ALBERT

Notes: Seeds of yellow foxtail, johnsongrass, pigweed and quackgrass were investigated to determine the effects of certain herbicides on water uptake by these species. Seeds of johnsongrass showed slight increase in water uptake over the 20-h period when treated with 1, 5, 10, and 500 mg/1 of 2,4-D. Tordon caused a most pronounced increase in water uptake at 0.1 and 1 mg/l as compared with the controls. Johnsongrass gave indications of either increases or decreases in water uptake when treated with herbicides during the 20-h period, but showed no effects during the 10-h period. Dormant seeds of yellow foxtail indicated an enhancement in water uptake at all 2,4-D concentrations during the 20 h period. The effects which the different herbicides had upon the uptake of water in yellow foxtail seeds seemed to be directly proportional to increase in imbibition time. In all cases, more water was imbibed after 20 h over that observed at 10 h. During the 10-h imbibition period, pigweed seeds treated with 2,4-D was noted to have a slight stimulating effect on water uptake at all concentrations employed except 5 mg/l, which indicated a depressing effect. It was also observed that 2,4-D caused a significant stimulating effect on water uptake of pigweed seeds over the 20-h period as compared with the controls. A stimulation in the total quantity of water imbibed after 20 h was noted at dacthal concentrations below 100 mg/l whereas at the 500 mg/l, a slight depression in water imbibition was observed. At dalapon concentrations of 1 to 100 mg/l, a marked stimulation in total water imbibed by quackgrass seeds was shown during the 10-h period.

Notes: The effects of 4 chemicals on the germination promotion of stratified and unstratified seeds of loblolly pine (Pinus taeda) and baldcypress (Taxodium distichum) were studied. The chemicals used were gibberellic acid, kinetin, potassium nitrate and thiourea, each at 3 different concentrations.Stratification promoted the germination of both seed species. Certain concentrations of gibberellic acid, potassium nitrate and thiourea improved the germination of unstratified loblolly pine and baldcypress seeds while kinetin had no stimulatory effect.All 4 chemicals at specific concentrations promoted the germination of loblolly pine seeds stratified for a short period of time. Considering both speed and completeness of germination, best results were obtained when 21-day stratified seeds were treated with either gibberellic acid (100 mg/1) or kinetin (10 mg/1). In baldcypress, on the other hand, none of these chemicals had any stimulatory effect on the germination of stratified seeds. Germination of both species of seeds was either partially or completely inhibited by the highest concentration of thiourea (30,000 mg/1) used.

Notes: The seeds of loblolly pine (Pirns taeda L.) were cold-stratified for 0, 14, 28, 42, and 56 days. Endogenous growth regulators were extracted from these seeds, and also from the germinating and the 28-day warm stratified seeds. Partially purified extracts were separated on chromatographic paper. The chromatograms were cut into 10 equal segments, and these were tested for biological activity using three different btoassays.The results indicated that the unstratified seeds and those stratified up to a period of 28 days contained very little or no growth promoter (GA-like substances), and a relatively high concentration of an inhibitor (presumably abscisic acid), Following 42-day stratification, the promoter concentration gradually increased while the inhibitor level fell almost to zero. A high level of promoter but no inhibitor was detected in germinating seeds.No auxin-like activity was noted in the unstratified seeds. This activity slowly increased up to a period of 28 days and remained at this level for the subsequent stratification periods. However, the activity greatly increased in the germinating seeds.Very little changes in the levels of growth regulators were noted in warm-stratified seeds as compared to the unstrati-fied controls.

Notes: Summary Interactions of cationic dye methylene blue with small polyanions like inositol hexasulfate, adenosine-triphosphate, ammonium molybdate, potassium ferro- and ferricyanide have been studied spectrophotometrically and conductometrically to ascertain the chromotropic characters of these polyanions. Results show that while almost all of them bind the dye stoichiometrically, none of them except ammonium molybdate is a chromotrope in the sense in which heparin, chondroitin sulfate etc. are. Inositol hexasulfate induces an intermediate spectra, though not perfectly metachromatic as is the case with inositol hexaphosphate. It is concluded that a chromotrope need not be a macromolecule to induce metachromasia in a dye solution, but the minimum number of charges per polyanion to give it a chromotropic character will vary with the nature of the polyanion.

Notes: Summary Photosensitization processes provoked by furocoumarins on various biological systems seem to be in connection with the photoreactions that these substances give bothin vitro andin vivo with pyrimidine bases of nucleic acids; in particular linear furocoumarins (psoralen) photoreact with native DNA giving both monofunctional and bifunctional additions (forming in this last case inter-strand cross-linkings) while angular furocoumarin (angelicin) can give only monofunctional additions. Previous studies on the possible recovery of this damage to DNA provoked both by linear and angular furocoumarins demonstrated that no repair underwent either by means of photosplitting experiments or through photoreactivation processes. In this paper are reported direct results indicating that the photodamage to DNA is repairable through post-irradiation dark recovery both operating on microbial cultures and on guinea-pig skin. In both biological systems monofunctional additions appear much more easily repairable than bifunctional additions; in any case bifunctional additions (which produce inter-strand cross-linkings) clearly appear to be repairable.

