Organization of the SUC gene family in Saccharomyces

The SUC gene family of yeast (Saccharomyces) includes six structural genes for invertase (SUC1 through SUC5 and SUC7) found at unlinked chromosomal loci. A given yeast strain does not usually carry SUC+ alleles at all six loci; the natural negative alleles are called suc0 alleles. Cloned SUC2 DNA probes were used to investigate the physical structure of the SUC gene family in laboratory strains, commercial wine strains, and different Saccharomyces species. The active SUC+ genes are homologous. The suc0 allele at the SUC2 locus (suc2(0) in some strains is a silent gene or pseudogene. Other SUC loci carrying suc0 alleles appear to lack SUC DNA sequences. These findings imply that SUC genes have transposed to different chromosomal locations in closely related Saccharomyces strains.

The secreted form of invertase in Saccharomyces cerevisiae is synthesized from mRNA encoding a signal sequence

The SUC2 gene of Saccharomyces cerevisiae encodes two differently regulated mRNAs (1.8 and 1.9 kilobases) that differ at their 5' ends. The larger RNA encodes a secreted, glycosylated form of invertase and the smaller RNA encodes an intracellular, nonglycosylated form. We have determined the nucleotide sequence of the amino-terminal coding region of the SUC2 gene and its upstream flanking region and have mapped the 5' ends of the SUC2 mRNAs relative to the DNA sequence. The 1.9-kilobase RNA contains a signal peptide coding sequence and presumably encodes a precursor to secreted invertase. The 1.8-kilobase RNA does not include the complete coding sequence for the signal peptide. The nucleotide sequence data prove that SUC2 is a structural gene for invertase, and translation of the coding information provides the complete amino acid sequence of an S. cerevisiae signal peptide.

Topography, cytoarchitecture, and sulcal patterns in primary somatic sensory cortex (SmI) prosimian primate, Perodicticus potto

The topographic organization of the primary somatic sensory projection area (SmI) in relation to cytoarchitectural fields and sulcal patterns was examined in the prosimian primate Perodicticus potto. The area of cortex responding to low threshold (LT) cutaneous stimulation of the glabrous and hairy surfaces of the hand was determined by microelectrode mapping techniques, with standardized threshold stimuli for defining receptive fields. A single somatotopic projection of the two hand surfaces was found; the glabrous projection area is rostral to that of the hairy hand. Within both the glabrous and hairy areas, receptive fields on the distal digits are found anterior to those on the proximal hand. The glabrous hand projection area is coextensive with a dense granular area typical of koniocortex. The hairy hand area corresponds to a cytoarchitectural field which is less granular than the glabrous field. While koniocortex occupies the crown of the gyrus caudal to the coronally oriented sulcus, a large more rostral field, which contains both granule and large pyramidal cells, occupies the whole of the caudal bank of the sulcus. Force thresholds of many receptive fields (RFs) in Perodicticus were high both on the borders and within the LT area (perhaps because of the advanced age of these animals). However, the receptive field sizes for both the glabrous and hairy hand areas were of the same magnitude as those of Nycticebus (Carlson and FitzPatrick, '82). From the combined studies of three species of Lorisidae, Perodicticus, Galago (Carlson and Welt, '80), and Nycticebus (Carlson and FitzPatrick, '81), using similar mapping and stimulation techniques, both general and specific features of SmI hand area organization can be illustrated. A single projection of the glabrous and hairy hand is common to Perodicticus and Galago, but two glabrous projection areas are seen in Nycticebus. The projection area for the hand in Perodicticus is twice as large (relative to brain size) as in Galago and Perodicticus. The possible behavioral significance of increased differentiation of the hand area in Nycticebus and elaboration of the area in Perodicticus could be examined by study of hand use and tactile capacity in these same species.

