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Coral polyps are basic clonal biological units of reef corals. However, in vitro experimental model for long-term physiological and ecological studies has not been well developed due to the difficulty of effectively acquiring and culturing single polyps. This study developed an experimental platform based on microfluidics for culturing single coral polyps and tracing its growth state over time in the long run. The corresponding computational modeling was conducted to predict the metabolic processes under the static and dynamic conditions by coupling the mass transfer and reaction with Navier-Stokes equations. Design and fabrication of the microfluidic chip was the key to provide a constant laminar flow environment that enabled the controlled high oxygen and bicarbonate transfer for the cultivation of the single coral polyps. The single coral polyps were induced to bail out of the coral reef upon the chemical stress and cultured for more than fifteen days in the microfluidic chip. It was found that the single coral polyps in the microfluidic chip can maintain their normal metabolic process over the cultivation period, suggesting that our microfluidic platform can serve as a suitable tool to study the coral polyps by providing a controllable and suitable biological microenvironment.

Scleractinian corals are foundational to coral reefs, vital marine ecosystems under threat from climate change. Montipora, a widely distributed reef‐building genus, contributes through continuous corallum mineralization, yet polyp budding and skeleton formation processes remain elusive. This study elucidates temporal and spatial dynamics of skeletal formation and polyp budding in Montipora capricornis using high‐resolution micro‐computed tomography (micro‐CT). We demonstrate that skeleton–canal network formation precedes polyp budding at colony margins, identifying a “transit area” (volumes ~1 mm3, skeleton‐to‐void ratio 20%–35%) within tubular canals as a pathway for polyp migration to new calices. This feature serves as a morphological budding marker, enabling visualization of polyp trajectories and growth axes. The polyp‐canal system undergoes dynamic changes, including concurrent skeleton formation and dissolution. These insights establish a structural framework for biomineralization regulation and colony expansion, contributing to the development of coral growth models, and informing environmental impacts on reef‐building in M. capricornis. Using high‐resolution micro‐computed tomography, this study demonstrates that in Montipora capricornis, skeleton–canal network formation precedes polyp budding at colony margins, with a “transit area” (volumes ~1 mm3, skeleton‐to‐void ratio 20%–35%) in tubular canals serving as a pathway for polyp migration to new calices. This feature acts as a morphological budding marker, enabling visualization of polyp trajectories, growth axes, and dynamic changes involving concurrent skeleton formation and dissolution. These findings provide a structural framework for biomineralization regulation, colony expansion, and modeling environmental impacts on reef‐building corals.

The slow-evolving invertebrate amphioxus has an irreplaceable role in advancing our understanding of the vertebrate origin and innovations. Here we resolve the nearly complete chromosomal genomes of three amphioxus species, one of which best recapitulates the 17 chordate ancestor linkage groups. We reconstruct the fusions, retention, or rearrangements between descendants of whole-genome duplications, which gave rise to the extant microchromosomes likely existed in the vertebrate ancestor. Similar to vertebrates, the amphioxus genome gradually establishes its three-dimensional chromatin architecture at the onset of zygotic activation and forms two topologically associated domains at the Hox gene cluster. We find that all three amphioxus species have ZW sex chromosomes with little sequence differentiation, and their putative sex-determining regions are nonhomologous to each other. Our results illuminate the unappreciated interspecific diversity and developmental dynamics of amphioxus genomes and provide high-quality references for understanding the mechanisms of chordate functional genome evolution.

A coral reef is an underwater ecosystem characterized by stony corals and reef rubble. Reef rubble is formed by the aragonite and calcite skeletons of dead scleractinian corals and other calcareous organisms. In the ocean, reef rubble contributes to numerous benefits to the marine environment, including the formation of coral reefs, the provision of habitats for marine organisms, and the ability to withstand the impact of waves; reef rubble also plays an important role in saltwater aquaria. However, the transformation process from coral skeleton to reef rubble is poorly understood. This study reconstructed mineralised samples at three stages of the formation process and observed this transformation visually using high-resolution micro-computer tomography. In the binding and cementation processes during reef rubble formation, the content of high-Mg calcite increased in the calcareous samples, the gaps among adjacent sediments disappeared, and the skeleton-void ratio of coral skeletons decreased from 40–50% to 12%. The compressive strength of coral skeletons increased from 4–7 MPa to more than 40 MPa during reef rubble formation, and decreased to 1–2.5 MPa after bioerosion by barnacles. This work provides structural information for diagenetic changes, insight into barnacle erosion in coral skeletons, and extends our understanding of mechanical strength changes during reef rubble formation, which contributes to understand the rigidity of coral reefs.

In Acropora, the complex canals in a coral colony connect all polyps to a holistic network, enabling them to collaborate in performing biological processes. There are various types of canals, including calice, axial canals, and other internal canals, with structures that are dynamically altered during different coral growth states due to internal calcium transport. In this study, we investigated the morphological changes in the corallite of six Acropora muricata samples by high resolution micro-computed tomography, observing the patterns of calcium carbonate deposition within axial corallite during processes of new branch formation and truncated tip repair. We visualized the formation of a new branch from a calice and the calcium carbonate deposition in the axial canal. Furthermore, the diameter and volume changes of the axial canal in truncated branches during rebuilding processes were calculated, revealing that the volume ratio of calcareous deposits in the axial canal exhibit significant increases within the first three weeks, returning to levels in the initial state in the following week. This work demonstrates that calcium carbonate can be stored temporarily and then remobilized as needed for rapid growth. The results of this study shed light on the control of calcium carbonate deposition and growth of the axial corallite in Acropora.

