Maternal vgll4a promotes blastoderm cohesion enabling yap1-mediated mechano-transduction during zebrafish epiboly

Cellular cohesion provides tissue tension, which is then sensed by the cytoskeleton and decoded by the activity of mechano-transducers, such as the transcriptional cofactor Yap1, thereby enabling morphogenetic responses in multi-cellular organisms. How cell cohesion is regulated is nevertheless unclear. Here we show that, zebrafish epiboly progression, a prototypic morphogenetic event that depends on Yap activity, requires the maternal contribution of the proposed yap1 competitor vgll4a. In embryos lacking maternal/zygotic vgll4a (MZvgll4a), spreading epithelial cells are ruffled, blastopore closure is delayed and the expression of the yap1-mediator arhgap18 is decreased, impairing the actomyosin ring at the syncytial layer. Furthermore, rather than competing with Yap1, vgll4a coordinate the levels of the E-Cadherin/β-catenin adhesion complex components at the blastomere plasma membrane and hence their actin cortex distribution. Taking these results together, we propose that maternal vgll4a may act at epiboly initiation to coordinate blastomere adhesion/cohesion, which is a fundamental piece of the self-sustained bio-mechanical regulatory loop underlying morphogenetic rearrangements during gastrulation.

In vitro culture of zygotic embryos and seeds of Caesalpinia ferrea Martius

ABSTRACT The aim of this study was to evaluate the in vitro germination of zygotic embryos and seeds of Caesalpinia ferrea Martius and the morphogenetic responses of the explants to different concentrations of growth regulators. Seeds and zygotic embryos were inoculated in MS culture medium and kept in a growth room at a temperature of 25 ± 2 ºC for 16 hours of photoperiod for 30 days. The seeds had a higher in vitro germination rate than the explants from zygotic embryos. However, zygotic embryos in MS medium supplemented with 0.9 mg L-1 BAP had the highest percentage of regeneration (50%), number of shoots (3.25), buds (2.85) and leaves (3.15), multiplication rate (27.75), and length of shoots (1.96 cm). The in vitro culture of zygotic embryos and seeds made possible the multiplication of a higher number of healthy seedlings. Thus, it can be used as an alternative technique for the propagation of this species.

Morphogenetic Responses in Anthurium Andreanum (Hort) Cultivars

In this study, in vitro morphogenetic responses have been studied in popular Anthurium andreanum cultivars Tropical Red, Acropolis, Sun Glow, Esmeralda, Chaco, Pistachio, Neveda and Safari employing explants of various types and growth stages, through indirect organogenesis. Creamy and compact callus initiated in cut ends along the veins of Leaf lamina with mid rib (LLMR) and petiole with leaf (PL) explants of various cultivars in 30-120 days of inoculation, it was sub cultured and incubated in dark for proliferation. Leaf tip, candle and petioles did not show any kind of response, turned brown and died later. Explants from young pale green leaves with smooth structure showed early response in all cultivars. Callus proliferation rate was 3.0-5.0 times 30-35 days of incubation in various cultivars. Shoot bud initiation and elongation observed after 45-60 days incubation in dark. Number of shoot buds per explants ranged from 30-60 per explants and 8-10 buds attained 1.5-2.5 cm in height. Then, shoots were separated, inoculated in shoot elongation medium and incubated in light. Remaining callus was sub cultured in callus multiplication medium and incubated in dark. Callus and shoot multiplication ratio was 1-2 and 2.5-4.2 times respectively. Shoots attained 4-5.3 cm in height in 45-55 days, rooted and ready for hardening in 65-80 days. Rooted plantlets were hardened in 1:1 ratio soil rite and coco-peat mix in portrays, transferred to beds prepared with coconut coir-pith, 95% plants survived, appeared normal and flowered. In this paper, materials, methodology, results will be discussed.

Identification of tiller age categories based on morphogenetic responses of continuously stocked marandu palisade grass fertilised with nitrogen

Nitrogen fertilization augments tiller appearance and death, modifying the age profile of tiller population. Tillers from different age categories present distinct responses to environmental factors and management practices characterized by variation in their morphogenetic responses, which interfere in the dynamics of the herbage accumulation process. In that context, rates of leaf appearance and elongation and leaf lifespan were used as indicators to identify tiller age categories of continuously stocked marandu palisade grass managed at 30cm and subjected to nitrogen fertilization regimes using cluster analysis. Analysis was based on the average distance method using combined means of the response-variables studied, and the results used to build a dendogram to illustrate the arrangement of the resulting clusters. Three clusters were identified corresponding to the tiller age categories denominated young (tillers with age between 0 and 60 days), mature (between 60 and 120 days) and old (over 120 days). Discrimination of the tiller age categories according to nitrogen fertilization regime followed the same pattern of clustering. The fact demonstrates consistency and indicates the three age categories as reference for detailed studies regarding the ecophysiology of marandu palisade grass.