Cyclooxygenase mediated airway response to leukotriene D4 in the cat

The effects of leukotriene D4 (LTD4) on pulmonary mechanics were investigated in anesthetized, paralyzed cats under conditions of controlled ventilation. Intravenous injections of LTD4 in doses of 3, 10, and 30 micrograms caused significant increases in transpulmonary pressure (PTP) and lung resistance (RL) while decreasing dynamic compliance (Cdyn). LTD4 also increased systemic arterial pressure (PAo). The changes in PTP, RL, and Cdyn in response to LTD4 were blocked by sodium meclofenamate, a cyclooxygenase inhibitor. However, there was no significant change in the increase in PAo following cyclooxygenase blockade. U 46619, a thromboxane mimic, was 30 to 100 times more potent than LTD4 in increasing PTP, RL and decreasing Cdyn in the cat. These data show that LTD4 has significant smooth muscle constrictor activity in central airways as well as peripheral portions of the feline lung. In addition, these data suggest that in the cat the actions of intravenously administered LTD4 on lung mechanics are mediated by release of cyclooxygenase products while the systemic pressor effects are not dependent upon the integrity of the cyclooxygenase pathway.     

Mapping genes conditioning in vitro androgenesis in maize using RFLP analysis

Summary This research was designed to map the genes in maize which condition a high response to anther culture using RFLP analysis. A set of 98 S₁ families were developed from the cross of B73 × 139/39-05. In vitro-cultured anthers of 139/39-05 produce numerous embryolike structures while anthers cultured from B73 produce none. Plants from each of the families were grown in the greenhouse. Tassels were harvested from ten individual plants within each family and pretreated prior to culture. Up to three Petri dishes with 60 anthers each were cultured from each tassel. Response was measured as the number of embryo-like structures per 100 anthers cultured. In excess of 105 RFLP clones were screened to detect polymorphism among the parents. A subset of 75 widely distributed clones were scored in the 98 families. Based on the analysis of the resulting genetic data set, the high anther culture response observed in 139/39-05 is conditioned by two major recessive genes, which are epistatic, and two minor genes. One of the two major loci resides in the proximal region of the long arm of chromosome 3 near the indeterminate gametophyte (ig1) gene. The second major locus maps to the centromeric region of chromosome 9. The minor genes reside on chromosomes 1 and 10. Fifty seven percent of the variability among the 98 family means is explained by a genetic model which includes these four chromosomal regions. Moreover, segregation at these loci explains much of the variability observed within the families.     

Quantitative analysis of the density and pattern of adrenergic innervation of blood vessels

Summary Automated quantitative image analysis (QIAF) was used to measure and compare the adrenergic nerve plexuses of 4 blood vessels from the guinea pig, demonstrated by glyoxylic acid fluorescence (GAF). The results showed considerable quantitative variation of plexus density, size of bundles, and numbers of varicosities. A range of alternative procedural and anatomical sources of variability were investigated and assessed. The carotid artery was found to have a dense plexus with more nerves than that of the mesenteric artery; the mesenteric vein and abdominal aorta had sparse plexuses. The carotid artery plexus, despite the density of its nerves, possessed only half the number of varicosities of the mesenteric artery plexus. This sparse varicosity population was shown to have a similar density to the varicosities demonstrated by QIAF in the scattered nerves of the mesenteric vein and abdominal aorta. QIAF confirmed visual estimates of adrenergic plexus density, and was able to demonstrate less obvious differences of nerve density and size, and varicosity populations, between the different plexuses studied. The method is applicable to stretch preparations and transverse sections of many adrenergically innervated tissues.     

Complete tag loss in capture–recapture studies affects abundance estimates: An elephant seal case study

1. In capture–recapture studies, recycled individuals occur when individuals lose all of their tags and are recaptured as though they were new individuals. Typically, the effect of these recycled individuals is assumed negligible.
2. Through a simulation‐based study of double‐tagging experiments, we examined the effect of recycled individuals on parameter estimates in the Jolly–Seber model with tag loss (Cowen & Schwarz, 2006). We validated the simulation framework using long‐term census data of elephant seals.
3. Including recycled individuals did not affect estimates of capture, survival, and tag‐retention probabilities. However, with low tag‐retention rates, high capture rates, and high survival rates, recycled individuals produced overestimates of population size. For the elephant seal case study, we found population size estimates to be between 8% and 53% larger when recycled individuals were ignored.
4. Ignoring the effects of recycled individuals can cause large biases in population size estimates. These results are particularly noticeable in longer studies.

     

Image analysis of FITC-immunofluorescence histochemistry in perivascular substance P-positive nerves

The ability of image analysis to quantify nerves labelled by FITC-immunofluorescence histochemistry has been tested on whole-mount stretch preparations of perivascular substance P-positive nerves. It has been shown that image analysis can make consistent measurements of nerves demonstrated by immunohistochemistry despite the fading of FITC-fluorescence which occurs during storage and on exposure to ultraviolet light.