Dynamic transcriptome and histomorphology analysis of developmental traits of hindlimb thigh muscle from Odorrana tormota and its adaptability to different life history stages

Abstract

Background: Systematic studies on the development and adaptation of hindlimb muscles in anura amphibians are rare. Here, we integrated analysis of transcriptome and histomorphological data for the hindlimb thigh muscle of Odorrana tormota (concave-eared torrent frog) at different developmental stages, to uncover the developmental traits of hindlimb thigh muscle from O. tormota and its adaptability to different life history stages.

Results: The development of hindlimb thigh muscle from O. tormota has the following characteristics. Before metamorphosis, myogenous cells proliferate and differentiate into myotubes, and form 11 muscle groups at G41; Primary myofibers and secondary myofibers appeared during metamorphosis; 11 muscle groups differentiated continuously to form myofibers, accompanied by myofibers hypertrophy after metamorphosis; During the growth process of O. tormota from G42 to G46, there were differences between the sexes in the muscle groups that differentiate into muscle fibers, indicating that there was sexual dimorphism in the hindlimb thigh muscles of O. tormota at the metamorphosis stages. Some genes and pathways related to growth, development, and movement ability of O. tormota at different developmental stages were obtained. In addition, some pathways associated with adaptation to metamorphosis and hibernation also were enriched. Furthermore, integrated analysis of the number of myofibers and transcriptome data suggested that myofibers of specific muscle groups in the hindlimbs may be degraded through lysosome and ubiquitin pathways to transform into energy metabolism and other energy-related substances to meet the physiological needs of hibernation.

Conclusions: These results provide further understanding the hindlimb thigh muscle development pattern of frogs and their adaption to life history stages.

Keywords: Adaptability; Anura amphibians; Development; Hindlimb thigh muscle; Histomorphology; Odorrana tormota; Transcriptome.

Fig. 1

Transverse section of hindlimb thigh muscles in different tadpole stages. Abbreviations: a G26; b G36; c G37; d G41; e G41; f G42; g G45; h G46. The rectangle represents two streams of myogenous cells. VM, vastus medialis muscle; MS, musculi semimenbranosus; AM, adductor magnus muscle; GM, gracilis major; VL, vastus lateralis muscle; BF, biceps femoris muscle; Sa, sartorius; Se, semitendinosus; GMi, gracilis minor; RF, rectus femoris muscle; AL, adductor longus. MC, myogenous cell; MT, myotube; P-MF, primary myofiber; S-MF, secondary myofiber. F-, corresponding muscle groups in the future

Fig. 2

Transverse section of hindlimb thigh muscles. Abbreviations: a 1-month old; b 3- month-old; c 5-month- old; d 10-month-old; e, 14-month-old; f 2-year-old; g 3-year-old; h 4-year-old. The hollow arrow refers to 2-, 3- or 4-nuclei myofibers. Magnification, 400x (bar = 50 μm)

Fig. 3

Comparison of the number of muscle fibers at 3-month-old and 5-month-old. MS, musculi semimenbranosus; GM, gracilis major; VL, vastus lateralis muscle; Sa, sartorius; GMi, gracilis minor; RF, rectus femoris muscle. *, P < 0.05 (one-way ANNOVA). Error bars indicate the mean ± SEM (standard error of mean)

Fig. 4

7 clusters obtained by time series analysis and PCA analysis. 3MO, 3- month-old; 5OM, 5-month- old; 14OM, 14-month-old; 2YO, 2-year-old

Fig. 5

KEGG pathways enriched in six comparable groups. a G36 vs G40 group. b G40 vs G42 group. c G45 vs 3-month-old group. d 3-month-old vs 5-month- old group. e 5-month- old vs 14-month-old group. f 14-month-old vs 2-year-old group

Fig. 6

Validation of six DEGs by RT-qPCR. The r value represents Pearson’s correlation coefficient between two methods