The lymphocyte as a dosimeter: Comparison of somatic chromosome aberrations in 522 newborn infants and 602 mothers

Summary The frequency of somatic chromosomal aberrations was studied in 522 newborn infants and 602 mothers. Both the rates of aberrations on a per cell basis and the frequency of individuals with varying rates of aberrations were determined. All types of aberrations were more frequent in maternal cells, and the total chromosome break rate in mothers was three times higher than in neonates. Only 2 of the infants had structural rearrangements when 10 cells/newborn were analyzed, compared to 8, or more than 1%, of the mothers. In view of the relative rarity of chromosome aberrations in the neonatal cells, lymphocytes can be utilized as a convenient biological dosimeter for the surveillance of human populations from birth onwards.

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Zusammenfassung Die Häufigkeit somatischer Chromosomenaberrationen wurde bei 522 Neugeborenen und 602 Müttern untersucht. Es wurden sowohl die Aberrationen pro Zelle bestimmt als auch pro Individuum in jeweils 10 Zellen. Alle Aberrationstypen (Gaps, Brüche, Fragmente, Strukturumbau) waren häufiger in mütterlichen Zellen. Die Bruchrate war bei Müttern 3mal höher als bei Neugeborenen. Nur 2 der Kinder hatten strukturelle Umbauten, im Vergleich zu 8 der Mütter (mehr als 1%). Angesichts der relativen Seltenheit von Chromosomenaberrationen in Neugeborenenzellen können Lymphocyten als ein geeigneter biologischer Dosimeter für die Überwachung menschlicher Populationen von Geburt an verwendet werden.

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Research Supported by N. I. H. Contract No. PH 43-6-71463.     

Degradation of Endrin, Aldrin, and DDT by Soil Microorganisms

Twenty microbial cultures which had been shown to degrade dieldrin were tested to determine their ability to degrade endrin, aldrin, DDT, gamma isomers of benzenehexachloride (gamma-BHC), and Baygon. All isolates were able to degrade DDT and endrin, whereas 13 degraded aldrin. However, none of them was able to degrade Baygon or gamma-BHC.     

Histoenzymorphology of β-D-glucuronidase in cortical granules in oocytes of some representative vertebrates

Summary Histoenzymorphologic investigations on -D-glucuronidase in cortical granules in oocytes of some representative vertebrates revealed interesting differences in localisation of the enzyme in the two techniques employed using 8-hydroxyquinoline -D-glucosiduronic acid and naphthol AS-BI -D-glucosiduronic acid as substrates. In the former a nonspecific localisation in the entire cytoplasm of the oocytes excepting nucleus was evident whereas in the latter the cortical granules alone exhibited intense activity. To some extent this difference could be accounted for on the basis of yolk content of the eggs. -D-glucoronidase-rich lysosomal cortical granules were found in the amphibian, reptilian and avian oocytes whereas mammalian oocyte cortical granules were devoid of this enzyme. -D-glucuronidase in cortical granules was sensitive to low concentrations of Hg⁺⁺, Cu⁺⁺, glucuronic and mucic acids. Other histochemical evidence for the lysosomal nature of the cortical granules is presented and discussed. -D-glucuronidase seems to have a role in ovum-nutrition and activation which, thus, make a new addition to the existing knowledge of physiological role of -D-glucuronidase and lysosomes.Dr. A. T. Varute — Research Project guide.     

Unidirectional inhibition and activation of "malic'' enzyme of Solanum tuberosum by meso-tartrate.

A kinetic study of "malic' enzyme (EC 1.1.1.40) from potato suggests that the mechanism is Ordered Bi Ter with NADP+ binding before malate, and NADPH binding before pyruvate and HCO3-. The analysis is complicated by the non-linearity that occurs in some of the plots. meso-Tartrate is shown to inhibit the oxidative decarboxylation of malate but to activate the reductive carboxylation of pyruvate. To explain these unidirectional effects it is suggested that the control site of "malic' enzyme binds organic acids (including meso-tartrate) which activate the enzyme. meso-Tartrate, however, competes with malate for the active site and thus inhibits the oxidative decarboxylation of malate. Because meso-tartrate does not compete effectively with pyruvate for enzyme-NADPH, its binding at the control site leads to a stimulation of the carboxylation of pyruvate. A similar explanation is advanced for the observation that malic acid stimulates its own synthesis.     

Influence of Antitranspirants on Rapeseed (Brassica campestris) Plants under Water-stressed and Nonstressed Conditions

Daily transpiration rate was decreased by low soil moisture, phenylmercuric acetate (PMA) in combination with kaolinite, Mobileaf (a filmforming wax emulsion manufactured by the Mobil Oil Co.), PMA alone, and kaolinite alone in this order. At high soil moisture, dry matter was decreased by PMA but was increased by Mobileaf and by PMA + kaolinite combination. At low soil moisture, dry matter was increased by Mobileaf.     

Membrane lipids and ethanol tolerance in the mouse. The influence of dietary fatty acid composition

Mice of the TO Swiss strain received diets containing different amounts of saturated or unsaturated fat throughout life. These diets produced characteristic changes in cardiac phospholipid fatty acid composition, but produced no significant differences in fatty acid composition of phospholipids from a crude membrane fraction of brain. When littermates of these animals were exposed to ethanol vapour in an inhalation chamber it was observed that mice which had received a diet high in saturated fat lost the righting reflex at an estimated concentration of ethanol in blood higher than that required for mice receiving a control diet, or a diet rich in polyunsaturated fat. Analysis of the brain membrane fraction from those animals which had received ethanol revealed that mice receiving the highly saturated fat diet now had a significantly greater proportion of saturated fatty acids in brain membrane phospholipids. These results are discussed in relation to the hypothesis that brain membrane lipid composition may influence the behavioural response to ethanol.     

Mechanisms of Giemsa banding

Summary We investigated the capability of individual thiazins in Giemsa mixtures (methylene blue and azures A, B, and C) and of two related dyes (toluidine blue and thionin) to produce G-banding. We further tested the effects of variations of buffer composition and concentration, dye concentration, and staining time.G-banding was produced by all of the dyes at low concentrations, although differences were noted. Overall, methylene blue and azure B produced the best banding, azures A, C, and toluidine blue produced moderately good banding, and thionin produced poor banding. This order did not appear to be altered essentially by different treatments. The optimal conditions for G-banding for all dyes and treatments included the use of (1) 0.025–0.05M phosphate buffer, (2) dye concentrations of 0.002%–0.005%, and (3) staining times of 6–15 min.     

Beneficial effects of combination of P and Zn for green gram (Phaseolus aureus L.)

Summary Dicalcium phosphate dihydrate and potassium dihydrogen phosphate were applied to calcareous soil in combination with zinc sulphate in the molar ratio of 100∶0, 100∶1, 100∶2 and 100∶4. Increasing addition of zinc sulphate into P sources gradually increased KCl (0.01M) soluble P and Zn, NaHCO₃ (0.5M, pH 8.5) extractable P and DTPA extractable Zn from soil and grain and straw yields of green gram.