Expansion of human and murine hematopoietic stem and progenitor cells ex vivo without genetic modification using MYC and Bcl-2 fusion proteins

The long-term repopulating hematopoietic stem cell (HSC) population can self-renew in vivo, support hematopoiesis for the lifetime of the individual, and is of critical importance in the context of bone marrow stem cell transplantation. The mechanisms that regulate the expansion of HSCs in vivo and in vitro remain unclear to date. Since the current set of surface markers only allow for the identification of a population of cells that is highly enriched for HSC activity, we will refer to the population of cells we expand as Hematopoietic Stem and Progenitor cells (HSPCs). We describe here a novel approach to expand a cytokine-dependent Hematopoietic Stem and Progenitor Cell (HSPC) population ex vivo by culturing primary adult human or murine HSPCs with fusion proteins including the protein transduction domain of the HIV-1 transactivation protein (Tat) and either MYC or Bcl-2. HSPCs obtained from either mouse bone marrow, human cord blood, human G-CSF mobilized peripheral blood, or human bone marrow were expanded an average of 87 fold, 16.6 fold, 13.6 fold, or 10 fold, respectively. The expanded cell populations were able to give rise to different types of colonies in methylcellulose assays in vitro, as well as mature hematopoietic populations in vivo upon transplantation into irradiated mice. Importantly, for both the human and murine case, the ex vivo expanded cells also gave rise to a self-renewing cell population in vivo, following initial transplantation, that was able to support hematopoiesis upon serial transplantation. Our results show that a self-renewing cell population, capable of reconstituting the hematopoietic compartment, expanded ex vivo in the presence of Tat-MYC and Tat-Bcl-2 suggesting that this may be an attractive approach to expand human HSPCs ex vivo for clinical use.

Small-molecule inhibitors of Bcl-2 family proteins are able to induce tumor regression in a mouse model of pre-B-cell acute lymphocytic lymphoma

The overexpression of prosurvival members of the Bcl-2 family is commonly associated with the enhanced malignancy of hematological tumors. There has been great interest in a novel set of agents that are able to mimic the function of the BH3 domain by binding to the groove of Bcl-2-like proteins and initiating the cell death sequence. We sought to examine the efficacy of BH3 mimetics in a spontaneous mouse model of B-cell neoplasia. We evaluated the ability of the BH3 mimetics to preferentially target tumor cells while sparing normal cells. In addition, we examined the contributions of Bim and Puma to the sensitivity of tumor cells to the BH3 mimetics. We report here that two BH3 mimetics (HA-14-1 and BH3-I-2') were able to induce apoptosis of murine B-cell lymphoma cells in vitro and in vivo. Tumors that arose from transplantation of primary lymphoma cells regressed following 7 days of treatment with BH3-mimetic drugs. The long-term benefits of the transient treatment of tumor-bearing mice with the BH3 mimetics, however, could not be properly evaluated, due to the high levels of toxicity we observed in vivo with these drugs. Decreased expression of either Bim or Puma from B-cell tumor cells was able to protect these cells from the apoptosis induced by these BH3 mimetics, suggesting that they function through other means. We conclude that while the BH3-mimetic drugs are effective at inducing cell death of lymphoma cells in vitro and in vivo, their unclear molecular specificity and their ability to kill normal cells may limit their therapeutic uses in humans.

Substitutions of conserved amino acids in the receptor-binding domain of the spike glycoprotein affect utilization of murine CEACAM1a by the murine coronavirus MHV-A59

The host range of the murine coronavirus (MHV) is limited to susceptible mice and murine cell lines by interactions of the spike glycoprotein (S) with its receptor, mCEACAM1a. We identified five residues in S (S33, L79, T82, Y162 and K183) that are conserved in the receptor-binding domain of MHV strains, but not in related coronaviruses. We used targeted RNA recombination to generate isogenic viruses that differ from MHV-A59 by amino acid substitutions in S. Viruses with S33R and K183R substitutions had wild type growth, while L79A/T82A viruses formed small plaques. Viruses with S33G, L79M/T82M or K183G substitutions could only be recovered from cells that over-expressed a mutant mCEACAM1a. Viruses with Y162H or Y162Q substitutions were never recovered, while Y162A viruses formed minute plaques. However, viruses with Y162F substitutions had wild type growth, suggesting that Y162 may comprise part of a hydrophobic domain that contacts the MHV-binding site of mCEACAM1a.

The protooncogene MYC can break B cell tolerance

The protooncogene MYC has been implicated in both the proliferation and programmed cell death of lymphoid cells, and in the genesis of lymphoid tumors. Here, we report that overexpression of MYC, as found in many lymphomas, can break immune tolerance. Mice that would otherwise be tolerant to a transgenic autoantigen mounted an immune response to the antigen if MYC was vigorously expressed in the B cell lineage. The responsive B cells converted to an activated phenotype and produced copious amounts of autoantibody that engendered immune complex disease of the kidney. MYC was required to both establish and maintain the breach of tolerance. These effects may be due to the ability of MYC to serve as a surrogate for cytokines. We found that the gene could mimic the effects of cytokines on both B cell proliferation and survival and, indeed, was required for those effects. These findings demonstrate a critical role for MYC in the response of B cells to antigen and expand the potential contributions of MYC to the genesis of lymphomas.

Receptor-dependent coronavirus infection of dendritic cells

In several mammalian species, including humans, coronavirus infection can modulate the host immune response. We show a potential role of dendritic cells (DC) in murine coronavirus-induced immune modulation and pathogenesis by demonstrating that the JAW SII DC line and primary DC from BALB/c mice and p/p mice with reduced expression of the murine coronavirus receptor, murine CEACAM1a, are susceptible to murine coronavirus infection by a receptor-dependent pathway.

The effect of evening alcohol consumption on next-morning glucose control in type 1 diabetes

OBJECTIVE

Alcohol is associated with acute hypoglycemia in patients with type 1 diabetes. After drinking alcohol in the evening, delayed hypoglycemia has also been described, although its cause is unknown. We performed a controlled study to investigate this phenomenon.

RESEARCH DESIGN AND METHODS

We admitted six men with type 1 diabetes (aged 19-51 years, HbA(1c) 7.0-10.3%) on two occasions, from 5:00 P.M. to 12:00 noon the following day. They received regular insulin injections before standardized meals, at 6:00 P.M. and 8:00 A.M., and a basal insulin infusion (0.15 mU x kg(-1) x min(-1)) from 11:00 P.M. They drank either dry white wine (0.75 g/kg alcohol) or mineral water at 9:00 P.M. over 90 min. Blood glucose, alcohol, insulin, cortisol, growth hormone, and glucagon levels were measured.

