Biology subjects

Ang, K. C.

Publications and source records attributed to Ang, K. C..

7 recordsLinked to original sources

bioRxiv2026

Long-range neural pathways for octopus chemotactile processing revealed from periphery-to-brain by centimeter-field microCT

Understanding how nervous systems mediate responses to sensation requires whole-body maps of periphery-to-brain connections. Octopuses exemplify this challenge with distributed control of eight arms and hundreds of suckers, yet their long-range microanatomical wiring remains elusive due to limitations in microscopy. We extend histotomography (Ding et al. 2019), a form of soft tissue microCT customized for volumetric characterization of cells and tissues, to centimeter range with a custom micro-CT imaging system (Ding et al., 2019). With its 10-mm field of view and 0.7-{micro}m isotropic voxels we created a high-resolution digital intact small octopus. This multi-tissue 3D blueprint enabled us to (i) elucidate previously uncharacterized chemotactile pathways from the suckers to the brain, (ii) discern subdivisions of the nerve ring connecting neighboring arms, and (iii) segment over 300 structures across organ systems at histology-like resolution. We release the labeled interactive digital specimen to facilitate collaborative whole-organism phenotyping as a practical foundation for digital organismal biology. ONE-SENTENCE SUMMARYWhole-body 3D histology reveals neural and organ architecture throughout a small octopus.

systems biology↗

bioRxiv2023

Staining and resin embedding of whole Daphnia samples for micro-CT imaging

Micro-CT imaging is a powerful tool for generating high resolution, isotropic three-dimensional datasets of whole, centimeter-scale model organisms that can be used for qualitative and quantitative analysis. The small size, global freshwater distribution, wide range of cell size and structures of micron scale, and common use of D. magna in toxicological and environmental studies make it an ideal model for demonstrating the potential power of micro-CT-enabled whole-organism phenotyping. This protocol details the steps involved in D. magna samples preparation for micro-CT: euthanasia, fixation, staining, and resin embedding. Micro-CT reconstructions of samples imaged using synchrotron micro-CT reveal histological (microanatomic) features of organ systems, tissues, and cells in the context of the entire organism at sub-micron resolution, and in 3 dimensionality. The enabled "3D histology" and 3D renderings can be used towards morphometric analyses across cells, tissues, and organ systems for both descriptive and hypothesis testing studies.

zoology↗

bioRxiv2022

Web-based Histology Reference Atlas for the Freshwater Crustacean Daphnia magna

Daphnia are keystone species of freshwater habitats used as model organisms in ecology and evolutionary biology. Their small size, wide geographic distribution, and sensitivity to chemicals make them useful as environmental sentinels in regulatory toxicology and chemical risk assessment. Biomolecular (-omic) assessments of responses to chemical toxicity, which reveal detailed molecular signatures, become more powerful when correlated with other phenotypic outcomes (such as behavioral, physiological, or histopathological) for comparative validation and regulatory relevance. However, the lack of histopathology or tissue phenotype characterization of this species presently limits our ability to access cellular mechanisms of toxicity. Here, we address the central concept that interpreting aberrant tissue phenotypes requires a basic understanding of species normal microanatomy. We introduce the female and male Daphnia Histology Reference Atlas (DaHRA) for the baseline knowledge of Daphnia magna microanatomy. Additionally, we also included developmental stages of female Daphnia in this current atlas. This interactive web-based resource of adult Daphnia features overlaid vectorized demarcation of anatomical structures whose labels comply with an anatomical ontology created for this atlas. We demonstrate the potential utility of DaHRA for toxicological investigations by presenting aberrant phenotypes of acetaminophen-exposed D. magna. We envision DaHRA to facilitate the effort of integrating molecular and phenotypic data from the scientific community as we seek to understand how genes, chemicals, and environment interactions determine organismal phenotype.

zoology↗

bioRxiv2021

Effects of Hypopigmentation Alleles and Ancestry on Skin Color in the Kalinago of Dominica

Our interest in the genetic basis of skin color variation between populations led us to seek a Native American population with African admixture but low frequency of European light skin alleles. Analysis of 458 genomes from individuals residing in the Kalinago territory of the Commonwealth of Dominica showed approximately 55% Native American, 32% African, and 12% European ancestry, the highest Native American ancestry among Caribbean populations to date. Skin pigmentation ranged from 20 to 80 melanin units, averaging 46. Three albino individuals were determined to be homozygous for a causative multi-nucleotide polymorphism OCA2NW273KV contained within a haplotype of African origin; its allele frequency was 0.03 and single allele effect size was -8 melanin units. Derived allele frequencies of SLC24A5A111T and SLC45A2L374F were 0.14 and 0.06, with single allele effect sizes of -6 and -4, respectively. Native American ancestry by itself reduced pigmentation by more than 20 melanin units (range 24 - 29). The responsible hypopigmenting genetic variants remain to be identified, since none of the published polymorphisms predicted in prior literature to affect skin color in Native Americans caused detectable hypopigmentation in the Kalinago.

