Age Of Pigeons Research Articles

Near-Random Distribution of Chromosome-Derived Circular DNA in the Condensed Genome of Pigeons and the Larger, More Repeat-Rich Human Genome.

Extrachromosomal circular DNA (eccDNA) elements of chromosomal origin are known to be common in a number of eukaryotic species. However, it remains to be addressed whether genomic features such as genome size, the load of repetitive elements within a genome, and/or animal physiology affect the number of eccDNAs. Here, we investigate the distribution and numbers of eccDNAs in a condensed and less repeat-rich genome compared with the human genome, using Columba livia domestica (domestic rock pigeon) as a model organism. By sequencing eccDNA in blood and breast muscle from three pigeon breeds at various ages and with different flight behavior, we characterize 30,000 unique eccDNAs. We identify genomic regions that are likely hotspots for DNA circularization in breast muscle, including genes involved in muscle development. We find that although eccDNA counts do not correlate with the biological age in pigeons, the number of unique eccDNAs in a nonflying breed (king pigeons) is significantly higher (9-fold) than homing pigeons. Furthermore, a comparison between eccDNA from skeletal muscle in pigeons and humans reveals ∼9-10 times more unique eccDNAs per human nucleus. The fraction of eccDNA sequences, derived from repetitive elements, exist in proportions to genome content, that is, human 72.4% (expected 52.5%) and pigeon 8.7% (expected 5.5%).Overall, our results support that eccDNAs are common in pigeons, that the amount of unique eccDNA types per nucleus can differ between species as well as subspecies, and suggest that eccDNAs from repeats are found in proportions relative to the content of repetitive elements in a genome.

Posthatch development of intestinal morphology and digestive enzyme activities in domestic pigeons (Columba livia)

The gastrointestinal tract plays an important role in studies of avian ontogenies because of its key function in nutrient intake. The pattern of intestinal development during postnatal growth in domestic pigeons (Columba livia), as an altricial bird, would be different from the pattern observed in precocial poultry. In this study, the intestinal morphology, mucosal enzyme activities, and pancreatic enzyme activities were determined from hatch to 14 d of age in pigeons. Rapid morphological development was observed immediately after hatching. Villus area and crypt depth increased in parallel in the duodenum and jejunum and more slowly in the ileum. Mucosal enzyme activities per gram of duodenum, jejunum, and ileum varied significantly with segment and age. There were also intestinal segment × age interactions, in which enzyme activity increased most dramatically in the jejunum as compared with the duodenum and ileum for sucrase and maltase activity from day of hatch to 8 d, and for alkaline phosphatase activity through 14 d. However, aminopeptidase-N activity increased most dramatically from day of hatch to 3 d in the ileum as compared with the duodenum and jejunum. Changes in carbohydrate-digesting enzymes activity in duodenum, jejunum, ileum, and pancreas are more pronounced than for protein-digesting enzymes activity from 3 d after hatching. Intestinal total enzyme activities exhibited a steady increase, which was highly correlated with BW. Pancreatic enzymes indicated patterns somewhat similar to those for intestinal enzymes. It was concluded that development of the absorptive area and the capacity for hydrolysis in the duodenum, jejunum, and ileum was rapid immediately after hatching, although rates of development were different in the 3 segments. Young pigeons differ from poultry, in whom intestinal and pancreatic digestive enzyme activities per gram of tissue are generally constant or decline during postnatal development. Also, the data seem consistent with the idea that intestinal hydrolysis may be a determining step in digestion and hence growth.

Functional and morphological assessment of age-related changes in the choroid and outer retina in pigeons.

We sought to determine if choroidal and outer retinal deterioration occur with age in pigeons, as they do in other species, and investigated the relationship between age-related retinal and choroidal changes. In 64 pigeons ranging in age over the pigeon lifespan (0.5-20 years), we measured some or all among the following parameters: choroidal blood flow (ChBF) by laser Doppler flowmetry, choroidal thickness and choriocapillary vessel abundance by LM histology, choriocapillary endothelial cell transport specializations by EM histology, acuity by behavioral methods, and degenerating photoreceptor abundance and total photoreceptor abundance by LM histology. Regression and Receiver Operator Curve (ROC) analyses were used to characterize the pattern of age-related changes and determine the ages at or by which significant changes occurred. For the 45 birds for which we measured choroidal parameters, choriocapillary vessel abundance showed a curvilinear decline with age and half of this decline occurred by 3.5-4.6 years. The endothelial cell transport specializations called channels also declined curvilinearly with age. Choroidal thickness was slightly increased between the ages of 3-6 years, and thereafter declined steadily so that choroidal thickness in the oldest birds was half that in the youngest. ChBF showed an abrupt decline of about 20% at 4 years and a further 20% decline thereafter. In the 53 birds for which we obtained visual acuity and/or photoreceptor data, we observed a curvilinear decline in acuity (with half the decline having occurred by 8 years) and a prominent stepwise decline of about 20% in photoreceptor abundance at 4.7 years, followed by further decline thereafter. The period of major photoreceptor loss coincided with ages during which about 10% of photoreceptors appeared to show degenerative changes (4-8 years of age). Using partial correlation analysis with the common effect of age held constant, ChBF was found to have a positive correlation with acuity. Our results show that ChBF and choroidal vascularity decline significantly with age in pigeons, as do acuity and photoreceptor abundance. Our statistical analyses suggest that prominent choroidal vascular decline preceded the visual decline, and that there is a positive relationship between choroidal and visual functions. Thus, our findings are consistent with the view that age-related decline in choroidal function might contribute to age-related vision loss in pigeons.

The influence of magnets and habituation to magnets on inexperienced homing pigeons

72 young and old pigeons habituated to wearing either magnets or brass bars, half having had their bars changed, were released under an overcast sky. 1. No significant differences appear between birds habituated to magnet and those habituated to brass. 2. No significant differences appear between birds released with magnet and those released with brass. 3. Though youngs home worse than yearlings and old pigeons, no significant differences concerning the age of pigeons appears within, nor between experimental groups.