Temperature-sensitive mutations in Drosophila melanogaster. XIV. A selection of immobile adults

Summary Improved methods for rearing and screening large numbers of flies permitted the recovery of 10 mutations exhibiting a reversible temperature-dependent adult paralysis among 1.1×10⁶ flies tested. Of the 10 mutations, two were allelic to para ^ts,two were alleles in a new locus, stoned (stn), and six fell into a third area, the shibire (shi) locus. Several of the shi alleles cause embryonic, larval and adult paralysis at 29° C as well as structural anomalies of various tissues. In addition to the ts mutations, several non-conditional mutations affecting adult movement were recovered.This work was supported by the National Research Council of Canada, grant A-1764, National Cancer Institute of Canada, grant 6051.Medical Research Council of Canada Postdoctoral Fellow.     

The origin of protein bodies in developing soybean cotyledons: a proposal

Summary The biogenesis of protein bodies is examined in cotyledons of soybean (Glycine max, Merr) at the time when reserve protein is beginning to accumulate in the cotyledons. Reserve protein is deposited in the central vacuoles of parenchyma cells and new protein bodies arise from the central vacuole by pinching-off small masses of reserve protein surrounded by a portion of the tonoplast.Supported by a grant to MJC from the National Science Foundation (Metabolic Biology) and a grant (to BYY) from the National Research Council of Canada.On leave from the Department of Biology, University of New Brunswick, N.B., Canada.     

Electrophoretic and heat-stability polymorphism at the phosphoglucomutase (Pgm) locus in natural populations of Drosophila melanogaster

Genetic polymorphism for electrophoretic and heat-sensitive alleles is known at the phosphoglucomutase (Pgm) locus in Drosophila melanogaster. Analysis of the distribution of electrophoretic and thermosensitive (ts) alleles was carried out in natural populations from Canada and West Africa and compared with already known data on Italian populations [Trippa, G., Loverre, A., and Catamo, A. (1976). Nature 260:42]. The data show the existence of five common alleles, Pgm ^1.00,tr, Pgm ^1,00,ts, Pgm ^0.70,ts, Pgm ^1.20,ts, and Pgm ^1.50,tr, and two rare alleles, Pgm ^0.55,ts and Pgm ^1.20,tr. The most frequent allele is always Pgm ^1.00,tr; the second most common allele is always of the ts type. The cumulated frequencies of ts alleles in the populations varies between 11 and 32%. The heat stability polymorphism is present in all populations examined and shows again the uniform geographic pattern that has been found for electrophoretic variation at this locus.This research was partially supported by an operating grant (to G.R.C.) from the Canadian National Science and Engineering Research Council (NSERC).     

The predominance of heterozygotes found in wild goldfish of lake Erie at the gene locus for sorbitol dehydrogenase

Sorbitol dehydrogenase (SDH) found in liver, kidney, and gonads of the goldfish (Carassius auratus) appears to be specified by a single autosomally inherited gene locus and, when subjected to electrophoresis, SDH behaves as a tetramer in that a homozygote gives a single band, while a heterozygote shows five bands of SDH. In a population of the wild goldfish inhabiting Lake Erie, two alleles which specify electrophoretic variants S^A and S^B coexist in nearly equal frequency, and there appears to be a slight excess of heterozygotes. Sixty-seven of the 109 wild goldfish were S^A/S^B heterozygotes. In the domesticated goldfish, on the other hand, an allele for the S^B variant appears to be a very rare allele. Only one of the 100 domesticated goldfish studied here and none of the 100 domesticated goldfish studied in Germany was an S^A/S^B heterozygote.Supported in part by a grant (CA 05138) and grant (FR 00433) from the National Cancer Institute, U.S. Public Health Service.On leave from McMaster University, Hamilton, Ontario, Canada.     

Improved electrophoretic resolution of some hemoglobin variants in Mus musculus

Electrophoretic separation of house mouse (Mus musculus) hemoglobins on starch gel in a 0.2 M tris maleate NaOH pH 7.0 buffer facilitates the recognition of the three phenotypes controlled by locus Hbb. Evidence that Hbb does control the electrophoretic patterns with this buffer system is discussed.This investigation was supported by National Research Council of Canada Grant A-867.     

