Influence of thyroid hormone on the sequence of cranial bones appearance in early ontogeny of the large African barb (Labeobarbus intermedius; Cyprinidae; Teleostei)

Anatomical Assessment of the Adult Skeleton of Zebrafish Reared Under Different Thyroid Hormone Profiles

“…Our anatomical results are largely consistent with previous studies of induced TH− and TH+ conditions, although there are key differences (Shkil and Smirnov, ; Shkil et al, ,b; Shkil et al, ; Smirnov et al, ; Kapitanova and Shkil, ,b). Our work uses zebrafish that have endogenously altered TH levels (McMenamin et al, ) rather than exogenously altered TH levels by continuous drug treatments (Shkil et al, ; Kapitanova and Shkil, ).…”

“…Previous work on zebrafish has shown that TH affects the Weberian apparatus, supraneurals, some craniofacial features, and the neural and hemal arches and spines (Shkil et al, ; Kapitanova and Shkil, ,b), although no comprehensive study of all skeletal elements has been performed. Work in barbs, another cypriniform group, has shown that the ossification sequence of cranial bones changed during ontogeny under different TH conditions (Shkil et al, ). Since TH modulation can produce suites of coordinated morphological changes, the hormone is a potential target for adaptation and diversification in fishes and other vertebrates; a better understanding of the skeletal modules regulated by the hormone can lend insight into TH as a target for evolutionary adaptation.…”

Thyroid hormone in skeletal development of cyprinids: effects and morphological consequences

“…The reactions of skull bones to TH changes are more pronounced. The cranial development of barbs has two peaks of explosive osteogenesis separated by a stasis stage – period when new skull bones do not arise, but earlier formed bones continue to grow (Shkil et al., 2010b; Smirnov et al., 2012). In larvae reared under high TH level, stasis period shows reduction to the point of complete disappearance.…”

“…react only slightly, if ever, to the increase of TH level, and, there are no changes in the timing of their appearance. Other bones of the second peak (infraorbitals; latero‐, supra‐ and mesethmoid, palatine, among others) display a strong reaction to TH level changes (Shkil et al., 2010b). These bones, normally appearing after the stasis period, arise precociously under high TH level.…”

“…Each clutch of fertilized eggs obtained from wild spawners was divided into three groups and reared under different hormonal regimes: (i) control group reared in pure water; (ii) group reared in 1 ng ml )1 of alkaline solution of 3,5,3¢-thriiodothyronine (T 3 ) -high TH level; and (iii) group reared under 0.02% of thiourea, a goitrogen blocking the activity of thyroid gland and leading to TH deficiency -low TH-level. All other conditions were the same for all groups, for more details see Shkil et al (2010b). In choosing T 3 we relied on evidence that it, and not T 4 , is the only active TH in fish (Janz and Weber, 2000).…”