A genetic and spatial Bayesian analysis of mastitis resistance

A nationwide health card recording system for dairy cattle was introduced in Norway in 1975 (the Norwegian Cattle Health Services). The data base holds information on mastitis occurrences on an individual cow basis. A reduction in mastitis frequency across the population is desired, and for this purpose risk factors are investigated. In this paper a Bayesian proportional hazards model is used for modelling the time to first veterinary treatment of clinical mastitis, including both genetic and environmental covariates. Sire effects were modelled as shared random components, and veterinary district was included as an environmental effect with prior spatial smoothing. A non-informative smoothing prior was assumed for the baseline hazard, and Markov chain Monte Carlo methods (MCMC) were used for inference. We propose a new measure of quality for sires, in terms of their posterior probability of being among the, say 10% best sires. The probability is an easily interpretable measure that can be directly used to rank sires. Estimating these complex probabilities is straightforward in an MCMC setting. The results indicate considerable differences between sires with regards to their daughters disease resistance. A regional effect was also discovered with the lowest risk of disease in the south-eastern parts of Norway.     

Biosensors for process monitoring

Summary A short review about the biosensor research activities for bioprocess monitoring in the F.R.G. after its reunification is given. The principles of biosensor applications are presented. In situ sensors and sensors based on the principles of flow injection analysis are studied. Some applications of a four-channel enzyme thermistor, bio-field effect transistors, and immunoanalysis systems for real process monitoring are presented.     

Synthesis of 5‐tert‐butyl‐1‐(3‐tert‐butyldimethylsiloxy)phenyl‐4,4‐dimethyl‐2,6,7‐trioxabicyclo[3.2.0]heptanes and their fluoride‐induced chemiluminescent decomposition: effect of a phenolic electron donor on the CIEEL decay rate in aprotic polar solvent

Four bicyclic dioxetanes bearing a phenolic substituent, 3‐tert‐butyldimethylsiloxy‐4‐chlorophenyl ( 3a ), 5‐tert‐butyldimethylsiloxy‐4‐chloro‐2‐ethylphenyl ( 3b ), 5‐tert‐butyldimethylsiloxy‐2‐ethylphenyl ( 3c ), and 3‐tert‐butyldimethylsiloxy‐4‐ethylphenyl ( 3d ), were synthesized. All dioxetanes 3a – 3d gave intense blue light on treatment with tetrabutylammonium fluoride (TBAF) in DMSO or acetonitrile. Kinetic study on the fluoride‐induced CIEEL decay of these dioxetanes 3a – 3d and the parent dioxetane 2b revealed that the para‐substitution with chlorine on the phenolic moiety of dioxetane increases free energy of activation (ΔG?), while the para‐substitution with ethyl on the aryl decreases ΔG?. On the other hand, substitution with an ethyl at the ortho‐position instead of the para‐position was found to increase ΔG? and to suppress the CIEEL decay. This fact is attributed to the steric factor of the ortho‐ethyl group which would prevent the aromatic ring from rotating freely around the axis joined to the peroxide ring, and supports the suggestion for a CIEEL‐active dioxetane bearing a phenolic moiety that an intramolecular electron transfer occurs preferentially from the phenolic donor to O–O of the dioxetane ring, when the aromatic ring lies in a certain conformation(s). Copyright © 2002 John Wiley & Sons, Ltd.     

The “ricochet effect” and prey capture in colonial spiders

Summary Increased prey capture efficiency in colonial spiders is a consequence of the ricochet effect, as prey are captured after they bounce off several webs in succession. In this study, the prey capture of three species of colonial spiders in the genus Metepeira from Mexico are compared. These species, from different habitats, show varying levels of social organization (group size and withingroup spacing) that affect prey capture from ricochets. Metepeira sp. a (a presumed new species tentatively named atascadero) from desert grassland habitats, occur solitarily or in small groups, and gain little from prey ricochets: prey capture rates are low and variance in prey captured/spider is high. M. spinipes, from mesic agricultural sites, occur in groups of 10–150, and show a ricochet effect resulting in more and larger prey, and reduced variance in capture rate. M. incrassata, from tropical rainforest/agricultural sites, occur in large colonies of hundreds to thousands of individuals, and show a similar ricochet effect. The ricochet effect does not influence taxonomic composition of prey in either M. atascadero or M. spinipes, but does in tropical M. incrassata. This result, however, is primarily due to the capacity of certain taxa (eg., Lepidoptera), more common in the tropics, to escape more easily from spider webs. A comparison of prey capture efficiency of colonial M. incrassata with that of solitary M. atascadero shows that the ricochet effect provides an increase in efficiency across all size classes of prey.     