The nuclei of the giant traps of a mutant of Monacrosporium bembicodes (Drechsler) Subram (Dactylella brochopaga Drechsler)

A mutant strain, MG-20, of the predacious hyphomycete Monacrosporium bembicodes (Drechsler) Subram (Dactylella brochopaga Drechsler) develops gaint ring traps, as well as normal ones when supplied with prey. Both types are functional. Giant traps contain more nuclei per cell than normal ones, and as they age, all their nuclei break into fragments which persist in the cell. These findings are briefly discussed.This research was supported by a grant from the National Research Council of Canada which is gratefully acknowledged.     

Some ring-trap mutants of the fungusDactylella brochopaga drechsler

Mutagenesis with nitrosoguanidine yielded two classes of ring trap mutants in the predacious HyphomyceteDactylella brochopaga: strains which could make no traps and those with a proportion of giant, functional traps. A third strain, derived from a trapless strain made abnormally small functional traps. The giant traps are described, together with developmental abnormalities they sometimes display. The characteristics of the chief mutant strains are discussed.This research was supported by a grant from the National Research Council of Canada which is gratefully acknowledged     

Genetic control of the quantitative variation of erythrocytic glyoxalase-1 (GLO-1) in mice

Quantitative genetic variation in the glyoxalase-1 content (QGlo-1) of red cells of mice is described. Its genetic control is shown to be exerted by either the Glo-1 locus or a closely linked gene to the left of H-2K. At least six alleles, designated QGlo-1 ^a through QGlo-1 ^f, can be found in different inbred strains of mice.This work was supported in part by Grants HL 0911 and AI 15413 of the National Institutes of Health and by a grant from the Sally and Alma Solomon Foundation.     

A system selective for yeast mutants deficient in meiotic recombination

Summary An experimental design and rationale for detecting and recovering Saccharomyces cerevisiae mutants specifically blocked in meiotic gene conversion is presented. The system utilizes an otherwise haploid strain disomic (n+1) for chromosome III which is simultaneously heterozygous for the mating-type locus and heteroallelic at leu2. The former is an essential requirement for inducing meiotic development; i.e., DNA replication and sporulation upon transfer to acetate media, while the latter provides a convenient signal for assaying recombination at the intragenic level. Of 940 clones screened qualitatively after mutagenesis with ethyl methanesulfonate, 91 presumptive mutants were isolated. These are classed arbitrarily into four groups according to the reduction in interallelic recombination observed in quantitative tests.Supported by research grants GM: 17317 and GM: 16522 from the National Institutes of Health and a grant from the National Sciences Foundation, GB: 8534.     

Red-light-enhanced conversion of tritiated gibberellin A9 into other gibberellin-like substances in homogenates of etiolated barley leaves

Summary Irradiation of homogenates of etiolated barley leaves with red light resulted in an increase in the levels of gibberellin (GA)-like substances as compared to dark controls. When homogenates were fed with [³H]-GA₉ there was as incorporation of the radioactivity into a number of other GA's: this process occurred to a greater extent in red light than in darkness, and could be inhibited by boiling the extract prior to addition of the [³H]-GA₉.Supported by National Research Council (Canada) grant A-5727 (Dr. D. M. Reid).Supported by National Research Council (Canada) grant A-2585 (Dr. R. P. Pharis).Supported by NATO-Science Research Council (U. K.) Postdoctoral Fellowship.     

Deficiency of dihydroxy acid dehydratase in the mito-chondria of the iv-1 mutants of Neurospora crassa

The isoleucine-valine requiring mutants of Neurospora crassa which map at the iv-1 locus lack, or have a very low level of activity for, the enzyme dihydroxy acid dehydratase in the mitochondrial fractions derived from them. This enzyme is, however, present in the soluble fractions of the mutant homogenates. The enzyme is present in both mitochondrial and soluble fractions from homogenates of wild-type and from homogenates of iv mutants blocked at other steps in the isoleucine-valine pathway.The work reported here was supported in part by grants GM 12323 and 5TO1-GM-00337-09 from the National Institutes of Health, United States Public Health Service, and by a grant from the Robert A. Welch Foundation.Recipient of Research Career Award 4-K-6-GM-18,383 from the National Institutes of Health, United States Public Health Service.     

