Natural hyperthermia and expression of the heat shock protein Hsp70 affect developmental abnormalities in Drosophila melanogaster

We demonstrate that natural heat stress on wild larval Drosophila melanogaster results in severe developmental defects in >10% of eclosing adults, and that increased copy number of the gene encoding the major inducible heat shock protein of D. melanogaster, Hsp70, is sufficient to reduce the incidence of such abnormalities. Specifically, non-adult D. melanogaster inhabiting necrotic fruit experienced severe, often lethal heat stress in natural settings. Adult flies eclosing from wild larvae that had survived natural heat stress exhibited severe developmental anomalies of wing and abdominal morphology, which should dramatically affect fitness. The frequency of developmental abnormalities varied along two independent natural thermal gradients, exceeding 10% in adults eclosing from larvae developing in warm, sunlit fruit. When exposed to natural heat stress, D. melanogaster larvae with the wild-type number of hsp70 genes (n=10) developed abnormal wings significantly more frequently than a transgenic sister strain with 22 copies of the hsp70 gene. Received: 19 April 1999 / Accepted: 16 July 1999     

Quantitative trait loci analysis for the developmental behavior of tiller number in rice (Oryza sativa L.)

 A doubled-haploid rice population of 123 lines from Azucena/IR64 was used for analyzing the developmental behavior of tiller number by conditional and unconditional QTL mapping methods. It was indicated that the number of QTLs significantly affecting tiller number was different at different measuring stages. Many QTLs controlling tiller growth identified at the early stages were undetectable at the final stage. Only one QTL could be detected across the whole growth period. By conditional QTL mapping, more QTLs for tiller number could be detected than that by unconditional mapping. The temporal patterns of gene expression for tiller number could be different at different stages. Even an individual gene or genes at the same genomic region might have opposite genetic effects at various growth stages. Received: 7 July 1997 / Accepted: 10 February 1998     

Immuno-electron microscopy reveals that the excitotoxin quinolinate is associated with the plasma membrane in human peripheral blood monocytes/macrophages

Quinolinate (QUIN), a tryptophan-derived excitotoxin, was localized ultrastructurally in human peripheral blood monocytes/macrophages (M?) by immuno-electron microscopy. A combined carbodiimide/glutaraldehyde/paraformaldehyde-based fixation procedure was developed for optimal retention of QUIN in the cell as well as minimal loss of ultrastructure; a silver-enhanced colloidal gold detection system was used for electron-microscopic analysis. Gold particles representing QUIN immunoreactivity were associated with the inner side of the plasma membrane in normal M?. The number of gold particles increased significantly when QUIN levels were elevated by treatment with its precursor kynurenine, but location of the gold particles remained essentially the same under this condition. Treatment with interferon-γ increased the number of Golgi bodies, vacuoles and pseudopodia, reflecting the activated state of the cell. Significantly increased numbers of gold particles representing QUIN were detectable in approximately the same location as in the case of kynurenine treatment. Combined treatment with kynurenine and interferon-γ maximally increased the number of gold particles at the periphery of the cell. The pseudopodia were intensely stained with gold particles, while they were not detectable in the inner part of the cytoplasm or in any other organelle even under this activated condition. The significance of the specific location of QUIN revealed in the present study and its relation to the release and subsequent actions of QUIN are discussed. Received: 30 May 1996 / Accepted: 22 May 1997     

AFLP analysis of genetic relationships in the tribe Datureae (Solanaceae)

The AFLP technique was evaluated as a tool for assessing species relationships within the tribe Datureae and genetic distances were estimated for 47 accessions of over 12 species. The phenetic trees from various analyses of the AFLP data gave very high co-phenetic correlation values, and were found to be consistent with previous trees based on the analysis of different data types, in particular ITS-1 sequences, isozymes and morphology, carried out on the same accessions. These results indicated that the AFLP technique is both an efficient and effective tool for determining genetic relationships among taxa in the Solanaceae. A new classification is proposed for the tribe Datureae, which maintains the arborescent species as a separate genus, Brugmansia, and recognises three sections within the genus Datura; Stramonium, Dutra and Ceratocaulis. D. discolor, previously placed in section Dutra, was found to be intermediate between sections Dutra and Stramonium. Received: 11 January 1999 / Accepted: 1 February 1999     

Quantitative chromosome maps and rDNA localization in the T subgenome of Nicotiana tabacum L. and its putative progenitors

