Sequence analysis of the germ-line VH gene corresponding to a nephritogenic antibody in MRL/lpr lupus mice.

In order to investigate the genetic origin of nephritogenic antibodies in MRL/Mp-lpr/lpr (MRL/lpr) lupus mice, we isolated the germ-line heavy chain variable region (VH) gene corresponding to the nephritogenic antibody, B1, derived from an unmanipulated MRL/lpr mouse. Injection of this antibody into C.B-17/Icr-scid/scid mice resulted in the generation of wire loop-like glomerular lesions resembling those of lupus nephritis. Nucleotide sequences of this germ-line VH gene showed no replacement mutation in the VH region of the B1 antibody. Furthermore, this gene was identical to that found in the C3H/HeJ-lpr/lpr strain of mice. Our results suggest that germ-line VH genes can encode nephritogenic antibodies without somatic mutation, even in a mouse strain not prone to lupus.     

Genetic variation within a parthenogenetic lineage

A clone of the grain aphid Sitobion avenae F. was maintained parthenogenetically over thirty-two generations (n= 344) in a constant environment: a new generation being set up by a female selected at random from the preceding generation. Genomic DNA from individual aphids was screened for genetic stability using RAPD-PCR with a previously tested ten-mer primer. A putative germ-line mutation was noted in generation 14 and somatic mutations were noted in generations 12, 25, 27 and 29. There were no differences in the RAPD-PCR profiles of winged and wingless morphs and samples tested for symbiotic DNA. No endobiotic fungal organism was associated with the clone. Southern blotting and hybridization studies indicated that band additions were of aphid origin. However, the RAPD-PCR profiles of the germ-line and somatic mutation samples were unique from other aphid clones cultured during the experimental period. This paper documents discernible genetic changes occurring within an animal clonal lineage over time and impacts on the consequences this may have for clonal systems.     

Establishment of Germ-line Competent C57BL/6J Embryonic Stem Cell Lines

Objective To establish C57BL/6J embryonic stem （ES） cell lines with potential germ- line contribution Methods ES cells were isolated from blastocyst inner cell mass of C5 7BL/6J mice, and cultured for 15 passages, and then injected into blastococels of ICR mice blastocysts to establish chimeric mice. Results Three ES cell lines （mC57ES1,mC57ES3, mC57ES7） derived from the inner cell mass of C57BL/6J mice blastocysts were established. They were characteristic of undifferentiated state, including normal XY karyotype, expression of a specific cell surface marker “stage-specific embryonic antigen-I” and alkaline phosphatase in continuous passage. When injected into immunodeficient mice, mC57ES1 cells consistently differentiated into derivatives of all three embryonic germ layers. When mC57ES1 cells were transferred into ICR mice blastocysts, 4 chimeric mice have been obtained. One male of them revealed successful germ-line transmission. Conclussion We have obtained C57BL/6J ES cell lines with a potential germ-line contribution, which can be used to generate transgenic and gene knock-out mice.     

The combination of Hirschsprung's disease and achalasia

The unusual combination of Hirschsprung's disease and Achalasia in one case treated by standard procedures led to the discussion about RET germ-line mutations and consequently to the speculation about higher risk for multiple endocrine neoplasia syndrome type 2-related tumors. Although a mutation could be excluded by sequence analysis in this case, the correlation of these specific diseases affords additive investigations to make sure that no further prophylactic procedures were necessary.     

Germ-line transformation of the South American malaria vector,Anopheles albimanus,with a piggyBac/EGFP transposon vector is routine and highly efficient

Stable and efficient germ-line transformation was achieved in the South American malaria vector, Anopheles albimanus, using a piggyBac vector marked with an enhanced green fluorescent protein gene regulated by the Drosophila melanogaster polyubiquitin promoter. Transgenic mosquitoes were identified from four independent experiments at frequencies ranging from 20 to 43% per fertile G0. Fluorescence was observable throughout the body of larvae and pupae, and abdominal segments of adults. Transgenic lines analysed by Southern hybridization had one to six germ-line integrations, with most lines having three or more integrations. Hybridized transposon vector fragments and insertion site sequences were consistent with precise piggyBac-mediated integrations, although this was not verified for all lines. The piggyBac/PUbnlsEGFP vector appears to be a robust transformation system for this anopheline species, in contrast to the use of a piggyBac vector in An. gambiae. Further tests are needed to determine if differences in anopheline transformation efficiency are due to the marker systems or to organismal or cellular factors specific to the species.     

From what should we protect future generations: Germ-line therapy or genetic screening?

This paper discusses the issue of whether we have responsibilities to future generations with respect to genetic screening, including for purposes of selective abortion or discard. Future generations have been discussed at length among scholars. The concept of Guardianfor Future Generations is tackled and its main criticisms discussed. Whilst germ-line cures, it is argued, can only affect family trees, genetic screening and testing can have wider implications. If asking how this may affect future generations is a legitimate question and since we indeed make retrospective moral judgements, it would be wise to consider that future generations will make the same retrospective judgements on us. Moreover such technologies affect present embryos to which we indeed can be considered to have an obligation.This revised version was published online in October 2005 with corrections to the Cover Date.     

piggyBac-mediated transposition in Drosophila melanogaster: an evaluation of the use of constitutive promoters to control transposase gene expression

Transgenic non-Drosophilid insects have been made using insect transposable elements that have a broad host range such as the piggyBac element. However, the success rate is often low. Previous piggyBac helper plasmids have used either the piggyBac or the hsp70 promoter from Drosophila melanogaster to control expression of the transposase gene. Here we show that plasmids with the piggyBac transposase gene regulated by constitutive promoters can be effective 'helpers' for mediating transposition in D. melanogaster. We also present preliminary evidence on the use of an RNA helper that encodes the transposase. Our results suggest that for germ-line transformation of non-Drosophilid insects it may be advantageous to isolate a constitutive promoter from the species of interest to control transposase expression.     

Criteria for mutation analysis in MEN 1-suspected patients: MEN 1 case-finding

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal, dominantly inherited cancer syndrome, with tumours in various endocrine glands. In 1997 the responsible tumour suppressor gene was identified. MEN1 gene germ-line mutations are detected in the vast majority of MEN 1 patients, however, with regard to case-finding, unfortunately only at a very low frequency in patients with apparently sporadic MEN 1-related tumours. In order to increase the detection rate of disease gene carriers among patients with apparently sporadic MEN 1-related tumours, clinical criteria were needed. DESIGN AND RESULTS: In this study MEN1 gene germ-line mutations were revealed in 16/16 MEN 1 patients/families (100%). Based on our clinical experience with MEN 1 patients/families we formulated clinical criteria to identify disease gene carriers among patients with apparently sporadic MEN 1-related tumours. The criteria for MEN 1-suspected patients are: young age at onset (< 35 years) and/or multiple MEN 1-related lesions in a single organ or two distinct organs affected. Application of these criteria yielded MEN1 gene germ-line mutations in nine of 15 MEN 1-suspected patients (60%), thus identifying novel MEN 1 families. Follow up was also guaranteed for patients not fulfilling these criteria. CONCLUSIONS: The clinical criteria for MEN 1-suspected patients increase the detection rate of germ-line MEN1 gene mutations among patients with apparently sporadic MEN 1-related tumours. These criteria may be used for (presymptomatic) identification of MEN 1 disease gene-carriers, thus enabling early detection of tumour development and timely treatment, as well as genetic counselling.