In situ measurements of reef squid polarization patterns using two-dimensional polarization data mapped onto three-dimensional tessellated surfaces

Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of reef squid have not been quantified in situ . To quantify polarization patterns from video polarimetric data, we developed a protocol to map two-dimensional polarization data onto squid-shaped three-dimensional tessellated surfaces. This protocol provided a robust data container used to investigate three-dimensional regions-of-interest, producing data lineouts derived from the squid's geometry. This protocol also extracted polarimeter and squid body orientations and the solar heading from polarization images. When averaged over the solar heading, the ventral midline gave a low degree of polarization (2.4 ± 5.3%), and the area between the ventral and flank midlines had higher values (9.0 ± 5.3%). These averaged data had a large discontinuity in the angle of polarization (AoP) at the mantle's ventral midline (64 ± 55°), with larger discontinuities measured on individual squid. Ray-tracing calculations demonstrated that the AoP pattern was not related to the squid's surface-normal geometry. However, the AoP followed virtual striation axes on the squid's surface oriented 24° to the squid's long axis, similar in angle (27°) to the striations of birefringent collagen fibres documented in other squid species’ skin.

Admp regulates tail bending by controlling the intercalation of the ventral epidermis through myosin phosphorylation

Chordate tailbud embryos have similar morphological features, including a bending tail. A recent study revealed that the actomyosin of the notochord changes the contractility and drive tail bending of the early Ciona tailbud embryo. Yet, the upstream regulator of tail bending remains unknown. In this study, we find that Admp regulates tail bending of Ciona mid-tailbud embryos. Anti-pSmad antibody signal was detected at the ventral midline tail epidermis. Admp knock-down embryo completely inhibited the ventral tail bending and reduced the number of the triangular-shaped cells, which has the apical accumulation of the myosin phosphorylation and inhibited specifically the cell-cell intercalation of the ventral epidermis. The degree of myosin phosphorylation of the ventral cells and tail bending were correlated. Finally, the laser cutter experiments demonstrated the myosin-phosphorylation-dependent tension of the ventral midline epidermis during tail bending. We conclude that Admp is an upstream regulator of the tail bending by controlling myosin phosphorylation and its localization of ventral epidermal cells. These data reveal a new aspect of the function of the Admp that might be evolutionarily conserved in bilaterian animals.Summary StatementAdmp is an upstream regulator of the bending of the tail in the tailbud embryo regulating tissue polarity of the ventral midline epidermis by phosphorylation of myosin.

Surgical management of congenital foetal hydrocephalus in a crossbred cow

A rare case of dystocia due to external congenital hydrocephalic foetus with ankylosis of forelimbs managed by ventral midline surgical approach in a crossbred cow is reported.

Somite morphogenesis is required for axial blood vessel formation

ABSTRACTAngioblasts that form the major axial blood vessels of the dorsal aorta and cardinal vein migrate towards the embryonic midline from distant lateral positions. Little is known about what controls the precise timing of angioblast migration and their final destination at the midline. Using zebrafish, we found that midline angioblast migration requires neighboring tissue rearrangements generated by somite morphogenesis. The somitic shape changes cause the adjacent notochord to separate from the underlying endoderm, creating a ventral midline cavity that provides a physical space for the angioblasts to migrate into. The anterior to posterior progression of midline angioblast migration is facilitated by retinoic acid induced anterior to posterior somite maturation and the subsequent progressive opening of the ventral midline cavity. Our work demonstrates a critical role for somite morphogenesis in organizing surrounding tissues to facilitate notochord positioning and angioblast migration, which is ultimately responsible for creating a functional cardiovascular system.Summary statementRetinoic acid induced somite morphogenesis generates a midline cavity that accommodates migrating angioblasts, which form the axial blood vessels.