Computational analyses decipher the primordial folding coding the 3D structure of the beetle horn

Post-embryonic tail development through molting of the freshwater shrimp Neocaridina denticulata

Neocaridina, a crustacean, exhibits distinctive tail morphogenesis during molting, making it a potential model for post-embryonic morphogenesis. After the first molting, two significant changes occur in the tail: the uropod branches are cleared and the telson undergoes convergent elongation. Cross-sectional analysis showed that uropod and telson branching begins immediately after hatching as cuticle branching. The surface structure of the developing tail suggested that telson elongation is achieved through anisotropic cuticle furrow extension during molting, linked to epithelial cell shape changes occurring post-hatching. An in vivo live imaging system with UV-LED resin revealed gradual telson contraction before molting. Additionally, a draft genome of Neocaridina denticulata was provided. This research enhances understanding of arthropod morphogenesis through molting and lays groundwork for further developmental and cytological studies in Neocaridina.

Growth regulation bringing modularity to morphogenesis of complex three-dimensional exoskeletons

Diverse three-dimensional morphologies of arthropods' outgrowths, including beetle horns, are formed through the non-uniform growth of epidermis. Prior to moulting, epidermal tissue peels off from the old cuticle and grows non-uniformly to shape protruding structures, which are often branching, curving or twisting, from the planar epidermis. This non-uniform growth is possibly regulated by the distribution of morphogens on the epidermal cell sheet. Previous studies have identified molecules and signalling pathways related to such morphogenesis; however, how local regulation of cell sheet growth can transform planar epidermis globally into complex three-dimensional structures, such as beetle horns, remains unclear. To reveal the relationship between epidermal growth regulation and generated structures, this study theoretically examined how various shapes can be generated from planar epidermis under a deductive growth model that corresponds morphogen distributions to non-uniform growth on tissue. The results show that the heterochronic expression of multiple morphogens can flexibly fuse multiple simple shapes to generate various structures emulating complex outgrowths of beetles. These findings indicate that morphogenesis through such a mechanism may have developmental stability and modularity, providing insights into the evolution of the diverse morphology of arthropods.

Adhesion and shrinkage transform the rounded pupal horn into an angular adult horn in Japanese rhinoceros beetle

Clarifying the mechanisms underlying shape alterations during insect metamorphosis is important for understanding exoskeletal morphogenesis. The large horn of the Japanese rhinoceros beetle Trypoxylus dichotomus is the result of drastic metamorphosis, wherein it appears as a rounded shape during pupation and then undergoes remodeling into an angular adult shape. However, the mechanical mechanisms underlying this remodeling process remain unknown. In this study, we investigated the remodeling mechanisms of the Japanese rhinoceros beetle horn by developing a physical simulation. We identified three factors contributing to remodeling by biological experiments - ventral adhesion, uneven shrinkage, and volume reduction - which were demonstrated to be crucial for transformation using a physical simulation. Furthermore, we corroborated our findings by applying the simulation to the mandibular remodeling of stag beetles. These results indicated that physical simulation applies to pupal remodeling in other beetles, and the morphogenic mechanism could explain various exoskeletal shapes.

Cottonseed Meal Protein Hydrolysate Improves the Growth Performance of Chinese Mitten Crab (Eriocheir sinensis) by Promoting the Muscle Growth and Molting Performance

Growth retardation and prolonged marketing cycle have been noticed in the practical aquaculture of Chinese mitten crab (Eriocheir sinensis) fed with artificial feed. Plant protein hydrolysates contain a large number of small peptides and free amino acids, which can improve the growth performance of aquatic animals. However, the potential mechanisms are still not well elucidated. In this research, the influences of cottonseed meal protein hydrolysate (CPH) on the growth, feed utilization, muscle growth, and molting performance were investigated in E. sinensis. A total of 240 crabs (mean body weight 37.32 ± 0.38 g) were individually randomly distributed to six diets supplemented with 0%, 0.2%, 0.4%, 0.8%, 1.6%, and 3.2% of CPH for 12 weeks. These findings indicated that the addition of CPH at 0.4% significantly increased the survival rate, body protein gain, apparent protein utilization, trypsin and pepsin activities, and the methyl farnesoate content. When the dose reached 0.8%, the weight growth ratio, meat yield, ecdysone concentration, and the transcription of the ecdysteroid receptor all significantly increased, while the transcriptions of both myostatin and molt-inhibiting hormone significantly decreased. When CPH was added at 1.6%-3.2%, the feed conversion ratio, body crude protein content, Na+/K+-ATPase activity, and the molting ratio were all significantly improved, while the opposite was true for the transcription of the transforming growth factor-β type I receptor. The investigation results indicated that when added above 0.4%, CPH could stimulate the growth performance of E. sinensis and promote the muscle growth and molting performance.

