Showing papers in "Biochemical Genetics in 1985"

Dietary ethanol and lipid synthesis in Drosophila melanogaster.

Abstract: When cultured on a defined diet, ethanol was an efficient substrate for lipid synthesis in wild-type Drosophila melanogaster larvae. At certain dietary levels both ethanol and sucrose could displace the other as a lipid substrate. In wild-type larvae more than 90% of the flux from ethanol to lipid was metabolized via the alcohol dehydrogenase (ADH) system. The ADH and aldehyde dehydrogenase activities of ADH were modulated in tandem by dietary ethanol, suggesting that ADH provided substrate for lipogenesis by degrading ethanol to acetaldehyde and then to acetic acid. The tissue activity of catalase was suppressed by dietary ethanol, implying that catalase was not a major factor in ethanol metabolism in larvae. The activities of lipogenic enzymes, sn-glycerol-3-phosphate dehydrogenase, fatty acid synthetase (FAS), and ADH, together with the triacylglycerol (TG) content of wild-type larvae increased in proportion to the dietary ethanol concentration to 4.5% (v/v). Dietary ethanol inhibited FAS and repressed the accumulation of TG in ADH-deficient larvae, suggesting that the levels of these factors may be subject to a complex feedback control.

The human glutathione S-transferases: developmental aspects of the GST1, GST2, and GST3 loci.

Abstract: The expression of the GST1, GST2, and GST3 loci in fetal, neonatal, and infant tissues has been studied using starch gel electrophoresis and chromatofocusing. Each locus demonstrated developmental changes in expression, some of which were specific to a single tissue while others occurred in several tissues. GST1 was not usually expressed in any of the tissues studied before 30 weeks of gestation but steadily increased thereafter until adult levels were reached in late infancy. In neonates and older infants the frequencies of the GST1*0, GST1*1, and GST1*2 alleles were 0.79, 0.07, and 0.14, respectively. GST2 was always expressed in liver and adrenal but was only weakly expressed in spleen, cardiac muscle, and diaphragm. In kidney this locus was not usually expressed until nearly 1 year after birth. The GST3 isoenzymes were present in all fetal, neonatal, and infant tissues, although their expression in liver decreased after 30 weeks of gestation. Other isoenzymes with fast anodal mobilities were also identified in several tissues; these are believed to be GST3 isoenzymes that have undergone posttranslational modification rather than products of the putative GST4 locus. No specifically fetal isoenzymes were detected.

Polymorphism of mitochondrial DNA in pigs based on restriction endonuclease cleavage patterns.

Abstract: Restriction endonuclease cleavage patterns of mitochondrial DNA (mtDNA) of pigs and Japanese wild boars were analyzed using 17 enzymes which recognize six nucleotides. The map of cleavage sites was made by double-digestion methods. Polymophism of mtDNA was detected in the digestion by BglII, EcoRV, ScaI, and StuI. The restriction cleavage patterns were identical among the breeds of Landrace, Hampshire, Duroc I, and Large White I (A type). The patterns of Large White II were the same as those of Japanese wild boars (B type). A difference between the A type and the B type of mtDNA was found in the case of three restriction enzymes, BglII, ScaI, and StuI, and the nucleotide alterations between them were estimated as more than six. On the other hand, a difference between mtDNA from almost all pigs and mtDNA from Duroc II was detected using EcoRV. We suggest that the difference of mtDNA between the A type and the B type of mtDNA could result from the different origin of boars, that is, whether they were of European or Asian origin.

Inheritance of the human salivary proline-rich proteins: a reinterpretation in terms of six loci forming two subfamilies.

Abstract: DNA studies suggest that six loci control the synthesis of human salivary proline-rich proteins (PRPs). Genes at two of these loci (proposed names, PRH1 and PRH2) contain regions that strongly hybridize to a probe made from a cDNA in which sites for the restriction enzyme HaeIII occur repeatedly; they code for the acidic PRPs. Genes at the remaining four loci (PRB1, PRB2, PRB3, and PRB4) contain regions that strongly hybridize to a probe with repeated BstN1 sites; they probably code for the basic and glycosylated PRPs. In contrast to these data suggesting six loci forming two gene subfamilies, studies of protein polymorphisms and families have led to the postulation of 13 loci with 11 common null alleles. The discrepancy in the number of loci is partly resolved by the hypothesis that the three acidic PRPs, Db, Pa, and PIF, are coded for by alleles at one of the HaeIII-type loci rather than by three discrete loci.

