Temporal relationship between fetal bovine skeletal growth and circulating hormonal levels

Widespread differential maternal and paternal genome effects on fetal bone phenotype at mid-gestation

Parent-of-origin-dependent (epi)genetic factors are important determinants of prenatal development that program adult phenotype. However, data on magnitude and specificity of maternal and paternal genome effects on fetal bone are lacking. We used an outbred bovine model to dissect and quantify effects of parental genomes, fetal sex, and nongenetic maternal effects on the fetal skeleton and analyzed phenotypic and molecular relationships between fetal muscle and bone. Analysis of 51 bone morphometric and weight parameters from 72 fetuses recovered at day 153 gestation (54% term) identified six principal components (PC1-6) that explained 80% of the variation in skeletal parameters. Parental genomes accounted for most of the variation in bone wet weight (PC1, 72.1%), limb ossification (PC2, 99.8%), flat bone size (PC4, 99.7%), and axial skeletal growth (PC5, 96.9%). Limb length showed lesser effects of parental genomes (PC3, 40.8%) and a significant nongenetic maternal effect (gestational weight gain, 29%). Fetal sex affected bone wet weight (PC1, p < 0.0001) and limb length (PC3, p < 0.05). Partitioning of variation explained by parental genomes revealed strong maternal genome effects on bone wet weight (74.1%, p < 0.0001) and axial skeletal growth (93.5%, p < 0.001), whereas paternal genome controlled limb ossification (95.1%, p < 0.0001). Histomorphometric data revealed strong maternal genome effects on growth plate height (98.6%, p < 0.0001) and trabecular thickness (85.5%, p < 0.0001) in distal femur. Parental genome effects on fetal bone were mirrored by maternal genome effects on fetal serum 25-hydroxyvitamin D (96.9%, p < 0.001) and paternal genome effects on alkaline phosphatase (90.0%, p < 0.001) and their correlations with maternally controlled bone wet weight and paternally controlled limb ossification, respectively. Bone wet weight and flat bone size correlated positively with muscle weight (r = 0.84 and 0.77, p < 0.0001) and negatively with muscle H19 expression (r = -0.34 and -0.31, p < 0.01). Because imprinted maternally expressed H19 regulates growth factors by miRNA interference, this suggests muscle-bone interaction via epigenetic factors.

Plasma alkaline phosphatase as a sensitive indicator of age and skeletal development in wild coscoroba swans

Context. Recent studies have suggested that plasma alkaline phosphatase (ALP) can be used to assess skeletal development as well as health status in wild animals. Aims. However, the information about age-related dynamics of ALP in birds, especially in precocial species, is very scarce. Therefore, before ALP measurements can be effectively interpreted, it is necessary to determine its normal variation for each species, age group and sex. Methods. Here, we report total-ALP levels of free-living coscoroba swans (Coscoroba coscoroba) from the most important breeding and moulting population in Brazil. Data were gathered during the moulting period and categorised according to sex and the following three different age classes: chick (n = 11), young (n = 14) and mature (n = 29). Key results. ALP levels were related to the longitudinal measure of the bones, gradually diminishing with age and showing significant differences among birds of different age classes. In all age groups, no effect of sex on T-ALP concentration was detected. Conclusions. We conclude that measuring ALP facilitates the discrimination among different-aged individuals with similar plumage characteristics and body size.

Growth and nutritional state of American Crow nestlings vary between urban and rural habitats

In urbanized areas, many adult birds find sufficient foods to survive, but the anthropogenic foods that are abundant there may be detrimental to nestling growth. In fact, American Crow (Corvus brachyrhynchos) nestlings are smaller in suburban than rural areas, possibly because of nutrient limitation. Here, we seek to identify possible causes of size differences by comparing both size and blood chemistry measures in rural and suburban crow nestlings. We quantified land use in known crow territories and distinguished three distinct environments: suburban-residential, suburban-managed (e.g., golf courses), and rural. We measured nestlings near fledging age in each environment and bled them for determination of unbound plasma calcium, total protein, and corticosterone. We supplemented a subset of broods in suburban-residential and rural areas with a food high in protein and calcium. Rural nestlings were significantly larger than suburban-residential crows and had higher total serum protein. Nestlings in suburban-managed areas were intermediate in size and serum protein but had the lowest plasma calcium levels. Nestling corticosterone levels did not differ significantly among habitats, indicating that, although suburban nestlings may be food-limited, they were not starving. Supplemented nestlings in suburban-residential areas were significantly larger in some growth measures than their unsupplemented counterparts. Unexpectedly, supplemented rural nestlings were significantly smaller than unsupplemented rural ones, suggesting that parents use easily accessible food even when it is nutritionally suboptimal. Our results indicate that nestlings in suburban areas are nutrient restricted, rather than calorie restricted.