Correlative microscopy and block-face imaging (CoMBI): a 3D imaging method with wide applicability in the field of biological science

Correlative microscopy and block-face imaging (CoMBI) is an imaging method, which is characterized by the ability to obtain both serial block-face images as a 3-dimentional (3D) dataset and sections for 2-dimentional (2D) light microscopic analysis. These 3D and 2D morphological data can be correlated with each other to facilitate data interpretation. CoMBI is an easy-to-install and low-cost 3D imaging method since its system can be assembled by the researcher using a regular microtome, consumer digital camera, and some self-made devices, and its installation and instruction manuals are open-source. After the first release of CoMBI method from our laboratory, CoMBI systems have been installed in more than a dozen laboratories and are used for 3D analysis of various biological specimens. Typical application of CoMBI is 3D anatomical analysis using the natural color and contrast of the specimen. We have been using CoMBI for analyzing human brain to obtain the fine 3D anatomy as a reference to determine the causes of neurological diseases and to improve the effectiveness of surgery. Recently, we have been using CoMBI for detecting the colors of chromogens, which are used for labeling specific molecules. Mouse embryos colored with X-gal, a conventional chromogen for detecting LacZ products, were imaged using CoMBI, and the 3D distribution of X-gal was successfully visualized. Thus, CoMBI can now be used for many purposes, including 3D anatomical analysis, 2D microscopy using sections, and 3D distribution of specific molecules. These suggest that CoMBI should be more widely used in the field of biological research.

Recent advances in understanding horn formation in the Japanese rhinoceros beetle Trypoxylus dichotomus using next-generation sequencing technology

The exaggerated horns of beetles are attractive models for studying the origin of novel traits and morphological evolution. Closely related species often differ profoundly in the size, number, and shape of their horns, and in the body region from which they extend. In addition, beetle horns exhibit exquisite nutrition-dependent phenotypic plasticity, leading to disproportionate growth of the horns in the largest, best-condition individuals and much smaller - even stunted - horn sizes in poor-condition individuals. These exciting phenomena in beetle horns have recently been revealed at the molecular level with the advent of next-generation sequencing. This section reviews the latest research on a horned beetle, the Japanese rhinoceros beetle Trypoxylus dichotomus, whose genome was recently sequenced.

An adaptive locally-coded point cloud classification and segmentation network coupled with genetic algorithm

Local information coding helps capture the fine-grained features of the point cloud. The point cloud coding mechanism should be applicable to the point cloud data in different formats. However, the local features of the point cloud are directly affected by the attributes, size and scale of the object. This paper proposes an Adaptive Locally-Coded point cloud classification and segmentation Network coupled with Genetic Algorithm(ALCN-GA), which can automatically adjust the size of search cube to complete network training. ALCN-GA can adapt to the features of 3D data at different points, whose adjustment mechanism is realized by designing a robust crossover and mutation strategy. The proposed method is tested on the ModelNet40 dataset and S3DIS dataset. Respectively, the overall accuracy and average accuracy is 89.5% and 86.5% in classification, and overall accuracy and mIoU of segmentation is 80.34% and 51.05%. Compared with PointNet, average accuracy in classification and mIoU of segmentation is improved about 10% and 11% severally.

Epithelial folding determines the final shape of beetle horns

The elaborate ornaments and weapons of sexual selection, such as the vast array of horns observed in scarab beetles, are some of the most striking outcomes of evolution. How these novel traits have arisen, develop, and respond to condition is governed by a complex suite of interactions that require coordination between the environment, whole-animal signals, cell-cell signals, and within-cell signals. Endocrine factors, developmental patterning genes, and sex-specific gene expression have been shown to regulate beetle horn size, shape, and location, yet no overarching mechanism of horn shape has been described. Recent advances in microscopy and computational analyses combined with a functional genetic approach have revealed that patterning genes combined with intricate epithelial folding and movement are responsible for the final shape of a beetle head horn.