Common principles of early mammalian embryo self-organisation

ABSTRACTPre-implantation mammalian development unites extreme plasticity with a robust outcome: the formation of a blastocyst, an organised multi-layered structure ready for implantation. The process of blastocyst formation is one of the best-known examples of self-organisation. The first three cell lineages in mammalian development specify and arrange themselves during the morphogenic process based on cell-cell interactions. Despite decades of research, the unifying principles driving early mammalian development are still not fully defined. Here, we discuss the role of physical forces, and molecular and cellular mechanisms, in driving self-organisation and lineage formation that are shared between eutherian mammals.

Game of Tissues: How the Epidermis Thrones C. elegans Shape

The versatility of epithelial cell structure is universally exploited by organisms in multiple contexts. Epithelial cells can establish diverse polarized axes within their tridimensional structure which enables them to flexibly communicate with their neighbors in a 360° range. Hence, these cells are central to multicellularity, and participate in diverse biological processes such as organismal development, growth or immune response and their misfunction ultimately impacts disease. During the development of an organism, the first task epidermal cells must complete is the formation of a continuous sheet, which initiates its own morphogenic process. In this review, we will focus on the C. elegans embryonic epithelial morphogenesis. We will describe how its formation, maturation, and spatial arrangements set the final shape of the nematode C. elegans. Special importance will be given to the tissue-tissue interactions, regulatory tissue-tissue feedback mechanisms and the players orchestrating the process.

Sweet cherry collection composition and breeding value of Melitopol experimental station of horticulture

Aim. To evaluate the composition and breeding potential of a gene poolcollection of sweet cherry varieties of M.F. SydorenkoMelitopolResearch Station of Fruit Growing of the Institute of Horticulture, NAAS of Ukraine. Result and Discussion.The results of studying the morphological, economic and biological features of sweet cherry (Cerasusavium L. Moench) varieties from the gene pool collection of MelitopolExperimental Station of Horticulturenamed after M.F. Sidorenko of the Institute of Horticulture of NAAS are presented. The history of the collection creation and the genealogy of modern Ukrainian varieties were analyzed. We found that they were the 1st and 2nd generations of traditional Western European varieties. Major sweet cherry varieties that had been most often used in developing modern Ukrainian assortment, were identified. Analysis of the collection showed that 111 accessions of 129 were varieties bred in Melitopol, 40 of which are officially registered.The other accessions are elite forms, which failed the state variety trials or are being tested according to the competitive design. Among the latter, promising forms (candidates for varieties and pre-breeding forms) were distinguished, as they are sources of valuable economic traits. It was determined that the morphogenic process had contributed to the diversity in fruit quality features, which enabled building up a trait collection of sweet cherries for 20 traits with 82 levels of their expression. However, morphogenesis almost did not affect the growth power, fructification nature, generative organs, fructification time and resistance to diseases, therefore there are no significant differences in these features between the collection accessions bred at Melitopol Experimental Station of Horticulture named after M.F. Sidorenko of the Institute of Horticulture of NAAS. Most of the varieties grown on Magalebian cherry plantlet have extensive crowns, bear fruit on "May bouquets" and, after one-year growth, are winter hardy, tolerant to drought, moderately and highly resistant to spur blight and leaf spot as well as self-infertile. On this parent stock, most of the varieties come into fruition after 5-6 years and quickly increase their yields. It was established that enrichment of the gene pool collection with valuable introduced accessions and their wide involvement in hybridization were currently the key objectives aimed at expansion of morphogenesis limits to obtain competitive varieties with high adaptability, productivity and marketability. Conclusions. Modern Ukrainian varieties are the 1st and 2nd generations of traditional Western European varieties. German variety Drogansgelbeknorpelkirsche (DroganaZhyoltaya) with its clone Napoleon Belaya and Russian-Ukrainian variety Valeriy Chkalov were the most actively used in their development. 86% of the gene pool collection of MelitopolExperimental Stationof Horticulture named after M.F. Sidorenkoof the Institute of Horticulture of NAAS are varieties bred in Melitopol differing mainly in ripening time and fruit quality. The collection contains released varieties, a number of sources of valuable traits and, as a tool for the effective implementation of modern breeding programs, requires enrichment with varieties of other eco-geographical groups.

Characterization of convergent thickening, a major convergence force producing morphogenic movement in amphibians

SUMMARYWe characterize the morphogenic process of convergent thickening (CT), which occurs in the involuting marginal zone (IMZ) during gastrulation of Xenopus, the African clawed frog. CT was described previously as the tendency of explants of the ventral IMZ of Xenopus to converge their circumblastoporal dimension and thicken their radial dimension (Keller and Danilchik 1988). Here we show that CT occurs from the onset of gastrulation, initially throughout the pre-involution IMZ. We suggest that CT is driven by an increase in the interfacial tension between the deep IMZ and its epithelium, resulting in cells of the deep IMZ tending to minimize their surface area. In explants, this results in a progressive shortening (convergence) of the IMZ along its longer mediolateral axis and thickening in the orthogonal planes, and can generate tensile force (Shook et al. 2018). In vivo, convergence of the annular IMZ generates circumferential tension, closing the blastopore. These results provide the first clear example of a tensile morphogenic force from a Holtfreterian/Steinbergian change in tissue affinity.

