Correcting eggshell indices of raptor eggs for hole size and eccentricity

Eggshell thickness is often expressed by means of an index based on the length, breadth and weight of the shell. The effect of the blow-hole and egg eccentricity on Ratcliffe's shell thickness index was investigated in a sample of 585 eggs from six raptor species. Corrections for the size of the hole and egg eccentricity are proposed, as is a combined formula to correct both sources of error at the same time. It is shown that by using these formulae, considerable improvements in estimates of shell thinning are obtained. These may be especially useful when sample sizes are small, which is often the case when working with species that have been reduced in numbers.     

Susceptibility of Rickettsia monacensis and Rickettsia peacockii to Cecropin A, Ceratotoxin A, and Lysozyme

Ticks host obligate intracellular bacteria that range from benign symbiotes to virulent human pathogens. The effects on those bacteria of antimicrobial peptides (AMPs) involved in arthropod innate immunity to microbial infections are largely unknown. We evaluated effects of AMPs and a c-type lysozyme on host cell-free suspensions of the tick symbiotes Rickettsia monacensis and Rickettsia peacockii with stain-based infectivity and viability assays. Cecropin A at a concentration of 8 μM had a lethal effect on both rickettsiae while ceratotoxin A was approximately 20-fold less effective. Toxicity of both AMPs was synergized by lysozyme, an enzyme expressed by ticks. Lactoferrin, a transferrin, had no effect on R. monacensis at up to 110 μM. The rickettsiae were less sensitive to the AMPs than is typical of bacteria that grow extracellularly. Our assays may be useful in the study of AMP activity against other obligate intracellular bacteria.     

Blood pressure power within frequency range approximately 0.4 Hz in rat conforms to self-similar scaling following spinal cord transection

This study quantified the effect of interrupting the descending input to the sympathetic preganglionic neurons on the dynamic behavior of arterial blood pressure (BP) in the unanesthetized rat. BP was recorded for approximately 4-h intervals in six rats in the neurally intact state and in the same animals after complete spinal cord transection (SCT) between T(4) and T(5). In the intact state, power within the frequency range of 0.35-0.45 Hz was 1.53 +/- 0.38 mmHg(2)/Hz (mean +/- SD by fast Fourier transform). One week after SCT, power within this range decreased significantly (P < 0.05) to 0.43 +/- 0.62 mmHg(2)/Hz. To test for self-similarity before and after SCT, we analyzed data using a wavelet (i.e., functionally, a digital bandpass filter) tuned to be maximally sensitive to fluctuations with periods of approximately 2, 4, 8, 16, 32, or 64 s. In the control state, all fluctuations with periods of >/=4 s conformed to a "self-similar" (i.e., fractal) distribution. In marked contrast, the oscillations with a period of approximately 2 s (i.e., approximately 0.4 Hz) were significantly set apart from those at lower frequencies. One day and seven days after the complete SCT, however, the BP fluctuations at approximately 0.4 Hz now also conformed to the same self-similar behavior characteristic of the lower frequencies. We conclude that 1) an intact sympathetic nervous system endows that portion of the power spectrum centered around approximately 0.4 Hz with properties (e.g., a periodicity) that differ significantly from the self-similar behavior that characterizes the lower frequencies and 2) even within the relatively high frequency range at 0.4 Hz self-similarity is the "default" condition after sympathetic influences have been eliminated.     

Tissue specificity of the sugarcane bacilliform virus promoter in oat,barley and wheat

The tissue-specificity of the sugarcane bacilliform virus (SCBV) promoter was investigated in oat, barley, and wheat to determine whether its expression pattern in one species was predictive of promoter specificity in the other closely related Gramineae species. Progeny of transgenic plants produced using constructs containing the SCBV promoter driving gusA were sampled at different stages of plant development and stained for GUS activity using a histochemical assay. Overall, the GUS staining patterns were most similar between oat and barley. In all three species, similar GUS staining patterns were observed in mature endosperms, leaves, and floral bracts of developing infloresences. No GUS staining was detected in oat embryos whereas the entire barley embryo was stained, and GUS staining was confined to the scutellum of wheat embryos. Oat and barley stems exhibited GUS staining whereas no GUS staining was observed in stems of the transgenic wheat plants. The SCBV promoter conferred strong GUS staining intensity in most tissues of oat and barley but was generally weaker in wheat. These differences in SCBV promoter specificity indicate that promoter evaluation should be conducted in the target species of interest rather than by extrapolation from expression patterns in other species.     

