Production of chicken progeny (Gallus gallus domesticus) from interspecies germline chimeric duck (Anas domesticus) by primordial germ cell transfer

The present study aimed to investigate the differentiation of chicken (Gallus gallus domesticus) primordial germ cells (PGCs) in duck (Anas domesticus) gonads. Chimeric ducks were produced by transferring chicken PGCs into duck embryos. Transfer of 200 and 400 PGCs resulted in the detection of a total number of 63.0 ± 54.3 and 116.8 ± 47.1 chicken PGCs in the gonads of 7-day-old duck embryos, respectively. The chimeric rate of ducks prior to hatching was 52.9% and 90.9%, respectively. Chicken germ cells were assessed in the gonad of chimeric ducks with chicken-specific DNA probes. Chicken spermatogonia were detected in the seminiferous tubules of duck testis. Chicken oogonia, primitive and primary follicles, and chicken-derived oocytes were also found in the ovaries of chimeric ducks, indicating that chicken PGCs are able to migrate, proliferate, and differentiate in duck ovaries and participate in the progression of duck ovarian folliculogenesis. Chicken DNA was detected using PCR from the semen of chimeric ducks. A total number of 1057 chicken eggs were laid by Barred Rock hens after they were inseminated with chimeric duck semen, of which four chicken offspring hatched and one chicken embryo did not hatch. Female chimeric ducks were inseminated with chicken semen; however, no fertile eggs were obtained. In conclusion, these results demonstrated that chicken PGCs could interact with duck germinal epithelium and complete spermatogenesis and eventually give rise to functional sperm. The PGC-mediated germline chimera technology may provide a novel system for conserving endangered avian species.     

Duck plague in gnotobiotic ducks

Four-week-old gnotobiotic and conventional ducks were inoculated orally with duck plague virus. Both groups of ducks died on the third and fourth day after inoculation. Gross and microscopic lesions of duck plague were similar in gnotobiotic and conventional ducks, indicating the synergistic action of species of Salmonella and Pasteurella was not essential for development of lesions.     

Effect of photoperiod on the incorporation of 3H-thymidine into the gonads of Carassius auratus

Gldfish, Carassius auratus of varying sizes were conditioned in continuous light or darkness f or 10, 20 and 30 days and the incorporation of ³H-thymidine into the gonads was investigated to attempt to develop a bioassay for fish gonadotropins.
The 24-hour gonadal ³H-thymidine of 10-day conditioned fish was significantly less at the dose level of 0.5 μCi ³H-thymidine/fish compared to 1.0, 2.0 and 3.0 μCi/fish which gave gonadal activities not significantly different from each other. Thus, for all subsequent work the dose of 1.0 μCi/fish was used.
Photoperiod of continuous light or darkness had little effect on fish weighing less than 11 g but in fish 11-15 g conditioned for 20 days in darkness and fish greater than 16 g conditioned for 10 days in darkness, depression in gonadal ³H-thymidine incorporation occurred. In fish 11-15 g, prolonged conditioning for 30 days in darkness induced more gonadal activity than was observed at 20 days.
The effect of injection of Channa striatus pituitary extract at doses of 1 mg/10 g body weight and 5 mg/10 g body weight induced a significant increase in ³H-thymidine incorporation in the gonads over saline injected controls. The results suggest the potential of using photoperiod as a means of inducing regression of gonads of suitable fish in a bioassay of gonadotropins.     

Testicular prolactin receptors and serum growth hormone in golden hamsters: effects of photoperiod and time of day