Metabolic traits affecting growth rates of pre-pubertal calves and their relationship with subsequent survival

This study related growth and metabolic traits in Holstein-Friesian calves (n=45) to subsequent performance and longevity. Animals were measured at birth, 3, 6 and 9 months (weight, crown rump length (CRL), heart girth and height). Endocrine and metabolic traits were assessed at 6 months of age. These traits were not influenced by sire (n=5). Milk production and mortality records were obtained through 3 lactations. Seven heifers failed to achieve a lactation, 6 were culled after one, 17 after two and 15 (33%) survived >/=3 lactations. Birth weight and girth but not skeletal measures were highly positively correlated with the repeated size measurements at 3-9 months. Calves with higher cortisol at 6 months were smaller in weight and girth at 3 months, with reduced 3-6 months skeletal growth. GH secretion was related to height, weight and growth, whereas urea was most strongly related to CRL. Calves not achieving a single lactation had lower IGF-I. Calves with higher glucose or BHB were more likely to be culled after 2 lactations, an effect which was independent of yield. Size and metabolic measurements of growing calves may therefore prove useful in predicting longevity.

Ontogenesis of IGF regulation of longitudinal bone growth in rat metatarsal rudiments cultured in serum-free medium

The aim of this study was to compare the effect of two cytokines, IGF-I and IGF-II on skeletal development in the rat. The three medial metatarsal rudiments were dissected out from fetuses at days 19, 20 or 21 of gestation and from newborns at days 1, 3, 6 and 9 after birth, then grown in serum-free MEM medium at 37 degrees C and 5% CO2 in air. From day 19 of gestation to the end of experiment, longitudinal bone growth (mm) was significantly increased by IGF-I (2.975 +/- 0.050) and IGF-II (2.530 +/- 0.062), compared to controls (2.188 +/- 0.060). In the same way, the width (mm) at the last experimental day was 0.360 +/- 0.010 in IGF-I- and 0.327 +/- 0.008 in IGF-II-treated bones, respectively (vs 0.313 +/- 0.012 in controls). Mineralization was also stimulated under both growth factors (length of the calcified diaphysis (mm): 0.691 +/- 0.019 in IGF-I- and 0.446 +/- 0.017 in IGF-II-treated bones; vs 0.383 +/- 0.024 in controls). IGF-I and IGF-II (but to a lesser extent) stimulation was due to an increased DNA synthesis (3H-thymidine uptake) as well as protein anabolism (incorporated proline). In addition, cartilage activity (35S captation) and mineralization (45Ca fixed) were involved in the action of these cytokines. An age dependency of bone response to IGFs was pointed out, the effect being higher during the fetal period than after birth. In conclusion, our results raise the possibility that IGF-II, as well as IGF-I, is involved in the control of osteogenesis.

Stimulation of adult chondrocyte metabolism by a thyroid-derived factor

This paper reports the effects of adding partially purified bovine thyroid calcitonin, thyrocalcitonin, to adult bovine articular cartilage cells. Thyrocalcitonin stimulated chondrocyte proliferation fourfold under low serum (0.5%) culture conditions. In serum-free medium, thyrocalcitonin stimulated cell proliferation more than twofold. With high-density cultures in serum-free medium, chondrocyte glycosaminoglycan (GAG) synthesis was stimulated 60% by thyrocalcitonin. Cell-associated radioactivity was increased twofold. In contrast to thyrocalcitonin, addition of human and salmon calcitonin peptides as well as the thyroid hormones T3 and T4 had no effect on adult cartilage cell proliferation or GAG synthesis. The data reported here suggest the existence of a thyroid-derived factor, independent of calcitonin peptides or thyroid hormones, which stimulates adult articular chondrocyte metabolism.

Gestational changes of thyroid hormone action in the developing fetal bovine epiphysis

Thyroid hormones are essential for cartilage growth and maturation. In order to assess their actions during different periods of skeletal development, [125I]-triiodothyronine (T3) binding capacity in epiphyseal cartilage and triiodothyronine concentrations in serum were quantitated in bovine fetuses of the second and third trimesters of gestation (equivalent to fetal sizes of 10-90 cm crown-rump (CR) length), and related to the alkaline phosphatase activities in the same cartilaginous tissues. Nuclear T3 binding levels, which were initially low during 10-30 cm CR, rose to a peak value (1.7 pmol/mg DNA) at the end of the second trimester (40-50 cm CR). Then, following a sharp decline at 50-60 cm CR, T3 binding rose to a moderate level in the later gestational period (60-90 cm CR). Serum total triiodothyronine rose transiently in fetuses of 30-50 cm CR to a peak level (34 ng/100 ml), and subsequently increased continuously in the later period (60-90 cm CR). Alkaline phosphatase activities measured in epiphyseal chondrocytes rose significantly in fetuses of 60-90 cm CR. The coincident rise of cartilage triiodothyronine binding capacity and serum circulating triiodothyronine levels in the late second trimester suggests that this thyroid hormone induces its own binding sites in bovine epiphyseal cartilage; the dramatic increase in the level of serum triiodothyronine during the third trimester of gestation is temporally related to the increase in alkaline phosphatase activity of chondrocytes, as well as other recognized developmental changes in the fetal bovine skeletal tissues.