Enzyme function and polymorphism: A test in two Anolis lizard species

Electrophoretic surveys of two lizard species were used to test hypotheses that relate levels of enzyme variability to enzyme function (single-substrate versus multiple-substrate enzymes, regulatory versus nonregulatory enzymes). Anolis roquet behaviorally regulates its body temperature, but its congener A. gundlachi is passive to variations in the thermal environment. As a result, populations of A. gundlachi probably experience the thermal environment as temporally coarse-grained, whereas populations of A. roquet do not. We therefore predicted that A. gundlachi would exhibit greater enzyme heterozygosity than A. roquet and that different enzyme classes would contribute disproportionately to this interspecific difference. The data show (1) that A. gundlachi does have a higher heterozygosity and (2) that this difference appears to result from high levels of heterozygosity at loci coding for multiple-substrate enzymes. The dichotomy between regulatory and nonregulatory enzymes offers no explanation for the variability in heterozygosity among enzyme loci in these species.E.Z. was supported by a grant from the Natural Sciences and Engineering Council of Canada. The study was accomplished while P.E.H. held a postdoctoral fellowship from the Killam Trust of Dalhousie University and a grant from the Research Development Fund of Dalhousie University. The collection of material was made possible by grants (to P.E.H.) from National Science Foundation (DEB 75-16334), the Explorers Club of New York, Sigma Xi, and the Richmond and Anderson Funds of Harvard University. We thank Dr. D. W. Foltz for his help with the calculations.     

Genetic variation of the cytoplasmic and mitochondrial malic enzymes in the monkey Macaca nemestrina

Electrophoretic variation of both the cytoplasmic and mitochondrial forms of the malic enzyme is described in Macaca nemestrina. Pedigree analysis of the observed phenotypes demonstrates that the two subcellular forms of the malic enzyme are genetically independent. The identity of the electrophoretic phenotypes in brain, heart muscle, liver, kidney, adrenal, and spleen from any given individual shows that each subcellular form is determined by the same genetic locus in a wide variety of tissues. After separation by ion exchange chromatography, the cytoplasmic and mitochondrial malic enzymes were shown to be distinct in their heat stability and K _m for malate, but no significant differences were found among the variants of the cytoplasmic enzyme or among the variants of the mitochondrial enzyme. It is possible that the polymorphism of the mitochondrial malic enzyme is selectively neutral.This study was supported by grant GM-15253 from the National Institutes of Health. One of us (G.S.O.) was a Special Fellow, U.S. Public Health Service (5F3 HD 43, 122-02); Fellow, National Genetics Foundation.     

Biochemical genetics of Fundulus heteroclitus (L.). I. Temporal and spatial variation in gene frequencies of Ldh-B,Mdh-A,Gpi-B,and Pgm-A

Natural populations of Fundulus heteroclitus show extensive spatial variation in gene frequencies at four unlinked polymorphic loci. Large clinal changes in gene frequencies were found for Ldh-B, Mdh-A, and Gpi-B, whereas the spatial variation for the Pgm-B locus was small. Since the geographical area over which these clines are found is characterized by a steep thermal gradient, the clines in gene frequency are correlated with a directional change in mean water temperature. Maximum gene diversity of these four loci was correlated with annual fluctuations in water temperature. Temporal stability of the allelic frequencies was established for a 2–4 year period.This work was supported by NSF Grants GB37548 and DEB 76-19877 and by a grant from the National Geographic Society. A. R. P. is an NIH trainee supported by a training grant (No. HD00139) to the Department of Biology.This is contribution No. 960 of the Department of Biology, Johns Hopkins University.     

Age-dependent allozymic variation in a natural population of lizards

An analysis of allozymic variation at 17 loci in a population of the sagebrush lizard (Sceloporus graciosus) in southern Utah yielded an estimate of genic heterozygosity of 0.028. Seven of the loci were variable, but only one, Est-1, was strongly polymorphic. The observation that the frequency of the common genotype (MM) at the Est-1 locus declined monotonically in successive age classes from 0.74 in hatchlings to 0.58 in adults 4 years old or older suggests that allele frequencies at this locus are not independent of selective influences.This research was supported by NSF grant GB-29141 to D.W.T. and NIH grant GM-15769 to R.K.S.     

