Initial assessment of protein and amino acid digestive dynamics in protein-rich feedstuffs for broiler chickens.

A study evaluating apparent digestibilities of protein and amino acids and their corresponding digestion rates in four small intestinal sites in broiler chickens was completed to further investigate dietary optimisation via synchronised nutrient digestion and absorption. A total of 288 male Ross 308 broiler chickens were offered semi-purified diets with eight protein-rich feedstuffs, including; blood meal (BM), plasma protein meal (PPM), cold pressed (CCM) and expeller-pressed (ECM) canola meal, high (SBM HCP) and low (SBM LCP) crude protein soybean meals, lupins and peas. Diets were iso-caloric, iso-nitrogenous and the test ingredient was the sole source of dietary nitrogen. Each diet was offered to 6 bioassay cages with 6 birds per cage from day 21 to 28 post hatch. On day 28, all birds were euthanized and digesta samples were collected from the proximal jejunum, distal jejunum, proximal ileum and distal ileum to determine apparent protein and amino acids digestibility coefficients, digestion rates and potential digestible protein and amino acids. Dietary protein source significantly influenced energy utilisation, nitrogen retention, apparent protein (N) digestibilities, digestion rates and potential digestible protein along the small intestine. Diets containing BM and SBM LCP exhibited the highest protein digestion rate and potential digestible protein, respectively. Digestibility coefficients and disappearance rates of the majority of amino acids in four sections of the small intestine were influenced by dietary protein source (P < 0.01) and blood meal had the fastest protein digestion rate. In general, jejunal amino acid and protein digestibilities were more variable in comparison to ileal digestibilities, and the differences in protein and amino acid disappearance rates were more pronounced between types of feedstuffs than sources of similar feedstuffs.

Characterization of dopamine-dependent rewarding and locomotor stimulant effects of intravenously-administered methylphenidate in rats.

In general, psychostimulants are thought to exert rewarding and locomotor stimulating effects via increased dopamine transmission in the ventral striatum. However, little is known about the mechanisms underlying the effects of the stimulant drug methylphenidate. The present study examined the putative role of dopaminergic transmission in i.v. methylphenidate reward as measured by conditioned place preference. Rats were shown to exhibit conditioned place preference for i.v. methylphenidate (5 mg/kg, not 2 mg/kg). Administration of the dopamine receptor antagonist cis-flupenthixol (0.1-0.8 mg/kg i.p.), either during conditioning or on test day, dose-dependently attenuated the magnitude of the conditioned place preference. Finally, we examined the effects of bilateral 6-hydroxydopamine lesions of nucleus accumbens core, medial shell or anteromedial olfactory tubercle on the rewarding and locomotor stimulant effects of methylphenidate. Residual dopamine innervation, as assessed by radioligand binding to the dopamine transporter, revealed a significant association between core dopamine innervation and the locomotor stimulant effect of methylphenidate. However, neither core nor medial shell dopamine innervation was related to conditioned place preference magnitude. Instead, conditioned place preference magnitude was associated with dopamine innervation in the anteromedial olfactory tubercle. These results establish a role for dopaminergic transmission in both i.v. methylphenidate conditioned place preference and locomotor stimulation. As well, they suggest that different ventral striatal subregions mediate the rewarding (anteromedial olfactory tubercle) and locomotor stimulant (accumbens core) effects of methylphenidate.

Patient with a 22q11.2 deletion with no overlap of the minimal DiGeorge syndrome critical region (MDGCR).

The apparent lack of genotype/phenotype correlation in patients with the DiGeorge anomaly and velocardiofacial syndrome (DGA/VCFS; the "22q11 deletion syndrome") indicates a complex genetic condition. Most cases, whatever the phenotype, have a 1.5-3 Mb chromosomal deletion that includes the minimal DiGeorge critical region (MDGCR). Another potential critical region on 22q11 has been suggested based on two patients with distal deletions outside the MDGCR. We report on a patient with a VCFS phenotype who has a deletion, mapped by short tandem repeat polymorphic loci and fluorescence in situ hybridization analysis, distal to and not overlapping the MDGCR. This patient is deleted for several genes, including the T-box 1 gene (TBX1; a transcription regulator expressed early in embryogenesis) and catechol-O-methyltransferase (COMT; involved in neurotransmitter metabolism). We discuss the role these two genes may play in the clinical phenotype of the patient.

Mapping the distribution of the telomeric sequence (T2AG3)n in rock-wallabies, Petrogale (Marsupialia: Macropodidae), by fluorescence in situ hybridization. I. The penicillata complex.

The eight Petrogale (rock-wallaby) species of the penicillata complex have a variable rate of karyotypic evolution, with species differing from the ancestral karyotype by two to six rearrangements. The distribution of the predominant vertebrate telomeric sequence (T2AG3)n was examined by fluorescence in situ hybridization (FISH) to determine if this sequence is retained during centric fusion events or is involved in other rearrangements. In all submetacentric chromosomes derived by centric fusions, the telomeric sequence was identified at or near the centromere, indicating that the (T2AG3)n sequence is consistently retained. In two acrocentric chromosomes, derived by centromeric transpositions from submetacentric fusion chromosomes, an interstitial signal was observed at the presumed site of the fusion. This represents the identification of a novel mechanism by which the (T2AG3)n sequence may become interstitial. Other interstitial telomeric signals were identified just below the centromere of chromosome 1 and interstitially on chromosome 4 in all eight species of the penicillata complex. These may be related to, respectively, the formation of euchromatic short arms on chromosome 1 and a more ancient rearrangement of chromosome 4 within marsupials.

B-chromosome systems in the greater glider, Petauroides volans (Marsupialia: Pseudocheiridae). II. Investigation of B-chromosome DNA sequences isolated by micromanipulation and PCR.

B chromosomes, despite their common occurrence throughout the animal and plant kingdoms, have not been investigated extensively at the molecular level. While the majority of B chromosomes occurring in animals have been described as heterochromatic, only a few researchers have examined the DNA of these chromosomes beyond this gross cytological level. This is the case in the largest of the gliding marsupial possums, the greater glider, Petauroides volans. To examine the molecular composition and localization of B-chromosome DNA sequences in P. volans, a combination of micromanipulation and the polymerase chain reaction was used in this study to isolate and then amplify the DNA of the B chromosomes. Localization of the isolated B-chromosome sequences to metaphase chromosomes was investigated using fluorescence in situ hybridization. The B chromosomes in this species are shown to be composed of a heterogeneous mixture of sequences, some of which are unique to the B chromosomes, while others exhibit homology to the centromeric regions of the autosomal complement.

B-chromosome systems in the greater glider (Petauroides volans volans) (Marsupialia:Petauridae). I. B-chromosome distribution.

Variations in diploid chromosome number, due to the presence of B chromosomes, are found within the distribution of P. v. volans. B chromosomes vary in number between one and eight per animal, are mitotically stable in various body tissues and, unlike the Y chromosome in male P. v. volans, are not eliminated from bone marrow cells. Animals possessing B chromosomes have a distinct distribution, and it appears that a stable equilibrium between the forces of B chromosome accumulation or elimination is operating in those populations possessing these chromosomes.