Allelic constitution of the hemoglobin beta chain in wild populations of the house mouse, Mus musculus.

Abstract: We studied the allelic frequency of the hemoglobin beta chain (Hbb) of wild mice, Mus musculus, collected from 46 localities, mostly in Asia and surrounding areas. The wild populations in the northern part of China, Korea, and the central part of Japan exhibited an almost monomorphic distribution of Hbbp. In the southern part of Asia, the frequency of Hbbp decreased and Hbbd was predominant. Although Hbbs and Hbbd are generally found in Europe, the Hbbp allele was present in Southeastern Europe (Bulgaria). In the light of these results, the Hbbp allele might have originated in mice of northern Asia.

Temperature-related kinetic differentiation of glucosephosphate isomerase alleloenzymes isolated from the blue mussel, Mytilus edulis.

Abstract: Two glucosephosphate isomerase (GPI;D-glucose-6-phosphate ketolisomerase; EC 5.3.1.9) alleloenzymes from the blue mussel,Mytilus edulis, were purified to homogeneity. The steady-state kinetic properties of GPI1.00 and GPI.96, which exhibit latitudinal clines in frequency along the Atlantic coast of North America, were determined in both the glycolytic and the gluconeogenic reaction directions at physiological temperatures and pH levels. The two alleloenzymes are catalytically similar at low temperatures (5–10°C), while GPI1.00 diverges to become more efficient at higher physiological temperatures (15–25°C). This pattern of differentiation is consistent with the latitudinal distributions of the alleloenzymes and is due to the greater temperature sensitivities of GPI1.00 V max /K m values of the two alleloenzymes are virtually the same over the physiological range of temperatures. The observed pattern of catalytic differentiation is similar to that seen for interspecific GPI variants.

Immunological characterization of human acid phosphatase gene products.

Abstract: The immunological cross-reactivity of heterogeneous acid phosphatase isozymes from different human tissues has been studied using monospecific antisera prepared against four homogeneous acid phosphatases. The enzyme characterized as tartrate-inhibitable, prostatic acid phosphatase is also found to be present in leukocytes, kidney, spleen, and placenta. The tartrate-inhibitable (liver) lysosomal enzyme is also found in kidney, fibroblasts, brain, placenta, and spleen, but it is not detectable in erythrocytes and prostate. In several tissues, 10-20% of the tartrate-inhibitable enzyme is not precipitated by any of the antisera used; an exceptionally high amount (54%) of such an enzyme is present in human brain. Antiserum against a low molecular weight tartrate-resistant liver enzyme (14 kDa) does not crossreact with the erythrocyte enzyme. (10-20 kDa). All other tissues except placenta, prostate, and fibroblast cells show a cross-reactivity with the 14-kDa acid phosphatase antiserum. Thus, the low molecular weight human liver acid phosphatase is distinct from the erythrocyte enzyme, and there are also at least three different tartrate-inhibitable acid phosphatases in human tissues. Chromosomal assignments have been made for only two of the (at least) five acid phosphatases that are present in adult human tissues.

Polymorphism at the Hor 1 locus of barley (Hordeum vulgare L.).

Abstract: The Hor 1 locus of barley encodes a group of seed storage polypeptides called C hordein. Two-dimensional electrophoretic analysis of C-hordein fractions from six cultivars with different alleles at the Hor 1 locus showed extensive polymorphism. A total of 34 major polypeptides was mapped, with between 4 and 18 present in each cultivar. There was less variation among the same cultivars in the numbers (6 to 10) of restriction fragments of genomic DNA which hybridized to a cDNA clone related to C hordein. The total number of restriction fragments was also lower (22), and most pairs of cultivars had more restriction fragments than polypeptides in common. A total number of about 20–30 C-hordein genes per haploid genome was estimated. The results indicate that cultivars differ mainly in the extent of gene and polypeptide divergence, rather than in the degree of gene reiteration. They are consistent with the proposed origin of the multiple structural genes at the Hor 1 locus by the duplication and divergence of a single ancestral gene.

Electrophoretic analysis of genetic variability in the house fly (Musca domestica L.).

Abstract: Methods are described for the resolution of house fly, Musca domestica L., enzymes by vertical polyacrylamide gel electrophoresis. An electrophoretic survey in Ames, Iowa, of 51 loci distributed among 26 enzyme systems revealed that 40% of the loci are polymorphic. Observed and expected heterozygosities measured at 33 loci were 0.0981 and 0.1148, respectively. A significant deficiency of heterozygotes was noted at certain loci.

