Data from: Second harmonic generation imaging reveals entanglement of collagen fibers in the elephant trunk skin dermis

Schulz, Andrew1 ; Plotczyk, Magdalena2; Sordilla, Sophia1; Gaboriau, David2; Boyle, Madeline1; Singal, Krishma1; Reidenberg, Joy3; Hu, David1; Higgins, Claire2

Published Dec 09, 2024 on Dryad. https://doi.org/10.5061/dryad.bk3j9kdm9

Data files

Dec 09, 2024 version files 959.28 MB

FigureData.xlsx
416.53 KB
H_E.zip
55.19 MB
PieceDescriptionforSHG.xlsx
9.16 KB
README.md
8.20 KB
SHG_images.zip
903.66 MB

Abstract

Form-function relationships often have tradeoffs: if a material is tough, it is often inflexible, and vice versa. This is particularly relevant for the elephant trunk, where the skin should be protective yet elastic. To investigate how this is achieved, we used classical histochemical staining and second harmonic generation microscopy to describe the morphology and composition of elephant trunk skin. We report structure at the macro and micro scales, from the thickness of the dermis to the interaction of 10 micro-m thick collagen fibers. We analyzed several sites along the length of the trunk to compare and contrast the dorsal-ventral and proximal-distal skin morphologies and compositions. We find the dorsal skin of the elephant trunk can have keratin armor layers over 2mm thick, which is nearly 100 times the thickness of the equivalent layer in human skin. We also found that the structural support layer (the dermis) of the elephant trunk contains a distribution of collagen-I (COL1) fibers in both perpendicular and parallel arrangement. The bimodal distribution of collagen is seen across all portions of the trunk, and is dissimilar from that of human skin where one orientation dominates within a body site. We hypothesize that this distribution of COL1 in the elephant trunk allows both flexibility and load-bearing capabilities. Additionally, when viewing individual fiber interaction of 10 micro-m thick collagen, we find the fiber crossings per unit volume are five times more common than in human skin, suggesting that the fibers are entangled. We surmise that these intriguing structures permit both flexibility and strength in the elephant trunk. The complex nature of the elephant skin may inspire the design of materials that can combine strength and flexibility.

README: Data from: Second harmonic generation imaging reveals entanglement of collagen fibers in the elephant trunk skin dermis

https://doi.org/10.5061/dryad.bk3j9kdm9

Data was collected at Imperial College London, South Kensington, on a 38-year-old female African elephant (Loxodonta africana) that initially lived in the United States. The trunk was on loan from the National Museum of Natural History (NMNH), Smithsonian Institution. These samples were shipped on dry ice to Imperial College London by the Smithsonian Institute Collections Department as a scientific exchange between the two CITES-registered institutions. The Animal Plant and Health Agency in the UK (authorization number ITIMP19.0822) approved the tissue shipment. The samples were stored at Imperial College London at -80 degrees C until embedding, sectioning, and imaging were conducted from January to March 2020.

Contact Andrew Schulz (aschulz@is.mpg.de) with any questions.

Description files include:

PieceDescriptionforSHG.xlsx

This Excel file contains information for each of the SHG microscopy TIF stacks, which is included in the Zip file folder. The H&E and SHG images in the zip folders are named by a specific piece number.These piece numbers correspond to the piece number included on this sheet as well as the dorsal or ventral description.

Variable	Units	Description
Trunk Piece Number (for SHG Labels)	Number	The specific number of the specimen. This corresponds to the SHG and H&E Zip files also included as a simple way to denote which piece is from which section on the trunk.
Dorsal or Ventral Trunk	D or V	This is to specify if the piece was from the dorsal (top portion) or ventral (bottom portion) of the trunk.
Distance from Tip	cm	This is the distance the piece is taken from the tip of the trunk given in cm.
Dissection Date	date	This is the date of the original dissection that was performed.
Detailed Description	text	This provides a detailed description of where the skin piece came from. LNP stands for left nasal passage. We also provide the anatomical description including dorsal, ventral, proximal, and distal.

FigureData.xlsx

This Excel file contains the information and raw data for the figures including figure values, averages, and raw data for Figure 4D, 5C, Figure 6B, as well as the Supplementary figures in the manuscript. Overall the file has four sheets or pages in including "FigureData", "SC* *Thickness", "VE Thickness", and "Dermis Thickness". The first page "FigureData" describes has the following tables:

Figure4D Table

Variable	Unit	Description
Location on Trunk	cm	This is the distance from the tip of the elephant trunk in cm ranging from 3 to 133 cm from the point.
Normalized Intensity	arbitrary units	This is the normalized intensity for the different sites on the elephant trunk describing the differences of the intensity of the SHG signal in the ImageJ analysis.
Dorsal/Ventral	Dorsal/Ventral	These headers indicate if the trunk position was on the dorsal or ventral measurement.

Figure5C Table

Variable	Unit	Description
Location on Trunk	cm	This is the distance from the tip of the elephant trunk in cm ranging from 3 to 133 cm from the point.
Dorsal/Ventral	Dorsal/Ventral	These headers indicate if the trunk position was on the dorsal or ventral measurement.
Perpendicular/Parallel	Perpendicular/Parallel	These headers indicate the perpendicular or parallel data for each of the sections
Percentage of fiber	%	These are the descriptions for the percentages of the fibers given in mean plus or minus standard deviation shown by the columns in percentage.

Figure 6 Table

Variable	Unit	Description
Species/site		This is the specific site as well as species indicating if the data is taken from elephants or humans as well as what site (dorsal/ventral) in elephants or plantar/non-plantar in humans.
Collagen crossings	crossings per micro-m^3	This is the number of collagen crossings that occur per micro-m^3

Sheet Tables "SC Thickness", "VE Thickness", and "Dermis Thickness":

Variable	Unit	Description
Location	Dorsal/Ventral	This indicates if the site was from the dorsal or ventral section of the trunk
Distance	cm	This is the distance in cm the location was from the tip of the elephant trunk
Thickness	mm	This is the thickness of the location and distance from the H&E files included in the zip folder.

Data files include:

H_E.zip

This is a file containing the raw H&E unedited images. Specific files are labeled by their elephant piece number which corresponds to the first column on the "PieceDescriptionforSHG.xlsx" also included in the repo.

SHG_images.zip

This file contains both the raw .tif unedited images of the second harmonic generation (SHG) microscopy files as well as the overlayed with scale bar .png files from the SHG scans. Specific files are labeled by their elephant piece number which corresponds to the first column of the "PieceDescriptionforSHG.xlsx" also included in the repo.