The X-ray induced G2 arrest in mouse eggs: a maternal effect involving a lack of polypeptide phosphorylation

Summary In some strains of mice, eggs when X irradiated during the pronuclear stage, undergo a mitotic block in the G₂ phase of the first cell cycle and cleave when the second division takes place in controls. The importance of this effect varies considerably with the strain and depends exclusively on the maternal genotype. In previous work, two-dimensional electrophoresis showed that eggs blocked at the one-cell stage after irradiation, undergo the same modifications in polypeptide synthesis as two-cell controls of the same age, except at the time of normal first mitosis, where three polypeptide sets of 30, 35 and 45 kDa appear only in cleaving controls. In the present study, we have found phosphorylations in dividing controls, on polypeptides of 30, 35 and 45 kDa. These phosphorylations are not seen in blocked irradiated eggs.     

Morphological dispersion of introduced Hawaiian finches: evidence for competition and a Narcissus effect

Summary Morphological analyses were conducted on finch species introduced to Oahu, Hawaii. As many as 25 species of finches representing four families (Emberizidae, Fringillidae, Ploecidae, Estrildidae) have been introduced to Oahu. Of these, 15 species currently have established wild populations. When compared with pools of 25 and 23 species introduced to Oahu, the 15 surviving species are morphologically overdispersed. This result is consistent with the hypothesis that competition has influenced the outcome of these introductions. We also tested the hypothesis that surviving introduced finches in one habitat (sugarcane fields) were morphologically overdispersed. When the seven surviving finch species found in sugarcane were compared with the pools of 25 and 23 species, they too were morphologically overdispersed. However, when the seven sugarcane species were compared with a species pool consisting of only the surviving 15 species found across Oahu, they were not morphologically overdispersed. This result suggests that morphological analyses of community structure based only on comparisons of assemblages of surviving species may be biased by a Narcissus effect.     

Effect of TSH in human thyroid cells: evidence for both mitogenic and antimitogenic effects.

The well-known mitogenic effects of TSH observed in vivo on the thyroid are not always reproducible of human thyroid cells in vitro where conflicting results have been obtained. In order to clarify this issue, we have used primary cultures of human thyroid cells obtained from normal tissue and maintained in serum-free medium for several days. In this in vitro model we have studied the effect of TSH on growth by measuring three different parameters: [3H]-thymidine incorporation, cell counts, and DNA measurement. Monolayer cultures were plated at both low and high cell density (2 x 10(4) and 8 x 10(4) cells/25 mm well, respectively). Although at either cell density cultures were equally able to functionally respond to TSH in terms of cAMP accumulation a significant growth response to TSH was observed only in low density cultures. In high density cultures TSH had an antimitogenic effect. Moreover, TSH potentiated the mitogenic effect of insulin only in low density cultures. In contrast to TSH, FCS induced a similar proliferative response at both high and low cell density. Following TSH stimulation, cAMP content was always increased, paralleling the effect of growth in low density but not in high density cultures. The cAMP analogues dibutyryl-cAMP and 8-bromo-cAMP, as well as cholera toxin and forskolin, did not mimic the mitogenic effect of TSH but had an antiproliferative effect. In addition, these agents blunted the proliferative effect of insulin. These data suggest that in thyroid cells TSH is able to elicit both a mitogenic and an antimitogenic effect depending on the environmental conditions such as cell density.(ABSTRACT TRUNCATED AT 250 WORDS)     

染色体辐射效应的微机检测 Ⅱ断片率 微核率与细胞畸变率间的相关性检测

本文继前文后,按照设计的线性回归程序在“IBM—PC/XT”微型计算机上,进一步检测了断片率、微核率与细胞畸变率之间的相关性,肯定了微核测定法,断片测定法可以替代染色体畸变分析法。