Why budgerigars breed in continuous darkness

Budgerigars ( Melopsittacus ) exposed to male vocalizations will breed in total darkness, and the possibility arises that darkness is stimulatory. The present experiments showed that the availability of a nest-box accelerates egg-laying, and that relative darkness is an important property of a nest-box. Furthermore in the absence of a nest-box breeding occurs sooner in continuous darkness than on 14 L: 10 D. Intermittent periods of darkness imposed in the light period of a 14 L: 10 D regime accelerate egg-laying somewhat.     

The three syndromes of fat embolism: pulmonary manifestations.

The clinical course and radiographs of 30 patients with fat embolism syndrome were reviewed. In all cases the classic triad of neurologic dysfunction, respiratory insufficiency, and petechiae were present. Three responses to embolized fat were noted. The hyperacute response was seen in two patients with paradoxical embolization of fat to the systemic circulation. A "classic response" was noted in 18 patients with transient respiratory compromise and variable radiographic findings. The two deaths in the group responding in the classical manner were attributed to massive pulmonary emboli. The third response, noted in ten patients, consisted of a chest radiograph compatible with pulmonary edema in the clinical setting of the adult respiratory distress syndrome. In this group the degree of respiratory dysfunction and pulmonary damage correlated with the development of disseminated intravascular coagulation. Pathologic correlations are presented and the mechanisms by which embolic fat produces tissue damage are discussed.     

Therapy of AKR leukemia with antibody-dependent normal lymphocytes and cyclophosphamide

Summary Rat antiserum (anti-Gross virus-associated antigens) plus normal allogeneic spleen cells (CBA/J) were used with cyclophosphamide in the immunochemotherapy of transplantable K36 leukemia in AKR mice. Cyclophosphamide (180 mg/kg) and cyclophosphamide plus normal CBA/J spleen cells increased the median survival time (MST) from 9.0 days (untreated control) to 16.5 and 18.0 respectively. Immune sera, in combination with cyclophosphamide and normal spleen cells, gave an MST of 22.0 days but were ineffective when used as the only adjunct to chemotherapy.Portions of this study were submitted as partial fulfillment of the requirements for the degree of Doctor of Philosophy at The George Washington University     

RhoA, encoding a Rho GTPase, is associated with smoking initiation

We used microarray analysis of acute nicotine responses in mouse brain to choose rationale candidates for human association studies on tobacco smoking and nicotine dependence (ND). Microarray studies on the time-course of acute response to nicotine in mouse brain identified 95 genes regulated in ventral tegmental area. Among these, 30 genes were part of a gene network, with functions relevant to neural plasticity. On this basis and their known roles in drug abuse or synaptic plasticity, we chose the genes RhoA and Ywhag as candidates for human association studies. A synteny search identified human orthologs and we investigated their role in tobacco smoking and ND in a human case-control association study. We genotyped five and three single nucleotide polymorphisms from the RhoA and Ywhag genes, respectively. Both single marker and haplotype analyses were negative for the Ywhag gene. For the RhoA gene, rs2878298 showed highly significant genotypic association with both smoking initiation (SI) and ND (P = 0.00005 for SI and P = 0.0007 for ND). In the allelic analyses, rs2878298 was only significant for SI. In the multimarker haplotype analyses, significant association with SI was found for the RhoA gene (empirical global P values ranged from 9 x 10(-5) to 10(-5)). In all multimarker combinations analyzed, with or without inclusion of the single most significant marker rs2878298, identical risk and protective haplotypes were identified. Our results indicated that the RhoA gene is likely involved in initiation of tobacco smoking and ND. Replication and future model system studies will be needed to validate the role of RhoA gene in SI and ND.     

Macroenvironment effects on oocytes and embryos in swine

As in other domestic mammals, the interaction between genotype and environment in swine has profound effects on the ultimate phenotype of the individual born. Interactions within the litter in utero add an additional level of complexity in a litter-bearing species like the pig. Nutritional manipulations during the preovulatory period affect the maturity of the follicle and enclosed oocyte, and the metabolic and endocrine mechanisms potentially mediating these effects have been described. Extensive research on lactational catabolism in the first parity sow has established an association between the development of immature follicles and oocytes, and the reduced fertility of these sows when bred at the first postweaning estrus. This negative impact of lactational catabolism appears to be exaggerated in contemporary dam-lines by a minimal delay between weaning and first estrus, further limiting the maturity of the follicle and oocyte at the time of ovulation. Metabolic programming may induce gender-specific loss of embryos by Day 30 and affects embryonic development directly, without significant effects on placental size. In contrast, inadvertent crowding of embryos in utero, particularly evident in a sub-population of mature sows with high ovulation rates and moderate to high embryonic survival to Day 30, significantly limits placental development of crowded litters. However, even at Day 30, moderate crowding in utero also appears to affect myogenesis in the embryo in a gender-specific manner. In the absence of compensatory placental growth after Day 30, classic measures of IUGR are evident in surviving fetuses at Day 90 and at term.     

Changes in satellite cell content and myosin isoforms in low-frequency-stimulated fast muscle of hypothyroid rat

Chroniclow-frequency stimulation was used to study the effects of enhancedcontractile activity on satellite cell content and myosin isoformexpression in extensor digitorum longus muscles from hypothyroid rats.As verified by immunohistochemical staining for desmin, vimentin, andmyosin heavy chain (MHC) isoforms and by histological analysis,stimulation induced a transformation of existing fast fibers towardslower fibers without signs of fiber deterioration or regeneration.Immunohistochemically detected increases in MHC I and MHC IIa isoforms,as well as reduced numbers of fibers expressing the faster MHCisoforms, mirrored the rearrangement of the thick-filament composition.These changes, especially the upregulation of MHC IIa, were accompaniedby an induction of developmental MHC isoforms in the transforming adultfibers. Satellite cell content rose 2.6-, 3.0-, and 3.7-fold over thatof corresponding controls (P < 0.05 in all cases) in 5-, 10-, and 20-day-stimulated muscles, respectively.Hypothyroidism alone had no effect on satellite cell content butresulted in a significant reduction in fiber size. The relativesatellite cell contents increased (P < 0.05) from 3.8% in euthyroid control muscles to 7.9, 11.5, and13.8% in the 5-, 10-, and 20-day-stimulated hypothyroid muscles,respectively. In 20-day-stimulated muscles, the relative satellite cellcontent reached an almost twofold higher level than that of normalslow-twitch soleus muscle. This increase occurred concomitantly with arise in myonuclear density, most probably because of the fusion of satellite cells with existing fibers.

     

Specificity and kinetics of triose phosphate isomerase from chicken muscle

The isolation of crystalline triose phosphate isomerase from chicken breast muscle is described. The values of k(cat.) and K(m) for the reaction in each direction were determined from experiments over wide substrate-concentration ranges, and the reactions were shown to obey simple Michaelis-Menten kinetics. With d-glyceraldehyde 3-phosphate as substrate, k(cat.) is 2.56x10(5)min(-1) and K(m) is 0.47mm; with dihydroxyacetone phosphate as substrate, k(cat.) is 2.59x10(4)min(-1) and K(m) is 0.97mm. The enzyme-catalysed exchange of the methyl hydrogen atoms of the ;virtual substrate' monohydroxyacetone phosphate with solvent (2)H(2)O or (3)H(2)O was shown. This exchange is about 10(4)-fold slower than the corresponding exchange of the C-3 hydrogen of dihydroxyacetone phosphate. The other deoxy substrate, 3-hydroxypropionaldehyde phosphate, was synthesized, but is too unstable in aqueous solution for analogous proton-exchange reactions to be studied.