Investigations were conducted to determine effects of exposure to short photoperiod--with its accompanying reductions in serum prolactin (Prl) concentrations--for various durations on testicular Prl receptors. An additional study investigated the possibility of nyctohemeral fluctuations in testicular Prl receptors and serum growth hormone (GH) concentrations and their alteration by photoperiod. After 10 and 28 days of exposure to a short photoperiod consisting of 5 h of light and 19 h darkness (5L:19D) (and prior to changes in testicular weight), there were progressive and significant reductions in the concentration of testicular Prl receptors (fmol/mg protein) when compared with long-photoperiod controls (14L:10D). After 12 weeks of 5L:19D, when testicular weights were dramatically decreased, Prl receptor concentration was reduced to 39% of long-photoperiod controls in one study, without alteration of affinity of Prl receptors for their labeled ligand. When measured at 6-h intervals in hamsters on 14L:10D, and on 5L:19D for 12 weeks, there were no significant changes in concentration or total content (fmol/testes) of testicular Prl receptors throughout the day. Although serum GH concentrations fluctuated markedly in hamsters on both photoperiods, no definitive nyctohemeral patterns were detected. These data provide indirect evidence for the ability of Prl to regulate its own testicular receptors, and demonstrate that diurnal fluctuations in testicular sensitivity to injected Prl are not a consequence of changes in Prl receptors. The data also suggest the absence of effects of photoperiod on serum GH concentrations in male golden hamsters.     

Mottled ducks,feral mallards,and their hybrids in Florida

The nonmigratory and endemic Florida mottled duck (Anas fulvigula fulvigula) is facing conservation threats from the combined effects of urbanization and introgressive hybridization with feral mallards (Anas platyrhynchos) and mallard x mottled duck hybrids. In the past, the status of the Florida mottled duck population was assessed during annual aerial surveys and most brown ducks (mottled ducks, mallards, and hybrids of them) detected during the survey would have been mottled ducks. But the release of domesticated mallards for aesthetic purposes has led to increases in the prevalence of mallards-hybrids (mallards or mallard x mottled duck hybrids) throughout peninsular Florida, USA, and because it is impossible to differentiate among mottled ducks, female mallards, and hybrids during aerial surveys, helicopter surveys were halted in 2009 until state researchers could conduct a range-wide study to determine what proportion of brown ducks are mottled ducks versus mallards-hybrids. We used plumage keys and high-resolution photography to categorize brown ducks from 557 wetland grid points as either mottled ducks or mallards-hybrids. Of the 5,179 brown ducks categorized, 40.1% were mottled ducks and 59.9% were mallards-hybrids. We used logistic regression analysis to model the interactive effect of a site's latitude and level of urbanization (urban gradient value within a 2-km buffer) to generate a predictive raster surface (1-km resolution) of the study area with values corresponding to the probability that a brown duck observed within a cell is a pure mottled duck. Predicted values will be used as correction factors when estimating final mottled duck population abundance from brown-duck survey data. Additionally, the predictive raster surface will be used to identify wetlands where mottled ducks remain predominant so that these sites can be targeted for preservation. Overall, mallards-hybrids outnumbered mottled ducks throughout most of peninsular Florida, especially in more urbanized regions, and their current prevalence rate presents a serious conservation threat, via hybridization, to extant mottled duck populations.     

Ontogenetical development of the chick and duck subcommissural organ. An immunocytochemical study

The ontogenetical development of the subcommissural organ (SCO) was investigated in chick embryos collected daily from the 1st to the 21st day in incubation. Some duck embryos, and adult chickens and ducks were also studied. Immunocytochemistry using an anti-Reissner's fiber (RF) serum as the primary antibody was the principal method used. In the chick embryos the events occurring at different days of incubation were: day 3 morphologically undifferentiated cells in the dorsal diencephalon displayed immunoreactive material (IRM); days 4 to 6 immunoreactive cells proliferated, formed a multilayered structure and developed processes which traversed the growing posterior commissure and ended at the brain surface; day 7 blood vessels penetrated the SCO, scarce hypendymal cells appeared, the first signs of ventricular release of IRM were noticed, appearance of IRM bound to cells of the floor of the Sylvius aqueduct; day 7 to 10 the number of apical granules and amount of extracellular IRM increased progressively; day 11 RF was observed along the Sylvian aqueduct, day 12 RF was present in the lumbar spinal cord; day 13 IRM on the aqueductal floor disappeared; days 10 to 21 hypendymal cells proliferated, developed processes and migrated dorsally, ependymal processes elongated and their endings covered the external limiting membrane. In adult specimens the ependymal cells lacked basal processes and the external membrane was contacted by hypendymal cells. the duck SCO appears to follow a similar pattern of development.     