Two differentially regulated mRNAs with different 5' ends encode secreted with intracellular forms of yeast invertase

The SUC2 gene of yeast (Saccharomyces) encodes two forms of invertase: a secreted, glycosylated form, the synthesis of which is regulated by glucose repression, and an intracellular, nonglycosylated enzyme that is produced constitutively. The SUC2 gene has been cloned and shown to encode two RNAs (1.8 and 1.9 kb) that differ at their 5' ends. The stable level of the larger RNA is regulated by glucose; the level of the smaller RNA is not. A correspondence between the presence of the 1.9 kb RNA and the secreted invertase, and between the 1.8 kb RNA and the intracellular invertase, was observed in glucose-repressed and -derepressed wild-type cells. In addition, cells carrying a mutation at the SNF1 locus fail to derepress synthesis of the secreted invertase and also fail to produce stable 1.9 kb RNA during growth in low glucose. Glucose regulation of invertase synthesis thus is exerted, at least in part, at the RNA level. A naturally silent allele (suc2 degrees) of the SUC2 locus that does not direct the synthesis of active invertase was found to produce both the 1.8 and 1.9 kb RNAs under normal regulation by glucose. A model is proposed to account for the synthesis and regulation of the two forms of invertase: the larger, regulated mRNA contains the initiation codon for the signal sequence required for synthesis of the secreted, glycosylated form of invertase; the smaller, constitutively transcribed mRNA begins within the coding region of the signal sequence, resulting in synthesis of the intracellular enzyme.

A clinical study of the periodontal status of abutment teeth supporting swinglock removable partial dentures--a pilot study

Eleven patients wearing mandibular swinglock bilateral distal extension removable partial dentures opposing maxillary complete dentures were studied for a period up to 2 years. They had moderate to advanced periodontal disease with retrograde mobility patterns. Periodontal therapy, as well as treatment of dental carious lesions, was completed before fabrication of the prosthesis. Recordings of the gingival status, pocket depth, plaque score, tooth mobility, and dental caries were made at the time of the placement of the prosthesis and thereafter at 6-month intervals. Final results were obtained at the end of 2 years in six patients (group A) and at 1 1/2 years in five patients (group B). Our findings show that both groups had a statistically significant increase in gingival inflammation. However, no differences in degree of inflammation were observed between the two groups with regard to the status of gingival tissues that were covered and uncovered by the components of the swinglock removable partial denture. Also, no statistically significant differences in pocket depths and plaque scores were found between the time of placement of the swinglock removable partial denture and the final recall visit. Of the 61 abutment teeth, 85.2% had no significant change in mobility, 11.5% showed a substantial decrease in mobility, and 3.3% showed a considerable increase in mobility. The patients were able to successfully wear the swinglock removable partial denture without clinically significant changes in the supporting structures of the abutment teeth. This report is part of an ongoing study to determine the efficacy of swinglock removable partial dentures.

Mutants of yeast defective in sucrose utilization

Utilization of sucrose as a source of carbon and energy in yeast (Saccharomyces) is controlled by the classical SUC genes, which confer the ability to produce the sucrose-degrading enzyme invertase (Mortimer and Hawthorne 1969). Mutants of S. cerevisiae strain S288C (SUC2+) unable to grow anaerobically on sucrose, but still able to use glucose, were isolated. Two major complementation groups were identified: twenty-four recessive mutations at the SUC2 locus (suc2-); and five recessive mutations defining a new locus, SNF1 (for sucrose nonfermenting), essential for sucrose utilization. Two minor complementation groups, each comprising a single member with a leaky sucrose-nonfermenting phenotype, were also identified. The Suc2 mutations isolated include four suppressible amber mutations and five mutations apparently exhibiting intragenic complementation; complementation analysis and mitotic mapping studies indicated that all of the suc2 mutations are alleles of a single gene. These results suggest that SUC2 encodes a protein, probably a dimer or multimer. No invertase activity was detected in suc2 probably a dimer or multimer. No invertase activity was detected in suc2 mutants,--The SNF1 locus is not tightly linked to SUC2. The snf1 mutations were found to be pleiotropic, preventing sucrose utilization by SUC2+ and SUC7+ strains, and also preventing utilization of galactose, maltose and several nonfermentable carbon sources. Although snf1 mutants thus display a petite phenotype, classic petite mutations do not interfere with utilization of sucrose, galactose or maltose. A common feature of all the carbon utilization systems affected by SNF1 is that all are regulated by glucose repression. The snf1 mutants were found to produce the constitutive nonglycosylated form of invertase, but failed to produce the glucose-repressible, glycosylated, secreted invertase. This failure cannot be attributed to a general defect in production of glycosylated and secreted proteins because synthesis of acid phosphatase, a glycosylated secreted protein not subject to glucose repression, was not affected by snf1 mutations. These findings suggest that the SNF1 locus is involved in the regulation of gene expression by glucose repression.

