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At least 73 records · Page 4Linked to original sources
PubMed1976

Anatomical and neurohistological observations on the heart of the rose ringed parakeet, Psittacula krameri.

Anatomy, histology and innervation of the heart of the rose ringed parakeet, Psittacula krameri have been studied in the present investigation. The sinuatrial node is found to be well-developed. It is located towards the right side of the cephalic end of the interatrial septum and composed of a few nucleated cells and a large fibrous mass. The atrioventricular node is poorly defined, present at the caudal end of the interatrial septum. The node is somewhat triangular in shape and is composed of elongated and multinucleated specialized fibres. The node is not covered by any connective tissue sheath. The poor development of the atrio ventricular node and the absence of any sheath around it may be correlated with the fast rate of the heart beat. The atrioventricular bundle is observed at the cephalic end of the interventricular septum. A branch from the right limb of the atrioventricular bundle is noted to pass directly into the right atrioventricular valve. The heart is richly innervated. Ganglion cells along with nerve fibres have been observed at the sulcus terminalis and the atrioventricular junction. A direct nervous connection could be observed between the sinuatrial and atrioventricular nodes. It is argued that the impulse which originates in the sinuatrial node would reach the atrioventricular node through the unspecialized muscle fibres and nerve fibres of the interatrial septum. Nerve cells could not be traced in the substance of the sinuatrial node, atrioventricular node and atrioventricular bundle.

Animals↗
PubMed1998

Parakeets, canaries, finches, parrots and lung cancer: no association.

The relationship between pet bird keeping and lung cancer according to exposure to tobacco smoking was investigated in a case-control study in hospitals of New York City and Washington, DC, USA. Newly diagnosed lung cancer cases (n = 887) aged 40-79 years were compared with 1350 controls with diseases not related to smoking, of the same age, gender and date of admission as the cases. The prevalence of pet bird keeping was 12.5% in men and 19.1% in women. There was no association between ever keeping a pet bird and lung cancer in never smokers (men adjusted odds ratio (OR) = 0.70, 95% confidence interval (CI) 0.15-3.17; women, 1.32, 95% CI 0.65-2.70), or in smokers and non-smokers combined, after adjustment for ever smoking (men: 1.28, 95% CI 0.88-1.86; women: 1.17, 95% CI 0.83-1.64; all: 1.21, 95% CI 0.95-1.56). Risk did not increase in relation to duration of pet bird keeping. Cases and controls kept similar types of birds. There was a tenfold increase of lung cancer risk associated with smoking among non-bird keepers (adjusted OR = 9.15). There was no indication of a synergism, either additive or multiplicative, between smoking and pet bird keeping with respect to lung cancer risk. Either alone or in conjunction with smoking, keeping parakeets, canaries, finches or parrots is not a risk factor for lung cancer among hospital patients in New York and in Washington, DC.

Animals↗
PubMed1974

Noise-induced threshold shift in the parakeet (Melopsittacus undulatus).

Parakeets exposed for 72 hr to a 1/3-octave band of noise centered at 2.0 kHz have a maximum threshold shift at 2.0 kHz with little or no spread of threshold shift to lower or higher frequencies. These results differ from those observed in mammals and suggest significant differences between avian and mammalian peripheral auditory processing.

Animals↗
PubMed2006

The pineal gland, but not melatonin, is associated with the termination of seasonal testicular activity in an annual reproductive cycle in roseringed parakeet Psittacula krameri.

