Morphogenesis of the Ciliature During Sexual Process of Conjugation in the Ciliated Protist Euplotes raikovi

Morphogenesis is an important process that widely occurs in almost all the organisms, including the ciliated protists. Ciliates are a large group of single-celled eukaryotes that can reproduce asexually (e.g., binary fission) and perform sexual process (e.g., conjugation). Morphogenesis happens in both asexual reproduction and sexual process in ciliates and the reorganization during conjugation is more complex. However, studies of morphogenesis focusing on conjugation are very limited. Here we studied the morphogenetic process during conjugation in the marine species Euplotes raikovi Agamaliev, 1966. The results indicate that: (1) the ciliature in the ventral side reorganizes twice during sexual process, i.e., conjugational and postconjugational reorganization; (2) the adoral zone of membranelles (AZM) is generated de novo in a pouch beneath the cortex during both reorganizations, with the anterior part generated during the first reorganization, while the posterior part formed during the second reorganization; (3) the frontoventral-transverse (FVT) cirri anlagen are formed de novo in both processes with the fragmentation pattern of 2:2:3:3:2; (4) one left marginal cirrus is generated de novo during both reorganizations; and (5) the dorsal ciliature remains intact during the whole process, except that the two caudal cirri originate from the end of the right-most two dorsal kineties during both reorganizations. Comparisons of the morphogenetic process during conjugation demonstrate a considerably stable pattern within Euplotes while the patterns vary dramatically among different ciliate groups.

Mechanical stress initiates and sustains the morphogenesis of wavy leaf epidermal cells

Plant cell morphogenesis is governed by the mechanical properties of the cell wall and the resulting cell shape is intimately related to the respective specific function. Pavement cells covering the surface of plant leaves form wavy interlocking patterns in many plants. We use computational mechanics to simulate the morphogenetic process based on experimentally assessed cell shapes, growth dynamics, and cell wall chemistry. The simulations and experimental evidence suggest a multistep process underlying the morphogenesis of pavement cells during tissue differentiation. The mechanical shaping process relies on spatially confined, feedback-augmented stiffening of the cell wall in the periclinal walls, an effect that correlates with experimentally observed deposition patterns of cellulose and de-esterified pectin. We provide evidence for mechanical buckling of the pavement cell walls that can robustly initiate patternsde novoand may precede chemical and geometrical anisotropy.HighlightsA multistep mechano-chemical morphogenetic process underlies the wavy pattern of epidermal pavement cells.Microtubule polarization is preceded by an event that breaks mechanical isotropy in the cell wall.Mechanical models simulate the formation of wavy cell shapes, predict buckling of the cell walls and spatially confined variations in the mechanical properties of leaf epidermal cells.Stress/strain stiffening following the buckling of the cell walls constitutes a crucial element in a positive feedback loop forming interlocking pavement cells.Polarization of cortical microtubules, cellulose microfibrils, and de-esterified pectin occur at the necks of wavy pavement cells, matching thein silicoprediction of cell wall stiffening.

Residents’ Perception and Assessment of Geomorphosites of the Alvão—Chaves Region

This work focuses on the paradigms of a multidimensional and interdisciplinary evaluation of geomorphological heritage and its valorisation within a geosystemic reading of relations between a geomorphological and cultural landscape. This research aims to (i) select geomorphosites at different scales, which represent the regional geodiversity, according to an interdisciplinary approach; and (ii) better understand the perception of the local population concerning the different values of geomorphosites by applying a questionnaire that addresses the scientific, preservation, use, cultural, and educational dimensions. First, the authors selected the geomorphosites at a regional level by respecting the following criteria: (i) representativeness of the landform as a morphogenetic process; (ii) the witnessed periods of morpho-dynamics with potential to contribute to the reconstruction of paleoenvironmental conditions; (iii) the current morpho-dynamic nature; (iv) the importance to the shaping of the cultural landscape; and (v) the use value. Results showed that the major landforms are perceived as those with greater value by the local populations.

Radially patterned cell behaviours during tube budding from an epithelium

The budding of tubular organs from flat epithelial sheets is a vital morphogenetic process. Cell behaviours that drive such processes are only starting to be unraveled. Using live-imaging and novel morphometric methods, we show that in addition to apical constriction, radially oriented directional intercalation of cells plays a major contribution to early stages of invagination of the salivary gland tube in the Drosophila embryo. Extending analyses in 3D, we find that near the pit of invagination, isotropic apical constriction leads to strong cell-wedging. Further from the pit cells interleave circumferentially, suggesting apically driven behaviours. Supporting this, junctional myosin is enriched in, and neighbour exchanges are biased towards the circumferential orientation. In a mutant failing pit specification, neither are biased due to an inactive pit. Thus, tube budding involves radially patterned pools of apical myosin, medial as well as junctional, and radially patterned 3D-cell behaviours, with a close mechanical interplay between invagination and intercalation.