Genetic evidence for a silent SUC gene in yeast

The SUC genes (SUC1-SUC7) of Saccharomyces are a family of genes that are dispersed in the yeast genome. A SUC+ allele at any locus confers the ability to produce the enzyme invertase and, thus, to ferment sucrose. Most yeast strains do not carry SUC+ alleles at all possible SUC loci. We have investigated the naturally occurring negative (suc0) alleles present at SUC loci with the aim of distinguishing between two possible models for the structure of suc0 alleles: (1) suc0 alleles correspond to a simple absence of SUC genetic information; (2) suc0 alleles are "silent" SUC genes that either produce a defective product or are not expressed. To facilitate these studies, sucrose-nonfermenting strains were constructed that are congenic to S. cerevisiae strain S288C (SUC2+), but carry at the SUC2 locus the naturally occurring negative allele, suc2(0), of strain FL100 (Lacroute 1968). These strains were used to study the genetic properties of the suc2(0) allele of FL100 and the suc0 alleles (suc1(0), suc3(0), etc.) of S288C. The suc2(0) allele was shown to revert to an active Suc+ state and to provide functional information at three points in the SUC2 gene in recombination experiments; this suc2(0) gene thus appears to be a "silent" gene. Similar tests for silent SUC genes in S288C (corresponding to loci other than SUC2) failed to reveal any additional silent genes.

Characteristics of sensory deficits following lesions of Brodmann's areas 1 and 2 in the postcentral gyrus of Macaca mulatta

This study re-examines the double dissociation of tactile deficits resulting from restricted surgical removals of Brodmann's areas 1 and 2 in the postcentral gyrus of macaque monkeys. Area 1-operated animals showed selective deficits on texture tasks, roughness and line discriminations, while area 2-operated animals showed deficits only on angle tasks, size and curve discriminations. Severe deficits were evident in spite of preoperative training, forced correction trials, and the presentation of tasks of graded difficulty.

High-dose methotrexate as secondary chemotherapy in metastatic soft-tissue sarcomas

High-dose methotrexate in a dose of 2-4 g/m2 every four weeks was given as secondary chemotherapy to 22 patients with metastatic soft-tissue sarcoma; toxic reactions included 1 death and 2 instances of moderate hematopoietic toxicity. The remaining patients tolerated this treatment without difficulty. Of 18 patients with measurable evaluable disease, 17 demonstrated progression. One patient with metastatic angiosarcoma had a complete response lasting for 15 months. Three patients were given adjuvant high-dose methotrexate following wedge resections of pulmonary metastases. One patient demonstrated recurrence after four months, another after 13 months, and the third after 15 months. One additional patient underwent resection of pulmonary metastases following two months of stabilization with high-dose methotrexate and has continued free of disease with high-dose methotrexate as adjuvant for eight months. Five patients are alive and have been disease-free for an average period of 14 months. Four of these underwent operative treatment combined with chemotherapy. The effectiveness of high-dose methotrexate appears limited in soft-tissue sarcomas when it is given as secondary chemotherapy.

Polarographic determination of edetate disodium in eyewash and ophthalmic decongestant solutions

The quantitative analysis of edetate disodium in nonprescription eyewash and ophthalmic solutions is described. The method involves differential pulse polarography using a dropping mercury electrode. A known concentration of cadmium or zinc is added to a buffer in a polarographic cell. The sample solution is incremented into the cell with a micropipet. The peak current decreases because the resulting chelate is not reducible at the potentials used. The quantity of edetate disodium in the sample then is determined graphically. Some contact lens cleaning and wetting solutions containing polymeric compounds are amenable to assay to edetate disodium if extraction, precipitation, centrifugation, or dilution steps minimize the maximum suppressor effect of the additives. These steps are very effective with cellulose ether compounds but are ineffective with polyvinyl alcohol.

Estrogen and progesterone receptors and tamoxifen in malignant melanoma

Tumor biopsies from 68 patients with malignant melanoma were assessed for estrogen receptor (ERc) binding, and 32 of these for progesterone receptor (PRc) binding. Twenty-five patients (37%) had ERc greater than or equal to 5 fmols/mg protein; 14 patients (44%) had PRc greater than or equal to 10 fmols/mg of protein. There was no significant difference between the sexes in relation to the presence or absence of ERc or PRc. The tumor ERc and PRc levels did not predict the survival of these patients. Seventeen patients were treated with tamoxifen; three female patients had objective responses. Two of the patients with complete response had ERc levels of 4.3 and 19 fmols/mg tumor cytosol protein, while the third patient had no detectable ERc.