RESULTS

Blood ethanol reached a mean (SEM) peak of 19.1 (1.2) mmol/l and was undetectable by 8:00 A.M. There were no significant differences in evening or overnight blood glucose levels between the studies. In the morning, fasting and postprandial blood glucose levels were significantly lower after consumption of wine (postprandial peak 8.9 [1.7] vs. 15 [1.5] mmol/l, P < 0.01), and from 10:00 A.M., five subjects required treatment for hypoglycemia (nadir 1.9-2.9 mmol/l). None of the subjects had hypoglycemia after consumption of water. After consumption of wine, growth hormone secretion was significantly reduced between midnight and 4:00 A.M. (area under the curve 2.1 [1.1] vs. 6.5 [2.1] microg. l(-1) x h(-1), P = 0.04). There were no differences in insulin or other hormone levels.

CONCLUSIONS

In type 1 diabetes, moderate consumption of alcohol in the evening may predispose patients to hypoglycemia after breakfast the next morning. This is associated with reduced nocturnal growth hormone secretion. Patients should be informed of this risk and advised regarding appropriate preventative measures.

Neurospora from Natural Populations: A Global Study

This is a summary report on samples of conidiating Neurospora species collected over three decades, in many regions around the world, primarily from burned vegetation. The genus is ubiquitous in humid tropical and subtropical regions, but populations differ from region to region with regard to which species are present. The entire collection, >4600 cultures from 735 sites, is listed by geographical origin and species. Over 600 cultures from 78 sites have been added since the most recent report. Stocks have been deposited at the Fungal Genetics Stock Center. New cultures were crossed to testers for species identification; evident mixed cultures were separated into pure strains, which were identified individually. New techniques and special testers were used to analyze cultures previously listed without species identification. The discussion summarizes what has been learned about species and natural populations, describes laboratory investigations that have employed wild strains, and makes suggestions for future work.

Geographic Distribution of Neurospora Spore Killer Strains and Strains Resistant to Killing

Spore killer strains, found in Neurospora, provided the first recognized example of meiotic drive in fungi. In the present study, natural populations throughout the world were examined for the presence of killer strains and strains that are resistant to killing. In N. intermedia, Sk-2 and Sk-3 are present but are rare. Killer strains were found at only five sites, in Borneo, Java, and Papua New Guinea. Nonkiller strains that are resistant to killing by Sk-2 or Sk-3 are frequent in that part of the world where the killer strains are present, but resistant stains were not found in regions where killers are absent. In N. sitophila, Sk-1 killer strains are common in nature, but only 1 of 392 nonkiller strains was resistant. In N. crassa, no killer strain was found among >500, but widely scattered Sk-2-resistant strains were present, suggesting the past or present existence of killers.

BAG-1: a novel biomarker predicting long-term survival in early-stage breast cancer

PURPOSE

Among women with early-stage breast cancer treated with lumpectomy and radiation therapy, 30% to 40% will develop metastatic disease, which is often fatal. A need exists therefore for biomarkers that distinguish patients at high risk of relapse. We performed a retrospective correlative analysis of BAG-1 protein expression in breast tumors derived from a cohort of early-stage breast cancer patients.

PATIENTS AND METHODS

Archival paraffin blocks from 122 women with stages I to II breast cancer treated with lumpectomy and radiation therapy (median follow-up, 12.1 years) were analyzed by immunohistochemical methods using monoclonal antibodies recognizing BAG-1 and other biomarkers, including Bcl-2, estrogen receptor, progesterone receptor, p53, and HER2/Neu. Immunostaining data were correlated with distant metastasis-free survival (DMFS) and overall survival (OS).

RESULTS

Cytosolic immunostaining for BAG-1 was upregulated in 79 (65%) of 122 invasive breast cancers (P <.001) compared with normal breast. Elevated BAG-1 was significantly associated with longer DMFS and OS, overall (stages 1 and II) and in node-negative (stage I only) patients, on the basis of univariate and multivariate analyses (DMFS, P =.005; OS, P =.01, in multivariate analysis of all patients; DMFS, P =.005; OS, P =.001, in multivariate analysis of node-negative patients). All other biomarkers failed to reach statistical significance in multivariate analysis. Clinical stage was an independent predictor of OS (P =.04) and DMFS (P =.02).

CONCLUSION

These findings provide preliminary evidence that BAG-1 represents a potential marker of improved survival in early-stage breast cancer patients, independent of the status of axillary lymph nodes.

Impaired absorption and omission of insulin: a novel method of detection using the diabetes advisory system computer model

The Diabetes Advisory System (DIAS) is a decision-support program developed to assist insulin dose adjustment in type 1 diabetes. In this paper, we show how it might be used to identify impaired absorption or omission of insulin in patients with poorly controlled blood glucose. An evaluation of glucose results from four outpatients with persistent hyperglycemia is presented (age 19-48 years with type 1 diabetes for 13-18 years of duration, HbA1c 9.4-13.6%). Each had completed a 4-day record of blood glucose (BG, pre-meal and bedtime), dietary (carbohydrate) intake, and insulin doses (with injection sites). From these data, DIAS modeled a glucose profile (simulated glucose, SG) for the same period. Qualitative assessments were made of differences between BG and SG, and selective reduction or complete removal of insulin doses where BG >> SG. Large improvements in modeling were attributed to either impaired absorption or omission of insulin. Confirmation of these problems was sought from the patients by detailed consultation and physical examination. Impaired insulin absorption was suspected in two patients, both having significant injection site abnormalities. Insulin omission was suspected in the other two subjects. Both had normal injection sites, and one admitted to missing doses. Following retraining, data from three patients showed noticeable improvements in overall modeling as well as glucose control. Using DIAS in the evaluation of patients with type 1 diabetes may highlight previously unrecognized injection site abnormalities or insulin dose omission. This could assist rational optimization of insulin therapy in cases of persistently poor glucose control.

True recurrence vs. new primary ipsilateral breast tumor relapse: an analysis of clinical and pathologic differences and their implications in natural history, prognoses, and therapeutic management

PURPOSE

The purpose of this study was to classify all ipsilateral breast tumor relapses (IBTR) in patients treated with conservative surgery and radiation therapy (CS+RT) as either new primary tumors (NP) or true local recurrences (TR) and to assess the prognostic and therapeutic implications of this classification.

METHODS AND MATERIALS

Of the 1152 patients who have been treated at Yale-New Haven Hospital before 1990, 136 patients have experienced IBTR as their primary site of failure. These relapses were classified as either NP or TR. Specifically, patients were classified as NP if the recurrence was distinctly different from the primary tumor with respect to the histologic subtype, the recurrence location was in a different location, or if the flow cytometry changed from aneuploid to diploid. This information was determined by a detailed review of each patient's hospital and/or radiotherapy record, mammograms, and pathologic reports.