Human lactase and the molecular basis of lactase persistence.

Abstract: Human lactase purified from detergent extracts of the total membrane fraction of postmortem jejunum by means of monoclonal immunoadsorbent chromatography appears to be a dimer of subunits identical in Mr (160K). Trypsin or papain removes a small hydrophobic anchoring peptide from each subunit to give a hydrophilic enzyme which no longer interacts with detergent micelles. Lactase hydrolyzes, besides lactose, cellobiose and the synthetic substrates, 4-methylumbelliferyl-β-galactoside and β-glucoside, as well as phlorizin; but it does not hydrolyze glucocerebroside. Phlorizin hydrolase is associated with lactase under all conditions investigated; coincident staining on immunodiffusion and immunoelectrophoresis, coincident elution on immunoadsorbent chromatography and on gel filtration in a dissociating buffer, and correlated reduction in activity in lactase-nonpersistent individuals. Adult and infant lactases are indistinguishable by titration or immunodiffusion against polyclonal rabbit antibodies. Adult individuals low in lactase activity also show a corresponding reduction in cross-reacting material. These observations suggest that lactase persistence is due to the continued synthesis of the infant enzyme.

The alcohol dehydrogenase alleloenzymes AdhS and AdhF from the fruitfly Drosophila melanogaster: an enzymatic rate assay to determine the active-site concentration.

Abstract: A rapid and reproducible enzymatic rate assay for the quantitative determination of the concentration of active sites is presented for the alleloenzymes AdhS and AdhF from Drosophila melanogaster Using this procedure the turnover numbers as catalytic-center activities were found to be 122 sec−1 for AdhF and 34 sec−1 for AdhS with secondary alcohols This showed a slower dissociation of the coenzyme from the binary enzyme-NADH complex with AdhS and hence a stronger binding of NADH to this alleloenzyme With ethanol, the catalytic-center activity was 14 sec−1 for AdhS and 28 sec−1 for AdhF, and hence the single amino acid mutation distinguishing the two alleloenzymes also affected hydride transfer

Genetic variability of proteins from mitochondria and mitochondrial fractions of mouse organs.

Abstract: Proteins of whole mitochondria from mouse liver and brain and proteins of liver mitochondrial fractions (plasma and rough membrane fraction) were separated by two-dimensional electrophoresis. Protein patterns of two inbred strains of mouse, C57BL/6J and DBA/2J, and of F1 mice of these two strains were studied. The protein patterns obtained from the different mitochondrial materials were analyzed with regard to their protein composition and the genetic variability of proteins (qualitative and quantitative protein variants). Included in this analysis are data previously obtained from the cytosols and plasma membranes of the same organs and mouse strains. The results showed the following. (1) Mitochondria and organelle-free cell components (cytosol and plasma membranes) have only a few percent of their proteins in common, while two organs, liver and brain, reveal up to approximately 50% organ-nonspecific proteins. The frequency of proteins common to solubilized and structure-bound proteins ranges below 20%. (2) Genetic variability in protein amount occurs much more frequently than genetic variability in protein structure. Liver proteins reveal more genetic variants than brain proteins. Proteins solubilized in the cell show more genetic variation than structure-bound proteins. Furthermore, the results show that with regard to the composition and the genetic variability of proteins, liver and brain differ more in their mitochondria than in their cytosol and plasma membranes.

Bovine mitochondrial DNA polymorphism in restriction endonuclease cleavage patterns and the location of the polymorphic sites.

Abstract: Cleavage patterns of mitochondrial DNA (mtDNA) by restriction endonuclease analysis were examined in four Japanese Black cows, three Japanese Shorthorn cows, and six Holstein cows. Seventeen restriction enzymes which recognize six base pairs and two restriction enzymes which recognize four base pairs were used in this study. Polymorphism was observed with three restriction enzymes, HindIII, TaqI, and MspI, and was detected within the breeds. Nucleotide substitution was determined in the HindIII polymorphic site by DNA cloning and sequencing; this is C ↔ T at position 10126 of the URF-3 region. Furthermore, the MspI and TaqI polymorphic sites were located on the physical map.

Absence of developmental incompatibility in hybrids between rainbow trout and two subspecies of cutthroat trout.

