Genetically caused retarded growth in animals

Research Note: Study on the in-situ preservation of pigeons based on the level of endangerment of genetic resources

The large-scale and intensive development of the meat pigeon breeding industry have resulted in the replacement of a large number of low-performance local breeds by a few breeds with excellent production performance. However, due to the characteristics of pigeon species that are monogamous, for which the W chromosome cannot be recovered and for which semen cannot be cryopreserved, the preservation of pigeon species is still mainly based on in-situ preservation. In this study, pigeons were classified into 6 classes of endangerment based on the criteria of the 100-year inbreeding coefficient of poultry populations in the "Assessment of Endangered Poultry Genetic Resources" (NY/T 2996-2016). The results show that when the generation interval was 1.5 yr, the number of ideal populations with the same gene frequency variance or the same heterozygosity decay rate of pigeons in class 1 to 5 was ≤149, 150 to 204, 205 to 316, 317 to 649 and ≥650. In random-reserved breeding, when the generation interval was 1.5 yr, the number of male (female) pigeons corresponding to class 1 to 5 was ≤74, 75 to 102, 103 to 157, 158 to 324 and ≥325. In family-equal-reserved breeding, when the generation interval was 1.5 yr, the number of male (female) pigeons corresponding to class 1 to 5 was ≤36, 37 to 50, 51 to 78, 79 to 162 and ≥163. When the generation interval was 1.5 yr, the inbreeding increments corresponding to class 1 to 5 were ≥0.00335, 0.00244 to 0.00334, 0.00159 to 0.00243, 0.00078 to 0.00158 and ≤0.00077; with the same population size, the inbreeding coefficient and inbreeding increment decreased with the increase of generation interval; the population effective content, inbreeding coefficient and inbreeding increment of family-equal-reserved pigeons were lower than those of random-reserved pigeons. The results of this study have certain reference value for analyzing the status quo of local and endangered species, constructing live gene banks and breeding farms of poultry genetic resources, and rescuing endangered species.

Phenotype and genotype of Boerka goats raised in Bali

Background and Aim

Boerka goats are the new breed in Bali targeted at meeting the increasing demand for lamb. They are meat-type goats created by crossing male Boer and female Kacang breeds. This new breed is expected to have good adaptation in a poor environment, such as Kacang goats and produce good quality lamb as Boer goats. Therefore, this study aimed to examine phenotypic and genotypic characteristics of Boerka goats raised in Bali.

Materials and Methods

A total of 16 female Boerka goats at 2 years old collected from a group of livestock farmers in Sanda Village were used as samples. This observational study began with observations of qualitative characteristics and morphometric measurements of goats, followed by polymerase chain reaction (PCR) of the growth hormone (GH) gene using GH5F and GH5R primers. Polymerase chain reaction products were then sequenced and analyzed with the MEGA 11 program.

Results

The results showed that all Boerka goats had stuck-down ears, the heads were predominantly brown in color (62.5%), the body color pattern tends to be white (87.50%), and the tail color pattern was also dominated by white (62.5%). In morphometric terms, the samples were close to Kacang goats based on the body weight, head length, head width, chest width, depth, and circumference, left front leg circumference, ear length, ear width, tail length, tail width, and flank height except for head height, body length, horn length, and shoulder height. Analysis of the GH gene showed that Boerka goats had a nucleotide composition dominated by the purine base guanine (26.5%) and pyrimidine cytosine (31.8%). Furthermore, they formed a separate cluster with a genetic distance of 14.1% to the Anhui White breed from China, the Tibetan breed, and the Swiss Saanen breed.

Conclusion

Boerka goats raised in Bali have phenotypes, including qualitative characteristics and morphometric measurements close to Kacang goats. As meat-type goats, they also form a separate cluster distinct from similar types worldwide.

Association of GH polymorphisms with growth traits in buffaloes

Members of the somatotrophic axis, especially GH and IGF1, are essential for growth. The association between GH polymorphisms and growth traits was numerously studied in cattle; however, no data are available for such association studies in buffalo. Therefore, this study was conducted to screen for polymorphisms in the GH gene and to study their putative association with growth traits in 200 Egyptian buffaloes. Polymerase chain reaction single-strand conformation polymorphism and sequencing were applied to look for polymorphisms in 3 loci spanning all exons and introns of buffalo GH. The C (MspI+) >T (MspI-) SNP in intron3, which is well known in cattle, was not detected in the examined buffaloes. However, 2 missense mutations were detected in exon5: one previously detected p.Leu153Val SNP, with very low frequencies for the mutant (Val) allele and one novel p.Asn174His SNP. At weaning age, the p.Leu153Val SNP was significantly associated with weaning body weight and gain with the positive effect of the wild allele (Leu) and higher GH serum, mRNA, and protein levels in animals with Leu/Asn and Leu/His haplotypes. At yearling age, the 2 SNPs associated with yearling weight and gain with positive effect for the mutant (Val and His) alleles with increased GH, and IGF1 serum, mRNA, and protein and GHR mRNA and protein levels in animals with Val/Asn haplotype. Therefore, the selection of Egyptian buffaloes with the Val/Asn haplotype could improve the growth traits of Egyptian buffaloes at yearling age which is the target age for perfect growing.

