Study on the photochemical reaction of HCN and its polymer products relating to primary chemical evolution

The photochemical reaction of HCN at 184.9 nm is studied in the gas phase. (CN)₂, H₂, CH₄, NH₃, N₂H₄, C₂H₆, and CH₃NH₂ are identified as gas phase products, and a reaction mechanism is proposed. HCN polymers^** are also obtained as solid reaction products, and their structure is investigated by Infrared Spectroscopy, UV-Visible Spectroscopy, Mass Spectrometry, and Amino acid Analysis. The process and nature of the formation of the polymers are discussed.     

Presence of allotypic determinants on polypeptide subunits of rabbit gamma globulin

Inhibition of passive haemagglutination showed the presence of the allotypic specificities Aa1 Aa2, Aa3, Ab4, Ab5 and Ab6 on polypeptide subunits of rabbit IgG belonging to the phenotypes Aa1-3/Ab4-4 Aa2-2/Ab4-4, Aa3-3/Ab4-4, Aa3-3/Ab4-5 and Aa3-3/Ab4-6, prepared by oxidative sulphitolysis followed by isolation on Sephadex G-100 in 6m urea and 0.05m formic acid. The determinants Aa1, Aa2 and Aa3 were found only on H chains and Ab4, Ab5 and Ab6 only on L chains. Of the latter, Ab4 and Ab5 were found in both fractions, i.e. L₁ and L₂, of the light chains, while Ab6 was found only in fraction L₁.     

Mechanism for the Coupled Photochemistry of Ammonia and Acetylene: Implications for Giant Planets,Comets and Interstellar Organic Synthesis

Laboratory studies provide a fundamental understanding of photochemical processes in planetary atmospheres. Photochemical reactions taking place on giant planets like Jupiter and possibly comets and the interstellar medium are the subject of this research. Reaction pathways are proposed for the coupled photochemistry of NH₃ (ammonia) and C₂H₂ (acetylene) within the context Jupiter’s atmosphere. We then extend the discussion to the Great Red Spot, Extra-Solar Giant Planets, Comets and Interstellar Organic Synthesis. Reaction rates in the form of quantum yields were measured for the decomposition of reactants and the formation of products and stable intermediates: HCN (hydrogen cyanide), CH₃CN (acetonitrile), CH₃CH = N-N = CHCH₃ (acetaldazine), CH₃CH = N-NH₂ (acetaldehyde hydrazone), C₂H₅NH₂ (ethylamine), CH₃NH₂ (methylamine) and C₂H₄ (ethene) in the photolysis of NH₃/C₂H₂ mixtures. Some of these compounds, formed in our investigation of pathways for HCN synthesis, were not encountered previously in observational, theoretical or laboratory photochemical studies. The quantum yields obtained allowed for the formulation of a reaction mechanism that attempts to explain the observed results under varying experimental conditions. In general, the results of this work are consistent with the initial observations of Ferris and Ishikawa (1988). However, their proposed reaction pathway which centers on the photolysis of CH₃CH = N-N = CHCH₃ does not explain all of the results obtained in this study. The formation of CH₃CH = N-N = CHCH₃ by a radical combination reaction of CH₃CH = N? was shown in this work to be inconsistent with other experiments where the CH₃CH = N? radical is thought to form but where no CH₃CH = N-N = CHCH₃ was detected. The importance of the role of H atom abstraction reactions was demonstrated and an alternative pathway for CH₃CH = N-N = CHCH₃ formation involving nucleophilic reaction between N₂H₄ and CH₃CH = NH is advanced.     

Distributions of C4 plants along environmental and compositional gradients in southeastern Arizona

Distributional patterns of C₄ plants were investigated in 4 study areas located in se Arizona: granite slopes in the Mule Mountains, limestone slopes in the Mule Mountains, calcareous bajada (alluvial plain) below the Mule Mountains, and limestone slopes in the Huachuca Mountains. Cover data for all vascular species were obtained from 238 0.1 ha (20×50 m) sample quadrats located over ranges of elevation and topographic position within the study areas. Overall, 69 C₄ species representing 6 angiosperm families were encountered. C₄ species accounted for 13.5% to 22.3% of vascular species within the study areas. C₄ species frequency in quadrats (on the basis of all species or of grasses only) increased from mesic to xeric community types in all study areas except the calcareous bajada. Similar, but less consistent, trends were evident in the relative cover contributed by C₄ species. In two of the study areas (granite slopes in the Mule Mountains, limestone slopes in the Huachuca Mountains) regression analyses revealed statistically significant trends of C₄ species frequency and relative cover along environmental (elevation/solar-irradiation scalar) and compositional (reciprocal averaging ordination) gradients. A lack of consistent trends on limestone slopes in the Mule Mountains may be the result of grazing and/or recent invasion of low-elevation limestone areas by a Chihuahuan Desert flora dominated by C₃ dicot shrubs. The calcareous bajada below the Mule Mountains was studied less intensively, but its flora was found to contain the highest frequency of C₄ species of the 4 study areas. In contrast, C₄ cover on the bajada was low, presumably as a consequence of heavy grazing pressure on the grasses. The results of the present investigation support the prediction that C₄ species should be proportionally more successful in habitats characterized by high temperatures, high irradiance and low moisture.     