RESULTS

As of 2/99, with a mean follow-up of 14. 2 years, the overall ipsilateral breast relapse-free rate for all 1152 patients was 86% at 10 years. Using the classification scheme outlined above, 60 patient relapses were classified as TR, 70 were classified as NP and 6 were unable to be classified. NP patients had a longer mean time to breast relapse than TR patients (7.3 years vs. 3.7 years, p < 0.0001) and were significantly younger than TR patients (48.9 years vs. 54.5 years, p < 0.01). Patients developed both TR and NP at similar rates until approximately 8 years, when TR rates stabilized but NP rates continued to rise. By 15 years following original diagnosis, the TR rate was 6.8% compared to 13.1% for NP. Of the patients who had been previously tested for BRCA1/2 mutations, 17% (8/52) had deleterious mutations. It is noteworthy that all patients with deleterious mutations had new primary IBTR, while patients without deleterious mutations had both TR and NP (p = 0.06). Ploidy was evenly distributed between TR and NP but NP had a significantly lower S phase fraction (NP 13.1 vs. TR 22.0, p < 0.05). The overall survival following breast relapse was 64% at 10 years and 49% at 15 years. With a mean follow-up of 10.4 years following breast relapse, patients with NP had better 10-year overall survival (TR 55% vs. NP 75%, p < 0.0001), distant disease-free survival (TR 41% vs. NP 85%, p < 0.0001), and cause-specific survival (TR 55% vs. NP 90%, p < 0.0001).

CONCLUSION

It appears that a significant portion of patients who experience ipsilateral breast tumor relapse following conservative surgery and radiation therapy have new primary tumors as opposed to true local recurrences. True recurrence and new primary tumor ipsilateral breast tumor relapses have different natural histories, different prognoses, and, in turn, different implications for therapeutic management.

Cyclin D1 expression and early breast cancer recurrence following lumpectomy and radiation

PURPOSE

The purpose of this study was to determine the prognostic significance of cyclin D1 (cycD1) levels in ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy.

METHODS AND MATERIALS

A total of 98 patients (49 patients with IBTR and 49 matched cases without IBTR) selected from our conservatively treated breast cancer population served as the patient population for the current study. All patients were treated with lumpectomy followed by radiation therapy to the intact breast to a total median dose of 64 Gy. The patients were followed in our clinic with a median follow-up of 13 years. Immunohistochemical analysis of cycD1 in these 98 early-stage breast cancer patients was performed using a polyclonal antibody generated against the human cycD1 protein. All clinical, pathologic, and molecular variables were entered into a computerized data base for statistical analysis.

RESULTS

Low levels of immunohistochemically detected cycD1 protein correlated with IBTR (p = 0.001), but there was no association between cycD1 protein levels and metastatic disease, axillary lymph node involvement, distant disease-free survival (DDFS), and overall survival (OS). Subgroup analysis revealed that for early breast tumor relapses (within 4 years of initial breast tumor diagnosis), low levels of cycD1 were associated with IBTR (p = 0.004), but cycD1 expression was not prognostic for IBTR from breast cancer patients with late relapses (p = NS).

CONCLUSION

These studies provide in vivo evidence for the prognostic and biologic significance of cycD1 expression in determining response to radiation therapy in breast cancer patients.

Rapid communication: development of in vitro resistance to macrophage-tropic- and T-cell-line-adapted HIV-1 strains among HIV-positive volunteers treated with highly active antiretroviral therapy

We have described a peripheral blood mononuclear cell (PBMC) culture system in which control of endogenous virus and resistance to exogenous HIV-1 correlates with low viremia among HIV-1-positive people. Nineteen patients remained consistently resistant or susceptible for more than 5 years of follow-up. On the fifth year, 5 consistently susceptible volunteers with high viral loads began receiving highly active anti-retroviral therapy (HAART). After >6 months on HAART, 5 of 5 became completely or predominantly resistant on four visits over the next 6 months. Among HIV-1-positive donors, we had never observed reversal of PBMC phenotype from consistently susceptible to consistently resistant. Resistance correlated with suppression of plasma viremia and rebound in CD4+ T-cell counts and percentages. When resistant PBMCs were challenged after CD8+ T-cell depletion, 38 of 41 and 40 of 59 cultures became susceptible to HIV-1MN and HIV-1BaL, respectively. After combined CD8+ T-cell depletion and antibody neutralization of beta-chemokines, 16 of 18 cultures became susceptible to HIV-1BaL. Overall, the finding that >90% of these cultures depleted of relevant antiviral effector arms could become infected indicates resistance was not due to residual antiretroviral drug metabolites in vitro. For 2 volunteers who discontinued therapy because of side effects, pretreatment viral load correlated with loss of in vitro resistance and viral rebound. In addition to resistance to laboratory strains of HIV-1, all patients developed resistance to at least one of two CCR5-tropic, clade B primary isolates: HIV-1P15 and HIV-1P27.

What do patients with diabetes know about their tablets?

AIMS

To assess knowledge about oral hypoglycaemic agents amongst patients with diabetes and non-specialist healthcare professionals.

METHOD

An anonymous questionnaire was used in two centres to assess knowledge about oral agents amongst 261 patients with Type 2 diabetes mellitus (mean age 64 years) and 102 health professionals (including doctors, nurses and pharmacists).

RESULTS

Only 15% of patients knew the correct mechanism of action of their medication and 62% took tablets correctly in relation to food. Only 10% of those taking a sulphonylurea knew it may cause hypoglycaemia and 20% of those taking metformin were aware of its gastrointestinal side-effects. Twenty per cent forgot to take their tablets at least once a week and 5% omitted tablets because of hyperglycaemia. Only 35% of patients recalled receiving advice about their medication with only 1% receiving written advice. The healthcare professionals showed important gaps in their knowledge on dosage timing and mechanism of action, particularly with respect to metformin and acarbose.

CONCLUSION

It is concluded that patients' and professionals' knowledge of oral hypoglycaemic agents is poor. More appropriate advice and information to patients from prescribers may improve patient understanding and hence compliance. Community pharmacists are ideally placed to reinforce this information.

Mutant p53 protein overexpression in women with ipsilateral breast tumor recurrence following lumpectomy and radiation therapy

BACKGROUND

The p53 tumor suppressor gene encodes a nuclear phosphoprotein that is thought to be important to cell cycle regulation and DNA repair and that also may regulate induction of apoptosis by ionizing radiation. Somatic p53 gene mutations occur in 30-50% of breast carcinomas and are associated with poor prognosis. Mutations in the p53 gene result in prolonged stability of the protein that can be detected by immunohistochemical techniques. In a matched case-control study of breast carcinoma patients with ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy, the authors investigated the frequency and prognostic significance of somatic p53 mutations as well as the clinical characteristics of patients with these mutations.

