Activation mechanism of tris(2,3-dibromopropyl)phosphate to the potent mutagen, 2-bromoacrolein

The potent mutagen 2- bromoacrolein is formed from the carcinogenic flame retardant tris(2,3-dibromopropyl)phosphate (Tris-BP) on incubation with hepatic microsomes. Substitution of deuterium for hydrogen at the terminal carbon atoms (C-3) of Tris-BP significantly decreased both the mutagenic response and the formation rate of 2- bromoacrolein . Mass spectral analysis of the 2- bromoacrolein that was formed from the selectively deuterated analogs of Tris-BP revealed that the primary mechanism for the formation of 2- bromoacrolein involves an initial oxidative dehalogenation at C-3 followed by a beta-elimination reaction.     

A portable DNA sequence carrying the cohesive site (cos) of bacteriophage lambda and the mob (mobilization) region of the broad-host-range plasmid RK2: a module for the construction of new cosmids

A polylinker DNA sequence carrying the cos site of bacteriophage lambda and the mob (oriT) region of the IncP group plasmid RK2 was constructed. This composite polylinker has EcoRI sites at both termini and also unique sites for ClaI, HindIII, PstI and XbaI. The cos-mob region is portable with the use of EcoRI or a combination of EcoRI with ClaI, HindIII or XbaI. Another cos-mob cassette was also constructed from which the cos-mob region can be lifted with HindIII, ClaI or either of these enzymes in combination with others. These cos-mob cassettes can be used in constructing new cosmids that can be mobilized into a variety of Gram-negative bacteria. Using one of these cassettes we have constructed a small IncW group cosmid (11.1 kb) that was mobilizable into Escherichia coli, Rhizobium spp. and Alcaligenes eutrophus at high frequency.     

Oxidant effect of acetylphenylhydrazine: a comparative study with erythrocytes of several animal species.

Red cells from several animal species were treated with acetylphenylhydrazine and a comparative study of the oxidation of hemoglobin (Hb) and glutathione (GSH) made. Wide interspecies differences were observed but the oxidation of GSH paralleled that of Hb. Added glucose protected both Hb and GSH from oxidation; GSH by itself exercises a protective effect on Hb. The characteristic rates of oxidation of GSH in the different species can be observed only in the presence of oxyhemoglobin but not carboxyhemoblobin or methemoglobin. The oxidation of Hb appears to be the primary event, the oxidation of GSH being a consequence thereof.     

Parasites,predators and other arthropods associated withMusca domestica and other flies breeding in bovine manure

The species of flies breeding in bovine manure, their parasites and predators as well as other associated arthropods in 3 localities in and near Bangalore are recoreded. The flies areMusca domestica L.,Musca pattoni Austen,Stomoxys calcitrans L.,Physiphora aenea F.,Physiphora demandata F.,Sargus metallinus F.,Sepsis thoracica R.-D.,Sepsis nitens Wiedemann,Sphaerocera scabricula Hal, andLeptocera (Coproica) hirtula Rondani. Four species of hymenopterous pupal parasites of these flies have been obtained:Spalangia cameroni Perkins from pupae ofM. domestica, M. pattoni, S. calcitrans, P. aenea andP. demandata; Spalangia endius Walker from pupae ofM. domestica, M. pattoni andS. calcitrans; Spalangia nigroaenea Curtis from pupae ofM. domestica andS. calcitrans; andDirhinus trichiophthalmus Masi from pupae ofSargus metallinus F. Percentage parasitism of fly puparia in field samples was noted. Four species ofHister andAleochara puberula Klug feeding on various immature stages ofM. domestica, 2 species of scarabaeid beetles, 2 species of ants and a pseudoscorpion were also found in the manure. The importance of biotic regulatory factors in the control of flies is discussed.

