Physical mapping of new DNA probes near the fragile X mutation (FRAXA) by using a panel of cell lines

The fragile X syndrome is a very common disorder, but there has been little progress toward isolating the fragile X mutation (FRAXA). We describe a panel of 14 somatic cell hybrid lines, lymphoblastoid cell lines, and peripheral lymphocytes with X-chromosome translocation or deletion breakpoints near FRAXA. The locations of the breakpoints were defined with 16 established probes between pX45d (DXS100) and St14-1 (DXS52). Seven of the cell lines had breakpoints between the probes RN1 (DXS369) and U6.2 (DXS304), which flank FRAXA at distances of 3-5 centimorgans. The panel of cell lines was used to localize 16 new DNA probes in this region. Six of the probes-VK16, VK18, VK23, VK24, VK37, and VK47--detected loci near FRAXA, and it was possible to order both the X-chromosome breakpoints and the probes in relation to FRAXA. The order of probes and loci near FRAXA is cen-RN1,VK24-VK47-VK23-VK16,FRAXA-++ +VK21A-VK18-IDS-VK37-U6.2-qter. The breakpoints near FRAXA are sufficiently close together that probes localized with this panel can be linked on a large-scale restriction map by pulsed-field gel electrophoresis. This panel of cell lines will be valuable in rapidly localizing other probes near FRAXA.     

An expanded mouse-human hybrid cell panel for mapping human chromosome 16

A mouse/human hybrid cell panel of human chromosome 16 has been extended to a total of 31 hybrids. These hybrids were derived from constitutional translocations and deletions ascertained during clinical cytogenetic studies. This panel of hybrids, together with four fragile sites, have the potential to divide chromosome 16 into 38 regions. Rapid detailed physical mapping of gene probes or anonymous DNA probes is possible using this hybrid panel. This hybrid cell panel also allows the physical mapping of other chromosomes with three breakpoints on chromosomes 1, 4, 11 and 13 and two on chromosomes 3, 10 and 18.     

Response of cabbage head weight to simulated Lepidoptera defoliation

Studies were conducted to determine the effects of continuous constant amounts of artificial defoliation through the preheading and heading growth stages on head weight of cabbage. High levels of continuous artificial defoliation caused a reduction in head weight in all three years of the study, but the highest yield was always attained at some low level of preheading or heading defoliation. These results demonstrate that cabbage is tolerant to some levels of continuous defoliation before and after head formation. Results from this study are incorporated into a cost-benefit analysis to estimate an economic threshold.

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Résumé L'étude a porté sur le poids des pommes de choux (Brassica oleracea) soumis à différentes intensités de défoliations répétées avant et pendant la formation des pommes. Pendant les trois années de l'étude, huit intensités de défoliation continue ont réduit le poids des pommes, mais le poids le plus élevé a toujours été obtenu avec une faible défoliation avant et pendant la formation des pommes. Ceci montre que le chou tolère une certaine défoliation avant et pendant la formation des pommes. Les résultats de cette étude ont été utilisés dans une analyse coût-bénéfice pour estimer le seuil économique de défoliation.

     

Immunotherapy for remission maintenance in acute myeloblastic leukemia

Summary Forty-eight patients with acute myeloblastic leukemia in remission were treated with immunotherapy in addition to remission-maintenance chemotherapy. The first 16 patients were treated with weekly BCG and a leukemia cell vaccine (group 1). The next 32 patients were randomly allocated to receive BCG and a leukemia cell vaccine given once monthly (group 2) or BCG given monthly with no leukemia cell vaccine (group 3). There was no significant difference in remission duration or survival between the randomly allocated groups (2 and 3).Comparisons with group 1 are limited by the non-random allocation to this group, but selection bias was unlikely and clinical features were similar in the three patient groups. No significant difference in remission duration or survival was seen amongst the three groups studied. There was no advantage in the addition of leukemia cell vaccine (groups 1 and 2) to BCG alone (group 3) and no advantage to weekly (group 1) versus monthly immunotherapy (groups 2 and 3). Only 7 of the 48 patients achieved a second remission, and 4 of these were short-term partial remissions.The following are contributing members of the Toronto Leukemia Study Group: Doctor's Hospital, Harvey Silver MD; Humber Memorial Hospital, Alan Seidenfeld MD; Mississauga Hospital, Michael King MD; Mount Sinai Hospital, Dominic Amato MD; Northwestern Hospital, Wilhelm Kwant MD; Oshawa General Hospital, Hak Chiu MD; St Michael's Hospital, Bernadette Garvey MD, Kenneth Butler MD; St Joseph's Hospital, H. James Watt MD, Murray Davidson MD; Toronto General Hospital, Gerald Scott MD, William Francombe MD, Kenneth Shumak MD; John Crookston MD, PhD; Toronto Western Hospital, James G. Watt MD, David Sutton MD; Michael Baker MD; Domenic Pantalony MD; Wellesley Hospital, Dale Dotten MD; Women's College Hospital, George Kutas MD; York Finch Hospital, Sam Berger MD     

Direct evidence for the involvement of T suppressor cells in the expression of low-dose paralysis to type III pneumococcal polysaccharide

Prior treatment (priming) with a subimmunogenic dose of type III pneumococcal polysaccharide results in the development of an antigen-specific state of unresponsiveness termed low-dose paralysis. Such unresponsiveness can be transferred by spleen cells obtained from mice within 5 to 24 hr after priming; the suppressive activity of transferred cells is abolished by treatment with monoclonal anti-Thy-1.2 antibody and complement. These findings show clearly that low-dose paralysis is mediated by T suppressor cells.     

Comparison of rat and guinea pig as sources of the S9 fraction in the salmonella/mammalian microsome mutagenicity test

A highly significant enhancement of mutagenicity occurs with 11 polycyclic aromatic hydrocarbons when 3-methylcholanthrene-induced guinea pig liver S9 is substituted for Aroclor-induced rat liver S9 in the Ames test. The use of MC-induced guinea pig liver S9 is particularly valuable for detecting the weak mutagenicity of benz[c]acridine, which is barely positive in a standard Ames assay. However, anthracene and phenanthrene, which are generally considered not to be carcinogens, remain non-mutagenic for strain TA100. This enhancement of mutagenicity does not correlate with arylhydrocarbon hydroxylase activities of the various liver preparations and does not apply to certain other non-PAH mutagens, including β-naphthylamine, aflatoxin B₁ and 4-dimethylaminoazobenzene.     

Laboratory growth rates of six species of freshwater Gymnamoebia

Summary Amaranthus and several other wind-pollinated species of plants are used to test some of the theoretical models of relative reproductive effort towards the male and female sexes. Consistent with these models, in self-compatible, monoecious Amaranthus, Chenopodium, Digitaria, Setaria, and Lepidium, female effort represented over 90% of the total reproductive effort. Also consistent with predictions, Lolium, a self-incompatible wind-pollinated species, was found to have about equal male and female effort. A method is described here that should prove useful in quantifying male and female effort in both wind and insect-pollinated species of plants.