METHODS

Between 1973 and 1995, there were 121 breast carcinoma patients with IBTR following lumpectomy and radiation therapy, and the authors identified 47 patients in whom the paraffin embedded tissue blocks from the primary breast tumors were available for further molecular analysis. Forty-seven control breast carcinoma patients from the breast carcinoma data base were individually matched to the index cases who did not have IBTR for age, treatment date, follow-up, histology, margin status, radiation dose, and adjuvant treatment. Immunohistochemistry using a monoclonal antibody to mutant p53 protein was used to determine mutant p53 protein overexpression in breast tumors and appropriately scored.

RESULTS

A total of 12 of 47 tumor specimens (26%) from index patients with breast tumor relapses demonstrated mutant p53 protein overexpression, whereas only 4 of 47 specimens from controls (9%) demonstrated high mutant p53 immunoreactivity (P = 0.02). The authors found that 9 of 23 patients (39%) with early breast tumor recurrences (recurrences within 4 years of diagnosis) had overexpression of mutant p53 protein, whereas only 1 of 23 control cases (4%) had high mutant p53 protein immunoreactivity (P = 0.003). In contrast, index cases from patients with late breast tumor relapses (more than 4 years after diagnosis), which are more likely to represent de novo breast tumors, and control cases from the breast carcinoma data base without IBTR had similar levels of mutant p53 protein overexpression (P = not significant). The 10-year distant disease free survival for patients with mutant p53 protein was 48%, compared with 67% for breast carcinoma patients without detection of mutant p53 protein (P = 0. 08). The authors found that 13 of 14 primary breast tumors (93%) with mutant p53 protein overexpression were estrogen receptor negative (P = 0.01) and 11 of 14 (79%) were progesterone receptor negative (P = not significant).

CONCLUSIONS

In a matched case-control study, overexpression of mutant p53 protein has prognostic significance with respect to IBTR following lumpectomy and radiation therapy. Breast tumors with p53 mutations are generally estrogen receptor negative and are associated with compromised distant disease free survival.

Prognostic significance of cyclin D1 protein levels in early-stage larynx cancer treated with primary radiation

Recent laboratory experiments have demonstrated that cyclin D1 levels (cycD1) can influence radiosensitivity. The purpose of the current study is to evaluate the prognostic significance of cycD1 for local recurrence in early-stage larynx cancer treated with primary radiation therapy. The study was conducted using a matched case-control design in 60 early-stage (T1-T2/N0) larynx cancer patients. All patients had squamous cell carcinoma of the larynx and were treated with primary radiation to a total median dose of 66 Gy in daily fractions of 2 Gy, without surgery or chemotherapy. Thirty patients who suffered a local relapse in the larynx after treatment served as the index case population. These 30 cases were matched by age, sex, site (glottic vs. supraglottic), radiation therapy technique/dose, and follow-up, to 30 control patients who did not experience a local relapse. Immunohistochemical staining from cycD1 was performed on the paraffin-embedded specimens. The pathologist, blinded to the clinical information, scored each of the specimens on a four-point intensity scale (0 = no stain, 1 = faint, 2 = moderate, 3 = strong) and percent distribution. Patients were considered to be positive for cyclin D1 if the staining was 2+ or greater with a percent distribution of at least 5%. By design of the study, the two groups were evenly balanced with respect to age, sex, stage, radiation dose, and follow-up. CycD1 levels correlated with proliferating cell nuclear antigen levels. Low levels of cycD1 significantly correlated with local relapse; 19/30 (63%) of the index cases stained negative, while only 10/30 (33%) of the control cases stained negative (P = 0.03). These data suggest that low levels of cycD1 correlate with relatively radioresistant early-stage larynx carcinoma. With larger more confirmatory clinical and laboratory data, this data may have significant clinical implications. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 22-28 (2000).

Elevated frequency and functional activity of a specific germ-line p53 intron mutation in familial breast cancer

Previous studies have determined that the frequency of germ-line p53 mutations in familial breast cancer patients is 1% or less, but these reports have not investigated the importance of polymorphic intron base changes in the p53 gene. Therefore, we investigated the frequency of both exon and intron germ-line p53 base changes in 42 breast cancer patients with a strong family history of breast cancer. The mean age of presentation of these patients was 44.0 years (range, 29-69), and 12 of 42 (29%) were of known Ashkenazi ancestry. Purified DNA obtained from the 42 index cases was screened for germ-line p53 mutations in exons 2-11 and surrounding introns using a combination of intron based primers for PCR-single strand conformation polymorphism analysis, direct sequencing, and microarray sequencing using the Affymetrix p53 gene chip methodology. Morphological analysis of apoptosis and cell survival determination were performed on EBV-immortalized lymphoblastoid cell lines from two patients with the p53 intron 6 mutation. A germ-line mutation in the p53 gene at nucleotide 13964 with a G to C base change (13964GC) was identified in 3 of 42 (7.1%) hereditary breast cancer patients. Two patients were heterozygous for this mutation, and one patient had a homozygous mutation. In comparison, 0 of 171 (0%) of sporadic breast cancer patients had the p53 13964GC mutation (P = 0.0003). We found that 0 of 42 (0%) of these hereditary breast cancer patients had other germ-line p53 mutation in exons 2-11. However, pedigree analysis demonstrated that all three patients had strong family histories of multiple types of cancers consistent with Li-Fraumeni syndrome but with late age of onset. Comprehensive BRCA1 and BRCA2 nucleotide analysis from patients with the p53 13964GC mutation revealed no concomitant deleterious BRCA1 or BRCA2 mutations, although they were found in the other hereditary breast cancer patients. Functional analysis of two immortalized lymphoblastoid cell lines derived from patients with the p53 13964GC mutation demonstrated prolonged in vitro survival in response to cisplatinum treatment and showed decreased chemotherapy-induced apoptosis. Immunohistochemical analysis of breast tumors from these patients revealed high levels of mutant p53 protein, suggesting a functional mutation in the p53 gene. In summary, we have identified a single p53 intron mutation in familial breast cancer patients that is present at elevated frequency and has functional activity.

