Culture System for Embryos of Blue-Breasted Quail from the Blastoderm Stage to Hatching

Skeletal development in blue-breasted quail embryos

The blue-breasted quail (Coturnix chinensis), the smallest species of quail with short generation interval and excellent reproductive performance, is a potential avian research model. A normal series of skeletal development of avian embryos could be served as a reference standard in the fields of developmental biology and teratological testing as well as in the investigation of mutation with skeletal abnormalities and in the study of the molecular mechanisms of skeletal development through genome manipulation. Furthermore, ossification sequence shows a species-specific pattern and has potential utility in phylogeny. However, data on the skeletal development of blue-breasted quail embryos are scarce. Here, we established a series of normal stages for the skeletal development of blue-breasted quail embryos. Cartilage and ossified bones of blue-breasted quail embryos were stained blue and red with Alcian blue 8GX and Alizarin red S, respectively. The time and order of chondrification and calcification of their skeletons were documented every 24 hr from 3 to 17 days of incubation, and a 15-stage series of skeletal development was created. Moreover, a comparative study with the Japanese quail (Coturnix japonica) demonstrated that ossification sequence differed significantly between these two species.

Developmental stages of the blue-breasted quail (Coturnix chinensis)

Chickens and Japanese quail (Coturnix japonica) have traditionally been the primary avian models in developmental biology research. Recently, the blue-breasted quail (Coturnix chinesis), the smallest species in the order Galliformes, has been proposed as an excellent candidate model in avian developmental studies owing to its precocious and prolific properties. However, data on the embryonic development of blue-breasted quail are scarce. Here, we developed a normal developmental series for the blue-breasted quail based on developmental features. The blue-breasted quail embryos take 17 days to reach the hatching period at 37.7°C. We documented specific periods of incubation in which significant development occurred, and created a 39-stage developmental series. The developmental series for the blue-breasted quail was almost identical to that for chickens and Japanese quail in the earlier stages of development (stages 1-16). Our staging series is especially useful at later stages of development (stages 34-39) of blue-breasted quail embryos as a major criterion of staging in this phase of development was the weight of embryos and the length of third toes.

Avian Biotechnology

Primordial germ cells (PGCs) generate new individuals through differentiation, maturation and fertilization. This means that the manipulation of PGCs is directly linked to the manipulation of individuals, making PGCs attractive target cells in the animal biotechnology field. A unique biological property of avian PGCs is that they circulate temporarily in the vasculature during early development, and this allows us to access and manipulate avian germ lines. Following the development of a technique for transplantation, PGCs have become central to avian biotechnology, in contrast to the use of embryo manipulation and subsequent transfer to foster mothers, as in mammalian biotechnology. Today, avian PGC transplantation combined with recent advanced manipulation techniques, including cell purification, cryopreservation, depletion, and long-term culture in vitro, have enabled the establishment of genetically modified poultry lines and ex-situ conservation of poultry genetic resources. This chapter introduces the principles, history, and procedures of producing avian germline chimeras by transplantation of PGCs, and the current status of avian germline modification as well as germplasm cryopreservation. Other fundamental avian reproductive technologies are described, including artificial insemination and embryo culture, and perspectives of industrial applications in agriculture and pharmacy are considered, including poultry productivity improvement, egg modification, disease resistance impairment and poultry gene "pharming" as well as gene banking.

Comparison of learning ability and memory retention in altricial (Bengalese finch, Lonchura striata var. domestica) and precocial (blue-breasted quail, Coturnix chinensis) birds using a color discrimination task

