Cytogenetic mapping of 31 functional genes on chicken chromosomes by direct R-banding FISH

Using direct R-banding fluorescence in situ hybridization, we determined the location of 31 functional genes on chicken chromosomes. Replication R-banded chromosomes were obtained by synchronizing splenocyte cultures with excessive thymidine, followed by BrdU treatment. Thirty-one functional genes were directly localized to banded chicken chromosomes using genomic DNA and cDNA fragments as probes. The possibility of conserved linkage homology between chicken and human chromosomes was demonstrated for seven chicken chromosome regions (1p, 1q, 2q, 4p, 4q, and 5q).     

Identification of differentially expressed genes involved in the regression and development of the chicken Müllerian duct

Müllerian ducts of male chickens undergo regression around day 12 of incubation, but the underlining mechanisms remain unclear. The purpose of this study was to identify factors that contribute to regression of the Müllerian duct in the chicken. We first employed annealing control primer-based RT-PCR to screen candidate genes differentially expressed in the Müllerian ducts between male and female. Four differentially expressed genes (MSX2, GAL10, VCP and PLCH1) were partially sequenced. The expression of mRNA of the latter genes and MSX1 in the male and female Müllerian ducts were compared at 7.5, 8 and 9 days of incubation using semi-quantitative RT-PCR. The results indicated that both MSX1 and MSX2 mRNA was highly expressed in the male Müllerian duct at day 9 of incubation, whereas, PLCH1 mRNA was lower in the male duct at day 9 of incubation compared to that of the female duct. Although VCP mRNA was expressed in both left and right female Müllerian ducts, no expression was detected in the male duct. Whole mount in situ hybridyzation analysis showed that the expression of MSX1 and MSX2 mRNA were localized specifically in the mesenchymal cells of the male Müllerian duct at day 9 of incubation. In contrast, VCP mRNA expression was observed in both mesenchymal and epithelial cells of the female Müllerian duct but not detected in the male duct. These results suggest that both up-regulation of MSX1 and MSX2 mRNA expression is involved in the regression of the Müllerian duct in male chicken embryo, whereas VCP expression is involved in development of the female duct.     

Identification of growth hormone DNA polymorphisms which respond to divergent selection for abdominal fat content in chickens

Summary Two strains of meat-type chickens which had been derived from the same genetic base, but were selected for high or low abdominal fat content, respectively, were analyzed for polymorphisms in the growth hormone gene (GH). A total of four DNA polymorphisms were identified, one at a SacI restriction site and three at MspI restriction sites. Restriction mapping indicated that all polymorphisms were in exons and/or introns and not in flanking regions of the gene. The incidence of GH polymorphisms was determined in 20 chickens from each strain and significant differences were observed for two of the four polymorphisms. Analysis by DNA fingerprinting using (CAC)₅ as a probe indicated that the inbreeding coefficient was 0.1 in both strains and that random genetic drift was minimal. Thus, the selection for abdominal fat appears to have affected the frequency of alleles of the growth hormone gene. Whether this is the direct consequence of an altered growth hormone gene on fat metabolism or reflects linkage to an allele of a neighbouring gene remains to be determined.     

Callose Synthase in Pinus sylvestris Response during Infection by Species of Heterobasidion annosum sensu lato with Varied Host Preferences

Strengthening of plant cell walls at the site of fungal entry is one of the earliest plant responses to fungal pathogens. The aim of our study was to characterize the pattern of callose synthase localization and callose deposition in roots of Pinus sylvestris after infection by species of the Heterobasidion annosum s.l. complex with different host specificity: H. annosum s.s., H. parviporum and H. abietinum. To address this, sense‐labelled probes and ribonuclease‐treated samples were used to determine in situ hybridizations of callose synthase by FISH method. Furthermore, determination of callose accumulation within P. sylvestris cells was carried out using aniline blue. The different species of H. annosum s.l. had distinct impacts on the callose synthase staining within plant tissues. Moreover, while inoculation with strains of H. abietinum resulted in callose synthase accumulation at the point of hyphae contact with the host cell, this was not observed with the other species. A significant difference in callose synthesis localization was observed after inoculation with varied species of H. annosum s.l. as a result of the specific interactions with the host.     

Quantification of prolactin messenger ribonucleic acid, pituitary content and plasma levels of prolactin, and detection of immunoreactive isoforms of prolactin in pituitaries from turkey embryos during ontogeny.

