Virulence of Agrobacterium tumefaciens strains with Brassica napus and Brassica juncea

Summary Brassica napus and Brassica juncea were infected with a number of Agrobacterium tumefaciens strains. Tumourigenesis was very rapid and extremely efficient on B. juncea with all but one of the strains. Tumourigenesis on B. napus varied widely. It was very efficient with the nopaline strains, was reduced with the succinamopine strain A281 and was very weak with the octopine strains. The latter observation was confirmed with six different B. napus rapeseed cultivars. The selectivity was due to differences in the virulence of Ti plasmids with B. napus, rather than the tumourigenicity of the T-DNA or virulence of the chromosomal genes associated with the strains. An exception was strain LBA4404. The virulence of the octopine strains was increased by coinfection with more virulent disarmed strains and by induction with acetosyringone.     

Effect of soil solarization on nodulation,infection by mycorrhizal fungi and yield of cowpea

Solarization of soil was found beneficial for plant growth in cowpea under field conditions. Root nodulation, infection by mycorrhizal fungi and yield were higher in plants grown in solarized soil. These increases were to the extent of 104.7, 20.0 and 23.7 per cent respectively when compared to control treatment without solarization.     

A causal approach to the study of fertility and familism

This paper tests, within the framework of LISREL, the causal structures of fertility using data from the 1973-74 Growth of Alberta Family Study (GAFS) of women aged 18-44 who are currently married or living common-law. Differential fertility among two groups of women classified by nativity also are examined. The women's background characteristics (e.g., age, religiosity, and education) are viewed as exogenous variables. The endogenous variables are familism and expected family size; familism is designated as an intermediate variable in the model, linking demographic and socioeconomic (including cultural) factors to fertility, The results indicate that familism acts as an important variable explaining fertility, particularly, among foreign-born women. The study confirms and extends earlier research findings that religiosity and education influence couples' fertility, the former positively and the latter negatively.     

Recent developments in in vivo neutron activation analysis facilities

Two new facilities for in vivo activation analysis of patients have been designed, developed, and constructed at Toronto General Hospital. One of these is for the determination of body calcium for the diagnosis of osteoporosis and other diseases associated with bone loss. The other is for the measurement of total body nitrogen for the determination of protein status. These facilities replace old university facilities and take into account the comfort and management of patients. In addition, in the case of the calcium facility, the precision of the measurements has been improved because of larger detector volume and increased neutron source strength. Both the facilities are now in routine hospital clinical use.     

Crystal structures of thrombin with thiazole-containing inhibitors: probes of the S1'' binding site.

Structures of the blood clotting enzyme thrombin complexed with hirugen and two active site inhibitors, RWJ-50353 10080(N-methyl-D-phenylalanyl-N-[5-[(aminoiminomethyl)amino]-1- [[(2-benzothiazolyl)carbonyl]butyl]-L-prolinamide trifluoroacetate hydrate) and RWJ-50215 (N-[4-(aminoiminomethyl)amino-1-[2- (thiazol-2-ylcarbonylethyl)piperidin- 1-ylcarbonyl]butyl]-5-(dimethylamino)naphthalenesulfonamide trifluoroacetate hydrate), were determined by x-ray crystallography. The refinements converged at R values of 0.158 in the 7.0-2.3-A range for RWJ-50353 and 0.155 in the 7.0-1.8-A range for RWJ-50215. Interactions between the protein and the thiazole rings of the two inhibitors provide new valuable information about the S1' binding site of thrombin. The RWJ-50353 inhibitor consists of an S1'-binding benzothiazole group linked to the D-Phe-Pro-Arg chloromethyl ketone motif. Interactions with the S1-S3 sites are similar to the D-phenylalanyl-prolyl-arginyl chloromethylketone structure. In RWJ-50215, a S1'-binding 2-ketothiazole group was added to the thrombin inhibitor-like framework of dansylarginine N-(3-ethyl-1,5-pentanediyl)amide. The geometry at the S1-S3 sites here is also similar to that of the parent compound. The benzothiazole and 2-ketothiazole groups bind in a cavity surrounded by His57, Tyr60A, Trp60D, and Lys60F. This location of the S1' binding site is consistent with previous structures of thrombin complexes with hirulog-3, CVS-995, and hirutonin-2 and -6. The ring nitrogen of the RWJ-50353 benzothiazole forms a hydrogen bond with His57, and Lys60F reorients because of close contacts. The oxygen and nitrogen of the ketothiazole of RWJ-50215 hydrogen bond with the NZ atom of Lys60F.     

Responses of the Circadian Locomotor Activity Rhythm of Mus Booduga to Shifts in LD Schedules

The responses of the field mouse Mus booduga to shifts in schedules of LD cycles were monitored and the results were interpreted with the help of a PRC constructed for the same species. The results reveal that, M. booduga reentrained faster with a lesser number of transients after delay shifts than advance shifts, thus exhibiting “asymmetry effect.” A positive correlation was observed between the number of transients and the number of hours of shift. In most of the shifts, the sign of the transients (negative for delaying transients and positive for advancing transients) coincided with the direction of the shift. Interestingly, 11 and 12 h of advance shifting resulted in delaying transients. An 11-h advance shift can also be interpreted as a 13-h delay. Reentrainment through delaying transients is faster as compared to reentrainment through advancing transients. Thus, this animal might have taken a “shorter route,” as proved by the fact that an 11-h advance shift has evoked delaying transients. But a 13-h advance shift evoked only advancing transients. This prompts us to speculate that there may be a “phase jump” in M. booduga. Further, irrespective of whether L or D has been doubled in a 12-h shift, both evoked only delaying transients.     

AT4 receptor structure-binding relationship: N-terminal-modified angiotensin IV analogues

The effect of structural changes in the N-terminal amino acid of AIV, with respect to AT₄ receptor binding, was examined by competition with [¹²⁵I]AIV in bovine adrenal membranes. Analogues with modifications of the first residue α-amino group possessed lower affinities than the primary amine-containing parent compound. Peptides with a residue 1 α-carbon in the d conformation exhibited poor affinity for the AT₄ receptor. Modifications of the residue 1 R-group demonstrate that a straight chain aliphatic moiety containing four carbons is optimal for receptor-ligand binding, as evidenced by the extremely high affinity of [Nle¹]AIV (K_i = 3.59±0.51 pM). Replacement of the 1–2 peptide bond of AIV with the methylene bond isostere Ψ (CH₂-NH), increased the K_i approximately fivefold, indicating that the peptide bond may be replaced wihle maintaining relatively high-affinity receptor binding.     

AT4 receptor structure-binding relationship: N-terminal-modified angiotensin IV analogues

The effect of structural changes in the N-terminal amino acid of AIV, with respect to AT₄ receptor binding, was examined by competition with [¹²⁵I]AIV in bovine adrenal membranes. Analogues with modifications of the first residue -amino group possessed lower affinities than the primary amine-containing parent compound. Peptides with a residue 1 -carbon in the conformation exhibited poor affinity for the AT₄ receptor. Modifications of the residue 1 R-group demonstrate that a straight chain aliphatic moiety containing four carbons is optimal for receptor-ligand binding, as evidenced by the extremely high affinity of [Nle¹]AIV (K_i = 3.59±0.51 pM). Replacement of the 1–2 peptide bond of AIV with the methylene bond isostere Ψ (CH₂-NH), increased the K_i approximately fivefold, indicating that the peptide bond may be replaced wihle maintaining relatively high-affinity receptor binding.