Abstract: We examined the developmental rate of hybrids between rainbow trout (Salmo gairdneri) and two subspecies of cutthroat trout: westslope cutthroat trout (Salmo clarki lewisi) and Yellowstone cutthroat trout (Salmo clarki bouvieri). These taxa show considerable genetic divergence at 42 structural loci encoding enzymes; the mean Nei's d between the rainbow trout and the two species of cutthroat trout is 0.22. We used four measures of developmental rate: time of hatching and yolk resorption, rate of increase in activity of four enzymes, and time of initial detection of seven isozyme loci. The two cutthroat trout subspecies reached hatching and yolk resorption earlier than rainbow trout. Cutthroat trout had higher relative enzyme activities than rainbow trout from deposition of eye pigment to hatching. There was no difference in the rate of increase in enzyme activity or time of initial expression of these loci between these species. Hybrids showed developmental rates intermediate or similar to that of the parental species using all measures. Our results indicate an absence of regulatory and developmental incompatibility between these taxa.

Two-dimensional gel electrophoresis of proteins for genetic studies in Douglas fir (Pseudotsuga menziesii).

Abstract: A method of two-dimensional gel electrophoresis of proteins from Douglas fir needles is described. Extraction in the presence of sodium dodecyl sulfate (SDS) and 2-mercaptoethanol followed by heating at 100°C produces reliable two-dimensional gels which are convenient for genetic studies. Three genotypes from different geographical origins have been compared: among 225 loci expressed, 22 display regulatory variations and 7 show allelic variations. Thus it is now possible to undertake the genetic study of Douglas fir using this powerful technique.

Genetics, subcellular localization, and molecular characterization of 6-phosphogluconate dehydrogenase isozymes in tomato.

Abstract: Three independent genes are responsible for 6-phosphogluconate dehydrogenase (6PGDH) activity in tomato. 6Pgdh-2, located on chromosome 12, codes for subunits of an active dimer which is restricted to the plastids. 6Pgdh-1, chromosome 4, and 6Pgdh-3, chromosome 5, code for subunits which form three dimers—two homodimers and an intergenic heterodimer. The latter three isozymes are found in the cytosol. 6Pgdh-1, 6Pgdh-2, and 6Pgdh-3 code for subunits with estimated molecular weights of 49,500, 50,500, and 51,200, respectively. The intergenic heterodimer encoded by 6Pgdh-1 and 6Pgdh-3 is thus composed of subunits that differ in length by approximately 15 amino acid residues. Divergence in the length and primary subunit structure may account for the lower thermal stability of the intergenic heterodimer compared with the corresponding homodimers. A limited survey of other solanaceous plant species suggests that the duplication of cytosolic 6PGDH-coding genes found in tomato may be widespread in the family.

The influence of the genes An1, An2 , and An4 on the activity of the enzyme UDP-glucose:Flavonoid 3- O -glucosyltransferase in flowers of Petunia hybrida

Abstract: A relation between gene dosage and UDP-glucose:flavonoid 3-O-glucosyl-transferase (UFGT) activity was found in homozygous dominant and recessive parental lines and their F1 progeny for both of the genes An1 and An2. In both F2 crosses, progeny plants could be classified as belonging to groups showing either a low or a medium to high UFGT activity. Test crosses showed that heterozygous and homozygous dominant plants were present throughout the medium- to high-active group. The dosage relation in F2 plants is most probably confounded by the segregation of modifiers. Thermal inactivation experiments indicated that structurally different UFGT enzymes are formed in homozygous dominant lines as well as in lines homozygous recessive for either An1 or An2. Lines homozygous recessive for the gene An4 contain a UFGT with a half-life time at 55° C of less than 8 min, whereas UFGTs from lines homozygous dominant for An4 show a half-life time of 25 min or above, with one exception. This relation was confirmed in the F2 progeny; heterozygotes for An4 showed an intermediate half-life time. It is concluded that An4 might be the structural gene for the enzyme; An1 and An2 are both regulatory genes. UFGT activity in flowerbuds of An4/An4 plants seems to be lower than in an4/an4 plants. Anthers of flowers of an4/an4 lines, however, are virtually devoid of UFGT activity.