The role of the pineal gland and its hormone melatonin in the regulation of annual testicular events was investigated for the first time in a psittacine bird, the roseringed parakeet (Psittacula krameri). Accordingly, the testicular responsiveness of the birds was evaluated following surgical pinealectomy with or without the exogenous administration of melatonin and the experimental manipulations of the endogenous levels of melatonin through exposing the birds to continuous illumination. An identical schedule was followed during the four reproductive phases, each characterizing a distinct testicular status in the annual cycle, namely, the phases of gametogenic quiescence (preparatory phase), seasonal recovery of gametogenesis (progressive phase), seasonal initiation of sperm formation (pre-breeding phase), and peak gametogenic activity (breeding phase). In each reproductive phase, the birds were subjected to various experimental conditions, and the effects were studied comparing the testicular conditions in the respective control birds. The study included germ cell profiles of the seminiferous tubules, the activities of steroidogenic enzymes 17beta-hydroxysteroid dehydrogenase (17beta-HSD), and Delta(5)3beta-hydroxysteroid dehydrogenase (Delta(5)3beta- HSD) in the testis, and the serum levels of testosterone and melatonin. An analysis of the data reveals that the pineal gland and its hormone melatonin may play an inhibitory role in the development of the testis until the attainment of the seasonal peak in the annual reproductive cycle. However, in all probability, the termination of the seasonal activity of the testis or the initiation of testicular regression in the annual reproductive cycle appears to be the function of the pineal gland, but not of melatonin.

Animals↗
PubMed1991

Thalassornectes (Alcidectes) aukletae, new subgenus and species (Acari: Hypoderatidae) from the crested and parakeet auklets (Aves: Charadriiformes; Alcidae).

In the genus Thalassornectes, a new subgenus, Alcidectes, and a new species, T. (Alcidectes) aukletae, are described from deutonymphs in the subcutaneous adipose tissue of the crested auklet, Aethia cristatella (Pallas), and the parakeet auklet, Cyclorrhynchus psittacula (Pallas), from the eastern Pacific USSR. The new subgenus and species differ from one or both of the single species in each of the other two subgenera, Thalassornectes and Rallidectes, by (1) the normal size, position, and parallel arrangement of the genital papillae; (2) the larger size of seta sce; (3) the greater length and stronger development of setae sci, d1, l1, h, and sh; (4) the equal size of tarsi III and IV or their size subequal, with tarsus IV slightly longer than tarsus III; (5) both epimera I and sternum well developed and nearly equal in length; and (6) the free sclerotized posteriad extension from epimerite II on the ventral cuticular surface. This is the first hypoderatid reported from the host order Charadriiformes. The distribution of T. (Alcidectes) aukletae among auklets may be attributed to either cospeciation or may have an ecological basis; data are insufficient at present to sustain either hypothesis.

Animals↗
PubMed1999

Epichlorohydrin induced biochemical changes in the rose-ringed parakeet, Psittacula krameri Scopoli.

Intraperitoneal administration of epichlorohydrin (ECH) at the dose level of 20 and 50 mg/kg body weight inhibited spermatogenesis in the testis of parakeet during breeding season. A total load of 60 mg/kg body weight of ECH given on 3 consecutive days proved to be lethal. Testicular proteins, nucleic acids (DNA and RNA), phospholipids and acid phosphatase activity were decreased, while the lipids, total cholesterol and alkaline phosphatase activity increased after ECH administration. The results suggest that the testicular atrophy caused by ECH was associated with an alteration in the activities of macromolecules and enzymes related to specific events of spermatogenesis.

Animals↗
PubMed2004

Molecular systematics in Aratinga parakeets: species limits and historical biogeography in the 'solstitialis' group, and the systematic position of Nandayus nenday.

The parrot genus Aratinga comprises 20 species that can be separated, based on morphological characters, in at least three distinct groups. We performed a phylogenetic analysis based on mtDNA sequences of individuals belonging to the solstitialis group with the objectives of: (1) assessing the genetic differences among individuals in order to clarify their specific status; (2) testing the monophyly of the group and establishing its phylogenetic position relative to other Aratinga species, (3) making inferences about temporal and geographical patterns of diversification in the Neotropics. As a result of the analysis, the three taxa belonging to the Aratinga solstitialis complex were found to be diagnosable phylogenetic species, the monotypic genus Nandayus was found to be included in the solstitialis group and the non-monophyly of the genus Aratinga was confirmed. Most of the speciation events occurred during the Pliocene and Pleistocene and may be related to habitat shifts associated to climate oscillation during these periods.

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