Mapping novel genetic loci associated with female liver weight variations using Collaborative Cross mice

BACKGROUND

Liver weight is a complex trait, controlled by polygenic factors and differs within populations. Dissecting the genetic architecture underlying these variations will facilitate the search for key role candidate genes involved directly in the hepatomegaly process and indirectly involved in related diseases etiology.

METHODS

Liver weight of 506 mice generated from 39 different Collaborative Cross (CC) lines with both sexes at age 20 weeks old was determined using an electronic balance. Genomic DNA of the CC lines was genotyped with high-density single nucleotide polymorphic markers.

RESULTS

Statistical analysis revealed a significant (P < 0.05) variation of liver weight between the CC lines, with broad sense heritability (H 2) of 0.32 and genetic coefficient of variation (CVG) of 0.28. Subsequently, quantitative trait locus (QTL) mapping was performed, and results showed a significant QTL only for females on chromosome 8 at genomic interval 88.61-93.38 Mb (4.77 Mb). Three suggestive QTL were mapped at chromosomes 4, 12 and 13. The four QTL were designated as LWL1-LWL4 referring to liver weight loci 1-4 on chromosomes 8, 4, 12 and 13, respectively.

CONCLUSION

To our knowledge, this report presents, for the first time, the utilization of the CC for mapping QTL associated with baseline liver weight in mice. Our findings demonstrate that liver weight is a complex trait controlled by multiple genetic factors that differ significantly between sexes.

Association of a Cac8I polymorphism in the IGF1 gene with growth traits in Indian goats

The Insulin-like Growth Factor 1 (IGF1) gene is a member of somatotropic axis and plays a key role in proliferation of cells, mitosis, myogenesis, meiosis, differentiation in foetal development and post natal growth. The objectives of this study were to verify the single nucleotide polymorphisms (SNPs) in IGF1 gene and their association with growth traits in two indigenous native goat genetic groups of Kerala, viz., Malabari and Attappady Black. A total of 277 goats were genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using the restriction enzyme Cac8I. One SNP, A224G was detected in the 5′ non-coding region of the IGF1 gene, and accordingly two genotypes were revealed, GG and AG. This SNP was significantly associated with growth traits in Attappady Black goats, which is maintained as meat breed in Kerala. Results from this study demonstrated higher performance of GG animals for growth traits. The association of IGF1 gene with these traits emphasizes the importance of caprine IGF1 as a candidate gene for growth traits in goat breeding.

Ontogenic differences in sexual size dimorphism across four plover populations

Sexual size dimorphism (SSD) among adults is commonly observed in animals and is considered to be adaptive. However, the ontogenic emergence of SSD, i.e. the timing of divergence in body size between males and females, has only recently received attention. It is widely acknowledged that the ontogeny of SSD may differ between species, but it remains unclear how variable the ontogeny of SSD is within species. Kentish Plovers Charadrius alexandrinus and Snowy Plovers C. nivosus are closely related wader species that exhibit similar, moderate (c. 4%), male-biased adult SSD. To assess when SSD emerges we recorded tarsus length variation among 759 offspring in four populations of these species. Tarsus length of chicks was measured on the day of hatching and up to three times on recapture before fledging. In one population (Mexico, Snowy Plovers), males and females differed in size from the day of hatching, whereas growth rates differed between the sexes in two populations (Turkey and United Arab Emirates, both Kentish Plovers). In contrast, a fourth population (Cape Verde, Kentish Plovers) showed no significant SSD in juveniles. Our results suggest that adult SSD can emerge at different stages of development (prenatal, postnatal and post-juvenile) in different populations of the same species. We discuss the proximate mechanisms that may underlie these developmental differences.

Growth hormone and growth?

