Intranuclear differences in the response of Purkinje cell DNA of the rat cerebellum to bleomycin

Summary A single dose of the DNA-binding cytostatic agent bleomycin (100 g/g body weight, subcutaneously) was given to 10-day-old rats to study unscheduled repair DNA synthesis in nucleolar and in bulk nuclear chromatin of postmitotic Purkinje neurons. The Feulgen reaction and Hoechst 33342 staining were used for quantitative evaluation of nuclear DNA content and chromatin structure. The repair synthesis of DNA was detected by ³H-thymidine autoradiography.The data showed a lesser staining of Purkinje as well as granule cell DNA by Hoechst 33342 in bleomycin-treated animals than in controls, but there was no difference in staining with the Feulgen reation. The mechanisms of DNA staining by both cytochemical methods suggest that bleomycin reacted preferentially with AT-rich and single stranded DNA in cerebellar cells in vivo. Weak ³H-thymidine labelling was found in Purkinje cells of both control and treated rats, but in the latter group the labelling was more pronounced near or over the nucleolus. The enhanced unscheduled DNA synthesis in the nucleolar region of Purkinje cells of treated animals may be due to greater damage of DNA in this region or may indicate a greater ability of the nucleolar chromatin to repair its DNA.Dedicated to Professor Dr. Z. Lojda, Dr. Sc., on the occasion of his 60th birthday.     

PCR-based fingerprinting using AFLPs as a tool for studying genetic relationships in Lactuca spp.

AFLP markers were evaluated for determining the phylogenetic relationships Lactuca spp. Genetic distances based on AFLP data were estimated for 44 morphologically diverse lines of cultivated L. sativa and 13 accessions of the wild species L. serriola, L. saligna, L. virosa, L. perennis, and L. indica. The same genotypes were analyzed as in a previous study that had utilized RFLP markers. The phenetic tree based on AFLP data was consistent with known taxonomic relationships and similar to a tree developed with RFLP data. The genetic distance matrices derived from AFLP and RFLP data were compared using least squares regression analysis and, for the cultivar data, by principal component analysis. There was also a positive linear relationship between distance estimates based on AFLP data and kinship coefficients calculated from pedigree data. AFLPs represent reliable PCR-based markers for studies of genetic relationships at a variety of taxonomic levels.     

A high-resolution map of the vicinity of the R1 locus on chromosome V of potato based on RFLP and AFLP markers

The R1 allele confers on potato a race-specific resistance to Phytophthora infestans. The corresponding genetic locus maps on chromosome V in a region in which several other resistance genes are also located. As part of a strategy for cloning R1, a high-resolution genetic map was constructed for the segment of chromosome V that is bordered by the RFLP loci GP21 and GP179 and includes the R1 locus. Bulked segregant analysis and markers based on amplified fragment length polymorphisms (AFLP markers) were used to select molecular markers closely linked to R1. Twenty-nine of approximately 3200 informative AFLP loci displayed linkage to the R1 locus. Based on the genotypic analysis of 461 gametes, eight loci mapped within the GP21–GP179 interval. Two of those could not be seperated from R1 by recombination. For genotyping large numbers of plants with respect to the flanking markers GP21 and GP179 PCR based assays were also developed which allowed marker-assisted selection of plants with genotypes Rr and rr and of recombinant plants.     

Feeding on Profitable and Unprofitable Prey: Comparing Behaviour of Growth-Enhanced Transgenic and Normal Coho Salmon (Oncorhynchus kisutch)

We compared the performance of normal and growth hormone‐transgenic coho salmon feeding on surface drifting edible and inedible novel prey items in various social environments. With an inherently higher appetite, we predicted that transgenic fish would be more willing to feed on novel prey, and that visual company with another fish would enhance this difference further. Transgenic and normal fish, of similar size and age, were equally willing to attack both the edible (live insects) and inedible (artificial angling lure flies) prey, but transgenic fish did so faster and were more likely to make repeated attacks. Transgenic fish managed to seize and consume the edible prey after fewer attacks than did normal fish. However, swallowing of prey took longer than for normal fish. More transgenic individuals interacted with the inedible prey compared with normal salmon, and initially, transgenic fish in visual company with another fish also interacted more with the prey than single transgenic or any constellation of normal focal fish. With repeated exposures, the number of individuals attacking and the number of interactions with the prey decreased. These responses were stronger in transgenic fish, partly explained by the initially low response in normal fish. The observed differences are most likely the consequences of elevated levels of growth hormone in transgenic fish generating enhanced feeding motivation and reinforcement capacity. In a natural environment, the performance of a growth hormone‐transgenic fish may therefore depend on the relative abundance of profitable vs. unprofitable prey, as well as the presence of other transgenic individuals.     

Calbindin 28 kDa in endocrine cells of known or putative calcium-regulating function

Summary The distribution of calbindin in some endocrine glands (thyroid, parathyroid, ultimobranchial body, pituitary and adrenals) and in the diffuse endocrine cells of the gut and pancreas has been investigated immunohistochemically using an antiserum raised against the 28 kDa calbindin from chicken duodenum. The identity of calbindin-immunoreactive cells in a number of avian and mammalian species was ascertained by comparison with hormone-reactive cells in consecutive sections or by double immunostaining of the same section with both calbindin and hormone antibodies. Calcitonin-producing C cells of the mammalian and avian thyroid, parathyroid or ultimobranchial body, PP, glucagon and insulin cells of the mammalian and avian pancreas, enteroglucagon cells of the avian intestine, secretin cells of the mammalian duodenum, histamine-producing ECL cells of the mammalian stomach, as well as noradrenaline-producing cells of the adrenal medulla and some (TSH?) cells of the adenohypophysis were among the calbindin-immunoreactive cells. Although some species variability has been observed in the intensity and distribution of the immunoreactivity, especially in the pancreas and the gut, a role for calbindin in the mechanisms of calcium-mediated endocrine cell stimulation or of intracellular and extracellular calcium homeostasis is suggested.     

Cytophotometric Re-investigation of DNA content in Purkinje cells of the rat cerebellum

Summary Stage scanning cytophotometry of Feulgen-stained cell nuclei of the cerebellum of young adult rats revealed that the absorbance values of the majority of the Purkinje cells show a Gaussian distribution with a low coefficient of variance. The peak absorbance of this population is the same as that of the granule cells. About 1% of the Purkinje cells measured, were found to have a stain content which indicates a 4C amount of DNA. For both the granular and the Purkinje cell population, a very small number of nuclei possesses absorbance values intermediate between 2C and 4C. The present data suggest prevalent diploidy of the Purkinje cells, and are at variance with those postulating a tetraploid and/or hyperdiploid status of this population.