BRCA1/BRCA2 germline mutations in locally recurrent breast cancer patients after lumpectomy and radiation therapy: implications for breast-conserving management in patients with BRCA1/BRCA2 mutations

PURPOSE

Breast cancer patients treated conservatively with lumpectomy and radiation therapy (LRT) have an estimated lifetime risk of local relapse (ipsilateral breast tumor recurrence [IBTR]) of 10% to 15%. For breast cancer patients carrying BRCA1 or BRCA2 (BRCA1/2) mutations, the outcome of treatment with LRT with respect to IBTR has not been determined. In this study, we estimate the frequency of BRCA1/2 mutations in a study of breast cancer patients with IBTR treated with LRT.

PATIENTS AND METHODS

Between 1973 and 1994, there were 52 breast cancer patients treated with LRT who developed an IBTR within the prior irradiated breast and who were willing to participate in the current study. From our database, we also identified 52 control breast cancer patients treated with LRT without IBTR. The control patients were individually matched to the index cases with respect to multiple clinical and pathologic parameters. Lymphocyte DNA specimens from all 52 locally recurrent patients and 15 of the matched control patients under age 40 were used as templates for polymerase chain reaction amplification and dye-primer sequencing of exons 2 to 24 of BRCA1, exons 2 to 27 of BRCA2, and flanking intron sequences.

RESULTS

After LRT, eight (15%) of 52 breast cancer patients had IBTR with deleterious BRCA1/2 mutations. By age, there were six (40%) of 15 patients with IBTR under age 40 with BRCA1/2 mutations, one (9.0%) of 11 between ages 40 and 49, and one (3.8%) of 26 older than age 49. In comparison to the six (40%) of 15 of patients under age 40 with IBTR found to have BRCA1/2 mutations, only one (6.6%) of 15 matched control patients without IBTR and had a BRCA1/2 mutation (P =.03). The median time to IBTR for patients with BRCA1/2 mutations was 7.8 years compared with 4.7 years for patients without BRCA1/2 mutations (P =.03). By clinical and histologic criteria, these relapses represented second primary tumors developing in the conservatively treated breast. All patients with BRCA1/2 mutations and IBTR underwent successful surgical salvage mastectomy at the time of IBTR and remain alive without evidence of local or systemic progression of disease.

CONCLUSION

In this study, we found an elevated frequency of deleterious BRCA1/2 mutations in breast cancer patients treated with LRT who developed late IBTR. The relatively long time to IBTR, as well as the histologic and clinical criteria, suggests that these recurrent cancers actually represent new primary breast cancers. Early onset breast cancer patients experiencing IBTR have a disproportionately high frequency of deleterious BRCA1/2 mutations. This information may be helpful in guiding management in BRCA1 or BRCA2 patients considering breast-conserving therapy.

Prognostic significance of apoptosis regulators in breast cancer

Dysregulation of normal programmed cell death mechanisms plays an important role in the pathogenesis and progression of breast cancer, as well as in responses of tumors to therapeutic intervention. Overexpression of anti-apoptotic members of the Bcl-2 family such as Bcl-2 and Bcl-X(L) has been implicated in cancer chemoresistance, whereas high levels of pro-apoptotic proteins such as Bax promote apoptosis and sensitize tumor cells to various anticancer therapies. Though the mechanisms by which Bcl-2 family proteins regulate apoptosis are diverse, ultimately they govern decision steps that determine whether certain caspase family cell death proteases remain quiescent or become active. To date, approximately 17 cellular homologs of Bcl-2 and at least 15 caspases have been identified in mammals. Other types of proteins may also modulate apoptotic responses through effects on apoptosis-regulatory proteins, such as BAG-1-a heat shock protein 70 kDa (Hsp70/Hsc70)-binding protein that can modulate stress responses and alter the functions of a variety of proteins involved in cell death and division. In this report, we summarize our attempts thus far to explore the expression of several Bcl-2 family proteins, caspase-3, and BAG-1 in primary breast cancer specimens and breast cancer cell lines. Moreover, we describe some of our preliminary observations concerning the prognostic significance of these apoptosis regulatory proteins in breast cancer patients, contrasting results derived from women with localized disease (with or without node involvement) and metastatic cancer.

Expression of AP-2 transcription factors in human breast cancer correlates with the regulation of multiple growth factor signalling pathways

The AP-2 transcription factors are required for normal growth and morphogenesis during mammalian development. Previous in vitro studies have also indicated that the AP-2 family of proteins may be involved in the etiology of human breast cancer. The AP-2 genes are expressed in many human breast cancer cell lines, and critical AP-2-binding sites are present in both the ERBB-2 (HER2/neu) and estrogen receptor promoters. We have now characterized immunological reagents that enable specific AP-2 family members, including AP-2alpha and AP-2gamma, to be detected in human breast cancer epithelium. Data obtained with these reagents demonstrate that whereas AP-2alpha and AP-2gamma are both present in benign breast epithelia, there is a significant up-regulation of AP-2gamma expression in breast cancer specimens (P = 0.01). There was also a significant correlation between the presence of the AP-2alpha protein and estrogen receptor expression (P = 0.018) and between specimens containing both AP-2alpha/AP-2gamma proteins and ERBB-2 expression (P = 0.003). Furthermore, we detected an association (P = 0.04) between the expression of AP-2gamma and the presence of an additional signal transduction molecule implicated in breast cancer, the insulin-like growth factor I receptor. Analysis of the proximal promoter of the insulin-like growth factor I receptor revealed a novel AP-2-binding site. Thus, AP-2 proteins may directly regulate the transcription of this growth factor receptor. Taken together, these data strongly support a role for the AP-2 gene family in the control of cell growth and differentiation in breast cancer.

Local recurrence in the conservatively treated breast cancer patient: a correlation with age and family history

BACKGROUND

The purpose of this study was to evaluate the relationships among young age at diagnosis, family history status, and local recurrence in breast cancer patients treated with lumpectomy and radiation therapy.

METHODS

Between January 1970 and December 1990, 984 early-stage breast cancer patients were treated with conservative surgery and radiation therapy at Yale-New Haven Hospital. All patient data, including demographics, staging information, treatment, and outcome variables were entered into a computerized database. The current study focused on the relationships between young age, family history, and local relapse. A group of 52 patients who experienced a local recurrence in the conservatively treated breast and 52 matched control patients who had not experienced a local recurrence were asked to participate in a study to determine whether local recurrence was associated with family history. Detailed family history interviews were conducted, and pedigrees were analyzed by a genetic counselor who was blind to the clinical history of the patients.

