Myocardial infarct death and temperature in Auckland,New Zealand

Daily myocardial infarct deaths for Auckland (36° 51S, 20 m above sea-level) show an increase in mortality rate with decreasing temperatures over the entire thermal range. Parallel studies in Brisbane and Montreal predicted a minimum death temperature between 21 and 24° C, but no such point was apparent. Lack of temperatures above 21° C, together with the small overall thermal range, is thought responsible.     

Novel 2D and 3D multiple-quantum bi-directional HCNCH experiments for the correlation of ribose and base protons/carbons in 13C/15N labeled RNA

Multiple-quantum 2D and 3D bi-directional HCNCH experiments are presented for the correlation of base and ribose protons/carbons in ¹³C/¹⁵N labeled HIV-1 TAR RNA. In both 2D and 3D experiments, the magnetization of H1 is transferred to H6/H8 and H1 through H1-C1-N1/9-C6/8-H6/8 and H1-C1-N1/9-C1-H1 pathways, and the magnetization of H6/8 is transferred to H1 and H6/8 through H6/8-C6/8-N1/9-C1-H1 and H6/8-C6/8-N1/9-C6/8-H6/8 pathways. Chemical shifts of four different nuclei (H1, C1, C6/8 and H6/8) are sampled in the 2D experiment. The correlation of base and ribose protons/carbons is established by the rectangular arrangement of crossover and out-and-back peaks in the proton/carbon correlated spectrum. The rectangular connections can be further resolved using the nitrogen dimension in a ¹H/¹³C/¹⁵N 3D experiment. Furthermore, by taking advantage of the well separated chemical shifts of N1 (pyrimidine) and N9 (purine), the 2D spectrum can be simplified into two sub-spectra based on their base type. Both experiments were tested on a ¹³C/¹⁵N labeled 27-mer HIV-1 TAR RNA containing a UUCG hairpin loop.     

Inverse relationship between poly (ADP-ribose) polymerase activity and 2′,5′-oligoadenylates core level in estrogen-treated immature rat

Summary The activity of poly (ADP-ribose) polymerase (ADPRP) and the content of 2,5-oligodenylates core (2,5A_n; n = 2,3 and 4) were measured in homogenates of the uterus and of the liver of immature rats immediately before (time 0) or at different times after injection of estradiol-valerate. ADPRP activity increased gradualy, starting 6 hours after estrogen injection, for about 4 days. Instead, the content of 2,5 A_n decreased by about 50% within 6 hours, and thereafter more slowly for 4 days to about 20% of starting values. Estrogen increased ADPRP activity and decreased 2,5A_n concentration also in the kidney and in the cardiac muscle of the same animals, but not in the skeletal muscle, where neither of the two parameters was affected. Injection of vehicle only (sesame oil) had no effect on ADPRP activity nor on 2,5A_n content of immature rat tissues.     

Carotenoid pigments of Sorangium compositum (Myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides

Summary The carotenoid pigments of the myxobacterium Sorangium compositum were analyzed by chromatographical and chemical techniques and by visible, infra red, and mass spectroscopy. Besides -carotene, neurosporene, torulene, lycopene, and 1,2-dihydro-1-hydroxy--carotene, four new carotenoid glycosides were found. These pigments were identified as 1,2-dihydro-1-hydroxy-torulene glucoside ester (I), 1,2-dihydro-3,1-dihydroxy-torulene glucoside ester (III), 1,2-dihydro-1-hydroxy-torulene rhamnoside (II), and 1,2-dihydro-3,1-dihydroxytorulene rhamnoside (IV).Fifth communication on the carotenoids of myxobacteria. Fourth communication see Arch. Mikrobiol. 76, 364–380 (1971).     

Physical properties and metabolite regulation of ribulose bisphosphate carboxylase from Thiobacillus A2