Pituitary GH is obligatory for normal growth in mammals, but the importance of pituitary GH in avian growth is less certain. In birds, pituitary GH is biologically active and has growth promoting actions in the tibia-test bioassay. Its importance in normal growth is indicated by the growth suppression following the surgical removal of the pituitary gland or after the immunoneutralization of endogenous pituitary GH. The partial restoration of growth in some studies with GH-treated hypophysectomized birds also suggests GH dependency in avian growth, as does the dwarfism that occurs in some strains with GHR dysfunctions. Circulating GH concentrations are also correlated with body weight gain, being high in young, rapidly growing birds and low in slower growing older birds. Nevertheless, despite these observations, there is an extensive literature that concludes pituitary GH is not important in avian growth. This is based on numerous studies with hypophysectomized and intact birds that show only slight, transitory or absent growth responses to exogenous GH-treatment. Moreover, while circulating GH levels correlate with weight gain in young birds, this may merely reflect changes in the control of pituitary GH secretion during aging, as numerous studies involving experimental alterations in growth rate fail to show positive correlations between plasma GH concentrations and the alterations in growth rate. Furthermore, growth is known to occur in the absence of pituitary GH, as most embryonic development occurs prior to the ontogenetic appearance of pituitary somatotrophs and the appearance of GH in embryonic circulation. Early embryonic growth is also independent of the endocrine actions of pituitary GH, since removal of the presumptive pituitary gland does not impair early growth. Embryonic growth does, however, occur in the presence of extrapituitary GH, which is produced by most tissues and has autocrine or paracrine roles that locally promote growth and development. The role of GH in avian growth is therefore still unclear.

Genetic architecture of body size in mammals

Much of the heritability for human stature is caused by mutations of small-to-medium effect. This is because detrimental pleiotropy restricts large-effect mutations to very low frequencies.

Genetic architecture of body size in mammals

Much of the heritability for human stature is caused by mutations of small-to-medium effect. This is because detrimental pleiotropy restricts large-effect mutations to very low frequencies.

Association of IGF-I gene polymorphisms with milk yield and body size in Chinese dairy goats

The association of IGF-I gene polymorphisms with certain traits in 708 individuals of two Chinese dairy-goat breeds (Guanzhong and Xinong Saanen) was investigated. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods were employed in screening for genetic variation. Two novel mutations were detected in the 5'-flanking region and in intron 4 of IGF-I gene, viz., g.1617 G > A and g.5752 G > C (accession D26119.2), respectively. The associations of the g.1617 G > A mutation with milk yield and the body size were not significant (p > 0.05). However, in the case of g.5752 G > C, Xinong Saanen dairy goats with the CG genotype presented longer bodies (p < 0.05). Chest circumference (p < 0.05) was larger in Guanzhong goats with the GG genotype. In Xinong Saanen dairy goats with the CC genotype, milk yields were significantly higher during the first and second lactations (p < 0.05). Hence, the g.5752 G > C mutation could facilitate association analysis and serve as a genetic marker for Chinese dairy-goat breeding and genetics.

Insulin-like growth factor type-1 receptor down-regulation associated with dwarfism in Holstein calves

Perturbations in endocrine functions can impact normal growth. Endocrine traits were studied in three dwarf calves exhibiting retarded but proportionate growth and four phenotypically normal half-siblings, sired by the same bull, and four unrelated control calves. Plasma 3,5,3'-triiodothyronine and thyroxine concentrations in dwarfs and half-siblings were in the physiological range and responded normally to injected thyroid-releasing hormone. Plasma glucagon concentrations were different (dwarfs, controls>half-siblings; P<0.05). Plasma growth hormone (GH), insulin-like growth factor-1 (IGF-1) and insulin concentrations in the three groups during an 8-h period were similar, but integrated GH concentrations (areas under concentration curves) were different (dwarfs>controls, P<0.02; half-siblings>controls, P=0.08). Responses of GH to xylazine and to a GH-releasing-factor analogue were similar in dwarfs and half-siblings. Relative gene expression of IGF-1, IGF-2, GH receptor (GHR), insulin receptor, IGF-1 type-1 and -2 receptors (IGF-1R, IGF-2R), and IGF binding proteins were measured in liver and anconeus muscle. GHR mRNA levels were different in liver (dwarfs<controls, P<0.002; dwarfs<half-siblings, P=0.06; half-siblings<controls, P=0.08) but not in muscle. IGF-1R mRNA abundance in liver in half-siblings and controls was 2.4- and 2.5-fold higher (P=0.003 and P=0.001, respectively) and in muscle tissue was 2.3- and 1.8-fold higher (P=0.01 and P=0.08, respectively) than in dwarfs. Hepatic IGF-1R protein levels (Western blots) in muscle were 2.5-fold higher (P<0.05) and in liver and muscle (quantitative immunohistochemistry) were higher (P<0.02 and P<0.07, respectively) in half-siblings than in dwarfs. The reduced presence of IGF-1R may have been the underlying cause of dwarfism in studied calves.