The Ras-like protein R-Ras2/TC21 is important for proper mammary gland development

R-Ras2/TC21 is a GTPase with high sequence and signaling similarity with Ras subfamily members. Although it has been extensively studied using overexpression studies in cell lines, its physiological role remains poorly characterized. Here we used RRas2-knockout mice expressing β-galactosidase under the regulation of the endogenous RRas2 promoter to investigate the function of this GTPase in vivo. Despite its expression in tissues critical for organismal viability, RRas2−/− mice show no major alterations in viability, growth rates, cardiovascular parameters, or fertility. By contrast, they display a marked and specific defect in the development of the mammary gland during puberty. In the absence of R-Ras2/TC21, this gland forms reduced numbers of terminal end buds (TEBs) and ductal branches, leading to a temporal delay in the extension and arborization of the gland tree in mammary fat pads. This phenotype is linked to cell-autonomous proliferative defects of epithelial cells present in TEBs. These cells also show reduced Erk activation but wild type–like levels of phosphorylated Akt. Using compound RRas2-, HRas-, and NRas-knockout mice, we demonstrate that these GTPases act in a nonsynergistic and nonadditive manner during this morphogenic process.

In vitro organogenesis of zucchini squash cv. Caserta

A protocol for the in vitro culture of Cucurbita pepo cv. Caserta was studied, using a cotyledon segment with an attached hypocotyl fragment as an explant. First, to determine the optimal seedling age, explants were collected from 4 to 6-day-old in vitro germinated seedlings and cultured in MS basal medium supplemented with benzylaminopurine (BAP, 4.5 µM), under a 16-h photoperiod at 27ºC. Based on the results obtained, the explants collected from the 4-day-old seedlings were then cultured in MS basal medium supplemented with different concentrations of BAP (0, 1.1, 2.2, 3.3, 4.5, or 5.5 µM) and incubated under a 16-h photoperiod at 27ºC. In vitro organogenesis was most efficient with explants collected from 4-day-old seedlings cultured in medium supplemented with 4.5 µM of BAP. After 4 weeks of incubation the development of adventitious buds at the cotyledon/hypocotyl junction could be observed. These buds were transferred to elongation and rooting medium and the developed plants were acclimatized to greenhouse conditions. The morphogenic process was characterized using light and scanning electron microscopy analyses to confirm the organogenesis. The results showed that this alternate explant is efficient for in vitro culture of zucchini squash cv. Caserta. The protocol will be further examined for future use in genetic transformation experiments in this species.

Organogenic Nodule Formation in Hop: A Tool to Study Morphogenesis in Plants with Biotechnological and Medicinal Applications

The usage ofHumulus lupulusfor brewing increased the demand for high-quality plant material. Simultaneously, hop has been used in traditional medicine and recently recognized with anticancer and anti-infective properties. Tissue culture techniques have been reported for a wide range of species, and open the prospect for propagation of disease-free, genetically uniform and massive amounts of plantsin vitro.Moreover, the development of large-scale culture methods using bioreactors enables the industrial production of secondary metabolites. Reliable and efficient tissue culture protocol for shoot regeneration through organogenic nodule formation was established for hop. The present review describes the histological, and biochemical changes occurring during this morphogenic process, together with an analysis of transcriptional and metabolic profiles. We also discuss the existence of common molecular factors among three different morphogenic processes: organogenic nodules and somatic embryogenesis, which strictly speaking depend exclusively on intrinsic developmental reprogramming, and legume nitrogen-fixing root nodules, which arises in response to symbiosis. The review of the key factors that participate in hop nodule organogenesis and the comparison with other morphogenic processes may have merit as a study presenting recent advances in complex molecular networks occurring during morphogenesis and together, these provide a rich framework for biotechnology applications.

Identification of chromosomal deficiency by flow cytometry and cytogenetics in mutant tomato (Solanum lycopersicum, Solanaceae) plants

Structural chromosomal aberrations can occur spontaneously in plant karyotypes as a result of both intrinsic and extrinsic factors. These aberrations may affect sporophyte fitness because fundamental genes involved with distinct morphogenic process may be lost. Inadequate development of flowers and anomalous fruits without seeds has been observed in plants of Solanum lycopersicum L. (Solanaceae) ‘BHG 160’ of the tomato germplasm bank (Universidade Federal de Viçosa, Brazil). The nuclear DNA content, quantified by flow cytometry, showed that mutant ‘BHG 160’ possesses 0.09 pg (4.59%) less nuclear DNA content than does the wild-type ‘BGH 160’. Improved cytogenetical preparations evidenced that this difference was due to a spontaneous terminal deficiency in the short arm of the mutant ‘BGH 160’ Chromosome 1. These results suggest that the genes encoded in the short arm of Chromosome 1 may be involved in the development of flowers and fruits in the tomato.