Purified ribulose-bisphosphate carboxylase (EC 4.1.1.39) was strongly and equally inhibited either by ADP or GDP and to a lesser extent by IDP. AMP or ATP exerted little effect on activity. Inhibition by the nucleotide diphosphates was competitive with respect to RuBP and non-competitive with respect to CO₂ and Mg²⁺, respectively. Treatment of the enzyme with urea or guanidine-HCl resulted in rapid loss of activity that was not restored by dialysis even in the presence of Mg²⁺ and cysteine. Sodium dodecyl sulfate electrophoresis of 8.0 M urea treated enzyme revealed the presence of a fast-moving (small) sub-unit with molecular weight 14150 and a slower moving (large) sub-unit with molecular weight 68000. Examination of native enzyme by sodium dodecyl sulfate electrophoresis gave sub-units of 13700 and 55500 respectively. The amino acid content standardized to phenylalanine was essentially similar to that from other sources. Arrhenius plots showed a break at 29°C with an E _a of 12.34 kcal per mole for the steeper part of the curve and a H of 11.43 kcal per mole while for the less steep region, the E _a was 1.04 kcal per mole and the H 1.92 kcal per mole.Abbreviations ADP adenosine-5-diphosphate - AMP adenosine-5-monophosphate - ATP adenosine-5-triphosphate - CDP cytidine-5-diphosphate - CMP cytidine-5-monophosphate - CTP cytidine-5-triphosphate - FDP fructose-1,6-diphosphate - F6P fructose-6-phosphate - GDP guanosine-5-diphosphate - GMP guanosine-5-monophosphate - G6P glucose-6-phosphate - GTP guanosine-5-triphosphate - IDP inosine-5-diphosphate - IMP inosine-5-monophosphate - PEP phosphoenolpyruvate - 6PG 6-phosphogluconate - R1P ribose-1-phosphate - R5P ribose-5-phosphate - RuBP ribulose-1,5-bisphosphate - SDS sodium dodecyl sulfate - TDP thymidine-5-diphosphate - TMP thymidine-5-monophosphate - TTP thymidine-5-triphosphate - UDP uridine-5-diphosphate - UMP uridine-5-monophosphate - UTP uridine-5-triphosphate     

Oligomerization reactions of deoxyribonucleotides on montmorillonite clay: The effect of mononucleotide structure,phosphate activation and montmorillonite composition on phosphodiester bond formation

2-d-5-GMP and 2-d-5-AMP bind 2 times more strongly to montmorillonite 22A than do 2-d-5-CMP and 5-TMP. The dinucleotide d(pG)₂ forms in 9.2% yield and the cyclic dinucleotide c(dpG)₂ in 5.4% yield in the reaction of 2-d-5-GMP with EDAC in the presence of montmorillonite 22A. The yield of d(pC)₂ (2.0%) is significantly lower but comparable to that obtained from 5-TMP. The yield of dimers which contain the phosphodiester bond decreases as the reaction medium is changed from 0.2 M NaCl to a mixture of 0.2 M NaCl and 0.075 M MgCl₂. A low yield of d(pA)₂ was observed in the condensation reaction of 5-ImdpA on montmorillonite 22A. The cyclic nucleotide (3,5-cdAMP) was obtained in 14% yield from 3-ImdpA. The yield of d(pA)₂ obtained when EDAC is used as the condensing agent increases with increasing iron content of the Na⁺-montmorillonite used as catalyst. Evidence is presented which shows that the acidity of the Na⁺-montmorillonite is a necessary but not sufficient factor for the montmorillonite catalysis of phosphodiester bond formation.     

A novel PH-CT-COSY methodology for measuring JPH coupling constants in unlabeled nucleic acids. Application to HIV-2 TAR RNA

A quantitative analysis of J_PH scalar couplings in nucleic acids is difficult due to small couplings to phosphorus, the extreme overlap of the sugar protons and the fast relaxation of the spins involved in the magnetization transfer. Here we present a new methodology that relies on heteronuclear Constant Time Correlation Spectroscopy (CT-COSY). The three vicinal ³J_PH3, ³J_PH5 and ³J_PH5 scalar couplings can be obtained by monitoring the intensity decay of the P_i-H3_{i – 1} peak as a function of the constant time T in a 2D correlation map. The advantage of the new method resides in the possibility of measuring the two ³J_PH5 and ³J_PH5 scalar couplings even in the presence of overlapped H5/H5 resonances, since the quantitative information is extracted from the intensity decay of the P-H3 peak. Moreover, the relaxation of the H3 proton is considerably slower than that of the H5/H5 geminal protons and the commonly populated conformations of the phosphate backbone are associated with large ³J_PH3 couplings and relatively small ³J_{PH5 / H5}. These two facts lead to optimal signal-to-noise ratio for the P-H3 correlation compared to the P-H5/H5 correlation.The heteronuclear CT-COSY experiment is suitable for oligonucleotides in the 10–15 kDa molecular mass range and has been applied to the 30mer HIV-2 TAR RNA. The methodology presented here can be used to measure P-H dipolar couplings (D_PH) as well. We will present qualitative results for the measurement of P-H_base and P-H2 dipolar couplings in the HIV-2 TAR RNA and will discuss the reasons that so far precluded the quantification of the D_PHs for the 30mer RNA.     