Hormonal and morphological study of the pituitaries in reeler mice

Reelin is a neuronal glycoprotein that plays a crucial role in brain layer formation during prenatal development. The reeler mutant mouse lacks Reelin, leading to abnormalities in the neuronal layering of cerebral cortex and cerebellum, producing ataxia, tremor and abnormal locomotion. Reeler mice are reported to have growth retardation and most of them are sterile or unable to bring up their newborns. Since the brain is one of the main regulator of pituitary hormone secretion and no information was reported regarding pituitary function and structure in these mutant mice, we studied pituitary endocrine activity and morphology in reeler mice. Mice were classified in three groups as reeler homozygote (RHM), reeler heterozygote (RHT) or control (CO). Pituitary hormone blood levels were assessed by enzyme immunoassay (EIA) and immunoradiometric assay (IRMA). Animals and their pituitaries were weighted and pituitaries were studied by histology, immunohistochemistry and electron microscopy. Results showed statistically significant differences in body weight and in adrenocorticotropic hormone (ACTH) and luteinizing hormone (LH) blood levels between the three groups. In contrast, growth hormone (GH) blood levels showed a high individual variation and no decrease in reeler groups compared with CO. Morphological studies revealed no differences in pituitary cell types except that somatotrophs appeared to be slightly smaller in RHM and RHT. Although it seems that pituitary hypofunction is not responsible for growth retardation, more studies are needed to obtain a deeper insight into the endocrine status of these mutant mice to elucidate the cause of their low body weight and reproductive behaviour.

Associations between single nucleotide polymorphisms in candidate genes and growth rate in Arctic charr (Salvelinus alpinus L.)

We tested for associations between single nucleotide polymorphisms (SNPs) in five candidate genes allied with the growth hormone axis and the age-specific growth rate of Arctic charr (Salvelinus alpinus L.: Salmonidae). Two large full sib families (N=217 and 95) were created by backcrossing males that were hybrids between two phenotypically divergent populations from Labrador, Canada and from Nauyuk Lake, Canada to females that were from Nauyuk Lake. Measures of individual growth rate (wet weight and fork length) were made three times during a 420-day period after the juveniles were transferred from 4 to 11 degrees C. We then identified SNP markers in 10 proposed candidate genes known to be related to the growth hormone axis. Comparative alignments of amino-acid sequences and nucleotide sequences from other fish species were used to design PCR primers that would amplify 0.5-3 kb DNA regions of the candidate genes. All the individuals in the two backcross families were genotyped for these SNP markers using either polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) or bidirectional amplification of specific alleles (Bi-PASA) approaches. A significant association between a particular SNP allele and early growth was found for the locus containing the growth hormone-releasing hormone and pituitary adenylate cyclase-activating polypeptide genes (GHRH/PACAP2, P=0.00001). We argue that using comparative sequence information to design PCR primers for candidate genes is an efficient method for locating quantitative triat loci in nonmodel organisms.

Linking hematopoiesis to endochondral skeletogenesis through analysis of mice transgenic for collagen X

Each skeletal element where marrow develops is first defined by a hypertrophic cartilage blueprint. Through programmed tissue substitution, the cartilaginous skeletal model is replaced by trabecular bone and marrow, with accompanying longitudinal tissue growth. During this process of endochondral ossification, hypertrophic cartilage expresses a unique matrix molecule, collagen X. Previously we reported that transgenic mice with dominant interference collagen X mutations develop variable skeleto-hematopoietic abnormalities, manifested as growth plate compressions, diminished trabecular bone, and reduced lymphatic organs (Nature 1993, 365:56). Here, histology and flow cytometry reveal marrow hypoplasia and impaired hematopoiesis in all collagen X transgenic mice. A subset of mice with perinatal lethality manifested the most severe skeletal defects and a reduction of marrow hematopoiesis, highlighted by a lymphocyte decrease. Thymic reduction is accompanied by a paucity of cortical immature T cells, consistent with the marrow's inability to replenish maturing cortical lymphocytes. Diminished spleens exhibit indistinct lymphatic nodules and red pulp depletion; the latter correlates with erythrocyte-filled vascular sinusoids in marrows. All mice display reduced B cells in marrows and spleens, and elevated splenic T cells. These hematopoietic defects underscore an unforeseen link between hypertrophic cartilage, endochondral ossification, and establishment of the marrow microenvironment required for blood cell differentiation.