Background:To date, few glycosaminoglycan (GAG) endosulfatases have been identified. Results: A novel chondroitin sulfate/dermatan sulfate (CS/DS) endosulfatase was identified for the first time from a marine bacterium. Conclusion: The endosulfatase has low homology to the conventional GAG sulfatases and can specifically remove 4-O-sulfate from CS/DS chains. Significance: The endosulfatase will be a useful tool for CS/DS-related research and applications.

Graphical Abstract Highlights d DS neurons in a non-dorsal visual area (V2) were studied with map-guided recordings d V2 DS neurons exhibit features distinct from the DS neurons in the dorsal area MT d Clusters of V2 DS neurons form functional architectures sensitive to motion contrast d Response properties of V2 DS neurons are suitable for figureground segregation SUMMARY In the primate visual system, direction-selective (DS) neurons are critical for visual motion perception. While DS neurons in the dorsal visual pathway have been well characterized, the response properties of DS neurons in other major visual areas are largely unexplored. Recent optical imaging studies in monkey visual cortex area 2 (V2) revealed clusters of DS neurons. This imaging method facilitates targeted recordings from these neurons. Using optical imaging and single-cell recording, we characterized detailed response properties of DS neurons in macaque V2. Compared with DS neurons in the dorsal areas (e.g., middle temporal area [MT]), V2 DS neurons have a smaller receptive field and a stronger antagonistic surround. They do not code speed or plaid motion but are sensitive to motion contrast. Our results suggest that V2 DS neurons play an important role in figure-ground segregation. The clusters of V2 DS neurons are likely specialized functional systems for detecting motion contrast.

Neurons in primate V4 exhibit various types of selectivity for contour shapes, including curves, angles, and simple shapes. How are these neurons organized in V4 remains unclear. Using intrinsic signal optical imaging and two-photon calcium imaging, we observed submillimeter functional domains in V4 that contained neurons preferring curved contours over rectilinear ones. These curvature domains had similar sizes and response amplitudes as orientation domains but tended to separate from these regions. Within the curvature domains, neurons that preferred circles or curve orientations clustered further into finer scale subdomains. Nevertheless, individual neurons also had a wide range of contour selectivity, and neighboring neurons exhibited a substantial diversity in shape tuning besides their common shape preferences. In strong contrast to V4, V1 and V2 did not have such contour-shape-related domains. These findings highlight the importance and complexity of curvature processing in visual object recognition and the key functional role of V4 in this process.

Significance Orientation selectivity is one of the most important functional features of visual neurons. In the primate visual cortex, whether all orientations are represented equally is still unclear. Previous electrophysiological recordings led to controversial findings. By analyzing a large set of optical imaging data, we found anisotropic representations of orientation in macaque visual areas and that different areas had different types of anisotropies. These findings not only shed light on the long-standing question regarding a basic property of the primate visual cortex, but also on the strategy the visual system takes to represent and analyze the visual world.