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Biomedical subjects

M R Goldsmith

Publications and source records attributed to M R Goldsmith.

At least 19 recordsLinked to original sources
PubMed2000

Characterization of early follicular cDNA library suggests evidence for genetic polymorphisms in the inbred strain C108 of Bombyx mori.

Recent work towards the completion of a saturated molecular genetic linkage map for the lepidopteran silkworm, Bombyx mori (n = 28), has provided evidence for existing polymorphisms in the inbred strain C108. Two inbred parental strains, p50 and C108, were crossed to produce the F1 (P/C) hybrid offspring. The populations used in this project were comprised of a combination of 29 F2 (F1 x F1) and 31 reciprocal backcross (P/C x C/C, P/C x P/P) progeny. All restriction fragment length polymorphisms (RFLPs) for the initial analysis were hybridized with anonymous probes derived from a random early follicular cDNA (Rcf) library from Bombyx. A total of 19 Rcf probes were selected as showing scorable codominant polymorphic patterns when screened against F2 and backcross DNAs digested with the restriction enzymes EcoRI, HindIII, or PstI, and Southern blotted to nylon membranes for hybridization. Of the newly reported Rcf probes, 7 (37%) were characterized as producing 'simple' polymorphic patterns, while 12 (63%) were characterized as producing 'complex' polymorphic patterns. Further characterization of the complex patterns subdivided this group into two general classes: polymorphisms that contained an additional allele, and multiple bands that contained an easily scored two banded polymorphism. Because the extra allele class was limited to the (P/C x C/C) backcross progeny, it is suggested that the inbred parental strain C108 harbors polymorphic loci that are inherited in a simple Mendelian fashion. A genetic analysis discussing plausible origins and maintenance of these polymorphisms is presented.

Animals↗
PubMed1993

A subtle defect underlies altered lamellar orientation in the Gr16 chorion mutant of Bombyx mori.

Gr16 (chromosome 2, 6.9 cM) is a dominant, grey egg mutation of the domestic silkmoth, Bombyx mori, which produces an opaque instead of a translucent chorion. To determine the underlying cause of this defect, we examined the effects of the mutation on chorion ultrastructure, protein accumulation, and biosynthesis patterns, and on the restriction patterns of early chorion structural genes, using the presumed wild-type progenitor strain, Old European 16 (OE16), for comparison. Cross-sections of mature chorions examined by scanning electron microscopy showed that the inner lamellae were oriented perpendicular, rather than parallel, to the egg surface, with a smaller vertical zone bordered by normally oriented lamellae in the heterozygote, suggestive of codominant expression. This defect first appeared in transmission electron micrographs early in choriogenesis, probably during framework formation and/or expansion stages. Mature chorion protein patterns resolved by isoelectric focusing or two-dimensional polyacrylamide gel electrophoresis, synthetic profiles of virtually all chorion proteins following pulse-labeling with tritiated or [14C]glycine, and restriction patterns of early chorion genes examined by Southern blot hybridization were identical between mutant, wild-type, and heterozygote. These observations ruled out a major deletion of chorion structural genes or defects in the production and accumulation of normal chorion proteins as mechanisms underlying the mutation, unlike other putative Gr mutants mapping in its vicinity. The sole difference that we detected was a set of minor, early protein doublets of related size but differing isoelectric point, which showed reciprocal labeling intensities in Gr16 vs OE16 and were codominantly expressed. Preliminary pulse-chase experiments suggested that these proteins may be post-translationally modified forms which undergo differential processing in mutant and wild-type. Based on these observations, we postulate that the Gr16 mutation affects the primary structure of a minor, previously unidentified chorion or follicular cell component which is critical for determining lamellar orientation, and discuss models of how this might function.

Animals↗
PubMed1989

Recombinant baculoviruses as vectors for identifying proteins encoded by intron-containing members of complex multigene families.