Genetic studies facilitated management decisions on the invasion of the ruddy duck in Europe

The ruddy duck (Oxyura jamaicensis), a stifftail native to the Americas, was introduced to the UK in the 1950s and has since been recorded in 22 western Palearctic countries. By 2000, the UK population peaked at nearly 6,000 individuals. In 1991, hybridisation with the native and globally threatened (IUCN Endangered) white-headed duck (Oxyura leucocephala), a stifftail restricted to the Mediterranean and Asia, was recorded in Spain and culling of hybrids and ruddy ducks began. Here we report on a series of genetic studies that have enabled and supported management decisions to the benefit of the white-headed duck. First, genetic data confirmed that these are two distinct species, each of which is more closely related to other stifftail species. Second, molecular studies indicated that ruddy ducks in Spain, Iceland and elsewhere in Europe were of captive origin and not descendants from vagrants from their native North America. Third, genetic methods were used to distinguish among different hybrid generations in Spain and detected no ruddy duck introgression in birds identified morphologically as white-headed ducks. Collectively, these results supported management decisions to eradicate ruddy ducks from Europe. Subsequently, a control programme reduced the UK population by over 95 % by 2010, and the arrival of ruddy ducks to Spain decreased from 21 birds in 2003 to two sightings in 2010–2011. However, increased efforts to control small ruddy duck populations elsewhere in Europe and Morocco are still required to ensure conservation of the white-headed duck. This case of invasion by hybridization demonstrates that successful control is feasible given early detection followed by a rapid response plan; it also shows the contribution of research to management and that to guarantee the conservation of an endangered native species action may be required in countries outside its distribution range.     

Possible waterborne transmission and maintenance of influenza viruses in domestic ducks.

Two duck farms in Hong Kong were examined monthly for 1 year for the occurrence and persistence of influenza viruses within the duck communities. The predominant virus in one community was H3N2, a virus antigenically related to the pandemic Hong Kong strain. This virus was isolated monthly throughout the year from feces or pond water or both, indicating a cycle of waterborne transmission. Viruses of the same antigenic combination were isolated 1 and 2 years after the last sampling occasion, implying persistence in the community. Infection was asymptomatic. Maintenance of virus appeared to be dependent upon the continual introduction of ducklings susceptible to infection onto virus-contaminated water; the feces of ducks 70 to 80 days old were generally free of detectable virus despite the exposure of the ducks to virus in pond water. In the second community, in which ducklings were not introduced after the initial sampling, the prevailing viruses, H7N1 and H7N2, also present asymptomatically, ceased to be detected once the ducks were 70 to 80 days old. The normal practice of raising ducks of different ages on the same farm, wherein the water supplies are shared, as typified by the first community, appears to be instrumental in maintaining a large reservoir of influenza viruses in the duck population of southern China.     

Feeding ecology of the diving ducks pochard (Aythya ferina), tufted duck (A. fuligula), scaup (A. mania) and goldeneye (Bucephala clangula) overwintering on Lough Neagh, Northern Ireland

1. The diets of pochard (Aythya ferina), scaup (A. marila) and goldeneye (Bucephala clangula) overwintering on Lough Neagh are dominated by chironomid larvae, while molluscs are more important in that of tufted duck (A. fuligula). 2. Inshore areas of Lough Neagh offer poor feeding conditions for these diving ducks because chironomid larvae and molluscs are of small individual body size or low abundance. These factors lead to all four ducks foraging at least in part at depths greater than those usually exploited. 3. Due to their common consumption of molluscs, the diet of tufted duck shows a higher overlap with that of an introduced roach (Rutilus rutilus) population than with any other duck or fish species. 4. The feeding ecology of tufted duck and roach in Lough Neagh may form an example of distant competition and be at least partly responsible for recent fluctuations in the numbers of tufted duck.     

