes restricted in differentiating stem cell daughters is poorly understood. While it is thought that signals from the niche are actively required to prevent differentiation, another model proposes that stem cells can reversibly transit between multiple states, some of which are primed, but not committed, to differentiate. In the Drosophila testis, somatic cyst stem cells (CySCs) generate cyst cells, which encapsulate the germline to support its development. We find that CySCs are maintained independently of niche self-renewal signals if activity of the PI3K/Tor pathway is inhibited. Conversely, PI3K/Tor is not sufficient alone to drive differentiation, suggesting that it acts to license cells for differentiation. Indeed, we find that the germline is required for differentiation of CySCs in response to PI3K/Tor elevation, indicating that final commitment to differentiation involves several steps and intercellular communication. We propose that CySC daughter cells are plastic, that their fate depends on the availability of neighbouring germ cells, and that PI3K/Tor acts to induce a primed state for CySC daughters to enable coordinated differentiation with the germline.

Symmetry breaking in the female germline cyst

In mammals and flies, only a limited number of cells in a multicellular female germline cyst become oocytes, but how the oocyte is selected is unknown. Here we show that the microtubule minus end-stabilizing protein, Patronin/CAMSAP marks the future Drosophila oocyte and is required for oocyte specification. The spectraplakin, Shot, recruits Patronin to the fusome, a branched structure extending into all cyst cells. Patronin stabilizes more microtubules in the cell with most fusome and this weak asymmetry is amplified by Dynein-dependent transport of Patronin-stabilized microtubules. This forms a polarized microtubule network, along which Dynein transports oocyte determinants into the presumptive oocyte. Thus, Patronin amplifies a weak fusome anisotropy to break cyst symmetry. These findings reveal a molecular mechanism of oocyte selection in the germline cyst.

Long noncoding RNA regulation of spermatogenesis via the spectrin cytoskeleton inDrosophila

The spectrin cytoskeleton has been shown to be critical in diverse processes such as axon development and degeneration, myoblast fusion, and spermatogenesis. Spectrin can be modulated in a tissue specific manner through junctional protein complexes, however, it has not been shown that long noncoding RNAs (lncRNAs) interact with and modulate spectrin. Here, we provide evidence of a lncRNA CR45362 that interacts with α-Spectrin, is required for spermatid nuclear bundling during Drosophila spermatogenesis. We observed that CR45362 showed high expression in the cyst cells at the basal testis, and CRISPR-mediated knockout of CR45362 led to sterile male, unbundled spermatid nuclei, and disrupted actin cones. Through chromatin isolation by RNA precipitation—mass spectrometry (ChIRP-MS), we identified actin-spectrin cytoskeletal components physically interact with the lncRNA CR45362. Genetic screening on identified cytoskeletal factors revealed that cyst cell-specific knockdown of α-Spectrin phenocopied CR45362 mutants and resulted in spermatid nuclear bundle defects. Consistently, CR45362 knockout disrupted the co-localization of α-Spectrin and spermatid nuclear bundles in the head cyst cells at the basal testis. Thus, we uncovered a novel lncRNA CR45362 that interacts with α-Spectrin to stabilize spermatid nuclear bundles during spermatid maturation.

Skin Cyst: A Pathological Dead-End With a New Twist of Morphogenetic Potentials in Organoid Cultures

A cyst is a closed sac-like structure in which cyst walls wrap certain contents typically including air, fluid, lipid, mucous, or keratin. Cyst cells can retain multipotency to regenerate complex tissue architectures, or to differentiate. Cysts can form in and outside the skin due to genetic problems, errors in embryonic development, cellular defects, chronic inflammation, infections, blockages of ducts, parasites, and injuries. Multiple types of skin cysts have been identified with different cellular origins, with a common structure including the outside cyst wall engulfs differentiated suprabasal layers and keratins. The skin cyst is usually used as a sign in pathological diagnosis. Large or surfaced skin cysts affect patients’ appearance and may cause the dysfunction or accompanying diseases of adjacent tissues. Skin cysts form as a result of the degradation of skin epithelium and appendages, retaining certain characteristics of multipotency. Surprisingly, recent organoid cultures show the formation of cyst configuration as a transient state toward more morphogenetic possibility. These results suggest, if we can learn more about the molecular circuits controlling upstream and downstream cellular events in cyst formation, we may be able to engineer stem cell cultures toward the phenotypes we wish to achieve. For pathological conditions in patients, we speculate it may also be possible to guide the cyst to differentiate or de-differentiate to generate structures more akin to normal architecture and compatible with skin homeostasis.