The structure of the incompatibility factors of Schizophyllum commune: Constitution of the three classes of B factors

Summary The B factors of Schizophyllum commune are of 3 classes: The high recombining class I has 7 alleles and 7 alleles; the low recombining classes are class II with 7 allels and probably 2 alleles and class III with probably 2 (or also 2) alleles and 7 allels. A fourth hypothetical class (-) was not found and either does not exist or is indistinguishable from class III by the tests employed. The and alleles differ from and by either (a) mutations affecting both mating specificity and recombination frequency, or (b) deletions involving most of the B region.The research was supported by a grant from the Atomic Energy Commission of the U.S. No. (30-1)-3875 and was performed at the Biological Laboratories, Harvard University, Cambridge, Mass., U.S.A.     

Adenosine-5′-phosphosulfate (APS) as sulfate donor for assimilatory sulfate reduction in Rhodospirillum rubrum

Crude extracts of Rhodospirillum rubrum catalyzed the formation of acid-volatile radioactivity from (³⁵S) sulfate, (³⁵S) adenosine-5-phosphosulfate, and (³⁵S) 3-phosphoadenosine-5-phosphosulfate. An enzyme fraction similar to APS-sulfotransferases from plant sources was purified 228-fold from Rhodospirillum rubrum. It is suggested here that this enzyme is specific for adenosine-5-phosphosulfate, because the purified enzyme fraction metabolized adenosine-5-phosphosulfate, however, only at a rate of 1/10 of that with adenosine-5-phosphosulfate. Further, the reaction with 3-phosphoadenosine-5-phosphosulfate was inhibited with 3-phosphoadenosine-5-phosphate whereas this nucleotide had no effect on the reaction with adenosine-5-phosphosulfate. For this activity with adenosine-5-phosphosulfate the name APS-sulfotransferase is suggested. This APS-sulfotransferase needs thiols for activity; good rates were obtained with either dithioerythritol or reduced glutathione; other thiols like cysteine, 2-3-dimercaptopropanol or mercaptoethanol are less effective. The electron donor methylviologen did not catalyze this reaction. The pH-optimum was about 9.0; the apparent K _m for adenosine-5-phosphosulfate was determined to be 0.05 mM with this so far purified enzyme fraction. Enzyme activity was increased with K₂SO₄ and Na₂SO₄ and was inhibited by 5-AMP. These properties are similar to assimilatory APS-sulfotransferases from spinach and Chlorella.Abbreviations APS adenosine-5-phosphosulfate - PAPS 3-phosphoadenosine-5-phosphosulfate - 5-AMP adenosine-5-monophosphate - 3-AMP adenosine-3-monophosphate - 3-5-ADP 3-phosphoadenosine-5-phosphate (PAP) - DTE dithiorythritol - GSH reduced glutathione - BAL 2-3-dimercaptopropanol     

Template-directed reactions of aminonucleosides

Summary We have studied the reactions between adenosine 5-phosphorimidazolide and 9-(2-amino-2-deoxyxylofuranosyl) adenine (I) or 3-methylamino-3-deoxyadenosine (II), both with and without a poly (U) template. We find that both amino compounds react much more rapidly than does adenosine, in the absence of a template. The rate of reaction is greatly enhanced by a poly (U) template in the case of I, but the enhancement is slight in the case of II.Abbreviations A adenosine - xylo A_NH2 9-(2-amino-2-deoxy--D-xylofuranosyl) adenine - A_NHMe 3-methylamino-3-deoxyadenosine - ImpA adenosine 5-phosphorimidazolide - A³ pA adenylyl-[35]-adenosine - A² pA adenylyl-[25]-adenosine - U_NPA adenylyl-[52]-2-amino-2-deoxyuridine - xylo A_NPA 9-[adenylyl-(52)-2-amino-2-deoxy--D-xylofuranosyl]adenine - A_(NMe)pA adenylyl-[53]-3-methylamino-3-deoxyadenosine - pA adenosine 5phosphate - AppA P₁, P₂-diadenosine 5pyrophosphate - (pA)_n n = 2, 3 [2-5]-linked oligomers of pA - A² pA² pA [2-5]-linked trinucleoside diphosphate of A - poly (U) polyuridylic acid     

Effects of midazolam on the contraction and relaxation of segments of thoracic aorta stripped of endothelium and stimulated by adrenaline – experimental study in rabbits