Using DAPI-stained prometaphase chromosomes, quantitative idiograms were constructed for the T subgenome of Nicotiana tabacum (2n = 4x = 48, SSTT) and two putative candidates for its T subgenome progenitor, Nicotiana otophora and Nicotiana tomentosiformis (both have 2n = 24, TT). The large chromosomes of the three karyotypes could be identified from the distributional pattern of the DAPI signal. Fluorescence in situ hybridization (FISH) with 5S rDNA gave not only good cytogenetical landmarks for identification of small chromosomes of the karyotypes but also phylogenetical information. In all three idiograms, 5S rDNA was localized in the proximal region of the long arm of a small submetacentric pair, but an additional 5S rDNA locus was detected terminally on the short arm of a small metacentric pair in N. otophora. The 18S rDNA locus detected here corresponded to satellite regions in all three karyotypes. Two satellited pairs in N. otophora and one satellited pair in N. tomentosiformis had single large subterminal DAPI blocks and two interstitial DAPI bands on their long arms, respectively. For the T subgenome component of N. tabacum, the single intense DAPI band was depicted on the center of the long arm of a satellited pair in the idiogram, although two interstitial bands were often detected on the long arm of the satellited pair in some spreads. Therefore, it was suggested that the T component of N. tabacum was more similar to that of N. tomentosiformis than N. otophora, especially in respect of the number and location of rDNA and the distributional patterns of DAPI signals. Received: 25 October 1999 / Accepted: 24 March 2000<@head-com-p1a.lf>Communicated by Y. Gleba     

Time series analysis supporting the hypothesis that enhanced cosmic radiation during germ cell formation can increase breast cancer mortality in germ cell cohorts

 Techniques from cancer epidemiology and time series analysis were used to explore the hypothesis that cosmic radiation can induce germ cell changes leading to increases in future breast cancer mortality. A birth cohort time series for female breast cancer mortality was obtained using a model-independent, age-period-cohort analysis on age-specific mortality data for 1940–1990. The birth cohort series contained several oscillatory components, which were isolated and compared to the corresponding frequency components of a cosmic ray surrogate time series – Greenland ice-core ¹⁰Be concentrations. A technique, referred to as component wave-train alignment, was used to show that the breast cancer and cosmic ray oscillations were phase-locked approx. 25 years before the time of birth. This is consistent with the time of germ cell formation, which occurs during the fetal development stage of the preceding generation. Evidence is presented that the observable oscillations in the birth cohort series were residues of oscillations of much larger amplitude in the germ cell cohort, which were attenuated by the effect of the broad maternal age distribution. It is predicted that a minimum of 50% of breast cancer risk is associated with germ cell damage by cosmic radiation (priming event), which leads to the development of individuals with a higher risk of breast cancer. It is proposed that the priming event, by preceding other steps of carcinogenesis, works in concert with risk factor exposure during life. The priming event is consistent with epigenetic changes such as imprinting. Received: 10 June 1996 / Revised: 4 December 1996 / Accepted: 19 December 1996     

The potential of ISSR-PCR primer-pair combinations for genetic linkage analysis using the seasonal flowering locus in Fragaria as a model

ISSR-PCR has been widely used for genetic distance analysis and DNA fingerprinting but has been less well utilised for mapping purposes. A key limitation lies in the small number of primer designs available to generate useful polymorphisms. In this study, the potential of paired combinations of ISSR primers is evaluated using a test cross mapping population of 168 BC₁ individuals between Fragaria vesca f. vesca and a closely related line F. vesca f. semperflorens. Ten ISSR primers and all possible pairwise combinations between them were used to generate markers potentially linked to the locus controlling seasonal flowering in F. vesca. Band profiles of individual primers were found to be highly reproducible for band position and intensity, and only minor variation was noted in band intensity (but not in position) between different constituent mixes of primer-pair combinations. Overall, ISSR primers used in isolation produced 85 markers of which only five were specific to F. vesca. None of these markers were linked to the seasonal flowering locus. In contrast, the primer-pair combina-tions yielded 493 markers, including 14 specific to F. vesca. These markers included two located within 2.2 cM of the seasonality locus. The strengths and limitations of using pairs of ISSR primers in combination for mapping and other genetic analyses are briefly explored. Received: 12 October 2000 / Accepted: 19 January 2001