Using a transfer vector derived from Bombyx mori nuclear polyhedrosis virus (BmNPV), we have constructed recombinant baculoviruses that contain complete silk moth chorion chromosomal genes encoding high-cysteine proteins under the control of the polyhedrin promoter. Silk moth tissue culture cells infected with these recombinant viruses were found to contain abundant RNA sequences of sizes similar to those of the authentic chorion mRNAs. Chorion transcripts present in infected cells were initiated almost exclusively at the cap site of the polyhedrin start site. Primer extension and RNase protection experiments revealed that a considerable proportion of the resultant transcripts were spliced at the same sites as those utilized in follicular cells for the production of functional chorion mRNA. Electrophoretic analysis and immunoprecipitation of the proteins of host cells infected with the recombinant viruses revealed the presence of the corresponding chorion proteins. We conclude that baculovirus vectors can be used for expressing efficiently not only cDNAs or simple genes devoid of intervening sequences but also intron-containing chromosomal genes. Thus, recombinant baculoviruses offer a powerful alternative to hybrid-selected translation, particularly when the identification of proteins encoded by members of complex multigene families is required.

Amino Acid Sequence↗
PubMed1987

Foucher's sign of the Baker's cyst.

We investigated the mechanism of Foucher's sign, the change in pressure in the Baker's cyst with extension and flexion of the knee, by echography, arthrography, and computed tomography. With extension the gastrocnemius and the semimembranosus muscles approximate each other and the joint capsule compressing the cyst against the deep fascia. Opposite effects in flexion allow the cyst to relax.

Humans↗
PubMed1984

Aspiration of the retrocalcaneal bursa.

We aspirated the retrocalcaneal bursa in cadavers to determine the characteristics of bursal fluid. A small amount of clear, viscous fluid was constantly present in the bursa. Leucocyte count was low, and the mucin clot test was good. With the same technique we aspirated the retrocalcaneal bursae of 4 patients. Three had Reiter's syndrome; the bursal fluid was inflammatory, and symptoms promptly resolved after local corticosteroid injection. The fourth patient presented with heel pain; intracellular, positively birefringent crystals were present in the aspirate, consistent with the diagnosis of pseudogout.

Achilles Tendon↗
PubMed1982

Hybridization-selected translation of Bombyx mori high-cysteine chorion proteins in Xenopus laevis oocytes.

Xenopus laevis oocytes were injected with poly(A)+-mRNA isolated from chorionating follicular epithelium of the domesticated silk moth (Bombyx mori). On two-dimensional gel electrophoresis, the resultant translation products comigrated with authentic, secreted, chorion standards, demonstrating that the frog oocyte system synthesizes and correctly process virtually all major chorion components. A cDNA clone has been shown to contain sequences complementary to those of mRNAs encoding B mori high-cysteine (Hc) chorion proteins Hc6-Hc11. mRNAs were selected by hybridization to plasmid m5000 DNA bound to diazobenzyloxymethyl-cellulose and subsequently translated in X. laevis oocytes into forms that comigrated with authentic chorion standards. The selection of a distinct subset of Hc mRNAs under stringent hybridization conditions (70% formamide/0.2 M NaCl, 60 degrees C) suggests that they are encoded by related genes. This is consistent with the pattern obtained by hybridizing radioactive m5000 DNA to Southern blots prepared from EcoRI-cleaved B. mori chromosomal DNA.

Animals↗
PubMed1981

Chromosome organization during male meiosis in Bombyx mori.

Chromatin organization during male meiosis in Bombyx mori has been investigated utilizing the Miller spreading procedure. During meiotic prophase, the linear 200-300 A chromatin fibers evident at interphase are folded into tandem arrays of approximately 7,000 loops per haploid genome. Adjacent loops visualized during early prophase are separated by 0.15-0.2 nm of nucleosomal DNA. Meiotic metaphase chromosomes display numerous loops which project radially from the central region of the chromosome suggesting that the loop conformation of prophase is maintained throughout meiosis. Spread preparations of spermatogenic stages through pachytene allow the visualization of actively transcribed ribosomal DNA. Throughout this period, these transcription units appear to be organized into loops in such a way that one active transcription unit exists on a single loop. Furthermore, there are various levels of transcription on different ribosomal loops, although the number of loops displaying active transcription remains constant throughout this period.