Somatic sensory cortex (SmI) of the prosimian primate Galago crassicaudatus: organization of mechanoreceptive input from the hand in relation to cytoarchitecture

Mechanoreceptive input from the hand to the somatic sensory cortex (SmI) of the prosimian primate Galago crassicaudatus was examined with microelectrode mapping methods. In anesthetized animals, low threshold cutaneous input from the hand projects to SmI cortex in a single, complete, somatotopically organized pattern. Within this single pattern, cells with receptive fields on the glabrous skin of the palm, digits and digit tips are located in the rostral half, and cells with RFs on the hairy skin of the dorsal hand and digits are located in the caudal half of the hand areas. The cutaneous hand area is coextensive with the densely granular architectonic region of SmI. Studies of single cells in this region of awake galagos reveal the same pattern of cutaneous input and, in addition, demonstrate the presence of cells responding to joint movement not detected in anesthetized animals. Cells responsive to joint movement are arranged in vertically oriented columns located adjacent to cutaneous columns with receptive fields on the same part of the hand. In anesthetized animals, cells rostral to the granular region, in an area typified by increasing numbers of pyramidal cells in layer V and decreasing numbers of granular cells in upper layers, respond to high threshold stimulation of large areas of the hand. The few cells isolated in this area in awake animals respond to either active or passive hand movements. In such animals, cells caudal to the granular region, in an area characterized as agranular and alaminar cortex, respond to either passive stimulation of single or multiple joints or to active hand movements. These results, together with similar findings in a related prosimian, Nycticebus coucang, emphasize the generality of a single cutaneous hand area in SmI of prosimian species. The demonstration of multiple hand areas corresponding to multiple cytoarchitectonic subdivisions in SmI of Old and New World simians illustrates the increased degree of SmI differentiation from the prosimian to the simian grade of organization. The present results further suggest that determination of the homologues of multiple areas or subdivisions within and surrounding SmI in primates will require comparisons of somatotopy, submodality, sulcal patterns, cytoarchitecture, and connectivity in representative members of prosimian and simian families.

High-dose methotrexate in malignant melanoma

High-dose methotrexate was given to 28 patients with advanced malignant melanoma who had previously failed to respond to two chemotherapy protocols. There were five instances of serious, but not fatal, toxicity. One patient has had an objective response and seven patients have had stabilization of disease with an average duration of 4 months.

A gene adjacent to satellite DNA in Drosophila melanogaster

Several copies of a sequence adjacent to 1.688 g/cm3 satellite DNA in the Drosophila melanogaster genome have been isolated by molecular cloning. This sequence, called the Dm142 gene, is homologous to a 1.6-kilobase RNA found in both D. melanogaster embryos and tissue culture cells. One cloned DNA segment includes two copies of the Dm142 gene and 1.688 g/cm3 satellite DNA sequences, which are located between and flanking both gene copies. The Dm142 gene is repeated many times in the D. melanogaster genome, and some copies are not flanked by 1,688 g/cm3 satellite DNA.

One of the copia genes is adjacent to satellite DNA in Drosophila melanogaster

A method for purifying sequences adjacent to satellite DNA in the heterochromatin of D. melanogaster is described. A cloned DNA segment containing part of a copia gene adjacent to 1.688 g/cm3 satellite DNA has been isolated. The copia genes compose a repeated gene family which codes for abundant cytoplasmic poly(a)-containing RNA (Young and Hogness, 1977; Finnegan et al., 1978). We have identified two major poly (A)-containing RNA species [5.2 and 2.1 kilobases (kb)] produced by the copia gene family. The cloned segment contains copia sequences homologous to the 5' end of RNA within 0.65 kb of the 1.688 satellite DNA sequences. Seven different cloned copia genes from elsewhere in the genome have also been isolated, and a 5.2 kb region present in five of the clones was identified as copia by heteroduplex analysis. In addition, three ususual copies of copia were found: a "partial" copy of the gene (3.7 kb) which has one endpoint in common with the 5.2 kb unit; a copia gene flanked on one side by a 1.6 kb sequence and on the other by the same 1.6 kb sequence in the inverted orientation; and a copia gene flanked only on one side by the same sequence.