Expression of Insulin-Like Growth Factor System Genes in Liver Tissue During Embryonic and Early Post-Hatch Development in Duck (Anas platyrhynchos Domestica)

The IGF system is one of the most important endocrine and paracrine growth factor systems that regulate fetal and placental growth, whereas the liver is the principal source of circulation IGF-I. In the present study, expression of IGF-I, IGF type-I receptor (IGF-IR), and IGF binding protein (IGFBP)-3 genes was quantified by RT-PCR in the liver tissue on days 13, 17, 21, 25, and 27 of embryonic development, as well as at 7 days post-hatching (PH) in meat-type Gaoyou ducks and egg-type Jinding ducks. The results showed that IGF-I mRNA could be detected as early as on E 13d, but the expression level was low throughout embryonic development before increasing dramatically by E 27d and 7 days PH in both duck breeds. However, Gaoyou ducks exhibited higher IGF-I mRNA level than Jinding ducks, and the differences were significant on E 13d, E 21d, and at 7 days PH. Expression of IGF-IR in liver increased gradually in the former stages of the embryonic development, reaching its highest point on E 21d, and then declined up until 7 days PH. The expression pattern of IGFBP-3 gene was similar to that of IGF-IR gene, increasing significantly from E 17d. The expression peak appeared on E 25d, then declined significantly just prior to hatching (day 27) and was followed by an increase at 7 days PH. In general, the expression level of IGF-IR and IGFBP-3 genes in Jinding ducks was higher than that in Gaoyou ducks. Inverse relationships were observed for the expression of IGF-I and IGF-IR, and IGF-I and IGFBP-3, whereas a positive relationship was observed for the expression of IGF-IR and IGFBP-3. Our data indicate a differential expression of selected genes that comprise the IGF system in the duck liver tissue during embryonic and early PH growth and development.     

鸭生长激素基因内含子2、3多态性分析

根据鸭生长激素基因内含子2、3的序列设计5对引物,利用PCR-SSCP方法对北京鸭、西湖野鸭、金定鸭、山麻鸭、荆江鸭、绍兴鸭等6个鸭品种进行了单核苷酸多态性分析, 并检测其多态性。结果共发现8个突变位点, 其中内含子2有7个: 2593处C-T, 2770处G-A, 2813处T-A, 2829处C-A, 2894处C-T, 2896处T-C,3100处C-G; 内含子3有1个: 3270处A-G。统计结果显示, 这8个变异位点的基因型频率分布与品种有关, 在这些基因座的变异水平上, 北京鸭和绍兴鸭表现出了相当的品种保守性, 本研究所检测到的这些基因座可能与鸭的生产性能有关。     

Comparative expression of laminin and smooth muscle actin in the testis and epididymis of poultry and rabbit

The present investigation was conducted to demonstrate laminin and α smooth muscle actin (αSMA) in the testis and epididymis of adult chickens, Sudani ducks, pigeons, and rabbits. This study may represent the first indication for the presence of laminin in the male reproductive organs of birds and rabbits and might therefore serve as a milestone for further reports. In the testis of chicken, Sudani duck, pigeon, and rabbit, the laminin was localized in the basal lamina of the seminiferous tubules and of the peritubular myoid cells, in the testicular capsule and to a small extent in the vicinity of Leydig cells. The testicular vasculature also exhibited intense laminin immunostaining. Weak laminin staining was additionally seen in the cytoplasm of the duck Sertoli cells. In the epididymis, the basal lamina of the epididymal epithelium showed a distinctly positive reaction in all birds and rabbit. The basal lamina of the periductal myoid cells also showed a positive reaction. In the interductal tissue, laminin immunostaining was particularly observed in chicken, duck and pigeon. Laminin positive reaction was also seen in the epididymal vasculatures of all birds and rabbit. Interestingly, weak to moderate laminin staining was observed in the apical surface of the ciliated cells of the proximal and distal efferent ductules in chicken, duck and pigeon. αSMA positive reaction was seen in the testicular capsule and in the peritubular myoid cells of all birds and rabbit. In the testicular capsule, αSMA staining was either observed in the inner portion (chicken) or throughout the tunica albuginea (Sudani duck and pigeon), or in the outer aspect (rabbit). Distinct αSMA reaction was additionally observed in the testicular vasculature. In the epididymis of all birds and rabbit, the αSMA was particularly seen in the periductal and interductal myoid cells as well as in the epididymal vasculatures. No αSMA specific staining was however detected in the epididymal epithelium, fibrous lamina propria, and luminal spermatozoa of all birds and rabbits. In conclusion, the distribution of laminin and αSMA in the testis and epididymis might point out to their roles in the male reproduction.     