---

Résumé Dans 3 localités de Bangalore ou proches de cette ville, on a inventorié les espèces de mouches vivant dans le fumier de vache, leurs parasites et prédateurs ainsi que d'autres arthropodes associés. Les mouches récoltées sont:Musca domestica L.,Musca pattoni Austen,Stomoxys calcitrans L.,Physiphora aenea F.,Physiphora demandata F.,Sargus metallinus F.,Sepsis thoracica R-D.,Sepsis nitens Wiedemann,Sphaerocera scabricula Hal. etLeptocera (Coproica) hirtula Rondani. Quatre espèces d'hyménoptères parasites des pupes ont été obtenues de ces mouches:Spalangia cameroni Perkins deM. domestica, M. pattoni, S. calcitrans, P. aenea etP. demandata: Spalangia endius Walker deM. domestica, M. pattoni etS. calcitrans, P. aenea etP. demandata; Spalangia endius Walker trans; etDirhinus trichiophthalmus Masi deSargus metallinus F. On a noté le taux de parasitisme des nymphes dans les conditions naturelles. Quatre espèces deHister etAleochara puberula Klug s'attaquant aux divers stades non imaginaux deM. domestica, 2 espèces de scarabeides, 2 espèces de fourmis et un pseudoscorpion ont été également trouvés dans le fumier. L'importance de ces facteurs biotiques dans la régulation des populations de mouches est discutée.

---

---

Paper presented at the seminar on utilization of farm wastes for rural industrial growth, National Dairy Research Institute, Bangalore, 31 st December, 1975.

---

This paper is published with the permission of the Director-General, Indian Council of Medical Research, New Delhi     

Effect of oilseed cakes on alpha-amylase production by Bacillus licheniformis CUMC305.

The effects of oilseed cakes on extracellular thermostable alpha-amylase production by Bacillus licheniformis CUMC305 was investigated. Each oilseed cake was made of groundnut, mustard, sesame, linseed, coconut copra, madhuca, or cotton. alpha-Amylase production was considerably improved in all instances and varied with the oilseed cake concentration in basal medium containing peptone and beef extract. Maximum increases were effected by a low concentration (0.5 to 1.0%) of groundnut or coconut, a high concentration (3%) of linseed or mustard, and an Rintermediate concentration (2%) of cotton, madhuca, or sesame. The oilseed cakes made of groundnut or mustard could completely replace the conventional peptone-beef extract medium as the fermentation base for the production of alpha-amylase by B. licheniformis. The addition of corn steep liquor to cotton, linseed, sesame, or madhuca cake in the medium improved alpha-amylase production.     

Sequence homology between Inc N group plasmids

DNA-DNA hybridization combined with "Southern blotting" was used to analyse the genetic organization and the nucleotide sequence homology between different regions of a previously characterized Inc N group plasmid pCUI and nine other Inc N group plasmids. The following conclusions could be reached: (1) N plasmids isolated from different parts of the world share substantial DNA sequence homology and also some similarity of overall genetic organization, (2) the majority of the N plasmids used in this study showed conservation of distribution of BglII and KpnI cleavage sites. Often, restriction endonuclease fragments of similar electrophoretic mobility encoded the same genetic function, (3) in one case, the N-specific properties appear to be integrated into the bacterial chromosome. (4) the plasmid DNA in strains carrying two Inc N plasmids, R199 and R113 were each composed of two molecular species only one of which constituted an N group plasmid.     

Sequence and analysis of the nodABC region of Rhizobium fredii USDA257, a nitrogen-fixing symbiont of soybean and other legumes.