Animals↗
PubMed1980

Molecular analysis of the GrB mutation in Bombyx mori through the use of chorion cDNA library.

To study the molecular basis of the GrB mutation, which prevents the synthesis of many stage-specific chorion proteins, a cDNA library has been constructed from wild-type chorion mRNA of Bombyx mori strain 703. By differential screening of the library with +/+ and B/B mRNAs, under appropriately stringent conditions to minimize cross hybridizations of related chorion sequences, we have selected several distinct clones corresponding to RNA sequences which are affected by the mutation (that is, are represented only in +/+ mRNA) or are unaffected (that is, are represented in both +/+ and B/B mRNAs). We show by Southern analysis that, whereas unaffected gene sequences are represented in both +/+ and B/B chromosomal DNA, affected sequences have been deleted from B/B DNA. The organization and regulation of developmental stage-specific chorion genes are discussed in light of these findings and the known effects of GrB on stage-specific protein synthesis.

Animals↗
PubMed1980

Organization of the chorion genes of Bombyx mori, a multigene family. III. Detailed marker composition of three gene clusters.

The chorion patterns produced by progeny from crosses that were used to define the linked gene clusters, Ch 1, Ch 2 and Ch 3 (strain C108 vs. strain Ascoli), were examined by two-dimensional gel electrophoresis (isoelectric focusing vs. SDS/urea). Approximately 60 proteins were assigned to four previously defined chorion classes, A, B, C and Hc, believed to represent the products of related genes, on the basis of size and relative cysteine content. All strain-specific markers showed co-dominance in the F1, indicating the likelihood that they are not products of post-translational modification. Twenty-seven Ascoli markers co-segregated in testcross progeny, and none of the resolved proteins showed independent assortment, confirming their linkage to chromosome 2. Two-dimensional screening of recombinants demonstrated that all three clusters contain Class A and B markers; Hc markers have been found only in Ch 1 and Ch 2; whereas, mapped C markers were confined to Ch 3. This indicates that chorion clusters are heterogeneous with respect to the markers they contain.

Animals↗
PubMed1978

Organization of the chorion genes of Bombyx mori, a multigene family. I. Evidence for linkage to chromosome 2.

The chorion genes of silkmoths comprise a multigene family that codes for 50 or more highly specialized structural proteins found in the eggshell. A detailed study of the chromosomal organization of these genes was initiated, using inbred stocks of Bombyx mori as a source of electrophoretic variants for genetic markers. Chorion protein patterns were screened on thin-slab polyacrylamide isoelectric focusing gels. A wide range of polymorphism was observed between stocks. However, isoelectric focusing patterns obtained within a stock were nearly homogeneous, indicating that inbreeding has produced a high degree of homozygosis. Testcrosses were carried out to examine the linkage relationships between electrophoretic markers in four inbred stocks. One race (C108) was selected as a standard against which to compare the inheritance of the variants found in the other three stocks. Chorion markers behaved like codominant Mendelian traits in F, crosses. A total of 15 out of 16 C108 markers cosegregated in subsequent testcrosses, indicating that they are linked. These genes were mapped to the second chromosome, using markers Gr and Y.

Animals↗
PubMed1977

Polyribosome Formation in Relation to Cytokinin-induced Cell Division in Suspension Cultures of Glycine max [L.] Merr.