Transposon insertion reveals pRM, a plasmid of Rickettsia monacensis

Until the recent discovery of pRF in Rickettsia felis, the obligate intracellular bacteria of the genus Rickettsia (Rickettsiales: Rickettsiaceae) were thought not to possess plasmids. We describe pRM, a plasmid from Rickettsia monacensis, which was detected by pulsed-field gel electrophoresis and Southern blot analyses of DNA from two independent R. monacensis populations transformed by transposon-mediated insertion of coupled green fluorescent protein and chloramphenicol acetyltransferase marker genes into pRM. Two-dimensional electrophoresis showed that pRM was present in rickettsial cells as circular and linear isomers. The 23,486-nucleotide (31.8% G/C) pRM plasmid was cloned from the transformant populations by chloramphenicol marker rescue of restriction enzyme-digested transformant DNA fragments and PCR using primers derived from sequences of overlapping restriction fragments. The plasmid was sequenced. Based on BLAST searches of the GenBank database, pRM contained 23 predicted genes or pseudogenes and was remarkably similar to the larger pRF plasmid. Two of the 23 genes were unique to pRM and pRF among sequenced rickettsial genomes, and 4 of the genes shared by pRM and pRF were otherwise found only on chromosomes of R. felis or the ancestral group rickettsiae R. bellii and R. canadensis. We obtained pulsed-field gel electrophoresis and Southern blot evidence for a plasmid in R. amblyommii isolate WB-8-2 that contained genes conserved between pRM and pRF. The pRM plasmid may provide a basis for the development of a rickettsial transformation vector.     

Autoradiographic localization of aromatic hydrocarbon receptor (AHR) in rhesus monkey ovary

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic congener of a large class of manmade pollutants that persist in the environment. TCDD exerts its toxic effects, in part, by binding to its receptor known as the aromatic hydrocarbon receptor (AHR). TCDD is estrogen modulatory and in some systems its receptor associates directly with estrogen receptors via co-activator molecules. TCDD inhibits steroid synthesis in human ovarian granulosa cells and AHR is found in these cells. We have previously shown that AHR is found in whole rhesus monkey ovary, but have yet to establish its location. In the present study, we set out to show that radiolabeled TCDD binds to monkey ovarian follicles and that this binding is receptor mediated. Ovaries from Macaca mulatta were sectioned on a cryostat at 10 micro m; and sections were incubated with either control vehicle, (3)H-TCDD, or (3)H-TCDD plus alpha-naphthoflavone (ANF), a known receptor-blocking agent. Here, we show for the first time specific binding of TCDD to the granulosa cells of antral follicles and other regions of the rhesus monkey ovary. Our data indicate a 60-fold increase in binding with (3)H-TCDD over that of control, and that this binding is reduced to the levels seen in controls with the addition of the competitive antagonist ANF. These findings support the hypothesis that TCDD directly affects primate ovarian function via the AHR.     

Bias Assessment of General Chemistry Analytes using Commutable Samples

Harmonisation of reference intervals for routine general chemistry analytes has been a goal for many years. Analytical bias may prevent this harmonisation. To determine if analytical bias is present when comparing methods, the use of commutable samples, or samples that have the same properties as the clinical samples routinely analysed, should be used as reference samples to eliminate the possibility of matrix effect. The use of commutable samples has improved the identification of unacceptable analytical performance in the Netherlands and Spain. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has undertaken a pilot study using commutable samples in an attempt to determine not only country specific reference intervals but to make them comparable between countries. Australia and New Zealand, through the Australasian Association of Clinical Biochemists (AACB), have also undertaken an assessment of analytical bias using commutable samples and determined that of the 27 general chemistry analytes studied, 19 showed sufficiently small between method biases as to not prevent harmonisation of reference intervals. Application of evidence based approaches including the determination of analytical bias using commutable material is necessary when seeking to harmonise reference intervals.