RESULTS

As of September 1997, with a median follow-up of 12.3 years for the 984 patients in the database, the overall actuarial 10-year survival is 73%, and the 10-year distant metastasis-free survival is 78%. Of the 984 patients, 112 have experienced a local relapse in the conservatively treated breast, resulting in a 10-year actuarial breast relapse rate of 15%. The 10-year survival after breast relapse is 69%. Patient age tested as a continuous variable correlated strongly with ipsilateral breast tumor relapse. Using age 40 as a cutpoint, patients aged 40 years or less had a significantly higher local relapse rate than patients older than 40 years (P < 0.001). Although the relationship between local relapse and young age was strong, no association was found between family history and local relapse in the detailed family history study.

CONCLUSIONS

Young age at diagnosis was a significant prognostic factor for local relapse. In a detailed family history study using a case-control design, no significant differences in family history status were found between patients who had experienced a local relapse and patients who had not.

Effective treatment of stage I uterine papillary serous carcinoma with high dose-rate vaginal apex radiation (192Ir) and chemotherapy

PURPOSE

Uterine papillary serous carcinoma (UPSC) is a morphologically distinct variant of endometrial carcinoma that is associated with a poor prognosis, high recurrence rate, frequent clinical understaging, and poor response to salvage treatment. We retrospectively analyzed local control, actuarial overall survival (OS), actuarial disease-free survival (DFS), salvage rate, and complications for patients with Federation International of Gynecology and Obstetrics (FIGO) (1988) Stage I UPSC.

METHODS AND MATERIALS

This retrospective analysis describes 38 patients with FIGO Stage I UPSC who were treated with the combinations of radiation therapy, chemotherapy, total abdominal hysterectomy, and bilateral salpingo-oophorectomy (TAH/BSO), with or without a surgical staging procedure. Twenty of 38 patients were treated with a combination of low dose-rate (LDR) uterine/vaginal brachytherapy using 226Ra or 137Cs and conventional whole-abdomen radiation therapy (WART) or whole-pelvic radiation therapy (WPRT). Of 20 patients (10%) in this treatment group, 2 received cisplatin chemotherapy. Eighteen patients were treated with high dose-rate (HDR) vaginal apex brachytherapy using 192Ir with an afterloading device and cisplatin, doxorubicin, and cyclophosphamide (CAP) chemotherapy (5 of 18 patients). Only 6 of 20 UPSC patients treated with combination LDR uterine/vaginal brachytherapy and conventional external beam radiotherapy underwent complete surgical staging, consisting of TAH/BSO, pelvic/para-aortic lymph node sampling, omentectomy, and peritoneal fluid analysis, compared to 15 of 18 patients treated with HDR vaginal apex brachytherapy.

RESULTS

The 5-year actuarial OS for patients with complete surgical staging and adjuvant radiation/chemotherapy treatment was 100% vs. 61% for patients without complete staging (p = 0.002). The 5-year actuarial OS for all Stage I UPSC patients treated with postoperative HDR vaginal apex brachytherapy and systemic chemotherapy was 94% (18 patients). The 5-year actuarial OS for Stage I UPSC patients treated with HDR vaginal apex brachytherapy and chemotherapy who underwent complete surgical staging was 100% (15 patients). The 5-year actuarial OS for the 20 Stage I UPSC patients treated with combinations of pre- and postoperative LDR brachytherapy and postop WART was 65%. None of the 6 surgically staged UPSC patients treated with LDR radiation and WART/WPRT developed recurrent disease. For patients with FIGO Stage IA, IB, and IC UPSC who underwent complete surgical staging, the 5-year actuarial DFS by depth of myometrial invasion was 100, 71, and 40%, respectively (p = 0.006). The overall salvage rate for local and distant recurrence was 0%. Complications following HDR vaginal apex brachytherapy included only Radiation Therapy Oncology Group (RTOG) grade 1 and 2 toxicity in 16% of patients. However, complications from patients treated with WART/WPRT, and/or LDR brachytherapy, included RTOG grade 3 and 4 toxicity in 15% of patients.

CONCLUSION

Patients with UPSC should undergo complete surgical staging, and completely surgically staged FIGO Stage I UPSC patients can be effectively and safely treated with HDR vaginal apex brachytherapy and chemotherapy. Both OS and DFS of patients with UPSC are dependent on depth of myometrial invasion. The salvage rate for both local and distant UPSC recurrences is extremely poor. Complications from HDR vaginal apex brachytherapy were minimal.

Insulin-like growth factor-I receptor overexpression mediates cellular radioresistance and local breast cancer recurrence after lumpectomy and radiation

The insulin-like growth factor-I receptor (IGF-IR) plays a critical role in cell growth regulation and transformation. The radiosensitivity of NIH 3T3 fibroblasts overexpressing either wild-type or mutant IGF-IR was examined. High levels of wild-type IGF-IR conferred radioresistance, and mutational analysis revealed that this effect correlated with the transforming capacity but not the mitogenic activity of the receptor. The radioresistant phenotype was reversed when the cells were incubated with antisense oligonucleotides targeted to IGF-IR mRNA, demonstrating that IGF-IR directly influences radioresistance. The clinical significance of these findings was examined in an immunohistochemical analysis of primary breast tumors, revealing that high levels of IGF-IR in tumor samples were highly correlated with ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy (P = 0.001). Subgroup analysis revealed that, for early breast tumor relapses (within 4 years of initial breast tumor diagnosis), elevated levels of IGF-IR were strongly associated with IBTR (P = 0.004) but IGF-IR expression was not prognostic for IBTR from breast cancer patients with late relapses (P was not significant). These studies provide evidence for the influence of IGF-IR on cellular radioresistance and response to therapy and raise the possibility that the radiocurability of selected tumors may be improved by pharmaceutical strategies directed toward the IGF-IR.

Cytogenetics of an intrachromosomal transposition in Neurospora

Knowledge of intrachromosomal transpositions has until now been primarily cytological and has been limited to Drosophila and to humans, in both of which segmental shifts can be recognized by altered banding patterns. There has been little genetic information. In this study, we describe the genetic and cytogenetic properties of a transposition in Neurospora crassa. In Tp(IR-->IL)T54M94, a 20 map unit segment of linkage group I has been excised from its normal position and inserted near the centromere in the opposite arm, in inverted order. In crosses heterozygous for the transposition, about one-fifth of surviving progeny are duplications carrying the transposed segment in both positions. These result from crossing over in the interstitial region. There is no corresponding class of progeny duplicated for the interstitial segment. The duplication strains are barren in test crosses. A complementary deficiency class is represented by unpigmented, inviable ascospores. Extent of the duplication was determined by duplication-coverage tests. Orientation of the transposed segment was determined using Tp x Tp crosses heterozygous for markers inside and outside the transposed segment, and position of the insertion relative to the centromere was established using quasi-ordered half-tetrads from crosses x Spore killer. Quelling was observed in the primary transformants that were used to introduce a critical marker into the transposed segment by repeat-induced point mutation (RIP).