Enzymatic activity of basidiomycetes

In mycelial acetone powder of the basidiomyceteOudemansiella mucida, the presence of enzymatic systems of NADH₂-oxidase and-dehydrogenase type and of NAD⁺-dependent alcoholdehydrogenase (using ethanol as substrate) has been detected. NADH₂-oxidase has its optimal pH value in the region of 6,0 and is not too active. NADH₂-dehydrogenase which reduces 2,6-dichlorophenolindophenol is very active, may be eluted from the mycelial preparation with water and its adequate pH is in the region of 6,2. On the other hand, NADH₂-dehydrogenase reducing triphenyltetrazolium chloride is non-eluable with water, its activity depends on the presence of menadione and its adequate pH lies in the region of 7,4.     

Isolation and characterisation of immunoglobulins in the serum of precolostral piglets

The presence of actively synthetized immunoglobulin in the serum of newborn precolostral germfree piglets was confirmed. This immunoglobulin, being of IgG antigenic type, carries determinants of typical IgG heavy and light chains and has a sedimentation constant of 4S. The first antibodies formed in germfree piglets after immunization with sheep red blood cells are of macroglobulinemic (IgM) nature. They are followed by formation of more slowly sedimenting antibodies of the IgG type. No fast sedimenting antibodies of the IgG type were detected.     

Formyl-met-tRNA inff supMet,a questionable initiator tRNA in eukaryotic systems

Met-tRNA _inff ^supMet is a much more efficient initiator in cell-free eukaryotic protein synthesis than the formylated species. Chemically and enzymatically formylated Met-tRNA _inff ^supMet exhibit the same activity. In contrast acetyl Met-tRNA _inff ^supMet is unable to initiate polypeptides in vitro.     

Studies on a gram-positive hydrogen bacterium,Nocardia opaca 1 b

Nocardia opaca strain 1 b has a NAD-dependent hydrogenase (hydrogen dehydrogenase). The enzyme has been purified from autotrophically grown cells and tested for optimal assay conditions and stability. The purification procedure involved protamine sulfate treatment, ammonium sulfate precipitation, and separation by DEAE-cellulose and Sephadex G-200 chromatography and resulted in a 63-fold increase of specific activity at a 11.7% enzyme recovery. The final specific activity was 103 μmoles H₂/min·mg protein. The purified enzyme was dependent on nickel and magnesium ions at 0.5 and 5.0 mM concentrations, respectively, as well as flavin mononucleotide at a 5–10 μM concentration. Straight enzyme kinetics were achieved by preincubating the enzyme in the presence of NADH₂. A high stability of the enzyme was observed in 0.1 M potassium phosphate buffer, pH 6.5, in the presence of 0.5 mM nickel and 5 mM magnesium ions under hydrogen atmosphere. Even under air the enzyme was remarkably stable, although less than under hydrogen. From double reciprocal plots of substrate saturation curves the Michaelis-Menten constants were calculated: For saturating NAD-concentration the K _m was 0.063 mM H₂ and for saturating hydrogen concentration the K _m was 0.123 mM NAD.     

Effect of root environment on proton efflux in wheat roots

Proton net efflux of wheat (Triticum aestivum L.) roots growing in sand culture or hydroponics was determined by measuring the pH values of the solution surrounding the roots by pH microelectrodes, by base titration and by color changes of a pH indicator in solid nutrient media. The proton net efflux was dependent on light, aeration, and source of nitrogen (NH ₄ ⁺ , NO ₃ ^? ). Ammonium ions caused the highest proton efflux, whereas nitrate ions decreased the proton efflux. Iron deficiency had no significant effect on proton efflux. Replacement of ammonium by nitrate inhibited proton efflux, whereas the reverse enhanced proton extrusion. A lag period between changes in plant environment and proton efflux was observed. The proton net efflux occurred at the basal portion of the roots but not in the root tips or at the elongation zone. Under optimal conditions, proton efflux capacity reached a maximum value of 5.7 μmole H⁺ g^?1 fresh weight h^?1 with an average (between different measurements) of 3.4 μmole H⁺ g^?1 fresh wth^?1 whereas the pH value decreased to 3.2–3.7 and reached a minimal value of 2.9. Inhibition of ATPase activity by orthovanadate inhibited proton efflux. The results indicate that proton efflux in wheat roots is ammonium ion and light dependent and probably governed by ATPase activity.     

