Interactions of rhizobia with rice and wheat

Recently, evidence has been obtained that naturally occurring rhizobia, isolated from the nodules of non-legume Parasponia species and from some tropical legumes, are able to enter the roots of rice, wheat and maize at emerging lateral roots by crack entry. We have now investigated whether Azorhizobium caulinodans strain ORS571, which induces root and stem nodules on the tropical legume Sesbania rostrata as a result of crack entry invasion of emerging lateral roots, might also enter rice and wheat by a similar route. Following inoculation with ORS571 carrying a lacZ reporter gene, azorhizobia were observed microscopically within the cracks associated with emerging lateral roots of rice and wheat. A high proportion of inoculated rice and wheat plants had colonized lateral root cracks. The flavanone naringenin at 10 and 10 M stimulated significantly the colonization of lateral root cracks and also intercellular colonization of wheat roots. Naringenin does not appear to be acting as a carbon source and may act as a signal molecule for intercellular colonization of rice and wheat by ORS571 by a mechanism which is nod gene-independent, unlike nodule formation in Sesbania rostrata. The opportunity now arises to compare and to contrast the ability of Azorhizobium caulinodans with that of other rhizobia, such as Parasponia rhizobia, to intercellularly colonize the roots of non-legume crops.     

Diet of bluegill Lepomis macrochirus in a South African reservoir during winter and summer

Alien fishes are considered a major threat to aquatic biodiversity in South Africa, yet relatively little regional information on their biology and ecology is available for many of these species. Seasonal changes in the diet of the bluegill Lepomis macrochirus in Howieson’s Poort Dam, Grahamstown, were assessed during summer and winter in 2014–2015, using stomach content analysis. In winter, juvenile and adult fish diets were dominated by crustacean zooplankton and insects, respectively. In summer, juvenile fish fed on crustaceans and insects, whereas adults consumed mostly fish eggs, indicating a potential impact by these invasive fish on native fish through oophagy.     

A novel Atg5-shRNA mouse model enables temporal control of Autophagy in vivo

Macroautophagy/autophagy is an evolutionarily conserved catabolic pathway whose modulation has been linked to diverse disease states, including age-associated disorders. Conventional and conditional whole-body knockout mouse models of key autophagy genes display perinatal death and lethal neurotoxicity, respectively, limiting their applications for in vivo studies. Here, we have developed an inducible shRNA mouse model targeting Atg5, allowing us to dynamically inhibit autophagy in vivo, termed ATG5i mice. The lack of brain-associated shRNA expression in this model circumvents the lethal phenotypes associated with complete autophagy knockouts. We show that ATG5i mice recapitulate many of the previously described phenotypes of tissue-specific knockouts. While restoration of autophagy in the liver rescues hepatomegaly and other pathologies associated with autophagy deficiency, this coincides with the development of hepatic fibrosis. These results highlight the need to consider the potential side effects of systemic anti-autophagy therapies.     

Generation and characterization of an HLA-DRα-specific monoclonal antibody using L-cell transfectants expressing human and mouse class II major histocompatibility dimers

Among the HLA-DR-specific monoclonal antibodies (mAbs) that have been characterized previously, there is a marked shortage of DR chain-specific mAbs which stain unfixed cells. This may result from the high degree of sequence similarity between the ₁ domains of HLA-DR and H-2E leading to a state of cross-tolerance to DR in H-2-expressing mice. BALB/b (E-negative) mice were immunized with DR1-transfected mouse L cells. The chain specificity of the resulting DR-specific mAb was determined using a panel of transfectants expressing hybrid mouse/human class II heterodimers. A DR-specific mAb was generated which was capable of immunoprecipitating DR dimers and inhibiting the anti-DR alloresponse of human T-cell clones. The present study demonstrates that, with the selection of suitable recipient strain, transfectants can be useful in the generation and definition of chain-specific mouse mAbs.     

Family study of the major histocompatibility complex in patients with systemic lupus erythematosus: importance of null alleles of C4A and C4B in determining disease susceptibility.

The families of 29 patients with systemic lupus erythematosus and 42 normal subjects were studied to determine the inheritance of the HLA-A, B, C, and DR antigens and also the complement polymorphisms for C2, C4A, C4B, and Bf, which are encoded in the same region of the sixth chromosome. Null (silent) alleles for C4A, C4B, or C2 were found in 24 of the 29 (83%) patients compared with 18 of the 42 (43%) normal controls. HLA-DR3 was present in 20 (69%) of the patients and seven out of 39 (18%) of the normal controls. There was strong linkage disequilibrium between DR3 and the null alleles for C4A and C4B. The data did not permit the relative contributions of DR3 and null factors of C4A and C4B as genetic risk factors to be distinguished. The known association of systemic lupus erythematosus with uncommon inherited and acquired deficiencies of complement components suggests, however, that the presence of null alleles for C4A and C4B, as well as C2, found in most of the patients, is relevant to their genetic susceptibility to this disease.     

Nurse practitioners in primary care iv. Impact of an interdisciplinary team on attitudes of a rural population.

Attitudes toward the expanded role of nurse practitioners in primary care (family practice nurses) have been determined for persons from a semirural area who chose as their principal souce of care an interdisciplinary family medical centre (FMC) incorporating two nurse practitioners, and those for whom the FMC was not the usual source of care. Data were obtaine using"before-and-after" structured interviews of a random sample of persons living in a southern Ontario township. Slowly evolving, nonsignificant trends of greater acceptance were observed among patiens who had dealth with family practice nurses. The greatest change observed was an increased acceptance of the nnurse by FMC users as the person who would be contacted as a second choice if theirfirst choice, usually a physician, could not be reached in specific worrry-inducing situations. FMC users depended more on nurses to provide information. A conclusion of increased general acceptance of the family practive nurse by FMC users is supported by a 34 per cent higher use of nurses by FMC patients compared to other persons of comparable characteristics living in the same community.     

The self-incompatibility phenotype in brassica is altered by the transformation of a mutant S locus receptor kinase

The self-incompatible (SI) Brassica napus line W1, which carries the 910 S allele, was transformed with an inactive copy of the 910 S locus receptor kinase (SRK) gene. Two transformed lines were analyzed based on their heritable ability to set self-seed. The first line was virtually completely self-compatible (SC), and reciprocal pollinations with the original W1 line demonstrated that only the stigma side of the SI phenotype was altered. An analysis of the expression of endogenous SRK-910 demonstrated that the mechanism of transgene action is via gene suppression. Furthermore, the expression of the S locus glycoprotein gene present in the 910 allele (SLG-910), SLG-A10, which is derived from a nonfunctional S allele, and an S locus-related gene were also suppressed. When the transgene was crossed into another SI line carrying the A14 S allele, it was also capable of suppressing the expression of the endogenous genes and of making this line SC. The second transgenic line studied was only partly SC. In this case as well, only the stigma phenotype was affected, although no gene suppression was detected for endogenous SRK-910 or SLG-910. In this line, the expression of the transgene most likely was causing the change in phenotype, and no effect was observed when this transgene was crossed into the other SI line. Therefore, this work reinforces the hypothesis that the SRK gene is required, but only for the stigma side of the SI phenotype, and that a single transgene can alter the SI phenotype of more than one S allele.