We cloned and analyzed nodABC from Rhizobium fredii USDA257. These genes are thought to have common functions in initiation of nitrogen-fixing nodules by all rhizobia. In USDA257, they were located in a 9.2-kb EcoRI fragment that was not closely linked to either of two copies of the regulatory gene, nodD. nodABC was present in a 3,094-base pair (bp) sequenced region, which also included a consensus nod-box promoter. The three open reading frames contained 654, 642, and 1,239 bp, respectively, and encoded deduced proteins of 21.9, 23.4, and 44.7 kD. The sequence of the nodABC region of USDA257 was generally homologous with corresponding regions from other rhizobia, but it diverged significantly in the 5' non-translated region and in the 3'terminus of nodC. nodC was not translationally coupled to nodSU, as in another soybean symbiont, Bradyrhizobium japonicum, and the deduced NodC protein was the shortest of any such proteins yet described. Site-directed mutagenesis of the 9.2-kb EcoRI fragment confirmed that nodA, nodB, and nodC are essential for nodulation of soybean, but failed to identify other linked nod genes. Daidzein, a major isoflavone from soybean roots, was the most potent of nine tested flavonoids in activating a plasmid-borne nodC::lacZ fusion. The 9.2-kb fragment complemented nodA-, nodB-, and nodC- mutants of R. meliloti to the Nod+ phenotype on Medicago sativa, M. truncatula, and Trigonella foenum-graecum. Nodule numbers, percentage of nodulated plants, and shoot dry weights, however, were considerably less than in plants inoculated with mutants complemented with nodABC from R. meliloti.     

Sequence-specific 1H NMR assignments and secondary structure in solution of Escherichia coli trp repressor

Sequence-specific 1H NMR assignments are reported for the active L-tryptophan-bound form of Escherichia coli trp repressor. The repressor is a symmetric dimer of 107 residues per monomer; thus at 25 kDa, this is the largest protein for which such detailed sequence-specific assignments have been made. At this molecular mass the broad line widths of the NMR resonances preclude the use of assignment methods based on 1H-1H scalar coupling. Our assignment strategy centers on two-dimensional nuclear Overhauser spectroscopy (NOESY) of a series of selectively deuterated repressor analogues. A new methodology was developed for analysis of the spectra on the basis of the effects of selective deuteration on cross-peak intensities in the NOESY spectra. A total of 90% of the backbone amide protons have been assigned, and 70% of the alpha and side-chain proton resonances are assigned. The local secondary structure was calculated from sequential and medium-range backbone NOEs with the double-iterated Kalman filter method [Altman, R. B., & Jardetzky, O. (1989) Methods Enzymol. 177, 218-246]. The secondary structure agrees with that of the crystal structure [Schevitz, R., Otwinowski, Z., Joachimiak, A., Lawson, C. L., & Sigler, P. B. (1985) Nature 317, 782], except that the solution state is somewhat more disordered in the DNA binding region and in the N-terminal region of the first alpha-helix. Since the repressor is a symmetric dimer, long-range intersubunit NOEs were distinguished from intrasubunit interactions by formation of heterodimers between two appropriate selectively deuterated proteins and comparison of the resulting NOESY spectrum with that of each selectively deuterated homodimer. Thus, from spectra of three heterodimers, long-range NOEs between eight pairs of residues were identified as intersubunit NOEs, and two additional long-range intrasubunits NOEs were assigned.     

Condensation of chromatin into chromosomes preserves an open configuration but alters the DNase I hypersensitive cleavage sites of the transcribed gene

DNase I was used to probe the molecular organization of the chicken ovalbumin (OV) gene and glyceraldehyde 3-phosphate dehydrogenase (GPD) gene in interphase nuclei and in metaphase chromosomes of cultured chicken lymphoblastoid cells (MSB-1 line). The OV gene was not transcribed in this cell line, whereas the GPD gene was constitutively expressed. The GPD gene was more sensitive to DNase I digestion than the OV gene in both interphase nuclei and metaphase chromosomes, as determined by Southern blotting and liquid hybridization techniques. In addition, we observed DNase I hypersensitive sites around the 5' region of the GPD gene. These hypersensitive sites were not always at the same locations between the interphase nuclei and metaphase chromosomes. Our results suggest that chromatin condensation and decondensation during cell cycle alters nuclease hypersensitive cleavage sites.