The expression of creatine kinase isozymes in Xenopus tropicalis, Xenopus laevis laevis, and their viable hybrid

Abstract: Starch gel electrophoresis of creatine kinase (CK) isozymes of Xenopus tropicalis shows that at least two different genes code for CK in this diploid (2n=20) species. These genes seem to be orthologous to the CK-A and CK-C genes of extant crossopterygian fish. Additional isozymes may be interpreted either as products of duplicate genes or, more probably, as epigenetically modified forms of the homodimers AtAt and CtCt, respectively. The originally tetraploid species X. laevis laevis (2n=36), which may have arisen by hybridization of diploid ancestors some 30–40 million years ago, has retained expression of all duplicate CK-A and CK-C genes. Differential expression during ontogenesis (CK-A genes) and in different adult tissues (CK-C genes) indicates that divergence occurred not only with respect to the primary sequence of these duplicate genes, but also with respect to the regulation of their expression. In the interspecific hybrid X. 1. laevis × X. tropicalis, all parental CK genes appear to be expressed simultaneously in the heart. However, several subunit combinations cannot be detected on the zymograms.

Inheritance of allozyme variants in bishop pine (Pinus muricuta D. Don).

Abstract: Isozyme phenotypes are described for 45 structural loci and 1 modifier locus in bishop pine (Pinus muricata D. Don,) and segregation data are presented for a subset of 31 polymorphic loci from 19 enzyme systems. All polymorphic loci had alleles that segregated within single-locus Mendelian expectations, although one pair of alleles at each of three loci showed significant segregation distortion. The consistency of resolution and segregation at many loci in bishop pine makes electrophoretic analyses feasible for many purposes in this species.

Genetics of Biomphalaria glabrata: linkage analysis of genes for pigmentation, enzymes, and resistance to Schistosoma mansoni.

Abstract: The snail, Biomphalaria glabrata, is a major intermediate host of the human blood fluke, Schistosoma mansoni, in the Americas. The inheritance and linkage relationships of a gene enabling adult snails to resist infection by a Puerto Rican strain of the parasite were analyzed using two laboratory stocks that differed in susceptibility, pigmentation, and five electrophoretically detectable enzyme markers. Segregation ratios in second-generation intraspecific hybrids between susceptible (M-stock) and resistant (10-R2-stock) snails indicate that the susceptibility gene is not linked to the enzyme (ACON-1, ACP, EST-2, PEP-2, PGD) or pigmentation loci studied. These seven loci assort independently of one another. Observed rates of infection among F1 and F2 progeny are consistent with Richards' finding that adult susceptibility to the PR-1 strain of S. mansoni is controlled by a single locus with resistance dominant. No association between allozymes of acid phosphatase and snail susceptibility to PR-1 was seen in the snail-parasite combinations studied.

Neurospora glucamylase and a mutant affected in its regulation.

Abstract: Neurospora glucamylase is a glucose-repressible extracellular enzyme. The enzyme was purified to homogeneity and found to have a molecular weight of 82,000 and to release glucose from either maltose or amylose. The rate of glucamylase synthesis increases more than 100-fold when cells are transferred from a glucose-containing medium to a glucose-free medium. Increased production of glucamylase begins within 30 min of the transfer. Glucamylase is rapidly secreted into the medium. A mutant affecting the ability of glucose to repress the synthesis of the glucose-repressible extracellular enzymes glucamylase and invertase has been isolated and studied. The mutant constitutively synthesizes and secretes a glucamylase which is indistinguishable from the wild-type enzyme.

Yolk polypeptide gene expression in Minute Drosophila females.

Abstract: Minutes have been considered for some time to be mutant at the sites of synthesis of some components of the protein synthetic apparatus. To study the hypothetical relationship between Minutes and suboptimal translation, a group of abundant proteins, the yolk polypeptides, was assayed in outcrossed females bearing M(3)w, M(3)h y , or M(1)n mutations. Recently emerged Minute females contained a lower amount of yolk polypeptides, in both ovarian and nonovarian tissues, than their non-Minute sisters. This low level correlated with the lower abundance of cytoplasmic RNA in Minutes compared to control females. By 1 week of age, both M(3)w and their non-Minute sibs contained the same amount of yolk polypeptides and the corresponding mRNA. The double heterozygote, ap 4/+;M(3)w/+, did not differ in yolk polypeptide content from control flies. M(3)w females demonstrated reduced fecundity during the period of low yolk polypeptide content but gradually increased egg deposition as yolk polypeptide levels rose. These results suggest that the low protein levels are due to the slower maturation of M(3)w, and not to less efficient translation machinery.

Isozyme relative mobility (Rm) changes related to leaf position; apparently smooth Rm trends and some implications.