The genes for ribosomal RNA in diploid and polytene chromosomes of Drosophila melanogaster

The proportion of the Drosophila genome coding for ribosomal RNA was examined in DNA from both diploid and polytene tissues of Drosophila melanogaster by rRNA-DNA hybridization. Measurements were made on larvae with one, two, three and four nucleolus organizer regions per genome. In DNA from diploid tissues the percent rDNA (coding for 28S and 18S ribosomal DNA) was found to be in proportion to the number of nucleolus organizers present. The number of rRNA genes within a nucleolus organizer therefore does not vary in response to changes in the number of nucleolus organizers. On the other hand, in DNA from cells with polytene chromosomes the percent rDNA remained at a level of about 0.1% (two to six times lower than the diploid values), regardless of either the number of nucleolus organizers per genome or whether the nucleolus organizers were carried by the X or Y chromosomes. This independence of polytene rDNA content from the number of nucleolus organizers is presumably due to the autonomous polytenization of this region of the chromosome. When the rDNA content of DNA from whole flies is examined, both the rDNA additivity of the diploid cells and the rDNA independence of polytene cells will affect the results. This is a possible explanation for the relative rDNA increase known to occur in X0 flies, but probably not for the phenomenon of rDNA magnification. — In further studies on DNA from larval diploid tissues, the following findings were made: 1) the Ybb-chromosome carries no rDNA; 2) flies carrying four nucleolus organizers do not tend to lose rDNA, even after eleven generations, and 3) the nucleolus organizer on the wild type Y chromosome may have significantly less rDNA than does that on the corresponding X chromosome.     

The role of homoeologous group 1 chromosomes in the control of rRNA genes in wheat

The presence of rRNA genes on homoeologous chromosomes 1A, 1B, and 1D of hexaploid wheat was investigated by rRNA/DNA hybridization, using DNA purified from aneuploid and substitution line derivatives of the variety Chinese Spring. Doubling the number of 1B chromosomes increased the number of rRNA genes by 31–49% but deleting the 1B chromosomes decreased the number by only 15–23%. This suggests that changes may occur in rRNA gene multiplicity at other nucleolar organizer sites to partially compensate for a deficiency of rRNA genes. There was no unequivocal evidence of rRNA genes on Chinese Spring chromosome 1A or 1D, but other varieties were shown to have rRNA genes on chromosome 1A. These results are consistent with the cytological observations that chromosomes 1A and 1B but not 1D possess nucleolar organizers.     

The dynamics of the formation of virus-neutralizing,complement-fixing and immunofluorescent antibodies to the rabies virus in guinea pigs

The aim of the present work was to establish the dynamics of the formation of virus-neutralizing (VN), complement-fixing (CF) and immunofluorescent (IF) antibodies in guinea pig antisera or fractions (IgM, IgG, 7S γ-2 7S γ-1 and F-fraction) obtained by gel filtration on a G-200 Sephadex column, or by chromatography on DEAE cellulose. It was shown that (I) there exists a correlation between the development and titres of VN and IF antibodies. This correlation was observed in both whole serum and its fractions IgG, 7S γ-2 and 7S γ-1 during the whole experimental period. (2) The formation of CF antibodies, followed a different pattern in comparison with VN and IF antibodies. (3) VN, IF and CF antibodies were found to be bound to the IgG fraction, and most of the activity was found in subfraction 7S γ-2. The subfraction 7S γ-1 possessed approximately one half of the activity of fraction 7S γ-2 as regards VN and IF antibodies, and almost no activity of CF antibodies. (4) Both VN and CF antibodies, present in the IgM fraction, reached the maximum in the second blood sample, i.e. 14 days after the first dose of virulent virus. In the further course of the antibody response in guinea pigs, the curve of VN, IF and CF antibodies showed a reversed trend in the whole serum rather than in the IgM fraction.     

On the carrying behaviour of basic South American primates

InCallithrix, Saguinus, Aotus, andCallicebus other group members than the mother participate in infant care. Differences among these species are obvious in respect to the time of being off any caregiver, and in respect to the carrying position (Aotus andCallicebus). Alloparental care, a basic behaviour pattern in these species, has evolved from the parking behaviour of the prosimians. The infants are «parked» at other group members.