The present study sought to assess the potential application of avian models with different developmental modes to studies on cognition and neuroscience. Six altricial Bengalese finches (Lonchura striata var. domestica), and eight precocial blue-breasted quails (Coturnix chinensis) were presented with color discrimination tasks to compare their respective faculties for learning and memory retention within the context of the two developmental modes. Tasks consisted of presenting birds with discriminative cues in the form of colored feeder lids, and birds were considered to have learned a task when 80% of their attempts at selecting the correctly colored lid in two consecutive blocks of 10 trials were successful. All of the finches successfully performed the required experimental tasks, whereas only half of the quails were able to execute the same tasks. In the learning test, finches required significantly fewer trials than quails to learn the task (finches: 13.5 ± 9.14 trials, quails: 45.8 ± 4.35 trials, P < 0.05), with finches scoring significantly more correct responses than quails (finches: 98.3 ± 4.08%, quails: 85.0 ± 5.77% at the peak of the learning curve). In the memory retention tests, which were conducted 45 days after the learning test, finches retained the ability to discriminate between colors correctly (95.0 ± 4.47%), whereas quails did not retain any memory of the experimental procedure and so could not be tested. These results suggested that altricial and precocial birds both possess the faculty for learning and retaining discrimination-type tasks, but that altricial birds perform better than precocial birds in both faculties. The present findings imply that developmental mode is an important consideration for assessing the suitability of bird species for particular experiments.

Apportioning protein requirements for maintenance v. growth for blue-breasted quail (Excalfactoria chinensis) from 7 to 21 days of age

The aim of this study was to investigate protein requirements for the maintenance and growth of blue-breasted quail (Excalfactoria chinensis) from 7 to 21 days of age. A total of 180 quails, 7 days old, were randomly assigned to 36 cages and for 2 weeks were fed diets with a metabolisable energy concentration of 12.13 MJ/kg and a dietary CP concentration of 125, 150, 175, 200, 225 or 250 g/kg. The average BW per cage and the feed intake per cage were recorded daily. The results showed that quails fed 125 g/kg CP could not maintain their BW and had negative feed efficiency. There were linear and quadratic relationships between CP level and response criteria, including BW, weight gain, feed intake, feed efficiency, final body nitrogen mass and body nitrogen accretion (P<0.05). The dietary CP requirements, as calculated using a one-slope quadratic broken-line model, were 211 and 202 g/kg according to weight gain and feed efficiency, respectively. The regression equations, on the basis of metabolic BW, of daily weight gain on daily protein intake according to the model were Y=0.137-2.128(0.113-X) if X<0.113 and Y=0.137 if X>or=0.113 (R2=0.96, P<0.001), which meant that the protein requirement for maintenance was 0.049 times the metabolic BW and that to gain 1 g weight quails needed to ingest an extra 0.47 g protein after the maintenance requirement was satisfied. The regression equations, on the basis of metabolic BW, of daily body nitrogen accretion on daily protein intake according to the model were Y=5.667-76.700(0.119-X) if X<0.119 and Y=5.667 if X>or=0.119 (R2=0.95, P<0.001), which meant that quails had to receive an amount of protein equal to their metabolic BW multiplied by 0.045 to satisfy the requirement for maintenance and then ingest an extra 13 g protein to accrete 1 g body nitrogen. In conclusion, growth or protein accretion rates should be regulated according to dietary CP for specific experimental purposes via apportioning protein requirements for maintenance v. growth.

Japanese quail: an efficient animal model for the production of transgenic avians

The ability to generate transgenic mice has been a powerful tool in studying functional genomics, and much of our knowledge about developmental biology has come from the study of chicken embryology. Unfortunately, the availability of molecular genetic techniques, such as transgenics and knockouts, has been limited for developmental biologists using avian animal models. Efforts to develop a system for the rapid production of transgenic chickens have met with many obstacles, including high animal husbandry costs and long generational times. Recently, the Japanese quail has proven to be an excellent model organism for the production of transgenic avians using lentiviral vectors. The relatively small size of the adults, short time to sexual maturity, and prodigious egg production of the Japanese quail make development of transgenic lines less labor- and space-intensive compared to chickens. The high degree of homology between chicken and quail genomes allows researchers to design highly specific DNA constructs for the production of transgenic birds. In addition, transgenic quail offer all of the advantages of the classic avian developmental model system, such as the ability to readily produce quail:chick transplant chimeras. Finally, Japanese quail are ideal for in ovo imaging of embryos expressing fluorescent reporters introduced from a transgene and/or electroporation. Here, we provide detailed methods for generating transgenic quail using high-titer lentivirus.