genetics↗

bioRxiv2021

A Wide-Field Micro-Computed Tomography Detector: Micron Resolution at Half-centimeter Scale

Ideal 3-dimensional imaging of many complex samples, such as biological tissues made up of micro-scale structures extending over millimeter- to centimeter-scale tissue samples and organisms, requires both a wide field-of-view and high resolution. With existing optics and detectors used for micro-CT imaging, sub-micron pixel resolution can only be achieved for fields-of-view of <2 mm. This manuscript presents a unique detector system with a 6-mm field-of-view image circle and 0.5 m pixel size that can be used in both synchrotron facilities and tabletop micro-CT units. A resolution-test pattern with linear microstructures and whole adult Daphnia magna were imaged on Beamline 8.3.2 of the Advanced Light Source. Volumes of 10,000 x 10,000 x 7,096 isotropic 0.5 m voxels were reconstructed over a 5.0 x 3.5 mm field-of-view. Measurements in the projection domain confirmed a 1.182 m measured spatial resolution that is largely Nyquist-limited. This unprecedented combination of field-of-view and resolution dramatically reduces the need for sectional scans and computational stitching for large samples, ultimately offering the means to elucidate change in tissue and cellular morphology in the context of larger whole, intact model organisms and specimens. This development is also anticipated to benefit micro-CT imaging in materials science, microelectronics, agricultural science, and biomedical engineering. SynopsisA custom wide-field lens and a new-generation megapixel camera enabled microCT scanning over a 3.5 x 5 mm field-of-view at a 1 m resolution / 0.5 m pixel size at the Berkeley Lawrence Advanced Light Source using a phantom with micron scale features. This novel combination of resolution and field-of-view will be broadly applicable to any setting in which micron-scale structures need to be characterized comprehensively in 3 dimensions over mm to cm scale.

bioinformatics↗

bioRxiv2021

Whole-organism 3D Quantitative Characterization of Zebrafish Melanin by Silver Deposition Micro-CT

Melanin-rich zebrafish melanophores are used to study pigment development, human skin color, and as a large-scale screening phenotype. To facilitate more detailed whole-body, computational analyses of melanin content and morphology, we have combined X-ray microtomography (micro-CT), a non-destructive, full-volume imaging modality, with a novel application of ionic silver staining to characterize melanin distribution in whole zebrafish larvae. Normalized micro-CT reconstructions of silver-stained fish consistently reproduced pigment patterns seen by light microscopy, and allowed direct quantitative comparisons of melanin content across wild-type and mutant samples, for both dramatic and subtle phenotypes not previously described. Silver staining of melanin for micro-CT provides proof-of-principle for whole-body, three-dimensional computational phenomic analysis of a particular cell type at cellular resolution, with potential applications in other model organisms and human melanoma biopsies. Whole-organism, high-resolution phenotyping is a challenging ideal, but provides superior context for functional studies of mutations, diseases, and environmental influences.

pathology↗

bioRxiv2018

Three-Dimensional Histology of Whole Zebrafish by Sub-Micron Synchrotron X-ray Micro-Tomography

Histological studies providing cellular insights into tissue architecture have been central to biological discovery and remain clinically invaluable today. Extending histology to three dimensions would be transformational for research and diagnostics. However, three-dimensional histology is impractical using current techniques. We have customized sample preparation, synchrotron X-ray tomographic parameters, and three-dimensional image analysis to allow for complete histological phenotyping using whole larval and juvenile zebrafish. The resulting digital zebrafish can be virtually sectioned and visualized in any plane. Whole-animal reconstructions at subcellular resolution also enable computational characterization of the zebrafish nervous system by region-specific detection of cell nuclei and quantitative assessment of individual phenotypic variation. Three-dimensional histological phenotyping has potential use in genetic and chemical screens, and in clinical and toxicological tissue diagnostics.\n\nOne Sentence SummarySynchrotron X-ray micro-tomography can be used to rapidly create 3-dimensional images of fixed and stained specimens without sectioning, enabling computational histological phenotyping at cellular resolution.

pathology↗