The content of prolactin mRNA as well as total prolactin content and type of isoforms of prolactin were measured in single pituitary glands from turkey embryos and poults. Levels of mRNA and pituitary content of prolactin remained low until 5 days before hatching, while plasma concentrations remained low until 2 days before hatching. Levels of prolactin mRNA then increased until the day of hatch, stayed stable during the 3 first days of age, and significantly increased until 2 wk of age. Similar changes were observed in pituitary content and plasma levels of prolactin. Two immunoreactive bands of apparent molecular masses of 24 and 27 kDa, corresponding to the nonglycosylated and glycosylated form of prolactin, respectively, were visualized on Western blots. In pituitary glands from embryos at 22 days of incubation, 31.5% of the protein was glycosylated, whereas in embryos at 27 days of incubation and poults at 1 and 7 days of age, 48.6%, 48.0%, and 56. 0% of prolactin was glycosylated, respectively. The results indicate that the increases in the synthesis and the release of prolactin occur mainly around and after the time of hatching in the turkey embryo. Higher percentages of glycosylated isoforms were associated with increasing levels of total prolactin in the pituitary gland. Thus, the synthesis of prolactin and its post-translational modifications may be important factors involved in the physiologic changes occurring around the time of hatching.     

A MspI polymorphism in the bovine ornithine decarboxylase gene and its possible association with selection for milk production in Holstein bulls

A polymerase chain reaction (PCR)-based method for detection of a MspI-restriction fragment length polymorphism (RFLP) in the bovine ornithine decarboxylase gene was developed, and the allele frequencies of the polymorphism in two groups of Holstein bulls representing progeny-tested bulls during the 1950s-1960s and 1980s, respectively, were estimated. The frequencies of the MspI(-) allele were 0.229 and 0.077 and that of MspI(+) were 0.771 and 0–923 in the progeny-tested bulls of the 1950s-1960s and 1980s, respectively. The difference in allele frequencies between the two groups was statistically significant (P< 0.005). Genetic drift could be responsible for the changes in allele frequencies; however, it could also be possible that selection for milk production was associated with the changes of the allele frequencies in the two bull populations.     

Avoiding transport bottlenecks in an expanding root system: Xylem vessel development in fibrous and pioneer roots under field conditions

? Premise of the study: Root systems develop to effectively absorb water and nutrients and to rapidly transport these materials to the transpiring shoot. In woody plants, roots can be born with different functions: fibrous roots are primarily used for water and nutrient absorption, whereas pioneer roots have a greater role in transport. Because pioneer roots extend rapidly in the soil and typically quickly produce fibrous roots, they need to develop transport capacity rapidly so as to avoid becoming a bottleneck to the absorbed water of the developing fibrous roots and, as we hypothesized, immediately activate a specific type of autophagy at a precise time of their development. ? Methods: Using microscopy techniques, we monitored xylem development in Populus trichocarpa roots in the first 7 d after emergence under field conditions. ? Key results: Newly formed pioneer roots contained more primary xylem poles and had larger diameter tracheary elements than fibrous roots. While xylogenesis started later in pioneer roots than in fibrous, it was completed at the same time, resulting in functional vessels on the third to fourth day following root emergence. Programmed cell death was responsible for creating the water conducting capacity of xylem. Although the early xylogenesis processes were similar in fibrous and pioneer roots, secondary vascular development proceeded much more rapidly in pioneer roots. ? Conclusions: Compared to fibrous roots, rapid development of transport capacity in pioneer roots is not primarily caused by accelerated xylogenesis but by larger and more numerous tracheary elements and by rapid initiation of secondary growth.     

Probing parentage in parasitic birds: an evaluation of methods to detect conspecific brood parasitism using goldeneyes Bucephala islandica and Bl. clangula as a test case

Conspecific brood parasitism (CBP) occurs in over 200 species of birds. Efforts to detect CBP have relied on either observational criteria, or more recently, on molecular methods. While molecular approaches are powerful, they are expensive, time consuming and may prove prohibitive for studies requiring estimates of CBP over large spatial and temporal scales involving hundreds of nests. We evaluated a series of observational methods that have been applied in previous studies to detect CBP, using two species of cavity‐nesting ducks, the Barrow's goldeneye Bucephala islandica and common goldeneye B. clangula, as test species. We first describe a method based on differences in egg morphology and find it to be a reliable method to detect CBP in both species in British Columbia, Canada. The application of recursive partitioning analysis was especially effective in classifying parasitized and non‐parasitized nests using differences in egg morphology. We then evaluated five additional observational criteria that have been used previously in several studies to detect CBP in birds. We show that considerable redundancy exists among all criteria, as expected, but no single method is effective at detecting all suspected cases of CBP. Subsets of criteria (2 or more eggs/d, eggs laid 2 or more days after incubation, and clutch sizes exceeding 12 eggs) were successful, in combination, in detecting 75% of parasitized nests for goldeneyes. Finally, we suggest that ecological and evolutionary analyses of the dynamics of CBP will require estimates of the frequency of the parasitic tactic in the population (rather than just the proportion of parasitized nests) and we provide a simple method to obtain such an estimate. Although our data are specific to goldeneyes, the techniques we used should have broad application to other studies of CBP.