Abstract: Relative mobilities (Rm's) of peroxidase and acid phosphatase isozymes were examined in leaves of flax (Linum usitatissimum L.). The leaves were sampled from four equidistantly spaced positions from main stem base to apex in various genotypes.Rm's for the two slowest-migrating isozymes of each enzyme system changed in a simple, coherent fashion in leaves from stem bases toward apices. TheRm trends up the stem seen in two highly branched flax types were somewhat different from those in two sparsely branched types. The coherentRm trends in the four types, suggesting a smooth continuum and a potentially large number of slightly different forms of these isozymes, are discussed in relation to other data for suchRm trends. In the study reported here, both enzyme systems behaved similarly. This fact and the simple Mendelian genetical system with no codominance controllingRm's in flax peroxidases and acid phosphatases suggest posttranscriptional or posttranslational modifications as plausible mechanisms underlying the numerous, presumably small molecular changes generating the small, consistent changes inRm's.

On the nature of L-xylulose reductase deficiency in essential pentosuria.

Abstract: Essential pentosuria is the result of a partial deficiency of L-xylulose reductase. Red blood cells of normal individuals have been found to contain two L-xylulose reductases: a major and a minor isozyme. Red cells from pentosurics contain only one isozyme. The residual enzyme of pentosurics and the normal minor isozyme have similar Michaelis constants for L-xylulose and xylitol, similar activity responses to pH, and similar rates of migration when electrophoresed or subjected to ion-exchange chromatography. It is suggested that homozygosity for the pentosuria allele results in the absence of the major isozyme and that the residual isozyme of pentosurics is identical to the minor isozyme of normal individuals.

Tissue-specific developmental regulation of superoxide dismutase (SOD-1 and SOD-2) activities in genetic strains of mice

Abstract: The activity levels of CuZn superoxide dismutase (SOD) (SOD-1) and Mn SOD (SOD-2) in liver, kidney, and lung were assessed in newborn and 3-, 10-, 25-, and ∼70-week-old females from seven genetic strains (BALB/c, Csb, C3H/HeSnJ, C3H/S, C57BL/6J, Swiss-Webster, and 129/ReJ) of mice. Total SOD enzyme activity was high at birth and declined somewhat with old age (∼70 weeks) in the liver and increased in both kidney and lung from newborn to 25 weeks. The activity level of SOD-1 was found to be highly variable among strains at different ages in liver, with little change associated with aging in the kidney, and showed a strain-specific increase during aging in the lung. In general, SOD-2 activity was lower than SOD-1 activity in liver and lung but levels of the two forms of this enzyme were similar in the kidney. The SOD-2 activity increased with age with little variation among strains in kidney. The increase in this form of the enzyme with age was relatively small and strain specific in lung and highly variable among strains in the liver. The Csb genotype (acatalasemic) at age ∼70 weeks showed an exceptionally high SOD-1 activity associated with an exceptionally low SOD-2 activity in the liver. Changes in enzyme activity with age in different tissues associated with differences in activity level among genotypes (of the type reported here for SOD-1 and SOD-2) may be indicative of a complex system of enzyme regulation. Further studies are needed to explain fully the genetic/molecular mechanism(s) for SOD regulation.

Genetic and physiological parameters associated with cadmium toxicity in Drosophila melanogaster.

Abstract: Two strains of Drosophila melanogaster represent the extremes in resistance and sensitivity to the lethal effects of CdCl2. The strain containing the mutations vermilion and brown (v; bw) and the strain Austin had LC50's of 3.3 and 1.3mm CdCl2, respectively. The three major chromosomes from these two strains were assorted genetically into the six possible combinations. The measured LC50's for CdCl2 for these six genotypes fell into two groups according to the X chromosome; those containing the X chromosome from v; bw had LC50's 0.5–1.0mm greater than those in which the X chromosome was from Austin. Since the parent strains differed by 2mm, we suggest that the X chromosome is a major, but not the sole, site of genes to produce resistance to CdCl2. When 109Cd was in the diet the uptake by v; bw and Austin over 2 days was the same. After 4 days of uptake, the Austin strain excreted the 109Cd five times faster than v; bw but the six genotypes did not differ appreciably in excretion rate from one another and resembled the sensitive parent Austin more than the resistant one. Thus a second process is indicated that distinguishes resistance to CdCl2 that apparently is not associated with the X chromosome.

Biochemical properties, homology, and genetic variation of Drosophila "nonspecific" esterases.