Protooncogene-encoded protein kinases in interleukin-2 signal transduction

Protooncogenes are the normal forms of cellular genes that when altered in their expression or coding sequences can contribute to neoplastic transformation. As these genes often are important for normal cellular growth control, we explored the possibility that protein kinases encoded by particular protooncogenes could participate in signal transduction pathways regulated by the T cell growth factor, interleukin-2 (IL-2). In this review we summarize our findings to date regarding Raf-1, a serine/threonine-specific kinase that becomes phosphorylated on tyrosine residues and enzymatically activated in response to IL-2 stimulation. In addition, we describe our investigations of Lck and Lyn, two closely related protein tyrosine kinases of the src gene family that physically associate with the IL-2 receptor complex and whose activities are regulated by IL-2 in at least some T cells and B cells, respectively.

Interleukin 2 regulates Raf-1 kinase activity through a tyrosine phosphorylation-dependent mechanism in a T-cell line

Previously we found that interleukin 2 (IL-2) induces tyrosine phosphorylation and activation of the serine/threonine-specific kinase encoded by the raf-1 protooncogene in a T-cell line, CTLL-2. Here we extended these findings by exploring the effects of selective removal of phosphate from tyrosines in p72-74-Raf-1 kinase that had been immunoprecipitated from IL-2-stimulated CTLL-2 cells. Treatment in vitro of IL-2-activated Raf-1 with the tyrosine-specific phosphatases CD45 and TCPTP (formerly called T-cell protein tyrosine phosphatase) reduced Raf kinase activity to nearly baseline levels. This effect was completely inhibited by the phosphatase inhibitor sodium orthovanadate. In contrast, treatment of Raf-1 with a serine/threonine-specific phosphatase, protein phosphatase 1 (PP-1), resulted in a more modest decrease in Raf in vitro kinase activity, and this effect was prevented by okadaic acid. Two-dimensional phosphoamino acid analysis confirmed the selective removal of phosphate from tyrosine by CD45 and from serine and threonine by PP-1. The immunoreactivity of p72-74-Raf-1 with anti-phosphotyrosine antibodies was also completely abolished by treatment with CD45 in the absence but not in the presence of sodium orthovanadate. These findings provide evidence that the IL-2-stimulated phosphorylation of Raf-1 on tyrosines plays an important role in upregulating the activity of this serine/threonine-specific kinase in CTLL-2 cells and, as such, provides a model system for studying the transfer of growth factor-initiated signals from protein tyrosine kinases to serine/threonine-specific kinases.

Differential regulation of the p72-74 RAF-1 kinase in 3T3 fibroblasts expressing ras or src oncogenes

The c-raf-1 protooncogene encodes a p72-74 serine/threonine-specific kinase that has been implicated in growth factor-mediated signal transduction and malignant transformation. Here, we compared the effects of Ha-c-ras and v-src oncogenes on the regulation of p72-74 RAF-1 kinase in NIH3T3 cells. In both serum-starved and platelet-derived growth factor-treated v-src-transformed cells, the RAF-1 kinase was constitutively activated, displaying characteristic retarded mobility in electrophoretic gels and elevated activity in in vitro kinase assays. In contrast, the RAF-1 protein from quiescent ras-transformed cells did not exhibit constitutively shifted gel mobility or elevated kinase activity but did respond normally with regard to platelet-derived growth factor- and phorbol myristate acetate-induced changes in p72-74 RAF-1 phosphorylation and kinase activity. 3T3 cells transformed by ras, however, contained elevated levels of p72-74 RAF-1 protein (as determined by immunoblotting), suggesting an indirect influence on this kinase. Quantitative differences in the levels and subcellular distribution of immunodetectable protein kinase C enzymes did not account for the differences between src- and ras-transformed 3T3 cells with regard to regulation of the RAF kinase. These findings in serum-deprived 3T3 cells demonstrate that expression of a ras oncogene can be insufficient for full activation of the p72-74 RAF-1 kinase, implying necessity for an additional growth factor-mediated stimulus.

Dysplasia and cancer complicating strictures in ulcerative colitis

Previous studies have found a widely variable prevalence of dysplasia and cancer in colonic strictures in patients with ulcerative colitis. Consequently, therapeutic recommendations are conflicting. To better assess the prevalence, we reviewed the clinical and pathological findings in all 27 patients with ulcerative colitis complicated by stricture who were entered into our Inflammatory Bowel Disease Registry. A true stricture was defined as a persistent localized narrowing of the colon found on air-contrast barium enema or on colonoscopy. Upon careful review, 12 of 27 patients were found to have transient colonic spasm, not a stricture, and were excluded. The remaining 15 patients with true strictures represented 3.2% of all ulcerative colitis patients in the registry. Strictures were identified at 13.3 +/- 9.9 years following the diagnosis of ulcerative colitis. Eleven patients had multiple strictures that were principally located in the left colon. Of the 15 patients, 11 had dysplasia and two had cancer found on colonoscopic biopsy. Ultimately, six patients had carcinoma found at colonoscopy or colectomy (three modified Dukes' stage A, one stage B, and two stage D). All cancers were at the site of a stricture. These findings indicate that a true colonic stricture in ulcerative colitis is frequently associated with dysplasia and cancer, which can be diagnosed with colonoscopic biopsy. A stricture should be considered a strong risk factor for cancer, requiring intensive colonoscopic surveillance. If dysplasia is discovered, or if the stricture cannot be adequately biopsied, consideration should be given to total colectomy.

Recombination block in the Spore killer region of Neurospora

Spore killers Sk-2K and Sk-3K are chromosomal meiotic drive factors in Neurospora. In heterozygous crosses, ascospores not containing the Spore killer die. Sk-2K and Sk-3K, which differ in killing specificity, were found to be associated with suppression of recombination in a centromere-spanning region of linkage group III, and investigation of that recombination block is reported here. The block covers a region that is normally 30 to 40 map units long. A locus (r(Sk-2)) conferring resistance to Sk-2K maps to the left end of the recombination block. Recombination is normal in r(Sk-2) X Sk sensitive but blocked in Sk-2K X r(Sk-2); so the block does not depend upon killing. By selective plating, SkK stocks carrying genetic markers within the block were obtained at frequencies on the order of 10(-5) or 10(-6). Since this tight block is far beyond what has been observed for genetic reduction of recombination, a structural basis is assumed. No evidence of chromosome rearrangement was obtained. Crosses homozygous for Sk-2K show normal crossing-over and map order for the flanking markers cum and his-7 and three included markers (acr-7, acr-2, and leu-1). Results would be consistent with a divergence of sequence great enough to interfere with homologous pairing.