Immunohistochemical evidence for 11beta-hydroxylase (P45011beta) and androgen production in the gonad during sex differentiation and in adults in the protandrous anemonefish Amphiprion clarkii

To obtain basic information on the endocrine mechanisms underlying sex change in the protandrous anemonefish Amphiprion clarkii, we examined the immunolocalization of the steroidogenic enzyme cytochrome 11beta-hydroxylase (P45011beta), which is involved in 11-ketotestosterone (11-KT) production, and analyzed the ability of gonads to produce steroid hormones throughout the sex differentiation process and at the breeding stage. Immunopositive reactions against P45011beta appeared in sexually undifferentiated gonads at 30 days post hatching (dph). The number of immunopositive cells continued to increase during ovarian differentiation (from 60 to 180 dph) and throughout the formation of ambisexual gonads with both ovarian and testicular tissue until 270 dph. In the male phase, strongly immunopositive cells were observed in the cellular interstices of both testicular and ovarian tissues. P45011beta was localized only in the theca cells enclosing developed oocytes in the female phase. In-vitro 11-KT production in the gonads gradually increased with testicular differentiation (before, during, and after differentiation). Production of 11-KT in the gonads was higher in the male phase than during testicular differentiation or in the female phase. Our results suggest that androgen is involved in testicular differentiation during sex differentiation and spermatogenesis.     

Postcatastrophe Population Dynamics and Density Dependence of an Endemic Island Duck

ABSTRACT Laysan ducks (Anas laysanensis) are restricted to approximately 9 km² in the Northwestern Hawaiian Islands, USA. To evaluate the importance of density dependence for Laysan ducks, we conducted a Bayesian analysis to estimate the parameters of a Gompertz model and the magnitude of process variation and observation error based on the fluctuations in Laysan duck abundance on Laysan Island from 1994 to 2007. This model described a stationary distribution for the population at carrying capacity that fluctuates around a long-term mean of 456 ducks and is between 316 to 636 ducks 95% of the time. This range of expected variability can be used to identify changes in population size that warn of catastrophic events. Density-dependent population dynamics may explain the recovery of Laysan duck from catastrophic declines and allow managers to identify population monitoring thresholds.     

A technique for liver biopsy performed in Pekin ducks using anesthesia with Telazol.

Infection of Pekin ducks with duck hepatitis B virus is a useful model for studying the hepadenoviruses, of which human hepatitis B virus is the prototype. The utility of this model has been limited, however, by the difficulties associated with anesthetizing and obtaining liver biopsies from ducks. We developed a technique using Telazol (13 mg/kg) to anesthetize ducks before surgical biopsy of the liver in ducks infected with duck hepatitis B virus. Eight Pekin ducks infected with duck hepatitis B virus underwent serial biopsies at 4- to 5-week intervals. There was one perioperative death in 34 surgical procedures with no evidence on intra-abdominal sepsis or wound complications. Telazol can be used safely and humanely to anesthetized ducks without the need for general endotracheal anesthesia.     

Propagation of vaccine strain of duck enteritis virus in a cell line of duck origin as an alternative production system to propagation in embryonated egg

Duck virus enteritis (DVE) also known as duck plague, is a viral infection of ducks caused by duck enteritis virus (DEV). The control of the disease is mainly done by vaccination with a chicken embryo-adapted live virus that is known to be poorly immunogenic and affords partial protection. Further, the risk of harboring other infectious agents in the embryo particularly the deadly and zoonotic avian influenza virus is also high. In this paper, we report propagation of a chicken embryo-adapted vaccine strain of duck enteritis virus in duck embryo fibroblast (DEF) cell line. Thirty serial passages were done in DEF cell that made the vaccine virus further attenuated which was tested in ducks. The growth behaviors of the virus in DEF cells were studied and at 30th passage level the virus titre was found to be 10^6.8 TCID₅₀/ml. Ducks were immunized with this virus and challenged after 21 days with high dose of virulent DEV. All the immunized ducks withstood challenge with no clinical symptoms in any of the ducks while all the control ducks died. DEF cell which is free from other infectious agents appears to be a good system for cultivation of duck enteritis virus vaccine strain.     