Nuclear activity during oogenesis in sea urchins

Summary Early meiotic stages of Arbacia punctulata oocytes have revealed the presence of synaptinemal complexes in the chromosomes, which persist through zygotene-pachytene. The synaptinemal complexes conform broadly to the usual tripartite structures found in other higher forms. In addition, nuclei at these stages consist of a small nucleolus and dense bodies of varying sizes. The nucleolus is fibrillar in texture throughout and does not seem to incorporate Uridine-5-³H after pulse labeling, whereas the chromosomes are labeled. The nucleolar label is visualized at diplotene stages and onwards. The nuclear envelope differentiates by the appearance of numerous nuclear pore complexes with dense material in the annuli, and the chromosomes become markedly diffused. At vitellogenesis stage the nucleolus and chromatin become highly labeled after pulse incorporation of Uridine, indicating synthesis of ribosomal and chromosomal RNAs.This investigation was supported by grants No. A-5049, A-3624 and D-17 from National Research Council, Canada, grant No. DRB-9340-05 (U6) from Defense Research Board, Canada, and grant No. DRG-918 AT from Damon Runyon Memorial Fund for Cancer Research.     

Duplication of the autosomally inherited 6-phosphogluconate dehydrogenase gene locus in tetraploid species of cyprinid fish

Among members of the fish family Cyprinidae,a diploid—tetraploid relationship exists. The present study on electrophoretic patterns of 6-phosphogluconate dehydrogenase indicates that such diploid members as Barbus tetrazonamaintain allelic polymorphism at a single gene locus for this enzyme. Tetraploid members such as the carp and goldfish are endowed with two separate gene loci for 6-PGD. Tetraploid evolution apparently fixed two former alleles of the same locus as two separate gene loci. Furthermore, it appears that after becoming tetraploid, the carp and goldfish developed a separate regulatory mechanism for each locus; thus preferential activation of one or the other 6-PGD locus occurs in different tissues of tetraploid species. This investigation was supported in part by a grant (CA-05138) from the National Cancer Institute, U.S. Public Health Service, and in part by a research fund established in honor of General James H. Doolittle. Contribution No. 4-68, Department of Biology, City of Hope Medical Center.Dr. Bender is a recipient of International Postdoctoral Fellowship 3 F05-TW-01198-0152 from the U.S. Public Health Service.     

Autoradiographic and immunofluorescent studies of cytological changes induced inBacillus cereus by chloramphenicol

Autoradiographic and fluorescent antibody techniques were used to study the formation of protrusions on the cell periphery ofBacillus cereus. The cells were grown in a synthetic medium containing chloramphenicol and H³-labelleddl-alanine, and examined at time intervals for cytological changes. One or more protrusions were detected on approximately 4% of the cell population. Active cell-wall synthesis was found to take place in these cells except at the periphery of the protrusions. On this basis it is suggested that the protrusions are not abnormal growing points but represent osmotically fragile zones where cell-wall synthesis has not taken place.The study was supported by a grant from the National Research Council of Canada.     

Metabolic suppressors of a regulatory mutant in Neurospora

The synthesis of a number of enzymes of sulfur assimilation in Neurospora crassa is controlled by the sulfur source. Mutants in one regulatory gene, cys-3, are unable to make any of the enzymes. This locus is thought to specify a macromolecule that is required for the expression of the structural genes. A mutant, scon ^c, of another regulatory gene is nonrepressible for the synthesis of the enzymes. We report here the isolation of suppressed scon ^c strains which are actually the double mutant, scon ^c,cys-3. These strains are phenotypically indistinguishable from single mutants at the cys-3 locus. Thus cys-3 is epistatic to scon ^c. Evidence that the expression of the cys-3 gene is itself controlled is also presented.This work is supported by a Public Health Service grant, GM-08995, from the National Institute of General Medical Sciences. One of us (R.L.M.) is supported by a Public Health Service Career Development Award.     

Electro-osmotic and biopotential measurements on phloem strands of Nymphoides

Summary Electroosmotic measurements on the excised vascular strand from the petiole of the water plant Nymphoides peltatum have been carried out, and the Onsager coefficients obtained. About 120 water moleculer per ion are carried electroosmotically when the strand is in 10^-4 M KCl, about 30 in 10^-1 M KCl. Potential measurements made on an intact and functioning petiole are discussed in the light of the pressure-flow and electroosmotic theories of translocation.This work has been made possible for one of us (D. S. Fensom) through the assistance of the National Research Council of Canada and a special grant from the Marjorie Young Bell Fund of Mount Allison University.