Abstract: The biochemical properties and tissue distribution of two major, soluble “nonspecific” esterases have been studied in Drosophila melanogaster, D. pseudoobscura, and related species. The “α-like” activity is due to a monomer enzyme (MW⋍60 kd) having a nonspecific tissue distribution, which was inhibited by p-hydroxymercuribenzoate (5×10−4 m) plus eserine (1×10−5 m) and was relatively unstable during polyacrylamide gel electrophoresis. Electrophoretograms of this enzyme could be enhanced by treating gels with β-mercaptoethanol before staining. This procedure allowed the identification of a new α-esterase (Est-4) in D. pseudoobscura. The “β-like” esterase activity (EC 3.1.1.1) is due to a dimer (MW⋍120 kd) in most Drosophila species. D. melanogaster and its siblings (D. simulans and D. mauritiana) were exceptions in which this enzyme had an unusual tissue distribution (increased activity in the male reproductive system) and was a monomer (MW⋍60 kd). Differences in the genetic variability of these esterases are discussed and interpreted by a population expansion model rather than by differences in biochemical properties of enzyme forms.

Localization of the gene for the vitamin B12 binding protein, transcobalamin II, near the centromere on mouse chromosome 11, linked with the hemoglobin alpha-chain locus

Abstract: Somatic cell hybrids, recombinant inbred (RI) mouse strains, and backcross breeding experiments were used to locate the gene of transcobalamin II (Tcn-2), the vitamin B12 binding protein in mouse serum. TCN-2 was found to be a useful genetic marker in the somatic cell hybrids. Selected hybrid clones were derived from fusions between GR mouse cells and the Chinese hamster cell line E36. Analysis of mouse specific chromosomal enzyme markers in relationship to TCN-2 secretion, in the hybrid clones, provided provisional evidence for assignment of the Tcn-2 locus to chromosome 11. The strain distribution pattern of the TCN-2 variants S and F in the RI series CXS, constructed from the cross of BALB/cHeA (TCN-2S) with STS/A (TCN-2F), implied a close linkage with the hemoglobin alpha-chain locus (Hba) on chromosome 11. Backcross breeding using inbred strains confirmed these findings and located the Tcn-2 gene closest to the centromere, linked with waved 2 (wa-2) and Hba with recombination frequencies of 6.9 and 19.2% each. The linkage group Tcn-2/wa-2/Hba was established.

Description of a genetic polymorphism of a human proline-rich salivary protein, Pc, and its relationship to other proteins in the salivary protein complex (SPC).

Abstract: A new polymorphism, Pc, has been identified in human saliva. Two proteins, Pc 1 and Pc 2, are determined by alleles Pc1and Pc2, respectively, which show autosomal codominant inheritance. No null phenotype has been encountered in 225 randomly collected salivas. The frequencies of the two alleles differ in the Black and White American populations, with Pc1and Pc2being 0.670 and 0.330 in the Black (N=47) and 0.461 and 0.539 in the White (N=178) populations, respectively. The alleles are in equilibrium in the two populations and segregation analyses (30 families) do not suggest the existence of a null allele in either population. Of seven polymorphic human salivary proteins determined by genes in the salivary protein complex (SPC), Pc phenotypes show association only with Ps phenotypes. Based on that association, our linkage studies, and the biochemical similarities with other SPC proteins, we tentatively conclude that Pc is a member of the SPC, bringing the total number of genes in that group to 13.

Enzymatic activity of atypical Oriental types of aldehyde dehydrogenases

Abstract: Catalytic activity of the atypical Oriental-type aldehyde dehydrogenase-2 (ALDH2) was considered to be null or severely diminished. Recently it was suggested that the atypical ALDH 2 2 retained about 30% of the specific activity of the usual ALDH 2 1 . We reexamined the problem by two-dimensional crossed immunoelectrophoresis. The usual Caucasian livers exhibited two distinctive precipitin peaks, one corresponding to the cytosolic ALDH1 and the other corresponding to the usual mitochondrial ALDH 2 1 , in both protein stain and enzyme activity stain. In contrast, the atypical Oriental livers exhibited two precipitin peaks in protein stain, but only one peak, corresponding to ALDH1, in enzyme activity stain. These results support the original notion that the atypical ALDH 2 2 is enzymatically inactive or far less active than the usual enzyme, refuting the idea of the atypical ALDH 2 2 with substantial enzyme activity.