We have investigated the relationship between cell proliferation and protein synthetic capacity in a cytokinin-requiring strain of cultured soybean cells (Glycine max [L.] Merr. cv. Sodifuri, of cotyledonary origin) in suspension culture. When transferred to a defined medium lacking cytokinin, very little cell division or cell enlargement took place over the course of a 6-day culture period. Cells transferred to medium of the same composition, but containing 0.5 mum zeatin, exhibited rapid initial growth, with maximum mitotic activity occurring after 24 hours in culture, and a doubling of the cell population within the first 36 hours of the culture period. The polyribosomal RNA content of the cells decreased over the course of the first 24 hours of the growth cycle while the polyribosome to monoribosome (P/M) ratio increased. The increase in the P/M ratio was greater in the cytokinin-treated cells. This apparent relationship between cytokinin-induced cell proliferation and polyribosome formation was examined further. Polyribosome formation was stimulated when zeatin was added directly to cell populations which had been cultured for 24 hours in medium lacking a cytokinin. Transfer to fresh medium alone also stimulated polyribosome formation, whether this medium contained a cytokinin or not. The magnitude of transfer-induced polyribosome formation depended upon the initial cell density (number of cells/ml of medium). Regardless of the initial cell density and independent of the P/M ratios attained, the cytokinin-treated cell populations divided while the cytokinin-deprived cell populations did not. In vivo labeling with [(35)S]methionine and slab gel electrophoretic separation of sodium dodecyl sulfate derivatives of the labeled polypeptides demonstrated qualitative changes in the spectrum of proteins synthesized by the cytokinin-treated cells. These qualitative changes were independent of the cell density (and hence, independent of the P/M ratio) but they preceded cytokinin-induced cell division.

Journal Article↗
PubMed1977

Improved radiographic detection of multiple gastric ulcers.

In more than 1,500 double contrast upper gastrointestinal examinations performed January through November 1974, 26 cases of multiple gastric ulcers were diagnosed. This represents 18.6% of the 140 patients who had a demonstrable gastric lesion, and 23.4% of the 111 patients who had either a single gastric ulcer or scar. This technique was developed in a country where gastric carcinoma is common, but in the United States its greatest usefulness will probably be in the detection of subtle mucosal defects such as multiple gastric ulcers, linear ulcers, and erosions. The sensitivity of the routine pharmacologically aided double contrast upper gastrointestinal examination is confirmed by the high incidence of multiple gastric ulcers found.

Aged↗
PubMed1976

Evaluation of routine double contrast views of the anterior wall of the stomach.

Since June 1974, we have performed over 1,500 consecutive double contrast upper gastrointestinal examinations. The double contrast study of the anterior wall has been a useful adjunct to conventional mucosal relief and dosed compression studies. Nevertheless, the low diagnostic yield of the anterior wall examination does not appear to justify including it as part of the routine double contrast upper gastrointestinal study.

Contrast Media↗
PubMed1972

Specific protein synthesis in cellular differentiation. Production of eggshell proteins by silkmoth follicular cells.

Silkmoth follicles, arranged in a precise developmental sequence within the ovariole, yield pure and uniform populations of follicular epithelial cells highly differentiated for synthesis of the proteinaceous eggshell (chorion). These cells can be maintained and labeled efficiently in organ culture; their in vitro (and cell free) protein synthetic activity reflects their activity in vivo. During differentiation the cells undergo dramatic changes in protein synthesis. For 2 days the cells are devoted almost exclusively to production of distinctive chorion proteins of low molecular weight and of unusual amino acid composition. Each protein has its own characteristic developmental kinetics of synthesis. Each is synthesized as a separate polypeptide, apparently on monocistronic messenger RNA (mRNA), and thus reflects the expression of a distinct gene. The rapid changes in this tissue do not result from corresponding changes in translational efficiency. Thus, the peptide chain elongation rate is comparable for chorion and for proteins synthesized at earlier developmental stages (1.3-1.9 amino acids/sec); moreover, the spacing of ribosomes on chorion mRNA (30-37 codons per ribosome) is similar to that encountered in other eukaryotic systems.

Animals↗