The digestive methods employed by amphioxus ( Branchiostoma )—both intracellular phagocytic digestion and extracellular digestion—have been discussed since 1937. Recent studies also show that epithelial cells lining the Branchiostoma digestive tract can express many immune genes. Here, in Branchiostoma belcheri , using a special tissue fixation method, we show that some epithelial cells, especially those lining the large diverticulum protruding from the gut tube, phagocytize food particles directly, and Branchiostoma can rely on this kind of phagocytic intracellular digestion to obtain energy throughout all stages of its life. Gene expression profiles suggest that diverticulum epithelial cells have functional features of both digestive cells and phagocytes. In starved Branchiostoma , these cells accumulate endogenous digestive and hydrolytic enzymes, whereas, when sated, they express many kinds of immune genes in response to stimulation by phagocytized food particles. We also found that the distal hindgut epithelium can phagocytize food particles, but not as many. These results illustrate phagocytic intercellular digestion in Branchiostoma , explain why Branchiostoma digestive tract epithelial cells express typical immune genes and suggest that the main physiological function of the Branchiostoma diverticulum is different from that of the vertebrate liver.

To overcome the shortcoming of conventional transarterial chemoembolization (cTACE) like high systemic release, a novel droplet-based flow-focusing microfluidic device was fabricated and the biocompatible poly(lactic-co-glycolic acid) (PLGA) magnetic drug-eluting beads transarterial chemoembolization (TACE) microspheres with tunable size and shell thickness were prepared via this device. Paclitaxel, as a model active, was loaded through O/O/W emulsion method with high efficiency. The size and the shell thickness vary when adjusting the flow velocity and/or solution concentration, which caters for different clinical requirements to have different drug loading and release behavior. Under the designed experimental conditions, the average diameter of the microspheres is 60 ± 2 μm and the drug loading efficiency has reached 6%. The drug release behavior of the microspheres shows the combination of delayed release and smoothly sustained release profiles and the release kinetics differ within different shell thickness. The microspheres also own the potential of magnetic resonance imaging (MRI) visuality because of the loaded magnetic nanoparticles. The microsphere preparation method and device we proposed are simple, feasible, and effective, which have a good application prospect.

Colonies are the basic geometric building blocks of coral reefs. However, the forming regulations of both colonies and reefs are still not understood adequately. Therefore, in this study, we reconstructed 25 samples using high‐resolution micro‐computed tomography to investigate coral growth patterns and parameters. Our skeleton and canal reconstructions revealed the characteristics of different coral species, and we further visualized the growth axes and growth rings to understand the coral growth directions. We drew a skeleton grayscale map and calculated the coral skeleton void ratios to ascertain the skeletal diversity, devising a method to quantify coral growth. On the basis of the three‐dimensional (3D) reconstructions and growth parameters, we investigated the growth strategies of different coral species. This research increases the breadth of knowledge on how reef‐building corals grow their colonies, providing information on reef‐forming regulations. The data in this paper contain a large amount of coral growth information, which can be used in further research on reef‐forming patterns under different conditions. The method used in this study can also be applied to animals with porous skeletons. In this study, we use high‐resolution micro‐computed tomography to reconstruct 25 representative coral samples, indicating that there is a polyp network supported by the canal system within coral skeletons, which maintains coral growth. We visualized coral growth regulations to highlight the similarities and differences among different genera, and investigated different growth strategies by their skeleton‐forming patterns. Growth parameters of coral skeletons were obtained being on the gray scale of 3D reconstructions to reveal the mineralizing diversity among species.

Coral reef ecosystems face escalating threats from anthropogenic global climate challenges, leading to frequent bleaching events. A key issue in coral transplantation is the inability of fragments to rapidly grow to sizes that can resist environmental pressures. The observation of accelerated growth during the early stages of coral regeneration provides new insights for addressing this challenge. To investigate the underlying molecular mechanisms, we study the fast-growing stony coral Acropora muricata . Using single-cell RNA sequencing, bulk RNA sequencing, and high-resolution micro-computed tomography, we identify a critical regeneration phase around 2–4 weeks post-injury. Single-cell transcriptome analysis reveals 11 function-specific cell clusters. Pseudotime analysis indicates epidermal cell differentiation into calicoblasts. Bulk RNA-seq results highlight a temporal limitation in coral’s rapid regeneration. Through integrated multi-omics analysis, this study emphasizes the importance of a comprehensive understanding of coral regeneration, providing insights beyond fundamental knowledge and offering potential protective strategies to promote coral growth. scRNA-seq reveals cell differentiation and bulk RNA-seq uncovers temporal gene regulation during skeletal regeneration in Acropora muricata, jointly highlighting a critical regenerative phase and offering insights for enhancing coral resilience.

The polyp-canal system is vital for the growth, budding, and mineralization of scleractinian corals. Seriatopora hystrix displays a unique structural trait, with its calices and canals making up only about 15% of the colony volume, lower than the 40-50% observed in other widely distributed genera such as Acropora , Montipora , Pocillopora , or Stylophora . We used micro-computed tomography to visualize the polyp-canal system of S. hystrix , quantify its growth parameters, and simulate the dynamic processes of polyp budding and movement. It reveals that the polyps in S. hystrix follow the budding pattern of unilateral extension along the growth axis and radiates within the horizontal plane, which simplifies its polyp-canal system. Through the finite element analyses under average and maximum wave velocities of South China Sea, we measured the stress distribution in coral models with varying canal volume proportions. We found that the lower volume proportion of polyp-canal system in S. hystrix reduces the VonMises stress at the branching areas by approximately 40-50%, ensuring the continual construction of branchlets in high speed flow field. This study enhances our understanding of Seriatopora coral growth patterns and their adaptation to marine environments, contributing to the species selection in coral reef restoration.