Conventional and unconventional analysis of an inversion in Neurospora

In(IL; IR)O Y348is a pericentric inversion of linkage group I inN. crassa, with a breakpoint betweenfrandun-5in the left arm and a breakpoint betweenad-9andnit-1in the right arm. Approximate breakpoint location was found by tabulating crossovers between the rearrangement and markers in normal chromosome sequence. Inversion structure was verified by markedIn O Y348×In O Y348crosses. Precise mapping of breakpoints was by duplication coverage. Inversions likeO Y348do not produce progeny with segmental chromosome duplications when crossed to normal sequence, but duplications were produced by crossing it toIn(IL; IR)O Y323(Barry & Leslie, 1982), another standard pericentric inversion, and toT(I → VI)NM103(Turner, 1977), a translocation to a tip. Each of these rearrangements has a breakpoint within the inverted region ofIn O Y348. Two duplications fromIn O Y348×In O Y323were converted to normal chromosome sequence by double mitotic recombination. Besides expediting mapping, the technique of intercrossing rearrangements increasingly enables us to make segmental duplications exactly tailored for studying specific included genes.

SPORE KILLER, A CHROMOSOMAL FACTOR IN NEUROSPORA THAT KILLS MEIOTIC PRODUCTS NOT CONTAINING IT

Three chromosomal factors called Spore killer (Sk) have been found in wild populations of Neurospora sitophila and N . intermedia. Sk resembles other examples of meiotic drive such as Segregation Distorter in Drosophila, Pollen killer in wheat, and Gamete eliminator in tomato. In crosses heterozygous for Sk, each ascus contains four viable black ascospores and four inviable, undersize, clear ascospores, with second-division segregations infrequent. The survivors contain the killer allele Skk, while unlinked markers segregate normally. Reciprocal crosses are identical. When crosses are homozygous for an allele of Sk, all eight ascospores are viable and black in most asci. (Many homozygms crosses have a background level of randomly occurring inviable spores; however, the pattern of 4 viable : 4 small clear ascospores is not found in any of the asci of Sk-homozygous crosses.)—killer (Sk-1K) and sensitive (Sk-1S) alleles occur in about equal numbers among a worldwide sample of N. sitophila strains, following no geographic pattern. No killer allele has been found in N . crassa. Sk-2K and Sk-3k, found in N . intermedia, are rare. Most N. intermedia strains are Sk-2S and Sk-3S, but some are wholly o r partially resistant to one or both of the killer alleles, while not themselves acting as killers. Sk-2K and Sk-2R are both specific in conferring resistance to Sk-2K, but not to Sk-3K. Likewise Sk-3K and Sk-3R are resistant specifically to Sk-3K, but not to Sk-2K. Resistance segregates as an allele of SkK.——Sk-2 and Sk-3 have been mapped near the centromere of linkage group I11 after introgression into N . crassa, where crossing over is normally 11 % between the proximal I11 markers acr-2 and leu-1. But crossing over is absent in this region when either of the killer alleles is heterozygous (Sk-2K x Sk-2S, Sk-3K x Sk-3S and Sk-2K X Sk-2R have been examined).

EUPLOID DERIVATIVES OF DUPLICATIONS FROM A TRANSLOCATION IN NEUROSPORA

Nontandem terminal chromosome duplications derived from N. crassa translocation T(I→VI)NM103 give rise mitotically to some daughter nuclei which have become euploid by loss of one or the other of the two duplicated segments. Loss of the segment in normal sequence occurs as often as loss of the translocated segment. This is in contrast to all of several other Neurospora duplications that have been studied, where loss of the segment in normal sequence is absent or rare.—T(NM103) has the distal two thirds of linkage group IR exchanged with the right tip of VI. Crosses to normal sequence produce a class of morphologically distinct progeny with IR chromosome duplications. For a few days after germination, test crosses of these progeny are barren (make perithecia but few or no spores, as observed commonly with Neurospora duplications). Growing duplication cultures become fertile by accumulating nuclei which have been reduced to either normal sequence (by loss of the segment in translocation sequence) or translocation sequence (by loss of the segment in normal sequence). Both types usually appear within the first week of growth. Naturally formed mixtures or heterokaryons of NM103 duplication nuclei and their reduced euploid products have been studied by plating and by progeny testing. Determination of nuclear type is based on culture morphology, expression of genetic markers, and crossing behavior. Within the limits of testing, loss is found to begin precisely at the interchange points. The unique finding of frequent breakdown of normal-sequence linkage group I chromosomes is not dependent on the strain from which the chromosome was derived. Many different strains were tested, and for each one evidence was found that nuclei reduced to translocation sequence had been produced from duplication nuclei by loss of the segment in normal sequence.

New duplication-generating inversions in Neurospora

Inversion In(ILR)NM176 has one break point at the extreme right end of linkage group I and the other distal to mating type in the left arm. In crosses of Inversion × Normal the products of single crossing over within the inversion are complementary duplication-deficiency classes. One crossover product is viable, with a large segment of IL duplicated and the dispensable right tip presumably deficient. This class has low fertility and distinctive morphology. The complementary product has a large deficiency which results in a pair of white, inviable ascospores. Single exchanges within the heterozygous inversion thus produce asci with 6 Black: 2 White spores; four-strand double exchanges produce 4 B:4 W; and non-exchanges produce asci with 8 B:0 W. Approximate mapping of break points was accomplished by three-point crosses. Precise placement of the left break point between ser-3 and un(55701t), just left of mating type, is based on coverage of markers by the heterozygous duplication. No crossover has been obtained between mating type and the break point, despite extensive efforts. In(ILR)NM176 differs from the inversion In(ILR)H4250 described by Newmeyer and Taylor (1967) in one main respect: the mating type locus is included in the inverted segment of NM176. Consequently, when duplications are generated, the progeny are unisexual and do not have the unstable inhibited phenotype characteristic of H4250 duplication progeny, which are heterozygous for the mating type alleles A and a. Three other inversions which originated independently of In(ILR)NM176 resemble it closely and have similar or identical break points.

Pesticide mobility: determination by soil thin-layer chromatography

Pesticide movement was evaluated by the comparison of R(F) values on thin layers of soils. Results from the new technique correlated well with existing information on pesticide movement, facilitating the grouping of pesticides into classes on the basis of mobility. Thin-layer chromatography may have broad applicability in soils research.

The chromophore of phytochrome

The chromophore of phytochrome, the plant photomorphogenic pigment, was cleaved from the associated protein. Chromatographic and spectral properties indicated that it was a bilitriene closely similar to but distinct from the chromophore of C-phycocyanin and allophycocyanin.