Long day photoperiods and temperature of 20 degrees C induce spermatogenesis in blinded and non-blinded marbled newts during the period of testicular quiescence

Adult male marbled newts (Triturus marmoratus) were collected at the end of the spermatogenesis period and exposed to different photoperiods (natural-daylength-simulated photoperiod, total darkness, 8L:16D, 12L:12D, 16L:8D, and continuous light) for 3 mo. Temperature was maintained at 20 degrees C. Two additional groups of newts were blinded and exposed to either the natural-simulated photoperiod and to 16 h of light per day respectively. Quantitative histologic studies on testicular development and germ cell volume per testis were performed. The newts captured in the field at the beginning (initial controls) or at the end of the experiments (final controls) were in the period of testicular quiescence. Newts kept in total darkness or exposed to a short photoperiod (8L:16D) showed germ cell development up to primary spermatocytes, whereas germ cell development in the newts exposed to long photoperiods (12L:12D or 16L:8D) progressed to elongated spermatids. The newts exposed either to intermediate photoperiods (natural-simulated photoperiod) or to constant light showed an intermediate degree of germ cell development (up to round spermatids). No significant differences between non-blinded and blinded animals were found. These results suggest that (1) mild temperature initiates testicular development in the period of testicular quiescence, (2) long photoperiods associated with mild temperatures produce spermatogenesis in this period, (3) complete darkness or constant light are less effective than some intermediate photoperiod, and (4) the effect of photoperiod on testicular function in newts is not related to ocular photoreception.     

Chronobiologic study in the domestic duck. II. Physiological mechanism of the chronobiologic action of visible light on the gonads of the male duck

1. The physiological mechanism of the gonad-stimulant effect of light rays on the pre-pubertal duck testis, is the basis of any chronobiolgical study of this effect. 2. The light stimulates the chain formed by the retina, the optic nerve, the hypothalamus and the anterior part of the pituitary. This chain includes 2 photo-receptors, a superficial one, the retina and a deep one, the hypothalamus. The retina is here only sensitive to orange and red rays. Consequently an autonomic retina intervenes instead of the visual retina. The hypothalamus, on the other hand, is sensitive to all visible rays when they are brought directly in contact with it through a quartz rod placed in the orbit which has been previously emptied. 3. The hypothalamus, which is thus enlightened directly is more than a hundred times more sensitive than the retina. This great sensitivity allows normal stimulation by the most penetrating rays in the orbital region. 4. Ultra-violet and infra-red rays are inactive on the autonomic retina and on the hypothalamus. 5. The neuro-secretory cells of the latter, stimulated directly or indirectly, secrete hormones which via the axones reach a capillary network covering the median eminence, then, by series of portal veins, the anterior part of the pituitary, the corresponding cells of which secrete various hormones, which through the systemic circulation reach the corresponding target organs and in particular the gonads. It is thus a neuro-hormonal mechanism which the external factor light, brings into play to stimulate various functions of the autonomic life of the organism.     

“双季稻-鸭”共生生态系统稻作季节氮循环

“稻鸭共生”是对我国传统农业稻田养鸭的继承与发展.2010年5-10月在长江流域双季稻主产区湖南布置了稻田养鸭田间试验,以常规稻作为对照,研究了早、晚稻两季“稻鸭共生”生态系统氮(N)循环特征.结果表明：“早稻-鸭”共生系统N输出是239.5 kg·hm^-2,其中鸭产品N是12.77 kg·hm^-2.“晚稻-鸭”共生系统N输出是338.7 kg·hm^-2,其中鸭产品N是23.35 kg·hm^-2.在早、晚稻两季,“稻鸭共生”系统在目前的N养分投入水平下,土壤均存在N亏缺;鸭子系统N输入主要来自系统外投入的饲料N;鸭粪N作为系统内被循环利用的养分,早、晚稻两季循环率分别为2.5%和3.5%.两季稻作后,土壤截存的N量是178.6 kg·hm^-2.