Radially-patterned cell behaviours during tube budding from an epithelium

The budding of tubular organs from flat epithelial sheets is a vital morphogenetic process. Cell behaviours that drive such processes are only starting to be unraveled. Using live imaging and novel morphometric methods we show that in addition to apical constriction, radially oriented directional intercalation of placodal cells plays a major contribution to the early stages of invagination of the salivary gland tube in the Drosophila embryo. Extending analyses in 3D, we find that near the pit of invagination, isotropic apical constriction leads to strong cell wedging, and further from the pit cells interleave circumferentially, suggesting apically driven behaviours. Supporting this, junctional myosin is enriched in, and neighbour exchanges biased towards the circumferential orientation. In a mutant failing pit specification, neither are biased due to an inactive pit. Thus, tube budding depends on a radially polarised pattern of apical myosin leading to radially oriented 3D cell behaviours, with a close mechanical interplay between invagination and intercalation.

Two consecutive microtubule-based epithelial seaming events mediate dorsal closure in the scuttle fly Megaselia abdita

Evolution of morphogenesis is generally associated with changes in genetic regulation. Here, we report evidence indicating that dorsal closure, a conserved morphogenetic process in dipterans, evolved as the consequence of rearrangements in epithelial organization rather than signaling regulation. In Drosophila melanogaster, dorsal closure consists of a two-tissue system where the contraction of extraembryonic amnioserosa and a JNK/Dpp-dependent epidermal actomyosin cable result in microtubule-dependent seaming of the epidermis. We find that dorsal closure in Megaselia abdita, a three-tissue system comprising serosa, amnion and epidermis, differs in morphogenetic rearrangements despite conservation of JNK/Dpp signaling. In addition to an actomyosin cable, M. abdita dorsal closure is driven by the rupture and contraction of the serosa and the consecutive microtubule-dependent seaming of amnion and epidermis. Our study indicates that the evolutionary transition to a reduced system of dorsal closure involves simplification of the seaming process without changing the signaling pathways of closure progression.

Geometrical Characterization of a Rototraslative Generative Tower

This chapter studies the geometric generation of the shape of a well-known building designed by the Spanish archistar Santiago Calatrava. The building is a skyscraper located in Malmö, Sweden named Turning Torso. The first step for analyzing the morphogenetic process is research on all of the available references that deal with building. This work aims to fully describe the process that has led the generation of the building itself.

Two consecutive microtubule-based epithelial seaming events mediate dorsal closure in the scuttle fly Megaselia abdita

Evolution of morphogenesis is generally associated with changes in genetic regulation. Here we report evidence indicating that dorsal closure, a conserved morphogenetic process in dipterans, evolved as the consequence of rearrangements in epithelial organization rather than signaling regulation. In Drosophila melanogaster, dorsal closure consists of a two-tissue system where the contraction of extraembryonic amnioserosa and a JNK/Dpp-dependent epidermal actomyosin cable result in microtubule-dependent seaming of the epidermis. We find that dorsal closure in Megaselia abdita, a three-tissue system comprising serosa, amnion and epidermis, differs in morphogenetic rearrangements despite conservation of JNK/Dpp signaling. In addition to an actomyosin cable, M. abdita dorsal closure is driven by the rupture and contraction of the serosa and the consecutive microtubule-dependent seaming of amnion and epidermis. Our study indicates that the evolutionary transition to a reduced system of dorsal closure involves simplification of the seaming process without changing the signaling pathways of closure progression.Impact StatementEvolutionary reduction in tissue number involves the simplification of the seaming process but not signaling during epithelial fusion.

Esterase and peroxidase isoforms during initial stages of somatic embryogenesis in Fritillaria meleagris L. leaf base

The aim of this study was to determine the enzymatic profile of esterases and peroxidases during early stages of somatic embryogenesis of Fritillaria meleagris L. Somatic embryogenesis was induced using the leaf base as explant on a medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D). Zymography showed the presence of different moieties, six isoforms of esterases and peroxidases, during morphogenesis as compared to control explants. One isoform of esterases was detected only during the process of somatic embryogenesis, and one isoform was detected in control explants. Analysis of esterases with 1-naphthyl butyrate proved that esterases, which participate in somatic embryogenesis of F. meleagris, belong to the family of aryl esterases. For the first time it was proved that five isoforms of esterases, which are involved in morphogenesis of F. meleagris, belong to the family of aryl esterases, while two isoforms are carboxyl esterases. One isoform of carboxyl esterases was visible in control explants. This is also the first description of peroxidases during the morphogenetic process, and of the difference between aryl and carboxyl esterases. More isoforms of esterases during morphogenesis as compared to control explants are probably responsible for some early physiological process during somatic embryogenesis of F. meleagris.