To evaluate the effects of midazolam on the angiokinesis of segments of rabbits' thoracic aorta stripped of endothelium and stimulated by adrenaline.Two groups of aortic rings removed from albinic rabbits anesthetized with thiopental were used (Group I – 6 animals; Group II – 12 animals), stripped of endothelium, studied in an organ chamber, perfused by Krebs-Henseleit solution. The groups were stimulated by adrenaline, recording the maximum contraction and dT/dt at 12, 36, 60 and 120. When the plateau phase was reached, the vessel was washed with perfusion solution, recording relaxation at 2, 4 and 6. When the base values were reached, Group I underwent a new adrenergic stimulus; and Group II was stimulated with midazolam and then with adrenaline, and the same values were recorded. T test was applied as a statistical analysis when two variables were studied. When studying more than two variables the Anova test was used, supplemented by the Tuckey test.Group I did not show any significant difference between the two stimuli. Group II – the midazolam significantly reduced the maximum contraction induced by adrenaline (83.01 ± 4.11%) (p < 0.01). The dT/dt was reduced at 12 (57.06 ± 8.47%), and also at 36 (70.59 ± 5.26%). There was no significance at 60 and 120 (p < 0.01).The relaxation increased significantly at all measurements – at 2-adrenaline 39.31 ± 9.60%; adrenaline/midazolam: 44.06 ± 9.62% (p < 0.05). At 4-adrenaline: 53.08 ± 8.3%; adrenaline/midazolam: 61.68 ± 8.50% (p < 0.01). At 6-adrenaline: 76.26 ± 5.45%; adrenaline/midazolam: 84.20 ± 7.96% (p < 0.01).Midazolam significantly reduced the maximum contraction obtained by the adrenergic stimulus as well as the dT/dt in the initial phases of contraction. The relaxation speed also increased.     

Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

In vitro investigation of α-amylase release from the digestive cells of the bivalve mollusc Pecten maximus: effect of second messengers and biogenic amines

The (neuro)endocrine control of enzyme release from invertebrate digestive cells remains poorly understood. A tissue dissociation procedure was developed to investigate the regulatory mechanisms of -amylase discharge from the cells of the stomach-digestive gland complex of the scallop Pecten maximus. The validity of the experimental system was tested by increasing the intracellular concentration of second messenger analogues (N ⁶,2-o-dibutyryl-adenosine-3,5 cyclic monophosphate and the ionophore A23187) known to mimic the activity of naturally occurring secretagogues in vertebrates: N ⁶,2-o-dibutyryl-adenosine-3,5 cyclic monophosphate increased the time and dose-dependent release of -amylase in a similar way as in vertebrates. A23187 was also very effective in inducing enzyme discharge. Since the in vitro bioassay was shown to be functional and because axon terminals were previously seen in close contact to -amylase secreting cells, the effect of some classic neurotransmitters was explored. Only the cholinergic agonist carbachol and dopamine evoked a secretory response. Maximal stimulation of -amylase release was reached at 10^-5 mol·l^-1 carbachol; at the same concentration dopamine was less effective than carbachol. By contrast, serotonin was totally inactive. The in vitro bioassay should prove useful for the identification of regulatory molecules involved in the control of enzyme discharge and to study stimulus secretion coupling mechanisms in scallop digestive cells.Abbreviations DBcAMP N ⁶, 2-O-dibutyryl-adenosine-3,5 cyclic monophosphate - cAMP adenosine-3,5 cyclic monophosphate     

Monomers for Oligonucleotide Synthesis with Linkers Carrying Reactive Residues: II. The Synthesis of Phosphoamidites on the Basis of Uridine and Cytosine and Containing a Linker with Methoxyoxalamide Groups in Position 2′

A convenient preparative synthesis of 2-amino-2-deoxyuridine was developed. Starting from 2-amino-2-deoxyuridine and 2-amino-2-deoxycytidine, monomers for the phosphoamidite oligonucleotide synthesis were obtained that carry a linker with methoxyoxalamide groups in position 2.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Geometry of the dry-state oligomerization of 2′,3′-cyclic phosphates

Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE 1,2-diaminoethane - HPLC high pressure liquid chromatography - RNase bovine pancreatic ribonuclease A, EC 3.1.4.22 - TEAB triethylammonium bicarbonate - tris tris(hydroxymethyl)aminomethane - UMP(S) uridine monophosphorothioate - U > p uridine cyclic 2,3-phosphate - U > p(S) uridine cyclic 2,3-O, O-phosphorothioate - Up(S)dT (P-thio)uridylylthymidine - U2p(R_p-S)5dT (P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage     