Notes: Résumé Les observations limnologiques régulières dans la partie Sud du Lac Volta révélaient des changements significatifs dans la transparence, la couleur, la quantité totale de fer et l'oxygène dissout pour la période de 1965 à 1966 mais rien de semblable pour celle de 1966 à 1967. Ces facteurs montraient aussi des corrélations si significatives que beaucoup d'entre eux pouvait être estimé à partie de la simple mensuration de la seule transparence. La densité de phytoplancton ne changeait pas de manière significative que ce soit de 1965 à 1966 ou de 1966 à 1967. Toutefois, les principaux constituants passaient par une série de changements allant des algues vertes (Actinatrum) au début de 1965, aux flagellates (Cryptomonas et Peridinium) de 1965 à 1966 puis aux diatomées (Nitzschia et Synedra) de 1966 à 1967. La densité de phytoplancton presentait une corrélation significative uniquement avec l'oxygène dissout duquel il pouvait être grossièrement estimé.

Notes: Abstract Four chemical agents, EMS EMS: Ethyl methanesulfonate; MNNG: N-methyl-N\t'-nitro-N\t'-nitrosoguanidine; NA: Nitrous acid; ICR-170: 2-methoxy-6-chloro-9-[3-(ethyl-2-chloroethyl) aminopropylamino] acridine 2 HCl; UV: Ultra violet radiation. , MNNG, NA, ICR-170, as well as UV were used to induce mutations in the wild-type haploid strain X2180-1B (α) of Saccharomyces. A total of 2053 (EMS, 427; MNNG, 444; NA, 469; ICR-170, 456; UV, 257) lysine-requiring mutant clones were isolated from many independent treatments and by nystatin enrichment technique. Mutants were classified into various functional groups on the basis of complementation analysis with 14 tester strains (lys 1 to lys 15 except lys 3). Of the clones analyzed, the number of isolates unable to complement with a given tester strain ranged from 2 for lys 5 to 918 for lys 4. Three of the mutually complementing lysine loci (lys 1, lys 2, and lys 4) accounted together for over 85% of the mutant clones whereas lys 6, lys 7, lys 8, and lys 14 had less than 10 noncomplementing isolates each. Mutants for lys 4 were most frequent with all of the mutagens tested except with NA in which case the mutants for lys 2 were most frequent. A total of 56 isolates failed to complement with lys 10, lys 11, and lys 12. Similarly, 47 isolates failed to complement with lys 9 and lys 13 simultaneously. Only 44 isolates complemented with all of the tester strains used.

Notes: Summary Regular observations at an affshore station near the dam showed a stratified distribution of phytoplankton from 1964 to 1966, interrupted only by the seasonal flood. Thereafter, the operation of hydroelectric turbines together with occasional spilling reversed the pattern to an overturned distribution irrespective of the season. The substantially increased outflow during this period reduced the stability and prevented stratification in the proximity of the dam. There was an appreciable increase of phytoplankton dominated by the diatom Synedra acus Kuetzing during 1968.

Notes: Summary Transformations of two linked ribosomal loci (str and ery) were carried out between the SIII-1 strain of pneumococcus and the Challis and SBE strains of group H streptococcus. Transfer of markers between the Challis and SBE strains is as efficient as in the corresponding intrastrain transformations. Transfer between either of these strains and the pneumococcus, however, is less efficient than in the corresponding intrastrain transformation, and is referred to as heterospecific transformation. The inefficiency of the heterospecific transformation is due neither to specific lethality nor reduced uptake of heterologous DNA. When DNA was extracted from the hybrid resulting from a heterospecific cross and used to transform the original donor and recipient species, we found: (a) no donor material in the hybrid DNA responsible for the markedly low efficiency of integration into the recipient species; (b) donor material, in addition to the transforming marker itself, detectable by the higher efficiency with which hybrid DNA transforms the original donor species than does DNA from the original recipient species. DNA was extracted from each of 36 independently derived, doubly marked transformants resulting from the cross: Challis str-s ery-sxSIII-1 str-r53 ery-r2 DNA. Variability was observed between the different hybrid DNAs when the integration efficiency of the str marker in each DNA was compared with that of the ery marker. Variability of as great a magnitude was not observed when the same hybrid DNA was tested in repeated experiments, or when different DNA preparations were extracted from the same hybrid strain, or when several DNA preparations were obtained from a number of independent homospecific transformants. It is concluded that different kinds of donor material are present in the various hybrids, and that the nature of this extra-marker material affects the integration of the marker. Linkage of the str and ery markers was reduced in heterospecific transformations. The kind of donor DNA in the hybrid genome did not affect the linkage reduction observed when the str and ery markers were transferred back to the donor species in which they originated. Indeed, this linkage reduction was the same as that observed when the markers were originally transferred from the SIII-1 to the Challis strain. Specific factors reducing linkage in heterologous crosses must, therefore, be distinct from other factors which affect integration efficiency. The former, however, may be primarily responsible for the inefficiency of heterospecific transformation. One of the hybrid DNAs was used to obtain a second generation of hybrids by passing it through each of the original parental strains. Tests of the DNAs extracted from 24 independently produced, second-generation hybrids showed that hybrid DNA is subject to further alteration by a second integration involving some heterologous confrontation. The probability of such alteration appears to be increased if the second integration is accompanied by linkage reduction.

Notes: Summary A class of mutants with SmR (streptomycin resistance) phenotype has been isolated from a strA1/strA + (streptomycin resistant allele/streptomycin sensitive allele) heterozygote merodiploid. The mutation is located in the strA gene of the E. coli chromosome. However, the streptomycin phenotype of the haploid strain is not altered. It has been suggested that the alteration in the structure of the strA + gene product (protein S12 which forms an integral part of the 30S subunit) leads to a change in the assembly of the smaller subunit. Thus, a possible mechanism for the mutation is postulated in the regulation of ribosomal subunit formation at the assembly step.