The Regulation of Growth in Developing, Homeostatic, and Regenerating Tetrapod Limbs: A Minireview

The size and shape of the tetrapod limb play central roles in their functionality and the overall physiology of the organism. In this minireview we will discuss observations on mutant animal models and humans, which show that the growth and final size of the limb is most impacted by factors that regulate either limb bud patterning or the elongation of the long bones. We will also apply the lessons that have been learned from embryos to how growth could be regulated in regenerating limb structures and outline the challenges that are unique to regenerating animals.

Modulating effect of growth hormone on the functional state of cultured cells from hen preovulatory follicles

Somatotropic hormone (STH) is an important positive modulator of ovarian function in mammals. Local production of STH and the expression of the corresponding specific receptors were also detected in hen ovarian follicles, which indicates the participation of this hormone in the endocrine/paracrine control of folliculogenesis in birds. Nevertheless, the role of STH in the regulation of growth of avian follicles at the final stage of maturation is still not clear.Objective: To study in vitro the effect of STH on the proliferative activity and apoptotic changes of granulosa and theca cells from preovulatory follicles of domestic hens.Materials and methods. Young laying hens aged 34-35 weeks with a long clutch were used in the experiments. Granulosa and theca cells were isolated from the largest yellow follicle in the hierarchy (F1). The cells were cultured in a medium containing 10% fetal bovine serum until a monolayer was formed, and then for 24 h in the medium without serum in the absence (control) or in the presence of STH at various concentrations (1-100 ng/ml). The proliferative activity and apoptotic changes in the cells were assessed by immunocytochemical assay, based on the expression level of proliferating cell nuclear antigen PCNA and pro-apoptotic protein Bax, respectively.Results. The proportion of PCNA-positive granulosa cells increased 1.3-1.8 times (P<0.01-0.05) as compared to control with increasing the content of STH in the medium to 10-100 ng/ml. Furthermore, within this concentration range, the studied hormone reduced 1.2-1.6 times (P<0.05) the relative number of granulosa cells with the positive reaction to Bax. The sensitivity of theca cells to the growth-stimulating effect of STH was lower than that of granulosa cells. Such the effect of STH led to an increase in the proportion of PCNA-positive thecal cells by 1.2-1.3 times (P<0.05) and was detected only at concentrations of 25 and 100 ng/ml. Meanwhile, STH (25-100 ng/ml) increased 1.3 times (P<0.05) the level of Bax expression in theca cells.Conclusions. The results of the present study indicate the stimulating effect of STH in vitro on the proliferative activity of granulosa and theca cells from the most mature hen preovulatory follicle. In addition, STH is able to reduce the expression of the pro-apoptotic protein Bax in granulosa cells and increase this expression in thecal cells. Thus, the data obtained indicate the possible participation of STH in the regulation of growth and development of follicles at the final stage of maturation during the period of maximum egg-laying intensity in laying hens.

Differences in Environmental and Hormonal Regulation of Growth Responses in Two Highly Productive Hybrid Populus Genotypes

Phenotypic plasticity in response to adverse conditions determines plant productivity and survival. The aim of this study was to test if two highly productive Populus genotypes, characterized by different in vitro etiolation patterns, differ also in their responses to hormones gibberellin (GA) and abscisic acid (ABA), and to a GA biosynthesis inhibitor paclobutrazol (PBZ). The experiments on shoot cultures of &lsquo;Hybrida 275&rsquo; (abbr. H275; Populus maximowiczii &times; P. trichocarpa) and IBL 91/78 (Populus tremula &times; P. alba) were conducted either by modulating the physical in vitro environment or by adding specific chemicals to the nutrient medium. Our results show that there are significant differences between the studied genotypes in environmental and hormonal regulation of growth responses. The genotype H275, which responded to darkness with PBZ-inhibitable shoot elongation, was unable to recover its growth after treatment with ABA. In contrast, the genotype IBL 91/78, whose shoot elongation was not affected either by darkness or PBZ treatment, recovered so well after the ABA treatment that, when rooted subsequently, it developed longer shoots and roots than without ABA treatment. Our results indicate that GA catabolism and repressive signaling provide an important pathway to control growth and physiological adaptation in response to immediate or impending adverse conditions. These observations can help breeders define robust criteria for identifying genotypes with high resistance and productivity and highlight where genotypes exhibit susceptibility to stress.

An investigation into growth-related genes in the Australasian snapper, Chrysophrys auratus