Cleavage of nucleotides by Ce4+ and the lanthanide metal complexes

The cleavage of adenosine-5-monophosphate (5-AMP) and guanosine-5-monophosphate (5-GMP) by Ce⁴⁺ and lanthanide complex of 2-carboxyethylgermanium sesquioxide (Ge-132) in acidic and near neutral conditions was investigated by NMR , HPLC and measuring the liberated inorganic phosphate at 37°C and 50°C. The results showed that 5-GMP and 5-AMP was converted to guanine (G), 5-monophosphate (depurination of 5-GMP), ribose (depurination and dephosphorylation of 5-GMP), phosphate and adenine (A), 5-monophosphate (depurination of 5-AMP), ribose (depurination and dephosphorylation of 5-AMP), phosphate respectively by Ce⁴⁺. In presence of lanthanide complexes, 5-GMP and 5-AMP were converted to guanosine (Guo) and phosphate and adenosine (Ado) and phosphate respectively. The mechanism of cleaving 5-GMP and 5-AMP is hydrolytic scission     

Synthesis of oligoguanylates on oligocytidylate templates

Summary Short oligocytidylates can act as templates for the self-condensation of guanosine 5-phosphorimidazolide. In the absence of a catalytic metal ion or in the presence of Pb²⁺ a noticeable template effect is already observed with the dimer and the yield of long oligomers reaches a plateau with a hexamer template. Short templates give oligomers longers than the template length. The products are predominantly 2-5 linked for the Pb²⁺-catalyzed reaction while mixed linkages are observed in the uncatalyzed reaction.In the presence of Zn²⁺, a template effect is first observed with the pentamer and is maximal by the heptamer. The products are predominantly 3-5 linked. Oligomers shorter than or as long as the template are obtained in substantial yield, and longer products in much lower yields.Abbreviations G Guanosine - Gp guanosine 2(3)-phosphate - pG guanosine 5-phosphate - Gp! guanosine cyclic 2,3-phosphate - ImpG guanosine 5-phosphorimidazolide - ImpG^* [8-¹⁴C]-guanosine 5-phosphorimidazolide - pGp 5-phosphoguanosine 2(3)-phosphate - G²pG guanylyl-[2-5]-guanosine - G³pG guanylyl-[3-5]-guanosine - ImpGpG 5-phosphorimidazolide of GpG - (pG)_n (n = 2,3) oligomers of pG - GppG P₁, P₂-diguanosine 5-diphosphate - GppGpG 5-[guanosine 5-pyrophosphate] of GpG - NH₂pG guanosine 5-phosphoramidate - (pG)₄₊ tetramer and higher oligoguanylates with 5 terminal phosphate - oligo(G) oligoguanylate - Cp cytidine 2(3)-phosphate - Cp! cytidine cyclic 2,3-phosphate - (Cp)_n–1 Cp! (n= 2,3,4) oligocytidylates terminated by 5-OH groups and 2,3-cyclic phosphates - oligo(C) oligocytidylate - poly(C) polycytidylic acid - poly(U) polyuridylic acid - poly(C,G) random copolymer of C and G - BAP bacterial alkaline phosphatase (E. coli) - EDTA ethylenediaminetetraacetic acid - R_f chromatographic mobility     

Den 1, Den2 and Den3, ATP-inhibited deoxyribonucleases from Dropsophila embryonic nuclei

Three Drosophila embryonic deoxyribonucleases, designated den1, den2 and den3, are identified in nuclear extracts separated by glycerol density gradient centrifugation. Den1, removes short products from the 5-ends of single-stranded DNA or double-stranded DNA with either blunt or 5-recessed termini. Den2 is inactive with single-stranded DNA and acts as 3-exonuclease with double-stranded DNA possessing either blunt or 3-recessed termini. Den3 preferentially uses partial duplex DNA containing single-stranded gap and it catalyzes hydrolysis, in 3-5 direction, of one of the shorter strands that flank the gap. Nucleolytic activities of den1, den2 and den3 are inhibited with ATP.     

Inheritance of callus formation ability in anther cultures of rice,Oryza sativa L.

Summary Inheritance of ability to form callus in rice anther culture was studied using the diallel technique. Anthers containing uninucleate microspores from two japonica cultivais (Minehikari and Taipei 309), two indica cultivars (Mingolo and Suweon 290), and 12 F₁'s of the diallel crosses involving these four parents were cultured on Chaleffs R₂ medium and evaluated for callus induction. The parents showed significant differences in anther callus formation, from 41.9% (Taipei 309) to 0% (Suweon 290). Callus induction ability was inherited as a recessive character conditioned by a single block of genes. Additive gene effects were predominant. The japonica types seemed to be good combiners for callus induction. The order of dominance among the four parents was Suweon 290, Mingolo, Minehikari and Taipei 309.