<p>Growth is a complex quantitative trait that is controlled by a variety of genetic and environmental factors. Due to its significance in animal breeding programmes, growth is a commonly studied trait in agriculture and aquaculture species. The Australasian snapper, Chrysophrys auratus, supports significant commercial and recreational fisheries in New Zealand and has the potential to be developed as a new aquaculture species. However, the relatively slow growth rate of C. auratus is a constraint and little is known of the specific regulation of growth in this species. The overall aim of this thesis research was to use genome sequence data and transcriptomics to investigate the loci that influence growth rate of C. auratus. In Chapter Two, the C. auratus Growth Hormone (GH) gene was identified in the reference genome and the structure and polymorphisms were characterised using re-sequenced data. The GH gene was approximately 5,577 bp in length and was comprised of six exons and five introns. Large polymorphic repeat regions were found in the first and third introns, and putative transcription factor binding sites were identified. Phylogenetic analysis of the GH genes of Perciform fish showed conserved non-coding regions and highly variable non-coding regions. The amino acid sequences and putative secondary structures were also largely conserved across this order. In Chapter Three, the genetic variation of two large intronic repeat regions were assessed in wild C. auratus populations and shown to be polymorphic. The intron 1 locus was then assessed in slow- and fast-growing C. auratus for associations with growth rate. No significant differences were detected in the variation between groups; however, trends seen in the results corroborated other studies of an association between shorter introns and increased gene expression. Further investigation with a larger sample size is needed. A high level of heterozygosity was detected in all populations used in this study and may be due to negative selection acting on one allele (485). In Chapter Four, gene expression data was compared between C. auratus at high (21 °C) and low (13 °C) temperatures to investigate how the gene regulation of growth is influenced by temperature. The high temperature treatment (HTT) was characterized by a large number of differentially expressed genes associated with biosynthesis, skeletal muscle components, and catalytic activity while the low temperature treatment (LTT) had an upregulation of genes associated with important degradation pathways. The results of this study also suggest the action of negative feedback on growth regulation in the HTT, which may be a result of chronic heat stress. This thesis research represents one of the first studies to explore the genetic regulation of growth in C. auratus and makes a significant contribution to the field of research into growth, not only in C. auratus, but also other fish species. The findings presented in this thesis may be applied to a selective breeding programme of C. auratus that aimed to increase the growth rate, and consequently, improve its economic viability as a commercial aquaculture species in New Zealand.</p>

An investigation into growth-related genes in the Australasian snapper, Chrysophrys auratus

<p>Growth is a complex quantitative trait that is controlled by a variety of genetic and environmental factors. Due to its significance in animal breeding programmes, growth is a commonly studied trait in agriculture and aquaculture species. The Australasian snapper, Chrysophrys auratus, supports significant commercial and recreational fisheries in New Zealand and has the potential to be developed as a new aquaculture species. However, the relatively slow growth rate of C. auratus is a constraint and little is known of the specific regulation of growth in this species. The overall aim of this thesis research was to use genome sequence data and transcriptomics to investigate the loci that influence growth rate of C. auratus. In Chapter Two, the C. auratus Growth Hormone (GH) gene was identified in the reference genome and the structure and polymorphisms were characterised using re-sequenced data. The GH gene was approximately 5,577 bp in length and was comprised of six exons and five introns. Large polymorphic repeat regions were found in the first and third introns, and putative transcription factor binding sites were identified. Phylogenetic analysis of the GH genes of Perciform fish showed conserved non-coding regions and highly variable non-coding regions. The amino acid sequences and putative secondary structures were also largely conserved across this order. In Chapter Three, the genetic variation of two large intronic repeat regions were assessed in wild C. auratus populations and shown to be polymorphic. The intron 1 locus was then assessed in slow- and fast-growing C. auratus for associations with growth rate. No significant differences were detected in the variation between groups; however, trends seen in the results corroborated other studies of an association between shorter introns and increased gene expression. Further investigation with a larger sample size is needed. A high level of heterozygosity was detected in all populations used in this study and may be due to negative selection acting on one allele (485). In Chapter Four, gene expression data was compared between C. auratus at high (21 °C) and low (13 °C) temperatures to investigate how the gene regulation of growth is influenced by temperature. The high temperature treatment (HTT) was characterized by a large number of differentially expressed genes associated with biosynthesis, skeletal muscle components, and catalytic activity while the low temperature treatment (LTT) had an upregulation of genes associated with important degradation pathways. The results of this study also suggest the action of negative feedback on growth regulation in the HTT, which may be a result of chronic heat stress. This thesis research represents one of the first studies to explore the genetic regulation of growth in C. auratus and makes a significant contribution to the field of research into growth, not only in C. auratus, but also other fish species. The findings presented in this thesis may be applied to a selective breeding programme of C. auratus that aimed to increase the growth rate, and consequently, improve its economic viability as a commercial aquaculture species in New Zealand.</p>

Evolution and future of growth plate therapeutics

Background: Longitudinal bone growth is regulated by multiple endocrine signals (e.g. growth hormone, insulin-like growth factor I, estrogen, androgen) and local factors (e.g. fibroblast growth factors and their receptors and the C-natriuretic peptide/NPR-2 pathway). Summary: Abnormalities in both endocrine and local regulation of growth plate physiology cause many disorders of human skeletal growth. Knowledge of these pathways creates therapeutic potential for sustaining or even augmenting linear growth. Key message: During the past four decades, advances in understanding growth plate physiology have been accompanied by development and implementation of growth-promoting treatments that have progressed in both efficacy and specificity of action. This paper reviews the history and continuing evolution of growth plate therapeutics.

Insilico Search for Potential DNA Binding Domain of Human Zinc Finger Protein Sp1

Specificity protein 1 (Sp1) belongs to a family of ubiquitously expressed, C2H2-type zinc finger-containing DNA binding proteins that activate or repress transcription of many genes in response to physiological and pathological stimuli. Specificity protein 1 is considered to be a constitutively expressed transcription factor and has been implicated in the regulation of a wide variety of housekeeping genes, tissue-specific genes, and genes involved in the regulation of growth. In order to determine the binding affinity of Sp1 zinc finger domains, the total energy for each and every possible combination of GC box and Zn finger motifs using Hex server, Model IT software’s is calculated. According to the findings of this study, the design of multi-zinc finger proteins with a variety of sequence specificities will be easier to accomplish. Among the three motifs present in Specificity protein 1, motifs 1 and 2 have higher binding affinity than motif 3.